Improvement in the performance of mobile/hidden secondary users in multi-user CRN

In a multi-user cognitive radio network (CRN), mobile or hidden secondary users (SUs) are present. Conventionally, such SUs utilize rigid threshold value (lambda) for spectrum sensing (SS). When these SUs perform SS, they receive poor quality signals from primary users. This provokes erratic SS decisions, reduces the involvement of SUs in SS, diminishes the probability of detection (P-d) and raises miss detection (P-m) or false alarm of SUs. As a consequence of this, SUs are not able to participate in SS and allocation in emergency circumstances. To alleviate these problems, an adaptive lambda can be utilized for mobile/hidden SUs during SS. Thus, a two-level lambda optimization technique for SS has been proposed using a coalition formation approach to maintain co-operation among SUs. The proposed technique has been validated on Universal Software Radio Peripheral test-bed. Estimation of the probability of error (P-e), P-d, and P-m for mobile/hidden SUs with energy detection SS (EDSS) performed using a fixed lambda and the two-level optimized lambda. From these estimations, it has been observed that compared to the fixed lambda EDSS, P-e and P-m is reduced remarkably, and P-d is enhanced for mobile/hidden SUs using the two-level optimized lambda EDSS.