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Analyzing Random Access Collisions in Massive IoT Networks

Research output: Contribution to journalArticle

Nan Jiang, Yansha Deng, Arumugam Nallanathan, Xin Kang, Tony Q.S. Quek

Original languageEnglish
Pages (from-to)6853-6870
Issue number10
Early online date17 Aug 2018
Publication statusPublished - Oct 2018


King's Authors


The cellular-based infrastructure is regarded as one of potential solutions for massive Internet of Things (mIoT), where the Random Access (RA) procedure is used for requesting channel resources in the uplink data transmission. Due to the nature of mIoT network with the sporadic uplink transmissions of a large amount of IoT devices, massive concurrent channel resource requests lead to a high probability of RA failure. To relieve the congestion during the RA in mIoT networks, we model RA procedure, and analyze as well as evaluate the performance improvement due to different RA schemes, including power ramping (PR), back-off (BO), access class barring (ACB), hybrid ACB and back-off schemes (ACB&BO), and hybrid power ramping and back-off (PR&BO). To do so, we develop a traffic-aware spatio-temporal model for the contention-based RA analysis in the mIoT network, where the signal-to-noiseplus- interference ratio (SINR) outage and collision events jointly determine the traffic evolution and the RA success probability. Compared with existing literature only modelled collision from single cell perspective, we model both SINR outage and the collision from the network perspective. Based on this analytical model, we derive the analytical expression for the RA success probabilities to show the effectiveness of different RA schemes. We also derive the average queue lengths and the average waiting delays of each RA scheme to evaluate the packets accumulation status and packets serving efficiency. Our results show that our proposed PR&BO scheme outperforms other schemes in heavy traffic scenario in terms of the RA success probability, the average queue length, and the average waiting delay.

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