Differentiating DTM Handover Commands via New IEI

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Solution Overview

Problem

In dual transfer mode (DTM) handover procedures for GPRS enhanced data rates for GSM evolution (EDGE), it is challenging for the source Base Station Subsystem (BSS) to determine whether a received message element contains a DTM Handover Command or a CS-only Handover Command, especially in cases of network delays or resource unavailability, leading to potential misinterpretation and unreliable handover processes.

Innovation Solution

The method involves adding an indicator outside the message element to signal the presence of a DTM Handover Command, using an additional information element, such as the New BSS to Old BSS Information element within the BSSMAP Handover Command, to ensure the source BSS can differentiate between DTM and CS-only handover messages without altering the core network processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the existing message flow for CS Handover is used to carry DTM Handover Command, then the core network is minimally impacted, but the source BSS cannot distinguish between CS handover and DTM handover messages

Engineering Contradiction:

Improvecore network changesVSAvoidhandover type identification

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

A new information element (IE) is introduced as an intermediary carrier to transport the DTM Handover Command. This new IE includes a specific IEI that allows the source BSS to distinguish DTM handover messages from CS handover messages, while the core network simply forwards the message without examining its content, thus minimizing impact on core network nodes.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The handover command information is segmented into a new information element structure with a unique IEI identifier. This segmentation allows the source BSS to identify the message type through the IEI field, resolving the ambiguity between CS and DTM handover messages while keeping the core network processing unchanged.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If the source BSS processes handover messages without clear identification, then processing simplicity is maintained, but handover reliability deteriorates due to potential misinterpretation

Engineering Contradiction:

Improvemessage processingVSAvoidhandover execution

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The information element is assigned a unique IEI identifier that acts as a distinctive marker or 'color' for DTM handover messages. This allows the source BSS to quickly and reliably identify the message type through simple IEI comparison, maintaining processing simplicity while ensuring accurate message interpretation and reliable handover execution.

Inventive Principle:

Principle #32Color changes

3Measurement precision

If an indicator is added to the message element to identify DTM handover, then message identification accuracy is improved, but the message structure complexity increases

Engineering Contradiction:

Improvemessage identification accuracyVSAvoidmessage structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The identification function is extracted from the message content itself and placed into a separate, standardized information element header with a unique IEI. This allows the source BSS to identify the message type through the IEI field without complicating the actual handover command content, achieving accurate identification while maintaining a clean, structured message format.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8260303B2Indication of content of message element

Publication Date: 2012.09.04 HMD GLOBAL

AI summary

By providing an indicator outside a message element the content of the message element is indicated. This is particularly applicable to indication of a dual transfer mode handover command.