A Random Non-Orthogonal Multiple Access Scheme for mMTC

Massive Machine Type Communication (mMTC) is one key usage scenario in future 5G. To fulfill the massive connection requirement in mMTC, and reduce the signaling overhead, a novel grant free Random Non-Orthogonal Multiple Access (RNOMA) scheme is proposed in this paper, inspired by the concept of conventional NOMA. In RNOMA, one physical resource area is reserved and divided into orthogonal resource units (RU), where each user is allowed to persuade-randomly transmit the same packet on each RU according to optimized probability. At the receiver, inter-and intra-RU Successive Interference Cancelation (SIC) is applied for multi-user receiving. A frame structure is also designed to enable RNOMA, where signaling overhead on informing each UE with assigned resources is reduced. Simulation results show, the proposed method is robust and is able to achieve significantly better performance than novel random access method, i.e. irregular repetition slotted aloha, where its access degree distribution is optimized for binary erasure channel.