Understanding MIMO OTA Testing: Simple Solution to a Complex Test

Start Date: 3/24/2011
Location: CTIA Wireless 2011, Orange County Convention Center, Room S 330 E-F

The ever increasing spectrum efficiency requirements of MIMO mobile devices in 4G networks challenge designers to implement multiple antennas into small form factor. MIMO Over-the-Air (OTA) testing is an accurate and cost-effective solution to validate complex MIMO device performance. This MIMO Expert Forum explains the fundamentals of MIMO OTA testing, providing an understanding of system performance and the core elements that facilitate systematic and repeatable performance measurements of MIMO devices. The Forum highlights the technical features of the test system, including the chamber, software and instrumentation. Topics to be discussed include a flexible and cost-effective way to perform MIMO OTA characterization using antenna pattern measurements, concepts and underlying assumptions behind MIMO-OTA models and the importance of radio channel modeling and validation in MIMO OTA testing. A panel discussion with the speakers concludes the Forum.

Organized by:

 

The event is over, but the on-demand webcast is available for viewing here.

 

 

Speaker Presentation Downloads

 

Part 1: MIMO OTA Antenna Measurements
Doug Reed, Solutions Architect, Spirent Communications

Part 2: Radio Channel Aspects
Jukka-Pekka Nuutinen, Research Manager, Elektrobit

Part 3: Multi-path Environment Simulator
Michael Foegelle, Dir. Of Technology, ETS-Lindgren

Part 4: OTA Test Challenges and the Two-stage Methodology
Moray Rumney, Lead Technologist, Agilent

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Program Details

The MIMO Expert Forum
Moderated by

Bryan Sayler,
Vice President and General Manager,
ETS-Lindgren

The MIMO Expert Forum
speakers include:

	Moray Rumney Lead Technologist, Agilent Technologies Using Antenna Pattern Measurement for Flexible and Cost-effective MIMO OTA Characterization Click here for abstract	Dr. Michael D. Foegelle Dir. of Tech. Development, ETS-Lindgren Multipath Environment Simulation for MIMO Over-the-Air Performance Testing Click here for abstract
	Doug Reed Solutions Architect, Spirent Communications MIMO-OTA: Concepts, Underlying Models and Assumptions Click here for abstract	Jukka-Pekka Nuutinen Research Manager, Elektrobit Importance of Radio Channel Modeling and Validation in MIMO OTA Testing Click here for abstract

Sponsored by:

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Bios

Moray Rumney joined Hewlett-Packard/Agilent Technologies in 1984, after completing a BSc in Electronics from Edinburgh’s Heriot-Watt University. Since then, Moray has enjoyed a varied career path, spanning manufacturing engineering, product development, applications engineering, and most recently technical marketing. His main focus has been the development and system design of base station emulators used in the development and testing of cellular phones. Moray joined ETSI in 1991 and 3GPP in 1999 where he was a significant contributor to the development of type approval tests for GSM and UMTS. He currently represents Agilent at RAN WG4, developing the air interface for HSPA+, LTE and LTE-Advanced. In his current role as Lead Technologist specializing in LTE, Moray has published many technical articles in the field of cellular communications, and was editor of Agilent’s book “LTE and the Evolution to 4G Wireless”. Moray is a regular presenter and chairman at industry conferences where he speaks on wireless technology issues and their implications on the wider industry.

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Dr. Michael D. Foegelle is the Director of Technology Development at ETS-Lindgren in Cedar Park, TX. He received his Ph. D. in Physics from the University of Texas at Austin, where he performed theoretical and experimental research in both Condensed Matter Physics and Electromagnetic Compatibility (EMC). He performed contract EMC research with Dr. J. D. Gavenda of UT for IBM and RayProof where he helped to develop a semi-anechoic chamber modeling system. In 1994 he began working for EMCO in Austin Texas (now ETS-Lindgren). There he has been integral to the development of products, software, and test methods for Wireless, RF, and EMC testing. He has been involved in numerous national and international standards committees on EMC and wireless, including the ANSI ASC C63® working groups, the CTIA Certification Program Working Group on over-the-air performance testing of wireless devices, the IEEE 802.11 Task Group T for wireless performance prediction of 802.11 devices, the Wi-Fi Alliance Wi-Fi Mobile Convergence Group, the CTIA/Wi-Fi Alliance Converged Wireless Group, and the WiMAX Forum’s Radiated Performance Test working group. He is vice-chair of the CTIA’s MIMO Anechoic Chamber subgroup and co-chair of the CTIA’s Converged Devices ad-hoc group and has served as Vice-Chair of the Wi-Fi Alliance’s Wi-Fi/Mobile Convergence group. He was also the editor and principal contributor for the WiMAX Forum™ Radiated Performance Tests (RPT) for Subscriber and Mobile Stations test plan. He has authored or co-authored numerous papers in the areas of Electromagnetics, EMC, Wireless Performance Testing, and Condensed Matter Physics, holds several patents on wireless and electromagnetic test methods and equipment, and is dedicated to advancing the state of the art in radiated RF testing of emerging wireless technologies.

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Doug Reed is a Solutions Architect at Spirent Communications. Over the years, Doug has focused his R&D career on advancing a variety of leading edge Cellular Radio Technologies. He has more than 40 US patents in air-interface design, radio propagation, and antennas. Doug is recognized in the industry as a primary contributor to the Wideband Spatial Channel Model, and continues to work on measurement techniques for MIMO antenna systems. His current interest is in developing new channel emulation techniques to support next-generation cellular networks.

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Jukka-Pekka Nuutinen is a Senior Specialist, Wireless Communications Tools at EB, Elektrobit. Mr. Nuutinen holds a Lic. Tech. degree from Tampere University of Technology and has 20 years experience in research and development. His research interests include radio propagation, MIMO technologies and wireless telecommunication systems. Mr. Nuutinen has several publications listed in IEEE and he holds several patents in the wireless telecommunication sector.

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Moderator

Mr. Bryan Sayler has over 20 years experience developing RF test solutions with ETS-Lindgren. He is an active member of, and contributes technically to, the leading wireless industry organizations, including the WiMAX Forum®, CTIA – The Wireless Association® and the Wi-Fi Alliance®. Recently he has devoted his considerable expertise to the development of MIMO OTA testing solutions. He holds a BA degree from Southeastern University and an MBA from Baylor University.

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Abstracts

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Using Antenna Pattern Measurement for Flexible and Cost-effective MIMO OTA Characterization

By Moray Rumney, Lead Technologist, Agilent Technologies
Several methods for measuring MIMO OTA performance are being considered by CTIA and 3GPP. Most rely on the creation of a spatially rich RF environment using either a reverberation chamber or anechoic chamber with multiple antennas. An alternative method is to split the characterization into two stages. In the first stage, the device antenna pattern is measured in an anechoic chamber. The antenna pattern is characterized non-intrusively by the device measuring the amplitude and relative phase of a received signal from a know direction. In the second stage, the antenna pattern is convolved with any 2D or 3D channel model using a two channel fading emulator. The resulting signal is injected into the device receiver using the temporary antenna connector ports used for traditional conducted conformance testing. Importantly, this second stage does not require an anechoic chamber. There are several important advantages to the two-stage method of MIMO OTA characterization. It can reuse existing SISO OTA anechoic chambers of the type certified for SISO OTA and requires just one two-channel fading emulator which can precisely emulate any channel model. This provides the widest test coverage for very low cost. The method can be used to emulate the other test methods that create spatial channel models using multiple antennas or reverberation chambers. The two stage method requires support within the device chipset to measure amplitude and relative phase. It is not possible to measure device self-desensitization, but this is substantially covered by existing SISO OTA tests.

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Multipath Environment Simulation for MIMO Over-the-Air Performance Testing

By Dr. Michael D. Foegelle, Director of Technology Development, ETS-Lindgren
Over-the-air (OTA) performance testing has become an industry staple for evaluating edge-of-link performance of mobile terminals. Metrics like Total Radiated Power (TRP) and Total Isotropic Sensitivity (TIS) are determined by evaluating the transmit or receive radiation pattern of the mobile device to predict average performance that correlates directly to dropped call statistics and related industry performance metrics. A fundamental assumption of these test methodologies is that the radiation pattern of the device under test (DUT) remains constant throughout the measurement process. Modern wireless devices use multiple antenna technology with adaptive algorithms that violate this assumption. In addition, with the emergence of MIMO based bandwidth enhancements, the focus of performance testing is expected to move from edge-of-link performance to edge-of-throughput performance, where services like streaming video will degrade below acceptable levels. Since the performance of MIMO and other multi-antenna technologies is not just a property of the mobile device itself, but also the environment in which it is used, new OTA performance test methods must be able to simulate a range of real-world RF environments. This presentation will show how this is done using an anechoic chamber to isolate the DUT in a controlled environment and an array of measurement antennas to produce an RF boundary condition that can simulate various angles of arrival around the DUT. RF channel emulation is then used to simulate the desired multipath environment and propagation conditions needed to evaluate MIMO performance. Measurement results for device performance testing and site validation will be presented.

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MIMO-OTA: Concepts, Underlying Models and Assumptions

By Doug Reed, Solutions Architect, Spirent Communications
Evaluating MIMO devices has become an active topic within standards bodies, with a wide variety of proposed over-the-air testing techniques under discussion. Since the methods utilize different approaches, it is important to step back and compare the underlying assumptions in order to understand the capabilities and limitations of each method. This discussion provides a conceptual basis for making comparisons and charts some possible next steps.

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Importance of Radio Channel Modeling and Validation in MIMO OTA Testing

By Jukka-Pekka Nuutinen, Senior Specialist, Wireless Communications Tools, Elektrobit
This presentation introduces one major element of the modern MIMO OTA test system, radio channel and its validation process. The ever increasing spectrum efficiency requirements of MIMO mobile devices impose designers with a challenge to provide multiple antennas into small form factor with good MIMO performance. The designers need to pay special attention to antenna design, but also to correlation properties and to many other radio channel phenomena. This presentation explains the MIMO OTA test system from the radio propagation perspective, since the radio propagation effects, such as spread of the signal, define the correlation properties of the signals and therefore control the performance of the MIMO device. Also, an understanding of radio channel emulator’s important capability to create pre-defined and repeatable propagation conditions inside the anechoic chamber is provided. The focus of the presentation is on a wide range of radio propagation studies. Participants will get a comprehensive idea of what needs to be highlighted in the MIMO OTA tests from the radio propagation perspective.