多输入多输出电力线通信系统中的空时编码策略研究

发布时间：2018-03-28 10:57

  本文选题：多输入多输出-正交频分复用-电力线通信　切入点：差分空时码　出处：《安徽工业大学》2017年硕士论文

【摘要】：智能电网因能使电力供应达到节约能源、降低损耗、增强可靠性而成为业界研究的热点。然而,智能电网的诸多功能都有赖于实时操作才能付诸实施,这使得智能电网中各个终端间快速而可靠的通信成为其成功的重要因素。由于多输入多输出电力线通信(MIMO-PLC)可借助原有的电力网基础设施实现电力网络全覆盖的同时,成倍提高系统容量和频谱利用率,而空时编码是实现MIMO-PLC的关键技术。为此,本文围绕多种差分酉空时码MIMO-PLC系统方案展开研究,并结合仿真对比分析这些编码系统的性能。首先,本文在研究了MIMO-PLC系统传递函数以及噪声分布模型基础上,提出了在接收端无需预知信道状态信息的差分酉空时码应用于该系统的方案。该方案首先将信息数据分别映射到满足分集积准则的实参对角块酉矩阵星座上,并以差分方式形成酉空时码字;随后,相应码字经数模转换后,耦合到不同的电力线端口通过电力线信道发送出去;最后,收端采用最大似然译码得到发送信息的估计值。仿真结果表明:对于系统数据率要求较低的MIMO-PLC系统,差分酉空时码能够显著提高其性能,并且在电力线脉冲噪声幅值较大时,优势更加显著。其次,针对差分酉空时码中满足分集积准则的酉矩阵难以构造以及数据率低的问题,提出了将Cayley差分酉空时码应用于MIMO-PLC系统的方案。该方案首先将携带信息的酉矩阵的高度非线性Stiefel流形映射到由斜Hermite矩阵表征的线性空间上,从而可在Cayley变换域和信息理论的基础上,构造出满足柯西随机分布的线性酉矩阵星座。仿真结果表明:尽管Cayley差分酉空时码会一定程度提高系统误码率,但由于其可显著提高系统的数据率,这点对于数据率要求较高的MIMO-PLC系统显得尤为重要。随后,针对MIMO-PLC系统在传输高速数据时,环境的多径使得MIMO信道成为频率选择性衰落信道的问题,提出了将基于正交空时分组码的正交频分复用(OFDM)多载波调制应用于宽带PLC系统的方案。该方案通过把频率选择性信道转化为一个等价的多个平坦衰落子信道构成的集合,结合43?正交空时分组码,这样,用于传送每个OFDM分组的每个载信空时符号的子载波可以认为在平坦衰落信道内传输。仿真结果表明:该编码系统随着子载波数的增加,性能得到显著提高。最后,为解决矩阵Stiefel流形的非线性导致酉矩阵星座难以构造以及信号集和与费用函数的非凸性问题,文章首先提出了将基于特殊李群SP(1)、SU(3)的差分酉空时码应用于MIMO-OFDM-PLC系统中的方案。以上编码方案分别通过放宽可达到满分集的不动点群的约束条件,在非线性特殊李群中诱导满足分集积准则的线形酉矩阵星座。随后,在忽略SU(3)酉矩阵行列式为1的约束条件下,进一步简化结构条件构建了两种AB差分酉空时码。仿真结果表明:以上多种编码方案,可在不牺牲系统性能的前提下,提供更高的数据率并获得较高的分集积;随子载波数增加,基于SP(1)的差分酉空时码误码率显著降低,而后三种编码会有一定程度的提高。
[Abstract]:Because of the smart grid can make power supply to save energy, reduce loss, improve reliability and become the focus of the industry. However, many functions of the smart grid implementation will depend on real-time operation ability, which makes the smart grid in each terminal between the fast and reliable communication has become an important factor in its success. Because of the multiple input multiple output power line communication (MIMO-PLC) by means of power network infrastructure original power network coverage and improve the system capacity and spectrum efficiency exponentially, while the space-time encoding is the key technology to implement MIMO-PLC. Therefore, this paper focuses on several differential unitary space-time code scheme for MIMO-PLC system is studied, and combined with simulation analysis the performance of these encoding system. Firstly, based on the study of the MIMO-PLC system transfer function and noise distribution on the basis of the model, put forward at the receiving end without knowing Program code is applied to the system of channel state information for differential unitary space-time. In this scheme, the information data are mapped to satisfy the argument block diagonal unitary matrix constellation diversity product standards, and the formation of unitary space-time codes in a differential manner; then, the corresponding code word DAC, coupled to the power line different port through the power line channel to send out; finally, the receiver estimates using maximum likelihood decoding by sending information. The simulation results show that the MIMO-PLC system data rate low, DUSTM can significantly improve its performance, and the larger the amplitude of impulse noise in power line, more advantages significant. Secondly, according to the diversity criterion to unitary matrix product structure and the problem of low data rate meet the code in differential unitary space-time, put forward the Cayley difference scheme code used in MIMO-PLC system. The scheme consists of unitary space-time Highly nonlinear manifold mapping Stiefel unitary matrix will first carry information to the linear space of skew Hermite matrix representation, which is based on Cayley transform and information theory, construct the linear unitary matrix constellation Cauchy random distribution. The simulation results show that although Cayley DUSTC will to a certain extent to improve the system BER, but because it can significantly improve the system data rate, which is particularly important for the data rate requirement of MIMO-PLC system is higher. Then, according to the MIMO-PLC system in high speed data transmission, multipath MIMO channel environment makes a frequency selective fading channel, the orthogonal frequency orthogonal space-time block codes based on wavelength division multiplexing (OFDM) multi carrier modulation is applied to broadband PLC system is proposed. The scheme through the frequency selective channel into a plurality of flat an equivalent 琛拌惤瀛愪俊閬撴瀯鎴愮殑闆嗗悎,缁撳悎43?姝ｄ氦绌烘椂鍒嗙粍鐮，

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