Performance Enhancement of Cooperative NOMA in Satellite Communication Through Combining Techniques

Abstract

This article studies the analysis of the key performance parameters in the proposed cooperative Non-Orthogonal Multiple Access (NOMA) system considering the satellite network. NOMA can be coupled with standard relaying procedures to increase the overall capabilities of the wireless communication system. The system under consideration consists of two users, one near and a far user, and a satellite. The paper explores by using a Decode and Forward (DF) relaying mechanism at the user closer to the satellite, which will forward the signal received from the satellite user that is distant from it. In separate case studies, the far user combines the direct and indirect transmission signals using Maximal Ratio Combining (MRC) and Selection Combining (SC) techniques. The expressions for outage, average Bit Error Rate (BER), and capacity are derived for MRC and SC methods. It is also derived and approximated, and closed-form expressions are obtained. The simulation results of these analytical expressions reveal that the MRC method of combining outperforms the SC technique in terms of outage, BER, and ergodic capacity.