5G Random Access Beam Selection for RF Exposure Mitigation
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Solution Overview
Problem
Existing 5G wireless communication systems face challenges in mitigating radio frequency exposure during the random access procedure, particularly due to maximum permissible exposure (MPE) limitations in mmWave frequency bands.
Innovation Solution
The proposed solution involves a method for performing a random access procedure that includes receiving information for a set of downlink reference signals, determining a set of exposure levels corresponding to spatial filters, and selecting a first downlink reference signal and spatial filter based on received power and exposure levels. This allows for the transmission of physical random access channels using the selected spatial filter, thereby mitigating RF exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If beamforming gain is used to support increased capacity in 5G systems, then communication capacity is improved, but radio frequency exposure increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting beam selection and transmission power based on exposure level parameters. The system determines exposure levels for different spatial filters and selects beams that maintain communication capacity while operating within MPE-compliant power parameters, thereby resolving the contradiction between capacity improvement and RF exposure mitigation.
2Object-affected harmful factors
If MPE limitations are enforced in mmWave frequency bands, then radio frequency exposure is mitigated, but random access procedure reliability deteriorates
Solution Approach 1:
The patent implements preliminary action by pre-determining exposure levels for different spatial filters before executing the random access procedure. The UE identifies MPE-compliant beams in advance and selects appropriate spatial filters proactively, ensuring that random access transmissions comply with MPE limitations while maintaining procedure reliability through careful beam selection.
3Loss of energy
If spatial filter selection is optimized for power control, then transmission power is reduced, but beam selection complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the beam selection process into distinct stages: determining exposure levels for multiple spatial filters, selecting compliant beams based on MPE requirements, and then performing power control within the selected beam. This segmented approach manages complexity by breaking down the optimization problem into manageable steps while achieving power reduction through systematic spatial filter selection.
Data Source
AI summary
Methods and apparatuses for radio frequency exposure mitigation via beam selection for random access procedure. A method for performing a random access (RA) procedure includes receiving information for a set of downlink reference signals (DL RSs). The method further includes determining: a set of DL reference signal received powers (RSRPs) corresponding to the set of DL RSs, a set of spatial filters corresponding to the set of DL RSs, a set of exposure levels corresponding to the set of spatial filters, a first DL RS from the set of DL RSs based on the set of DL RSRPs and the set of exposure levels, and a first spatial filter corresponding to the first DL RS. The method further includes transmitting a physical random access channel (PRACH), a physical uplink shared channel (PUSCH), or a physical uplink control channel (PUCCH) using the first spatial filter.