A Novel Cs-Based Non-Orthogonal Multiple Access Mimo System For Downlink Of Mtc In 5g

The main challenges for machine type communication (MTC) are not only supporting the random access of massive users, but also increasing the spectral efficiency in future 5G system. To address these challenges, we propose a novel compressed sensing (CS) based non-orthogonal multiple access (NOMA) multiple input multiple output (MIMO) scheme, called CS-NOMA MIMO scheme, for the downlink of MTC. In the proposed scheme, a version of low mutual coherence spreading signatures, named CS signatures, is introduced to enable system overloading. Furthermore, a novel CS-based tensor frame structure is proposed, in which symbols are spread over multiple CS signatures. In order to allow CS based multiuser detection (CS-MUD) to be deployed in the user receivers, we provide the theoretical analysis of restricted isometry property (RIP) for the effective channel matrix which guarantee the sparse signal recovery. Simulation results using two CS algorithms show that the proposed scheme achieves a relatively high system overload (up to 3) when the active users are relatively sparse with an activity ratio of 1%.