RF EMF Power Control for 5G Base Stations
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Solution Overview
Problem
The introduction of Active Antenna Systems (AAS) in 4G/5G base stations increases beamforming gain, leading to larger RF Electric and Magnetic Field (EMF) exclusion zones, making deployment challenging in dense urban environments, as traditional methods for calculating exclusion zones are based on maximum Equivalent Isotropically Radiated Power (EIRP) and do not account for time-averaging of power density.
Innovation Solution
Implementing a power control method that computes the average total transmit power over a control period and adjusts the Physical Resource Block (PRB) limits to ensure the time-averaged power remains below a predetermined threshold, using power scaling and PRB limitation to reduce the exclusion zone while maintaining capacity and coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Active Antenna Systems (AAS) with beamforming are deployed to increase network capacity and coverage, then beamforming gain is improved, but RF EMF exclusion zones are enlarged making deployment challenging
Solution Approach 1:
The patent implements dynamic power control that adjusts transmit power levels in real-time based on instantaneous power measurements. The system dynamically scales power across resource blocks and time to maintain average power within regulatory limits while maximizing instantaneous capacity utilization, thereby reducing exclusion zones without sacrificing network productivity
Solution Approach 2:
The system employs periodic power averaging over defined time intervals to comply with RF exposure regulations. By controlling the time-averaged power rather than instantaneous peak power, the system allows higher instantaneous transmission for capacity while ensuring the averaged power remains within safe limits, effectively reducing exclusion zone requirements
2Reliability
If traditional maximum EIRP methods are used for exclusion zone calculation, then compliance with RF exposure regulations is ensured, but deployment flexibility is reduced in dense urban environments
Solution Approach 1:
The patent changes the control parameter from maximum EIRP to time-averaged power. By measuring and controlling the average power over time intervals rather than peak instantaneous power, the system maintains RF exposure compliance while enabling more flexible deployment scenarios where higher instantaneous powers can be utilized temporarily, increasing adaptability in dense urban environments
3Area of stationary object
If power scaling is applied to reduce average power levels, then exclusion zones are reduced, but capacity and coverage may be impacted
Solution Approach 1:
The system applies dynamic power scaling that adjusts power levels based on real-time conditions. During periods when average power is below regulatory thresholds, the system can increase instantaneous power to maintain capacity and coverage. The scaling is applied selectively across different resource blocks and time intervals, ensuring exclusion zone requirements are met while minimizing impact on network productivity
Solution Approach 2:
The patent implements partial power scaling where only sufficient power reduction is applied to meet average power requirements, not excessive reduction. The system scales power just enough to comply with RF exposure limits while maintaining maximum possible capacity and coverage, avoiding unnecessary degradation of network performance
Data Source
AI summary
Systems and methods are disclosed for power assisted Radio Frequency (RF) Electric and Magnetic Field (EMF) average power control for a Radio Access Network (RAN) node of a cellular communications system. In one embodiment, a method of operation of a controller for a RAN node comprises computing an average total transmit power over a control period and computing an initial Physical Resource Block (PRB) limit for transmission of a Physical Downlink Shared Channel (PDSCH) for the cell based on a comparison of the computed average and a reference. The method further comprises determining whether power scaling is to be used, adjusting the initial PRB limit and providing the adjusted PRB limit and a power scaling indication to a scheduler associated to the cell if power scaling is to be used, and otherwise providing the initial PRB limit and an indication of no power scaling to the scheduler.