QoS Server Bandwidth Measurement for A/V Stream Latency
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Solution Overview
Problem
In networks carrying audio-visual (A/V) streams, existing Quality of Service (QoS) management techniques often result in delays or glitches due to bandwidth allocation challenges, particularly in environments with limited bandwidth, where direct or indirect methods like buffering or prioritization can lead to user-perceptible delays or decreased signal quality.
Innovation Solution
A server measures available bandwidth before transmitting A/V streams, allowing for immediate start of data transmission with optimized parameters, using cached measurements or low priority settings if necessary, to minimize latency and interference with other network traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If buffering is used to manage QoS in A/V streams, then transmission quality is improved by handling delayed packets, but user-perceptible delays of five seconds or more occur which exceed user expectations
Solution Approach 1:
The patent measures available bandwidth before the A/V stream transmission begins, allowing the system to proactively configure transmission parameters and allocate bandwidth reserves in advance. This preliminary bandwidth measurement and allocation eliminates the need for lengthy buffering delays by preparing the network path beforehand, enabling immediate stream startup without compromising transmission quality.
2Reliability
If A/V data streams are transmitted with high bandwidth allocation, then user experience is improved, but network bandwidth is consumed excessively causing other data streams to be affected
Solution Approach 1:
The patent dynamically adjusts transmission parameters of A/V streams based on measured available bandwidth. When bandwidth is sufficient, higher quality transmission parameters are used; when bandwidth is limited, the system automatically lowers transmission parameters such as resolution or bitrate. This adaptive parameter adjustment ensures optimal A/V stream quality while preventing excessive bandwidth consumption that would harm other network traffic.
3Measurement precision
If bandwidth measurement is performed before stream transmission, then accurate bandwidth allocation is achieved, but transmission delay occurs reducing user experience
Solution Approach 1:
The system performs bandwidth measurement and reserves bandwidth in advance when the sink device associates with the server, before the user initiates stream playback. This preliminary bandwidth reservation ensures accurate bandwidth allocation is completed beforehand, so when the user requests stream playback, the stream can start immediately using the pre-configured parameters without experiencing measurement-induced delays.
Solution Approach 2:
The patent caches the results of bandwidth measurements for reuse. Once bandwidth is measured and transmission parameters are determined, these parameters are stored and can be quickly reused for subsequent stream transmissions on the same network path, avoiding repeated bandwidth measurement delays while maintaining accurate bandwidth allocation.
Data Source
AI summary
An access control mechanism in a network connecting one or more sink devices to a server providing audio/visual data (A/V) in streams. As a sink device requests access, the server measures available bandwidth to the sink device. If the measurement of available bandwidth is completed before the sink device requests a stream of audio/visual data, the measured available bandwidth is used to set transmission parameters of the data stream in accordance with a Quality of Service (QoS) policy. If the measurement is not completed when the data stream is requested, the data stream is nonetheless transmitted. In this scenario, the data stream may be transmitted using parameters computed using a cached measurement of the available bandwidth to the sink device. If no cached measurement is available, the data stream is transmitted with a low priority until a measurement can be made. Once the measurement is available, the transmission parameters of the data stream are re-set. With this access control mechanism, A/V streams may be provided with low latency but with transmission parameters accurately set in accordance with the QoS policy.