Uplink Front End with Finite Duty Cycle for SAR-Limited Power
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Solution Overview
Problem
Cellular user equipment (UE) is limited by Specific Absorption Rate (SAR) regulations, preventing the uplink power from exceeding certain limits, which restricts communication quality, especially at the cell edge or indoors where link degradation is common.
Innovation Solution
Implementing a front end system with a power amplifier and low noise amplifier, coupled by a duplexer, to transmit radio frequency signals at a higher power level for uplink using frequency division duplexing with a finite duty cycle, while maintaining compliance with SAR limits and ensuring continuous downlink reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uplink power is increased to improve communication stability and coverage, then communication quality is improved, but SAR regulatory limits are exceeded
Solution Approach 1:
The patent applies periodic action by implementing a finite duty cycle for uplink transmissions. The UE transmits at higher power levels intermittently rather than continuously, with transmission bursts separated by idle periods. This periodic transmission pattern allows the UE to achieve improved communication stability and coverage during active transmission while maintaining compliance with SAR regulatory limits through reduced average power exposure over time.
2Reliability
If uplink power is increased to prevent call drops at cell edge, then communication reliability is improved, but average power limit is exceeded
Solution Approach 1:
The patent implements periodic action through finite duty cycle operation, where the UE transmits at elevated power levels during scheduled bursts rather than maintaining continuous transmission. This allows the system to achieve sufficient signal strength for call drop prevention at cell edge locations while keeping the time-averaged power within regulatory limits. The intermittent transmission pattern creates peaks of high power for reliability when needed, followed by lower power periods for compliance.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the duty cycle parameter and transmission power level based on communication conditions. The system modifies these parameters to transmit at higher power during critical periods when call drop risk is present, then reduces power during less critical periods. This dynamic parameter adjustment enables the system to adapt to varying channel conditions and maintain reliability without continuously exceeding average power limits.
3Productivity
If higher power level is used for uplink transmission, then data rate is improved, but SAR compliance is violated
Solution Approach 1:
The patent applies periodic action by structuring uplink transmissions as periodic bursts with finite duty cycle. During these transmission bursts, the UE operates at higher power levels that enable improved data rates for productivity-critical communications. Between bursts, the system enters idle or low-power states that allow SAR compliance to be maintained. This periodic high-power operation achieves enhanced data throughput when needed while respecting regulatory exposure limits over the complete cycle.
Data Source
AI summary
Systems and methods for high power uplink transmission are disclosed. In one aspect, a mobile device includes an antenna configured to transmit radio frequency signals to a base station via an uplink and receive radio frequency signals from the base station via a downlink and a front end system coupled to the antenna. The front end system is configured to transmit and receive the radio frequency signals from the antenna, and duplex the radio frequency signals via frequency division duplexing. The front end system is further configured to transmit data on the uplink at a first power level that is higher than a predetermined level and at a finite duty cycle.