Reliable compressive sensing (CS)-based multi-user detection with power-based Zadoff-Chu sequence design

Internet-of-Things (IoT) applications grew rapidly in recent years. Deployment of massive machine-type communication (mMTC) with scalability and reliability becomes a challenging issue. The feature of activity sparsity in mMTC devices makes room for us to efficiently handle detection by compressive sensing (CS)-based multi-user detection (CS-MUD). However, the limited resource, such as the design of spreading sequences for massive devices, makes CS-MUD in mMTC congested and collided. Thus, non-orthogonal multiple access (NOMA) attracts attention in mMTC. Despite NOMA can accommodate more devices, the non-orthogonality makes the performance degradation. In this paper, we take advantage of NOMA to generate more set of sequences by Zadoff-Chu (ZC) sequence which the bit-error-rate (BER) is reduced by two orders. Meanwhile, by considering the channel characteristic and received power of devices, these devices are grouped to make a more reliable mMTC system which eliminates the effect of non-orthogonality and improves the BER by 1.7 times with 128 devices. Thus, the proposed ZC sequence design with power-based grouping scheme can greatly improve the device scalability and reliability of the detection process for uplink multi-user problems that provides a potential solution in mMTC scenarios.