RAT Handover SIB Validity Filtering in UMTS
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Solution Overview
Problem
In mobile telecommunications systems, particularly UMTS, there is a challenge in determining the validity of Radio Access Technology (RAT) handover information, leading to potential handover failures when the System Information Block (SIB) validity expires, causing user equipment (UE) to reject handover attempts and resulting in inefficiencies due to the inability to prevent SIB expiration in all scenarios.
Innovation Solution
A method and apparatus for querying RAT handover data in mobile telecommunications devices, where the UE determines the validity of stored SIB16s and only transmits identifiers for those that will remain valid within a predetermined or randomly set expiry period, preventing the selection of expired SIBs during inter-RAT handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE stores SIB16 information for inter-RAT handover, then handover capability is enabled, but the SIB validity may expire leading to handover failures
Solution Approach 1:
The UE performs preliminary validation of SIB16 expiry status before transmitting identifiers to the network. This advance checking prevents expired SIBs from being selected for handover, ensuring that only valid SIBs are used in the handover process, thereby resolving the contradiction between enabling handover capability and preventing expiry-related failures
Solution Approach 2:
The network receives feedback from the UE regarding the validity status of stored SIB16 information. The UE provides information about which SIB identifiers are still valid, allowing the network to make informed decisions about handover configuration. This feedback mechanism ensures handover reliability while managing the limited validity period of SIB information
2Adaptability or versatility
If the UE transmits all stored SIB16 identifiers to the network, then handover options are maximized, but expired SIBs may be selected causing handover failures
Solution Approach 1:
The UE performs preliminary filtering of SIB16 identifiers based on their validity status before transmission to the network. By removing identifiers of expired or expiring SIBs in advance, the UE ensures that the network receives only valid options, thus maintaining handover flexibility while preventing selection of expired SIBs that would cause failures
Solution Approach 2:
The UE extracts and removes expired or invalid SIB16 identifiers from the set of stored identifiers before transmitting to the network. This extraction process separates valid from invalid options, allowing the network to work only with valid SIBs, thereby resolving the contradiction between providing multiple handover options and avoiding expired SIB selection
3Reliability
If the UE re-reads SIB16 before handover to ensure validity, then handover reliability is improved, but handover delay increases
Solution Approach 1:
The UE performs validity checking of SIB16 in advance, before the handover execution phase. By determining expiry status beforehand and communicating this information to the network, the UE avoids the need for time-consuming re-reading operations during the actual handover process, thus maintaining reliability while minimizing delay
Solution Approach 2:
The UE autonomously determines the validity status of its own stored SIB16 information using its internal clock and the stored expiry timing information. This self-service validation eliminates the need for network-assisted verification or re-reading operations during handover, reducing delay while ensuring reliability
Data Source
AI summary
A mobile telecommunications system comprises a network of a plurality of cells and at least one user equipment device operable to communicate in the system and to operate in a first RAT and a second RAT. The method comprises, in the user equipment device, determining whether the validity of data stored on the user equipment device will expire within an expiry period, the stored data being for use in handover of operation of the user equipment device from the first RAT to the second RAT.