Multimedia Capability Negotiation via SDP Audit in MGC-MG Architecture
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Solution Overview
Problem
In existing communication architectures, media gateways (MG) and media gateway controllers (MGC) cannot perform multimedia capability negotiation due to limitations in the use of Session Description Protocol (SDP), particularly in the H.248 protocol, where SDP messages increase linearly with media descriptions and lack differentiation between actual and potential configurations.
Innovation Solution
A method is introduced to determine and obtain SDP capability negotiation mechanisms supported by MGs through an audit command with a functional package, using property parameters to indicate support levels, allowing for transmission, media, and decoding capabilities, enabling multimedia capability negotiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SDP is used in H.248 protocol for multimedia description, then media description capability is improved, but message size increases linearly and capability negotiation is not supported
Solution Approach 1:
The patent segments the SDP capability negotiation by introducing a functional package structure that divides multimedia capabilities into modular components. Each package represents a specific capability set that can be independently negotiated, preventing the linear growth of message size while maintaining comprehensive description capability.
Solution Approach 2:
The patent introduces dynamic capability negotiation mechanisms that allow the SDP message structure to adapt based on actual negotiation needs. The functional package approach enables the system to include only necessary capability descriptions rather than all possible media descriptions, making the message size dynamic rather than linearly fixed.
2Ease of operation
If H.248 master/slave mode is used between MGC and MG, then control mechanism is simplified, but multimedia capability negotiation is not enabled
Solution Approach 1:
The patent applies preliminary action by enabling the MG to proactively advertise its SDP capability support through the functional package before the actual multimedia session is established. This allows the MGC to plan and negotiate capabilities in advance, maintaining the master/slave control structure while enabling bidirectional capability information exchange.
Solution Approach 2:
The patent introduces a feedback mechanism where the MG responds to MGC's Audit commands with detailed SDP capability information. This feedback loop allows the MGC to make informed decisions about capability negotiation while maintaining control, resolving the contradiction between simplified control and enabled negotiation.
3Measurement precision
If Audit command is used to obtain SDP version support, then version negotiation is achieved, but comprehensive multimedia capability negotiation is not supported
Solution Approach 1:
The patent makes the Audit command multi-functional by extending it to carry and process comprehensive SDP capability information through the functional package. The same command structure used for version detection is now also used for negotiating transmission capabilities, media properties, and encoding/decoding types, eliminating the need for separate negotiation mechanisms.
Data Source
AI summary
Embodiments of the present invention relate to a method, an apparatus, and a system for multimedia capability negotiation. The method includes: determining, by a media gateway controller MGC and through an audit command, whether a media gateway MG supports SDP capability negotiation; and when the media gateway supports the SDP capability negotiation, obtaining, by the media gateway controller, an SDP capability negotiation mechanism supported by the media gateway. In the embodiments of the present invention, a technological gap in multimedia capability negotiation in an architecture where an MG is separated from an MGC is filled.