Cooperative spectrum sharing with space time block coding and non-orthogonal multiple access

Abstract

In this paper, we have proposed a novel two-phase cooperative spectrum sharing protocol on the basis of Alamouti space time block coded (STBC) non-orthogonal multiple access. The network scenario comprising of a primary transmitter-receiver pair and a secondary transmitter-receiver pair. During the first two time slots, the primary transmitter transmits two STBC primary symbols to the cooperative secondary transmitter. The secondary transmitter acting as a decode-and-forward relay for the primary system is allowed to transmit its own secondary signal superposed on the STBC coded primary signal in exchange of cooperation during the next two time slots. Simulation and theoretical results demonstrate the efficacy of the proposed protocol compared to the conventional super positing coding based overlay scheme in terms of the outage probability and the ergodic capacity.