An Identical Code–Data Based Nonorthogonal Multiple Access

Abstract

ABSTRACTNonorthogonal multiple access (NOMA) is a promising technique operating with limited resources. NOMA can be executed in both power and code domains. Cyclic interleaved NOMA strategies are debated in recent literature, combining power and code domains. Identical code cyclic shift (ICCS) transmission is viewed to be a bridge between code division access and NOMA. We propose identical code–data cyclic shift NOMA (ICDCS‐NOMA) in which the code and data are cyclically shifted in distinction to simple cyclic interleaved transmission introduced in our earlier work and the ICCS transmission. The cell‐edge user in a NOMA pair engages its signal transmission using ICDCS; in contrast, the cell‐center user prefers simple cyclic interleaved transmission. The spread data stream and its cyclic shifted version are blended in ICDCS, followed by cyclic interleaving. A distinct and extreme fading channel pair is assumed with the same number of paths for the edge and center users. Diversity combining multipath signals is embraced at the edge user terminal, and frequency domain equalization (FDE)/matched filter (MF) receiver is employed at the center user. The simulation indicates the dominance of the proposed ICDCS‐NOMA transmission in terms of the attained diversity gain over the conventional, ICCS, and simple cyclic interleaved transmissions.