Dynamic Multicast Caching for IP TV Channel Change Latency
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Solution Overview
Problem
In IP TV broadcast networks, channel changes in existing systems result in significant video display latency due to limited bandwidth and the need for unicast transmission of reference frames, which burdens network resources and can exceed capacity, especially during peak channel change times.
Innovation Solution
A device and method that dynamically caches multicast data from channels at network elements closer to user devices, allowing for rapid channel changes by storing data on a storage medium only when requested and transmitting it via unicast from the storage medium upon subsequent requests, thereby reducing network resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If unicast transmission is used to provide reference frames for channel changes, then video display latency is reduced, but network resource consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-storing reference frames and GOP structures in buffers at the access node before they are needed. When a channel change request arrives, the system can immediately retrieve pre-buffered reference frames via unicast transmission, avoiding the need to wait for reference frames to be transmitted through the limited bandwidth multicast channel. This reduces video display latency while limiting unicast transmission to only essential reference frames rather than entire video streams.
Solution Approach 2:
The patent extracts only the critical reference frames and GOP header information from the full video stream for unicast transmission during channel changes. Instead of transmitting complete video data or waiting for full GOP structures, the system identifies and extracts minimal necessary data (reference frames) to enable decoder initialization, then transitions to multicast stream. This selective extraction reduces network resource consumption while achieving fast channel switching.
2Loss of energy
If all channels are cached at a central location distant from subscriber premises, then network resource usage is reduced, but channel change speed and reliability deteriorate
Solution Approach 1:
The patent implements local quality by distributing buffer storage capabilities to access nodes located closer to subscriber premises rather than concentrating all caching at a distant central location. Each access node maintains local buffers for reference frames and GOP structures, enabling faster local retrieval during channel changes. This distributed approach combines the benefits of reduced network resource usage (compared to universal caching) with improved channel change speed (compared to distant central caching).
3Loss of energy
If reference frames are transmitted only through multicast channel during channel changes, then network resource consumption is minimized, but video display latency increases
Solution Approach 1:
The patent segments the video data transmission into two distinct paths: multicast channel for continuous video stream delivery and unicast channel for urgent reference frame delivery during channel changes. The system identifies reference frames as a separate, critical segment that requires immediate delivery via unicast, while the main video stream continues through multicast. This segmentation allows the system to minimize overall network resource consumption by using multicast for bulk data while using unicast only for time-critical reference frames.
Data Source
AI summary
A device and a method for enabling access to data from a channel are provided. The device comprises a storage medium for storing the data from the channel as it is received at a network element and a controller. The controller enables commencing storage of at least a portion of multicast data from the channel not already stored on a storage medium as the data is received at a network element, after detecting a request to receive data from the channel. In the event of receiving a subsequent request associated with a user device to receive data from the channel, the data is transmitted from the storage medium to the user device. A controller for controlling storage of the data comprises a memory and a processor.