Mission Critical User Priority-Based Random Access Scheme for Collision Resolution in Coexisting PS-LTE and LTE-M Networks

Ishtiaq Ahmad,Kyunghi Chang

doi:10.1109/access.2019.2934778

Abstract

Random-access channels (RACHs) are designed to establish a connection between the user equipments (UEs) and the network. However, the current long-term evolution (LTE) standard has limitations in providing RACH resources to massive UE connections. If numerous UEs send a connection request simultaneously, it results in severe collisions and significant access delays that degrade system performance. There has been a lot of previous research into controlling this overload; however, there are no proposals to resolve RACH overload issues for mission-critical high-priority (MCHP) UEs in coexisting LTE-based public safety (PS-LTE) and LTE-based marine (LTE-M) networks. Thus, immense interest and practical research are urgently required to resolve the UE initial access problem during the random-access procedure, most importantly when MCHP users exist. In this paper, we propose an efficient mission-critical user priority-based random-access scheme for coexisting PS-LTE and LTE-M networks. Since PS-LTE users have mission-critical service requirements, we give higher priority to PS-LTE UEs when allocating RACH resources in the contention-based random-access (RA) procedure. Our proposed scheme efficiently assigns RA preambles to MCHP UEs in order to avoid preamble collisions when multiple UEs try to access coexisting PS-LTE and LTE-M networks. In this paper, the performance of the proposed scheme is analyzed and evaluated based on the number of successful RACH attempts, the number of collisions, and the access delay. The simulation results show the effectiveness of the proposed scheme. Compared with a conventional random-access scheme, the proposed scheme performs remarkably well by improving the number of successful RACH attempts, reducing the number of collisions, and minimizing the access delay to coexisting PS-LTE and LTE-M networks.

Highlights

In modern cellular networks, mobile stations request initial access to a network when establishing a connection by sending a request using random-access channels (RACHs)
We propose a mission-critical high-priority user–based random-access (MCHP-RA) scheme for collision resolution when PS-long-term evolution (LTE) and LTE-based marine (LTE-M) networks coexist
PROPOSED MCHP-RA SCHEME to secure mission-critical high-priority users during the random-access procedure and to reduce preamble collisions, we propose the MCHP-RA scheme

Summary

INTRODUCTION

Mobile stations request initial access to a network when establishing a connection by sending a request using random-access channels (RACHs). The proposed MCHP-RA scheme dynamically allocates random-access preambles to MCHP UEs, and provides an optimal channel access opportunity based on the number of active MCHP users. This creates a difficult challenge, or gap, for the mission-critical users during the random-access process, because no proposal is available in the existing literature [1]–[39] To fill this gap, we established this strategy of taking statistics from the current RACH slot that give an approximately correct estimation for preamble allocation to MCHP UEs in the RACH slot. A. SIMULATION RESULTS AND DISCUSSION The performance of the proposed MCHP-RA scheme for coexisting PS-LTE and LTE-M networks is assessed utilizing important performance matrices, such as the number of successful access attempts, the number of collisions and the length of access delays. The number of users that are successfully complete an access attempt is defined as: Success_Attempts

UNormal PrUNormal

Findings

CONCLUSION