Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-03-02
2001-12-11
Kincaid, Lester G. (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S422100, C455S561000, C370S338000
Reexamination Certificate
active
06330441
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication system providing voice and data communication services through LAN (Local Area Network) system and relates to a cordless communication system of a private branch exchange (PBX) system wherein plural radio base stations are present in a limited are.
2. Description of the Related Art
Generally, a personal computer which is equipped with a voice processor board and a network I/F (Interface) card is provided for managing a voice communication or a data communication of a PBX (Private Branch eXchange) system within a limited area of one firm location, that is, the voice processor is connected to a PBX switchboard through a telephone line and the voice communication is performed through the PBX switchboard. A wired network system such as LAN (Local Area Network) system is connected to the network I/F card and the data communication is practiced among personal computers connected to the network system. However, in this communication system, a large-scale wiring construction is necessary for the system to connect all personal computers which handle telephones provided for each persons to a telephone network. Furthermore, a massive PBX switchboard is necessary to assign one telephone line per person. Moreover, a telephone conversation is limited within the telephone network, when a voice processor board which is applicable for the telephone network is installed. In any cases, a call can be initiated only by a private line. Therefore, it is impossible to initiate or to answer to a call unless a person is on his private line, although the massive PBX switchboard is equipped or the voice processor board which is suitable for the network is installed.
In addition thereto, mobile radiotelephones such as PHS (Personal Handy-phone System) telephones are used for a communication system of a PBX system wherein the PHS telephones communicate with other telephones through radio base stations. The communication system is used in firms in conjunction with the LAN system. When a PHS telephone is moved from a service area of one radio base station which is hereinafter called an original station to another service area of another radio base station which is hereinafter called a new station, the PHS telephone receives a control signal from the new station and notifies the new station that the PHS telephone can communicate with the new station so that the PHS telephone can not receive a control signal from the original station any more. Service areas of plural radio base stations are assigned for overlapping partially or intentionally assigned to overlap in heavy traffic areas. All communication channels may become busy although plural communication channels which are called an individually assigned slot are provided for one radio base station. In this case, a mobile radiotelephone would not search a control signal from the other radio base station unless the mobile radiotelephone is moved into other service area while the mobile radiotelephone is receiving the control signal from the original station. Therefore, the mobile radiotelephone can not communicate with other radio base stations as far as staying in the same service area when all communication channels of the original station from which the mobile radiotelephone is receiving the control signal are occupied by other radio equipment although some communication channels of another radio base station which can be communicated with the mobile radiotelephone within the same service area are vacant. The mobile radiotelephone is obliged to keep waiting for a vacancy of the communication channel of the original station. Furthermore, the mobile radiotelephone searches the same original station once again and can not communicate with other radio base stations although a power switch of the mobile radiotelephone is turned off and turned on to search another radio base station due to a same process algorithm for searching radio base station.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a communication system which requires a reasonable sized PBX (Private Branch eXchange) switchboard not a massive PBX switchboard and the communication system assures a person of initiating a call or answering a call when he is not on his private line. Further, the communication system assists to communicate with other persons who are out of a network.
In addition thereto, when all communication channels of one radio base station are busy, wherein the radio base station is transmitting control signals to a mobile radiotelephone, the communication system provides a seamless communication by using a communication channel of another radio base station in a same service area whenever the communication channel of the radio base station is vacant.
In order to achieve the above object, the present invention provides, according to an aspect thereof, a radio base station and a circuit controller are connected to a private branch network wherein plural mobile radiotelephones can communicate with each other through the radio base station. Further, in case that telephone equipment are connected to the private branch network, or other telephone equipment are connected to an ISDN (Integrated Services Digital Network) network or an analog telephone network through an ISDN I/F (Interface) or a PSTN I/F (Private Switched Telephone Network Interface), the communication system controls the radio base station and the circuit controller and telephone equipment so that the mobile radiotelephones can communicate with telephone equipment connected to the private branch network or can communicate with other telephone equipment connected to the ISDN network or the analog telephone network.
According to another aspect of the present invention, a communication system is provided. When all communication channels of one radio base station are busy, wherein the one radio base station is transmitting control signals to a mobile radiotelephone, that is, there is no vacant communication channel at all, the control signals from the one radio base station is interrupted. The mobile radiotelephone can use a vacant communication channel of the other radio base station which has a vacant communication channel, wherein the mobile radiotelephone can communicate with the other radio base station through control signals of the other radio base station so that the control signals from the one radio base station is interrupted and the mobile radiotelephone is isolated from the one radio base station.
In more specific aspect of the present invention, there provided a communication system comprising plural radio base stations and a circuit control device. The circuit control device controls the communication system, wherein the circuit control device recognizes usage of respective communication channels of plural radio base stations and directs the radio base stations to start or to stop transmitting control signals of respective radio base stations.
Other objects and further features of the present invention will be apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings.
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Kumagai Nobuaki
Onodera Katsuya
Anderson Kill & Olick P.C.
Kincaid Lester G.
Victor Company of Japan Ltd.
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