Throughput Analysis of a Randomized Sensing Scheme in Cell-Based Ad-Hoc Cognitive Networks

Cognitive radios have a great potential to improve spectrum utilization by enabling secondary (unlicensed) users to opportunistically access the spectrum without disturbing the primary (licensed) users´ communication. However, to assure acceptable QoS for secondary users without interfering with primary users several challenges must be overcome under physical constraints. Because of hardware constraints, secondary users can only sense a limited number of spectrum channels. Therefore a secondary user must wisely select the channels to be sensed to increase it´s likelihood for successful data transmission. However if a secondary user takes up a greedy approach and disregards other secondary users in its channel selection, the whole secondary network would suffer in terms of aggregate throughput. Also because of the autonomous nature of secondary users, the search policy must be as decentralized as possible, i.e. secondary users should need almost no information of one another to operate. In this work we propose a search policy for secondary users in a cell based ad-hoc network and evaluate its performance (total primary and secondary throughput) as a function of different system parameters.