Revealing the Benefits of Rate-Splitting Multiple Access for Uplink IoT Traffic

To address the challenges faced by non-orthogonal multiple access (NOMA) for multiple access in beyond fifth generation (B5G) networks, rate-splitting multiple access (RSMA) has newly emerged as a promising approach. In addition to achieving high data rates, RSMA may be used for massive machine-type communication (mMTC)/massive Internet of things (mIoT) applications as well. Although RSMA addresses the user coupling and scheduling overhead problems met by NOMA, it is not clear whether and how RSMA can be applied to uplink mMTC/mIoT traffic. In this study, we explore the applicability of RSMA for uplink traffic and investigate whether there is any benefit to employ RSMA and if yes how this benefit can be achieved. To this end, we propose a novel uplink RSMA scheme with two constituent components, known as inter-device decoding and intra-device decoding, respectively. Through user pairing for inter-device decoding and power allocation for intra-device decoding, we reveal under which circumstances RSMA can bring benefits for uplink traffic.