1. Virtual Wire for Managing Virtual Dynamic Backbone in Wireless Ad Hoc Networks Bo Ryu, Jason Erickson, Jim Smallcomb ACM MOBICOM 1999

2. Outline Introduction The Concept Notation and Basic Rules Management of VDB Backbone Selection Process (BSP) Backbone Connection Process (BCP) Backbone Maintenance Process (BMP) Routing Unicasting Multicasting Conclusion

3. Introduction A novel distributed algorithm Employs the concept of virtual wire Its structure was called virtual dynamic backbone (VDB) reliable and scalable routing in wireless mobile ad hoc networks The requirements Unicast routing Multicast routing QoS routing Low overhead Reliability Scalability

4. The Concept (1/6) Virtual Dynamic Backbone (VDB)

5. The Concept (2/6) The advantages provided by VDB include:

6. The Concept (3/6) Virtual Wire Messages (VWMs)

7. The Concept (4/6) Virtual Wire Messages (VWMs) Rate r Example: Let r = 0.1 VWM/sec Node 4 and 5 transmit VWMs rate is 8r VWMs size = 20 bytes Bandwidth overhead = 128 bits/sec 20 x 8 x 8 x 0.1 = 128 bits/sec

8. The Concept (5/6) Virtual Handoff 6

9. The Concept (6/6) Virtual wire brings several key benefits:

10. Notation and Basic Rules(1/4) Three types of nodes: Black => VDB node Green => at least one black node as its neighbor White => no black node as its neighbor LQ ab link quality from node a to node b  (v) The number of neighbors of node v Each node generates Virtual Wire Messages Virtual Attachment Point (VAP) Black or green has at least one Connect to VDB via VAP

11. Notation and Basic Rules(2/4) A VWM contains the following fields: Source Node ID (S) Forwarding Node ID (F) VAP Link Quality Node ID (N) Link Quality Feedback (LQ) Hop Count (HC) Time-to-Live (TTL) Source Sequence Number Transmitter Sequence Number Color (c) Degree(  )

12. Notation and Basic Rules(3/4) For example:

13. Notation and Basic Rules(4/4)

14. Management of VDB(1/3) Backbone Selection Process (BSP)  Backbone Selection Process (BSP)  Backbone Connection Process (BCP)  Backbone Maintenance Process (BMP)

15. Management of VDB(2/3) Backbone Connection Process (BCP)  Backbone Selection Process (BSP)  Backbone Connection Process (BCP)  Backbone Maintenance Process (BMP)

16. Management of VDB(3/3) Backbone Maintenance Process (BMP)  Backbone Selection Process (BSP)  Backbone Connection Process (BCP)  Backbone Maintenance Process (BMP)

17. Routing(1/8) Unicasting

18. Routing(2/8) Unicasting

19. Routing(3/8) Multicasting

20. Routing(4/8) Multicasting

21. Routing(5/8) Multicasting

22. Routing(6/8) Multicasting

23. Routing(7/8) Multicasting

24. Routing(8/8) Multicasting

25. Conclusion This architecture is suitable for highly dynamic wireless ad hoc networks The algorithm combines: virtual wire virtual dynamic backbone The algorithm provides: Unicast routing Multicast routing Future work Extensive simulation for evaluating its performance under  various topology  Node mobility scenarios

26. The related issues Overhead Routing sub-optimality Redundancy Scalability QoS support Asymmetric routing