Wireless Networks manuscript No.
(will be inserted by the editor)
A Survey on Wireless Body Area Networks
Benoˆıt Latr´e · Bart Braem · Ingrid Moerman · Chris Blondia ·
Piet Demeester
Received: date / Accepted: date
Abstract The increasing use of wireless networks and
the constant miniaturization of electrical devices has
empowered the development of Wireless Body Area Net-
works (WBANs). In these networks various sensors are
attached on clothing or on the body or even implanted
under the skin. The wireless nature of the network and
the wide variety of sensors offer numerous new, practi-
cal and innovative applications to improve health care
and the Quality of Life. The sensors of a WBAN mea-
sure for example the heartbeat, the body temperature
or record a prolonged electrocardiogram. Using a WBAN,
the patient experiences a greater physical mobility and
is no longer compelled to stay in the hospital. This pa-
per offers a survey of the concept of Wireless Body Area
Networks. First, we focus on some applications with
special interest in patient monitoring. Then the com-
munication in a WBAN and its positioning between
the different technologies is discussed. An overview of
the current research on the physical layer, existing MAC
and network protocols is given. Further, cross layer and
quality of service is discussed. As WBANs are placed
on the human body and often transport private data,
security is also considered. An overview of current and
past projects is given. Finally, the open research issues
and challenges are pointed out.
Benoˆıt Latr´e, Ingrid Moerman, Piet Demeester
Department of Information Technology, Ghent University /
IBBT, Gaston Crommenlaan 8 box 201, B-9050 Gent, Belgium,
Tel.: +32-45-678910
Fax: +132-45-678910
E-mail: benoit.latre@intec.ugent.com
Bart Braem, Chris Blondia
Department of Mathematics and Computer Science, University
of Antwerp / IBBT,
Middelheimlaan 1, B-2020, Antwerp, Belgium
1 Introduction
The aging population in many developed countries and
the rising costs of health care have triggered the in-
troduction of novel technology-driven enhancements to
current health care practices. For example, recent ad-
vances in electronics have enabled the development of
small and intelligent (bio-) medical sensors which can
be worn on or implanted in the human body. These
sensors need to send their data to an external medical
server where it can be analyzed and stored. Using a
wired connection for this purpose turns out to be too
cumbersome and involves a high cost for deployment
and maintenance. However, the use of a wireless in-
terface enables an easier application and is more cost
efficient [1]. The patient experiences a greater physical
mobility and is no longer compelled to stay in a hospi-
tal. This process can be considered as the next step in
enhancing the personal health care and in coping with
the costs of the health care system. Where eHealth is
defined as the health care practice supported by elec-
tronic processes and communication, the health care
is now going a step further by becoming mobile. This
is referred to as mHealth [2]. In order to fully exploit
the benefits of wireless technologies in telemedicine and
mHealth, a new type of wireless network emerges: a
wireless on-body network or a Wireless Body Area Net-
work (WBAN). This term was first coined by Van Dam
et al. in 2001 [3] and received the interest of several
researchers [4–8].
A Wireless Body Area Network consists of small, in-
telligent devices attached on or implanted in the body
which are capable of establishing a wireless commu-
nication link. These devices provide continuous health
monitoring and real-time feedback to the user or med-
ical personnel. Furthermore, the measurements can be
2
recorded over a longer period of time, improving the
quality of the measured data [9].
Generally speaking, two types of devices can be dis-
tinguished: sensors and actuators. The sensors are used
to measure certain parameters of the human body, ei-
ther externally or internally. Examples include mea-
suring the heartbeat, body temperature or recording
a prolonged electrocardiogram (ECG). The actuators
(or actors) on the other hand take some specific ac-
tions according to the data they receive from the sensors
or through interaction with the user. E.g., an actuator
equipped with a built-in reservoir and pump adminis-
ters the correct dose of insulin to give to diabetics based
on the glucose level measurements. Interaction with the
user or other persons is usually handled by a personal
device, e.g. a PDA or a smart phone which acts as a
sink for data of the wireless devices.
In order to realize communication between these de-
vices, techniques from Wireless Sensor Networks (WSNs)
and ad hoc networks could be used. However, because
of the typical properties of a WBAN, current proto-
cols designed for these networks are not always well
suited to support a WBAN. The following illustrates
the differences between a Wireless Sensor Network and
a Wireless Body Area Network:
– The devices used have limited energy resources avail-
able as they have a very small form factor (often less
than 1 cm
3
[10]). Furthermore, for most devices it
is impossible to recharge or change the batteries al-
though a long lifetime of the device is wanted (up
to several years or even decades for implanted devi-
ces). Hence, the energy resources and consequently
the computational power and available memory of
such devices will be limited;
– All devices are equally important and devices are
only added when they are needed for an application
(i.e. no redundant devices are available);
– An extremely low transmit power per node is needed
to minimize interference and to cope with health
concerns [11];
– The propagation of the waves takes place in or on a
(very) lossy medium, the human body. As a result,
the waves are attenuated considerably before they
reach the receiver;
– The devices are located on the human body that can
be in motion. WBANs should therefore be robust
against frequent changes in the network topology;
– The data mostly consists of medical information.
Hence, high reliability and low delay is required;
– Stringent security mechanisms are required in order
to ensure the strictly private and confidential char-
acter of the medical data;
– And finally the devices are often very heterogeneous,
may have very different demands or may require
different resources of the network in terms of data
rates, power consumption and reliability.
When referring to a WBAN where each node com-
prises a biosensor or a medical device with sensing unit,
some researchers use the name Body Area Sensor Net-
work (BASN) or in short Body Sensor Network (BSN)
instead of WBAN [12]. These networks are very similar
to each other and share the same challenges and prop-
erties. In the following, we will use the term WBAN
which is also the one used by the IEEE [13].
In this article we present a survey of the state of
the art in Wireless Body Area Networks. Our aim is to
provide a better understanding of the current research
issues in this emerging field. The remainder of this pa-
per is organized as follows. First, the patient monitoring
application is discussed in Section 2. Next, the char-
acteristics of the communication and the positioning
of WBANs amongst other wireless technologies is dis-
cussed in Section 4. Section 5 gives an overview of the
properties of the physical layer and the issues of com-
municating near or in the body. Existing protocols for
the MAC-layer and network layer are discussed in Sec-
tion 6 and Section 7 respectively. Section 8 deals with
cross-layer protocols available for WBANs. The Quality
of Service and possible security mechanisms are treated
in Section 9 and 10. An overview of existing projects
is given in Section 11. Finally, the open research issues
are discussed in Section 12 and Section 13 concludes
the paper.
2 Patient Monitoring
The main cause of death in the world is CardioVascular
Disease (CVD), representing 30% of all global deaths.
According to the World Health Organization, world-
wide about 17.5 million people die of heart attacks or
strokes each year; in 2015, almost 20 million people will
die from CVD. These deaths can often be prevented
with proper health care [14]. Worldwide, more than 246
million people suffer from diabetes, a number that is
expected to rise to 380 million by 2025 [15]. Frequent
monitoring enables proper dosing and reduces the risk
of fainting and in later life blindness, loss of circulation
and other complications [15].
These two examples already illustrate the need for
continuous monitoring and the usefulness of WBANs.
Numerous other examples of diseases would benefit from
continuous or prolonged monitoring, such as hyperten-
sion, asthma, Alzheimer’s disease, Parkinson’s disease,
renal failure, post-operative monitoring, stress-monitoring,
3
prevention of sudden infant death syndrome etc [9,16,
17]. These applications can be considered as an indica-
tor for the size of the market for WBANs. The number
of people suffering from diabetics or CVD and the per-
centage of people in the population age 60 years and
older will grow in the future. Even without any further
increase in world population by 2025 this would mean a
very large number of potential customers. WBAN tech-
nology could provide the connectivity to support the
elderly in managing their daily life and medical condi-
tions [18]. A WBAN allows continuous monitoring of
the physiological parameters. Whether the patient is in
the hospital, at home or on the move, the patient will
no longer need to stay in bed, but will be able to move
around freely. Furthermore, the data obtained during a
large time interval in the patient’s natural environment
offers a clearer view to the doctors than data obtained
during short stays at the hospital [9].
An example of a medical WBAN used for patient
monitoring is shown in Figure 1. Several sensors are
placed in clothes, directly on the body or under the skin
of a person and measure the temperature, blood pres-
sure, heart rate, ECG, EEG, respiration rate, SpO
2
-
levels etc. Next to sensing devices, the patient has actu-
ators which act as drug delivery systems. The medicine
can be delivered on predetermined moments, triggered
by an external source (i.e. a doctor who analyzes the
data) or immediately when a sensor notices a problem.
One example is the monitoring of the glucose level in
the blood of diabetics. If the sensor monitors a sudden
drop of glucose, a signal can be sent to the actuator
in order to start the injection of insulin. Consequently,
the patient will experience fewer nuisances from his dis-
ease. Another example of an actuator is a spinal cord
stimulator implanted in the body for long-term pain
relief [19].
A WBAN can also be used to offer assistance to the
disabled. For example, a paraplegic can be equipped
with sensors determining the position of the legs or
with sensors attached to the nerves [20]. In addition,
actuators positioned on the legs can stimulate the mus-
cles. Interaction between the data from the sensors and
the actuators makes it possible to restore the ability to
move. Another example is aid for the visually impaired.
An artificial retina, consisting of a matrix of micro sen-
sors, can be implanted into the eye beneath the surface
of the retina. The artificial retina translates the elec-
trical impulses into neurological signals. The input can
be obtained locally from light sensitive sensors or by an
external camera mounted on a pair of glasses [21].
Another area of application can be found in the do-
main of public safety where the WBAN can be used by
firefighters, policemen or in a military environment [22].
EEG
Hearing Aid
Cochlear Implant
Motion sensor
Blood pump
ECG
Glucose
Artificial
Knee
Lactic Acid
Artificial
Knee
Positioning
Insulin
Injection
Pressure sensor
Blood oxygen
Personal device
Fig. 1 Example of patient monitoring in a Wireless Body Area
Network.
The WBAN monitors for example the level of toxics
in the air and warns the firefighters or soldiers if a
life threatening level is detected. The introduction of
a WBAN further enables to tune more effectively the
training schedules of professional athletes.
Next to purely medical applications, a WBAN can
include appliances such as an MP3-player, head-mounted
(computer) displays, a microphone, a camera, advanced
human-computer interfaces such as a neural interface
etc [20]. As such, the WBAN can also be used for gam-
ing purposes and in virtual reality.
This small overview already shows the myriad of
possibilities where WBANs are useful. The main char-
acteristic of all these applications is that WBANs im-
prove the user’s Quality of Life.
3 Taxonomy and Requirements
The applications described in the previous section in-
dicate that a WBAN consists of several heterogeneous
devices. In this section an overview of the different types
of devices used in a WBAN will be given. Further the re-
quirements and challenges are discussed. These include
the wide variability of data rates, the restricted energy
consumption, the need for quality of service and relia-
bility, ease-of-use by medical professionals and security
and privacy issues.
4
3.1 Types of Devices
(Wireless) Sensor node:
A device that responds to and gathers data on phys-
ical stimuli, processes the data if necessary and re-
ports this information wirelessly. It consists of sev-
eral components: sensor hardware, a power unit, a
processor, memory and a transmitter or transceiver [23].
(Wireless) Actuator node:
A device that acts according to data received from
the sensors or through interaction with the user.
The components of an actuator are similar to the
sensor’s: actuator hardware (e.g. hardware for medi-
cine administration, including a reservoir to hold the
medicine), a power unit, a processor, memory and
a receiver or transceiver.
(Wireless) Personal Device (PD):
A device that gathers all the information acquired
by the sensors and actuators and informs the user
(i.e. the patient, a nurse, a GP etc.) via an exter-
nal gateway, an actuator or a display/LEDS on the
device. The components are a power unit, a (large)
processor, memory and a transceiver. This device is
also called a Body Control Unit (BCU) [4], body-
gateway or a sink. In some implementations, a Per-
sonal Digital Assistant (PDA) or smart phone is
used.
Many different types of sensors and actuators are
used in a WBAN. The main use of all these devices is
to be found in the area of health applications. In the
following, the term nodes refers to both the sensor as
actuator nodes.
The number of nodes in a WBAN is limited by na-
ture of the network. It is expected that the number of
nodes will be in the range of 20–50 [6, 24].
3.2 Data Rates
Due to the strong heterogeneity of the applications,
data rates will vary strongly, ranging from simple data
at a few kbit/s to video streams of several Mbit/s. Data
can also be sent in bursts, which means that it is sent
at higher rate during the bursts.
The data rates for the different applications are given
in in Table 1 and are calculated by means of the sam-
pling rate, the range and the desired accuracy of the
measurements [25, 26]. Overall, it can be seen that the
application data rates are not high. However, if one has
a WBAN with several of these devices (i.e. a dozen mo-
tion sensors, ECG, EMG, glucose monitoring etc.) the
aggregated data rate easily reaches a few Mbps, which
Table 1 Examples of medical WBAN applications [21, 25–27]
Application Data Rate Bandwidth Accuracy
ECG (12 leads) 288 kbps 100-1000 Hz 12 bits
ECG (6 leads) 71 kbps 100-500 Hz 12 bits
EMG 320 kbps 0-10,000 Hz 16 bits
EEG (12 leads) 43.2 kbps 0-150 Hz 12 bits
Blood saturation 16 bps 0-1 Hz 8 bits
Glucose monitoring 1600 bps 0-50 Hz 16 bits
Temperature 120 bps 0-1 Hz 8 bits
Motion sensor 35 kbps 0-500 Hz 12 bits
Cochlear implant 100 kbps – –
Artificial retina 50-700 kbps – –
Audio 1 Mbps – –
Voice 50-100 kbps – –
is a higher than the raw bit rate of most existing low
power radios.
The reliability of the data transmission is provided
in terms of the necessary bit error rate (BER) which is
used as a measure for the number of lost packets. For a
medical device, the reliability depends on the data rate.
Low data rate devices can cope with a high BER (e.g.
10
−4
), while devices with a higher data rate require
a lower BER (e.g. 10
−10
). The required BER is also
dependent on the criticalness of the data.
3.3 Energy
Energy consumption can be divided into three domains:
sensing, (wireless) communication and data process-
ing [23]. The wireless communication is likely to be
the most power consuming. The power available in the
nodes is often restricted. The size of the battery used
to store the needed energy is in most cases the largest
contributor to the sensor device in terms of both di-
mensions and weight. Batteries are, as a consequence,
kept small and energy consumption of the devices needs
to be reduced. In some applications, a WBAN’s sensor-
/actuator node should operate while supporting a bat-
tery life time of months or even years without interven-
tion. For example, a pacemaker or a glucose monitor
would require a lifetime lasting more than 5 years. Es-
pecially for implanted devices, the lifetime is crucial.
The need for replacement or recharging induces a cost
and convenience penalty which is undesirable not only
for implanted devices, but also for larger ones.
The lifetime of a node for a given battery capacity
can be enhanced by scavenging energy during the op-
eration of the system. If the scavenged energy is larger
5
than the average consumed energy, such systems could
run eternally. However, energy scavenging will only de-
liver small amounts of energy [5, 28]. A combination
of lower energy consumption and energy scavenging is
the optimal solution for achieving autonomous Wireless
Body Area Networks. For a WBAN, energy scavenging
from on-body sources such as body heat and body vi-
bration seems very well suited. In the former, a thermo-
electric generator (TEG) is used to transform the tem-
perature difference between the environment and the
human body into electrical energy [27]. The latter uses
for example the human gait as energy source [29].
During communication the devices produce heat which
is absorbed by the surrounding tissue and increases the
temperature of the body. In order to limit this temper-
ature rise and in addition to save the battery resources,
the energy consumption should be restricted to a min-
imum. The amount of power absorbed by the tissue is
expressed by the specific absorption rate (SAR). Since
the device may be in close proximity to, or inside, a
human body, the localized SAR could be quite large.
The localized SAR into the body must be minimized
and needs to comply with international and local SAR
regulations. The regulation for transmitting near the
human body is similar to the one for mobile phones,
with strict transmit power requirements [11, 30]
3.4 Quality of Service and Reliability
Proper quality of service (QoS) handling is an impor-
tant part in the framework of risk management of med-
ical applications. A crucial issue is the reliability of the
transmission in order to guarantee that the monitored
data is received correctly by the health care profession-
als. The reliability can be considered either end-to-end
or on a per link base. Examples of reliability include
the guaranteed delivery of data (i.e. packet delivery ra-
tio), in-order-delivery, . . . Moreover, messages should
be delivered in reasonable time. The reliability of the
network directly affects the quality of patient monitor-
ing and in a worst case scenario it can be fatal when a
life threatening event has gone undetected [31].
3.5 Usability
In most cases, a WBAN will be set up in a hospital
by medical staff, not by ICT-engineers. Consequently,
the network should be capable of configuring and main-
taining itself automatically, i.e. self-organization an self-
maintenance should be supported. Whenever a node is
put on the body and turned on, it should be able to join
the network and set up routes without any external
intervention. The self-organizing aspect also includes
the problem of addressing the nodes. An address can
be configured at manufacturing time (e.g. the MAC-
address) or at setup time by the network itself. Fur-
ther, the network should be quickly reconfigurable, for
adding new services. When a route fails, a back up path
should be set up.
The devices may be scattered over and in the whole
body. The exact location of a device will depend on the
application, e.g. a heart sensor obviously must be placed
in the neighborhood of the heart, a temperature sen-
sor can be placed almost anywhere. Researchers seem
to disagree on the ideal body location for some sensor
nodes, i.e. motion sensors, as the interpretation of the
measured data is not always the same [32]. The net-
work should not be regarded as a static one. The body
may be in motion (e.g. walking, running, twisting etc.)
which induces channel fading and shadowing effects.
The nodes should have a small form factor consis-
tent with wearable and implanted applications. This
will make WBANs invisible and unobtrusive.
3.6 Security and Privacy
The communication of health related information be-
tween sensors in a WBAN and over the Internet to
servers is strictly private and confidential [33] and should
be encrypted to protect the patient’s privacy. The med-
ical staff collecting the data needs to be confident that
the data is not tampered with and indeed originates
from that patient. Further, it can not be expected that
an average person or the medical staff is capable of set-
ting up and managing authentication and authorization
processes. Moreover the network should be accessible
when the user is not capable of giving the password (e.g.
to guarantee accessibility by paramedics in trauma sit-
uations). Security and privacy protection mechanisms
use a significant part of the available energy and should
therefor be energy efficient and lightweight.
4 Positioning WBANs
The development and research in the domain of WBANs
is only at an early stage. As a consequence, the termi-
nology is not always clearly defined. In literature, pro-
tocols developed for WBANs can span from communi-
cation between the sensors on the body to communica-
tion from a body node to a data center connected to
the Internet. In order to have clear understanding, we
propose the following definitions: intra-body communi-
cation and extra-body communication. An example is
![Fig. 4 Characteristics of a Wireless Body Area Network compared with Wireless Sensor Networks (WSN) and Wireless Local Area Network (WLAN). Based on [44].](/figures/fig-4-characteristics-of-a-wireless-body-area-network-2wo6qzxj.webp)
![Table 1 Examples of medical WBAN applications [21,25–27]](/figures/table-1-examples-of-medical-wban-applications-2125-27-2c2jik4o.webp)