π/4-DQPSK信号的迭代差分检测  

Iterative differential detection forπ/4-DQPSK signals

作　　者：张君[1] 李静[1] 彭华[1] 

机构地区：[1]信息工程大学信息工程学院,河南郑州450002

出　　处：《信号处理》2009年第2期334-338,共5页Journal of Signal Processing

摘　　要：为了提高π/4-DQPSK信号在差分检测中的性能,本文提出了一种基于比特APP(A Posteriori Probability)差分解调和软判决译码联合迭代处理的新的检测方法。该方法将Brink系统模型推广至差分编码信号,软解调时不依赖网格结构,而是直接利用了星座映射引入的相关性和信道译码的反馈信息,获得了系统复杂度的降低;通过编码比特的软信息在解调器与译码器间的充分交换,实现系统低信噪比环境下整体误比特性能的提高。仿真结果表明,在无码间干扰的AWGN信道下,接收信号大于3.5dB时,文中的差分检测方法仅需迭代3次就可获得低于10^(-4)的误比特性能,较同条件的迭代相干检测只有约1.4dB的性能损失。This paper considers the improvement of differential detection for coded π/4-DQPSK signals with bit-interleaved, which would be an extended application of the detection system proposed by Dr. Brink for these absolute encoded signalings. Based on the principle of iterative decoding, the signals is joint demodulated and decoded in a differential fashion. A soft demodulator using bit-bybit MAP algorithm is specially designed,which generates ＂soft information＂ from constellation and provides the reliability of demapped bits for followed MAP convolutional decoder. The iterative detection is one of the ways to approach the global optimum performance, which, in a certain extent, remedies the penalty leaded by differential detection. Simulation results for the reception of π/4-DQPSK sig- nals transmitted over non-ISI AWGN channel, shows performance well even at low SNR,which outperform the conventional system,fur- thermore,only inferior to the coherent system with 1.4dB when BER is 10-4.

关 键 词：解调译码联合处理 逐符号MAP算法 APP差分解调 软信息 

分 类 号：TN914.3[电子电信—通信与信息系统]