CN107645364B - Complementary encoding method and device, complementary decoding method and device, OvXDM system - Google Patents

Abstract

The application discloses a complementary coding method and device, a complementary decoding method and device, and an OvXDM system, wherein the first segment of a complex modulation envelope waveform is superposed to the tail segment in the coding process, or the tail segment is superposed to the first segment, so as to generate a complementary complex modulation envelope waveform, or the first segment of a digital signal in a first domain is superposed to the tail segment in the decoding process, or the tail segment is superposed to the first segment, so as to generate a complementary digital signal, so that the decoded data are completely superposed, the problem of higher error rate of the last symbols in the traditional technology does not exist, meanwhile, the length of the data is not required to be very large, a stable decoding path can be obtained even if the length of the data is short, the decoding processing time delay is reduced, and the real-time performance and the transmission speed of the system are improved.

Description

Complementary encoding method and device, complementary decoding method and device, OvXDM system

technical field

The present application relates to the field of signal processing, and in particular to a complementary encoding method and device, a complementary decoding method and device, and an OvXDM system.

Background technique

Overlapping multiplexing system, whether it is overlapping time division multiplexing (OvTDM, Overlapped Time Division Multiplexing) system, overlapping frequency division multiplexing (OvFDM, Overlapped Frequency Division Multiplexing) system or overlapping code division multiplexing (OvCDM, Overlapped code Division Multiplexing) system, time-frequency Two-dimensional overlapping multiplexing system (OvHDM, Overlapped Hybrid Division Multiplexing) and space division overlapping multiplexing system (Overlapped Space Division Multiplexing) are in the shape of a parallelogram when superimposed in the encoding process, as shown in Figure 1. For an overlapping multiplexing For an overlapping multiplexing system of K, there will be a section of "first" and "tail" that do not overlap K times during the encoding and overlaying process, and for an input digital sequence with a length of N, the length becomes N+K-1 after overlapping encoding , where the lengths of the "header" and "tail" that have not been fully overlapped K times are both K-1. Since the length of the useful information flow is N, generally only data with a length of N is sent at the sending end, for example, " "Tail", and then decode the data with the "tail" removed at the receiving end; or send the complete data with a length of N+K-1 at the sending end, and then decode the "tail" of the data at the receiving end Without decoding, the above two methods will make the bit error rate of the last few symbols higher.

In addition, due to the overlapping coding constraints of the overlapping multiplexing system, a stable decoding path will only appear when the data depth is at least 4K to 5K in the decoding process. If it is small, since the "first" and "tail" are not completely overlapped K times, the stable path may not appear in the decoding process, and the data has already been decoded, which will greatly increase the bit error rate of the system; on the other hand, If the length N of the transmitted data is large, although the requirement of a stable decoding path is met, it will increase the decoding output delay and affect the processing time of the system.

Contents of the invention

In order to solve the above problems, the present application provides a complementary encoding method and device, a complementary decoding method and device, and an OvXDM system.

According to the first aspect of the present application, the present application provides a complementary encoding method, which is applicable to the OvXDM system, comprising the following steps:

generating an initial envelope waveform in the first domain according to the design parameters;

shifting the initial envelope waveform on the first domain at predetermined intervals according to the number of times of overlapping multiplexing, to obtain shifted envelope waveforms at fixed intervals;

Multiply the digital signals in the input sequence with their corresponding shifted envelope waveforms to obtain each modulated envelope waveform;

superimposing the modulation envelope waveforms on the first domain to obtain a complex modulation envelope waveform on the first domain, wherein the complex modulation envelope waveform includes an insufficiently superimposed first section, a fully superimposed main section, and An insufficiently superimposed tail section;

The first segment of the complex modulation envelope waveform is superimposed on the tail segment, or the tail segment is superimposed on the first segment to generate a complementary complex modulation envelope waveform, and then subsequent processing is performed.

According to the second aspect of the present application, the present application provides a complementary decoding method, which is applicable to the OvXDM system, comprising the following steps:

receiving a signal and processing the received signal to obtain a digital signal in a first domain, wherein the digital signal in the first domain includes an insufficiently superimposed first segment, a sufficiently superimposed body segment, and an insufficiently superimposed tail segment;

superimposing the first segment of the digital signal in the first domain to the tail segment, or superimposing the tail segment to the first segment, to generate a complementary digital signal;

The digital signal is decoded according to a certain decoding algorithm.

According to the third aspect of the present application, the present application provides a complementary encoding device, which is suitable for the OvXDM system, including:

A waveform generating module, configured to generate an initial envelope waveform in the first domain according to design parameters;

A shift module, configured to shift the initial envelope waveform on the first domain at predetermined intervals according to the number of times of overlapping multiplexing, to obtain shifted envelope waveforms at fixed intervals;

The multiplication module is used to multiply the digital signals in the input sequence with their corresponding shifted envelope waveforms to obtain each modulated envelope waveform;

A superimposition module, configured to superimpose the modulation envelope waveforms on the first domain to obtain complex modulation envelope waveforms on the first domain, wherein the complex modulation envelope waveforms include insufficiently superimposed first segments, sufficient Superimposed body segments and insufficiently superimposed tail segments;

The complementary module is used for superimposing the first segment of the complex modulation envelope waveform to the tail segment, or superimposing the tail segment to the first segment, so as to generate a complementary complex modulation envelope waveform.

According to the fourth aspect of the present application, the present application provides a complementary decoding device, which is suitable for the OvXDM system, including:

The receiving module is used to receive the signal and process the received signal to obtain the digital signal in the first domain, wherein the digital signal in the first domain includes an insufficiently superimposed first section, a fully superimposed body section, and an insufficiently superimposed end of

a complementary module, configured to superimpose the first segment of the digital signal in the first domain to the tail segment, or the tail segment to the first segment, to generate a complementary digital signal;

The decoding module is used to decode the digital signal according to a certain decoding algorithm.

According to a fifth aspect of the present application, the present application provides an OvXDM system, including the above-mentioned complementary encoding device, or including the above-mentioned complementary decoding device.

The beneficial effect of this application is:

According to the complementary encoding method and device, complementary decoding method and device, and OvXDM system implemented above, since the first segment of the complex modulation envelope waveform is superimposed to the tail segment, or the tail segment is superimposed to the first segment during the encoding process, to generate complementary complex modulation envelope waveform, or in the decoding process, the first segment of the digital signal in the first domain is superimposed to the tail segment, or the tail segment is superimposed to the first segment to generate a complementary digital signal, so that the decoded The data is completely overlapped, so there is no problem of high bit error rate of the last few symbols in the traditional technology, and the length of the data is not required to be large, and stable translation can be obtained even if the length of the data is short The code path reduces the decoding processing delay and improves the system processing time accuracy and transmission speed.

Description of drawings

Figure 1 is a schematic diagram of data superposition in an overlapping multiplexing system;

FIG. 2 is a schematic flowchart of a complementary encoding method in the first embodiment of the present application;

FIG. 3 is a schematic structural diagram of a complementary encoding device according to the first embodiment of the present application;

FIG. 4 is a schematic flowchart of a complementary decoding method according to a second embodiment of the present application;

FIG. 5 is a schematic structural diagram of a complementary decoding device according to a second embodiment of the present application;

FIG. 6 is a schematic structural diagram of a transmitting end of a traditional OvFDM system;

Figure 7(a) is a block diagram of a signal receiving end of a traditional OvFDM system;

Figure 7(b) is a block diagram of the traditional OvFDM system received signal detection

FIG. 8 is a schematic diagram of complementary superposition of an OvFDM system in an embodiment of the present application;

Fig. 9 is a code tree diagram of a traditional OvFDM system;

Figure 10 is a node state transition diagram of a traditional OvFDM system;

Fig. 11 is a trellis diagram of a traditional OvFDM system;

Fig. 12 is a schematic diagram of complementary superposition of data in an example of the present application;

Fig. 13 is a schematic diagram of detection of decoding complementary data in an example of the present application;

FIG. 14 is a schematic structural diagram of a transmitting end of a traditional OvTDM system;

Figure 15(a) is a schematic diagram of a traditional OvTDM system preprocessing unit;

Figure 15(b) is a schematic diagram of a traditional OvTDM system sequence detection unit;

FIG. 16 is a schematic diagram of complementary superposition of the OvTDM system in an embodiment of the present application;

Figure 17 is a code tree diagram of a traditional OvTDM system;

Figure 18 is a node state transition diagram of a traditional OvTDM system;

Figure 19 is a trellis diagram of a traditional OvTDM system;

Fig. 20 is a schematic diagram of data complementary superposition in another example of the present application;

FIG. 21 is a schematic diagram of detection of decoding complementary data in another example of the present application.

detailed description

The present application will be described in further detail below through specific embodiments in conjunction with the accompanying drawings.

In this application, OvXDM (Overlapped X Division Multiplexing) is used to refer to the overlapping multiplexing system, where X can represent time T, frequency F, code domain C, space S or hybrid H, etc. Correspondingly, the OvXDM system at this time is OvTDM system, OvFDM system, OvCDM system, OvSDM system or OvHDM system. The inventive idea of this application is to superimpose the "head" and "tail" of the data encoded by overlapping multiplexing at the sending end or the receiving end, so that before the data is decoded according to a certain decoding algorithm, all data symbols All have been fully superimposed, so that on the one hand, the problem of high bit error rate of the last few symbols in the traditional technology is solved, and the bit error rate of the system is greatly reduced. On the other hand, the length of the data can not be required to be large , even if the length of the data is short, a stable decoding path can be obtained, which reduces the decoding processing delay and improves the system processing time precision and transmission speed. The present application discloses an OvXDM system, which includes the complementary encoding device disclosed in Embodiment 1 below, or includes the complementary decoding device disclosed in Embodiment 2 below.

Embodiment one

Please refer to FIG. 2 , this embodiment discloses a complementary coding method applicable to the OvXDM system, including steps S01-S09.

Step S01. Generate an initial envelope waveform in the first domain according to design parameters.

Step S03 , shifting the initial envelope waveform on the first domain at predetermined intervals according to the number of times of overlapping multiplexing, to obtain shifted envelope waveforms at fixed intervals.

Step S05, multiplying the digital signals in the input sequence with their corresponding shifted envelope waveforms to obtain each modulated envelope waveform;

Step S07: Superimpose the modulation envelope waveforms on the first domain to obtain complex modulation envelope waveforms on the first domain, wherein the complex modulation envelope waveforms include the first segment that is not fully superimposed, the fully superimposed Body segments and tail segments that are not sufficiently superimposed.

Step S09 , superimposing the first segment of the complex modulation envelope waveform to the tail segment, or superimposing the tail segment to the first segment, to generate a complementary complex modulation envelope waveform, and then perform subsequent processing.

In an embodiment, the OvXDM system is an OvFDM system, and correspondingly, the first domain at this time is the frequency domain. In step S09 , the subsequent processing of the generated complementary complex modulated envelope waveform may, in one embodiment, be transformed into a complementary complex modulated envelope waveform in the time domain by, for example, inverse Fourier transform for transmission.

In an embodiment, the OvXDM system is an OvTDM system, and correspondingly, the first domain at this time is the time domain. In step S09, the subsequent processing of the generated complementary complex modulation envelope waveform, in one embodiment, transmits it.

Correspondingly, referring to FIG. 3, this embodiment also proposes a complementary encoding device suitable for OvXDM systems, including a waveform generation module 01, a shift module 03, a multiplication module 05, a superposition module 07, and a complementary module 09. In an implementation In an example, a subsequent processing module 11 may also be included.

The waveform generation module 01 is used to generate an initial envelope waveform in the first domain according to design parameters.

The shifting module 03 is used for shifting the initial envelope waveform on the first domain at predetermined intervals according to the times of overlapping multiplexing, to obtain shifted envelope waveforms at fixed intervals.

The multiplication module 05 is used to multiply the digital signals in the input sequence with their corresponding shifted envelope waveforms to obtain each modulated envelope waveform.

The superposition module 07 is used to superimpose each modulation envelope waveform on the first domain to obtain a complex modulation envelope waveform on the first domain, wherein the complex modulation envelope waveform includes an insufficiently superimposed first segment, a fully superimposed Body segments and tail segments that are not sufficiently superimposed.

The complementary module 09 is used to superimpose the first segment of the complex modulation envelope waveform to the tail segment, or the tail segment to the first segment to generate a complementary complex modulation envelope waveform;

The subsequent processing module 11 is used for performing subsequent processing on the complementary complex modulation envelope waveform.

In an embodiment, when the OvXDM system is an OvFDM system, correspondingly, the first domain is the frequency domain. Therefore, the subsequent processing of the generated complementary complex modulation envelope waveform by the subsequent processing module 11 may, in one embodiment, be transformed into a complementary complex modulation envelope waveform in the time domain by, for example, inverse Fourier transform for transmission.

In an embodiment, the OvXDM system is an OvTDM system, and correspondingly, the first domain at this time is the time domain. The subsequent processing module 11 performs subsequent processing on the generated complementary complex modulation envelope waveform, and in one embodiment, transmits it.

Embodiment two

As shown in FIG. 4 , this embodiment proposes a complementary decoding method suitable for the OvXDM system, including steps S31-S35.

Step S31, receiving a signal and processing the received signal to obtain a digital signal in the first domain, wherein the digital signal in the first domain includes an insufficiently superimposed first section, a fully superimposed main section, and an insufficiently superimposed tail part.

In an embodiment, the OvXDM system is an OvFDM system, and accordingly, the first domain is a frequency domain. In one embodiment, specifically, in step S31, first form symbol synchronization for the received signal in the time domain; then perform digital processing on the signal in each symbol time interval, including sampling and quantization, and convert it into a received digital signal sequence; Then Fourier transform is performed on the received digital signal sequence of each time symbol interval to form the actual received signal spectrum of each time symbol interval; then the actual received signal spectrum of each time symbol interval is divided into subcarrier spectrum intervals in the frequency domain Obtain the segmented spectrum of the actual received signal.

In an embodiment, the OvXDM system is an OvTDM system, and correspondingly, the first domain is a time domain. In one embodiment, specifically, in step S31, the received signal is first synchronized, including carrier synchronization, frame synchronization and symbol time synchronization, etc.; then according to the sampling theorem, the received signal in each frame is digitized; and then Cut the received waveform according to the waveform sending time interval.

Step S33 , superimposing the first segment of the digital signal in the first domain to the last segment, or superimposing the last segment to the first segment, so as to generate a complementary digital signal.

Step S35, decoding the digital signal according to a certain decoding algorithm. The decoding algorithm may use an existing or future decoding algorithm, for example, the decoding algorithm may be a Viterbi decoding algorithm, an iterative decoding algorithm, and the like.

In an embodiment, the OvXDM system is an OvFDM system, and accordingly, the first domain is a frequency domain.

In an embodiment, the OvXDM system is an OvTDM system, and correspondingly, the first domain is a time domain.

In an embodiment, the OvXDM system is an OvCDM system, and correspondingly, the first domain is a code division domain.

In an embodiment, the OvXDM system is an OvSDM system, and accordingly, the first domain is a spatial domain.

In one embodiment, the OvXDM system is an OvHDM system, and accordingly, the first domain is a hybrid domain

Correspondingly, as shown in FIG. 5 , this embodiment also proposes a complementary decoding device suitable for an OvXDM system, including a receiving module 31 , a complementary module 33 and a decoding module 35 .

The receiving module 31 is used to receive the signal and process the received signal to obtain a digital signal in the first domain, wherein the digital signal in the first domain includes an insufficiently superimposed first section, a fully superimposed main section, and an insufficiently superimposed of the tail section.

The complementary module 33 is configured to superimpose the first segment of the digital signal in the first domain to the last segment, or the last segment to the first segment, so as to generate a complementary digital signal.

The decoding module 35 is used for decoding the digital signal according to a certain decoding algorithm. The decoding algorithm may use an existing or future decoding algorithm, for example, the decoding algorithm may be a Viterbi decoding algorithm, an iterative decoding algorithm, and the like.

Next, the above-mentioned embodiment will be explained and illustrated with two practical examples.

The first example may wish to illustrate with the OvFDM system.

The existing OvFDM system overlaps the data in a parallelogram shape, and there are a "first segment" and a "tail segment" before and after the encoded data, and the shape is an upper triangle and a lower triangle, which are just complementary. We move the "tail section" of the encoded data to the position of the "first section", or move the "first section" to the position of the "tail section", that is, the lower triangle and the upper triangle are complementary superimposed to form a rectangular shape, which can be We call this overlapping a complementary OvFDM system. The complementary data is in the shape of a rectangle, and each data is overlapped K times, thus solving the problems existing in the prior art in the background art.

The encoding process is shown in Figure 6:

(1) Generate the initial envelope waveform H(f) in the frequency spectrum according to the design parameters.

(2) After the initial envelope waveform H(f) designed in (1) is shifted by a specific carrier spectrum interval ΔB, other subcarrier envelope waveforms H(f-i×ΔB) with spectrum intervals of ΔB are formed. Wherein, the spectrum interval is the subcarrier spectrum interval ΔB, wherein the subcarrier spectrum interval ΔB=B/K, B is the bandwidth of the initial envelope waveform, and K is the number of overlapping multiplexing. In an embodiment, the subcarrier spectrum interval ΔB is greater than or equal to the reciprocal of the system sampling.

(3) Multiply the symbol X _i to be transmitted with the corresponding subcarrier envelope waveform H(fi×ΔB) generated in (2) to obtain the modulated envelope waveform X _i H(fi ×ΔB).

(4) Superimpose each modulation envelope waveform formed in (3) by X _i H (fi×ΔB) to form a complex modulation envelope waveform. The complex modulation envelope waveform superposition process can be expressed as:

(5) Perform inverse discrete Fourier transform on the complex modulation envelope waveform generated in (4), and finally form the complex modulation envelope waveform in the time domain. The transmitted signal can be expressed as: Signal(t) _TX = ifft(S(f) ).

The above is the encoding process of the traditional OvFDM system. The superposition process in (4) is reflected in the coding of the data, as shown in Fig. 1 . For data with a symbol length of N, after the above modulation and encoding, the length becomes N+K-1, which has a length of K-1 without K-time superposition of the first segment, and a length of K-1 The tail segment of which has not undergone K times of stacking.

The decoding process is shown in Figure 7:

The transmitting end transmits the coded and modulated signal through the antenna, the signal is transmitted in the wireless channel, and the receiving end performs matching filtering on the received signal. Since the received signal is a time domain signal, it is necessary to perform Fourier transform on the time domain signal first. Convert to frequency domain signal, and then decode the signal. Inverse Fourier transform and Fourier transform in OvFDM system both involve the setting of the number of sampling points. The number of sampling points of the two should be consistent, and the value is 2 ⁿ . Then the signals are sampled and decoded respectively, and finally the output bit stream is judged. specifically:

(6) Symbol synchronization is formed in the time domain for the received signal.

(7) Perform digital processing on the signals of each symbol time interval, including sampling and quantization, and convert them into received digital signal sequences.

(8) Fourier transform is performed on the received digital signal sequence of each time symbol interval to form the actual received signal spectrum of each time symbol interval. Its expression is: Signal (f) _RX = fft (s (t)).

(9) Segment the actual received signal spectrum of each time symbol interval in the frequency domain with the subcarrier spectrum interval ΔB to obtain the segmented spectrum of the actual received signal.

(10) Decoding the cut spectrum waveform according to a certain decoding algorithm.

The above is the encoding process of the traditional OvFDM system. During the decoding process, the data in the tail segment will not be decoded, because the length of the useful information stream is N, so only the length of the transmitted information is N+K-1 The first N data in the data are decoded.

The inventive idea of the present application is to move the first segment of the above-mentioned coded data with a length of N+K-1 to the tail segment, and superimpose with the original tail segment to form a new tail segment, thereby forming a new data length of The complementary coded data of N, of course, can also move the tail segment to the first segment for superimposition, as shown in FIG. 8 . The above-mentioned moving process can be put into the programming process, and can also be put into the decoding process. In one embodiment, if the above moving process is included in the programming process, before (5), the first segment/end segment of the data can be moved to the end segment/first segment for superimposition. In one embodiment, if the above-mentioned moving process is put into the decoding process, before (10), the first segment/tail segment of the data can be moved to the tail segment/first segment for superimposition.

The decoding algorithm in (10) includes many kinds, such as Viterbi decoding algorithm and iterative decoding algorithm. Let's take the Viterbi decoding method as an example for illustration.

After adopting this application, when proceeding to the decoding of (10), the sequence y _i (i=1～N) whose length is N is decoded, and each symbol is the result of superposition of K symbols, that is The complementary data sequence is decoded. .

First, generate the possible states after superposition of K-way symbols, that is, ideal symbols S _theory (j), j= ^{1˜2 K} , 2 ^K types in total.

叠加后对应的表示形式为

如果用+1来表示叠加后的输出电平，则共计包含K+1种符号电平，依次为:±K、±(K-2)、...±(K-2^k)，k＝1～K/2，记为Y_theory(index),index＝1～K+1。The K-road notation is expressed as:

The corresponding expression after superposition is

If +1 is used to represent the superimposed output level, then a total of K+1 symbol levels are included, followed by: ±K, ±(K-2), ... ±(K-2 ^k ), k= 1～K/2, recorded as Y _theory (index), index=1～K+1.

对应输出的符号电平为±3、±1共四种，即Y_theory(1)＝-3，Y_theory(2)＝-1，Y_theory(3)＝1，Y_theory(4)＝3。For example, when K=3, there are a total of 8 states after the symbols are superimposed, which are:

The corresponding output symbol levels are ±3 and ±1, a total of four types, namely Y _theory (1)=-3, Y _theory (2)=-1, Y _theory (3)=1, Y _theory (4)=3 .

Second, calculate the measure distance of the current symbol.

当p＝2时，即为欧式距离，欧式距离是两个信号之间的真实距离，能够真实的反应实际信号和理想信号之间的距离，其定义为

本实施案例中我们以欧式距离为例说明。The metric distance represents the distance between two signals and is defined as

When p=2, it is the Euclidean distance. The Euclidean distance is the real distance between two signals, which can truly reflect the distance between the actual signal and the ideal signal. It is defined as

In this implementation case, we take the Euclidean distance as an example.

Use the current symbol y _i (i=1~N) and the generated 2 ^K kinds of ideal symbols S _theory (j) to calculate the Euclidean distance sequentially, and obtain 2 ^k Euclidean distances. recorded as

Third, calculate the cumulative distance of the current symbol.

When comparing the Euclidean distance, if only the Euclidean distance between the current symbol and the theoretical symbol is compared, as the decoding depth increases, the optimal path may deviate, resulting in a decrease in the final decoding success rate.

Since the symbol superposition process itself is that K symbols overlap each other, and the symbols are highly correlated, we use the sum of the current Euclidean distance and the previous accumulated Euclidean distance to judge, so that as the decoding depth increases, more accurate judgments can be made. The optimal path improves the decoding success rate.

The cumulative Euclidean distance expression is written as:

Among them, D _{i, j} represent the Euclidean distance after the accumulation of the current symbol, and since the first symbol has no accumulated distance, only its current distance d _current is calculated. i represents the index of the current symbol in the entire received symbol sequence, and j represents the index of the accumulated symbol, and there are 2 ^K types in total.

D _{prev_i-1} represents the cumulative Euclidean distance after screening before the current node y _i , totaling 2 ^K-1 , that is, 2 ^K-1 kinds of D _{prev_i-1} are selected from 2 ^K kinds of D _i-1,j . Since only the sign of the first path is different in 2 ^K states, only 2 ^K-1 Euclidean distances and 2 ^K-1 optimal paths are retained in the end, so D _{prev_i-1} has 2 ^K-1 Euclidean distances in total. Due to the first symbols have no accumulative distance, so D _{prev_i-1} does not exist.

The value of d _current is always the Euclidean distance between the current symbol and the theoretical symbol.

Fourth, choose the best path

After the third step above, 2 ^K kinds of cumulative Euclidean distance D _i,j and path _j are obtained, j=1～2 ^K , because these 2 ^K kinds of paths can be roughly divided into two parts, that is, the previous state is Enter +1 or enter -1. Therefore, we divide the 2 ^K paths into two parts, each part contains 2 ^K-1 paths, and divide the corresponding cumulative Euclidean distance into two parts.

The cumulative Euclidean distance of each row corresponding to each part is compared in pairs to find the smallest one, that is, the first row of the first part is compared with the first row of the second part, and the second row of the first part is compared with the second row of the second part, so that By analogy, find the minimum Euclidean distance for each row, record the cumulative Euclidean distance D _i,j corresponding to this row, and mark it as the new filtered cumulative Euclidean distance D _{prev_i} , which is the accumulation of the i+1 node Euclidean distance D _i+ 1 _{, used for the cumulative Euclidean distance of the first i nodes in j} , while retaining the symbol path path corresponding to the cumulative Euclidean distance, inputting +1 or -1 for the current symbol according to the transfer path, and corresponding Increment the depth of path by 1.

After the above steps, 2 ^K-1 Euclidean distances D _{prev_i} and corresponding 2 ^K-1 symbol paths are obtained.

Fifth, the last symbol processing

According to the first to fourth steps, the remaining symbols are processed sequentially. When the last symbol y ^N is processed, 2 ^K-1 Euclidean distances d _j and their corresponding 2 ^K-1 symbol path paths are obtained after screening. When the depth of the path is N. Sort the 2 ^K-1 Euclidean distances from small to large, find the Euclidean distance with the smallest cumulative distance, and obtain its corresponding index. According to its index, take out the decoding symbol sequence corresponding to the index of path, which is the final translation code result.

Denote the decoded sequence as S _decode (i), i=1~N. Comparing the decoding sequence S _decode (i) with the input sequence _xi can check whether the decoding result is correct, and calculate the bit error rate of the system at the same time.

For the decoding process, refer to K=3 in accompanying drawing 9, the code tree diagram of overlapping time-division input-output relationship, the node state transition diagram in accompanying drawing 10, and K=3 in accompanying drawing 11, the trellis diagram of OvFDM system.

In general, since the length of the data to be decoded is long, and with the deepening of the decoding depth, the accumulation distance becomes larger and larger, if the system decodes all the data and then performs decoding output, it will consume more system resources. , so a better processing method is adopted for the storage capacity of the path and the storage of the distance. Generally, the path storage length is selected to be 4K to 5K. At this time, if the path memory is full and the decoding judgment output has not yet been forced to be judged, the initial node with the same path will be output first; as the decoding depth deepens, the accumulated The distance will also become larger and larger, and the accumulated distance can be stored as a relative distance, that is, a reference distance is defined, and its value depends on different systems. The distance storage records the second distance of each path relative to the reference distance Relative value, compared by relative distance when screening the best path.

For example, in this case, we use a square wave as the multiplexed waveform to illustrate the encoding and decoding process. Set the number of overlapping multiplexing K=3, the length of the input sequence N=9, the symbol sequence x _i ={-1,+1,-1,+1,+1,+1,-1,+1,-1}, After being encoded by the OvFDM system, the length of the output sequence becomes 11 (N+K-1), and the output symbol sequence s'(t)={-1,0,-1,+1,+1,+3,+1,+ 1,-1,0,-1}, the superposition process of the symbols in this case is shown in Figure 12, it can be seen from the figure that the first two and the last two symbols in the superimposed symbol sequence are not 3-way superposition, so We perform complementary superposition of these two parts of the signal and place them in front of the middle symbol to form a complementary OvFDM mode. The output symbol sequence after complementary superposition is s(t)={-1,-1,-1,+1,+1 ,+3,+1,+1,-1}. The coded signal is transmitted through the actual channel, and the symbol sequence received at the receiving end will have deviation, which is denoted as y _i , where i=1~9. The sequence of symbols received in this case is:

y _i ={-0.9155,-1.4137,0.0825,0.5699,0.5244,3.7270,0.2254,1.9963,-2.1995};

All symbols are decoded one by one according to the aforementioned Viterbi decoding method, and the symbol detection path in the decoding process is shown in FIG. 13 . After decoding all symbols, four optimal paths and their corresponding Euclidean distances are obtained, as follows:

path ₁ : {-1,1,-1,1,1,1,-1,1,1};

path ₂ : {-1,1,-1,1,1,1,-1,1,-1};

path ₃ : {-1,1,-1,1,1,1,-1,-1,1};

path ₄ : {-1,1,-1,1,1,1,-1,-1,-1};

The corresponding Euclidean distances are d ₁ =8.1839, d ₂ =6.1839, d ₃ =8.1839, d ₄ =7.7848. After comparing these four distances, the Euclidean distance of d ₂ is the smallest, and the corresponding path path ₂ is selected is the output sequence of symbols. That is, we think that the output symbol sequence S _decode ={-1,1,-1,1,1,1,-1,1,-1}, and the input symbol sequence x _i ={-1,+1,- 1,+1,+1,+1,-1,+1,-1}, comparing the sequences of S _decode and _xi are exactly the same, then the decoding result is correct.

The second example may wish to illustrate with the OvTDM system.

The existing OvTDM system overlaps the data in a parallelogram shape, and there are a section of "first section" and "tail section" before and after the encoded data, and the shape is an upper triangle and a lower triangle, which are just complementary. We move the "tail section" of the encoded data to the position of the "first section", or move the "first section" to the position of the "tail section", that is, the lower triangle and the upper triangle are complementary superimposed to form a rectangular shape, which can be This overlap is called a complementary OvTDM system. The complementary data is in the shape of a rectangle, and each data is overlapped K times, thus solving the problems existing in the prior art in the background art.

The encoding process is shown in Figure 14:

(1) Generate the initial envelope waveform h(t) in the time domain according to the design parameters.

(2) After the envelope waveform h(t) designed in (1) is shifted by a specific time, an offset envelope waveform h(t-i×ΔT) of the transmitted signal at other times is formed.

(3) Multiply the symbol _xi to be transmitted by the offset envelope waveform h(ti×ΔT) generated in (2) at the corresponding time to obtain the modulation envelope waveform _xi h(ti×ΔT) at each time.

(4) The modulation envelope waveform x _i h (ti×ΔT) at each time point formed in (3) is superimposed to form a complex modulation envelope waveform for transmission. The complex modulation envelope waveform can be expressed as follows:

The above is the encoding process of the traditional OvTDM system. The superposition process in (4) is reflected in the coding of the data, as shown in Fig. 1 . For data with a symbol length of N, after the above modulation and encoding, the length becomes N+K-1, which has a length of K-1 without K-time superimposed first segment, and a length of K-1 The tail segment of , which has not undergone K times of stacking. The data in Figure 1 is arranged in a parallelogram, the triangle at the left end is the "first data", the triangle at the right is the "tail data", and the data in the middle is fully superimposed.

The decoding process is shown in Figure 15:

The transmitting end transmits the coded and modulated signal through the antenna, and the signal is transmitted in the wireless channel. The receiving end performs matching filtering on the received signal, and then samples and decodes the signal respectively, and finally judges and outputs the bit stream. specifically:

(5) Synchronize the received signal first, including carrier synchronization, frame synchronization, symbol time synchronization, etc.

(6) According to the sampling theorem, digitalize the received signal in each frame.

(7) Cut the received waveform according to the waveform sending time interval.

(8) Decode the cut waveform according to a certain decoding algorithm.

The above is the encoding process of the traditional OvTDM system. During the decoding process, the data in the tail segment will not be decoded, because the length of the useful information stream is N, so only the length of the transmitted information is N+K-1 The first N data in the data are decoded.

The inventive idea of the present application is to move the first segment of the above-mentioned coded data with a length of N+K-1 to the tail segment, and superimpose with the original tail segment to form a new tail segment, thereby forming a new data length of The complementary coded data of N, of course, can also move the tail segment to the first segment for superimposition, as shown in FIG. 16 . The above-mentioned moving process can be put into the programming process, and can also be put into the decoding process. In one embodiment, if the above moving process is included in the programming process, then in (4), the first/last segment of the data can be moved to the last/first segment for superimposition. In an embodiment, if the above-mentioned moving process is put into the decoding process, before (8), the first segment/tail segment of the data can be moved to the tail segment/first segment for superimposition. ,

The decoding algorithm in (8) includes many kinds, such as Viterbi decoding algorithm and iterative decoding algorithm. Let's take the Viterbi decoding method as an example for illustration.

After adopting this application, when proceeding to the decoding of (8), the sequence y _i (i=1～N) of length N is decoded, and each symbol is the result of superposition of K-way symbols, that is The complementary data sequence is decoded.

Firstly, the possible states after superposition of K-way symbols are first generated, that is, ideal symbols S _theory (j), j= ^{1˜2 K} , 2 ^K types in total.

叠加后对应的表示形式为

如果用+1来表示叠加后的输出电平，则共计包含K+1种符号电平，依次为:±K、±(K-2)、...±(K-2^k)，k＝1～K/2，记为Y_theory(index),index＝1～K+1。The K-road notation is expressed as:

The corresponding expression after superposition is

If +1 is used to represent the superimposed output level, then a total of K+1 symbol levels are included, followed by: ±K, ±(K-2), ... ±(K-2 ^k ), k= 1～K/2, recorded as Y _theory (index), index=1～K+1.

对应输出的符号电平为±3、±1共四种，即Y_theory(1)＝-3，Y_theory(2)＝-1，Y_theory(3)＝1，Y_theory(4)＝3。For example, when K=3, there are a total of 8 states after the symbols are superimposed, which are:

The corresponding output symbol levels are ±3 and ±1, a total of four types, namely Y _theory (1)=-3, Y _theory (2)=-1, Y _theory (3)=1, Y _theory (4)=3 .

Second, calculate the measure distance of the current symbol.

当p＝2时，即为欧式距离，欧式距离是两个信号之间的真实距离，能够真实的反应实际信号和理想信号之间的距离，其定义为

本实施案例中我们以欧式距离为例说明。The metric distance represents the distance between two signals and is defined as

When p=2, it is the Euclidean distance. The Euclidean distance is the real distance between two signals, which can truly reflect the distance between the actual signal and the ideal signal. It is defined as

In this implementation case, we take the Euclidean distance as an example.

Use the current symbol y _i (i=1~N) and 2 ^K kinds of ideal symbols S _theory (j) generated in (1) to calculate the Euclidean distance sequentially, and obtain 2 ^k Euclidean distances. recorded as

Third, calculate the cumulative distance of the current symbol.

When comparing the Euclidean distance, if only the Euclidean distance between the current symbol and the theoretical symbol is compared, as the decoding depth increases, the optimal path may deviate, resulting in a decrease in the final decoding success rate.

Since the symbol superposition process itself is that K symbols overlap each other, and the symbols are highly correlated, we use the sum of the current Euclidean distance and the previous accumulated Euclidean distance to judge, so that as the decoding depth increases, more accurate judgments can be made. The optimal path improves the decoding success rate.

The cumulative Euclidean distance expression is written as:

Among them, D _{i, j} represent the Euclidean distance after the accumulation of the current symbol, and since the first symbol has no accumulated distance, only its current distance d _current is calculated. i represents the index of the current symbol in the entire received symbol sequence, and j represents the index of the accumulated symbol, and there are 2 ^K types in total.

D _{prev_i-1} represents the cumulative Euclidean distance after screening before the current node y _i , totaling 2 ^K-1 , that is, 2 ^K-1 kinds of D _{prev_i-1} are selected from 2 ^K kinds of D _i-1,j . Since only the sign of the first path is different in 2 ^K states, only 2 ^K-1 Euclidean distances and 2 ^K-1 optimal paths are retained in the end, so D _{prev_i-1} has 2 ^K-1 Euclidean distances in total. Due to the first symbols have no accumulative distance, so D _{prev_i-1} does not exist. The value of d _current is always the Euclidean distance between the current symbol and the theoretical symbol.

Fourth, choose the best path.

After the processing of the third step above, 2 ^K kinds of cumulative Euclidean distances D _i,j and path _j are obtained, j=1～2 ^K , because these 2 ^K kinds of paths can be divided into two parts, that is, the previous state is the input +1 or -1 for typing. Therefore, we divide the 2 ^K paths into two parts, each part contains 2 ^K-1 paths, and divide the corresponding cumulative Euclidean distance into two parts.

The cumulative Euclidean distance of each row corresponding to each part is compared in pairs to find the smallest one, that is, the first row of the first part is compared with the first row of the second part, and the second row of the first part is compared with the second row of the second part, so that By analogy, find the minimum Euclidean distance for each row, record the cumulative Euclidean distance D _i,j corresponding to this row, and mark it as the new filtered cumulative Euclidean distance D _{prev_i} , which is the accumulation of the i+1 node The accumulated Euclidean distance of the first i nodes in the Euclidean distance D _i+1,j is used, and the symbol path path corresponding to the accumulated Euclidean distance is reserved at the same time. For the current symbol, input +1 or -1 according to the transfer path, and the corresponding The depth of the path is increased by 1.

After the above steps, 2 ^K-1 Euclidean distances D _{prev_i} and corresponding 2 ^K-1 symbol paths are obtained.

Fifth, the last symbol processing.

According to the first to fourth steps, the remaining symbols are processed sequentially. When the last symbol y _N is processed, 2 ^K-1 Euclidean distances d _j and their corresponding 2 ^K-1 symbol path paths are obtained after screening. When the depth of the path is N. Sort the 2 ^K-1 Euclidean distances from small to large, find the Euclidean distance with the smallest cumulative distance, and obtain its corresponding index. According to its index, take out the decoding symbol sequence corresponding to the index of path, which is the final translation code result.

Denote the decoded sequence as S _decode (i), i=1~N. Comparing the decoding sequence S _decode (i) with the input sequence _xi can check whether the decoding result is correct, and calculate the bit error rate of the system at the same time.

For the decoding process, refer to K=3 in the accompanying drawing 17, the code tree diagram of the overlapping time-division input-output relationship, the node state transition diagram in the accompanying drawing 18, and the K=3 in the accompanying drawing 19, the OvTDM system trellis (Trelli) diagram.

In general, since the length of the data to be decoded is long, and with the deepening of the decoding depth, the accumulation distance becomes larger and larger, if the system decodes all the data and then performs decoding output, it will consume more system resources. , so a better processing method is adopted for the storage capacity of the path and the storage of the distance. Generally, the path storage length is selected to be 4K to 5K. At this time, if the path memory is full and the decoding judgment output has not yet been forced to make a judgment output, the initial node with the same path will be output first; as the decoding depth deepens, the accumulated The distance will also become larger and larger, and the accumulated distance can be stored as a relative distance, that is, a reference distance is defined, and its value depends on different systems. The distance storage records the second distance of each path relative to the reference distance Relative value, compared by relative distance when screening the best path.

For example, in this case, we use a square wave as the multiplexed waveform to illustrate the encoding and decoding process. Set the number of overlapping multiplexing K=3, the length of the input sequence N=9, the symbol sequence x _i ={-1,+1,-1,+1,+1,+1,-1,+1,-1}, After OvTDM series encoding, the output sequence length becomes 11(N+K-1), and the output symbol sequence s'(t)={-1,0,-1,+1,+1,+3,+1,+ 1,-1,0,-1}, the superposition process of the symbols in this case is shown in Figure 20, and it can be seen from the figure that the first two and the last two symbols in the superimposed symbol sequence are not a 3-way superposition, so We perform complementary superposition of these two parts of the signal and place them in front of the middle symbol to form a complementary OvTDM mode. The output symbol sequence after complementary superposition is s(t)={-1,-1,-1,+1,+1 ,+3,+1,+1,-1}. The coded signal is transmitted through the actual channel, and the symbol sequence received at the receiving end will have deviation, which is denoted as y _i , where i=1~9. The sequence of symbols received in this case is:

y _i ={-0.9155,-1.4137,0.0825,0.5699,0.5244,3.7270,0.2254,1.9963,-2.1995};

All symbols are decoded one by one according to the aforementioned Viterbi decoding method, and the symbol detection path in the decoding process is shown in FIG. 21 . After decoding all symbols, four optimal paths and their corresponding Euclidean distances are obtained, as follows:

path ₁ : {-1,1,-1,1,1,1,-1,1,1};

path ₂ : {-1,1,-1,1,1,1,-1,1,-1};

path ₃ : {-1,1,-1,1,1,1,-1,-1,1};

path ₄ : {-1,1,-1,1,1,1,-1,-1,-1};

The corresponding Euclidean distances are d ₁ =8.1839, d ₂ =6.1839, d ₃ =8.1839, d ₄ =7.7848. After comparing these four distances, the Euclidean distance of d ₂ is the smallest, and the corresponding path path ₂ is selected is the output sequence of symbols. That is, we think that the output symbol sequence S _decode ={-1,1,-1,1,1,1,-1,1,-1}, and the input symbol sequence x _i ={-1,+1,- 1,+1,+1,+1,-1,+1,-1}, comparing the sequences of S _decode and _xi are exactly the same, then the decoding result is correct.

The complementary encoding method and device, complementary decoding method and device of the present application can achieve a higher decoding success rate under the same signal-to-noise ratio, and can be widely used in addition to OvTDM and OvFDM systems In the actual mobile communication system, such as TD-LTE, TD-SCDMA and other systems, it can also be widely used in any wireless communication system such as satellite communication, microwave line-of-sight communication, scattering communication, atmospheric optical communication, infrared communication and aquatic communication. It can be applied not only to large-capacity wireless transmission, but also to small-capacity light radio systems.

The above content is a further detailed description of the application in conjunction with specific implementation methods, and it cannot be determined that the specific implementation of the application is limited to these descriptions. For those of ordinary skill in the technical field to which the present application belongs, some simple deduction or replacement can also be made without departing from the inventive concept of the present application.

Claims (10)

1. A complementary coding method suitable for an OvXDM system is characterized by comprising the following steps:

generating an initial envelope waveform in a first domain based on the design parameters;

shifting the initial envelope waveform on a first domain according to the overlapping multiplexing times at preset intervals to obtain shifted envelope waveforms of all fixed intervals;

multiplying digital signals in the input sequence by respective corresponding displacement envelope waveforms to obtain each modulation envelope waveform;

superposing the modulation envelope waveforms on a first domain to obtain complex modulation envelope waveforms on the first domain, wherein the complex modulation envelope waveforms comprise a first section which is not sufficiently superposed, a main section which is sufficiently superposed and a tail section which is not sufficiently superposed;

only overlapping the first segment of the complex modulation envelope waveform to the tail segment, so that the first segment which is not fully overlapped and the tail segment which is not fully overlapped are overlapped, thereby all symbols are fully overlapped, and the fully overlapped main segment and the signal segment after the first segment and the tail segment are overlapped form a complementary complex modulation envelope waveform; or, only the tail segment of the complex modulation envelope waveform is superposed to the first segment, so that the tail segment which is not fully superposed and the first segment which is not fully superposed are superposed, all symbols are fully superposed, and the signal segment which is superposed by the first segment and the tail segment and the main segment which is fully superposed form a complementary complex modulation envelope waveform.

2. The complementary encoding method of claim 1, wherein the OvXDM system is an OvFDM system, an OvTDM system, an OvCDM system, an OvSDM system, or an OvHDM system; when the OvXDM system is an OvFDM system, the first domain is a frequency domain, when the OvXDM system is an OvTDM system, the first domain is a time domain, when the OvXDM system is an OvCDM system, the first domain is a code division domain, when the OvXDM system is an OvSDM system, the first domain is a space domain, and when the OvXDM system is an OvHDM system, the first domain is a hybrid domain.

3. A complementary decoding method is suitable for an OvXDM system, and is characterized by comprising the following steps:

receiving a signal and processing the received signal to obtain a digital signal in a first domain, wherein the digital signal in the first domain comprises a first segment which is not fully overlapped, a main segment which is fully overlapped and a tail segment which is not fully overlapped;

only overlapping the first segment of the complex modulation envelope waveform to the tail segment, so that the first segment which is not fully overlapped and the tail segment which is not fully overlapped are overlapped, thereby fully overlapping all symbols, and forming a complementary complex modulation envelope waveform by the fully overlapped main segment and the signal segment after the first segment and the tail segment are overlapped; or, only the tail segment of the complex modulation envelope waveform is superposed to the first segment, so that the tail segment which is not fully superposed and the first segment which is not fully superposed are superposed, all symbols are fully superposed, and the signal segment which is superposed by the first segment and the tail segment and the main segment which is fully superposed form a complementary complex modulation envelope waveform;

and decoding the digital signal according to a certain decoding algorithm.

4. The complementary decoding method of claim 3, wherein the OvXDM system is an OvFDM system, an OvTDM system, an OvCDM system, an OvSDM system, or an OvHDM system; when the OvXDM system is an OvFDM system, the first domain is a frequency domain, when the OvXDM system is an OvTDM system, the first domain is a time domain, when the OvXDM system is an OvCDM system, the first domain is a code division domain, when the OvXDM system is an OvSDM system, the first domain is a space domain, and when the OvXDM system is an OvHDM system, the first domain is a hybrid domain.

5. Complementary coding device, suitable for an OvXDM system, comprising:

a waveform generation module for generating an initial envelope waveform in a first domain based on the design parameters;

a shifting module, configured to shift the initial envelope waveform in a first domain at predetermined intervals according to the number of overlapping multiplexing, so as to obtain shifted envelope waveforms at fixed intervals;

the multiplication module is used for multiplying the digital signals in the input sequence by the respective corresponding displacement envelope waveforms to obtain the modulation envelope waveforms;

the superposition module is used for superposing the modulation envelope waveforms on a first domain to obtain complex modulation envelope waveforms on the first domain, wherein the complex modulation envelope waveforms comprise first segments which are not sufficiently superposed, main segments which are sufficiently superposed and tail segments which are not sufficiently superposed;

a complementary module, configured to superimpose only a first segment of the complex modulation envelope waveform onto a last segment, so that the first segment that is not sufficiently superimposed and the last segment that is not sufficiently superimposed are superimposed, so that all symbols are sufficiently superimposed, and the main segment that is sufficiently superimposed and a signal segment in which the first segment and the last segment are superimposed form a complementary complex modulation envelope waveform; or only overlapping the tail segment of the complex modulation envelope waveform to the first segment, so that the tail segment which is not fully overlapped and the first segment which is not fully overlapped are overlapped, all symbols are fully overlapped, and the signal segment after the first segment and the tail segment are overlapped and the main segment which is fully overlapped form a complementary complex modulation envelope waveform.

6. The complementary encoding apparatus of claim 5, wherein the first domain is a frequency domain when the OvXDM system is an OvFDM system, the first domain is a time domain when the OvXDM system is an OvTDM system, the first domain is a code division domain when the OvXDM system is an OvCDM system, the first domain is a spatial domain when the OvXDM system is an OvSDM system, and the first domain is a hybrid domain when the OvXDM system is an OvHDM system.

7. A complementary decoding apparatus, adapted to an OvXDM system, comprising:

the receiving module is used for receiving signals and processing the received signals to obtain digital signals in a first domain, wherein the digital signals in the first domain comprise a first segment which is not fully superposed, a main segment which is fully superposed and a tail segment which is not fully superposed;

a complementary module, configured to superimpose only a first segment of a complex modulation envelope waveform onto a last segment, so that the first segment that is not sufficiently superimposed and the last segment that is not sufficiently superimposed are superimposed, so that all symbols are sufficiently superimposed, and the main segment that is sufficiently superimposed and a signal segment in which the first segment and the last segment are superimposed form a complementary complex modulation envelope waveform; or, only the tail segment of the complex modulation envelope waveform is superposed to the first segment, so that the tail segment which is not fully superposed and the first segment which is not fully superposed are superposed, all symbols are fully superposed, and the signal segment which is superposed by the first segment and the tail segment and the main segment which is fully superposed form a complementary complex modulation envelope waveform;

and the decoding module is used for decoding the digital signal according to a certain decoding algorithm.

8. The complementary decoding apparatus of claim 7, wherein the first domain is a frequency domain when the OvXDM system is an OvFDM system, the first domain is a time domain when the OvXDM system is an OvTDM system, the first domain is a code division domain when the OvXDM system is an OvCDM system, the first domain is a spatial domain when the OvXDM system is an OvSDM system, and the first domain is a hybrid domain when the OvXDM system is an OvHDM system.

Ovxdm system, comprising complementary encoding means according to claim 5 or 6, or comprising complementary decoding means according to claim 7 or 8.

10. The OvXDM system in accordance with claim 9, wherein the OvXDM system is an OvFDM system, an OvTDM system, an OvCDM system, an OvSDM system, or an OvHDM system.

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