Uplink Beam Selection Under RF Exposure Power Limits
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Solution Overview
Problem
Wireless communication devices face challenges in complying with radio frequency (RF) exposure limits during transmission, as beams with strong received signal power may be limited by a shared RF exposure budget, restricting their ability to transmit at high power.
Innovation Solution
The technique involves selecting a beam based on uplink signal quality, considering RF exposure limits and signal power, and exploiting spatial diversity by assigning separate RF exposure budgets to each antenna module, allowing independent RF exposure tracking and increased transmission power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shared RF exposure budget is used for all beams, then compliance with RF exposure limits is ensured, but transmission power is restricted and uplink performance deteriorates
Solution Approach 1:
The patent divides the single shared RF exposure budget into multiple separate RF exposure budgets, one for each antenna module. This segmentation allows each antenna module to independently manage its RF exposure, enabling stronger transmission power on specific beams without being constrained by a global budget, thereby improving uplink throughput while maintaining overall RF exposure compliance.
2Productivity
If transmission power is increased to improve uplink throughput, then productivity increases, but RF exposure limits are violated
Solution Approach 1:
By segmenting the RF exposure budget allocation per antenna module, the system enables higher transmission power on specific beams that have better channel conditions, while other antenna modules maintain lower power levels. This selective power increase improves uplink throughput without causing overall RF exposure violations.
Solution Approach 2:
The patent applies different transmission power levels to different antenna modules based on their local channel conditions and RF exposure situations. Antenna modules with better channel quality can transmit at higher power, while others transmit at lower power, optimizing the balance between throughput and RF exposure compliance.
3Ease of operation
If beam selection is based only on received signal power, then ease of operation is maintained, but transmit power limits are not optimized
Solution Approach 1:
The patent changes the beam selection criterion from considering only received signal power to considering both received signal power and transmit power limits. This dual-parameter approach enables the system to select beams that not only have good channel conditions but also allow for higher transmission power, thereby optimizing transmission efficiency while maintaining manageable beam selection complexity.
Data Source
AI summary
Techniques and apparatus for beam selection in compliance with radio frequency (RF) exposure limits. A method that may be performed by a wireless device includes receiving, from another wireless device, a plurality of signals via a plurality of beams; measuring a received signal power for each of the beams, based on the received plurality of signals; determining a transmit power limit for each of the beams based at least in part on an RF exposure limit; determining an estimation of a signal quality at the other wireless device for each of the beams based at least in part the received signal powers and the transmit power limits; selecting one of the beams based on the estimations of the signal qualities for the beams; and transmitting a signal via the selected beam.