Energy efficient cooperative communications using coalition formation games

It is well-known that a single node in a network cooperates with one another employing cooperative communications can lead to transmission power saving. However, due to the additional processing power in receiving and retransmitting other’s information, not all nodes and cooperative protocols can achieve energy efficiency. To ensure energy efficiency of a cooperative network, a novel merge process, consisting of transmission request stage, merge stage, and cooperative transmission stage, utilizing coalition formation games is proposed. The goal is to find a good cooperation structure, in which individual nodes in cooperative groups can achieve their own energy efficiency, thus resulting in energy efficiency of the cooperative network. The merge process is applied to a cooperative communication protocol, namely wireless network cocast (WNC), to demonstrate and validate its effectiveness. Simulations show that for the same network setting, the cooperative transmission networks can require 3.3 times less total power, accounting for both transmission and processing power, than the direct transmission networks to provide a comparable quality of service. The larger the network dimension is the larger the power saving for cooperative transmission over direct transmission. In addition, the cooperative networks achieve balanced power distribution, which helps improving the network lifetime. Comparing with an iterative merge-and-split process in coalition formation games, the simulations show that the iterative merge-and-split process should be only used in small-size networks while the proposed merge process has much more advantage in large-size networks.