Majority based antenna selection schemes in downlink NOMA network with channel estimation errors and feedback delay

Abstract

This paper develops new suboptimal antenna selection (AS) schemes, majority based transmit antenna selection/maximal ratio combining (TAS-maj/MRC) and joint transmit and receive antenna selection (JTRAS-maj), in a multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) network. The impact of the channel estimation errors (CEEs) and feedback delay (FD) on the performance of the network is studied in Nakagami-m fading channels. First, the outage behavior of the network is investigated in a unified manner for the proposed AS schemes by deriving the closed-form expression of the exact outage probability (OP). Next, in the presence of the CEEs and FD, the corresponding upper bound of the OP is obtained. The OP expression in high signal-to-noise ratio region is then provided to illustrate an error floor value in the presence of the CEEs and FD as well as diversity and array gains in the absence of the CEEs and FD. Finally, the analytical results in the presence and absence of the CEEs and FD are verified by the Monte Carlo simulations. The numerical results show that the proposed majority based AS schemes are superior to both max-max-max and max-min-max based AS schemes and the system performance is more sensitive to the CEE than FD.