[Paper Review] Content Distribution based on Joint V2I and V2V Scheduling in mmWave Vehicular Networks

Lan Su, Yong Niu+6 more|arXiv (Cornell University)|Jun 1, 2022

Millimeter-Wave Propagation and Modeling4 citations

TL;DR

This paper proposes a joint V2I and V2V scheduling scheme in mmWave vehicular networks to minimize content distribution time slots and maximize system throughput. By leveraging RSU-based V2I transmission and full-duplex, concurrent V2V communications, the scheme reduces time slots by up to 41.5% and boosts throughput by over 60% compared to non-cooperative and FCFS schemes, especially under large file transfers and high vehicle density.

ABSTRACT

With the explosive growth of vehicle applications, vehicular networks based on millimeter wave (mmWave) bands have attracted interests from both academia and industry. mmWave communications are able to utilize the huge available bandwidth to provide multiple Gbps transmission rates among vehicles. In this paper, we address the content distribution scheduling problem in mmWave vehicular networks. It has been challenging for all vehicles in the same network to complete content downloading due to the limited communication resources of roadside units (RSUs) and the high mobility of vehicles. We propose a joint vehicle-to-infrastructure (V2I) and vehicle-tovehicle (V2V) scheduling scheme to minimize the total number of content distribution time slots from a global optimization perspective. In the V2I phase, the RSU serially transmits integrity content to vehicles, which are selected according to the vehicular network topology and transmission scheduling scheme. In the V2V phase, full-duplex communications and concurrent transmissions are exploited to achieve content sharing between vehicles and improve transmission efficiency. Performance evaluations demonstrate that our proposed scheme reduces the number of time slots and significantly improves system throughput when compared with other schemes, especially under large-size file transfers and a large number of vehicles.

Motivation & Objective

• Address the challenge of content distribution in mmWave vehicular networks where RSUs are overloaded and vehicle mobility causes unstable connectivity.
• Overcome limitations of standalone V2I (limited coverage, high load) and V2V (unreliable, high delay) communication for large file transfers.
• Minimize total time slots for content distribution through global optimization of V2I and V2V scheduling.
• Improve system throughput and energy efficiency by exploiting full-duplex V2V communications and concurrent transmissions.
• Ensure all vehicles complete content downloads even under high mobility and large file sizes.

Proposed method

• RSUs select vehicles for V2I transmission based on network topology and vehicle proximity to optimize subsequent V2V forwarding.
• The V2I phase uses RSU to serially transmit full content to selected vehicles with high potential for forward propagation.
• The V2V phase enables full-duplex communication, allowing vehicles to transmit and receive simultaneously, increasing spectral efficiency.
• Concurrent transmissions among vehicles are scheduled to maximize spatial reuse and reduce end-to-end delay.
• A joint scheduling algorithm optimizes the allocation of time slots across V2I and V2V phases to minimize total distribution time.
• Signal interference cancellation (SIC) is applied in full-duplex V2V links to mitigate self-interference and improve reliability.

Experimental results

Research questions

• RQ1 How can joint V2I and V2V scheduling reduce the number of time slots required for content distribution in mmWave vehicular networks?
• RQ2 What is the impact of full-duplex V2V communication and concurrent transmissions on system throughput and latency?
• RQ3 How does the proposed scheme outperform non-cooperative and FCFS-based V2V cooperation schemes in terms of time efficiency and reliability?
• RQ4 To what extent does self-interference cancellation improve performance in full-duplex V2V links under varying channel conditions?
• RQ5 How does the scheme scale under increasing vehicle density and large file sizes?

Key findings

• The proposed scheme reduces the number of time slots by 41.5% compared to the random cooperation scheme and 40.6% compared to the FCFS scheme when transferring 3 GB files.
• System throughput increases by 60.9% compared to the non-cooperative scheme and by 59.2% compared to the FCFS scheme under 3 GB content size.
• The performance gain is most significant under large file transfers and high vehicle density, demonstrating scalability.
• Energy consumption is higher than in the random cooperation scheme due to increased RSU transmissions, but this is offset by improved efficiency and reliability.
• System throughput stabilizes when self-interference cancellation reaches β = 10⁻¹³, indicating diminishing returns beyond this point.
• The non-cooperative scheme fails to deliver content to all vehicles due to RSU capacity limits, while the proposed scheme ensures complete delivery.