Mode 0: A New 3GPP V2X Resource Allocation Category for Roadside Computing Unit-Assisted Safety Communication
2026-05-25 • Networking and Internet Architecture
Networking and Internet ArchitectureMultiagent Systems
AI summaryⓘ
The authors argue that the current 3GPP system for vehicle communication, which only considers base stations and vehicles, is missing an important category. They propose adding 'Mode 0,' centered on Roadside Computing Units that combine sensors, communication, and computing at traffic spots. Their simulations show this setup improves coordination and safety by reducing communication delays and better handling complex traffic situations. They suggest 3GPP should study and standardize this new mode to enhance vehicle-to-everything (V2X) communication.
3GPPV2XLTENRRoadside Computing UnitResource AllocationLatencyMulti-Agent Proximal Policy OptimizationSidelink CommunicationTraffic Management
Authors
Dewei Jiang, Xiang Gu
Abstract
The 3GPP V2X resource allocation framework defines two entity classes -- the base station and the vehicle UE -- and four modes across LTE and NR generations. We demonstrate that this binary taxonomy is structurally incomplete. Base station-led scheduling saturates at high-density traffic nodes, producing latency-tail failures that persist even when mean packet delivery ratios approach the service-class target. UE autonomy is categorically incapable of pre-emergence warning for occluded traffic participants and insufficient for large-scope cascading environmental hazards. We propose Mode 0, a new 3GPP V2X category whose defining entity is the Roadside Computing Unit (RCU) -- an infrastructure ensemble integrating elevated sensing (Seeing), sidelink communication (Speaking), and local computational evaluation (Thinking), owned by traffic management authorities. Mode 0 defines a subfamily spectrum from Mode 0a (all-passive UEs, the guaranteed minimum) through Mode 0c (all-active UEs, the optimal target). Convergent deployment evidence from Chinese national standards (DB11/T 2329.1-2024, T/ITS 0224.1-2025), China Unicom RS-MEC infrastructure, and European and US C-V2X programs confirms that both institutional sides are converging on the roadside traffic node without a coordination standard. A fifteen-run Multi-Agent Proximal Policy Optimization (MAPPO) simulation validates the architectural family: Mode 0a in shared-pool baseline sits at the analytical symmetric-Nash coordination floor; Mode 0c with demand separation achieves strict Pareto improvement for both traffic classes (M0 PDR 0.999, M1 PDR 0.998 at $ρ_{\rm pool} \leq 1$) and lifts the worst-TTI delivery ratio from near-zero to 0.601 -- the only configuration satisfying the latency safety requirement structurally. We call for a 3GPP study item on Mode 0 within the NR-V2X sidelink enhancement work programme.