Fast and Slow Hopping MAC Protocol for Single-hop Ad Hoc Wireless Networks Khaled Hatem Almotairi, Xuemin (Sherman) Shen Department of Electrical and Computer Engineering University of Waterloo200 University Avenue West Waterloo, Ontario, Canada IEEE ICC 2011

Outline Introduction System model Dynamic channel assignment using fast and slow hopping Simulation Conclusion

Introduction Network performance of ad hoc networks is limited due to the interference among nodes

Introduction Many schemes and technologies have been proposed to improve the network performance – Smart antennas – Multiple channels

Introduction Multi-channel medium access control protocol – Single rendezvous (SR) – Multiple rendezvous (MR)

Introduction SR multi-channel MAC – Channel hopping – Split phase – Control/data channel

Introduction- Channel hopping Channel-hopping multiple access – ICC 2000 Ch1 Ch2 Ch4 Ch5 Ch6 Ch3 AB C AB C AB C AB C AB C AB C Hopping sequence : 1,3,5,2,4,6… ABABAB

Introduction- Channel hopping The drawbacks – Time synchronization is required – Performing broadcast is difficult – Busy receiver problem

Introduction- Split phase Multi-channel mac for ad hoc networks: (MMAC) – HobiHoc 2004 Beacon Interval Time Beacon Interval ATIM WindowData Window

Introduction- Split phase The drawbacks – Time synchronization is required – Low channel utilization

Introduction- control/data channel A new multi-channel mac protocol with on- demand channel assignment for multi-hop mobile ad hoc networks – ISPAN 2000 – DCA

Introduction- control/data channel Control channel A B RTS CTS RES Data channel A B sender receiver Data ACK Time

Introduction- control/data channel The drawbacks – Control channel congestion – Control channel is needed Only use for control packet

Goal Propose a novel multi-channel MAC protocol – Based on frequency hopping Avoid congestion Utilization of multiple channels – Multiple rendezvous

System model n nodes k channels with equal bandwidth Single hop Synchronized Two half-duplex interfaces can work simultaneously – Fast hopping – Slow hopping

Dynamic channel assignment using fast and slow hopping Hopping control Discovery Rendezvous Broadcast

Dynamic channel assignment using fast and slow hopping Hopping control – Slow hopping – Fast hopping

Dynamic channel assignment using fast and slow hopping Discovery & Rendezvous A fastslow Ch2 Ch5 Ch3 Ch4 Ch1 Ch6 Ch8 Ch7 … Ch4 Ch1 Ch8 Ch5 Ch7 Ch6 Ch3 Ch2 … HELLO 1.seed of the slow hopping sequence 2.Local clock time 3.Remain time to the next channel

Dynamic channel assignment using fast and slow hopping Discovery & Rendezvous A fastslow Ch2 Ch5 Ch3 Ch4 Ch1 Ch6 Ch8 Ch7 … Ch4 Ch1 Ch8 Ch5 Ch7 Ch6 Ch3 Ch2 … B fastslow Ch1 Ch6 Ch3 Ch8 Ch5 Ch2 Ch7 Ch4 … Ch3 Ch8 Ch2 Ch1 Ch6 Ch7 Ch4 Ch5 … DATA

Dynamic channel assignment using fast and slow hopping Discovery & Rendezvous A fastslow Ch3 Ch8 Ch2 Ch1 Ch6 Ch7 Ch4 Ch5 … Ch4 Ch1 Ch8 Ch5 Ch7 Ch6 Ch3 Ch2 … B fastslow Ch1 Ch6 Ch3 Ch8 Ch5 Ch2 Ch7 Ch4 … Ch3 Ch8 Ch2 Ch1 Ch6 Ch7 Ch4 Ch5 … DATA RTSCTS ACK

Dynamic channel assignment using fast and slow hopping Discovery & Rendezvous A fastslow Ch2 Ch5 Ch3 Ch4 Ch1 Ch6 Ch8 Ch7 … Ch4 Ch1 Ch8 Ch5 Ch7 Ch6 Ch3 Ch2 … B fastslow Ch1 Ch6 Ch3 Ch8 Ch5 Ch2 Ch7 Ch4 … Ch3 Ch2 Ch8 Ch1 Ch6 Ch7 Ch4 Ch5 … DATA

Dynamic channel assignment using fast and slow hopping Broadcast – Broadcast packet is transmitted through both interfaces Reliability

Simulation

Simulation result G. Bianchi, “Performance analysis of the IEEE distributed coordination function,” IEEE Journal on Selected Areas in Communications, vol. 18, no. 3, pp. 535–547, March 2000.

Conclusion The authors proposed a novel multi-channel MAC protocol – Based on fast and slow hopping – Multiple rendezvous approach – Busy receiver problem cloud be eliminated Simulation result shows that our protocol demonstrate the improvement in the capacity of the networks

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