VoIP over Wireless VoIP over Wireless LANsLANs

Sangho ShinSangho Shin

IP

Why VoIP?Why VoIP?

Voice

Personalized ServiceLocation-based ServiceEmergency Service

IP

Voice

Service

Why 802.11?Why 802.11?

► Unlicensed Unlicensed ChannelsChannels

► Easy to installEasy to install► High speedHigh speed► Widely DeployedWidely Deployed

Why 802.11?Why 802.11?

IEEE 802.11Standards

ab

e

f

g

ik

mn p r

sT

u

v

wy

VoIP over 802.11 WLANsVoIP over 802.11 WLANs

PBX

InternetInternet

Quality of Service ?Quality of Service ?

► HandoffHandoff

► CapacityCapacity Limited bandwidthLimited bandwidth Low utilization of VoIP trafficLow utilization of VoIP traffic

SIP Client in PDASIP Client in PDA

SIP = Session Initiation Protocol (RFC 3261)

SIP

SIP Client in PDASIP Client in PDASHARP ZaurusPrototype

SIP Client in PDASIP Client in PDAFinal product

HandoffHandoff

Handoff Time500 ms ~ 1 s

4 ms ~ 100 ms

Selective Scanning& Caching

ACM MobiWac’04

Layer 2 (MAC layer) Handoff

Selective Scanning & Caching

US PatentApplication No. 60/549,782

2004 Product of the Year Award INTERNET TELEPHONY ® magazine

(www.itmag.com)

1 2 3 4 5 6 7 8 9 10 11

2.402 GHz 2.468 GHz22 MHz

► Selective ScanningSelective Scanning

► CachingCaching LocalityLocality Store the scanned AP information to a cacheStore the scanned AP information to a cache

HandoffHandoff

802.11b channels

HandoffHandoff

Handoff Time 1 min

20 ms ~ 300 ms

Fast L3 HandoffACM WICON’06

Passive DADIEEE GLOBECOM’06

Layer 3 (IP layer) Handoff

HandoffHandoff

► Fast L3 Handoff (Client side)Fast L3 Handoff (Client side) Scan unused IPs in a new subnetScan unused IPs in a new subnet

► Passive DAD (Server side)Passive DAD (Server side)

160.123.234.31160.123.231.32160.123.235.35160.123.232.36160.123.238.38

160.123.234.32 160.123.234.32 160.123.234.35 160.123.234.36 160.123.234.31 160.123.234.38

VVVV

Request

Response

CapacityCapacity

Theater Stadium

More simultaneous calls need to be supported

CapacityCapacity

802.11 MAC

PCF DCF

DPCFIEEE WCNC’05

APCACM QSHINE’06

VoIP Capacity 25%~30%

Call Admission ControlCall Admission Control

QP-CAT

Better PredictionHigher Utilization

ExperimentsExperiments

NJ Rutgers University

ExperimentsExperiments

►Capacity for VoIP traffic in IEEE 802.11 Capacity for VoIP traffic in IEEE 802.11 WLANsWLANs

►APCAPC►DPCFDPCF►QP-CATQP-CAT

IEEE INFOCOM’07

ApplicabilityApplicability

►Voice + Audio + VideoVoice + Audio + Video

IEEE 802.11

ApplicabilityApplicability

►Voice + Audio + VideoVoice + Audio + Video

IEEE 802.11

Thank you !

Why Voice over IP ?Why Voice over IP ?

►Personalized servicePersonalized service Location based serviceLocation based service

►Ring sound is turned off Automatically in a Ring sound is turned off Automatically in a theatertheater

►When you arrive at home, all calls to you are When you arrive at home, all calls to you are forwarded to home.forwarded to home.

Why 802.11Why 802.11

►802.11 802.11 CSMA/CDCSMA/CD Unlicensed channelUnlicensed channel Shared by many usersShared by many users High SpeedHigh Speed

►802.11a/g : 54 Mb/s802.11a/g : 54 Mb/s►802.11n (MIMO) : 100Mb/s ~ 500Mb/s802.11n (MIMO) : 100Mb/s ~ 500Mb/s

Easy installationEasy installation CheapCheap

http://images.google.com/imgres?imgurl=http://www.ezoutletshoppingmall.com/files/samsung_logo.jpg&imgrefurl=http://www.techeblog.com/index.php/tech-gadget/samsungs-hybrid-hard-drives&h=268&w=390&sz=28&hl=ko&start=46&tbnid=UNPGQ-JHPKhLfM:&tbnh=85&tbnw=123&prev=/images%3Fq%3DSamsung%2Blogo%26start%3D36%26ndsp%3D18%26svnum%3D10%26hl%3Dko%26sa%3DN

BOSS