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 Grasp the 4 kinds of channel combination and understand the idea of multi-frame. Know some radio techniques Get the idea of EDGE Page 2

References BSS Feature Description BSS Signaling Analysis Manual BSC Technical Manual Page 3

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 Page 4

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) Page 5

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 Page 6

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. Page 7

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). Page 8

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 Page 9

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 Page 10

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 Page 11

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

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

The Frequency Spectrum Range (MHz) Uplink Frequency Frequency Point Available Downlink Frequency GSM 450 450.4~457.6 460.4~467.6 Fu(n)=450.6+0.2(n-259) 259<=n<=293 Fd(n)=Fu(n)+10 GSM 480 478.8~486 488.8~496 Fu(n)=479+0.2(n-306) 306<=n<=340 GSM 850 824~849 869~894 Fu(n)=824.2+0.2(n-128) 128<=n<=251 Fd(n)=Fu(n)+45 E-GSM 900 880~915 925~960 Fu(n)=890+0.2n Fu(n)=890+0.2(n-1024) 0<=n<=124 975<=n<=1023 R-GSM 900 876~915 921~960 955<=n<=1023 PCS 1900 1850~1910 1930~1990 Fu(n)=1850.2+0.2(n-512) 512<=n<=810 Fd(n)=Fu(n)+80 Page 14

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. Page 15

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

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

1 1 2 3 Cell Types Omni-directional Cell 120 Degree Cell Omni 120 Page 18

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 Page 19

GSM-GPRS Network Component PSTN ISDN MSC/VLR GMSC GSM /GPRS BSS BSC MS HLR/AUC BTS PCU SS7 BSC SMS system MS BTS GPRS Backbone Internet, Intranet 此页标题禁止有多级标题，更不要出现所在章节的名称。 此页标题要简练，能直接表达出本页的内容。 内容页可以除标题外的任何版式，如图、表等。 该页在授课和胶片＋注释中都要使用。 SGSN GGSN OMC CG BG Other PLMN BSS NSS Page 20

Interface Between Different Entities PSTN ISDN MSC/VLR GMSC GSM /GPRS BSS A Abis BSC 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 此页标题禁止有多级标题，更不要出现所在章节的名称。 此页标题要简练，能直接表达出本页的内容。 内容页可以除标题外的任何版式，如图、表等。 该页在授课和胶片＋注释中都要使用。 SGSN Gi Ga GGSN OMC CG BG Gp Other PLMN BSS NSS Page 21

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

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

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 Page 24

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

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 Page 26

Mobile-service Switching Center – MSC Call Processing Operations and Maintenance Support Interface management Inter-network & Inter-working Billing Inter-network: communication between GSM network and other network Inter-working : communication between different entities inside the GSM network Page 27

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

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

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 Page 30

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

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 Page 32

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

Location Area Identification 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 Page 34

CGI The CGI is a unique international identification for a cell 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 Page 35

BSIC NCC BCC 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! Page 36

National (significant) Mobile station international MSISDN CC NDC SN National (significant) Mobile number Mobile station international ISDN number 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 Page 37

IMSI MCC MNC MSIN Not more than 15 digits 3 digits 2 digits 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 Page 38

TMSI TMSI: Temporary Mobile Subscriber Identification) 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. Page 39

IMEI IMEI IMEI: International Mobile Station Equipment Identification TAC FAC SNR SP IMEI 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# Page 40

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 Page 41

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 1 2 3 4 5 6 7 1 2 3 Timeslot The information carried in one time slot is called a “burst” TDMA FRAME TDMA FRAME Page 42

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. Page 43

Traffic Channel (TCH) TCH Traffic Channels Speech Data TCH/FS TCH/HS 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 Page 44

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

Broadcast Control Channel – BCCH 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 Page 46

Common Control Channel – CCCH 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 Page 47

Dedicated Control Channel – DCCH 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 Page 48

Uplink Logical channel RACH CCCH CCH 1、 随机接入信道（RACH） 上行信道，用于移动台随机提出入网申请，请求分配一个SDCCH，请求包括3bit的建立原因（呼叫请求、寻呼响应、位置更新请求以及短消息请求等）和5bit的参考随机数供MS区别属于自己的接入允许消息。 2、 独立专用控制信道（SDCCH） 是双向专用信道，传送建立连接的信令消息、位置更新消息、短消息、鉴权消息、加密命令、信道分配消息、以及各种附加业务等。可分为独立专用控制信道（SD/8）与CCCH相组合的专用控制信道（SD/4）。 3、 慢速随路控制信道（SACCH） 与业务信道或SDCCH联用，在传送用户信息期间带传某些特定信息，上行链路主要传递无线测量报告，下行链路主要传递部分系统消息。这些消息包括通信质量、LAI、CELL ID、邻区BCCH信号强度、NCC限制、小区选项、TA、功率控制级别等。 4、快速随路控制信道（FACCH） 与TCH联用，用于在传输过程中给系统提供比慢速随路控制信道（SACCH）速度和及时性高得多的信令信息。通过从业务信道借取帧来实现接续，传送如“越区切换”等指令信息。由于话音译码器会重复最后20ms的话音，所以这种偷帧中断不会被用户察觉。除了上述三类控制信道外，还有一种小区广播控制信道（CBCH），它用于下行线，载有短消息业务小区广播（SMSCB）信息，使用像SDCCH相同的物理信道。 SDCCH DCH DCCH SACCH FACCH TCH/F TCH TCH/H Page 49

Downlink Logical channel FCCH SCH BCCH PCH AGCH CCCH CCH 1、频率校正信道（FCCH） 载有供移动台频率校正用的信息，通过FCCH，MS就可以定位一个小区并解调出同一小区的其它信息。通过FCCH，MS也可以知道该载频是不是BCCH载频。 2、 同步信道（SCH） 在FCCH解码后，MS接着要解出SCH信道消息，该消息含移动台帧同步和基站识别的信息：基站识别码(BSIC)，它占有6个比特其中3个比特为0～7范围的PLMN色码，另3个比特为0～7 范围的基站色码(BCC)。 简化的TDMA帧号（RFN），它占有22个比特。 3、广播控制信道（BCCH） 通常，在每个基站收发信台中总有一个收发信机含有这个信道，以向移动台广播系统消息，这些系统消息使得MS可以在空闲模式下有效工作。 4、 寻呼信道（PCH） 这是一个下行信道，用于寻呼被叫的移动台，当网络想与某一MS建立通信时，它会根据MS当前所登记的LAC向该LAC区域内所有小区通过PCH信道发寻呼消息，标示为TMSI或IMSI。 5、准予接入信道（AGCH） 这是一个下行信道，用于基站对移动台的入网请求作出应答，即分配一个SDCCH或直接分配一个TCH。 SDCCH DCH DCCH SACCH FACCH TCH TCH/F TCH/H Page 50

How to use these channels? Power-off Search for frequency correction burst FCCH SCH BCCH PCH RACH AGCH SDCCH TCH FACCH Search for synchronous burst Extract system information Idle mode Monitor paging message Send access burst Allocate signaling channel Dedicated mode Set up the call Allocate voice channel Conversation Release the call Idle mode Page 51

Packet logic channel TCH TCH BCCH CCCH SACCH Packet data channel (PDCH) Comprising packet service channel and packet control channel Packet service channel (PDTCH) Combined into the single-directional service channel Packet control channel Broadcast control channel: PBCCH Public control channel: PPCH, PRACH, PAGCH Private control channel: PACCH, PTCCH TCH BCCH CCCH SACCH Page 52

GSM Logical Channel Combination Main BCCH combination – FCCH + SCH + BCCH + CCCH SDCCH combination – SDCCH/8 + SACCH/8 Combined BCCH – BCCH + CCCH +SDCCH/4 + SACCH/4 TCH/FR combination – TCH/F + FACCH/F + SACCH/F TCH/HR combination – TCH/H + FACCH/H + SACCH/H Page 53

Combination of packet logic channel Packet logic channels (PDCH) can be combined via the following three modes Mode 1: PBCCH+PCCCH+PDTCH+PACCH+PTCCH; Mode 2: PCCCH+PDTCH+PACCH+PTCCH; Mode 3: PDTCH+PACCH+PTCCH In case of small GPRS traffic, GPRS and circuit services use the same BCCH and CCCH in the cell. In this case, only combination mode 3 is needed in the cell With the increase of traffic, the packet public channel should be configured in the cell. Channel combination mode 1 and mode 2 should be adopted Page 54

CONTROL CHANNELS GSM Multi-frames TDMA Frames 1 2 4 3 46 47 48 50 49 1 2 4 3 46 47 48 50 49 51 – Frame Multi-frames CONTROL CHANNELS 5 6 7 Page 55

TRAFFIC CHANNELS GSM Multi-frames TDMA Frames 1 2 4 3 21 22 23 25 24 1 2 4 3 21 22 23 25 24 26 – Frame Multi-frames TRAFFIC CHANNELS 5 6 7 Page 56

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 Page 57

Power Control 5W 0.8W 8W Saves battery power Reduces co-channel and Both Uplink and Downlink power settings can be controlled independently and individually. 5W 0.8W Saves battery power Reduces co-channel and adjacent channel interference 8W BCCH ------- Does not attend Power control Page 58

Discontinuous Transmission – DTX DTX and VAD Discontinuous Transmission – DTX Voice Activity Detection – VAD Battery Saving Interference reduction Page 59

Timing Advance (TA) TA Transmission delay t Transmission delay t The mobile phone should send the signal in advance! TA Transmission delay t When the MS is in idle mode, the time sequence within the MS can be adjusted via the SCH channel. However, the mobile station does not know how far it is away from the base station. If the distance between the MS and the base station is 30km, the time sequence of the MS will be 100μs slower than that of the base station. When the mobile phone sends its first RACH signal, it is already 100μs later. For there is still another 100μs of transmission delay, when the signal reaches the base station, the total delay is 200μs . It is very possible that the signal collides with the pulse of the adjacent timeslot around the base station. Therefore, RACH and some other channel access pulses will be shorter than other pulses. Only after receiving the time sequence adjustment signal (TA) from the base station, MS can send pulses of normal length. In this case, the MS needs to send signals by 200μs in advance. Transmission delay t Page 60

Multi-path Fading Time Dispersion Diversity Frequency Hopping Page 61

Diversity – What’s Diversity? Receive diversity provides an effective technique for both overcoming the impact of fading across the radio channel and increasing the received signal to interference ratio. The former is achieved by ensuring “uncorrelated” (i.e. low enough correlated) fading between antenna branches i.e. not all antennas experience fades at the same time. Page 62

Kinds of Diversity Time diversity Frequency diversity Space diversity Coding, interleaving Frequency diversity Frequency hopping Space diversity Multiple antennas Polarization diversity Dual-polarized antennas Multi-path diversity Equalizer f Page 63

Frequency Hopping Frequency f 0 f 1 f 2 f 3 f 4 Frame Time Page 64

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 Page 65

GSM Development Evolution 57.6 kbps 115 384 2 Mbps GSM HSCSD GPRS EDGE IMT-2000 9.6 2G 2.5G 3G Page 66

Data rate of EDGE and GPRS 8PSK GMSK Page 67

Huawei EDGE Test Result Downlink, 4 TS, MCS-9： Page 68

Summary The basic idea of GSM The frequency spectrum used in GSM The structure of GSM Certain service area and numbers Some radio techniques used in GSM Evolution of GSM Summary Page 69