![](bg8.png)
ms threshold indicated in (Zhen et al., 2008) as a
generic maximum latency for medical applications in
body area networks (BANs), showing the feasibility
of the protocols under study in the scenario. In partic-
ular, a constant delay is an important feature of a pro-
tocol to use for transmitting health related data. The
proposed PHY/MAC solution, even in the presence
of interference (more patients in the room), exhibits
a stable behaviour, hence guaranteeing the mandatory
reliability of the transmitted information that doctors
use for diagnosis. Clearly, further work is required
to evaluate not only the average delay but also the jit-
ter, to meet the requirements of some critical real-time
application.
6 CONCLUSIONS
This paper has investigated average throughput and
delay performance of contention-based MAC proto-
cols in a realistic medical ICT scenario when consid-
ering different applications used for health monitoring
as: ECG, EEG, heart rate, respiratory rate and tem-
perature of the body. The performance has been eval-
uated using the network simulator Opnet, after vali-
dation with theoretical analysis.
The scenario addresses a wireless sensor network
for vital signal monitoring, in which the physical layer
technology is IR-UWB, as defined in IEEE 802.15.4a
standard. The network architecture is the star topol-
ogy defined by the IEEE 802.15.4 standard. Given
that the study targets cheap sensors implementations,
the considered receiver scheme is the non-coherent
energy detector. The MAC protocols investigated are
S-Aloha and PSMA, whose performance has been ob-
tained by varying the number of nodes in the scenario.
The events of false alarm and miss detection in the
sensing of the preamble, and the possibility of the re-
ceiver capturing a packet subjected to collision are the
realistic effects that have been included in both anal-
ysis and simulations.
The results show good performance in terms of
throughput for both protocols, but for the delay,
PSMA performs better. In addition, the results en-
lighten the importance of accounting for realistic
PHY effects and accurate modelling of the applica-
tion. The study showed that the average delay is be-
low the indicative maximum latency of 125 ms and
that the capture improves the performances. Given
the lack of explicit reference delay for these kinds of
applications, we can conclude that in a realistic envi-
ronment the network architecture used and the MAC
protocols investigated satisfy the requirements for en-
abling the concept of wireless health monitoring.
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