CSI Resource Configuration for Low-Latency Inter-DU Mobility
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Solution Overview
Problem
Current 5G wireless networks face challenges in L1/L2 mobility due to the lack of capability to configure CSI-RS resources in L1/L2 mobility candidate cells provided by neighbor DUs, leading to longer latency, increased signaling overhead, and longer interruptions during inter-cell mobility.
Innovation Solution
Implement methods for UEs to receive CSI resource configurations from a CU via a DU for L1/L2-based inter-cell mobility, enabling CSI measurements and reports on candidate cells provided by neighbor DUs, and facilitate L1/L2 mobility procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If CSI-RS resources are configured in L1/L2 mobility candidate cells provided by neighbor DUs, then mobility latency is reduced and signaling overhead is decreased, but device complexity increases due to the need for CU-DU coordination and CSI configuration management
Solution Approach 1:
The patent applies preliminary action by pre-configuring CSI-RS resources in neighbor cells before the actual mobility event occurs. The CU configures CSI measurement resources in advance, allowing the UE to perform measurements and prepare for mobility decisions ahead of time, thereby reducing latency when mobility is actually needed.
Solution Approach 2:
The CU serves as an intermediary between the serving DU and neighbor DUs, coordinating CSI-RS configuration across DUs. The CU receives CSI configuration from the serving DU, requests CSI-RS configuration from neighbor DUs, and manages the overall mobility decision process, simplifying the complexity of inter-DU coordination.
2Measurement precision
If CSI measurements are performed on candidate cells from neighbor DUs, then mobility decision accuracy is improved, but processing time and signaling overhead increase due to additional measurement and reporting requirements
Solution Approach 1:
The patent applies local quality by configuring CSI-RS resources with specific qualities and characteristics tailored to each neighbor cell's actual conditions. Each neighbor cell's CSI-RS is configured with appropriate parameters (power, periodicity, resource allocation) suited to that specific cell's characteristics, enabling accurate measurements without unnecessary processing overhead.
Solution Approach 2:
The system dynamically adjusts CSI measurement parameters based on UE capability, cell conditions, and mobility needs. The CU can modify measurement frequency, resource allocation, and reporting thresholds to optimize the balance between measurement accuracy and processing time, reducing unnecessary computational overhead.
3Duration of action of moving object
If L1/L2 mobility procedures are implemented with neighbor DUs, then mobility interruption is reduced, but signaling overhead increases due to coordination between serving DU, neighbor DU, and CU
Solution Approach 1:
The patent merges multiple functions into the CSI-RS configuration process: neighbor cell identification, CSI-RS resource allocation, measurement configuration, and mobility decision criteria are all combined into a single coordinated process managed by the CU, reducing the number of separate signaling exchanges needed.
Solution Approach 2:
The system maintains continuous CSI measurement and reporting during the mobility evaluation process. By keeping the measurement and reporting mechanisms active and continuous rather than intermittent, the system reduces overall processing time and enables smoother mobility transitions with less interruption.
Data Source
AI summary
Embodiments include methods for a user equipment (UE) configured to communicate with a radio access network (RAN) node comprising a central unit (CU) and a distributed unit (DU) via a serving cell. Such methods include receiving, from the CU via the DU, an RRCReconfiguration message that includes channel state information (CSI) resource configurations associated with at least one candidate cell for L1/L2-based inter-cell mobility. The at least one candidate cell is provided by one or more neighbor DUs. Such methods include performing CSI measurements on the at least one candidate cell according to the respective CSI resource configurations and sending, to the DU via the serving cell, one or more CSI reports based on the CSI measurements performed. Other embodiments include complementary methods for a CU, a first DU, and a second DU, as well as UEs, CUs, and DUs configured to perform such methods.