A Distance Routing Effect Algorithm for Mobility (DREAM)* Stefano Basagni Irnrich Chlamtac Violet R. Syrotiuk Barry A. Woodward

Outline Introduction DREAM -Dissemination of Location Information -A model of DREAM -DREAM procedure Simulations and Results Conclusion

Introduction Old problem for Ad hoc network routing: -Proactive: it corresponds to a next hop table lookup, sequence is not explicit; -Reactive: the movement of any node in the sequence renders the path invalid. A new definition of routing table entry is needed

Dissemination of Location Information (DREAM) Each node transmits control messages bearing its current location to all the others. (e.g. geographic coordinates; obtained by the use of GPS [7]) The frequency with which these control messages is determined by: -distance effect -mobility rate

Dissemination of Location Information (control message) We assign each control packet a life time A majority of the packets have a “short” life time: short lived packets are sent at high frequency, and “die” after they have traveled. Long lived packets, sent less frequently, travel farther through the network.

A Model for DREAM S sends a message to node R, it refers to its LT (Location Table) in order to retrieve location information about R. S selects from among its neighbors those nodes that are in the direction of R It is guaranteed that R can be found with a given probability p, 0< p <1, following result in that direction.

A Model for DREAM The time interval from t0 to tl, tl > t0 x = (tl – t0)v Node R, whose speed is v, cannot be anywhere outside the circle C one hop neighbors those nodes A, direction A. lies within the range [θ- α, θ+ α] Angle α must be chosen in a way that the probability of finding R in the sector S is at least p. we want to find a minimum value for α

A Model for DREAM (method of finding α)-1

A Model for DREAM (method of finding α)-2

Distance Routing Effect Algorithm for Mobility (DREAM procedure)

Distance Routing Effect Algorithm for Mobility (DREAM procedure: Recovery) Its actual implementation may vary, depending on the characteristic of the network. For instance, flooding

Simulations Results Simulated our DREAM protocol using MAISIE [1] Placing n = 30 nodes randomly on a grid of size 100 x 100. we assume that each node has the same speed V given in grid units per 100 ticks of the simulation clock average end-to-end delay

Conclusions Simulation results showed that with over 80% probability this method can find a route to a given node. (if any exists) The average end-to-end delays with respect to the DSR reactive protocol are lower. DREAM protocol provides loopfree routes, and is robust in providing multiple routes.