Cooperative Multi-User NOMA with Selection Combining

In 5G and beyond 5G cellular networks, higher spectral efficiency is achieved through Non-Orthogonal Multiple Access (NOMA) for dense users. Users who are located near, center, and edge of the cellular region suffer from poor signal reception due to the shadowing and rich scattering environment. A downlink mobile network consisting of a base station, a regenerative relay, and multiple users in a Nakagami fading environment is considered in this work. The users receive multiple signals from the base station and relay are combined through selection combining. In this work, the outage probability and ergodic capacity of the users are derived, and the results are validated through simulations. From the numerical results, it is inferred that the users in the cell edge region get the reduced outage because of the cooperation, and the overall system capacity increases for a cooperative system than a noncooperative system.