Grant-free (GF) access has been one of the enablers for the various use cases in 5th generation (5G) mobile system, especially for time-critical massive machine-type communication (mMTC). However, these use cases have diverse quality of service (QoS) requirements, which can be measured in terms of an access success rate from a GF random access perspective. Consequently, a GF scheme that enables supporting of diverse QoS is highly sought. This article proposes a GF access scheme in which high-QoS users superpose multiple preambles to improve their access success rate as a result of the diversity in access collision and multiple access interference seen by multiple preambles. We further show that in the presence of multiple antennas in the base station (BS), a low-complexity receiver can correctly detect active preambles with a significantly high probability, even under severe multiple access interference caused by non-orthogonal preamble transmission. A theoritical performance analysis is conducted by modeling the preamble reception as a multiple measurement vector-based compressive sensing problem. The preamble misdetection probability is shown to decrease exponentially as the number antennas at BS increases. Numerical results demonstrate multiple-order improvement in terms of the access success rate for critical-QoS users, even under severe noise and multiple access contamination.
Bibliographical noteFunding Information:
Manuscript received February 1, 2020; revised June 9, 2020; accepted July 21, 2020. Date of publication September 9, 2020; date of current version February 17, 2021. This work was supported in part by Samsung Research, Samsung Electronics, and in part by the National Research Foundation of Korea (NRF) grant funded by the Korean Government (MSIT) under Grant 2020R1A2C1009984. (Corresponding author: Chung G. Kang.) The authors are with the School of Electrical Engineering, Korea University, Seoul 02841, South Korea (e-mail: email@example.com; firstname.lastname@example.org).
© 1983-2012 IEEE.
- Grant-free access
- non-orthogonal Zadoff-Chu sequences
- quality-of-services (QoS)
ASJC Scopus subject areas
- Computer Networks and Communications
- Electrical and Electronic Engineering