Transmitter Output Power Dithering for EVM Control
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Solution Overview
Problem
High output power in wireless transmitters at high data rates leads to EVM degradation due to antenna load variations, causing link quality issues, and existing solutions are either costly or ineffective in directly improving transmitter performance.
Innovation Solution
A method of output power dithering that involves transmitting packets at varying output powers, determining error rates, and adjusting the power based on comparisons to minimize error rates, allowing for dynamic optimization of transmitter performance without requiring extensive hardware modifications or dual-end communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If high output power is transmitted to extend transmission range, then transmission range is improved, but EVM degradation increases due to power amplifier compression
Solution Approach 1:
The transmitter dynamically adjusts output power based on real-time feedback about power amplifier operating conditions. The system monitors compression point shifts caused by antenna load variations and adapts the output power level accordingly, transitioning from static power transmission to dynamic power control to maintain optimal EVM while extending transmission range.
Solution Approach 2:
The system implements a feedback mechanism where the transmitter receives information about power amplifier compression point shifts and antenna load conditions, then adjusts output power in response. This closed-loop control allows the system to compensate for EVM degradation by reducing power when compression occurs or increasing power when the amplifier operates in its linear region, thereby improving transmission range without sacrificing signal quality.
2Manufacturing precision
If output power is reduced to maintain EVM quality, then EVM is improved, but transmission range decreases
Solution Approach 1:
Rather than statically reducing output power, the system dynamically adjusts power levels based on real-time monitoring of power amplifier operating conditions. When the amplifier operates in its linear region with good EVM, the system transmits at higher power to extend range. When compression occurs and EVM degrades, the system reduces power. This dynamic adaptation allows the system to achieve both good EVM and extended transmission range compared to static power reduction.
Solution Approach 2:
The system changes the output power parameter in response to detected changes in power amplifier compression point and antenna load conditions. By monitoring EVM and compression point shifts, the system adjusts the power level parameter to maintain optimal operation, thereby avoiding the need for permanent power reduction while still maintaining EVM quality and extending transmission range when conditions permit.
3Stability of the object's composition
If hardware-based solutions like isolators are added to control antenna load variation, then EVM stability is improved, but device complexity and cost increase
Solution Approach 1:
The system replaces hardware-based solutions like isolators with a software/firmware-based control mechanism. Instead of using physical components to isolate the power amplifier from antenna load variations, the system uses digital signal processing and adaptive power control algorithms to compensate for load effects. This substitution reduces device complexity and cost while achieving EVM stability through intelligent control rather than physical isolation.
Solution Approach 2:
The transmitter monitors its own operating conditions and automatically adjusts its output power to compensate for antenna load variations and power amplifier compression effects. The system performs self-diagnosis and self-correction by detecting EVM degradation and adjusting power accordingly, eliminating the need for external hardware components like isolators or complex calibration systems. This self-service approach simplifies the overall system while maintaining EVM stability.
4Reliability
If excessive power reduction is applied to account for errors, then EVM reliability is improved, but total output power and transmission range are reduced
Solution Approach 1:
The system replaces static power reduction with dynamic power adjustment. Instead of permanently reducing power to account for potential errors, the system monitors real-time operating conditions and adjusts power levels dynamically. When the power amplifier operates in its linear region with good EVM, the system transmits at full power. When compression occurs and reliability concerns arise, the system reduces power. This dynamic approach maintains EVM reliability only when necessary while preserving total output power and transmission range for the majority of operating conditions.
Solution Approach 2:
The system performs preliminary monitoring of power amplifier operating conditions and predicts when compression might occur. By detecting early signs of compression point shifts or antenna load variations, the system proactively adjusts power before significant EVM degradation occurs. This preliminary action maintains EVM reliability by preventing errors rather than compensating for them through excessive power reduction, thereby preserving transmission range and total output power.
Data Source
AI summary
A technique for admission control of packet flows is disclosed. In one particular exemplary embodiment, the technique may be realized as a method for output power dithering for improved transmitter performance. The method may comprise transmitting a plurality of packets at a first output power, determining a first error rate associated with the transmission of the plurality of packets at the first output power, transmitting the plurality of packets at at least one second output power different from the first output power, determining at least one second error rate associated with the transmission at the at least one second output power, and identifying a desired output power based at least in part on a comparison between the first error rate and the at least one second error rate.