1. A Seamless Handoff for Dual-interfaced Mobile Devices in Hybrid WLAN Speaker : Rui-Yi Chien Date : 2005 / 02 / 17

2. Outline Introduction Dual-Interface Handoff Mechanisms Performance Evaluation Of Handoff Conclusions

3. Outline Introduction Dual-Interface Handoff Mechanisms Performance Evaluation Of Handoff Conclusions

4. Introduction Today’s wireless access network consist of several overlapping tiers Provision of real time undisrupted communication to mobile users, anytime and anywhere through these heterogeneous overlay networks, is a challenge

5. A Typical Heterogeneous Network

6. Characteristics of the Overlay Networks The network’s service areas are overlapped Two network support different data rates The signal powers received from the BSs of the different networks are incomparable When there is a change in IP address of the MN, process may cause service disruption

7. Outline Introduction Dual-Interface Handoff Mechanisms Performance Evaluation Of Handoff Conclusions

8. State Model of an Interface

9. Dual-Interface Handoff Mechanisms Use two interfaces each capable of connecting to the WLAN & GPRS networks Two different thresholds (TH1 WLAN, TH2 WLAN ) of Signal to Noise Ratio (SNR)  TH1 WLAN > TH2 WLAN Only WLAN subnet is scanned and connected  TH1 WLAN > SNR > TH2 WLAN The interface may be attached to GPRS  TH2 WLAN < SNR

10. The policy Interfaces follow (1/3) Interface1 Active Interface2 Standby SNR > TH1wlan TH1wlan > SNR > TH2wlan Interface2 OFF WLAN2 WLAN1

11. The policy Interfaces follow (2/3) SNR > TH2wlan SNR < TH2wlan Interface1 Active Interface2 Ready Interface2 OFF WLAN GPRS

12. The policy Interfaces follow (3/3) SNR > THGPRS SNR < THGPRS Interface1 Ready Interface2 Ready Interface2 OFF GPRS1 GPRS2

13. Horizontal Handoff between WLANs Interface1 Active SNR > TH1wlan TH1wlan > SNR > TH2wlan Interface2 OFF Interface2 Standby Interface1 Standby Interface2 Active Interface1 Idle WLAN1 WLAN2

14. Vertical Handoff from WLAN to GPRS SNR > TH2wlan SNR < TH2wlan Interface1 Active Interface2 Standby Interface2 OFF Interface1 Standby Interface1 Idle Interface2 Ready WLAN GPRS

15. Vertical Handoff from GPRS to WLAN SNR > TH2wlan Interface1 Off Interface2 Active Interface2 Standby Interface1 Standby Interface1 Active Interface2 Off WLAN GPRS

16. Outline Introduction Dual-Interface Handoff Mechanisms Performance Evaluation Of Handoff Conclusions

17. Performance Evaluation (1/2)

18. Performance Evaluation (2/2)

19. Outline Introduction Dual-Interface Handoff Mechanisms Performance Evaluation Of Handoff Conclusions

20. The handoff requires that MN can control the switching of communication between two dual mode interfaces

21. Reference A seamless handoff for dual-interfaced mobile devices in hybrid wireless access networks Inayat, R. Aibara, R. Nishimura, K. Advanced Information Networking and Applications, 2004. AINA 2004. 18th International Conference on 2004 IEEE