Throughput comparison in cognitive radio networks

Primary user (PU) activities can significantly impact on the quality of service of secondary user (SU) sharing a common channel. Expressions of forced termination and blocking probabilities for the SU packets with a fixed length header and exponentially distributed payload length are derived. The optimal mean payload length which maximizes packet throughput is also investigated. Numerical results are given which compare exponentially distributed payload length with fixed size payload length. The results show that although exponentially distributed payload has both lower blocking and forced termination probability, this type of packet stream actually has lower throughput than the fixed size packet stream, given the same payload intensity. Simulation results are also included.