A COOPERATIVE LOW POWER MAC PROTOCOL FOR WIRELESS SENSOR NETWORKS Ahmed Ben Nacef, Sidi-Mohamed Senoucik, Yacine Ghamri- Doudane and Andr´e-Luc Beylot IEEE ICC 2011 Speaker : Chuan-Heng, Chi
Outline Introduction Related works Motivation Goals CL-MAC CL-MAC(P) CL-MAC(R) Simulation Conclusion
Introduction WSNs are composed of small and cheap sensors that can sense, compute and communicate
Introduction How to design a MAC protocol Reduce energy consumption with LPL Improve network throughputs with cooperative communication
Related works B-MAC Low Power Listening (LPL) Sender Receiver Long Preamble awake sleep DATA Target address in data header S R others Receive DATA
Related works X-MAC Sender Receiver awake sleep DATA Receive DATA S R PR R wake up A A Short preambles with target address information
Motivation Unnecessary energy waste Bad channel conditions and packet retransmission Sender Receiver DATA Receive DATA PR R wake up A A
Goals This proposed protocol combine the X-MAC and cooperative communication Reduce the energy consumption Improve the radio resource usage
CL-MAC A Cooperative LPL MAC Protocol Proactive low power cooperative [CL-MAC(P)] Reactive low power cooperative [CL-MAC(R)]
CL-MAC(P) Source Destination Wake-up N1 (selected relay) N2 RDV PR packets: destination address and RDV BRS: Begin Relay Selection R-R: Relay reply R-A: Relay ACK BRS R-R R-A DATA PR ACK S D N1 N2 awake sleep Preamble packets
CL-MAC(P) ACK DATA S D N1 N2 Source Destination Wake-up N1 (selected relay) N2 RDV PR packets: destination address and RDV BRS: Begin Relay Selection R-R: Relay reply R-A: Relay ACK BRS R-R R-A DATA PR More than one source awake sleep
CL-MAC(P) Preamble collision avoidance Source 1 Source 2 Wake-up Inter-preamble RandomBack-off Preamble heard delay the transmission PR S1 S2 awake sleep
CL-MAC(P) Relay selection – The potential relay deduces the state of the channel to the destination from the last received packets and read its own residual energy N1 N2 Destination Begin units R-R R-A 0.1 units CSI: channel state information RE: residual energy S D N1 N2 RDV awake sleep
CL-MAC(R) Source Destination N1 (selected relay) N2 PR packets: destination address and RDV DATA ACK Wake-up PR S D N1 N2 RDV awake sleep
CL-MAC(R) Source Destination N1 (selected relay) N2 PR packets: destination address and RDV RFR: Request-For-Relay DATA ACK DATA RFR S D N1 N2 Wake-up PR RDV awake sleep
Simulation Simulation environment Opnet simulator Sleep period : 0.09s Wake up period : 0.01s Interpreamble length : 0.005s Sink : 1 Source : varying from 1to 5 Potential relays : varying from 0 to 4 Each source node sends a periodic traffic : 1 packet/s The size of data packet : 127bytes The size of BRS,ACK,PR,R-R,RFR and R-ACK : 2020bytes The current draws of the radios are : 17.4mA for transmission, 19.7mA for reception and mA when the node is sleep mode
Simulation
Conclusion The proposed protocol and its variants combine Low Power Listening and cooperative communication techniques enhance the channel use reduce the energy consumption