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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:[email protected], sips:[email protected]
(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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SIP session setupSIP session setup
[email protected]: 128.59.16.1
INVITE
REGISTER
BYE
INVITE sip:[email protected] SIP/2.0Via: SIP/2.0/UDP pc33.atlanta.com ;branch=z9Max-Forwards: 70To: Bob <sip:[email protected]>From: Alice <sip:[email protected]> ;tag=1928301774Call-ID: [email protected]: 314159 INVITEContact: <sip:[email protected]>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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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:[email protected]
Help!!! (invoke sipc to callsip:[email protected]
INVITE sip:[email protected]
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Do sip:[email protected] 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
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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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