Multiuser Detector based on Fused Amended Orthogonal Matching Pursuit and Subspace Pursuit Algorithms for Uplink Grant-Free NOMA Wireless Communication Systems

This paper focuses on multiuser detection scheme for both user data and user activities in uplink Non Orthogonal Multiple Access (NOMA) networks with grant-free transmission mode. In this paper a new fused compressive sensing algorithms-based multiuser detection (MUD) scheme is proposed. The scheme is based on the union of amended versions of two traditional compressive sensing algorithms, the subspace pursuit (SP) and the orthogonal matching pursuit (OMP) algorithms. The proposed MUD is named the Amended OMP-union-Amended SP (AmdOMP-union-AmdSP)-based MUD. The AmdOMP-union-AmdSP-based MUD recovers transmitted signal within a continuous time slots. During this period it is assumed that there are variations in user activities. The results obtained from the computer simulation carried out indicate that the proposed AmdOMP-union-AmdSP-based MUD exhibits improved performance when compared with its constituent MUDs and other MUDs considered in this paper. However, the computational complexity cost of the proposed MUD is quite expensive, and is more than double the respective computational complexity cost of its constituent MUDs, the Amended OMP-based MUD and the Amended SP-based MUD.