Wireless Backhaul Frequency Reuse via Interference Cancellation

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Solution Overview

Problem

Conventional microwave backhaul architectures face challenges in efficiently managing increased capacity demands and interference, leading to high costs due to the need for multiple frequency bands to avoid inter-hop interference, which limits spectrum efficiency and increases operational expenses.

Innovation Solution

The system employs a parabolic dish antenna complemented with auxiliary isotropic antennas and digital signal processing to cancel interfering signals, allowing for frequency reuse by pre-adjusting gain and using a signal processing module to extract the desired signal, thereby reducing the need for multiple frequency bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple frequency bands are used to avoid inter-hop interference, then interference between backhaul links is reduced, but spectrum efficiency decreases and operational costs increase

Engineering Contradiction:

Improveinterference avoidanceVSAvoidspectrum efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent converts the harmful interference from co-channel backhaul links into a manageable signal by using auxiliary antennas to capture the interferer signal and digital signal processing to cancel it out. This allows frequency reuse without requiring multiple frequency bands, thereby improving spectrum efficiency while maintaining reliability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces auxiliary antennas and digital signal processing as intermediary components between the parabolic dish antenna and the receiver. These intermediaries enable the system to handle co-channel interference by capturing and processing the interferer signal separately, then subtracting it from the combined signal to recover the desired signal.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If multiple frequency bands are used to avoid inter-hop interference, then link reliability is improved, but operational expenses increase

Engineering Contradiction:

Improvelink reliabilityVSAvoidoperational expenses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent makes a single frequency band serve multiple backhaul links simultaneously through frequency reuse. The auxiliary antennas and signal processing system enable co-channel operation, allowing the same frequency to be universally used across multiple links without causing harmful interference, thereby reducing the need for multiple frequency bands and lowering operational expenses.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If frequency reuse is implemented without interference cancellation, then spectrum efficiency improves, but signal quality deteriorates due to co-channel interferers

Engineering Contradiction:

Improvespectrum efficiencyVSAvoidsignal quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent segments the received signal into two components: the desired signal from the parabolic dish antenna and the interferer signal from auxiliary antennas. By separately capturing and processing these segmented signals, the system can cancel the interferer component while preserving the desired signal, thereby maintaining signal quality during frequency reuse.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses feedback from the auxiliary antennas that continuously monitor the interferer signal. This feedback information is fed into the digital signal processing system, which adjusts the cancellation in real-time to maintain optimal signal quality while enabling frequency reuse.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables efficient frequency reuse, preserving link-planned SNR even in the presence of co-channel interferers, allowing operators to reduce spectrum holding costs and simplify network frequency planning by using a single frequency band, while maintaining robustness against interference.

Implementation Method 1

a parabolic dish antenna complemented with auxiliary isotropic antennas

Methodology Applied

Scientific EffectParabolic focusing: Focusing

Implementation Method 2

digital signal processing to cancel interfering signals, allowing for frequency reuse by pre-adjusting gain and using a signal processing module to extract the desired signal

Methodology Applied

Scientific EffectSignal cancellation: Interference

Data Source

PatentUS10243601B2System and method for frequency reuse for wireless point-to-point backhaul

Publication Date: 2019.03.26 MAXLINEAR ASIA SINGAPORE PTE LTD

AI summary

A system and method for frequency reuse for wireless point-to-point backhaul. Frequency reuse is enabled through the cancellation of interfering signals generated by interference sources. In one embodiment, a conventional dish antenna is complemented with one or more additional auxiliary antennas (e.g., isotropic). The one or more additional auxiliary antennas enable cancellation of interfering signals whose direction of arrival (DOA) is off the dish antenna's bore-sight.