Dynamic Carrier Adjustment for LTE Interference Mitigation

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Solution Overview

Problem

The increasing demand for mobile device usage leads to interference issues due to unwanted out-of-band emissions from power amplifiers in mobile devices, particularly when operating in adjacent frequency bands, which current filter technologies cannot adequately mitigate, resulting in reduced system capacity and battery life.

Innovation Solution

A communication system that adjusts the carrier frequency when interference exceeds a threshold, using a combination of Physical Uplink Control Channel (PUCCH) over-dimensioning and tighter power output limitations, along with a carrier selection module that dynamically selects a secondary radio frequency carrier to minimize interference, employing voltage-controlled oscillators to generate different carriers and a direct converter transmitter to manage resource block allocations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If current filter technologies are used to mitigate out-of-band emissions, then interference reduction is attempted, but the filtering is inadequate and system capacity is reduced

Engineering Contradiction:

Improveinterference from out-of-band emissionsVSAvoidsystem capacity

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent changes the frequency parameter of the carrier wave dynamically. When interference is detected in adjacent bands, the system adjusts the carrier frequency to a different value, thereby moving the out-of-band emissions to different frequencies that cause less interference. This parameter change allows the system to maintain capacity while reducing harmful emissions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system transitions from static filtering to dynamic carrier adjustment. The carrier frequency is no longer fixed but is adjusted in real-time based on interference conditions. This dynamic approach allows the system to adapt to changing spectral environments, reducing interference while maintaining system capacity.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If power output limitations are tightened to reduce interference, then out-of-band emissions are reduced, but power efficiency decreases and battery life is reduced

Engineering Contradiction:

Improveout-of-band emissionsVSAvoidpower efficiency and battery life

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

Instead of reducing power output, the system changes the frequency parameter of the carrier. By adjusting the carrier frequency away from values that cause adjacent band interference, the system can maintain full power output while still reducing out-of-band emissions. This preserves power efficiency and battery life.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The carrier frequency adjustment acts as an intermediary mechanism between power output and interference reduction. Rather than directly reducing power to mitigate interference, the system uses frequency adjustment as an intermediate step to achieve interference reduction while maintaining power efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If carrier frequency is adjusted to minimize interference, then adjacent band interference is reduced, but device complexity increases

Engineering Contradiction:

Improveadjacent band interferenceVSAvoidcarrier selection and adjustment mechanism

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The system implements a feedback mechanism where interference levels in adjacent bands are monitored, and based on this feedback, the carrier frequency is adjusted. The interference measurement unit provides continuous feedback about spectral conditions, and the carrier selection unit uses this feedback to dynamically adjust the carrier frequency, creating a closed-loop control system that reduces interference automatically.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs self-adjustment of carrier frequency based on its own interference measurements. The terminal autonomously monitors its own out-of-band emissions and adjusts its carrier frequency accordingly without requiring external intervention, reducing the need for complex external control mechanisms.

Inventive Principle:

Principle #25Self-service

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 approach effectively reduces interference between adjacent frequency bands, maintaining system capacity and power efficiency while extending battery life by dynamically adjusting carriers based on interference levels.

Implementation Method 1

employing voltage-controlled oscillators to generate different carriers

Methodology Applied

Scientific EffectVoltage-controlled oscillation:

Data Source

PatentUS8923877B2Method and apparatus for providing carrier adjustment to mitigate interference

Publication Date: 2014.12.30 VERIZON PATENT & LICENSING INC

AI summary

An approach is provided for mitigating interference from Long Term Evolution (3GPP LTE) terminals to adjacent frequency bands. A platform determines whether a region associated with transmission of one or more resource blocks are an interfering region according to predetermined criteria, where one or more resource blocks are assigned a primary carrier as a default carrier for the transmission. The platform selects a secondary carrier for the one or more resource blocks instead of the primary carrier if the region is determined to be interfering.