Investigating the Effect of Handover on Latency in Early 5G NR Deployments for C-V2X Network Planning

Vehicle-to-Everything (V2X) communication technology aims to enhance intelligent vehicles' coordination and perception by enabling interactions with other vehicles, road users, and infrastructure. Although 4th and 5th generation cellular technologies (4G LTE and 5G NR) can support non-safety V2X communication, their design, rooted in multimedia and telephony, doesn't align well with safety-critical applications. Despite the advancements of 5G NR over 4G LTE, ensuring reliable Quality-of-Service (QoS) metrics remains a notable concern. The process of handover, a core cellular network function, significantly contributes to the challenges in cellular communication reliability. To assess handover's impact on latency in V2X communication scenarios, a driving-focused measurement campaign was executed on an early 5G NR-enabled commercial cellular network. Findings reveal that, in terms of its effect on end-user latency, the more mature 4G LTE network displays on average 63% (intra-freq.) and 36% (inter-freq.) lower latency costs when performing handovers compared to early 5G NR deployments. Notably, inter-generation handovers (4G to 5G and vice versa) exhibit 24% (intra-freq.) and 10% (inter-freq.) higher average latency costs with respect to other handover types. Furthermore, discernible variations in network reliability emerge between distinct V2X scenarios such as urban and rural environments. The prevailing reliability concerns tied to present handover algorithms hold substantial weight, as they undermine intelligent vehicles' trust in network-received information. Consequently, these outcomes underscore the urgency for designing and implementing handover strategies better suited to the dynamic mobility characteristics of intelligent vehicles across diverse V2X scenarios.