A Dynamic Backoff Window Scheme for Machine-Type Communications in Cyber-Physical Systems

Jenhui Chen,Yu-Syuan Lyu,Ray-Guang Cheng,Obinna Agbodike

doi:10.1109/access.2020.2973239

Abstract

A cyber-physical system (CPS) requires a time-bounded communication process for real-time interaction between the digital world and the physical world so that they can form a tight loop. Using the machine-type communication (MTC) protocol for a large-scale CPS is a good solution. However, the MTC protocol uses a random access (RA) mechanism to solve the radio resource contention problem, but that inevitably causes access delays especially in scenarios when there is a large number of MTC devices. To meet CPS requirement and address this problem, we propose a dynamic backoff window adjustment (DBA) algorithm for a pull-based RA process that can appropriately distribute the failed MTC devices engaged in the backoff window, so as to expedite their contention retrial time interval and achieve increased success probability. Simulation results showed that the DBA algorithm significantly increases the success probability of MTC devices contending for RA, and as well, shortens the mean access delay of the MTC devices. In comparison to the standard RA backoff scheme and a novel dynamic backoff (DB) scheme, the DBA algorithm proved to be more effective and suitable for the CPS to the best of our knowledge.

Highlights

The evolved universal terrestrial radio access (E-UTRA) standards, i.e., the long-term evolution (LTE) [1] and the 5G new radio (5G-NR) [2], provide a technique called the machine-type communication (MTC) that enables MTC devices to connect with the LTE networks
In this paper, we propose a novel dynamic backoff adjustment (DBA) algorithm that can systematically adjust the backoff window size for failed MTC devices in RA channels (RACHs) trials to complete their random access (RA) process by the time point of group paging. This idea is based on our previous work [17], in which we presented the general concept of the dynamic backoff window adjustment (DBA) algorithm
We significantly improved the DBA algorithm and provided more simulations for in-depth comparative analyses based on different performance metrics with respect to the cyber-physical system (CPS) scenario

Summary

INTRODUCTION

The evolved universal terrestrial radio access (E-UTRA) standards, i.e., the long-term evolution (LTE) [1] and the 5G new radio (5G-NR) [2], provide a technique called the machine-type communication (MTC) that enables MTC devices to connect with the LTE networks. In this paper, we propose a novel dynamic backoff adjustment (DBA) algorithm that can systematically adjust the backoff window size for failed MTC devices in RACH trials to complete their RA process by the time point of group paging. This idea is based on our previous work [17], in which we presented the general concept of the DBA algorithm.

TECHNOLOGY BACKGROUND

THE DBA ALGORITHM

CONCLUSION