Conditional Handover Under Network Energy Saving Cell Shutdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, conditional handover (CHO) processes fail when network energy saving (NES) is activated, leading to connection failures due to the absence of suitable cells, increased latency, and impacts on data performance and mobility robustness.
Innovation Solution
A method for wireless devices to evaluate target cells based on additional conditions indicated by the network energy saving state, allowing for efficient conditional handover and fast recovery procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the network activates energy saving mode by turning off cells, then energy consumption is reduced, but connection reliability deteriorates due to absence of suitable cells for handover
Solution Approach 1:
The network pre-configures multiple candidate target cells for conditional handover before activating energy saving mode. When a cell is turned off, the UE already has evaluated and identified suitable candidate cells, enabling immediate handover execution without connection failure. This preliminary preparation resolves the contradiction by ensuring reliability is maintained even when cells are deactivated for energy saving.
Solution Approach 2:
The invention changes the handover execution parameters by introducing conditional handover with multiple candidate cells and specific execution conditions (A3, A4, A5 events). The UE monitors candidate cells and executes handover when conditions are met, rather than relying on a single target cell. This parameter change allows the system to maintain connection reliability while enabling aggressive energy saving through cell shutdown.
2Device complexity
If the network configures single candidate target cell for conditional handover, then configuration complexity is reduced, but handover success rate deteriorates when the cell is turned off
Solution Approach 1:
The invention segments the handover target into multiple candidate cells instead of a single target. The network configures multiple candidate target cells (e.g., cell1, cell2, cell3) with individual execution conditions. This segmentation allows the UE to have multiple fallback options, ensuring that if one candidate cell is turned off, other candidates remain available for handover execution.
Solution Approach 2:
The network provides beforehand cushioning by pre-configuring multiple candidate target cells with different execution conditions. This creates a buffer against the risk of single-cell shutdown, ensuring that handover can still succeed even if some candidates are unavailable. The UE evaluates multiple candidates and can switch between them based on condition fulfillment.
3Measurement precision
If the UE waits to find a suitable cell before executing handover, then handover accuracy is improved, but latency increases during network energy saving transitions
Solution Approach 1:
The UE performs preliminary evaluation of multiple candidate target cells before the handover trigger occurs. The network provides measurement configuration for multiple candidates, and the UE continuously monitors their conditions. When the serving cell triggers handover, the UE can immediately execute to a pre-evaluated candidate without additional waiting time, thus reducing latency while maintaining selection accuracy.
Solution Approach 2:
The invention introduces dynamic conditional handover where the UE continuously evaluates multiple candidate cells based on real-time measurement conditions (A3, A4, A5 events). The handover target is not fixed but dynamically selected based on which candidate first satisfies its execution condition. This dynamic approach maintains high selection accuracy while enabling rapid handover execution.
4Reliability
If the network uses conventional handover process, then mobility robustness is maintained, but data performance deteriorates during energy saving state transitions
Solution Approach 1:
The network pre-configures multiple candidate target cells and their execution conditions before entering energy saving mode. This preliminary configuration ensures that when cells are turned off, the UE can immediately execute handover to an already-evaluated candidate without connection failure or RRC re-establishment, thus maintaining mobility robustness while preventing data performance degradation.
Solution Approach 2:
The conditional handover mechanism allows the UE to skip the conventional handover preparation and execution delays by having pre-evaluated candidates ready. When the serving cell is turned off, the UE can rapidly execute handover to a suitable candidate without the typical handover latency, thus maintaining both mobility robustness and data performance during energy saving transitions.
Data Source
AI summary
A method and apparatus for network energy saving in a wireless communication system is provided. The method comprises: receiving a configuration for a conditional mobility to a target cell, wherein the configuration includes a first condition and a second condition; evaluating whether the target cell satisfies the first condition for the conditional mobility to the target cell; determining to apply the second condition based on receiving an indication informing that the serving cell uses a network energy saving solution; and evaluating whether the target cell satisfies the second condition for the conditional mobility.