Goteborg, Sweden
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Karlsson K.,Technical Research Institute of Sweden | Chen X.,Chalmers University of Technology | Carlsson J.,Technical Research Institute of Sweden | Skarbratt A.,Bluetest
IEEE Antennas and Wireless Propagation Letters | Year: 2013

In this letter, over-the-air (OTA) tests of the performance of the IEEE 802.11p radio system are performed in a reverberation chamber (RC) that is equipped with a fast rotating mode stirrer. By varying the speed of the mode stirrer, different levels of Doppler spreads are created, and the 802.11p radio system is tested accordingly. As expected, the Doppler spread affects the package error rate (PER) of the radio system adversely. In addition to measurements, a simple PER model is presented, which sheds some light into the OTA tests. © 2002-2011 IEEE.

Kildal P.-S.,Chalmers University of Technology | Orlenius C.,Chalmers University of Technology | Orlenius C.,Bluetest | Carlsson J.,Chalmers University of Technology | Carlsson J.,SP Technical Research Institute of Sweden
Proceedings of the IEEE | Year: 2012

New over-the-air (OTA) measurement technology is wanted for quantitative testing of modern wireless devices for use in multipath. We show that the reverberation chamber emulates a rich isotropic multipath (RIMP), making it an extreme reference environment for testing of wireless devices. This thereby complements testing in anechoic chambers representing the opposite extreme reference environment: pure line-of-sight (LOS). Antenna diversity gain was defined for RIMP environments based on improved fading performance. This paper finds this RIMP-diversity gain also valid as a metric of the cumulative improvement of the 1% worst users randomly distributed in the RIMP environment. The paper argues that LOS in modern wireless systems is random due to randomness of the orientations of the users and their devices. This leads to the definition of cumulative LOS-diversity gain of the 1% worst users in random LOS. This is generally not equal to the RIMP-diversity gain. The paper overviews the research on reverberation chambers for testing of wireless devices in RIMP environments. Finally, it presents a simple theory that can accurately model measured throughput for a long-term evolution (LTE) system with orthogonal frequency-division multiplexing (OFDM) and multiple-input-multiple-output (MIMO), the effects of which can clearly be seen and depend on the controllable time delay spread in the chamber. © 2012 IEEE.

Orlenius C.,Bluetest
2013 7th European Conference on Antennas and Propagation, EuCAP 2013 | Year: 2013

The breakthrough of mobile phone communications in the late 1990's led to the invention and development of reverberation chambers for Over-the-Air measurements of wireless devices at Bluetest and Chalmers University of Technology. This paper gives a short description of the most important events over the course of 13 years in the development from early idea to worldwide acceptance and commercial success. The history given here will focus on the scientific achievements over the years, with some mentions of the commercial development. © 2013 EurAAP.

Kildal P.-S.,Chalmers University of Technology | Chen X.,Chalmers University of Technology | Orlenius C.,Bluetest | Franzen M.,Bluetest | Patane C.S.L.,Bluetest
IEEE Transactions on Antennas and Propagation | Year: 2012

The paper deals with reverberation chambers for over-the-air (OTA) testing of wireless devices for use in multipath. We present a formulation of the S-parameters of a reverberation chamber in terms of the free space S-parameters of the antennas, and the channel matrix in the way this is known from propagation literature. Thereby the physical relations between the chamber and real-life multipath environments are more easily explained. Thereafter we use the formulation to determine the uncertainty by which efficiency-related quantities can be measured in reverberation chamber. The final expression shows that the uncertainty is predominantly determined by the Rician K-factor in the reverberation chamber rather than by the number of excited modes, assumed by previous literature. We introduce an average Rician K-factor that is conveniently expressed in terms of the direct coupling between the transmitting and receiving antennas (corresponding to a line-of-sight contribution) and Hill's transmission formula (corresponding to a multipath or non-line-of-sight contribution). The uncertainty is expressed in terms of this average K-factor and geometrical mode stirring parameters, showing strong reduction by platform and polarization stirring. Finally the formulations are verified by measurements, and the new understanding of uncertainty is used to upgrade an existing reverberation chamber to better uncertainty. © 1963-2012 IEEE.

Skarbratt A.,Bluetest | Asberg J.,Bluetest | Orlenius C.,Bluetest
Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011 | Year: 2011

This paper discusses the possibilities of using the reverberation chamber as a multipath emulator for testing of wireless terminals, especially those with multi-antenna solutions implemented. The tests are consisting of measurements of data bit throughput, in order to relate the performance of the terminal to an end-user experience. The experimental part includes HSDPA measurements with focus on overall system performance in different channel models, and LTE measurements of individual antenna parameters. © 2011 EurAAP.

Pirkl R.J.,U.S. National Institute of Standards and Technology | Remley K.A.,U.S. National Institute of Standards and Technology | Patane C.S.L.,Bluetest
IEEE Transactions on Electromagnetic Compatibility | Year: 2012

This contribution evaluates the utility of several different metrics for studying correlation between reverberation chamber measurements collected at different stirrer positions. Metrics considered are the autocovariance, the correlation matrix, and two metrics based upon the entropy of the data correlation matrix: 1) the effective number of uncorrelated measurements and 2) the measurement efficiency. The different metrics are shown to be useful for different correlation analyses. Application of these metrics reveals that the correlation between reverberation chamber measurements is strongly affected by stirring methodology, loading configuration, and measurement frequency. © 2012 IEEE.

Bluetest | Date: 2012-11-30

Transportable chambers, buildings and rooms of metal used for checking and measuring the operation of antennas and wireless devices. Computer software for use in checking and measuring the operation of antennas and wireless devices; Electric apparatus and instruments for checking and measuring the operation of antennas and wireless devices; Antennas for transmitting and receiving electromagnetic radiation; antenna holders; Switches for transmitting radio signals. Installation, maintenance and repair of equipment and apparatus for checking and measuring the operation of antennas and wireless apparatus. Design and development of computer programs and software; Maintenance of computer software; Technical support services, namely, troubleshooting of computer software problems; Technical consultancy in the field of equipment for checking and measuring the operation of antennas and wireless devices; Design and development of equipment and apparatus for checking and measuring the operation of antennas and wireless devices.

An apparatus including a chamber that defines an internal cavity therein, adapted to enclose the device under test, and including walls of an inwardly reflective material, rendering the walls reflective to electromagnetic waves, thereby simulating a multi-path environment. Thus, the chamber is a reverberation chamber. At least one moveable object and chamber antenna are arranged in the cavity. A measuring instrument is connected to the device under test and the chamber antenna, for measuring the transmission between them. Further, an improved antenna holder is disclosed, comprising three surfaces of a reflective material, said surfaces extending in planes which are orthogonal in relation to each other and each surface facing away from the other surfaces, and wherein a chamber antenna is arranged on each of said at least three surfaces. Other improvements relate to video surveillance, channel emulation and shielding.

News Article | August 25, 2008

When murmurs of the new iPhone’s purported subpar 3G performance made its way around to Sweden, a company called Bluetest decided to try and determine once and for all if we all just had a case of the crazies. They stuck an iPhone 3G into a $110,000 noise-free chamber along with a simulated base station, and tested communications in both directions. Then they did the same tests with a Sony Ericsson P1 and a Nokia N73. Turns out, they all performed about the same. Great news, right? Unfortunately, the test doesn’t really prove anything. It appears that they only tested one of each handset, which wouldn’t expose flaws between batches. More importantly, it seems they only tested it against 3G, which completely ignores the EDGE/3G hand-off that many people believe to be the problem. Oh well. At least we know the iPhone works great in a noise-proof box.

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