Wireless Uplink Duty Cycle Adjustment for RF Exposure Compliance

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Solution Overview

Problem

Existing wireless communication technologies face challenges in providing efficient and satisfactory wireless communications while ensuring compliance with regulatory limits on radio-frequency exposure, particularly due to static maximum uplink duty cycles and reliance on maximum power reductions, which can lead to reduced uplink coverage and radio link failures.

Innovation Solution

A wireless network system that dynamically adjusts the maximum uplink duty cycle based on proximity detection, allowing user equipment to transmit an indicator to the base station, which in turn adjusts the uplink schedule to maintain compliance with RF exposure regulations without requiring maximum transmit power reductions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If maximum power reductions are applied to ensure RF exposure compliance, then RF exposure limits are satisfied, but uplink coverage and throughput are reduced

Engineering Contradiction:
ImproveRF exposure complianceVSAvoiduplink throughput
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent implements dynamic adjustment of the uplink duty cycle based on real-time proximity detection results. Instead of static power reductions, the system dynamically modifies the duty cycle parameter to adapt to changing conditions, allowing optimal balance between RF exposure compliance and uplink performance

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the duty cycle parameter rather than directly reducing transmit power. By modifying the duty cycle (the proportion of time the transmitter is active), the system achieves RF exposure compliance while maintaining higher instantaneous power levels when needed, thereby preserving uplink coverage and throughput

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If static maximum uplink duty cycle is used, then device complexity is reduced, but adaptability to RF exposure conditions deteriorates

Engineering Contradiction:
Improveduty cycle controlVSAvoidRF exposure adaptability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The user equipment performs self-detection of proximity conditions using onboard sensors and autonomously determines appropriate duty cycle adjustments. This self-service approach enables adaptability to RF exposure conditions without requiring complex network-side control or additional infrastructure

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system implements a feedback mechanism where proximity detection results are continuously monitored and used to adjust the duty cycle. The UE reports proximity status to the network, which then provides feedback signals to confirm or modify the duty cycle settings, creating a closed-loop control system that adapts to changing conditions

Inventive Principle:
Principle #23Feedback

3Object-affected harmful factors

If rapid coordination of duty cycle adjustments is implemented, then RF exposure compliance is maintained, but communication overhead increases

Engineering Contradiction:
ImproveRF exposure complianceVSAvoidcommunication overhead
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The system applies partial coordination by allowing the UE to autonomously determine duty cycle adjustments based on proximity detection, requiring network confirmation only for significant changes. This partial action approach maintains RF exposure compliance while reducing the frequency and volume of coordination messages compared to full centralized control

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4604645A1Systems and methods for controlling radio-frequency exposure
Publication Date: 2025.08.20 APPLE INC
  • EP4604645A1 patent drawingFigure 1
  • EP4604645A1 patent drawingFigure 2
  • EP4604645A1 patent drawingFigure 3

AI summary

A wireless network may include a base station and user equipment (UE). The UE may transmit uplink (UL) signals to the base station using a dynamically adjustable maximum UL duty cycle. When the UE identifies that a user is in proximity to the UE, the UE may transmit an indicator to the base station. The indicator may identify that a radiofrequency exposure (RFE) event has occurred and/or a suggested maximum UL duty cycle that would allow the UE to satisfy limits on RFE. The base station may limit a UL grant to the UE so that the UE performs subsequent communications using the suggested maximum UL duty cycle or a different maximum UL duty cycle. Coordinating adjustment of UL duty cycle in this way may allow the UE to meet limits on RFE without requiring the UE to perform maximum transmit power level reductions.