K-best sphere detector based receiver for mimo non-orthogonal multiple access systems

Abstract

Non-Orthogonal Multiple Access (NOMA) is a promising radio access technology, which improves the spectrum efficiency and system throughput considerably over conventional Orthogonal Multiple Access (OMA) techniques and also enables massive connectivity. NOMA is currently being considered extensively as a key enabling technology for 5G wireless networks. However, in NOMA, one of the key technical challenges is to develop efficient receivers due to the presence of Multiple-Access Interference (MAI) caused by non-orthogonal resource allocation. Minimum Mean Square Error (MMSE) based Successive Interference Cancellation (SIC) receivers have widely been discussed in the literature for power-domain NOMA systems. However MMSE detector is a linear detector with poor error performance. In this research, a K-Best sphere detector based SIC receiver is discussed for the downlink of power-domain MIMO-NOMA systems. The BER performance of the proposed receiver is investigated for different power allocation ratios and for different K values of the K-Best detector. Link level simulation results demonstrate that our proposed K-Best detector based receiver offers much superior performance over the MMSE-SIC based receiver.