Transmitter Power Amplifier Gain Control via Receiver Cross-Correlation
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Solution Overview
Problem
Conventional techniques for reducing adjacent channel interference in transmitter power amplifiers are either costly, require significant hardware overhead, or are computationally intensive, and lack reliable methods for measuring amplifier operating points without special instrumentation.
Innovation Solution
A method involving a receiver circuit that computes cross-correlation coefficients between the symbol stream and adjacent channel samples to estimate adjacent channel interference, allowing for reduced computation and dynamic adjustment of the transmitter amplifier's operating point without additional hardware on the transmit side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a larger power amplifier is used to transmit the communication signal with its operating point substantially backed-off from its compression point, then adjacent channel interference is reduced, but power consumption and heat generation increase
Solution Approach 1:
The patent implements dynamic operating point adjustment by continuously monitoring adjacent channel interference levels and automatically adjusting the amplifier's operating point in real-time. This allows the system to operate closer to the compression point when interference is low, reducing power consumption, while backing off when interference increases, thus resolving the contradiction between maintaining low interference and reducing power usage.
Solution Approach 2:
The system employs feedback mechanisms where the receiver measures adjacent channel interference and sends control signals back to the transmitter to adjust the amplifier operating point. This closed-loop control enables the system to maintain optimal performance by dynamically responding to actual interference conditions, allowing operation at higher efficiency points without compromising interference suppression.
2Use of energy by moving object
If the operating point is set as close as possible to the maximum point before distortion becomes unacceptable, then power efficiency is improved, but safety margin for operating point drift is reduced
Solution Approach 1:
The system dynamically adjusts the operating point based on real-time measurements of adjacent channel interference and temperature conditions. By continuously adapting the operating point rather than using a fixed setting, the system can safely operate closer to the maximum efficient point while maintaining reliability through automatic adjustment when conditions change, thus resolving the contradiction between power efficiency and safety margin.
Solution Approach 2:
The patent incorporates temperature monitoring and predictive adjustment mechanisms that anticipate operating point drift before it becomes problematic. By monitoring temperature and other parameters in advance, the system can proactively adjust the operating point to maintain safety margins while still operating at high efficiency points, preventing reliability issues before they occur.
3Stability of the object's composition
If temperature monitor circuitry is added to the transmitter for compensation, then operating point stability is improved, but hardware overhead and cost increase
Solution Approach 1:
The patent integrates temperature monitoring and compensation functions into existing receiver and control circuitry that already performs other measurement and control tasks. By making existing components multi-functional, the system achieves operating point stability without adding dedicated temperature monitor hardware, thus resolving the contradiction between stability and hardware complexity.
Solution Approach 2:
The system uses the receiver's existing measurement capabilities to monitor transmitter operating conditions and automatically adjust the operating point without requiring separate monitoring hardware. The receiver effectively serves dual purposes: receiving communication signals and monitoring transmitter health, thereby achieving stability without additional hardware overhead.
4Object-affected harmful factors
If power output monitoring is added to the transmitter power amplifier, then adjacent channel interference control is improved, but hardware complexity and operational degradation increase
Solution Approach 1:
The patent introduces the receiver as an intermediary that performs the measurement function. Instead of adding monitoring hardware to the transmitter, the receiver measures adjacent channel interference and uses this information to control the transmitter operating point. This intermediary approach achieves interference control without adding complexity to the transmitter hardware.
Solution Approach 2:
The measurement and monitoring functions are extracted from the transmitter and relocated to the receiver. By taking out the monitoring capability from the transmitter side, the system achieves interference control without adding hardware complexity to the amplifier, while the receiver's existing capabilities handle the measurement tasks.
5Measurement precision
If conventional measurement techniques are used to directly measure adjacent channel interference, then measurement accuracy is improved, but computational cost and system interruption increase
Solution Approach 1:
The system implements periodic measurement of adjacent channel interference at controlled intervals rather than continuous measurement. This periodic approach maintains measurement accuracy for control purposes while minimizing computational overhead and avoiding frequent interruptions to system operation, thus resolving the contradiction between measurement precision and operational continuity.
Solution Approach 2:
The patent applies measurement and computation only when necessary for control decisions rather than continuously. By using partial action - measuring and computing only at critical moments when operating point adjustment is needed - the system maintains adequate measurement accuracy while significantly reducing computational cost and maintaining system operation continuity.
Data Source
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AI summary
Signals are received that include a channel band and an adjacent band. The channel band is demodulated to obtain recovered symbols. Cross-correlation between the recovered symbols and the adjacent band is estimated. Adjacent channel interference is estimated, using the estimated cross-correlation of the recovered symbols and the adjacent band. Upon the estimated adjacent channel interference meeting a condition, a back-off command is sent to a transmitter power amplifier.