Effects of Small-Scale User Mobility on Highly Directional XR Communications

TL;DR

This work addresses the challenge of maintaining reliable, high-rate mmWave XR connectivity in the presence of small-scale mobility (lateral shifts and head rotations) that causes beam misalignment. It combines a real-world VR gaming mobility dataset with 3D simulations of directional mmWave links (IEEE 802.11ad/ay at 60 GHz) to quantify how angular and lateral movements, and their speeds, affect beam alignment, SNR, and outages. The study finds that angular movements dominate misalignment, with higher angular speeds exacerbating SNR degradation and outage risk, while beamwidth adjustments can mitigate these effects. The authors propose IMU-assisted beam management, predictive and on-demand beam realignment, and redundancy as effective strategies, and provide a public mobility dataset (myData) to benchmark future XR beam management approaches, informing design choices for robust XR wireless systems.

Abstract

The development of next-generation communication systems promises to enable extended reality (XR) applications, such as XR gaming with ultra-realistic content and human-grade sensory feedback. These demanding applications impose stringent performance requirements on the underlying wireless communication infrastructure. To meet the expected Quality of Experience (QoE) for XR applications, high-capacity connections are necessary, which can be achieved by using millimeter-wave (mmWave) frequency bands and employing highly directional beams. However, these narrow beams are susceptible to even minor misalignments caused by small-scale user mobility, such as changes in the orientation of the XR head-mounted device (HMD) or minor shifts in user body position. This article explores the impact of small-scale user mobility on mmWave connectivity for XR and reviews approaches to resolve the challenges arising due to small-scale mobility. To deepen our understanding of small-scale mobility during XR usage, we prepared a dataset of user mobility during XR gaming. We use this dataset to study the effects of user mobility on highly directional communication, identifying specific aspects of user mobility that significantly affect the performance of narrow-beam wireless communication systems. Our results confirm the substantial influence of small-scale mobility on beam misalignment, highlighting the need for enhanced mechanisms to effectively manage the consequences of small-scale mobility.

Figures (5)

• Figure 1: Illustration of directional XR communication and beam misalignment due to small-scale mobility.
• Figure 2: Misalignment due to angular and lateral movement.
• Figure 3: Beam misalignment during VR gaming.
• Figure 4: SNR w.r.t. angular speed.
• Figure 5: Outage w.r.t. antenna elements.