Christopher D. Ziomek and Matthew T. Hunter Ph.D
ZTEC Instruments, Inc. Albuquerque, New Mexico, USA
This paper discusses the practical constraints of testing Radio Frequency Integrated Circuit (RFIC) devices in a Multiple-Input Multiple-Output (MIMO) topology. Techniques to optimize test equipment setup and operation for MIMO architectures are detailed. Because RFICs are tested at a device level, this paper focuses on MIMO compliance testing and characterization within a cabled RF environment without open-air antennas. The IEEE 802.11 WLAN protocol is used as an example to detail the theory, specific use cases, and test scenarios.
The drive to increase wireless data rates within the limited radio frequency (RF) spectrum has led to radios with capabilities beyond a single-input single-output (SISO) topology. SISO radio devices use one transmitter and one receiver to send data over a single RF channel. Recently introduced wireless protocols have adopted Multiple-Input Multiple-Output (MIMO) topologies that use two or more transmitters and two or more receivers to send data simultaneously over the same RF bandwidth. For example, the IEEE 802.11n/ac WLAN and IEEE 802.16e WiMAX standards include MIMO functionality.
In this paper, we discuss MIMO RF topologies and the implications of MIMO on Radio Frequency Integrated Circuit (RFIC) test. Because MIMO topologies make use of multi-path signal transmission in a highly-scattered open-air environment, there are implications when testing MIMO RFIC devices in a cabled RF environment. This paper focuses on verification of MIMO RFIC performance using a cabled RF test topology. We use IEEE 802.11 WLAN to illustrate the details of MIMO test equipment setup and operation for a specific protocol.
Full Paper (.pdf): MIMO_RFIC Test_Architectures