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Mohammad Ariful HuqSupervisor : Eryk Dutkiewicz

Minimizing Channel Access Delay for Emergency Traffic in IEEE 802.15.6Wireless Body Area Network (WBAN)

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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.

• A typical WBAN consists of a number of inexpensive, lightweight, miniature sensor platforms, each featuring one or more physiological sensors like

– 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/non-medical 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

• Mica2-based pulse oximeter Measures heart rate, blood oxygen saturation

• Telos-based two-lead Electrocardiogram

• 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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Network beacon

Contention period

Transmitted by network coordinator. Contains network information,frame structure and notification of pending node messages.

Access by any node using CSMA-CA

GuaranteedTime Slot

Reserved for nodes requiring guaranteed bandwidth

802.15.4 Superframe Format

Contention Access Period

Contention Free Period

Inactive period

beacon beacon

Inactive Period Sleep period

Active period

CAP CFP

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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

0 0 1 3 4

1 1 1 2

2 2 4 5

3 1 3 5 6

4 7 8

0 ;

1;

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;21

; 21

; 2

i ie e

iRAP e

iRAP e

i iMAP e e

iCAP e

d if t or t

d D if t

d D if t

d D if t or t

d D if t

1 1, 0 1

2 2, 2 3

3 1 2 3 4

4 5 6

1;

21

; 2

1;

2*

1;

2

iRAP e

iRAP e

i iMAP e e

LW

iCAP e

d D if t t t

d D if t t t

d D if t t t or t t tN

d D if t t t

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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

Congested ScenariosNon Congested Scenarios

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Thank You

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