Buffer-Aided AF Cooperative Relaying Network with NOMA Transmission Scheme

A buffer-aided cooperative communication network employing non-orthogonal multiple access (NOMA) with fixed gain amplify-and-forward relaying is considered in this paper. Using NOMA scheme the mobile user which acts as a relay and is a strong user transmits the information to the two destination devices which are the weak users. The strong user is aided with a data buffer and it amplifies and forwards the superposed signal received from the source. The buffer at the relay has the potential to offer flexible scheduling of data reception and transmission by utilizing the channel resources and also helps in offloading the data servers. The approximate upper bound expressions for the successful transmission probabilities at the two weak users are derived considering that the device acting as a relay (strong user) has global channel state information. By adopting a Markov chain approach to model the evolution of the strong user's buffer status, the closed-form expression for the outage probability and the average packet delay of the system are also derived. Numerical results corroborate the derived analytical results.