ZTE X-Edge Solution: Diversifying XR Commercial Scenarios

The extended reality (XR) industry is one of the seven key industries in the development of digital economy. As XR equipment can provide immersive experience, it is regarded as the entrance into the metaverse in the future. 2016 was once called the first year of Chinese VR, but poor mobility and low resolution of terminals became hindrances to industry development. With the large-scale commercial use of 5G, XR services have ushered in a good momentum of progress.

Opportunities and Challenges Coexist

According to statics, the global XR market size is about US $27.96 billion in 2021 and is expected to reach US $252.16 billion in 2028, at a CAGR of about 31.64%. The Asia-Pacific market is growing most rapidly. With the enrichment of content and the upgrade of device experience, the shipments of VR/AR head-mounted displays are growing steadily.

Compared with video services, XR requires higher resolution for immersive experience. Most smart phones support a resolution of 1080p, while XR is a near-eye display service that requires a resolution of 8K to completely eliminate the sense of image granularity, which increases the demand for network traffic more than ten times. This is both an opportunity and a challenge for 5G networks.

The XR service can be divided into the following four levels according to different bandwidth and latency requirements (Fig. 1):

• High fidelity and strong interaction: bandwidth > 100 Mbps, latency < 20 ms
• High fidelity and weak interaction: bandwidth > 100 Mbps, latency > 150 ms
• Low fidelity and strong interaction: bandwidth < 100 Mbps, latency < 100 ms
• Low fidelity and weak interaction: bandwidth < 10 Mbps, latency > 150 ms

It is a huge challenge to commercial scenarios with data rates of over 100 Mbps and 20 ms latency. As more and more users use XR applications, ensuring the best experience for each user is an urgent issue to be addressed.

ZTE X-Edge Solution Enables Deterministic User Experience

ZTE has put forward the X-Edge solution to guarantee XR services. With 5G RAN intelligent sensing and scheduling, differentiated services are precisely guaranteed to enable ultimate user experience. First, identify XR service features, such as frame size and period; second, schedule it with the best suitable scheme. What's more, introducing multicast and broadcast services (MBS) for XR will enable greater user density in a single cell, which is a major issue in commercial networks. In addition, the network status can be transferred to XR applications for cross-layer coordination. This helps the applications adjust their transmission strategies to improve the success rate.

• Intelligent identification: The XR industry is maturing and developing on a large scale, and there is a strong demand for using XR everywhere. However, there are various types of XR services with diverse features, so it is difficult to unify the requirements for mobile networks. ZTE owns unique base station-level deep packet inspection (DPI) that can identify 16,000+ services (apps) and provide targeted guarantee for different XR services.
• Intelligent scheduling: After being identified, different XR flows need to be guaranteed. The intelligent scheduling policy can reduce the waiting delay of the XR service, and an XR video source coding algorithm presents a quasi-periodic rule. For example, a 120 frame-per-second (fps) video transmits one frame of data packet at an interval of 8.33 ms. The gNodeB automatically learns the packet period characteristics of different XR flows and matches them with efficient scheduling policies to reduce the XR delay and jitter.
• Multi-user anti-congestion scheme: Video data packets usually consist of I frames and P frames, in which an I frame involves all the information of the image and a P frame only contains part of the supplement information, so that the I frame is much larger than the P frame. In a large-capacity scenario, because I frames are irreplaceable, when multiple users request the XR service at the same time, I frames may arrive at the base station at the same time, causing I frame collision and instantaneous congestion. As a result, some XR services are delayed, and user experience is poor. Therefore, the multi-user anti-congestion policy is used in the X-Edge solution to stagger traffic periods and avoid congestion. The result shows that the collision probability decreases by 10 times, that is, the video stalling probability decreases by 10 times.
• XR experience evaluation system: An end-to-end XR evaluation system is established on the basis of differentiated guarantee for XR services. Digital twins are used to improve efficiency and accuracy of the evaluation and accelerate the development of the XR industry chain. The evaluation system is established in terms of media quality, interactive quality and display quality, which involves whether there are VR audios and videos, whether users feel dizzy, and whether blurred screens and stuttering occur when watching videos. In addition, a digital twin simulation platform is also built to collect and process data, analyze service features, and iteratively optimize evaluation algorithms to improve the accuracy of the evaluation system.
• Cloud rendering @ computing base station: At present, the processing capability of the terminal cannot meet the requirement for full immersive experience, and the existing network architecture cannot meet the latency need of strong interactive XR services. One highlight of the X-Edge solution is the industry's exclusive cloud rendering @ computing base station, which implements accurate identification of XR services and guarantees priority scheduling of XR services. Moreover, the rendering function is offloaded from the terminal side to the base station, reducing power consumption and terminal complexity.
• Energy saving on XR terminals: The terminal energy-saving function improves battery life of the terminal, alleviates its heating problem, and provides users with a comfortable wearing experience. For example, if the video frame rate is 60 fps, the XR service transmits one frame of data packets at an interval of 16.7 ms. In the traditional solution, the C-DRX period is an integer (such as 6/8/10/20/30), which cannot correspond to the XR service period. As the data volume increases, the deviation becomes larger and larger, resulting in jitter. In the X-Edge solution, the gNodeB can adaptively adjust the wake-up signals in accordance with the identified period characteristics, so that the C-DRX period can be dynamically matched with the XR service period. The simulation result shows that the solution saves power by 20%.

5G Helps XR Become a More Popular Application

In addition to the development of XR applications, 5G will bring mobility to drive XR from indoor to outdoor, from fixed places to broad areas, and expand more XR applications to anywhere. The growth of XR services will greatly increase the needs for 5G traffic, increase the investment in 5G network, and improve user experience. This will promote the development of more high-quality content, thereby attracting more XR users. 5G and XR can form the flywheel effect. ZTE is poised to work with industry partners to promote the development of new technologies with the aim of providing superior networks for large-scale commercial use of XR.