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OMA000001 GSM Fundamentals

OMA000001 GSM Fundamentals. ISSUE 4.0. Objectives. Upon completion of this course, you will be able to: Grasp basic idea of GSM system such as frequency spectrum, frequency reuse etc. Grasp the structure of the GSM system and the protocol used. Grasp certain numbers that refer to BSS

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OMA000001 GSM Fundamentals

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  1. OMA000001GSM Fundamentals ISSUE 4.0

  2. Objectives Upon completion of this course, you will be able to: • Grasp basic idea of GSM system such as frequency spectrum, frequency reuse etc. • Grasp the structure of the GSM system and the protocol used. • Grasp certain numbers that refer to BSS • Grasp the 4 kinds of channel combination and understand the idea of multi-frame. • Know some radio techniques • Get the idea of EDGE

  3. References • BSS Feature Description • BSS Signaling Analysis Manual • BSC Technical Manual

  4. Contents Chapter 1 GSM System Overview Chapter 2 GSM Network Structure Chapter 3 Service Area and Number Planning Chapter 4 Channels on the Wireless Interface Chapter 5 Radio Techniques Chapter 6 GPRS & EDGE Introduction

  5. GSM system overview • The GSM system is a frequency- and time-division cellular system, each physical channel is characterized by a carrier frequency and a time slot number • Cellular systems are designed to operate with groups of low-power radios spread out over the geographical service area. Each group of radios serve MSs presently located near them. The area served by each group of radios is called a CELL • Uplink and downlink signals for one user are assigned different frequencies, this kind of technique is called Frequency Division Duplex (FDD) • Data for different users is conveyed in time intervals called slots , several slots make up a frame. This kind of technique is called Time Division Multiple Access (TDMA)

  6. GSM Development 1989 Standard Protocol for GSM take effect 1991 GSM system began to provide service in Europe(2G) System was named as Global System for Mobile Communication 1992 1994 Provide services for the whole world 1996 Micro Cell Technique is used in GSM system

  7. Cell Technique Macro Cell and Micro Cell • A certain radio coverage area formed by a set of transceivers that connected to a set of antennas is called a CELL. • Macro Cell • In the beginning , High-Power BTSs are adopted to provide services. The BTS covers a wider area , but its frequency utilization is not efficient. So , it can only provide a few channels for subscribers. • Micro Cell • Later the Low-Power BTS joins the system for getting a better service area with high capacity . At the same time it adopts the frequency reuse technique to improve the efficiency of the frequency utilization and also the whole capacity of the network.

  8. Multiple Access Technique • Multiple Access Technique allows many subscribers to use the same communication medium. • There are three kinds of basic Multiple Access Technique : FDMA , TDMA and CDMA. • GSM system adopt FDD-TDMA (FDMA and TDMA together).

  9. FDMA • FDMA uses different frequency channels to accomplish communication. • The whole frequency spectrum available is divided into many individual channels (for transmitting and receiving)，every channel can support the traffic for one subscriber or some control information. Frequency Time

  10. TDMA • TDMA accomplishes the communication in different timeslot. • A carrier is divided into channels based on time. Different signals occupy different timeslots in certain sequence , that is , many signals are transmitted on the same frequency in different time. Frequency Time

  11. CDMA • CDMA accomplishes the communication in different code sequences. • Special coding is adopted before transmission, then different information will lose nothing after being mixed and transmitted together on the same frequency and at the same time. Frequency Time

  12. Uplink Downlink 890 915 935 960MHz The Frequency Spectrum GSM 900 Duplex Separation: 45MHz Channel Bandwidth: 200KHz

  13. Base Station Receive Base Station Transmit 1710 1785 1805 1880MHz The Frequency Spectrum DCS 1800 Duplex Separation: 95MHz Channel Bandwidth: 200KHz

  14. The Frequency Spectrum

  15. Frequency Reuse • The frequency resource of mobile system is very limited. • The different Subscribers can use the same frequency in different places. • The quality of communication must be ensured.

  16. 2 Frequency Reuse 7(Site)X 1(Cell) reuse 2 7 3 1 6 4 5

  17. Frequency Reuse 7 5 3 1 11 9 8 6 4 2 10 12 R 4 site X 3 cells reuse

  18. 120 Degree Cell Omni 1 1 2 120 degree 3 Cell Types Omni-directional Cell

  19. Contents Chapter 1 GSM System Overview Chapter 2 GSM Network Structure Chapter 3 Service Area and Number Planning Chapter 4 Channels on the Wireless Interface Chapter 5 Radio Techniques Chapter 6 GPRS & EDGE Introduction

  20. GPRS Backbone GSM-GPRS Network Component PSTN ISDN MSC/VLR GMSC GSM /GPRS BSS BSC MS HLR/AUC BTS PCU SS7 BSC SMS system MS BTS Internet, Intranet SGSN GGSN OMC CG BG Other PLMN BSS NSS

  21. Interface Between Different Entities PSTN ISDN MSC/VLR GMSC GSM /GPRS BSS A BSC Abis MS HLR/AUC BTS C/D/Gs PCU SS7 Gb BSC SMS system MS Um Gr/Gs/Gd/Ge Gc BTS Internet, Intranet GPRS backbone SGSN Gi GGSN Ga OMC CG BG Gp Other PLMN BSS NSS

  22. International Mobile Equipment Identity (IMEI) – Mobile Equipment Mobile Station—MS MS=ME+SIM International Mobile Subscriber Identity (IMSI) – Subscriber Identity Module

  23. SIM Subscriber Identity Module – SIM • International Mobile Subscriber Identity (IMSI) • Temporary Mobile Subscriber Identity (TMSI) • Location Area Identity (LAI) • Subscriber Authentication Key (Ki)

  24. Base Station Subsystem – BSS MSC • The Base Station Controller – BSC • The Base Transceiver Station – BTS • The Trans-coder – TC and Sub multiplexer (SM) BSS TC/SM BSC BTS

  25. Packet Control Unit-----PCU • Packet data switching • Bridge between SGSN and BSC • Provide Pb and Gb interface MSC BSS TC/SM GPRS Backbone BSC PCU SGSN BTS

  26. The Network Switching System NSS AUC OMC HLR EIR PSTN EC MSC/VLR Mobile-service Switching Center –MSC Home Location Register – HLR Visitor Location Register – VLR Equipment Identity Register – EIR Authentication Center – AUC Echo Cancellor – EC BSS

  27. Call Processing Operations and Maintenance Support Interface management Inter-network & Inter-working Billing Mobile-service Switching Center – MSC

  28. Subscriber ID (IMSI and MSISDN) Current subscriber VLR (current location) Supplementary service information Subscriber status (registered/deregistered) Authentication key and AuC functionality Home Location Register – HLR

  29. Mobile Status (IMSI attached / detached / busy / idle etc.) Location Area Identity(LAI) Temporary Mobile Subscriber Identity(TMSI) Allocating the Roaming Number Visitor Location Register – VLR

  30. Equipment Identity Register – EIR • White List • Black List • Grey List IMEI is Checked In White List If NOT found EIR focus on the equipment , not the subscriber!! IMEI is Checked in Black/Grey List

  31. Security Management Event/Alarm Management MMI OS DB Fault Management Configuration Management Performance Management OMC Functional Architecture

  32. Contents Chapter 1 GSM System Overview Chapter 2 GSM Network Structure Chapter 3 Service Area and Number Planning Chapter 4 Channels on the Wireless Interface Chapter 5 Radio Techniques Chapter 6 GPRS & EDGE Introduction

  33. Service Area Service Area PLMN service area PLMN service area PLMN service area MSC service area... MSC service area... ...... Location area... Location area... cell cell

  34. LAI MCC MNC LAC Location Area Identification The LAI is the international code for a location area. MCC: Mobile Country Code，It consists of 3 digits . For example: The MCC of China is "460" MNC: Mobile Network Code，It consists of 2 digits . For example: The MNC of China Mobile is "00" LAC: Location Area Code，It is a two bytes hex code. The value 0000 and FFFF is invalid. For example: 460-00-0011

  35. CGI CGI: Cell Global Identification The CGI is a unique international identification for a cell The format is LAI+CI LAI: Location Area Identification CI: Cell Identity. This code uses two bytes hex code to identify the cells within an LAI. For example : 460-00-0011-0001

  36. NCC BCC BSIC BSIC BSIC（Base Station Identification Color Code) NCC: PLMN network color code. It comprises 3 bit. It allows various neighboring PLMNs to be distinguished. BCC: BTS color code. It comprises 3 bit, used to distinguish different cells assigned the same frequency!

  37. CC NDC SN National (significant) Mobile number Mobile station international ISDN number MSISDN CC: Country Code. For example: The CC of China is "86". NDC: National Destination Code. For example: The NDC of China Telecom is 139, 138, 137, 136, 135. SN: Subscriber Number. Format:H0 H1 H2 H3 ABCD Example: 86-139-0666-1234

  38. IMSI Not more than 15 digits 3 digits 2 digits MSIN MCC MNC NMSI IMSI MCC: Mobile Country Code，It consists of 3 digits . For example: The MCC of China is "460"。 MNC: Mobile Network Code，It consists of 2 digits . For example: The MNC of China Telecom is "00"。 MSIN: Mobile Subscriber Identification Number. H1H2H3 S ABCDEF For example: 666-9777001 NMSI: National Mobile Subscriber Identification，MNC and MSIN form it together. For Example of IMSI : 460-00-666-9777001

  39. TMSI • The TMSI is assigned only after successful subscriber authentication. • The VLR controls the allocation of new TMSI numbers and notifies them to the HLR. • TMSI is used to ensure that the identity of the mobile subscriber on the air interface is kept secret. • The TMSI consists of 4 bytes( 8 HEX numbers) and determined by the operator. TMSI: Temporary Mobile Subscriber Identification)

  40. TAC FAC SNR SP IMEI IMEI IMEI: International Mobile Station Equipment Identification TAC: Type approval code, 6 bit, determined by the type approval center FAC: Final assembly code, 2 bit, It is determined by the manufacturer. SNR: Serial number, 6 bits, It is issued by the manufacturer of the MS. SP: 1 bit , Not used. Check the IMEI in your MS : *#06#

  41. Contents Chapter 1 GSM System Overview Chapter 2 GSM Network Structure Chapter 3 Service Area and Number Planning Chapter 4 Channels on the Wireless Interface Chapter 5 Radio Techniques Chapter 6 GPRS & EDGE Introduction

  42. Physical Channel and Logical Channel The physical channel is the medium over which the information is carried: 200KHz and 0.577ms The logical channel consists of the information carried over the physical channels 0 1 2 3 4 5 6 7 0 1 2 3 Timeslot The information carried in one time slot is called a “burst” TDMA FRAME TDMA FRAME

  43. Two types of Logical Channel Traffic Channel (TCH) : Transmits traffic information, include data and speech. Control Channel (CCH) : Or Signaling Channel, transmits all kinds of control information.

  44. Traffic Channel (TCH) TCH Traffic Channels Speech Data TCH/HS TCH/FS TCH/9.6 TCH/2.4 TCH Traffic Channel TCH/FS Full rate Speech Channel TCH/HS Half rate Speech Channel TCH/9.6 Data Channel 9.6kb/s TCH/4.8 Data Channel 4.8kb/s TCH/2.4 Data Channel 2.4Kb/s TCH/4.8

  45. Control Channel (CCH) CCH (Control Channels) DCCH BCH SDCCH ACCH Synch. CH. BCCH CCCH SACCH FACCH SCH FCCH RACH CBCH Broadcast Control Channel – BCCH Common Control Channel – CCCH Dedicated Control Channel – DCCH Associated Control Channel – ACCH PCH/AGCH

  46. Broadcast Control Channel – BCCH CCH The information carried on the BCCH is monitored by the MS periodically when it is in idle mode BCCH: Broadcast Control Channel FCCH: Frequency Correction Channel SCH: Synchronization Channel BCH Synch. Channels BCCH SCH FCCH

  47. Common Control Channel – CCCH CCH The CCCH is responsible for transferring control information between all mobiles and the network. RACH: Random Access Channel PCH: Paging Channel AGCH: Access Granted Channel CBCH: Cell Broadcast Channel CCCH RACH uplink CBCH downlink PCH/AGCH downlink

  48. Dedicated Control Channel – DCCH CCH DCCH is assigned to a single wireless connection for measurement and handover purpose. SDCCH: Stand-alone Dedicated Control Channel ACCH:Associated Control Channel SACCH: Slow Associated Control Channel FACCH: Fast Associated Control Channel DCCH SDCCH ACCH FACCH SACCH

  49. CCH CCCH RACH Uplink Logical channel SDCCH DCH DCCH SACCH FACCH TCH/F TCH TCH/H

  50. FCCH CCH BCCH SCH BCCH PCH CCCH AGCH Downlink Logical channel SDCCH DCCH DCH SACCH FACCH TCH/F TCH TCH/H

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