Candidate Cell List Management for Handover Optimization
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Solution Overview
Problem
Conventional network-controlled handover mechanisms in communication systems, particularly in 3GPP and NR technologies, face high failure rates due to degraded quality of service, leading to too early, too late, or wrong cell handovers, especially in high-frequency deployments, which can result in ping-pong effects and increased signaling overhead.
Innovation Solution
Implementing a method where user equipment (UE) receives a list of prepared candidate cells from a source cell and transmits this list to a target cell during or after handover, allowing for autonomous or conditional handovers based on network-configured conditions, and enabling the target cell to manage and modify the list to optimize handover decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional network-controlled handover is used, then the network can manage handover decisions, but handover failure rate increases due to degraded quality of service and timing issues
Solution Approach 1:
The network prepares multiple candidate cells in advance and provides them to the UE before handover is needed. The UE stores these candidate cell configurations and can autonomously execute handover to any of them when conditions are met, eliminating the need for real-time network decision-making during handover execution.
Solution Approach 2:
The UE is empowered to autonomously select and execute handover to a suitable candidate cell based on pre-configured conditions and measurements, without requiring continuous network control or real-time commands. This self-service capability reduces dependency on network responsiveness and improves handover reliability under degraded conditions.
2Speed
If autonomous handover is implemented, then handover speed improves, but handover accuracy deteriorates leading to wrong cell selection
Solution Approach 1:
The network performs preliminary evaluation and preparation of multiple candidate cells before providing them to the UE. This pre-screening ensures that only suitable cells are included in the candidate list, guiding the UE's autonomous selection toward accurate targets while maintaining fast execution.
Solution Approach 2:
The list of prepared candidate cells acts as an intermediary between the network's comprehensive cell evaluation capabilities and the UE's autonomous selection capability. It provides the UE with pre-filtered, suitable options, enabling accurate cell selection without requiring the UE to perform complex evaluations itself.
3Adaptability or versatility
If multiple candidate cells are prepared, then handover flexibility increases, but signaling overhead increases
Solution Approach 1:
The network prepares and provides the candidate cell list to the UE in advance, consolidating the signaling exchange into a single preparatory phase. This eliminates the need for repeated signaling during handover execution, as the UE can autonomously select from the pre-provided list without additional network communication.
Solution Approach 2:
The UE stores copies of candidate cell configurations and identification information locally. This allows the UE to perform autonomous handover selection based on these stored copies without requiring real-time network communication, significantly reducing signaling overhead during the actual handover process.
4Speed
If UE-based mobility is used, then handover responsiveness improves, but network control capability is reduced
Solution Approach 1:
The network performs preliminary cell preparation and evaluation, providing a curated list of candidate cells to the UE. This maintains network control over the quality and suitability of handover targets while enabling the UE to respond quickly by autonomously selecting from the pre-prepared options.
Solution Approach 2:
The candidate cell list serves as an intermediary that bridges network control and UE autonomy. It provides the UE with pre-evaluated options, enabling responsive autonomous selection while maintaining network oversight of cell quality and suitability, thus balancing both control and responsiveness.
Data Source
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AI summary
Various communication systems may benefit from improved handover. For example, it may be helpful to manage a list candidate cells to which a user equipment may be handed over.A method may include receiving at a user equipment a list of prepared candidate cells from a source cell. The method may also include transmitting the list of prepared candidate cells from the user equipment to a target cell after or during handover from the source cell to the target cell.