Wireless Transmitter Amplifier Linearization via Network Pre-Distortion
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Solution Overview
Problem
Conventional methods for linearizing transmission amplifiers in wireless networks require additional hardware, increasing complexity, power consumption, and size, while also reducing efficiency due to the need for pre-distortion and bias current adjustments.
Innovation Solution
A method that calculates a pre-distortion characteristic using a test signal transmitted and received by nodes in a wireless network, allowing for automatic linearization of transmission amplifiers without additional hardware, by identifying the transmitter, calculating the pre-distortion characteristic based on a distorted ramp signal, and applying it to the transmission amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pre-distortion is performed by coupling the transmission signal to an additional reception signal path for demodulation and comparison, then the transmission amplifier can be linearized, but additional hardware is required which increases complexity, power consumption and size
Solution Approach 1:
The patent extracts the essential function of determining the inverse characteristic from the complex reception signal path and implements it through a simplified test signal approach. Instead of coupling the full transmission signal through demodulation and comparison circuits, the invention uses a dedicated test signal that directly probes the amplifier's characteristics, extracting only the necessary information for pre-distortion calculation without requiring the full reception signal path hardware
Solution Approach 2:
The patent changes the parameter being measured from the full complex transmission signal to a specific test signal with known characteristics (ramp signal). By changing the input signal parameter to a controlled test signal rather than the actual transmission signal, the system can determine amplifier characteristics without requiring the complex demodulation and comparison hardware that would be needed for general signal processing
2Manufacturing precision
If bias currents are provided to the transistors of the power amplifier to reduce nonlinearity, then distortion is reduced, but the efficiency of the transmission power stage is reduced
Solution Approach 1:
The patent applies preliminary action by calculating and applying the pre-distortion characteristic before the signal reaches the power amplifier. Instead of trying to reduce nonlinearity through bias current adjustment during amplifier operation, the invention pre-compensates for the expected nonlinearities by modifying the input signal in advance, allowing the amplifier to operate efficiently without requiring excessive bias currents for linearization
3Measurement precision
If conventional pre-distortion methods are used with additional reception signal path, then the inverse characteristic can be determined, but the apparatus size increases
Solution Approach 1:
The patent uses a copy approach by employing a test signal that replicates the essential characteristics needed for determining the inverse characteristic, rather than processing the actual transmission signal. The test signal serves as a simplified copy that provides sufficient information for pre-distortion calculation without requiring the full signal path hardware, thereby reducing apparatus size while maintaining measurement accuracy
Data Source
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AI summary
A method and apparatus for linearizing a transmission amplifier of a transmitter within a wireless network comprising the steps of transmitting (S1) a test signal which comprises a preamble and a ramp signal by the transmitter of the wireless network; receiving (S2) the test signal transmitted by the transmitter of the wireless network by at least one receiver of the wireless network; identifying (S3) the transmitter of the transmitted test signal by the at least one receiver of the wireless network on the basis of the preamble of the test signal received by the respective receiver of the wireless network; calculating (S4) a pre-distortion characteristic of the transmission amplifier of the identified transmitter by the at least one receiver of the wireless network on the basis of the distorted ramp signal of the test signal received by the receiver of the wireless network; transmitting (S5) a retransmission signal which comprises a preamble and the calculated pre-distortion characteristic of the transmission amplifier of the identified transmitter by the receiver of the wireless network to the identified transmitter of the wireless network; and linearizing (S6) the transmission amplifier of the transmitter on the basis of the pre-distortion characteristic of the retransmission signal received by the transmitter of the wireless network from the receiver of the wireless network.