L1/L2 Mobility Candidate Cell Configuration with Delta Signaling
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Solution Overview
Problem
In 5G New Radio (NR) networks, existing conditional handover and candidate cell configuration procedures require frequent reconfiguration of candidate cells, leading to increased signaling overhead and inefficiency due to the smaller coverage and denser deployment of millimeter wave frequency bands, which limits seamless handovers between cells.
Innovation Solution
Implementing a method for L1/L2-based mobility with optimized signaling using a common base configuration and replaceable delta configurations for candidate cells, allowing devices to switch between cells without additional RRC reconfiguration messages, thereby reducing signaling overhead and enhancing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing conditional handover procedures are used with frequent cell switching in FR2, then mobility performance is improved, but signaling overhead increases due to repeated candidate cell reconfiguration
Solution Approach 1:
The candidate cell configuration is segmented into two parts: a common base configuration that remains valid across multiple cell switches, and cell-specific delta configurations that contain only the varying parameters. This segmentation allows the UE to reuse the base configuration without reconfiguration signaling, reducing overhead while maintaining accurate cell-specific settings for each candidate cell.
Solution Approach 2:
The network pre-configures multiple candidate cells with their respective delta configurations relative to a common base configuration before handover execution. This preliminary configuration enables the UE to rapidly switch between candidate cells using only lightweight delta updates, avoiding the need for complete reconfiguration signaling during frequent cell switches in FR2 networks.
2Manufacturing precision
If complete candidate cell configurations are reconfigured for each cell switch, then configuration accuracy is improved, but handover efficiency deteriorates due to additional RRC reconfiguration messages
Solution Approach 1:
The invention extracts only the cell-specific varying parameters from the complete candidate cell configuration, separating them from the common base configuration. This extraction creates compact delta configurations that maintain configuration accuracy for cell-specific settings while eliminating redundant common parameters that would otherwise require retransmission in every handover scenario.
Solution Approach 2:
Instead of reconfiguring complete cell configurations, the system changes only the necessary parameters by transmitting delta configurations that contain differences relative to the common base configuration. This parameter change approach maintains configuration accuracy where needed while dramatically reducing the amount of signaling data required for handovers.
3Device complexity
If candidate cells are released and reconfigured with existing procedures, then configuration management is simplified, but mobility performance deteriorates due to inability to maintain multiple candidate cells
Solution Approach 1:
The common base configuration serves as a universal foundation that can be reused across multiple candidate cells and across multiple handover events. This universal configuration structure allows the system to maintain multiple candidate cells simultaneously with their respective delta configurations, enabling rapid switching without the complexity of managing completely separate configurations for each cell.
Data Source
AI summary
A method of L1/L2-based mobility with signaling optimization using base (reference) configuration and replaceable (delta) configuration for candidate cells is proposed. All candidates can be configured at different levels provided by Radio Resource Control (RRC) signaling. To support L1/L2-triggered mobility (LTM), there is a common base configuration for candidates, and the candidates are modelled as replaceable configurations which are delta configurations on top of the common base configuration (instead of UE's current RRC configuration). The common and replaceable configurations are also referred to as reference configuration and candidate delta configuration. The candidate delta configuration is applied on top of the reference configuration to form a complete candidate configuration for handover.