SFU Bandwidth Estimation for Sender-Side Rate Control
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Solution Overview
Problem
Current communication systems lack an effective method for end-to-end bandwidth estimation from publishers to subscribers, which is essential for global optimization of bitrate in multi-party conferencing scenarios.
Innovation Solution
Implementing full sender-side rate-control between publishers, a Selective Forwarding Unit (SFU), and subscribers, where the SFU determines bandwidth estimations for each subscriber and aggregates them to limit the sender's bitrate, ensuring optimal bitrate adjustment based on collective subscriber feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If receiver-side rate control is used with REMB messages, then the subscriber can communicate bandwidth estimation back to the sender, but the REMB messages are typically inaccurate and do not provide end-to-end bandwidth estimation
Solution Approach 1:
The patent introduces timing feedback messages as an intermediary mechanism between the SFU and publisher. These timing feedback messages contain precise timing information about packet arrival times, which the publisher uses to calculate accurate bandwidth estimation through sender-side rate control, eliminating the need for unreliable receiver-side REMB messages.
Solution Approach 2:
The patent implements a feedback mechanism where the SFU sends timing feedback messages to the publisher, and the publisher adjusts its transmission rate based on this feedback. This closed-loop feedback system enables continuous refinement of bandwidth estimation, achieving high measurement precision without relying on inaccurate receiver-side reports.
2Productivity
If sender-side rate control is used between publisher and SFU, then the publisher can probe available bandwidth, but there is no method for merging multiple timing feedbacks from multiple subscribers
Solution Approach 1:
The patent merges multiple timing feedbacks from multiple subscribers by aggregating their individual timing information at the SFU. The SFU combines timing feedback messages from all subscribers and presents a unified bandwidth estimation to the publisher, enabling the publisher to perform single probe operations that effectively test the aggregate capacity of all subscriber connections simultaneously.
Solution Approach 2:
The timing feedback mechanism serves multiple functions: it provides bandwidth estimation for each individual subscriber connection, aggregates to provide end-to-end bandwidth estimation across all subscribers, and enables the publisher to adjust its transmission rate accordingly. This multi-functional approach eliminates the need for separate probing operations for each subscriber.
3Reliability
If the SFU collects bandwidth estimation from all subscribers and forwards to the publisher, then end-to-end rate control is achieved, but the complexity of aggregating and processing multiple bandwidth estimations increases
Solution Approach 1:
The SFU automatically performs bandwidth estimation for each subscriber connection using timing feedback messages, and then aggregates these estimations to determine the end-to-end bandwidth. This self-service mechanism eliminates the need for manual configuration or complex external processing, as the SFU autonomously handles the aggregation and presents a unified bandwidth estimation to the publisher.
Data Source
AI summary
A method and apparatuses for full sender-side rate control include receiving a data stream at a forwarding unit, determining a bandwidth estimation for communicating the data stream between the forwarding unit and a sender of the data stream, determining respective bandwidth estimations for communicating the data stream between the forwarding unit and at least two receivers, aggregating the bandwidth estimations determined for communicating the data stream between the forwarding unit and the at least two receivers, and limiting the bandwidth estimation determined for communicating the data stream between the forwarding unit and the sender of the data stream based on the aggregated bandwidth estimations. In some embodiments, the bandwidth estimation determined for communicating the data stream between the forwarding unit and the sender of the data stream is limited by communicating a limitation message regarding the aggregated bandwidth estimation of the receivers to the sender.