User Terminal Channel Estimation Accuracy Correction
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Solution Overview
Problem
In future radio communication systems, when a demodulation reference signal (DMRS) is mapped to the front side of a subframe, the channel estimation accuracy deteriorates on the rear side of the subframe, leading to decreased communication quality, especially in high-speed user terminals.
Innovation Solution
A user terminal is equipped with a receiver that receives a downlink signal including a data signal, a demodulation reference signal, and a correction reference signal. The channel estimator calculates channel estimation values using the DMRS, while the channel corrector calculates temporal fluctuation amounts using the correction reference signal, which are then used to correct channel estimation values and improve demodulation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a demodulation reference signal (DMRS) is mapped to the front side of a subframe, then processing time for channel estimation and signal demodulation is reduced, but channel estimation accuracy deteriorates on the rear side of the subframe
Solution Approach 1:
The patent segments the reference signal into two distinct types: demodulation reference signals (DMRS) mapped to the front side of the subframe for quick initial channel estimation, and correction reference signals (CRS) mapped to the rear side for accuracy correction. This segmentation allows the system to benefit from both early processing initiation and maintained estimation accuracy throughout the subframe.
Solution Approach 2:
The correction reference signal acts as an intermediary that bridges the gap between the front-mapped DMRS and the actual channel conditions at the rear of the subframe. The CRS provides updated channel information that corrects the initial estimation, effectively mediating between the time-saving early mapping and the accuracy requirement at later times.
2Loss of time
If a demodulation reference signal (DMRS) is mapped to the front side of a subframe, then processing time is reduced, but communication quality decreases in high-speed user terminals
Solution Approach 1:
The patent divides the reference signal functionality into two segments: DMRS for rapid initial estimation enabling fast processing, and CRS for accuracy correction ensuring reliable demodulation. This segmentation allows high-speed terminals to benefit from reduced processing time while maintaining communication quality through the corrective function of CRS.
Solution Approach 2:
The correction reference signal provides a feedback mechanism that updates the initial channel estimation obtained from DMRS. By comparing the CRS-based estimation with the DMRS-based estimation, the system can correct errors and maintain accurate channel knowledge throughout the subframe, ensuring reliable communication even for high-speed terminals.
3Device complexity
If channel estimation is performed using only front-side demodulation reference signal, then device complexity is reduced, but channel estimation accuracy deteriorates on the rear side of the subframe
Solution Approach 1:
The patent segments the channel estimation process into two stages: initial estimation using DMRS from the front side, and correction using CRS from the rear side. This segmentation adds minimal complexity compared to using only rear-side references, while significantly improving accuracy for the entire subframe by utilizing both front and rear reference signals.
Data Source
AI summary
A user terminal according to the present invention calculates a channel estimation value for each subcarrier by using a demodulation RS, calculates the time fluctuation amount of each symbol by using a correction RS mapped on a symbol following a symbol on which the modulation RS is mapped, corrects the channel estimation value for the subcarrier of a resource element on which a data signal to be demodulated is mapped, by using the time fluctuation amount of the symbol of the resource element, and calculates the channel estimation value of the resource element.