geographic forwarding in wireless sensor networks with ... · geographic forwarding in wireless...

Geographic Forwarding inWireless Sensor Networks withLoose Position-AwarenessThomas Watteyne, Isabelle Augé-Blum,Mischa Dohler, Dominique Barthel

pimrc, 5 September 2007

Loose position routing @ pimrc / 05.09.07 / Thomas Watteyne 2

Wireless Sensor Networks

- measuring a physical value

- processing

- wireless communication

• hard to reach area

• random deployment

• no human intervention (battery…)

• no fixed infrastructure

• changing topology

• multi-hop

� Application domains military, surveillance, Health, intelligent homes …

Embedded systemEmbedded system

• processing power

• memory

• embedded energy


• Routing in WSNs

• Loose position awareness

• Using Path-recording

• Performances


Self-Organization: a definition

"Self-organization can be defined as the

emergence of system-wide adaptive structure

and functionality from simple local interactions

between individual entities"

C. Bettstetter

Routing !


TaxonomyRouting ?

data-centric hierarchical geographic

• flooding (1988)

• gossiping (1988)

• Dir. Diff. (2000)

• …

• LEACH (2000)

• TEEN (2001)

• PEGASIS (2002)

•…

• MFR (1984)

• GAF (2001)

• GFG/GPSR

(1999/2000)

• …

☺☺☺☺ easy

�� slow/overhead

☺☺☺☺ organized

�� energy inefficient ?

☺☺☺☺ implicit organization

�� location-awareness


Geographic routing: pros and cons

Pros

• Local decisions

• Simple

• Guaranteed delivery possible

Cons

• Each node needs to know its position

• Each node needs to know the destinations position

• Maintaining a neighborhood table

next paper ;-)


Greedy geographic routing

may fail If it doesn't fail, near to shortest

path


Greedy-Face-Greedy

Right hand rule to circumnavigate the void

greedy

mode

face

mode

?

planar

graph


Positioning inaccuracy

pla

nar

tra

nsf

orm

atio

n


GFG fails w. non-perfect positioning

When positioning

is not perfect,

creating a planar

graph disconnects

the network.


Our proposal

• Record path in the packet

1. never send a packet to a

neighbor whom you have

already sent a packet to;

2. send a packet back to a

neighbor (i.e. he has sent you

a packet before) only if there

are no other neighbors you

have never communicated

with;

3. if you have several choices of

neighbors whom you can

send back a packet, pick the

neighbor who has sent you a

packet last.


Example

greedy mode

face

mode


Results: delivery ratio


Results: number of hops

~ same as GFG but we do not assume triangular inequality

� Can be used when imperfect positioning accuracy


Thomas Watteyne

[email protected]

http://perso.citi.insa-lyon.fr/twatteyn/

geographic forwarding in wireless sensor networks with ... · geographic forwarding in wireless...

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