QoS aware resource allocation for coexistence mechanisms between eMBB and URLLC: Issues, challenges, and future directions in 5G

Abstract

5G NR enables three types of use case scenarios viz. enhance mobile broadband (eMBB), ultra-reliable low latency communication (URLLC), and massive machine type communication (mMTC). The eMBB is suitable for applications that demand higher throughput. Whereas URLLC is suitable for mission-critical applications with stringent requirement of low latency and reliability. The mMTC on the other hand is suitable for machine-to-machine (M2M) communications and massive IoT infrastructures. To meet all these requirements, 5G NR combines eMBB with URLLC services under a unified 5G air interface framework. Most of the coexistence mechanisms between eMBB and URLLC were presented by the researchers with a goal to enhance eMBB throughput with stringent latency and reliability requirements of URLLC services. Formulation of optimal resource scheduling and allocation were found to be the key problems of eMBB and URLLC traffic. This paper investigated the 5G state-of-the-art focused on coexistence mechanisms between eMBB and URLLC traffic for resource scheduling. We followed the PRISMA statement and classified the works to five major classes viz. multiplexing-, QoS-, Machine learning-, Network slicing-, and C-RAN architecture-based approaches. Each work was carefully examined against their methodology and performance metrics. In addition, several key issues, challenges, and future directions were also highlighted to provide detailed insights for researchers working in the field of 5G.