Because they inhabit such high-multipath environments, commercial wireless systems greatly benefit from the use of multiple-input multiple-output (MIMO) antenna systems. Due to MIMO's complexity, however, utilizing the technology requires both expertise and the right equipment. For an engineer who is working to develop and integrate robust MIMO receivers, for example, it is necessary to be able to accurately test the receivers under real-world conditions. Such testing also must take place early enough in the design cycle to find and fix any problems. To provide guidance on this process, Agilent Technologies recently released a white paper titled, "MIMO Receiver Test."
Because of issues like channel sensitivity and mobility requirements, it is not effective or practical to test MIMO receivers in a "real" wireless environment. Although other solutions are available, they must be augmented with third-party faders. As a result, this approach leads to manual power-calibration problems, which arise due to poor power accuracy.
In contrast, the paper recommends the use of an integrated solution that combines the signal source, noise source, and fader. For example, the company's PXB baseband generator and channel emulator promises to test MIMO receivers in realistic wireless channels and conditions. By delivering channel-emulation capabilities for the latest LTE and WiMAX standards, the PXB vows to rapidly replicate real-world MIMO conditions and channels. It generates realistic fading scenarios including path and channel correlations.
Because aspects like antenna spacing, polarization, radiation pattern, and angular spread affect channel correlation, they must be accurately modeled. The PXB uses an antenna-parameter setup menu to perform this task. Once an operator sets antenna parameters, the PXB software calculates the correlation associated with those various factors and populates the resulting coefficients into a correlation matrix.
With the availability of such solutions, engineers can accurately simulate real-world conditions in the lab. Such simulations will rapidly test corner cases while stressing devices beyond standard requirements. To ensure design robustness earlier in the design process, they also can test co-existence. With the prevalence of MIMO technology in today's communications designs, such solutions can help engineers take advantage of its benefits while not getting waylaid by the technology's complexity.
Agilent Technologies, Inc.
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