深空通信中的线性Log-MAP算法

Linear Log-MAP Algorithm in Deep Space Communications

Turbo码由于具有逼近香农信道容量限的性能,已经被CCSDS标准采纳。译码算法是Turbo码译码的关键组成部分,也是影响其性能的关键因素,而MAP类译码算法以其优越的性能成为译码算法的主体。在对MAP类译码算法的译码复杂度和性能仿真对比、分析的基础上,针对深空通信中的低信噪比、低误比特率的要求,提出一种线性Log-MAP算法方案,该方案在保证性能损失尽可能小的前提下,有效降低了计算复杂度,适用于深空通信的实际要求。

Turbo code is adopted as a standard in CCSDS because of its performance close to the Shannon capacity limits. The adopted decoding algorithm plays an important role in the performance of corresponding Turbo code, and MAP-like decoding algorithms becomes a principal part of decoding algorithm because of their excellent performances. Since a low bit error probability at a low signal-to-noise ratio is a basic requirement in deep space communications, this paper makes the simulation analysis and comparison of decoding complexity and performances of MAP-like decoding algorithms, and then proposes a linear Log-MAP algorithm scheme, in which the computing complexity is largely reduced with small performance loss. The simulation results show that the linear Log-MAP algorithm can meet the requirements of deep space communications.