Carrier Aggregation Handover via Primary Secondary Carrier Swap
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Solution Overview
Problem
In cellular wireless networks, handovers between base stations often result in connectivity issues due to the need for a user equipment (UE) to switch carriers, which can disrupt Radio Resource Control (RRC) signaling and impact the success of the handover process, especially when carrier-aggregation is used.
Innovation Solution
A method where the first base station predicts a handover to an adjacent base station on a secondary carrier and reconfigures the UE's carrier-aggregation service by swapping the primary and secondary carriers, ensuring continuity of service on the secondary carrier during the handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE switches carriers during handover, then the handover can be executed, but RRC signaling continuity is disrupted and handover success rate decreases
Solution Approach 1:
The network performs preliminary actions by predicting the handover target base station in advance and pre-configuring the secondary cell group (SCG) with the target base station's cell. This allows the UE to maintain RRC signaling continuity during handover without needing to switch primary carriers, thereby resolving the contradiction between handover execution and signaling continuity.
Solution Approach 2:
The patent segments the carrier functions by separating the primary cell (PCell) from secondary cells (SCells). The PCell maintains RRC signaling while SCells provide data transmission capacity. During handover, only the PCell changes while SCells can be pre-configured, allowing handover execution without disrupting RRC signaling continuity.
2Productivity
If carrier aggregation is used to increase data rate, then throughput is improved, but handover complexity increases due to multiple carrier management
Solution Approach 1:
The patent divides carrier functions into primary cell (PCell) for control signaling and secondary cells (SCells) for data transmission. This segmentation allows handover to be managed through PCell changes while SCells can be pre-configured or maintained, reducing handover management complexity while preserving carrier aggregation throughput benefits.
Solution Approach 2:
The network predicts handover targets in advance and pre-configures secondary cells with target base station information. This preliminary action simplifies handover management by reducing the complexity of real-time multi-carrier coordination during handover, while maintaining the high throughput benefits of carrier aggregation.
Data Source
AI summary
When a first base station is serving a UE with carrier-aggregation on a combination of carriers including a first carrier as PCC of the carrier-aggregation service and a second carrier as an SCC of the carrier-aggregation service, the first base station could predict that the UE will hand over from being connected with the first base station to being connected with an adjacent second base station on the second carrier. In response to this prediction, the first base station could then reconfigure the UE's carrier aggregation service by swapping the UE's PCC and SCC so that the second carrier would become the PCC of the carrier-aggregation service and the first carrier would become an SCC of the carrier-aggregation service. This reconfiguration of the UE's carrier-aggregation service could thereby facilitate carrier continuity as the UE engages in the predicted handover.