Directional EMF Power Control for Cell Throughput
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Solution Overview
Problem
Existing wireless communication systems face challenges in managing RF exposure limitations, leading to reduced downlink throughput and cell coverage due to cell-wide EMF limit enforcement strategies, particularly when users are spatially distributed.
Innovation Solution
Implementing multiple spatial controllers associated with EMF sectors, using beamforming gain and link adaptation to calculate and enforce EMF limits for each sector, and employing bandwidth limiting strategies for cell-edge users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cell-wide EMF limit enforcement strategy is used, then RF exposure compliance is ensured, but downlink throughput is significantly reduced
Solution Approach 1:
The patent divides the cell into multiple spatial sectors and implements separate EMF limit enforcement for each sector. This allows the system to maintain RF exposure compliance while enabling higher throughput in sectors with favorable EMF conditions, rather than applying a uniform cell-wide limitation that restricts all users equally.
Solution Approach 2:
The patent applies different EMF limiting mechanisms to different spatial locations within the cell. By calculating sector-specific EMF limits based on directional power transmission and spatial distribution of users, the system allows local optimization of throughput in each sector while ensuring overall RF exposure compliance across the entire cell.
2Reliability
If cell-wide power scaling is applied, then EMF average power limit is met, but cell coverage is reduced
Solution Approach 1:
The patent segments the power control mechanism by spatial sector, allowing different power scaling factors to be applied in different directions. This enables the system to meet the average power limit requirement while maintaining adequate coverage in sectors where power can be transmitted at higher levels without exceeding directional EMF constraints.
Solution Approach 2:
The patent implements dynamic power control where the power spectral density is adjusted based on real-time EMF limit calculations for each sector. This dynamic adaptation allows the system to optimize power distribution across different spatial directions, maintaining coverage areas that would be lost under static cell-wide power scaling.
3Reliability
If bandwidth limitation is enforced cell-wide, then EMF exposure is controlled, but received signal power at cell-edge users decreases
Solution Approach 1:
The patent applies bandwidth limitation selectively in specific spatial sectors rather than uniformly across the entire cell. This allows cell-edge users in sectors with sufficient EMF headroom to receive signals at full bandwidth and power, while limiting bandwidth only in sectors where EMF exposure would otherwise exceed regulatory limits.
Solution Approach 2:
The patent implements location-aware bandwidth control where the bandwidth allocation depends on the spatial sector and the user's position within that sector. This ensures that cell-edge users receive adequate signal power in their local sector while the overall system maintains EMF exposure compliance across all directions.
Data Source
AI summary
A method, system and apparatus are disclosed. A network node is provided. The network node includes processing circuitry configured to estimate a first signal quality metric associated with the first wireless device, determine a first directional electromagnetic field, EMF, limiting mechanism for transmission to the first wireless device based on the first signal quality metric where the first directional EMF limiting mechanism is different from another directional EMF limiting mechanism used for transmission to at least one other wireless device in the cell, and cause transmission to the first wireless device using the first directional EMF limiting mechanism.