ARC: Consistent, Low-Latency Delivery via Receiver-Side Scheduling

TL;DR

ARC is a lightweight receiver-side protocol that restores sender-like timing in data delivery, reducing jitter and improving performance for latency-sensitive applications without requiring transport modifications.

Contribution

It introduces a novel receiver-only scheduling protocol, ARC, that maintains sender timing and order, enhancing application performance across various transport protocols.

Findings

ARC removes large jitter excursions in cloud gaming workloads.

ARC closely matches sender timing, improving perceptual smoothness.

Broader latency benefits are observed across TCP, QUIC, WebRTC, UDP, and RTP.

Abstract

Applications such as cloud gaming, video streaming, telemetry, ML inference, and data transfer provide a better experience when data is released at the receiver with timing reflecting how the data enters the sender. In practice, network delay variation and recovery dynamics at the receiver distort this timing even when transports deliver all packets correctly, producing visible jitter, stalls, and unstable playback. Many such applications operate best when delivery preserves this timing behavior and its implied order; out-of-order or irregular delivery can significantly degrade performance even when all data eventually arrives. We present a lightweight receiver-side release scheduling protocol, Adaptive Release Control (ARC), that restores this timing at the receiver. ARC releases recovered data in a manner that follows the sender's timing, maintaining ordering and limiting reordering when necessary while producing smooth delivery with minimal added latency given network conditions. It operates entirely on the receiver clock and requires no feedback, synchronization, or changes to the underlying transport. As an example, we integrate ARC into LT3, a network-layer system currently deployed as a software overlay that forwards traffic without altering the transport protocols it carries, where ARC functions as an independent module that regulates release timing for forwarded data. Evaluating LT3 with ARC on a cloud-gaming workload shows that the protocol removes virtually all large jitter excursions and yields release intervals that closely match the sender's timing, translating into improved perceptual smoothness. Broader latency improvements arise from the behavior of the full LT3 system. The benefits of ARC extend to transport protocols carried over LT3, including TCP, QUIC, WebRTC, UDP, and RTP, as preserving sender timing improves their behavior across a wide range of conditions.