OFDM RF Distortion Compensation via Frequency Domain Inverse Sync
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Solution Overview
Problem
In orthogonal frequency division multiplexing transmission systems, existing methods for compensating distortion caused by digital/analog converters are inefficient and power-intensive, particularly in portable terminals where complex digital filters and interpolation methods increase operational complexity and power consumption.
Innovation Solution
A radio frequency distortion compensator is introduced that processes frequency domain data before the inverse fast Fourier transform unit, using a digital modulator, inverse sync function coefficient generator, and sync function compensator to generate and apply compensation signals, reducing the number of operations and power consumption by compensating distortion directly in the frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex digital filters and interpolation methods are used to compensate distortion, then signal quality is improved, but power consumption and operational complexity increase
Solution Approach 1:
The patent changes the domain of operation from time domain to frequency domain for distortion compensation. By applying inverse sync function coefficients in the frequency domain rather than using complex time-domain digital filters, the system achieves effective distortion compensation with reduced computational complexity and power consumption, particularly in portable terminals
Solution Approach 2:
The patent extracts the distortion compensation function from the time domain processing chain and implements it separately in the frequency domain using inverse sync function coefficients. This separation allows the compensation to be applied efficiently without requiring complex digital filters, thereby reducing power consumption while maintaining signal quality
2Measurement precision
If complex digital filters and interpolation methods are used to compensate distortion, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent changes the domain of operation from time domain to frequency domain for distortion compensation. By applying inverse sync function coefficients in the frequency domain rather than using complex time-domain digital filters, the system achieves effective distortion compensation with reduced computational complexity and power consumption, particularly in portable terminals
Solution Approach 2:
The patent uses pre-calculated inverse sync function coefficients that are stored and applied during signal processing. Instead of performing complex real-time filter operations, the system copies and applies these pre-computed coefficients in the frequency domain, significantly reducing operational complexity while maintaining compensation effectiveness
3Device complexity
If digital signal is converted to analog at the same clock frequency, then system simplicity is maintained, but signal distortion occurs in radio frequency band
Solution Approach 1:
The patent applies distortion compensation in the frequency domain before the digital-to-analog conversion. By pre-compensating the signal with inverse sync function coefficients in the frequency domain, the system prepares the signal to counteract the distortion that will occur during the simple same-clock-frequency conversion, thus maintaining both system simplicity and signal quality
Solution Approach 2:
The patent applies the inverse sync function coefficients to create a preliminary anti-action that counteracts the expected distortion from the digital/analog converter. This pre-compensation in the frequency domain ensures that when the simple conversion occurs, the signal distortion is minimized, achieving both simplicity and accuracy
Data Source
AI summary
The present invention relates to a device for compensating a radio frequency distortion caused by a sample/hold operation of a digital/analog converter in an orthogonal frequency division multiplexing (OFDM) transmission system, and a method thereof. In a digital transmission system, an edge frequency signal of a transmission signal band is distorted by a sample/hold operation of a digital/analog converter such that a signal attenuation is generated at a frequency domain by a sync function having a zero point at a sample frequency of a transmission signal. In the present invention, the signal distortion may be compensated by multiplying a coefficient of an inverse sync function by a signal weight value at the frequency domain, and it may be compensated by using a single multiplier and a lookup table storing the coefficient of the inverse sync function.