OFDM Communication Apparatus PAPR Reduction via Signal Insertion
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Solution Overview
Problem
In OFDM communication systems, the Peak-to-Average Power Ratio (PAPR) increases with larger FFT sizes, requiring complex calculations to reduce PAPR, which complicates the process.
Innovation Solution
A communication apparatus that inserts redundant signals into the modulated signal, calculates the PAPR, and adjusts the signal until it matches a predetermined reference, simplifying the process by repeating this insertion and calculation until the desired PAPR is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If sequential decision procedure is used to calculate optimum phase for reducing PAPR, then PAPR reduction is achieved, but calculation complexity increases
Solution Approach 1:
The patent creates a copy of the modulated signal by inserting a predetermined element (such as a pilot signal or reference signal) at a predetermined position. This copied signal structure allows for simplified PAPR calculation and control without requiring complex sequential decision procedures, as the inserted element provides direct information about the signal characteristics.
Solution Approach 2:
The patent changes the approach from calculating optimum phase for each subcarrier to inserting a predetermined element that directly provides PAPR information. This parameter change transforms the problem from complex iterative optimization to a simpler insertion and measurement process, reducing calculation complexity while maintaining PAPR reduction effectiveness.
2Loss of energy
If subcarrier-by-subcarrier phase control is implemented, then PAPR is reduced, but process complexity increases
Solution Approach 1:
Instead of controlling phase for each subcarrier individually, the patent inserts a predetermined element (a copied reference structure) at a specific position in the modulated signal. This copying approach simplifies the process by providing a unified reference point for PAPR control rather than requiring separate control operations for each subcarrier.
3Productivity
If FFT size is increased to improve communication efficiency, then data transmission capacity increases, but PAPR becomes higher
Solution Approach 1:
The patent introduces a predetermined element (intermediary signal) inserted at a specific position in the modulated signal. This intermediary provides reference information that enables PAPR control without requiring reduction of the FFT size, thus maintaining data transmission capacity while managing PAPR through the inserted reference element.
Data Source
AI summary
The communication apparatus comprises a modulator that modulates an input signal to generate a modulated signal; an inserter that inserts a predetermined element into the modulated signal at a predetermined position to generate inserted data of which the number of elements is equal to a size of Fast Fourier Transformation (FFT); a calculator that calculates Peak-to-Average Power Ratio (PAPR) of a baseband signal corresponding to the inserted data; and a transmitter transmits a transmission signal corresponding to the baseband signal based on the calculated PAPR.