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Azimuth unveils 'first' tester for 802.11n devices

Posted: 13 Jun 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Alex Mendelsohn? Azimuth Systems? 802.11n? channel-modeling? WLAN?

This $6,000 adjunct (for an annual license) to Azimuth Systems' existing product line represents an industry-first functional tester that will let you test draft 802.11n-based products for interoperability, peRFormance, conformance, and backward compatibility.

As a channel-modeling WLAN tester, it can actually emulate multi-path RF environments to determine the effect of multi-channel interactions.

As the company's press release notes, this platform is based on the ACE 400NB Azimuth Channel Emulator and W-Series platform. The ACE 400NB stand-alone platform was used to evaluate 802.11a, 802.11b and 802.11g devices, and now serves 802.11n as well.

Testing MIMO is especially significant, as MIMO is the foundation for next-generation WLAN products. With multiple Transmit and Receive antennas, MIMO devices promise ensure higher data throughput and greater range.

While multi-path is generally thought of as an effect that degrades 802.11 performance, MIMO takes advantage of multi-path reflections to tune transmissions, minimize errors, and improve overall performance.

But, multi-path is difficult to predict. Microwave signals can bounce off buildings and even people as they move, creating multi-path effects. That's where Azimuth's graphical-interface ACE 400NB comes in. It can now emulate multi-path behavior.

In use, the 400NB digitizes an RF signal generated by your wireless device under test, and then it mathematically introduces multi-path, signal fading, and cross-channel correlation. With a great deal of flexibility, the ACE 400NB can also regenerate impaired signals. As such, it can be used to test and exercise MIMO algorithms and help you debug.

Channel modeling
You can also test interoperability between MIMO implementations from different vendors, too. The ACE 400NB's 4x4 channel emulation can simulate up to 16 transmissions channels, so you can measure RF interaction between devices with up to four input/output antennas.

What's more, built-in channel models are included so you can readily make performance comparisons in typical Wi-Fi scenarios. Bi-directional channel modeling also lets you simulate transmissions in forward and reverse paths. This can be used to test reciprocal channels in antenna beam-forming applications, for example.

Benchtop WLANs
For its part, Azimuth's W-Series lets you configure WLAN networkson a benchtop chassis. Providing a controlled RF environment, a W-Series box can ensure repeatability, which is what's needed to make meaningful compliance, interoperability, functional, and performance tests. The programmable W-Series lets you evaluate WLAN gear under varying conditions and traffic patterns as well.

The modular W-Series system is controlled and configured through Azimuth's Windows-based DIRECTOR test executive, with every configuration and analysis function accessed through any of three DIRECTOR components. You get a GUI, a test manager, and a standard tool command language script interface. You can even operate DIRECTOR remotely, across the Internet, for example.

In use, you plug appropriate modules plug into a W-Series chassis, and then make digital and RF connections to the system's backplane using a patented interconnect scheme that sidesteps knotty RF problems such as cable termination and impedance matching.

The selection of the system's modules and chassis can actually be connected to let you to configure setups that scale from a single basic service set (BSS) with one client, to multiple overlapping BSSs with hundreds of clients simultaneously operating in any of the three 802.11 bands and on multiple channels. Nifty, to be sure.

Virtual PositioningThe W-Series platforms also use so-called virtual positioning. That involves the creation of real-world scenarios (roaming and hidden stations). The system's virtual positioning lets you accurately position devices in relation to an entire network, using a combination of programmable attenuators.

- Alex Mendelsohn

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