Theodoros Mavridis

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.

UWB Interferometry TDOA Estimation for 60-GHz OFDM Communication Systems

A simple technique to estimate the time difference of arrival (TDOA) that necessitates only one reference device to perform 1-D positioning of a mobile device is presented. Using a multiple-input-single-output (MISO) system, this interferometric technique uses ultrawideband signals and is particularly well suited for 60-GHz orthogonal frequency-division multiplexing (OFDM) communications. The accuracy of the technique is assessed by simulation, using the IEEE 802.11ad channel, as well as by measurement.

Information Spatial Focusing Scheme for UWB Wireless Communications in Smart Environments

This letter presents an information spatial focusing method for future smart environments using ultrawideband (UWB) wireless communications. This method allows to send high-data-rate information at predetermined specific spatial positions without localizing users, thereby protecting their privacy. The proposed approach is a combination of simplified UWB beamforming and signal processing. Compared to classical UWB beamforming, the proposed method exhibits greater information focusing capabilities by increasing greatly the peak-to-floor ratio between main and side beams.

A 60 GHz Off-Body channel implementation

In the field of smart environments, high data rate wireless wireless communication can be reached with the unlicensed 60 GHz RF Band. In this spectrum, Body Area Networks channel modeling is required. In this paper, a 60 GHz Off-Body channel modeling is presented using a simplified and fast computation result of the scattering of plane waves by a human body at 60 GHz and the IEEE 802.11ad indoor channel model.

Millington Effect and Propagation Enhancement in 60-GHz Body Area Networks

Millington effect for on-body propagation enhancement is presented in the 60-GHz band. Millingtons equations are developed to describe propagation above a flat inhomogeneous surface. This study focuses on mixed paths (human skin-metallic) for on-body scenarios. It is shown that adding metallic paths on the human skin can improve the power link budget between two nodes placed on the body. Two different schemes are studied experimentally to assess the analytical model using a flat phantom with electric properties of human skin and different lengths of metallic inserts. The first scheme considers a metallic plate between the transmitting and receiving antennas, while the second scheme proposes locating the metallic plates under the antennas. It is shown that the second scheme yields a better link budget than the first one for the same length of metal. Moreover, a numerical study is performed to assess the impact of the following different parameters: the location of the metal plate, size of the plate, and the height of the antennas. Excellent agreement between numerical and experimental results has been shown. In the best cases, the presented techniques allow to improve the path loss of 10-20 dB.

Human influence on 60 GHz communication in close-to-user scenario

This paper presents a new human influence model for 60 GHz close-to-user communications. The model is based on both Geometrical Optics results and a modified creeping wave formulation. It is applied in an indoor environment and the mean attenuation of the channel with the human body presence is calculated. As expected, it is shown that the attenuation is highly affected by the user orientation with respect to the transmitter. In this paper, only a normally incident plane wave with TM polarization is studied.

60 GHz SIW horn antenna : Off-body performance comparison with 4 GHz UWB monopole antenna

A 6.6 dBi-gain Substrate Integrated Waveguide (SIW) horn antenna is used for off-body channel measurement at 60 GHz. Statistical scenario-based measurements are more suitable to assess Body Area Network (BAN) communication since they include both the environment and the antenna behaviors. Measurements are performed for four scenarios and two antenna positions. Results are discussed and compared with measurements at 4 GHz using a SkyCross monopole antenna in terms of link outage probability using receiver performance from the literature. In particular, it is shown that in all considered scenarios, results at 4 GHz and at 60 GHz led to outage of less than 15% and less than 8% respectively.