基于后验概率判决的动态迭代停止算法

针对窄带低信噪比应用环境,提出了一种Turbo码与连续相位调制(CPM)级联的迭代接收方案。根据CPM的Rimoldi分解模型,引入Turbo迭代检测机制,利用软输入软输出(SISO)解调和译码算法,将内、外迭代相结合达到信息共享及纠错互补的目的。为了减小解调译码迭代时延,对不同迭代时刻译码器输出似然值进行推导分析,提出了一种基于后验概率判决(APPD)的动态迭代停止算法,并建立Turbo-CPM系统模型进行仿真。仿真结果表明:本文算法具有比流水线级联更优异的纠错性能,不仅可以有效减小迭代时延,而且能够改善系统的收敛性和可靠性。

Dynamic iteration stopping algorithm based on APPD

An iterative receiver scheme cascading Turbo codes with Continuous Phase Modulation(CPM) is proposed for low Signal to Noise Ratio(SNR) and narrowband applications.According to Rimoldi decomposition model of CPM,the purpose of sharing-information and correcting-complementary is achieved by combining the inner iterations with outer iterations.Turbo iterative detection is introduced and Soft-Input Soft-Output(SISO) demodulation and decoding algorithms are adopted.For reducing the iteration delay,a novel dynamic iteration stopping algorithm is presented based on A Priori Probability Decision(APPD).The likelihood at different iteration time is derived and analyzed.Turbo-CPM system model is built and simulation is carried out.Simulation results show that the error correction performance of the proposed iterative scheme is much better than that of the pipelining cascade at very low SNR.Meanwhile,the proposed stopping algorithm can not only reduce the iteration delay,but also improve the system convergence and reliability.