Multipath QUIC for Access Traffic Steering Switching and Splitting in 5G Advanced

The proliferation of modern mobile devices equipped with several wireless interfaces (multi-homed), along with the increasing demand for high-throughput and ultra-reliable connectivity, motivated 3GPP to specify a solution that enables multi-access communication, called access traffic steering, switching, and splitting (ATSSS). Based on this solution, a mobile device can exchange data traffic with the 5G core network by simultaneously using different access networks (e.g., WiFi and 5G-NR). Consequently, data flows can enjoy aggregated bandwidth and also reduced delay and increased reliability. In this article, we briefly present the key concepts and functionality of ATSSS, and we focus on the ATSSS enhancements considered for 5G Advanced (i.e., in 3GPP Rel-18). In particular, we present a new steering functionality that is based on the QUIC protocol and its multipath extensions. We discuss the motivation for this steering functionality, its features and user-plane operation, and we explain how it can be applied to proxy UDP traffic over HTTP.