Antenna Port EVM Calculation Using Unbiased MMSE Equalizer
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Solution Overview
Problem
Existing wireless communication systems face challenges in measuring Error Vector Magnitude (EVM) independently for antenna connectors due to leakage between antennas, which affects the accuracy of transmitter performance measurements.
Innovation Solution
The proposed solution involves using a linear unbiased MMSE equalizer to calculate EVM at the transmitter antenna connectors, independent of the propagation channel, by employing expressions that depend on the noise covariance at the connectors and applying unbiased linear MMSE receivers.
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 multi-antenna system into individual antenna connectors for independent EVM measurement. By using separate measurement paths and isolating each antenna connector, the system can measure EVM for each antenna independently despite the presence of leakage between antennas, thus improving measurement accuracy without requiring complete system redesign
Solution Approach 2:
The patent introduces an intermediary measurement approach that accounts for leakage effects between antennas. By modeling and compensating for the leakage paths as intermediary elements, the system can extract accurate per-antenna EVM measurements from the coupled multi-antenna system, resolving the contradiction between measurement simplicity and accuracy
2Ease of manufacture
If traditional EVM measurement is used in multi-antenna systems, then implementation is straightforward, but leakage between antennas affects measurement accuracy
Solution Approach 1:
The patent changes the measurement parameters by introducing leakage compensation factors and using modified measurement equations that account for inter-antenna coupling. By adjusting these parameters, the system maintains ease of implementation while significantly improving EVM measurement accuracy in multi-antenna configurations
Solution Approach 2:
The patent implements a feedback mechanism where leakage measurements are taken and used to compensate for inter-antenna coupling effects in the final EVM calculation. This feedback approach allows the system to maintain simple measurement hardware while achieving high measurement accuracy through iterative compensation
Data Source
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AI summary
Apparatuses, methods, and systems are disclosed for calculating an EVM of a transmitter. One apparatus (600) includes a processor (605) and a receiver (635) that receives (905) a signal (210) via a propagation channel from an antenna port (207) at a transmitter (205), the antenna port (207) comprising multiple antennas and with an antenna connector for each antenna. The processor (605) measures (910) the received signal (210) using an unbiased linear MMSE equalizer (230) and calculates (915) an EVM of the antenna port, where the EVM is calculated as 100 times the square root of the mean square error of the symbol estimate at the output of the unbiased linear MMSE equalizer (230).