Selective Peak Power Reduction for Mixed-Modulation Signals
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Solution Overview
Problem
Existing techniques are ineffective in reducing the peak-to-average power ratio (PAPR) for combined signals from different modulation schemes, such as OFDM and TDMA or CDMA, as they require different PAPR techniques and can result in undesirable PAPR when signals are combined.
Innovation Solution
A selective peak power reduction technique that applies peak reduction distortion only to specific frequency bands of a combined signal, where the distortion can be tolerated, minimizing impact on other signals, thereby reducing peak power effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PAPR reduction techniques are applied to individual signals before combining, then the PAPR of individual signals is reduced, but the PAPR of the combined signal still increases significantly
Solution Approach 1:
The patent divides the combined signal into multiple frequency bands and applies PAPR reduction selectively to specific bands rather than uniformly to the entire signal. This segmentation allows different processing strategies for different frequency regions, reducing the overall PAPR while preserving signal quality in critical bands.
Solution Approach 2:
The patent applies different PAPR reduction techniques to different frequency bands based on their specific characteristics and tolerance levels. Some bands receive aggressive PAPR reduction while others receive minimal or no processing, optimizing the balance between PAPR reduction and signal quality preservation.
2Reliability
If different PAPR techniques are applied to different modulation schemes, then each signal type can be optimized, but the system complexity increases
Solution Approach 1:
The patent implements a universal PAPR reduction framework that can handle multiple modulation schemes (OFDM, CDMA, TDMA) through a common processing architecture. The system automatically adapts to different signal types and applies appropriate reduction techniques, eliminating the need for separate dedicated processors for each modulation scheme.
Solution Approach 2:
The patent employs dynamic signal routing and adaptive processing where the system automatically identifies the modulation scheme of incoming signals and directs them to appropriate processing paths. This dynamic adaptation allows a single system to efficiently handle diverse signal types without requiring static, dedicated hardware for each scheme.
3Reliability
If peak clipping is applied to reduce peaks above threshold, then PAPR is reduced, but distortion is introduced to the signal
Solution Approach 1:
The patent introduces frequency band selection as an intermediary layer between the input signal and the PAPR reduction process. By selecting specific frequency bands for processing and excluding others, the system acts as a mediator that prevents distortion from propagating to the entire signal, applying clipping only where it will have minimal impact on overall signal quality.
Solution Approach 2:
The patent converts the potential harm of distortion into a benefit by strategically applying distortion only in frequency bands where it will be least noticeable or least impactful. The distortion introduced in selected bands is offset by preserving signal fidelity in unprocessed bands, effectively transforming a harmful effect into an acceptable trade-off for achieving PAPR reduction.
Data Source
AI summary
The present invention provides a technique for reducing the peak power of a combined signal that has a first signal of a first modulation type and a second signal of a second modulation type. Based on the combined signal, peak reduction distortion is determined. The peak reduction distortion is configured such that, if applied to the entirety of the combined signal, excessive peaks throughout the combined signal would be reduced. However, instead of applying the entirety of the peak reduction distortion, a selected portion of the peak reduction distortion is applied to a corresponding portion of the combined signal to reduce the peak power of the combined signal.