Transcript MOBILE COMMUNICATIONS Alexandre ELAGUINE & Mikhail

MOBILE COMMUNICATIONS
Alexandre ELAGUINE & Mikhail BAIAKOVSKI
31.01.2002
MOBILE COMMUNICATIONS
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Basic principles
Early analog networks
Digital networks, GSM
GPRS and EDGE
UMTS
Future networks
Wireless versus Mobile
BASIC NETWORK
STRUCTURE
Propagation Mechanisms
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Reflection
Diffraction (Shadowing)
Scattering
Doppler effects
Fading
FREQUENCY REUSE
3/9 CELL PATTERN
BASIC NETWORK
STRUCTURE
SYSTEM STRUCTURE
ANALOGUE MOBILE
NETWORKS
NMT 450
NMT 900
AMPS
TACS
Start
1981
1986
MHz Up
453 - 457.5 890-915
MHz Down 463-467.5 935-960
No. of channels 180
1000
1984
824-849
869-894
832
1985
890-915
935-960
1000
DIGITAL MOBILE
NETWORKS
Start
MHz Up
MHz Down
Multiplex
GSM
1992
890-915
935-960
TDMA
D-AMPS
PDC
1991
1993
824-849 ~900 ~1400
869-894 ~800 ~1400
TDMA
TDMA
SIM: SUBSCRIBER IDENTITY
MODULE
GSM frequency bands
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900 MHz
– 2*25 MHz Bands
– 45 MHz Duplex Spacing
– 125 carriers
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1800 MHz
– 2*75 MHz Bands
– 95 MHz Duplex Spacing
– 375 carriers
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1900 MHz
– 2*60 MHz Bands
– 80 MHz Duplex Spacing
– 300 Carriers
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890-915 MHz Uplink
935-960 MHz Downlink
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1710-1785 MHz Uplink
1805-1880 MHz Downlink
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1850-1910 MHz Uplink
1930-1990 MHz Downlink
GSM: AREAS
THREE ACCESS METHODS IN
CELLULAR SYSTEMS
• FDMA Frequency Division Multiple Access
• TDMA Time Division Multiple Access
• CDMA Code Division Multiple Access
TDMA: FRAME
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
CDMA
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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 chip
code
• 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 »
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 towspeed data and signalling in an efficient manner over GSM radio
networks.
• 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 these
channels 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.
GPRS, GENERAL PACKET
RADIO SERVICE (2)
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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 nonGPRS services and functionality: e.g., paging for circuitswitched calls which can be performed more efficiently via
the SGSN, and combined GPRS and non-GPRS location updates.
EDGE
Enhanced Data rates for GSM Evolution
• ECSD - Enhanced CSD (Circuit Switched Data)
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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
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
IMT-2000
• The main characteristic of 3G Systems, known collectively as IMT2000, 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
IMT-2000
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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)
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All 3G standards have been developed by regional standard
developing 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 negotiatians
to 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.
The most important IMT-2000
proposals
• UMTS (W-CDMA)
– as the successor of GSM
• CDMA2000
– universal wireless communication-13 6 (UWC136)/EDGE as the successor of the interim standard'95
(IS-95)
• time division-synchroneous CDMA (TD-CDMA)
– as the TDMA-based enhancements to DAMPS/GSM
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
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DS: Direct Sequence, MC: Multi-Carrier, TC: Time Code, FT :Frequency Time
Key Differences between W-CDMA and
cdma2000
Parameter
Chip rate
Sinchronisation
Frame duration
cdma2000
3.68 Mc/s
Synchronous
20 ms
W-CDMA
3.84 Mc/s
Asynchronous
10 ms
Dedicated time
Common code
division
Foreward Pilot multiplexed pilot multiplexed pilot
Signaling
ANSI-41
GSM-MAP
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/Telecommunication
Technology Committee (ARIB/TTC) (Japan)
– American National Standards Institute (ANSI) T-1 (USA)
– Telecommunications Technology Association (TTA) (South Korea)
– Chinese Wireless Telecommunication Standard (CWTS) (China)
Towards UMTS
Evolutionary Concept
Maximum Data Rates