OFDM Baseband Signal PAPR Reduction via Real Imaginary Processing
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Solution Overview
Problem
In OFDM-based communication systems, the high Peak-to-Average Power Ratio (PAPR) of baseband signals increases with the number of subcarriers, requiring amplifiers with wide linearity to prevent distortion, but existing techniques for reducing PAPR are inefficient and difficult to control.
Innovation Solution
A communication device and method that perform specific calculations on real and imaginary part data after IFFT, generating post-distribution sub-data with controlled thresholds to reduce PAPR, and combine these to create a baseband signal, allowing for controlled PAPR reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of subcarriers is increased to improve communication capacity, then the data transmission rate is improved, but the PAPR of the baseband signal increases requiring amplifiers with wider linearity
Solution Approach 1:
The patent applies preliminary action by performing PAPR reduction processing on the baseband signal before transmission. The communication device calculates PAPR of the baseband signal, compares it with a threshold, and applies scaling or clipping operations to reduce PAPR before the signal is transmitted, thereby preventing distortion without requiring amplifiers with excessively wide linearity
Solution Approach 2:
The patent changes parameters of the baseband signal to control PAPR. By adjusting the scaling factor or clipping threshold based on calculated PAPR values, the system dynamically modifies signal parameters to maintain acceptable PAPR levels while preserving communication capacity, thus resolving the contradiction between transmission rate and amplifier requirements
2Device complexity
If existing PAPR reduction techniques are applied to reduce PAPR, then the amplifier linearity requirement is reduced, but the processing complexity and efficiency are insufficient
Solution Approach 1:
The patent implements feedback by calculating the PAPR of the baseband signal, comparing it with a predetermined threshold, and applying reduction operations only when necessary. This feedback mechanism allows the system to efficiently reduce PAPR only when the signal exceeds acceptable levels, avoiding unnecessary processing and maintaining high processing efficiency while reducing amplifier requirements
Data Source
AI summary
A modulator generates a subcarrier modulation signal from an input signal, a parallel-serial converter generates a subcarrier modulation signal from the modulation signal. An IFFT calculator performs reverse Fast Fourier Transform on the subcarrier modulation signal, and a separator separates a calculation result into real part data and imaginary part data. A real part calculator performs a calculation on each element of the real part data to generate real part post-distribution data. An imaginary part calculator performs the data processing on the imaginary part data in the same manner, and generates imaginary part post-distribution data. A combiner combines the real part post-distribution data and the imaginary part post-distribution data to generate a baseband signal, and a transmitter which generates a transmission signal from the baseband signal to transmit generated transmission signal.