BER analysis of full duplex NOMA downlink and uplink co-operative user relaying systems over Nakagami-m fading environment

Abstract

A Co-operative user Relaying Full Duplex Non Orthogonal Multiple Access (CR-FD-NOMA) system is considered, when there is no direct link between base station and the far user. Deriving analytical expressions for probability of error of systems with NOMA technique is a challenging task. In this paper, the Bit Error Rate (BER) performance of pre-paired CR-FD-NOMA users in downlink and uplink scenarios over Nakagami-m fading distribution is investigated. Quadrature Phase Shift Keying and Binary Phase Shift Keying modulations are used for near user and far user information respectively. By exploiting self interference and using the properties of Gaussian Q-functions at high signal to noise ratio regime, an approximated closed form BER expressions of both the users in downlink and uplink systems are derived. The performance of the proposed downlink and uplink CR-FD NOMA systems are compared with the conventional NOMA systems with the existence of direct path for both the users from BS. It is observed that the uplink performance of the CR-FD-NOMA systems outperforms the conventional NOMA systems.