VoIP over Wireless LANs Sangho Shin

VoIP over Wireless LANs Sangho Shin

Outline Why VoIP ? Why 802.11 ? My research Applicability

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

Why 802.11? Unlicensed channels Easy to install High speed Widely deployed

VoIP over 802.11 WLANs Internet Internet PBX AP (Access Point) WIFI

My Research Quality of Service for VoIP in 802.11 WLANs

VoIP (SIP) Client in PDA SIP Session Initiation Protocol (RFC 3261) SIP

VoIP Client in PDA SHARP Zaurus Prototype ARM chip Linux

VoIP Client in PDA Final product

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

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

Layer 2 Handoff Selective Scanning 802.11b channels 1 2 3 4 5 6 7 2.402 GHz Caching 8 9 10 11 2.468 GHz 22 MHz Locality Store the scanned AP information to a cache

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

Layer 3 Handoff Fast L3 Handoff (Client side) Fast subnet change detection Scan unused IPs in a new subnet Passive Monitor DAD (Server side) Collect IPs 160.123.234.31 160.123.231.32 160.123.235.35 160.123.232.36 160.123.238.38 Update IP list V V V V 160.123.234.32 160.123.234.32 160.123.234.35 160.123.234.36 160.123.234.38 160.123.234.31 Fast Response Request Response

Capacity More simultaneous calls Theater Stadium Low VoIP capacity in WLANs Low bandwidth Low utilization of VoIP traffic

Capacity VoIP Capacity 25% 30% Reduce polling overhead DPCF IEEE WCNC’05 PCF APC ACM Qshine’06 DCF 802.11 MAC Fair resource distribution

Call Admission Control (CAC) QoS WIFI WIFI WIFI WIFI WIFI WIFI

Call Admission Control (CAC) QoS CAC WIFI WIFI WIFI WIFI WIFI WIFI

Call Admission Control (CAC) 90% 80% QoS Utilization CAC

Call Admission Control (CAC) 90% 80% QoS Utilization CAC 100% 98% QoS Utilization CAC with QP-CAT

QP-CAT ? Predicted delay with QP-CAT Delay QoS

Experiments NJ Rutgers University

Experiments Capacity for VoIP traffic in 802.11 IEEE Infocom‘07 WLANs DPCF QP-CAT APC

Applicability

Applicability 802.11 WLAN

Thank you !

Applicability 802.11

Applicability Voice Audio Video IEEE 802.11

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

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.

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

BOSS