Single-Carrier Multi-Carrier Receiver ISI Cancellation
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Solution Overview
Problem
Single-carrier/multi-carrier receivers face increased computation complexity when trying to eliminate inter-symbol interference (ISI) due to the limitations of conventional decision feedback equalizers, especially in long channels, and frequency-domain equalizers are inefficient in directly addressing this issue.
Innovation Solution
Incorporating a discrete Fourier transform unit, a frequency-domain equalizer, an inverse discrete Fourier transform unit, and an ISI cancellation unit to process signals in the frequency domain, using a minimum mean squared error equalizer and digital filters to cancel ISI, thereby reducing computational complexity and improving signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a decision feedback equalizer is used to eliminate channel effects and improve deep fading, then the deep fading issue is improved, but computation complexity is increased when the channel is long
Solution Approach 1:
The equalization process is segmented into two distinct stages: frequency-domain equalization using a frequency-domain equalizer, and time-domain equalization using a decision feedback equalizer. This segmentation allows the system to perform initial equalization in the frequency domain with lower complexity, then refine the results in the time domain, thereby reducing the overall computational burden while maintaining effective deep fading elimination.
Solution Approach 2:
The patent transitions between frequency domain and time domain representations of the signal. By performing equalization operations in the frequency domain first (using discrete Fourier transform), then converting to time domain for decision feedback equalization, the system leverages the dimensional advantage of frequency-domain processing to reduce the complexity requirements of the time-domain decision feedback equalizer.
2Device complexity
If a frequency-domain equalizer is used instead of a decision feedback equalizer to lower computation complexity, then computation complexity is reduced, but the frequency-domain equalizer cannot directly use decision feedback method and is unable to eliminate ISI efficiently
Solution Approach 1:
The frequency-domain equalizer performs preliminary equalization on the received signal before the decision feedback equalizer processes it. This preliminary action in the frequency domain reduces the complexity of subsequent time-domain processing and prepares the signal for more effective ISI cancellation by the decision feedback equalizer.
Solution Approach 2:
The decision feedback equalizer uses feedback from previously detected symbols to cancel intersymbol interference. By combining this feedback mechanism with frequency-domain equalization, the system achieves both reduced computation complexity (from frequency-domain processing) and effective ISI elimination (from time-domain feedback equalization).
Data Source
AI summary
A single-carrier/multi-carrier community receiver includes a discrete Fourier transform unit, a frequency-domain equalizer, an inverse discrete Fourier transform unit and an inter-symbol interference (ISI) cancellation unit. The discrete Fourier transform unit is utilized for executing a discrete Fourier transform upon a received signal to generate a frequency-domain signal. The frequency-domain equalizer is utilized for executing an equalization operation upon the frequency-domain signal to generate a frequency-domain equalized signal. The inverse discrete Fourier transform unit is utilized for executing an inverse discrete Fourier transform upon the frequency-domain equalized signal to generate a time-domain equalized signal. The ISI cancellation unit is utilized for executing an ISI cancellation operation upon the time-domain equalized signal to generate an ISI-cancelled signal.