CN105991498A - Leading symbol generation method and reception method - Google Patents

Abstract

The present invention provides a preamble symbol generation method, a reception method, a generation device, and a reception device, wherein the preamble symbol includes a format control section, and wherein a frequency domain body sequence ZC is generated according to a predetermined sequence generation rule based on a constant envelope zero autocorrelation sequence CAZAC, the predetermined sequence generation rule including: giving different root values to the constant envelope zero autocorrelation sequence CAZAC to generate; and/or giving the constant envelope zero autocorrelation sequence CAZAC the same root value to produce, further carry on the cyclic shift to produce the sequence produced, utilize frequency domain body sequence ZC obtained to transmit the system required signalling, raise the transmission efficiency, further, the first time domain symbol of the format control channel part in the leading symbol can be a known symbol, is used for the initial channel estimation used for coherent detection, can choose the number of symbols in PFC to transmit the required signalling flexibly according to the system need at the same time.

Description

Leading symbol generation method and reception method

technical field

The invention belongs to the field of broadcast communication, and in particular relates to a method for generating and receiving a leading symbol and a corresponding device.

Background technique

At present, the method for realizing time synchronization between the transmitting end and the receiving end in the OFDM system is basically based on preamble symbols. The preamble symbol is a symbol sequence known to both the sender and the receiver of the OFDM system. The preamble symbol marks the beginning of the physical frame (named P1 symbol), and only one P1 symbol or multiple P1 symbols appear consecutively in each physical frame. Symbols, the uses of P1 symbols include:

1) Make the receiving end detect quickly to determine whether the signal transmitted in the channel is the desired signal;

2) Provide basic transmission parameters (such as FFT points, frame type information, etc.), so that the receiving end can perform subsequent receiving processing;

3) Detect the initial carrier frequency offset and timing error, and use it to achieve frequency and timing synchronization after compensation;

4) Emergency alarm or PA system wake up.

Usually, the preamble symbol includes a physical layer format control part (PHY Format Control, or PFC) and a physical layer content control part (PHY Content Control, or PCC). The preamble symbol of the DVB_T2 system includes P1 and P2, both of which are used to transmit signaling information or further used to transmit frame format parameters. However, the prior art P1 can only transmit 7-bit signaling, resulting in insufficient system transmission efficiency, and it is not suitable for coherent decoding systems, and does not consider the number of time-domain symbols used to transmit the required symbols by selecting the number of preamble symbols. Signaling to suit system needs.

Contents of the invention

The problem that the present invention solves is that the preamble symbol transmission method of the prior art causes the system transmission efficiency to be insufficient, and it cannot be applied to a coherent decoding system, and does not consider transmitting the required signaling by selecting the number of time domain symbols of the preamble symbol to meet system needs.

In order to solve the above problems, an embodiment of the present invention provides a method for generating a preamble symbol. A method for generating a preamble symbol is characterized in that it includes the following steps: generating a frequency domain subcarrier based on a frequency domain subject sequence; Subcarriers are subjected to inverse Fourier transform to obtain a time-domain main signal; and at least one time-domain symbol based on the time-domain main signal is used to generate the preamble symbol, wherein the step of generating the frequency-domain sub-carrier includes: using A predetermined sequence generation rule for generating the frequency domain main sequence; and/or a predetermined processing rule for generating the frequency domain subcarrier by processing the frequency domain main sequence, the predetermined sequence generation rule includes any of the following One or two combinations: generated based on different sequence generators; and/or generated based on the same sequence generator, and further cyclically shifting the generated sequence, the predetermined processing rules include: based on the frequency domain subject sequence Phase modulation is performed on the pre-generated sub-carriers obtained through processing according to the frequency offset value.

Optionally, in the step of performing phase modulation based on the pre-generated subcarriers with the frequency offset value, the frequency domain subcarriers corresponding to the same time domain main signal use the same frequency offset value to pair Phase modulation is performed on each effective subcarrier in the frequency domain subcarriers, and the frequency offset values used by the frequency domain subcarriers corresponding to different main signals in the time domain are different.

Optionally, in the predetermined sequence generation rule, the different sequence generation formulas are obtained by assigning different root values to the same constant envelope zero autocorrelation sequence, and the same sequence generation formula is obtained by assigning the constant envelope zero autocorrelation sequence The same root value is obtained.

Optionally, the step of generating the frequency-domain sub-carriers includes: generating the frequency-domain main sequence by using a different-based sequence generation formula in the predetermined sequence generation rule.

Optionally, the step of generating the frequency-domain subcarriers includes: using the predetermined sequence generation rule based on different sequence generation formulas to generate the frequency-domain main sequence, and continuing to use the frequency-domain main sequence The above predetermined processing rules are used to generate frequency-domain subcarriers.

Optionally, the frequency domain main sequence is generated based on one or more constant envelope zero autocorrelation sequences, and the frequency domain main sequence has a predetermined sequence length N _ZC .

Optionally, when generating based on multiple constant envelope zero autocorrelation sequences, each has a corresponding subsequence length L _M , for each constant envelope zero autocorrelation sequence according to the predetermined sequence generation rule A subsequence with a subsequence length L _M is generated, and multiple subsequences are spliced into the frequency domain main sequence with the predetermined sequence length N _ZC .

Optionally, the predetermined sequence length N _ZC of the frequency domain main sequence is not greater than the Fourier transform length _NFFT of the time domain main signal, and the pregenerated subcarriers are obtained based on the frequency domain main sequence processing The step includes a processing filling step, the processing filling step includes: referring to the predetermined sequence length N _ZC to map the main frequency domain sequence into positive frequency subcarriers and negative frequency subcarriers; referring to the Fourier transform length _NFFT in the filling the outer edges of the positive frequency subcarrier and the negative frequency subcarrier with a predetermined number of virtual subcarriers and DC subcarriers; a location.

Optionally, the step of processing and filling further includes the following step: performing PN modulation on the frequency-domain main sequence, and then performing the mapping, and is used for the frequency-domain main sequence corresponding to each of the time-domain main signals The PN sequences for performing the PN modulation are the same or different.

Optionally, the step of performing the cyclic shift in the predetermined sequence generation rule is set before or after performing the PN modulation.

Optionally, information is transmitted by using the root value corresponding to the first main signal in the time domain and/or the initial phase of the PN sequence used for the PN modulation.

Optionally, when the frequency-domain subcarriers used for signaling transmission are generated using the predetermined sequence generation rule,

If the first time domain main signal of the at least one time domain main signal adopts a pre-known frequency domain main sequence, the frequency domain main sequence and the corresponding frequency offset value are not used for signaling .

Optionally, wherein the preamble symbol is located in a physical frame, and the signaling transmitted through the frequency domain body sequence includes a frame format parameter for indicating the physical frame and/or is used for indicating emergency broadcast content.

Optionally, wherein the time-domain symbol has the following three-segment structure: wherein, the first three-segment structure includes: the time-domain main signal, a prefix generated by selecting a part of the end of the time-domain main signal, and A suffix generated by selecting a part of the main signal in the time domain within the prefix range; the second three-segment structure includes: the main signal in the time domain, a prefix generated by selecting a part of the end of the main signal in the time domain, and based on The main time-domain signal selects a part of the generated super-preamble within the prefix range, and the preamble symbol includes: the time-domain symbol having the first three-segment structure; or having the second three-segment structure structure; or a free combination of several time-domain symbols having the first three-segment structure and/or several time-domain symbols having the second three-segment structure arranged in no particular order.

An embodiment of the present invention also provides a method for generating a preamble symbol, wherein a time domain symbol having the following three-segment structure is generated based on the main signal in the time domain; and the preamble symbol is generated based on at least one of the time domain symbols ,

Wherein, the first type of three-segment structure includes: the main signal in the time domain, a prefix generated by selecting a part of the end of the main signal in the time domain, and a suffix generated by selecting a part within the range of the prefix based on the main signal in the time domain ; The second three-segment structure includes: the time-domain main signal, a prefix generated by selecting a part of the end of the time-domain main signal, and a super-prefix generated by selecting a part within the prefix range based on the time-domain main signal , the leading symbol includes: the time-domain symbol with the first three-segment structure; or the time-domain symbol with the second three-segment structure; or several time-domain symbols with the first three-segment structure arranged in no particular order A time-domain symbol with a three-segment structure and/or a free combination of several time-domain symbols with a second three-segment structure.

Optionally, wherein, the main signal in the time domain is defined as the first part, the main signal in the time domain as the suffix or the super-prefix is defined as the second part, and the main signal in the time domain as the prefix is defined as A part is defined as a third part, the third part is obtained by directly copying a part of the first part, and the second part is obtained based on a frequency offset modulation of a part of the first part.

Optionally, set the length of the first part as N _A , set the length of the second part as Len _B , set the length of the third part as Len _C , set the length of the first part In the three-segment structure, select the starting point of the second part corresponding to the first sampling point number of the first part to be N1_1, and select the starting point of the second part in the second three-segment structure corresponding to the first part The sequence number of the second sampling point is set to N1_2, which satisfies the following formula: N1_1+N1_2=2N _A -(Len _B +Len _c ), the modulation frequency offset value f _SH of the modulation frequency offset is selected corresponding to the time domain symbol The subcarrier spacing in the frequency domain is 1/N _A T or 1/(Len _B +Len _c )T, and the initial phase of modulation is selected arbitrarily, and T is the sampling period.

Optionally, wherein, for each of the first three-segment structure and each of the second three-segment structure, the value of N _A is 2048, the value of Len _C is 520, and the value of Len _B is 504 , the sequence number of the first sampling point N1_1=1544, the sequence number of the second sampling point N1_2=1528, and the modulation frequency offset value f _SH is 1/(1024T) or 1/(2048T).

Optionally, wherein the emergency broadcast is identified by using a different starting point for selecting the second part from the first part.

Optionally, the number of at least one time-domain symbol included in the preamble symbol is four.

Optionally, the three-segment structures of the four time-domain symbols respectively include: the first three-segment structure, the second three-segment structure, and the first three-segment structure structure and the second three-segment structure; or the first three-segment structure, the second three-segment structure, the second three-segment structure and the second three-segment structure; or the The second three-stage structure, the first three-stage structure, the first three-stage structure, and the first three-stage structure; or the first three-stage structure, the second Three-stage structure, the first three-stage structure, and the first three-stage structure; or the first three-stage structure, the first three-stage structure, the first three-stage structure, and The second three-segment structure; or the first three-segment structure, the first three-segment structure, the first three-segment structure, and the first three-segment structure; or the first three-segment structure A three-segment structure, the first three-segment structure, the second three-segment structure, and the second three-segment structure.

Optionally, the main time domain signal is obtained by inverse Fourier transforming the frequency domain subcarriers generated based on the frequency domain main sequence, wherein the step of generating the frequency domain subcarriers includes: generating the A predetermined sequence generation rule for the main sequence in the frequency domain; and/or a predetermined processing rule for generating the subcarrier in the frequency domain by processing the main sequence in the frequency domain, the predetermined sequence generation rule includes any one or both of the following Combination: generated based on different sequence generators; and/or generated based on the same sequence generator, and further cyclically shifting the generated sequence, the predetermined processing rule includes: processing the sequence based on the main body in the frequency domain The pre-generated sub-carriers are phase-modulated according to the frequency offset value.

The embodiment of the present invention also provides a method for receiving a preamble symbol, which is characterized in that the received physical frame is processed to obtain a baseband signal; judging whether there is a preamble symbol to be received in the baseband signal; determining the received The location of the preamble symbol in the physical frame and deciphering the signaling information carried by the preamble symbol when the signaling information exists.

Optionally, when judging whether there is the preamble symbol expected to be received in the baseband signal, any one of the following methods or any combination of at least two methods may be used for reliability judgment: initial timing synchronization method, integer Multiplication frequency offset estimation method, precise timing synchronization method, channel estimation method and decoding result analysis method.

Optionally, the fractional multiple frequency offset is estimated from the preliminary result obtained through the initial timing synchronization manner.

Optionally, when the first one of the at least one time-domain main signal does not transmit signaling as known information, the initial timing synchronization method includes: through the first performing a differential operation on the time-domain symbols, and performing a differential operation on the time-domain sequence corresponding to the known information, and then performing cross-correlation between the two to obtain a cross-correlation value, based on the obtained one or more cross-correlation values, at least based on this Results in initial synchronization.

Optionally, the integer multiple frequency offset estimation method is performed based on the result obtained in the initial timing synchronization method.

Optionally, in the step of estimating the integer multiple frequency offset, any one or a combination of the following two methods is included: the first integer multiple frequency offset estimation method includes: adopting a frequency sweep method to scan all or After some time-domain waveforms are modulated with different frequency offsets, several frequency-sweeping time-domain signals are obtained, and the known time-domain signals obtained by inverse Fourier transform of known frequency-domain sequences are combined with each of the frequency-sweeping time-domain signals After the sliding correlation is performed, the frequency offset value modulated by the frequency-sweeping time-domain signal of the maximum correlation peak value is the estimated value of the integer multiple frequency offset; and/or the second integer multiple frequency offset estimation method includes: synchronizing according to the initial timing The position results of intercepting the main time domain signal and performing Fourier transform on the frequency domain subcarriers are cyclically shifted according to different shift values in the frequency scanning range, and the receiving sequence corresponding to the effective subcarrier is intercepted, and the receiving sequence Perform a predetermined operation with the known frequency domain sequence and then perform an inverse Fourier transform, and obtain the correspondence between the shift value and the estimated value of the integer multiple frequency offset based on the inverse Fourier transform results of several sets of shift values , thus obtaining an integer multiple frequency offset estimate.

Optionally, after the integer multiple frequency offset estimation is completed, the frequency offset is compensated and then the transmission signaling is analyzed.

Optionally, after the integer multiple frequency offset estimation is completed, when the first main time domain signal in the at least one time domain main signal does not transmit signaling and is known information, use this known signal to perform The precise timing synchronization method.

Optionally, the channel estimation method, included in the step of analyzing the transmission signaling, includes: after the decoding of the last main signal in the time domain is completed, using the obtained decoding information as the sending information, at the time The channel estimation is performed again in the domain/frequency domain, and a specific operation is performed with the previous channel estimation results to obtain a new channel estimation result, which is used for channel estimation of the signaling analysis of the main signal in the next time domain.

Embodiments of the present invention also provide devices for generating preamble symbols corresponding to the above generating method and receiving method.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

According to the leading symbol generation method and receiving method, the leading symbol generating device and the receiving device provided by the embodiments of the present invention, since any one of the leading symbols or a plurality of three-segment structures freely combined are generated, the main part of each three-segment symbol can be The signaling is transmitted in the time domain structure and the frequency domain structure respectively. In the time domain, the three-segment structure can be used to achieve coherent demodulation. At the same time, the problem of single-frequency interference can be solved by implementing frequency offset modulation in the suffix or super-prefix. Solve the problem of small bias estimation failure under dangerous delay through two different three-stage structures; in addition, in the frequency domain, the generated sequence is further cycled by generating based on different sequence generators and/or based on the same sequence generator The frequency-domain subcarrier is generated by shifting, which can optionally be further combined with performing phase modulation on the processed pre-generated subcarrier according to the frequency offset value, so as to improve system transmission efficiency. Further, the time-domain main signal in the first time-domain symbol can use known symbols for initial synchronization and channel estimation of coherent detection, and at the same time, the number of time-domain symbols in the preamble symbol can be flexibly selected according to system requirements to transmit the required signaling.

Description of drawings

Fig. 1 is a schematic flow chart of Embodiment 1 of a method for generating a leading symbol of the present invention;

FIG. 2 is a schematic diagram of a time-domain structure of a physical frame in an embodiment of the present invention;

3 is a schematic diagram of a physical frame structure including a format control part and a content control part in an embodiment of the present invention;

FIG. 4 is a schematic diagram of a frequency domain corresponding to a time domain symbol in a preamble symbol according to an embodiment of the present invention;

5 is a schematic diagram of the first three-stage structure in an embodiment of the present invention;

6 is a schematic diagram of a second three-stage structure in an embodiment of the present invention;

FIG. 7 is a schematic flowchart of Embodiment 2 of the method for generating a leading symbol of the present invention; and

FIG. 8 is a schematic flowchart of an embodiment of a method for receiving a preamble symbol in the present invention;

Fig. 9 is a logic operation block diagram of obtaining preliminary timing synchronization results by using 4 groups of cumulative correlation values of 4 time domain symbols in the present invention; and

Fig. 10 is a logical operation block diagram for obtaining preliminary timing synchronization results by using two sets of accumulated correlation values of two time-domain symbols in the present invention.

detailed description

The inventors found that the preamble symbols in the prior art have problems such as low transmission efficiency, insufficient transmission flexibility, poor initial timing synchronization performance, inability to implement coherent decoding, and thus poor decoding performance at low SNR.

In view of the above problems, the inventor provided a method for generating and receiving preamble symbols after research. The design of the preamble symbols not only improves the timing synchronization performance of the preamble symbols, but also utilizes the characteristics of the cyclic prefix to implement coherent decoding, which improves the Receive performance issues in most cases. At the same time, signaling is transmitted in both the time domain and the frequency domain, the frequency domain implements signaling transmission through various methods, and the time domain can implement emergency broadcast signs. At the same time, by flexibly using the number of symbols in the time domain to implement the signaling that needs to be transmitted to meet the needs of the system, and to achieve transmission flexibility and scalability. At the same time, with regard to the method for generating preamble symbols of the present invention, corresponding receiving algorithms are described in detail, and these receiving algorithms can achieve very robust performance with relatively low complexity.

In order to make the above objects, features and advantages of the present invention more comprehensible, the specific implementation manners of the present invention will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a schematic flowchart of an embodiment of a method for generating a leading symbol in the present invention. As shown in Figure 1, the generation method of leading symbol in the present embodiment, comprises the following steps:

Step S1-1: Generate frequency-domain subcarriers based on frequency-domain subject sequences;

Step S1-2: performing inverse Fourier transform on frequency domain subcarriers to obtain time domain main signal; and

Step S1-3: Generate a preamble symbol from at least one time-domain symbol formed based on the main time-domain signal.

Wherein, the step of generating frequency domain subcarriers includes: (1) predetermined sequence generation rules for generating frequency domain main sequences; and/or (2) processing frequency domain main sequences for predetermined processing of generating frequency domain subcarriers rule,

(1) The predetermined sequence generation rules include any one or a combination of the following:

(1a) generated based on a different sequence production; and/or

(1b) Generate based on the same sequence generator, and further perform cyclic shift on the generated sequence,

(2) The predetermined processing rule includes: performing phase modulation on the pre-generated sub-carriers obtained by processing based on the main sequence in the frequency domain according to the frequency offset value.

Fig. 2 is a schematic diagram of a time-domain structure of a physical frame in an embodiment of the present invention.

As shown in FIG. 2 , this implementation discloses a frame structure. In FIG. 2 , two physical frames are shown. Each physical frame includes a preamble symbol and a data area, wherein the preamble symbol is located before the data area.

The data area is used to transmit data information, such as TS packets or IP packets.

The preamble symbol is used for rapid detection to determine whether the signal transmitted in the channel is an expected signal, and provides basic transmission parameters (such as FFT points, frame type information, etc.), so that the receiving end can perform subsequent receiving processing; detect the initial carrier frequency offset and timing error, to achieve frequency and timing synchronization after compensation; emergency broadcast wake-up, etc.

Fig. 3 is a schematic diagram of a physical frame structure including a format control part and a content control part in an embodiment of the present invention.

As shown in Figure 3, the physical frame structure includes a preamble symbol and a data area, wherein the preamble symbol includes: a physical layer format control part PFC and a physical layer content control part PCC. Certainly, the leading symbol involved in the present invention is not limited to include the PFC part and the PCC part.

The format control part PFC is composed of one or more time-domain symbols (indicated by a slash box in the figure), and each OFDM time-domain symbol has the same size. In this embodiment, OFDM symbols are used as time domain symbols.

Fig. 5 is a schematic diagram of a first three-stage structure in an embodiment of the present invention; and Fig. 6 is a schematic diagram of a second three-stage structure in an embodiment of the present invention.

The format control part PFC of the preamble symbol contains at least one time-domain symbol. Since the time-domain symbols in this embodiment all adopt the following first three-segment structure or the second three-segment structure, the time-domain symbols contained in the preamble symbol It can also be called a three-segment structure time-domain symbol. However, without limitation, the time-domain symbols in the preamble symbols satisfying the above requirements may also adopt other structures other than the three-segment structure.

It can be seen from Fig. 5 and Fig. 6 that in the first embodiment, the time-domain symbol has the following three-segment structure: the first three-segment structure in Fig. 5: time-domain main signal (section A), based on the time-domain main signal The prefix (section C) generated by the rear part of , and the suffix (section B) generated by selecting a part in the prefix range based on the time-domain main signal; as shown in the second three-section structure in Figure 6: the time-domain main signal (A Segment), a prefix generated based on the rear part of the main signal in the time domain (segment C), and a super-prefix generated based on a part of the main signal in the time domain within the prefix range (segment B).

A section of time-domain subject signal (marked by A in the figure) is taken as the first part, and a part is taken from the end of the first part according to the predetermined acquisition rules, scheduled to be processed and copied to the front of the first part to generate the third part (marked by A in the figure). C mark) to be used as a prefix, and at the same time, a part is taken out from the rear part of the first part according to the predetermined acquisition rule, and the predetermined process is processed and copied to the rear part of the first part or processed and copied to the front part of the prefix to generate the second part ( Marked with B in the figure) so that they are respectively used as a suffix or a super prefix, thereby generating the first three-segment structure (CAB structure) with B as a suffix as shown in Figure 5 and the one with B as a super prefix as shown in Figure 6 The second three-segment structure (BCA structure).

Based on the time-domain symbols with a three-segment structure, the leading symbols generated in this embodiment may include: time-domain symbols with a first type of three-segment structure; or time-domain symbols with a second type of three-segment structure; or A free combination of several time-domain symbols with the first three-segment structure and/or several time-domain symbols with the second three-segment structure arranged in no particular order. That is, the leading symbol may only contain CAB or BCA, may also be several CABs or several BCAs, or may be any free combination of an unlimited number of several CABs and several BCAs in no particular order. It should be noted that the preamble symbol of the present invention is not limited to only include C-A-B or B-C-A structures, and may also include other time-domain structures, such as traditional CP structures.

Section A is obtained based on a certain frequency-domain subject sequence through, for example, 2048-point IFFT transformation. Section C in the three-segment structure is a direct copy of a part of section A, while section B is a part of the modulated signal section in section A. The data range of is not more than the data range of C, that is, the range of the part A selected for the modulated signal segment B will not exceed the range of the part A intercepted as the prefix C. Preferably, the sum of the length of B and the length of C is the length of A.

Let N _A be the length of A, let Len _C be the length of C, and Len _B be the length of modulation signal segment B. Let the sampling point number of A be 0, 1,...N _A -1. Let N1 be the sampling point number of the first part A corresponding to the starting point of the second part B of the modulation signal segment, and N2 be the sampling point number of the selection copying to the modulation signal segment The sampling point number of the first part A corresponding to the end point of the second part B. in,

N2＝N1+Len _B -1 (Formula 1)

Usually, the modulation implemented on the second part B section is the modulation frequency offset, the modulation M sequence or other sequences, etc. In this implementation, the modulation frequency offset is taken as an example. Let P1_A(t) be the time domain expression of A, then the first The time-domain expression of a common preamble symbol is

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& {\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; SH</span>}}\mathrm{<span\; class="notranslate">\; t</span>}}& <span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; otherwise</span>}\end{array}\right.$

(Formula 2)

Among them, the modulation frequency offset value f _SH can be selected as the frequency domain subcarrier interval corresponding to the time domain OFDM symbol, that is, 1/N _A T, or 1/(Len _B +Len _c )T where T is the sampling period, and N _A is the time The length of the domain OFDM symbol, for example, N _A is 1024, f _SH =1/1024T, and the initial phase of the modulation frequency offset can be selected arbitrarily. In order to make the correlation peak sharp, f _SH can also be selected as 1/(Len _B T) or a value close to its value.

In the B-C-A structure, the modulation frequency offset value is just opposite to the C-A-B structure, and the initial phase of the modulation can be selected arbitrarily.

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; SH</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& {\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& <span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; otherwise</span>}\end{array}\right.$

(Formula 3)

Select the second part (B) starting point corresponding to the first sampling point sequence number of the first part (A) in the first three-segment structure (CAB) as N1_1, select the second in the second three-segment structure (BCA) The starting point of part (B) corresponds to the second sampling point number of the first part (A) is set to N1_2, the first sampling point number N1_1 and the second sampling point number N1_2 need to satisfy the following formula

N1_1+N1_2＝2N _A -(Len _B +Len _c ) (Formula 4)

The advantage of satisfying such a relationship is that the delay relationship of the same content from section C to section B in the CAB structure is the same as the delay relationship from section B to section A in the BCA structure, and the delay of the same content from section A to section B in the CAB structure The relationship is the same as the delay relationship of the same content from section B to section C in the BCA structure, which is beneficial to receiver implementation. In addition, in the CAB structure and the BCA structure, if the modulation used for the B segment is the modulation frequency offset, the frequency offset value f _SH of the two structures should be just opposite, which is beneficial to the implementation of the receiver.

Use number 1 to indicate the symbol of C-A-B structure, and use number 2 to indicate the symbol of B-C-A structure. Then let P1_A(t) be the time-domain expression of A1, and P2_A(t) be the time-domain expression of A2, then the time-domain expression of the C-A-B three-segment structure is

$\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& {\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; SH</span>}}\mathrm{<span\; class="notranslate">\; t</span>}}& <span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; otherwise</span>}\end{array}\right.$

(Formula 5)

The time-domain expression of the B-C-A three-segment structure is

$\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; SH</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& {\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& <span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; otherwise</span>}\end{array}\right.$

(Formula 6)

Among them, the first three-segment structure and the second three-segment structure arranged in no particular order can respectively form several first three-segment structures and/or several second three-segment structures according to the sequence. Free combination of leading symbols. The following example gives the time-domain expression of the first preamble symbol of 1 C-A-B and 1 B-C-A in sequence, and the time domain expression of the second preamble symbol of 1 B-C-A and 1 C-A-B in sequence.

Then, the time-domain expression of the first leading symbol is:

(Formula 7)

The time domain expression of the second leading symbol is:

(Formula 8)

Based on the time-domain expressions of the first preamble symbol and the second preamble symbol, other combinations of C-A-B and B-C-A can be deduced, which will not be repeated here.

As in the above case, when the C-A-B structure and the B-C-A structure are cascaded, the problem of small bias estimation failure under dangerous delay can be solved. When dangerous delays cause segments C and A to cancel each other out, segment CB of the first structure and segment BC of the second structure can still be used for timing synchronization and for estimating small offsets.

Set the number of at least one time-domain symbol contained in the preamble symbol to transmit four symbols, and several preferred four time-domain symbol structures are given below, arranged in order as any of the following structures:

(1) C-A-B, B-C-A, C-A-B, B-C-A; or

(2) C-A-B, B-C-A, B-C-A, B-C-A; or

(3) B-C-A, C-A-B, C-A-B, C-A-B; or

(4) C-A-B, B-C-A, C-A-B, C-A-B; or

(5) C-A-B, C-A-B, C-A-B, B-C-A; or

(6) C-A-B, C-A-B, C-A-B, C-A-B or

(7) C-A-B, C-A-B, B-C-A, B-C-A.

Among them, for example (1) the structure of four time-domain symbols such as C-A-B, B-C-A, C-A-B, and B-C-A maximizes the effect of concatenation. For example (2) The structure of four time-domain symbols such as C-A-B, B-C-A, B-C-A, and B-C-A will lengthen the guard interval of part A of subsequent symbols, and usually the first symbol is a known signal, so C-A-B is used.

List a preferred embodiment of the three-stage structure, N _A is 2048, assuming is 520, Len _B = 504, N1_1 = 1544, N1_2 = 1528, all let P1_A(t) be the expression of time domain subject A, then the time domain expressions of CAB and BCA can be deduced as

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1528</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 520</span>}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 520</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 520</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 2568</span>}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1024</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; SH</span>}}\mathrm{<span\; class="notranslate">\; t</span>}}& \mathrm{<span\; class="notranslate">\; 2568</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 3072</span>}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; otherwise</span>}\end{array}\right.$

(Formula 9)

as well as

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1528</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; SH</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 520</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 504</span>}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1024</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 504</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 1024</span>}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1024</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>& \mathrm{<span\; class="notranslate">\; 1024</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 3072</span>}\mathrm{<span\; class="notranslate">\; T</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; otherwise</span>}\end{array}\right.$

(Formula 10)

Further, f _SH can be selected as 1/(1024T) or 1/(2048T).

Further, the emergency broadcasting system can be identified by selecting different starting points of the second part B from the first part A, that is, selecting different N1, or N1_1 and N1_2, and copying to the starting point of the B segment to identify the emergency broadcasting system. For example, in the symbol of the three-segment structure of C-A-B, N1_1=1544 identifies the common system, while N1_1=1528 identifies the emergency broadcast system. For another example, in the symbol of the three-segment structure of B-C-A, N1_2=1528 identifies a common system, while N1_2=1544 identifies an emergency broadcast system.

Combining with the steps of generating the above preamble symbols in FIG. 1 , it can be known that the time-domain main signal A is obtained by generating frequency-domain subcarriers based on the frequency-domain main sequence and performing inverse Fourier transform IFFT. A time-domain symbol having a three-segment structure such as C-A-B or B-C-A is then formed from the main time-domain signal A, thereby forming a preamble symbol having at least one time-domain symbol in this embodiment.

The following describes the generation process of the time-domain main signal A of the three-segment structure (CAB or BCA).

Fig. 4 is a schematic diagram of a frequency domain corresponding to a time domain symbol in a preamble symbol according to an embodiment of the present invention.

As shown in FIG. 4 , the frequency-domain subcarrier generation of a time-domain symbol in the PFC of the preamble symbol is given, and the frequency-domain subcarrier is obtained based on the main sequence in the frequency domain.

The generation of frequency domain subcarriers includes predetermined sequence generation rules for generating frequency domain main sequences and/or predetermined processing rules for generating frequency domain subcarriers by processing frequency domain main sequences.

For the predetermined sequence generation rules, the generation process of the main sequence in the frequency domain is relatively flexible, and the predetermined sequence generation rules include any one or a combination of the following: generated based on different sequence generation formulas; and/or generated based on the same sequence generation formula , and further perform cyclic shift on the generated sequence. In this embodiment, it is realized by using a constant envelope zero autocorrelation sequence (CAZAC sequence), that is to say, the above-mentioned different sequence generation formulas are obtained by assigning different root values to the same CAZAC sequence, or the above-mentioned same sequence generation formula can be obtained by It is obtained by assigning the same root value to the CAZAC sequence.

The frequency domain main sequence is generated based on one or more CAZAC sequences, and the frequency domain main sequence has a predetermined sequence length N _ZC . The predetermined sequence length N _ZC is not greater than the Fourier transform length _NFFT of the main signal in the time domain.

The steps of processing and filling the frequency domain subject sequence generally include: mapping the frequency domain subject sequence into positive frequency subcarriers and negative frequency _subcarriers with reference to the predetermined sequence length N _ZC ; filling the outer edge of the negative frequency subcarrier with a predetermined number of virtual subcarriers and DC subcarriers; and cyclically shifting the obtained subcarriers to the left, so that the zero subcarrier corresponds to the first position of the inverse Fourier transform.

Here, an example of generation based on one CAZAC sequence is given. First generate a frequency domain subject sequence (Zadoff-Chu, sequence, ZC) of N _ZC length, which is a kind of CAZAC sequence,

Let the sequence formula be: $a_q\left(\mathrm{no}\right)=e^{-\mathrm{j\&pi;q}\frac{\mathrm{no}(\mathrm{no}+1)}{N_{\mathrm{root}}}}$

(Formula 11)

Note that N _ZC can be equal to or less than N _root , that is, it can be generated by a complete Zadoff-Chu sequence with a certain root value, and then you can choose to modulate a PN sequence of the same length on this ZC sequence to obtain a ZC_M sequence, and ZC_M The sequence is divided into two parts, the length of the left half is Mapped to the negative frequency part, the right half has length Mapped to the positive frequency part, N _ZC can choose a certain natural number, which does not exceed the FFT length of section A; in addition, at the edge of the negative frequency, add number of zeros, and at the edge of positive frequencies, fill The number of zeros is a virtual subcarrier; therefore, this particular sequence is given by zero, A PN modulated ZC sequence, 1 DC subcarrier, A PN modulated ZC sequence and zero sequence; the effective number of subcarriers is N _ZC +1.

Specifically, the generation process of the subject sequence in the frequency domain, such as the sequence formula Several different root values q can be selected, and for the sequence generated by each root value q, different cyclic shifts can be performed to obtain more sequences, and signaling can be transmitted by either or both of these two methods.

For example, take 256 root values q, get 256 sequences, then you can transmit 8 bits, based on 2^8=256, and the shift value is set to 1024, then each sequence in 256 can be 0- 1023 shifts, that is, each sequence realizes 10-bit signaling transmission through 1024 shifts, based on 2^10=1024, so a total of 8+10=18-bit signaling can be transmitted.

These signalings are mapped to bit fields, and the transmitted signaling may contain frame format parameters used to indicate physical frames and/or used to indicate emergency broadcast content, wherein, frame format parameters such as: frame number, frame length, PCC symbol Bandwidth, bandwidth of data region, FFT size and guard interval length of PCC symbols, PCC modulation and coding parameters.

The cyclic shift in the above predetermined sequence generation rule can be performed before the PN sequence modulation on the ZC sequence, or after the PN sequence modulation. The domain subject sequences are the same or different among the PN sequences for the PN modulation.

Wherein, if the first time-domain main signal in at least one time-domain main signal adopts a pre-known frequency-domain main sequence, the frequency-domain main sequence and the corresponding frequency offset value are not used for transmission signaling, and the subsequent time-domain symbols In the PFC to transmit signaling.

The frequency domain main sequence (ZC sequence) used in the last OFDM symbol and the frequency domain main sequence (ZC sequence) used in the first OFDM symbol have a phase difference of 180 degrees, which is used to indicate the last OFDM symbol of PFC; The ZC sequence used by the first OFDM symbol, generally is a root sequence without cyclic shift of a certain length, and at this length, there is a set of ZC sequences, so the present invention selects a certain sequence in this set, which can indicate a certain information, such as a version number or indicate a transmission in a data frame In addition, the initial phase of the PN sequence used for PN modulation also has a certain signaling capability , for example to indicate a version number.

Here, an example of generation based on a plurality of CAZAC sequences is given. Each CAZAC sequence has a corresponding subsequence length L _M , for each CAZAC sequence, a subsequence with a subsequence length L _M is generated according to the above predetermined sequence generation rules, and multiple subsequences are spliced into a frequency domain with a predetermined sequence length N _ZC subject sequence.

Specifically, in the generation of effective subcarriers in the frequency domain, it consists of M CAZAC sequences, and the lengths of the M CAZAC sequences are respectively L ₁ , L ₂ ,...L _M , and satisfy The generation method of each CAZAC sequence is the same as above, only one step is added. After generating M CAZAC sequences, they are spliced into a sequence of length N _ZC . ZC_M can be formed after being modulated by a PN sequence, and then interleaved in the frequency domain. Form a new ZC_I, and then fill in the same subcarrier position as above, the length of the left half is Mapped to the negative frequency part, the right half has length Mapped to the positive frequency part, N _ZC can choose a certain natural number, which does not exceed the FFT length of section A; in addition, at the edge of the negative frequency, add number of zeros, and at the edge of positive frequencies, fill The number of zeros is a virtual subcarrier; therefore, this particular sequence is given by zero, A PN modulated ZC sequence, 1 DC subcarrier, A PN modulated ZC sequence and zero order, wherein the step of modulating PN can also be performed after frequency domain interleaving.

Subcarrier position filling may also take other filling steps, which are not limited here.

After the subcarriers filled with the above processing are cyclically shifted to the left, after the first half and the second half spectrum are swapped, it is similar to the fftshift in Matlab, that is, the zero subcarrier corresponds to the first position of the discrete inverse Fourier transform, and the predetermined Pregenerated subcarriers for frequency-domain OFDM symbols of length _NFFT .

Further, in the frequency domain subcarrier generation process of this embodiment, in addition to the above-mentioned predetermined sequence generation rules, it is also more preferable to adopt the predetermined processing rules for processing the main sequence in the frequency domain to generate the frequency domain subcarriers . The present invention does not limit the use of any one or both of the predetermined processing rule and the predetermined sequence generation rule to form frequency-domain subcarriers.

The predetermined processing rule includes: performing phase modulation on the pre-generated sub-carrier according to the frequency offset value S, wherein the pre-generated sub-carrier is obtained through the above-mentioned steps of processing and filling the main sequence in the frequency domain, and circularly shifting to the left. In this predetermined processing rule, the frequency domain subcarriers corresponding to the same time domain main signal A use the same frequency offset value S to perform phase modulation on each effective subcarrier in the frequency domain subcarriers, and the frequency domain subcarriers corresponding to different time domain main signals A The frequency offset values used by the subcarriers in the frequency domain are different S.

Specifically for the predetermined processing rules, for example, the subcarrier expression of the original OFDM symbol is

a ₀ (k) k=0,1,2,... N _FFT -1,

(Equation 12) The expression for phase modulation of each subcarrier according to a certain frequency offset value such as s is as follows:

$\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;sk</span>}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; FFT</span>}}}}& \mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; FFT</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}\end{array}$

(Formula 13)

Wherein, the zero-carrier multiplication operation does not actually need to be performed, and only needs to be operated on valid subcarriers. The frequency offset value s can be selected from an integer in the range of [-( _NFFT -1),+( _NFFT -1)], and the frequency offset value s is determined based on the Fourier transform length _NFFT of the main signal in the time domain, Its different values can be used for transmission signaling.

It should be noted that the above implementation method of phase modulating each pre-generated subcarrier according to the frequency offset value S can also be implemented in the time domain. It is equivalent to: the original unmodulated phase frequency domain OFDM symbol is transformed by IFFT to obtain the time domain ODFM symbol, and the time domain OFDM symbol can be cyclically shifted to generate the time domain main signal A, which is transmitted through different cyclic shift values signaling. In the present invention, phase modulation is performed on each effective subcarrier according to a certain frequency offset value in the frequency domain, and the obvious equivalent operation method in the time domain is also within the present invention.

To sum up, in this embodiment, in the process of generating subcarriers in the frequency domain, the above predetermined sequence generation rule (1a), predetermined sequence generation rule (1b) and predetermined processing rule (2) can be performed based on frequency domain subject sequence selection. Any one of or a free combination of at least two.

For example, the method for generating preamble symbols according to rule (1a) is used to transmit signaling.

For example, as described in the above example, there are 256 types of root values q, and the cyclic shift value of each root value q is 0-1023, so 8+10=18-bit signaling can be transmitted.

For another example, for example, the method for generating the preamble symbol of rule (1a) and rule (2) is used to transmit signaling.

There are 2 types of root value q, the time-domain OFDM symbol length is 2048, and 1024 kinds of shift values are taken, with an interval of 2, such as 0, 2, 4, 6, ... 2046, etc., and 1+10=11-bit signaling is transmitted .

For another example, for example, only the leading symbol generation method of rule (2) is used.

The root value q is fixed, and the frequency domain subcarriers are phase modulated according to different frequency offset values S, for example, the above _NFFT is 2048, $\begin{array}{cc}{a}_{\mathrm{the\; s}}\left(k\right)=a_0\left(k\right)\&Center\; Dot;e^{j\frac{2\mathrm{\&pi;sk}}{N_{\mathrm{FFT}}}}& k=\mathrm{0,1,2},...N_{\mathrm{FFT}}-1\end{array}$ The value of s is 0, 8, 16, ... 2032, etc., which is equivalent to the time-domain OFDM symbol after IFFT of the frequency-domain OFDM symbol without phase modulation, and performs cyclic shift of 256 different shift values, with 8 as Intervals, such as 0, 8, 16, ... 2032, etc., transmit 8-bit signaling. Here, the present invention does not limit the left shift or right shift of the cyclic shift. When s is a positive number, it corresponds to a time-domain cyclic shift to the left. For example, a value of 8 corresponds to a time-domain cyclic shift to the left of 8; when s is a negative number , which corresponds to a right shift in the time domain cycle, for example, a value of -8 corresponds to a right shift in the time domain cycle by 8.

The present invention also provides a receiving method according to Embodiment 2 of the preamble symbol. Fig. 7 is a schematic flowchart of Embodiment 2 of the leading symbol generation method of the present invention.

As shown in Figure 7, the generation method of leading symbol in the present embodiment, comprises the following steps:

Step S2-1: Generate a time-domain symbol with the following three-segment structure based on the main time-domain signal; and

Step S2-2: Generate a preamble symbol based on at least one time domain symbol.

Wherein, the first three-segment structure in the three-segment structure includes: the time-domain main signal, a prefix generated by selecting a part of the end of the time-domain main signal, and based on the time-domain main signal within the range of the prefix Select a part of the generated suffix; the second three-stage structure in the three-segment structure includes: the time-domain main signal, a prefix generated by selecting a part of the end of the time-domain main signal, and based on the time-domain main signal. Select a part of the generated super prefixes from the above prefix range,

The leading symbol includes: the time-domain symbol with the first three-segment structure; or the time-domain symbol with the second three-segment structure; or several time-domain symbols with the first three-segment structure arranged in no particular order A free combination of time-domain symbols with segment structure and/or several time-domain symbols with the second three-segment structure.

In the second embodiment, there are technical elements corresponding to those in the first embodiment, such as the specific structure of the first three-stage structure and the second three-stage structure, and the same description is omitted here.

Embodiments of the present invention also provide a method for receiving a preamble symbol. Fig. 8 is a schematic flowchart of an embodiment of a method for receiving a preamble symbol in the present invention.

As shown in Figure 8, the method for receiving the preamble symbol in this embodiment includes the following steps:

Step S3-1: Process the received physical frame to obtain a baseband signal;

Step S3-2: judging whether there is a preamble symbol expected to be received as generated by the above generation method in the baseband signal;

Step S3-3: Determine the position of the received preamble symbol in the physical frame and decipher the signaling information carried by the preamble symbol.

When judging in step S3-2 whether there is the preamble symbol desired to be received in the baseband signal, any one of the following methods or any combination of at least two methods can be used for reliability judgment: initial timing synchronization method, integer frequency multiplication Partial estimation method, precise timing synchronization method, channel estimation method and decoding result analysis method.

The step S3-2 includes an initial timing synchronization method, which is used to preliminarily determine the position of the preamble symbol in the physical frame. Further, after the initial synchronization, small bias estimation can also be performed based on the result of the initial timing synchronization. In addition, further, after the initial synchronization, the integer multiple frequency offset estimation method may also be performed based on the result obtained in the initial timing synchronization method.

When the leading symbol generation method of the sending end adopts the first time-domain main signal not to transmit signaling as known information, the (①) initial timing synchronization method includes: performing a differential operation through the first time-domain symbol, and combining the The difference operation is also performed on the time domain sequence corresponding to the known information, and then the two are cross-correlated to obtain a cross-correlation value. Based on one or more cross-correlation values obtained, at least initial synchronization is performed based on this result.

Next, the integer multiple frequency offset estimation method based on the initial timing synchronization result is described. In the step of integer multiple frequency offset estimation, any one or a combination of the following two methods is included:.

The first integer multiple frequency offset estimation method includes: after modulating all or part of the intercepted time-domain waveforms with different frequency offsets in a frequency-sweeping manner, several frequency-sweeping time-domain signals are obtained, which are then fuzzed by known frequency-domain sequences. After the known time-domain signal obtained by Liye inverse transform is slidingly correlated with each frequency-sweeping time-domain signal, the frequency offset value modulated by the frequency-sweeping time-domain signal with the maximum correlation peak value is the estimated value of the integer times frequency offset; and /or

The second integer multiple frequency offset estimation method includes: the frequency domain subcarrier obtained by intercepting the main time domain signal according to the position result of the initial timing synchronization and performing Fourier transform is cyclically shifted according to different shift values within the frequency sweep range, and the interception The received sequence corresponding to the effective subcarrier, the predetermined operation is performed on the received sequence and the known frequency domain sequence, and then the inverse Fourier transform is performed, and the shift value and integer multiple are obtained based on the inverse Fourier transform results of several sets of shift values Correspondence between estimated frequency offset values, thereby obtaining integer multiple frequency offset estimated values.

The following example specifically describes the offset estimation method. The known information of the first symbol of the PFC can be used for offset estimation and initial channel estimation, and the known information of the first symbol must be used.

The first integer multiple frequency offset estimation method intercepts all or part of the time-domain waveform of the received preamble symbol according to the position where the preamble symbol is detected synchronously at the initial timing, and adopts a frequency sweep method, that is, at a fixed frequency change step path, for example, corresponding to an integer multiple frequency offset interval, after modulating this part of the time-domain waveform with different frequency offsets, several time-domain signals are obtained

${A1}_{\mathrm{the\; y}}\left(n\right)=r\left(n\right)\&Center\; Dot;e^{j2\mathrm{\&pi;ynT}{f}_{\mathrm{the\; s}}/N_A}$ (Formula 14)

Among them, T is the sampling period, f _s is the sampling frequency. The time-domain signal corresponding to the inverse Fourier transform of the known frequency-domain sequence after the predetermined subcarrier filling method is A2, and A2 is used as a known signal to perform sliding correlation with each A1 _y , and the A1 _y with the largest correlation peak is selected, then The frequency offset value y modulated by it is the estimated value of integer times frequency offset.

Among them, the scanning range corresponds to the frequency offset range that the system needs to fight against. For example, it needs to fight against the frequency offset of plus or minus 500K, and the system sampling rate is 9.14M, and the main body of the preamble symbol is 2K in length, then the scanning range is That is [-114,114].

The second integer multiple frequency offset estimation method: according to the location where the preamble symbol detected synchronously at the initial timing, the main time domain signal A is intercepted, and FFT is performed, and the frequency domain subcarrier after FFT is scanned for different shift values cyclic shift, and then intercept the received sequence corresponding to the effective subcarrier, use the received sequence and the known frequency domain sequence to perform some kind of operation (usually conjugate multiplication, or division), and perform IFFT on the result, the IFFT Perform specific operations on the results, such as taking the energy of the largest diameter, or taking the accumulation of several large diameter energies. Then for several shift values, after several times of IFFT, one operation result is obtained each time, and several groups of operation results will be obtained. Based on these several sets of results, it is judged which shift value corresponds to the integer multiple frequency offset estimation, thereby obtaining the integer multiple frequency offset estimation value.

A common judging method is to select the shift value corresponding to the group with the largest energy based on the results of several groups as the estimated value of the integer multiple frequency offset.

There are many specific algorithms for integer multiple frequency offset estimation, which will not be repeated here.

In addition, the channel estimation is completed by using the received first symbol containing known information and the known frequency domain sequence in the first symbol and/or the time domain signal corresponding to its inverse Fourier transform, and can also choose to perform in the time domain And/or in the frequency domain, including time-frequency joint operations, which will not be expanded here.

Further, after the above integer multiple frequency offset estimation is completed, the frequency offset is compensated and then the transmission signaling is analyzed.

Further optionally, after the integer multiple frequency offset estimation is completed, when the first time-domain main signal in the at least one time-domain main signal does not transmit signaling and is known information, the known signal is used to perform precise timing synchronization.

The channel estimation method is included in the step of analyzing the transmission signaling, and the channel estimation method includes: after the decoding of the main signal in the last time domain is completed, the obtained decoding information is used as the transmission information, and the channel estimation method is retransmitted in the time domain/frequency domain. Channel estimation is performed once, and a specific operation is performed with the previous channel estimation results to obtain a new channel estimation result, which is used for channel estimation of the signaling analysis of the main signal in the next time domain.

Further, after the frame format parameters and/or emergency broadcast content are solved, the position of the PCC symbol or the position of the data symbol can be obtained according to the parameter content and the position of the determined PFC symbol, and the subsequent analysis of the PCC symbol or data symbol can be performed based on this .

More specifically, for the preamble symbol having a three-segment structure defined from the perspective of the time domain, such as the CAB or BCA with an unlimited number of arbitrary combinations in Embodiment 2:

In the receiving end used to receive the above-mentioned preamble symbols, the (②) initial timing synchronization method includes: when the time domain symbol is detected to have a three-segment structure, using the unique processing relationship and/or modulation of each CAB and/or BCA Delayed sliding autocorrelation is performed on the relationship to obtain one or more sets of accumulated correlation values, and then a specific mathematical operation is performed based on one or more sets of the correlation values, and at least preliminary timing synchronization is performed based on the values of the operation results.

Continuing with such preamble symbols, when the sender selects the different starting points of the second part from the first part to mark the emergency broadcast, the initial timing synchronization resolves the emergency broadcast through any one of the following or a free combination of any two: the third Different delay relationships of the same content between the first part and the second part; and different delay relationships of the same content between the first part and the second part, so as to distinguish between emergency broadcasts and ordinary broadcasts.

Further, when the PFC in the transmitted preamble symbol includes the following two cases (a) and (b),

(a) it is known that a first of said at least one time-domain host signal is not used for signaling;

(b) and detecting that said time-domain subject signal has said three-segment structure,

The initial timing synchronization is completed by any one or a combination of the above (①) initial timing synchronization method and (②) initial timing synchronization method. Wherein when based on two kinds of completions, then the first preliminary synchronization calculation value obtained by the (1) initial timing synchronization method and the second preliminary synchronization calculation value obtained by the (2) initial timing synchronization method are weighted again, based on the The weighted operation value completes the initial timing synchronization.

The method for preliminarily determining the position of the leading symbol in the physical frame will be described below in combination with specific method data and calculation formulas.

[Article (①) Initial Timing Synchronization Method]

Among them, when the first symbol of PFC does not transmit signaling and is a known signal, the first (①) initial timing synchronization method can perform a differential operation through the first symbol of PFC, and the time-domain signal corresponding to the known information is also differentiated Then perform cross-correlation between the two, perform initial synchronization based on one or more sets of differential correlation results, and preliminarily determine the position of the leading symbol in the physical frame.

The specific process of differential correlation in (①) initial timing synchronization mode is described below, and the process of single-group differential correlation is firstly introduced.

Determine the difference value, perform the difference operation according to the difference value on the received baseband data, and perform the difference operation according to the difference value on the local time domain sequence corresponding to the known information, and then cross-correlate the results of the two difference operations, A differential correlation result corresponding to the differential value is obtained. The operation process of the differential correlation result of this single group belongs to the prior art. Let the differential value be D, and the received baseband data be r _n , and the specific formula of each step is described as follows;

First, the received baseband data is subjected to a differential operation based on the differential value

$z_m^{\left(\mathrm{D.}\right)}=r_m{r}_{m-\mathrm{D.}}^{*}$ (Formula 15)

After the differential operation, the phase rotation caused by the carrier frequency offset becomes a fixed carrier phase e ^{j2 π D Δ f} , where Δf represents the carrier frequency offset.

At the same time, the local time domain sequence is also differentially calculated

$\begin{array}{cc}{c}_{\mathrm{no}}^{\left(\mathrm{D.}\right)}={\mathrm{the\; s}}_{\mathrm{no}}{\mathrm{the\; s}}_{\mathrm{no}-\mathrm{D.}}^{*}& \mathrm{no}=\mathrm{D.},...,L-1\end{array}$ (Formula 16)

Then cross-correlate the received data after difference with the local difference sequence to get

$R_{\mathrm{dc},m}^{\left(\mathrm{D.}\right)}=\underset{\mathrm{no}=\mathrm{D.}}{\overset{L-\mathrm{D.}}{\mathrm{\&Sigma;}}}{z}_{\mathrm{no}+m}^{\left(\mathrm{D.}\right)}{\left[c_{\mathrm{no}}^{\left(\mathrm{D.}\right)}\right]}^{*}$ (Formula 17)

When the system has no multipath and no noise,

$R_{\mathrm{dc},m}^{\left(\mathrm{D.}\right)}=\underset{\mathrm{no}=\mathrm{D.}}{\overset{L-\mathrm{D.}}{\mathrm{\&Sigma;}}}{z}_{\mathrm{no}+m}^{\left(\mathrm{D.}\right)}{\left[c_{\mathrm{no}}^{\left(\mathrm{D.}\right)}\right]}^{*}=e^{j2\mathrm{\&pi;D\&Delta;f}}\underset{\mathrm{no}=\mathrm{D.}}{\overset{L-\mathrm{D.}}{\mathrm{\&Sigma;}}}{c}_{\mathrm{no}+m}^{\left(\mathrm{D.}\right)}{\left[c_{\mathrm{no}}^{\left(\mathrm{D.}\right)}\right]}^{*}$ (Formula 18)

Correlation peaks are well given and are not affected by carrier deviation. The frame synchronization/timing synchronization position is obtained using the following formula

${\widehat{\mathrm{no}}}_0=\underset{m}{\arg \max }\left\{\right|R_{\mathrm{dc},m}^{\left(\mathrm{D.}\right)}\left|\right\}$ (Formula 19)

From the above single-group differential correlation operation process, it can be seen that the differential correlation algorithm can resist the influence of any large carrier frequency offset, but because the received sequence is differentially calculated first, the signal noise is enhanced, and the noise enhancement is very serious under low signal-to-noise ratio , resulting in a significant deterioration of the signal-to-noise ratio.

In order to avoid the above problems, not only a single set of differential correlation operations, but also multiple sets of differential correlations can be implemented. For example, the value of N is 64, and 64 sets of differential correlations are implemented to obtain Where D(0), D(1), ..., D(N-1) are N different difference values selected.

Perform specific mathematical operations on the N results to obtain the final correlation result.

In this embodiment, for the process in which multiple groups of differential correlations (64 groups) are selected according to predetermined differential selection rules, any one of the following two types can be used based on the performance requirements of the transmission system:

(1) The first predetermined difference selection rule: the difference value D(i) arbitrarily selects N different values and satisfies D(i)<L, where L is the length of the local time domain sequence corresponding to the known information.

(2) The second predetermined difference selection rule: the difference value D(i) selects N different values of the arithmetic sequence and satisfies D(i)<L, that is K is satisfied A constant integer of , where L is the length of the local time domain sequence corresponding to the known information.

Carry out predetermined processing operations on the N results (64) to obtain the final correlation results. There are two preferred embodiments of the predetermined processing operations here, which will be described separately.

The first scheduled processing operation:

N different values can be arbitrarily selected for the differential value D(i), satisfying D(i)<L. Because, for the arbitrarily selected differential value D( ⁱ ), the phase e ^{j2 π D(i) Δ f} i=0,...,N-1 of each group of differential correlations are different, so they cannot be directly vector added, So only weighted absolute values can be summed or averaged. Predetermined processing operations are performed on the N different differential correlation results by the following formula to obtain the final differential result. The following formula is an example of adding the absolute value to obtain the final difference result.

$\begin{array}{cc}{R}_{\mathrm{dc},m}=\underset{i=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\mathrm{abs}\left(R_{\mathrm{dc}\left(i\right),m}^{\left(\mathrm{D.}\left(i\right)\right)}\right)& i=0,...N-1\end{array}$ (Formula 20)

The second scheduled processing operation:

The difference value D(i) can choose N different values arbitrarily, satisfying D(i)<L, and satisfying that D(i) is an arithmetic sequence, that is, D(i+1)-D(i)=K, K to satisfy A constant integer of .

The difference value chosen according to this rule is obtained as After the differential correlation values of the two adjacent sets of differential correlation values are conjugate multiplied, N-1 groups of conjugate multiplied values are obtained by the following formula.

$\begin{array}{cc}{\mathrm{RM}}_{i,m}=R_{\mathrm{dc}\left(i\right),m}^{\left(\mathrm{D.}\left(i\right)\right)}\&Center\; Dot;{\left(R_{\mathrm{dc}(i+1),m}^{\left(\mathrm{D.}(i+1)\right)}\right)}^{*}& i=\mathrm{0,1,2},...,N-2\end{array}$ (Formula 21)

Because, through this conjugate multiplication, the originally different phase e ^{j2 π D(i) Δ f} of each group becomes the same e ^{j2 π K Δ f} , so, the N-1 groups of RM _i obtained by the following formula 8 _,m can perform weighted vector addition or averaging to obtain the final difference result, so as to obtain better performance than the first predetermined processing operation. The following formula is an example of vector addition to obtain the final difference result.

$\begin{array}{cc}{R}_{\mathrm{dc},m}=\underset{i=0}{\overset{N-2}{\mathrm{\&Sigma;}}}{\mathrm{RM}}_{i,m}& i=0,...N-1\end{array}$ (Formula 22)

It should be noted that, when the difference value D(i) adopts the above-mentioned second predetermined difference selection rule, it can not only match the conjugate multiplication value obtained in the second predetermined processing operation, and then perform weighted vector addition or average In order to obtain the final correlation result, it is also possible to directly add or average the weighted absolute values of at least two differential correlation results according to the above-mentioned first predetermined processing operation to obtain the final correlation result.

Therefore, the position of the leading symbol in the physical frame is preliminarily determined based on the operation R _dc,m .

[Article (②) Initial Timing Synchronization Method]

Wherein, when the preamble symbol has a time domain structure of C-A-B or B-C-A, the baseband signal is subjected to necessary inverse processing and/or the delay sliding auto Correlation to obtain one or more sets of cumulative correlation values, and then after performing delay relationship matching and/or specific mathematical operations based on one or more sets of cumulative correlation values, the calculated values are used for initial timing synchronization to preliminarily determine the leading symbol in the physical The position of the frame. For example, the formula for obtaining cumulative correlation value of delayed sliding autocorrelation is as follows:

$\begin{array}{c}{u}_1\left(\mathrm{no}\right)=r\left(\mathrm{no}\right)r^{*}(\mathrm{no}-N_A)\\ {u_1}^{\&prime;}\left(\mathrm{no}\right)=\frac{1}{N_{\mathrm{CP}}}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{u}_1(\mathrm{no}-k)\end{array}$ (Formula 23)

It is optional to perform energy normalization on U ₁ '(n) to obtain U _1s '(n).

which is ${u_{1\mathrm{the\; s}}}^{\&prime;}\left(\mathrm{no}\right)=\frac{{u_1}^{\&prime;}\left(\mathrm{no}\right)}{0.5\underset{k=0}{\overset{N_{\mathrm{cp}}-1}{\mathrm{\&Sigma;}}}({\left|r(\mathrm{no}-k)\right|}^2+{\left|r(\mathrm{no}-k-N_A)\right|}^2)}$ (Formula 24)

Energy normalization can also adopt other methods, the conjugation operation _* in U ₁ (n) can also be realized by r(n), and r( _nNA ) does not take conjugation.

In each C-A-B or B-C-A structure, three cumulative correlation values of CA, AB and CB based on the same content can be obtained respectively.

For example, here only the C-A-B structure is used as an example, and B-C-A can be deduced accordingly.

Use the same part of section C and section A to perform sliding delay correlation. Note that the above steps of energy normalization can be added, so I won't go into details here. Three correlation values can be obtained for each structure of CAB or BCA: U _ca '(n), U _cb '(n), U _cb '(n)

$\begin{array}{c}{u}_1\left(\mathrm{no}\right)=r\left(\mathrm{no}\right)r^{*}(\mathrm{no}-N_A)\\ {u_{\mathrm{ca}}}^{\&prime;}\left(\mathrm{no}\right)=\frac{1}{{\mathrm{Len}}_C}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{u}_1(\mathrm{no}-k)\end{array}$ (Formula 25)

Sliding delay correlation is performed using the same part of section B and section C that only modulates the frequency offset:

$\begin{array}{c}{u}_2\left(\mathrm{no}\right)=r\left(\mathrm{no}\right)r^{*}(\mathrm{no}-N_A-N_A+N1)e^{-\mathrm{jn}{f}_{\mathrm{SH}}T}\\ {u_{\mathrm{cb}}}^{\&prime;}\left(\mathrm{no}\right)=\frac{1}{\mathrm{corr}\_\mathrm{len}}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{u}_2(\mathrm{no}-k)\end{array}$ (Formula 26)

Sliding delay correlation is performed using the same part of segment B as segment A that only modulates the frequency offset:

$\begin{array}{c}{u}_3\left(\mathrm{no}\right)=r\left(\mathrm{no}\right)r^{*}(\mathrm{no}-N_A+N1)e^{-\mathrm{jn}{f}_{\mathrm{SH}}T}\\ {u_{\mathrm{ab}}}^{\&prime;}\left(\mathrm{no}\right)=\frac{1}{\mathrm{corr}\_\mathrm{len}}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{u}_3(\mathrm{no}-k)\end{array}$ (Formula 27)

Among them, corr_len can take 1/f _SH T to avoid continuous wave interference, or take Len _B to make the peak sharp.

However, when the leading symbol contains multiple three-segment structures, multiple groups of CA, AB and CB can be obtained. Three accumulated correlation values, that is, multiple groups of U _ca '(n) _, U _cb '(n) _, U _ab '(n) , perform delay relationship matching and/or mathematical operations based on one or more of the multiple sets of values to obtain a final calculated value, which is used for initial synchronization.

For example, for the preferred four time-domain symbols with a three-segment structure, when they are arranged as CAB, BCA, CAB, and BCA, we get $u_{\mathrm{ca}}^1\left(\mathrm{no}\right),u_{\mathrm{cb}}^1\left(\mathrm{no}\right),u_{\mathrm{ab}}^1\left(\mathrm{no}\right),u_{\mathrm{ca}}^2\left(\mathrm{no}\right),u_{\mathrm{cb}}^2\left(\mathrm{no}\right),u_{\mathrm{ab}}^2\left(\mathrm{no}\right),$ $u_{\mathrm{ca}}^3\left(\mathrm{no}\right),u_{\mathrm{cb}}^3\left(\mathrm{no}\right),u_{\mathrm{ab}}^3\left(\mathrm{no}\right),u_{\mathrm{ca}}^4\left(\mathrm{no}\right),u_{\mathrm{cb}}^4\left(\mathrm{no}\right),u_{\mathrm{ab}}^4\left(\mathrm{no}\right).$

then you can put One or more of them are added or averaged after delay relationship matching and/or phase adjustment to obtain the final U _ca (n). This is because they have the same phase value. Examples of delayed matching are as follows:

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

$u_{\mathrm{ca}}^3(\mathrm{no}-(N_A+2{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ as well as

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$

Can be One or more of them are added or averaged after delay relationship matching and/or phase adjustment to obtain the final U _cb-ab (n). This is because they have the same phase value. Examples of delayed matching are as follows:

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cb</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

$u_{\mathrm{cn}}^3(\mathrm{no}-(N_A+2{\mathrm{Len}}_B)),$ as well as

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

Can be One or more of them are added or averaged after delay relationship matching and/or phase adjustment to obtain the final U _ab-cb (n). Examples of delayed matching are as follows:

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cb</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Len</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

$u_{\mathrm{ab}}^3(\mathrm{no}-\left(2{\mathrm{Len}}_B\right)),$ as well as

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cb</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

Finally, based on one or more of U _ca (n) and U _cb-ab (n) and U _ab-cb (n), perform delay matching and perform specific operations. The delay matching here is as follows:

U _ca (n), U _cb-ab (n), U _ab-cb (nA)

Initial timing synchronization is performed based on the result of an operation, a specific digital operation may be an absolute value addition. For example, take the maximum value position to complete the initial timing synchronization.

It should be noted that, taking into account the influence of the system sampling clock deviation, in the above embodiment, the delay numbers that some of the delay correlators should have can be added and subtracted by one to form the three delay numbers of itself and the addition and subtraction of one, according to The three delay numbers implement sliding delay autocorrelation, and then select the one with the most obvious correlation result, and at the same time, the timing deviation can be estimated.

Fig. 9 has just provided the logic operation block diagram that utilizes 4 groups of cumulative correlation values of 4 time-domain symbols to obtain preliminary timing synchronization results in this implementation; and Fig. 10 has just provided 2 groups of using 2 time-domain symbols in this implementation A logic operation block diagram for accumulating correlation values to obtain preliminary timing synchronization results.

Not generally, if the preamble symbol contains other time-domain characteristics in addition to the C-A-B or B-C-A structure, in addition to using the timing synchronization method of the above-mentioned C-A-B or B-C-A structural characteristics, it is superimposed on other time-domain structure characteristics to implement Other timing synchronization methods do not deviate from the spirit described in the present invention.

Further, after the initial timing synchronization is preliminarily completed, fractional multiple frequency offset estimation can also be performed by using the preliminary timing synchronization results of the (①) method and/or the (②) method.

For the algorithm of fractional multiple frequency offset estimation, for example, when adopting (①) preliminary timing synchronization method, $\begin{array}{cc}{R}_{\mathrm{dc},m}=\underset{i=0}{\overset{N-2}{\mathrm{\&Sigma;}}}{\mathrm{RM}}_{i,m}& i=0,...N-1\end{array},$ Taking its maximum value, the corresponding phase is e ^{j2 π K Δ f} , and Δf can be calculated and converted into the corresponding first small deviation value.

For another specific example, when (②) is in the preliminary timing synchronization mode, the angle of the maximum value in U _ca (n) can be taken to calculate the second small deviation value, and then U _cb-ab (n) and U _ab- After the conjugate multiplication of _cb (n), the angle corresponding to the maximum value is also taken, and the third small deviation value can be calculated. The angles in the logic operation block diagram above are used to obtain the schematic part of the small deviation, and the small deviation estimation can be performed based on any one or both of the second small deviation value and the third small deviation value.

When the PFC in the transmitted preamble contains both (①) and (②) features required for the implementation of the preliminary timing synchronization method, based on any one of the first, second, and third small offset values or any at least two combination to get a small biased estimate.

In the step of deciphering the signaling information carried by the preamble symbol in the above step S3-3, the signaling information parsing step includes: using all or part of the time domain waveform of the preamble symbol and/or using all or part of the preamble symbol Signaling information carried by the preamble symbol is deciphered from the frequency domain signal obtained after the time domain waveform is Fourier transformed.

For example, according to the length N _FFT of the time-domain received data corresponding to each received symbol in the PFC part, the FFT operation of the corresponding length is performed, and the zero carrier is removed, and the received frequency-domain sub-carrier is taken out according to the effective sub-carrier position. It is used for signaling analysis.

If the transmission sequence is PN modulated, the receiving end can first perform demodulation and PN operation on the received frequency domain subcarriers, and then perform ZC sequence signaling analysis. Signaling analysis may also be performed directly by using the received frequency-domain subcarriers without demodulating the PN. The difference between the two lies only in the method adopted for the collection of known sequences, which will be explained below.

Further, in the step of analyzing the signaling information, the set of known signaling sequences and all possible The frequency domain modulates the frequency offset value to resolve signaling. The set of known sequences here includes the following meanings:

CAZAC sequences generated by all possible rooting and/or all possible frequency domain cyclic shifts, if the PN is modulated at the sending end, the known sequence set can refer to the sequence set after the PN is modulated, or the sequence set before the PN is modulated collection of sequences. If the receiving end performs the demodulation PN operation in the frequency domain, the known sequence set adopts the sequence set before modulating the PN, and if the receiving end does not use the demodulating PN in the frequency domain, the known sequence set adopts the sequence set after modulating the PN. If you want to use the time-domain waveform corresponding to the known sequence set, you must use the CAZAC sequence to modulate the sequence set after PN.

Further, if the sending end generates the CAZAC sequence and performs interleaving operation, the known sequence set can refer to the CAZAC sequence and/or the sequence set after frequency-domain interleaving after modulating PN, or it can refer to the sequence set before frequency-domain interleaving set of sequences. If the receiving end performs deinterleaving in the frequency domain, the known sequence set uses the sequence set before frequency domain interleaving; if the receiving end does not use deinterleaving in the frequency domain, the known sequence set uses the sequence set after frequency domain interleaving . If you want to use the time-domain waveform corresponding to the known sequence set, you must use the CAZAC sequence and/or modulate the PN and deinterleave the sequence set, that is, the set of sequences that are finally mapped to the subcarriers.

The specific process of signaling analysis is described as follows from the following two transmission situations adopted by the generation method of the sending end respectively.

<First sending situation> When the subcarriers in the frequency domain are generated by using different sequence generation formulas and/or based on the same sequence generation formula to further cyclically shift the generated sequence.

Perform specific mathematical operations on the frequency-domain signaling subcarriers, channel estimates, and all possible frequency-domain subject sequences for signaling analysis, where the specific mathematical operations include any of the following:

(1) A maximum likelihood correlation operation combined with channel estimation; or

(2) After performing channel equalization on the frequency domain signaling subcarriers, the channel estimation value is correlated with all possible frequency domain main sequences, and the maximum correlation value is selected as the decoding result of signaling analysis.

The following specifically describes the signaling analysis process in the first sending situation.

For example, let i=0:M-1, M is the number of signaling subcarriers, j=0:2P-1, ^P is the number of signaling bits transmitted in the frequency domain, that is, the corresponding signaling subcarrier set has 2 ^P elements. And each element corresponds to a sequence of length M. H _i is the channel estimation value corresponding to each signaling subcarrier, SC_rec _i is the received frequency domain signaling subcarrier value, SC _i ^j is the signaling subcarrier The i-th value of the j-th element in the carrier set.

but $\begin{array}{cc}{\mathrm{corr}}_j=\mathrm{Re}(\underset{i=0}{\overset{m-1}{\mathrm{\&Sigma;}}}\mathrm{SC}\_{\mathrm{rec}}_i{h_i}^{*}{\mathrm{SC}}_i^{*j})& j=0:2^P-1\end{array}$ (Equation 28) Take the j corresponding to max(corr _j ), that is, obtain the frequency domain transmission signaling.

If the sender has modulated PN and SC_rec _i has not been demodulated by PN, then Corresponding to the set of sequences after modulating PN; if SC_rec _i is demodulated by PN, then Correspondingly adopts the sequence set before modulating PN.

For the operations involving frequency domain interleaving at the sending end, it can be simply deduced, and will not be elaborated here.

Optionally, the decoding process of the transmission signaling in the frequency domain can also be performed in the time domain, using the time domain signaling waveform set corresponding to the known signaling subcarrier set after IFFT transformation to directly compare with the time domain for obtaining the accurate position of the multipath Synchronously correlate the received signals in the frequency domain, and take the one with the largest absolute value of the correlation value, which can also solve the transmission signaling in the frequency domain, which will not be repeated here.

If the signaling subcarriers of each PFC symbol are composed of more than one ZC sequence modulated PN and frequency domain interleaving, then after the receiving end obtains the effective subcarriers in the frequency domain, it performs the corresponding frequency domain deinterleaving operation, demodulates the PN operation, and then performs Analysis of ZC sequence signaling. If the modulation PN is performed before the frequency domain interleaving, the frequency domain deinterleaving is performed first, and then the demodulation PN is performed. If the modulated PN is interleaved in the frequency domain, the PN is demodulated first, and then the frequency domain deinterleave is performed, or the frequency domain deinterleave is performed first, and then the PN is demodulated. However, the demodulated PN sequence at this time is the PN sequence obtained by deinterleaving the original PN.

<Second sending situation> When the phase modulation of the pre-generated sub-carrier with the frequency offset value is used in the generation process of the frequency-domain sub-carrier.

Use any one or a combination of at least two of the following three signaling methods for signaling analysis:

The first analytical signaling method: After the frequency domain signal is taken out of the effective subcarriers for channel equalization, it is matched/divided with each known sequence of the known signaling set, and the frequency offset value in the frequency domain is directly calculated or inverse Fu Lie operations; and/or

The second analytical signaling method: when it is determined that the frequency-domain signaling set of each time-domain symbol has only one known sequence and the known sequences of the previous and subsequent symbols are also the same, only the delay correlation between the previous and subsequent time-domain symbols is solved. time domain cyclic shift values for resolution signaling; and/or

The third analytical signaling method: correspondingly cross-correlate the time-domain received signal of each time-domain symbol with the known time-domain sequences corresponding to the known frequency-domain sequences before all possible modulation frequency offsets, and the cross-correlation Values are pre-determined, and then the cross-correlation values of the pre- and post-symbols after the pre-determined processing are further correlated with the delay correlation of the pre- and post-symbol interval lengths according to the predetermined symbol length relationship of the time-domain symbols. Time-domain cyclic shift values resolve transmission signaling.

Specifically, in the step of deciphering the signaling information carried by the preamble symbol by using the frequency domain signal, if the frequency domain sequence at the transmitting end is obtained by phase-modulating each effective subcarrier according to the above-mentioned frequency offset value S, then the implementable There are three types of parsing and receiving algorithms:

The first analysis receiving algorithm:

The value of the effective subcarrier is taken out of the frequency domain signal, after channel equalization, each subcarrier is matched/divided with the subcarrier corresponding to each frequency domain known sequence of the known frequency domain signaling set, and then the IFFT operation is performed , based on the result of IFFT, the transmitted signaling (including the main sequence in the frequency domain and the signaling transmitted by the cyclic shift value in the time domain) is solved.

For example, it is known that the expression of the transmitted frequency domain subcarrier without phase modulation is A _k , and the expression after phase modulation is

${\mathrm{AM}}_k=A_k\&CenterDot;e^{j\frac{2\mathrm{\&pi;sk}}{N_{\mathrm{FFT}}}},$ (Formula 29)

After passing through the channel, the received frequency domain data expression is

$R_k={\mathrm{AM}}_k\&CenterDot;h_k+N_k=A_k\&Center\; Dot;h_k\&CenterDot;e^{j\frac{2\mathrm{\&pi;sk}}{N_{\mathrm{FFt}}}}+N_k,$ (Formula 30)

Wherein A _k is a known value of the kth carrier in the known signaling set. then proceed

or E _k =R _k ·(A _k ·H _k ) ^* or (Formula 31)

Where σ ² is the estimated noise variance, and then E _k is subjected to IFFT operation, and the position with the largest absolute value of the operation result is used to analyze the signaling, that is, the frequency domain modulation frequency offset value S (time domain cyclic shift value).

For example, if there is only one known sequence in the known frequency domain signaling set, that is, only rely on the frequency domain modulation frequency offset value S (time domain cyclic shift value) to transmit signaling, then based on the result of one IFFT, the absolute value The position where the maximum value occurs is used to analyze the signaling of time-domain cyclic shift transmission.

For example, the known frequency domain signaling set has two known sequences, which are generated by CAZAC sequences with different root values and modulated by PN to transmit one signaling, and also rely on domain modulation frequency offset value (time domain cycle shift value) to transmit 8 signalings, then respectively perform 2 above-mentioned processes to obtain 2 IFFT results, and based on the 2 IFFT results, select the one with the largest absolute value to solve the 1-bit signaling transmitted in the frequency domain, At the same time, the 8-bit signaling transmitted by the cyclic shift in the time domain is analyzed according to the position where the larger peak appears.

The second analysis receiving algorithm:

The signaling transmitted by the time-domain cyclic shift value is solved based on the delay correlation between the preceding and following symbols, that is, the frequency-domain modulation frequency offset value. This method can be used when the known frequency-domain signaling set corresponding to each time-domain main signal has only one known sequence, and the known sequences corresponding to the time-domain main signals of the preceding and following time-domain symbols are the same, only relying on frequency-domain modulation frequency offset Value (time-domain cyclic shift value) transmission signaling.

Specifically, for example, time-domain shift transmission of N-bit signaling corresponds to 2 ^N shift values respectively. Then add the 2 ^N shift values to the inherent delay number between 2 symbols to obtain 2 ^N delay values, the receiver tries the delay correlation of 2 ^N delay values D, and the delay correlation expression is as above

$\begin{array}{c}{\mathrm{E.}}_{1,\mathrm{D.}}\left(\mathrm{no}\right)=r\left(\mathrm{no}\right)r^{*}(\mathrm{no}-\mathrm{D.})\\ \mathrm{E.}\left(\mathrm{D.}\right)=\frac{1}{L}\underset{k=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{\mathrm{E.}}_{1,\mathrm{D.}}({\mathrm{no}}_0+k)\end{array}$ (Formula 32)

Among them, L can be selected as the length of the time-domain subject A, and n ₀ is the starting point of the time-domain subject A after initial timing synchronization or precise timing synchronization.

A total of 2 ^N E(D)s are obtained, and the D corresponding to the maximum value is taken out, and then the transmitted signaling can be obtained by inversion.

The third parsing receiving algorithm:

Based on the received signal in the time domain, cross-correlate the known sequences in the time domain corresponding to all possible known frequency-domain sequence sets before the modulation frequency offset corresponding to the time-domain main signal of each time-domain symbol, and perform cross-correlation based on the cross-correlation value For a specific operation, the processed cross-correlation value is further subjected to delay correlation such as the second analysis receiving algorithm with a length of two symbol intervals before and after, to solve the signaling transmitted by the time-domain cyclic shift value.

The specific operation performed on the cross-correlation value here is generally to extract the large diameter and filter out the noise. Specifically, the larger peak part of the cross-correlation value is reserved, and the noise floor part is set to 0. Subsequent delay correlation of the two symbols before and after is further performed based on the processed cross-correlation value. The method and judgment are the same as those of the second parsing and receiving algorithm, and will not be repeated here.

For further explanation, if there is more than one time-domain known sequence corresponding to the known frequency-domain sequence set corresponding to the time-domain main signal of each time-domain symbol, that is, the sending end includes different root values that use the frequency domain to generate the cazac sequence And/or use the cyclic shift of the same root value of the CAZAC sequence generated in the frequency domain to transmit the signaling, and also use the method of phase-modulating each effective subcarrier according to the frequency offset value in the frequency domain to transmit the signaling, then multiple times The known sequences in the domain are cross-correlated with the received signals in the time domain, and then the one with the largest cross-correlation value is selected for each time-domain symbol for subsequent processing, and the element in the corresponding known frequency-domain sequence set with the largest cross-correlation is used , the signaling transmitted by different root values of the CAZAC sequence generated in the frequency domain and/or the cyclic shift of the same root value of the CAZAC sequence generated in the frequency domain can be analyzed. At the same time, the follow-up cross-correlation value is further used to perform a delay correlation of two symbol interval lengths before and after, to solve the signaling transmitted by the method of phase-modulating each effective subcarrier according to the frequency offset value in the frequency domain.

Further, no matter which signaling analysis method is used, when the decoding of the main signal in the last time domain of PFC is completed, it is assumed that the decoding is correct, and the previous decoding information is used as the sending information, and the time domain/frequency domain is again Carry out channel estimation, and perform a specific operation with the previous channel estimation results to obtain a new channel estimation result, which is used for the channel estimation of the signaling analysis of the next main signal in the time domain.

Further, when the signaling analysis is completed, that is, after the frame format parameters and/or emergency broadcast content are solved, the position of the PCC symbol or the position of the data symbol can be obtained according to the parameter content and the position of the determined PFC symbol, and subsequent analysis can be performed based on this PCC symbols or data symbols.

Finally, it is particularly noted that at the receiving end, there are many ways to judge whether there is a preamble symbol that is expected to be received. For example, it can be judged by the calculation result after correlation in the above-mentioned ① initial timing synchronization, or it can be estimated by the subsequent integer multiple frequency offset. , precise timing synchronization, channel estimation or the reliability of decoding results to judge.

Among them, judging from the calculation result after correlation in the above-mentioned ① initial timing synchronization, the method of fixed threshold can be adopted, that is, if the calculation result exceeds the fixed threshold, it is considered that there is a part of the preamble symbol that is expected to be received, and based on the calculation result corresponding to The position can be deduced from where the time-domain symbol of the corresponding three-segment structure occurs.

Not shown in the figure, the embodiment of the present invention also provides a preamble generation device, the generation device includes: a subcarrier generation unit, based on the frequency domain main sequence to generate frequency domain subcarriers; performing inverse Fourier transform on the domain subcarriers to obtain a time domain main signal; and a time domain processing unit for generating a preamble symbol from at least one time domain symbol formed based on the time domain main signal.

Wherein, the subcarrier generation unit includes: a sequence generation module for generating predetermined sequence generation rules for frequency domain main sequences; and/or a carrier processing module for processing frequency domain main sequences for generating predetermined processing rules for frequency domain subcarriers .

The predetermined sequence generation rules in the sequence generation module include any one or a combination of the following: generation based on different sequence generation formulas; and/or generation based on the same sequence generation formula, further cyclically shifting the generated sequence, and the carrier processing module The predetermined processing rule includes: performing phase modulation on the pre-generated sub-carriers obtained by processing based on the main sequence in the frequency domain according to the frequency offset value.

Not shown in the figure, the embodiment of the present invention also provides a preamble generation device, the generation device includes: a time domain generation unit, based on the main signal in the time domain to generate a time domain symbol with the following three-segment structure; and A preamble generating unit is configured to generate a preamble symbol based on at least one time-domain symbol.

Among them, the first three-segment structure includes: the main signal in the time domain, the prefix generated by selecting a part of the end of the main signal in the homogeneous time domain, and the suffix generated by selecting a part of the prefix range based on the main signal in the time domain; the second three-segment structure includes : The main signal in the time domain, the prefix generated by selecting a part of the end of the main signal in the homogeneous time domain, and the super prefix generated by selecting a part in the prefix range based on the main signal in the time domain.

The preamble symbols generated by the preamble generating unit include: time-domain symbols with the first three-segment structure; or time-domain symbols with the second three-segment structure; Structured time-domain symbols and/or a free combination of several time-domain symbols with the second three-segment structure.

Not shown in the figure, the embodiment of the present invention also provides a receiving device for preamble symbols, the receiving device includes: a baseband processing unit, processing the received physical frame to obtain a baseband signal; a judging unit, judging the baseband signal Whether there is a preamble symbol expected to be received; the signaling analysis unit determines the position of the received preamble symbol in the physical frame and deciphers the signaling information carried by the preamble symbol when the signaling information exists.

The generation device and receiving device of the preamble symbol provided in this implementation correspond to the generation method and the receiving method of the preamble symbol in the above-mentioned embodiments respectively, then the structure and technical elements in the device can be formed by corresponding transformation of the generation method, in This omitted description will not be repeated.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention, and any person skilled in the art can use the methods disclosed above and technical content to analyze the present invention without departing from the spirit and scope of the present invention. Possible changes and modifications are made in the technical solution. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention, which do not depart from the content of the technical solution of the present invention, all belong to the technical solution of the present invention. protected range.

Claims (43)

1. a generation method of leading symbol, is characterized in that, comprises the steps: generating frequency domain subcarriers based on frequency domain subject sequences; performing an inverse Fourier transform on the frequency-domain subcarrier to obtain a time-domain main signal; and generating said preamble symbol from at least one time domain symbol formed based on said time domain master signal, Wherein, the step of generating the frequency domain subcarrier includes: a predetermined sequence generation rule for generating the frequency domain main sequence; and/or processing the frequency domain main sequence for generating the frequency domain subcarrier scheduled processing rules, The predetermined sequence generation rules include any one or a combination of the following: generated based on a different sequence production; and/or Generated based on the same sequence generator, and further perform cyclic shift on the generated sequence, The predetermined processing rule includes: performing phase modulation on the pre-generated sub-carriers obtained by processing based on the frequency domain main sequence according to a frequency offset value. 2. the generation method of leading symbol as claimed in claim 1, is characterized in that, Wherein, in the step of performing phase modulation based on the pre-generated subcarrier with the frequency offset value, The frequency domain subcarriers corresponding to the same time domain main signal use the same frequency offset value to perform phase modulation on each effective subcarrier in the frequency domain subcarriers, The frequency offset values used by the frequency domain subcarriers corresponding to different time domain main signals are different. 3. the generation method of leading symbol as claimed in claim 1, is characterized in that, In the predetermined sequence generation rule, The different sequence generation formulas are obtained by assigning different root values to the same constant envelope zero autocorrelation sequence, The generating formula of the same sequence is obtained by giving the constant envelope zero autocorrelation sequence the same root value. 4. the generation method of leading symbol as claimed in claim 3, is characterized in that, Wherein, the step of generating the frequency-domain subcarriers includes: using different sequence generation formulas in the predetermined sequence generation rules to generate the frequency-domain main sequence. 5. the generation method of leading symbol as claimed in claim 3, is characterized in that, Wherein, the step of generating the frequency-domain subcarrier includes: using the predetermined sequence generation rule based on different sequence generation formulas to generate the frequency-domain main sequence, and continuing to use the predetermined processing rule for the frequency-domain main sequence to generate frequency-domain subcarriers. 6. The generation method of leading symbol as claimed in claim 3, is characterized in that: Wherein, the frequency domain subject sequence is generated based on one or more constant envelope zero autocorrelation sequences, The frequency domain body sequence has a predetermined sequence length N _ZC . 7. The generation method of leading symbol as claimed in claim 6, is characterized in that: When generated based on a plurality of said constant envelope zero autocorrelation sequences, each having a respective subsequence length L _M , generating a subsequence with a subsequence length L _M for each of the constant envelope zero autocorrelation sequences according to the predetermined sequence generation rule, splicing the plurality of subsequences into the main frequency domain sequence with the predetermined sequence length N _ZC . 8. The generation method of leading symbol as claimed in claim 1, is characterized in that: The predetermined sequence length N _ZC of the main frequency domain sequence is not greater than the Fourier transform length N _FFT of the main time domain signal, The step of obtaining the pre-generated subcarriers based on the main sequence in the frequency domain includes a processing filling step, and the processing filling step includes: Mapping the frequency domain main sequence into positive frequency subcarriers and negative frequency subcarriers with reference to a predetermined sequence length N _ZC ; filling a predetermined number of virtual subcarriers and DC subcarriers on the outer edges of the positive frequency subcarrier and the negative frequency subcarrier with reference to the Fourier transform length _NFFT ; and The resulting subcarriers are cyclically shifted left such that the zero subcarrier corresponds to the first position of the inverse Fourier transform. 9. The generation method of leading symbol as claimed in claim 8, is characterized in that: The step of processing filling also includes the following steps: performing PN modulation on the main sequence in the frequency domain, so as to perform the mapping, The PN sequences used to perform the PN modulation on the frequency domain main sequences corresponding to the respective time domain main signals are the same or different. 10. the generation method of leading symbol as claimed in claim 9, is characterized in that, Wherein, the step of performing the cyclic shift in the predetermined sequence generation rule is set before or after performing the PN modulation. 11. the generation method of leading symbol as claimed in claim 9, is characterized in that, Wherein, information is transmitted by using the root value corresponding to the first main signal in the time domain and/or the initial phase of the PN sequence used for the PN modulation. 12. the generation method of leading symbol as claimed in claim 1, is characterized in that, Wherein, when the frequency-domain subcarriers used for signaling transmission are generated using the predetermined sequence generation rule, If the first time domain main signal of the at least one time domain main signal adopts a pre-known frequency domain main sequence, the frequency domain main sequence and the corresponding frequency offset value are not used for signaling . 13. The generation method of leading symbol as claimed in claim 12, is characterized in that, Wherein, the preamble symbol is located in a physical frame, and the signaling transmitted through the frequency domain body sequence includes a frame format parameter for indicating the physical frame and/or is used for indicating emergency broadcast content. 14. the generation method of leading symbol as claimed in claim 1, is characterized in that, Wherein, the time-domain symbol has the following three-segment structure: Wherein, the first type of three-segment structure includes: the main signal in the time domain, a prefix generated by selecting a part of the end of the main signal in the time domain, and a suffix generated by selecting a part within the range of the prefix based on the main signal in the time domain ; The second three-segment structure includes: the time-domain main signal, a prefix generated by selecting a part from the end of the time-domain main signal, and a super-prefix generated by selecting a part within the prefix range based on the time-domain main signal, The leading symbols include: said time-domain symbols having said first three-segment structure; or a time-domain symbol having said second three-segment structure; or A free combination of several time-domain symbols having the first three-segment structure and/or several time-domain symbols having the second three-segment structure arranged in no particular order. 15. A method for generating a leading symbol, comprising the steps of: generating a time-domain symbol having the following three-segment structure based on the time-domain subject signal; and generating the preamble symbol based on at least one of the time domain symbols, Wherein, the first type of three-segment structure includes: the main signal in the time domain, a prefix generated by selecting a part of the end of the main signal in the time domain, and a suffix generated by selecting a part within the range of the prefix based on the main signal in the time domain ; The second three-segment structure includes: the main signal in the time domain, a prefix generated by selecting a part from the end of the main signal in the time domain, and a super prefix generated by selecting a part within the prefix range based on the main signal in the time domain, The leading symbols include: said time-domain symbols having said first three-segment structure; or a time-domain symbol having said second three-segment structure; or A free combination of several time-domain symbols having the first three-segment structure and/or several time-domain symbols having the second three-segment structure arranged in no particular order. 16. the generation method of leading symbol as claimed in claim 15, is characterized in that, Wherein, the main signal in the time domain is defined as the first part, the main signal part in the time domain as the suffix or the super-prefix is defined as the second part, and the main signal part in the time domain as the prefix is defined as the second part three parts, The third part is obtained by directly copying a part of the first part, and the second part is obtained based on a part of the modulated frequency offset of the first part. 17. The generation method of leading symbol as claimed in claim 16, is characterized in that, Wherein, the length of the first part is set as N _A , the length of the second part is set as Len _B , and the length of the third part is set as Len _C , In the first three-segment structure, select the starting point of the second part corresponding to the first sampling point sequence number of the first part as N1_1, and select the starting point of the second part in the second three-segment structure The serial number of the second sampling point corresponding to the first part is set as N1_2, which satisfies the following formula: N1_1+N 1_2=2N _A -(Len _B +Len _c ), For the modulation frequency offset value f _SH of the modulation frequency offset, select the frequency domain subcarrier spacing corresponding to the time domain symbol, that is, 1/N _A T or 1/(Len _B +Len _c )T, and the initial phase of modulation is arbitrary Select, T is the sampling period. 18. The generation method of leading symbol as claimed in claim 17, is characterized in that, Wherein, for each of the first three-segment structure and each of the second three-segment structure, The value of N _A is 2048, the value of Len _C is 520, the value of Len _B is 504, the first sampling point sequence number N1_1=1544, the second sampling point sequence number N1_2=1528, The modulation frequency offset value f _SH is 1/(1024T) or 1/(2048T). 19. The generation method of leading symbol as claimed in claim 16, is characterized in that, Wherein, the emergency broadcast is identified by using different starting points for selecting the second part from the first part. 20. The generation method of leading symbol as claimed in claim 15, is characterized in that, Wherein, the number of at least one time-domain symbol included in the preamble symbol is four. 21. the generation method of leading symbol as claimed in claim 20, is characterized in that, Wherein, the three-segment structures respectively possessed by the four time-domain symbols are as follows: the first three-segment structure, the second three-segment structure, the first three-segment structure, and the second three-segment structure; or the first three-segment structure, the second three-segment structure, the second three-segment structure, and the second three-segment structure; or the second three-segment structure, the first three-segment structure, the first three-segment structure, and the first three-segment structure; or the first three-segment structure, the second three-segment structure, the first three-segment structure, and the first three-segment structure; or the first three-segment structure, the first three-segment structure, the first three-segment structure, and the second three-segment structure; or the first three-segment structure, the first three-segment structure, the first three-segment structure, and the first three-segment structure; or The first three-segment structure, the first three-segment structure, the second three-segment structure, and the second three-segment structure. 22. The generation method of leading symbol as claimed in claim 15, is characterized in that, The time-domain main signal is obtained by inverse Fourier transforming the frequency-domain subcarriers generated based on the frequency-domain main sequence, Wherein, the step of generating the frequency domain subcarrier includes: a predetermined sequence generation rule for generating the frequency domain main sequence; and/or processing the frequency domain main sequence for generating the frequency domain subcarrier scheduled processing rules, The predetermined sequence generation rules include any one or a combination of the following: generated based on a different sequence production; and/or Generated based on the same sequence generator, and further perform cyclic shift on the generated sequence, The predetermined processing rule includes: performing phase modulation on the pre-generated sub-carriers obtained by processing based on the frequency domain main sequence according to a frequency offset value. 23. A method for receiving a leading symbol, comprising the steps of: Process the received physical frame to obtain the baseband signal; judging whether there is a preamble symbol to be received in the baseband signal; Determining the position of the received preamble symbol in the physical frame and deciphering the signaling information carried by the preamble symbol when the signaling information exists. 24. The receiving method of the preamble symbol as claimed in claim 23, characterized in that, Wherein, when judging whether there is the preamble symbol expected to be received in the baseband signal, any one of the following methods or any at least two methods can be freely combined for reliability judgment: Initial timing synchronization method, integer multiple frequency offset estimation method, precise timing synchronization method, channel estimation method and decoding result analysis method. 25. The receiving method of the preamble symbol as claimed in claim 24, characterized in that, Wherein, the fractional multiple frequency offset is estimated through the preliminary result obtained by the initial timing synchronization manner. 26. The receiving method of the preamble symbol as claimed in claim 24, is characterized in that, Wherein, when the first one of the time domain main signals in the at least one time domain main signal does not transmit signaling is known information, the initial timing synchronization method includes: Perform a differential operation through the first time-domain symbol, and perform a differential operation on the time-domain sequence corresponding to the known information, and then perform cross-correlation between the two to obtain a cross-correlation value, based on the obtained one or more of the cross-correlation Relevant values, at least for initial synchronization based on this result. 27. The receiving method of the preamble symbol as claimed in claim 24, characterized in that, Wherein, the integer multiple frequency offset estimation method is performed based on the result obtained in the initial timing synchronization method. 28. The receiving method of the preamble symbol as claimed in claim 27, characterized in that, In the step of estimating the integer multiple frequency offset, any one or a combination of the following two methods is included:. The first integer multiple frequency offset estimation method includes: after modulating all or part of the intercepted time-domain waveforms with different frequency offsets in a frequency-sweeping manner, several frequency-sweeping time-domain signals are obtained, which are then fuzzed by known frequency-domain sequences. After the known time-domain signal obtained by Liye inverse transform is slidingly correlated with each of the frequency-sweeping time-domain signals, the frequency offset value modulated by the frequency-sweeping time-domain signal with the maximum correlation peak value is an integer multiple frequency offset estimated value; and/or The second integer multiple frequency offset estimation method includes: cyclically shifting the frequency domain subcarriers obtained by intercepting the main time domain signal according to the position result of the initial timing synchronization and performing Fourier transform according to different shift values within the frequency sweep range , intercept the received sequence corresponding to the effective subcarrier, perform predetermined operations on the received sequence and the known frequency domain sequence, and then perform inverse Fourier transform, and obtain the shift based on the inverse Fourier transform results of several sets of shift values value and the estimated value of the integer multiple frequency offset, thereby obtaining the estimated value of the integer multiple frequency offset. 29. The receiving method of the preamble symbol as claimed in claim 27, characterized in that, After the integer multiple frequency offset estimation is completed, the frequency offset is compensated and then the transmission signaling is analyzed. 30. The method for receiving preamble symbols as claimed in claim 27, characterized in that, After the integer multiple frequency offset estimation is completed, when the first one of the at least one time-domain main signal does not transmit signaling and is known information, use the known signal to perform the precise timing Synchronously. 31. The method for receiving a preamble symbol according to claim 24, wherein: The channel estimation method, included in the step of analyzing the transmission signaling, includes: After the decoding of the main signal in the time domain described above is completed, the obtained decoded information is used as the transmission information, and the channel estimation is performed again in the time domain/frequency domain, and a specific operation is performed with the previous channel estimation result to obtain The new channel estimation result is used for the channel estimation of the signaling analysis of the main signal in the next time domain. 32. The method for receiving a preamble symbol according to claim 23, wherein: When judging whether there is a preamble symbol as claimed in claim 15 in the baseband signal, the judging step includes an initial timing synchronization method. 33. The method for receiving a preamble symbol according to claim 32, wherein: Wherein, in the initial timing synchronization method, when the sending end selects different starting points of the second part from the first part to mark the emergency broadcast, the emergency broadcast is parsed by any one of the following or a free combination of any two: A different delay relationship for the same content between the third part and the second part; and Different delay relationships for the same content between the first part and the second part. 34. The receiving method of the preamble symbol as claimed in claim 32, characterized in that, Wherein, the initial timing synchronization method includes: When it is detected that the time-domain symbol has the three-segment structure, delay sliding is performed using the unique processing relationship and/or modulation relationship of each of the first three-segment structure and/or the second three-segment structure Autocorrelation is used to obtain one or more sets of accumulated correlation values, and after a specific mathematical operation is performed based on one or more sets of the correlation values, at least preliminary timing synchronization is performed based on the values of the operation results. 35. The method for receiving a preamble symbol according to claim 24, wherein: When the sent preamble symbol contains the following two situations: It is known that a first of said at least one time-domain body signal is not used for signaling; and detecting that said time-domain body signal has said three-segment structure, The initial timing synchronization is accomplished based on any one or a combination of the following two, The first method of initial timing synchronization: performing a differential operation through the first time-domain symbol, and performing a differential operation on the time-domain sequence corresponding to the known information, and then performing cross-correlation between the two to obtain a cross-correlation value, performing initial synchronization based on a first computed value derived from one or more of said cross-correlation values; and The second method of initial timing synchronization: using the unique processing relationship and/or modulation relationship of each of the first three-segment structure and/or the second three-segment structure to perform delayed sliding autocorrelation to obtain a set of or multiple sets of accumulated correlation values, and then perform a specific mathematical operation based on one or more sets of the correlation values to obtain the second calculation value to complete the preliminary timing synchronization, Wherein, when the initial timing synchronization is completed based on two methods, the obtained first operation value and the second operation value are then subjected to a weighted operation, and the initial timing synchronization is completed based on the weighted operation value. 36. The method for receiving a preamble symbol according to claim 26 or 34 or 35, wherein: Wherein, the fractional multiple frequency offset estimation is performed simultaneously on the result obtained by the method of the initial timing synchronization method. 37. The method for receiving a preamble symbol according to claim 23, wherein: In the step of deciphering the signaling information carried by the preamble symbol, including: Using all or part of the time domain waveform of the preamble symbol and/or a frequency domain signal obtained by Fourier transforming all or part of the time domain waveform of the preamble symbol to decipher the signaling information carried by the preamble symbol . 38. The method for receiving a preamble symbol according to claim 37, wherein: In the step of parsing signaling information, Using the known signaling sequence set and/or all possible frequency domain modulation frequency offset values generated by using all possible different root values and/or different frequency domain shift values of the frequency domain main sequence sent by the sending end to Analyze signaling. 39. The method for receiving a preamble symbol according to claim 37, wherein: When the generation process of the frequency-domain subcarrier is based on different sequence generation formulas and/or based on the same sequence generation formula, when the generated sequence is further cyclically shifted, Performing specific mathematical operations on the frequency-domain signaling subcarriers, channel estimates, and all possible frequency-domain main sequences to perform signaling analysis, Wherein, the specific mathematical operation includes any of the following: A maximum likelihood correlation operation combined with channel estimation; or After performing channel equalization on the frequency-domain signaling sub-carriers, the channel estimation value is then correlated with all possible frequency-domain main sequences, and the maximum correlation value is selected as a decoding result of signaling analysis. 40. The method for receiving a preamble symbol according to claim 37, wherein: Wherein, when the phase modulation of the pre-generated sub-carrier is carried out with the frequency offset value in the generation process of the frequency-domain sub-carrier, Use any one or a combination of at least two of the following three signaling methods for signaling analysis: The first analytical signaling method: After the frequency domain signal is taken out of the effective subcarriers for channel equalization, it is matched/divided with each known sequence of the known signaling set, and the frequency offset value in the frequency domain is directly calculated or inverse Fu Lie operations; and/or The second analytical signaling method: when it is determined that the frequency-domain signaling set of each time-domain symbol has only one known sequence and the known sequences of the previous and subsequent symbols are also the same, only the delay correlation between the previous and subsequent time-domain symbols is solved. time domain cyclic shift values for resolution signaling; and/or The third analytical signaling method: correspondingly cross-correlate the time-domain received signal of each time-domain symbol with the known time-domain sequences corresponding to the known frequency-domain sequences before all possible modulation frequency offsets, and the cross-correlation Values are pre-determined, and then the cross-correlation values of the pre- and post-symbols after the pre-determined processing are further correlated with the delay correlation of the pre- and post-symbol interval lengths according to the predetermined symbol length relationship of the time-domain symbols. Time-domain cyclic shift values resolve transmission signaling. 41. A device for generating a leading symbol, comprising: a subcarrier generating unit, which generates a frequency domain subcarrier based on a frequency domain main sequence; a frequency domain transformation unit, performing an inverse Fourier transform on the frequency domain subcarrier to obtain a time domain main signal; and a time-domain processing unit, configured to generate the preamble symbol from at least one time-domain symbol formed based on the time-domain main signal, Wherein, the subcarrier generation unit includes: a sequence generation module for generating a predetermined sequence generation rule of the frequency domain main sequence; and/or processing the frequency domain main sequence to generate the frequency domain subcarrier The carrier processing module of the predetermined processing rule, The predetermined sequence generation rule in the sequence generation module includes any one or combination of the following: generated based on a different sequence production; and/or Generated based on the same sequence generator, and further perform cyclic shift on the generated sequence, The predetermined processing rule in the carrier processing module includes: performing phase modulation on the pre-generated sub-carriers obtained by processing based on the main sequence in the frequency domain according to a frequency offset value. 42. A device for generating a leading symbol, comprising: A time-domain generation unit generates time-domain symbols having the following three-segment structure based on the time-domain subject signal; and a preamble generation unit, configured to generate the preamble symbol based on at least one of the time domain symbols, Wherein, the first type of three-segment structure includes: the main signal in the time domain, a prefix generated by selecting a part of the end of the main signal in the time domain, and a suffix generated by selecting a part within the range of the prefix based on the main signal in the time domain ; The second three-segment structure includes: the time-domain main signal, a prefix generated by selecting a part from the end of the time-domain main signal, and a super-prefix generated by selecting a part within the prefix range based on the time-domain main signal, The leading symbols generated by the leading generation unit include: said time-domain symbols having said first three-segment structure; or a time-domain symbol having said second three-segment structure; or A free combination of several time-domain symbols having the first three-segment structure and/or several time-domain symbols having the second three-segment structure arranged in no particular order. 43. A device for receiving a preamble symbol, comprising: The baseband processing unit processes the received physical frame to obtain a baseband signal; A judging unit, judging whether there is a preamble symbol to be received in the baseband signal; The signaling parsing unit determines the position of the received preamble symbol in the physical frame and decodes the signaling information carried by the preamble symbol when the signaling information exists.