The Impact of Mobile Blockers on Millimeter Wave Cellular Systems

TL;DR

This paper models dynamic millimeter wave blockage events caused by mobile blockers and evaluates their impact on system performance, emphasizing the importance of BS density for meeting QoS in urban environments.

Contribution

It introduces a LOS dynamic blockage model for mmWave systems and analyzes the effects of blockers and NLOS links on system reliability and latency.

Findings

Blockage events significantly affect mmWave system performance.

Minimum BS density is driven by blockage and latency constraints.

NLOS links can mitigate blockage effects in dense urban areas.

Abstract

Millimeter Wave (mmWave) communication systems can provide high data rates, but the system performance may degrade significantly due to interruptions by mobile blockers such as humans or vehicles. A high frequency of interruptions and lengthy blockage durations will degrade the quality of the user's experience. A promising solution is to employ the macrodiversity of Base Stations (BSs), where the User Equipment (UE) can handover to other available BSs if the current serving BS gets blocked. However, an analytical model to evaluate the system performance of dynamic blockage events in this setting is unknown. In this paper, we develop a Line of Sight (LOS) dynamic blockage model and evaluate the probability, duration, and frequency of blockage events considering all the links to the UE which are not blocked by buildings or the user's own body. For a dense urban area, we also analyze the impact of non-LOS (NLOS) links on blockage events. Our results indicate that the minimum density of BS required to satisfy the Quality of Service (QoS) requirements of Ultra Reliable Low Latency Communication (URLLC) applications will be driven mainly by blockage and latency constraints, rather than coverage or capacity requirements.