MEDICINSKI GLASNIK

24
Medicinski Glasnik, Volumen 9, Number 1, February 2012
INTRODUCTION
Significant technological advances in recent years
have enabled the development of wireless
sensor networks (WSN) as a new technology
with wide application possibilities (1, 2). For the
development of WSN, the advances in the area of
microelectronics, wireless communications, micro-electro-mechanical
systems (MEMS) and the
sensing technology have been most significant.
Such advances have enabled the development of
the low-cost miniature intelligent sensor nodes,
which are capable of mutual wireless communication.
Sensor nodes can be equipped with different
sets of nodes, depending on the specific application.
Every sensor node is capable of sensing, data
processing and wireless communication with
neighbouring sensor nodes and/or other devices
(e.g. base station). Such sensor networks can be
seamlessly integrated in other network structures,
such as wireless personal-area (WPAN) or
wireless body-area networks (WBAN).
Wireless sensor networks have quickly become
a widely adopted technology and found many
possible applications (3). Medical applications
of the wireless sensor networks are one of the
most promising areas for their practical use (4,
5). There are many research efforts worldwide
that are focused on the development of the reliable,
flexible and inexpensive WBAN network
suitable for medical applications (6, 7). Research
efforts resulted in certain prototypes of wireless
networks specialized for medical applications (8,
9, 10, 11). Some of these prototypes could become
accepted and used in practice worldwide.
The authors analyze the current status of the research
of medical wireless sensor networks. This
paper surveys the current projects and prototypes
of this area. The authors also propose the general
system architecture for the realization of medical
sensor networks including the model for hardware
and software organization. Adherence to the
general widely accepted system architecture should
ensure the interoperability and interconnectivity
among different medical systems based on
wireless sensor networks (12, 13, 14). Finally, the
paper analyzes the future development directions
and possible benefits obtained by the implementation
of the advanced medical systems based on
sensor networks.
WIRELESS SENSOR NETWORKS
In the last decade, a new technology of wireless
sensor networks (WSN) has emerged and become
rapidly accepted and outspread worldwide.
The most important prerequisites for the WSN
development have been the advances in MEMS,
wireless communications, microelectronics, embedded
computing and sensing technology. These
technological advances led to the development of
the miniature multifunctional low-cost wireless
sensor node which is equipped with data processing,
storage, transceiver, power supply and sensing
unit. The architecture of the typical sensor
node is given in the Figure 1.
The data processing unit generally consists
of the CPU (Central Processing Unit) and the
associated storage unit. This unit coordinates all
tasks related to the sensing and inter-node collaboration
and communication. The transceiver
unit enables mutual wireless communication
between sensor nodes, such as the communication
between nodes and base station. The battery
is usually used as the power supply unit, although
in some cases it can be extended with some
energy scavenging unit (e.g. solar cells) or the
power generator. The sensor node can also be
extended with other optional application dependent
units, such as the location finding system.
The sensing unit usually consists of two main
components: sensors and analog to digital converters
(ADC).
The dispersed sensor nodes constitute the sensor
field and form the multihop infrastructureless
architecture. Each sensor node from the sensor
field is capable of collecting data and routing
them to the sink (base station). The data sink is
connected to the end user or to the task manager
node locally or remotely, via the Internet, GSM
or other global network. The typical architecture
of the sensor network is shown in Figure 2.
Figure 1. The architecture of the sensor node (Grgić K., 2011)