Transcript WiSense Seminar#31 Khaled Ali`s presentation March 11, 2010.pdf

Urgency-based MAC Protocol for
WSBANs
WiSense Seminar Series
Presented by:
Dr. Khaled A. Ali
Outline
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Introduction
Wireless Personal Area Networks
WSBAN Application Examples
IEEE 802.15.4 MAC Protocol
Urgency-based MAC Protocol for WSBANs
U-MAC Performance Evaluation and Results
Concluding Remarks
Introduction
• Massive deployment of Sensor Networks
– Stimulated by numerous industry segments, and government
organizations
– Sensors and RFID tags will begin to inhabit every object
– Emergence of smart sensors with local intelligence
• Traffic volume increases dramatically
– Significant architectural changes to global IT infrastructure is
expected
– Process moves to network edge to aggregate and filter traffic
– Directional shift in network traffic
Introduction
• Integration of WSNs into 4G Networks
– Evolution of current ITU and IEEE standards
– Connect sensor world with back-end computing
environments
– Enable end-to-end solutions
2G
Other
networks
network
Phone
network
IP Network
3G
network
Cellular
Net
Sensor
Net
4G network
– Mixed Network Traffic of different priority levels and
different bandwidth requirements
Wireless Personal Area Networks
• WPAN (General Description):
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Low-rate: (250 kb/s, 40 kb/s and 20 kb/s data rates)
Range: 10-20 meters
Low power consumption
Addresses: short 16-bit or long 64-bit
Channels: 16 channels (2450 MHz band) , 10 channels
(915 MHz band ) and 1 channel (868 MHz band)
Access mechanisms: CSMA/CA or Aloha
Reliability : Fully acknowledgement, error checking
Cost: Low cost of deployment
MAC& PHY: IEEE 802.15.4 and IEEE 802.15.4a
Wireless Personal Area Networks
• WPAN (Network Topology):
peer-to-peer topology
star topology
FFD (PAN)
RFD
Wireless Personal Area Networks
• WPAN (Layered Architecture):
Upper Layers
802.2 LLC
SSCS
MAC
PHY
Physical Medium
WSBAN Application Example
Personal Health Care-mixed data rates
• Non-invasive WSBANs:
– Monitoring and sensing signals from the human
body for medical applications
– Distributed communication over the human body
• Invasive (In-Body) WSBANs:
– Connect implanted medical devices (MICS band)
and on-body sensors (ISM band)
– Miniature “Pill camera”
• Images and medical data are transmitted to a
central WS
• View, edit, archive and e-mail the live video,
images and date
• Physician can observe and detect exact location
of suspected “in-body” disorder
• Patient data can be sent through the network to
establish a diagnosis and trigger the required
actions via actuators
WSBAN Application Example
Business Meeting-mixed data rates
• RFID tag integrated in the watch
allows entrance in the conference
room
• Presentation can be downloaded
from nodes in the room
• Business cards are exchanged by
handshake
• Additional information can be
displayed by video glasses
• Using microphone/motion sensors
the main processing unit becomes
aware of the meeting and
automatically blocks phone calls
IEEE 802.15.4 MAC Protocol
• MAC Sublayer
INACTIVE
Beacon
CAP
CAP- Contention Access Period
CFP- Contention Free Period
GTS- Guaranteed Time Slots
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Generating Network beacons (PAN)
Synchronization
PAN association and disassociation
CSMA-CA
GTS
CFP(GTS)
Beacon
Urgency-based MAC Protocol for WSBANs
• Objectives:
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Supporting QoS in WSBANs for medical applications
Increasing network throughput
Minimizing packet rejection rate
Minimizing power consumption
• Approach:
– Star network topology
– Controlling the number of packet retransmission
• High priority traffic contend more for the transmission medium
than low priority traffic
– Slotted Aloha access mechanism
Urgency-based MAC Protocol for WSBANs
• Traffic Classification
– Critical Traffic
– Non-Critical Traffic
• Arrival Rate
– New Packet Arrival rate (λ)
• Critical packet arrival rate
• Non critical packet arrival rate
– Retransmitted packet
arrival rate (λr)
• Retransmission Queues
λ
Success
λ + λr
Channel
C1
C2
C3
Cr
U-MAC Block diagram
Collision
Urgency-based MAC Protocol for WSBANs
• Packet Transmission Scenario:
– Number of critical packet retransmission s; rc= 3
– Number of non critical packet retransmissions ;rnc= 2
rc
3
2
1
rnc
2
1
0
Pc
Pnc
U-MAC Performance Evaluation and Results
• Beacon frame enabled Star network
topology
• RFD nodes communicate with a single
FFD
• RFD nodes composed of critical nodes
and non critical nodes
• Critical nodes contend for the medium
rc times
• Non critical nodes contend for the
medium rnc times
• Maximum number of Critical Nodes
• Critical Nodes Packet Arrival Rate
• Network Throughput
U-MAC Performance Evaluation and Results
• Maximum Number of Critical Nodes Nc
– Aggrigate Packet Arrival rate G=1
– Number of Critical Nodes
U-MAC Performance Evaluation and Results
• Maximum Number of Critical Nodes Nc (Cont.)
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Ntotal=20 G=1
λc=0.05, 0.06
λnc=0.015
rnc= 0, 2, 5
rc= 0- 5
U-MAC Performance Evaluation and Results
• Critical Packet Arrival Rate
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Ntotal=20, Nc=5
λnc=0.015
rnc= 0, 2, 5
rc= 0- 5
G=1
U-MAC Performance Evaluation and Results
• Network Throughput
– Critical Nodes Throughput
– Non Critical Nodes Throughput
U-MAC Performance Evaluation and Results
• Network Throughput (Cont.)
– Nc=10
Nnc=10 rnc=1 10000 time slots each of 1 sec.
λc =λnc=0.025
λc =λnc=0.03
Concluding Remarks
• An Urgency-Based MAC protocol for WSBAN is
proposed
• U-MAC protocol differentiates nodal medium access
based of the criticality of the reported traffic
• Critical traffic is allowed to retransmit collided
packets more than non critical traffic
• U-MAC protocol performance is evaluated
mathematically and through simulation
• The performance results show the ability of the
proposed protocol to differentiate network traffic
Thank you