A-Interface Resource Selection for GSM-to-IP Migration

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Solution Overview

Problem

Existing GSM networks with TDM-based A-interfaces face challenges in migrating to IP technology without utilizing existing transcoding resources effectively, leading to inefficiencies in speech quality and network load when introducing AoIP with TC in MGW feature.

Innovation Solution

A migration scenario that allows simultaneous support of both AoIP and AoTDM interfaces, determining the preferred A-interface transport type based on codec and transport type, and using control plane signaling to manage resource allocation between BSS and MSC, enabling efficient use of existing resources and optimizing network performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If AoIP with TC in MGW feature is introduced in existing GSM networks with TDM-based A-interfaces, then IP bandwidth savings and network flexibility are improved, but existing 2G transcoders and TDM lines cannot be utilized effectively, causing extra load in MGW and affecting speech quality

Engineering Contradiction:

ImproveIP-based network flexibilityVSAvoidspeech quality

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces a migration scenario with a migration indicator that acts as an intermediary mechanism between legacy TDM-based A-interfaces and new IP-based A-interfaces. The MSC server uses this indicator to determine whether to establish connections over TDM or IP networks, enabling smooth transition while maintaining compatibility with existing transcoders and preventing MGW overload.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically selects between TDM and IP transport types based on the migration indicator and current network conditions. The MSC server can adaptively choose the appropriate interface type (TDM or IP) for each call connection, allowing flexible resource utilization while maintaining speech quality and preventing network overload.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If AoIP with TC in MGW feature is introduced, then network element reduction and maintenance simplicity are improved, but existing transcoding resources cannot be utilized without causing extra load in MGW

Engineering Contradiction:

Improvenumber of network elementsVSAvoidMGW call handling capacity

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The system dynamically routes calls through either TDM or IP networks based on the migration indicator. When the indicator shows legacy TDM capability, calls are routed through existing TDM transcoders, preserving their utilization. When IP capability is indicated, calls use the streamlined AoIP path. This dynamic routing maintains MGW call handling capacity by preventing unnecessary transcoding operations in the MGW.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The BSS autonomously indicates its migration status and capability through the migration indicator, allowing the MSC server to make intelligent routing decisions without requiring complex centralized control. This self-service approach enables existing transcoders to continue serving calls independently when appropriate, reducing the burden on MGW.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If simultaneous support of both AoIP and AoTDM interfaces is implemented, then migration smoothness and resource utilization are improved, but control complexity and resource allocation management increase

Engineering Contradiction:

Improvedual interface supportVSAvoidresource allocation management

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the complexity of dual-interface management by introducing a simple migration indicator that the BSS autonomously sets based on its capability. This indicator is included in capability information messages, allowing the MSC server to make routing decisions without complex real-time negotiations. The extraction of this decision-making parameter simplifies the overall control architecture while maintaining dual-interface support.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The BSS performs preliminary action by pre-determining its migration status and capability, encoding this information in the migration indicator before any call setup occurs. This preliminary indication allows the MSC server to pre-plan resource allocation and connection routing, avoiding complex real-time decisions during call establishment and reducing control complexity.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2526735B1A method for selecting an a-interface resource in a mobile communication system

Publication Date: 2019.03.06 NOKIA SOLUTIONS & NETWORKS OY

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AI summary

A preferred A-interface resource on a first connection leg is determined (202) by a mobile switching centre server (21, 200) based on information on capabilities (201) of a base station subsystem (10, 100) and on characteristics of second connection leg of a connection. A request message (203) is transmitted to the base station subsystem (10, 100), which requests a connection according to the preferred A-interface resource. The request message is processed by the base station subsystem (10, 100) and an A-interface resource is selected (204) for the user plane connection.