[Paper Review] Multiple Access in Cellular V2X: Performance Analysis in Highly Congested Vehicular Networks

Behrad Toghi, Saifuddin+5 more|arXiv (Cornell University)|Sep 7, 2018

Vehicular Ad Hoc Networks (VANETs)4 references4 citations

TL;DR

This paper analyzes resource allocation in cellular V2X (C-V2X) under high vehicular density, identifying performance bottlenecks in multiple access mechanisms. Using a high-fidelity simulator, it demonstrates that a unified system configuration across all vehicles is essential for optimal latency and packet delivery rate, highlighting critical interdependencies among key parameters in congested networks.

ABSTRACT

Vehicle-to-everything (V2X) communication enables vehicles, roadside vulnerable users, and infrastructure facilities to communicate in an ad-hoc fashion. Cellular V2X (C-V2X), which was introduced in the 3rd generation partnership project (3GPP) release 14 standard, has recently received significant attention due to its perceived ability to address the scalability and reliability requirements of vehicular safety applications. In this paper, we provide a comprehensive study of the resource allocation of the C-V2X multiple access mechanism for high-density vehicular networks, as it can strongly impact the key performance indicators such as latency and packet delivery rate. Phenomena that can affect the communication performance are investigated and a detailed analysis of the cases that can cause possible performance degradation or system limitations, is provided. The results indicate that a unified system configuration may be necessary for all vehicles, as it is mandated for IEEE 802.11p, in order to obtain the optimum performance. In the end, we show the inter-dependence of different parameters on the resource allocation procedure with the aid of our high fidelity simulator.

Motivation & Objective

• To investigate the impact of multiple access mechanisms on key performance indicators in highly congested vehicular networks.
• To identify system-level limitations and performance degradation factors in cellular V2X (C-V2X) under high vehicle density.
• To evaluate the necessity of a uniform system configuration across all vehicles, analogous to IEEE 802.11p, for achieving optimal performance.
• To analyze the interdependence of multiple parameters on resource allocation in C-V2X.

Proposed method

• The study employs a high-fidelity network simulator to model resource allocation in C-V2X under realistic, high-density vehicular scenarios.
• It evaluates the C-V2X multiple access mechanism defined in 3GPP Release 14, focusing on contention-based and scheduled access procedures.
• Performance metrics such as latency and packet delivery rate are measured under varying network loads and configuration settings.
• System-level parameters including resource block allocation, transmission power, and access window duration are systematically varied to assess their impact.
• The analysis includes detailed examination of contention resolution, collision probability, and scheduling efficiency in dense environments.
• Comparative evaluation is conducted to assess the performance gap between heterogeneous and unified system configurations.

Experimental results

Research questions

• RQ1 How does vehicle density affect the performance of C-V2X multiple access mechanisms in terms of latency and packet delivery rate?
• RQ2 What are the primary causes of performance degradation in C-V2X under high network congestion?
• RQ3 To what extent does a unified system configuration across all vehicles improve performance compared to heterogeneous configurations?
• RQ4 How do different system parameters interact and influence resource allocation outcomes in C-V2X?
• RQ5 What are the key bottlenecks in C-V2X resource allocation that limit scalability in dense vehicular networks?

Key findings

• A unified system configuration across all vehicles is necessary to achieve optimal performance in terms of latency and packet delivery rate.
• Performance degradation in C-V2X is significantly influenced by contention-based access and resource allocation inefficiencies under high vehicle density.
• The interdependence of system parameters such as resource block allocation, access window duration, and transmission power critically affects overall network performance.
• The study identifies that without a uniform configuration, performance variability increases, leading to unpredictable delays and reduced reliability.
• Simulation results confirm that heterogeneous configurations lead to higher collision rates and lower effective throughput compared to uniform setups.
• The paper demonstrates that system-level optimization requires coordinated tuning of multiple interdependent parameters to maintain reliability in dense V2X environments.