Yu-Chee Tseng, Jen-Jee Chen, and Yu-Li Cheng National Chiao Tung University, Taiwan

1. IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 56, NO. 6, NOV. 2007 Design and Implementation of a SIP-Based Mobile and Vehicular Wireless Network With Push Mechanism Yu-Chee Tseng, Jen-Jee Chen, and Yu-Li Cheng National Chiao Tung University, Taiwan

2. Outline • Introduction • System Architecture and Motivation • Basic Operations of the SIP-Based Mobile Network • MH Joining the Mobile Network • Session Setup Procedure and CAC and RM Mechanisms • Handoff Procedure • MH Leaving the Mobile Network • Proposed Push Mechanism • Sleep Procedure • Wake-Up Procedure • Experimental Results and Comparison • Our Prototype • Call Setup Time and Maximum Num ber of Supported Calls • Handoff Delay • Performance of the Push Mechanism • Comparison of Signaling Cost • Conclusion

3. Introduction • Extensive research has focused on how to maintain the global reachability of a device without interruption even when it is moving around. • However, these host mobility management schemes manage the mobility and connectivity of mobile devices in an individual manner. • Supporting host mobility when users exhibit group mobility causes significant costs.

4. Introduction (cont.) • MIPv6-NEMO • IETF network mobility working group • “Network Mobility Basic Support Protocol” RFC 3963 • SIP-NEMO • C.-M. Huang, C.-H. Lee, and J.-R. Zheng, “A novel SIP-based route optimization for network mobility,” IEEE J. Sel. Areas Commun., vol. 24, no. 9, pp. 1682–1691, Sep. 2006.

5. Introduction (cont.) • Both MIPv6-NEMO and SIP-NEMO have shortcomings • Do not consider how to manage wireless resource. • Incurs unnecessary charges and energy consumption for the external wireless interfaces. • For SIP-NEMO, additional servers are required.

6. Introduction (cont.) • SIP-based Mobile Network Gateway (SIP-NMG) • The only component that required. • No modification required to the end nodes. • Support multiple external interfaces. • When there is no Internet activity, the SIP-NMG disconnect the wireless interfaces to save energy and cost. • SIP session control feature is exploited and a push mechanism is proposed. • A push server is required.

7. System Architecture and Motivation

8. System Architecture and Motivation(cont.) • Design motivations • Saving charges of Internet access • QoS guarantee • Push mechanism • An added service for public transportation operators • Backward compatibility • Reducing handoffs • Saving the power consumption of MHs • Decreasing the complexity of MHs

9. Basic Operations of the SIP-Based Mobile Network

10. MH Joining the Mobile Network

11. Session Setup Procedure and CAC and RM Mechanisms

12. Handoff Procedure

13. MH Leaving the Mobile Network • The MH may detect other networks and update its contact information by sending a SIP REGISTER message. • If there is an ongoing session, it can be resumed by SIP re-INVITE. • Since the MH does not deregister with the SIP-MNG, the allocated resource will never be released. • The authors suggest setting a timer for each session and integrating the SIP-MNG with the underlying routing protocol in MANET

14. Proposed Push Mechanism

15. Sleep Procedure SIP-MNG id, status, MSISDN, and IP address SIP URI, SIP-MNG id, and registration expiration time

16. Wake-up Procedure

17. Session Transfer Process

18. Experimental Results and Comparison

19. The Prototype • SIP-NMG (IBM T42) is implemented over FC4 • iptables and libipq are used for NAT and SIP-ALG • External wireless interfaces • Nokia card (GSM) phone • PHS WiWi Card MC-P300/P-Card MC-6550 and Huawei E612 WCDMA PCMCIA card • Push server (ASUS note book) is implemented by C++ on Microsoft Windows XP • MHs are IBM X23 with ASUS WL-167G usb WLAN adapters • OS: Windows XP • SIP client: Windows messenger 5.1

20. Call Setup Time and Maximum Number of Support Calls • IP phone MH2 • Support calls by single interface with acceptable quality, i.e. <1% packet dropping rate. • A GPRS interface cannot provide enough bandwidth to support even one single voice call • the GPRS downlink bandwidth is only 28.8 kb/s, and the uplink bandwidth is even less • Via cellular > via 802.11 • Internet PSTN cellular network  MANET

22. Handoff Delay

23. Performance of the Push Mechanism • IP phone  MH2 • Call setup time consists of two major components:short message transmission time+ wireless interface reconnection time • The call setup time is not short. • This is why we design our push server to temporarily answer an incoming call to keep the session alive, or the caller may hang up before the call is established.

24. Comparison of Signaling Cost (when handoff) • The offline case • SIP-MNG has no SIP signaling cost • MIPv6-NEMO has to track network signaling and update with its HA (costHABU) • The online case • SIP-MNG  N x costSIP-reregistration + S x costSIP-reINVITE • N is the # of MHs in the mboile network • S is the # of sessions • MIPv6-NEMO  costHABU + M x costBU • M is the # of CNs • assume that the routing optimization approach based on binding update for network prefixes is used

25. Conclusion • A SIP-based mobile network architecture to support networking services on the roads • Multiple wireless interfaces • Dynamic bandwidth to internal users • By interpreting SIP signaling, the RM and CAC mechanisms inside the SIP-MNG can guarantee QoS for users • a push mechanism to allow the SIP-MNG to stay offline • do not modify the current SIP client–server architecture and protocol • A prototype has been developed

26. comments • Simple, but maybe effective proposal • The handoff detection on SIP-NMG still rely on lower layer. • May not be efficient enough • When basing on Mobile IP(v6), if address translation is used, the cooperation with upper (application) layer should be considered. • e.g., Using SIP. • Implementing a prototype is interesting but requires manpower and time.