Summary
Cooperative communication is a significant technology for fifth generation (5G) and beyond wireless communication to improve the quality of service (QoS) in massive networks. In addition, it serves as a promising candidate along with non‐orthogonal multiple access (NOMA) scheme to increase the spectral efficiency. Conventionally, cooperative‐NOMA (C‐NOMA) systems are analysed by assuming perfect successive interference cancellation (SIC) and imperfect SIC (I‐SIC) over Rayleigh, Rican,
α−μ, Hoyt fading channels, and so on. In this paper, near–far relay (NFR) C‐NOMA system is analysed aiding perfect SIC, perfect channel state information (CSI), imperfect (I‐CSI) and (I‐SIC) over Rayleigh fading channel. Initially, we derive analytical expressions of outage probability (OP) by considering I‐SIC and I‐CSI for NFR‐C‐NOMA system. The accuracy of analytical results is verified through Monte Carlo (MC) simulations. Interpretation of the results conveys that I‐CSI and I‐SIC have a substantial impact on OP in NFR‐C‐NOMA scheme and existing schemes. Later, we examined impact on OP in NFR‐C‐NOMA by varying relay position, target rate of users and jointly considering the I‐SIC, I‐CSI. Further, it is also observed that the NFR‐C‐NOMA scheme shows better outage performance than state‐of‐the‐art schemes.
Cooperative communication is a key factor in 5G and beyond standards for increasing the quality of service and aids for dense networks. It works in conjugate with non-orthogonal multiple access (NOMA) to increase the connectivity and spectral efficiency. In this paper, a novel minimum variance maximum mean relay selection scheme with fixed power allocation (MVMM-FPA) is proposed for two-stage cooperative NOMA (C-NOMA) networks using decode-and-forward protocol. The outage probability analytical expressions are derived for the MVMM-FPA over Rayleigh fading channel and its performance is observed with the conventional relay selection (RS) schemes. The impact of outage performance on target rate for users and number of relays have been analyzed for the proposed scheme. Monte Carlo simulations are used to corroborate the analytical expressions of outage probability. Simulation results reveal that the MVMM-FPA RS scheme for C-NOMA offers a minimal outage probability than existing max-min RS and orthogonal multiple access schemes without sacrificing the spectral efficiency.
IntroductionThe goals of 5G and beyond wireless communications are high spectral efficacy, high data rates, low latency and seamless connectivity. One of the trustworthy entrant for 5G is non-orthogonal multiple access (NOMA), when compared to alternative technologies like time division multiple access (TDMA), frequency division multiple access (FDMA) and orthogonal frequency division multiple (OFDM) access schemes [1][2][3][4][5][6][7]. NOMA permits multiple users to transmit data simultaneously at same frequency band using power domain, [8][9][10]. NOMA with cooperative communication will further improve the quality of the service (QoS). The state of art cooperative NOMA (C-NOMA) techniques are discussed below.
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