ProxLink: A Lightweight Decentralized Synchronization Framework for Multi-User XR

Abstract

Multi-user extended reality (XR) applications require accurate spatial synchronization across devices to support real-time interactions such as content sharing. Existing approaches primarily rely on centralized infrastructure and exhaustive cross-user visual feature matching, resulting in substantial communication and computational overhead. In this paper, we present ProxLink, a fully decentralized synchronization framework that eliminates the need for a global map server and enables lightweight peer-to-peer spatial coordination without centralized control. To reduce bandwidth and computation overhead, ProxLink introduces a multi-stage filtering pipeline before visual feature matching, combining RF-IMU distance estimation to identify nearby users, overlapping map-point density prediction to estimate potential view overlap, and graph-based structured matching to narrow the map-point candidate space before final feature-based relative pose estimation. Implemented on commodity XR devices without server support, ProxLink reduces bandwidth consumption by 10-15× and initial pairwise synchronization latency by over 3× compared with Map++, the state-of-the-art centralized baseline, and over 2× compared with FreeAR (a decentralized scheme), while keeping bandwidth below 6 Mbps for 15 users and achieving comparable or better synchronization accuracy.