Gsm Power Point272

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MOBILE COMMUNICATIONS

Alexandre ELAGUINE & Mikhail BAIAKOVSKI

31.01.2002


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MOBILE COMMUNICATIONS

Basic principles

Early analog networks

Digital networks, GSM

GPRS and EDGE

UMTS

Future networks


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Wireless versus Mobile


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BASIC NETWORK

STRUCTURE


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Propagation Mechanisms

Reflection

Diffraction (Shadowing)

Scattering

Doppler effects

Fading


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FREQUENCY REUSE


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3/9 CELL PATTERN


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BASIC NETWORK

STRUCTURE


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SYSTEM STRUCTURE


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ANALOGUE MOBILE

NETWORKSNMT 450 NMT 900 AMPS TACS

Start 1981 1986 1984 1985

MHz Up 453 - 457.5 890-915 824-849 890-915

MHz Down 463-467.5 935-960 869-894 935-960

No. of channel 180 1000 832 1000


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SIM: SUBSCRIBER IDENTITY

MODULE


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GSM frequency bands

900 MHz

2*25 MHz Bands

45 MHz Duplex Spacing

125 carriers

1800 MHz

2*75 MHz Bands


375 carriers

1900 MHz

2*60 MHz Bands


300 Carriers

890-915 MHz Uplink

935-960 MHz Downlink

1710-1785 MHz Uplink


1850-1910 MHz Uplink



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GSM: AREAS


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THREE ACCESS METHODS IN

CELLULAR SYSTEMS

FDMA Frequency Division Multiple Access

TDMA Time Division Multiple Access

CDMA Code Division Multiple Access


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TDMA: FRAME


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D-AMPS

The EIA/TIA (TDMA) standard has many names

TDMA (the most common)

US Digital Cellular (USDC)

North American TDMA (NA-TDMA)

Digital AMPS (D-AMPS)

IS-54 and IS-136


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CDMA

Every mobile in the network has a unique code, the chip sequence

When a mobile sends a bit stream, each bit is replaced by the chip code

A one in the bit stream is replaced by the chip code

A zero in the bit code is replaced by the compliment of the chipcode

If the chip code is n bits long, each bit in the original bit stream is

replaced by n bits

Instead of some 10kbps in the original bit stream, Mbps is sent

This is often referred as to spread spectrum techniques


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GPRS, GENERAL PACKET

RADIO SERVICE (1)

Genera! Packet Radio Service (GPRS) is a new service designed for

digital cellular networks (GSM, DCS, PCS).

GPRS uses a packet-mode technique to transfer high-speed and tow-

speed data and signalling in an efficient manner over GSM radionetworks.

GPRS can be used for carrying end user's packet data protocol

such as IP andX.25

GPRS is standardised in ETSI (European Telecommunications

StandardsInstitute).

New GPRS radio channels are defined, and the allocation of thesechannels is flexible: from 1 to 8 radio interface timeslots can

be allocated per TDMA frame, timeslots are shared by the active

users, and up and downlink are allocated separately.

Various radio channel coding schemes are specified to allow

bitrates from 9 to more than 150 kbit/s per user.


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GPRS, GENERAL PACKET

RADIO SERVICE (2) GPRS introduces two new network nodes in the GSM PLMN: The

Serving GPRS Support Node (SGSN), which is at the same

hierarchical level as the MSC, keeps track of the

individual MSs' location and performs security functions

and access control. The SGSN is connected to the base

station system with Frame Relay. The Gateway GSN (GGSN)

provides interworking with external packet-switched

networks, and is connected with SGSNs via an IP-based GPRS

backbone network. The HLR is enhanced with GPRS subscriber

information, and the SMS-MSCs are upgraded to support SMS

transmission via the SGSN. Optionally, the MSC/VLR can be

enhanced for more-efficient co-ordination of GPRS and non-GPRS services and functionality: e.g., paging for circuit-

switched calls which can be performed more efficiently via

the SGSN, and combined GPRS and non-GPRS location updates.


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EDGEEnhanced Data rates for GSM Evolution

ECSD - Enhanced CSD (Circuit Switched Data)

EGPRS - Enhanced GPRS

For higher data rates New coding and modulation schemes

The base stations need to be up dated

EGPRS up to 384 kbps (48 kbps per time slot) ECSD 28.8 kbps


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IMT-2000

FPLMTS: Future Public Land Mobile Telecommunications System

IMT 2000: International Mobile Telecommunications

UMTS: Universal Mobile Telecommunications System

UMTS: Specificed by ETSI, CEPT and UMTS forum

UMTS: Specificed by ETSI, CEPT and UMTS forum


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IMT-2000

The main characteristic of 3G Systems, known collectively as IMT-

2000, are a single family of compatible standards that have the

following characteristics

Used worldwide

Used for all mobile applications

Support both packet-switched and circuit-switched data

transmission

Offer high data rates up to 2Mbps (depending on

mobility/velocity)

Offer high spectrum efficiency


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IMT-2000

IMT-2000 stands for

IMT: International Mobile Communications2000: the frequency range of

2000 MHz and the year 2000 (WARC'92: 1885-2025 MHz and 2110-2200

MHz)

All 3G standards have been developed by regional standarddeveloping organizations (SDOs)

In total, proposals for 17 different IMT-2000 standards were

submitted by regional SDOs to ITU in 1998. 11 proposals for

terrestrial systems and 6 for mobile satellite systems (MSSs).

Evaluation of the proposals was completed in 1998, and negotiatiansto build a consensus among different views were completed in mid

1999. All 17 proposals have been accepted by ITU as IMT-2000

standards. The specification for the Radio Transmission Technology

(RTT) was released at the end of 1999.


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The most important IMT-2000

proposals UMTS (W-CDMA)

as the successor of GSM

CDMA2000

universal wireless communication-13 6 (UWC-

136)/EDGE as the successor of the interim standard'95

(IS-95)

time division-synchroneous CDMA (TD-CDMA)

as the TDMA-based enhancements to D-

AMPS/GSM


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ITU IMT2000 Radio Interface

Specifications 5 were approved by the ITU in November 1999

IMT DS Wideband CDMA (WCDMA)

IMT MC cdma 2000

IMT SC UWC-136 (EDGE)

IMT TC UTRA TDD or TD-SCDMA

IMT FT DECT

DS: Direct Sequence, MC: Multi-Carrier, TC: Time Code, FT :Frequency Time


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Key Differences between W-CDMA and

cdma2000

Parameter cdma2000 W-CDMA

Chip rate 3.68 Mc/s 3.84 Mc/s

Sinchronisation Synchronous Asynchronous

Frame duration 20 ms 10 ms

Foreward Pilot

Common code

multiplexed pilot

Dedicated time

division

multiplexed pilot

Signaling ANSI-41 GSM-MAP


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UMTS

UMTS is being developed by Third-Generation Partnership Project

(3GPP), a joint venture of several SDOs

ETSI (Europe)

Association of Radio Industries and Business/TelecommunicationTechnology Committee (ARIB/TTC) (Japan)

American National Standards Institute (ANSI) T-1 (USA)

Telecommunications Technology Association (TTA) (South

Korea)

Chinese Wireless Telecommunication Standard (CWTS) (China)


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Towards UMTS


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Evolutionary Concept


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Maximum Data Rates

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