Topology control protocols for WSNs challenges and research opportunities, 14 Nov 2014

This project is funded by Structural Funds of the European Union and state budget of the Czech Republic

NEW CREATIVE TEAMS IN PRIORITIES OF SCIENTIFIC RESEARCH

CZ.1.07/2.3.00/30.0055


Topology Control Protocols for WSNChallenges and Research Opportunities

Mohamed Mostafa Fouad


Agenda • WSN: An Overview• WSN Design challenges

• Topology Control (TC) Basic Idea• Topology Control Phases

– Topology Construction Phase– Topology Maintenance Phase– The A3 Algorithm– Topology Control Motivations

• Challenges & Open research Opportunities


• WSN: An Overview• WSN Design challenges




1

WSN: An Overview

Agenda




WSN: An Overview


WSN Design challenges• Resource constraints

• Depletable resources (e.g. battery power)


WSN Design challenges• Heterogeneity

– Devices with different capabilities

• Distribution Strategy– Structured vs. Randomized


• Fault Tolerance

• Privacy and security

WSN Design challenges






2

Topology Control (TC) Basic Idea

Agenda


Topology Control (TC) Basic Idea• A topology control protocol can be defined as an iterative process that

dynamically reduces the initial topology of a wireless sensor network.

Initialization Phase

Topology Construction

Topology Maintenance


Topology Construction Phase

Initial Topology Reduced Topology


Topology Construction Phase

Assign Node’s Transmission Power


Topology Control Motivations• Energy Conservation

• Collision Avoidance• Eliminate Exposed Terminal

Problem


* taken from Pedro Wightman, Miguel A. Labrador, ”A3: a topology control algorithm for wireless sensor networks”, In Proceedings of the IEEE GLOBECOM, 2008.

The A3 TC Algorithm *

AC

D

B

GE

a. Hello MessageNeighbor discovery

F


AC

D

B

GE

b. Parent Recognition Message

Answer from candidate nodes, with metrics

F




AC

D

B

GE

c. Children Recognition Message

List of selected children

F




AC

D

B

GE

d. Sleeping MessageNodes that received this message will turn

off

F




AC

D

B

GE

e. Check for ChildrenNode D will send a Hello Message,

looking for uncovered nodes

F




AC

D

BF

GE

f. Final Topology

The A3 TC Algorithm



Topology Maintenance Phase• Monitors the network status and takes the decision

for switching to a new reduced topology.


Topology Maintenance Triggering Criteria

NEW TOPOLOGY CONSTRUCTION

Failure-based

Energy-based

Time-based






3

Challenges &

Opportunities

Agenda


• Finding the Minimum Connected Dominating Set (CDS) of Active Nodes that guarantee both:– Network connectivity – Area coverage

• The Critical Transmission Range

Challenges & Opportunities


Challenges & Opportunities • Define the Optimal Time / Energy threshold for Topology

Maintenance phase

• Maintenance Scope– Global– Local


Challenges & Opportunities • Static topology maintenance

• Dynamic topology maintenance

• Hybrid topology maintenance


Challenges & Opportunities

• Security


29

The Question

Using Optimization Techniques Can Bring any

Enhancement toTopology Control Protocols’ ?


Thank you

Mohamed Mostafa Ismail

Ostrava, Faculty of Electrical Engineering and Computer Science (14 Nov 2014)


Presentations & Public Speaking

Topology control protocols for WSNs challenges and research opportunities, 14 Nov 2014