OFDM Satellite Transmitter Predistortion for Nonlinear Distortion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
OFDM-based satellite communication systems face challenges in compensating for nonlinear distortion, which affects the performance and efficiency of satellite transponders due to high peak-to-average power ratio (PAPR) levels.
Innovation Solution
The implementation of a method for applying transmitter data predistortion to OFDM-like transmission channels in satellite transmitters, which compensates for nonlinear distortion by using a computationally efficient distortion construction that incorporates input from all OFDM subcarriers, allowing for successive data predistortion at the transmitter or soft cancellation at the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM modulation is used in satellite communication systems, then spectral efficiency and data rate are improved, but nonlinear distortion increases due to high peak-to-average power ratio (PAPR)
Solution Approach 1:
The patent applies data predistortion at the transmitter to pre-compensate for nonlinear distortion before signal transmission. By modifying the data symbols in advance based on the characteristics of the nonlinear amplifier, the system counteracts the expected distortion effects, allowing the HPA to operate near saturation while maintaining signal integrity
Solution Approach 2:
The patent implements iterative distortion compensation where the receiver estimates nonlinear distortion and feeds back correction information to the transmitter. Through multiple iterations of distortion estimation and compensation, the system progressively reduces nonlinear distortion effects, enabling efficient HPA operation
2Object-generated harmful factors
If traditional distortion compensation methods are used, then nonlinear distortion is reduced, but computational complexity and processing overhead increase
Solution Approach 1:
The patent divides the distortion compensation process into separate stages: data predistortion at the transmitter and soft cancellation at the receiver. This segmentation allows each component to handle specific aspects of distortion compensation with optimized computational requirements, reducing overall system complexity compared to unified compensation methods
Solution Approach 2:
The patent changes the approach from signal-level predistortion to data-level predistortion, and from hard cancellation to soft cancellation. These parameter changes in the compensation methodology reduce computational complexity while maintaining effective distortion mitigation, as data-domain operations are more efficient than time-domain signal processing
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Implementations described herein are directed to correcting for distortion in satellite communications systems that utilize OFDM-like signaling. This distortion correction may account for the linear and nonlinear distortion introduced by the high power amplifier of a satellite receiving a composite signal, the linear and nonlinear distortion caused by the interaction of the signals in the composite, the linear and nonlinear distortion caused by the interaction between OFDM subcarriers, and/or the linear and nonlinear distortion caused by inter-carrier interference.