The invention relates generally to wireless communication systems and, more particularly, to wireless communication system devices that use radio frequencies for transmitting and receiving voice and data signals within an internal communications network and to an external communication networks.
Wireless communication systems continue to grow, particularly in the areas of cellular and digital telephony and in paging systems. Wireless systems are especially popular in remote areas of the world that have limited wired service because of the cost and difficulty of building a wired infrastructure.
Traditional wireless communication systems such as cellular telephones use radio communication between a plurality of subscriber units within the synchronous wireless system and between subscriber units and the Public Switched Telephone Network (PSTN) for calls that are outside of the wireless system. Most of these systems are characterized by wireless mobile telephone units communicating synchronously with base stations that are connected to centralized mobile switching centers (MSC), which are in turn connected to the PSTN. The centralized MSC performs a number of functions, including routing wireless mobile units calls to other mobile units and wired (land-line) users and routing land-line calls to mobile units. At no time do these traditional wireless communications systems allow the handset to interface with the PSTN directly. The very core of the centralized wireless communications theory requires every PSTN interface to be made through an MSC. This is the only interface allowed.
Others' systems use point-to-point radio communication where mobile units may communicate with other mobile units in the local area. They send origin and destination address information and make use of squelching circuits to direct the wireless transmission to the correct destination address. Most of these systems do not appear to provide a connection to a PSTN to send and receive calls outside the wireless network. This type of system is decentralized, but because of the decentralization, collecting accurate billing information may be a problem.
Another form of wireless system is called a local multipoint distribution service (LDMS). In an LMDS system, a local area or cell that is approximately 4 km in diameter contains fixed base stations, geographically distributed throughout the local area. One or more antennas within the local area receive calls from the fixed base stations and relay the calls to other fixed base stations. In order for the system to work, the fixed base stations must be within the line-of-sight path of at least one of the antenna units. The LDMS does not provide for mobile stations. Calls can only be routed within the local area and not to an external network. The system is essentially a centralized system within a local area. If one station is not within the line of sight of the antenna, it is effectively cut off from communication.
There is a need for decentralized wireless communication system that is capable of handling voice and data communication that allows for a multiplicity of communication paths. It is desirable to have an ability to call on bandwidths as needed, to provide local communication links, and to access links to external networks. Such networks may include public switch telephone networks, high speed-broadband cable, Internet, satellites and radio emergency networks. It is desirable to have a system that does not require a centralized switching center, provides for secure operation, allows for control of the operational state of the internal network, provides for emergency notification and provides a way to collect revenue from the system. It is also desirable to provide alternate direct-path communication between wireless handsets and the PSTN, without centralized switching. Such an interface augments the conventional path routing and reduces call loads on any central communications interface.