Wireless Tx Power Control Using Feedback-Guided Rate Probing
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Solution Overview
Problem
In wireless communication systems, high data rates are restricted to short-range transmissions due to power amplifier distortion, hardware inaccuracies, and parameter uncertainties, leading to reduced link budget and limited transmit power.
Innovation Solution
A closed-loop system using receiver-side feedback for transmitter power optimization, which adjusts transmit power and rate to balance signal-plus-noise and distortion, reducing error vector magnitude and maximizing link throughput by leveraging beamforming and power control mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high data rates are used, then throughput is improved, but transmit power must be reduced due to PA distortion and EVM constraints
Solution Approach 1:
The patent implements a closed-loop feedback system where the receiver measures EVM and packet error rate, then feeds this information back to the transmitter. The transmitter uses this feedback to dynamically adjust its transmit power and data rate, optimizing performance while maintaining compliance with EVM constraints. This resolves the contradiction by enabling real-time adaptation rather than static power backoff.
Solution Approach 2:
The system transitions from static transmit power settings to dynamic adjustment of both power and data rate based on channel conditions and receiver feedback. The transmitter can adaptively change operating parameters in real-time, allowing high data rates when channel conditions permit while maintaining power efficiency when conditions degrade.
2Length of stationary object
If transmit power is increased to extend range, then transmission distance is improved, but PA distortion increases causing higher EVM
Solution Approach 1:
The receiver continuously monitors EVM and feeds this measurement back to the transmitter. When EVM exceeds thresholds due to PA distortion from high power transmission, the transmitter receives feedback to reduce power or adjust modulation, maintaining EVM compliance while maximizing transmission distance.
Solution Approach 2:
The system dynamically changes multiple parameters including transmit power, data rate, and modulation scheme based on feedback. By adjusting these parameters in combination rather than just power, the system can extend transmission distance while keeping EVM within acceptable limits through coordinated parameter optimization.
3Manufacturing precision
If power backoff is applied to reduce distortion, then EVM is improved, but link budget decreases reducing throughput
Solution Approach 1:
Instead of applying fixed power backoff, the system dynamically adjusts transmit power based on real-time feedback about actual channel conditions and receiver performance. This allows the system to operate at higher power when conditions permit (maintaining throughput) while applying backoff only when necessary to maintain EVM compliance.
Solution Approach 2:
The system compensates for power backoff by adjusting other parameters such as data rate and modulation scheme. When power must be reduced to maintain EVM, the system adapts the data rate to maintain overall throughput, or adjusts modulation to be more robust, thereby mitigating the impact of power backoff on productivity.
4Reliability
If hardware inaccuracies and parameter uncertainties are compensated, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent uses feedback from the receiver about actual performance metrics (EVM, packet error rate) to compensate for hardware inaccuracies and parameter uncertainties. Rather than requiring complex pre-compensation circuits in the transmitter, the system uses simple feedback loops that allow the receiver to inform the transmitter about actual conditions, achieving reliability through measurement and adaptation rather than complex hardware.
Data Source
AI summary
A transmit power optimization and rate-control system includes a transmitter circuit having one or more power amplifiers transmit radio-frequency (RF) signals at a transmission (Tx) rate and a Tx power level. A receiver circuit receives RF signals, decodes the received RF signals and provides one or more Tx status feedbacks. A rate-control module adjusts the Tx rate based at least on a channel condition. A probing engine generates at least two consecutive frames at a first Tx power level, and a second Tx power level in response to a trigger causes the transmitter to transmit the at least two consecutive frames, and processes respective Tx status feedbacks received in response to transmission of the two consecutive frames in order to optimize the Tx power of the transmitter.