A Distance RoutingEffect Algorithm for Mobility

(DREAM)*

Stefano BasagniIrnrich ChlamtacViolet R. Syrotiuk

Barry A. Woodward

Outline

• Introduction• DREAM -Dissemination of Location Informat

ion -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 anyw

here outside the circle C• one hop neighbors those nodes A, directi

on 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)

Distance Routing Effect Algorithmfor 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.