MIMO Transmitter EVM Calculation Using Unbiased MMSE Equalization
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Solution Overview
Problem
Existing wireless communication systems face challenges in independently measuring Error Vector Magnitude (EVM) for antenna connectors due to leakage between antennas, leading to inaccurate EVM requirements for multi-layer MIMO transmissions.
Innovation Solution
The use of an unbiased linear Minimum Mean Square Error (MMSE) MIMO equalizer to calculate EVM by measuring the mean square error of the layer estimate at the output, where EVM for each transmission layer is calculated as 100 times the square root of this error, ensuring unbiased estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EVM is measured without addressing leakage between antennas, then measurement process is simple, but EVM requirement cannot be met and measurement accuracy deteriorates
Solution Approach 1:
The patent segments the MIMO signal measurement process by applying separate unbiased linear MMSE equalizers to each transmission layer. This allows independent EVM calculation for each layer while accounting for antenna leakage effects, thereby improving measurement accuracy without requiring complete system redesign
Solution Approach 2:
The unbiased linear MMSE MIMO equalizer serves as an intermediary processing step between signal reception and EVM measurement. It pre-processes the received signal to eliminate interference from antenna leakage before EVM calculation, enabling accurate measurement while maintaining a structured measurement workflow
2Measurement precision
If conventional EVM measurement is used, then measurement procedure is straightforward, but independent EVM measurement for each antenna connector is not possible
Solution Approach 1:
The measurement process is segmented into layer-specific operations where each transmission layer is processed independently through its own unbiased linear MMSE equalizer. This segmentation enables independent EVM measurement for each antenna connector while accounting for the coupled nature of MIMO signals
Solution Approach 2:
The patent changes the measurement parameter approach by using unbiased linear MMSE equalization instead of conventional direct measurement. This parameter transformation enables the extraction of independent EVM metrics for each antenna connector from the coupled MIMO signal space
Data Source
AI summary
Apparatuses, methods, and systems are disclosed for calculating an EVM of a transmitter. One apparatus includes a processor and a receiver that receives a multiple-layer MIMO signal from a transmitter via a propagation channel. The processor measures the received multiple-layer MIMO signal using an unbiased linear MMSE MIMO equalizer and calculates an EVM of the transmitter, where the EVM for each transmission layer is calculated as 100 times the square root of the mean square error of the layer estimate at the output of the unbiased linear MMSE MIMO equalizer.