1. Supporting Groupware in Mobile Networks Idit Keidar, Technion – I.I.T Joint work with N. Lavi and I. Cidon

2. Agenda Motivation for mobile groupware Current solutions Our proposed architecture Group management- one solution Simulation and analysis Future work Conclusions

3. Current Application Trends Groupware and collaborative applications are widely used.  Chat, Instant-Messaging, VoIP, VCoIP, Net-meeting  Exchange, Lotus notes, webex  Multiplayer interactive games  Push-to-talk (PTT)

4. Current Cellular Trends Simple groupware such as Instant Messaging widely used Major cellular providers (Orange, Verizon, Nextel) offer PTT services The Yankee Group (Sep. 2003):  In 2003, $84 million PTT revenue, 2.3 million PTT subscribers  By 2008, $10.1 billion PTT revenue, 340 million PTT subscribers

5. Future Cellular Trends Richer groupware applications  Data+ voice+ video Adopting TCP/IP infrastructure  Session Initiation Protocol (SIP) signaling  OMA, 3GPP, 3GPP2 standards

6. Wireless Networks Trends Maturing standards (Wi-Fi, WiMAX) High availability of hot spots Supported in PDAs, Pocket PCs, laptops, and cellular-phones Emerging standards and working groups: IETF-MIP, Open Mobile Alliance, 4G

7. Mobile Networks Trend Groupware popularity + Wireless access availability B3G Convergence Cellular going IP +

8. The Future Network IP based

9. Mobile Groupware Design Goals Mapping group names to subscribers Mobility support Seamless handoff QoS support for RT applications Transport efficiency Transport reliability Roaming, AAA Scalable Support for incremental deployment

10. Previous Solutions: Mobile IP RFC 3344  The standard for seamless mobility  Unicast sessions only  Dependence on a single home  Triangle routing Poor performance and lack of QoS support Inadequate for RT applications Route optimization to 3344  Eliminate triangle routing  Difficult to deploy  Unclear if it can support simultaneous movements

11. Previous Solutions: Cellular OMA PoC working group (cellular operators)  Single server architecture  Large overhead  Triangle routing

12. Our Proposed Solution Mobility and Group Management Architecture [Lavi, Cidon, Keidar MWCN 2004]

13. MaGMA’s Architecture Consists of Mobile-Group Managers (MGMs) and Mobile Nodes (MNs) Version 1: MGMs static and well-known MGM in charge of one or more domains Entering a new domain, MNs obtain IP addresses and contact local MGMs

14. Example: MaGMA Groups Domain-4 Group Blue Group Red

15. Group Management Approaches Subscription model  Sending MN implements multicast  MGMs provide list of subscribers in group  MGMs notify sender of changes join, leave, move (change IP)  Good for lightweight servers, small groups Multicast overlay model  MGMs implement multicast + QoS + reliability using transport-level overlay  Scalable in group size, good for low battery clients

16. Group Management in Subscription Model

17. MaGMA Group View GROUP X

18. MaGMA Group View GROUP X

19. MaGMA Solutions MGMFlood: Flood all events (join, move,…) to all MGMs  Sends unnecessary control messages to MGMs not in group MGMLeader: forward group events only to MGMs participating in the group Less control overhead

20. MaGMA Solution 2:MGMLeader join/move/leave group X join Needs the group’s view Coordinator view

21. View Consistency with Concurrent Joins MGM1 Coordinator MGM2 MGM3 MN1 join MN2 join view Ignor e join(MN1) join(MN2) {MGM2, MGM3} Solution uses a Local Event Counter (LEC) per MGM [2,1,1] [1,1,2] local view {MGM2, MGM3, MGM1} Inconsistent LEC 1 =1 LEC 1 =2

22. Handling Move Goal 1: smooth handoff Goal 2: reduce control overhead  while keeping view consistency group X Coordinator move from MGM1 move view transport tunnel

23. Coordinator Election Need to ensure a single coordinator Need to address coordinator leave See MWCN paper…

24. Some Simulation & Analysis Results

25. Ns2 Simulations & Analysis: MGMFlood vs. MGMLeader Control Overhead Evaluation

26. Simulation: MaGMA vs. MIP Transport Delay MGM1 functions as the HA

27. MaGMA Multicast Overlay Model MGMs organized in overlay Multicast data forwarded over the overlay

28. Ongoing and Future Direction Efficient solutions for multicast overlay model  Keeping MGM-level views not MN-level views  Optimizing overlay, adding QoS support  Mapping groups to optimal servers Fault-tolerance: tolerating MGM failures and dynamic changes Advanced application support

29. Conclusions Wireless networks (Wi-Fi, WiMAX) will merge with the Internet and cellular infrastructure  Converged B3G will be IP-based Users will demand support for real-time (RT) groupware such as PTT Current mobility solutions - inadequate for RT MaGMA can provide comprehensive support for mobility, group management, and QoS