Partially Reliable Transport Layer for QUICker Interactive Immersive Media Delivery

Abstract

Interactive immersive media come with stringent network-level requirements such as high bandwidth (i.e., several Gbps) and low latency (i.e., five milliseconds). Today, most video-streaming applications leverage the transmission control protocol (TCP) for reliable end-to-end transmission. However, the reliability of TCP comes at the cost of additional delay due to factors such as connection establishment, head-of-line (HOL) blocking, and retransmissions under sub-optimal network conditions. Such behavior can lead to stalling events or freezes, which are highly detrimental to the user's Quality of Experience (QoE). Recently, QUIC has gained traction in the research community, as it promises to overcome the shortcomings of TCP without compromising on reliability. However, while QUIC vastly reduces the connection establishment time and HOL blocking, thus increasing interactivity, it still underperforms while delivering multimedia due to retransmissions under lossy conditions. To cope with these, QUIC offers the possibility to support unreliable delivery, like that of the user datagram protocol (UDP). While live-video streaming applications usually opt for completely unreliable protocols, such an approach is not optimal for immersive media delivery since it is not affordable to lose certain data that might affect the end user's QoE. In this paper, we propose a partially reliable QUIC-based data delivery mechanism that supports both reliable (streams) and unreliable (datagrams) delivery. To evaluate its performance, we have considered two immersive-video delivery use cases, namely tiled 360-degree video and volumetric point clouds. Our approach outperforms state-of-the-art protocols, especially in the presence of network losses and delay. Even at a packet loss ratio as high as 5%, the number of freezing events for a 120-second video is almost zero as against 120 for TCP.

Adaptive Partially Reliable Delivery of Immersive Media Over QUIC-HTTP/3

“…Unlike TCP, QUIC introduces streams on the transport layer, thereby making it aware of the streams being multiplexed on the application layer. The streams on the transport layer can be mapped to those on the application layer, which lets the transport layer process streams individually [7].…”

“…Moreover, the presence of reliability at the transport layer proves to be a performance bottleneck, especially for applications with lowlatency requirements. In our previous work, we have shown that not all applications require complete reliability at the transport layer [7]. This subsection provides an overview of related work in the domain of partially reliable data delivery.…”

“…As mentioned in Section I, in [7] we have introduced the partially reliable transport layer framework. The datagram extension to the QUIC protocol was deployed to transfer data in parallel, using reliable streams and unreliable datagram flows on a single connection.…”

“…Nowadays, video streaming applications using dynamic adaptive streaming over hypertext transfer protocol (HTTP) (DASH) rely on the transmission control protocol (TCP) for the sake of reliability. However, under fluctuating lossy conditions, TCP suffers from issues like head-of-line (HOL) blocking, slow connection setup times, and delay due to retransmissions [7]. In the context of video streaming, this translates to startup delay, service delay, lower throughput, and playout interruptions.…”

“…In our previous work, we presented a proof of concept of a partially reliable variant of QUIC (QPR) [7]. This work offered preliminary insights into the functioning of the protocol using a static scenario, both in terms of content and networking conditions.…”