Dynamic Power Scaling for Multi-Band Uplink SAR Compliance
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Solution Overview
Problem
Wireless communication systems face challenges in managing power aggregation across multiple radio frequency spectrum bands to comply with specific absorption rate (SAR) limits, as the total transmit power often exceeds predetermined limits, requiring dynamic power scaling to maintain compliance.
Innovation Solution
User equipment (UE) performs power scaling across multiple bands by prioritizing power reduction based on semi-static and dynamic factors, such as carrier frequencies, bandwidths, and message priorities, to ensure the total transmit power meets the SAR-oriented power limit, allowing for temporary boosts in transmit power while averaging power within acceptable limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE transmits uplink messages via multiple radio frequency spectrum bands with high power, then the uplink user perceived throughput and data rates are enhanced, but the total transmit power exceeds the SAR-oriented power limit
Solution Approach 1:
The patent implements dynamic power scaling where the UE continuously monitors its transmit power across multiple bands and adjusts power levels in real-time based on SAR constraints. The power scaling factor is dynamically calculated and applied to maintain throughput while complying with SAR limits
Solution Approach 2:
The patent applies differential power scaling across different frequency bands and message types. Priority messages (e.g., uplink control information) maintain higher power levels while non-priority data messages receive greater power reduction, ensuring critical communications are preserved while managing overall SAR exposure
2Reliability
If the UE performs power scaling to satisfy the uplink transmission power criterion, then compliance with SAR limits is achieved, but the transmission power for non-priority messages is reduced
Solution Approach 1:
The patent applies partial power scaling selectively to non-priority messages while maintaining full or reduced power for priority messages. This partial action approach ensures SAR compliance is achieved through targeted power reduction rather than uniform scaling across all transmissions
3Power
If the UE aggregates power across multiple bands to exceed individual band limits, then temporary transmit power boosts are achieved, but the total power may exceed the uplink transmission power criterion
Solution Approach 1:
The patent implements a feedback mechanism where the UE monitors cumulative transmit power across all aggregated bands and compares it against the uplink transmission power criterion. When the threshold is approached, the UE applies power scaling factors to individual bands to maintain compliance while preserving as much total power as possible for critical communications
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may be configured to satisfy an uplink transmission power criterion, such as a specific absorption rate (SAR). The UE may be scheduled to transmit a first uplink message via a first frequency band and a second uplink message via a second frequency band. The UE perform power scaling on the first frequency band and the second frequency band to satisfy the uplink transmission power criterion. For example, the UE may select a first transmission power level for transmitting the first uplink message and a second transmission power level for transmitting the second uplink message based on a function of UE transmission power level over a preceding time interval. The UE may perform uplink power aggregation techniques to temporarily boost transmit power while satisfying the uplink transmission power criterion.