[Paper Review] Wireless Access to Ultimate Virtual Reality 360-Degree Video At Home

Huanle Zhang, Ahmed Elmokashfi+2 more|arXiv (Cornell University)|Dec 5, 2018

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TL;DR

This paper evaluates whether current wireless technologies—5G, IEEE 802.11ac, and IEEE 802.11ad—can support ultimate VR 360 video at home, defined by 1.5 Gbps downlink and 6.6 Gbps uplink with RTT < 8.3 ms. It finds that only IEEE 802.11ac supports single-user viewing, while IEEE 802.11ad may support it with latency improvements; none support live broadcasting or multiple users.

ABSTRACT

Virtual reality 360-degree videos will become the first prosperous online VR application. VR 360 videos are data-hungry and latency-sensitive that pose unique challenges to the networking infrastructure. In this paper, we focus on the ultimate VR 360 that satisfies human eye fidelity. The ultimate VR 360 requires downlink 1.5 Gbps for viewing and uplink 6.6 Gbps for live broadcasting, with round-trip time of less than 8.3 ms. On the other hand, wireless access to VR 360 services is preferred over wire-line transmission because of the better user experience and the safety concern (e.g., tripping hazard). We explore in this paper whether the most advanced wireless technologies from both cellular communications and WiFi communications support the ultimate VR 360. Specifically, we consider 5G in cellular communications, IEEE 802.11ac (operating in 5GHz) and IEEE 802.11ad (operating in 60GHz) in WiFi communications. According to their performance specified in their standards and/or empirical measurements, we have the following findings: (1) Only 5G has the potential to support both the the ultimate VR 360 viewing and live broadcasting. However, it is difficult for 5G to support multiple users of the ultimate VR live broadcasting at home; (2) IEEE 802.11ac supports the ultimate VR 360 viewing but fails to support the ultimate VR 360 live broadcasting because it does not meet the data rate requirement of the ultimate VR 360 live broadcasting; (3) IEEE 802.11ad fails to support the ultimate VR 360, because its current implementation incurs very high latency. Our preliminary results indicate that more advanced wireless technologies are needed to fully support multiple ultimate VR 360 users at home.

Motivation & Objective

• To assess whether existing wireless technologies can meet the extreme networking demands of ultimate VR 360 video at home.
• To identify the key performance bottlenecks—data rate and latency—for wireless access to ultra-high-fidelity VR 360 content.
• To evaluate the feasibility of 5G, IEEE 802.11ac, and IEEE 802.11ad in supporting both viewing and live broadcasting of ultimate VR 360.
• To highlight the urgent need for next-generation wireless technologies to enable multi-user, low-latency, high-throughput VR experiences.

Proposed method

• Evaluated 5G, IEEE 802.11ac, and IEEE 802.11ad based on standard specifications and empirical measurements of data rate and RTT.
• Measured RTT using ping between closely located devices to assess latency performance in real-world conditions.
• Analyzed theoretical and practical data rates for both uplink and downlink across the three technologies.
• Assessed beamforming and antenna tracking delays in IEEE 802.11ad as key contributors to high RTT.
• Compared performance against the target requirements: 1.5 Gbps downlink, 6.6 Gbps uplink, and RTT < 8.3 ms for 120 FPS.
• Evaluated the potential of implementation enhancements (e.g., beam tracking optimization) to improve IEEE 802.11ad performance.

Experimental results

Research questions

• RQ1 Can 5G support the 1.5 Gbps downlink and 6.6 Gbps uplink required for ultimate VR 360 viewing and live broadcasting?
• RQ2 Can IEEE 802.11ac support both single-user viewing and live broadcasting of ultimate VR 360 at home?
• RQ3 Can IEEE 802.11ad support single-user ultimate VR 360 viewing with acceptable latency, and what are the main latency sources?
• RQ4 Can any of the current wireless technologies support multiple users simultaneously accessing ultimate VR 360 content?
• RQ5 What are the key performance gaps that necessitate the development of next-generation wireless technologies?

Key findings

• 5G cannot support ultimate VR 360 due to insufficient user data rate, despite promising theoretical performance.
• IEEE 802.11ac supports single-user ultimate VR 360 viewing with a measured RTT of 2.3 ms and client-side data rate of 3.5 Gbps.
• IEEE 802.11ac fails to support live broadcasting due to insufficient uplink throughput (6.6 Gbps required, not met).
• IEEE 802.11ad has theoretical downlink and uplink rates of 6.8 Gbps and 4.6 Gbps, respectively, but incurs high RTT (62.7 ms) due to beam tracking delays.
• With implementation enhancements—especially in beamforming and antenna tracking—IEEE 802.11ad could potentially support single-user viewing.
• No existing wireless technology can fully support multiple users accessing ultimate VR 360 content due to insufficient uplink capacity and latency constraints.