 xDSL transmission rates are calculated Cable and hybrid fibre cable systems characteristics Principles of optical fibre communications Combination of fixed line systems for higher transmission rates Broadband Telecommunications Technologies and Management, First Edition. Riaz Esmailzadeh. C 2016 Riaz Esmailzadeh. Published 2016 by John Wiley & Sons, Ltd. Companion Website: www.wiley.com/go/BTTM Broadband Telecommunications Technologies and Management Historical Note Packet-switched computer data communications bet- ween a computer terminal (such as the DEC VT100 pictured [1])¹ and a mainframe computer emerged in the 1960s. The subsequent growth in importance and value in the 1970s and 1980s led to major changes in the telecommunications industry. These included theoretical work in packet switching and queuing the- ories as well as development of network equipment to facilitate transmission of digital traffic over wide areas. As a result, a new 'digital' infrastructure became necessary to support these 'wide-area networks' and connect customer premises with exchanges and com- puter centres, and with each other. The new digital infrastructure used fixed lines media, that is wired as opposed to wireless, and a number of standards emerged to specify how telecommu- nications infrastructure could be built on this fixed media. The traditional voice telecommunications network as discussed in Chapter 3 comprises a number of local, regional and international exchanges and the connecting infrastructure is gen- erally made of copper wires. A subscriber's premises is commonly connected to a local exchange using twisted pair copper wires, whereas exchanges are connected by high capacity links: copper wires, coaxial cables and more recently optical fibres. These systems use fre- quency division multiplexing (FDM) and time division multiplexing (TDM) technologies to simultaneously transport multiple voice calls. Digital modulation of voice necessitated changes to the network equipment at both sub- scriber premises and exchanges