Optimal power allocation for cognitive radio multicast networks under primary users' outage loss constraint

Abstract

In this paper, we consider an underlay cognitive radio (CR) multicast network where secondary users (SUs) coexist with primary users (PUs). The cognitive radio network (CRN) consists of a cognitive base station (CBS) and multiple multicast groups. Each multicast group comprises of a number of SUs and is served by the CBS using a common PU channel. Our objective is to minimize the aggregate group outage probability for the CR multicast network. To protect Pus' transmission, a probabilistic model of interference is considered unlike the traditional interference temperature constraint. In addition, an average transmit power constraint is imposed on CBS's transmission. The problem is formulated using constrained optimization framework and an optimal transmit power control policy is proposed. The power adaptation strategy clearly illustrates the dependence of CBS's transmission power on various system parameters including Pus' channel conditions and target rates, link interferences as well as multicast group target rates and SUs' channel conditions. Simulation results are presented to validate the proposed power allocation scheme.