eNodeB Signal Masking via CAZAC Guard Band Spreading

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Solution Overview

Problem

Passengers on aircraft face interference and network disturbances due to high-speed and altitude-related issues with mobile RF communication devices trying to maintain connectivity with terrestrial networks, and existing solutions require separate masking signal generators and may not effectively block terrestrial communication signals across the entire LTE channel bandwidth.

Innovation Solution

An eNodeB system that parallelizes information data streams over LTE transmission channels with guard bands, using CAZAC sequences to spread data across orthogonal subcarriers, including pilot and sensor information, to effectively mask terrestrial communication signals without separate masking signal generators, and fills unused subcarriers to enhance jamming capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate masking signal generators are used to block terrestrial communication signals, then masking effectiveness is improved, but device complexity and cost increase

Engineering Contradiction:

Improvemasking effectivenessVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The eNodeB's existing transmission resources (data streams, subcarriers, guard bands) are made to serve dual purposes: normal LTE communication and masking of terrestrial signals. By spreading CAZAC sequences over guard band subcarriers, the system achieves masking functionality without adding separate masking signal generators, thus reducing device complexity while maintaining masking effectiveness.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If guard bands are left unused in LTE transmission, then interference between carriers is reduced, but spectrum efficiency decreases

Engineering Contradiction:

Improvechannel estimation performanceVSAvoidspectrum efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The guard bands, which are traditionally left unused to prevent interference but represent wasted spectrum resources, are converted into useful resources for masking. By spreading CAZAC sequences over these guard band subcarriers, the system transforms the harmful effect of unused spectrum into a beneficial masking function that blocks terrestrial communication signals while maintaining the original interference-protection purpose of guard bands.

Inventive Principle:

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

3Reliability

If mobile RF devices operate at full power to maintain connectivity at high altitude and speed, then communication reliability is improved, but RF interference with onboard equipment increases

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidRF interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The system applies preliminary anti-action by transmitting masking signals (CAZAC sequences) over guard band subcarriers before terrestrial communication signals can be received. This pre-established masking field proactively counteracts the harmful RF interference that would otherwise affect onboard electronic equipment, allowing mobile devices to operate at full power for reliable communication without causing interference issues.

Inventive Principle:

Principle #9Preliminary anti-action

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

The solution provides efficient masking of terrestrial communication signals across the LTE channel bandwidth, reduces weight and power consumption, and allows for cost-effective implementation by using software modifications, while maintaining LTE service and offering 2G services alongside LTE, thereby improving communication stability and quality.

Implementation Method 1

spreading the first information data stream over a plurality of mutually orthogonal data subcarriers within the first channel transmission bandwidth

Methodology Applied

Scientific EffectOrthogonal Frequency Division Multiplexing (OFDM):

Implementation Method 2

generating a CAZAC sequence; spreading the generated CAZAC sequence over guard band subcarriers within the at least one guard band

Methodology Applied

Scientific EffectCAZAC sequence spreading:

Data Source

PatentUS9923662B2Method for masking communication signals, enodeb with masking functionality and aircraft

Publication Date: 2018.03.20 AIRBUS OPERATIONS GMBH

AI summary

A method for masking communication signals, particularly for masking terrestrial RF communication signals on board of an aircraft, includes parallelizing a first information data stream to be transmitted on a first LTE transmission channel, the first LTE transmission channel having a first channel transmission bandwidth and at least one guard band adjacent to the channel transmission bandwidth; spreading the first information data stream over a plurality of mutually orthogonal data subcarriers within the first channel transmission bandwidth; generating a CAZAC sequence; spreading the generated CAZAC sequence over guard band subcarriers within the at least one guard band; and transmitting the first information data stream over the data subcarriers in parallel to the CAZAC sequence over the guard band subcarriers.