Orthogonal Matching Pursuit (OMP) based Active User Detection on Grant-Free NOMA Communication with Shared Subcarrier Variation

Non-orthogonal Multiple Access (NOMA) system is capable to serve a large number of user, but it may cause high signaling overhead and latency. The signaling overhead can be reduced by using grant-free scheme. In a grant-free NOMA, a user can communicate to a Base Station (BS) without scheduling process. Active user detection in grant-free NOMA can be considered as signal reconstruction in Compressive Sensing (CS). Here, we implement Orthogonal Matching Pursuit (OMP) as active user detection method in the grant-free NOMA. The OMP is employed to detect active users from all of the users. An active user communicates to a BS using some shared subcarriers or each subcarrier. We compare the OMP performance to the MP’s assuming that the signal suffered from Additive White Gaussian Noise (AWGN). We find that the performance of the OMP is better than the MP when there are shared subcarriers, in terms of Bit Error Rate (BER) and Signal to Noise Ratio (SNR). We also find that in general, the OMP performance with more shared subcarriers is better than the OMP performance with less shared subcarriers.