Conditional Handover Cell Selection in 5G Networks
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Solution Overview
Problem
Current wireless communication systems face challenges in efficient handover processes, particularly in 5G networks, where radio link failures can occur due to delayed measurement reports and handover commands, leading to resource-intensive recovery processes.
Innovation Solution
The implementation of a conditional handover (CHO) mechanism, where the network proactively sends a CHO command to user equipment (UE) when specific radio conditions are met, allowing the UE to select a target cell from prepared candidate cells based on factors like channel conditions, bandwidth, and discontinuous reception (DRX) configurations, ensuring a seamless handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover mechanisms are used, then the system operates with standard procedures, but radio link failures occur due to delayed measurement reports and handover commands
Solution Approach 1:
The network proactively sends a conditional handover (CHO) command to the UE in advance, before the actual handover is needed. This CHO command includes pre-configured handover conditions and multiple candidate target cells. When the UE later experiences radio link failure or meets the predetermined conditions, it can immediately execute the handover without waiting for measurement reports and handover commands, thus resolving the contradiction between handover reliability and handover delay.
2Reliability
If conditional handover with multiple candidate cells is implemented, then handover reliability improves, but device complexity increases due to DRX configuration management
Solution Approach 1:
The UE autonomously selects the most appropriate target cell from the multiple candidate cells provided in the CHO command. The selection is based on the UE's own DRX configuration requirements and the DRX configurations of the candidate cells. This self-service mechanism allows the UE to manage the complexity of multiple candidate cells independently, while the network benefits from improved handover reliability without having to centrally manage all selection decisions.
3Reliability
If proactive handover planning is implemented, then radio link failures are reduced, but signaling overhead increases due to CHO commands
Solution Approach 1:
The network sends a single CHO command in advance that contains pre-configured handover conditions and multiple candidate target cells. This preliminary action consolidates what would otherwise require multiple separate signaling exchanges (measurement reports, handover commands for each candidate cell) into one efficient signaling message. The UE stores this CHO configuration and only executes handover when predetermined conditions are met, thereby reducing radio link failures while minimizing ongoing signaling overhead.
Data Source
AI summary
Techniques to select a cell for conditional handover (CHO) are disclosed. A user equipment (UE) may receive a CHO command from a serving cell. The CHO command may include a CHO configuration, which in turn may include one or more CHO conditions and a plurality of cells. The one or more CHO conditions may specify one or more conditions, when met by any of the plurality of cells, may trigger a handover from the serving cell to a target cell. When multiple cells of the plurality of cells meet the one or more CHO conditions, the UE may select one of them as the target cell and perform the handover. The UE may consider several factors in selecting the target cell. The factors may include channel conditions, bandwidths, whether the UE is operating as a multiSIM, and cell priorities.