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Introduction

Over-the-Air (OTA) testing is becoming increasingly important as standards organizations and network providers move to introduce test specifications that more accurately predict the real-world performance of a mobile device. The Cellular Telecommunications Industry Association (CTIA) has defined the methods and set the standards for performing over-the-air testing, but specifications for the RF performance of the mobile devices have not yet been formally established by the European Telecommunication Standards Institute (ETSI) or the 3rd Generation Partnership Project (3GPP). Standard testing methods specified by CTIA for completing OTA tests on a mobile device will be discussed in their different modes. In addition, the parameters that are used to evaluate the RF performance of a mobile device are presented.

Overview

To better predict the real-world performance of mobile devices, OTA tests have been developed to test the RF performance of a mobile device. Mobile devices have been tested typically under nominal 50 ohm conditions by connecting to the antenna connector port and performing measurements. Testing the mobile device in this way does not accurately describe the range of conditions that the end user might present. OTA tests, in addition to the classical handset tests, serve to provide a better feel for the real world performance of the mobile device. OTA tests are performed by placing the mobile device in an anechoic chamber and using a range of test equipment to evaluate the performance of the device. CTIA test specifications require that the mobile device be tested under free space conditions, as well as attached to a special mannequin to simulate talk position near a human head. Certified OTA tests are performed in a CTIA Authorized Test Laboratory (CATL), which are laboratories that have received accreditation from CTIA. At the time of this writing there are twenty-four CATL laboratories in the world; ten in the United States, four in Taiwan, two in China, two in Germany, two in South Korea, two in the United Kingdom, one in Canada, and one in Finland. In November of 2004, there were only five CATL laboratories, four in the United States and one in Finland. That means that the number of CATL laboratories has quadrupled in a very short amount of time. This trend demonstrates the increasing importance that is being placed on OTA testing for mobile devices. Some network providers, such as Cingular Wireless, are already setting specifications for the OTA performance results of mobile devices intended for use on their network.

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•White Paper: Over-The-Air Testing