1 Introduction During the first half of this century, the transmission of human voice through the telephone was the dominant means of communication next to telegraphy. Radio-supported mobile communication has constantly grown in importance during the last few decades and particularly the last few years to technical advances in transmission and switching technology as well as in microelec- tronics. Table 1.1 presents an overview of the chronological development of mobile radio systems. In contrast to wireline networks, mobile radio networks that comply with the wish for geographically unrestricted communication can be used anywhere where it is not economic or possible to install cabling. Whereas the limiting factor with wireline networks is the network infrastructure that has to be cre- ated, the capacity of radio networks is determined by the frequency spectrum available and the physical attributes of radio waves in the earth’s atmosphere. The development of radio systems is influenced considerably by the scarcity of an important resource—frequencies. For instance, spectral efficiency can be improved through the digitalization of speech and the use of source and chan- nel coding. Existing analogue radio systems are therefore being replaced more and more by digital mobile radio networks. Modern digital techniques used in modulation, coding and equalization enable bandwidth-efficient transmis- sion and offer better interference behaviour and lower susceptibility to noise than analogue-modulated signals. Digital voice and data can be processed and stored before being transmitted. This allows the use of multiplexing methods such as TDM (Time-Division Multiplexing), FDM (Frequency-Division Multiplexing) and CDM (Code- Division Multiplexing) that enable services to be provided to many users. For example, with TDM a large number of users in a specific frequency band- width are able to exchange information without extremely high selectivity of the receiver. This means that fewer steep-edged filters and resonating el- ements are needed, thereby resulting in a cost reduction, whereas modems transmit in burst mode and therefore are more costly. Digital modulation techniques often produce a higher level of transmission quality and are also more compatible with existing digital fixed networks. Mobile communication today is available from a broad spectrum of techno- logical and service-specific forms. The aim of this book is to provide the reader with an overview of the digital communications networks that have been in- troduced over the last few years, along with the services these networks offer Mobile Radio Networks: Networking and Protocols. Bernhard H. Walke Copyright © 1999 John Wiley & Sons Ltd ISBNs: 0-471-97595-8 (Hardback); 0-470-84193-1 (Electronic) 2 1 Introduction Table 1.1: Chronological development of mobile radio systems Year Paging system standards Cordless phone system standards Mobile terrestrial system standards Mobile satellite system standards 1980 POCSAG CT0 NMT 450 Nordic Mobile Telephone Inmarsat-A 1985 CT1 AMPS (USA) Advanced Mobile Phone System RC2000(F) Radio Communication C450 (D,P) Cellular TACS (UK) Total Access Commu- nication System Inmarsat-C 1990 CT2 GSM Global System for Mobile Communication DCS 1800 Digital Cellular System at 1800 MHz Inmarsat-B Inmarsat-M Inmarsat- Paging 1994 ERMES TFTS Terrestrial Flight Telephone System 1998 Inmarsat-P21, Iridium, Aries, Odyssey, Globalstar, Ellipso 2000 UMTS Universal Mobile Telecommunication System FPLMTS Future Public Land Mobile Telecommunication System 2000+ Mobile Broadband System/ Wireless ATM and their protocols. Special emphasis is given to systems in Europe that are currently being used, are being standardized or whose introduction is immi- nent. Deregulation and liberalization of the telecommunications market, along with the various agreements on standardization, are having a major effect on the development of mobile radio systems. Detailed specifications are nec- essary in order to achieve compatibility between the products of different system and terminal suppliers. International and European standards bod- ies are defining mobile radio systems that can be used and operated across country boundaries. This will enable users to be reachable wherever they are roaming and will result in the cost-effective production of terminals per unit, thereby opening up the market to different types of customers. The most important standards organizations active in the mobile radio area are covered in Appendix B. Physical connections over a radio channel are far more complex than those in a fixed network. Some of the main characteristics of radio transmission are therefore presented in Chapter 2. 4 1 Introduction CT0 analogue 1984: CT1 analogue 1987: CT1+ analogue Eurosignal 1974: 1989: Cityruf 1990: Euromessage 1989: Telepoint analogue 1989: CT2 digital 1997: ERMES IMT 2000 1992: USDC digital 1993: PDC digital 1958: A-Netz analogue 1972: B-Netz analogue 1981: NMT analogue 1986: C-Netz analogue 1984: AMPS analogue 1991: GSM 1994: DCS 1800 E1-Netz digital 1992: Data Radio Modacom INMARSAT-C 1988: LEO Satellite Sys. W-ATM 2000:1997:1996: W-LAN 802.11 HIPERLAN/1 2002: UMTS 1991: DECT digital 1991: Trunked Radio analogue 1995: Trunked Radio TETRA digital Satellite Radio Broadband Radio Cellular Radio Data Packet Radio Trunked Radio Paging Systems Telephony Cordless 1974: Private MPT 1327Mobile Radio D-Netz digital 1998: Iridium Figure 1.2: Evolution of mobile radio systems (dates refer to introduction in the field) 1 Introduction 5 Table 1.2: An overview of analogue cellular mobile radio Parameter C 450 NMT 450 NMT 900 TACS E-TACS AMPS Original country Germany Scandinavia Scandinavia GB GB USA Standardized by DBP Telekom CRAG CRAG FCC Introduced in 1985 1981 1986 1984 1983 Uplink [MHz] 450.3–454.74 453–457.5 890–915 890–915 872–905 824–849 Downlink [MHz] 461.3–465.74 463–467.5 935–960 935–960 917–950 869–894 Channel spacing [kHz] 20 25 (20) 25 (12.5) 25 25 30 Duplex range [MHz] 11 10 45 45 45 45 Access method FDMA FDMA FDMA FDMA FDMA FDMA Modulation FSK FFSK FFSK PSK PSK PSK MAH a Yes No No No No No Cell diameter [km] 15–40 2–20 Frequencies [#] 222 180 (220) 1000 1000 1320 833 (1999) Data services [kbit/s] 2.4 – – – 2.4 (no HO) Traffic capacity [Erl./km 2 ] 14 14 12 (3 km distance) a Mobile Assisted Handover 6 1 Introduction Figure 1.3: Distribution of analogue cellular systems in Europe The concept of cordless communication systems summarizes services and applications based on cordless telephony. In principle, with cordless tele- phones, the cable between the telephone terminal and the handset was merely replaced by a radio path that allows a radio connection of up to 300 m/50 m (outdoors/indoors); see Chapter 9. Wireless local area networks take into account the growing demand to avoid cabling of workstation computers; see Chapter 12, whereas mobile satellite radio systems provide global communication and accessibility; see Chapter 14. The mobile communications market is currently developing at a rapid pace, and it is anticipated that the next few years will bring a dramatic growth in the number of users and an increased demand for quality. As a result, the standardization bodies are already developing new standards with the aim of providing a universal, service-integrated mobile telecommunications system in the near future; see Chapter 5. 1.1 Existing and New Networks and Services 1.1.1 GSM/DCS 1800 System The spectacular growth of the GSM-based cellular mobile radio networks, including networks based on the DCS 1800 standard, convey the impression 1.1 Existing and New Networks and Services 7 CITY RUF EURO SIGNAL CT0 CT1 CT1+ ARTS IMTS AMPS NAMTS TACS E TACS900 NMT B C450 RC 2000 RMTS CT2 CT2 plus CT3 PHP DECT ERMES Analogue Digital NMT 450i D AMPS CDMA ? PDCGSM D AMPS2 PCS 1900 PHS 1900 PCS 1800 DCS UMTS IMT 2000 US Japan A EuropeUS CND Cordless Telephony Europe Paging ITA F D FIN NOR SWE D GB Europe PLMN NMT 450 Figure 1.4: Overview of worldwide standards for mobile radio systems that the essential development needed in this area has been accomplished through the introduction of these cellular mobile radio networks. What one forgets is that these networks have been designed as an “extension” of ISDN to the mobile user, but only address the needs to a limited degree: instead of two B-channels per user, only one with a considerably lower user data rate (13/6.5 kbit/s for voice and 9.6 kbit/s for data) is available. Likewise the ISDN-D channel has only been reproduced to a point: an X.25 packet service (X.31) on the D m channel is not possible in GSM. The primary rate connection (2.048 Mbit/s) available with ISDN does not exist. The situation is a similar one with competing systems in the USA and Japan (see Table 1.3 and Figure 1.4). A number of concepts of GSM 900/DCS 1800 systems will have to be devel- oped further in order to head off the competitive pressure of other concepts for cellular networks (UMTS, IMT 2000, Spread Spectrum CDMA) and to provide better support to mobile image and data services. The anticipated demand for ISDN-compatible mobile data services (64 kbit/s) is pressuring . 1991: Trunked Radio analogue 1995: Trunked Radio TETRA digital Satellite Radio Broadband Radio Cellular Radio Data Packet Radio Trunked Radio Paging Systems. Telephony Cordless 1974: Private MPT 1327Mobile Radio D-Netz digital 1998: Iridium Figure 1.2: Evolution of mobile radio systems (dates refer to introduction