SIP Extensions for Enhanced Location Based Services in 3G Networks

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SIP Extensions for Enhanced Location Based
Services in 3G Networks International SIP 2004,
Paris
Pavitra Krishnaswamy pavitra_at_ccpu.com
Application-Ready Platform Solutions
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AGENDA

• SIP in 3G Networks An Introduction
• Location Based Services
• Role of SIP in Location Based Services
• Proposed Solutions
• Sample Call Flows
• Q A

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SIP in 3G Networks An Introduction

• SIP chosen to be protocol of choice for
  signaling in 3G release 5 IP Multimedia
  subsystem.
• Motivation
• Need for a Converged Network
• Simplicity of the protocol
• Extensibility
• Support for Mobility in SIP

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3G UMTS Release 5 Architecture
UTRAN
Towards Destination Network
IMS
Towards Destination network
UMTS Universal Mobile Telecom System UTRAN
UMTS Terrestrial Radio Access Network RNC
Radio Network Controller PS-CN Packet
Switched Core Network IMS IP Multimedia
Subsystem SGSN Serving GPRS Support Node GGSN
Gateway GPRS Support Node
Signaling
User Data
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IP Multimedia Subsystem (IMS)
CSCF Call State Control Function P-CSCF
Proxy CSCF I-CSCF Interrogating CSCF S-CSCF
Server CSCF MG Media Gateway MGC
Media Gateway Controller HSS Home
Subscriber Server
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Location Based Services

• Location Based Services can be described as
  "applications, which re-act according to a
  geographic trigger".

• A Geographic trigger might be the input of a Town
  name, Zip code or Street into a web page, the
  position of a mobile phone user or the precise
  position of your car as you are driving home from
  the office.

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Location Based Services (LBS)

• Need For LBS
• Commercial Uses
• e.g. Location based entertainment information.
• Network Uses
• e.g. Network service related procedures
• Emergency Uses
• e.g. 911 calls

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Traditional Location Services Model

• To support Location based services the 3G Network
  provides a method to discover the location of a
  UE. This procedure is termed as Location Services
  (LCS).
• Two types of location services are possible
• - Network Initiated Initiated by SGSN
• - Client Initiated Initiated by external client
  node or by the originating mobile device(UE)

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Traditional Location Services Model

• The following steps are involved in Location
  Services
• A remote client or a requests the SGSN for
  location information.
• SGSN requests the radio network (UTRAN) to locate
  the mobile device.
• UTRAN provides location coordinates after
  communicating with the device.
• SGSN provides the co-ordinates to the requested
  nodes/ clients

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Traditional Location Services Model
Network Initiated Location Services
Mobile Device
Radio Network
SGSN
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Traditional Location Services Model
UE Initiated Location Services
Mobile Device
Radio Network
SGSN
HLR/HSS
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Traditional Location Services An Example

Global/Local Database
Application Server

Wireless Network
SGSN
RNC
Location Server
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SIP Location Based Services

• For multimedia calls and calls that require
  location based services SIP can be used to carry
  the location co-ordinates of the mobile
  device(UE) to the application server.
• UEs can request special location based service
  by inserting a specific SIP header into the
  message.

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SIP Location Based Services

• Why use SIP for LBS?
• SIP message headers can be easily extended to
  carry location information and to request
  location based services.
• By inserting the location data for multimedia
  calls when initiating call signaling, additional
  location services procedures need not be
  initiated by application servers on receiving the
  request thus saving time network bandwidth.

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Proposed Solutions Solution 1

• Two solutions have been proposed to use SIP to
  enhance location based services(LBS) in a 3G
  network.
• Solution 1
• - The mobile device initiates the LCS
  procedures to discover its geographical
  co-ordinates, for calls requiring LBS.
• - The LCS procedures used will be that
  prescribed in the normal 3G procedures.
• - The Mobile device inserts location
  information into SIP signaling on completion of
  LCS procedures.

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Solution 1 A Conceptual ViewMultimedia/ LBS
Calls
Destination Network
P-CSCF (Visiting Network Proxy)
Mobile
Radio Network
S-CSCF Serving Proxy
SGSN
GGSN
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Location Based Services based on Solution 1 An
Example
Global/Local Database

Application Server

Wireless Network
SGSN
RNC
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Proposed Solutions Solution 1

• Pros
• The Mobile Device is responsible for providing
  the location information .
• The network is not required to implement
  additional procedures or use additional resources
  to determine UE location.
• Cons
• The handset/ UE will need to be enhanced to
  initiate LCS procedures for specific calls.
• The mobile device needs to be made more
  intelligent to change call initiation procedures
  based on the type of call.

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Proposed Solutions- Solution 2

• Solution 2
• The Proxy (P-CSCF) in the visited network
  performs the LCS procedures.
• The P-CSCF, in this case, will request the SGSN
  to locate the user coordinates for calls that
  require location based services.
• P-CSCF will insert location information into SIP
  Signaling on completion of LCS procedures.
• All procedures described above are only done for
  calls requiring Location Based Services.

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Solution 2 A Conceptual ViewMultimedia Calls /
Calls Requiring Location Based Services
P-CSCF Visiting Network Proxy
Destination Network
Mobile
Radio Network
S-CSCF Serving Proxy
SGSN
GGSN
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Location Based Services based on Solution 2 An
Example
Global/Local Database


Application Server
Wireless Network
SGSN
RNC
P-CSCF
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Proposed Solutions Solution 2

• Pros
• - Time and network bandwidth Savings
• Implementing LCS at the initiating end can help
  avoid separate procedures to do the same at the
  destination network.
• Cons
• - The Proxy CSCF will need to be enhanced to
  communicate with the SGSN, to initiate LCS
  procedures.
• - Complicated P-CSCF (proxy) Implementation.
• The P-CSCF will need additional intelligence to
  insert the location information into the SIP
  signaling.
• The proxy-CSCF might now require a B2BUA
  implementation of the SIP stack instead of a
  regular SIP proxy.

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Extensions to SIP for use in 3G LCS

• Based on the earlier proposals, the
  following extensions are required in the SIP
  protocol to support location services
• 1) New parameter in Request URI
• The new parameter ,user lcs will be added to
  the Request URI field in the SIP header.
• The parameter will inform the network entities
  that a call requires location based services.

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Extensions to SIP for use in 3G LCS

• 2 ) New SIP header
• The new header, location , will carry
  location coordinates and wireless cell
  information.
• This header will be filled by the proxy (P-CSCF)
  or the UE when it wants to send location
  information inside the SIP message.
• The new SIP header concept may have security
  implications. Alternatively, the location data
  could be inserted into the SIP body, to avoid
  this issue.

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Summary

• SIP selected as protocol of choice for 3G IM
  subsystems.
• SIP can be enhanced easily to improve Location
  based services in 3G Networks.
• Two solutions proposed to use SIP for Location
  Based Services.
• New Headers required in SIP for use in LCS
  procedures.

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