Sylvain Ranvier

Capacity enhancement by increasing both mutual coupling and efficiency: a novel approach

In this paper a method which increases both mutual coupling and efficiency is presented. It is based on hardware modification and applied to patch antenna arrays. It is seen that by increasing the mutual coupling, the channel capacity is increased significantly. In addition, this method removes, over a certain frequency band, the main drawback of mutual coupling: the losses at the ports level. The benefits of this method on the channel capacity are analyzed for 3 antenna structures. The channel capacity is calculated using a measurement based tool called MEBAT. The effects of this method are shown both by simulations and measurements.

VNA-based wideband 60 GHz MIMO channel sounder with 3-D arrays

This paper presents a wide band 60 GHz MIMO channel measurement system using a VNA and 3-D arrays at both ends. It uses virtual antenna arrays which can be reconfigured easily. The bandwidth of the system is 3.5 GHz, which leads to a time resolution of 0.29 ns. This fine resolution is suitable for characterizing dense multipaths in indoor environments. Line of sight (LOS) and obstructed line of sight (OLOS) measurements were performed with 64-element arrays at both TX and RX. Preliminary results (power delay profiles) are presented.

Low-Cost Planar Omnidirectional Antenna for mm-Wave Applications

This letter presents a planar omnidirectional antenna structure with wide beam for applications in the 60-GHz band. The antenna was designed using only one metal layer on top of a quartz substrate, which is very cost efficient. The optimal structure, of size 4.5 times 4.3 mm2, exhibits a gain of 1.4 dBi plusmn 0.5 dBi in the omnidirectional plane and a half power beam width of about 75 deg in the perpendicular plane. The bandwidth with return loss at least 10 dB covers the 57-64-GHz license-free band, which is commonly considered for very high data rate communications. The consistency of the simulated results was successfully checked with measurements.

Millimeter-Wave MIMO Radio Channel Sounder

Nowadays, the need for high-data-rate-communication channels is increasing and will ineluctably continue to increase in the future. From a theoretical point of view, the multiple input multiple output (MIMO) approach seems to be one of the best solutions to provide such a high capacity. This paper presents a millimeter-wave MIMO channel measurement system developed in the Radio Laboratory of Helsinki University of Technology. The system is based on a sounder and virtual antenna arrays: The antenna arrays are obtained by two 2-D scanners which shift a single transmit antenna and a single receive antenna. Measurements in line of sight (LOS) and non-LOS are reported from what the MIMO channel capacity is calculated for various antenna array sizes. Furthermore, from the same measurements, the direction of departure and direction of arrival are estimated

A microwave transmission-line network guiding electromagnetic fields through a dense array of metallic objects

Abstract We present measurements and simulations of a transmission-line network that has been designed for cloaking applications in the microwave region. Here the network is not used for cloaking but for channelling electromagnetic fields through an electrically dense array of metal objects, which alone is basically impenetrable to the impinging electromagnetic radiation. With the designed transmission-line network the waves emitted by a source placed in an air-filled waveguide are coupled into the network and guided through the array of metallic objects. Our goal is to illustrate the simple manufacturing, assembly, and the general feasibility of cloaking devices based on the transmission-line approach. Most importantly, we demonstrate both with measurements and with numerical simulations the excellent coupling of waves between the network and the surrounding medium.

Five-element inverted-F antenna array for MIMO communications and radio direction finding on mobile terminal

A five-element inverted-F antenna array on mobile terminal for both multiple input multiple output (MIMO) communications and radio direction finding (RDF) applications is presented. The multi-element antenna (MEA) system has been designed to be used in the frequency band of the future Long Term Evolution (LTE) system at 3400–3600 MHz and integrated along the edges of the upper ground plane of a clamshell type mobile terminal. Without using any specific multi-antenna isolation techniques, the antennas have been optimized to have acceptable mutual coupling and small envelope correlation in order to provide enhanced capacity with multiple input multiple output (MIMO) techniques. The ambiguities of the proposed design in RDF applications have also been investigated. A prototype has been fabricated and tested. Good agreement between numerical simulations and experimental results has validated the antenna concept.

Development of a 60 GHz MIMO Radio Channel Measurement System

Nowadays the need for high-data-rate-communication channels is increasing and will ineluctably continue to increase in the future. From a theoretical point of view, MIMO (multiple input multiple output) approach seems to be one of the best solutions to provide such a high capacity. This paper presents a mm-wave MIMO channel measurement system developed in the Radio Laboratory of Helsinki University of Technology. The system is based on virtual antenna arrays: the antenna arrays are obtained by two 2D scanners which shift a single transmit antenna and a single receive antenna. Measurements in LOS (line of sight) and NLOS (non line of sight) are reported, from what the MIMO channel capacity is calculated and the DOD (direction of departure) and DOA (direction of arrival) are estimated

Mm-wave MIMO systems for high data-rate mobile communications

In this paper, the performance of 60 GHz MIMO system is analyzed based on experimental data. The mutual information (MI) of the measured channel is compared to the MI of an iid MIMO Rayleigh channel. It is seen that the mean MI of the channels are quite close to each other. Then, the MI of the MIMO system is compared to the one of a MIMO system with antenna selection. It is found that, when considering switching networks with realistic losses, the performance decreases drastically and, in most cases, MIMO antenna selection leads to lower MI than traditional MIMO with the same number of RF chains. Finally, the achievable data-rate of a realistic 4×4 MIMO system is calculated, based on the experimental data. It is shown that with 500 MHz bandwidth such a system can provide multigigabit communications at distance up to 10m.

Measurement-Based Mutual Information Analysis of MIMO Antenna Selection in the 60-GHz Band

The mutual information (MI) of several multiple-input-multiple-output (MIMO) antenna selection configurations has been studied based on 60-GHz MIMO channel measurement data. Several array shapes with different numbers of available antennas have been considered. The effect of the switching network (either lossless or with realistic losses) as well as the influence of the selection criterion [either maximum signal-to-noise ratio (SNR) or optimum capacity criterion (OCC)] has been analyzed. It is found that in the best case (optimum capacity criterion and lossless switching network) antenna selection can increase the MI by up to 127% as compared to traditional MIMO systems. Nevertheless, with more reasonable conditions (maximum SNR criterion, realistic switching network) the MI decreases drastically, with a maximum improvement of only 11% as compared to traditional MIMO systems.

Integrated MM-Wave MIMO Antenna with Directional Diversity using MEMS Technology

This paper presents the design of a fully integrated antenna with directional diversity in the 60 GHz band using MEMS process on high resistivity silicon wafer. This active antenna designed for MIMO systems integrates switches and phase shifters.