Receiver Congestion Detection via Transmission Clock Rate
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Solution Overview
Problem
Detecting network congestion in packet-switched networks is challenging due to delayed symptoms of packet loss, which can be caused by factors other than congestion, making it difficult to accurately reduce transmission bitrate to improve performance.
Innovation Solution
A method and receiver configuration that estimate the transmission clock rate of packets using timestamps and adaptive filtering techniques, comparing it to a threshold to detect congestion, and adjusting the bitrate accordingly to mitigate congestion by requesting a reduction or increase based on available bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If packet loss rate is used to detect congestion, then congestion can be detected, but the detection is delayed and inaccurate because packet loss can be caused by factors other than congestion
Solution Approach 1:
Instead of detecting congestion through its traditional symptom (packet loss), the patent inverts the approach by detecting the cause of congestion (transmission clock rate variations) before it manifests as packet loss. The receiver measures the transmission clock rate by analyzing timestamp differences between consecutive packets, allowing early congestion detection before packets are dropped.
Solution Approach 2:
The patent performs preliminary detection of congestion by monitoring transmission clock rate before packet loss occurs. By continuously measuring the clock rate derived from packet timestamps, the system can identify congestion trends and trigger bitrate reduction proactively, preventing packet loss rather than reacting to it after the fact.
2Reliability
If transmission bitrate is reduced to alleviate congestion, then packet loss decreases, but media stream quality deteriorates
Solution Approach 1:
The patent implements dynamic bitrate adjustment based on real-time congestion detection. Rather than using a fixed bitrate or simple on/off congestion response, the system continuously monitors transmission clock rate and adjusts the bitrate proportionally to the detected congestion level, allowing smooth transitions that maintain quality while preventing packet loss.
Solution Approach 2:
The patent establishes a feedback loop where the receiver continuously measures transmission clock rate, detects congestion conditions, and sends control messages back to the transmitter to adjust bitrate. This closed-loop system allows the transmitter to adapt its encoding rate dynamically, reducing bitrate only when congestion is detected and restoring it when conditions improve, thereby maintaining optimal quality-reliability balance.
Data Source
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AI summary
The invention concerns a method for detecting congestion in a packet-switched network comprising: estimating, by a receiver, a transmission clock rate of one or more packets of a media stream received by the receiver, each packet comprising a timestamp generated based on the transmission clock rate; comparing the estimated transmission clock rate with a threshold; and detecting congestion in the network based on said comparison.