Interference Detection in Distributed Base Stations via IQ Data Analysis

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Solution Overview

Problem

Wireless networks face challenges in detecting and managing interference, particularly intermodulation signals, due to their complex frequency-time nature and overlap with desired signals, which limits their ability to meet consumer demands for speed, capacity, and quality over limited spectrum resources.

Innovation Solution

A distributed base station system with a tester that extracts complex digitized signals from the front-haul communication link between the BBU and RRH, applying signal processing and statistical algorithms to detect interfering signals, including intermodulation, by measuring peak-to-average power ratio, kurtosis, and cyclic frequency, and using spectral estimation to identify and isolate interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Difficulty of detecting and measuring

If spectral estimation is performed on uplink signals to detect interference, then interference detection capability is improved, but measurement precision deteriorates when desired signals are bursty and overlap in frequency-time with intermodulation signals

Engineering Contradiction:

Improveinterference detection capabilityVSAvoidsignal measurement accuracy

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent segments the frequency-time domain analysis by processing signals in discrete time slots and frequency bins. The system divides the continuous signal into manageable segments, analyzing each segment's spectral characteristics to identify interference patterns that would be invisible in a single continuous spectrum plot.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension of analysis by transforming the traditional two-dimensional spectrum plot into a three-dimensional representation that includes time, frequency, and signal strength dimensions. This allows bursty signals and intermodulation products to be visualized and distinguished across multiple dimensions, making them detectable even when they overlap in traditional spectral plots.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If the frequency spectrum is increased to meet consumer demands for speed and capacity, then network capacity is improved, but interference from unintended transmissions and inter-modulation signals increases

Engineering Contradiction:

Improvenetwork capacityVSAvoidinterference from unintended transmissions

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the system continuously monitors the uplink signals for interference signatures and feeds this information back to the network controller. Based on this feedback, the system can dynamically adjust transmission parameters, allocate frequencies, or trigger interference management procedures to maintain network capacity while reducing harmful interference effects.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent converts the harmful interference signals into useful diagnostic information by analyzing their spectral and temporal characteristics. The intermodulation products and unintended transmissions, which were previously merely noise, are now identified as distinct signal patterns that provide information about the network's operational state and can be used to optimize frequency allocation and transmission parameters.

Inventive Principle:

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

3Adaptability or versatility

If downlink intermodulation signals are transmitted in the uplink band, then spectrum utilization is improved, but signal isolation becomes difficult when signals overlap in time and frequency

Engineering Contradiction:

Improvespectrum utilizationVSAvoidsignal isolation capability

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent employs dynamic signal processing that adapts to the time-varying nature of wireless communications. The system continuously updates its spectral estimates and interference models based on real-time signal conditions, allowing it to dynamically distinguish between desired uplink signals and downlink intermodulation products even when they overlap in frequency, thereby maintaining spectrum utilization efficiency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the analysis parameters from traditional single-frequency spectral plots to multi-dimensional parameter spaces that include time, frequency, signal strength, and signal type dimensions. This parameter transformation allows the system to resolve overlapping signals by analyzing their different characteristics across multiple parameters, making isolation possible even when signals coincide in traditional frequency-time plots.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10609582B2Interference detection and identification in wireless network from RF or digitized signal

Publication Date: 2020.03.31 OUTDOOR WIRELESS NETWORKS LLC

AI summary

A method for detecting interference in a wireless system is disclosed. The method includes receiving an uplink signal at a remote radio head in a distributed base station, passing the uplink signal from the remote radio head to a baseband unit over a front-haul communication link as baseband IQ data, and intercepting the baseband IQ data at a tester coupled between the remote radio head and the baseband unit. Processing of the IQ data is performed to determine whether an interfering signal is present in the uplink signal.