Research Of Joint Design Of Network-Channel Coding On Relay Nodes

Network coding allows the relay node forward and encode the information receivedthrough multiple paths, then the destination node obtains the original information by thecorresponding decoding, makes communication networks can achieve the maximum capacity,maximum use of existing network resources. Network coding becomes the research focus ofwidespread concerning. Because of it can improve the network’s throughput, has betterrobustness, and effectively improve the efficiency of forwarding by relay nodes. Therefore, inthe relay node, a joint design of network-channel coding can further improve BERperformance of the system BER performance.This paper first introduces channel coding and network coding techniques. Based on theLDPC codes’ principle, we joint design channel and network coding on relay nodes. Thenforward it to destination nodes. We call this code as network LDPC coding.Second, Based on the research of Razaghi, who designed the two kinds of Bilayer-LDPCcodes (divided into Expurgated and Lengthened type), we propose a kind of network-channelcoding called NBL-LDPC code (Network Bilayer Lengthened LDPC, referred to as theNBL-LDPC). Meanwhile, shows the process of encoding and decoding, and for this code, theGaussian density evolution algorithm has to be improved, so the BER performance can becalculated and simulated. Simulation results show that the proposed coding scheme performsbetter than the NBE-LDPC code (Network Bilayer Expurgated LDPC, referred to asNBE-LDPC).At last, this code makes use of PSO to optimize the degree distribution sequence. Particleswarm optimization (PSO) is a typical group of intelligent evolutionary algorithm, particleaction is decided by the history best position and global best position. The particle swarmalgorithm and EXIT curves of LDPC codes is combined, the cost function value is used ofanalyzing the size of the optimization iterations, then we can search for the optimal degreedistribution sequence. Using Gaussian approximation algorithms calculate the bit error rate.Simulation results show that, PSO algorithm can effectively improve the BER of NBL-LDPCcode.