Performance analyses of TAS/Alamouti‐MRC NOMA in dual‐hop full‐duplex AF relaying networks

Abstract

Abstract In this article, performance of a multi‐user downlink non‐orthogonal multiple access system in dual‐hop full‐duplex amplify‐and‐forward relaying networks is investigated over Nakagami‐ fading channels in the presence of channel estimation error and feedback delay. The base station applies transmit antenna selection (TAS)/Alamouti space‐time block coding scheme, while the users exploit maximum‐ratio combining to utilize benefits of receive diversity. To demonstrate superiority of the proposed system, outage probability (OP) is investigated, and tight lower bound expression is derived to support the exact OP. Moreover, asymptotic analyzes are also conducted for ideal and practical conditions to provide further insights into the OP in high signal‐to‐noise ratio region. In addition, software defined radio based test‐bed implementation is realized to confirm the analysis and show feasibility of the proposed system. Theoretical analyzes verified by simulations and practical implementations demonstrate that more performance improvement can be achieved for the weakest user (with the lowest channel gain) in the case of practical conditions when compared to ideal cases. Also, both diversity order and array gain are dominant in achieving minimum OP (based on relay location) in ideal conditions, while only array gain has effect in practical manner.