DAPS Handover Timing Control for UE Switching Limits
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Solution Overview
Problem
The existing 3GPP specifications for dual-active protocol stack (DAPS) handover do not adequately account for switching times between different cells, leading to potential data loss due to insufficient receive-to-transmit and transmit-to-receive switching times, especially at cell edges or with imperfect cell phase synchronization.
Innovation Solution
Implement dynamic detection and mitigation strategies at both the UE and network level to identify and address switching constraints, including UE-based autonomous interruption and network-based scheduling adjustments, ensuring timely transitions during DAPS handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If DAPS handover is implemented with shared RF components between source and target cells, then device complexity is reduced, but receive-to-transmit and transmit-to-receive switching times become insufficient leading to data loss
Solution Approach 1:
The patent dynamically adjusts the timing of uplink and downlink transmissions based on the UE's switching capability. The network node configures different time offsets for uplink and downlink transmissions to ensure adequate switching time between source and target cells, making the system adaptive to the UE's actual switching performance rather than using fixed timing arrangements.
Solution Approach 2:
The patent changes the timing parameters of transmissions by introducing configurable time offsets between uplink and downlink transmissions. These parameter adjustments ensure that the UE has sufficient time to switch between receiving from source cell and transmitting to target cell (or vice versa), thereby preventing data loss while maintaining shared RF component architecture.
2Ease of operation
If cell phase synchronization is relaxed, then ease of operation improves, but switching time constraints cannot be met leading to data loss
Solution Approach 1:
The patent introduces configurable time offsets as adjustable parameters that compensate for phase synchronization differences between source and target cells. By dynamically adjusting these timing parameters based on actual cell phase relationships and UE switching capabilities, the system maintains reliable handover operation without requiring stringent cell phase synchronization.
3Reliability
If switching time is increased to prevent data loss, then reliability improves, but handover speed decreases
Solution Approach 1:
The patent dynamically optimizes the timing configuration based on the UE's actual switching capability and the specific handover scenario. Rather than using excessive fixed switching time that would slow all handovers, the system adjusts timing parameters adaptively to provide just enough switching time for each UE, thereby preventing data loss while maintaining fast handover performance where possible.
Data Source
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AI summary
An example method according to some of the techniques described below is performed by a device operating in a wireless network, where the device could be a UE or a network node, e.g., an NR gNB. This example method includes the step of determining (610) whether a receive-to-transmit or transmit-to-receive switching limitation of a UE can be met during a dual-active protocol stack handover for the UE from a source cell to a target cell. The method further includes the step of taking one or more mitigation actions (620) in response to said determining. Mitigation actions might include, for example, stopping a downlink reception early or starting a scheduled transmission late, in various embodiments or instances.