Frequency Domain Multiplexed Signal Receiver Without DFT
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Solution Overview
Problem
In communication systems, the peak to average power ratio (PAPR) of transmitted signals affects communication quality, limiting the number of frequency channels that can be set, and the use of discrete Fourier transforms requires high-speed ADCs, increasing costs and complexity, especially in optical communication where frequency deviation compensation is challenging.
Innovation Solution
A method and device for receiving frequency domain multiplexed signals that decode without applying a discrete Fourier transform, using a digital signal acquisition step, branching, initial coefficient storage, equalization, and decoding, with coefficients stored as initial weights to equalize and decode signal sequences, allowing for accurate frequency deviation compensation and reduced ADC sampling frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discrete Fourier transform is applied to decode frequency domain multiplexed signals, then decoding accuracy is improved, but ADC sampling frequency requirement increases to twice the signal bandwidth
Solution Approach 1:
The patent segments the frequency domain multiplexed signal into multiple frequency channels, then processes each channel separately using band-pass filters tuned to specific frequency components. This allows the ADC to sample at a lower rate than the full signal bandwidth, as each filter processes a narrower frequency band independently, resolving the contradiction between decoding accuracy and sampling frequency requirements
Solution Approach 2:
The patent introduces band-pass filters as intermediary components between the ADC and the decoding process. These filters act as mediators that selectively extract specific frequency channels from the multiplexed signal, enabling accurate decoding of individual channels while allowing the ADC to operate at a reduced sampling frequency, thus resolving the contradiction between decoding precision and sampling rate requirements
2Productivity
If the number of frequency channels is increased in OFDM, then spectral efficiency is improved, but the peak to average power ratio increases affecting communication quality
Solution Approach 1:
The patent segments the high-rate data stream into multiple parallel lower-rate streams, each modulated onto a separate frequency channel. By processing multiple channels in parallel with reduced modulation complexity per channel, the system achieves high spectral efficiency while keeping the PAPR of each individual channel manageable, thus resolving the contradiction between spectral efficiency and communication quality
Solution Approach 2:
The patent changes the modulation parameters for different frequency channels, using different modulation schemes or rates optimized for specific channel conditions. This allows the system to maintain high overall spectral efficiency while adapting individual channel parameters to control PAPR and maintain communication quality, resolving the contradiction between productivity and reliability
3Quantity of substance
If frequency channel corresponding to DC component is used, then the number of usable frequency channels is improved, but signal characteristics deteriorate due to interference and noise
Solution Approach 1:
The patent extracts and removes the DC component frequency channel from the frequency domain multiplexed signal processing. By eliminating this problematic frequency component that suffers from interference and noise, the system maintains high signal quality in all usable channels while still achieving high spectral efficiency through the remaining frequency channels, resolving the contradiction between channel quantity and signal reliability
Data Source
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AI summary
A frequency domain multiplexed signal receiving method which decodes received signals that are multiplexed in a frequency domain, includes: a digital signal acquisition step of acquiring digital signals from the received signals that are multiplexed in the frequency domain; a branching step of branching the obtained digital signals to frequency channel numbers for the decoding; an initial coefficient storage step of storing different coefficients with low correlation as initial weights with respect to each of the branched signal sequences; an equalization step of equalizing each of the branched signal sequences using the different coefficients; and a decode step of decoding each of the equalized signal sequences.