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an experimental setup can also provide insights, it
is costly, labor intensive and it usually takes much
longer time than simulations. For example, it takes a
large amount of effort to assemble and configure large
number of terminals to use a particular set of applica-
tions. Moreover, it is often a non-trivial task to mea-
sure QoS parameters, such as delays and throughput
from live terminals. Therefore, we study the perfor-
mance in selected scenarios through network simula-
tions and compare the results. We use OPNET Mod-
eler software to do the wireless network simulations.
In this article, we first give an overview of the
use case scenarios considered in IEEE P11073.1.1
standard - Guidelines for the Use of RF Technology
(IEEE Std P11073-00101/D04, 2008). We focus on
802.11 (Wi-Fi) technologies and its performance, and
therefore, we will cover in greater detail the use cases
which are expected to use WLAN technology and
stress the network. In section 2 we give a summary
of uses cases described in the IEEE P11073.1.1 stan-
dard. An overview of IEEE 802.11 technology and
different features which could provide capabilities to
differentiate medical traffic and provide the needed
QoS is also given in this section. In section 3 we
describe the simulation model and scenarios that we
used to study and compare the performance achieved
with different 802.11 protocol modes, the number of
devices and the simulated medical and non-medical
applications. In section 4 we present and discuss our
simulation results. Finally, we end the paper with
concluding remarks in section 5.
2 IEEE P11073.1.1 USE CASE
SCENARIOS
IEEE P11073 group has undertaken effort to develop
guidelines for the use of RF wireless technologies
for point-of-care medical devices and it will be avail-
able as IEEEP1073.1.1 document (IEEE Std P11073-
00101/D04, 2008). The goal of the document is to
provide better understanding among all stake hold-
ers, for example, hospitals, care givers and patients
by having common view of the wireless technologies.
A review of the available and emerging wireless tech-
nologies, their capabilities and limitations, the ways
to configure/specify each, the relevant medical de-
vices and applications for each technology, and costs
and drawbacks are covered in the document. More-
over, the document includes several generic models
of typical healthcare use cases which could be used
to analyze, evaluate, compare and optimize differ-
ent wireless technologies and modes, or parameters
within each, for the intended use cases.
2.1 Use Case Overview
The IEEE P11073.1.1 standard has outlined several
use case scenarios which highlight the data charac-
teristics and QoS needs of the medical applications,
the number and type of such and network configura-
tions in which they are expected to be served. The
standard lists nine use case scenarios and they are:
1) Personal (Home/Mobile) Monitoring; 2) Sub-acute
cases involving telemetry and basic vital signs moni-
toring for a single patient in a room; 3) and 4) Increas-
ing complexity compared with (2) and ambulatory pa-
tients; 5) Cardiac patient moving through three areas;
6) Critical burn patient tracked from MedEvac to ER
to ICU through recovery; 7) Rescue and MedEvac;
8) Ancillary; and 9) Maternity. The reader is referred
to Appendix A in (IEEE Std P11073-00101/D04,
2008) for more details of these scenarios.
In this article we focus on the wireless local
area networking (WLAN) technologies, that is, IEEE
802.11 wireless networking, and, therefore, would
present the use cases where this technology is ex-
pected to be used. Among the use cases given in
(IEEE Std P11073-00101/D04, 2008), the use case 4
stresses the network most and in this case it is ex-
pected that trends of performance achievable in dif-
ferent IEEE 802.11 modes of the operation would be
easily observed. Therefore, we describe the use case
4 in detail next.
In the use case 4 there are sixteen patients and
each patient has some medical devices connected to
it. A patient is outfitted with a ambulatory monitoring
device, PWD (patient worn device), which transmits
5 ECG vectors. In addition to ECG, episodic SpO
2
and blood pressure measurements are transmitted rel-
atively infrequently; 1 and 15 min intervals, respec-
tively. There are wrist RFID (radio frequency identifi-
cation) tags, Nurse PDA, laptop PCs and VoIP (voice-
over-IP) phones expected to operate in the scenario
as well. Since, we consider IEEE 802.11 networks
only; we exclude RFID and other technologies using
non WLAN networking from the scenarios we have
simulated. The QoS requirement for PWD is max-
imum latency of less than 500 ms and for VoIP the
max latency should be less than 100 ms. Our objec-
tive in the simulation runs is to estimate the expected
performance and QoS when WLAN is operating in
the offered load environment. Since, applications like
episodic SpO
2
and blood pressure measurements have
very low throughput requirements, we do not include
these in our simulation; doing so, does not affect the
general observations we make about the performance
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