Conditional Handover Configuration Management for Multi-Cell Requests
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Solution Overview
Problem
Existing conditional handover (CHO) procedures in wireless communication networks are limited to a maximum of 8 configurations per UE, with the source RAN node being unaware of existing configurations at the UE, leading to inefficient resource allocation and potential waste of resources due to unknown better radio conditions of secondary cells.
Innovation Solution
Implement mechanisms for the source node to indicate the maximum number of conditional configurations allowed for the target node, enabling controlled allocation and sequential preparation of secondary cell configurations, with unique identifiers for each configuration to manage updates and cancellations effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the target RAN node sends multiple conditional configurations for PSCells as an answer to a single CHO request, then the UE has more handover options and better radio conditions can be selected, but the number of conditional configurations exceeds the UE's processing capacity and causes resource waste
Solution Approach 1:
The patent segments the conditional configuration preparation process by introducing a multi-round request mechanism. The source node divides a single large CHO request into multiple smaller requests, each targeting specific PSCells. The target node prepares configurations in segments across different rounds, with each round focusing on a subset of PSCells. This segmentation reduces the complexity burden on the UE while still providing comprehensive handover options.
Solution Approach 2:
The patent applies preliminary action by having the source node identify and prioritize PSCells before sending CHO requests. The source node performs preliminary evaluation of radio conditions and determines which PSCells are most important to prepare. This preliminary sorting allows the target node to focus configuration preparation on the most critical cells first, reducing unnecessary configuration overhead while ensuring the best handover options are available.
2Reliability
If the source node prepares configurations for all PSCells without knowing their radio conditions, then all potential target cells are covered, but resources are wasted on preparing configurations for cells with poor radio conditions
Solution Approach 1:
The patent applies local quality by enabling the source node to perform local evaluation of radio conditions for each PSCell before including it in CHO requests. The source node assesses the radio quality of individual PSCells and assigns different priorities or includes/excludes them based on their local conditions. This localized quality assessment ensures that configuration preparation resources are concentrated on PSCells with better radio conditions, improving handover reliability while reducing waste on poor-condition cells.
3Device complexity
If the UE is limited to a maximum of 8 conditional configurations, then device complexity is reduced and processing is simplified, but the UE cannot evaluate more than 8 potential target cells for handover
Solution Approach 1:
The patent applies dynamics by making the conditional configuration set dynamic rather than static. Instead of limiting the UE to a fixed set of 8 configurations, the system dynamically updates the configuration set through multiple rounds of requests and responses. The source node can replace lower-priority configurations with higher-priority ones as new information becomes available, allowing the effective number of evaluated cells to exceed 8 while maintaining the UE's processing limit at any given time.
Data Source
AI summary
Described herein is a first network node that that controls a source cell for a user equipment, UE, in a radio access network, the first network node being a master node for carrier aggregation or dual connectivity of the UE in the radio access network, comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first network node at least to: determine a conditional handover for the UE that is served by the source cell; transmit a conditional handover request for the UE to a second network node that controls potential target cells for the UE in the radio access network, the second network node being a target master node for the carrier aggregation or dual connectivity of the UE; receive a conditional handover request acknowledgement from the second network node comprising at least one conditional configuration of target cells for the handover; and maintain a number of conditional configurations for the UE.