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Multiple-input, multiple-output (MIMO) systems use multiple antennas at both the transmitter and receiver to improve communication performance. MIMO technology offers significant increases in data throughput and link range without additional bandwidth or increased transmit power. It achieves this goal by spreading the same total transmit power over the antennas to achieve an array gainthat improves the spectral efficiency (more bits per second per hertz of bandwidth) and/or to achieve a diversity gain that improves the link reliability (reduced fading). The increased data throughput offered by MIMO is being utilized in LTE communications and RADAR systems.
EDI CON 2014 to be held at the Beijing International Convention Center, April 8th through 10th will feature a dozen technical papers and workshops on MIMO design and related test/verification solutions. The following is a summary of the paper topics and speakers presenting their work in this area. In addition, the exhibition will feature products and demonstration from leading MIMO test and measurement equipment providers such as Spirent Communications, Agilent Technologies, Microwave Vision Group, General Test Systems (Tri-L), National Instruments and more.
MIMO OTA Channel Validation
By Hui Xiao , Spirent (United States)
The complexity of assessing MIMO performance has driven a need to supplement traditional conducted testing with testing using controlled radiated signals, giving rise to several methods of implementing Over-the-Air (OTA) testing. While different OTA approaches have been presented and discussed by industry leaders, the main contenders involve the use of either reverberation chambers or anechoic chambers. While topically similar, these two methods invoke differences in cost structure, accuracy, and depth of detail in the modeling required to take advantage of higher degrees of accuracy.
MIMO Antenna System Simulation CST Workshop
By Cier Siang Chua, CST (Singapore)
Multiple-input, multiple-output (MIMO) systems are a major field of study for researchers interested in achieving high data rate communication in typical urban multi-path environments. Although a fast analysis can be based on S-parameters, this approach has limitations. A more detailed analysis needs to take into account broadband, farfield and antenna properties. These are especially important in presence of the human body. This workshop will show how simulation can be used to calculate the effect of hand and head (e.g. CTIA models) on mobile devices, MIMO for wearable antennas and different power weighting functions for different environments, along with post-processing options for envelope correlation (including spatial power weighting functions), derived quantities diversity gain and multiplexing efficiency. Finally, there will be a demonstration of the link between CST MICROWAVE STUDIO® and Optenni Lab for multiple antenna matching to optimize power transfer to antennas while minimizing cross-coupling.
Board Level Noise Coupling and LTE MIMO Antenna Design – EMSS Workshop
By Peter Futter, EMSS (South Africa)
This technical FEKO workshop will cover two case studies which highlight the role of electromagnetic simulation in modern wireless device design. The first study deals with a novel approach to investigate PCB board level noise interference issues. In this joint project with Samsung Electronics, FEKO's Characteristic Mode Analysis (CMA) was applied to study the modal behavior of noise sources, and how they couple to the antenna receive port. The second study covers the typical design and integration challenges for mobile devices. The integration of a dual element LTE MIMO configuration is used to highlight these concepts.
Prototyping Massive MIMO
By James Kimery, NI (United States)
Massive MIMO presents several challenges to researchers. Along with the technical challenges of beam forming and pilot “pollution”, prototyping a Massive MIMO system presents several challenges. With an order of magnitude number of antennas, the complexity of the receiver and transmitter increases the computational and data throughput requirements requiring an analysis of algorithm efficiency in implementation and perhaps new architectural data conduits to move the raw bits to the processing elements where the bits are processed to usable data. Massive MIMO holds much promise but if it is not feasible then it’s simply research. This paper will examine the challenge of prototyping a Massive MIMO and will also present some data from this analysis.
MIMO OTA Driving Industry Testing and Standards
By Simon Wang, Spirent (China)
This panel will be led by Spirent and will include industry participants (ETS-Lindgren, CTIA, PCTest, TMC) representing various aspects of the wireless ecosystem, metrology/compliance labs and standards body responsible for determining over-the-air (OTA) testing requirements specific to the Asia market. Spirent and the other panelists will share their perspectives on the factors driving Over-The-Air (OTA) test methodologies as a means to achieve a complete picture of real-world performance for mobile devices and base stations as well as the impact of emerging standards on carrier networks and OEMs.
ETSI MIMO Wireless Device Regulatory Test System
By Chin Aik Lee, Agilent Technologies (Malaysia)
and Brian Chi, Agilent Technologies Taiwan (Taiwan)
The MIMO wireless connectivity method has been widely used in today’s broadband data transmission equipment. However, with the revision of the ETSI EN 300 328 v1.8.1 test standard, new requirements for multi-channel RF power measurement have been defined which also could be leveraged to other test standards like EN 301 893.v1.7.1. Conforming to these new RF power measurement requirements presents the test challenges that will be addressed in this paper.
Performance of the Dual Polarized Spatial Channel Model including: Ergodicity, Spatial, and Temporal Characteristics
By Doug Reed, Spirent (United States) presented by Ron Borsato Spirent (United States)
The Spatial Channel Model (SCM) was developed more than a decade ago as a system level simulation for the evaluation of MIMO performance. The original model included single and dual polarized versions, along with Macro, Micro, and Suburban environment types. Later, additional models added more capabilities, with the same dual polarized methodology. These subsequent models include: SCME, Winner I & II, and ITU models, which are currently used in numerous standards. Since the original model was published, hundreds of papers have referenced the SCM or later versions of the model in their MIMO performance evaluation. In link level applications, the normally random polarization states, which were defined to facilitate the system level simulation, must be fixed along with all other small and large scale parameters. Only when all parameters are fixed is the link level model Ergodic, and when the proper selection of the polarization state is made, will the model produce the theoretical cluster behavior. This paper investigates how to use the model at the link level, and explains what is needed to achieve the expected result for both the spatial and temporal behaviors, along with the proper generation of an ensemble of sequences.
Measurement of I/Q Mismatch in MIMO-OFDM Transmitters
By Ziquan Bai (Agilent)
Multiple input multiple output (MIMO) and orthogonal frequency division multiplexing (OFDM) are the most promising technologies for wireless communications in foreseeable future and have been widely adopted in both cellular and non-cellular standards, such as 3GPP LTE and WLAN 802.11ac, etc. Transmitter I/Q mismatch, as one of the major radio frequency (RF) impairments, greatly degrades the performance of MIMO-OFDM systems in practice. Thus, I/Q mismatch must be accurately measured to qualify MIMO-OFDM transmitters. Established methods for I/Q mismatch measurement depends heavily on calibration of the measurement channel” between the transmitter under test and instrument. Improper calibration may result in significant loss of measurement accuracy. However, in many cases, the calibration is very cost- and time-consuming or even impossible to be realized. In this paper, we analyzed the challenges in measurement of I/Q mismatch in MIMO-OFDM transmitter, and then introduced the I/Q mismatch measurement method implemented in Agilent VSA, which addresses the problem of measurement through un-calibrated measurement channel and therefore enable I/Q mismatch measurement in more test applications. Feasibility of the new method is demonstrated by examples.
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