wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

30-8 Industrial Communication Systems
multitiered monitoring applications [28,29]. Tejero-Calado et al. provide an example of physiological
monitoring using IEEE 802.11 technology in [27]. Here, an IEEE 802.11b compliant module supporting
rates up to 11.Mbps collects real-time ECG data from an electronic subsystem (analog conditioning
plus digital sampling) and performs its transmission to a central server for storage (and analysis) using
a TCP/IP communication transport. The real-time ECG data fed to the server can be viewed on display
devices, such as PCs, laptops, PDAs, etc., as long as they can communicate with the server using the
TCP/IP transport.
The architecture of monitoring applications typically employs (at least) two tiers: one where data
are collected and the other where data are made available for professional analysis. In the first tier, the
vital sensors worn by patients are connected (through wires or wirelessly) to a local unit (mobile phone,
PDA, etc.) that displays signals and related information, performs basic signal processing, and transmits
data using the IEEE 802.11 technology. In the second tier, multiple local units transmit data to a
central server where it is stored, processed, and further analyzed looking for abnormalities. Examples
of monitoring applications supported on IEEE 802.11 enabled gateways are proposed by Karatzanis et
al. and Postolache et al. The former presents an acquisition and processing system, based on a wearable
textile-based ECG device connected to a PDA that collects heart rate (HR) and respiratory rate (RespR)
signals, which are then transmitted to a home gateway using IEEE 802.11 communications. The home
gateway produces the corresponding time series, packs, and sends them to a central repository where
a clinical decision support system can detect the onset of early decompensation episodes. The latter
introduces a portable biosignal measuring system based on a personal digital assistant (PDA) that collects,
stores, and analyzes data from the ECG, and the oxygen saturation (SpO2S) and skin temperature
sensors. Besides online spontaneous heart rate (HR), the PDA determines the heart rate variability
(R-R variation). The detection of a major event (deviation from a given set of parameters) results in the
transmission of the last 10.min of physiological data to the host laptop. This transmission is performed
using a TCP/IP transport protocol on top of IEEE 802.11b communications. The physiological data are
then further analyzed using advanced algorithms (e.g., the fast Fourier transform) in order to obtain an
accurate patient diagnosis.
30.4.6 Nonindustrial Technologies
The free industrial, scientific, and medical (ISM) bands are becoming crowded as a result of the
massive adoption of wireless communication technologies (e.g., Wi-Fi and Bluetooth). To cope with
the problem of interference in medical environments, the US Federal Communications Commission
(FCC) has allocated the 402–405.MHz range of frequencies to the medical implant communication
systems (MICS) band and the 608–614, 1395–1400, and 1427–1432.MHz frequency ranges to the
wireless medical telemetry service (WMTS) band [30]. These unlicensed bands can be used for both
short range (MICS) and moderate range (WMTS) communications without the risk of interference
from industrial wireless technologies. Furthermore, the MICS band is restricted to transmissions of
less than −16 dBm, which reduces the operational range to a few meters but increases the autonomy
of MICS-based communication devices. The WMTS band is usually employed in telemetry applications
requiring operational ranges of more than 100.m, as the band allows a maximum transmission
power of 1.5.W.
Examples of nonindustrial communication technologies are the wireless woven inductor channel
described in [31] and the BAN based on the MICS/WMTS proposed in [32]. The former is employed
in BANs and addresses the problem of ultra-low-power near-field communication while the latter
envisages multitiered vital signal monitoring systems based on MICS/WMTS communications for
healthcare environments.
The Wireless Woven Inductor allows a wearable sensor network to communicate with a gateway
device through several layers of clothes, i.e., it enables ultralow-power communication between sensors
in close contact with the patient’s body and a gateway without the inconvenience of having wires passing
© 2011 by Taylor and Francis Group, LLC