Mobile Station PDCP-SN Adaptation for Base Station Reconnection
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Solution Overview
Problem
Communications cannot be continued when a mobile station UE with a radio base station S-eNB supporting extended PDCP-SN reconnects with a radio base station T-eNB not supporting extended PDCP-SN, due to HFN mismatch issues.
Innovation Solution
The mobile station UE detects radio link failures and resets the extended sequence number and COUNT value, then establishes a bearer using conventional PDCP-SN by performing a reconnection procedure with a radio base station T-eNB that only supports regular sequence numbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extended PDCP-SN is used to avoid HFN mismatch, then the possibility of HFN mismatch is reduced, but communication compatibility with base stations not supporting extended PDCP-SN is lost
Solution Approach 1:
The patent implements dynamic switching between extended PDCP-SN and regular PDCP-SN based on reconnection scenarios. The mobile station detects whether it is reconnecting to the same base station or a different one, and adapts the PDCP-SN format accordingly. This dynamic adaptation resolves the contradiction by allowing extended PDCP-SN to be used when compatible (improving reliability) while falling back to regular PDCP-SN when reconnecting to incompatible base stations (maintaining adaptability).
Solution Approach 2:
The patent changes the PDCP-SN parameter format based on the reconnection context. When reconnecting to a base station that does not support extended PDCP-SN, the mobile station resets and switches to using regular PDCP-SN format. This parameter change enables compatibility with older base stations while maintaining the ability to use extended PDCP-SN when available, thus resolving the contradiction between reliability improvement and adaptability maintenance.
2Productivity
If a large amount of PDCP-PDUs are multiplexed on one RLC-PDU to increase transmission efficiency, then productivity is improved, but the possibility of HFN mismatch occurrence increases
Solution Approach 1:
The patent performs preliminary actions by resetting the extended PDCP-SN and COUNT value before reconnection to a base station not supporting extended PDCP-SN. This preliminary reset prevents HFN mismatch from occurring in the first place, allowing the system to safely multiplex large amounts of PDCP-PDUs without worrying about mismatch risks, thus resolving the contradiction between transmission efficiency and reliability.
3Speed
If extended PDCP-SN is implemented to handle high transmission rates, then the system can handle higher data rates, but device complexity increases
Solution Approach 1:
The patent implements dynamic management of PDCP-SN format, switching between extended and regular formats based on operational context. This dynamic approach allows the system to use extended PDCP-SN only when high transmission rates are required and the base station supports it, while using regular PDCP-SN in other scenarios. This reduces the average device complexity while maintaining the capability to handle high transmission rates when needed.
Data Source
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AI summary
In a state where a mobile station UE is communicating with a radio base station S-eNB supporting "extended PDCP-SN, " the mobile terminal continues communications even if it performs a reconnection procedure with a radio base station T-eNB not supporting "extended PDCP-SN. " A mobile communication method according to the invention includes the steps of, when detecting RLF in the bearer in the above-described state, the mobile station UE resetting setting of "extended PDCP-SN" and establishing a bearer using "conventional PDCP-SN" by performing a reconnection procedure with a radio base station T-eNB not supporting "extended PDCP-SN."