Selective Peak Reduction Across Mixed-Modulation Frequency Bands
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Solution Overview
Problem
Existing communication systems face inefficiencies due to high peak-to-average power ratio (PAPR) when combining signals from different modulation schemes, such as OFDM and TDMA or CDMA, as existing PAPR reduction techniques are ineffective across multiple modulation types.
Innovation Solution
A method that generates peak reduction distortion based on a combined input signal and selectively applies it to specific frequency bands of the combined signal, tailored to the modulation type that can tolerate the distortion, thereby reducing peak power while minimizing impact on other modulation types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If PAPR reduction techniques are applied to combined signals from different modulation schemes, then amplifier efficiency is improved, but the techniques become ineffective and PAPR reduction fails
Solution Approach 1:
The patent segments the combined signal into multiple frequency bands, where each band corresponds to a specific modulation scheme. By identifying which frequency bands contain which modulation types, the system can apply modulation-specific PAPR reduction techniques to each segment, thereby maintaining effectiveness while improving overall amplifier efficiency.
Solution Approach 2:
The patent applies different PAPR reduction techniques to different frequency bands based on the local modulation scheme present in each band. This local quality approach ensures that each segment of the signal receives the most appropriate processing for its specific modulation type, resolving the contradiction between maintaining effectiveness and improving efficiency.
2Adaptability or versatility
If multiple modulation schemes are combined in the same signal, then system versatility is improved, but PAPR increases significantly
Solution Approach 1:
The patent divides the combined signal containing multiple modulation schemes into separate frequency bands, each associated with a specific modulation scheme. This segmentation allows the system to maintain support for multiple modulation types while managing the PAPR of each segment individually, preventing the overall PAPR from becoming excessively high.
Solution Approach 2:
By applying modulation-specific processing to each frequency band based on its local modulation scheme, the patent enables the system to maintain versatility across multiple modulation types while controlling the peak power characteristics of each local segment, thereby managing overall PAPR.
3Loss of energy
If peak clipping is applied to reduce PAPR, then amplifier efficiency is improved, but signal distortion increases
Solution Approach 1:
The patent segments the signal into frequency bands and applies clipping only to specific bands where it is most beneficial and least harmful. By identifying which frequency bands can tolerate clipping without excessive distortion, the system can improve amplifier efficiency while minimizing overall signal distortion.
Solution Approach 2:
The patent applies clipping selectively to specific frequency bands based on their local characteristics and modulation scheme. This local quality approach allows clipping to be applied where it improves efficiency without causing excessive distortion, resolving the contradiction between amplifier efficiency and signal quality.
Data Source
AI summary
A communication system comprising signal processing circuitry and up-conversion circuitry. The signal processing circuitry is configured to: i) generate a first signal of a first modulation type and a second signal of a second modulation type; ii) combine the first and second signals to form a combined input signal; iii) generate peak reduction distortion based on the combined input signal; iv) select a portion of the peak reduction distortion that corresponds to a first frequency band; and v) apply the selected portion of the peak reduction distortion in the first frequency band of the combined input signal to provide a combined output signal. The up-conversion circuitry up-converts the combined output signal to an RF signal for transmission.