1. VoIP over Wireless LANs Sangho Shin

2. IP Why VoIP? Voice Personalized Service Location-based Service Emergency Service IP Voice Service

3. Why 802.11? ► Unlicensed Channels ► Easy to install ► High speed ► Widely Deployed

4. Why 802.11? IEEE 802.11 Standards a b e f g i k m np r s T u v w y

5. VoIP over 802.11 WLANs PBX Internet

6. Quality of Service ? ► Handoff ► Capacity  Limited bandwidth  Low utilization of VoIP traffic

7. SIP Client in PDA SIP = Session Initiation Protocol (RFC 3261) SIP

8. SIP Client in PDA SHARP Zaurus Prototype

9. SIP Client in PDA Final product

10. Handoff Handoff Time 500 ms ~ 1 s 4 ms ~ 100 ms Selective Scanning & Caching ACM MobiWac’04 Layer 2 (MAC layer) Handoff

11. Selective Scanning & Caching US Patent Application No. 60/549,782 2004 Product of the Year Award INTERNET TELEPHONY ® magazine (www.itmag.com)www.itmag.com

12. 1 2 3 4 5 6 7 89 10 11 2.402 GHz2.468 GHz 22 MHz ► Selective Scanning ► Caching  Locality  Store the scanned AP information to a cache Handoff 802.11b channels

13. Handoff Handoff Time 1 min 20 ms ~ 300 ms Fast L3 Handoff ACM WICON’06 Passive DAD IEEE GLOBECOM’06 Layer 3 (IP layer) Handoff

14. Handoff ► Fast L3 Handoff (Client side)  Scan unused IPs in a new subnet ► Passive DAD (Server side) 160.123.234.31 160.123.231.32 160.123.235.35 160.123.232.36 160.123.238.38 160.123.234.32 160.123.234.35 160.123.234.36 160.123.234.31 160.123.234.38 V V V V Request Response

15. Capacity Theater Stadium More simultaneous calls need to be supported

16. Capacity 802.11 MAC PCFDCF DPCF IEEE WCNC’05 APC ACM QSHINE’06 VoIP Capacity 25%~30%

17. Call Admission Control QP-CAT Better Prediction Higher Utilization

18. Experiments NJ Rutgers University

19. Experiments ► Capacity for VoIP traffic in IEEE 802.11 WLANs ► APC ► DPCF ► QP-CAT IEEE INFOCOM’07

20. Applicability ► Voice + Audio + Video IEEE 802.11

21. Applicability ► Voice + Audio + Video IEEE 802.11

22. Thank you !

23. Why Voice over IP ? ► Personalized service  Location based service ► Ring sound is turned off Automatically in a theater ► When you arrive at home, all calls to you are forwarded to home.

24. Why 802.11 ► 802.11  CSMA/CD  Unlicensed channel  Shared by many users  High Speed ► 802.11a/g : 54 Mb/s ► 802.11n (MIMO) : 100Mb/s ~ 500Mb/s  Easy installation  Cheap

29. BOSS