摘要双向中继技术，与单向中继相比,能在不增加基站数目的前提下，提高无线通信网络的系统容量和频谱效率，减小覆盖盲区，增强传输可靠性，未来将有望应用于卫星通信和移动通信等领域。

本文主要研究无线协作通信系统中的双向中继波束成形技术，分别给出了单用户对和多用户对双向中继系统模型，针对前者分析比较了基于放大转发(Amplify-and-forward，AF)的三种波束成形技术，分别是迫零（Zero-forcing, ZF），最小均方根误差（Minimum mean square error, MMSE）和最大和速率（Maximizing sum-rate, MSR）。仿真结果表明在和速率与误码率(Bit error rate, BER)性能方面，MSR方案最优，而MMSE方案优于ZF方案。在计算复杂度方面， MSR方案最复杂，ZF方案最简单。61686

针对多用户对双向中继系统模型，首先研究对比了基于AF的ZF、块对角化(Block-diagonalization, BD)和奇异值分解（Singular value decomposition, SVD）波束成形方案。仿真结果表明，在和速率与误码率性能方面，SVD方案优于BD方案，而MMSE方案优于ZF方案。但是SVD方案需要用户端完全协作，实际系统中实现难度较大。

其次研究了基于译码转发(Decode-and-forward, DF )的多用户双向中继系统，仿真比较了AF波束成形和BD波束成形的和速率性能，发现BD算法依然优于ZF算法，但是运算复杂度相对较高。

毕业论文关键词  双向中继  波束成形  单用户对  双用户对  放大转发  译码转发  迫零  最小均方误差  最大和速率  块对角化  奇异值分解

毕业设计说明书（论文）外文摘要

Title  Precoding  and   Beamforming   for   Two-way Relaying  Cooperative  Wireless  Communication  Systems                       

Abstract Compared with single-way relaying, two-way relaying can improve both system capacity region and spectrum efficiency, reduce blind areas of coverage and enhance transmission reliability without increasing the number of base stations in wireless networks. In the coming future, relaying will probably be applied to satellite communication and mobile communication, etc.

This paper mainly studies the two-way relay beamforming techniques in wireless cooperative communication system. Single-pair and multi-pair two-way relay systems are respectively established. For the former, three typical relay beamforming algorithms based on amplify-and-forward (AF) are studied and compared as follows: zero-forcing (ZF), minimum mean square error (MMSE) and maximizing sum-rate (MSR). Simulation shows that in terms of sum-rate and bit error rate (BER), MSR performs the best while MMSE is better than ZF. As for complexity, MSR> MMSE>ZF.

With regard to multi-pair two-way relay system, ZF, block-diagonalization (BD) and singular value decomposition (SVD) algorithms based on AF are investigated. Simulation shows that SVD outperforms ZF and BD in terms of sum-rate and BER while BD outperforms ZF. However, SVD algorithm is almost impossible to be put into practice due to its requirement of full collaboration among user stations.

Afterwards, multi-pair two-way relay system based on decode-and-forward (DF) is studied. The sum-rate performance of ZF and BD algorithms are compared through simulation. Still, BD outperforms ZF at the expense of higher computational complexity.

Keywords  Two-way  relay  beamforming  single-pair  multi-pair  AF  DF  ZF  MMSE  MSR  BD  SVD

1 绪论 1

1.1 研究背景和意义 1

1.2 双向中继研究现状