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sage) to be reliably detected (actuated) within a
certain time period. The simulation results clearly
show the benefits of adopting a cooperative strat-
egy in healthcare applications highlighting how
it could enhance the QoS of future emerging E-
Healthcare systems.
related also to the two above performance
indices.
Energy consumption. To permit the net-
work to work under specified performance
requirements for a sufficient time, de-
noted as the network lifetime, the nodes
must be capable of playing their role for
a sufficiently long period using the energy
provided by their battery. Consequently,
energy efficiency is one of the main re-
quirements of a WBAN.
BACKGROUND AND
RELATED WORK
Depending on the type of target application, QoS
in WBANs can be characterized by, among other
factors, reliability, energy efficiency, timeliness,
robustness, availability, and security. Some QoS
parameters may be used to measure the degree of
satisfaction with these services, such as through-
put, delay, jitter, and packet loss rate. Among the
different performance indices measuring the level
of QoS guaranteed in a WBAN, the following are
particularly significant:
Jitter generally refers to variations in de-
lay, although there are many other defini-
tions. It is often caused by the difference in
queueing delays experienced by consecu-
tive packets.
Packet loss rate is the percentage of data
packets that are lost during the process of
transmission. It can be used to represent
the probability of packets being lost. A
packet may be lost due to e.g. congestion,
bit error, or bad connectivity. This param-
eter is closely related to the reliability of
the network.
Throughput is the effective amount of
data transmitted in a specific unit of time.
Sensors requiring high throughput include
those nodes that generate high-speed data
streams, such as a camera sensor. In health-
care monitoring, to provide a better obser-
vation of a patient's health condition, a
sensor can transmit data at a high reporting
frequency and then use a high data rate to
send out the large amount of data sensed.
Scalability. This is the ability of a WBAN
to guarantee acceptable performance (i.e. a
reliability > 80%) with the increasing num-
ber of patient sensors. It indicates if the
WBAN will be suitable for a large nursing
system.
Mobility. This is the ability of a WBAN to
guarantee acceptable performance when
patients are mobile.
Delay is the time elapsing from the de-
parture of a data packet from the source
node to its arrival at the destination node,
including queueing delay, switching delay
and propagation delay, etc. Delay sensitive
applications are common in healthcare en-
vironments requiring WBANs to deliver
the data packets in real-time in order to
fulfill specific timing requirements.
Several variants of the AODV (Ad Hoc Dis-
tance Vector) have been proposed in the literature
to improve the QoS in WSANs and eventually in
WBANs. In (Zhu, (2002)) a QoS routing protocol
is presented that establishes routes with a reserved
bandwidth. In (Gerasimov, (2002)) a protocol is in-
troduced in order to perform path searching simul-
taneously with time slot scheduling TDMA (Time
Division Multiple Access). In (Zhang, (2005)),
in addition to the bandwidth, the packet delivery
Reliability is the packet reception ratio
(the number of ''received'' packets divided
by the number of ''transmitted'' packets),
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