协作通信系统中分布式空时编码及相关技术的研究

发布时间：2018-07-10 02:46

本文选题：协作通信 + 分布式空时编码　；参考：《天津大学》2014年博士论文

【摘要】：无线通信系统中，为了进一步提高传输速率和传输可靠性，研究者们提出了协作通信技术。其基本思想是：网络中每个节点向目的节点发送信息的同时，作为中继帮助其他节点转发信息。通过节点间共享彼此的天线，组成虚拟的多输入多输出(MIMO)系统以获得空间分集增益，进而提高系统性能。协作通信技术可以有效增加分集增益，扩大网络覆盖范围并降低终端发射功率，得到了工业界和学术界的广泛关注，并有望成为第四代移动通信系统的关键技术之一。本文针对协作通信系统中的分布式空时编码技术及其检测技术展开研究，重点解决非同步协作通信系统中码间干扰（ISI）估计和消除问题，，以及半双工中继网络中的满速率传输问题：首先，针对非同步协作通信系统中的ISI问题，提出了基于非相干检测的ISI估计和消除算法。该算法使用分布式差分空时编码技术，在目的节点不知道任何信道状态信息（CSI）和定时误差信息的情况下，实现ISI的消除，并获得较好的误码率性能。该算法计算复杂度低，对码字速率影响小，并有效解决了传统ISI消除方案中CSI估计复杂度高，实现难度大的问题。接着，本文研究了具有满码字传输速率半双工中继传输方案的误符号率，重点分析了两通路连续中继（TPSR）方案和满速率传统中继方案。文中给出了上述两种方案的误符号率，进一步分析：满速率传统中继方案在调制阶数很低的情况下性能略优于TPSR方案，而调制阶数较高时，TPSR方案性能更优。即TPSR方案适用于高速无线网络。最后，针对TPSR网络引起的中继间干扰（IRI）问题，提出了两种IRI消除方案：部分IRI消除方案和基于信号空间分集（SSD）编码的差分传输方案。部分IRI消除方案中，目的节点保留部分IRI信号作为码字符号的副本，在译码过程中加以利用以提高系统性能。同时，针对这一方案译码复杂度较高的问题，提出迭代最大比合并译码算法，并给出了相应的分集增益分析和性能仿真。结果表明，部分IRI消除方案可获得额外分集增益并有效降低误符号率。最后，本文提出了基于SSD编码的差分传输方案以解决基于AF中继的TPSR网络中CSI估计复杂度高的问题。该方案中，目的节点无需知道任何CSI，而中继节点仅需估计中继间信道，即可有效消除IRI并对接收信号进行非相干译码，具有较低的计算复杂度和CSI估计复杂度。
[Abstract]:In order to further improve the transmission rate and transmission reliability in wireless communication systems, researchers proposed cooperative communication technology. The basic idea is that while each node in the network sends information to the destination node, it helps other nodes to forward the information as a relay. By sharing each other's antennas among nodes, a virtual multiple-input multiple-output (MIMO) system is constructed to gain spatial diversity gain and improve system performance. Cooperative communication technology can effectively increase diversity gain, expand network coverage and reduce terminal transmission power. It has been widely concerned by industry and academia, and is expected to become one of the key technologies in the fourth generation mobile communication systems. In this paper, the distributed space-time coding technology and its detection technology in cooperative communication systems are studied, and the problem of ISI estimation and elimination in asynchronous cooperative communication systems is emphatically solved. And the full-rate transmission problem in half-duplex relay networks. Firstly, an ISI estimation and cancellation algorithm based on incoherent detection is proposed for the ISI problem in asynchronous cooperative communication systems. The algorithm uses distributed differential space-time coding (DSTC) to eliminate ISI and achieve better BER performance without knowing any channel state information (CSI) and timing error information. The algorithm has low computational complexity and little influence on codeword rate, and effectively solves the problem of high CSI estimation complexity and difficult implementation in the traditional ISI elimination scheme. Then, the symbol error rate of the half-duplex relay transmission scheme with full codeword transmission rate is studied, and the two-channel continuous relay (TPSR) scheme and the traditional full rate relay scheme are analyzed. In this paper, the symbol error rate of the two schemes is given, and further analyzed: the performance of the traditional full rate relay scheme is slightly better than that of the TPSR scheme when the modulation order is very low, but the performance of the TPSR scheme is better when the modulation order is higher. That is, TPSR scheme is suitable for high speed wireless network. Finally, aiming at the inter-relay interference (IRI) problem caused by TPSR network, two kinds of IRI cancellation schemes are proposed: partial IRI cancellation scheme and differential transmission scheme based on signal space diversity (SSD) coding. In the partial IRI cancellation scheme, the destination node retains part of the IRI signal as a copy of the codeword symbol and uses it in the decoding process to improve the system performance. At the same time, aiming at the high decoding complexity of this scheme, an iterative maximum ratio merge decoding algorithm is proposed, and the corresponding diversity gain analysis and performance simulation are given. The results show that the partial IRI elimination scheme can obtain additional diversity gain and reduce symbol error rate effectively. Finally, a differential transmission scheme based on SSD coding is proposed to solve the problem of high CSI estimation complexity in AF relay based TPSR networks. In this scheme, the destination node does not need to know any CSI, and the relay node only needs to estimate the inter-relay channel, which can effectively eliminate the IRI and decode the received signal incoherently, which has low computational complexity and CSI estimation complexity.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN92

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