OFDM Receiver Channel Estimation Filter Selection
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Solution Overview
Problem
Existing OFDM receiver systems face challenges in accurately determining whether the channel environment is a single path or near delay path environment, leading to insufficient precision in utilizing the guard interval (GI) for improved signal quality, which can result in signal deterioration due to erroneous channel estimation.
Innovation Solution
A receiving device and method that employs an optimum filter coefficient selection circuit to control the interpolation filter used in frequency interpolation processing, allowing for high-precision determination of the channel environment by trial usage of plural interpolation filters and selecting the actual filter based on signal quality analysis, thereby optimizing the FFT operation and GI utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single interpolation filter is used in frequency interpolation processing, then the device complexity is reduced, but the measurement precision of channel environment determination deteriorates
Solution Approach 1:
The system dynamically switches between different interpolation filters (narrowband and wideband) based on the determined channel environment. The filter selection is not fixed but adapts to the actual transmission conditions, allowing the receiver to optimize performance for either single-path or multipath environments by selecting the appropriate filter type.
Solution Approach 2:
The system changes the bandwidth parameter of the interpolation filter based on channel conditions. By selecting between narrowband and wideband filters, the system adjusts the frequency selectivity parameter to match the channel environment, thereby improving the precision of channel estimation and signal recovery.
2Reliability
If the guard interval is effectively utilized through high-precision channel environment determination, then the S/N ratio is improved, but the device complexity increases due to trial usage of multiple filters
Solution Approach 1:
The system performs preliminary trials with different interpolation filters before final signal processing. By预先 testing narrowband and wideband filters and selecting the optimal one based on signal quality metrics, the system prepares the best possible channel estimation before utilizing the guard interval, thereby maximizing S/N ratio improvement.
Solution Approach 2:
The system uses feedback from signal quality assessment to select the appropriate interpolation filter. By evaluating the performance of different filters and choosing the one that provides the best signal quality, the system creates a closed-loop control mechanism that optimizes the utilization of the guard interval for S/N ratio improvement.
Data Source
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AI summary
A receiving device comprising: a pilot signal extractor configured to extract a pilot signal from a received orthogonal frequency division multiplexing (OFDM) signal; an estimator configured to estimate a characteristic of a channel of the OFDM signal for the pilot signal and interpolate a channel characteristic in a time direction to thereby obtain a channel characteristic of every predetermined number of subcarriers; an interpolator configured to carry out filtering of the channel characteristic of every predetermined number of subcarriers by an interpolation filter having a first band for interpolating a channel characteristic in a frequency direction to thereby obtain a first all-subcarrier channel characteristic, and carry out filtering of the channel characteristic of every predetermined number of subcarriers by an interpolation filter having a second band wider than the first band for interpolating a channel characteristic in the frequency direction to thereby obtain a second all-subcarrier channel characteristic; a distortion corrector configured to correct distortion of the OFDM signal by using the first all-subcarrier channel characteristic and correct distortion of the OFDM signal by using the second all-subcarrier channel characteristic; a calculator configured to calculate quality of each of the OFDM signals whose distortion has been corrected; and a determiner configured to determine whether or not a channel environment is a single path environment or a near delay path environment in which all paths are allowed to be included in a passband of an interpolation filter having the first band, based on quality of a first distortion-corrected signal that is the OFDM signal whose distortion has been corrected by using the first all-subcarrier channel characteristic and quality of a second distortion-corrected signal that is the OFDM signal whose distortion has been corrected by using the second all-subcarrier channel characteristic.