Multi-Carrier RF Signal Power Control for Spectral Mask Compliance
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Solution Overview
Problem
Current multi-carrier waveforms, such as OFDM, suffer from spectral inefficiency due to guard intervals and frequency transition zones, leading to reduced data transmission rates and increased complexity in filtering for fragmented spectra.
Innovation Solution
A method that modulates sub-carriers in frequency transition zones with controlled power to match emission spectral masks, allowing for increased sub-carrier usage and improved spectral efficiency without compromising signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If guard interval or cyclic prefix is inserted to eliminate intersymbol interference, then reliability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent extracts and removes the guard interval or cyclic prefix from the transmission structure, transitioning from block-based transmission with guards to continuous stream transmission, thereby eliminating the spectral efficiency loss while maintaining interference suppression through other means
Solution Approach 2:
The patent changes the fundamental transmission parameter from block-based with guard intervals to continuous stream transmission, fundamentally altering how data is structured and transmitted to eliminate the need for spectral inefficiency-causing guard periods
2Object-generated harmful factors
If sub-carriers in frequency transition zones are transmitted with zero power to respect emission spectral masks, then harmful emissions are reduced, but spectral efficiency deteriorates
Solution Approach 1:
The patent changes the power parameter of sub-carriers in frequency transition zones from zero to a controlled non-zero value, allowing these sub-carriers to carry data while still respecting emission spectral masks through power control, thereby improving spectral efficiency without compromising mask compliance
Solution Approach 2:
The patent applies partial power transmission to sub-carriers in frequency transition zones rather than complete zero power, using just enough power to transmit data effectively while staying within acceptable emission limits, thus improving overall spectral utilization
3Object-generated harmful factors
If temporal filtering is applied to reduce secondary lobes and improve spectral confinement, then harmful emissions are reduced, but device complexity and intersymbol interference increase
Solution Approach 1:
The patent removes the temporal filtering operation from the transmission chain, eliminating the complexity of filter implementation and the associated intersymbol interference, while addressing spectral confinement through alternative means such as optimized windowing or frequency-domain techniques
Solution Approach 2:
The patent substitutes the mechanical/temporal filtering approach with a frequency-domain or signal-structure-based approach, replacing complex time-domain filter operations with simpler alternative techniques that achieve similar spectral confinement without the associated complexity and intersymbol interference
Data Source
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AI summary
The invention relates to a method for generating a multi-carrier radio frequency signal intended to be transmitted over a radio frequency transmission channel while respecting an emission spectral mask, the mask defining a signal attenuation requirement relative to a useful signal power in a useful frequency band smaller than the channel width, the attenuation requirement being defined for at least one frequency transition zone between an edge of the useful frequency band and an adjacent edge of the transmission channel.Such a process includes, for at least one subcarrier intended to be transmitted in a frequency transition zone: - modulation (E300) of the subcarrier by a corresponding modulation symbol, delivering a modulated subcarrier of the signal; and - power control (E310) of the modulated subcarrier relative to the useful power so as to respect the spectral emission mask in the frequency transition zone.