Research On IRA Code Coding And Decoding Scheme Against Burst Interference

In order to improve the information transmission speed of the current communication system and meet the requirements of ultra-high-speed data transmission,the application of the Millimeter-Wave frequency band has attracted the attention of scholars.On the one hand,Millimeter-Wave is beneficial to increase the transmission rate because of its ultra-high frequency characteristics.On the other hand,because of its ultra-short wavelength,the signal is susceptible to burst interference during transmission,causing information transmission to fail.In order to solve the problem that Millimeter-Wave communication is vulnerable to sudden interference,the fifth-Generation(5G)communication system adopts two types of solutions.The first category is to design a suitable large-scale antenna technology,including precoding technology and beamforming technology.The second category is to design appropriate channel coding techniques.The 5G standard stipulates that data transmission adopts Low Density Parity Check(LDPC)code and error packet retransmission scheme at the physical layer.However,the data packet retransmission scheme causes great delay and system overhead.Therefore,the design of channel coding to combat burst interference is a key technical problem to be solved urgently in future communication systems.In this thesis,channel modeling is carried out in the presence of burst interference,and the theoretical analysis algorithm of Irregular Repeat Accumulate(IRA)code is derived.Based on these algorithms,a random interleaved IRA code under the best degree distribution is designed.In addition,the Belief Propagation(BP)decoding algorithm under burst interference scenarios is optimized.By using Channel State Information(CSI),an excellent performance closer to the channel capacity is obtained.The main research work of the thesis is as follows.First,the sudden interference scene is modeled as a two-state Markov channel,and a GEAWGN(Gilbert Elliott-Additive White Gaussian Noise)channel model is proposed.By adjusting the relevant parameters,it can simulate the actual scene of sudden interference of different degrees.Then,the iterative code design auxiliary tool under the GE-AWGN channel,Extrinsic Information Transfer(EXIT)diagram and related theories are deduced.Specifically,it includes the EXIT formula of the IRA code under the GE-AWGN channel and the algorithm that uses the EXIT principle to find the decoding threshold.The Differential Evolution(DE)algorithm is used to globally optimize the degree distribution of the IRA code,and the best degree distribution of the IRA code under a given code rate is obtained.The simulation results show that selectively reducing the dimension of the optimized vector can effectively improve the convergence speed of the DE algorithm.So far,the tools and theories needed to design IRA code under the GE-AWGN channel have been deduced.Based on this,under the conditions of a given code rate and optimal degree distribution,an IRA code check matrix meeting the requirements of the optimal degree distribution is constructed through a random interleaving method.Then the BP decoding algorithm of IRA code under the GE-AWGN channel is designed.Then,the EXIT algorithm under the GEAWGN channel is used to calculate the BP decoding threshold of the IRA code.The simulation results show that the decoding threshold of the constructed IRA code can be close to the channel capacity.Under different channel parameters and code rates,the constructed IRA code still has performance close to the channel decoding threshold,and the above analysis results are verified by Bit Error Rate(BER)simulation.In addition,under the same coding parameters and GE-AWGN channel parameters,the LDPC code proposed by 5G standardization is compared with the IRA code designed,and it is found that the BER performance of the IRA code designed is better than that of the 5G LDPC code under different code lengths.Finally,in order to further improve the decoding performance,CSI is introduced in the decoding process,and the combined factor graph of channel and coding is used to guide the information update process of iterative decoding,so as to carry out the BP decoding algorithm under the GE-AWGN channel.Effective improvement.The simulation results show that the optimized BP decoding algorithm has better decoding performance and is closer to the channel capacity.