Tree-splitting algorithms for massive random access of 5G NB-IoT communications

V. A. Beschastnyi^a, A. M. Turlikov^b, N. V. Stepanov^b, V. S. Shorgin<sup>c

a</sup> Peoples' Friendship University of Russia (RUDN University), 6 Miklukho- Maklaya Str., Moscow 117198, Russian Federation
^b Saint Petersburg State University of Aerospace Instrumentation, 67 Bolshaya Morskaya Str., Saint Petersburg 190000, Russian Federation
^c Federal Research Center "Computer Science and Сontrol" of the Russian Academy of Sciences, 44-2 Vavilov Str., Moscow 119333, Russian Federation

Abstract: State-of-the-art Internet of Things (IoT) applications are characterized by exclusive requirements on latency which are much higher than those defined for 5G Massive Machine-Type Communications in ITU-R M.2410 (e. g., less than 10 ms). For this reason, 3GPP (3rd Generation Partnership Project) has defined several procedures to reduce access latency in the 5G NB-IoT systems. However, these procedures are purely ALOHA-type and do not use information that may be available on the NB-IoT base station. In this paper, two extensions of the random access procedure based on tree-splitting algorithms have been considered. The results show that the algorithm with blocked access is characterized by a 25%–35% higher throughput compared to the free-access algorithm. At the same time, the considered algorithms can be effectively employed in the case when the traffic load does not exceed 70%–80% of the available throughput.

Keywords: 5G, NB-IoT, RACH, delay, tree splitting.

Received: 22.08.2025
Accepted: 15.10.2025

DOI: 10.14357/08696527250402