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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
95 MHz Duplex Spacing
375 carriers
1900 MHz
2*60 MHz Bands
80 MHz Duplex Spacing
300 Carriers
890-915 MHz Uplink
935-960 MHz Downlink
1710-1785 MHz Uplink
1805-1880 MHz Downlink
1850-1910 MHz Uplink
1930-1990 MHz Downlink
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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