OFDM Receiver Filter Center Control for Channel Estimation
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Solution Overview
Problem
Existing OFDM receiving apparatuses face challenges in maintaining estimation precision for transmission path characteristics, particularly in DVB-T.2 systems where the fixed arrangement pattern of pilot signals can lead to deteriorated signal quality and incorrect filter center positioning, resulting in suboptimal distortion correction and potential decoding failures.
Innovation Solution
The proposed receiving apparatus includes a filter center controlling portion that adjusts the position of the interpolation filter's pass band based on time direction interpolation characteristic data, ensuring optimal signal quality by dynamically controlling the filter center position using pilot signals from both P2 symbols and data symbols, even before complete decoding of the P2 frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed arrangement pattern of pilot signals is used in DVB-T.2 systems, then the device complexity is reduced, but the estimation precision for transmission path characteristics deteriorates
Solution Approach 1:
The patent implements a dynamic filter center position adjustment mechanism that adapts to varying transmission conditions. The filter center controlling portion dynamically changes the filter center position based on detected transmission path characteristics, transforming the static fixed arrangement into a dynamic adaptive system that maintains high estimation precision without increasing overall system complexity
Solution Approach 2:
The patent changes the parameter of filter center position dynamically based on transmission conditions. By adjusting the filter center position parameter according to detected transmission path characteristics, the system optimizes estimation precision for different multi-path environments while maintaining the simplicity of the fixed pilot signal arrangement
2Device complexity
If the filter center position is fixed, then the device complexity is reduced, but the signal quality deteriorates in multi-path environments with large delay spreading
Solution Approach 1:
The patent implements a feedback mechanism where the filter center controlling portion continuously detects transmission path characteristics and adjusts the filter center position accordingly. This closed-loop feedback system ensures high signal quality in varying multi-path environments by adapting to changing conditions without requiring complex open-loop control mechanisms
Solution Approach 2:
The patent performs preliminary detection of transmission path characteristics using pilot signals before processing data symbols. This preliminary action allows the system to pre-adjust the filter center position to optimal values, ensuring high signal quality from the outset without requiring complex real-time adjustment mechanisms during data processing
3Measurement precision
If pilot signals are used only after complete decoding of P2 frame, then the measurement precision is improved, but the loss of time increases
Solution Approach 1:
The patent performs transmission path characteristic estimation using pilot signals from P2 symbols before complete decoding of the P2 frame. This preliminary estimation action enables early filter center position adjustment, reducing the time loss associated with waiting for complete decoding while maintaining measurement precision through subsequent refinements using data symbols
Data Source
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AI summary
A receiving apparatus includes: a transmission path characteristics estimating section obtaining pre-interpolation transmission path characteristic data as estimate values for transmission path characteristics as characteristics of a transmission path of an OFDM signal for transmission symbols of pilot signals by using the pilot signals contained in the OFDM signal, and filtering the pre-interpolation transmission path characteristic data by using an interpolation filter, thereby obtaining transmission path characteristic data as estimate values for transmission path characteristics for transmission symbols of the OFDM signal; a distortion correcting section performing distortion correction for the OFDM signal by using the transmission path characteristic data; and a filter controlling section controlling a pass band of the interpolation filter.