An Improved CoSaMP Multiuser Detection for Uplink Grant Free NOMA System

Abstract

Non-Orthogonal Multiple Access (NOMA) is the most prominent technology that enhances massive connectivity and spectral efficiency in 5G cellular communication. It provides services to the multi-users in time, frequency, and code domain with significant power level. Message Passing Algorithm (MPA) detection in a multiuser uplink grant-free system requires user activity information at the receiver that makes it impractical. To circumvent this problem, (MPA) is combined with Compressed Sensing (CS) based detection which not only detects the user activity but also the signal data. However, the Compressive Sampling Matching pursuit (CoSaMP) algorithm uses Zero Forcing (ZF) detector to estimate the signal but its performance degrades with increment in Signal to Noise Ratio (SNR). Therefore, Minimum Mean Square Error (MMSE) detector in CoSaMP algorithm is deployed in this paper that enhances detection accuracy and BER performance. The simulation results validate that the proposed algorithm attains better performance than MPA and conventional CoSaMP algorithm in high SNR.

Grant-Free Transmission by LDPC Matrix Mapping and Integrated Cover-MPA Detector

“…Since the factor graph used in MPA is the same as that in Section III.D, check node c and variable node v involved in (16)(17) will have the same range as that mentioned in Section III.D, i.e. we have c ∈ {l|I[l] = 1} and v ∈ Ûa ac ( Î).…”