Raffaele D'Errico

Ultrawide Bandwidth RFID: The Next Generation?

Future advanced radio-frequency identification (RFID) systems are expected to provide both identification and high-definition localization of objects with improved reliability and security while maintaining low power consumption and cost. Ultrawide bandwidth (UWB) technology is a promising solution for next generation RFID systems to overcome most of the limitations of the current narrow bandwidth RFID technology such as: reduced area coverage, insufficient ranging resolution for accurate localization, sensitivity to interference, and scarce multiple-access capability. In this paper, a survey of current progress in the application of the UWB technology for RFID systems is presented with particular attention to low-complexity solutions for high-definition tag localization.

Time-variant BAN channel characterization

In this paper we present a time-variant on-body channel measurement campaign at 2.45 GHz and in the 3–5GHz band. Measurements were performed in an anechoic chamber and an indoor scenario. Three different human body movements for seven human subjects were considered to assess the influence of human activity on the channel behavior. To this aim, an analysis on mean channel gain, slow fading and shadowing correlation is presented with emphasis on the differences given by the human body variability and the movement condition.

Evaluating a TDMA MAC for body area networks using a space-time dependent channel model

Wireless communications for body area network (BAN) applications require an adaptable, dynamic and flexible medium access control (MAC) to cope with a variety of application requirements. The proposed MAC adjusts its communication protocols and the parameters of the IEEE 802.15.4 superframe. It is based on to achieve low power consumption and low latency which are among the key requirements in BAN applications. In this paper, accordingly with measurements made in an anechoic chamber, we first define a BAN channel model useable in network simulations embedding a spatial and temporal dependency using ray tracing techniques. It is applied to the body postures and movements of a walking person. As body posture highly affects the performance of the MAC protocol, we second evaluate the effects of the varying body shadowing in the walking scenario on our MAC protocol performances.

Passive Ultrawide Bandwidth RFID

Ultrawide bandwidth (UWB) technology is a promising solution for next generation radiofrequency identification (RFID) systems to overcome most of the main limitations of current RFID systems such as very short operating range, insufficient ranging resolution for accurate localization, sensitivity to interference and scarce multiple access capability. In this paper, the UWB technology is applied to (semi-)passive RFID based on backscatter modulation and the potential performance is investigated in terms of range/data rate trade-off and clutter effect mitigation using experimental data.

A review of radio channel models for body centric communications

The human body is an extremely challenging environment for the operation of wireless communications systems, not least because of the complex antenna-body electromagnetic interaction effects which can occur. This is further compounded by the impact of movement and the propagation characteristics of the local environment which all have an effect upon body centric communications channels. As the successful design of body area networks (BANs) and other types of body centric system is inextricably linked to a thorough understanding of these factors, the aim of this paper is to conduct a survey of the current state of the art in relation to propagation and channel models primarily for BANs but also considering other types of body centric communications. We initially discuss some of the standardization efforts performed by the Institute of Electrical and Electronics Engineers 802.15.6 task group before focusing on the two most popular types of technologies currently being considered for BANs, namely narrowband and Ultrawideband (UWB) communications. For narrowband communications the applicability of a generic path loss model is contended, before presenting some of the scenario specific models which have proven successful. The impacts of human body shadowing and small-scale fading are also presented alongside some of the most recent research into the Doppler and time dependencies of BANs. For UWB BAN communications, we again consider the path loss as well as empirical tap delay line models developed from a number of extensive channel measurement campaigns conducted by research institutions around the world. Ongoing efforts within collaborative projects such as Committee on Science and Technology Action IC1004 are also described. Finally, recent years have also seen significant developments in other areas of body centric communications such as off-body and body-to-body communications. We highlight some of the newest relevant research in these areas as well as discussing some of the advanced topics which are currently being addressed in the field of body centric communications.

Opportunistic relaying protocols for human monitoring in BAN

Body Area Networks (BAN) offer amazing perspectives to instrument and support humans in many aspects of their life. Among all possible applications, this paper focuses on body monitoring applications having a body equipped with a set of sensors transmitting in real-time their measures to a common sink. The underlying network topology is a star topology which is quite usual in the broad scope of wireless sensor networks. Therefore, a classical superframe structure as proposed in 802.15.3 or 802.15.4 seems to comply with the needs of such an application. Basically however, the specificities of the BAN channel can reduce the performance of such protocol. Indeed, channel time variations make the star structure unstable and temporary subject to a high packet error rate. A multi-hop mesh topology cannot counteract this problem efficiently, since the pathloss attenuation in a BAN environment is almost independent with the emitter-receiver distance. In this paper, we address this issue by considering the topology of a BAN network as a time-varying fully connected network instead of a star structure. We then show how an opportunistic cooperative mechanism based on a decode-and-forward protocol can address this issue. We derive a performance criterion based on a packet error rate outage and we discuss the implementation of this scheme in the classical superframe structure.

An UWB-UHF semi-passive RFID System for localization and tracking applications

We present a novel radio-frequency identification (RFID) system with capability of localization and tracking of passive or semi-passive tags. Localization and tracking features are enabled by backscatter modulation on ultra-wide bandwidth tags antenna. A ultra-high frequency signal allows the wake-up of the tags enabling the reduction of energy consumption and ensuring compatibility with existing RFID systems. The overall system as well as the reader and tag architectures are introduced. The localization and tracking performance evaluation is presented in some reference scenarios.

Body-to-Body communications: A measurement-based channel model at 2.45 GHz

This paper presents a channel characterisation for Body-to-Body communications. Starting from indoor real-time measurements at 2.45 GHz, the radio channel was modeled, both in Line-of-Sight (LOS) and Non Line-of-Sight (NLOS) conditions, through a mean channel gain component plus a fading contribution, the latter arising from the body movements. The body shadowing effect was also evaluated considering the orientation of one human body with respect to another one. Two different antennas were employed in the measurements, to assess their impact on the radio channel characteristics.

Body-to-Body Indoor Channel Modeling at 2.45 GHz

This paper presents an indoor Body-to-Body narrowband channel model based on experimental data, acquired through a real-time dynamic measurement campaign at 2.45 GHz. The radio channel was investigated under different communication conditions, according to the movement performed by some human subjects and to their mutual position. Several node locations were considered, and two antenna types were used to assess the impact of their radiation characteristics on channel properties. For each investigated link, the channel power transfer function was modeled as composed by a channel gain and a small-scale fading contribution, the latter arising from the multipaths due to the environment and the humans motion. The shadowing effect of the body was also evaluated considering that the body itself can act as an obstacle to the communication, according to its spatial orientation. Every model component was characterized for each scenario, highlighting how a specific movement results in different effects on channel dynamic properties.

Antenna design and channel modeling in the BAN context - part II: channel

The first results achieved in the French ANR (National Research Agency) project BANET (Body Area NEtwork and Technologies) concerning the channel characterization and modeling aspects of Body Area Networks (BANs) are presented (part II). A scenario-based approach is used to determine the BAN statistical behavior, trends, and eventually models, from numerous measurement campaigns. Measurement setups are carefully described in the UWB context. The numerous sources of variability of the channel are addressed. A particular focus is put on the time-variant channel, showing notably that it is the main cause of the slow fading variance. Issues related to the data processing and the measurement uncertainties are also described.