Dual Active Protocol Stack Handover Capability Reporting
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Solution Overview
Problem
Conventional wireless communication systems experience mobility interruptions during handovers between base stations, particularly in next-generation networks where simultaneous connectivity is expected, leading to inefficiencies in Dual Active Protocol Stack Handover (DAPS-HO) processes.
Innovation Solution
User Equipment (UE) selects and reports DAPS-HO capability information to the network, which includes parameters such as simultaneous reception and transmission capabilities, timing advance, and uplink power sharing, allowing the network to initiate appropriate physical layer procedures for seamless handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional handover procedures are used where UE releases link with source base station before establishing link with target base station, then device complexity is reduced, but mobility interruption increases
Solution Approach 1:
The network configures the UE with dual active protocol stack handover capabilities in advance, including multiple timing advance values and uplink power sharing parameters, so that the UE is prepared to maintain simultaneous connectivity with both source and target base stations during handover, thereby reducing mobility interruption without significantly increasing device complexity
2Productivity
If UE reports detailed DAPS-HO capability information including simultaneous reception and transmission parameters, then handover efficiency is improved, but device complexity increases
Solution Approach 1:
The UE capability reporting is segmented into distinct parameter groups including simultaneous reception capabilities, simultaneous transmission capabilities, timing advance support, and uplink power sharing parameters. This segmentation allows the network to selectively configure DAPS-HO based on specific capability subsets, improving handover efficiency while managing device complexity through modular capability indication
3Loss of time
If UE maintains simultaneous connectivity with source and target base stations during handover, then mobility interruption is reduced, but use of energy increases
Solution Approach 1:
The UE dynamically adjusts its connectivity state during DAPS-HO by maintaining simultaneous protocol stacks with both source and target base stations only when configured by the network. The UE can switch between dual connectivity and single connectivity modes based on network instructions, reducing mobility interruption when needed while managing energy consumption by not maintaining dual stacks continuously
4Reliability
If UE supports multiple timing advance values for simultaneous connectivity, then handover reliability is improved, but device complexity increases
Solution Approach 1:
The UE is configured with multiple timing advance values as a parameter set that can be selectively applied during DAPS-HO. The network instructs the UE on which timing advance value to use for each base station, allowing the UE to maintain reliable simultaneous connectivity without having to autonomously manage complex timing synchronization, thus improving handover reliability while limiting device complexity through network-controlled parameter selection
Data Source
AI summary
Aspects of the present disclosure propose solutions to a problem of mobility interruption during handover between base stations by providing a UE with mechanisms to report the UE capability for simultaneous connectivity based handover, or so-called Dual Active Protocol Stack Handover (DAPS-HO). A UE reports the DAPS-HO capability of the UE to the network and then the base station initiates physical layer procedures to carry out DAPS-HO in accordance with the DAPS-HO capability reported by the UE. Aspects of the present disclosure also provide examples of signaling that may be used by the UE for reporting DAPS-HO capability to the network and the physical layer procedures that the UE may follow in accordance with the configuration that the network provides to the UE, which should be in accordance with the UE's capability.