• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.134-143
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• 2009

In this paper, we propose a new relay selection algorithm for a two-way multiple relay channel. In the two-way multiple relay channel, two users exchange information with each other via multiple relays. The relays use a decode-and-forward or amplify-and-forward protocol, and exploit the combining process of the received packets to reduce the required channel resources. In the multiple relay network, diversity gain is achieved as the number of relays increases, and various schemes are proposed. In this paper, we propose a single best relay selection scheme based on instantaneous channel conditions. First of all, relays obtain the instantaneous channel state information in the handshaking process, and a single best relay is selected in a distributed methods prior to data transmissions. The relay selection metric is proposed so that the end-to-end channel condition is evaluated based on the intantaneous channel state informations. Simulation results show that the proposed relay selection algorithm achieve the increased throughput and diversity order when the number of potential relays is increased.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.39-47
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• 2012

As a scheme to efficiently reduce the effects of multipath fading in next generation wireless communication systems, cooperative communication systems have recently come into the spotlight. Since these cooperative communication systems use cooperative relays with diverse fading coefficients to transmit information, having all relays participate in cooperative communication may result in unnecessary waste of resources, and thus relay selection schemes are required to efficiently use wireless resources. In this paper, we propose an efficient relay selection scheme through self-learning in cooperative wireless networks using Q-learning algorithm. In this scheme, we define states, actions and two rewards to achieve good SER (Symbol Error Rate) performance, while selecting a small number of cooperative relays. When these parameters are well-defined, we can obtain good performance. For demonstrating the superiority of the proposed Q-learning, We compared the proposed scheme with Q-learning and a relay selection scheme with a mathematical analysis. The simulation results show that, compared to a scheme that obtains optimum relays through a mathematical analysis, the proposed scheme uses resources efficiently by using smaller numbers of relays with comparable SER performance. According to these simulation results, the proposed scheme can be considered as a good attempt for future wireless communication.