OFDM Protection-Edge Tones for UWB Interference Cancellation
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Solution Overview
Problem
Current wireless communication technologies face challenges in effectively canceling in-band interference in ultra-wide band (UWB) systems without causing spectrum overshoot, particularly when coexisting with conventional service bands like radio astronomy bands, where traditional methods like notch filtering are costly or inefficient.
Innovation Solution
The implementation of active interference cancellation (AIC) tones and protection-edge tones, determined through optimization, to collectively achieve the required attenuation without excessive bandwidth sacrifice, using a combination of digital signal processing and time-domain windowing to suppress interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional notch filtering is used to cancel interference in victim frequency bands, then interference cancellation is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts and removes the harmful interference components from the transmitted signal by setting specific subcarrier tones to zero in the frequency domain, rather than using complex physical filtering. This digital cancellation approach eliminates the need for expensive analog notch filters while achieving the same interference suppression effect in the victim frequency bands
Solution Approach 2:
The patent replaces the mechanical/analog notch filtering system with a digital signal processing approach. By using software-based interference cancellation through optimized tone selection and power constraint management, the system substitutes complex hardware filtering with computationally efficient digital operations, reducing device complexity and cost
2Object-affected harmful factors
If interference cancellation tones are increased to achieve better attenuation, then interference suppression improves, but bandwidth is excessively sacrificed
Solution Approach 1:
The patent changes the optimization parameters by introducing power constraints on the interference cancellation tones. Instead of simply increasing the number of canceled tones, the system optimizes the power distribution across tones subject to average power constraints, achieving better interference attenuation with more efficient bandwidth utilization through parameter-optimized signal design
Solution Approach 2:
The patent applies partial action by selectively canceling only the specific tones that cause interference in victim bands, rather than excessively canceling all tones. This targeted approach achieves sufficient attenuation (23 dB) without unnecessarily sacrificing bandwidth, optimizing the balance between interference suppression and data throughput
3Productivity
If power limits are exceeded to maintain communication throughput, then communication performance is maintained, but regulatory compliance is violated
Solution Approach 1:
The patent implements feedback through iterative optimization that monitors and enforces average power constraints on the interference cancellation tones. The system adjusts the tone power distribution based on the constraint feedback, ensuring regulatory compliance while maintaining communication throughput through optimized power allocation rather than brute-force power increases
Data Source
AI summary
A method of wirelessly communicating is disclosed. The method comprises determining a matrix W based in part on limiting a plurality of active interference cancellation tone values (416), determining the active interference cancellation tone values (416) based on W and based on a plurality of information data values (410), and transmitting an orthogonal frequency division multiplex signal (310) based on the plurality of active interference cancellation tone values (416) and the information data values (410).