Research On Recognition Of Channel Codes Based On Soft Decision

Channel code recognition is usually used when the channel code is unknown.It is widely used in the civilian and military fields.In the civilian field,the application of this technology in intelligent communication systems can improve the efficiency of transmission.In the military field,channel code recognition is the key technology in communication reconnaissance and communication countermeasure systems.However,the research of channel code recognition is still imperfect,the existing research materials lack the recognition algorithm of the pattern mapper of convolutional code.In addition,in engineering applications,to adapt to different frame lengths and correct burst errors,RS codes need to be shortened and interleaved.However,there is a lack of research on shortened interleaved RS codes.In this thesis,the recognition algorithms of convolutional code and RS code are studied.The main work is as follows:(1)Regarding the recognition problem of convolutional code encoder using pattern mapper to realize code rate transformation,a code word soft information reflection method based on probability is proposed.Combined with the convolutional code recognition algorithm based on the average Syndrome Posterior Probability Log-Likelihood Ratio(SPP LLR),it can correctly recognize the convolutional code encoder.It solves the problem that the existing code recognition algorithms cannot recognize the pattern mapper of the codeword.Through simulation,the recognition algorithm based on the average SPP LLR is compared with the Generalized Likelihood Ratio Test(GLRT)algorithm to verify the performance of the algorithm.Simulation results show that the proposed algorithm can effectively recognize the convolutional code encoder under the low signal-to-noise ratio.(2)Regarding the recognition of the shortened interleaved RS code,a recognition model of the shortened interleaved RS code based on the soft decision is proposed in this thesis.It solves the problem that the existing recognition algorithms can not recognize the shortened interleaved RS code.In addition,for the problems of high complexity and poor performance of existing RS code recognition algorithms,a soft decision RS code recognition algorithm is proposed,which adopts the equivalent binary field to avoid the complex high-order Galois field operation.Through simulation,the proposed RS code recognition algorithm is compared with the traditional algorithm.The simulation results show that the recognition performance of the proposed algorithm is better than the traditional algorithm under the same amount of data.