Bit Inversion Peak Reduction for High-PAPR Wireless Signals
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Solution Overview
Problem
Conventional power amplifiers for wireless communication face inefficiencies due to high peak to average power ratio (PAPR) in signals, leading to lower transmit power and suboptimal signal-to-noise ratios, especially in high constellations like 4096 QAM, where existing PAPR reduction algorithms fail to provide significant improvements.
Innovation Solution
A wireless communication system with signal peak reduction circuitry that inverts specific bits in symbols causing amplitude peaks, using a bit inverter and peak detector to reduce signal amplitude below a predetermined threshold, while ensuring forward error correction in the receiver restores the original bit values, thus reducing PAPR without degrading error vector magnitude (EVM) or introducing out-of-band noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If signal amplitude peaks are reduced by clipping or conventional algorithms, then PAPR is reduced, but signal distortion and error vector magnitude degrade
Solution Approach 1:
The patent inverts specific bits in the modulated symbols that cause peak amplitude excursions, rather than directly clipping the amplitude. This inversion approach reduces PAPR while maintaining signal integrity because the inverted bits are corrected by the forward error correction decoder at the receiver, avoiding permanent distortion.
Solution Approach 2:
The patent performs bit inversion before transmission as a preventive measure. By proactively inverting bits that would cause peak excursions before the signal is transmitted, the system prevents PAPR issues rather than correcting them afterward, while ensuring the receiver can restore the original data through FEC decoding.
2Reliability
If power amplifier operates at lower peak power to handle high PAPR signals, then signal distortion is reduced, but average transmit power and power efficiency decrease
Solution Approach 1:
Instead of limiting the peak power capability of the amplifier, the patent inverts bits to prevent peak excursions in the first place. This allows the power amplifier to operate at higher average power levels without risking signal distortion, thereby improving overall power efficiency while maintaining signal quality.
3Loss of energy
If existing PAPR reduction algorithms are applied to high constellation signals like 4096 QAM, then some PAPR reduction is achieved, but the improvement is insignificant and complexity increases
Solution Approach 1:
The patent uses a simple bit inversion mechanism that is particularly effective for high constellation signals. Rather than employing complex clipping or iterative algorithms, the system identifies and inverts specific bits causing peaks, providing significant PAPR reduction for 4096 QAM and similar high-order modulations with minimal added complexity.
Solution Approach 2:
The patent changes the approach from amplitude manipulation to bit-level inversion. By operating at the bit level rather than the amplitude level, the system achieves effective PAPR reduction for high constellation signals without the complexity of conventional algorithms that are designed for lower-order modulations.
Data Source
AI summary
A system and method for reducing peak to average power ratio in a wireless communication system. A wireless communication system includes a radio frequency wireless transmitter that includes signal peak reduction circuitry configured to reduce peak to average power ratio of a signal to be transmitted by reducing amplitude of the signal to be transmitted that is greater than a predetermined amplitude. The signal peak reduction circuitry includes a bit inverter configured to invert a bit of a symbol identified as causing the amplitude of the signal to exceed the predetermined amplitude. The bit inverter is also configured to select the bit to invert such that inversion of the bit reduces the amplitude of the signal, and such that forward error correction in a receiver wirelessly coupled to the transmitter restores the bit to a pre-inversion value.