Transcript DoCoMo

Mobile Services Using SIP
and 7DS
Henning Schulzrinne
Joint work with Jonathan Lennox, Maria Papadopouli,
Jonathan Rosenberg, Sankaran Narayanan, Kundan Singh,
Xiaotao Wu and other members of the IRT lab
Columbia University
August 2002
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Outline
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SIP as enabler of mobile services
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quick overview of SIP
terminal, service and session mobility
event notification
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machine-to-machine communications
location-based services
Multimodal communications
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7DS
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SIP
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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
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methods, extensible header, opaque body
built-in mobility model:
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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 model
outbound proxy
SIP trapezoid
[email protected]:
128.59.16.1
registrar
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SIP session setup
INVITE
INVITE sip:[email protected] SIP/2.0
Via: SIP/2.0/UDP pc33.atlanta.com
[email protected]:
;branch=z9
128.59.16.1
Max-Forwards: 70
To: Bob <sip:[email protected]>
REGISTER
From: Alice <sip:[email protected]>
;tag=1928301774
Call-ID: [email protected]
CSeq: 314159 INVITE
Contact: <sip:[email protected]>
Content-Type: application/sdp
Content-Length: 142
BYE
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SIP in 3GPP
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3GPP (and 3GGP.2) uses SIP as signaling
protocol for Internet Multimedia Subsystem
(IMS)
but mobile operator mentality:
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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 design
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Framework with three applications:
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route messages to abstractly specified
(user@domain) destination
possibly with multiple physical destinations
applications =
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Establishing and controlling IP telephony and
multimedia sessions
instant messaging
presence
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SIP transparency
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Not Q.931/ISUP split  signaling messages
and intent preserved by network
Transparency (D. Willis):
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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 notification
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Missing service glue:
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network management
alarms – "water in level 2"
email alert
geographic proximity alert
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media interaction  DVR
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"friend Alice is in the area"
see geopriv work in the IETF  location object with embedded
security and privacy policy
"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 notification
alarms
IR detector
temperature
1000
100
10
video
process
control
audio
1
email
0.1
event
interval
0.01
polling
SIP events
RTP
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Controlling devices
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CINEMA
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Integrated communications environment
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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 components
Cisco 7960
MySQL
sipconf
user database
rtspd
LDAP server
conferencing
server
(MCU)
sipd
RTSP
media
server
RTSP
plug'n'sip
wireless
802.11b
proxy/redirect server
unified
messaging
server
Pingtel
Nortel
Meridian
Cisco
2600
sipum
VoiceXML
server
PBX
T1
T1
SIP
sipvxml
PhoneJack interface
sipc
SIP-H.323
converter
sip-h323
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sip:[email protected]
INVITE sip:[email protected]
My owner’s SIP address is
sip:[email protected]
Help!!! (invoke sipc to call
sip:[email protected]
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Device control
Do sip:[email protected] SIP/2.0
…..
<Control>
<Action>turn lamp on</Action>
</Control>
serial port
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Terminal mobility
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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:
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pre-call redirection
mid-call re-INVITE (but not simultaneous moves)
not good for TCP applications – except with NATs
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Session mobility
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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 mobility
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Ability to transparently move services
between devices  much more data than in
GSM SIM
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end-system call handling descriptions
address books
call logs
Solutions:
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SyncML (with SIP event notification?)
SIP URI binding for configuration information 
SIP BIND proposal
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Current SIP standardization
activities
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IM/presence infrastructure
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authorization, buddy lists, presence
publication, ...
authentication and anonymity
emergency calls and ETS
conferencing support
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Multimodal networking
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"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 networking
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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 modalities
bandwidth
(peak)
delay
high
low
high
7DS
802.11
hotspots
low
satellite
SMS?
voice (2G,
2.5G)
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Cost of networking
Modality
mode speed
OC-3
P
155 Mb/s
$0.0013
Australian DSL
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
P
?
$62.50
P
8 kb/s
$133
videoconferencing or 1/3 MP3)
(512/128 kb/s)
(160 chars/message)
Motient
(BlackBerry)
$/MB (= 1 minute of 64 kb/s
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New wireless modes
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High upstream cost  caching
cf. early Internet (Australia)
expand reach by leveraging mobility
locality of data references
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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 points
2G/3G
WLAN
hotspot + cache
Infostation
access sharing
7DS
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Our Approach
Increase data availability by enabling devices to
share resources
– Information sharing
– Message relaying
– Bandwidth sharing
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Self-organizing
No infrastructure
Exploit host mobility
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7DS
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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 7DS
news
events in campus,
pictures
where is
the closest
Internet
café ?
service location queries
WAN
pictures,
measurements
traffic, weather,
maps, routes, gas station
schedule info
autonomous cache
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Information sharing with 7DS
WLAN
data query
Host A
WAN
Host D
cache miss
Host C
query WLAN data cache hit
Host B
Host A
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7DS options
Cooperation
Power conservation
Server to client
communication enabled
Peer to peer
Querying
active (periodic)
on
off
Forwarding
passive
time
FW query
query
Host A
Host B
Host C
time
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7DS cooperation
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Server to client
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peer-to-peer
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only server acquires and shares data
fixed server
mobile server (taxi, bus)
all peers share data
either data of local interest
or "memory dump" (iPod = 10 GB disk)
incentives:
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recover expensive 3G bandwidth costs  cooperative,
currency
enhanced user environment
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Simulation environment
querier
wireless coverage
pause time 50 s
mobile user speed 0 .. 1.5 m/s
host density 5 .. 25
hosts/km2
wireless coverage 230 m (H),
115 m (M), 57.5 m (L)
dataholder
randway model
ns-2 with CMU mobility,
wireless extension &
randway model
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Dataholders (%) after 25'
high transmission power
Dataholders (%)
100
P2P
90
80
P2P data sharing
(power cons.)
Mobile Info Server
70
P2P data sharing
60
50
P2P data sharing & FW
(power cons.)
Fixed Info Server
40
Fixed Info Server
30
20
10
Mobile Info Server
0
0
5
10
15
20
25
2
Density of hosts (#hosts/km )
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Average Delay (s)
Average Delay (s) vs dataholders (%)
peer-to-peer schemes
1600
1400
1200
1000
800
600
400
200
0
high transmission power
medium transmission power
0
10
20
30
40
50
60
70
80
90
100
Dataholders (%)
P2P (high transmission power) one initial dataholder & 20 cooperative hosts in 2x2
P2P(medium transmission power) one initial dataholder & 20 coperative hosts in 1x1
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Dataholders (%)
Fixed Info Server
simulation and analytical results
high transmission power
60
40
20
0
0
500
1000
1500
simulation
model
2000
2500
3000
Time (s)
Probability a host will acquire data by time
t follows 1-e-at
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Delay (s) vs. dataholders (%)
Average Delay (s)
Fixed info server
1200
1000
one server in 2x2
high transmission power
800
600
400
4 servers in 2x2
medium transmission power
200
0
0
5
10
15
20
25
30
35
Dataholders (%)
Fixed Info Server(medium transmission power) 4 initial dataholders (servers) in 2x2
Fixed Info Server (high transmission power ) one initial dataholder (server) in 2x2
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Message relaying with 7DS
WAN
messages
WLAN
Host A
Gateway
WLAN
Message
relaying
Host A
Host B
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avg. # of
buffered
messages = 5
Message relayed (%)
Messages (%) relayed after 25 min
100
80
60
40
20
0
5
10
15
20
25
2
Density of hosts (#hosts/km )
High transmission power (No FW)
High transmission power (FW 6)
Medium transmission power (No FW)
Medium transmission power (FW 6)
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7DS Implementation
"sports"
proxy cache
list of items
7DS
peer
HTTP GET
 full-text content index with HTML parser
 type index ("news", "sport", "map")
 select according to age, size, origin
 FAZ > SZ > AZ
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7DS implementation
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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 ideas
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Conclusion
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Mobility is more than mobile IP and
RAN...
SIP as service enabler for mobile
services
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not necessarily mobile terminals
Multimodal networks for cost-efficient
mobile data access
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