Research On Relay Selection In Wireless Cooperative Networks

Cooperative communications are not only the product which multiple inputmultiple output (MIMO) system develops to a certain stage, but also the application ofMIMO system in the constrained mobile terminal equipment. Thus it continues theadvantages of MIMO system, and inherits its nature of using spatial diversity tocombat wireless channel fading. By using each other’s antennas to form virtualMIMO system, cooperative communication technology overcomes the problem thatsmall mobile terminal can’t be equipped with multiple antennas, further it enhancesthe ability of portable mobile devices to go against fading, and improvescommunications reliability. At the same time, cooperative communication technologyeffectively extends the usage time of battery-operated devices, and extends thedistance of wireless communication and the network coverage.As a key component of the cooperative communication system, cooperativepartner has a very important role on system performance. The good performance ofcooperative communications is closely related to the choice of relays. To a largeextent, the selection of relays determines the overall performance of the system.For cooperative communication in wireless cooperative networks, this paperfocuses on the research of partner selection strategy. In this paper, the relay selectionstrategy is considered mainly from two aspects. On one hand, it is fairness andpriority. Relay selection and cooperative nodes residual power are joined to avoid thatthe ones with good channel quality run out of power, which results to die early, andprolongs the network lifetime. Simultaneously, firstly, we sort signal-to-noise ratio ofthe links from source to destination for the priority of source. Secondly, using relayselection strategy, we pick out the one with good quality to help the source with theworst SNR forwarding its information to destination. So, these methods may optimizeand improve overall network performance. On the other hand, it is complexity. Indecode-and-forward (DF) protocol, we use the new method which firstly selects relay,then judges whether it can decode source information correctly, rather than thetraditional partner selection process which decides to the decoding set and thenchooses the best relay from it. Thus it is highlight the advantages of low complexitywhen the network size is large. Simulation results show that the improved relay selection scheme proposed in this paper has a distinct advantage in both the fairnessand the complexity.