In the telephone networks, the circuit between the subscriber's equipment (. telephone set) and the local exchange in the central office is called the `subscriber loop' or `local loop'. Traditionally, the copper wire has been used as the medium for local loop to provide voice and voice-band data services. Since 1980's, the demand for communications services has increased explosively. There has been a great need for the basic telephone service, . the plain old telephone service (POTS) in developing countries. On the other hand, in the industrialized countries, the demand for high-speed data and multimedia services at home and/or office. | Wireless Local Loops Theory and Applications Peter Stavroulakis Copyright 2001 John Wiley Sons Ltd ISBNs 0-471-49846-7 Hardback 0-470-84187-7 Electronic 13 Current and Future Services Using Wireless Local Loop WLL Systems Dong Geun Jeong and Wha Sook Jeon Introduction In the telephone networks the circuit between the subscriber s equipment . telephone set and the local exchange in the central office is called the subscriber loop or local loop . Traditionally the copper wire has been used as the medium for local loop to provide voice and voice-band data services. Since 1980 s the demand for communications services has increased explosively. There has been a great need for the basic telephone service . the plain old telephone service POTS in developing countries. On the other hand in the industrialized countries the demand for high-speed data and multimedia services at home and or office has increased continuously. These requirements have been a motivation for innovation in local loop. There are two remarkable challenges in local loop technologies. One is mainly from the expansion of landscape in service types. According to drastic growth of Internet to access Internet at home or office became a usual lifestyle today. Moreover to enjoy multimedia services at home will not be strange in near future. These services require broadband local loop systems. To deal with this situation in short term the digital subscriber line DSL technologies including high-bit-rate DSL HDSL asymmetrical DSL ADSL and very-high-bit-rate DSL VDSL have been studied and developed 1 . Another technical advance on which we will focus in this chapter is the wireless local loop WLL adopting radio as the transmission medium. WLL is often called the radio local loop RLL or the fixed wireless access FWA . And WLL services are also referred to as the fixed cellular services . WLL has many advantages from the viewpoints of the service providers and subscribers 2-8 The WLL approach .
