Interpreting the Total Isotropic Sensitivity and Diversity Gain of LTE-enabled wireless devices from Over The Air Throughput Measurements in Reverberation Chambers

The characterization of the performance of wireless devices is the key to developing new RF products conforming to the latest communications protocols. Traditionally, communication performance tests have focused on the RF performance of the tested devices, e.g., smart phones, pads, laptops, etc. More specifically, the focus has shifted from conducted (i.e., cabled) measurements to more realistic Over-The-Air (OTA) characterization of the RF performance of these devices in transmit or receive mode. For example, the receiver performance of 2G and 3G wireless devices can be measured in terms of the total isotropic sensitivity (TIS) that depends on the antenna and the receiver parts of a wireless device. These measurements can be performed in a reverberation chamber setup. However, standard TIS measurements can be time consuming and do not reflect the actual performance gains of Multiple-Input Multiple- Output (MIMO) antenna systems operating over Orthogonal Frequency Division Multiplexing (OFDM) channels, such as those encountered in 4G Long Term Evolution (LTE) systems. Therefore, in order to meet both time and cost efficiency requirements, we propose here a new method to determine the TIS, as well as the diversity performance, of an LTE device based on throughput measurements. The proposed method shows that the TIS of an LTE device is characterized much faster directly from OTA throughput measurements than from standard TIS measurements and with excellent accuracy

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

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

Measurements of relative Throughput in Reverberation Chamber using Universal Software Radio Peripheral

This paper aims to show how Universal Software Radio Peripheral can be used in conjunction with reverberation chamber to measure throughput of wireless communication systems in Rich Isotropic Multipath environment. The results are in agreement with theories based on the threshold receiver model

Diversity gains of multiport mobile terminals in multipath for talk positions on both sides of the head

The paper studies the over-the-air (OTA) performance of a mobile terminal. A practical two-port mobile terminal model on the left side and the right side of the head for both standard cheek position and standard tilt position is used to study the diversity gains. The diversity gain has been determined by measurements in a reverberation chamber as well as by simulations using the far field patterns from CST Microwave Studio, and then exposing these patterns to rich isotropic multipath (RIMP) environment in a ray-based simulation tool

Characterization of Small Antennas & Wireless Devices for MIMO Systems in Rich Isotropic Multipath & Random Line-of-Sight

The current thesis is about over-the-air (OTA) performance characterization of wireless terminals in rich isotropic multipath (RIMP) environment as well as in pure line-of-sight (LOS) environment while not ignoring the random positions and orientations of the mobile terminals due to randomness of the user. The latest mobile wireless terminals such as iPhone and iPad can be used in any random position and orientation thereby making the received LOS-component to appear as a random voltage at the antenna ports. The terms such as "RIMP" and "Random-LOS" are coined to represent two limiting environments for OTA performance characterization of mobile terminals. The RIMP environment is emulated by reverberation chambers while pure-LOS is emulated by anechoic chambers. Mobile terminals are mostly used in multipath environments, e.g. indoor environments and therefore the focus of this thesis is about measuring and simulating diversity gains, channel capacity, and throughput of wireless devices in a RIMP environment. The papers [A-D] discuss some work related to using RIMP as a reference environment and study convergence of diversity gains and capacity. The reverberation chamber has been used to measure both passive antennas and complete active wireless devices for many years. Recently, the active measurements of Long Term Evolution (LTE) or 4G devices have become very important in order to test implemented Multiple-Input Multiple-Output (MIMO) diversity and Orthogonal Frequency Division Multiplexing (OFDM) technology. Features such as adaptable modulation scheme, system bandwidth, coding rate, and diversity have made communication system more robust and adaptable to the environment. A theory to estimate the OTA throughput of LTE devices including the diversity gains due to MIMO and OFDM is presented and tested for different LTE system bandwidths and coherence bandwidths in papers [E-H]. During the last few years, we have developed multipath environment simulation tools to study convergence, to validate measurements in RIMP, and to study other multipath environments for comparison. Most of the work in this thesis is based on these simulation tools i.e. Rayleigh-lab and ViRM-lab. A section of many listed papers discuss about these simulation tools. At Chalmers University, a multiport ultra-wideband (UWB) bow-tie antenna has been designed and developed during last few years. The OTA performance characterization of this antenna has been done by measurements and simulations in RIMP environment. The results are discussed in papers [I-J]. The OTA performance characterization of single-port mobile terminals has been studied for several years now. Today, we have LTE mobile terminals with multiport antennas which must be be characterized for OTA environments. The OTA performance characterization of a two-port mobile phone mockup on both sides of the head following standardized talk positions is presented and discussed in papers [K-L]. The OTA performance of a compact UWB antenna developed for mobile phone applications at Linkoping University is discussed in paper M. The antenna covers all important bands such as GSM, UMTS, LTE, Bluetooth, and WLAN, etc. Keywords: OTA, RIMP, Rayleigh, reverberation chamber, random LOS, LTE, MIMO

Optimizing Small Wideband Antenna Performance for Both RIMP and Random-LOS

Rich Isotropic Multipath (RIMP) environment like reverberation chamber (RC) has proven to be useful for characterizing mobile LTE devices. The user statistics have larger effect in environments with stronger Line-Of-Sight (LOS), because the angle of arrival (AoA) and the polarization of the LOS contribution become randomized due to the user. Thus, we introduce the term Random-LOS. The present paper elaborates on characterization of an example antenna in both RIMP and random-LOS. We show how to characterize the micro BTS by the probability of detection (PoD) of one and more bitstreams in both RIMP and random-LOS, by considering the user randomly located and oriented within the angular coverage sector. We limit the treatment to a wall-mounted BTS antenna, and assume a desired hemi-spherical coverage

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin