Uplink Demodulation Using Historical Frequency Offset
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Solution Overview
Problem
In the LTE system, reducing the TTI to 0.5 milliseconds for faster data transmission introduces challenges in accurate frequency offset estimation and calibration due to the absence of a DM-RS symbol, leading to increased reference signal overhead and reduced data transmission efficiency.
Innovation Solution
The method involves selecting a reduced MCS index for the terminal device, using a historical frequency offset value for calibration, and omitting the need for an additional DM-RS symbol, thereby reducing resource occupation and enhancing data transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a DM-RS symbol is added to the 0.5-millisecond TTI to enable accurate frequency offset estimation, then frequency offset estimation accuracy is improved, but reference signal overhead increases and data transmission capacity is reduced
Solution Approach 1:
The patent performs frequency offset estimation in advance using DM-RS from a previous 1ms TTI, storing the estimated value for later use. This preliminary action eliminates the need to add extra DM-RS symbols in the shortened 0.5ms TTI, thereby maintaining frequency offset estimation accuracy while reducing reference signal overhead and preserving data transmission capacity.
2Loss of time
If the TTI is reduced to 0.5 milliseconds to decrease transmission delay, then data transmission speed is improved, but the ability to perform accurate frequency offset estimation is worsened due to insufficient DM-RS symbols
Solution Approach 1:
The patent performs frequency offset estimation in advance during a 1ms TTI when sufficient DM-RS symbols are available, stores the estimated value, and reuses it in subsequent 0.5ms TTIs. This preliminary action enables the system to achieve both reduced transmission delay and maintained frequency offset estimation accuracy by decoupling the estimation process from the data transmission interval.
3Productivity
If the TTI is reduced to 0.5 milliseconds to increase productivity, then data transmission efficiency is improved, but reference signal overhead increases when additional DM-RS symbols are added
Solution Approach 1:
The patent performs frequency offset estimation in advance during a 1ms TTI and stores the result for reuse in 0.5ms TTIs. This approach maintains high data transmission efficiency by using shortened TTIs while avoiding the need to add extra DM-RS symbols in each 0.5ms TTI, thereby preventing reference signal overhead from increasing and preserving data transmission capacity.
Data Source
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AI summary
Embodiments of the present invention provide an uplink information demodulation method, an apparatus, and an uplink information demodulation system, and relate to the field of communications technologies. After an MCS index is selected for a terminal device, reduction processing is performed on the MCS index according to a preset MCS index reduction exponent, a reduced MCS index is indicated to the terminal device, frequency offset estimation is performed on the terminal device by using a recorded historical frequency offset value, and a PUSCH sent by the terminal device according to the reduced MCS index is demodulated after the frequency offset estimation. A frequency offset value is determined by using the prerecorded historical frequency offset value, so that the frequency offset value does not need to be determined in an existing manner of adding a DM-RS symbol to a 0.5-millisecond TTI. Therefore, fewer resources are occupied, data transmission efficiency is improved, and reference signal system overheads are reduced.