Biomedical Engineering Reference
In-Depth Information
1.1 Overview of Wireless Body Area Networks
With the recent advancement in wireless sensor networks and miniaturized hard-
ware technologies, it has been possible to implement wireless networks that operate
in and around human body. A WBAN is a networking concept that has evolved with
the idea of monitoring vital physiological signals from low power and miniaturized
in-body or on-body sensors. Data collected from these sensors are transferred to a
remote node via a wireless medium, where the data is forwarded to a higher layer
application to be interpreted.
WBAN communication can be divided into three major categories; commu-
nication between a node on body surface to an outside base station, communica-
tion between two nodes that are placed on body surface, and communication from
a node that is implanted in the body to an outside node. These three communi-
cation scenarios are named off-body communication, on-body communication and
in-body communication respectively [
3
]. The IEEE wireless body area network
standard (IEEE 804.15.6 TG6) [
4
] had been formed in order to develop and
standardize the Physical Layer (PHY) and Medium Access Control (MAC) pro-
tocols for short range, low power and highly reliable wireless communication
schemes to operate in, on and around the human body. The recent activities of this
standard can be found in [
5
]. The standard has identified eight operating scenarios
for WBAN.
• Implant to Implant.
• Implant to Body Surface.
• Implant to External.
• Body Surface to Body Surface (Line-of-Sight (LOS)).
• Body Surface to Body Surface (Non Line-of-Sight (NLOS)).
• Body Surface to External (LOS).
• Body Surface to External (NLOS).
A WBAN can be used for many applications, such as physiological signal
monitoring in health care environments, personnel entertainment applications and
industrial communication applications for monitoring worker health conditions in
safety critical environments. Hence a WBAN should be able to support a variety of
data rates from a few bps to several Mbps. With recent advancements in data
sensing technologies, the amount of data gathered by sensors has increased dra-
matically. This increases the demand for high data rate systems to transfer data.
For example a 128-channel neural recording system requires a real-time wireless
data transmission up to 10 Mbps [
6
]. Hence, a WBAN should be able to support
high data rate communication. Sensor nodes used in either implantable or wearable
WBAN applications are battery powered devices. Hence, power efficient operation
is a critical aspect of the devices involved in WBAN communication. Furthermore,
these implantable and wearable sensor nodes should have a small form factor.
Since WBAN sensor nodes operate at a close proximity to the human body, it
should operate within various regulations applied for Specific Absorption Rate
