OFDM Modulator Phase Control for PAPR Reduction
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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 signal deformation, and existing techniques struggle to effectively control and reduce PAPR.
Innovation Solution
A communication device and method that involves a modulator performing a predetermined operation on input signal elements, multiplying them by a data series with specific auto-correlation characteristics, and using IFFT to generate a baseband signal, along with a receiver that performs FFT and demodulation to reduce PAPR and improve bit error rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of subcarriers is increased to increase the FFT size, then the data transmission capacity is improved, but the PAPR increases requiring amplifiers with wide linearity
Solution Approach 1:
The patent applies parameter changes by modifying the phase parameters of subcarrier modulation signals through sequential decision procedures. The optimal phase is calculated to reduce PAPR while maintaining the increased FFT size and data transmission capacity, thus resolving the contradiction between transmission capacity and PAPR control.
Solution Approach 2:
The patent implements preliminary action by controlling the phase of subcarrier modulation signals before the IFFT operation. The optimal phase is calculated in advance through sequential decision procedures, and this pre-control prevents PAPR increase even when using large FFT sizes for high data transmission capacity.
2Object-generated harmful factors
If sequential decision procedure is used to calculate optimal phase for PAPR reduction, then PAPR is reduced, but the device complexity and computational load increase
Solution Approach 1:
The patent applies partial action by implementing sequential decision procedures that calculate optimal phase for PAPR reduction only where necessary, rather than exhaustive optimization of all parameters. This approach achieves sufficient PAPR reduction while limiting computational complexity to manageable levels.
Solution Approach 2:
The patent implements dynamics by using adaptive sequential decision procedures that adjust the phase control strategy based on signal conditions. This dynamic approach optimizes the balance between PAPR reduction effectiveness and computational complexity, applying more aggressive optimization only when needed.
3Object-generated harmful factors
If PAPR reduction techniques are applied, then amplifier linearity requirements are relaxed, but the modulation complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying only the phase parameters of subcarrier modulation signals through sequential decision procedures, rather than changing the fundamental modulation scheme. This approach reduces PAPR while maintaining relatively simple modulation structures and avoiding excessive modulation complexity.
Data Source
AI summary
A modulator performs a predetermined operation for making an absolute value of an operation result of at least one element of an input signal greater than 0 on the individual elements of the input signal. The modulator generates post-operation data by associating individual elements of the input signal with individual elements of a data series which is a set of pieces of data which are equal in number to the elements of the input signal and whose absolute values are equal to one another, and multiplying the individual elements of the input signal which are subjected to the predetermined operation by the elements of the data series. An IFFT calculator performs inverse fast Fourier transformation on the post-operation data, and a synthesizer synthesizes operation results from the IFFT calculator to generate a baseband signal. A transmitter generates a transmission signal from the baseband signal and transmits the transmission signal.