Transmit Chain Power Ratio Alignment for Nonlinearity Control
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Solution Overview
Problem
In wireless communication systems, the assumption of uniform non-linearity characteristics across multiple transmit chains can lead to suboptimal pre-distortion, resulting in errors such as error vector magnitude (EVM) and adjacent channel leakage ratio (ACLR) degradation due to variations in process, physical layout, and other factors.
Innovation Solution
A wireless communication device adjusts the amplification saturated power and output power ratios across transmit chains to align their non-linearity characteristics, using a controller to manage these ratios and apply pre-distortion uniformly, thereby improving transmitter performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If uniform non-linearity characteristics are assumed across multiple transmit chains, then pre-distortion can be applied uniformly, but this leads to EVM and ACLR degradation due to process and physical layout variations
Solution Approach 1:
The patent measures and determines specific non-linearity characteristics for each individual transmit chain, then applies chain-specific pre-distortion coefficients. This allows each transmit chain to be optimized according to its actual characteristics rather than using a uniform assumption, thereby resolving the contradiction between ease of uniform operation and actual transmitter reliability.
2Reliability
If chain-specific pre-distortion coefficients are used, then distortion-related errors are reduced, but measurement and control complexity increases
Solution Approach 1:
The patent employs automatic measurement and determination of non-linearity characteristics for each transmit chain using test signals and feedback mechanisms. The system self-calibrates by measuring the actual output characteristics and determining appropriate pre-distortion coefficients without requiring complex manual calibration, thereby reducing the practical complexity while maintaining high transmitter performance.
3Power
If power amplification is increased to improve signal strength, then transmission power is enhanced, but non-linear distortion increases
Solution Approach 1:
The patent applies pre-distortion to the input signal before power amplification by modifying the signal characteristics in advance based on the measured non-linearity characteristics of each transmit chain. This preliminary action compensates for the expected non-linear distortion that will occur during amplification, allowing the system to operate at higher power levels while maintaining signal integrity and reducing distortion-related errors.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. A wireless communication device may have an apparatus that aligns the non-linearity between transmit chains of the wireless communication device that are driven by the same digital port. The apparatus may adjust an amplification power out or an amplification saturated power to adjust a ratio between the amplification saturated power and the amplification power out for one or more transmit chains of the wireless communication device. The apparatus may adjust the ratios of transmit chains to align the ratios of the transmit chains for more consistent management of non-linear characteristics of the chain components. Numerous other aspects are described.