PERSONAL WIRELESS COMMUNICATION SYSTEMS The idea that a person could carry around with him a telephone booth of his own is a very attractive one. However, the technology required to make the telephone booth small and light enough for this to be possible, and furthermore convenient to carry, has been available only in the last 30 years. Mobile radio has been available in North America since the 1930s but they were exclusive in the hands of the police. | Telecommunication Circuit Design Second Edition. Patrick D. van der Puije Copyright 2002 John Wiley Sons Inc. ISBNs 0-471-41542-1 Hardback 0-471-22153-8 Electronic 11 PERSONAL WIRELESS COMMUNICATION SYSTEMS INTRODUCTION The idea that a person could carry around with him a telephone booth of his own is a very attractive one. However the technology required to make the telephone booth small and light enough for this to be possible and furthermore convenient to carry has been available only in the last 30 years. Mobile radio has been available in North America since the 1930s but they were exclusive in the hands of the police. Later taxicab operators installed radios in their vehicles. These mobile units were large heavy and electrical power hungry. They used amplitude modulation which is notorious for poor performance in the presence of electrical noise and there was more than enough noise generated by the ignition systems of the vehicles in which they were installed. Moreover they were operational in either the transmit or the receive mode at any given time they were of the push-to-talk type. The invention of the transistor and its progression to integrated circuits made it possible to reduce the weight and size of circuits and at the same time increase their capability and flexibility. These advances were accompanied by an enormous reduction in the amount of power required to operate transistor circuits. The stage was set for the introduction of the personal telephone booth . There are many applications in which radio plays a vital part. These go from remote keys for the automobile garage door openers pagers walkie-talkies cordless telephones to cellular telephones with access to the Internet. In this chapter we limit ourselves to a discussion of paging systems cordless and cellular telephones. The paging system was designed to send information from a base station to a mobile terminal. The mobile terminal has no capability to transmit information in the .
