RF Path Switching for SAR-Limited Multi-Antenna Transmission
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Solution Overview
Problem
Existing electronic devices experience interruptions in data transmission and reception due to Tx/Rx blanking times caused by SAR backoff, which can be perceptible to users and are triggered when the specific absorption rate exceeds a threshold, leading to inefficiencies in power management.
Innovation Solution
The electronic device employs multiple RF circuits and antennas to identify conditions for switching RF paths based on SAR limits, adjusting transmission paths to minimize interruptions by utilizing antennas with different power differences and distances to maintain optimal communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If SAR backoff is performed when SAR exceeds threshold, then electromagnetic wave safety is improved, but data transmission and reception are interrupted causing service interruptions
Solution Approach 1:
The patent implements dynamic RF path switching by monitoring SAR levels in real-time and automatically transitioning between first and second RF paths when SAR thresholds are exceeded. This dynamic adaptation allows the system to maintain continuous data transmission by switching to an alternative RF path rather than interrupting service, thereby resolving the contradiction between electromagnetic wave safety and transmission reliability
Solution Approach 2:
The system changes the operational parameters by switching between different RF paths with different SAR characteristics. When the first RF path exceeds SAR thresholds, the system transitions to the second RF path, effectively changing the transmission parameters to maintain safety while preserving service continuity
2Object-affected harmful factors
If maximum transmittable power is backed off based on cumulative SAR, then long-term SAR compliance is improved, but transmission power is reduced affecting communication efficiency
Solution Approach 1:
The patent dynamically switches between RF paths based on cumulative SAR monitoring. When cumulative SAR thresholds are approached, the system transitions to alternative RF paths that have lower cumulative SAR impact, thereby maintaining communication efficiency without exceeding long-term SAR limits. This dynamic path selection avoids permanent power backoff while ensuring compliance
Solution Approach 2:
The system maintains multiple RF paths that serve as copies or alternatives to each other. When one path's cumulative SAR becomes problematic, the system switches to a copied alternative path with different SAR characteristics, preserving communication efficiency while managing cumulative exposure
3Device complexity
If single RF path is used for transmission, then device complexity is reduced, but service interruptions occur when SAR limits are exceeded
Solution Approach 1:
The patent segments the RF transmission system into multiple independent RF paths (first RF path and second RF path), each capable of independent operation. This segmentation allows the system to switch between paths when SAR limits are exceeded, maintaining service continuity. The segmentation is implemented through separate RF circuits and antennas, providing redundancy without excessive complexity
Solution Approach 2:
The system changes the active RF path parameter based on SAR conditions. By maintaining multiple RF paths with different SAR profiles and switching between them, the system ensures service continuity when SAR limits are approached, resolving the contradiction between simplicity and reliability
Data Source
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AI summary
According to various embodiments, an electronic device, may include a first radio frequency (RF) circuit including a first amplifier, a second RF circuit including a second amplifier, and a plurality of antennas, at least one processor, and memory storing instructions, and the instructions, when executed by the at least one processor, may cause the electronic device to transmit first signals to a first antenna among the plurality of antennas through a first RF path that uses the first RF circuit, transmit second signals to a second antenna among the plurality of antennas through a second RF path that uses the second RF circuit, identify that a first condition for switching an antenna based on a specific absorption rate (SAR) limit is satisfied, while concurrently transmitting the first signals and the second signals, identify a first power difference between a maximum transmittable power of the first signals and a backoff maximum power related to SAR backoff of the first signals, and a second power difference between a maximum transmittable power of the second signals and a backoff maximum power related to SAR backoff of the second signals, and control so as to change the first RF path for transmitting the first signals, to a third RF path associated with a third antenna among the plurality of antennas based on identifying that the first power difference is greater than the second power difference and that the first condition is satisfied, wherein a first distance between the first antenna and the second antenna is less than a first threshold distance , and a second distance between the first antenna and the third antenna is greater than or equal to a second threshold distance.