s based on GSM technology but operates in the 1,800-MHz fre- quency band and provides much higher capacity than GSM in terms of the number of users. DCS-1800 is a technology for the European implementa- tion of personal communications network (PCN), but it is in use in other parts of the world as well. The goal of PCN is to provide a mass mobile telecom- munications service in urban areas. 5.4.5.3 Personal Communications Network and Service Note here that the term personal communications refers to cellular mobile communications in which a call is routed to a person who carries a terminal instead of a fixed terminal location as in the conventional fixed telephone network. The PCN and personal communications service (PCS) simply refer to microcellular systems that emphasize low-cost and high-capacity cellular service and a hand-portable terminal with a long battery life. In Europe the DCS-1800 system is also called PCN because it is the implementation tech- nology for PCN. In the United States several digital technologies are used to implement the high-capacity cellular service that is known as PCS. These technologies are GSM-1900 (GSM at 1,900 MHz), NADC (known also as D-AMPS or US-TDMA), and CDMA. All of these network technologies are briefly introduced next. Note that all systems at higher frequency bands (1,800-1,900 MHz) are referred to as personal communications systems and systems below 1 GHz are referred to as cellular systems. 5.4.5.4 PCS-1900 As just mentioned, many technologies are specified for implementation of PCS in the United States and one of them is GSM-1900. GSM-1900 is based on GSM/DCS1800 technology but adapted to the frequency alloca- tion of North America. These three GSM-based systems are SO similar that with the help of a multimode mobile station a subscriber can use all of these networks with the same terminal and subscription (same subscriber card). We illustrate the structure and operation of this system in Section 5.5 as an example of a modern digital cellular system. 5.4.5.5 North Amer