Digital TX Distortion Estimation for Receiver Sensitivity
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Solution Overview
Problem
In frequency division duplex (FDD) wireless systems, transmitter signals can cause distortions that degrade receiver sensitivity, particularly in LTE inter-band carrier aggregation scenarios, where transmitter signals or their harmonics may fall into the receiver's frequency band, leading to receiver de-sense and sensitivity issues.
Innovation Solution
A method and system that estimate and reduce transmitter-induced distortions in the digital domain by detecting distortions caused by the transmitter signal, its conjugate, harmonic, or conjugate harmonic, and applying adjustment signals to mitigate these effects, using a TX distortion estimation module within the wireless terminal's digital baseband module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital domain distortion estimation and reduction is implemented, then receiver sensitivity is improved, but device complexity increases
Solution Approach 1:
The patent introduces a TX distortion estimation module as an intermediary component within the digital baseband module. This module estimates transmitter-induced distortions by processing the transmitted signal and received signal, then generates compensation signals to reduce the distortions. The intermediary module isolates the complexity from the core receiver functionality while improving receiver sensitivity through distortion compensation.
Solution Approach 2:
The patent creates a digital model (copy) of the transmitter signal and its expected distortions. By estimating the distortion coefficients through correlation between the transmitted signal and received signal, the system creates a virtual representation of the distortion that can be compensated without physically modifying the analog front-end components.
2Ease of manufacture
If distortion compensation is implemented in the digital domain, then manufacturing cost is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces potential analog/physical distortion compensation mechanisms with digital signal processing. Instead of modifying analog front-end components or adding complex RF filtering hardware, the system uses digital domain operations (correlation, coefficient estimation, signal generation) to achieve distortion compensation, thereby reducing manufacturing cost while shifting precision requirements to the digital processing domain.
3Reliability
If real-time distortion calibration is implemented, then receiver sensitivity is improved, but processing time increases
Solution Approach 1:
The patent performs distortion coefficient estimation using the transmitted signal and received signal in real-time. By continuously monitoring and estimating distortion coefficients based on actual transmitted and received signals, the system prepares compensation signals proactively, reducing the time penalty of calibration while maintaining improved receiver sensitivity.
Data Source
AI summary
Computer-implemented methods, computer software, and computer systems for adjusting receiver distortion caused by transmitter signals. A first signal is transmitted by a transmitter of the wireless terminal. A second signal is detected by a receiver of the wireless terminal. The second signal includes distortion caused by at least one of the first signal, a conjugate of the first signal, a harmonic of the first signal, or a conjugate of a harmonic of the first signal. At least one distortion coefficient is estimated in a digital domain based on the first signal and the second signal. Distortion of a third signal received by the receiver of the wireless terminal is adjusted based on the at least one distortion coefficient. Adjustment of distortion can be in the form of reduction, as well as elimination, of the distortion.