一种 1x2x4分布式空时编码异步协作方案

协作分集技术可以有效提高移动通信系统的容量和可靠性。近年来，分布式空时码（DSTC）被广泛应用到协作分集系统以实现空间分集增益。然而，时间异步和频率异步会使正交DSTC的码字结构受到破坏，严重影响系统性能。本文针对时间异步的协作通信系统，提出一种基于分布式Alamouti STBC的1x2x4异步协作方案。对这种方案进行了理论分析和算法推导，并且重新定义了中继节点归一化后的发射信号幅度。仿真结果表明该方案的误比特率性能具有明显优势，能在时间异步的协作通信系统中很好地发挥多天线接收性能。

An 1x2x4 Distributed STBC Asynchronous Cooperative Scheme

The cooperative diversity technique can efficiently improve coverage and reliability of mobile communication systems. In recent years, Distributed Space Time Coding (DSTC) has been widely used in cooperative communication system to achieve spatial diversity gain. However, the time asynchronism and frequency asynchronism will destroy the structure of orthogonal DSTC, which may drastically undermine the system performance. In this paper, we propose an 1x2x4 time asynchronous cooperative scheme based on distributed Alamouti STBC. We provide theory analysis and algorithm derivation of the scheme. In addition, we redefine the normalized range of transmitting signal at relay nodes. The simulation results demonstrate that the proposed scheme has better bit error rate (BER) performance and realizes multiple antennas receiving performance in time asynchronism cooperative communication system.