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A Novel Physical Carrier Sensing Scheme for enhancing Spatial Reuse in Multihop Wireless Networks

Yongning Zhang, Bassel Alawieh, Chadi Assi 

Dept. of Science & Engineering, Concordia University in the

U.S.A.

World of Wireless, Mobile and Multimedia Networks(WoWMoM), 2008

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Outline

Introduction Protocol Simulation Conclusion

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Introduction

Higher CSth

rc

A B C

4

Introduction

lower CSth

rc

A B C

5

Introduction

A B C

d

6

Introduction

A B C

n

r

P

P

rt P

r

P

4

cnntol PPP

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Introduction

A B C

cnt

tol Pr

PP

44

1

4

)(

cnt

ii

PrP

Pr

ri

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Protocol

Scenario 1

A B

Cfailure

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Protocol

Interference from concurrent transmissions Collisions which are due to contending hosts

which initiate their transmissions simultaneously

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Protocol

transmits T times A times are successful Pc is collision probabilities Pe is error probabilities Nbusy and Nidle represent respectively the number of

time slots in which a node senses the channel as busy/idle

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Protocol

Pc is collision probabilities Pe is error probabilities

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Protocol

If Pe is above a certain threshold PF ,a node decreases its CSth.

If Pe is below a certain threshold PS, a node increases its CSth.

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Protocol

Scenario 2

A B

Cfailurefailure

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Protocol

A B C

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Protocol

A B C

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Protocol

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Protocol

Switch from 4-way to 2-way handshake

If this transmission is successful, the 2-way handshake will be activated for the next transmission attempt.

otherwise, a node will keep on using the 4-way handshake until the transmission is successful.

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Simulation

Simulator : Qualnet Propagation model : 2-ray mode Routing protocol : AODV

Dynamic CCA adaptation : 11Mbps Spatial Backoff : default CS th=-84dbm

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Simulation

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Simulation

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Simulation

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Simulation

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Conclusion

The paper proposed a novel scheme that balances

the tradeoff between collision and spatial reuse in multihop wireless networks.