Uplink Timing Adjustment for Large TA in Short TTI LTE
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Solution Overview
Problem
In LTE communication systems using short Transmission Time Intervals (TTIs), terminals often lack sufficient processing time to transmit uplink signals due to large timing advances (TA), leading to potential failure in signal transmission.
Innovation Solution
A timing adjustment method where the base station determines and adjusts the moment for the terminal to transmit uplink signals based on the actual TA, allowing sufficient processing time by delaying the transmission according to a calculated time adjustment amount, ensuring the terminal can process data before transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If short TTI is used to improve transmission rate, then productivity is improved, but processing time for terminal becomes insufficient
Solution Approach 1:
The patent applies dynamics by making the timing relationship flexible rather than fixed. The base station dynamically adjusts the timing between PDCCH reception and PUSCH transmission based on the terminal's processing capability and the actual timing advance value. This allows the system to adapt the processing time to match both the short TTI requirements for high speed and the terminal's actual processing needs, resolving the contradiction between transmission rate improvement and processing time sufficiency.
2Reliability
If large TA value is used to maintain timing synchronization, then reliability is improved, but processing time for terminal decreases
Solution Approach 1:
The patent applies parameter changes by adjusting the timing relationship parameters based on the actual TA value and terminal processing capability. Instead of using a fixed timing relationship, the system modifies the timing parameters dynamically - specifically, the offset between PDCCH reception time and PUSCH transmission time is adjusted to account for large TA values. This ensures that even with large timing advances that maintain synchronization reliability, the terminal still has sufficient processing time to prepare uplink transmissions.
3Device complexity
If fixed timing relationship is used to simplify scheduling, then device complexity is reduced, but adaptability to different TA values decreases
Solution Approach 1:
The patent transforms the fixed timing relationship into a dynamic one that adapts to different TA values and terminal capabilities. The base station determines the appropriate timing offset based on the actual timing advance and terminal processing capability, then communicates this adjusted timing relationship to the terminal. This dynamic approach maintains scheduling simplicity from the terminal's perspective while providing the adaptability needed to handle varying TA values and processing capabilities across different terminals.
Data Source
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AI summary
The present disclosure provides a timing adjustment method, a base station, a terminal, and a communication system. The timing adjustment method includes: determining, by a base station, timing advance of a terminal; and adjusting, by the base station according to the TA, a moment for the terminal to transmit an uplink signal. The present disclosure adaptively adjusts the moment at which the terminal transmits the uplink signal based on the actual TA value.