Timing Advance Acquisition for L1/L2 Inter-Cell Mobility Failures
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Solution Overview
Problem
Existing wireless networking technologies face challenges in efficiently managing timing advance acquisition during L1/2 triggered inter-cell mobility, leading to inefficiencies and potential connectivity issues during handovers.
Innovation Solution
The implementation of a user equipment apparatus and network nodes that manage timing advance acquisition by transmitting random access preambles, adjusting transmission power, and utilizing timers to handle failures and retransmissions, ensuring efficient L1/L2 triggered mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user equipment transmits random access preamble to acquire timing advance for target cell, then timing advance acquisition is enabled, but transmission failure may occur due to insufficient signal power
Solution Approach 1:
The patent dynamically adjusts the transmission power parameter of the random access preamble based on measured downlink signal quality (RSRP/RSSQ). When signal quality falls below thresholds, the UE increases transmission power to compensate for poor channel conditions, thereby improving the reliability of timing advance acquisition while adapting to varying signal power conditions.
2Reliability
If the network node sends instruction to re-transmit random access preamble, then timing advance acquisition failure is handled, but additional transmission time is required
Solution Approach 1:
The patent performs timing advance acquisition and validates random access preamble transmission success before the actual handover execution. By completing TA acquisition in advance and using the acquired TA value for uplink synchronization during handover, the system eliminates the need for post-handover random access procedures, thereby reducing handover execution time while maintaining reliability.
Solution Approach 2:
The patent enables the UE to skip the random access procedure on the target cell by utilizing the pre-acquired timing advance value. When TA is successfully obtained during the preparation phase, the UE can directly proceed with handover without performing additional random access transmissions, thus rushing through the handover process and minimizing time loss.
3Measurement precision
If the user equipment increases transmission power for random access preamble re-transmission, then signal detection reliability is improved, but energy consumption increases
Solution Approach 1:
The patent applies partial power increase rather than maximum power for random access preamble re-transmissions. The transmission power is adjusted incrementally based on the number of retransmission attempts and measured signal quality, achieving sufficient detection accuracy without consistently using excessive power, thus balancing detection reliability with energy conservation.
Solution Approach 2:
The system implements feedback mechanisms where the network node acknowledges successful random access preamble reception. Upon receiving positive feedback, the UE stops further power increases and retransmissions. This feedback-driven approach ensures transmission power is increased only as much as necessary to achieve reliable detection, preventing unnecessary energy consumption.
Data Source
AI summary
There is provided a user equipment apparatus that includes at least one processor and memory storing instructions. The instructions, when executed by the at least one processor, cause the user equipment apparatus at least to: establish a connection with a serving cell controlled by a serving network node; perform configuration for L1/L2 triggered mobility (LTM) to a target cell, the target cell controlled by one of: the serving network node or a target network node; prior to receiving a command to switch to the target cell: transmit, towards the target cell, a random access preamble for acquiring timing advance for the target cell; and receive, from the serving network node, an instruction to acquire timing advance for the target cell.