Blocking Signal Cancellation via Reference Signal Compensation
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Solution Overview
Problem
In wireless communication systems, particularly in public safety contexts, the issue arises when a blocking signal overpowering a desired signal within a shared radio channel, making it difficult to filter out the blocking signal without degrading the desired signal's reception.
Innovation Solution
A method and system for generating a reference signal to cancel the blocking signal by modulating blocking bits, passing them through bandpass filters to identify signal parameter differences, and applying compensations to produce a conditioned reference signal for use in a blocking-signal-canceling system, such as an adaptive-noise-cancellation system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a narrow filter is applied to filter out the blocking signal, then the blocking signal is reduced, but the desired signal is degraded
Solution Approach 1:
The patent extracts the blocking signal from the composite received signal by generating a reference signal that replicates the blocking signal's characteristics. This reference signal is then subtracted from the received signal to isolate and remove the blocking component, allowing the desired signal to be recovered without using narrow filtering that would degrade the desired signal.
Solution Approach 2:
The patent changes parameters of the reference signal (amplitude, phase, frequency) to match the blocking signal's parameters. By dynamically adjusting these parameters based on channel conditions and blocking signal characteristics, the system creates an accurate replica that can be effectively canceled without affecting the desired signal spectrum.
2Object-affected harmful factors
If a narrow filter is used to limit blocking signal energy, then blocking signal power is reduced, but the filter bandwidth becomes too narrow to pass the desired signal
Solution Approach 1:
Instead of using a narrow filter that would cut off the desired signal, the patent extracts the blocking signal component through reference signal generation and subtraction. This allows the full bandwidth filter to pass both desired and blocking signals, after which the blocking signal is removed through signal processing rather than frequency filtering.
Solution Approach 2:
The patent introduces a reference signal as an intermediary that represents the blocking signal. This reference signal acts as a mediator between the received composite signal and the isolated desired signal, enabling the separation of blocking and desired components without requiring narrowband filtering.
3Power
If the blocking signal power is significantly higher than the desired signal power, then the blocking signal dominates the channel, but filtering becomes ineffective without degrading the desired signal
Solution Approach 1:
The patent converts the harmful high-power blocking signal into a useful reference signal. By utilizing the blocking signal's own characteristics (through pilot tones or known patterns) to generate a reference signal, the system transforms the interference into a tool for cancellation, making the solution feasible even when the blocking signal is much stronger than the desired signal.
Solution Approach 2:
The patent employs feedback mechanisms to continuously adjust the reference signal parameters based on the blocking signal's actual characteristics. This adaptive feedback allows the system to track and cancel the blocking signal effectively, maintaining cancellation performance despite variations in blocking signal power and channel conditions.
Data Source
AI summary
Disclosed herein are methods and systems for canceling a blocking signal to obtain a desired signal. An example process includes receiving both a blocking signal and a set of blocking bits corresponding to a demodulation of the blocking signal. A remodulated blocking signal is generated by modulating the received set of blocking bits. The remodulated blocking signal is passed through a blocking-band bandpass filter to generate an estimated blocking signal, and is also passed through a desired-band bandpass filter to generate an unconditioned reference signal. One or more signal-parameter differences between the blocking signal and the estimated blocking signal are identified, and one or more signal compensations are accordingly applied to the unconditioned reference signal to generate a conditioned reference signal, which is then output to a blocking-signal-canceling system.