Research On The Mobility Of Relay In Cooperative Communication Systems

Cooperative communication has become a hot research topic in the wireless communication systems, because it can resist the fading and interference and improve the utilization of the system by introducing the cooperative diversity and relay. This thesis puts forward the mobile relay selection strategy by analyzing the mobility of the relay node. The main works are as follows:(1) The simulation and analysis of the fixed relay performance in AF and DF mode are made. It can be found that the bit error rate(BER) of the system decreases with the signal-to-noise ratio increases in both AF and DF mode by simulation. In the same signal-to-noise ratio conditions, the BER of the DF is better than that of AF.(2)For the mobile relay node, this thesis analyzes the impact of relay node location on the system and shows that the research on mobile relay is very important. Then this thesis puts forward the relay selection strategy for the single and multiple relay cooperative mode. It can be concluded that the system break probability fluctuations is in a better range by switching the relay node from the simulation results. And the diversity gain and system capacity of the multi relay cooperative mode is better than that of the single relay mode.(3) Considering the actual wireless communication environment, there are more than one cell and the interference signals comes from the adjacent cells. Taking the single relay node cooperation as an example, the mobile relay nodes election strategy is proposed for the interference suppression and inter-cell coordination. It indicates that the adjacent cell cooperative scheme can effectively resist the inter-cell interference. Also the system can obtain the space diversity gain in this way.