Real-Time Immersive Aerial Video Streaming: A Comprehensive Survey, Benchmarking, and Open Challenges

Over the past decade, the use of Unmanned Aerial Vehicles (UAVs) has grown significantly due to their agility, maneuverability, and rapid deployability. An important application is the use of UAV-mounted 360-degree cameras for real-time streaming of Omnidirectional Videos (ODVs), enabling immersive experiences with up to six Degrees-of-freedom (6DoF) for applications like remote surveillance and gaming. However, streaming high-resolution ODVs with low latency (below 1 second) over an air-to-ground (A2G) wireless channel faces challenges due to its inherent non-stationarity, impacting the Quality-of-experience (QoE). Limited onboard energy availability and energy consumption variability based on flight parameters add to the complexity. This paper conducts a thorough survey of challenges and research efforts in UAV-based immersive video streaming. First, we outline the end-to-end 360-degree video transmission pipeline, covering coding, packaging, and streaming with a focus on standardization for device and service interoperability. Next, we review the research on optimizing video streaming over UAV-to-ground wireless channels, and present a real testbed demonstrating 360-degree video streaming from a UAV with remote control over a 5G network. To assess performance, a high-resolution 360-degree video dataset captured from UAVs under different conditions is introduced. Encoding schemes like AVC/H.264, HEVC/H.265, VVC/H.266, VP9, and AV1 are evaluated for encoding latency and QoE. Results show that HEVC's hardware implementation achieves a good QoE-latency trade-off, while AV1's software implementation provides superior QoE. The paper concludes with discussions on open challenges and future directions for efficient and low-latency immersive video streaming via UAVs.