1. Min-Te Sun, Lifei Huang, Anish Arora, Ten-Hwang Lai Presented by Md Tareq Adnan CSE 6590 - High Performance Computer Networks 1

2. Outline  Existing Multicast MAC Protocols  Problems with Existing Multicast MAC Protocols  Batch Mode Multicast MAC protocol, BMMM  Location Aware Multicast MAC protocol, LAMM  Performance Evaluation based on Simulation CSE 6590 - High Performance Computer Networks2

3. IEEE 802.11 multicast/broadcast Protocol  IEEE 802.11 multicast/broadcast protocol is based CSMA/CA  Increased probability of lost frames due to interference or collisions  MAC-level recovery on multicast frame CSE 6590 - High Performance Computer Networks3

4. Solution to unreliable IEEE 802.11 multicast/broadcast protocol  Batch Mode Multicast MAC protocol, BMMM  Reduces the number of contention phases  Reduces the time required for a multicast/broadcast  Location Aware Multicast MAC protocol, LAMM  Uses node Geo location  Further improve upon BMMM. CSE 6590 - High Performance Computer Networks4

5. Overview on CSMA/CA  A node before transmit listens to the medium  Backoff timer  Contention phase  Hidden terminal problem  Distributed Coordination Function (DCF) MAC protocol CSE 6590 - High Performance Computer Networks5

6. Existing Multicast MAC Protocols and Problems cont…  In IEEE 802.11  RTS/CTS / ACK is not used for broadcast/multicast  Protocol in [19]  Introduce RTS/CTS handshake  WAIT_FOR_CTS  WAIT_FOR_DATA  Problems  Collision of CTS frames  Short inter-frame spacing (SIFS)  Direct Sequence (DS) capture ability  Contention window [0,w] CSE 6590 - High Performance Computer Networks6

7.  Broadcast Support Multiple Access (BSMA)  Introduce NAK Frame  WAIT_FOR_NAK  Problem  Collision of NAK Frame CSE 6590 - High Performance Computer Networks7 Existing Multicast MAC Protocols and Problems cont…

8.  Broadcast Medium Window (BMW)  Each broadcast is treated as multiple unicast requests  Each node maintains three lists  NEIGHBOR  SEND BUFFER  RECEIVER BUFFER  Problems  Requires at least n contention phases for each multicast  Long time for multicast process lead to time out CSE 6590 - High Performance Computer Networks8 Existing Multicast MAC Protocols and Problems cont…

9. BMMM reduces multicast time compared with BMW Reduces n contention phases into one CSE 6590 - High Performance Computer Networks9

10. BMMM Provides Simple Coordination  Prevent neighbors from passing contention phase  RTS frame tells to transmit CTS sequentially  RAK frame tells to transmit ACK sequentially CSE 6590 - High Performance Computer Networks10

11. Why use BMMM  Greatly reduces the number of contention phases  No modification on control frame format  Co-exist with IEEE 802.11 protocols CSE 6590 - High Performance Computer Networks11

12. Batch Mode Multicast MAC Protocol(BMMM) CSE 6590 - High Performance Computer Networks12

13. Location Aware Multicast MAC Protocol(LAMM)  GPS location information  A subset S’ of S will be a cover set if A(S)=A(S’). 1. Sender receives an ACK from every node in S’ Receiver guaranteed to receive data frame without collision CSE 6590 - High Performance Computer Networks13

14. Location Aware Multicast MAC Protocol(LAMM) 2. Minimum cover set of S can be computed in O(n^4/3) time 3. Every receiver is guaranteed to receive the data frame without collision if the transmission area of a node is completely covered by the transmission areas of a set of nodes CSE 6590 - High Performance Computer Networks14

15. Cover Angle  If two nodes are at the same location, cover angle is [0,360]  If two nodes are R away, cover angle is Ø  Transmission area of p, A(p) is completely covered by C CSE 6590 - High Performance Computer Networks15

16. Why use LAMM  LAMM protocol is refinement of the BMMM protocol  US FCC has requested all wireless service carriers to provide 911 calls CSE 6590 - High Performance Computer Networks16

17. Expected number of contention phases before data sent CSE 6590 - High Performance Computer Networks17

18. Successful Delivery Rate CSE 6590 - High Performance Computer Networks18

19. CSE 6590 - High Performance Computer Networks19 Successful Delivery Rate

20. Average Number of Contention Phases CSE 6590 - High Performance Computer Networks20

21. Average Message Completion Time CSE 6590 - High Performance Computer Networks21

22. A Pointer to Future Work  Focus was to resolve the hidden terminal problem for multicast  Has not addressed the exposed terminal problem CSE 6590 - High Performance Computer Networks22

23. Thank You CSE 6590 - High Performance Computer Networks23