CMAC : A N ENERGY EFFICIENT MAC LAYER PROTOCOL USING CONVERGENT PACKET FORWARDING FOR WIRELESS SENSOR NETWORKS SECON 2007 S HA LIU, K AI - WEI FAN, P RASUN SINHA D EPARTMENT OF COMPUTER SCIENCE AND ENGINEERING, O HIO STATE UNIVERSITY # Presentation: Jinhyung Lee Computer Network Lab

C ONTENTS  I NTRODUCTION  C ONTRIBUTION  F EATURES  E VALUATION  C ONCLUSION  D ISCUSSION / 17

I NTRODUCTION  MAC LAYER DESIGN GOALS FOR WSN  L ONG LIFETIME  L OW LATENCY  L OW MAINTENANCE OVERHEAD  H IGH THROUGHPUT  E XISTING SOLUTIONS  S YNCHRONIZED MAC  SMAC, TMAC, DMAC  C ONSUME A LOT OF ENERGY ON PERIODIC SYNCHRONIZATION  U NSYNCHRONIZED MAC  BMAC, XMAC  U SE LONG PREAMBLES / 17

C ONTRIBUTION  CMAC  U NSYNCHRONIZED DUTY CYCLING  N O SYNCHRONIZATION OVERHEAD  A GGRESSIVE RTS, A NYCAST  Q UICKLY MAKE ROUTING PROGRESS  C ONVERGENT PACKET FORWARDING  A VOID OVERHEAD OF ANYCAST  A CHIEVED GOALS  E NERGY EFFICIENCY  L OW LATENCY  H IGH THROUGHPUT / 17

C ONVERGENT MAC  A GGRESSIVE RTS  A NYCAST PACKET FORWARDING  C ONVERGENT FORWARDING / 17

C ONVERGENT MAC  A GGRESSIVE RTS  A NYCAST PACKET FORWARDING  C ONVERGENT FORWARDING

A GGRESSIVE RTS  L ONG PREAMBLE MECHANISM OF BMAC  H IGH LATENCY  B REAKS UP LONG PREAMBLE INTO MULTIPLE RTS PACKETS  RTS BURST  S ENDER RECEIVES A CTS, IT SENDS PACKET IMMEDIATELY  L ATENCY AT EACH HOP COULD BE REDUCED BY HALF / 17 Sender Receiver Sleep Packet Sleep RTS RXCTS RXSleep Aggressive RTS

A GGRESSIVE RTS  A SSESS CHANNEL QUICKLY DURING EACH WAKE UP TIME  T O ALLOW NODES TO WORK AT A VERY LOW DUTY CYCLE  I F RECEIVER WAKES UP DURING THE GAP BETWEEN TWO RTS S  MISS RTS BURST / 17 RTS Channel check

A GGRESSIVE RTS  D OUBLE CHANNEL CHECK  C HECK THE CHANNEL TWICE TO AVOID MISSING ACTIVITIES  F OR EACH CHANNEL CHECK, NODES SAMPLE UP TO 5 TIMES  B ETWEEN TWO CHANNEL CHECKS, PUT TO SLEEP MODE  I NTERVAL MUST BE SHORTER THAN RTS TRANSMISSION TIME / 17 RTS Channel check RTS Channel check RTS Channel check (a)(b) (c) Executed channel check Canceled channel check

C ONVERGENT MAC  A GGRESSIVE RTS  A NYCAST PACKET FORWARDING  C ONVERGENT FORWARDING

A NYCAST PACKET FORWARDING  N ODES OTHER THAN TARGET RECEIVER MAY  W AKE UP EARLIER  C AN MAKE SOME PROGRESS TOWARD SINK  R EDUCE LATENCY  A NYCAST TO THE ONE CLOSEST TO DESTINATION  F ORWARDING SET  N EIGHBOR NODES OF THE SENDER THAT ARE CLOSER TO THE DESTINATION  P ARTITION INTO 3 SUB REGIONS / 17

A NYCAST PACKET FORWARDING  M ORE THAN ONE NODE MAY CONTEND TO SEND CTS  E ACH GAP BETWEEN TWO CONSECUTIVE RTS IS DIVIDED  3 CTS SLOTS FOR (R1, R2, R3)  P RIORITIZE THE CTS PACKET TRANSMISSION  E ACH CTS SLOT DIVIDED INTO MINI - SLOTS  E ACH NODE IN THE SAME REGION RANDOMLY PICKS UP A MINI - SLOT / 17 Canceled RTS CTS RTS Sender CTS slot Canceled CTS mini-slot Node in R 1 Node in R 2 Node in R 3 Canceled CTS

C ONVERGENT MAC  A GGRESSIVE RTS  A NYCAST PACKET FORWARDING  C ONVERGENT FORWARDING

C ONVERGENT FORWARDING  A NYCAST HAS HIGHER OVERHEAD THAN UNICAST  S UBOPTIMAL ROUTES  A NYCAST RTS/CTS  S WITCH FROM ANYCAST TO UNICAST IF  N ODE IS ABLE TO COMMUNICATE WITH A NODE IN R1  C ANNOT FIND A BETTER NEXT HOP THAN CURRENT ONE  N ODES STAY AWAKE FOR A SHORT DURATION AFTER RECEIVING A PACKET  S YNCHRONIZED WAKE - UP SCHEDULING  T IMEOUT / 17

C ONVERGENT FORWARDING / 17

E XPERIMENTS  T ESTBED : KANSEI TESTBED  105 XSM NODES  7 X 15 TOPOLOGY, SEPARATION OF 3 FEET  I MPLEMENTATION PARAMETERS / 17 CTS-slot length7.488 ms Number of CTS-slots3 Mini-slot length416 μs Number of mini-slots6 RTS packet size44 bytes Double channel check interval10 ms

E XPERIMENTS  M ETRICS  T HROUGHPUT  L ATENCY  N ORMALIZED ENERGY CONSUMPTION  S CENARIOS  S TATIC EVENT  M OVING EVENT  C OMPARISON  CMAC 1%, BMAC 1%  CMAC 100%, BMAC 100% / 17

E XPERIMENTS – STATIC SCENARIO / 17 ThroughputLatencyEnergy Consumption

E XPERIMENTS - MOVING SCENARIO / 17 ThroughputLatencyEnergy Consumption

S IMULATION / 17 ThroughputLatencyEnergy Consumption

C ONCLUSION  CMAC  AGGRESSIVE RTS, ANYCAST, CONVERGENT PACKET FORWARDING  S UPPORTS HIGH THROUGHPUT, LOW LATENCY AND CONSUMES LESS ENERGY THAN EXISTING SOLUTIONS  D ISCUSSION  N O CONSIDERATION OF NODE MOBILITY  A WAKE DURATION AFTER RECEIVING PACKET IS SENSITIVE TO PERFORMANCE  F OR LOW DATA RATES, CAN ’ T CONVERGE FROM ANYCAST TO UNICAST  T OO SIMILAR WITH XMAC / 17

Thank You # 17 CS

Appendix # 17 CS

 H OW LONG SHOULD NODES KEEP AWAKE AFTER RECEIVI NG A PACKET ?  L ONGER AWAKE PERIOD → LOWER LATENCY  B UT LONGER AWAKE PERIOD MAY NOT BE MORE ENERGY EFFICIENT  D EPENDENT ON DATA RATE AND NODE DENSITY lambda: packet arrival rate in a Poisson arrival process

25  P ERFORMANCE OF ANYCAST IF LACK OF CONVERGENCE  E XPERIMENT SETTINGS :  V ARY TRANSMISSION RANGES TO CREATE DIFFERENT NODE DENSITI ES  M ETRIC :  L ATENCY NORMALIZED BY DISTANCE ( HOPS IN UNICAST )  R ESULTS :  CMAC 1% ACHIEVES LOWER LATENCY THAN BMAC 1%