Beam-Specific Timing Advance for RACH-Less UE Mobility
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Solution Overview
Problem
RACH-based random access procedures cause significant delays during UE mobility, particularly in scenarios where multiple UEs collide, leading to increased latency and inefficiencies in accessing wireless networks, which is not suitable for ultra-reliable low latency communication (URLLC) requirements.
Innovation Solution
A method where a user equipment (UE) receives beam-associated information from a source base station, including beam identifiers and default timing advances, allowing it to perform RACH-less mobility by transmitting uplink signals with pre-configured timing advances and power settings, eliminating the need for real-time random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RACH-based random access procedure is used for UE mobility, then network access is achieved, but significant delay occurs due to shared channel collisions
Solution Approach 1:
The patent applies preliminary action by pre-configuring uplink transmission parameters including timing advance values and power settings before the UE needs to access the target base station. The source base station provides the UE with beam information messages containing multiple default timing advance values corresponding to different beams, allowing the UE to immediately transmit uplink signals without performing random access procedures, thus eliminating handover delay while ensuring reliable network access.
2Productivity
If multiple UEs transmit simultaneously on shared RACH, then network access is attempted, but transmission collisions occur
Solution Approach 1:
The patent applies self-service by enabling each UE to independently determine its uplink transmission timing and power settings using pre-configured beam-specific timing advance values. The UE autonomously selects the appropriate timing advance from the provided set based on the target beam, and self-adjusts transmission power using the configured power settings, eliminating the need for collision-prone shared random access channels while ensuring transmission success.
3Loss of time
If RACH-less mobility is implemented, then handover latency is reduced, but beam-specific timing configuration complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the timing advance configuration into multiple beam-specific groups, where each beam has its own default timing advance value. Instead of providing a single timing advance for all beams, the system segments the configuration space and provides beam-specific parameters, allowing the UE to quickly select the appropriate timing advance for the target beam without complex real-time calculations, thus reducing handover latency while managing configuration complexity through structured organization.
Data Source
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AI summary
In accordance to embodiments, a user equipment (UE) may receive, from the source base station, a beam information message comprising beam associated information. The beam associated information may indicate a plurality of beam identifiers (IDs) corresponding to a plurality of beams in the target base station and a plurality of default timing advance (TA) s. Each default TA of the plurality of TAs is associated with one beam of the plurality of beams in the target base station and additional related configurations.