EXIT Chart Analysis of Cooperative Non-Orthogonal Multiple Access for Next Generation Wireless Communication Systems

Non-orthogonal Multiple Access (NOMA) has garnered considerable attention as a prime candidate for the next generation of wireless communication systems due to its improvement of spectral efficiency. The proposed model exploits one of NOMA's key features, namely of users having to decode other users messages before decoding their own as part of Successive Interference Cancellation (SIC). The purpose of the proposed model is to utilize such prior knowledge to allow users to cooperate with other users through their relaying of information, thereby increasing the overall diversity gain and, by extension, each user's data rate. The main focus of this paper is to asses the proposed model for a multi-user case. The performance comparison between the Bit Error Rate (BER) versus Signal to Noise Ratio (SNR) is evaluated along with the data rate experienced at each user with independent Rayleigh fading. User fairness is also analysed through the implementation of Extrinsic Information Transfer (EXIT) charts. Furthermore, expressions for the data rates at each user are derived independently and used to supplement the experimental data.