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

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 2 Motivation: Flooding over wireless ad hoc networks Packet collisions in wireless flooding The jitter technique for flooding Framework: goals, assumptions, approach Main results Discussion Agenda

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 3 Motivation Flooding in Wireless Ad hoc Networks Flooding Periodic dissemination of messages over the network Routers participating in flooding: 1) Create and transmit their own messages 2) Receive and forward messages from other routers in the network Example: Link-state routing: OSPF, OLSR Other…

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 4 Motivation Wireless Ad hoc Networks Wireless communication Dynamic and unpredictably changing topology Less available bandwidth More updates required (in routing protocols)

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 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 !

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 6 A tx Shared channel (from D) A B B rx processing B tx C C rx processing C tx systematic collision Wireless flooding : Stating the problem A B C D Wireless flooding Packet collisions in flooding

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 7 Wireless flooding with jitter | Intuition A tx Shared channel (from D) A B B rx processing B tx C C rx processing C tx random delay for C tx random delay for B tx The jitter technique Jitter for flooding A B C D

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 8 Packet piggybacking Wireless flooding with jitter : RFC 5148 Self-generated msg at t=t 1 Received pkt at t=t 0 Assigns a jitter value j to all msgs of the pkt N=1 Extracts N-th msg from the pkt N-th msg needs to be forwarded? Schedule tx at t=t 0 +j Scheduled tx at t=t 2 Next N? Send all msgs scheduled and not sent at t=t 2 Schedule tx at t=t 1 t 2 =t 1 Yes No The jitter technique Jitter for flooding

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 9 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 Impact of jitter technique in wireless flooding Main effects

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 10 System model Packet arrival ~punctual, homogeneous Poisson process Instantaneous packet transmission All packets received are to be forwarded R In λ in Self-generated λ g Out λ out Impact of jitter technique in wireless flooding Model and assumptions

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 11 time (in) Arrival triggering a collecting phase Impact of jitter technique in wireless flooding Variables t t0t0

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 12 time (in) … Arrival triggering a collecting phase Impact of jitter technique in wireless flooding Variables t t1t1

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 13 time (in) (self) … (in) D(t) avg length of collecting phase t Arrival triggering a collecting phase Effective time of transmission Impact of jitter technique in wireless flooding Variables

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 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

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 15 time (in) (self) … (in) t Arrival triggering a collecting phase Effective time of transmission Impact of jitter technique in wireless flooding Variables G(t) T tx (t)

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 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

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 17 Impact of jitter technique in wireless flooding Some particular results Uniformly distributed jitter ( RFC 5148 ) Packet delays: D(t), T tx (t) Packet rate: λ out (λ in, λ g ), λ out (T) JmJm 1/J m pdf T j JmJm 1 cdf T j

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 18 Impact of jitter technique in wireless flooding Delays before transmission T tx (t) Avg time of transmission D(t) Avg duration of collecting phase ( λ in = 4 pkt/sec, λ g = 0.2 pkt/sec, J m = 1 sec) Model results D(t) T tx (t)

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 19 Impact of jitter technique in wireless flooding Out-packet rate λ out Out-packet rate (pkts/sec) (J m = 1 sec) λ g = 0 λ g = 0.9 Model results λ out λ in + λ g

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 20 λ out Out-packet rate (pkts/sec) ( λ in = 4 pkts/sec, λ g = 0.2 pkts/sec ) Impact of jitter technique in wireless flooding Out-packet rate Model results with simulations

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 21 Discussion & Conclusions Future work Non-instantaneous packet transmissions ( packet collisions) More jitter … less collisions ? Network experimental results RFC 5148 : jitter + piggybacking for flooding (OLSR, OSPF, DYMO…) Theoretical model : additional delay D(t) vs. packet rate ( λ out ) reduction Generality of results Model limitations

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 22 Questions ?

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 23 Backup slides

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 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

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 25 Some values… Jitter scale (Friedman, Hay & Kliot, 2009) For Jm = t = 10 msec, λ in = 15 pkt/sec, λ g = 0,25 pkt/sec, λ out = 14,2 pkt/sec (-7%) D(t) = 9,74 msec, T tx (t) = 8,92 msec (worst case)

Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding 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 , IEEE, December (Conference, 2003) T. Henderson et al.: A Wireless Interface Type for OSPF, Proceedings of the IEEE Military Communications Conference (MILCOM), pp , Boston, MA (United States), October (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 (MobiCom98), pp. 85–97, Dallas, TX (United States), October 1998.