Non-Orthogonal Random Access Control Exploiting Timing-Advance Grouping for Cellular IoT Networks

초록

Supporting massive numbers of devices with bursty access traffic remains a fundamental challenge in cellular Internet of Things (IoT) networks. Conventional orthogonal random access control schemes rely on exclusive preamble usage and therefore suffer from severe congestion and throughput degradation under high access load. In this paper, we propose a non-orthogonal random access control (N-RAC) scheme that jointly exploits timing advance (TA) group diversity and adaptive access class barring (ACB) to improve access scalability and efficiency. The proposed scheme enables non-orthogonal preamble reuse by allowing multiple devices from different TA groups to share the same preamble when their transmissions are resolvable at the base station (BS). To support this operation, we develop a TA-group-based backlog estimation method and derive an optimal ACB parameter that maximizes the average access throughput per PRACH slot under a given BS resolution capability. The resulting control mechanism operates with a single broadcast ACB parameter and does not introduce additional signaling overhead. Simulation results demonstrate that the proposed N-RAC scheme significantly reduces total service time and access delay while improving average access throughput compared with conventional orthogonal random access control. The performance gains become more pronounced as the number of TA groups and the BS’s non-orthogonal resolution capability increase. These results indicate that the proposed N-RAC scheme provides a practical and scalable random access solution for cellular massive IoT systems. © 2014 IEEE.

키워드