Analysis of Cooperative Relay-Based Energy Detection of Unknown Deterministic Signals in Cognitive Radio Networks

In this article, we develop an analytical framework for the performance analysis of cooperative amplify-and-forward (CAF) relay-based energy detection. We derive mathematical expression for the detection probability for single cognitive relay system and later extend it to multi-relay system. Our resulting expression is based on the canonical series representation of generalized Marcum Q-function of real order in conjunction with the derivatives of moment generating function (MGF) of signal-to-noise ratio of fading channels. First, we considered single relay based sensing and compared to direct sensing. We found out that the direct sensing performs better than the single relay sensing as expected. Then, combining both direct sensing and relay-based sensing using either of maximum ratio combining (MRC) and square-law combining (SLC) to form a CAF relaybased sensing system greatly enhance the performance. Also, the performance of multi-relay diversity system is analysed; and as expected, increase in relay diversity improves the sensing performance. In all diversity combining cases, we found out that CAF relay sensing based on MRC outperforms the ones based on SLC. Keywords— Energy detection, Cognitive radio, Fading channels, Maximum ratio combining, Square-law combining, Cooperative amplify-and-forward.