UL-Triggered Handover with Simultaneous Downlink Carrier Aggregation
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Solution Overview
Problem
Existing wireless communication systems face challenges in balancing uplink and downlink performance during handover processes, particularly in scenarios where uplink coverage issues trigger handover, leading to potential UL interference, poor UL throughput, and delayed carrier aggregation configuration.
Innovation Solution
A method and system for simultaneously performing uplink triggered handover and downlink carrier aggregation configuration, involving the target cell determining UL quality and configuring the source cell as a DL CA Scell, with information retention and transmission to ensure seamless integration and reduce configuration delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uplink triggered handover is performed to improve UL coverage, then UL throughput is improved, but DL CA configuration is delayed and UL interference increases
Solution Approach 1:
The patent combines the handover procedure with the DL CA Scell activation procedure into a single integrated process. The target cell determines UL quality and configures the source cell as a DL CA Scell simultaneously during handover, rather than performing these operations separately in sequence. This merging eliminates the configuration delay and reduces UL interference by establishing both handover and CA configuration in one coordinated action.
Solution Approach 2:
The target cell performs preliminary determination of UL quality and preparation of DL CA Scell configuration before completing the handover process. By assessing UL conditions and preparing CA configuration in advance, the system can execute both handover and CA setup without delay, ensuring seamless transition and maintaining both UL and DL performance.
2Device complexity
If DL quality based handover is used to maintain simple measurement, then measurement complexity is reduced, but UL coverage issues arise due to asymmetric cell edges
Solution Approach 1:
The system dynamically adapts the handover trigger mechanism based on actual network conditions. While DL quality measurements remain simple, the system now incorporates UL quality assessment and dynamically decides whether to execute handover or activate DL CA Scell based on real-time UL/DL condition evaluation. This dynamic approach maintains measurement simplicity while addressing UL coverage issues through conditional response.
Solution Approach 2:
The patent changes the decision parameters from solely DL quality-based to a combination of DL quality and UL quality parameters. The target cell assesses both DL measurement reports and UL conditions (such as UL SINR or UL throughput) to make informed handover decisions. This parameter expansion allows the system to address asymmetric cell edge issues while maintaining operational simplicity.
3Device complexity
If carrier aggregation is configured after handover to maintain simple procedure, then procedure complexity is reduced, but DL throughput is delayed
Solution Approach 1:
The patent merges the DL CA Scell configuration with the handover procedure execution. Instead of configuring CA after handover completes, the target cell determines and configures the DL CA Scell (source cell) as part of the handover process itself. This simultaneous execution eliminates the throughput delay while the integrated nature of the procedure keeps the implementation manageable.
Solution Approach 2:
The target cell performs preliminary configuration of the DL CA Scell before the handover is fully executed. By preparing and configuring the CA Scell in advance during the handover decision process, the system ensures that DL throughput can be maintained without delay once handover completes, while the configuration remains integrated into a single procedure.
Data Source
AI summary
A target cell for handover of a wireless device from a source cell to the target cell is provided. The target cell includes processing circuitry configured to: determine to configure the source cell as a downlink carrier aggregation secondary cell, DL CA SCell, for the wireless device, and cause transmission of an indication to the source cell to at least one of: temporarily retain, after the handover, at least a portion of information specific to the wireless device; and transmit the at least the portion of information specific to the wireless device to the target cell. The indication is based at least in part on the determination.