Non-Orthogonal Multiple Access

Abstract

At present, the spectrum available in wireless communication systems is limited. To meet the high demands in fifth-generation (5G) wireless communication systems, Non-orthogonal multiple access (NOMA) has been introduced. Over the years, several aspects of theNOMAhave been actively investigated. TheNOMA’s primary goal is to support more users than the number of orthogonal resource slots. This can be achieved with the help of non-orthogonal resource allocation. In the NOMA, multiplexing is achieved either in the power domain or code domain. And, to detect individual users’ symbols, a sophisticated inter-user interference cancellation technique is employed at the receiver. In this thesis, from the perspective of information theory, we present theNOMA with a successive interference cancellation (SIC) the receiver provides a better tradeoff between user fairness and efficiency than the orthogonal multiple access (OMA) techniques. We also provide a comprehensive study on the dominant NOMA solutions, starting with the older approaches to the most recent development in the fields of the NOMA. Specifically, the NOMA’s two prominent schemes, namely power domain NOMA (PD-NOMA) and code domain NOMA (CD-NOMA) and their applications, are discussed. A comparison between the achievable data rates in downlink and uplink of the NOMA and the OMA is presented. A systematic comparison of several multiuser detection (MUD) receivers is presented. We discuss the sparse code multiple access technique, which is a prominent technology in the NOMA. This thesis’s significant contribution is that a novel message-passing algorithm for the sparse NOMA systems is proposed. The performance of this algorithm is compared with the sparse code multiple access decoder. The bit error rate is compared while varying the signal-to-noise ratio and for different overloading factors.