1 GSM Mohamed Mokdad Ecole d’Ingénieurs de Bienne

2 Agenda GSM –Architecture, Interface, … Enhancements –HSCSD –GPRS SIM –Architecture –Protocoles

3 Why GSM in 1982? Good subjective speech quality Low terminal and service cost Support for international roaming Ability to support handheld terminals Support for range of new services and facilities Spectral efficiency ISDN compatibility

4 Phased GSM Approach 1 GSM Phase 1 features –Call Forwarding –All Calls –No Answer –Engaged –Unreachable –Call Barring Outgoing - Bar certain outgoing calls (e.g. ISD) Incoming - Bar certain incoming calls (Useful if in another country) –Global roaming - Visit any other country with GSM and a roaming agreement and use your phone and existing number

5 Phased GSM Approach 2 GSM Phase 2 features –SMS - Short Message Service - Allows you to send text messages too and from phones –Multi Party Calling - Talk to five other parties as well as yourself at the same time –Call Holding - Place a call on Hold –Call Waiting - Notifies you of another call whilst on a call –Mobile Data Services - Allows handsets to communicate with computers –Mobile Fax Service - Allows handsets to send, retrieve and receive faxes –Calling Line Identity Service - This facility allows you to see the telephone number of the incoming caller on our handset before answering –Advice of Charge - Allows you to keep track of call costs –Cell Broadcast - Allows you to subscribe to local news channels –Mobile Terminating Fax - Another number you are issued with that receives faxes that you can then download to the nearest fax machine.

6 Phased GSM Approach 3 GSM Phase 2 + features –Available by 1998 –Upgrade and improvements to existing services –Majority of the upgrade concerns data transmission, including bearer services and packet switched data at 64 kbps and above –DECT access to GSM –PMR/Public Access Mobile Radio (PAMR)-like capabilities –GSM in the local loop –Virtual Private Networks –Packet Radio –SIM enhancements –Premium rate services (e.g. Stock prices sent to your phone)

7 GSM & UMTS numbering

8 Phased GSM Approach 3 GSM-R –Future Railway control platform UMTS –In the context of IMT 2000 families –Releases 4, 5 and 6 –Each release is a complete set and a system can be build on it

9 GSM Evolution review

10 Reference Configuration ISDN/PSTN

11 Cellular System The geographic area is divided into cells Each cell has a Base Station managing the communications A set of cells managed by a single MSC is called Location Area Base Station VLR MSC VLR MSC HLR MSC Mobile Switching Center VLR Visitor Location Register HLR Home Location Register land link Radio link

12 GSM Architecture Databases Switches Radio Systems BTS BSC MS MSC GMSC SSP PSTN BSS HLRVLR EIR SSP AuC NSS PLMN NSS Network and Switching Subsystem EIR Equipment Identity Register AuC Authentication Center GMSC Gateway MSC BSS Base Station System BSC Base Station Controller BTS Base Transceiver Station MS Mobile Station SSP Service Switching Point

13 The GSM Interfaces 1 BS/MSCMT0 BS/MSCMT1TE1 BS/MSCMT1TATE2 BS/MSCMT2TE2 UmSR

14 The GSM Interfaces 2 + B, C, D, E, F, G, H et I to HLR, VLR, MCS, …

15 The GSM Interfaces 3

16 GSM Radio Interface Spectrum –900 MHz (and 1800 MHz) MHz Uplink MHz Downlink FDMA –124 carriers under 900 MHz TDMA –8 Time Slots per carrier 1 (physical) channel per Time Slot –1 channel = 1 communication = 15/26 ms

17 GSM Radio Interface bis

18 E.g. 2G Mobile telephony Spectrum

19 Channels: Logical & Physical

20 Les canaux GSM

21 Logical control channels Broadcast Control CHannel (BCCH) downlink only, used to broadcast Cell specific information; Synchronization CHannel (SCH) downlink only, used to broadcast synchronization and BSS identification information; Paging CHannel (PCH) downlink only, used to send page requests to Mobile Stations; Random Access CHannel (RACH) uplink only, used to request a Dedicated Control CHannel; Access Grant CHannel (AGCH) downlink only, used to allocate a Dedicated Control CHANNEL; Stand Alone Dedicated Control CHannel (SDCCH) bi ‑ directional; Fast Associated Control CHannel (FACCH) bi ‑ directional, associated with a Traffic CHannel; Slow Associated Control CHannel (SACCH) bi ‑ directional, associated with a SDCCH or a Traffic CHannel; Cell Broadcast CHannel (CBCH) downlink only used for general (not point to point) short message information.

22 GSM Frames Hyperframes –i.e Superframes Superframes –1326 frames: –i.e. 51 x 26 Multiframes for signalling –i.e. 26 x 51 Multiframes for traffic Multiframes –i.e 51 TDMA frames for signalling channels –i.e. 24 TDMA frames for traffic channels + 2

23

24 Speech Coding

25 GSM Speech Coding 8 bit samples –i.e kHz sampling rate Implies 64 kbps – i.e. Normal ISDN Then Compressed – i.e. 13 kbps FR (Full Rate Coding)

26 GSM Speech Coding

27 GSM Layers Layer 1 –Enables physical transmission (TDMA, FDMA, etc.) –Assessment of channel quality Layer 2 –Multiplexing of 1 or more layer 2 connections –Routing, flow control, a.o. Layer 3 –Connection management (air interface) –Management of location data –Subscriber identification

28 Layer 3 Radio resource management –Cell Selection, Handover, etc. Mobility management –Authentication, Location management, etc. Connection management Call control Supplementary service support Short message service support

29 System overview Logical control channels –BCCH, SCH, … Sub Layers –Sublayer resource management –Sublayer mobility management and –Sublayer connection management Procedures Messages format

30 Sublayers in layer 3 Sublayer radio resource mgmt - RR –Radio Resource management procedures –Establish, maintain & release R connections –Cell selection/reselection and the handover Sublayer mobility management - MM –Management of the radio interface (Um) –In cooperation with RR Sublayer connection management - CC –Call control (CC) protocol

31 + sublayers layers Supplementary Services - SS –… Short Message Service - SMS –… SIM manager - SIM –…

32 Sublayer RR Idle mode –MS available ready for signalling (e.g. paging) –BSS sends system information (e.g. cell info) Establishment & release of RR connection –Physical point ‑ to ‑ point bi ‑ directional –RR connection transfer RR connected mode –Automatic cell reselection –Indication of temporary unavailability

33 RR Messages Channel establishment messages: ADDITIONAL ASSIGNMENT IMMEDIATE ASSIGNMENT IMMEDIATE ASSIGNMENT EXTENDED IMMEDIATE ASSIGNMENT REJECT Handover messages: ASSIGNMENT COMMAND ASSIGNMENT COMPLETE ASSIGNMENT FAILURE HANDOVER ACCESS HANDOVER COMMAND HANDOVER COMPLETE HANDOVER FAILURE PHYSICAL INFORMATION Ciphering messages: CIPHERING MODE COMMAND CIPHERING MODE COMPLETE Channel release messages: CHANNEL RELEASE PARTIAL RELEASE PARTIAL RELEASE COMPLETE Paging messages: PAGING REQUEST TYPE 1 PAGING REQUEST TYPE 2 PAGING REQUEST TYPE 3 PAGING RESPONSE

34 Sublayer MM MM common procedures –TMSI reallocation procedure –Temporary Mobile Subscriber Identity MM specific procedures –IMSI attach procedure –International Mobile Subscriber Identity –Location updating –Authentication, Ciphering

35 MM Messages Registration messages: IMSI DETACH INDICATION LOCATION UPDATING ACCEPT LOCATION UPDATING REJECT LOCATION UPDATING REQUEST Security messages: AUTHENTICATION REJECT AUTHENTICATION REQUEST AUTHENTICATION RESPONSE IDENTITY REQUEST IDENTITY RESPONSE TMSI REALLOCATION COMMAND TMSI REALLOCATION COMPLETE Connection management messages: CM SERVICE ACCEPT CM SERVICE REJECT CM SERVICE ABORT CM SERVICE REQUEST CM RE-ESTABLISHMENT REQUEST ABORT Miscellaneous message: MM STATUS

36 Sublayer CC Call establishment procedures –From MS or Network Signalling procedures during active state –Notifications & connection rearrangement Call clearing –Call release Miscellaneous procedures –In ‑ band tones and announcements

37 CC messages Call establishment messages: ALERTING CALL CONFIRMED CALL PROCEEDING CONNECT CONNECT ACKNOWLEDGE EMERGENCY SETUP PROGRESS SETUP Call information phase messages: MODIFY MODIFY COMPLETE MODIFY REJECT USER INFORMATION Call clearing messages: DISCONNECT RELEASE RELEASE COMPLETE Messages for supplementary service control FACILITY HOLD HOLD ACKNOWLEDGE HOLD REJECT RETRIEVE RETRIEVE ACKNOWLEDGE RETRIEVE REJECT Miscellaneous messages: CONGESTION CONTROL NOTIFY START DTMF START DTMF ACKNOWLEDGE START DTMF REJECT STATUS STATUS ENQUIRY STOP DTMF STOP DTMF ACKNOWLEDGE

38 E.g. the IEs in Alerting IEIInformation elementType / ReferencePresenceFormatLength Call controlProtocol discriminator M V ½ protocol discriminator(RR, MM, CM) Transaction identifierTransaction identifier M V ½ (Voir norme) AlertingMessage type M V 1 message type(Ciphering, Handover) 1CFacilityFacility O TLV 2 ‑ ? EProgress indicatorProgress indicator O TLV EUser ‑ userUser ‑ user O TLV 3 ‑

39 Some indications Protocol discriminator – Call Control; call related SS messages – Mobility Management messages – Radio Resource management messages Presence –Mandatory –Optional Format –TType only –VValue only –TVType and Value –LVLength and Value –TLVType, Length and Value

40 CC IEs 0 : : : : : : : : : Type 3 & 4 info elements Bearer capability Cause Note Call Control Capabilities Facility Progress indicator Keypad facility Signal Connected number Connected subaddress Calling party subad Called party BCD number Called party subad Low layer compatibility High layer compatibility User-user SS version indicator

41 Capability IEs Bearer capability –Synchronous –V.110, X.30 Low layer compatibility –Unrestricted digital information transfer –3.1 kHz audio High layer compatibility –Telephony –Facsimile G2/G3

42 Incoming GSM Call 2

43 Where is the cellular phone? Handset Switched ON > "here I am" Location update The radio station relays the information to the nearest exchange: The VLR The VLR updates the HLR This way, the home exchange always knows where the phone is The telephone number of the cellular phone indicates the home exchage. The handy works with a provision number

44 Roaming (# Handover) Roaming is the ability to use your own GSM phone number in another GSM network. A roaming agreement is a business agreement between two network operators to transfer items such as call charges and subscription information back and forth, as their subscribers roam into each others areas.

45 Location Based Services

46 GPRS - HSCSD Mohamed Mokdad Ecole d’Ingénieurs de Bienne

47 HSCSD High Speed Circuit Switched Data

48 GPRS Global Packet Radio Service

49 GPRS time slots

50 Coding schemes

51 GPRS Architecture

52 GPRS VPN Tunneling To Access Point Name

53 GPRS – the components Serving GPRS Support Node Gatway GPRS Support Node GPRS Tunneling Protocol

54 The GTP Tunnel

55 E.g. http Encapsulation Overhead of 88 bytes !!!

56 GPRS Data Transmission Speeds The supported data transmission speed per channel is 13.4Kbits. Depending on the type of phone, the following data transmission speeds are theoretically possible: Type 2+1: Receive 26.8Kbits & send 13.4Kbits. Type 3+1: Receive 40.2Kbits &send 13.4Kbits. Type 4+1: Receive 53.6Kbits &send 13.4Kbits

57 GPRS vs HSCSD Stay connected all the time (+) Higher Transfer Speed (=) IP Support (+) APN (-) –Access Point Name –GPRS can be only connected to the ISP GPRS WAP –Much confortable (Speed & Connection)

58 HSCSD vs GPRS / services FunctionHSCSDGPRS Moving images++++ Audio streaming++++ Fax transmission++- transmission++ Telemetry++++ Internet & WAP browsing+++++

59 Is GSM Data-Ready? SMS (Short Message Services) –160 ASCII characters Direct IP (starting with 9.6 kbps) –bypass PSTN 14.4 kbps per time slot –new channel coding GPRS (General Packet Radio Services) –packet mode –fractional & multiple time slots (0.8 to 128 kbps) HSCSD (High-Speed Circuit Switch Data) –38.4 kbps (4 time slots) Yes, the technology is ready and it can (and will) be improved

60 Evolution of GSM EDGE (Enhanced Data rate for GSM Evolution) –2.5 G –new modulation scheme but still 200kHz –384 kbps is the maximum data rate –designed for service providers that may or may not migrate to UMTS UMTS (Universal Mobile Telecommunications Systems) –3G –384 kbps for wide-area coverage –2 Mbps for local coverage –WCDMA (wideband CDMA) 2GHz) –Adopted by Europe and Japan

61 EDGE modulations Channel Coding Scheme Modulation Slot Combinations 1 Slot4 Slots8 Slots MCS1GMSK8.8 kb/s35.2 kb/s70.4 kb/s MCS4GMSK17.6 kb/s70.4 kb/s140.8 kb/s MCS58PSK22.4 kb/s89.6 kb/s179.2 kb/s MCS98PSK59.2 kb/s236.8 kb/s473.6 kb/s

62 SIM Card Mohamed Mokdad Ecole d’Ingénieurs de Bienne

63 SIM = Smart Card ?

64 Smart Card Pinout

65 SPI: Clock and Data Clock Data

66 SIM Content User ID –IMSI, Ki, PINs, PUKs, etc Phone Book SMS A3/A8 Algorithm –Challenge response application Other info –Directory structure

67 SIM and Handy

68 Instructions format CLA:INS:P1:P2:P3 Verify CHV (PIN) –A Incorrect parameter P Run GSM A38 Algorithm –A Incorrect parameter P

69 Stack Hardware e.g. Symbian APIs Application