Sensing based interference and data queue back-pressure approach for cognitive radio

The Lyapunov drift based back-pressure framework is applied to the cognitive radio context. A group of spatially distributed sensing units are utilized to monitor re-used spectrum. The sensing results for secondary user received power are utilized in virtual interference queues that, when stabilized, enforce spatially point-wise received power constraints, given in terms of a maximum allowed rate for exceeding an absolute received power level. A system stabilizing algorithm consisting of packet admission and transmit power control is applied to the problem. Numerical evaluations are utilized to characterize the system behavior in terms of fulfilling interference constraints, required transmitted energy per bit and queuing delay, when either a received power or an interference outage type virtual queue, and either water-filling type or binary ON-OFF power allocation is utilized.