Timing Advance Command Application in Wireless Enhanced Coverage
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Solution Overview
Problem
Conventional approaches to applying Timing Advance Commands (TACs) in wireless communication devices operating in Enhanced Coverage mode can lead to degraded network node reception performance due to linear phase changes in uplink transmit timing, causing distortion in channel estimates and decoding performance.
Innovation Solution
A new rule for applying TACs in wireless communication devices, where the time difference between TAC application and reception is greater than or equal to a specified time, and TAC application does not occur during ongoing uplink transmission repetitions, ensuring timely alignment of uplink signals and minimizing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If TAC is applied immediately after reception to adjust uplink transmit timing, then timing alignment is achieved quickly, but the reception performance of the network node degrades due to linear phase change corrupting accumulated reference signals
Solution Approach 1:
The patent applies preliminary action by checking whether an uplink transmission is currently ongoing before applying the TAC. The device determines the timing of the TAC application based on the transmission timing information, and only applies the TAC when no uplink transmission is active. This prevents the linear phase change from corrupting the accumulated reference signals during coherent averaging, thereby maintaining reception performance while still achieving timely timing alignment.
2Reliability
If TAC application is delayed to avoid disturbing ongoing uplink transmissions, then reception performance is maintained, but timing alignment responsiveness is reduced
Solution Approach 1:
The patent implements a dynamic TAC application mechanism where the timing of TAC application is flexibly determined based on the current transmission state. The device continuously monitors uplink transmission timing information and dynamically selects the appropriate moment to apply the TAC - immediately when no transmission is ongoing, or deferred to the next available opportunity when a transmission is active. This dynamic approach balances reception performance maintenance with timely timing alignment.
3Device complexity
If conventional TAC application rule (subframe n+6) is used, then implementation is simple, but it may cause TAC application during ongoing repetitions leading to distorted channel estimates
Solution Approach 1:
The patent employs feedback by using the transmission timing information of ongoing uplink transmissions to control TAC application. The device receives TAC from the network node, determines the current transmission state based on stored timing information, and makes a feedback-driven decision whether to apply the TAC immediately or defer it. This feedback mechanism ensures that TAC is never applied during ongoing repetitions, preventing distortion of channel estimates while maintaining reasonable implementation complexity.
Data Source
AI summary
Embodiments disclosed herein relate to a method in a wireless communication device that operates in an enhanced coverage mode, the enhanced coverage mode comprising sequential repetition of messages sent from the wireless communication device to a network node. An example method includes: receiving a Timing Advance Command TAC from the network node; and adapting a time at which the TAC is applied, wherein a time difference between the time at which the TAC is applied and a time at which the TAC is received shall be greater than or equal to a specified time depending on a type of the used Radio Access Technology, such that application of the TAC does not occur during a period after a first subframe of a repeated uplink transmission till the end of the repeated uplink transmission.