Converged LMR LTE Device Interference Mitigation

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Solution Overview

Problem

Converged communication devices operating on both Land Mobile Radio (LMR) narrowband and Long Term Evolution (LTE) broadband systems face interference issues, particularly when LMR signals are weak, which can disrupt communication.

Innovation Solution

The solution involves modifying the data flow and data rate of the LTE modem based on channel conditions, enabling or disabling applications according to interference levels, and controlling data rate using Quality of Service (QoS) priority, while considering LTE RSRP, LMR RSSI, and band combinations to minimize interference between LMR and LTE systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the device operates on both LMR narrowband and LTE broadband systems simultaneously, then communication versatility is improved, but interference between the two systems increases

Engineering Contradiction:

Improvecommunication versatilityVSAvoidinterference between LMR and LTE systems

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic adjustment of LTE data rates based on LMR signal conditions. The system continuously monitors LMR RSSI and RSRP values and adapts LTE transmission parameters in real-time, switching between different data rate modes (full, reduced, minimal) to minimize interference with LMR communications while maintaining LTE connectivity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes key transmission parameters including LTE data rate, modulation scheme, and power allocation based on detected LMR signal strength. When LMR signals are detected below threshold levels, the system reduces LTE data rates and adjusts transmission parameters to reduce spectral overlap and interference with narrowband LMR communications.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If LTE data rate is increased for better data communication, then productivity is improved, but interference with LMR signals increases

Engineering Contradiction:

Improvedata communication rateVSAvoidinterference with LMR signals

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts LTE data rates based on real-time LMR signal conditions. It implements multiple operational modes (full data rate, reduced data rate, minimal data rate) and transitions between them based on LMR RSSI and RSRP measurements, ensuring high productivity when LMR interference is low and reducing LTE throughput when LMR signals are weak.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs feedback mechanisms where the system continuously monitors LMR signal strength (RSSI) and reference signal received power (RSRP), then uses this feedback to adjust LTE transmission parameters. The closed-loop control ensures that LTE data rates are optimized based on current LMR channel conditions, preventing interference while maintaining maximum possible productivity.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If LTE applications are enabled for full functionality, then adaptability is improved, but interference generation increases

Engineering Contradiction:

Improveapplication functionalityVSAvoidinterference generation

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The system implements partial action by selectively enabling or disabling LTE applications based on LMR signal conditions. When LMR interference thresholds are exceeded, the system disables non-critical LTE applications and data transmissions while maintaining essential communications, thereby reducing overall interference generation while preserving core functionality.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent applies different quality levels to different LTE applications based on their criticality and interference characteristics. Essential applications maintain full functionality while non-critical applications are restricted or disabled when LMR signals are weak, creating localized quality adjustments that reduce overall interference while maintaining necessary adaptability.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP3963760B1Method and device to minimize interference in a converged LMR/LTE communication device

Publication Date: 2022.10.26 MOTOROLA SOLUTIONS INC

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AI summary

A method and converged LMR/LTE communications device provide for minimizing interference in the converged LMR/LTE communications device that operates in a land mobile radio (LMR) narrowband communication system and a long term evolution (LTE) broadband communication system. The converged LMR/LTE communications device detects, using an electronic processing device, that the converged LMR/LTE communications device is operating in the first LTE band and the first LMR band. The converged LMR/LTE communications device determines that a first LMR received signal strength indicator (RSSI) at the converged LMR/LTE communications device is less than a first LMR threshold signal strength and disables at least one LTE application based upon the first LMR RSSI being less than the LMR threshold signal strength.