Performance Analysis And FPGA Implement On Turbo Codes In Wireless Communication

Channel coding as a key technology of channel anti-jamming technology, it can effectivelyreduce the probability of sudden mistakes when signals transmit in the wireless or wiredchannel,and ensure the signal ’s reliability and validity in the process of transmission, andultimately ensure the quality of communication. As people make in-depth exploration andresearch on the channel coding technology for a long time, noisy channel coding theorem ispresented by Shannon in1948. Shannon channel coding theorem provides a powerful platformfor the future generations continue to research error correcting codes, as well as points out acorrect path for the channel coding researchers. The error correction performance of Turbo codescan approach the Shannon theoretical limit. And it is a kind of concatenated codes proposed onthe basis of the channel coding theorem. Because Turbo codes have very good ability of errorcorrection, so it has a very wide application market and development space in thecommunication field. Firstly, this paper mainly introduces the basic principles of the encodingand decoding of Turbo codes, followed by a theory analysis of the key part of Turbo encoder anddecoder. The two kinds decoding algorithm of Turbo codes was derived in detail, one kind is themaximum a posteriori probability (MAP) algorithm and its simplified algorithm, another kind isSoft Output Viterbi Algorithm (SOVA). Make an analysis and comparison on the computationcomplexity of two kinds of decoding algorithm. In addition, analysis the major factors which areaffecting the error rate performance of Turbo codes through MATLAB simulations, and theMATLAB simulation is in additive white gaussian noise (AWGN) channel model. Secondly, thispaper make use of MATLAB to simulate the bit error rate (BER) of Turbo codes in Rayleighfading channel and rice fading channel, and compare them with the BER in AWGN channel.Analysis and discuss the adaptive wireless communication environment of Turbo codes in thepractical application. Finally, this paper select Xilinx ISE integrated development platform, andrealize the FPGA design of the Turbo encoder and decoder by using Verilog HDLlanguage, and through the ModelSim waveform simulation tools to timing simulation of thegiven information sequence, observe the rearrange of information sequence and decodingprocess.Through the observation of the simulation waveform and compare the results with thetheoretical value, eventually be able to prove the correctness of the Turbo encoding decoderFPGA design.