GERAN Cell Capability Bit for PS Handover Signaling
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Solution Overview
Problem
In current 3GPP specifications, the Serving Radio Network Controller (SRNC) lacks information on whether a target GERAN cell supports Packet Switched (PS) Handover, leading to unnecessary message transfers and relocation preparations during inter-RAT PS Handover from UTRAN to GERAN, as the SRNC must attempt handover without prior knowledge of the target cell's capabilities.
Innovation Solution
Incorporating a one-bit indicator in the GERAN Cell Capacity Information Element (IE) to convey whether a neighbor GERAN cell supports PS Handover, which is included in messages like RADIO LINK SETUP RESPONSE or RADIO LINK ADDITION RESPONSE, allowing the SRNC to determine the capability of GERAN cells before initiating handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the SRNC initiates inter-RAT PS Handover without knowing the target GERAN cell capability, then the handover attempt can be made, but unnecessary message transfers and relocation preparations are performed when the target cell does not support PS Handover
Solution Approach 1:
The DRNC performs preliminary action by determining and providing PS handover capability information of neighbor GERAN cells to the SRNC before the SRNC decides to initiate handover. This allows the SRNC to make informed handover decisions and avoid unnecessary signaling when the target cell does not support PS handover.
2Loss of information
If the O&M system configures GERAN neighbor cell capability only in the DRNC, then the capability information is available, but the SRNC cannot access this information to make informed handover decisions
Solution Approach 1:
The DRNC provides feedback to the SRNC about the PS handover capability of neighbor GERAN cells through capability information elements in signaling messages. This feedback mechanism enables the SRNC to access capability information without requiring direct configuration in the SRNC, maintaining system functionality while improving decision-making capability.
3Adaptability or versatility
If the SRNC attempts PS Handover to a GERAN cell without prior capability knowledge, then the handover procedure can be initiated, but the SRNC and SGSN processing is wasted when the handover fails
Solution Approach 1:
The system performs preliminary determination of target GERAN cell capability before initiating handover procedures. The DRNC provides capability information to the SRNC in advance, allowing the SRNC to assess whether handover should be attempted, thereby avoiding wasted processing time when the target cell does not support PS handover.
Data Source
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AI summary
GERAN Cell Capability indicated in a bit of an Information Element is modified to indicate whether a neighbor GERAN cell belonging to a radio access technology (GSM) supports packet switched (PS) handover or not so that the serving radio network controller can be in possession of such information before deciding whether to attempt PS handover to the cell of the GSM network and thereby avoid unnecessary signaling in case such a handover is not possible and to thereby allow the serving radio network controller to consider some other target cell or some other solution than triggering PS handover toward that GSM cell.