OFDM Transmitter Testing with Orthogonal Preambles
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Solution Overview
Problem
Testing multiple orthogonal frequency division multiplexing (OFDM) transmitters simultaneously with a single vector signal analyzer (VSA) is challenging due to the need for parallel data streams and separate signal processing, which increases test costs and time when using traditional methods.
Innovation Solution
A method and apparatus for transforming and processing composite data signals from multiple OFDM transmitters to calculate error vector magnitude (EVM) using signal transformation and processing means, allowing simultaneous testing with a single VSA by leveraging preamble data and known data packets to separate and analyze signals from multiple transmitters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple OFDM transmitters are tested sequentially with a single VSA, then equipment cost is reduced, but test time increases significantly
Solution Approach 1:
The patent segments the composite signal into individual transmitter components by utilizing orthogonal preamble sequences. Each transmitter is assigned a unique preamble pattern, allowing the VSA to distinguish and separate multiple transmitters' signals in the time domain through correlation processing, enabling parallel testing with a single instrument
Solution Approach 2:
The patent transforms the testing approach from sequential time-domain measurement to parallel frequency-domain analysis. By using orthogonal preambles across multiple transmitters simultaneously and processing them through spectral analysis, the system achieves multi-transmitter testing in a single measurement cycle, effectively adding a frequency dimension to the test process
2Loss of time
If multiple VSAs are used to test multiple OFDM transmitters simultaneously, then test time is reduced, but equipment cost increases
Solution Approach 1:
The patent enables a single VSA to perform multiple testing functions simultaneously by processing composite signals from multiple transmitters. The VSA is configured to identify and analyze each transmitter's contribution through orthogonal preamble recognition, making one instrument serve the purpose of multiple test systems
Solution Approach 2:
The patent combines multiple transmitter signals into a single composite input for the VSA. By using orthogonal preambles, the system merges multiple test cases into one measurement, allowing the VSA to decompose and analyze each transmitter's performance from the combined signal without requiring separate instruments
3Device complexity
If traditional single-transmitter testing methods are used, then signal analysis is simplified, but testing efficiency decreases
Solution Approach 1:
The patent introduces orthogonal preambles as intermediary markers that enable the VSA to distinguish between multiple transmitters. These preamble sequences act as identifiers that allow the signal processing system to separate and analyze each transmitter's contribution from the composite signal through correlation and spectral analysis
Solution Approach 2:
The patent changes the signal processing approach by transforming the time-domain composite signal into the frequency domain through spectral analysis. By converting the signal representation and utilizing frequency-selective characteristics, the system can resolve multiple transmitters' signals that would otherwise be indistinguishable in the time domain
Data Source
AI summary
Apparatus and method for testing signals from two or more OFDM transmitters simultaneously with a single VSA.