To more accurately predict the real-world performance of a mobile device, both standards organizations and network providers are increasingly turning to over-the-air (OTA) testing. The Cellular Telecommunications Industry Association (CTIA), for example, has defined the methods and set the standards for performing OTA testing. In a four-page white paper, RFMD (www.rfmd.com) examines test methods specified by CTIA for OTA tests on a mobile device.
Typically, mobile devices have been tested under nominal 50-Ohm conditions by connecting to the antenna connector port and performing measurements with a test source and analyzer. OTA tests are performed by placing the mobile device in an anechoic chamber. A range of test equipment is then used to evaluate its performance. The base-station simulator (BSS), for example, communicates with the mobile device using a particular protocoljust as it would in an actual call.
According to CTIA standards, mobile cellular communications devices must be tested at two frequencies: 836.5 and 1880 MHz. They also have to be tested in two positions: in free space and attached to a Specific Anthropomorphic Mannequin (SAM) phantom head. During OTA testing, the main focus of evaluation is transmit and receive performance. The key parameters that are measured include total radiated power (TRP), near-horizon partial radiated power (NHPRP) values, total isotropic sensitivity (TIS), and near-horizon partial isotropic sensitivity (NHPIS) values. The note defines each of these measurements and then details how to perform them.
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