Soft Switch Local Loop for TDM Voice Streams

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Solution Overview

Problem

In Next Generation Networks (NGN), the existing soft switch call control methods using the H.248 protocol require creating two contexts for media stream conversions between users under the same media gateway, leading to resource wastage in media gateways and packet switching networks due to unnecessary digital signal processing and IP loop of RTP streams.

Innovation Solution

A method for soft switch call control that optimizes the H.248 protocol by allowing a local loop with call control of two TDM terminations under the same gateway, where the soft switch device creates a context with semi-permanent physical terminations for both parties, reducing the need for ephemeral terminations and minimizing resource usage by implementing a local loop of TDM voice streams, thereby reducing digital signal processing and IP loop of RTP streams.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the standard H.248 protocol is used to control media gateway for call establishment between two users under the same gateway, then the call can be established with proper media stream conversion, but two contexts must be created which causes resource wastage in media gateway and packet switching network

Engineering Contradiction:

Improvecall establishment reliabilityVSAvoidsystem resource usage

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent merges the call control for two users under the same media gateway into a single context instead of creating separate contexts for each user. The soft switch device identifies that both users are served by the same media gateway and consolidates their terminations into one shared context, thereby reducing resource overhead while maintaining call establishment reliability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the context structure universal by enabling a single context to serve multiple users under the same media gateway. The context is designed to accommodate multiple terminations from different users, allowing it to perform multiple functions simultaneously rather than being dedicated to a single user pair

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Manufacturing precision

If two contexts are created for media stream conversion between users under the same media gateway, then proper TDM to RTP conversion can be performed, but unnecessary digital signal processing and IP loop of RTP streams occur leading to resource wastage

Engineering Contradiction:

Improvemedia stream conversion accuracyVSAvoidcontext management complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple terminations into a single context when they share the same media gateway, reducing context management complexity. The media stream conversion process is simplified by eliminating redundant conversion steps that would occur with separate contexts, while still maintaining accurate TDM to RTP conversion through proper termination configuration

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Instead of converting TDM to RTP for each user pair separately through multiple contexts, the patent inverts the approach by maintaining TDM streams locally within the media gateway when possible and only converting to RTP when necessary for packet network transmission. This eliminates unnecessary IP looping of RTP streams by keeping local traffic in TDM domain

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If the existing soft switch call control method is used, then call control functions are provided for users under different gateways, but resource wastage occurs when users under the same gateway communicate

Engineering Contradiction:

Improvecall control adaptabilityVSAvoidsystem efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent introduces dynamic context management where the soft switch device adapts the context creation strategy based on the specific scenario. When users are under the same media gateway, the system dynamically consolidates them into a single context; when users are under different gateways, separate contexts are created. This dynamic adaptation maintains versatility while improving efficiency for local communications

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The media gateway is enabled to perform self-service by handling local media stream conversions within the same gateway without requiring external packet network routing. The soft switch device leverages the media gateway's inherent capabilities to process local traffic efficiently, reducing the burden on the packet switching network and improving overall system productivity

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS7656863B2Method for soft switch call control and soft switch device using the same

Publication Date: 2010.02.02 ALCATEL

AI summary

A method for soft switch call control and a soft switch device therefore are provided. The soft switch device acquires an initial address message (IAM) at a calling side, analyzes information of the calling party and the called party based on the acquired initial address message (IAM), and informs the media gateways to create a context and to add TDM semi-permanent physical terminations of time slots corresponding to the calling party and the called party into the context when the calling party and the called party are controlled by the same media gateway. Thus, it can implement a local loop of TDM voice, reduce IP loop of RTP streams and efficiently reduces network resources such as steps for digital signal processing, echo elimination and etc.