1. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 1 Reliable Multicast in Multi- Access Wireless LANs Speaker : Chi-Wen Yang Advisor : Kai-Wei Ke Date : 2007/05/07

2. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 2 Reference UPKAR VARSHNEY, Multicast Over Wireless Networks. Communications of the ACM, Vol. 45, No. 12(Dec. 2002), 31–37. JOY KURI and SNEHA KUMAR KASERA, Reliable Multicast in Multi-Access Wireless LANs, Kluwer Academic Publishers., 2001, 359–369.

3. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 3 Outline Multicast Overview Multicast Over Wireless Network Reliable Multicast in Multi-Access Wireless LANs Summary

4. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 4 Outline Multicast overview Multicast Over Wireless Network Reliable Multicast in Multi-Access Wireless LANs Summary

5. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 5 Multicast overview Multicast is the delivery of information to a group of destinations simultaneously using the most efficient strategy to deliver the messages over each link of the network only once, creating copies only when the links to the destinations split. Multicast is defined in RFCs 966, 988, 1054, and 1112.

6. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 6 Multicast overview A multicast application can be characterized as one of three types:  One-to-Many  Many-to-Many  Many-to-One.

7. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 7 Multicast overview One-to-Many multicast transmission from a single host to all intended recipient hosts. The sender dispatches a multicast packet addressed to the multicast group of receivers.

8. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 8 Multicast overview Many-to-Many multicast transmission from two senders to all intended recipient hosts. The senders dispatch multicast packets addressed to the multicast group of receivers.

9. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 9 Multicast overview Many-to-one multicast transmission from two senders to a single receiver. The senders dispatch multicast packets addressed to the multicast group of receivers. In the illustrated example above, the group consists of a single host.

10. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 10 Multicast overview Multicast protocols :  Internet Group Management Protocol (IGMP)  Protocol Independent Multicast (PIM)  Distance Vector Multicast Routing Protocol (DVMRP)  Multicast BGP (MBGP)  Multicast Source Discovery Protocol (MSDP)  Multicast Listener Discovery (MLD)  GARP Multicast Registration Protocol (GMRP)

11. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 11 Multicast overview Multicasting has been implemented using Mbone. Mbone (short for "multicast backbone") is an experimental backbone for IP Multicast traffic across the Internet. IGMP 、 Multicast Router and IP tunnel DVMRP 、 PIM-DM 、 PIM-SM and MOSPF in MBone

12. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 12 Multicast overview IP multicast support in the MBone using tunneling.

13. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 13 Multicast overview A multicast can be divided into two mode:  Sparse Mode (PIM-SM)  Dense Mode (DVMRP)

14. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 14 Multicast overview Example for Multicast working. Multicast source, routers, and receiver group, showing the network segments that form the multicast path between them as red arrows.

15. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 15 Outline Multicast overview Multicast Over Wireless Network A New Multicast Routing Protocol Based on Autonomous Clustering in Ad Hoc Networks Summary

16. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 16 Multicast Over Wireless Network Problem of mobility in wireless :  Loss of packets  Incorrect routing  Discard multicast packets  Transmission range limited  Dynamic connectivity  Group membership management

17. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 17 Multicast Over Wireless Network Qualitative comparison of wired and wireless multicast.

18. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 18 Multicast Over Wireless Network Multicast Routing for Infrastructure-based Wireless Networks:  DVMRP  MOSPF  PIM  PIM-SM Multicast Routing for Ad Hoc Wireless Networks:  MAODV (tree-based)  ODMRP (meshed-based)  CAMP (meshed-based)  AMRoute (hybrid)  AMRIS (tree-based)

19. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 19 Multicast Over Wireless Network Multicast routing protocols is classified into three categories:  Multicast routing using a tree (tree-based)  Multicast routing using mesh (mesh-based)  Multicast routing using other structures (stateless and hybrid)

20. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 20 Multicast Over Wireless Network Multicast routing using a tree  Use source based route between souces and receivers, there is only one route path for any pair source  Route update in one of three ways: Store and update Delete all and refresh Unicast protocol support  A multicast tree is subject to disruption due to link/node failure and node mobility.

21. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 21 Multicast Over Wireless Network Multicast routing using mesh:  Use multiple redundant routes for rubost handling of link failure and node mobility during a multicast session.  It may have looping problem. Multicast routing using other structures:  Multicast routing provides stateless topology- independent routing.  Forwarding packets in many directions and functioning independent of topology.

22. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 22 Multicast Over Wireless Network Multicast routing in ad hoc wireless networks.

23. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 23 Multicast Over Wireless Network Reliable in Wireless Multicast:  Packet loss can be detected through one of two approaches: Sender-initiated –Receivers return ACK for correctly received packets. Receiver-initiated –NAK are used by receivers to inform the sender about packet loss.

24. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 24 Outline Multicast overview Multicast Over Wireless Network Reliable Multicast in Multi-Access Wireless LANs Summary

25. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 25 Top view of the system, showing bases, terminals, the shared wireless channel in each cell and the wired interconnection between bases. Reliable Multicast in Multi-Access Wireless LANs

26. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 26 Two important issues:  The problem of the sender acquiring the multi-access channel for multicast transmission.  For reliable multicast in each cell of the wireless LAN, we examine ARQ-based approaches. The second issue is important because the wireless link error can be very high. Reliable Multicast in Multi-Access Wireless LANs

27. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 27 There are significant differences between the wired and wireless LAN transmission media.  CSMA/CD in wired LAN.  RTS/CTS in wireless LAN. Reliable Multicast in Multi-Access Wireless LANs

28. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 28 Hidden Terminal. Reliable Multicast in Multi-Access Wireless LANs

29. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 29 RTS/CTS/data/ACK and NAV setting Reliable Multicast in Multi-Access Wireless LANs

30. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 30 Three generic protocols:  Leader-based protocol (LBP)  Delayed feedback-based protocol (DBP)  Probabilistic feedback-based protocol (PBP) Reliable Multicast in Multi-Access Wireless LANs

31. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 31 Leader-based protocol:  Base→Receivers (Slot 1). Send multicast-RTS.  Receivers→Base (Slot 2). Leader: If ready to receive data, send CTS. If not ready to receive data (e.g., due to insufficient buffers), do nothing. Others: If ready to receive data, do nothing. If not ready to receive data, send NCTS (Not Clear to Send)1. Reliable Multicast in Multi-Access Wireless LANs

32. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 32  Base→Receivers (Slot 3). If a CTS was heard in slot 2, start multicast transmission. If no CTS was heard in slot 2, back off and go to step A. The next step is executed only when multicast transmission occurs in step C.  Receivers→Base (Slot (l + 3)). Leader: If packet received without error, send ACK. If in error, send NAK. Others: If packet received without error, do nothing. If in error, send NAK. Reliable Multicast in Multi-Access Wireless LANs

33. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 33 Delayed feedback-based protocol:  Base→Receivers. 1. Send multicast-RTS. 2. Start a timer (timeout period T ), expecting to hear a CTS before the timer expires.  Receivers→Base. 1. On hearing RTS, start timer with an initial value chosen randomly from {1, 2,...,L}. 2. Decrement timer by 1 in each slot. 3. If a CTS is heard before timer expires, freeze timer (CTS suppression). If no CTS is heard before timer expires, send CTS. Reliable Multicast in Multi-Access Wireless LANs

34. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 34  Base→Receivers. If no CTS is heard within T, back off and go to step A. If a CTS is heard within T (at a random time), start data transmission. After finishing transmission, prepare to transmit next packet and go to step A (no waiting for feedback). The next step is executed only when multicast transmission occurs in step C.  Receivers→Base. If packet received without error, do nothing. If in error, contend for the channel to send NAK. Reliable Multicast in Multi-Access Wireless LANs

35. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 35 Probabilistic feedback-based protocol: PBP is similar to DBP with one difference. The receivers in PBP could send NCTS if they are not ready. Reliable Multicast in Multi-Access Wireless LANs

36. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 36 Comparison of the three protocols:  A successful RTS-CTS exchange, DBP and PBP would take longer than LBP.  The buffer requirements in DBP is higher both at the base-station and receivers.  A problem with DBP and PBP is the choice of right parameters for waiting times and probability of sending feedback. Reliable Multicast in Multi-Access Wireless LANs

37. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 37 There are two ways in which hidden terminal can affect the operation of LBP:  The first occurs then there is a collision during the control packet exchange.  The second way in which multicast transmission can be affected occurs when there is a collision affecting the multicast data. The second is the same holds true for the other protocols DBP and PBP. Reliable Multicast in Multi-Access Wireless LANs

38. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 38 Compare the performance of LBP, DBP and PBP:  It’s evidently in favor of DBP and PBP since no retransmissions are necessary.  DBP have a shorter mean access period than PBP.  The performance of LBP is better than the best performance achievable with DBP. Reliable Multicast in Multi-Access Wireless LANs

39. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 39 Variation of ph with L, keeping N and T fixed. Reliable Multicast in Multi-Access Wireless LANs

40. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 40 Performance of DBP:  The probability that the base hears a CTS within time T:  The time that the base spend in the access period:  The mean time spent in the access period: Reliable Multicast in Multi-Access Wireless LANs

41. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 41 Performance of PBP:  The probability that the access period lasts 2 slots:  The mean time spent in the access period: Reliable Multicast in Multi-Access Wireless LANs

42. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 42 Comparison of the expected time spent in the access period under DBP and PBP. Reliable Multicast in Multi-Access Wireless LANs

43. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 43 Cost under DBP versus cost under LBP:  The cost of a packet under DBP:  The cost of a packet transmission under LBP: Reliable Multicast in Multi-Access Wireless LANs

44. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 44 Events on the error-free channel; DBP. Events on the error-free channel; protocol LBP. Reliable Multicast in Multi-Access Wireless LANs

45. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 45 Comparison of packet transmission costs under DBP and LBP; C = 20. Reliable Multicast in Multi-Access Wireless LANs

46. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 46 Outline Multicast overview Multicast Over Wireless Network Reliable Multicast in Multi-Access Wireless LANs Summary

47. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 47 Summary The leader-based protocol provides very efficient solutions to the CTS and ACK/NAK collision problems. It is very simple to implement. It can be potentially integrated with the current wireless LAN.

48. 2007/05/07 無線與寬頻網路實驗室 台北科技大學資訊工程系所 48 THE END Q and A