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MOBILE COMMUNICATIONS Alexandre ELAGUINE & Mikhail BAIAKOVSKI 31.01.2002. MOBILE COMMUNICATIONS. Basic principles Early analog networks Digital networks, GSM GPRS and EDGE UMTS Future networks. Wireless versus Mobile. BASIC NETWORK STRUCTURE. Propagation Mechanisms. Reflection
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MOBILE COMMUNICATIONSAlexandre ELAGUINE & Mikhail BAIAKOVSKI31.01.2002
MOBILE COMMUNICATIONS • Basic principles • Early analog networks • Digital networks, GSM • GPRS and EDGE • UMTS • Future networks
Propagation Mechanisms • Reflection • Diffraction (Shadowing) • Scattering • Doppler effects • Fading
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 GSM frequency bands
THREE ACCESS METHODS IN CELLULAR SYSTEMS • FDMA Frequency Division Multiple Access • TDMA Time Division Multiple Access • CDMA Code Division Multiple Access
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 • 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 tow-speed 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) • 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.
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
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 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
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 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 (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
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
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)
