SESAM: A Semi -Synchronous, Energy Savvy, Application-Aware MAC Renato Lo Cigno, Matteo Nardelli DISI, University of Trento Trento, Italy Michael Welzl Institute of Computer Science, University of Innsbruck Innsbruck, Austria Networking Group University of Trento

Networking Group University of Trento Outline TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion

Networking Group University of Trento 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:

Networking Group University of Trento 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 Trento Outline TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion

Networking Group University of Trento Energy consumption Low level MAC Idle power1 μW Sense power30 mW Rx power60 mW Tx power25 to 50 mW Energy [J] No. of stations Total energy consumption per node per day Bench-MAC 0.2 pck/min Bench-MAC 1.0 pck/min Bench-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 Trento Energy consumption Energy [J] No. of stations Energy consumption per day for each function; 1 pck/min Bench-MAC Tx Bench-MAC Rx Bench-MAC Sense

Networking Group University of Trento Energy consumption

Networking Group University of Trento Outline TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work

Networking Group University of Trento Mac Protocol An 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 Trento Outline TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion

Networking Group University of Trento SESAM SESAM 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 Trento 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 Trento SESAM Housekeeping periods:

Networking Group University of Trento Result We 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 Trento Result Energy [J] No. of Station Total energy consumption per node per day SESAM BanchMAC 1-P BanchMAC 0-P rate: 2pck/min rate: 1pck/min rate: 0,5pck/min

Networking Group University of Trento Result % Packet lost Packet/min Packet Lost for 10 station τ lp = 500ms τ lp = 50ms BanchMAC 0-P BanchMAC 1-P SESAM

Networking Group University of Trento Outline TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion

Networking Group University of Trento 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 Trento Multi-housekeeping domain - bootstrapping Power on Sensing channel rx msg? N Send msg. NEW HK Send msg. ACK to HK end sense? Y Y N Syncro. to one 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 Trento Outline TRITon Project Energy consumption Mac Protocol in WSN SESAM Future work Conclusion

Networking Group University of Trento Conclusion