on the optimization and comparative evaluation of a reliable and efficient caching-based wsn...
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Paper presented at DRCN 2013TRANSCRIPT
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
On the Optimization and Comparative
Evaluation of a Reliable and Efficient
Caching-Based WSN Transport Protocol
Nestor M. C. Tiglao, António M. Grilo
INESC-ID/Instituto Superior TécnicoLisbon, Portugal
6 March 2013DRCN 2013, Budapest, Hungary
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Outline
1 Introduction
2 Related workCaching-based WSN TransportDTSN
3 Proposed MechanismsNACK RepairAdaptive MAC RetryTransmission Window Optimization
4 Performance Evaluation
5 Conclusion
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Wireless Sensor Network
Composed of small, resource-constrained wireless devices
Multi-hop operation
Transport protocol: reliability, congestion control,energy-efficiency
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Motivation
Develop simple mechanisms that can be implemented inconstrained devices (i.e., O(1) complexity)
Explore novel approaches in the transport layer
Leverage on intermediate caching to improve performance
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Caching-based Transport Protocols
Pump Slowly, Fetch Quickly (PSFQ, 2002)
sink-to-sensor, hop-by-hop reliability, designed for codeupdate, uses broadcast
Reliable Multi-Segment Transport (RSMT, 2003)
end-to-end reliability, uses NACKs, timer-driver lossdetection
Distributed TCP Caching (DTC, 2004)
caching TCP segments and retransmitting segmentslocal in case of packet loss
TCP Support for Sensor Networks (TSS, 2007)
not forward a cached TCP segment until the next-hophas received all previous segments (backpressure)
Distributed Transport for Sensor Networks (DTSN, 2007)
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
DTSN
Basic DTSN
Enhanced DTSN
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Cross-Layer Approach
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Enhanced NACK Repair Mechanism
RNACK Procedure
procedure pkt_recv(pkt)...if (!rpending_ && seqno! =next_) then
repseqno_ ← seqno
rpending_ ← 1 ⊲ raise Repair PendingSend RNACK (seqno)
else
do nothingend if
if (rpending_ && seqno==repseqno_) then
rpending_ ← 0 ⊲ clear Repair Pendingnext_ ← maxseen_ + 1 ⊲ update next_
end if
if (seqno > maxseen_) then
maxseen_ ← seqno ⊲ update maxseen_
end if
...end procedure
Example of the Enhanced NACKRepair Mechanism
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Adaptive MAC Retry Limit
r ← max
{
3, ⌊log Π− log p
log p⌋
}
R = 1−Π
Π is the Frame Error Rate(FER)p is the physical layer frame error rater is the MAC retry limitR is the desired MAC layer reliability
0 0.2 0.4 0.6 0.8 10
10
20
30
40
50
60
FER
r
Π=0.8
Π=0.9
Π=0.95
MAC retry limit value, r , forvarious MAC reliability levels
R FER≤0.3 FER=0.5 FER=0.7
80% 3 3 490% 3 3 695% 3 4 8
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Transmission Window Optimization
Dynamic Window
Additive Increase Multiplicative, Decrease (AIMD)algorithm (cwnd in TCP)inefficient in wireless networks
Fixed Window
based on the bandwidth-delay product, i.e., W =n4
where n = number of hopsHow about caching-based protocols?
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Setup
Simulation Parameters
Parameter Value
Network topology Linear chainPacket size 500 bytesNumber of packets(pktno) 500DTSN EAR interval 200 msecRouting protocol StaticMAC protocol 802.11bMAC retry limit (default) 3 (default)PHY error model Binary Symmetric ChannelMax. simulation time 2,000 secondsSimulator ns-2.31
Assumptions:Routing topology is stable
Cross-layer information isavailable
Scenario 1: Global Hotspot
Scenario 2: Localized Hotspot
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
DTSN Transmission Window OptimizationGoodput
AWopt = [CS , CS + ∆], ∆ = 10
2 8 10 20 30 40 500
20
40
60
80
100
120
140
Acknowledgment Window (AW) (in packets)
Goo
dput
(in
pac
kets
/sec
)
FER=0 FER=0.1 FER=0.3 FER=0.5 FER=0.7
(a) CS=10
2 8 10 20 30 40 500
20
40
60
80
100
120
140
Acknowledgment Window (AW) (in packets)
Goo
dput
(in
pac
kets
/sec
)
FER=0 FER=0.1 FER=0.3 FER=0.5 FER=0.7
(b) CS=20
Scenario 1 – Goodput, as a function of AW
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
DTSN Transmission Window OptimizationTransmission Cost
tx_cost =Ndata + Nack + Nnack + Nmack
pktno
2 8 10 20 30 40 500
50
100
150
200
250
Acknowledgment Window (AW) (in packets)
Tra
nsm
issi
on C
ost
FER=0 FER=0.1 FER=0.3 FER=0.5 FER=0.7
(a) CS=10
2 8 10 20 30 40 500
50
100
150
200
250
Acknowledgment Window (AW) (in packets)
Tra
nsm
issi
on C
ost
FER=0 FER=0.1 FER=0.3 FER=0.5 FER=0.7
(b) CS=20
Scenario 1 – Transmission Cost, as a function of AW
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Performance Analysis
Protocols considered:
DTPA – The DTPA protocol, W = BDP(n) + 3
DTPA-CWL – The DTPA protocol, W = BDP(n)
DTSN+ – The DTSN protocol with the proposedenhanced NACK repair and adaptive MAC retry limitmechanisms
TCP− – The TCP protocol without the RTO exponentialbackoff
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Performance AnalysisGoodput
Scenario 1
0 0.10 0.30 0.50 0.700
20
40
60
80
100
120
140
Frame Error Rate
Goo
dput
(in
pac
kets
/sec
)
DTPA−BDPDTPATCP−
DTSN+
Performance Gain of DTSN+
FER DTPA-CWL DTPA TCP−
0 96% 129% 88%0.10 51% 138% 59%0.30 71% 75% 137%0.50 720% 723% 1221%0.70 ∞ ∞ ∞
Scenario 2
0 0.10 0.30 0.50 0.700
20
40
60
80
100
120
140
Frame Error Rate
Goo
dput
(in
pac
kets
/sec
)
DTPA−BDPDTPATCP−
DTSN+
Performance Gain of DTSN+
FER DTPA-CWL DTPA TCP−
0 96% 129% 88%0.10 87% 135% 81%0.30 67% 123% 69%0.50 100% 92% 239%0.70 346% 266% 883%
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Performance AnalysisTransmission Cost
Scenario 1
0 0.10 0.30 0.50 0.700
20
40
60
80
100
120
140
160
Frame Error Rate
Tra
nsm
issi
on C
ost
DTPA−BDPDTPATCP−
DTSN+
Performance Gain of DTSN+
FER DTPA-CWL DTPA TCP−
0 29% 58% 29%0.10 20% 65% 21%0.30 19% 54% 19%0.50 39% 54% 49%0.70 ∞ ∞ ∞
Scenario 2
0 0.10 0.30 0.50 0.700
20
40
60
80
100
120
140
160
Frame Error Rate
Tra
nsm
issi
on C
ost
DTPA−BDPDTPATCP−
DTSN+
Performance Gain of DTSN+
FER DTPA-CWL DTPA TCP−
0 29% 58% 29%0.10 28% 60% 28%0.30 23% 63% 22%0.50 25% 57% 25%0.70 31% 48% 49%
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Performance AnalysisTCP cwnd Evolution
100 110 120 1300
2
4
6
8
10FER=0
Time (in sec)cw
nd (
in p
kt)
100 110 120 1300
2
4
6
8
10FER=0.1
Time (in sec)
cwnd
(in
pkt
)
100 110 120 1300
2
4
6
8
10FER=0.3
Time (in sec)
cwnd
(in
pkt
)
100 110 120 1300
2
4
6
8
10FER=0.5
Time (in sec)
cwnd
(in
pkt
)
100 110 120 1300
2
4
6
8
10FER=0.7
Time (in sec)
cwnd
(in
pkt
)
Scenario 1 – Evolution of TCP cwnd
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Performance AnalysisPacket Reception
100 102 104 106 108 1100
50
100
150
200
250
300
350
400
450
500
Time (in seconds)
Seq
uenc
e N
umbe
r
DTPA−CWLDTPATCP−
DTSN+
(a) FER=0
100 105 110 1150
50
100
150
200
250
300
350
400
450
500
Time (in seconds)
Seq
uenc
e N
umbe
r
DTPA−CWLDTPATCP−
DTSN+
(b) FER=0.1
100 105 110 115 120 125 1300
50
100
150
200
250
300
350
400
450
500
Time (in seconds)
Seq
uenc
e N
umbe
r
DTPA−CWLDTPATCP−
DTSN+
(c) FER=0.3
100 150 200 250 300 3500
50
100
150
200
250
300
350
400
450
500
Time (in seconds)
Seq
uenc
e N
umbe
r
DTPA−CWLDTPATCP−
DTSN+
(d) FER=0.5
Scenario 1 – Packet Reception
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
Conclusion
Transmission window and loss recovery semantics forcaching-based transport mechanisms need to be optimized
We have proposed the following mechanisms
enhanced NACK recoveryadaptive MAC retry limitoptimal DTSN transmission window
DTSN+ significantly outperforms TCP and DTPA interms of goodput and energy-efficiency
Future work
consider more complex and dynamic network scenariosstudy performance in presence of network congestion
Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
References
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Introduction Related work Proposed Mechanisms Performance Evaluation Conclusion
End
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