Transmitter Feedback Interference Cancellation
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Solution Overview
Problem
In MIMO wireless communications, signal distortion occurs due to interference between transmit and feedback channels, which existing technologies have not effectively addressed.
Innovation Solution
A transmitter with a feedback cancellation module, a digital predistorter (DPD), and a power amplifier (PA) is used to perform interference cancellation on the feedback channel when it is in an idle state, generating a predistortion signal to reduce distortion on the transmit channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the feedback channel is connected to the transmit channel for continuous monitoring, then the feedback signal can be obtained in real-time, but interference from the transmit channel leaks into the feedback channel causing signal distortion
Solution Approach 1:
The patent applies preliminary action by collecting feedback interference signals during idle states before actual transmission occurs. The system pre-characterizes the interference profile by measuring the feedback channel when transmit channels are idle, then uses this pre-collected interference information to cancel interference during active transmission, avoiding real-time interference contamination.
Solution Approach 2:
The patent extracts the interference signal component from the feedback channel by separating it during idle states. The feedback cancellation module extracts the interference profile by measuring only the interference portion (when no transmit signal is present) and removes this extracted interference characteristic from the combined feedback signal during transmission, isolating the useful feedback information.
2Object-generated harmful factors
If transmit channels are separated by physical distance or cavity shielding, then interference among transmit channels is reduced, but signal leakage from transmit channels to feedback channel still occurs
Solution Approach 1:
The patent applies feedback by creating a feedback cancellation module that monitors the feedback channel and uses collected interference information to generate cancellation signals. The system feeds back the interference characteristics to the transmit channel processing, creating a closed-loop interference cancellation mechanism that continuously compensates for leakage effects.
Solution Approach 2:
The patent introduces an intermediary feedback cancellation module that mediates between the transmit channels and feedback channel. This intermediary component collects interference signals, processes them through correlation analysis, and generates cancellation signals that are injected back into the feedback path, acting as a buffer that eliminates direct interference coupling.
3Measurement precision
If the feedback channel is grounded or disconnected during idle state, then interference signal can be collected cleanly, but the system requires switching operations adding complexity
Solution Approach 1:
The patent applies periodic action by implementing periodic idle states where the feedback channel is switched to ground or disconnected from transmit channels at regular intervals. During these periodic idle periods, the system collects interference signals cleanly, then returns to normal transmission mode, creating a rhythmic cycle of interference measurement and cancellation that simplifies the switching control logic.
Data Source
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AI summary
Embodiments of the present invention provide a transmitter and an interference cancellation method. The transmitter provided in the embodiments of the present invention includes: a feedback cancellation module, a first digital predistorter DPD and a power amplifier PA, where the feedback cancellation module is located on a feedback channel of the transmitter, and the feedback cancellation module is separately connected to the PA and the first DPD; the feedback cancellation module is configured to perform, according to a feedback cancellation signal, interference cancellation on a signal of the feedback channel, to acquire a first mixed signal, and send the first mixed signal to the first DPD; the first DPD is configured to perform linear predistortion processing according to a first baseband signal on a first transmit channel and the first mixed signal, to generate a first predistortion signal; and the PA is configured to amplify a to-be-transmitted signal and then transmit the signal by using an antenna, where the to-be-transmitted signal is the first predistortion signal or a signal obtained according to the first predistortion signal. The embodiments of the present invention can reduce distortion of a transmit signal.