SGMA: Semi-granted multiple access for non-orthogonal multiple access (NOMA) in 5G networking

Abstract

With the rapid prosperity of mobile Internet, proliferating smart terminals, and deep penetration of Internet of things (IoTs), the fourth generation mobile communication system (4G) has become increasingly unable to meet the human needs. Therefore, the fifth generation mobile communication system (5G), being studied world-widely, needs to directly face to ultra-huge network capacity and the massive wireless connectivity. Non-orthogonal multiple access (NOMA), enabling different user equipments (UEs) sharing overlapping wireless resources, is regarded as one of the most promising key technologies of 5G, and has attracted great attention in both industry and academia in recent years. In order to guarantee the quality of service (QoS) and achieve low access latency and signaling overhead, NOMA needs to support two kinds of access methods: scheduling access and random access, named granted access and grant-free access respectively. However, how to efficiently support both granted and grant-free access simultaneously becomes a tricky challenge. In this article, we propose semi-granted multiple access, named SGMA. Other than strictly separating the wireless resources between granted and grant-free access, SGMA allows both of them to share the same resources. SGMA is a general method that can be used in several potential NOMA solutions. We also model SGMA and analyze the performance. Moreover, a heuristic resource allocation algorithm for SGMA is proposed. The simulation results show that SGMA further improves the network capacity and user connectivity of NOMA in 5G networking, and also adapts to the dynamic time-varying services. To the best of our knowledge, this is the first work to propose a multiple access method to allow the granted and grant-free access sharing the same wireless spectrum and further design the resource allocation algorithm in 5G NOMA system.