Goteborg, Sweden
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Lotback C.S.P.,Bluetest
2017 11th European Conference on Antennas and Propagation, EUCAP 2017 | Year: 2017

The wireless industry is getting deeply engaged in the 5th generation communication standard. Despite lack of clear definitions, there are some parameters of the emerging standard which are commonly accepted. Higher frequencies (frequencies above 6 GHz) in the millimeter wave spectrum will be a key component for enabling a massive increase of the available bandwidth and thus data rates for the end users. This will however impose challenges on the test equipment for the wireless devices operating on these frequencies. The Over-the-Air test facilities used today for 4G and legacy standards are optimized for operation below 6 GHz. A frequently used tool for Over-the-Air performance assessment is the reverberation chamber. This paper will analyze the feasibility of the reverberation chamber to be extended to the frequencies considered for 5G. © 2017 Euraap.

Lotback C.S.P.,Bluetest | Skarbratt A.,Bluetest | Arvidsson K.,Bluetest
2017 11th European Conference on Antennas and Propagation, EUCAP 2017 | Year: 2017

The 4:th generation communication standard is constantly evolving with more features being added to the standard specifications. Carrier aggregation and higher order MIMO are examples of features used to support higher data rates. The addition of features puts new requirements on wireless devices and this increasing complexity implies that Over-the-Air testing is more important than ever. At the same time it is important to keep the complexity of test setups to a minimum and to reduce measurement time, given the constant addition of new test cases. This paper elaborates on the reverberation chamber as a fast, accurate and comprehensive Over-the-Air testing environment for assessing advanced features of state-of-the-art wireless devices. It is shown that a number of different testing scenarios can be realized with one test chamber using time efficient measurement algorithms. This test chamber can also be used for legacy standards and for assessing traditional metrics for antenna and wireless device performance. © 2017 Euraap.

Lotback C.P.,Bluetest | Arvidsson K.,Bluetest | Hogberg M.,Huawei | Gustafsson M.,Huawei
2017 11th European Conference on Antennas and Propagation, EUCAP 2017 | Year: 2017

Base station conformance and performance testing is traditionally carried out in a conducted manner, i.e. test instruments are connected via cables to physical ports on the base station. As the complexity of the base station transceiving circuitry increases and more and more antennas are added to the transceiving links, new measurement techniques based on Over-the-Air metrics are needed. This is especially important for base stations for the new emerging 5G standard. The reverberation chamber is a good candidate for these tests, given its short test times and low test setup complexity. The reverberation chamber is already a frequently and well-proven tool in the wireless industry to assess performance of user equipment and the extension to base station testing is straightforward. This paper elaborates on the feasibility of the reverberation chamber for base station Over-the-Air testing. Several key parameters are measured and compared to results from conducted testing, showing that the metrics currently measured in conducted mode can be translated to Over-the-Air metrics with high accuracy. In addition, an analysis of major uncertainty contributions is provided. This analysis shows that there is insignificant impact on the measurement accuracy when measuring antennas with high gain in the reverberation chamber. © 2017 Euraap.

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.

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.

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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