RACH-Based Inter-Cell Mobility for Handover Latency Reduction
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing handover procedures between cells, particularly in reducing handover latency and improving inter-cell mobility, especially in scenarios involving multiple candidate target cells and varying physical cell identifiers.
Innovation Solution
The implementation of random access channel (RACH) based inter-cell mobility techniques using physical layer (PHY) or medium access control (MAC) layer signaling, which allows user equipment (UE) to detect and initiate handover conditions, transmit random access signals on uplink resources, and complete handover procedures, thereby reducing latency and enhancing mobility management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional handover procedures are used, then handover reliability is maintained, but handover latency increases
Solution Approach 1:
The network entity pre-configures multiple candidate target PCIs and their associated uplink resources to the UE before handover is needed. When handover conditions are met, the UE can immediately use the pre-configured resources to access the target cell, eliminating the need for resource allocation negotiations during handover and thus reducing latency while maintaining reliability through pre-validated configurations
Solution Approach 2:
The system dynamically selects from multiple pre-configured candidate target PCIs based on real-time conditions. The UE monitors handover conditions for multiple candidates and can switch to different target cells depending on which conditions are first met, enabling flexible and adaptive handover that reduces latency by having multiple ready options rather than a single static target
2Adaptability or versatility
If multiple candidate target PCIs are configured, then inter-cell mobility flexibility improves, but signaling complexity increases
Solution Approach 1:
The handover configuration is segmented into multiple independent candidate target PCI entries, each with its own associated uplink resources and handover conditions. This segmentation allows the system to provide high mobility flexibility by configuring multiple targets without requiring complex inter-dependent signaling, as each candidate can be independently evaluated and selected
Solution Approach 2:
The patent uses lightweight, simple signaling structures for configuring multiple candidate targets. Each candidate PCI configuration is a self-contained, simple data structure that can be quickly processed and discarded if not selected, avoiding the need for complex persistent configurations and reducing overall signaling complexity while maintaining flexibility
Data Source
AI summary
Aspects of the present disclosure provide a method for wireless communications by a UE. The method generally includes receiving signaling configuring the UE with multiple candidate PCIs of at least one candidate target cell, receiving signaling configuring the UE with at least one HO condition for each PCI of the multiple candidate target PCIs, detecting that an HO condition is satisfied for a target PCI of one or more target PCIs selected from the multiple candidate target PCIs for HO, initiating an HO procedure to a target cell associated with the target PCI for which the HO condition is satisfied, the HO procedure involving transmitting a random access signal on an UL resource configured for the target PCI, and transmitting or receiving an HO complete message, via physical or MAC layer signaling, a handover complete message indicating completion of the HO procedure.