OFDM Communication Device PAPR Reduction via Differential Encoding
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Solution Overview
Problem
OFDM communication systems face challenges in reducing Peak-to-Average Power Ratio (PAPR), which requires complex iterative calculations and individual phase control for each subcarrier, leading to inefficiencies in amplifier linearity and signal distortion.
Innovation Solution
A communication device that employs differential encoding, modulation, inverse Fast Fourier Transformation (IFFT), and selection of baseband signals with lower PAPR, using predetermined identification data to generate and transmit signals with reduced PAPR, while also including a receiver for demodulation and decoding to restore signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If iterative calculations and individual phase control per subcarrier are performed to reduce PAPR, then PAPR reduction is achieved, but device complexity and calculation time increase
Solution Approach 1:
The patent segments the data stream into multiple portions and assigns different modulation schemes to each segment. This allows independent optimization of PAPR for each segment while reducing the overall computational complexity compared to uniform phase control across all subcarriers. The segmentation enables selective application of differential encoding only where needed to achieve PAPR reduction.
Solution Approach 2:
The patent changes the modulation parameter dynamically by switching between primary modulation and differential encoding based on PAPR characteristics. Instead of fixed phase control, the system adapts the modulation scheme per segment, changing parameters such as encoding type and modulation mode to optimize PAPR reduction while minimizing computational overhead.
2Reliability
If differential encoding and selection methods are used to reduce PAPR, then amplifier linearity is improved, but communication efficiency decreases
Solution Approach 1:
The patent applies local quality by differentiating treatment between data segments. Not all segments receive differential encoding - only those exceeding PAPR thresholds. This localized application maintains amplifier linearity where needed while preserving communication efficiency in segments where PAPR is already acceptable, thus optimizing the trade-off between linearity and efficiency.
Solution Approach 2:
The system dynamically adjusts the modulation scheme based on real-time PAPR measurement of each data segment. The selector unit dynamically switches between primary modulation and differential encoding based on instantaneous PAPR characteristics, allowing the system to adapt communication efficiency to current signal conditions rather than using a fixed inefficient mode.
3Reliability
If individual phase control per subcarrier is implemented, then PAPR reduction is achieved, but processing time increases
Solution Approach 1:
The patent merges multiple subcarriers into data segments that are processed together as units. Instead of controlling phase individually for each subcarrier, the system applies differential encoding to segments of data, combining multiple subcarrier operations into a single processing step. This merging significantly reduces processing time while maintaining effective PAPR reduction.
Solution Approach 2:
The system performs preliminary segmentation and PAPR assessment before applying modulation. By pre-identifying which data segments require differential encoding based on their PAPR characteristics, the system avoids unnecessary processing for segments that don't need it, thereby reducing overall processing time while ensuring PAPR reduction is applied only where beneficial.
Data Source
AI summary
An identification provider provides predetermined identification data to an input signal, and generates a first signal. A differential encoder performs a differential encoding of a data series that is an aggregate of data having a matching number of elements to that contained in the first signal, and generates a second signal. A modulator modulates each of the first and second signals using a primary modulation, and generates first and second modulated data. An IFFT calculator performs an inverse fast Fourier transformation on each of the first and second modulated data, and generates first and second inverse transformed data. A selector compares peak-to-average power ratios calculated by baseband signals associated with the first and second inverse transformed data, and selects a baseband signal having the lower peak-to-average power ratio. A transmitter generates a transmission signal based on the selected baseband signal, and transmits the transmission signal.