Timing Advance Reporting Feedback for Uplink Scheduling Accuracy
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Solution Overview
Problem
Terminal devices in mobile communication systems cannot determine whether a timing advance report (TAR) is successfully transmitted to the network side device, leading to potential scheduling delays due to assumptions based on worst-case round trip time (RTT), which affects uplink scheduling and acknowledgement feedback timing.
Innovation Solution
The terminal device determines the success of TAR transmission by receiving indication information from the network side device, such as MAC CE, PDCCH, differential Koffset MAC CE, HARQ process, RRC message, or ACK of PDCP/RCL PDUs, to confirm successful reporting and retransmit if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal device sends TAR to the network side device, then the network side device can obtain RTT information for scheduling, but the terminal device cannot determine whether the TAR is successfully received, leading to potential scheduling delays
Solution Approach 1:
The network side device sends indication information (such as HARQ ACK/NACK, MAC CE, or RRC message) to the terminal device to confirm whether the TAR is successfully received. This feedback mechanism allows the terminal device to determine transmission success and retransmit if necessary, resolving the uncertainty about TAR delivery while enabling timely scheduling decisions.
Solution Approach 2:
The terminal device waits for the indication information from the network side device before proceeding with scheduling decisions. This preliminary confirmation step ensures that the terminal device has reliable knowledge of TAR delivery status before making scheduling assumptions, preventing both premature scheduling and unnecessary delays.
2Productivity
If the network side device assumes worst-case RTT for scheduling, then scheduling can proceed without waiting for TAR confirmation, but scheduling efficiency deteriorates due to excessive time margins
Solution Approach 1:
The indication information provides real-time feedback on TAR delivery status, allowing the network side device to adjust scheduling decisions based on actual RTT information rather than always assuming worst-case scenarios. This enables more efficient resource allocation while maintaining reliability.
Solution Approach 2:
The scheduling timing is dynamically adjusted based on the received indication information. When TAR is confirmed successfully received, the network side device can use the actual RTT for scheduling; when confirmation is pending or negative, it falls back to worst-case assumptions. This dynamic adaptation optimizes scheduling efficiency while maintaining system reliability.
3Reliability
If the terminal device retransmits TAR upon not receiving confirmation, then transmission reliability improves, but device complexity increases due to retransmission management
Solution Approach 1:
The clear binary indication (success/failure) provided by the network side device simplifies the terminal device's retransmission logic. The terminal device only needs to check the indication information and retransmit based on a simple condition, rather than implementing complex retransmission algorithms, thus maintaining low device complexity while ensuring reliable delivery.
Data Source
AI summary
A method for reporting a timing advance report (TAR), performed by a terminal device, includes: sending a TAR to a network side device; and determining that sending of the TAR is successful in response to receiving indication information sent by the network side device, in which the indication information is configured to indicate that the network side device receives the TAR.