Queue performance measures for cognitive radios in spectrum sharing systems

This paper investigates the queuing system of a cognitive user who is trying to communicate, using spectrum sharing methods, over a channel reserved to a licensed user. For the cognitive user to use the channel, its transmission power should satisfy the outage probability requirement of the primary user. In this environment, the cognitive user is found to have an M/G/1 queue model, where the queue service rate is equal to the cognitive channel capacity. Some queue performance measures are investigated. These include the first two moments of the service time process, mean waiting and transit times, mean number of waiting and transit packets, mean duration of server busy period, and mean number of packets served during a busy period. We also investigate the effects of changing some of the communication environment parameters on the queue behavior.