Best Practices for Making Accurate WiMAX™ Channel-Power Measurements

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  • Author: David Huynh and Bob Nelson
Today’s wireless designers are challenged to deliver state of the art devices. Rapid changes in technologies, along with the commercial promise of these modern gadgets, are forcing them to be more attentive to delivery schedules while at the same time ensuring that their designs conform to interoperability specifications. Although many wireless technology standards provide power specifications, the procedures for making these measurements are often unclear and therefore, the likelihood of making them incorrectly is high. This is especially the case with Mobile WiMAX™ signals due to the inherent complexity of the OFDM-based RF waveforms employed in the IEEE 802.16 standard. Consequently, spectrum analysis fundamentals must be properly understood and taken into account by the engineer. And, with the “burst” nature and high peak-to-average ratios encountered in WiMAX waveforms, the triggering techniques to be used and associated gating parameters have become critical to obtaining valid easurements of power and spectrum. As a result, a fundamental challenge that wireless designers now face with WiMAX is making accurate, repeatable and verifiable channel-power masurements. This article provides critical information for making WiMAX channel-power measurements. The principles presented also apply to the three main WiMAX power measurements: transmit power, adjacent channel power and spectral emissions pass/fail testing.