LTE MIMO throughput measurement method for characterization of multi-antenna terminal performance

This paper presents experiences and results from LTE MIMO throughput measurements of a USB dongle in a reverberation test system. The measurements are performed with the dongle itself and also when it is connected to external diversity antennas with high and low correlation. Three different maximum bit rates are used, 59, 70 and 81 Mbps. The results illustrate that it is possible to separate a good antenna design from a bad from reverberation chamber measurements. Also, the effect of using a laptop test fixture, or a laptop dummy, instead of having the host computer present in the chamber, is demonstrated. It is shown that the noise induced by the host computer degrades the performance of the dongle

MIMO LTE OTA measurements in reverberation chamber: rich isotropic reference environment makes agreement with theoretical system model

The reverberation chamber has during the last 10 years been developed into an accurate instrument for OTA measurements, having a well-defined rich isotropic multipath environment. This has been introduced as a new reference environment for testing of wireless devices, complementing the traditional anechoic reference environment. The rich isotropic multipath environment and the definition of an ideal error-correcting digital receiver have made it possible to develop simple theoretical models that predict the measured throughput data rate in a reverberation chamber versus received power within a few tenth of dBs The present paper overviews the developments of the reverberation chamber that has made it possible to achieve such agreement, as well as the on-going work of determining relevance of the rich isotropic environment compared to real-life environments

LTE MIMO multiplexing performance measured in reverberation chamber and accurate simple theory

We present measurement results of the data-rate throughput inside a reverberation chamber of a commercial USB dongle operating in 2×2 MIMO spatial multiplexing configuration. A simple and accurate theory is provided by which the measured throughput can be accurately explained. The theory is based on a recently published digital threshold receiver model

Measurements of RFID Tag Sensitivity in Reverberation Chamber

The reverberation chamber is now commonly accepted and used for fast and accurate performance evaluation of mobile phones and other wireless devices for in particular new systems such as LTE 4G and IEEE 802.11n Wi-Fi. In this letter, we describe a new methodology of measuring sensitivity of RFID tags in a reverberation chamber, and we show how the measurements time can be shortened by using the fact that the RFID tag behaves like an ideal threshold receiver. We then extend to tag population measurements that can be used to select the best tag among the many during the same measurement sequence

Evaluation of multi element antennas in reverberation chamber

This paper focuses on the latest advances in the use of reverberation chambers for active device testing. Contained are description and comparison of different figure-of-merits that are applicable to multi element antennas, with a specific focus on LTE devices with MIMO capability. There are two new parameter concepts introduced: Modified Total Isotropic Sensitivity measurements to include MIMO signaling, and a Throughput Threshold Level for simplified quantification of data bit throughput measurement results

Characterization of Reverberation Chambers for OTA Measurements of Wireless Devices: Physical Formulations of Channel Matrix and New Uncertainty Formula

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

A new compact wideband MIMO antenna – the double-sided tapered self-grounded monopole array

We present a new compact wideband multiple input multiple output (MIMO) antenna—the double-sided 4-port arm-tapered self-grounded monopole array, briefly referred to as the butterfly antenna, in the communication. The antenna is very compact with low correlation between ports and high diversity gain. The genetic algorithm optimization scheme has been employed in the design. Simulation results have been verified against measurements. The measured reflection coefficients at all ports are below -7 dB over 0.5–9 GHz and below -4.5 dB over 0.4–0.5 GHz and 9–15 GHz. The measured correlation coefficients are below 0.4 over 0.4–15 GHz and lower than 0.1 in most of the frequency band. This new MIMO antenna is developed as a transmit antenna in reverberation chambers, and we believe that it will find more applications in other systems, such as micro base station antennas in wireless communication systems

Threshold Receiver Model for Throughput of Wireless Devices with MIMO and Frequency Diversity Measured in Reverberation Chamber

We present a simple theoretical model for the throughput data rate of a wireless LTE device including the improvements of data rate due to diversity in frequency (OFDM) and spatial domains (MIMO) under frequency selective fading. The model is based on defining an ideal threshold receiver for the line-of-sight (LOS) case, corresponding to reception with advanced error-correcting codes. The theoretical throughput model is in agreement with measurements in a reverberation chamber of a commercial LTE device for the 1 x 2 SIMO case, both regarding diversity and MIMO array gains, and it can therefore be used to complement measured results in evaluation of performance of LTE devices