Grant-Free NOMA over Universal Filtered Multicarrier

In this paper, the grant-free non-orthogonal multiple access over universal filtered multicarrier (GF-UFMC) is studied. Note that the even-component of frequency domain (FD) received signal suffers from neither inter-sub-band interference nor inter-sub carrier interference while the odd-component suffers from both. A two-stage joint active user detection (AUD) and channel estimation (CE) is proposed. In the first stage, the cross-validation aided block sparsity adaptive subspace pursuit is employed to perform the AUD and CE by utilizing only the even-component. In the second stage, the unreliable estimates by the first-stage are further refined by utilizing additional odd-component. Specifically, a proper reliability metric defined as the second order variation rate of cross validation error is presented. Finally, simulation results are given to demonstrate the performance of the proposed method.