Download 1 - Cyber-Physical Systems Integration Group @ DGIST

A Survey and Outlook
Sunghwa Son
Wireless Body Area Network
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WBAN
Wireless Personal Area Network (WPAN)
-> Body Area Network (BAN)
-> WBAN
WBAN is a RF-based wireless networking
technology that interconnects tiny nodes with
sensor or actuator capabilities in, on, or around
a human body
WBANs provide ubiquitous networking
functionalities for applications varying from
healthcare to safeguarding of uniformed
personnel
Wireless Body Area Network
• Typically, it covers a short range of about 2m
• It can be connected to local and wide area networks
• Human-computer interaction (HCI) is booming
WBAN characteristics
• Architecture: consists of two categories of
nodes: sensors/actuators and router nodes
• Density: nodes are not deployed with high
redundancy, and thus do not require high
node density
• Data rate: WBANs are employed for
monitoring human physiological activities.
Thus, the application data streams exhibit
relatively stable rates
WBAN characteristics
• Latency: for both healthcare and
consumer applications, latency resulting
from the underlying network such as a
WBAN should be minimized
• Mobility: WBAN nodes affiliated with the
same wearer move together and in the
same direction
Application of WBANs
WBANs for healthcare
WBANs for HCI
CodeBlue project
• Harvard University
• It considers a hospital environment
where multiple router nodes can be
deployed on the wall
-> all nodes use ZigBee radio
• System is limited to 40 kb/s aggregate
bandwidth per receiver because of
mobility and multihop
Advanced Health and Disaster Aid
Network (AID-N)
• It is developed at Johns Hopkins
University based on the CodeBlue
architecture
• GPS is employed for outdoor localization
and MoteTrack for indoors
• Patients have mobility constraints
- lack of routers in the network
• Limited number of sensor nodes
- limited bandwidth
Wearable Health Monitoring
Systems (WHMS)
• It is developed at the University of
Alabama and targets a larger-scale
telemedicine system
• WHMS has a star-topology network
• Power consumption and cost associated
with long-term data uploading can
hamper system realization
Application of WBANs
WBANs for healthcare
WBANs for HCI
Intra-Body Communications (IBC)
• Traditional computer interfaces are all
replaceable by potential WBAN devices
• It can be used to assist handicapped
people -> blind person and deaf person
MITHrill
• It is a wearable computing platform that
includes electrocardiography (ECG), skin
temperature, and galvanic skin response
sensors for wearable sensing and
context-aware interaction -> not a real
WBAN
• MITHrill 2003 -> using Wi-Fi
Microsystems Platform for Mobile
Services and Applications (MIMOSA)
• Its approach is similar to WHMS while it
exclusively employs a mobile phone as
the user-carried interface device
• Bluetooth Low Energy and RFID are used
for connecting local sensor nodes
• NanoIP, and Simple Sensor Interface (SSI)
protocols are integrated into MIMOSA
Wireless Sensor Node for a Motion Capture
System with Accelerometers (WiMoCA)
• It is concerned with the design and
implementation of a distributed gesture
recognition system
• It uses star topology and coordinator in
turn relays the data to an external
processing unit using Bluetooth
Sensor devices
• Sensors are key components of a WBAN
role: bridge the physical world and
electronic systems
• Previous -> low sampling frequency and
low data transmission rate would be
sufficient
• Today -> for better monitor human, a
wide range of commercially available
sensors can be deployed
• With advances in micro-electromechanical systems (MEMS),
sensor devices are getting even tinier in size and changing the
traditional way of measuring human physiological parameters
Radio Technologies
Radio Propagation
Blutooth Low Energy Technology
UWB
BluTooth 3.0 + High speed
ZigBee
• Researchers have made considerable
progress in characterizing the body area
propagation environment through both
measurement-based and simulation-based
• Theses works have been conducted in both
the industrial, scientific, and medical (ISM)
bands and the ultra-sideband (UWB)
• In each of the frequency bands, intra-body,
on-body, and off-body channels have been
studied
Significant progress been made toward
• Identification of the propagation mechanisms
that affect signal transmissions between nodes
• Assessment of the effects of multipath
reflections from the external environment to
signal transmissions between nodes
• Characterization of the fading statistics on body
links that occur with body motion and change of
body position in both sparse and rich scattering
environment
• Development of standard UWB channel impulse
response models and evaluation of typical
modulation schemes utilizing them
• With advances in very large-scale integration (VLSI), dual and
multiple-standard radios can be integrated into a single chip,
greatly reducing the cost and power consumption
Radio Technologies
Radio Propagation
Blutooth Low Energy Technology
UWB
BluTooth 3.0 + High speed
ZigBee
Bluetooth Low End Extension (LEE)
• It was introduced in 2004 by Nokia
• It was designed to wirelessly connect small
devices to mobile terminals
• LEE was released to the public with the name
Wibree in 2006
• Its products can be categorized into two groups
- dual-mode chips: equipped with
sensors/actuators
- standalone chips: equipped with a personal
server
• It will likely operate using a simpler protocol
stack and focus on short-range star-configured
networks
Radio Technologies
Radio Propagation
Blutooth Low Energy Technology
UWB
BluTooth 3.0 + High speed
ZigBee
UWB
• According to the Federal
Communications Commission (FCC),
UWB refers to any radio technology
• FCC also regulates license-free use of
UWB in the 3.1-10.6 GHz band
• The suitability of UWB applications in
short-range and indoor environments
UWB
• UWB is also an ideal technology for
precise localization
• IEEE 802.15.6-Body Area Networks (BANs)
will likely employ UWB
• However, when this standard and any
electronics that utilize it will become
available remains unknown
Radio Technologies
Radio Propagation
Blutooth Low Energy Technology
UWB
BluTooth 3.0 + High speed
ZigBee
BluTooth 3.0 + High speed
• BluTooth 3.0 + High speed introduces
the 802.11 protocol adaptation layer (PAL)
into the protocol stack, and increases
data rate support from 3 Mb/s to 24
Mb/s
• Limitations of Bluetooth include the
small number of active slaves (seven)
that each piconet supports and indirect
communications between slaves
Radio Technologies
Radio Propagation
Blutooth Low Energy Technology
UWB
BluTooth 3.0 + High speed
ZigBee
ZigBee/IEEE 802.15.4
• It targets low-data-rate and low-powerconsumption applications
• It can provide a flexible framework and it
better suits WBAN deployment scenarios
in a limited area
• Compared to Bluetooth and UWB, it can
operate in three ISM bands, with data
rates from 20 kb/s to 250 kb/s
ZigBee/IEEE 802.15.4
• ZigBee supports three types of topologies
-> star, cluster tree, and mesh
• The major advantage of ZigBee is its
capability of providing multihop routing
in a cluster three or mesh topology
-> WBAN network coverage can be
expanded to a WPAN using the same
radio
ZigBee/IEEE 802.15.4
• ZigBee mesh network
- full-function devices (FFDs)
- reduced-function devices (RFDs)
• They think ZigBee may have a better
chance to be adopted in the area of
home automation and industrial
automation and control
Connecting WBANs and the
world
• A global trend for interconnection of data
networks is to use IP
• WBAN packets can be translated into IP
datagrams by a gateway at the edge of a
WBAN
• The ubiquitous access and connectivity of
WBANs into the global network requires
• - network infrastructure support, lowpower and low-footprint software
implementations for routing, flow/error
control, remote procedure calls, database
management, and user interface
Open research issues
&
Conclusion
Open research issues
• Physical characteristics of sensor/actuator
materials and electronic circuits
• Development and evaluation of improved
propagation and channel models
• Networking and resource management
schemes
• Security, authentication, and privacy issues
• Power supply issues
• Rules of engagement
Conclusion
• WBAN plays a very important role in
ubiquitous healthcare applications and
enjoys a huge potential market in the
area of consumer electronics
• While WBAN technologies provide a
promising platform to enable ubiquitous
communications, several open issues still
need to be addressed