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Routing Techniques in Wireless Sensor Networks: A Survey Routing Techniques in Wireless Sensor Networks: A Survey

Routing Techniques in Wireless Sensor Networks: A Survey - PowerPoint Presentation

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Routing Techniques in Wireless Sensor Networks: A Survey - PPT Presentation

Outline Background Classification of Routing Protocols Data Centric Protocols Flooding and Gossiping SPIN Directed Diffusion Rumor Routing Background Sensor nodes Small wireless battery ID: 297669

nodes routing packet gpsr routing nodes gpsr packet data protocol node forwarding cluster greedy network packets perimeter sensor protocols

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Slide1

Routing Techniques in Wireless Sensor Networks: A Survey

Slide2

Outline

Background

Classification of Routing Protocols

Data Centric Protocols

Flooding and Gossiping

SPIN

Directed Diffusion

Rumor RoutingSlide3

Background

Sensor

nodes

Small

, wireless, battery

powered

Energy

, bandwidth constrained

Data

sensing, relaying,

aggregating

No

global addressing scheme

Sink nodes

More

powerful nodes

Usually

gateway to wired networks

Data

collecting and processingSlide4

Goal

So at network layer, it is highly desirable to find methods for energy efficient route discovery and relaying of data from the sensor nodes to the BS so that the life time of the network is

maximized.Slide5

Routing ProtocolsSlide6

Data-centric Protocols

The ability to query a set of sensor nodes

Attribute-based

naming

Data

aggregation during relaying

For

example:

Flooding

& Gossiping

SPIN

Directed

Diffusion

Rumor RoutingSlide7

Flooding & Gossiping

In flooding, sensor broadcasts packets to all

its neighbors

till

dst

reached or packets'

ttl

== 0

In gossiping, sensor sends packets to

a randomly

selected neighbor which does

the sameSlide8

Flooding & Gossiping(cont.)

Pros

Simple

No

routing, no state maintenance

Cons

Implosion

Overlap

Resource blindness

Delay

in GossipingSlide9

SPIN – Sensor Protocols forInformation via Negotiation

Metadata negotiation done before transmitting the actual data.

3-way handshake: ADV, REQ, DATA

Event-drivenSlide10

SPIN(cont.)

Pros

Solve

the classic problems

Topological

changes are localized

Cons

No

guarantee on the delivery of dataSlide11

Directed Diffusion

Sink node floods named “interest” with

larger update

interval

Sensor

node sends back data via “gradients”

Sink

node then sends the same “interest”

with smaller

update interval

Query-drivenSlide12

Directed Diffusion (cont)

Pros

On

demand route setup

Each

node does aggregation and caching,

thus good

energy efficiency and low delay

Cons

Query-driven

, not a good choice for

continuous data

delivery

Extra

overhead for data matching and queriesSlide13

Rumor Routing

A trade-off between Query & Event flooding

An

agent, a long-lived packet, is

generated when

events happen

The

agent propagate the event to distant nodesSlide14

Rumor Routing (cont)

Pros

Avoid

query flooding

Cons

Performs

well only when # of events is small

Overhead

to maintain agents and event-tablesSlide15

Hierarchical Routing Protocols

When sensor density increases single tier networks cause

Gateway overloading

Increased latency

Large energy consumption

Clustered Network allow coverage of large area of interest and additional load without degrading the performanceSlide16

Hierarchical Routing Protocols

Idea

Partition the entire network into regions or clusters.

Select one or more nodes as the cluster head.

The routing is nodes -> cluster head A -> cluster head B -> cluster head C -> nodes

The routing between cluster heads and the routing within a cluster may follow different protocols (EGP-BGP and IGP-OSPF).

Issues resolved: Energy wasted in collision, collision avoidance, idle-listening

Achieves

Better scalability

Removes the load to less powerful nodesSlide17

The LEACH Protocol

L

ow-

E

nergy

A

daptive

C

lustering

H

ierarchy.

Distributed cluster formation technique that enables

self-organization

of large numbers of nodes.Slide18

LEACH - Setup

Set up phase

Cluster Head (CH) selection (random + rotating)

ADV

Join REQ

TDMA SCH prepared by CH (no collisions and reduced energy consumption)Slide19

LEACH - Steady State

Broken into frames, where nodes send their data to the cluster head at most once per frame during their allocated transmission slot.

Once the cluster head receives all the data, it performs data aggregation.Slide20

PEGASIS

P

ower-

E

fficient

GA

thering in

S

ensor

I

nformation

S

ystems.

The key idea in PEGASIS is to form a

chain

among the sensor nodes so that each node will

receive from and transmit to a close neighbor

.

Well, what was so bad in LEACH except for a bad name...Slide21

PEGASIS - Concept

Be

Greedy

!

Align with the one that has the max signal strength, form a near-optimal chain.

Communicate with

neighbors

only

.

But who takes care of communicating to BS?Slide22

PEGASIS - Leader

The main idea in PEGASIS is for each node to receive from and transmit to close neighbors and take turns being

the leader for transmission to the BS

.

Nodes take turns transmitting to the BS (

i

mod N

node in round

i

out of N nodes shall transmit to BS).Slide23

Passing the buck...

Token

passing approachSlide24

The TEEN Protocol

T

hreshold sensitive

E

nergy

E

fficient sensor

N

etwork protocol.

Proactive Protocols (LEACH)

The nodes in this network

periodically

switch on their sensors and transmitters, sense the environment and transmit the data of interest.

Reactive Protocols (TEEN)

The nodes react immediately to

sudden

and

drastic changes

in the value of a sensed attribute.Slide25

TEEN - Functioning

At every cluster change time, the cluster-head broadcasts to its members

Hard Threshold (HT)

This is a

threshold value for the sensed attribute

.

It is the absolute value of the attribute beyond which, the node sensing this value must switch on its transmitter and report to its cluster head.

Soft Threshold (ST)

This is a

small change in the value of the sensed attribute

which triggers the node to switch on its transmitter and transmit.Slide26

TEEN - Hard Threshold

The first time a parameter from the attribute set

reaches its hard threshold value

, the node switches on its transmitter and sends the sensed data.

The

sensed value is stored

in an internal variable in the node, called the

sensed value (SV)

.Slide27

TEEN - Soft Threshold

The nodes will next transmit data in the current cluster period, only when

both

the following conditions are true:

The current value of the sensed attribute is

greater than the hard threshold

.

The current value of the sensed attribute

differs from SV by an amount equal to or greater than the soft threshold

.Slide28

TEEN - Drawback

If the thresholds are not reached, the user will not get any data from the network at all and will not come to know even if all the

nodes

die

-

A

daptive

P

eriodic TEEN

This scheme practical implementation would have to ensure that there are no

collisions

in the cluster.Slide29

GPSR: Greedy Perimeter Stateless Routing for Wireless

NetworksSlide30

Presentation Overview

Introduction

Algorithm Key Ideas & Concepts

Examples

Evaluation

Matrices &

Results

Summary Slide31

GPSR Overview

Routing Protocol that

uses positions

of routers and a packet’s destination to make packet forwarding decisions

GPSR keeps state only about the local

topology (for only a single hop)

The word “

Stateless

” is not meant literally but refers to small, purely local state

GPSR

scales better

in per-router state than shortest-path and ad-hoc routing protocols

GPSR

finds correct new route quickly

under frequent topology changesSlide32

Algorithm’s Key Ideas

“The position of a packet’s destination and positions of the candidate next hops are sufficient to make correct forwarding decisions, without any other topological information.”

“Routing protocol that rely on end-to-end state concerning the path, face scaling challenge with increasing

number of

routers & rate of change of topology (mobility).”

“GPSR

generates routing protocol traffic independent of the length of the routes through the network, therefore generates a constant, low volume protocol messages as mobility

increases,”Slide33

GPSR Modes

Modes

Nominal:

Greedy

Forwarding

Special :

Perimeter Forwarding

Greedy

Forwarding

Uses only information about router’s immediate

neighbors

Forwarding node makes

locally optimal greedy choice

of the packet’s next hopSlide34

Greedy Forwarding Example

Follows successive closer geographic hops, until the destination is reached Slide35

Perimeter Forwarding

Used in the region where Greedy forwarding fails.

There are topologies in which the only route to a destination requires a packet move

temporarily farther

in geometric distance from the destination

Special mechanism (right hand rule) is used in such special situationSlide36

Perimeter Forwarding Example

Right Hand Rule

: x receives a packet from y, and forwards it to its first neighbor counterclockwise about itself , z

When Greedy Forwarding Fails.

x is a local maximum in geographic proximity to D

w and y are farther from DSlide37

Perimeter Forwarding Example

D is the destination

; x

is the node where the packet enters perimeter mode; forwarding hops are solid arrows; the line

xD

is dashed.

GPSR forwards packets along the face intersected by the line

xD

x

forwards the packet to the first edge counterclockwise about x form the line

xD

, follows right hand rule thereafterSlide38

Network Graphs

Full Graph

Greedy Forwarding

Planar Graph

Perimeter Forwarding Slide39

Planarized Graphs

The RNG graph.

For

edge(u; v) to be included,

the shaded

lune

must contain no witness w.

The GG graph.

For

edge(u; v) to be included,

the shaded

circle must contain no witness w.Slide40

GPSR Operation

GPSR combines greedy forwarding on full network graph and perimeter forwarding in

planarized

network graphs

All nodes maintain neighbor table, which stores the address and location of their single-hop radio neighbors

The table provides all states required for forwarding decisionsSlide41

GPSR Operation

All packets are marked initially as greedy mode

Upon receiving a greedy-mode packet, a node searches its neighbor table geographically closest to the packet’s destination.

If the neighbor is closer to the destination, it forwards the packet to the neighbor.

If no neighbor is closer, the packet is marked into perimeter mode.Slide42

GPSR Operation

In perimeter mode, the packet is forwarded using a simple planner graph

The packet is forwarded to progressively closer faces of the planner graph using the right hand rule

In perimeter node, the GPSR records the location where greedy failed, and the first edge a packet crosses on a new face

When the destination is not reachable, the packet will tour unsuccessfully around the entire face as no intersection with

xD

is detected

Upon traversing on the face second time, the repetition is detected to correctly drop the packetSlide43

Algorithm Evaluation Matrices

Packet

delivery success

rate

Fraction of applications’ packets delivered successfully by the routing algorithm

R

outing

protocol

overhead

Per-node state: storage required at each node

Protocol message cost: number of protocol packets sent by the routing algorithm

O

ptimality

of

path lengths

taken by data

packetsSlide44

Packet Delivery Success Rate

GPSR

with

varying

beacon

intervals

, B,

compared

with

Dynamic

Source

Routing (DSR). 50 nodes

GPSR delivers a slightly greater fraction of packets successfully than DSRPause time

is the time duration for which all nodes hold the same positions at waypoints. The mobility model used is the random way point model which generates waypoints at random. Slide45

Routing Protocol Overhead

Total routing

protocol

packets sent network-wide during the simulation for

GP

R

with varying

beacon intervals, B, compared

with

DSR. 50

nodes

.

GPSR offers greater savings in routing protocol overheadSlide46

Packet Delivery Success Rate

Packet Delivery

Success Ra t e . F o r G P S R

with

B =

1.5 compared with

DSR. 50, 112, a n d 200 node s .

GPSR delivers 97% of its packets along optimal-length paths vs. 84.9% for DSRSlide47

Routing Protocol Overhead

Total routing

protocol

packets sent network-wide during the simulation for GPSR

with

B = 1.5 compared with DSR. y axis log-scaled. 50, 112,

and

200 nodes.

GPSR generates drastically less routing protocol traffic

w.r.t

. to DSR Slide48

Summary

GPSR routing algorithm uses geography to achieve small per-node route state, small routing protocol message complexity, and extremely robust packet delivery

GPSR generates routing protocol traffic independent of the length of the routes through the network, therefore generates a constant, low volume protocol messages as mobility increases

GPSR performs better than

DSR. GPSR keeps states proportional to no. of neighbors; DSR keeps sates proportional to product of no of routes learned and route length in hops.

Besides Hierarchy and Caching, Geography is leverages for scaling routingSlide49

Thank you