HARQ protocols for cooperative networks

本研究计划的目的是增进我们对在协作通信网络中部署所谓的HARQ协议的基本原则、限制和权衡的理解。网络中终端之间的协作被视为提高无线环境中通信的覆盖范围、速率和可靠性的一种方式。它通常采用中继的形式，终端之间相互帮助，将信息传递到各自的目的地。在无线环境中，传输错误是不可避免的，因此有必要考虑通过所谓的混合自动重传请求(HARQ)协议进行重传。虽然HARQ在点对点通信中是一种众所周知的机制，但在协作网络的环境中部署HARQ并不是一件容易的事情，因为由于存在许多终端，重传的可能性显著增加。由于中继可能使用所谓的网络编码，因此说明和分析如何有效地将其与基于中继的HARQ相结合是很重要的。

The objective of this research program is to increase our understanding of the fundamental principles, limitations, and trade-offs related to the deployment of the so-called HARQ protocols in the collaborative communications networks. The collaboration between the terminals in the network is seen as a way to increase the coverage, the rate, and the reliability of the communication in the wireless environment. It usually takes the form of relaying, where the terminals help each other to convey information to their respective destinations. In the wireless context, the transmission errors are unavoidable so it is necessary to consider retransmission via the so-called hybrid automatic repeat request (HARQ) protocol. While it is a well-known mechanism in point-to-point communications, deploying HARQ in the context of collaborative network is not trivial because the number of retransmissions possibilities is significantly increased due to the presence of many terminals. Another dimension to the problem is added since the relays may use the so-called network-coding and thus it is important to elucidate and analyze how to combine it efficiently with the relay-based HARQ.