1. BITS Pilani Pilani | Dubai | Goa | Hyderabad EA C451 Vishal Gupta

2. BITS Pilani Pilani | Dubai | Goa | Hyderabad Agenda: 3G Networks

3. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 What is 3G 3G or 3rd generation mobile telecommunications is a generation of standards for mobile phones and mobile telecommunication services fulfilling the International Mobile Telecommunications-2000 (IMT-2000) specifications by the International Telecommunication Union. Application services include wide-area wireless voice telephone, mobile Internet access, video calls and mobile TV, all in a mobile environment. To meet the IMT-2000 standards, a system is required to provide peak data rates of at least 200 kbit/s. The following standards are typically branded 3G: the UMTS system, first offered in 2001, standardized by 3GPP, used primarily in Europe, Japan, China (however with a different radio interface) and other regions predominated by GSM 2G system infrastructure. The cell phones are typically UMTS and GSM hybrids. the CDMA2000 system, first offered in 2002, standardized by 3GPP2, used especially in North America and South Korea, sharing infrastructure with the IS-95 2G standard. The cell phones are typically CDMA2000 and IS-95 hybrids.

4. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 3G Network

5. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 GPRS Core Network General packet radio service (GPRS) is a packet oriented mobile data service on the 2G and 3G cellular communication system's GSM. GPRS was originally standardized by European Telecommunications Standards Institute (ETSI) and is now maintained by the 3rd Generation Partnership Project (3GPP). GPRS usage charging is based on volume of data, either as part of a bundle or on a pay- as-you-use basis. This contrasts with circuit switching data, which is typically billed per minute of connection time, regardless of whether or not the user transfers data during that period. GPRS is a best-effort service, implying variable throughput and latency that depend on the number of other users sharing the service concurrently, as opposed to circuit switching, where a certain quality of service (QoS) is guaranteed during the connection. 2.5G and 3G systems rely on double core network infrastructures; traditional circuit- switched network nodes (switching points) for telephony, and packet-switched GPRS nodes for various data services. Dedicated nodes handle the SMS service.

6. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 GPRS Core Network GPRS supports the following protocols: Internet protocol (IP). In practice, built-in mobile browsers use IPv4 since IPv6 is not yet popular. Point-to-point protocol (PPP). In this mode PPP is often not supported by the mobile phone operator but if the mobile is used as a modem to the connected computer, PPP is used to tunnel IP to the phone. X.25 connections. This is typically used for applications like wireless payment terminals, although it has been removed from the standard. When TCP/IP is used, each phone can have one or more IP addresses allocated. GPRS will store and forward the IP packets to the phone even during handover. The TCP handles any packet loss (e.g. due to a radio noise induced pause). Addressing A GPRS connection is established by reference to its access point name (APN). The APN defines the services such as WAP access, SMS, MMS, and for Internet communication services such as email and WWW access.

7. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 GPRS Core Network The GPRS core network is the central part of the GPRS which allows 2G, 3G and WCDMA mobile networks to transmit IP packets to external networks such as the Internet. The GPRS system is an integrated part of the GSM network switching subsystem. The GPRS core network provides mobility management, session management and transport for Internet Protocol packet services in GSM and WCDMA networks. The core network also provides support for other additional functions such as billing.

8. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 GPRS support nodes (GSN) A GSN is a network node which supports the use of GPRS in the GSM core network. All GSNs should have a Gn interface and support the GPRS tunneling protocol. There are two key variants of the GSN, namely Gateway GPRS Support Node (GGSN) and Serving GPRS Support Node (SGSN). Gateway GPRS Support Node (GGSN) The GGSN is responsible for the interworking between the GPRS network and external packet switched networks, like the Internet. From an external network's point of view, the GGSN is a router to a sub- network, because the GGSN ‘hides’ the GPRS infrastructure from the external network.

9. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 Gateway GPRS Support Node (GGSN) The GGSN is the anchor point that enables the mobility of the user terminal in the GPRS/UMTS networks. It carries out the role in GPRS equivalent to the Home Agent in Mobile IP. It maintains necessary routing information to tunnel the Protocol Data Units (PDUs) to the SGSN that service a particular MS. The GGSN converts the GPRS packets coming from the SGSN into the appropriate PDP format (e.g., IP or X.25) and sends them out on the corresponding packet data network. In the other direction, PDP addresses of incoming data packets are converted to the GSM address of the destination user. The readdressed packets are sent to the responsible SGSN. The GGSN is responsible for IP address assignment and is the default router for the connected user equipment (UE). The GGSN also performs authentication and charging functions. Other functions include subscriber screening, IP Pool management and address mapping, QoS and PDP context enforcement.

10. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 Serving GPRS Support Node (SGSN) It is responsible for the delivery of data packets from and to the mobile stations within its geographical service area. It provides session management, i.e. mechanisms for establishment, maintenance, and release of end user PDP contexts. Its tasks include packet routing and transfer, mobility management (attach/detach and location management), logical link management, and authentication and charging functions. It – Detunnel GTP packets from the GGSN (downlink) – Tunnel IP packets toward the GGSN (uplink) – Carry out mobility management as Standby mode mobile moves from one Routing Area to another Routing Area – Billing user data

11. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 GPRS tunnelling protocol (GTP) GTP is a group of IP-based communications protocols used to carry GPRS within GSM, UMTS and LTE networks. It is the protocol which allows end users of a GSM or UMTS network to move from place to place whilst continuing to connect to the Internet as if from one location at the GGSN. It does this by carrying the subscriber's data from the subscriber's current SGSN to the GGSN which is handling the subscriber's session. Three forms of GTP are used by the GPRS core network. GTP-U for transfer of user data in separated tunnels for each PDP context. GTP-C for control reasons including: – setup and deletion of PDP contexts – verification of GSN reachability – updates; e.g., as subscribers move from one SGSN to another. GTP' for transfer of charging data from GSNs to the charging function.

12. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 PDP (Packet Data protocol) Context When a GPRS mobile phone sets up a PDP context, the access point (An IP network to which a mobile can be connected) is selected. At this point an access point name (APN) is determined. The PDP (e.g., IP, X.25, FrameRelay) context is a data structure present on both the SGSN and the GGSN which contains the subscriber's session information when the subscriber has an active session. When a mobile wants to use GPRS, it must first attach and then activate a PDP context. This allocates a PDP context data structure in the SGSN that the subscriber is currently visiting and the GGSN serving the subscriber's access point. The data recorded includes: Subscriber's IP address Subscriber's IMSI Subscriber's – Tunnel Endpoint ID (TEID) at the GGSN – Tunnel Endpoint ID (TEID) at the SGSN The Tunnel Endpoint ID (TEID) is a number allocated by the GSN which identifies the tunnelled data related to a particular PDP context.

13. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 3G Network

14. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956

15. 3GPP – WLAN Interworking Scenarios 3GPP 22.934 specifies six 3GPP-WLAN interworking scenarios. Each scenario realises an additional step in integrating WLAN in the 3GPP service offering and naturally includes the previous level of integration of the previous scenario. 3GPP -WLAN interworking scenarios may be considered with the aid of the simplified reference diagram shown in next slide. This reference diagram illustrates the elements of the 3GPP system and WLANs being interworked. These may be interconnected in a variety of ways to develop the progressive scenarios outlined in this section

16. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956

17. Scenario 1 - Common Billing and Customer Care The connection between the WLAN and the 3GPP system is that there is a single customer relationship. The customer receives one bill from the mobile operator for the usage of both 3GPP and WLAN services. Integrated Customer Care allows for a simplified service offering from both the operator and the subscribers perspective. The security level of the two systems may be independent. This scenario does not pose any new requirements on 3GPP specifications.

18. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 Scenario 2 - 3GPP system based Access Control and Charging This is the scenario where authentication, authorization and accounting are provided by the 3GPP system. The security level of these functions applied to WLAN is in line with that of the 3GPP system. This provide means for the operator to charge access in a consistent manner over the two platforms. Benefits of reusing the 3GPP system access control principles: The 3GPP system operator may easily allow subscribers within his existing 3GPP system customer base to access the WLAN with a minimum effort both for the subscriber and the operator. The maintenance of the subscriber may also be simplified.

19. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 Scenario 3: Access to 3GPP system PS based services The goal of this scenario is to allow the operator to extend 3GPP system PS based services to the WLAN. These services may include, for example, APNs, IMS based services, location based services, instant messaging, presence based services etc. Even though this scenario allows access to all services, it is an implementation question whether only a subset of the services is actually provided. However, service continuity between the 3GPP system part and the WLAN part is not required.

20. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 Scenario 4: Service Continuity The goal of this scenario is to allow the services supported in Scenario 3 to survive a change of access between WLAN and 3GPP systems. The change of access may be noticeable to the user, but there will be no need for the user/UE to reestablish the service. There may be a change in service quality as a consequence of the transition between systems due to the varying capabilities and characteristics of the access technologies and their associated networks. It is also possible that some services may not survive, as the continuing network may not support an equivalent service.

21. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 Scenario 5: Seamless services The goal of this scenario is to provide seamless service continuity between the access technologies, for the services supported in Scenario 3. By seamless service continuity is meant minimizing aspects such as data loss and break time during the switch between access technologies.

22. BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956 Scenario 6: Access to 3GPP CS Services This scenario allows access to services provided by the entities of the 3GPP Circuit Switched Core Network over WLAN. This scenario does not imply any circuit-switched type of characteristics to be included into WLAN.