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Mobile Services Using Mobile Services Using SIP and 7DSSIP and 7DS

Henning SchulzrinneJoint work with Jonathan Lennox, Maria Papadopouli, Jonathan Rosenberg, Sankaran Narayanan, Kundan

Singh, Xiaotao Wu and other members of the IRT lab

Columbia UniversityAugust 2002

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OutlineOutline

SIP as enabler of mobile services quick overview of SIP terminal, service and session mobility event notification

machine-to-machine communications location-based services

Multimodal communications 7DS

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SIPSIP IETF-standardized application-layer signaling

protocol SIP URIs: sip:alice@example.com, sips:bob@foo.net

(TLS) Uses Session Description Protocol (SDP) to

describe multimedia streams Syntax similar to HTTP and SMTP/RFC 2822

methods, extensible header, opaque body built-in mobility model:

registrars track end system location proxies to provide known contact point "soft handoff" one identifier, multiple terminals mid-call session renegotiation

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System modelSystem model

SIP trapezoid

outbound proxy

a@foo.com: 128.59.16.1

registrar

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SIP session setupSIP session setup

a@foo.com: 128.59.16.1

INVITE

REGISTER

BYE

INVITE sip:bob@biloxi.com SIP/2.0Via: SIP/2.0/UDP pc33.atlanta.com ;branch=z9Max-Forwards: 70To: Bob <sip:bob@biloxi.com>From: Alice <sip:alice@atlanta.com> ;tag=1928301774Call-ID: a84b4c76e66710@pc33.atlanta.comCSeq: 314159 INVITEContact: <sip:alice@pc33.atlanta.com>Content-Type: application/sdpContent-Length: 142

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SIP in 3GPPSIP in 3GPP 3GPP (and 3GGP.2) uses SIP as signaling

protocol for Internet Multimedia Subsystem (IMS)

but mobile operator mentality: regular SIP client may not work on 3G

network limited interworking with clients on wired side lack of openness and transparency trusted network model <> IETF: protect user

from network (and other users)

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SIP designSIP design

Framework with three applications: route messages to abstractly

specified (user@domain) destination possibly with multiple physical

destinations applications =

Establishing and controlling IP telephony and multimedia sessions

instant messaging presence

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SIP transparencySIP transparency Not Q.931/ISUP split signaling

messages and intent preserved by network

Transparency (D. Willis): dialog (sequence number) identity of user header new services without network

knowledge body new session negotiation topology discovery, loop prevention functional new methods

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Event notificationEvent notification Missing service glue:

network management alarms – "water in level 2" email alert geographic proximity alert

"friend Alice is in the area" see geopriv work in the IETF location object with

embedded security and privacy policy media interaction DVR

"start of show postponed by 30 minutes" "semantic SMS"

can build services one-by-one generic platform for quick service creation

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Event notificationEvent notification

100 10 1 0.1 0.011000 eventinterval

alarms IR detector temperatureprocesscontrol

audio

video

emailpolling

SIP eventsRTP

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Controlling devicesControlling devices

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CINEMACINEMA Integrated communications environment

multimedia: audio, video, shared applications, chat, …

call handling and routing conferencing unified messaging control of networked devices instant messaging and presence

Carrier (hosted) or enterprise environment Integrated with existing PSTN environment

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CINEMA componentsCINEMA components

RTSP

sipum

Cisco 7960

sipvxmlSIP

rtspdsipconfLDAP server

MySQL

PhoneJack interface

sipc

T1T1

sipd

mediaserver

RTSP

SIP-H.323converter

messagingserver

unified

server(MCU)

user database

conferencing

sip-h323

VoiceXMLserver

proxy/redirect server

Cisco2600

Pingtel

wireless802.11b

PBX

MeridianNortel

plug'n'sip

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My owner’s SIP address is sip:john@cs.columbia.edu

sip:john@cs.columbia.edu

Help!!! (invoke sipc to callsip:john@cs.columbia.edu

INVITE sip:john@cs.columbia.edu

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Do sip:lamp@cs.columbia.edu SIP/2.0…..<Control><Action>turn lamp on</Action></Control>

serial port

Device controlDevice control

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Terminal mobilityTerminal mobility Terminal moves to different network usually, via mobile IPv4/6 but requires home network support not likely to work through firewalls SIP can support limited terminal mobility:

pre-call redirection mid-call re-INVITE (but not simultaneous

moves) not good for TCP applications – except with

NATs

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Session mobilitySession mobility

Move existing session from one (logical) terminal to another

e.g., from 3G to 802.11 terminal to landline terminal

not IP mobility maintain separate interfaces

use SIP REFER for transferring session

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Service mobilityService mobility Ability to transparently move services

between devices much more data than in GSM SIM end-system call handling descriptions address books call logs

Solutions: SyncML (with SIP event notification?) SIP URI binding for configuration information

SIP BIND proposal

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Current SIP Current SIP standardization activitiesstandardization activities

IM/presence infrastructure authorization, buddy lists, presence

publication, ... authentication and anonymity emergency calls and ETS conferencing support

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Multimodal networkingMultimodal networking "The term multimodal transport is often

used loosely and interchangeably with the term intermodal transport. Both refer to the transport of goods through several modes of transport from origin to destination." (UN)

goods packaged in containers packets and messages

Networking combine different modes of data transport that maximize efficiency

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Multimodal networkingMultimodal networking

Speed, cost and ubiquity are the core variables

cf. pipelines, ships, planes, trucks Traditional assumption of value of

immediacy from PSTN demise of Iridium

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Access modalitiesAccess modalities

high low

high 7DS 802.11hotspots

low satelliteSMS?

voice (2G, 2.5G)

band

wid

th(p

eak)

delay

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Cost of networkingCost of networkingModality mod

espeed $/MB (= 1 minute of 64

kb/s videoconferencing or 1/3 MP3)

OC-3 P 155 Mb/s $0.0013

Australian DSL(512/128 kb/s)

P 512/128 kb/s

$0.018

GSM voice C 8 kb/s $0.66-$1.70

HSCSD C 20 kb/s $2.06

GPRS P 25 kb/s $4-$10

Iridium C 10 kb/s $20

SMS (160 chars/message) P ? $62.50

Motient (BlackBerry) P 8 kb/s $133

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New wireless modesNew wireless modes High upstream cost caching cf. early Internet (Australia) expand reach by leveraging mobility locality of data references

mobile Internet not for general research Zipf distribution for multimedia content newspapers local information (maps, schedules,

traffic, weather, tourist information)

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A family of access pointsA family of access points

Infostation

2G/3G

access sharing

7DS

hotspot + cache

WLAN

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Our ApproachOur ApproachIncrease data availability by enabling devices

to share resources– Information sharing– Message relaying– Bandwidth sharing

Self-organizing No infrastructure Exploit host mobility

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7DS7DS Application Zero infrastructure Relay, search, share & disseminate information Generalization of infostation Sporadically Internet connected Coexists with other data access methods Communicates with peers via a wireless LAN Power/energy constrained mobile nodes

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Examples of services using Examples of services using 7DS7DS

schedule info

WANWAN

autonomous cache

newsevents in campus,pictures

where is the closest Internet café ?

service location queries

traffic, weather, maps, routes, gas station

pictures, measurements

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Information sharing with Information sharing with 7DS7DS

Host B

Host C

data cache hit

cache miss

data

Host A

query

WANWAN Host A Host D

query

WLAN

WLAN

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7DS options7DS options

Forwarding

Host A Host B

query

FWquery

Host C

time

Queryingactive (periodic)

passive

Power conservation

on

off time

communication enabled

CooperationServer to client

Peer to peer

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7DS cooperation7DS cooperation Server to client

only server acquires and shares data fixed server mobile server (taxi, bus)

peer-to-peer all peers share data either data of local interest or "memory dump" (iPod = 10 GB disk)

incentives: recover expensive 3G bandwidth costs

cooperative, currency enhanced user environment

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Simulation environmentSimulation environment

pause time 50 smobile user speed 0 .. 1.5 m/shost density 5 .. 25 hosts/km2

wireless coverage 230 m (H), 115 m (M), 57.5 m (L)

ns-2 with CMU mobility, wireless extension & randway model

dataholder

querier

randway model

wireless coverage

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0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25

Density of hosts (#hosts/km )

Da

tah

old

ers

(%

) P2P data sharing(power cons.)

P2P data sharing

P2P data sharing & FW(power cons.)

Fixed Info Server

Mobile Info Server

Dataholders (%) after 25'Dataholders (%) after 25'

high transmission power

2

Fixed Info Server

Mobile Info Server

P2P

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Average Delay (s) vs dataholders Average Delay (s) vs dataholders (%)(%)peer-to-peer schemespeer-to-peer schemes

0200400600800

1000120014001600

0 10 20 30 40 50 60 70 80 90 100Dataholders (%)

Ave

rag

e D

elay

(s)

P2P (high transmission power) one initial dataholder & 20 cooperative hosts in 2x2

P2P(medium transmission power) one initial dataholder & 20 coperative hosts in 1x1

medium transmission power

high transmission power

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Fixed Info ServerFixed Info Serversimulation and analytical simulation and analytical resultsresults

0

20

40

60

0 500 1000 1500 2000 2500 3000Time (s)

Dat

aho

lder

s (%

)

simulation model

Probability a host will acquire data by time t follows 1-e-at

high transmission power

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Delay (s) vs. dataholders (%)Delay (s) vs. dataholders (%)

0

200

400

600

800

1000

1200

0 5 10 15 20 25 30 35Dataholders (%)

Avera

ge D

ela

y (

s)

Fixed Info Server(medium transmission power) 4 initial dataholders (servers) in 2x2

Fixed Info Server (high transmission power ) one initial dataholder (server) in 2x2

one server in 2x2high transmission power

4 servers in 2x2medium transmission power

Fixed info server

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Message relaying with 7DSMessage relaying with 7DS

Host B

Messagerelaying

Host A

messages

Gateway

WAN

Host AWLAN

WLAN

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0

20

40

60

80

100

5 10 15 20 25Density of hosts (#hosts/km )

Mes

sage

rel

ayed

(%

)

High transmission power (No FW)High transmission power (FW 6)Medium transmission power (No FW)Medium transmission power (FW 6)

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Messages (%) relayed after 25 minMessages (%) relayed after 25 min

avg. # of avg. # of buffered buffered messages = messages = 55

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7DS Implementation7DS Implementation

full-text content index with HTML parser type index ("news", "sport", "map") select according to age, size, origin

FAZ > SZ > AZ

"sports"

list of items

HTTP GET

proxy cache

7DSpeer

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7DS implementation7DS implementation

Initial Java implementation on laptop

Compaq Ipaq (Linux or WinCE) Inhand Electronics ARM RISC board

Low power PCMCIA slot for storage,

network or GPS

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7DS deployment ideas7DS deployment ideas

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ConclusionConclusion

Mobility is more than mobile IP and RAN...

SIP as service enabler for mobile services not necessarily mobile terminals

Multimodal networks for cost-efficient mobile data access