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Minimizing Channel Access Delay for
Emergency Traffic in
IEEE 802.15.6Wireless Body Area
Network (WBAN)
Mohammad Ariful Huq
Supervisor : Eryk Dutkiewicz
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Outlines
• Introduction
• Necessity of MAC Protocol for WBAN
• IEEE 802.15.4, IEEE 802.15.6 , MEB MAC
• Channel Access Delay Minimization for Emergency Traffic
• Simulation Results
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Outlines
• Introduction
• Necessity of MAC Protocol for WBAN
• IEEE 802.15.4, IEEE 802.15.6 , MEB MAC.
• Channel Access Delay Minimization for Emergency Traffic
• Simulation Results
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Wireless Network
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Introduction
•
WBAN is RF based wireless networking technology that interconnects tiny
nodes with sensors in, on, or around a human body.
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A typical WBAN consists of a
number of inexpensive, lightweight,
miniature sensor platforms, each
featuring one or more
physiological sensors like
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Motion Sensors
ECG (Electrocardiograms)
Sp02
Breathing Sensors
Blood pressure
EMG (Electromyograms)
EEG(Electro-encephalograms)
Blood Glucose Sensors
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Introduction
• Network size of WBAN
– Application dependent
( up to 256 devices)
• WBAN Sensors could be located on
– The body as intelligent patches
– Integrated into clothing
– Implanted below the skin
– Embedded deeply in tissues
Figure: Positioning of a Wireless Body Area Network
in the realm of wireless networks.
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SENSING ACTIVITIES IN MEDICAL BANS
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WBAN Traffic Classification
• – Normal traffic: Based on normal operation between device and
coordinator.
• – On-demand traffic: Initiated by Coordinator to know certain
information.
• – Emergency traffic: In case of critical condition.
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WBAN Architecture
 Level 1 contains in-body and on-body BAN Nodes (BNs)
 Level 2 contains a BAN Network Coordinator (BNC) that gathers patient’s vital information
from the BNs and communicates with the base-station.
 Level 3 contains a number of remote base-stations that keep patient’s medical/nonmedical records and provides relevant (diagnostic) recommendations.
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WBAN Applications
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CodeBlue
CodeBlue is the project of Harvard University trying to develop novel applications of wireless sensor network technology to
medical applications. Many products of the project have great potential to apply to practice.
Figure 6:Intel SHIMMER motes
Stroke patient rehabilitation monitoring system [CodeBlue].
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Mercury: A Wearable Sensor Network
Platform for High-Fidelity Motion Analysis
The Intel SHIMMER mote, including a
triaxial accelerometer
The SHIMMER mote connected
to its programming board.
SHIMMER sensors being worn
on a patient's arm.
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VitalDust: Wireless vital sign monitoring
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Mica2-based pulse oximeter
Measures heart rate, blood oxygen saturation
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Telos-based two-lead Electrocardiogram
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PDA- and PC-based applications for multi-patient triage
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Outlines
• Introduction
• Necessity of MAC Protocol for WBAN
• IEEE 802.15.4, IEEE 802.15.6 , MEB MAC.
• Channel Access Delay Minimization for Emergency Traffic
• Simulation Results
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Major Sources of Energy Waste in Sensor
Network
1. Collision : Two nodes emit at the same time
2. Idle Listening : Node listens to an idle channel
3. Overhearing: Node listens for a message sent to
another node
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Energy in WBAN
• Battery lifetime is very important
– Required Lifetime
• Swallowable Camera Pills : 12 hours
• Cardiac Defibrillators and pacemakers : 5 years
• Reducing the waste of energy can maximize battery lifetime
• How to improve energy efficiency
– Routing
– Mobile Base Station
– Energy efficient MAC protocol
– …
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Major MAC Protocol Approaches
• Contention Based (CSMA/CA)
– Nodes need to perform CCA before transmission of data
– If the channel is busy, the node defers its transmission till it
becomes idle.
– Its infrastructure-free
– Ad hoc feature
– Good adaptability to traffic fluctuation
• Schedule Based(TDMA)
– Channels are divided into fixed/variable time slots which are
assigned to nodes that transmit during its slot period
– Free of idle listening, overhearing and packet collisions because of
the lack of medium competition,
– But require tight time synchronization.
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Outlines
• Introduction
• Necessity of MAC Protocol for WBAN
• IEEE 802.15.4, IEEE 802.15.6 , MEB MAC.
• Channel Access Delay Minimization for Emergency Traffic
• Simulation Results
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802.15.4 Superframe Format
Active period
CAP
beacon
CFP
Contention Access
Period
Network beacon
Contention period
Inactive period
Contention
Free Period
beacon
Transmitted by network coordinator. Contains network information,
frame structure and notification of pending node messages.
Access by any node using CSMA-CA
Guaranteed
Time Slot
Reserved for nodes requiring guaranteed bandwidth
Inactive Period
Sleep period
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802.15.6 Superframe Format
The EAP is Emergency Access Period.
-> In this period only devices with emergency traffic can contend.
The RAP(Random Access Period) can be used by any device both
emergency and non-emergency.
-> The data that are accumulated in the device buffers have a priority
assigned to them. Each of the devices have to contend with backoff
windows according to their priority.
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Outlines
• Introduction
• Necessity of MAC Protocol for WBAN
• IEEE 802.15.4, IEEE 802.15.6 , MEB MAC.
• Channel Access Delay Minimization for Emergency Traffic
• Simulation Results
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Channel Access Delay
• Channel Access Delay is the duration from
the time when a packet arrives at the queue
until the designated packet gains access to
the channel.
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MEB-MAC: Superframe Format
 Listening Window is placed periodically in Scheduled Access
Phase to reduce the access delay of Emergency Data.
A Listening Window is dedicated to emergency alarms to
provide high reliability with low delay.
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Algorithm for Inserting Listening Window
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Average Channel Access Delay
d0  0
; if  0  tei   1 or  3  tei   4
1
d1  DRAP1
2
1
d 2  DRAP 2
2
1
d3  DMAP
2
1
d 4  DCAP
2
; if  1  tei   2
; if  4  tei   5
; if  1  tei   3 or  5  tei   6
; if  7  tei   8
1
d1  DRAP1, ; if t0  tei  t1
2
1
d 2  DRAP 2, ; if t2  tei  t3
2
1
d3 
DMAP ; if t1  tei  t2 or t3  tei  t4
2* N LW
1
d 4  DCAP ; if t5  tei  t6
2
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Outlines
• Introduction
• MAC Protocol for WBAN
• IEEE 802.15.4, IEEE 802.15.6 , MEB MAC.
• Channel Access Delay Minimization for Emergency Traffic
• Simulation Results
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Simulation Result : Channel Access Delay
Comparison
Non Congested Scenarios
Congested Scenarios
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Thank You
?
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