Transmission Amplifier Linearization Using Receiver Feedback Predistortion
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Solution Overview
Problem
Conventional methods for linearizing transmission amplifiers in wireless networks require additional hardware to determine the inverse characteristics of power amplifiers, increasing complexity, power consumption, and size, while also reducing transmission efficiency due to bias current reduction.
Innovation Solution
A method involving a test signal with a preamble and ramp signal is transmitted, allowing receivers to calculate and transmit a pre-distortion characteristic back to the transmitter, which linearizes the amplifier without additional hardware by identifying the transmitter, calculating the pre-distortion characteristic based on the received distorted ramp signal, and applying it to correct signal distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional hardware is provided to determine the inverse characteristics of the transmission amplifier, then the linearization accuracy is improved, but the device complexity, power consumption and size increase
Solution Approach 1:
The transmitting device performs self-calibration by using its own transmitted test signal as the reference, eliminating the need for separate reception hardware. The device measures its own amplifier characteristics by comparing the transmitted test signal with the received test signal, achieving self-service linearization without additional hardware components.
Solution Approach 2:
The receiving device performs multiple functions: it acts as both a test signal receiver and a reference signal source. By utilizing the received test signal as the reference for calculating inverse characteristics, the system eliminates the need for separate dedicated hardware for each function, achieving multi-functionality with existing components.
2Measurement precision
If bias currents are provided to the transistors of the power amplifier, then the linearity is improved, but the transmission efficiency decreases
Solution Approach 1:
The system performs preliminary measurement and calculation of the transmission amplifier's characteristics using test signals before actual data transmission. By pre-determining the inverse characteristics through calibration, the system can apply optimal bias currents or pre-distortion settings in advance, achieving both linearity and efficiency during normal operation without continuous power loss.
Solution Approach 2:
The system uses feedback from the received test signal to calculate the inverse characteristics of the transmission amplifier. This feedback mechanism allows the system to automatically adjust and optimize the amplifier's operating parameters, achieving linearity improvement through intelligent control rather than continuous high bias currents, thereby maintaining transmission efficiency.
3Measurement precision
If the transmission signal is coupled to an additional reception signal path for demodulation and comparison, then the inverse characteristics can be determined accurately, but the hardware complexity increases
Solution Approach 1:
The system merges the transmission and reception functions into a unified calibration process. The same communication channel is used for both transmitting test signals and receiving them for measurement. By combining these functions and using the received signal as the reference, the system eliminates the need for separate dedicated reception signal paths and hardware components.
Solution Approach 2:
The transmitting device performs self-measurement by using its own transmitted test signal as the reference for calculating inverse characteristics. This self-service approach eliminates the need for external measurement equipment or additional reception hardware, achieving accurate characteristic determination using only the existing communication infrastructure.
Data Source
AI summary
A method and apparatus for linearizing a transmission amplifier of a transmitter within a wireless network includes transmitting (S1) a test signal having a preamble and a ramp signal by the transmitter; receiving (S2) the test signal transmitted by at least one receiver; identifying (S3) the transmitter of the test signal on the basis of the preamble; calculating (S4) a pre-distortion characteristic of the transmission amplifier of the identified transmitter on the basis of the distorted ramp signal; transmitting (S5) a retransmission signal which comprises a preamble and the calculated pre-distortion characteristic; and linearizing (S6) the transmission amplifier of the transmitter on the basis of the pre-distortion characteristic.