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Juan-Antonio Cordero Philippe Jacquet Emmanuel Baccelli

Orlando, FL -- March 29 th , 2012. 31st Annual IEEE International Conference on Computer Communications. Impact of Jitter-based Techniques on Flooding over Wireless Ad hoc Networks Model and Analysis. Juan-Antonio Cordero Philippe Jacquet Emmanuel Baccelli. Agenda.

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Juan-Antonio Cordero Philippe Jacquet Emmanuel Baccelli

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  1. Orlando, FL -- March 29th, 2012 31st Annual IEEE International Conference on Computer Communications Impact of Jitter-based Techniques on Flooding over Wireless Ad hoc Networks Model and Analysis Juan-Antonio Cordero Philippe Jacquet Emmanuel Baccelli

  2. Agenda • Motivation: Flooding over wireless ad hoc networks • Packet collisions in wireless flooding • The jitter technique for flooding • Framework: goals, assumptions, approach • Main results • Discussion

  3. Motivation Flooding in Wireless Ad hoc Networks • Flooding • Periodic dissemination of messages over the network • Routers participating in flooding: • Create and transmit their own messages • Receive and forward messages from other routers in the network • Example: • Link-state routing: OSPF, OLSR • Other…

  4. Motivation Wireless Ad hoc Networks • Wireless communication • Dynamic and unpredictably changing topology Less available bandwidth More updates required (in routing protocols)

  5. Motivation Wireless Ad hoc Networks • Wireless communication • Dynamic and unpredictably changing topology Less available bandwidth More updates required (in routing protocols) Packet collisions in flooding !

  6. Wireless flooding Packet collisions in flooding B A • Wireless flooding : Stating the problem D C Shared channel (from D) systematic collision A A tx B B rx B tx processing C C rx C tx processing

  7. The jitter technique Jitter for flooding B A • Wireless flooding with jitter | Intuition D C Shared channel (from D) A A tx B B rx B tx processing random delay for B tx C C rx C tx random delay for C tx processing

  8. Received pkt at t=t0 Self-generated msg at t=t1 Scheduled tx at t=t2 Schedule txat t=t1 Assigns a jitter value jto all msgs of the pkt t2=t1 N=1 Send all msgs scheduled and not sent at t=t2 Extracts N-thmsg from the pkt Packet piggybacking Yes N-th msg needs to be forwarded? No  Next N? No Yes Schedule txat t=t0+j The jitter technique Jitter for flooding • Wireless flooding with jitter : RFC 5148

  9. Impact of jitter technique in wireless flooding Main effects • Advantages • Reduction of systematic packet collisions by spreading transmissions • Reduction in the number of transmissions due to piggybacking • Drawbacks • Delay of the flooding operation • Increase of the length of the transmitted packets

  10. In λin Out λout R Self-generated λg Impact of jitter technique in wireless flooding Model and assumptions • System model • Packet arrival ~ punctual, homogeneous Poisson process • Instantaneous packet transmission • All packets received are to be forwarded

  11. Impact of jitter technique in wireless flooding Variables Arrival triggering a collecting phase (in) t0 time t

  12. Impact of jitter technique in wireless flooding Variables Arrival triggering a collecting phase … (in) (in) (in) (in) t1 time t

  13. Impact of jitter technique in wireless flooding Variables Arrival triggering a collecting phase Effective time of transmission … (in) (in) (in) (in) (self) time D(t) ≡ avg length of collecting phase t

  14. Impact of jitter technique in wireless flooding Average duration of collecting phase • ODE • General solution ( D(0) = 0 ; D’(0) = 1 ) • Out-packet rate

  15. Ttx(t) Impact of jitter technique in wireless flooding Variables Arrival triggering a collecting phase Effective time of transmission … G(t) (in) (in) (in) (in) (self) time t

  16. Impact of jitter technique in wireless flooding In-packet delays • Average in-packet cumulated delay before out-packet transmission where • Average forwarding delay for an in-packet

  17. cdf Tj 1 Jm 1/Jm Jm Impact of jitter technique in wireless flooding Some particular results • Packet delays: D(t) , Ttx(t) • Packet rate: λout(λin, λg) , λout(T) Uniformly distributed jitter ( RFC 5148 ) pdf Tj

  18. Impact of jitter technique in wireless flooding Delays before transmission Model results • D(t) ≡ Avg duration of collecting phase • Ttx(t)≡ Avg time of transmission (λin = 4 pkt/sec, λg = 0.2 pkt/sec, Jm = 1 sec) D(t) Ttx(t)

  19. Impact of jitter technique in wireless flooding Out-packet rate Model results • λout≡ Out-packet rate (pkts/sec) (Jm = 1 sec) λin +λg λg = 0.9 λout λg = 0

  20. Impact of jitter technique in wireless flooding Out-packet rate Model results with simulations • λout≡ Out-packet rate (pkts/sec) ( λ in= 4 pkts/sec, λg = 0.2 pkts/sec )

  21. Discussion & Conclusions • RFC 5148 : jitter + piggybacking for flooding (OLSR, OSPF, DYMO…) • Theoretical model : additional delayD(t)vs. packet rate (λout) reduction • Generality of results • Model limitations • Future work • Non-instantaneous packet transmissions ( packet collisions) • More jitter … less collisions ? • Network experimental results

  22. Questions ? E-mail: cordero@lix.polytechnique.fr

  23. Backup slides

  24. Transition equations for D(t) and F(t) • Avg duration of collecting phase • Avg cumulative delay of in-packets arrived within a collecting phase

  25. Some values… • Jitter scale (Friedman, Hay & Kliot, 2009) For Jm = t = 10 msec, λin = 15 pkt/sec, λg = 0,25 pkt/sec, λout = 14,2 pkt/sec(-7%) D(t) = 9,74 msec, Ttx(t) = 8,92 msec (worst case)

  26. References • (Technical Report, 2009) R. Friedman; D. Hay; G. Kliot: Jittering Broadcast Transmissions in MANETs: Quantification and Implementation Strategies. Department of Computer Science, Technion – Institute of Technology of Israel. • (Journal, 2004) C. Adjih; E. Baccelli; T. Clausen; P. Jacquet; G. Rodolakis: Fish Eye OLSR Scaling Properties. In: IEEE Journal of Communications and Networks (JCN), Special Issue on Mobile Ad Hoc Wireless Networks, Volume 6, Number 4, pp. 343-351, IEEE, December 2004. • (Conference, 2003) T. Henderson et al.: A Wireless Interface Type for OSPF, Proceedings of the IEEE Military Communications Conference (MILCOM), pp. 137-145, Boston, MA (United States), October 2003. • (Conference, 1998) J. Broch; D. A. Maltz; D. B. Johnson; Y.-C. Hu; J. Jetcheva: A performance comparison of multi-hop wireless ad hoc network routing protocols, Proc. ACM Annual International Conference on Mobile Computing and Networking (MobiCom’98), pp. 85–97, Dallas, TX (United States), October 1998.

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