Gsm Information

8/2/2019 Gsm Information

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KOREK TELECOM

Korek Telecom is a shared limited company registered inIraq to operate and provide GSM service in the capital ofKurdistan-Erbil and province of Duhok.

On November 2000, the ministry of telecommunicationshas granted KOREK telecom 5 years exclusive GSMmobile license for operating a mobile network in the regioncovered by the capital of Iraqi Kurdistan (Erbil) and theprovince Duhok.

Korek Telecom has attracted hundreds of employees andexperts in the fields of engineering and cellularcommunications. With 350 employees, almost 100% Kurds,Korek Telecom is committed to drawing from local humanresources as an engine for continued progress and

expansion.

Main Office Head quarterKorek TelecomKurdistan St.Pirmam , Erbil , Iraq.

HISTORY OF WIRELESS COMMUNICATION

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The origins of mobile communications followed quickly behindthe invention of radio in the late 1800s. The first applications ofmobile radio were related to the navigation and safety of ships at

sea. As radio concepts developed, so did its use as acommunications tool. The major milestones in the developmentof wireless communications are summarized bellow:

1906Reginald Fesseden successfully transmits human voice over radio.Up until that time, radio communications consisted oftransmissions of Morse Code.1915

J. A. Fleming invents the vacuum tube making itpossible to build mobile radios.1921The Detroit police department used a 2 MHz frequency in thedepartment's first vehicular mobile radio. The system was only oneway and police had to find a wireline phone to respond to radiomessages.1930s

Amplitude Modulation (AM) two-way mobile systems were in placein the U.S. that took advantage of newly developed mobile

transmitters and utilized a "push-to-talk" or half-duplextransmission. By the end of the decade channel allocation grewfrom 11 to 40.1935Invention of Frequency Modulation (FM) improved audio quality.FM eliminated the need for large AM transmitters and resulted inradio equipment which required less power to operate. This madethe use of transmitters in vehicles more practical.1940s

The Federal Communications Commission (FCC) recognized acommunication service it classified as Domestic Public LandMobile (DPLM) radio service. The first DPLM system wasestablished in St. Louis in 1946 and it utilized the 150 MHz band.The following year, a "highway" system was developed along theNew York - Boston corridor using the 35-40 MHz band.1947:D.H. Ring, working at Bell Laboratories, envisionsthe cellular concept.

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1948Shockley, Bardeen and Brittain, at Bell Laboratories, invent thetransistor which enables electronic equipment, including the radioto be miniaturized.

1949 Radio Common Carriers (RCCs) were recognized.1949,1958Bell Systems made broadband proposals.1964AT&T introduces Improved Mobile Telephone System (IMTS).

1968The FCC began to address issue of new US spectrumrequirements.1969

Nordic countries of Denmark, Finland, Iceland,Norway andSweden agree to form a group to study and recommend areas ofcooperation in telecommunication. This led to the standardizationof telecommunications for all members of the Nordic MobileTelephone (NMT) group, the first comprehensive internationalstandardization group.1973The NMT group specifies a feature allowing mobile telephones tobe located within and across networks. This feature would becomethe basis for roaming.

1979The FCC authorized the installation and testing of the firstdevelopmental cellular system in the US (Illinois Bell TelephoneCompany).1981Ericsson launches the worlds first cellular system in Saudi Arabiabased on the analog NMT 450 standard.1991The first digital cellular standard (GSM) is launched.

1998The number of mobile subscribers world-wide has grown to over200 million.

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What is GSM?

GSM (Global System for Mobile communications) is an open,digital cellular technology used for transmitting mobile voice and

data services. GSM differs from first generation wireless systemsin that it uses digital technology and time division multiple accesstransmission methods. GSM is a circuit-switched system thatdivides each 200kHz channel into eight 25kHz time-slots. GSMoperates in the 900MHz and 1.8GHz bands.

GSM 900:

Up link frequency is ( 890 - 915 )Down link frequency (935 - 960 )

890 915 935 960 Mhz

In band 900 no. of radio channel is 175 channel

GSM 1800:

Up link frequency (1710 - 1785 )Down link frequency (1805 - 1880 )

1710 1785 1805 1880 Mhz

In band 900 no. of radio channel is 375 channel

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Entities of the GSM system:

There're three types of generation:

1GThe first generation of analogue mobile phone technologiesincluding AMPS, TACS and NMT

2GThe second generation of digital mobile phone technologiesincluding GSM, CDMA IS-95 and D-AMPS IS-136

2.5G

The enhancement of GSM which includes technologies such asGPRS

3GThe third generation of mobile phone technologies covered by theITU IMT-2000 family

GSM NETWORK COMPONENTS

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The GSM network is divided into two systems. Each of thesesystems are comprised of a number of functional units which areindividual components of the mobile network. The two systemsare:

* Switching System (SS)* Base Station System (BSS)

In addition, as with all telecommunications networks, GSMnetworks are operated, maintained and managed fromcomputerized centers.

Abbreviations:

AUC AUthentication Center

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BSC Base Station ControllerBTS Base Transceiver StationEIR Equipment Identity RegisterHLR Home Location Register

MS Mobile StationMSC Mobile services Switching CenterNMC Network Management CenterOMC Operation and Maintenance CenterVLR Visitor Location Register

The SS is responsible for performing call processing andsubscriber related functions. It includes the following

functional units:

* Mobile services Switching Center (MSC)* Home Location Register (HLR)* Visitor Location Register (VLR)* AUthentication Center (AUC)* Equipment Identity Register (EIR)

The BSS performs all the radio-related functions. TheBSS is comprised of the following functional units:

* Base Station Controller (BSC)* Base Transceiver Station (BTS)

The OMC performs all the operation and maintenance tasks for thenetwork such as monitoring network traffic and network alarms.The OMC has access to both the SS and the BSS.MSs do not belong to any of these systems.

SWITCHING SYSTEM (SS) COMPONENTS

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The Equipment Identity Register (EIR) is an optional register. Itspurpose is to register IMEIs of mobile stations in use. Byimplementing the EIR the network provider can blacklistmalfunctioning MSs or even receive reports to the operations

centre when stolen mobile stations are used to make calls.

BASE STATION SYSTEM (BSS) COMPONENTSIs the section of traditional cellular telephone network which isresponsible for handling traffic and signaling between a mobilephone and the network switching system. The BSS carries outtranscoding of speech channels, allocation of radio channels to

mobile phones, paging ,quality management of transmission andreception over the air interface and many other tasks related to theradio network.

A typicalGSM Base Station

The Base Transciever Station(BTS)or(RBS):The Base TransceiverStation (BTS) is the entity corresponding to one sitecommunicating with the Mobile Stations. Usually, the BTS willhave an antenna with several TRXs (radio transceivers) that eachcommunicate on one radio frequency. The link-level signaling onthe radio-channels is interpreted in the BTS, whereas most of thehigher-level signaling is forwarded to the BSC and MSC.

Types of BTS:

1. Indoor

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2.3. Outdoor

Indoor BTS:

2202 6 TRX2208 12 TRX

Outdoor BTS:

2106 12 TRX2111 6 TRX

Indoor BTS consist of:

1. cabinet2. RBS (radio base station)3. BBS(battery backup station)4. Link

5. Mdb (main distribution bord)6. split

Outdoor BTS consist:

1. tower 2. antenna3. dish + radio

4. feeder cable5. lightning rode6. Earthing

Note: RBS 2106 is a outdoor RBS with stand everycondition (snow, rain).

Differences between RBS:

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CDU: combine and distribution unit.BBS: battery backup station.

Channel:

We can determine the no. of channel.For example every BTS need (12) frequency

12 * 8 (Ts) =941 in 94 is BCCH (brod cast channel)1 in 94 is SDCCH (massage)

Types of antenna:

Korek telecom company use these type of antenna:

1. sector antenna

x-pol

v-pol

2. Omni antenna

2202 2206 2106TRU 6 12 12

CDU 3 3 3

BBS no no yes

Cooling system no no yes

link external external internal

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Difference between ( pol and omni antenna):

Pol it covers (120) degree maximum angle.

Omni covers (360) degree maximum angle.

Pol use for long distance.

Omni use fore short distance.

Link:

It is data transfer from a point (control) to another point.

Outdoor:

1. Dish.2. Radio.3. Cable.

Indoor:

1. Rack.

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2. AMM.3. MMU.4. DDF.5. DDU.

Dish:

Use dish with diameter (0.3, 0.6) m forshort distance.

Use dish with diameter (1.2, 1.8) m for longdistance.

Radio: Use (28, 25, 23, 21)Ghz for inside the city.

Use (18)Ghz for short distance outside thecity.

Use (7.5)Ghz for long distance.

Mini link (E1):

Micro wave ( 7 Ghz - 38 Ghz).

2 * 2 it means 2 E12 * 4 4 E12 * 8 8 E1

Note:The temperature of BTS must be between ( -5 - 55 ).

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The radio interface

The radio interface in GSM uses a combination between frequency(FDMA) and time (TDMA) multiplexing. The frequency division inGSM 900 allocates 125 frequencies in each direction for GSM.The uplink (MS to BTS) frequency is in the area 890 - 915 MHzand the downlink (BTS to MS) frequencies in the are 935-960MHz. The carrier frequencies are separated with 200 kHz on eachside. The frequencies are allocated in pair, so that eachuplink/downlink pair is separated with exactly 45 MHz

Each of the carrier frequencies are divided into 8 logical channels,using TDMA. A TDMA frame contains one time-frame from each of theeight channels, and lasts 4.615 ms. The time-frames from eachchannel lasts 0.577 ms.The total bitrate for all 8 channels is 270.833kbit/s, whereasthe bitrate for each channel is 22.8 kbit/s.

Liecining & sliping:

When the signal is logic (1) the mobile hand received the signal .but ifthe signal is logic (0) i.e.(sliping).it is usueful for battery mobile.

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The Base Station Controller:

Each Base Station Controller (BSC) control the magnitude ofseveral hundred BTSs. The BSC takes care of a number of

different procedures regarding call setup, location update andhandover for each MS. The handover control procedures will comeespecially into focus in this thesis. It is the BSC that decides whenhandover is necessary. This is accomplished by analyzing themeasurement results that are sent from the MS during a call andordering the MS to perform handover if this is necessary. Thecontinous analyzing of measurements from many MSs requiresconsiderable computational power. This put strong constraints onthe design of the BSC

Cells and location areas:

In GSM it is distinguished between cells and location areas. A cellis defined as the area in which one can communicate with acertain base station. In other words, the cell is related to the BTS.When not communicating, the MS does not need to activelyannounce a shift from one cell to another. If the MS is enganged incommunication, a handover must be performed in order to changefrom one cell to another.

A location area is the area assosiated with one VLR. On networkswhere there is a one-one mapping between MSCs and VLRS, thelocation area corresponds to the area controlled by one MSC. Ona change of location area, the MS need to perform a locationupdate in order to register its presence in the new VLR and eraseits presence in the old VLR. In this case, the HLR also needs to beupdated. If the MS is engaged in communication, a handover mustbe performed between the different MSCs. Note that handover

between MSCs belonging to different network-providers isimpossible.

A possible cell configuration

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Handover :

Handover procedures are defined for each of the following cases:

Intra-cell handover. The connections is transferred toanother channel on the same BTS. Intern inter-cell handover. The connection istransferred to another BTS on the same BSC. MSC intern handover. The connection is transferredbetween BTSs belonging to two different BSCs within oneMSC. MSC extern handover. The connection is transferred toa BTS within another MSC.

FREQUENCY CONCEPTS:

The following table summarizes the frequency-relatedspecifications of each of the GSM systems. The terms used in thetable are explained in the remainder of this section.

System P-GSM 900 E-GSM 900 GSM 1800 GSM 1900

Frequencies:Uplink Downlink

Wavelength

BandwidthDuplex DistanceCarrier Separation

Radio Channels1Transmission Rate

890-915 MHz935-960 MHz

~ 33 cm25 MHz`45 MHz200 kHz

125270 kbits/s

880-915MHz925-960MHz

~ 33 cm35 MHz

45 MHz200 kHz

175270 kbits/s

1710-1785MHz1805-1880 MHz

~ 17 cm75 MHz

95 MHz200 kHz

375270 kbits/s

1850-1910 MHz1930-1990 MHz

~ 16 cm60 MHz

80 MHz200 kHz

300270 kbits/s

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NETWORK MONITORING CENTERS

Operation and Maintenance Center (OMC):

An OMC is a computerized monitoring center which isconnected to other network components such as MSCs andBSCs via X.25 data network links. In the OMC, staff arepresented with information about the status of the network andcan monitor and control a variety of system parameters. Theremay be one or several OMCs within a network depending on thenetwork size.

Network Management Center (NMC:

Centralized control of a network is done at a NetworkManagement Center (NMC). Only one NMC is required for anetwork and this controls the subordinate OMCs. The advantageof this hierarchical approach is that staff at the NMC canconcentrate on long term system-wide issues, whereas localpersonnel at each OMC can concentrate on short term, regional

issues.OMC and NMC functionality can be combined in the samephysical network node or implemented at different locations.

MOBILE STATION (MS):

An MS is used by a mobile subscriber to communicate with themobile network. Several types of MSs exist, each allowing thesubscriber to make and receive calls. Manufacturers of MSs

offer a variety of designs and features to meet the needs ofdifferent markets.The range or coverage area of an MS depends on the outputpower of the MS. Different types of MSs have different outputpower capabilities and consequently different ranges. Forexample, hand-held MSs have a lower output power and shorterrange than car-installed MSs with a roof mounted antenna.Figure 1-4 Ranges for different types of MSs

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