Dynamic Frequency Domain Control for SAR Compliance
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Solution Overview
Problem
Existing wireless devices face challenges in maintaining specific absorption rate (SAR) within regulated thresholds without compromising airtime efficiency or performance, as reducing transmission power or using time-domain duty cycling can lead to performance degradation.
Innovation Solution
A wireless information handling system dynamically adjusts the frequency domain by selecting a subset of frequencies and optionally adjusting transmission power or time-domain duty cycling to maintain SAR within a desired range, using protocols like OFDMA to optimize transmission parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transmission power is reduced to lower SAR, then SAR compliance is improved, but airtime efficiency and performance deteriorate
Solution Approach 1:
The frequency domain is segmented into multiple individual frequency resources that can be independently selected and activated. Instead of transmitting across the entire frequency band or reducing power uniformly, the system divides the band into discrete frequency units and selectively activates only the necessary subset, thereby reducing overall SAR while maintaining efficient data transmission on active frequencies.
Solution Approach 2:
The system dynamically adjusts the frequency domain configuration based on real-time SAR measurements and channel conditions. The set of activated frequency resources is not fixed but adapts continuously, allowing the system to optimize the balance between SAR compliance and airtime efficiency by activating or deactivating specific frequency resources as needed.
2Object-affected harmful factors
If time-domain duty cycling is used to reduce SAR, then SAR compliance is improved, but performance and airtime efficiency deteriorate
Solution Approach 1:
Instead of managing SAR control solely in the time domain through duty cycling, the system transitions to frequency domain management by selecting subsets of frequency resources. This dimensional shift allows SAR reduction without the performance penalties of time-domain gating, as data transmission continues efficiently on the activated frequency resources without temporal interruptions.
3Object-affected harmful factors
If a subset of frequencies is selected to reduce SAR, then SAR compliance is improved, but frequency resource utilization may worsen
Solution Approach 1:
The system implements closed-loop feedback by continuously measuring SAR and using these measurements to dynamically adjust the selection of frequency resources. The SAR measurement feedback drives the optimization process, allowing the system to automatically adapt the frequency domain configuration to maintain compliance while maximizing resource utilization efficiency.
Solution Approach 2:
The system changes the parameter of frequency resource allocation by dynamically adjusting which frequency resources are activated based on SAR levels and channel conditions. This parameter optimization allows the system to find the optimal balance between SAR compliance and effective utilization of available frequency resources, preventing waste while maintaining efficiency.
Data Source
AI summary
A wireless information handling system includes a specific absorption rate sensor, a wireless communications module, and a wireless controller in communication with the specific absorption rate sensor and the wireless communications module. The wireless communications module is to transmit a signal using a frequency domain including a set of frequencies. The specific absorption rate sensor is to measure the specific absorption rate when transmitting the signal. The wireless communication module is to transmit a subsequent signal using an adjusted frequency domain including a subset of the set of frequencies in response to measuring the specific absorption rate.