Distributed RF Channel Emulator for Over-the-Air Testing
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Solution Overview
Problem
Current RF channel emulators face limitations in producing a scalable and efficient RF environment for over-the-air testing due to physical constraints, such as the need for a large number of antennas and amplifiers, which results in significant RF path losses and increased costs, especially as the frequency and size of the test volume increase.
Innovation Solution
A distributed channel emulation system is implemented, where the functions of a spatial channel emulator are split between a central location and a remote location within the test chamber, using low-loss intermediate frequency or baseband signals to reduce cable losses and moving power amplification directly to the antennas, allowing for more efficient power control and reduced uncertainties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of antennas and amplifiers are used to produce RF environment for over-the-air testing, then the test coverage and frequency range are improved, but the RF path losses increase and costs increase
Solution Approach 1:
The system divides the boundary array into multiple distributed nodes, each independently generating and amplifying RF signals locally before transmission. This segmentation allows each node to operate with lower power requirements and reduces the cumulative path losses associated with centralized high-power transmission across the entire array.
Solution Approach 2:
The patent transitions from traditional conducted testing to over-the-air testing by introducing spatial and electromagnetic dimensions. This allows signals to propagate through free space rather than confined cable paths, fundamentally changing the transmission medium and enabling new testing capabilities at higher frequencies with reduced losses.
2Device complexity
If traditional RF cable paths are used to connect channel emulators to antennas, then system simplicity is maintained, but cable losses increase significantly
Solution Approach 1:
The patent extracts the amplification function from the centralized channel emulator and places it directly at each antenna node. This removes the need for long RF cable connections between the emulator and antennas, eliminating the primary source of cable losses while maintaining system functionality.
Solution Approach 2:
The system introduces distributed power amplifiers as intermediary devices between the channel emulator and antennas. These amplifiers act as local signal boosters, compensating for transmission losses and enabling efficient signal delivery without requiring excessively long or high-power cable connections.
3Ease of operation
If power amplification is performed at centralized location before cable transmission, then control is simplified, but power control uncertainties increase
Solution Approach 1:
The centralized power amplification is segmented into multiple distributed power amplifiers, each located at individual antenna nodes. This allows independent power control and calibration for each transmission path, eliminating the cumulative uncertainties that arise from centralized amplification followed by long cable transmissions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces RF path losses, improves signal-to-noise ratio, and enables testing at higher frequencies with lower costs by minimizing the need for extensive and lossy RF cables, while maintaining precise control over amplification and calibration.
Implementation Method 1
an up-converter is configured to up-convert an impaired signal of the emulated channel to produce a radio frequency, RF, signal
Implementation Method 2
The array of antennas 12 radiate electromagnetic energy (radio waves) toward the DUT in a variety of directions
Data Source
AI summary
In some embodiments, an electromagnetic measurement system to perform radio frequency, RF, downlink testing of a device under test, DUT, in a chamber is provided. Exterior to the chamber is an emulator core configured to introduce an impairment in each of at least one transmit signal to produce at least one impaired signal for each of at least one emulated channel. Within the chamber, for each of the at least one emulated channel, an up-converter is configured to up-convert an impaired signal of the emulated channel to produce a radio frequency, RF, signal.