Long Cheng†‡, Jiannong Cao‡, Canfeng Chen§, Hongyang Chen∥, Jian Ma§, Joanna Izabela Siebert‡

†State Key Lab of Networking & Switching Tech., Beijing Univ. of Posts and Telecomm., China‡Department of Computing, Hong Kong Polytechnic University, Hong Kong

§Nokia Research Center, Beijing, China∥Institute of Industrial Science, The University of Tokyo, Tokyo, Japan

COOPERATIVE CONTENTION-BASED FORWARDING FOR WIRELESS SENSOR

NETWORKS

ACM IWCMC 2010

2

Outline• Introduction• Related Works• Goals• Assumption• Cooperative Contention-Based Forwarding (CCBF)• Simulation• Conclusion

3

Introduction• Geographic routing

Source

Sink

Poor link qualityUnreliable link Interference

Overhear transmissions

Overhear transmissions

4

Introduction

Source

How to choose the cooperative node?

Sink

B

5

Introduction• Cooperative

– PHY Layer

Sender Receiver

Cooperative node (CN)

Sender Receiver

Cooperative node (CN)

6

Introduction• Cooperative

– MAC Layer

Sender Receiver

Cooperative node (CN)

7

• CBF (Cluster-based forwarding)

Related Works

Sender A

D

C

Sink

Distant helper

B

nexthop

Intermediate helper

8

CBF

Sender A

nexthop B

C

D

Data

Data

Data

Data Data

Slot for distant helper Slot for intermediate helper

Sender A

D

C

Sink

Distant helper

Intermediate helper

nexthop B

New nexthop

RTS CTS

New nexthopData

9

• CBF (Cluster-based forwarding)

Related Works

Sender A

D

C

Sink

Intermediate helper

B

nexthop

10

CBF

Sender A

nexthop B

C

D

Data

Data

Data

Slot for distant helper Slot for intermediate helper

Sender A

D

C

Sink

Distant helper

Intermediate helper

nexthop B

New nexthop

RTS CTS

New nexthop

Data

Data

11

• CRL (Cooperative Relaying and Leapfrogging)

Related Works

Sender A

D

C

Sink

LPF

B

1) Didn’t receive RTS from A.2) Overhear a data packet from

C.

LeaPFrog Node

nexthop

Relay

12

CRL

Sender A

nexthop B

C

LPF D

Data

Data

Data

Sender A

D

C

Sink

LPF

nexthop B

LOSS

Data

Data

Data

Timer

ACKD terminates the forwarding process of B.

D becomes a new sender.

RTS CTS ACK

Relay

13

Related Works – Disadvantage

D

Destination

C

B

nexthop

Sender A

helper

helper

t0： A→B

t1： C→B

t2： D→B

Sender A

nexthop B

C

Data

Data

Data

LOSS

Data

DData

Data

Data

Data duplications

Hidden helper problem

Packet duplications

14

Goals• Select better next-hop.– increasing the average advance per hop (AAPH)

• Avoid packet duplications.

DS

C

A B

15

Assumption• Every node knows

– Its location.– Neighbor locations.– Destination and its location.

16

Cooperative Contention-Based Forwarding (CCBF)

Sender A

E

DDestination

C

B

nexthop

Overview

17

CCBF• Phase I

– Nexthop Selection

• Phase II– Cooperative Forwarding

18

CCBF• Next-Hop Selection

Sender A

B

C

E

RTS CTS

BackoffC = t(sender, C, dest.)

BackoffE= t(sender, E, dest.)

ndestinationsendertbackoffn ,,

,0 , ,

1 randomiTr

dnsEADVmax

PRR

dnDistdsDist

/1

) ,() ,( BackoffB = t(sender, B, dest.)

Sender A

E

C

B

Destination

19

d

• Next-Hop Selection

CCBF

ndestinationsendertbackoffn ,,

,0 , ,

1 randomiTr

dnsEADVmax

PRR

dnDistdsDist

/1

) ,() ,(

Sender A

19

NODE B

Dist 141-116 = 25

PRR 0.91

C

141-133 = 8

0.79

E

141-104 = 37

0.41

EADV 22.75 6.32 15.17

NODE B C E

• Dist(B,d) = 116• PRRB = 0.91

• Dist(E,d) = 104• PRRE = 0.41

• Dist(C,d) = 133• PRRC = 0.79

• Dist(A,d) = 141

10s 10s 10sTmax

𝜏 3s 3s 3s

1 −𝐸𝐴𝐷𝑉 ( 𝐴 ,𝑛 ,𝑑)

𝑟 0.43120.8420.621𝑟𝑎𝑛𝑑𝑜𝑚(0 ,𝜏) 1s 3s 1s

t(s,n,d)(backoff) 5.3𝜇𝑠11.4𝜇𝑠7.2𝜇𝑠

B

E

Packet reception ratio

C

20

CCBF• Next-Hop Selection

Sender A

B

C

E

RTS CTS

BackoffC = t(sender, C, dest.)

BackoffE= t(sender, E, dest.)

ndestinationsendertbackoffn ,,

,0 , ,

1 randomiTr

dnsEADVmax

PRR

dnDistdsDist

/1

) ,() ,( BackoffB = t(sender, B, dest.)

Sender A

E

C

B

nexthop

Data

CTS Cancels backoff.

CTS Cancels backoff.

Destination

21

CCBF• Phase I

– Nexthop Selection

• Phase II– Cooperative Forwarding

22

CCBF• Cooperative Forwarding

– Cooperative Area1) received the data packet

2) received the CTS

3) positive advances toward the destination

23

CCBF• Cooperative Area

Sender A

E

DDestination

C

B

nexthop

Cooperative Area

1) Received the data packet

2) Received the CTS

3) Positive advances toward the destination

24

CCBF• Cooperative Forwarding

Sender A

E

C

B

nexthop

Sender A

B

C

E

RTS CTS

BackoffC

BackoffE

BackoffB

Data

ACK Cancels backoff.

Data

Data

Data

) ,() ,(,, dnDistdsDistdnsADV

dnstbackoffn ,, ,0

, ,1 randomiT

r

dnsADVmax

Phase I Phase II

ACK

ACK Cancels backoff.

…

25

CCBF• Next-hop receiver B and it serves as the actual forwarder.

Sender A

B

RTS CTS

Phase I Phase II

ACK

Data

Data …

Sender A

E

Other node

B

Nexthop & forwarder

26

CCBF• The helper E serves as the actual forwarder.

Sender A

B

RTS CTS

Phase I Phase II

ACK

Data

Data

… EData

CONF (confirmation)

Data

Sender A

E

Other node

B

Nexthop

Forwarder

Other node(A’s neighbors)

27

Simulation

Parameter Value

Simulator NS-2

Sensing range 40m

Map size 200m*200m

Tmax 0.01s

TSIFS 10s

TDIFS 50s

28

Simulation

(0,0)

(200,200)

Source

Sink

200m

200m

29

Simulation

30

Simulation

31

Simulation

32

Simulation

33

Conclusion• CCBF avoids packet duplications.• In simulations,

– Increasing the average advance per hop– Improving the end-to-end energy e ciency and latencyffi– Improving the packet loss ratio

Thanks for your attention