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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
5
Introduction• Cooperative
– PHY Layer
Sender Receiver
Cooperative node (CN)
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
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
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
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
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