1. An efficient reliable broadcasting protocol for wireless mobile ad hoc networks Chih-Shun Hsu, Yu-Chee Tseng, Jang-Ping Sheu Ad Hoc Networks 2007, vol. 5, no. 3

2. 2 Outline Introduction Efficient reliable broadcasting protocol Simulation Conclusions

3. 3 Introduction Reliable broadcast is an important operation in MANET  Searching routes  Notifying important signals

4. 4 Introduction Flooding  Redundant rebroadcasts  Contention  Collision  Congestion  Broadcast storm problem

5. 5 Introduction Existing protocols  Unreliable  Reliable but based on a too costly approach

6. 6 Goal Proposed an efficient reliable broadcasting protocol  Low-cost broadcast  Guarantee reliability Additional acknowledgement Handshaking

7. 7 Efficient reliable broadcasting protocol Mobile hosts number ： n Single common channel Collecting a global topology of the MANET is prohibitive

8. 8 Efficient reliable broadcasting protocol Scattering phase Gathering phase Purging phase

9. 9 Efficient reliable broadcasting protocol C(id): a counter to keep track of the number of times M is heard Par(id): an ordered list of hosts serving as x’s parents in the upstream gathering tree T ack (id): the acknowledgement timer for M

10. 10 Efficient reliable broadcasting protocol C th : the counter threshold T hand : the handshake timer hand_req: handshake request bit

11. 11 Efficient reliable broadcasting protocol Broadcast history  stable_id[1…n]  unstable_msg  unstable_id  unstable_ack

12. 12 Efficient reliable broadcasting protocol B(M, id): broadcast packet, with content M and identity id. ACK(id, v): acknowledgement packet, for message id with acknowledgement vector v. NACK(H.unstable_id): negative acknowledgement. HAND(H.stable_id[1…n],H.unstable_id,H. pending_ack): handshake packet. PURGE(id): to notify all hosts that message id has stabilized.

13. 13 Scattering phase  Counter-based scheme C B A C(A)=1 Par(A)={A} C(A)=2 Par(A)={A,B}

14. 14 Scattering phase H3 H1 H2 H6 H9 H8 H4 H5 H7 H10 C th =2

15. 15 Scattering phase

16. 16 Gathering phase A host which has heard the broadcast message should return an ACK packet to the source. According to the sequence Par(id) No host in Par(id) is available  Appended to H.pending_ack

17. 17 Gathering phase pending_ack

18. 18 Gathering phase T hand expiring  HAND(H.stable_id, H.unstable_id, H.pending_ack)

19. 19 Gathering phase

20. 20 Purging phase When the source host finds that a message (M, id) initiated by itself has stabilized  Broadcasting a PURGE packet to inform all hosts

21. 21 Simulation Setup Transmission radius ： 250 m Area size ： 1000 m*1000 m Transmission rate ： 2M bits/s Beacon interval ： 1 s Pause time ： 30 s Contention window MIN_CW ： 31 and MAX_CW ： 1023 Retry limit ： 5 T hand ： 1 s T ack ： MAX_CW*ST

22. 22 Simulation Setup Five parameters are tunable in our simulations:  Counterthreshold ： 2–5  Moving speed of hosts ： 0–20 m/s  Broadcast rate ： Broadcasts are generated by a Poisson distribution with rate between 1 and 4 broadcasts/s (in the whole network)  Number of hosts ： 50–250  Broadcast packet size ： 256–1024 bytes

23. 23 Reliable broadcast in mobile wireless network  AV protocol The source host broadcasts to all its 1-hop neighbors. Each receiver should return an acknowledgement to the sender. If the sender does not receive an acknowledgement from any neighbor after a certain time interval, it rebroadcasts the message. Using a handshake procedure to exchange their histories.

24. 24 Providing reliable and fault tolerant broadcast delivery in mobile ad-hoc networks  PR protocol Based on a clustering structure Forwarding tree

25. 25 Simulation Results

26. 26 Simulation Results

27. 27 Simulation Results

28. 28 Simulation Results

29. 29 Simulation Results

30. 30 Simulation Results

31. 31 Simulation Results

32. 32 Simulation Results

33. 33 Simulation Results

34. 34 Simulation Results

35. 35 Simulation Results

36. 36 Simulation Results

37. 37 Simulation Results

38. 38 Conclusions Proposed an efficient reliable broadcast protocol  Counter-based Relieving the broadcast storm effect  Tree-based approach  Handshake mechanism

39. 39 Thank you!