Distributed space-time block coding for cooperative diversity

协作分集是一种允许无线终端集群通过为彼此中继信号来协作的方案，并且因此改善了所有无线终端与接入点的链路。在过去的几年里，已经提出了几个这样的计划，并在理论上表明，它们可以导致显着的性能改善。然而，在实现这种方案中可能遇到的实际问题上，很少有工作，例如来自节点的传输的同步，以及尤其是中继将如何实际实现。本项目将研究使用基于空时分组码的方案的实际实现，空时分组码是在多个发射天线上实现分集传输的一种非常简单而有效的方式。它将首先调查这样一个系统的同步和信道估计误差的影响，然后调查实际的方法来克服这些问题，例如，使用迭代解码和估计技术。在协作分集系统中，通过利用通过单天线终端的网络的多个路由而不是单个终端上的多个天线来提供分集。该方案还将根据网络编码的概念，研究这种方法的一种更一般的模式，这种模式将来可以提供更有效的合作分集办法。

Cooperative diversity is a scheme which allows a cluster of wireless terminals to collaborate by relaying signals for one another, and thus improve the link with an access point for all of them. Several such schemes have been proposed over the past few years, and have shown in theory that they could result in a remarkable improvement in performance. However there has been little work on the practical problems likely to be encountered in implementing such a scheme, such as synchronisation of the transmissions from the nodes and, not least, how the relaying will actually be implemented. This project will investigate practical implementation using a scheme based on space-time block codes, which are a very simple and effective way of implementing diversity transmission over multiple transmitting antennas. It will first investigate the effect of synchronisation and channel estimation errors on such a system, and then investigate practical ways to overcome these problems, using, for example, iterative decoding and estimation techniques. In a cooperative diversity system the diversity is provided by exploiting multiple routes through a network of single-antenna terminals, rather than multiple antennas on a single terminal. The programme will also investigate a more general model of this approach, based on the concepts of network coding, which could provide more efficient cooperative diversity schemes in the future.