Polling Model for Analysis of Round-Trip Time in the IAB Network

In today’s rapidly evolving world of mobile communications, 5G and 6G networks are leveraging millimeter-wave and sub-millimeter-wave frequencies to achieve faster speeds and higher capacities. To address the challenge of shorter coverage areas, integrated access and backhaul (IAB) technologies have been adopted, creating a dense and cost-effective network of relay nodes. This approach has the potential to significantly reduce the cost and time required for operators to transition to next-generation networks. This paper explores the operation of boundary nodes in IAB networks with half-duplex data transmission. To simulate the operation of the boundary node, we propose a mathematical model of a polling service system with an arbitrary number of queues in continuous time. This model is used to analyze the probabilistic-time characteristics of the system. We investigate delays in packet transmission in the network and their compliance with 5G network standards. The proposed model is analyzed using queueing theory, generating functions (GFs), and integral transformations such as Laplace (LT) and Laplace-Stieltjes (LST) transforms. As a result, a polling service model with an arbitrary number of queues and a cyclic service was designed, where requests are received during switching periods after the end of the service cycle. The GF, distributions, raw and central moments of the number of requests in queues, as well as LST, cumulative distribution functions (CDFs), and raw and central moments of request dwell time at the queue service phases, were derived. Additionally, a numerical analysis of round-trip time (RTT) fragment during data transmission was performed, allowing us to investigate the age of information metric.