Predistortion Function Selection for Transient Spectral Emission Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing predistortion techniques in wireless communication systems face challenges in dynamically updating coefficients to compensate for changing environmental and signal conditions, leading to lag in power reporting and increased spectral emissions due to transient increases in power levels.
Innovation Solution
A method is introduced to select a 'lift power level' between the maximum and minimum signal power levels, allowing for the application of a corrective predistortion function based on the current power level, which reduces transient spectral emissions and improves dynamic range by using a higher predistortion function when the current power is below the lift level, and adjusting the lift level over time to maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a corrective predistortion function based on average power with time constant is used, then the predistortion function can track changing signal conditions, but the power report lags behind actual power changes causing transient spectral emissions
Solution Approach 1:
The patent applies dynamics by making the predistortion function selection adaptive to instantaneous power levels rather than relying solely on averaged power with time constants. The system dynamically adjusts which predistortion function to apply based on real-time power level comparisons, eliminating the inherent lag of averaging filters while maintaining adaptability to changing signal conditions.
Solution Approach 2:
The patent uses preliminary action by pre-calculating and storing multiple predistortion functions corresponding to different power levels. When the instantaneous power level is detected, the appropriate pre-computed function is immediately selected and applied, avoiding the delay associated with real-time averaging and function recalculation.
2Reliability
If predistortion coefficients are updated periodically to compensate for component aging and drift, then predistortion accuracy is maintained, but processing resources are significantly consumed
Solution Approach 1:
The patent applies local quality by selecting predistortion functions based on local instantaneous power level conditions rather than performing global periodic updates. Multiple predistortion functions are pre-computed for different power levels, and the system locally selects the appropriate function based on current operating conditions, avoiding unnecessary processing resources while maintaining accuracy.
Solution Approach 2:
The patent changes the parameter used for predistortion function selection from time-based periodic updates to power-level-based selection. By monitoring instantaneous power levels and selecting functions based on these parameter changes, the system maintains predistortion accuracy through condition-based updates rather than resource-intensive periodic recalculations.
3Measurement precision
If a training signal with specific power levels and noise is used to calculate predistortion function, then reliable information is obtained for determining coefficients, but power and noise levels are introduced into live wireless communications
Solution Approach 1:
The patent applies preliminary action by pre-calculating predistortion functions using training signals with specific power levels and noise characteristics before live communication occurs. These pre-computed functions are stored and later applied during actual communication based on detected power levels, obtaining reliable coefficient information in advance without introducing harmful power and noise levels into live wireless communications.
Data Source
AI summary
A corrective predistortion function is applied to a signal to compensate for or cancel out distortion that is introduced by a component that processes the signal. A disclosed example includes applying a corrective predistortion function to a transmitted signal used for wireless communications. A technique for selecting the corrective predistortion function includes determining a current power level of the signal. When the current power level is at or below a lift level between a maximum signal power level and a minimum signal power level, a corrective predistortion function corresponding to the lift level is applied to the signal. When the actual signal power level is above the lift level, a corrective predistortion function corresponding to the actual current power level is applied.