A Distance RoutingEffect Algorithm for Mobility
(DREAM)*
Stefano BasagniIrnrich ChlamtacViolet R. SyrotiukBarry 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)
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.
