CN115174000A - EDD-CCM-based adaptive adjustment method for rate under fading channel - Google Patents

Abstract

The invention discloses a rate self-adaptive adjusting method under a fading channel based on EDD-CCM, which improves a sending symbol and a decoding method of the CCM method, firstly converts an original RP symbol into a low-order symbol at a sending end for sending and adding an error detection code, then converts the low-order symbol into the RP symbol at a receiving end, simultaneously deletes the wrong RP symbol by using the error detection code, and only carries out subsequent decoding by using the checked RP symbol. Therefore, the code modulation method which has lower interruption probability under the conditions of a fading channel and low signal-to-noise ratio and has a certain rate self-adaptive adjustment capability is obtained, and high-reliability transmission of certain key instruction information under the condition of a severe channel is ensured.

Description

Rate Adaptive Adjustment Method in Fading Channel Based on EDD-CCM

technical field

The invention belongs to the technical field of wireless communication, and in particular relates to an EDD-CCM-based rate adaptive adjustment method under a fading channel.

Background technique

In the field of wireless communication, fading refers to the phenomenon that the amplitude of the received signal changes randomly due to the change of the channel, that is, signal fading. Channels that cause signal fading are called fading channels. The bit-symbol mapping method used in the CCM method to perform weighted summation to generate transmission symbols basically belongs to the high-order modulation above the 8th order. Adaptive adjustment will not saturate quickly, but the use of high-order modulation also weakens the anti-noise ability of CCM symbols during channel transmission, resulting in an increase in the number of erroneous symbols at the receiving end when the signal-to-noise ratio is low, thereby reducing decoding. Success rate. Specifically, under high dynamic channel conditions, symbol transmission channel will inevitably suffer from multipath fading, and the bit error rate of high-order modulation under fading channel will be significantly higher than that of Gaussian white noise channel. Therefore, under the condition of fading channel, the existing CCM method will reduce the adaptive rate adjustment performance due to the large error of most of the received RP symbols, and even cause the communication to be completely interrupted.

Similarly, according to the RPC-BP decoding process, the RPC-BP decoding method needs to estimate the noise probability distribution function of the received signal while receiving the RP symbol, so as to perform decoding estimation, that is, RPC-BP Step 2 of Decoding Method Steps. Of course, better decoding performance can be obtained by jointly decoding the noise distribution probability function. However, in the fading channel, in order to obtain an accurate and real-time estimation of the fast time-varying noise probability distribution function, it must spend more computation. . In addition, inaccurate noise distribution estimates can also increase the number of iterations required for successful decoding.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a rate adaptive adjustment method under fading channel based on EDD-CCM, which improves the transmission symbol and decoding method of the CCM method. First, the original RP symbol is converted into The low-order symbols are sent and added with error detection coding, and then the low-order symbols are converted into RP symbols at the receiving end. At the same time, the error detection coding is used to delete the erroneous RP symbols, and only the RP symbols that pass the verification are used for subsequent decoding. In this way, a coding and modulation method can be obtained that can have a lower interruption probability under the condition of fading channel and low signal-to-noise ratio, and has a certain rate adaptive adjustment ability, so as to ensure the highly reliable transmission of some key command information under harsh channel conditions. .

In order to achieve the above-mentioned technical purpose, the present invention is achieved through the following technical solutions:

A rate adaptive adjustment method under a fading channel based on EDD-CCM, comprising the following steps:

S1: At the transmitting end, the source bit information is modulated by RPC to generate RP symbols, and then the RP symbols are converted into corresponding signed binary information and CRC error detection and check information is added. Finally, the spectral efficiency and anti-noise performance are compared. Good QPSK modulation completes the bit-symbol mapping again and generates the multi-carrier signal to be transmitted by IFFT;

S2: After the receiving end completes QPSK demodulation in the opposite process, it first performs error detection and verification on the binary bit information corresponding to the RP symbol, deletes the RP symbol that fails the verification, and performs RPC with multiple non-consecutive RP symbols that have been verified successfully. -BP decoding, and finally get the transmitted source bit information;

S3: For the transmission rate of the EDD-CCM method, it is related to the value range of the RP symbol and the length of the CRC check bit; define the signed binary representation corresponding to the maximum value of the RP symbol generated under a certain weight set The length is L _{RP_bin} , the length of the CRC check bit is L _CRC , and the transmission rate of the EDD-CCM method can be expressed as

Preferably, in S2, in order to ensure a lower error detection probability, that is, the symbols that are successfully verified are completely correct symbols, CRC error detection codes with better error detection performance are used;

Preferably, the length of the CRC check digit needs to be selected according to performance requirements;

Preferably, in S2, before performing RPC-BP decoding with the restored multiple non-consecutive integer-valued RP symbols, the rows of the generator matrix G need to be deleted correspondingly according to the positions of the deleted RP symbols, that is, correspondingly Delete the rows corresponding to the failed RP symbols in the G matrix, and then perform RPC-BP decoding with the processed G matrix, and perform corresponding calculations with equations (1) and (2) in the decoding process:

Preferably, the specific processing flow of the receiving end in S2 is as follows: at the receiving end, the bit information and CRC check information of QPSK demodulation are firstly grouped according to the pre-conversion principle, and each group represents an RP symbol; Group bits are used for CRC check and RP symbol restoration, and at the same time delete and mark the position of the RP symbol that fails to check; because each row of the generator matrix corresponds to an RP symbol, after deleting the error symbol, the RP symbol needs to be decoded according to the marked error before decoding. The position of the symbol correspondingly deletes the row of the decoding matrix (ie the generator matrix); finally, the RPC-BP decoding is performed with the restored and successfully verified integer value RP symbol to recover the source bit information b ₁ , b ₂ , b ₃ ,...b _M .

The beneficial effects of the present invention are:

The present invention firstly converts the high-order RPC symbols into low-order QPSK symbols in S1, thereby improving the anti-noise performance of the symbols, and is more suitable for fading channels than the CCM method; The received symbols are detected and deleted, and then decoded based on integer symbols. Compared with the RPC-BP decoding method, there is no need to calculate the noise probability distribution function of the receiving end, which not only reduces the computational complexity, but also improves the low signal-to-noise ratio. Finally, it can be seen in S3 that the transmission rate of the present invention can be controlled and adjusted by the number of initial transmitted symbols, the transmission step, the number of times of transmission and the length of the CRC check bit. Compared with the CCM method, There are more adjustment parameters, which can be adjusted in consideration of transmission reliability and validity, and are applicable to a wider range of scenarios.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is the rate adjustment flow diagram based on EDD-CCM method of the present invention;

FIG. 2 is a schematic diagram of the processing flow of the receiving end of the EDD-CCM method of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

A rate adaptive adjustment method under a fading channel based on EDD-CCM, comprising the following steps:

S1: At the transmitting end, the source bit information is modulated by RPC to generate RP symbols, and then the RP symbols are converted into corresponding signed binary information and CRC error detection and check information is added. Finally, the spectral efficiency and anti-noise performance are compared. Good QPSK modulation completes the bit-symbol mapping again and generates the multi-carrier signal to be transmitted by IFFT;

S2: After the receiving end completes QPSK demodulation in the opposite process, it first performs error detection and verification on the binary bit information corresponding to the RP symbol, deletes the RP symbol that fails the verification, and performs RPC with multiple non-consecutive RP symbols that have been verified successfully. -BP decoding, and finally get the transmitted source bit information;

S3: For the transmission rate of the EDD-CCM method, it is related to the value range of the RP symbol and the length of the CRC check bit; define the signed binary representation corresponding to the maximum value of the RP symbol generated under a certain weight set The length is L _{RP_bin} , the length of the CRC check bit is L _CRC , and the transmission rate of the EDD-CCM method can be expressed as

Preferably, in S2, in order to ensure a lower error detection probability, that is, the symbols that are successfully verified are completely correct symbols, CRC error detection codes with better error detection performance are used;

Preferably, the length of the CRC check digit needs to be selected according to performance requirements;

Preferably, in S2, before performing RPC-BP decoding with the restored multiple non-consecutive integer-valued RP symbols, the rows of the generator matrix G need to be deleted correspondingly according to the positions of the deleted RP symbols, that is, correspondingly Delete the rows corresponding to the failed RP symbols in the G matrix, and then perform RPC-BP decoding with the processed G matrix, and perform corresponding calculations with equations (1) and (2) in the decoding process:

Preferably, the specific processing flow of the receiving end in S2 is as follows: at the receiving end, the bit information and CRC check information of QPSK demodulation are firstly grouped according to the pre-conversion principle, and each group represents an RP symbol; Group bits are used for CRC check and RP symbol restoration, and at the same time delete and mark the position of the RP symbol that fails to check; because each row of the generator matrix corresponds to an RP symbol, after deleting the error symbol, the RP symbol needs to be decoded according to the marked error before decoding. The position of the symbol correspondingly deletes the row of the decoding matrix (ie the generator matrix); finally, the RPC-BP decoding is performed with the restored and successfully verified integer value RP symbol to recover the source bit information b ₁ , b ₂ , b ₃ ,...b _M .

In the description of this specification, description with reference to the terms "one embodiment," "example," "specific example," etc. means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one aspect of the present invention. in one embodiment or example. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above-disclosed preferred embodiments of the present invention are provided only to help illustrate the present invention. The preferred embodiments do not exhaust all the details, nor do they limit the invention to only the described embodiments. Obviously, many modifications and variations are possible in light of the contents of this specification. These embodiments are selected and described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is to be limited only by the claims and their full scope and equivalents.

Claims (5)

1. A method for adaptively adjusting the rate under a fading channel based on EDD-CCM (enhanced digital-code communication-continuous mode), which is characterized by comprising the following steps:

s1: at a sending end, RPC is used for modulating information source bit information to generate an RP symbol, then the RP symbol is converted into corresponding signed binary information, CRC error detection check information is added, finally QPSK modulation with better spectrum efficiency and anti-noise performance is used for re-completing bit-symbol mapping, and a multi-carrier signal to be sent is generated through IFFT;

s2: after the receiving end completes QPSK demodulation in a reverse process, error detection and verification are firstly carried out on binary bit information corresponding to the RP symbols, the RP symbols which fail to be verified are deleted, RPC-BP decoding is carried out on a plurality of discontinuous RP symbols which are successfully verified, and finally transmitted information source bit information is obtained;

s3: for the transmission rate of the EDD-CCM method, the transmission rate is related to the value range of the RP symbol and the length of the CRC check bit; defining the length of signed binary representation corresponding to the maximum value of RP symbols generated under a certain weight set to be L _{RP_bin} CRC check bit length of L _CRC The transmission rate of the EDD-CCM method can be expressed as

2. The adaptive rate adjustment method for fading channel based on EDD-CCM as claimed in claim 1, wherein in S2, in order to ensure a lower error detection probability, i.e. the successfully checked symbol is the completely correct symbol, a CRC error detection code with better error detection performance is used.

3. The adaptive rate adjustment method for fading channels based on EDD-CCM as claimed in claim 1, wherein the CRC check bit length needs to be chosen in compromise according to performance requirements.

4. The method as claimed in claim 1, wherein in S2, before performing RPC-BP decoding on a plurality of restored non-consecutive integer value RP symbols, rows of a generation matrix G are deleted correspondingly according to positions of the deleted RP symbols, that is, rows corresponding to RP symbols failed in detection in the G matrix are deleted correspondingly, then the RPC-BP decoding is performed on the G matrix after processing, and corresponding calculation is performed in the decoding process according to equations (1) and (2):

5. the method according to claim 1, wherein the specific processing flow at the receiving end in S2 is as follows: grouping QPSK demodulated bit information and CRC check information according to a pre-conversion principle at a receiving end, wherein each group represents an RP symbol; then, performing CRC (cyclic redundancy check) and RP (reverse protocol) symbol reduction on each group of bits, and deleting and marking the RP symbol position failed in verification; because each row of the generating matrix correspondingly generates an RP symbol, the rows of the decoding matrix (namely the generating matrix) are correspondingly deleted according to the marked position of the error symbol before the RP symbol is decoded after the error symbol is deleted; finally, the information source bit information b can be recovered by performing RPC-BP decoding by using the restored integer value RP symbol which is successfully checked ₁ ,b ₂ ,b ₃ ,...b _M 。

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