Crest Factor Reduction Gain Compensation for Peak Power Consistency
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Solution Overview
Problem
Modern communication systems face challenges in maintaining consistent peak power levels across a wide range of transmission power values due to varying gain in crest factor reduction modules, which complicates the requirements for D/A converters and digital predistortion systems.
Innovation Solution
A gain multiplier is introduced between the baseband signal generation module and the crest factor reduction module, with a device calculating the gain using power estimates from both modules to ensure the output power from the crest factor reduction module matches the baseband signal generation module's power, using an iteration algorithm or lookup table to maintain a consistent overall gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a crest factor reduction module is inserted to reduce the PAR of the signal, then the signal can be amplified more efficiently, but the gain of the CFR module is not constant and varies with TX power level
Solution Approach 1:
The patent implements a feedback mechanism where the actual output power of the CFR module is measured and fed back to a controller. The controller then adjusts the gain of the CFR module dynamically to compensate for power losses, ensuring the overall gain remains constant across different TX power levels. This closed-loop feedback system resolves the contradiction by maintaining gain stability while preserving the efficiency benefits of CFR.
Solution Approach 2:
The patent changes the operating parameters of the CFR module dynamically based on the TX power level. By adjusting the gain parameter of the CFR module in response to measured output power, the system adapts to different operating conditions. This parameter adjustment ensures that the CFR module maintains appropriate gain characteristics across the full range of TX power levels, resolving the gain consistency issue.
2Stability of the object's composition
If a gain module is added after the CFR module to correct for gain error, then the overall gain can be maintained, but the peak values coming out of the gain module will not be consistent and will vary in time
Solution Approach 1:
The patent applies preliminary action by placing the gain adjustment mechanism before the CFR module rather than after it. By pre-adjusting the gain of the signal before it enters the CFR module, the system ensures that the peak power levels remain consistent throughout the signal processing chain. This preliminary gain adjustment prevents the peak power variations that would occur if gain correction was applied after the CFR module.
Solution Approach 2:
The patent introduces an intermediary gain control mechanism that acts as a mediator between the signal source and the CFR module. This intermediary device dynamically adjusts the gain to compensate for the non-constant gain characteristics of the CFR module, ensuring both overall gain stability and peak power consistency. The intermediary gain controller resolves the contradiction by coordinating the gain adjustment with the CFR module's operating conditions.
3Adaptability or versatility
If the gain of the CFR module varies with TX power level, then the module can adapt to different power ranges, but it becomes difficult for the baseband signal generation module to guarantee the actual signal power level
Solution Approach 1:
The patent uses feedback to measure the actual output power of the CFR module and feeds this information back to the controller. The controller then adjusts the gain of the CFR module to compensate for power losses, ensuring that the baseband signal generation module can guarantee the actual signal power level. This feedback mechanism maintains adaptability across power ranges while providing precise power level control.
Solution Approach 2:
The patent replaces manual or fixed gain settings with an automated electronic control system. By using electronic feedback and dynamic gain adjustment, the system achieves more precise and reliable power level guaranteeing compared to fixed mechanical settings. The electronic control system can rapidly adapt to different power levels and maintain accurate power control, resolving the contradiction between adaptability and measurement precision.
Data Source
AI summary
An apparatus and method for compensating for transmit power losses that are caused by the addition of a clipping or crest factor reduction module in the TX path of a communications system. The method includes applying a gain to a signal input into the crest factor reduction module, so that a power of a signal output from the crest factor reduction module is equal to a power of a signal output from a baseband signal generation module in the TX chain. The apparatus and method have the benefit that the peaks of the signal to be transmitted will be consistent over a wide range of TX power values.