CU-DU Signaling for NES Conditional Handover Continuity
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Solution Overview
Problem
In wireless communications systems, the challenge of efficiently transitioning user equipments (UEs) to a network energy savings (NES) mode during conditional handover (CHO) is hindered by the lack of clear communication between central and distributed units regarding which UEs should perform the NES-related CHO, leading to increased interruptions.
Innovation Solution
The central unit (CU) and distributed unit (DU) communicate via an F1 interface to configure UEs for NES-related CHO, indicating which UEs to perform the transition to NES mode based on measurement reports and threshold values, reducing interruptions by ensuring only eligible UEs undergo the transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network entity performs handover procedure to transition UEs to a different network entity, then the service continuity is maintained, but the complexity of coordination between network entities increases
Solution Approach 1:
The network entity is segmented into a central unit (CU) and a distributed unit (DU). The CU handles high-level control and decision-making for handover, while the DU manages radio resource control signaling with UEs. This segmentation distributes the coordination complexity across separate functional units, maintaining service continuity while reducing the burden on any single entity.
2Use of energy by stationary object
If the network entity enters energy saving mode by transitioning UEs to a different network entity, then the energy consumption is reduced, but the handover coordination complexity increases
Solution Approach 1:
The CU proactively identifies UEs that are candidates for energy-saving handover based on their service patterns and network conditions. Before the actual handover is executed, the CU prepares the target network entity with necessary UE context information and coordinates the transition timing. This preliminary action allows the source entity to enter energy-saving mode smoothly while managing coordination complexity through advance planning.
3Measurement precision
If disaggregated signaling is implemented between CU and DU for NES-related CHO, then the precision of UE selection is improved, but the signaling overhead increases
Solution Approach 1:
The signaling for NES-related CHO is extracted and disaggregated into specific messages exchanged between the CU and DU. The CU sends a dedicated indication message to the DU containing the subset of UEs selected for NES-related handover. This extraction approach improves UE selection precision by providing explicit, targeted signaling rather than generic handover commands, while the overhead is managed by sending only the necessary subset information rather than complete UE lists.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. The described techniques provide for a central unit (CU) and a distributed unit (DU) to communicate information for a network energy savings (NES) related conditional handover (CHO). For example, the CU, which may configure one or more user equipments (UEs) for the CHO, may indicate which UEs are configured to the DU, which may serve the UEs via Layer-1 (L1) signaling. The CU may further indicate which of the configured UEs are to perform the NES related CHO, which may be determined according to measurement reports from the configured UEs. In some examples, the DU may trigger the NES related CHO for UEs associated with measurement reports that satisfy an NES-specific threshold value, which may support the CU and the DU transitioning to the NES mode.