Non-Orthogonal Random Access and Data Transmission Scheme for Machine-to-Machine Communications in Cellular Networks

Yali Wu,Ningbo Zhang,Kaixuan Rong

doi:10.1109/access.2020.2972064

Abstract

In order to address the signalling overhead and resource allocation problems of Machine-to-Machine (M2M) communications with non-orthogonal multiple access (NOMA), we propose a hybrid non-orthogonal random access and data transmission (NORA-DT) scheme. A novel design of NORA-DT protocol for M2M communications in cellular networks is firstly proposed. A power back-off scheme is introduced to adjust machine-type communications device (MTCD)'s target arrived power, and a closed-form analytic formula for the relation of MTCD's transmission power is derived. Based on the transmission power relation, the devices are clustered into a set of NOMA clusters. In the hybrid NORA-DT protocol, the cluster center MTCD transmits a extended preamble on behalf of the MTCDs in the same NOMA cluster on the physical random access channel (PRACH) for connection request. Base station (BS) can perfectly detect the preamble collisions in advance and schedules physical uplink shared channel (PUSCH) only to the NOMA clusters without collision. Then the MTCDs in the same NOMA clusters transmit data packets right after preamble transmission on the PUSCH to reduce the signalling overhead. By finding the optimal power allocation, we propose a low-complexity energy efficiency maximization problem for NORA-DT scheme. Due to the relation of MTCD's transmission power, we transform the problem into the function of cluster center MTCD's transmission power and solve it by difference of convex (DC) programming under the maximum transmission power constraints and minimum rate requirements at the MTCDs. A computationally efficient adaptive resource allocation scheme is finally proposed to improve the system throughput and resource usage. The optimal resource allocation between PRACH and PUSCH for any number of MTCDs can be learned by BS in advance, which avoids frequent computation. The analytic model is validated by simulation results. We demonstrate that the proposed NORA-DT scheme can significantly improve the system throughput, resource efficiency and energy efficiency performance.

Highlights

Different form the aforementioned studies which mainly focus on performance analysis of data transmission process, Liang et al [42] propose a non-orthogonal random access (NORA) scheme based on successive interference cancelation (SIC), which utilizes the spatial distribution of machine-type communications device (MTCD) to allow multiple devices to use the same resource block (RB) for preamble transmission
Based on the relation of MTCD’s transmission power, the MTCDs are clustered into a set of non-orthogonal multiple access (NOMA) clusters
Based on the range of transmission power derived under the maximum transmission power constraints and minimum rate requirements at the MTCDs, the MTCDs are clustered into a set of NOMA clusters

Summary

INTRODUCTION

As a key technology in 5G wireless communications, non-orthogonal multiple access (NOMA) can simultaneously enable multiple users to transmit in the same channels by splitting different users in the power domain, which yields a significant gain in spectrum efficiency [16]–[20] This favorable character makes NOMA to be a promising access solution for supporting the massive MTCDs in cellular enabled M2M networks. Different form the aforementioned studies which mainly focus on performance analysis of data transmission process, Liang et al [42] propose a non-orthogonal random access (NORA) scheme based on SIC, which utilizes the spatial distribution of MTCDs to allow multiple devices to use the same RBs for preamble transmission.

SYSTEM MODEL

NOMA CLUSTER ESTABLISHMENT

ADAPTIVE RESOURCE ALLOCATION BASED ON DEVICE

PERFORMANCE EVALUATION

Findings

CONCLUSION