Efficient Minimization of Routing Cost in Delay Tolerant Networks

Transcription

1 Computer Science Department Christos Tsiaras Master Thesis Presentation (short edition) Efficient Minimization of Routing Cost in Delay Tolerant Networks Supervised by Dr. Stavros Toumpis Zürich, 20 July 2011

2 Outline What are and how to model DTNs (focus on Deterministic DTNs) Why minimize routing cost in DTNs Our approach through a simple example Performance Potential uses Q & A Time Slide 1 of 26

3 What are DTNs Basic characteristics All nodes in DTNs can and should store data Efficient data forward Examples Military ad hoc networks Sensor networks Satellite networks Slide 2 of 26

4 How to model a DTNs Slide 3 of 26

5 Deterministic DTNs Full knowledge of network evolution Known every time slot Known connectivity every time slot Known storage cost for every every time slot Transmission cost for every possible link Slide 4 of 26

6 Why minimize routing cost in DTNs Nodes => Routing cost Time slots => Routing cost DTNs can be very patient consider forward data DTNs can be very impatient consider routing decisions Slide 5 of 26

7 Our approach through a simple example Slide 6 of 26

8 Our approach through a simple example Slide 7 of 26

9 Our approach through a simple example Slide 8 of 26

10 Our approach through a simple example Slide 9 of 26

11 Our approach through a simple example Slide 10 of 26

12 Our approach through a simple example Slide 11 of 26

13 Our approach through a simple example Slide 12 of 26

14 Our approach through a simple example Slide 13 of 26

15 Our approach through a simple example Slide 14 of 26

16 Performance Simple Dijkstra implementation O (T 2 V 3 net ) O (T 2 V 2 net ) many to many one to many Recursive use of Dijkstra O (T V 3 net ) many to many O (T V 2 net ) one to many Simple Bellman-Ford O (T 2 V 4 net ) O (T 2 V 3 net ) many to many one to many Recursive Bellman-Ford O (T V 4 net ) O (T V 3 net ) many to many one to many Slide 15 of 26

17 Performance Slide 16 of 26

18 Performance Slide 17 of 26

19 Performance Slide 18 of 26

20 Performance Slide 19 of 26

21 Performance Slide 20 of 26

22 Potential uses Distributed scenario Recursive Dijkstra Airplanes network! Shortest paths precalculation about black box data exchange between planes Most of the Black box data reach the ground even if plane does not! Slide 21 of 26

23 Potential uses Distributed scenario Recursive Bellman-Ford Distributed data replication Replicate data with minimum cost Maybe someone want to pay to transfer the trafic through his network (information?) Slide 22 of 26

24 Potential uses Centralised scenario Recursive Dijkstra WSN Plant smart nodes and create a backbone for the WSN e.g. Runners Protocol Slide 23 of 26

25 Demonstration of our implementation This is the fun part Slide 24 of 26

26 Demonstration of our implementation Question: Find the minimum cost journey, so node 1 will send data to node 10 at a 21 maximum number of time slots Answer: Node 1 will store data for 8 time slots where he will forward the data to node 8 Node 8 will store data for 4 time slots where he will meet node 10 and he will deliver the data Data will reach node 10 in 12 time slots All nodes will continue travelling untill time slot 21 Slide 25 of 26

27 Conclusions Every DTN should be handled with different routing algorithm Distributed and Centralised routing decisions should be possible Fast calculation of the optimal routing path is mandatory Slide 26 of 26

28 Q & A Time This presentation can be found at