An LTE Matching-Based Scheduling Scheme for Critical-MTC with Shortened Transmission Time Intervals

Shortened transmission time interval (sTTI) is considered one of the most significant enhancements to evolve the current Long-Term Evolution (LTE) networks to fulfill the 5G requirement of supporting critical machine-type communications (cMTC). However, scheduling the sporadic cMTC and the data-intensive human-type communications (HTC) on different scales of transmission duration is a challenging task. In addition, the finite blocklength coding of the small-size packets of cMTC makes the process more challenging. In this paper, we address the scheduling problem of cMTC coexistent with HTC in LTE. In this regard, we formulate the processes as optimization problems that maximize the system utility while providing guarantees for the different quality-of-service (QoS) of both types of traffic. Moreover, we propose computationally-efficient algorithms that utilize the matching theory and analyze them from a practical perspective to prove that they can be used as practical schemes. The simulation results show a close-to-optimal performance for the proposed scheme and its superiority to conventional algorithms.

I. Introduction

Critical machine-type communications (cMTC), or ultrareliable low-latency communications (URLLC), have been considered as a major use case in the fifth generation (5G) mobile communications [1]. As a candidate 5G technology, the Third Generation Partnership Project (3GPP) is working on evolving the LTE standard to fulfill the requirements of the International Mobile Telecommunications (IMT)-2020 [2]. In this regard, several studies in 3GPP’s Releases 14 and 15 have been conducted to enable cMTC in LTE networks [3]. The proposed enhancements include shortened transmission time intervals (sTTIs) [4], fast uplink access on MAC [5], and support of reduced processing times [4].