Antenna Array Beam Switching for EMF Compliance

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Solution Overview

Problem

Current wireless communication networks face restrictive electromagnetic field (EMF) exposure limits at frequencies above 6 GHz, particularly for devices near the human body, limiting transmission power and requiring innovative solutions to maintain quality of service while complying with regulations.

Innovation Solution

A transmitting node with independently controllable antenna elements that switches between different beams or subsets to optimize transmission power, utilizing spatial and temporal spreading to reduce average power per area or volume, ensuring compliance with EMF exposure limits by alternating transmission patterns over defined time intervals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If transmission power is increased to improve coverage and capacity, then service quality is improved, but EMF exposure limits are exceeded

Engineering Contradiction:
Improvetransmission powerVSAvoidEMF exposure
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The antenna array is divided into multiple independently controllable antenna elements or subsets. Different subsets are activated at different time intervals to transmit signals, thereby segmenting the total transmission power across multiple elements rather than using all elements simultaneously at full power.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The transmitting node periodically switches between different antenna subsets in a time-division manner. Each subset is activated for a specific time interval, then switched to another subset, creating a periodic transmission pattern that distributes EMF exposure over time while maintaining overall transmission power levels.

Inventive Principle:
Principle #19Periodic action

2Productivity

If multiple antenna elements are used to increase transmission power, then coverage and capacity are improved, but average EMF exposure increases

Engineering Contradiction:
Improvecoverage and capacityVSAvoidaverage EMF exposure
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts which antenna elements are active at any given time, switching between different configurations based on transmission requirements and EMF exposure considerations. This dynamic switching allows the system to maintain high productivity when needed while controlling average EMF exposure over time.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The transmitting node changes operational parameters by switching between different antenna subsets and adjusting transmission timing. This parameter changes approach allows the system to optimize coverage and capacity while managing EMF exposure levels through temporal and spatial distribution of transmissions.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If continuous transmission is used to maintain service quality, then signaling quality is maintained, but EMF exposure limits are exceeded

Engineering Contradiction:
Improvesignaling qualityVSAvoidEMF exposure
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Instead of continuous transmission, the system employs periodic transmission intervals with switching between antenna subsets. This periodic action maintains signaling quality by ensuring transmissions occur at regular intervals while reducing peak EMF exposure by not using all antenna elements simultaneously.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system maintains continuous useful action through rapid switching between antenna subsets, ensuring that transmission service is continuously available while the actual EMF exposure is distributed over time. The switching occurs fast enough to maintain service continuity but slow enough to allow EMF averaging.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP3427337B1EMF-limit compliant transmission with multiple antenna elements
Publication Date: 2020.01.08 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3427337B1 patent drawingFigure 1
  • EP3427337B1 patent drawingFigure 2
  • EP3427337B1 patent drawingFigure 3

AI summary

The present disclosure pertains to a transmitting node (10) for a wireless communication network. The transmitting node (10) is adapted for transmission utilizing independently controllable antenna elements of an antenna arrangement (24). Moreover, the transmitting node (10) is adapted for switching between different beams and/or subsets of the antenna elements for transmission based on transmitted power in relation to EMF exposure limits. There are also disclosed related devices and methods.