Using SIP for Ubiquitous and Location-Based Communications

1
Using SIP for Ubiquitous and Location-Based
Communications

• Henning Schulzrinne
• (with Stefan Berger, Jonathan Lennox, Maria
  Papadopouli, Stelios Sidiroglou, Kundan Singh,
  Xiaotao Wu, Weibin Zhao)
• Columbia University IRT Lab
• CUCS Site Visit
• January 2003

2
Overview

• What is ubiquitous computing?
• What is SIP?
• Location-based computing in SIP
• On-going work

3
Ubiquitous/pervasive computing

• Computers embedded into the environment
• Mobility, but not just cell phones
• Computation and communications
• Integration of devices
• borrow capabilities found in the environment ?
  composition into logical devices
• seamless mobility ? session mobility
• adaptation to local capabilities
• environment senses instead of explicit user
  interaction
• from small dumb devices to PCs

4
What are the core problems?

• Interested in multimedia communications (? Jason
  Nieh for computational mobility)
• Moving and splitting sessions
• Locating services
• Event notification

5
What is SIP?

• Session Initiation Protocol ? protocol that
  establishes, manages (multimedia) sessions
• also used for IM, presence event notification
• Developed at Columbia (with others)
• Standardized by IETF, 3GPP (for 3G wireless),
  PacketCable
• About 60 companies produce SIP products
• Microsofts Windows Messenger (4.7) includes SIP

6
Session mobility

• Walk into office, switch from cell phone to desk
  phone
• e.g., wall display desk phone PC for
  collaborative application
• SIP third-party call control

7
How to find services?

• Two complementary developments
• smaller devices carried on user instead of
  stationary devices
• devices that can be time-shared
• Need to discover services in local environment
• SLP (Service Location Protocol) allows querying
  for services
• find all color displays with at least XGA
  resolution
• CU SLP extensions for scalable, resilient
  discovery
• Need to discover services before getting to
  environment
• is there a camera in the meeting room?
• CU SLP extension find remote DA via DNS SRV

8
Determining locations

• For many devices, cant afford hardware to
  determine location
• Implementing BlueTooth-based location sensor
  networks
• CU 7DS project offer local content location
• Developing programmable active badges with IR and
  RF capabilities

9
Location-based services
Alice has entered Room 700
CPL-based ruleset
WNYC
SIP-based messaging
Make this Alices phone
SIP-based event notification
10
Location filtering language
40.8N, 73.9W
geo civil categorical properties
location-filtering language
EST
in train ? only IM
communication filtering
within 30 of campus
11
Columbia SIP servers (CINEMA)
Telephone switch
Local/long distance 1-212-5551212
rtspd media server
Quicktime
Single machine
RTSP
sipconf Conference server
RTSP clients
Department PBX
sipum Unified messaging
Internal Telephone Extn 7040
713x
sipd Proxy, redirect, registrar server
SQL database
SIP/PSTN Gateway
Web based configuration
SNMP (Network Management)
Extn 7134
H.323
Extn 7136
siph323 SIP-H.323 translator
NetMeeting
xiaotaow_at_cs
12
Pushing context-sensitive data to users

• User with mobile device should get location
  information when entering city, campus or
  building
• flight and gate information
• maps and directions
• local weather forecast
• special advisories (choose security checkpoint
  2)
• Often does not require knowing user
• but interface with (e.g.) calendar
• Example Columbia implementation (7DS)
• OBEX data exchange over BlueTooth
• PDA pushes current appointment or event name
• base station delivers directions and map

13
Conclusion

• SIP auxiliary protocols supports many of the
  core requirements for ubiquitous computing and
  communications
• mobility modalities terminal, user, session,
  service
• service negotiation for devices with different
  capabilities
• automatic configuration and discovery
• event notification and triggered actions
• automatic actions event filtering, CPL, LESS
• SIP offers a loosely-coupled approach
• Also need data push functionality