CHO-DAPS Handover Coordination for Reliable UE Throughput
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Solution Overview
Problem
The inter-working of Conditional Handover (CHO) and Dual Active Protocol Stack (DAPS) features in wireless communication systems, particularly in NR and LTE, is not specified, leading to potential system failures and reduced UE throughput during handovers due to unreliable configuration synchronization between the UE and the source cell.
Innovation Solution
The source node configures the UE with conditions for applying reduced DAPS configurations, informing the source master node about the start of DAPS handover, allowing the UE to apply the target DAPS configuration only when the CHO execution condition is met, thereby maintaining full source PS throughput until the handover is completed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE applies reduced DAPS configuration immediately upon receiving CHO configuration, then the source cell can prepare for handover earlier, but the UE throughput is reduced during the handover preparation period and configuration synchronization becomes unreliable
Solution Approach 1:
The source node configures the UE with conditional handover parameters and target DAPS configuration in advance, but the UE only applies this configuration when the CHO execution condition is met. This preliminary preparation without immediate application maintains throughput while ensuring reliable configuration synchronization when handover actually occurs.
Solution Approach 2:
The patent introduces dynamic conditional execution where the DAPS configuration application is not static but depends on whether the CHO execution condition is satisfied. The UE dynamically switches from maintaining full source PS throughput to applying target configuration based on real-time condition evaluation, resolving the contradiction between early preparation and throughput maintenance.
2Productivity
If the UE maintains full source PS throughput until handover execution, then UE throughput is preserved, but the handover preparation time is extended and may delay the handover process
Solution Approach 1:
The source node performs all necessary handover preparation actions including configuring target DAPS parameters, establishing target radio resources, and preparing data forwarding paths before the UE executes the handover. This preliminary configuration of the target side allows the UE to switch quickly once the execution condition is met, minimizing actual handover time while maintaining throughput during preparation.
Solution Approach 2:
The UE continuously monitors the CHO execution condition (e.g., signal quality thresholds) and provides feedback to determine when to apply the target configuration. This feedback mechanism ensures that the UE maintains full source throughput during preparation but can quickly transition to target configuration when conditions warrant, optimizing both throughput preservation and handover timing.
3Duration of action of stationary object
If the source node configures the UE with target DAPS configuration early, then the target cell can be prepared in advance, but configuration synchronization between UE and source cell becomes unreliable
Solution Approach 1:
The source node configures the UE with target DAPS configuration parameters including radio resources, PDCP settings, and RLC configurations in advance during the CHO preparation phase. This preliminary configuration allows the target cell to be fully prepared before handover execution, ensuring smooth transition while maintaining configuration synchronization through conditional application only when CHO condition is met.
Data Source
AI summary
The example embodiments of the invention provide at least a method and apparatus to perform determining, by a network node of a communication network, information including a conditional handover configuration and a target dual active protocol stack handover configuration for a handover of user equipment in the communication network, wherein the information includes at least one triggering condition associated with the handover to be met for application of the target dual active protocol stack handover configuration for the handover; and sending toward the user equipment the information for use by the user equipment with the handover. In addition, example embodiments of the invention provide at least a method and apparatus to perform receiving, by a user equipment of a communication network, from a network node information including a conditional handover configuration and a target dual active protocol stack handover configuration for use with a handover of the user equipment in the communication network, wherein the information includes at least one triggering condition associated with the conditional handover to be met for application of the target dual active protocol stack handover configuration for the handover; and based on the information, performing operations for the handover.