Mobile Wireless

1. MobileWireless

2. Exponential Growth of World Wide GSM Data Users • Growth in mobile data is expected to be 70% p.a. in next 5 yrs (Merryl Lynch) 90 innovators early adaptors early majority Late majority 80 70 60 in million subscriber 50 ~ 1% 40 30 20 10 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

3. Dramatic Increase of Mobile Data Volume UMTS study funded by the European Comission • data will account for up to 75% of total mobile traffic • by 2005 up to 40% of people in the EU will be using mobile phones 35 30 25 20 Mbytes per user per month Today 0.8 Mb/user/month 15 10 5 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

4. Wireless Data Network Drivers • Information access • PDAs • Network computers • Alpha paging, information distribution • Web/WAP technology

5. Call Forwarding 37% Paging 33% Internet/E-mail 24% Traffic/Weather 15% Conference Calling 13% News 3% Services Most Often Requested After Basic Wireless Telephony Service DataApplications Source: CTIA Web PagePeter D. Hart Research Associates, March 1997

6. Data Services on Cellular • Standards for packet services on cellular are already defined • GSM: GPRS - GSM Packet Radio System • CDMA: IWF and MobileIP • Both utilize bandwidth over the backhaul/backbone to gateway devices • A data network built for packet data transport can reduce the need to expand the backbone beyond voice requirements

7. Wireless Market Segments

8. Residential WLANs • Found in office environment for wireless network access • Either infrared or radio • Standards are • Bluetooth • IEEE 802.11

9. Fixed Wireless • Provide high speed wireless link to connect remote sites • Point-to-point or point-to-multipoint • Line-of-sight or non-line-of-sight systems • Two standards • LMDS – Local Multipoint Distribution System • MMDS

10. Mobile Wireless Networks • Usually digital cellular radion networks • Provide voice and data services • 1G – analog transmission • 2G – digital cellular networks (like GSM) • Circuit switched • 2G+ • HSCSD (circuit switched bundeled timeslots) • GPRS (voice CS, data PS) • 3G – like UMTS • Completely packet switched voice and data

11. GPRS and other Mobile Wireless Technologies Technology Type Throughput Investment Std. Body Availability GSM data Circuit 9.6 kbits/s Low ETSI Now HSCSD Circuit 56 kbits/s Medium ETSI 1999-2000 EDGE Packet 380 kbits/s Medium Ericsson 2000-2001 GPRS Packet 150 kbits/s Medium ETSI 2000-2001 UMTS Packet 2 Mbits/s High (radio) ETSI 2002 HSCSD … High Speed Circuit Switched Data EDGE … Enhanced Data Rate for GSM Evolution GPRS … General Packet Radio Service UMTS … Universal Mobile Telephone Service

12. GSM Packet Data Service Options • Two services as part of "Phase 2+" of the GSM specification • High Speed Circuit Switched Data • (HSCSD) • General Packet Radio Service • (GPRS)

13. High Speed Circuit Switched Data (HSCSD) • allows the combination of multiple timeslots • Channels can be multiplexed together to offer a data rate of up to 56 Kbit/s when using all four slots (14.4 Kbs/channel) • because each time slot could carry a conventional conversation, the use of multiple slots restricts the capacity for speech traffic, resulting in the handset user specifying a minimum acceptable data rate and a preferred (and usually higher) data rate • will prove particularly useful for applications with high-speed data requirements, such as large-scale file transfers, advanced fax services and mobile video communications

14. General Packet Radio Service (GPRS) • available over GSM networks • Data is packet switched - voice remains circuit switched • may also be supported as part of other standards, such as DECT and TDMA • based on the transportation and routing of packetized data • Capacity limitation is hence in terms of the amount of data being transmitted rather than the time of connection • reduces the time spent setting up and taking down connections • works with public data networks using Internet protocol & X.25 • "bursty" applications such as e-mail, traffic telematics, telemetry, broadcast services, and Web browsing • requires modifications to the GSM system architecture and has targeted commercial availability in the 1999 timeframe

15. HSCSD vs GPRS • HSCSD is a small market • HSCD doesn’t do anything to ease spectrum capacity constraints that operators are facing • GPRS benefits • ultimately, higher speed data • the packet data element is most important because it uses the spectrum in a better way • not tying up a whole channel end-to-end for one user

16. Enhanced Data Rate for GSM Evolution (EDGE) • GSM Standard bodies are defining data networking technologies which will build upon GPRS • One such technology is Enhanced Data Rate for GSM Evolution (EDGE) • EDGE will offer a theroretical rate of up to 384 Kbs. • Beyond EDGE, 3G (UMTS) cellular systems will eventually offer data rates up to 2 Mbs

17. Universal Mobile Telephone Service UMTS • 3G mobile system • Developed within ITU-2000 framework • Frequency bands • Terrestrial: 1885 – 2025 MHz and 2110 – 2200 MHz • Sattelite: 1980 – 2010 MHz and 2170 – 2200 MHz • Data rates up to 2Mbps • Inherent IP support • Fully packet switched (data and voice) • Concept of VME (Virtual Home Environment)

18. GGSN SGSN MSC BSC MSC BSC GSM Cellular Packet Data SSS … Switching Subsystem VLR … Visitor Location Register HLR … Home Location Register AUC … Authentication Center EIR … Equipment Identity Center MSC … Mobile Switching Center BSS … Base Station Subsystem BSC … Base Station Controller BTS … Base Transceiver Stations BTS BSS VLR GPRS SGSN and GGSN provide packet data services SSS HLR AUC Backhaul EIR Internet BTS Transit Net Transit Net GSN … GPRS Support Node SGSN … Serving GSN GGSN … Gateway GSN

19. GSM Network Areas

20. GSM Network Areas • GSM network consists of geographical areas • Location Areas – LA • made up of a group of cells served by a BSC • BSC hndles inter cell signaling updates • Keeps track of the cell a user is located • MSC/VLR Service Areas • MSC administers several BSCs • handles signaling traffic of inter LA updates • Public Land Mobile Networks – PLMNs

21. GPRS Logical Architecture • PS GPRS uses completely different network architecture as underlying GSM network • Thus introduction of two new network nodes GPRS Support Nodes • SGSN … Serving GSN (GPRS Support Node) • GGSN … Gateway GSN (GPRS Support Node)

22. SGSN and GGSN Functionality • SGSN • Keeps track of user’s location • Performs security functions and access control • GGSN • Provides internetworking functions with external networks • Simply a strong router with IP and X.25 capability

23. Further Elements and Enhancements • SGSNs are connected to PCUs (Packet Control Units which are part of the BSC) • Via Gb interface – with FR links • GSNs are interconnected over Gn interface via IP backbone • GPRS backbone or GPRS network • HLR is enhanced with GPRS subscriber information • SMS components are upgraded to support SMS transmission via SGSN

24. Intra and Inter PLMN Backbone Networks • Gp interface • Connects two independent GPRS networks for message exchange • Message exchange done by BG (router) • Gi interface • Connection between operator’s GPRS networks and external networks (Internet)

25. GPRS Support Nodes • GSN is main element in GPRS infrastructure • Mobility router • Provides connection • Enables interworking with various data networks

26. GGSN • Used to access external data network • IP router containing all necessary routing info for attached GPRS users • Routing info used to tunnel PDUs to MS’s current point of attachement (SGSN) • Allocation of dynamic IP addresses • Either itself or external DHCP server

27. SGSN • Serves MS in terms of packet data services • SGSN establishes connection via GGSN to requested data network • Maintains all data structures (contexts) for • Authentication • Routing process • In case of roaming (SGSN and GGSN in different PLMNs) – interconnected via Gp interface • Provides security and others

28. PCU • Located in the BSC • Acts as an interface to the SGSN • Distinguishes data and voice • Sends data over FR via SGSN into GPRS backbone • Realized in SW or HW

29. APN • Access Point Name • Defined by ETSI in order to deal with huge number of IP networks to connect to • Uniquely identifies the network a user wants to access • L3 protocols defined are IPv4 and IPv6

30. Access Point Name (username) Type (Ipv4, Ipv6, X.25) Access mode (non/transparent) DHCP local pool information Accept network initiate PDP create request List of PDP contexts on the APN IP for DHCP, RADIUS … IP for charging gateway APN • Contains • Name of foreign NW • Network access mode • Stored in HLR • User may select APN by himself from the MS

31. GPRS Concepts • APN: targeted network (ISP, intranet) • PDP context: session id • 1) reach the SGSN (telecom part) • 2) reach the GGSN serving the APN (GTP=moving tunnel) • 3) reach the APN (dedicated link, tunnel)

32. GPRS PDN Interworking Model • GGSN is access point for internetworking • Seen from outside as normal router • GPRS network seems to be normal IP subnet

33. GPRS Transmission Plane Um … radio interface Uses same PL coding as classical GSM Thus no HW changes TE requires up to 8 slots / TDMA frame GTP … GPRS Tunneling Protocol SNDCP … Subnetwork Dependent Convergence Protocol BSSGP … Base Station System GPRS Protocol

34. Gb Interface • Link layer is FR • BSSGP (BSS GPRS) conveys routing and QoS info between BSS and SGSN • SNDCP encapsulates IP traffic between terminal and SGSN • Multiplexing of L3 connections • Ciphering, segmentation, compression

35. Gn Interface • GTP (ETSI) tunnels IP packets between SGSN and GGSN • One tunnel per active TE • Runs either over UDP or TCP

36. MS • MS could be • Only GPRS phone • User with NW connection via GPRS to his PC

37. The GGSN is effectively a router The GPRS network appears to the PDN as another IP subnet Transparent Internet Access • User who wants to get connected to internet • MS is given an IP address out of the operators address space • Could be statically or dynamically allocated • May be public or private • Authentication performed by SGSN via HLR

38. Transparent Internet Access

39. Non Transparent Access • Allows user to select SPs of his choice • Connection to intranet VPN for email access, intraweb, databases • Has to request IP address and perform authentication in company network • Realized by SGSN during PDP context activation via selected APN • MS sends authentication request • GGSN requests authentication and IP address from specified server (Radius, DHCP) of customers intranet • Use of Ipsec and/or L2 tunnel for terminating private IP addresses at GGSN via Internet

40. Interworking Between GPRS Roaming User’s BGP (RFC 1771)

41. H.323 GW FR SGSN GGSN IP PSTN Transit Net BTS BSC QoS on GPRS H.323 Gateway IP QoS CAR WFQ CRTP H.323 client FR CoS Priotities IP QoS WFQ WRED IP QoS IP QoS CRTP

42. Quality of Service Mapping between GPRS QoS and IP QoS levels • Use of IP CoS mechanisms in GGSN/SGSN and in the Backbone: WRED, WFQ, CAR • Admission Control (GGSN): S traffic < Total BW

43. Backbone Issues • Leverage End-to-End Consistency • WFQ, WRED, CAR • MPLS (GGSN as edge router) • Integrated management

44. IP Address Management • GGSN can hold (local pool/DHCP): • Operator’s public IP addresses • Operator’s private IP addresses (NAT) • Other’s public IP addresses (local pool) • Other’s private IP addresses (local pool, dedicated I/F) • configuration per APN

45. IP Address Management • GGSN can allocate addresses: • transparently (local pool using built-in DHCP server/DHCP) • non-transparently (CHAP/IPCP processing, RADIUS/DHCP requests generation) through IOS built-in RADIUS/DHCP clients • configuration per APN

46. GSM to UMTS Evolution

47. Evolution TowardsUMTS • UMTS Backward compatibility to legacy systems • Operators will try to use existing infrastructure as long as possible • Development steps • 1) MIP on top of GPRS • 2) optimize existing routing mechanisms • 3) SGSN and GGSN combined in one node • In future UMTS will completely integrate PSTN • VSCs will replace all class 4 and class 5 switches • Calls will be routed over IP backbone

48. Questions ???