Transceiver Orthogonal Basis Generator for OFDM Spectral Leakage
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Solution Overview
Problem
Orthogonal frequency-division multiplexing (OFDM) technologies face significant challenges due to large out-of-band emission (OOBE) phenomena, which lead to interference between adjacent channels and reduce efficiency, especially when guard bands are used to mitigate these effects.
Innovation Solution
A transceiver is designed with an orthogonal basis generator that multiplies input data by a Gaussian characteristic value to generate an out-of-band emission (OOBE) value, which is then used as input to an Itô-Hermite polynomial to generate an orthogonal basis, thereby reducing OOBE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM is used to transmit multiple closely spaced orthogonal subcarrier signals, then spectral efficiency is improved, but out-of-band emission (OOBE) increases causing interference between adjacent channels
Solution Approach 1:
The patent applies preliminary action by generating an orthogonal basis before signal transmission using Itô-Hermite polynomials. This pre-processing of the basis functions ensures that the subsequent modulated signals inherently have reduced spectral leakage, preventing OOBE issues before they occur during transmission.
Solution Approach 2:
The patent changes the mathematical parameters of the basis functions by using Itô-Hermite polynomials instead of traditional orthogonal bases. This parameter change in the basis function formulation fundamentally alters the spectral characteristics of the OFDM signal, reducing out-of-band emissions while maintaining spectral efficiency.
2Object-affected harmful factors
If a guard band is used to reduce interference between adjacent channels, then OOBE influence is decreased, but frequency band utilization efficiency deteriorates
Solution Approach 1:
The patent converts the harmful spectral leakage phenomenon into a benefit by using Itô-Hermite polynomials to shape the signal spectrum. The mathematical properties of these polynomials transform the natural spectral spread of OFDM signals into a controlled form that reduces interference without requiring guard bands, thereby eliminating the trade-off between interference reduction and bandwidth utilization.
3Device complexity
If traditional orthogonal bases are used in OFDM, then implementation simplicity is maintained, but OOBE phenomenon increases
Solution Approach 1:
The patent substitutes the traditional mechanical/mathematical approach of using standard orthogonal bases with a more advanced mathematical framework based on Itô-Hermite polynomials. This substitution replaces the conventional basis generation method with one that inherently provides better spectral confinement, reducing OOBE while adding manageable computational complexity.
Data Source
AI summary
A transceiver includes a transmitter up-converting a frequency of input data to transmit data of a first frequency, an orthogonal basis generator receiving the input data from the transmitter to generate an orthogonal basis; and a receiver receiving the orthogonal basis from the orthogonal basis generator and receiving the transmitted data for down-converting a frequency of the received data to a second frequency different from the first frequency. The orthogonal basis generator includes, a multiplier multiplying the input data by a Gaussian characteristic value obtained by extracting a Gaussian characteristic of the data to generate an out of band emission (OOBE) value, and a polynomial block generating the orthogonal basis by using the OOBE value as an input to an Itô-Hermite polynomial.