Abstract
This work investigates the user pairing issue of indoor and outdoor users for a cellular downlink NOMA system, where a less complex algorithm called least and most cost method (LMCM) is proposed to maximize the achievable data rate and obtain high fairness. Furthermore, the proposed algorithm mainly depends on the diversity of the channel gains of indoor and outdoor users, where the most and least cost matrix techniques are applied. Moreover, we discuss the channel path loss for the case of indoor and outdoor users by proposing to apply particular and empirical propagation models. In addition to that, different performance metrics such as achievable data rate and fairness index are analysed to measure the efficiency of the proposed algorithm. The simulation results show that the proposed algorithm outperforms a random user pairing in terms of different performance metrics.