FPGA implementation of optimum distributed sensing for cognitive radio network

Spectrum sensing is an essential component in the cognitive radio (CR) systems for opportunistic usage of unutilized radio spectrum. In this paper, spectrum sensing is performed using energy measurement in a particular frequency band. This approach is extended for distributed/cooperative sensing using different hard decision fusion rules to mitigate the fading and shadowing effects in the medium. The sensing period and number of CR users required in cooperation are critical parameters in spectrum sensing. In this work, optimal sensing period is computed to maximize the achievable throughput for the Cognitive/Secondary user network with constraint that the licensed users are sufficiently protected. Moreover, the optimum number of nodes required for distributed sensing is computed based on total error rate. The sensing algorithm is also implemented with optimum number of nodes in Xilinx Virtex-4 Field Programmable Gate Array (FPGA) using MOST fusion logic.