1. SIP Extensions for Enhanced Location Based Services in 3G Networks International SIP 2004, Paris Pavitra Krishnaswamy pavitra@ccpu.com Application-Ready Platform Solutions™

2. 2 AGENDA SIP in 3G Networks – An Introduction Location Based Services Role of SIP in Location Based Services Proposed Solutions Sample Call Flows Q & A

3. 3 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

4. Towards Destination Network 3G UMTS Release 5 Architecture Towards Destination network IMS Signaling User Data RNC PS-CN SGSN GGSN 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 UTRAN 4

5. IP Multimedia Subsystem (IMS) User Data Signaling P-CSCF I-CSCF S-CSCF HSS MGCMG IMS User Data to/from Destination Network SIP 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 5

6. 6 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.

7. 7 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

8. 8 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)

9. 9 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

10. Traditional Location Services Model SGSN Radio Network Mobile Device Network Initiated Location Services Location Request Location Report UE positioning messages

11. 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

12. 1. Request Nearest Spanish 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.Restaurant Information 12. Restaurant Information RNC Wireless Network 5 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 Information 7

13. 13 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.

14. 14 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.

15. 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. 15

16. Solution 1 : A Conceptual View Multimedia/ LBS Calls Destination Network S-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 SIP

17. 6. Request Nearest Spanish Restaurant Location : Location : Bercy, France Application Server 7. Forward Request to Application Server Location : Bercy, France SGSN 10. Restaurant Information RNC Wireless Network 2 3. Locate Mobile Location Based Services based on Solution 1– An Example Global/Local Database 8. Locate Restaurant in Bercy, France 9. Restaurant Information 4 1. Request Mobile Location 5. Mobile Location Response Location : Bercy, France 11. Restaurant Information

18. 18 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.

19. 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. 19 Proposed Solutions- Solution 2

20. Solution 2 : A Conceptual View Multimedia Calls / Calls Requiring Location Based Services Destination Network S-CSCF Serving Proxy P-CSCF Visiting Network Proxy GGSN SGSN MobileRadio Network SIP signaling including header(s) requesting Location Based Service Location Request UE positioning messages Location Request Location Report SIP signaling including location information

21. Application Server 7. Forward Request to Application Server Location : Bercy, France SGSN 10. Restaurant Information RNC Wireless Network 3 4. Locate Mobile Location Based Services based on Solution 2– An Example Global/Local Database 8. Locate Restaurant in Bercy, France 9. Restaurant Information 5 11. Restaurant Information P-CSCF 1. Request Nearest Spanish Restaurant 2. Locate Mobile 6. Mobile Location: Bercy, France

22. 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. 22

23. 23 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.

24. 24 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.

25. 25 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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