Primary Cell Handover in Carrier Aggregation Systems
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Solution Overview
Problem
The Long Term Evolution-Advanced (LTE-A) system requires improved peak rates that cannot be achieved with a single carrier of maximum 20MHz bandwidth, necessitating Carrier Aggregation (CA) for User Equipment (UE), but lacks an effective handover process for primary and secondary cells.
Innovation Solution
A method and apparatus for changing the primary cell in a carrier aggregation system, where User Equipment (UE) and base stations generate and transmit primary cell change commands, incorporating configuration information to update target primary and secondary cells, enabling handover within or across base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If Carrier Aggregation is introduced to extend bandwidth in LTE-A system, then transmission bandwidth and peak rates are improved, but handover process complexity increases due to multiple cells
Solution Approach 1:
The handover process is segmented into two independent phases: primary cell handover and secondary cell handover. The primary cell change command handles PCell configuration independently, while secondary cell changes are managed separately through dedicated commands. This segmentation allows each handover component to be processed independently, reducing overall process complexity despite multiple cells being involved.
Solution Approach 2:
Configuration information for target primary and secondary cells is pre-configured and stored in the UE before actual handover execution. The base station provides advance notification of upcoming handovers with complete configuration details, allowing the UE to prepare resource allocations and parameter settings in advance. This preliminary action eliminates the need for complex real-time decision-making during the handover execution phase.
2Productivity
If multiple cells are aggregated for UE in LTE-A, then data rates are improved, but configuration information management becomes complex
Solution Approach 1:
Configuration information is segmented into distinct categories: primary cell configuration (handled by primary cell change command) and secondary cell configuration (handled by secondary cell change command). Each configuration type follows independent management rules and update procedures, simplifying the overall configuration management process despite involving multiple cells.
Solution Approach 2:
Complete configuration information for all cells (primary and secondary) is provided to the UE in advance through RRC signaling before handover execution. The UE stores this configuration information locally and applies it automatically when handover is triggered, eliminating the need for complex real-time configuration updates during active data transmission.
Data Source
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AI summary
A cell deployment method and device for replacing PCells, used for enabling PCell replacement in a carrier aggregation system. Said method comprises: a User Equipment (UE) obtains PCell and SCell deployment information via a PCell replacement command; UE obtains target PCell and target SCell deployment information by combining the obtained PCell and SCell deployment information with saved original PCell and SCell deployment information, and hands over from the original PCell and original SCell to the target PCell and target SCell. A device used to carry out the method is also disclosed.