Distributed Base Station Mobility Using Full or Delta UE Configuration
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Solution Overview
Problem
Current mechanisms for providing configuration information in Multi-Radio Access Technology Dual Connectivity (MR-DC) scenarios do not allow certain procedures to be performed effectively, leading to incorrect or unsuccessful completion of mobility procedures between different gNB-DUs.
Innovation Solution
A method involving a central unit of a distributed base station apparatus that sends messages to a target distributed unit with configuration information and an indication of whether a full or delta type of configuration has been used, enabling correct treatment of configuration information by the master node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If delta configuration information is used to reduce signalling overhead, then message size is reduced, but configuration accuracy may be compromised when mobility procedures are not correctly handled
Solution Approach 1:
The target gNB-DU applies the configuration (full or delta) before the mobility procedure is complete, and provides an indication of the configuration type to the master node. This preliminary application allows the system to use compact delta configurations while maintaining reliability through proper tracking of configuration state.
Solution Approach 2:
The target gNB-DU provides feedback to the master node about which type of configuration (full or delta) has been applied. This feedback mechanism enables the master node to correctly interpret subsequent signalling and maintain configuration accuracy while benefiting from reduced overhead when delta configurations are used.
2Reliability
If full configuration information is always provided, then configuration accuracy is ensured, but signalling overhead and message size increase
Solution Approach 1:
Instead of always providing full configuration information, the system applies only the necessary portion (delta configuration) when the target gNB-DU already has the base configuration. This partial action approach reduces signalling overhead while maintaining sufficient accuracy for the mobility procedure.
Solution Approach 2:
The system changes the parameter of configuration completeness based on the specific mobility scenario and the state of the target gNB-DU. When appropriate, delta configurations with changed parameters are used instead of full configurations, reducing overhead while maintaining necessary accuracy.
3Productivity
If delta configuration is applied at target gNB-DU without indication to master node, then signalling efficiency improves, but master node cannot correctly treat the configuration information
Solution Approach 1:
The target gNB-DU applies the delta configuration in advance and prepares the indication of configuration type before the master node needs to process the information. This preliminary action ensures that when the master node receives the configuration information, it can immediately and correctly interpret it without additional complexity.
Solution Approach 2:
The indication of configuration type acts as an intermediary element that bridges the gap between the target gNB-DU's local configuration state and the master node's need to correctly interpret incoming signalling. This intermediary enables efficient delta configuration usage while maintaining correct configuration treatment at the master node.
Data Source
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AI summary
There is presented a method performed by a central unit of a distributed base station apparatus in a cellular communication system, as part of a change of a UE context from a source distributed unit to a target distributed unit. A first message is sent to the target distributed unit of the distributed base station apparatus. A second message is received, from the target distributed unit of the distributed base station apparatus. The second message includes configuration information for the target distributed unit which may be full or delta. A third message is sent to a further base station apparatus that contains the received configuration information for the target distributed unit and an indication of whether a full or a delta type of configuration, has been used.