Throughput optimization in a cooperative double-threshold sensing scheme

Abstract

Cognitive radio (CR), as the novel approach to improve the utilization of the available radio spectrum is introduced under the constraint that the current authorized users are sufficiently protected against any harmful interferences. However, there are many challenges associated with detection of the primary users (PUs) which need to be addressed carefully. One of the most important challenges in CR networks is how to sense the existence of a PU transmission. The secondary users (SUs) are required to sense the channels, and once the PUs are found, they are required to vacate the channel in a specific amount of time. In a single threshold energy detection scheme, the higher the probability of detection, the better the PUs are protected, however; it gives higher probability of false alarm which means less chances the channel can be reused when it is available. A double threshold detection scheme ensures the target probability of detection while keeping the probability of false alarm as low as required at the cost of increasing the sensing time. This paper is concerned with analysis of the designing the sensing duration and two thresholds difference value in a cooperative double threshold sensing scheme that maximizes the throughput of the SUs, subject to adequate protection to the PUs. Through this work, we formulate the sensing-throughput tradeoff problem mathematically, and prove that the formulated problem is indeed a unimodal function of both parameters and there is an optimal set of two sensing parameters which yields the highest throughput for the secondary network.