无码率码在无线传感器网络中的应用研究

传统固定码率通信方案在大规模网络中存在时延和多反馈情况，影响无线传感器网络(wireless sensor network, WSN)的传输性能。无码率码能够根据信道状态实时改变传输码率，很好地解决这一问题。本文以多源多中继网络模型为基础，设计了基于累积无码率(accumulate rateless, AR)码的分布式协同传输机制，并对传输的广播、转发、译码等阶段进行了阐述和分析。结合使用外信息转移(extrinsic information transfer, EXIT)图和凸优化工具对方案中的AR码度分布进行了联合优化求解。仿真结果和对比分析表明，所提分布式AR码度优化方案，在错误平层上明显优于分布式卢比转换码方案，在译码性能上较现有Raptor方案和AR码单独度分布优化方案分别减小3.7%和1.3%的码率倒数。

Research on application of rateless code in wireless sensor network

The traditional fixed bit rate communication scheme has time delay and multiple feedback in large scale network, which affects the transmission performance of wireless sensor network (WSN). And rateless code, which changes its transmission rate according to real-time channel state, can solve this problem very well. This paper designs the distributed cooperative transmission mechanism in accumulate rateless (AR) code based on the multiple source relay network model, and makes the detailed elaboration and analysis of the transmission phases of broadcasting, forwarding and decoding. Then it optimized the degree distribution of AR code jointly in the scheme using the methods of extrinsic information transfer (EXIT) and convex optimization. By the simulation results and comparative analysis, the proposed distributed degree optimization scheme of AR code is obviously better than the LT scheme of classical distribution in error floor. And compared with the existing Raptor scheme and the AR code singleness distribution optimization scheme, the code rate reciprocal is reduced by 1.3% and 3.7% respectively.