Performance of a Sensor Network Aided Cognitive Radio system

A Sensor Network Aided Cognitive Radio Network uses the concept of a wireless sensor network that assists a cognitive radio network by providing information about the current primary spectrum occupancy. In this paper we study the performance of the cognitive network for various cell sizes and transmit power levels when deployed co-located with a mobile primary system that uses a cellular reuse pattern with seven frequencies. Co-location of secondary and primary base stations has been found to be very important in order to reduce network costs. An expression for the degree of co-location of secondary and primary base stations is derived and used for identifying optimal secondary cell sizes. For these optimal secondary cell sizes, we determine the performance in terms of throughput, packet loss, delay, coverage and connectivity when using spectrum holes in the space, time and frequency domains. Especially, we find that cell size and transmit power levels are crucial for secondary system performance, and that smaller cell sizes and less expensive base stations for the secondary system such as WiFi access points and femto-cells is beneficial.