Julien Sarrazin

Theoretical and Experimental Investigation of a 60-GHz Off-Body Propagation Model

A fast computation and accurate analytical model for off-body propagation is derived in this paper. The paper discusses the off-body model propagation from an external source to a receiver located on the body. The model is developed for normal incident plane wave by describing the human body with a circular cylinder. We show that the total received electric field around the human body can be written as a creeping wave in the shadow region and as a geometrical optics result for the lit region. It is also shown that at 60 GHz, the shadow boundary width is negligible. The model shows perfect agreement with the experimental results conducted on a perfectly conducting cylinder. Measurements of the creeping wave path gain have been also conducted on a real body to assess the validity of the cylinder assumption. The results have shown a path gain of about 5 dB/cm for the TM case and 3 dB/cm for the TE case. The standard deviation between the measurements and the cylindrical model is about 3.5 dB for both TM and TE cases.

Analytical Creeping Wave Model and Measurements for 60 GHz Body Area Networks

The propagation of 60 GHz electromagnetic waves around a human body is studied analytically and experimentally. The body is treated here as a circular lossy cylinder, which is an approximation of the human torso. Analytical formulations based on creeping wave theory are given and discussed for both vertical and horizontal polarizations. An exact path gain expression is derived from analytical formulations and a simpler first order approximation is given. Path gain coefficients are shown for frequencies spanning the world available 60 GHz unlicensed band and for several sizes of the torso. Finally, the results of an experimental campaign conducted in an anechoic chamber to isolate the contribution of on-body propagation are reported. The measurement of the distance dependence of the received power on a brass cylinder and on a human body for both vertical and horizontal polarizations confirmed theoretical predictions.

Statistical On-Body Measurement Results at 60 GHz

This communication studies the path loss and shadowing between two body mounted devices at 60 GHz. The temporal fading is experimentally investigated and the Doppler spectrum is characterized and modeled. Measurements have been conducted in an anechoic chamber for both horizontal and vertical polarizations.

Creeping Wave Model of Diffraction of an Obliquely Incident Plane Wave by a Circular Cylinder at 60 GHz

This paper presents a creeping wave model for the diffraction of an obliquely incident plane wave by a perfectly conducting or lossy circular cylinder at 60 GHz. The model developed for both TM and TE polarizations is valid for electrically large cylinders and for a receiver in the close vicinity of the surface. An experimental validation is conducted on a perfectly conducting cylinder.

A New Multi-Sensor Fusion Scheme to Improve the Accuracy of Knee Flexion Kinematics for Functional Rehabilitation Movements

Exergames have been proposed as a potential tool to improve the current practice of musculoskeletal rehabilitation. Inertial or optical motion capture sensors are commonly used to track the subject’s movements. However, the use of these motion capture tools suffers from the lack of accuracy in estimating joint angles, which could lead to wrong data interpretation. In this study, we proposed a real time quaternion-based fusion scheme, based on the extended Kalman filter, between inertial and visual motion capture sensors, to improve the estimation accuracy of joint angles. The fusion outcome was compared to angles measured using a goniometer. The fusion output shows a better estimation, when compared to inertial measurement units and Kinect outputs. We noted a smaller error (3.96°) compared to the one obtained using inertial sensors (5.04°). The proposed multi-sensor fusion system is therefore accurate enough to be applied, in future works, to our serious game for musculoskeletal rehabilitation.

On the bandwidth enhancement of a multipolarization and reconfigurable pattern antenna for adaptive MIMO systems

A multipolarization cubic antenna concept which introduces pattern diversity for adaptive MIMO systems has been presented. The frequency bandwidth has been improved keeping radiation characteristics constant over the whole band.

Four co-located antennas for MIMO systems with a low mutual coupling using mode confinement

Multiple input multiple output (MIMO) systems can drastically improve wireless communication capacity and robustness by exploiting multipath effects. Performances of these multiple antenna systems largely depend on the correlation between received signals. To maximize the capacity, the correlation must be as low as possible. Spatial diversity is usually used to decrease this correlation. The antenna system presented in this paper is composed of four co-located antennas which are able to produce uncorrelated signals by using both magnitude and polarization diversities. Furthermore, the structure is planar and contains a ground plane which is well-suited to be integrated in a communicant terminal. The diversity potential of the structure is quantify by calculating the envelope correlation between each radiation pattern. The coupling between each access has been decreased by using vias for confinement modes.

Enhanced Broadside Gain of an Ultrawideband Diamond Dipole Antenna Using a Hybrid Reflector

This communication studies the effect of a hybrid reflector on the radiation pattern of an ultrawideband diamond dipole antenna. The cause of a split radiation pattern in the broadside direction appearing when using a uniform artificial-magnetic-conductor-based reflector is investigated and is found to be due to destructive interference in the broadside direction produced by surface currents localized in certain areas of the reflector. A hybrid reflector is then proposed to mitigate this problem using both electrical and magnetic conductors. This solution enhances the gain in the broadside direction of the ultrawideband antenna. A complete antenna with a feeding system and a hybrid reflector has been fabricated and the measurement results are presented.

Performance Assessment of IR-UWB Body Area Network (BAN) Based on IEEE 802.15.6 Standard

Performance of impulse radio-based ultrawideband (IR-UWB) communications in wireless body area networks is investigated using the dedicated IEEE 802.15.6 standard. An IR-UWB transceiver system is implemented for both on-off keying and differential binary phase-shift keying modulations. Bit error rates are determined from measurements for different on-body links with different data rates. It is shown that using a 25-dB-gain low noise amplifier (LNA) at the receiver, reaching an uncoded bit error rate BER of 10-3 was not possible for some links operating at higher data rates. Power and energy consumption issues are then addressed, and results in terms of required pJ/bit to achieve a certain quality of communication are given and discussed.

TDOA estimation method using 60 GHz OFDM spectrum

In the field of high data rate wireless communications, localization issues play a key role in achieving energy-efficient communication and geographic routing. time-difference of arrival (TDOA)-based localization methods present numerous advantages. In this paper, a new method of TDOA estimation is proposed. With this method, unlike conventional TDOA measurements, it is possible to perform communication and localization at the same time by using a multi-input single-output system. By transmitting ultra-wide-band orthogonal frequency-division multiplexing signals using spatial diversity, it is possible to extract TDOA from interference patterns in spectral domain. In addition, increasing the precision of localization is also studied using a multi-band approach. This whole study is made within the framework of the WiGig alliance specifications; however, it is compatible with other standards.