Analysis And Research On The Uncertainty Of OTA Measurement System

With the increasing complexity of current network environment, good radiation performance of the mobile station is more significant. About RF performance testing, people increasingly value the overall performance of the mobile station, which directly reflects the final transmit and reception performance. Mobile station over the air performance(i.e. OTA, over the air) is an effective method to measure the overall performance of a mobile station, which is an active testing and mainly consists of two parts: the total isotropic radiated power(TIRP, Total Isotropic Radiated Power) and total isotropic radiated sensitivity(TIRS, Total Isotropic Radiated Sensitivity).The measurement uncertainty is an important basis in judging measurement results and ensuring the accuracy of laboratory measurements. As integrated measurement tools, test system has its system uncertainty, which would produce a non-negligible impact to the measurement result. According to ISO/IEC 17025, the uncertainty of test system must be evaluated. A complete test data and report should include information about the uncertainty. So we should analyze and research the uncertainty of OTA measurement system, which provides a guarantee to the reliability of OTA measurements and improves the accuracy of test data.This paper firstly introduces the basic concepts of uncertainty and general evaluation method, laid the theoretical foundation for the subsequent analysis. Secondly, the principles and components of OTA testing system are described in detail. Thirdly, in accordance with the analysis of OTA test system in front, the article will give the mathematical models which conforms to the actual measurement process of the laboratory and identify the various impact factors of uncertainty comprehensively, then through the statistical methods and technical datasheet, quantitatively calculate the total uncertainty and give uncertainty report. Finally, according to the analysis of the report, the article will propose some effective recommendations to reduce the uncertainty of OTA measurement system. In this paper, the uncertainty of Tianjin Radio Monitoring Station's OTA measurement system meets the standard YD/T 1484-2011 with the relevant requirements, which reflects OTA measurement capability of the laboratory.