A New Energy Efficiency/Spectrum Efficiency Model for Cooperative Cognitive Radio Network

In this paper we study the resources access problem in cognitive radio networks, especially we are interested in the large number of secondary users (SUs). We establish a model based on channel access process when the PU (Primary User) is active, respecting the level of interference authorized by the operator. We study a system of cooperation between the SUs and the PUs to increase the performance of the system. SUs pass through an negotiation phase with the PUs for the acquisition of the underutilized channels with exceeded interference caused to the PU. The PU will support additional interference Δ but will benefit from the cooperation of SUs to relay its data. We model this cooperation as coalitional game.The utility function depends on two main parameters which are: transmission power and noise level. A distributed coalition formation algorithm is also proposed, which can be used by SUs to decide whether to join or leave a coalition. Such a decision is based on whether it can increase the maximal coalition utility value. We consider also the trade off between energy efficiency and the target throughput in the proposed cooperative relay network. The objective of this work is to validate the expected enhancement of the overall throughput of the network and also the energy efficiency while increasing the opportunity for SUs to access the licensed spectrum owned by PUs.