Bandwidth Estimation Using Cross-Traffic Indications
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Solution Overview
Problem
Existing methods for estimating bandwidth in packet-based communications systems, such as 'Max throughput' and 'Relative delay' methods, require network load modification and are prone to feedback delays, while 'Blackbox methods' lack precision due to insufficient generic input information, making them inadequate for real-time applications and rate control.
Innovation Solution
A method that estimates bandwidth by receiving a packet stream, incorporating cross-traffic observations, transmission and reception times, and packet sizes using an estimation function, which calculates bandwidth based on the relationship between these factors, avoiding the limitations of RTT-based methods and providing accurate bandwidth estimation for real-time applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RTT-based bandwidth estimation methods are used, then bandwidth can be estimated using feedback packets, but feedback delays severely impact the estimation accuracy
Solution Approach 1:
The patent extracts the bandwidth estimation function from the RTT feedback mechanism. Instead of relying on RTT feedback packets that are subject to network delays, the system uses one-way delay measurements combined with cross-traffic information to directly calculate bandwidth at the receiver, eliminating the feedback delay problem entirely.
Solution Approach 2:
The patent introduces cross-traffic information as an intermediary element in the bandwidth estimation process. By measuring the actual transmission times of packets and combining this with information about cross-traffic volume, the system can calculate bandwidth without relying on delayed RTT feedback, thus resolving the contradiction between measurement accuracy and feedback delay.
2Measurement precision
If Max throughput method is used to estimate bandwidth, then the channel capacity can be determined, but the channel is overloaded obstructing other simultaneous traffic
Solution Approach 1:
The patent applies partial action by using normal packet transmission for bandwidth estimation rather than the excessive loading required by Max throughput methods. The system estimates bandwidth by measuring delays of regular traffic packets combined with cross-traffic information, achieving accurate estimation without overloading the channel and obstructing other traffic.
3Measurement precision
If Relative delay method with large packet intervals is used, then bandwidth can be estimated from RTT slope, but network queuing effects are avoided, yet transmission efficiency is reduced
Solution Approach 1:
The patent uses feedback in the form of cross-traffic information provided by the transmitter to the receiver. This feedback allows the receiver to compensate for queuing effects caused by normal packet transmission intervals, enabling accurate bandwidth estimation without requiring large packet intervals that would reduce transmission efficiency.
4Ease of operation
If Blackbox methods with generic observables are used, then bandwidth estimation can be performed without network modification, but the generic input does not provide sufficient information for precise estimation
Solution Approach 1:
The patent changes the parameters used for bandwidth estimation from generic observables to specific measurements: one-way packet transmission delays and cross-traffic volume. These specific parameters provide sufficient information for precise bandwidth estimation while maintaining ease of operation, as the measurements are obtained from normal packet transmission without requiring complex network modifications.
Data Source
AI summary
A method, program and apparatus for estimating a bandwidth of a channel from a transmitter to a receiver. The method comprises: receiving a packet stream at the receiver from the transmitter; receiving from the transmitter an indication of data transmitted from the transmitter to one or more other recipients than said receiver between packets of said packet stream; and determining at the receiver, using said indication, an estimate of the bandwidth of said channel. The estimate may enable transmission of packets from the transmitter to be controlled.