H.245 Signaling for Codec Negotiation in Video Telephony Gateways
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Solution Overview
Problem
Current technologies lack efficient interworking solutions for video telephony between the IMS and CS domains, leading to unnecessary transcoding and resource inefficiencies, especially when different codecs are used across these networks.
Innovation Solution
The implementation of an enhanced H.248 protocol interface between the MGCF and IM-MGW, allowing for autonomous H.223 and H.245 negotiations, ensures that the same codecs are used on both sides, thereby avoiding transcoding and optimizing the setup of telecommunications connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different codecs are used in CS and IMS networks for video telephony, then interoperability between networks is achieved, but transcoding operations are required which consume additional resources and reduce efficiency
Solution Approach 1:
The patent changes the parameter of codec selection by enabling dynamic negotiation of H.245 codec capabilities during call setup. The MGCF and IM-MGW exchange codec capability information and select a common codec through H.245 negotiation, avoiding the need for transcoding while maintaining interoperability between CS and IMS networks that use different default codecs.
2Adaptability or versatility
If transcoding operations are performed to ensure codec compatibility, then interoperability is maintained, but image and voice quality deteriorate and bandwidth is consumed
Solution Approach 1:
The patent performs preliminary codec negotiation through H.245 signaling before the actual media transmission begins. The MGCF and IM-MGW exchange Terminal Capability Set messages and negotiate common codec parameters in advance, ensuring that both ends use the same codec from the start, thereby avoiding transcoding operations that would consume bandwidth and degrade quality.
3Productivity
If autonomous H.223 and H.245 negotiations are implemented between MGCF and IM-MGW, then codec consistency is achieved, but signaling complexity increases
Solution Approach 1:
The patent leverages the existing H.245 protocol, which is already universally used in H.324 video telephony systems, to perform codec negotiation between MGCF and IM-MGW. By reusing the standard H.245 Terminal Capability Set and codec negotiation mechanisms, the patent achieves codec consistency without introducing proprietary or complex custom signaling procedures.
4Adaptability or versatility
If H.245 codec negotiation is performed in-band after bearer setup, then codec selection flexibility is maintained, but call setup time increases
Solution Approach 1:
The patent continues the H.245 codec negotiation process after bearer setup by establishing an H.245 control connection between MGCF and IM-MGW. This allows codec negotiation to proceed continuously without interrupting or restarting the call setup process, maintaining flexibility while minimizing additional setup time by seamlessly integrating negotiation into the existing H.324 protocol flow.
Data Source
AI summary
A video telecommunication connection is established via a landline telecommunications network and an IP multimedia subsystem telecommunications network using a media gateway control function of at least one Internet multimedia-media gateway device in the IP multimedia subsystem telecommunications network. An H.223 multiplex level usable for a telecommunication connection is exposed to an H.223 protocol negotiation, in carrying out an H.245 protocol negotiations for setting up the H.223 protocol negotiations connection for a telecommunication connection. A media gateway control function device is informed when the H.223 logic channels are open by H.245 signaling, thereby enabling the Internet multimedia-media gateway device of the IP multimedia subsystem telecommunications network to carry out at least part of the setup.