Mobile Multimedia and VoIP

Prof. Henning SchulzrinneAndrea Forte · Matthew Mintz-Habib · Takehiro Kawata · Jonathan Lennox ·

Anshuman Rawat · Ron Shacham · Kundan Singh · Sangho Shin · Xiaotao WuDepartment of Computer Science

Columbia Universityhttp://www.cs.columbia.edu/IRT

CATT Research Review, December 3, 2004CATT Research Review, December 3, 2004

December 3, 2004 CATT Research Review 2

Research projects

• Research issues in VoIP and multimedia moving from core protocols to services and mobility support

• PSTN emulation new services

• Large-scale deployments security, spam, management

911 for VoIPVoIP spam prevention

location-based services

session mobilityprofile mobility

SIP terminal mobility

TCP for streaming media

rapid DHCPpredictive handover

L2 handoff accelerationL2 VoIP capacity enhancement

applications

session

transport

network

link

December 3, 2004 CATT Research Review 3

Making 802.11 work for VoIP

• IEEE 802.11 not designed for VoIP• Long layer-2 hand-off delays cannot

replace cordless phones in building• Lots of related work on MAC layer

– but most requires dramatic changes in APs and mobile hosts

– we aim for backward-compatible changes• Designed and implemented algorithms for

– rapid L2 hand-off– increase capacity for VoIP calls by 25%,

while reducing delay in mixed voice/data networks

– decrease L3 hand-off• DHCP optimizations in protocol and

implementation• predictive address acquisition

Packet Delay in Sender

0

50

100

150

200

250

Normal Handoff Selective Scanning Caching

Ave

rage

Del

ay (

ms)

25.323.122.320.1

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 1 2 3

Number of FTP Sessions

Th

rou

gh

pu

t (k

bp

s)

0

50

100

150

200

250

300

350

400

450

500

En

d-t

o-E

nd

De

lay

(ms)

FTP Throughput (download)

VoIP Throughput

VoIP Delay (90%)

December 3, 2004 CATT Research Review 4

Re-architecting “9-1-1” for a VoIP world

• U.S. 9-1-1 emergency calling system is 1970’s technology – reaching end of extensibility

• VoIP imposes new constraints and offers new opportunities

• We are designing protocols and prototyping systems in cooperation with NENA (National Emergency Number Association) and MapInfo

911112

sip:sos@domainw/location or w/out location

geo location

POTS/Wireless Network

IP Network

911

IP Gateway

sip:sos@domainwithout location

Envinsa Server

sip:psap@domainwith location

location

GeoLynx Display

ALI ServerDHCP Server

DNS Server**

DHCP InformMAC Address

Location Info

TCP Socket Telephone Number

PSAP Info

HTTP SOAPLatitude/Longitude

Location Info

VerifiedLocation

Info

civil location**

December 3, 2004 CATT Research Review 5

Session and profile mobility

• Beyond terminal mobility• Mobile devices limited I/O capabilities

– small screen– lo-res camera not suited for conferencing

• Utilize ubiquitous resources– video projectors– networked cameras– speaker phones

• Move session transparently from mobile to local (fixed) resources – and back

• Profile mobility: make “borrowed” devices behave as if they were the user’s

– Internet pay phone– outbound call personalization– call authorization

SA

DA

ResourceControl(3pcc)

Service LocationQuery

SA

sendaudioto SIPUA2

NetworkAppliance

Control

SIP UA1

turn onprojector

SIPUA2call

ResourceDiscovery(SLP UA)

audioand

videostreams

Scriptengine

December 3, 2004 CATT Research Review 6

Spam prevention in VoIP

• Spam & phishing likely to be a problem for VoIP– cheap– anonymous– easily automated

• Content-based spam filtering unlikely to work

• Designing spam prevention based on– user management policies– social networks

Alice Bob

CarolDavid

Emily Frank

has sentemail to

has sentIM to

is this a spammer?