OFDM Duobinary Transmission Signal Equalization
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Solution Overview
Problem
Conventional digital transmission systems face challenges in efficiently equalizing linear distortion, particularly multipath distortion, especially in multi-carrier systems, due to the limitations of adaptive equalizers and the need for cyclic prefixes, which increase overhead and reduce bandwidth efficiency.
Innovation Solution
A signal equalizing receiver processes OFDM symbols with pseudo-extensions to form overlapped compound blocks, applying circular convolution or Fourier transforms to remove linear distortion without cyclic prefixes, allowing for dynamic adjustment of pseudo-prefixes and suffixes to accommodate varying echo durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyclic prefixes are used to equalize linear distortion in OFDM systems, then signal equalization is achieved, but bandwidth efficiency is reduced and overhead increases
Solution Approach 1:
The patent extracts and removes the cyclic prefix from the OFDM signal structure, replacing it with a new equalization approach that processes the signal without requiring this overhead element. The equalization is achieved through signal processing techniques that operate on the useful signal portion only, eliminating the need for cyclic prefix transmission.
Solution Approach 2:
The patent changes the fundamental parameter of signal structure by transitioning from cyclic-prefix-based equalization to a method that uses the natural signal properties and processing. This parameter change eliminates the overhead while maintaining equalization capability through alternative signal processing mechanisms.
2Reliability
If adaptive equalizers are used to handle multipath distortion, then signal quality is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces complex adaptive equalizers with a simpler, fixed processing approach that achieves comparable signal quality. The new method uses predetermined processing steps rather than complex adaptive algorithms, reducing computational complexity while maintaining equalization effectiveness for multipath distortion.
3Reliability
If cyclic prefixes are added to OFDM symbols, then linear distortion equalization is achieved, but power consumption increases
Solution Approach 1:
The patent extracts and eliminates the cyclic prefix component from the transmission signal, thereby removing the associated power consumption. The equalization function is achieved through alternative processing that operates on the condensed signal without requiring the additional energy expenditure of transmitting and processing cyclic prefixes.
4Reliability
If conventional equalization methods are used in multi-carrier systems, then signal processing is achieved, but overhead increases and battery life is reduced
Solution Approach 1:
The patent changes the fundamental operating parameters of the equalization process by eliminating cyclic prefix transmission and using alternative signal processing techniques. This parameter change reduces the total energy consumption per transmitted symbol, thereby extending battery life in mobile devices while maintaining signal processing capability.
Data Source
AI summary
A method of modulating a series of input digital symbols of a first modulation scheme is provided. The method is implemented by a transmitter and includes receiving a sequential series of samples of the digital symbols in a first domain of the first modulation scheme. The first domain is one of the time domain and the frequency domain. The method further includes determining a dual of the first modulation scheme. The dual has a second modulation scheme in a second domain that is different from the first domain the second domain is the other of the time domain and the frequency domain. The method further includes applying a 90 degree rotational operation to the second modulation scheme to generate a rotational modulation format, modulating the series of digital symbols with the generated rotational modulation format, and outputting the modulated series of digital symbols to a receiver.