Chapter overview

Chapter 2 is to familiarize the reader with some of the basic telecommunications concepts. In this chapter the following areas will be discussed; types of channels and their methods of operation, modulation methods as ways of imposing information on the channel, the difference between analog and digital channels and different ways of making connections across the network. The open systems interconnection (OSI) model introduces the concept of layered architectures and the functions of the various layers are explained. More experienced readers may wish to skip this chapter.

Chapter 3 examines some of the different types of transmission media used for physically conveying signals from one point to another. The approach taken will be to explain the fundamental method of operation of each of these transmission media types, introduce the various system components and discuss the application for each type. Some of the main bearer design considerations will be discussed to enable the reader to make an informed decision as to which type of media to use for a particular application. The discussion will commence with systems guided over a physical bearer; namely twisted pair and coaxial copper, fiber-optic cables and the power distribution system. The discussion will then move on to wireless systems; namely microwave radio systems, satellite systems and infra-red transmission, which require no specific bearer and radiate their signals as electromagnetic waves. The emphasis in this chapter is on the fundamental transmission bearer systems, Chapter 6 discusses the methods of carrying information, both analog and digital, on these bearer systems.

Chapter 4 discusses the structure of the PSTN, together with the CCITT signaling system No. 7, which provides a common signaling channel across the digital networks to enable many sophisticated network services, such as ISDN, to be provided.

Chapter 5 discusses various aspects of the voice switching equipment located in a customer's premises. This includes PBX systems, key systems and centrex service. The discussion covers computer telephony integration (CTI), which allows a computer and a telephone to work together so that a user can manage their telephony services using a PC in conjunction with a telephone. For example this allows customer details to pop up on the computer screen when the call is answered.

Chapter 6 considers the different communication approaches used for the provision of services in the public telecommunications network. Fundamentally circuits can be divided into four categories: either analog or digital and each of these can be either switched or leased. First we will consider the switched analog network and then look at the use of dedicated or leased analog circuits. Next the digital services will be discussed beginning with the various types of switched digital services and concluding with various alternatives for dedicated digital services, primarily directed at the large users. In each section the method of operation will be explained, the circuit characteristics described and

Introduction to telecommunications 3

the particular advantages the method offers will be considered. This is intended to enable the reader to make an informed choice about the appropriateness of that particular approach for their unique situation.

Chapter 7 examines the available technologies for the provision of broadband customer access at greater than 1 Mbps, including both wired and wireless services. The wired systems discussed include: systems operating over the existing POTS copper pairs, known collectively as xDSL systems, systems used to provide existing cable television services such as hybrid fiber coax (HFC) and their new counterparts such as fiber to the curb (FTTC) and fiber to the home (FTTH). The wireless systems include multi-channel multipoint distribution system (MMDS), local multipoint distribution services (LMDS), and short-range systems such as Bluetooth. This chapter discusses the operation of each of these alternative customer access technologies together with their relative merits and associated performance issues.

Chapter 8 looks at the following aspects of providing local area networks to business customers:

• The various LAN topologies as well as their advantages and disadvantages

• Various media access methods, specifically CSMA/CD, CSMA/CA, token passing and polling

• Various LAN standards with emphasis on IEEE 802.3, IEEE 802.5, IEEE 802.11 and ANSI X3T9.5

• The functionality devices used to interconnect networks: repeaters, bridges, routers, switches and gateways

• The basic characteristics of LANs, WANs, MANs, VLANs and VPNs.

Chapter 9 deals with the convergence of conventional PSTN networks and IP based internetworks, in particular the Internet. As a result of this convergence, 'voice over IP' is making major inroads into the telecommunications industry. This chapter will introduce the ITU-T H.323 standard for multimedia (audio, video and data) transmission and discuss the TCP/IP protocol suite sufficient for the understanding of the operation of this protocol.

Chapter 10 explains the basic operation of cellular wireless communication systems. The following wireless technologies are discussed:

• Analog cellular voice systems, in particular AMPS and N-AMPS

• Digital cellular voice systems, in particular D-AMPS (North American TDMA), CDMA and GSM

• Cellular data systems, in particular CDPD, GPRS and HDR

• 'Cordless' technologies, in particular CTS and DECT

• Personal communications service (PCS)

• Wireless applications protocol (WAP)

• Third generation (3G) mobile technologies.

Chapter 11 provides in-depth information about wireless LAN technologies. The following areas are discussed:

• Wireless LAN security issues

• Wireless personal area networks (WPAN)

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