Open membership coalition formation of cognitive interference systems

We consider a cognitive radio setting in which a set of secondary transmitter-receiver pairs coexist with a primary user. In the channel sensing phase, each secondary system senses the primary user´s channel to determine its occupancy. The existence of a fusion center enables joint processing of the sensing data. This would improve the joint sensing performance, however at the cost of a delay required for reporting the sensed data. In the channel access phase, noncooperative secondary transmission can lead to a degradation of secondary users´ average achievable rates due to excessive mutual interference. We propose to coordinate the secondary system transmission by providing orthogonal multiple access rules for the secondary users which report their sensing data to the fusion center. Using models from game theory, a coalition formation algorithm is proposed to find a stable set of secondary users participating in sensing data fusion. It is shown by simulation that the proposed mechanism provides an incentive for the secondary users to participate in joint sensing at an extent depending on the signal-to-noise ratio and the reporting overhead.