Cell Handover MAC Reset Strategy for BSR and HARQ Continuity
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Solution Overview
Problem
Existing cell handover methods in mobile communication systems cause disruptions in data transmission due to incomplete resetting of media access control (MAC) layer information, leading to service quality deterioration during handover.
Innovation Solution
A method for partial resetting of MAC layer information by canceling specific buffer status reports (BSRs) and hybrid automatic repeat request (HARQ) processes based on configuration information of source and target cell groups, ensuring continuity of data transmission by maintaining valid BSRs and HARQ processes in the target cell group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete resetting of MAC layer information is performed during cell handover, then service continuity is ensured, but data transmission interruption increases and user experience deteriorates
Solution Approach 1:
The patent segments the MAC layer information into different components: BSR information and HARQ information. Instead of completely resetting all MAC layer information, the patent selectively maintains certain components (BSR and HARQ) while resetting others, thereby reducing data transmission interruption while ensuring service continuity.
Solution Approach 2:
The patent applies partial resetting action by selectively canceling only those BSRs that are not needed in the target cell group and deleting only those HARQ processes that are not needed, rather than performing a complete reset of all MAC layer information. This partial action reduces the negative impact on data transmission continuity.
2Loss of time
If selective cancellation of BSR and deletion of HARQ processes is performed, then data transmission continuity is improved, but complexity of determining which BSRs and HARQ processes to maintain increases
Solution Approach 1:
The patent uses feedback from the handover command and configuration information comparison to automatically determine which BSRs and HARQ processes should be maintained. The terminal device receives feedback about the target cell group configuration and automatically makes determination decisions based on this feedback, reducing the perceived complexity for the user.
Solution Approach 2:
The terminal device performs self-service by autonomously comparing its current BSR and HARQ process information with the target cell group configuration and automatically determining which items to maintain and which to cancel/delete, without requiring complex external control or intervention.
3Loss of energy
If all triggered BSRs are canceled during handover, then resource wastage is reduced, but validity of BSR information in target cell group cannot be ensured
Solution Approach 1:
The patent applies local quality by treating different BSRs differently based on their relevance to the target cell group. BSRs corresponding to logical channels that exist in the target cell group are maintained with high quality (validity), while BSRs corresponding to logical channels that do not exist in the target cell group are canceled to avoid resource wastage. This localized differentiation resolves the contradiction.
Solution Approach 2:
The patent changes the status parameter of BSRs from a uniform state (all canceled) to a differentiated state (maintained or canceled) based on the existence of corresponding logical channels in the target cell group. This parameter change allows the system to maintain valid BSRs while canceling invalid ones, resolving the contradiction between resource wastage and BSR validity.
4Ease of operation
If partial resetting of MAC layer information is implemented, then user experience is improved, but complexity of the handover procedure increases
Solution Approach 1:
The patent performs preliminary action by comparing the source and target cell group configurations and determining which BSRs and HARQ processes to maintain before actually executing the handover. This preliminary determination simplifies the actual handover execution and reduces the perceived complexity for the user, while still implementing the complex selective maintenance logic.
Data Source
AI summary
Embodiments of this application provide a cell handover method and apparatus, and are applied to the communication field. The cell handover method includes a terminal device receiving a handover command from an access network device. Based on configuration information of a source cell group and configuration information of a target cell group, the method cancels a triggered first buffer status report BSR and/or deletes a data packet corresponding to a first hybrid automatic repeat request HARQ process. Then the method performs handover to the target cell group based on the handover command. In embodiments of this application, a behavior of partially resetting information at a MAC layer by the terminal device can be specified, to improve continuity of data transmission during cell handover, so as to improve user experience.