Uplink Beam Selection Under RF Exposure and Power Limits
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Solution Overview
Problem
Existing wireless communication systems face challenges in selecting uplink beams that maximize transmission power while adhering to radio frequency exposure limits, leading to hindered uplink transmission performance and capacity due to reliance on downlink reference signal received power (RSRP) without considering maximum permissible exposure (MPE) constraints.
Innovation Solution
A method for selecting uplink beams based on transmission power and RF exposure, using an RF exposure calculator to determine the maximum allowed power for each antenna module, taking into account specific absorption rate (SAR) and power density (PD) limits, and adjusting beam selection to ensure compliance with MPE regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If beam selection is based on downlink reference signal received power (RSRP) only, then beam selection simplicity is maintained, but uplink transmission performance is hindered due to ignoring maximum permissible exposure (MPE) constraints
Solution Approach 1:
The patent changes the beam selection parameter from only downlink RSRP to include both downlink RSRP and uplink power availability considering MPE constraints. This dual-parameter approach resolves the contradiction by maintaining operational simplicity through automated power calculation while improving uplink transmission performance through MPE-aware beam selection.
Solution Approach 2:
The patent implements feedback mechanisms where the UE reports power headroom information and MPE constraint status to the network, and the network adjusts beam selection and power allocation accordingly. This feedback loop enables dynamic adaptation to MPE constraints while maintaining optimal uplink performance.
2Reliability
If transmission power is increased to improve uplink performance, then signal-to-noise ratio (SNR) improves, but radio frequency exposure limits are exceeded
Solution Approach 1:
The patent dynamically adjusts transmission power parameters based on real-time MPE constraint evaluation. By calculating available uplink power considering MPE limits for each beam, the system achieves the highest permissible power level that improves SNR while remaining compliant with RF exposure regulations.
Solution Approach 2:
The patent implements dynamic power control where transmission power is continuously adjusted based on MPE constraints, beam selection, and channel conditions. This dynamic approach allows the system to operate at optimal power levels that maximize SNR while adapting to changing RF exposure requirements.
3Productivity
If beam selection considers both transmission power and RF exposure constraints, then uplink transmission capacity improves, but computational complexity increases
Solution Approach 1:
The patent performs preliminary calculations of maximum allowed power for each antenna module before beam selection. By pre-computing MPE constraints and available power levels, the system reduces real-time computational complexity during actual beam selection while maintaining accurate consideration of both power and RF exposure constraints.
Solution Approach 2:
The patent enables the UE to autonomously determine its own power headroom and MPE constraint status without requiring complex network-side calculations. This self-service approach reduces overall system complexity by distributing computational tasks to the UE, which has direct access to its own transmission power and exposure information.
Data Source
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AI summary
Certain aspects of the present disclosure relate to beam selection. An example method generally includes selecting, from a plurality of beams, a beam for uplink transmission during a particular time interval, the selecting being based on a transmission power and a radio frequency (RF) exposure for each of the plurality of beams and transmitting at least one uplink signal using the selected beam during the particular time interval.