Physical Cell Identity Collision Resolution in Disaggregated gNB Mobility
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Solution Overview
Problem
Conventional mobility management in wireless networks, particularly in disaggregated gNB architectures, is inefficient due to the need for centralized units to handle both intra-DU and inter-DU mobility events, leading to increased computational burden and latency, especially in distributed cloud deployments.
Innovation Solution
Implementing a bi-layered mobility approach where intra-DU mobility events are managed by distributed units, while inter-DU events are handled by the centralized unit, using a mapping between physical cell group identifiers (CU-PCIG) and distributed unit physical cell identities (DU-PCI) to determine the appropriate handling entity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the centralized unit handles both intra-DU and inter-DU mobility events, then mobility management is unified and simple to implement, but the computational burden and latency increase significantly
Solution Approach 1:
The mobility management function is segmented into two independent parts: intra-DU mobility events are handled by the distributed unit locally, while inter-DU mobility events are handled by the centralized unit. This segmentation eliminates the need for the centralized unit to process all mobility events, thereby reducing computational burden and latency for intra-DU events while maintaining unified management architecture.
2Extent of automation
If the centralized unit processes all mobility events, then centralized control is maintained, but latency increases especially in distributed cloud deployments
Solution Approach 1:
The intra-DU mobility event handling function is extracted from the centralized unit and assigned to the distributed unit. This extraction allows local decision-making for intra-DU events, eliminating the time delay associated with centralized processing while the centralized unit retains control over inter-DU events, thus maintaining balanced centralized control.
3Loss of time
If all mobility events are handled at the distributed unit level, then latency is reduced, but the distributed unit's computational load increases
Solution Approach 1:
The system applies different handling qualities to different mobility events: intra-DU events are handled locally at the distributed unit with fast response, while inter-DU events are forwarded to the centralized unit. This local quality approach allows the distributed unit to handle only relevant events locally, reducing overall computational load while maintaining low latency for intra-DU events.
Data Source
AI summary
A method includes receiving via a serving cell that is associated with a first distributed unit of the network node, a list of conflicting physical cell identities and a request to provide an indication of whether a measured cell is intra-distributed unit or inter-distributed unit with respect to the serving cell; determining a physical cell group identifier of the serving cell; determining, by the user equipment, a physical cell group identifier of the measured cell; comparing the physical cell group identifier of the measured cell to the physical cell group identifier of the serving cell, to determine whether: the measured cell is intra-distributed unit with respect to the serving cell, or the measured cell is inter-distributed unit with respect to the serving cell; and sending a layer 1 measurement report including information indicating whether the measured cell is intra-distributed unit or inter-distributed unit with respect to the serving cell.