Performance Analysis of Non-Orthogonal Beam Division Multiple Access for Full Duplex based Massive-MIMO Systems

Abstract

For the Full Duplex (FD) scheme based large-scale multi-input Multi-Output (MIMO) systems, a multi-user MIMO (MU-MIMO) non-orthogonal multiple access (NOMA) scheme, known as the beam division NOMA (BD-NOMA) is addressed for massive MIMO systems. Traditional MIMO in the spatial domain is analyzed using lens antenna array to form Beam Division Multiple Access scheme which has orthogonal resource allocation lacking optimization. The Power Domain-Non Orthogonal Multiple Access (PD-NOMA) provides different power allocation for near and far users by exploiting supper position coding at the base station followed by Successive Interference Cancellation (SIC) at mobile stations. To get technical advantage for resource optimization, BD-NOMA is formed by combining BDMA with PD-NOMA. Millimeter wave communication is a promising technology for future wireless systems. One of the practical difficulty is to achieve its large-antenna gains with only limited number of radio frequency (RF) chains. To this end, a new lens antenna array enabled mm-wave MIMO is addressed. Using lens antenna array, a conventional spatial channel is transformed in to beam space channel in order to capture the channel sparsity at mm-wave frequencies. Accordingly, the dominant beams are selected from the sparse beam space channel to reduce the number of required RF chains by using interference-aware beam selection. A precoding scheme based on the principle of wiener filter (WF) is designed to reduce Inter-Beam Interference (IBI) in the downlink. Additionally, to maximize the achievable sum rate, a dynamic (iterative) power allocation is proposed by solving the joint power optimization problem, that address not only intra-beam optimization, but also considers inter-beam optimization. In this paper, an FD base station is analyzed with the Half-Duplex (HD) users. At this FD base station, downlink antennas affects the performance of uplink antennas creating a Self-Interference (SI) because of that both transmission and reception is conducted at the same time and frequency at the FD base station. To mitigate the effect of SI in the uplink, the paper uses two SI channel estimators assuming that the interference follows both Rician and Rayleigh fading channels. The first one is the Minimum Mean Square Error (MMSE) estimator, while the second is the Least Square (LS) estimator. After these estimators, an uplink spectral efficiency of proposed BD-NOMA is analyzed. Simulation results showed that BD-NOMA scheme has around 10% spectral and energy efficiency increment over BD-OMA (BDMA). Traditional MIMO has higher spectral efficiency than BD-NOMA with a cost of enormous energy consumption. But it is proved that Traditional MIMO will have almost a zero energy efficiency as compared to proposed BD-NOMA.