Inter-RAT Capability Transfer Mechanism for Mobile Handovers
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Solution Overview
Problem
In multi-RAT environments, mobile terminals may not provide complete capability information for all supported radio access technologies during handovers, leading to potential handover failures due to incomplete information being exchanged between source and target RATs.
Innovation Solution
A mechanism is introduced to request and provide inter-RAT capability information for mobile terminals, ensuring that all relevant capability information is exchanged during handovers, even when multiple RATs are involved, using indicator bits and Routing Area Update procedures to ensure accurate handover processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source RAT node sends mobile terminal capabilities in a format expected by the target RAT node during handover, then the handover process can be completed, but capability information for other supported RATs may be lost or not transferred
Solution Approach 1:
The capability information transfer process is segmented into multiple stages: initial capability transfer in source-to-target format for handover completion, and subsequent capability transfer in original terminal format for future handovers. This segmentation allows each stage to fulfill its specific purpose without compromising overall information completeness.
Solution Approach 2:
The target RAT node proactively requests capability information for RATs other than the current target RAT before the handover is fully completed. This preliminary action ensures that capability information for future handovers is obtained in advance, preventing information loss in subsequent handover operations.
2Productivity
If capability information is transferred only in source-to-target format during handover, then the immediate handover succeeds, but future handovers to other RATs may fail due to missing capability data
Solution Approach 1:
The system performs preliminary acquisition of capability information for multiple RATs during the current handover process. By requesting and obtaining capability data for potential future target RATs in advance, the system ensures that future handovers can proceed smoothly without delays or failures due to missing information.
Solution Approach 2:
The target RAT node acts as an intermediary that receives capability information from the source RAT node and then requests additional capability information from the mobile terminal. This intermediary role allows the system to bridge the gap between immediate handover requirements and future handover needs, ensuring comprehensive capability information is available across multiple RAT transitions.
3Reliability
If the system requests and transfers capability information for multiple RATs during handover, then future handovers are more reliable, but the complexity of the handover signaling increases
Solution Approach 1:
The capability information transfer mechanism is designed to be universal and multi-functional. The same signaling procedures and message structures are used whether transferring capability information for one RAT or multiple RATs. This universality allows the system to handle multi-RAT capability transfer without proportionally increasing signaling complexity, as the existing framework accommodates extended functionality.
Data Source
AI summary
An apparatus for enabling transfer of mobile terminal inter-RAT capabilities in a multi-RAT environment from the perspective of the capability provider may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured, with the processor, to cause the apparatus to perform at least receiving an indication of a request for mobile terminal inter-RAT capability information relative to a particular RAT, acquiring the inter-RAT capability information in response to receipt of the indication of the request for inter-RAT capability information, and providing the inter-RAT capability information to a target base station.