Digital RF Canceller for Real-Time Full-Duplex Interference Removal

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Solution Overview

Problem

Current RF interference cancellation techniques, especially in full-duplex communication systems, face challenges in achieving real-time operation due to high computational requirements and inefficiencies in separating transmitted and received signals, often relying on hardware-based solutions that are complex and not adequately effective.

Innovation Solution

A method and system utilizing a digital adaptive filter with a tap weight estimator that processes only a subset of data frames, allowing for real-time RF interference cancellation by time-aligning and phase-aligning the transmitted and received signals, reducing computational complexity through decimation or interpolation of tap weight values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If hardware RF cancellers are used for interference cancellation, then interference cancellation capability is improved, but device complexity increases and adequate canceling is not achieved

Engineering Contradiction:
Improveinterference cancellation capabilityVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces hardware-based RF cancellers with a software-based digital signal processing approach. The system uses analog-to-digital converters to transform RF signals into digital domain, where adaptive filtering algorithms perform interference cancellation. This substitution of mechanical/hardware systems with software/digital processing resolves the contradiction by achieving adequate canceling performance without the complexity of multiple hardware cancellation filters.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating domain from analog RF domain to digital baseband domain. By converting signals to digital form and performing cancellation operations in the digital domain with adjustable tap weights, the system achieves flexible and adequate interference cancellation. The parameter changes include transitioning from fixed hardware filtering to adaptive digital filtering with dynamically adjustable coefficients.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If full-band cancellers are used to cancel transmission components, then interference cancellation is improved, but real-time operation cannot be achieved due to extensive computational requirements

Engineering Contradiction:
Improveinterference cancellation capabilityVSAvoidreal-time operation capability
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent segments the computational workload by processing data in frames and calculating tap weight values for only a subset of frames. Instead of performing full computational processing on every incoming sample, the system divides the continuous signal stream into discrete frames and selectively processes representative subsets, enabling real-time operation while maintaining adequate cancellation performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by calculating tap weight values for only a subset of data frames rather than every frame. The system estimates or interpolates tap weights for intermediate frames based on calculated values from subset frames, achieving acceptable cancellation performance with reduced computational effort that enables real-time operation.

Inventive Principle:
Principle #16Partial or excessive action

3Object-affected harmful factors

If multiple cancellation filters are used in hardware-based canceling systems, then interference cancellation is improved, but device complexity and computational requirements increase

Engineering Contradiction:
Improveinterference cancellation capabilityVSAvoidnumber of cancellation filters
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges multiple hardware cancellation filters into a single software-based adaptive filtering system. Instead of implementing separate physical filters for different frequency bands or signal paths, the system uses a unified digital signal processing architecture where a single adaptive filter with adjustable tap weights performs cancellation across the entire bandwidth, significantly reducing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a universal software-based cancellation system that can handle multiple signal types, frequency bands, and interference scenarios through a single adaptive filtering framework. The same digital signal processing architecture and algorithm can be configured for different applications by adjusting parameters and tap weights, eliminating the need for dedicated hardware filters for each specific case.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS20170141910A1Systems and methods for real-time operation of software radio frequency canceller
Publication Date: 2017.05.18 BLUE RIDGE INNOVATIONS LLC
  • US20170141910A1 patent drawing
  • US20170141910A1 patent drawing
  • US20170141910A1 patent drawing

AI summary

A full-duplex RF communication system and corresponding methods use digital adaptive filters for interference cancellation. As provided, the techniques allow full-duplex radio frequency communication without frequency-, time-, or code-division multiplexing and without the use of hardware RF cancellers, in real-time. Such techniques may be useful for wireless communication, such a cellular communication, radio communication, broadcasting, short-range point-to-point communication, wireless sensor networks, and wireless computer networks.