协同网络中AR码的度分布优化设计

Optimal Designing of Degree Distribution of AR Code in Collaborative Network

在大规模网络中,固定码率的信道编码自适应性较差,严重影响传输性能。针对这一问题,提出了一种基于累积无码率码(Accumulate Rateless Code,AR码)的协同传输方案,并利用外信息转移(Extrinsic Information Transfer,EXIT)图对该方案下的软信息迭代译码模型进行整体分析,以最大化码率为目标,设计了一种AR码的联合度分布优化方法,并给出三种求解策略,解决了AR码应用到协同网络中度分布优化的问题。理论分析与仿真结果均表明,该文所提方法求得的度分布在译码性能上,均优于LT码经典度分布及现有方法所得AR码的度分布,能够降低错误平层至10-6以下,并至少减小6.25%的码率倒数。同时,基于AR码的协同传输方案具有很好的自适应特性,提高了低信噪比网络的传输性能。

Channel coding with fixed rate in large-scale network communication has poor adaptability,which greatly affects the reliability of information transmission.In order to solve this problem,this paper proposed the cooperative transmission mechanism in Accumulate Rateless Code(AR Code).Then it made an overall analysis of soft information iterative decoding model with extrinsic information transfer(EXIT)chart,and designed the scheme of joint optimization of degree distribution of AR Code for the goals of maximizing the code rate.And three kinds of solution strategies was given.The method solved the problem of degree distribution optimization of AR code in collaborative network.The theoretical analysis and simulation results have shown that the degree distribution of AR code gave by our method is better than that of classical degree distribution of LT codes and the degree of existing AR code distribution optimization results in decoding performance.It can reduce the error floor below 10-6,and get a 6.25%reduction of the reciprocals of code rate at least.Meanwhile,the cooperative transmission scheme based on AR code has the very good adaptive characteristics,and improves the network transmission performance of low signal to noise ratio(SNR).