JPH07162393A - Error correction coding Frequency hopping Spread spectrum communication system - Google Patents

Abstract

(57) [Abstract] [Object] The present invention provides an error correction coding frequency hopping spread spectrum communication system capable of transmitting a large amount of information with high reliability within a limited transmission power and frequency band. The purpose is to provide. [Structure] Input data D40 is first converted by encoding means 40.
~ Nth data D40 _{1 to} D40 _N are branched, and the branch data D40 _{1 to} D40 _N are provided with redundancy for error correction, and the first to Nth spreading means 41 _{1 to} 41 _N respectively have different N Frequency hopping is performed with each of the hopping patterns HP _{1 to} HP _N , and the data D41 _{1 to} D41 _N are modulated by the carrier wave by the combining means 42 and combined, and then the radio wave R1 is generated.
The radio wave R10 is emitted as 0, and the first to Nth despreading means 4
Hopping pattern HP similar to the above depending on 3 ₁ to 43 _N
1 despread demodulated by to HP _N, using the above-described redundancy included in the despread data D42 ₁ ~D42 _N by decoding means 44 configured to obtain the original data by performing error correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error correction coding frequency hopping spread spectrum communication system which is a multiple access system for mobile communication such as mobile phones and wireless LANs.

In the field of mobile communication, it is difficult to obtain a stable communication path due to fading or the like, so that it is required to improve communication reliability by error correction coding or diversity combining. In addition, since available frequencies are limited, a communication system is required that allows as many users as possible to simultaneously communicate in a given frequency band.

[0003]

2. Description of the Related Art In conventional digital wireless communication,
In order to improve the reliability of communication, error correction coding and diversity reception by an antenna are performed.

[0004]

However, since error correction coding must take a large amount of code redundancy,
There is a problem in that the effect of error correction is not sufficiently exerted when the information transmission speed is lowered or the band is spread, and the received electric field strength is lowered due to fading.

Even if a process such as interleaving is performed to solve this problem, it is necessary to increase the delay in order to sufficiently bring out the performance of the code. Therefore, there is a practical limit in the application of a mobile phone or the like.

Further, in the diversity reception by the antenna, there is a problem that the demand for downsizing of the receiver is limited. The present invention has been made in view of the above point, and error correction coding frequency hopping that enables highly reliable transmission of a large amount of information within a limited transmission power and frequency band. It is intended to provide a spread spectrum communication system.

[0007]

FIG. 1 shows a transmission principle of the present invention, and FIG. 2 shows a reception principle of the present invention. In FIG. 1, reference numeral 40 denotes a coding unit having a coding rate of 1 / N, which provides input data D40 with redundancy for error correction, and branches to first to Nth data D40 _{1 to} D40 _N. And output it.

Reference numerals 41 _{1 to} 41 _N are first to Nth spreading means, and frequency hopping is performed on the _first to Nth data D40 _{1 to} D40 _N with N different hopping patterns HP _{1 to} HP _N. Is used for diffusion modulation.

Reference numeral 42 denotes a synthesizing means, which modulates the output data D41 _{1 to} D41 _N of the _first to N-th spreading means 41 _{1 to} 41 _N with a carrier wave and synthesizes them. In FIG. 2, reference numerals 431 to 43N denote _first to _N- th despreading means, respectively, which output a signal S21 corresponding to the output signal S20 of the synthesizing means 42 transmitted by the radio signal R10 from the transmitter shown in FIG.
Spread demodulation is performed with _N hopping patterns HP _{1 to} HP _N.

Reference numeral 44 denotes a decoding means, which is the output data D42 _{1 to} D42 _N of the _first to _N-th despreading means 43 ₁ to 43 _N.
Error correction is performed using the above-described redundancy included in (1) to output.

Further, the passage / blocking of the above-mentioned first to N-th data D40 _{1 to} D40 _N is individually performed between the above-mentioned encoding means 40 and the above-mentioned first to N-th spreading means 41 _{1 to} 41 _N. connects the first switching means capable, the output data D of the first to N diffusion means 41 ₁ to 41 _N between the combining means 42 described above with first through N diffusion means 41 ₁ to 41 _N described above
The _first to Nth despreading means 43 are connected by connecting the second switch means capable of individually passing / blocking 41 _{1 to} D41 _N.
Output data D42 _{1 to} D 42 of the _first to _Nth despreading means 43 ₁ to 43 N between ₁ to 43 _N and the decoding means 44 described above.
The above-mentioned coding rate and the above-mentioned coding rate are obtained by connecting the third switch means capable of individually passing / blocking 42 _N and turning ON / OFF the first to third switch means synchronously according to the number of simultaneous communication stations. It is preferable that the number of frequency hopping is variable.

[0012]

According to the present invention described above, one user performs communication by using a code having a low coding rate 1 / N and using many hopping patterns HP _{1 to} HP _N.
The coding gain of the coding means 1 and the diversity effect of frequency hopping work effectively, and reliable communication can be performed with low power.

Further, by changing the frequency slot for frequency hopping simultaneously with the coding rate 1 / N by the first to third switching means, according to the number of simultaneous communication stations,
When the number of users increases, interference can be reduced and effective communication can be performed.

This is because when the number of simultaneous communication stations is increased, there are many hits in which signals between users share the same time slot and frequency slot, which causes interference, which eliminates the cause of increasing errors. is there.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of a transmitter according to the error correction coding frequency hopping spread spectrum communication system of the first embodiment of the present invention, and FIG. 4 is a block diagram of a receiver.

In the error correction coding frequency hopping spread spectrum communication system of the first embodiment, the number of multiplexed transmission data is set to "7", and HP1 to HP1 shown in FIG.
It is assumed that 7 hopping patterns are assigned to each user by using the hopping pattern of the period “30” shown by HP7.

However, each hopping pattern HP1 to HP
No. 7 is a frequency hopping CDMA (Code Di
The RS (Reed-Solomon: person's name) codes used for vision multiple access are time-shifted.

In the transmitter shown in FIG. 3, 1 is a convolutional encoder, 2 to 8 are FSK (Frequency-Shift Keying) modulators, 9 to 15 are spread modulators, 16 is a combiner, and 17 is an antenna.

In the receiver shown in FIG. 4, 19 is an antenna, 20-26 are despreaders, 27-33 are soft decision demodulators, and 34 is a Viterbi decoder. The transmission data DS input to the convolutional encoder 1 shown in FIG. 3 is convolutionally encoded with a constraint length of 5 and an encoding rate of 1/7. That is, the transmission data DS is branched into seven, and the branched data D1 to D7
A process for giving redundancy to error correction is performed. The data D1 to D7 obtained by the convolutional encoder 1 are F
It is output to the SK modulators 2 to 8. However, the 7 series of data D1 to D7 output from the convolutional encoder 1 have different values.

In each of the FSK modulators 2 to 8, FSK modulation in which the frequency of the carrier of a predetermined frequency is modulated with each of the data D1 to D7 is performed, and the signal S1 obtained by this is performed.
~ S7 are input to the spread modulators 9 to 15. In addition, FS
PSK (Phase Shift Keying) instead of K modulators 2-8
Means for performing modulation may be used.

In the spread modulators 9 to 15, the input signal S
Frequency hopping (spread modulation) is performed by modulating 1 to S7 with hopping patterns HP1 to HP7.

The transmission signals S11 to S thus obtained
17 is combined by the combining unit 16, and the combined signal S18 is transmitted from the antenna 17 as a radio wave signal R1. This transmitted radio signal R1 is the antenna 1 of the receiver shown in FIG.
9 and received as the signal S19 by the despreaders 20 to 26.
Is output to.

In the despreading units 20 to 26, the input signal S19 is multiplied by the hopping patterns HP1 to HP7 to perform despread demodulation. By this despreading demodulation, the spreading modulators 9 to 9 of the transmitter shown in FIG.
The seven series of signals S9 to S15 output from 15 are obtained respectively. Let those signals be S21 to S27.

The signals S21 to S27 are sent to the soft decision demodulator 2
7 to 33, the soft decision demodulation is performed, and the data is output to the Viterbi decoder 34 as data D11 to D17 that are substantially equivalent to the respective data D1 to D7 output from the convolutional encoder 1 of the transmitter.

In the Viterbi decoder 34, the redundancy provided in the convolutional encoder 1 is used to perform error correction on each of the data D11 to D17. Through this process, the Viterbi decoder 34 outputs the reception data DR equivalent to the transmission data DS.

According to the first embodiment described above, one user uses a code having a low coding rate and communicates by using a plurality of hopping patterns HP1 to HP7. The conversion does not lower the information transmission rate or spread the band, and the error correction effect can be sufficiently exerted even when the received electric field strength is reduced due to fading.

Further, the diversity effect due to frequency hopping works effectively, and the interval between the antennas can be narrowed as compared with the conventional diversity reception, so that it becomes possible to meet the demand for miniaturization of the receiver.

Next, a second embodiment will be described with reference to FIGS. FIG. 5 is a block diagram of a transmitter and FIG. 6 is a block diagram of a receiver. In these figures, parts corresponding to the respective parts of the second embodiment shown in FIG. 3 and FIG.
The description is omitted.

The transmitter of the second embodiment shown in FIG. 5 differs from the transmitter of the first embodiment shown in FIG. 3 in that the convolutional encoder 1 and each F
A switch unit 40 for connecting / disconnecting the data D1 to D7 of each system path is connected between the SK modulation units 2 to 8 and each system between the spread modulation units 9 to 15 and the combining unit 16. This is because the switch unit 41 for connecting / disconnecting the road signals S11 to S17 is connected.

The transmitter of the second embodiment shown in FIG. 6 is different from the transmitter of the first embodiment shown in FIG. 4 in that the data of each path between the despreading units 20 to 26 and the Viterbi decoder 34 is different. D11-D1
This is because the switch unit 43 for connecting / disconnecting 7 is connected.

The switch section 40 is composed of switches SW1 to SW7 connected to each system path, and a switch control signal S3 output from the switch control section 42.
ON / OFF according to 1.

Similarly, the switch section 41 is also composed of switches SW1 to SW7 connected to each system path, and a switch control signal S3 output from the switch control section 42.
ON / OFF according to 1.

The switch unit 43 in the receiver is also composed of switches SW1 to SW7 connected to each system path, and is turned on / off according to a switch control signal S32 output from the switch control unit 44. ing.

However, the switches SW1 to SW7 of each of the switch units 40, 41, 43 are designed to operate synchronously. Further, the switch control units 42, 44 that control the switch units 40, 41, 43 perform switching control according to the number of simultaneous communication stations.

In such a configuration, the coding rate of the convolutional code can be changed from 1/2 to 1/6 by turning on / off the switches SW1 to SW7 as shown in FIG.

The coding rate is set in inverse proportion to the number of users. Data D1 to D7 output from the convolutional encoder 1 corresponding to the coding rate according to ON in FIG.
SK-modulated and corresponding hopping patterns HP1-H
After being spread-modulated by P7, they are combined and transmitted.

Since the number of simultaneous hops for frequency hopping is also changed according to the change in the coding rate, the coding rate can be changed without changing the transmission rate. At the decoding side, that is, at the receiver, each of the hopping patterns HP1 to HP1
Despreading is performed in P7, and the signal corresponding to the coding rate is output to the Viterbi decoder 34. This is done in FIG.
This is for simplifying the function of the Viterbi decoder 34 by not using the one that is turned off in 1.

As described above, by varying the coding rate and the number of simultaneous hops, when the number of simultaneous communication stations increases, the number of frequencies used by each user can be reduced to drastically reduce interference. Therefore, highly reliable communication can be performed. Also in the second embodiment, the first
The same effect as the embodiment can be obtained.

[0039]

As described above, according to the present invention,
By combining error correction coding and frequency hopping multiple access and directly frequency hopping modulating the output of the error correction coding means, coding gain and diversity effect can be obtained, and fading is performed without further processing such as interleaving. Since the error can be dispersed by the method, the processing delay can be reduced, the effect of the error correction code can be utilized, and the communication quality can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a transmission principle of the present invention.

FIG. 2 is an explanatory diagram of a reception principle of the present invention.

FIG. 3 is a block diagram of a transmitter according to the error correction coding frequency hopping spread spectrum communication system of the first embodiment of the present invention.

FIG. 4 is a block configuration diagram of a receiver according to the error correction coding frequency hopping spread spectrum communication system of the first embodiment of the present invention.

FIG. 5 is a diagram showing an example of a hopping pattern.

FIG. 6 is a block configuration diagram of a transmitter according to an error correction coding frequency hopping spread spectrum communication system of a second embodiment of the present invention.

FIG. 7 is a block configuration diagram of a receiver according to an error correction coding frequency hopping spread spectrum communication system of a second embodiment of the present invention.

FIG. 8 is an ON / OFF state of the switch unit shown in FIGS. 6 and 7.
It is a figure which shows the correspondence of a state and a coding rate.

[Explanation of symbols]

40 Coding Means 41 _{1 to} 41 _N 1st to Nth Spreading Means 42 Combining Means 43 ₁ to 43 _{N 1st} to _Nth Despreading Means 44 Decoding Means D40 Input Data of Multiplexing Means 40 D40 _{1 to} D40 _N Codes Output data of the conversion means D41 _{1 to} D41 _N Data after spreading 42 Signal obtained by modulating spread data with carrier wave and synthesized R10 Radio signal S21 Signal corresponding to signal S21 D42 ₁ to D42 _N Data after despreading

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04L 12/28 7831-5K H04L 11/00 310 B

Claims (3)

[Claims] 1. The input data (D40) is provided with redundancy for error correction, and the first to Nth data (D40 ₁ to D 40
Coding means with a coding rate of 1 / N for branching to 40 _N ) for output
(40) and the _first to Nth data (D40 ₁ to D40 _N ) are different N
1st to Nth spreading means (4) for performing spread modulation by performing frequency hopping with _one hopping pattern (HP _{1 to} HP _N ).
1 _{1 to} 41 _N ) and the output data (D41 _{1 N} ) of the _first to Nth diffusion means (41 _{1 to} 41 _N ).
~ D41 _N ) are modulated with a carrier and are combined (4
2) comprises a transmitter comprising, and a signal (S21) corresponding to the output signal (S20) of the synthesizing means (42) transmitted by the radio signal (R10) from the transmitter,
First to Nth despreading means (43 ₁ to 43 _N ) for spreading and demodulating with the _N hopping patterns (HP _{1 to} HP _N ), and the _first to _Nth despreading means (43 ₁ to 43 _N ). Output data (D42
₁ to D42 _N ), an error correction coded frequency hopping spectrum, characterized in that the receiver is provided with a decoding means (44) for performing error correction using the redundancy included in ( ₁ ) to (D42 _N ). Spread communication method. 2. The first to N-th data (D40) between the encoding means (40) and the first to N-th spreading means (41 _{1 to} 41 _N ).
₁ to D40 _N ) are individually connected to a first switch means, and the first to N-th diffusion means (41 _{1 to} 41 _N ) and the synthesizing means (42) are connected to each other. ~ Nth diffusion means (41 ₁ ~
41 _N ) output data (D41 ₁ to D41 _N ) are individually connected to a second switch means that can pass / block the output data (D41 ₁ to D41 _N ).
Output data (D42) of the _first to _N-th despreading means (43 ₁ to 43 _N ) between the despreading means (43 ₁ to 43 _N ) and the decoding means (44).
₁ to D42 _N ) are separately connected to a third switch means, and the first to third switch means are synchronously turned on / off in accordance with the number of simultaneous communication stations, thereby the coding rate The error-correcting coded frequency hopping spread spectrum communication system according to claim 1, wherein the number of frequency hopping is variable. 3. The error correction coding frequency according to claim 1, wherein a convolutional encoder is used for the encoding means (40) and a Viterbi decoder is used for the decoding means (44). Hopping spread spectrum communication system.