Two-way Full Duplex Cooperative Distributed Space-Time Coding

Because of limited spectrum resources, we have to further study new communication technologies to solve problems which today's mobile Internet communications is facing. Wireless communication systems need to be able to provide more data services, multimedia services and high rate in the future. And cooperative communications just use the nodes in the network to help a needed-communication node get high-speed, reliable wireless communications. Therefore, cooperative communication technology is expected to become the next key communication technology.Network nodes work in a HD or FD mode. Half-duplex cooperative communications can obtain full diversity gain. With the urgent need for frequency resources, many scholars and institutions naturally apply the half-duplex communications network to full-duplex relay networks, because theoretically its frequency efficiency can be doubled. But if these space-time coding schemes are directly applied to a full-duplex relay system, it will face serious loop self-interference. Therefore, analyzing how to eliminate interference becomes the key point for the full-duplex relay network.In this paper, based on one-way full duplex cooperative systems, we propose a two-way full duplex cooperative distributed space-time coding. Each node in this system works in FD node.and can communicate each other, due to that it can greatly improve the spectrum utilization. In this paper, according to analyzing the loop self-interference of all nodes, we eliminate part of loop self-interference and build distributed cooperative space-time codes with using the remaining self-interference. At the same time, according to the inherent characteristics of two-way communication, we utilize the most optimal power amplification factor criteria which can gain the overall optimal performance. Also we analyze the influence of the residual interference at the terminal node and the relay node with simulation. Especially with the relatively good information of channel state, the two-way full-duplex asynchronous cooperative distributed space-code can achieve full diversity gain and improve the system performance and capacity.