OFDM Baseband Signal PAPR Reduction via Threshold Clipping
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Solution Overview
Problem
In OFDM communication, the increase in the number of subcarriers leads to a high Peak-to-Average Power Ratio (PAPR), requiring amplifiers with wide linearity to prevent distortion, and existing techniques struggle to effectively control and reduce PAPR.
Innovation Solution
A communication apparatus and method that modulates input signals using a predetermined scheme, performs inverse Fast Fourier Transformation, decomposes data into real and imaginary parts, and applies threshold values to generate positive and negative data, which are then combined to generate a baseband signal, reducing PAPR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of subcarriers is increased to increase the FFT size, then the communication capacity is improved, but the PAPR increases requiring amplifiers with wide linearity
Solution Approach 1:
The patent applies preliminary action by performing PAPR reduction processing on the time-domain signal before the signal is transmitted. The operator processes the time-domain signal by subtracting a threshold value from peak values to reduce PAPR in advance, preventing the need for wide-linearity amplifiers while maintaining high communication capacity through increased FFT size
Solution Approach 2:
The patent changes the parameter of the time-domain signal by applying threshold-based clipping operations. The operator modifies signal parameters (amplitude values) by subtracting threshold values from peak values, thereby changing the signal's PAPR characteristic while preserving the underlying communication information
2Object-affected harmful factors
If existing PAPR reduction techniques are used, then the PAPR is reduced, but the degree of reduction cannot be controlled
Solution Approach 1:
The patent introduces dynamics by making the threshold value adjustable rather than fixed. The operator uses a configurable threshold parameter that can be dynamically changed based on system requirements, allowing flexible control over the degree of PAPR reduction. This enables adaptation to different communication scenarios and performance requirements
3Object-affected harmful factors
If subcarrier-by-subcarrier phase control is performed to reduce PAPR, then the PAPR is reduced, but the processing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the signal processing into distinct functional blocks: the modulator for subcarrier modulation, the transformer for IFFT conversion, and the operator for PAPR reduction. This modular segmentation allows the PAPR reduction operation to be performed as a simple threshold-based clipping process on the time-domain signal, avoiding complex subcarrier-by-subcarrier phase control while maintaining effectiveness
Data Source
AI summary
A modulator generates a modulation signal from an input signal. A serial-parallel converter generates a subcarrier modulation signal from the modulation signal. An IFFT unit performs an inverse fast Fourier transformation on the subcarrier modulation signal, generating first data. A decomposer decomposes the first data into real data and imaginary data. An operator performs a predetermined operation using a predetermined threshold value, a boundary value and the real data, generating positive data and negative data. Another operator performs a similar operation on the imaginary data. A generator adds the positive data and negative data based on the real data, and adds the positive data and negative data based on the imaginary data, generating real operation data and imaginary operation data. A synthesizer synthesizes both operation data to generate a baseband signal. A transmitter generates a transmission signal from the baseband signal, and transmits it to another apparatus via an antenna.