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SHORT PAPER: TCP over 6LoWPAN for IndustrialApplications
Tiancong Zheng, Ahmed Ayadi, Xiaoran Jiang
IT/TELECOM BretagneRennes, France
8-9 February 2011
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 1 / 23
Outline
1 IPv6 over Low-power Wireless Personal Area Networks: Overview
2 Reliable transport protocols for 6LoWPANs: Why TCP??
3 TCP over 6LoWPANs for Industrial Applications
4 Experimental SetupHardware SetupSoftware SetupPhysical SetupEnergy Parameters
5 Results and DiscussionOne hop ScenarioMulti-hop Results
6 Conclusion and perspectives
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 2 / 23
IPv6 Low-power Wireless Personal Area Networks:Overview
6LoWPAN is the name of a working group in the internet area of the IETF,
The IETF Working Group 6LoWPAN has recently introduced an adaptationlayer that provides header compression and fragmentation/reassemblymechanisms to allow sending/receiving IPv6 packets over LLNs (e.g., IEEE802.15.4).
Internet
IPv4/IPv6
Edgerouters
LoWPAN nodes
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 3 / 23
The 6LoWPAN layer in TCP/IP model
Figure: The 6LoWPAN architecture
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 4 / 23
Reliable transport protocols for 6LoWPANs: Why TCP??
Currently, the 6LoWPAN WG has defined only UDP header compressionalgorithm named NHC,
UDP does not assure reliable communication between wireless divines,
If some industrial applications are loss tolerant, many others applications aresensitive to losses and their performance decrease when the loss ratioincreases.
TCP is the most reliable transport protocol used in IP-based networks,
TCP ensures reliability of data transmission from a sensor to a host externalIP and vice versa,
TCP could be a good choice for Machine-To-Machine reliable connection,
With TCP, we are able open SSH connection to log into wireless devices(sensors, actors, etc.) and execute commands.
TCP allows also remotely programming/retasking wireless devicesover-the-air.
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 5 / 23
Reliable transport protocols for 6LoWPANs: Why TCP??
Currently, the 6LoWPAN WG has defined only UDP header compressionalgorithm named NHC,
UDP does not assure reliable communication between wireless divines,
If some industrial applications are loss tolerant, many others applications aresensitive to losses and their performance decrease when the loss ratioincreases.
TCP is the most reliable transport protocol used in IP-based networks,
TCP ensures reliability of data transmission from a sensor to a host externalIP and vice versa,
TCP could be a good choice for Machine-To-Machine reliable connection,
With TCP, we are able open SSH connection to log into wireless devices(sensors, actors, etc.) and execute commands.
TCP allows also remotely programming/retasking wireless devicesover-the-air.
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 5 / 23
Outline
1 IPv6 over Low-power Wireless Personal Area Networks: Overview
2 Reliable transport protocols for 6LoWPANs: Why TCP??
3 TCP over 6LoWPANs for Industrial Applications
4 Experimental SetupHardware SetupSoftware SetupPhysical SetupEnergy Parameters
5 Results and DiscussionOne hop ScenarioMulti-hop Results
6 Conclusion and perspectives
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 6 / 23
TCP over 6LoWPANs for Industrial Applications
Reduces wired links between machines,
I Replace cables by reliable wireless Machine-to-Machine (M2M) links:low-cost, easy installation, easy move and removal, etc.
1
1larousse.frAhmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 7 / 23
TCP over 6LoWPANs for Industrial Applications
Renewable energy: Solar energy2, Wind power 3, etc.
I Reduce maintenance, integration and operation costs
2ecofriend.org3wordpress.com
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 8 / 23
TCP over 6LoWPANs for Industrial Applications
Environment: Waste control, 45, Air quality, etc.
4evoc.com5waste.epa.gov.tw
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 9 / 23
Outline
1 IPv6 over Low-power Wireless Personal Area Networks: Overview
2 Reliable transport protocols for 6LoWPANs: Why TCP??
3 TCP over 6LoWPANs for Industrial Applications
4 Experimental SetupHardware SetupSoftware SetupPhysical SetupEnergy Parameters
5 Results and DiscussionOne hop ScenarioMulti-hop Results
6 Conclusion and perspectives
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 10 / 23
Hardware Setup
In our testbed, all wireless devices are connected to the standard laptop byUSB port. This solution allows us to log the output messages from the motsto the standard laptop,
The embedded device used in our testbed: the Crossbow TelosB mote. Ituses TI MSP430 microcontroller, which offers a 10kB RAM, and a 48 kBprogram flash memory. Its radio is CC2420,which uses ISM frequency bandand offers 250 kbps data rate.
We used the last channel (No. 26) of IEEE 802.15.4 to reduce theinterference with IEEE 802.11.
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 11 / 23
Software Setup
Contiki OS 6 as the operating system for our wireless devices.
Contiki OSis a memory-constraint open source operating system fornetworked embedded devices that includes the uIPv6 stack.
We have chosen Contiki OS because 6LowPAN, UDP and TCP are alreadyimplemented on this OS.
Contiki OS provides standard operating system features like threads, timers,random number generator, clocks, a file system, and a command line shell.
TCP is partially implemented on Contiki OS because of thememory-constraint of the wireless devices.
6www.sics.se/contikiAhmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 12 / 23
Physical Setup
ERN1
N2
N3 N4
N5
EN
Laptop Station
Wireless Devices
1m 3m 3m
1.5m
1.5m
3m
Seven wireless nodes are distributed with the same distance (between threeand four meters) between each neighbor.We can distinguish four types ofwireless devices based on their functionalities:
1 The Edge Router is the border router that connects the wirelessnetwork to the IP-based wired network.
2 Wireless nodes (N1, N2, N3, N4, and N5) play two functions: a sensornode where TCP client application is running called Ternminal Node,or relay of data frames from the ER to the TN and vice-versa.
3 The External Node generates a concurrent CBR traffic.
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 13 / 23
Outline
1 IPv6 over Low-power Wireless Personal Area Networks: Overview
2 Reliable transport protocols for 6LoWPANs: Why TCP??
3 TCP over 6LoWPANs for Industrial Applications
4 Experimental SetupHardware SetupSoftware SetupPhysical SetupEnergy Parameters
5 Results and DiscussionOne hop ScenarioMulti-hop Results
6 Conclusion and perspectives
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 14 / 23
Energy Parameters
Contiki OS provides a tool to compute the running time spent by a node onone of the flowing radio states: Transmit and Listen.
Contiki OS provides also an estimation of its CPU consumption.
For example to compute the consumed energy due the channel listeningEListen
EListen = TListen × Voltage × IListen
where TListen and IListen are respectively the time spent by a mote in listen modeand the listen current.
Table: Energy Parameters
Parameter ValueVoltage 3 VCPU 0.5 mATransmit 17.4 mAListen 19.7 mA
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 15 / 23
One hop Results
Compare three scenarios:
I Only TCP,I TCP with UDP (364bps),I TCP with UDP (1546bps).
Table: Energy consumption distribution
Mac Protocol CPU Transmit ListenCX-MAC 7.5% 14.3% 78.1%
Table: TCP with CX-MAC: One hop performance
Cons. Ener.(mj) Segm. Retrans. Trans. Dur.(s)No CBR 2755.7 0.1 267.1CBR=364bps 2886.7 10.3 295.2CBR=1.5kbps 3393.1 52.1 408.7
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 16 / 23
Multi-hops scenario
Compare three scenarios:
I Only TCP,I TCP with UDP (364bps),I TCP with UDP (1546bps).
ERN1
N2
N3 N4
N5
EN
Laptop Station
Wireless Devices
1m 3m 3m
1.5m
1.5m
3m
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 17 / 23
Multi-hop: Retranmissions
1 2 3 4 5
0
50
100
150
200
250
Number of hops
Ret
ran
smis
sion
tim
es
No CBRCBR=364bps
CBR=1546bps
Figure: Experimental results of multi-hop TCP over 6LoWPAN end-to-endretransmissions times with and without a concurrent CBR traffic
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 18 / 23
Multi-hop: Transfer Duration
1 2 3 4 5
500
1,000
1,500
2,000
Number of hops
Tra
nsf
erD
ura
tion
(s)
No CBRCBR=364bps
CBR=1546bps
Figure: Experimental results of multi-hop TCP over 6LoWPAN transferdurationwith and without a concurrent CBR traffic
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 19 / 23
Multi-hop: Throughput
1 2 3 4 5
500
1,000
1,500
Number of hops
Th
rou
ghp
ut
(bp
s)
No CBRCBR=364bps
CBR=1546bps
Figure: Experimental results of multi-hop TCP over 6LoWPAN throughput withand without a concurrent CBR traffic
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 20 / 23
Multi-hop: Consumed energy
1 2 3 4 50.2
0.4
0.6
0.8
1
·104
Number of hops
Con
sum
edE
ner
gy(m
J)
No CBRCBR=364bps
CBR=1546bps
Figure: Experimental results of multi-hop TCP over 6LoWPAN total consumedenergy with and without a concurrent CBR traffic
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 21 / 23
Conclusion and perspectives
ConclusionI The IEEE 802.15.4 radios are very sensitive (interference with WiFi,
Air-conditioner Movement of persons, etc.).I TCP offers a reliable data communication between anywhere IP host to
a low-power wireless device,
PerspectivesI The TCP performance could be improved by reducing the header size
(TCPHC),I A cross-layer mechanisms could also optimize the energy consumption
by reducing the radio passive listening.
AcknowledgmentI This work has been funded by the Pole de Recherche Avancee en
Communications.
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 22 / 23
Thank you
Ahmed Ayadi (IT/TELECOM Bretagne) NTMS Wireless Sensor Networks 2011 Paris, 8-9 February 2011 23 / 23