【作者】 李自义；

【导师】 陈彦辉；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2008， 硕士

【摘要】 串行级联连续相位调制(SCCPM:Serially Concatenated Continuous Phase Modulation)系统不仅具有很高的频谱利用率和功率利用率,而且具有类似于Turbo码卓越的误码性能。由于连续相位调制可以分解为一个连续相位编码(CPE:Continuous Phase Encoder)和一个无记忆调制器(MM:Memoryless Modulator),而连续相位编码器实际上就是一个简单的递归卷积码,SCCPM不需要独立的内码,具有与串行级联卷积编码(SCCC:Serially Concatenated Convolutional Codes)相似的结构。SCCPM系统进行软输入软输出的迭代译码可以获得很高的交织增益,因此在快衰落和极低的信噪比环境中,SCCPM具有更好的性能,这些优点使得其特别适合于跳频系统和军用Ad-Hoc网络。本文主要研究了串行级联连续相位调制系统的性能,以及迭代译码算法和系统的DSP实现。本文首先介绍了CPM的特点,推导出CPM的分解模型,在此基础上提出了SCCPM的系统模型,通过计算机仿真得到SCCPM的系统性能;然后深入研究了迭代停止译码算法,提出了一种基于平均外信息交换的迭代停止译码算法,仿真结果证明该算法能够在保证系统性能的前提下大大降低了计算的复杂性,缩短了译码的时间;最后对SCCPM的实际应用进行初步的探索,在DSP软环境下实现了该系统。更多还原

【Abstract】 Recently, serially concatenated CPM (SCCPM) systems with high spectral efficiency, power efficiency and some turbo-like coding performance draw more attention. Since CPM can be decomposed into a continuous-phase encoder(CPE) and a memory-less modulator(MM),and the CPE is equivalent to a convolutional encoder, there is no need of inner code in SCCPM which has the similar structure compared with serially concatenated convolutional codes. SCCPM with iterative decoding based on soft-input soft-output (SISO) shows a large interleaving gain. It is robust under highly dynamic and fading environment, which is suitable to frequency hopping system and military‘ad hoc’networks.In this thesis Serially Concatenated Continuous Phase Modulation (SCCPM) and its performance are mainly studied, as well as the algorithms of iterative decoding and the implementation of this system with digital signal processor (DSP). First of all, based on the principle of the CPM signal, a decomposition approach to CPM is developed, and then we present the system model of SCCPM and obtain its performance through computer simulation; secondly, through analysis to the stopping algorithm of dynamic iterative decoding, a new stopping algorithm based on average extrinsic information exchange is proposed, simulation result shows that the combination of average extrinsic information exchange and stopping algorithm of dynamic iterative decoding can improve the BER performance as well as reduce iterative decoding time. Finally we primarily explore the application of SCCPM, and implement it in DSP simulation environment.更多还原