Interference Effects of Non-Ideal Dynamic Spectrum Access on Primary and Secondary User Capacities

Dynamic spectrum access (DSA) technology can improve the spectrum utilization significantly and is the key solution to the spectrum scarcity problem. In a typical DSA scenario, the secondary user (SU) is required to co-exist with the primary user (PU) in a non-interfering manner. However, the SU's spectrum sensing limitations can result in erroneous secondary transmissions that can affect the PU's capacity. In this paper, we model the interference caused by the SU to the PU and simulate the resulting capacity loss experienced by the PU. The trends in the PU and SU capacities that occur with variation in the system parameters such as transmit SNR, PU - SU spatial separation and the spectrum sensing time have been discussed. The results presented in this paper show that the capacity loss of the PU as well as the SU due to DSA interference is insignificant when limits are placed on the SU system parameters. Furthermore, the maximum effective throughput that can be achieved by the SU under such limited operation is also computed.