LTE-A Aggregated Cell Reconfiguration Without Security Key Recalculation
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Solution Overview
Problem
In LTE systems, frequent handovers due to changes in signal quality or load lead to data transmission interruptions and losses, as existing technologies require recalculating security keys and re-establishing entities like PDCP and RLC, which is not accounted for in carrier aggregation scenarios.
Innovation Solution
A method and system for reconfiguring aggregated cells in LTE-A systems by sending RRC connection reconfiguration messages to UE, allowing for changes in aggregated cells without recalculating security keys, thus enabling uninterrupted data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover is performed when UE moves to cell edge, then service continuity is maintained, but data transmission is interrupted and data may be lost due to re-establishment of PDCP, RLC, and MAC entities
Solution Approach 1:
The patent segments the handover procedure into two types: conventional handover for single-carrier UEs and carrier aggregation-specific handover for multi-carrier UEs. The latter allows data transmission to continue on remaining carriers while handover occurs on the target carrier, preventing complete data interruption.
Solution Approach 2:
The patent maintains continuous data transmission by allowing data to continue flowing on carriers that are not undergoing handover. The PDCP entity continues operating without re-establishment when handover occurs on only one carrier among multiple aggregated carriers.
2Reliability
If security keys are recalculated for each handover, then security is maintained, but data transmission interruption occurs during re-establishment of entities
Solution Approach 1:
The patent performs preliminary configuration of the target carrier before handover execution. The network device sends RRC connection reconfiguration messages in advance to add the target carrier to the aggregated cell set, so that when handover occurs, the UE is already prepared to receive and process data on the new carrier without interruption.
3Productivity
If carrier aggregation is used to provide larger bandwidth, then peak rate is improved, but the complexity of managing multiple aggregated cells increases
Solution Approach 1:
The patent creates a unified handover mechanism that works for both single-carrier and multi-carrier UEs. The same RRC connection reconfiguration message format and processing logic handle both conventional handover and carrier aggregation handover, simplifying the overall system design despite the added capability.
Data Source
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AI summary
The present invention provides a method for reconfiguring an aggregated cell, which includes that: a network side device judges whether the aggregated cell of a user equipment (UE) needs to be changed in the cell set in which the carriers can be aggregated; when the judgment result is that the change is needed, the network side device transmits a radio resource control (RRC) connection reconfiguration message to the UE, and the RRC connection reconfiguration message carries the change information of the aggregated cell of the UE; the UE receives the RRC connection reconfiguration message, and reconfigures the aggregated cell according to the RRC connection reconfiguration message. In the present invention, for the LTE-A system, when the aggregated cell of UE which supports the carrier aggregation changes within the same cell set in which the carriers can be aggregated, the aggregated cell of the UE can be reconfigured; and the same access stratum (AS) key is used to perform the security processing procedure for the data, which enables the uninterrupted transmission for the data.