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e.g. in cellular data communications (Istepanian,
Philip & Martini, 2009).
WLAN is used in many Telemedicine systems
especially where there are communications among
mobile devices and also in presence of Internet
connection. The most sensitive multimedia traffic
is the Internet telephony (Voice-over-IP). For a
sufficient speech quality the mouth-to-ear delay
must be kept small and should be released of jitter
at the receiver (Wiethoelter & Hoene, 2003).The
traffic model and evaluation of traffic requirements
for wireless e-Health networks are presented in
(Zvikhachevskaya, Markarian & Mihaylova,
2009). In addition (Martinez, Salvador & Fer-
nandez, 2003), describes a methodology for the
technical evaluation of QoS traffic requirements
in healthcare services based on telemedicine,
which includes the service description, consider-
ing application requirements, network topologies
and the service evaluation implemented by an
automated tool.
Hu , et al. in (Hu & Kumar, 2003), have pro-
posed a mobile sensor network infrastructure
to support the third-generation telemedicine
applications, which uses an energy-efficient
query resolution mechanism in large-scale mobile
sensor networks and provides the guaranteed
mobile QoS for multimedia calls. Dudzik, et al.
in (Dudzik, Schoettner & Kassler, 1998), present
the architecture of the European Wireless ATM
Network Demonstrator (WAND) System, which
is evaluated in the medical environment. Such
mobile applications increase the quality and ef-
ficiency of treatment, but require high bandwidth
and low latency, which can be guaranteed by a
wireless ATM network (Vergados, Vergados &
Maglogiannis, 2006).
Further, the concept of handoff was introduced
in order to achieve the uninterrupted communica-
tion of an ongoing call. In cellular telecommu-
nications, the term handoff refers to the process
of transferring an ongoing call or data session
from one channel connected to the core network
to another. So, it is the process of changing the
channel (frequency, time slot, spreading code,
or a combination of them) associated with the
current connection, while a call is in progress
(Tripathi, 1998). Traditionally, handoff is always
implemented on the voice channels and constitutes
an essential part of the mobile communications
(Lee, 2005).
There are different types of handoff (Lee, 2005)
in digital systems:
Hard handoff (break-before-make process
and handoff between two frequencies),
Soft handoff (make-before-break pro-
cess). The process needs to secure two
code channels during the handoff process,
Softer handoff. Handoff occurring be-
tween sectors only at the serving cell. It is
a make-before break type using combined
diversity of two code channels.
There are two decision-making parameters
of handoff: that based on signal strength and
that based on carrier-to-interference ratio (Lee,
2005; Freeman, 2009; Rohdes and Schwarz
News, 2003; Makalainen, 2007; Gabriel, 2004).
The handoff process is one of the most complex
functions in a cellular network since it ensures the
continuity of connection and has a direct impact
on the QoS perceived by users as well as for the
mobility support (which is the important factor
of the QoS provisioned in telemedicine/e-Health
services). The handoff process is managed by the
so-called handoff schemes. Therefore, the level
of QoS of wireless mobile networks depends on
the handoff strategy. Several handoff schemes,
that support different services and different traf-
fic requirements, can be found in the literature
(Freeman, 2009; “Rohdes and Schwarz News”,
2003; Makalainen, 2007; Gabriel, 2004; Yi-Bing
& Mohan, 1994; Katzela & Naghshineh, 1996).
However, the implementation of handoff for non-
voice related services differs from the traditional
circuit-switch approach as the desired e-Health
services and applications will seemingly utilise
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