sesam: a semi -synchronous, energy savvy, application-aware mac renato lo cigno, matteo nardelli...
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SESAM: A Semi -Synchronous, Energy Savvy, Application-Aware MAC
Renato Lo Cigno, Matteo NardelliDISI, University of Trento
Trento, Italy
Michael WelzlInstitute of Computer Science,
University of InnsbruckInnsbruck, Austria
Networking Group University of Trento
http://networking.disi.unitn.it
Networking Group University of Trentohttp://networking.disi.unitn.it
Outline
TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion
Networking Group University of Trentohttp://networking.disi.unitn.it
TRITon is a research and innovation project funded by the project members and the Autonomous Province of Trento (Provincia Autonoma di Trento, PAT) aimed at advancing the state of the art in the management of road tunnels, specifically to improve safety and reduce energy costs.
An example application, central in TRITon, is adaptive lighting. In current deployments, the light intensity inside the tunnel is typically regulated based on design parameters and the current date and time, and regardless of the actual environmental conditions.
Web Site:http://triton.disi.unitn.it/
Networking Group University of Trentohttp://networking.disi.unitn.it
In TRITon, the light intensity inside the tunnel will instead be regulated through a wireless sensor network (WSN).
To bring state-of-the-art research and technology like WSN into road tunnel management, the traditional lab-centered research is not sufficient. Indeed, TRITon will transfer its results in real test-sites, four operational tunnels on road SS 45bis near Trento. This will provide not only the ultimate test for the project outcomes, but also a direct and measurable benefit to the local population.
Networking Group University of Trentohttp://networking.disi.unitn.it
Outline
TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion
Networking Group University of Trentohttp://networking.disi.unitn.it
Energy consumptionLow level MAC 802.15.4
Idle power 1 μW
Sense power 30 mW
Rx power 60 mW
Tx power 25 to 50 mW
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600
2 4 6 8 10 12 14 16 18 20
Ene
rgy
[J]
No. of stations
Total energy consumption per node per day
Bench-MAC 0.2 pck/minBench-MAC 1.0 pck/minBench-MAC 5.0 pck/min
Energy efficiency is one of the primary concern in a wireless sensor network expecially if the sensors are located in unfriendly environment like a road tunnel
In Table we report the typical consumption value of a WSN node
Graph rappresent the energy consumption with different transmission rate
Networking Group University of Trentohttp://networking.disi.unitn.it
Energy consumption
0
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2 4 6 8 10 12 14 16 18 20
Ene
rgy
[J]
No. of stations
Energy consumption per day for each function; 1 pck/minBench-MAC TxBench-MAC Rx
Bench-MAC Sense
Networking Group University of Trentohttp://networking.disi.unitn.it
Energy consumption
Networking Group University of Trentohttp://networking.disi.unitn.it
Outline
TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work
Networking Group University of Trentohttp://networking.disi.unitn.it
Mac ProtocolAn extensive amount of work has been done on energy conserving MAC protocols.
Existing approaches can be categorized as synchronous and asynchronous, although there are some hybrids.
Synchronous: SMAC
PROS
• periodic listening;
• collision avoidance;
• overhearing avoidance.
CONS
• Nighbors synchronization
• Sleep and listen period is predefined and constant
•Complex implementation
Asynchronous: BMAC
PROS
• Low Power Listening (LPL)
• Scalability
CONS
• preamble is longer than sleep period;
• overhearing.
Networking Group University of Trentohttp://networking.disi.unitn.it
Outline
TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion
Networking Group University of Trentohttp://networking.disi.unitn.it
SESAMSESAM is a distributed MAC protocol, which, making use of application level information to predict future transmission instants between nodes.
Our goal is:
• Useless (re)-trasmissions;
• receiving packets which are not for the node;
• sensing the channel without need.
Constraints are:
• No global coordination, but only pairwise (i,j) implicit signaling;
• Self-bootstrapping properties for new nodes entering the system and for the activation of a new traffic relation.
Networking Group University of Trentohttp://networking.disi.unitn.it
SESAM
The system is based on low-level real time MAC functions able to do CSMA and generate acknowledgments.
Elementary coordination for a single relation:
Networking Group University of Trentohttp://networking.disi.unitn.it
SESAMHousekeeping periods:
Networking Group University of Trentohttp://networking.disi.unitn.it
ResultWe compared SESAM with two version of a B-MAC like protocol. For all protocol we consider acknowelged transmission and absence of collision avoidance procedures
BenchMAC-0: Upon plain CDMA we insert a low power listening (LPL) functionality which enables nodes to sleep most of the time, and wake up periodically to sample the channel status;
BenchMac-1: This is the 1-persistant version of the protocol. The different with the BenchMAC-0 are: if the channel is sensed busy the node wait until the trasmission ends and immediatly transmits the packet and all other nodes must keep sensing the channel after the end of a packet trasmission.
Networking Group University of Trentohttp://networking.disi.unitn.it
Result
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2 4 6 8 10 12 14 16 18 20
Ene
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No. of Station
Total energy consumption per node per day
SESAMBanchMAC 1-P
BanchMAC 0-P
rate: 2pck/min
rate: 1pck/min
rate: 0,5pck/min
Networking Group University of Trentohttp://networking.disi.unitn.it
Result
0
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10 20 30 60 90 120 150 180 210 240
% P
acke
t lo
st
Packet/min
Packet Lost for 10 station
τlp = 500ms
τlp = 50ms
BanchMAC 0-PBanchMAC 1-P
SESAM
Networking Group University of Trentohttp://networking.disi.unitn.it
Outline
TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion
Networking Group University of Trentohttp://networking.disi.unitn.it
Multi-housekeeping domain
The most critical working conditions for a CSMA base WSN are with a wide area coverage using the same frequency channel
Networking Group University of Trentohttp://networking.disi.unitn.it
Multi-housekeeping domain - bootstrapping
Power on
Sensingchannel
rx msg?
N
Send msg. NEW HK
Send msg.ACK to HK
end sense?
Y
Y
N
Syncro. toone or multi HK
Packet format:
NEW HK = (ID node, HK domain, τ, NEW)
ACK HK = (ID node, ID node sender, HK, τ, ACK)
Networking Group University of Trentohttp://networking.disi.unitn.it
Outline
TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion
Networking Group University of Trentohttp://networking.disi.unitn.it
Conclusion