相移键控(MPSK)论文：多符号差分相移键控(PSK)调制半定松弛检测算法研究.doc

相移键控(MPSK)论文：多符号差分相移键控（PSK）调制半定松弛检测算法研究【中文摘要】相移键控MPSK调制技术是数字通信中常用的调制技术。使用MPSK调制一般情况下需要进行相干解调,这就需要进行信道估计,然而当通信系统信道变化太快或者天线数目较多时,这种信道估计就很难实现。尽管利用差分检测技术可以避免复杂的信道估计,但是它会导致性能的损失,而且在快衰落信道中会出现严重的误码平层问题。为了改善和提高差分检测的性能,人们提出了多符号差分检测(Multi-Symbol Differential Detection,MSDD)技术。目前,基于最大似然(ML)的MSDD是性能最优的,不过其复杂度会随着调制阶数和维数成指数增长。因此,能够降低ML-MSDD的复杂度十分有意义。半定松弛(Semi-definite Relaxation,SDR)检测算法便是很有效的一种,它已经在信号处理和通信系统中得到了广泛应用,如在波束成形技术、传感网络节点定位技术以及MIMO检测技术等。近来,已有文献将SDR应用到了MSDD中,提出了一种新颖的SDR-MSDD检测算法。该算法在大幅度减小复杂度的同时,也取得了优异的性能。不过该研究目前是基于QDPSK调制的,本文在对SDR检测算法及其在MIMO系统中的性能进行研究和分析的基础上,研究了适用于高阶MDPSK调制的SDR-MSDD算法,并在时变瑞利衰落信道中对其性能进行了仿真和分析。结果证明,在高阶情况下其性能也和最优的ML-MSDD检测性能非常接近,而且在这种高阶情况下,其复杂度要比球形译码低很多,同时也可以克服传统差分检测中存在的误码平层问题。由于软判决比硬判决能够提供更好的性能,同时考虑到MSDD的优异性能,本文将低秩半定松弛多符号差分检测算法与软判决译码结合,研究了基于最大后验概率(Maximum-a-posteriori,MAP)的低秩半定松弛多符号差分(MAP-SDR-MSDD)检测算法。本文推导了该检测算法的数学模型,详细阐述了该检测算法的原理和过程,并结合卷积码和Turbo码在时变瑞利衰落信道中进行了性能的仿真和分析。结果显示,该检测算法可以使系统的性能得以大幅度提升。【英文摘要】M-ary phase shift keying (MPSK) is a popular digital modulation technique in digital communication. Generally speaking, with MPSK modulation, if the coherent detection is adopted, the channel estimation is required. However, when the channel varies too fast or there are a larger number of antennas in the communication system, the channel estimation becomes very difficult. Although differential detection eliminates the need for explicit channel phase and amplitude estimation at the receiver side, it suffers from a performance penalty when compared to ideal coherent detection. In addition, a severe error floor occurs if differential detection is applied to rapid-fading channels. In order to improve the performance of differential detection, the so-called multi-symbol differential detection (MSDD) algorithm has been proposed.It is known that MSDD with respect to the maximum-likelihood (ML) criterion (ML-MSDD) is optimum in the performance. But the detection complexity grows exponentially with the modulation order and dimension size, if brute-force search is applied. Therefore, its very significant to reduce the complexity of ML-MSDD. The semi-definite relaxation (SDR) technique has shown great significance to reduce the complexity, and now it has been widely studied and applied in signal processing and communications, such as transmit beam-forming, sensor network localization and MIMO signal detection etc. Recently, a novel MSDD detection algorithm based on SDR (SDR-MSDD) has been proposed, which can reduce the complexity significantly and achieve excellent performance. However, this SDR-MSDD approach is used in system only based on differential QPSK modulation. In this paper, we first study the SDR technology and its performance in the MIMO system, and then extend SDR-MSDD from only based on differential QPSK modulation to be suitable for higher order differential MPSK (MDPSK) modulation. At last, the performance of the SDR-MSDD is studied in the time-varying Rayleigh fading channel. Analysis and simulation results verify that, for higher modulation alphabet size, the performance of the SDR-MSDD algorithm is very close to that of ML detection and the computational complexity is lower than that of sphere decoder.Considering the soft decision decoding (SDD) can provide better performance than that of the hard decoding (HDD), simultaneously taking into account the excellent performance of MSDD, we combine low-rank SDR-MSDD with the soft decision decoding and present a new algorithm for MSDD based on maximum a posteriori (MAP) and SDR, which is called MAP-SDR-MSDD. In this paper, a mathematical model of the MAP-SDR-MSDD detection algorithm is derived. Also, the principle and process is described in detail. At last, combining with convolutional codes and turbo codes in a time-varying Rayleigh fading channel, the performance of the proposed detection algorithm is simulated and analyzed. It is validated through simulations that the proposed MAP-SDR-MSDD algorithm can greatly enhance the performance of the system.【关键词】相移键控(MPSK) 半定松弛(SDR) 多符号差分(MSDD) 时变瑞利衰落信道 软判决译码 最大后验概率(MAP)【英文关键词】M-ary phase shift keying (MPSK) semi-definite relaxation (SDR) multi-symbol differential detection (MSDD) time-varying Rayleigh fading channel soft decision decoding maximum a posteriori (MAP)【目录】多符号差分相移键控（PSK）调制半定松弛检测算法研究摘要6-7ABSTRACT7-8第1章 绪论11-191.1 论文研究背景及意义11-161.1.1 半定松弛算法概述13-151.1.2 差分检测算法概述15-161.2 论文研究的主要内容16-171.3 论文结构及内容安排17-19第2章 MIMO系统中的SDR检测算法19-322.1 信道模型介绍19-202.1.1 高斯白噪声信道192.1.2 瑞利衰落信道19-202.2 MIMO系统模型20-212.3 SDR算法及在MIMO中的应用21-282.3.1 SDR算法简介21-242.3.2 SDR算法在MIMO中的应用24-282.4 仿真结果与分析28-312.5 本章小结31-32第3章 SDR在多符号差分相移键控(PSK)检测算法中的应用32-523.1 传统差分检测算法32-343.1.1 差分调制32-333.1.2 差分检测333.1.3 传统差分检测算法性能仿真与分析33-343.2 多符号差分检测算法34-433.2.1 ML-MSDD模型35-373.2.2 球形译码多符号差分检测37-393.2.3 半定松弛多符号差分检测39-433.3 仿真结果与分析43-513.3.1 算法性能分析43-493.3.2 复杂度分析49-513.4 本章小结51-52第4章 多符号差分相移键控调制SDR软解调研究52-664.1 引言52-534.2 最大后验概率(MAP)软解调53-554.3