Early Timing Advance Acquisition for Low-Latency Cell Switching
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently acquiring early timing advance (ETA) for seamless handover and mobility management, particularly in heterogeneous networks with diverse cell sizes and varying traffic conditions, leading to delays and suboptimal resource allocation.
Innovation Solution
Implementing a mechanism for early timing advance acquisition (ETA) through conditional handover (CHO) procedures and L1/L2 triggered mobility, utilizing advanced signaling and message exchanges between wireless devices and base stations to optimize timing alignment and resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional timing advance acquisition methods are used, then existing network operation is maintained, but handover efficiency is reduced and latency increases
Solution Approach 1:
The patent applies preliminary action by acquiring timing advance information early in the handover preparation phase rather than waiting for the actual handover execution. The wireless device obtains timing advance values from target base stations during the measurement and selection phase, enabling the network to pre-configured timing parameters before the handover actually occurs. This early acquisition eliminates timing-related delays during the critical handover moment, directly reducing latency while improving handover efficiency.
2Productivity
If early timing advance acquisition is implemented, then handover efficiency is improved and latency is reduced, but signaling complexity and message exchange requirements increase
Solution Approach 1:
The patent merges multiple functions into existing signaling messages. The timing advance acquisition is integrated into the random access procedure and handover preparation messages that already exist in the network. Instead of creating separate dedicated signaling channels for timing advance acquisition, the patent reuses existing message structures (such as RRC messages and random access responses) to carry timing advance information. This merging approach enables early timing advance acquisition while avoiding the complexity of additional signaling protocols.
Solution Approach 2:
The patent makes existing signaling messages multi-functional. Existing messages that originally served single purposes (such as random access responses or handover preparation) are enhanced to also carry timing advance information. This universalization allows the same message infrastructure to serve multiple functions: random access, timing alignment, and handover preparation. By making the signaling system more versatile rather than adding separate dedicated channels, the patent achieves early timing advance acquisition without proportionally increasing signaling complexity.
3Productivity
If timing advance is acquired early, then resource allocation is optimized, but measurement and detection requirements become more stringent
Solution Approach 1:
The patent employs feedback mechanisms where the wireless device measures downlink signal characteristics from candidate target base stations and reports these measurements back to the network. The network uses this feedback information to determine appropriate timing advance values. The feedback loop includes measurement of reference signals, calculation of timing differences, and communication of these measurements to the selecting base station. This feedback-based approach enables accurate timing advance acquisition while distributing the measurement burden across multiple network nodes rather than requiring single-point high-precision measurements.
Data Source
AI summary
A wireless device receives, from a base station, a radio resource control (RRC) reconfiguration message comprising a layer 1 and/or layer 2 triggered mobility (LTM) configuration of the wireless device. The LTM configuration comprises a configuration of a candidate cell for an LTM, a first identifier of the candidate cell, and a second identifier of the candidate cell for an early timing advance acquisition (ETA). The ETA comprises a user equipment (UE) based timing advance (TA) measurement. The wireless device measures a TA value of the candidate cell based on the RRC reconfiguration message comprising the second identifier. The wireless device receives an LTM cell switch command indicating the candidate cell. In response to receiving the LTM cell switch command, the wireless device transmits, via the candidate cell and based on the TA value, an uplink packet.