Cellular and PCS
Cellular and PCS systems are comprised of a set of radio towers that are strategically distributed over a geographical area in order to provide a continuous service coverage area. A mobile switching center (MSC) provides the switching and control functions necessary to connect calls from the public switched telephone network (PSTN) to the individual mobile telephones. The MSC also manages the radio resources within the entire network.
Several service providers (carriers) within a particular geographical area can provide wireless services simultaneously as long as they use a different set of radio frequencies that do not interfere with each other. Specific sets of radio frequencies are allocated for use in cellular communications systems. Typically a government agency is responsible for assigning these frequencies and licensing them to specific service providers.
Paging
Paging is a wireless system that is capable of delivering message to one or more people whose exact whereabouts are unknown by the sender of the message. Users typically carry a small paging receiver that displays a numeric or alphanumeric message displayed on an electronic readout. It also could be sent and received as voice message or other data. Pager systems may be classified based upon their capabilities as numeric, alphanumeric, tone, or voice.
Paging networks are comprised of terrestrial based antennas all interconnected by means of some other type of physical network. Satellite transmission systems are often used to distribute the messages to multiple towers for retransmission. The use of satellite interconnection systems permits regional, nationwide, or global paging service. Some paging systems are capable of providing two-way communications.
Each pager in the network has a unique identifier (address) that is stored to the pager’s memory. This address is also stored in the paging network. When an incoming telephone call accesses the pager customer’s account, the network transmits the address of the pager on its radio tower. In addition to sending a specific paging address, the system may send other digits, text, or even voice information that follows the addressing message.
Wireless Data
Wireless data networks transfer data between network access points (wireless data devices) through radio transmission and are primarily designed to transfer data from one point to one or more points (multipoint). These networks may be composed of a variety of communication systems including: mobile data terminals, radio access nodes, packet switching networks. Wireless data networks provide a variety of services including: equipment status monitoring, dispatch services, vehicle and goods tracking, credit card validation, and include wireless Internet access.
Broadcast
Broadcasting is a process that sends voice, data, or video signals simultaneously to group of people or companies in a specific geographic area or who are connected to the broadcast network system (e.g., satellite or cable television system). It is typically associated with radio or television radio transmission systems that send the same radio signal to many receivers in a geographic area. Broadcasting can also be applied to wired distribution or point-to-point networks where all users that are connected to the network can receive the same information signal.
Figure below shows the different types of wireless networks. This diagram shows a private land mobile radio system, television broadcast system, paging system, mobile telephone system, and satellite communication system. Although all wireless networks can transmit information from one point to another, different types of networks better suited to provide specific types of services (e.g., paging compared to television broadcasting).
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