Non-causal OFDM Peak Suppression via Signal Scaling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
OFDM communication systems face high Peak to Average Power Ratio (PAPR) issues, leading to inefficient power amplifier operation, potential signal distortion, and reduced transmitter lifetime due to peak clipping, which existing solutions attempt to address with phase randomization but increase system complexity.
Innovation Solution
The method involves routing the OFDM signal through two processing paths, time delaying it in one path and scaling the signal magnitude in the other if it exceeds a threshold, preventing the power amplifier from entering a non-linear region without causing phase distortion, thus reducing PAPR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power amplifier operates at maximum output level, then the power efficiency is improved, but the amplifier enters non-linear region causing signal distortion
Solution Approach 1:
The patent applies preliminary action by detecting peak signal levels in advance and applying pre-scaling to the OFDM signal before amplification. The scaling factor is calculated based on predicted peak values, allowing the power amplifier to operate at maximum linear output level without distortion while maintaining power efficiency.
Solution Approach 2:
The patent changes the amplitude parameter of the OFDM signal by applying a scaling factor to reduce peak values. This parameter transformation allows the signal to stay within the linear region of the power amplifier, enabling efficient operation without distortion.
2Reliability
If peak clipping is applied to maintain linear operation, then signal distortion is reduced, but the voltage standing wave ratio changes drastically causing power reflection
Solution Approach 1:
The patent applies preliminary action by detecting and scaling peak signal levels in advance before they reach the power amplifier. This pre-processing prevents drastic VSWR changes and power reflection by ensuring the amplifier receives a scaled signal that maintains stable impedance matching throughout operation.
3Object-generated harmful factors
If phase randomization is applied to reduce PAPR, then the peak power ratio is improved, but the system complexity increases
Solution Approach 1:
The patent extracts and removes the harmful peak components from the OFDM signal by applying scaling factors to reduce PAPR. This extraction approach eliminates the need for complex phase randomization techniques while achieving PAPR reduction through direct magnitude adjustment.
Data Source
AI summary
System (200) and methods (800) for reducing a PAPR of an OFDM signal (204). The methods comprise: routing the OFDM signal to first and second signal processing paths (FSPP and SSPP); time delaying the OFDM signal traveling along FSPP (206); and determining whether an instantaneous signal magnitude value of the OFDM signal traveling along SSPP (208) is greater than a threshold value that would force a power amplifier (250) into a non-linear operational region. If it is determined that the instantaneous signal magnitude value is greater than the threshold value, then a magnitude of at least one complex symbol sample of the OFDM signal which has been time delayed is scaled to a level that precludes the power amplifier from entering its non-linear operational region. If it is determined that the instantaneous signal magnitude value is not greater than the threshold value, then the complex symbol sample is output without modification to the magnitude thereof.