H.320 Gateway Protocol Translation for Video Flow Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Interworking between H.323 IP video terminals and H.320 PSTN video terminals results in loss of capabilities and bandwidth disruptions due to limitations in ITU specifications H.245 and H.221/H.242, leading to incomplete video stream transmission and potential overflow during bandwidth reduction.
Innovation Solution
Implementing gateway devices that translate and map signaling messages and flow control messages between H.323 and H.320 protocols using non-standard commands, such as hexadecimal bytes 0×FE and 0×FF, to ensure seamless communication and bandwidth management across IP and TDM networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If H.263 capabilities are passed transparently between H.323 terminals, then video communication quality is improved, but capability loss occurs when traversing H.320 PSTN networks
Solution Approach 1:
The gateway acts as an intermediary device between H.323 IP networks and H.320 PSTN networks. It translates H.245 capability messages from H.323 terminals into H.221/H.242 compatible messages, preserving H.263 capabilities including Standard MPI and Pixel Aspect Ratio Code fields that would otherwise be lost in translation. The gateway maintains capability information through the protocol conversion process.
2Reliability
If maximum bandwidth is allocated for video calls between H.323 terminals, then video stream quality is improved, but bandwidth overflow and disruptions occur when H.320 legs are involved
Solution Approach 1:
The system implements flow control feedback mechanisms where H.323 terminals send flow control messages indicating their bandwidth requirements. The gateway translates these messages into H.221/H.242 compatible format and forwards them to H.320 networks. This feedback loop allows dynamic bandwidth adjustment, preventing overflow conditions while maintaining optimal video quality.
Solution Approach 2:
The bandwidth allocation is made dynamic rather than static. Flow control messages enable real-time adjustment of bandwidth allocation based on actual network conditions and terminal requirements. The system can adapt bandwidth allocation during the call, reducing it when necessary to prevent overflow while maintaining quality when resources are available.
Data Source
AI summary
In one embodiment, a system includes first and second gateway devices operable to communicate with respective first and second video terminals in accordance with H.323, the first and second gateway devices also being operable to communicate with each other over an H.320 call leg. Responsive to a first message received from the first video terminal that contains a terminal capability in H.245, the first gateway mapping the terminal capability into a non-standard section of an H.221 data stream, and send the data stream to the second gateway device. The second gateway device decoding the terminal capability from the non-standard section, encoding the terminal capability in H.245 in a second message, and sending the second message to the second video terminal. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure.