Towards Efficient Transport for Real-Time Immersive Applications over Hybrid Networks

Immersive telepresence demands high data rates and low latency, yet no single commercial data path reliably meets these needs. Fine-grained content selection also remains underdeveloped. This work proposes a hybrid, multi-path delivery framework combining broadcast and unicast into a single service. A lightweight base scene is broadcast via File Delivery over Unidirectional Transport (FLUTE), ensuring no viewer ever sees a fully blank scene, while viewer-specific enhancements are steered over unicast. An open-source testbed is released to investigate the impact of network impairments, instrument common protocols, and enable reproducible experiments. On high-quality volumetric video (up to 100k points per frame at 30 frames per second), the hybrid design (i) keeps latency below 40 ms while scaling quality with unicast bandwidth, (ii) reduces server and network load compared to pure unicast, and (iii) masks typical wireless loss patterns with only $15 \%$ Forward Error Correction (FEC) overhead. These findings show that treating broadcast and unicast as complementary channels is crucial for scalable Extended Reality (XR) services.