Channel coding method for a micro frequency hopping multiple access communication system

Abstract

The application belongs to the technical field of channel coding and decoding of communication systems, and particularly relates to a channel coding method of a micro-frequency hopping multiple access communication system, which comprises frame header coding and payload coding; the frame header coding adopts a polar code, and the payload coding adopts an RS code; the polar code coding is based on channel confidence to select information bits and frozen bits; the payload coding uses the RS code to enhance error correction capability; micro-frequency hopping symbol mapping adjusts the number of bits borne by each symbol according to a spreading factor SF; and gray code conversion ensures the robustness of data transmission; and the application further improves the sensitivity and anti-interference capability of the micro-frequency hopping spread spectrum multiple access communication system on the basis of the original advantages of the micro-frequency hopping multiple access communication system through coding and decoding technology.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of channel coding of communication systems, and particularly relates to a channel coding method of a micro-frequency hopping multiple access communication system. BACKGROUND

[0002] Mainstream technologies of low power wide area network (LPWAN) include NB-IoT, Lora, etc., and currently some Internet of Things chip manufacturers in China have proposed their own technologies, such as turMass of DooBi, AdvancedM-FSK of ZongXing, chirp-IoT of PanQiWei, Pluto-IoT based on micro-frequency hopping spread spectrum modulation technology of HuoPuWei, etc. Among these existing LPWAN technologies, channel coding plays an irreplaceable role in improving sensitivity performance and increasing anti-interference capability.

[0003] According to the Shannon formula, C=B*log2(1+S / N), the channel capacity of a Gaussian channel is related to bandwidth and signal-to-noise ratio, but the maximum transmission rate of a channel for error-free transmission cannot reach the channel capacity C. When converted to EbNo, it can be expressed as: in the condition of AWGN channel, in order to transmit information without loss, the Eb / No should be not less than-1.59dB, which is the Shannon limit. In order to approach the Shannon limit as much as possible, various channel coding technologies are proposed, including Turbo code, LDPC, polar code, etc.

[0004] However, LPWAN is a low-power scenario, and the complexity and power consumption of the implementation of LDPC, Turbo code and other probabilistic decoding make it impossible for LPWAN to use such coding and decoding. For example, Yoann Roth of France once proposed a turbo-FSK technology, in which turbo refers to a channel coding and decoding technology combined with constellation modulation, which can achieve a performance of only 2DB away from the Shannon limit. However, due to the high implementation complexity and the poor anti-single-tone interference capability of mFSK itself, this technology only exists in papers. On the other hand, in order to save power, the channel coding of the currently popular Lora technology adopts a very simple (7,4) Hamming code. Although the implementation is simple and the power consumption is extremely low, the coding gain is also extremely low, which makes Lora about 7DB away from the Shannon limit at a frame error rate of 10e-2. Therefore, how to design channel coding to make the power consumption and performance most consistent with the LPWAN scenario of the chip is a problem to be solved. SUMMARY

[0005] The purpose of the present application is to provide a channel coding method of a micro-frequency hopping multiple access communication system, to improve the sensitivity and anti-interference capability of the micro-frequency hopping spread spectrum multiple access communication system, so as to solve the problems proposed in the background technology.

[0006] In order to achieve the above object, the application adopts the following technical scheme: a channel coding method of a micro-frequency hopping multiple access communication system, comprising frame header coding and payload coding; wherein the frame header coding adopts a polar code, and the payload coding adopts an RS code.

[0007] Preferably, the frame header coding comprises:

[0008] information bit mapping, polar code encoding, micro-frequency hopping symbol mapping, and gray code conversion.

[0009] Preferably, the information bit mapping comprises:

[0010] The information bits before encoding are 10 bits, wherein the first 8 bits are used to indicate payload size information nByte, and the last 2 bits are used to indicate the error correction capability t of the RS code, wherein 00 indicates that the error correction capability t of the RS code is 1 symbol, 01 indicates that the error correction capability t of the RS code is 4 symbols, 10 indicates that the error correction capability t of the RS code is 8 symbols, and 11 indicates that the error correction capability t of the RS code is 16 symbols.

[0011] According to the confidence of 32 channels of the polar code, it is determined which channels transmit information bits and which channels transmit frozen bits, wherein the frozen bits are 0.

[0012] Among them, the [32, 31, 30, 28, 24, 16, 29, 23, 26, 27, 22] bits are filled with information bits, and the remaining bits are filled with frozen bits, and the zero is filled.

[0013] Preferably, the polar code encoding comprises:

[0014] The 32-bit information before encoding filled with frozen bits is subjected to an encoding matrix g(32) to generate 32-bit information after encoding, wherein the encoding matrix g(32) is a 5th tensor product of [1, 0; 1, 1].

[0015] Preferably, the micro-frequency hopping symbol mapping of the frame header coding comprises:

[0016] The spreading factor of the micro-frequency hopping spread spectrum multiple access communication system comprises six kinds of [6, 7, 8, 9, 10, 11].

[0017] The frame header coding adopts a compression mode, that is, the lower two bits of each micro-frequency hopping symbol do not carry information, so the number of bits carried by each symbol is six kinds of [4, 5, 6, 7, 8, 9].

[0018] When the SF is [6, 7, 8, 9], 8 symbols are used to carry 32-bit information after encoding, when the SF is [10, 11], 4 symbols are used to carry 32-bit information after encoding, and when the number of bits carried exceeds 32 bits, the first bits in 32 bits are repeated and supplemented.

[0019] Preferably, the data mapped to the micro-hopping symbol is converted according to a gray code to binary data mode.

[0020] Preferably, the payload coding comprises 4 RS coding, micro-hopping symbol mapping and gray code conversion.

[0021] Preferably, in the RS coding, a primitive polynomial of the RS code is P(x) = D^8+D^4+D^3+D^2+1, and a generator polynomial g(x) of the RS code is g(x) = (x-1)*(x-a^1)*...(x-a^(2*t-1)), wherein t is an error correction capability, and t is 1, 4, 8, 16, a is a primitive element, and a is 2.

[0022] The RS coding process is as follows:

[0023] The information polynomial m(x) is multiplied by x^(2*t) and then the generator polynomial g(x) is taken modulo, to obtain the check polynomial r(x), i.e., r(x) = mod(m(x)*x^(2*t),g(x)), wherein mod is modulo.

[0024] Preferably, the micro-hopping symbol mapping is as follows:

[0025] The RS coded data is converted into parallel-serial conversion, to obtain a data stream of nBits (nByte+2*t)*8 bits.

[0026] The serial data stream is mapped to the micro-hopping symbol according to SF bits, i.e., each symbol carries SF bits, and if the serial data bit number mod is not equal to 0, SF is filled with 0, wherein mod is modulo.

[0027] Preferably, the data mapped to the micro-hopping symbol is converted according to a gray code to binary data mode.

[0028] The technical effects and advantages of the present application are as follows:

[0029] On the basis of the original advantages of the micro-hopping multi-address communication system, the sensitivity and anti-interference capability of the micro-hopping spread spectrum multi-address communication system are further improved through coding and decoding technology. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 FIG. 1 is a data frame structure diagram of the micro-hopping multi-address communication system of the present application.

[0031] Figure 2 Channel coding architecture diagram for the micro frequency hopping multiple access communication system of the present application;

[0032] Figure 3 Schematic diagram of the fast Hadamard transform of the present application;

[0033] Figure 4 Schematic diagram of the frame header data mapping to the micro frequency hopping symbol of the present application;

[0034] Figure 5 RS codebook original polynomial structure diagram of the present application;

[0035] Figure 6 RS code generation polynomial structure diagram of the present application;

[0036] Figure 7 Schematic diagram of the payload data mapping to the micro frequency hopping symbol of the present application. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. The specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0038] The present application provides a channel coding method of a micro frequency hopping multiple access communication system, including frame header coding and payload coding; Wherein the frame header coding adopts polar code, and the payload coding adopts RS code.

[0039] Among them, the frame header coding includes: information bit mapping, polar code encoding, micro frequency hopping symbol mapping and gray code conversion.

[0040] Further, the information bit mapping includes: 10 bits of information bits before encoding, wherein the first 8 bits are used to indicate the payload size information nByte, and the last 2 bits are used to indicate the error correction capability t of RS code, wherein 00 indicates that the error correction capability t of RS code is 1 symbol, 01 indicates that the error correction capability t of RS code is 4 symbols, 10 indicates that the error correction capability t of RS code is 8 symbols, and 11 indicates that the error correction capability t of RS code is 16 symbols;

[0041] According to the confidence of 32 channels of polar code, it is determined which channels transmit information bits and which channels transmit frozen bits, wherein the frozen bits are 0;

[0042] Wherein, the [32, 31, 30, 28, 24, 16, 29, 23, 26, 27, 22] bits fill information bits, and the rest bits fill frozen bits, and fill zero.

[0043] Further, the polar code encoding comprises: generating 32-bit coded information from 32-bit uncoded information filled with frozen bits through an encoding matrix g(32), wherein the encoding matrix g(32) is a 5th tensor product of [1, 0; 1, 1].

[0044] Further, the micro-hopping symbol mapping of the frame header encoding comprises: a spreading factor of the micro-hopping spread spectrum multiple access communication system, comprising six kinds of [6, 7, 8, 9, 10, 11]; the frame header encoding adopts a compression mode, that is, the lower two bits of each micro-hopping symbol do not carry information, so that the number of bits carried by each symbol is six kinds of [4, 5, 6, 7, 8, 9].

[0045] When SF is [6, 7, 8, 9], 8 symbols are used to carry 32-bit coded information, when SF is [10, 11], 4 symbols are used to carry 32-bit coded information, and when the number of bits carried exceeds 32 bits, the first bits in 32 bits are repeatedly supplemented.

[0046] Preferably, the data mapped to the micro-hopping symbol is converted in a gray code to binary data manner.

[0047] Further, the payload encoding comprises four RS encodings, micro-hopping symbol mapping and gray code conversion.

[0048] Wherein, in the RS encoding, the primitive polynomial of the RS code is: P(x) = D^8+D^4+D^3+D^2+1, the generator polynomial g(x) of the RS code is (x-1)*(x-a^1)*...(x-a^(2*t-1)), wherein t is the error correction capability, and the value of t is 1, 4, 8, 16, a is the primitive element, and a is 2.

[0049] Further, the RS encoding process is: multiplying the information polynomial m(x) by x^(2*t) and taking the modulus of the generator polynomial g(x) to obtain the check polynomial r(x), that is, r(x) = mod(m(x)*x^(2*t), g(x)), wherein mod is the modulus.

[0050] Further, the micro-hopping symbol mapping is: performing parallel-serial conversion on the RS encoded data to obtain a data stream of nBits (nByte+2*t)*8 bits; mapping the serial data stream according to SF bits to obtain a micro-hopping symbol, that is, each symbol carries SF bits, and if the number of serial data bits mod is not equal to 0, SF is filled with 0, wherein mod is the modulus.

[0051] Further, the data mapped to the micro-hopping symbol is converted in a gray code to binary data manner.

[0052] The following will be described in detail with reference to the accompanying drawings:

[0053] In order to improve the sensitivity and anti-interference ability of the micro-hopping spread spectrum multiple access communication system, the embodiment proposes a low complexity and high coding gain channel coding scheme.

[0054] Firstly, the micro-hopping spread spectrum multiple access communication system is a LPWAN (Low Power Wide Area Network) system, therefore, the data frame format is relatively simple, such as Figure 1 , including 8 or 4 micro-hopping symbol frame header, x micro-hopping symbol payload.

[0055] Specifically, the value of x is determined by the payload quantity nByte, RS code error correction capability t, spreading factor SF and other parameters, that is, x is equal to ceil((nByte+2*t)*8 / SF).

[0056] Figure 2 For the channel coding architecture of the micro-hopping multiple access communication system, by Figure 2 It can be seen that it includes frame header Polar encoding, payload RS encoding, symbol padding mapping, gray code conversion to binary code and other processes. Specifically, it includes:

[0057] The frame header information is 10 bits, the high bits are in front, of which the first 8 bits represent the payload size, that is, the number of bytes nByte of the payload, and the last two bits represent the RS code error correction capability, specifically, 00 represents t=1, 01 represents t=4, 10 represents t=8, and 11 represents t=16;

[0058] The 10-bit frame header information is mapped to the preferred position in the 32-bit according to the channel quality, and the remaining frozen bits are filled with zeros;

[0059] The 32-bit encoded data is subjected to fast Hadamard transform to generate 32-bit polar code data, wherein the schematic diagram of the fast Hadamard transform is as Figure 3 The 32-bit register is updated for five times, and the rule is:

[0060] bit(i)=bit(2*i)^bit(2*i-1);

[0061] bit(i+16)=bit(2*i);

[0062] Wherein, i=0 to 15; ^ represents bit XOR, the initial value of the 32-bit register is the information bit after filling the frozen bit, and after the register is updated for five times, the 32-bit data in the register is the polar code data.

[0063] Afterwards, the encoded 32-bit Polar code data is sequentially filled into a matrix of 8 columns by (SF-2) rows or 4 columns by (SF-2) rows in bit order, where each column is the first SF-2 bits of a micro-hopping symbol, the number of columns of the matrix is 8 or 4, the number of rows of the matrix is SF-2, and the filling is in row order, and when the matrix is not filled, the filling is repeated from the high bits. Figure 4 When SF is equal to 6, 7, 8, or 9, the number of columns of the matrix is 8, and when SF is equal to 10 or 11, the number of columns of the matrix is 4, and finally, the last two bits of each micro-hopping symbol are supplemented with 01 to form a complete symbol.

[0064] The payload is encoded using RS encoding, where the primitive polynomial of the RS code is P(x) = D^8 + D^4 + D^3 + D^2 + 1, as shown in Figure 5 .

[0065] The generating polynomial of the RS code is g(x) = (x-1)*(x-a^1)*...(x-a^(2*t-1)), as shown in Figure 6 . After nByte data is RS encoded, nByte+t*2 bytes of encoded data are generated.

[0066] After the payload is encoded, it is sequentially filled into a matrix of x columns by SF rows in bit order, where x is the number of micro-hopping symbols, and x is equal to ceil((nByte+2*t)*8 / SF). The filling is in row order, and when the matrix is not filled, zeros are supplemented, as shown in Figure 7 .

[0067] After all the micro-hopping symbols, including the frame header symbols and the payload symbols, are filled, in order to reduce the number of error bits in each symbol, the data of each symbol needs to be converted from gray code to binary. When the received binary symbol data has a +-1 offset, the conversion to gray code becomes a symbol with only one error bit, thus reducing the number of error bits in the received data and improving the error correction capability of the system.

[0068] Finally, it should be noted that the above description is only for the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A channel coding method for a micro- frequency hopping multiple access communication system, characterized by, The frame header coding and the payload coding are included. The frame header coding adopts a polar code, and the payload coding adopts an RS code. The frame header coding includes information bit mapping, polar code coding, micro-hopping symbol mapping, and gray code conversion. The payload coding includes four RS encodings, micro-hopping symbol mapping, and gray code conversion.

2. The channel coding method of a MFWA communication system according to claim 1, wherein, The information bit mapping includes: The information bits before coding are 10 bits, of which the first 8 bits are used to indicate payload size information nByte, and the last 2 bits are used to indicate the error correction capability t of the RS code, wherein 00 indicates that the error correction capability t of the RS code is 1 symbol, 01 indicates that the error correction capability t of the RS code is 4 symbols, 10 indicates that the error correction capability t of the RS code is 8 symbols, and 11 indicates that the error correction capability t of the RS code is 16 symbols. According to the confidence of 32 channels of the polar code, it is determined which channels transmit information bits and which channels transmit frozen bits, wherein the frozen bits are 0. The first [32, 31, 30, 28, 24, 16, 29, 23, 26, 27, 22] bits are filled with information bits, and the remaining bits are filled with frozen bits, and the zero is filled.

3. The channel coding method of a MFWA communication system according to claim 2, wherein, The polar code coding includes: The 32 bits of the information before coding filled with frozen bits are subjected to an encoding matrix g(32) to generate 32 bits of the information after coding, wherein the encoding matrix g(32) is a 5th order tensor product of [1, 0; 1, 1].

4. The channel coding method of a MFWA communication system according to claim 3, wherein The micro-hopping symbol mapping of the frame header coding includes: The spreading factor of the micro-hopping spread spectrum multiple access communication system includes six [6, 7, 8, 9, 10, 11]; The frame header coding adopts a compression mode, that is, the lower two bits of each micro-hopping symbol do not carry information, so the number of bits carried by each symbol is six [4, 5, 6, 7, 8, 9]; When SF is [6, 7, 8, 9], 8 symbols are used to carry 32 bits of the information after coding, when SF is [10, 11], 4 symbols are used to carry 32 bits of the information after coding, and when the number of bits carried exceeds 32 bits, the first bits in 32 bits are repeatedly supplemented.

5. The channel coding method of a MFWA communication system as claimed in claim 1, wherein The data mapped to the micro-hopping symbol is converted in the manner of gray code to binary data.

6. The channel coding method of a MFWA communication system as claimed in claim 1, wherein In the RS encoding, the primitive polynomial of the RS code is P(x) = D^8+D^4+D^3+D^2+1, and the generator polynomial g(x) of the RS code is (x-1)*(x-a^1)*...(x-a^(2*t-1)), wherein t is the error correction capability, which takes values of 1, 4, 8, 16, and a is the primitive element, which is 2. The RS encoding process is: After multiplying the information polynomial m(x) by x^(2*t), the generator polynomial g(x) is taken modulo to obtain the check polynomial r(x), that is, r(x) = mod(m(x)*x^(2*t), g(x)), wherein mod is the modulo.

7. The method of claim 6, wherein the channel coding method of a MFWA communication system is characterized by the fact that, The micro-hopping symbol mapping is: The RS encoded data is converted into a data stream of nBits = (nByte+2*t)*8 bits through parallel-serial conversion. The serial data stream is mapped to the micro-hopping symbol according to SF bits, that is, each symbol carries SF bits, and if the serial data bit number mod is not equal to 0, SF is filled with 0, wherein mod is modulo.

Images