sip extensions for enhanced location based services in 3g networks international sip 2004, paris...
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SIP Extensions for Enhanced Location Based Services in 3G
Networks
International SIP 2004, ParisPavitra [email protected]
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
Towards Destination Network
3G UMTS Release 5 Architecture
Towards Destination network
IMS IMS
SignalingUser Data
RNC
PS-CN
SGSN GGSN
UMTS : Universal Mobile Telecom SystemUTRAN : UMTS Terrestrial Radio Access NetworkRNC : Radio Network ControllerPS-CN : Packet Switched Core NetworkIMS : IP Multimedia SubsystemSGSN : Serving GPRS Support NodeGGSN : Gateway GPRS Support Node
UTRAN
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IP Multimedia Subsystem (IMS)
User Data
Signaling
P-CSCF
I-CSCF
S-CSCF
HSS
MGCMG
IMS
User Data to/from Destination Network
SIP
SIP
SIP
CSCF : Call State Control FunctionP-CSCF : Proxy CSCFI-CSCF : Interrogating CSCFS-CSCF : Server CSCFMG : Media GatewayMGC : Media Gateway ControllerHSS : 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 Usese.g.: Network service related procedures
Emergency Usese.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
Traditional Location Services Model
SGSN Radio Network Mobile Device
Network Initiated Location Services
Location Request
Location Report
UE positioning messages
Traditional Location Services Model
HLR/HSS SGSN Radio Network Mobile Device
UE Initiated Location Services
Service Request
Security Procedures
Service Invoke
UE positioning messages
Location Request
Location Report
Service Response
1. Request NearestSpanish
Restaurant Location
Application
Server
Location Server
2. Forward Request to Application Server
3. Request Location of
mobile
4. Request Location of
the mobile
8. Location of
mobile
SGSN
13.RestaurantInformation
12. RestaurantInformationRNC
Wireless Network
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9. Location of the mobile
6. Locate Mobile
Traditional Location Services – An Example
Global/Local Database
10. Locate
Restaurant based
on
location of mobile
11. Restaurant
Information7
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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.
UE’s 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.
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 View
Multimedia/ LBS CallsDestination
NetworkS-CSCF
Serving Proxy
P-CSCF(Visiting Network
Proxy)
GGSN SGSN MobileRadio Network
SIP Signaling with embedded location information
Service Request
Service Invoke
UE positioning messages
Location Request
Location Report
Service Response
SIPSIP
6. Request NearestSpanish
Restaurant Location :
Location : Bercy, France
Application
Server
7. Forward Request to Application Server
Location : Bercy, France
SGSN 10. RestaurantInformation
RNC
Wireless Network
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3. Locate Mobile
Location Based Services based on Solution 1–
An ExampleGlobal/Local
Database
8. Locate
Restaurant in
Bercy, France
9. Restaurant
Information4
1. Request Mobile Location
5. Mobile Location Response
Location : Bercy, France
11. Restaurant Information
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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.
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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Proposed Solutions- Solution 2
Solution 2 : A Conceptual ViewMultimedia Calls / Calls Requiring
Location Based Services
Destination Network
S-CSCF Serving Proxy
P-CSCFVisiting Network
Proxy
GGSN SGSN MobileRadio Network
SIP signaling including header(s) requesting Location Based Service
Location Request
UE positioning messages
Location Request
Location Report
Location Report
SIP signaling including location information
Application
Server
7. Forward Request to Application Server
Location : Bercy, France
SGSN 10. RestaurantInformation
RNC
Wireless Network3
4. Locate Mobile
Location Based Services based on Solution 2–
An ExampleGlobal/Local
Database
8. Locate
Restaurant in
Bercy, France
9. Restaurant
Information5
11. Restaurant Information
P-CSCF1. Request
NearestSpanish
Restaurant
2. Locate Mobile6. MobileLocation:
Bercy, France
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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