Qo s based mac protocol for medical wireless body area sensor networks
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Author:
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HHuusssseeiinn TT.. MMoouuffttaahh
School of Information Technology and Engineering
University of Ottawa
Ottawa, Ontario, K7L 3N6
Presented by:
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15th Batch.
Date: 3rd May 2012.
2. CCoonntteennttss
Contribution.
Problem Definition.
• Background
Proposed Protocol
• Network Model
• Mathematical analysis
Performance Evaluation.
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Slide 2
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
3. CCoonnttrriibbuuttiioonnss
The paper proposed QoS-based MAC protocol that can be
employed in WBASNs.
This protocol is based on the IEEE 802.15.4 a Ultra Wide Band
(UWB) MAC protocol and the sensor nodes utilize the slotted
Aloha random access mechanism.
Also prioritizes the critical packets access to the transmission
medium by cutting of the number of retransmissions of the
collided non critical packets.
The critical traffic throughput is increased and its rejection rate is
decreased ,maintaining the non critical traffic QoS parameters
above a minimum provisioned level.
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Slide 3
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
4. Slide 4 PPrroobblleemm DDeeffiinniittiioonn
Medical information have different urgency levels and timing
constraints that require a sensor to:
Sense a physiological phenomenon ,
Process the sensed value,
Communicate the processed value to a central node, in a
bounded and guaranteed time.
For these requirements, A MAC protocol has to ,
Maximize network throughput,
Minimize packet rejection rate and,
Differentiate network traffic.
Green Networking Research Group 4
Dept. of Computer Science and Engineering, University of Dhaka
5. PPrroobblleemm DDeeffiinniittiioonn
The medium access mechanism in WBASNs is based on the MAC
protocol of Wireless Personal Area Networks (WPANs) standard.
WPAN (extended to UWB) s’ MAC protocol uses,
Carrier Sense Multiple Access/Collison Avoidance
(CSMA/CA) and,
Aloha access mechanism.
In this standards, star and peer-to-peer both network topologies
are supported.
Two communication modes for the star topology,
Beacon mode and
Non-beacon mode.
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Slide 5
BACKGROUND
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
6. PPrroobblleemm DDeeffiinniittiioonn
In beacon mode, network communications are controlled by the
network coordinator.
This coordinator periodically transmits beacon frames for ,
Device synchronization and network association control.
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Slide 6
BACKGROUND
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
7. PPrroobblleemm DDeeffiinniittiioonn
In Non-beacon mode, a network node can send data to the
coordinator using CSMA/CA or Aloha access mechanisms.
To receive data from the network coordinator, the node must
power up ,and poll the coordinator.
Non-beacon operation mode provides the best performance since,
Sensor nodes’ receivers are not required to power up for
receiving the beacon frame.
But the network coordinator cannot communicate with a node
unless it has been invited by the node to communicate.
The beacon mode operation is mainly suitable under very tight
data rate restrictions.
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Slide 7
BACKGROUND
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
8. PPrroobblleemm DDeeffiinniittiioonn
A Distributed Queuing Body Area Network (DQBAN) MAC
protocol for healthcare applications, that propose a QoS MAC
protocol.
The CRQ control access requests to the medium,
DTQ schedules sensor nodes collision-free packet transmissions.
But DQBAN requires the management of different queues and the
logic system implementation in every sensor node.
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Slide 8
BACKGROUND
Collision Resolution Queue (CRQ) and,
Data Transmission Queue (DTQ).
Green Networking Research Group
It utilizes two queues:
Dept. of Computer Science and Engineering, University of Dhaka
9. PPrrooppoosseedd PPrroottooccooll
In the proposed QoS-based MAC protocol,
slotted Aloha access mechanism is used,
which sensor nodes contend for the medium only at the
beginning of each time slot of the MAC frame.
Network nodes are grouped into,
Sensor nodes with critical information (C1)and ,
Sensor nodes of non critical information (C2).
Sensor nodes have the capability to sense multiple health
parameters to indentify the traffic, if it is critical or non critical,
Based on a predefined threshold.
Traffic is non critical if its sensed value is below the threshold.
It becomes critical when such threshold is exceeded.
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Slide 9
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
10. PPrrooppoosseedd PPrroottooccooll
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Slide 10
Figure: QoS-based MAC Protocol Illustration.
The total number of packets G, ready for transmission at the
beginning of a time slot can be defined as,
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
11. PPrrooppoosseedd PPrroottooccooll
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Slide 11
Network Model
A star network model composed of,
The coordinator node a Full-Function Device (FFD) and,
The sensor nodes are composed of Reduced-Function Devices
(RFDs).
Figure: WBAN Network for QoS-based MAC protocol Evaluation.
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
12. PPrrooppoosseedd PPrroottooccooll
N: total number of sensor nodes
Nc: sensor nodes of critical information
Nnc: sensor nodes of non critical information
G: aggregate packet arrival rate per time slot
Gc: aggregate critical packet arrival rate per time slot
Gnc: aggregate non critical packet arrival rate per time slot
Sc: total critical throughput
Snc: total non critical throughput
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Slide 12
Mathematical Analysis
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
Definitions
13. PPrrooppoosseedd PPrroottooccooll
Rc: total critical rejection rate
Rnc: total non critical rejection rate
λc : critical nodes packet arrival rate
λnc: non critical nodes packet arrival rate
rc: number of allowed packet retransmissions for critical nodes
rnc: number of allowed packet retransmissions for non critical
nodes
rc
max : maximum number of allowed packet retransmissions
for critical nodes
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Slide 13
Mathematical Analysis
min: minimum number of allowed packet retransmissions
for critical nodes
rc
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
Definitions
14. PPrrooppoosseedd PPrroottooccooll
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Slide 14
Mathematical Analysis
Here,
Aggregate critical packet arrival rate Gc per time slot is,
The term psucc in Equation (2) defines the probability of a
successful packet transmission in a time slot.
Equation (2) can be simplified ,
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
15. PPrrooppoosseedd PPrroottooccooll
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Slide 15
Mathematical Analysis
Equation (4) can be more simplified,
Similarly, Gnc can be written,
The aggregate packet arrival G per time slot can be rewritten,
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
16. PPrrooppoosseedd PPrroottooccooll
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Slide 16
Mathematical Analysis
Equation (7) can be simplified as in Equation (8)
Substituting the psucc term of Equation (8) ,
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
17. PPrrooppoosseedd PPrroottooccooll
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Slide 17
Mathematical Analysis
Equation (8) defines the aggregate network traffic generation
per time slot ,which is solved numerically to obtained G value.
This G value is used to compute the critical and non critical
throughput Sc and Snc respectively,
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
18. PPrrooppoosseedd PPrroottooccooll
Traffic Rejection Rate, the another performance parameter
studied in this paper is the total packet rejection rate.
This parameter is defined here for critical and non critical traffic
respectively,
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Slide 18
Mathematical Analysis
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
19. PPeerrffoorrmmaannccee EEvvaalluuaattiioonn
Figure :Aggregate Throughput, λ c = λ nc = 0.02. Figure:Aggregate Throughput, λ c = λnc = 0.025
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Slide 19
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
20. PPeerrffoorrmmaannccee EEvvaalluuaattiioonn
Figure :Aggregate Throughput, λ c = λ nc = 0.03. Figure: Packet Rejection Rate, λ c = λnc = 0.02
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Slide 20
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
21. PPeerrffoorrmmaannccee EEvvaalluuaattiioonn
Figure: Packet Rejection Rate, λ c = λnc = 0.025 Figure: Packet Rejection Rate, λ c = λnc = 0.03
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Slide 21
Green Networking Research Group
Dept. of Computer Science and Engineering, University of Dhaka
22. THANK YOU
Green Networking Research Dept. of
Computer Science and Engineering,
University of Dhaka
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