How to right-size your wireless testing: Page 2 of 5

July 11, 2016 //By JFW Industries
Whether mobile devices, Internet of Things, or industrial RF applications, the world runs on wireless. As a result, wireless testing is more important than ever before. But how do you balance thoroughness, speed, and budgets? Quipping “pick any two of the three” isn’t a good answer. Testing must be thorough, fast enough to keep up with getting to market, and yet within tight budgets. Test engineers should adopt a right-sizing approach to manage trade-offs and find solutions that are the best fit for a particular situation.

Making choices

In a perfect world, you would have the most flexible test system available. It would connect any set of radios or collection of handsets and antennas that you wanted to test. Every path between two devices would have a programmable attenuator to separately adjust the signal strength between the devices and include the ability to adjust signal strength over time to simulate signal fading.

However, as the numbers of ports, potential paths, and RF components increase, so does the expense. Additional components expand the amount of rack space necessary for housing. They also put greater demands on power and heat dissipation.

If you reduce the number of components in the test system; size, power, and cooling demands decrease, as does cost. The price you pay is a loss of testing flexibility. Some test configurations may be impossible to model. Other scenarios could take longer as decreased flexibility necessitates more testing iterations to cover individual cases and more time in the schedule to accommodate additional setup and stages of testing.

In handover testing, an additional source that can balance flexibility, time, and savings is the use of manual attenuators. They are less expensive than programmable ones because they lack the circuitry for remote programming. Instead, an engineer sets them through knobs on the front of the attenuators. The manual action increases the time for configuration and cannot accommodate all testing scenarios, like fading the dB setting over time to simulate signal fading.

Even input power specifications can pressure a budget. Test equipment frequently accepts limited antenna or access point power input, like 1 W, versus a typical commercial 40 W device, because of the power dissipation characteristics of the equipment components. Adding a dedicated attenuator instead of running tests at full power is far less costly than upgrading the test system’s components.

Although not strictly a trade-off, the use of technically neutral language can broaden your options in searching for appropriate test equipment. The frequencies used by LTE wireless differ by country, for example. Specify actual frequency ranges. Companies vary in how they refer to frequency ranges. Some specify everything in megahertz; others quote gigahertz. Look for the appropriate values under each to be sure you don’t shortchange your search.

 

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