Spatial time index non‐orthogonal multiple access for beyond 5G wireless networks

Abstract

AbstractMultiple input multiple output (MIMO) based non‐orthogonal multiple access (NOMA) has been an evolving technique for 5G and beyond 5G wireless networks in the last decade. The goal of the proposed technique is to achieve improved spectral efficiency, with reduced complexity in the transceiver design. A novel time‐based spatial modulation‐MIMO based NOMA (SM‐MIMO‐NOMA) known as space time index‐based NOMA (STIN) has been proposed, which brings down the number of RF chains used at the transmitter end and improves the spectral efficiency in terms of bits per channel use. In the STIN algorithm, Joint GPS enabled channel estimation and threshold rate‐based power allocation are performed for user clustering and enhancing capacity. The transmit information bits are conveyed by the active antenna index as well as amplitude phase modulation by incorporating the block user‐symbol ratio at the base station. On the receiver side, user‐timeslot‐based successive interference cancellation with a maximum likelihood detector is implemented in the user equipment. STIN improves the bits per channel use with increasing modulation order and number of users by 33%. This novel algorithm has shown better performance in comparison with the existing NOMA‐based spatial modulation techniques in terms of average bit error rate, spectral efficiency, and complexity.