Antenna Power Control for SAR-Compliant SRS Transmission
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Solution Overview
Problem
The limitation of output power for sounding reference signals (SRS) in wireless communication devices to comply with Specific Absorption Rate (SAR) specifications leads to reduced signal-to-noise ratio and impaired downlink beamforming performance, affecting communication quality.
Innovation Solution
A method for controlling antenna output power in user equipment (UE) that allows SRS signals to be transmitted at maximum power while non-SRS signals are adjusted to meet SAR requirements, ensuring channel reciprocity and communication quality by calculating a power decrease value based on electromagnetic power density exposure needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the output power of the antenna is reduced to meet SAR specifications, then electromagnetic radiation compliance is improved, but communication quality deteriorates
Solution Approach 1:
The patent segments the transmission signals into SRS signals and non-SRS signals, applying different power control strategies to each type. SRS signals are transmitted at maximum power to maintain channel reciprocity, while non-SRS signals have their power reduced to meet SAR requirements. This segmentation resolves the contradiction by allowing critical communication functions to operate at full power while limiting overall radiation exposure.
Solution Approach 2:
The patent applies local quality by assigning different power levels to different signal types based on their specific requirements. The SRS signals receive preferential treatment with maximum power allocation to ensure accurate channel state information, while other signals undergo power reduction. This localized power management approach maintains communication quality for critical functions while reducing overall SAR exposure.
2Object-affected harmful factors
If the output power of SRS signal is limited to meet SAR requirements, then electromagnetic radiation compliance is improved, but channel reciprocity is damaged
Solution Approach 1:
The patent separates SRS signal transmission from other signal transmissions, allowing SRS signals to be transmitted at maximum power without being constrained by SAR-based power limits applied to other signals. This segmentation ensures that channel state measurement precision is maintained while still achieving SAR compliance through power limiting on non-SRS signals.
Solution Approach 2:
The patent allows SRS signals to exceed the power limits imposed on other signals by transmitting at maximum power. This partial excessive action is justified by the critical need for accurate channel reciprocity measurement, while the overall system still achieves SAR compliance through power reduction on other signal types.
3Object-affected harmful factors
If the output power of SRS signal is reduced to meet SAR requirements, then electromagnetic radiation compliance is improved, but signal-to-noise ratio is reduced
Solution Approach 1:
The patent segments the power allocation such that SRS signals receive maximum power allocation while other signals undergo power reduction. This ensures that the signal-to-noise ratio for channel measurement remains high, while the overall average power meets SAR requirements. The segmentation allows critical measurement signals to maintain high SNR without compromising overall radiation compliance.
Data Source
AI summary
This application provides example methods for controlling an output power of an antenna for user equipment. One example method includes, during a sounding reference signal (SRS) transmission period, transmitting, by a first antenna of at least one antenna of the user equipment, a first SRS signal to a base station at a first SRS output power, where the first SRS output power is equal to a maximum output power (Pcmax) of the first antenna. During the SRS period, a non-SRS signal is transmitted to the base station at a non-SRS output power, where the non-SRS output power is less than a difference between the maximum output power of the first antenna and a maximum output power reduction of the first antenna, and the maximum output power reduction of the first antenna is set to meet an electromagnetic power density exposure requirement of the first antenna.