MIMO Wireless Terminals OTA Performance Test Based on Boundary Array Methodology
MIMO antenna technology is commonly used in high speed wireless communication (LTE, WIFI, WIMAX) as well as in high performance radar (MIMO radar). There are more and more wireless terminals with MIMO antenna around the current market. However, there are no current standardized measurement methodologies to evaluate the new technology. The main international standardization organizations, including 3GPP, CTIA and the national organization of China (CCSA), are working to standardize the test methodology. Part of the difficulty in completing a standard of the test method is due to the fact that channel models of multi-path environments complicate the test system to a large degree. Such complexity can be taken into account by the methodology based on boundary array OTA method that makes it a very important evaluation candidate for MIMO OTA performance test. The paper presents a real MIMO OTA test system. After the introduction of boundary array concept, the system calibration is described, including input and output calibration of the entire system. Subsequently, the system validation is examined from several aspects, such as power validation, filed mapping, temporal correlation and so on. Finally, the measurement results of an actual wireless product, with three different antennas, are provided to further elaborate the test methodology. At the end, the current status of the MIMO OTA test methodology standardization is provided to conclude the paper.