FR2 Handover Timing Advance Triggering for Late Handover Prevention
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Solution Overview
Problem
Existing handover mechanisms in FR2 networks face challenges with 'extreme too late' handovers, where the link quality between the UE and the serving cell degrades rapidly, leading to failures before the UE can send a measurement report or receive a handover command, and increasing the cell individual offset to mitigate this causes more 'too early' handovers.
Innovation Solution
A timing advance (TA)-based solution is introduced to trigger measurement reports and handover decisions, utilizing TA information to synchronize uplink transmissions and optimize handover timing, thereby avoiding extreme 'too late' handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cell individual offset is increased to mitigate 'extreme too late' handovers, then handover timing is advanced, but this causes more 'too early' handovers
Solution Approach 1:
The patent changes the parameter used for handover triggering from cell individual offset (CIO) to timing advance (TA). By using TA which directly reflects the propagation delay and distance from the serving cell, the system can accurately determine handover timing without the trade-off between too early and too late handovers. The TA value provides a direct measurement of the uplink propagation delay, enabling precise handover timing decisions.
2Ease of operation
If existing handover mechanisms are used in FR2 networks, then handover procedures are executed, but link quality degrades rapidly causing 'extreme too late' handover failures
Solution Approach 1:
The patent implements feedback by continuously monitoring the timing advance value, which provides real-time information about the UE's distance from the serving cell and uplink propagation delay. This feedback mechanism enables the system to detect when handover is needed based on actual propagation conditions rather than relying on potentially outdated signal strength measurements, thus preventing extreme too late handovers in FR2 networks.
3Reliability
If timing advance based handover triggering is implemented, then uplink transmissions are synchronized and handover timing is optimized, but additional measurement and calculation requirements are introduced
Solution Approach 1:
The patent leverages the timing advance mechanism that already exists in the system for uplink synchronization purposes. Since TA is already being calculated and maintained by the network for synchronization, the invention reuses this existing parameter for handover triggering without requiring additional measurements or complex calculations. The TA value is already available in the system, eliminating the need for separate measurement infrastructure.
Data Source
AI summary
An apparatus includes at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to: establish a connection with a source cell; determine a first timing advance that indicates a propagation delay of uplink transmission to the source cell; determine a second timing advance that indicates a propagation delay of uplink transmission to a target cell; determine whether to initiate a handover procedure to the target cell, based at least on the first timing advance; and synchronize to the target cell during the handover procedure.