Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1995-06-02
2001-05-08
Korzuch, William R. (Department: 2641)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S465000, C455S011100
Reexamination Certificate
active
06230008
ABSTRACT:
TECHNICAL FIELD
This invention relates to a communications system for access to the public switched network, through which a conventional fixed telephone set obtains access to the switched public network by means of a terminal fixed station that is connected, by radio, to a set of base stations of a wireless communications system.
BACKGROUND OF THE INVENTION
One of the major problems that telecommunications operating companies faced with is the need to install infrastructures to give service in certain areas of low subscriber density where the economic return is very poor as a result of the widespread geographical distribution of the customers.
This is particularly the case in the access part of the network in environments with a certain demand where, in addition, the installation and provision of these services have to be implemented rapidly.
To resolve these problems, in recent years use has been made of what is normally termed radio access, in which a set of base stations of wireless communications systems (cellular, point to multipoint, etc.) provide radio coverage for a certain zone in which are installed a number of “special” wireless terminals, which are cordless terminals of the type normally used in such communications systems but into which a line interface circuit has been incorporated, while personal interfaces (microphone, loudspeaker, keypad, display element) have been suppressed. This line interface performs the functions of conversion required for both directions of transmission, so that, from a conventional telephone set connected to this terminal, it is possible to offer the same kind of functions as with a fixed telephone connected directly to the public switched network.
Among these functions are to be found those of four-to-two wire conversion, user signal tone generation, dial signal conversion, etc.
In this way it is possible to have a set of fixed telephones that have access to the public switched network by means of a wireless communications network. There is no mobility provided by this communications network, so that a new wireless communications system would be necessary with the consequent duplication of equipment and the possible saturation of the radiofrequency spectrum, should the subscribers also wish to have cordless telephones to provide a desired mobility within an area similar to that covered by the wireless network.
DISCLOSURE OF INVENTION
The object of this invention is to develop, on the actual system infrastructure described above, functions of mobility within a closed area constituted by the same set of base stations as are employed to implement the access part of the fixed terminals to the network.
The system according to the invention comprises a set of base stations that are connected to a local telephone exchange, and a set of wireless terminal stations which communicate, by radio, with at least one of the base stations in order to offer thereby telephone services to telephone sets connected, by subscriber lines, to the wireless terminal stations. In this system, the wireless terminal stations are inhibited or enabled by control means depending on whether or not a cordless telephone is used which, in an alternative form to that of the wireless terminal stations, also communicates directly with the base stations in the event that these cordless telephones are to be found inside the area of coverage of any of the system base stations.
When the cordless telephones are outside the range of any of the system base stations, the wireless terminal stations have, in addition, and so as to offer a certain local mobility, a radio transceiver that works as a repeater and which is activated by the control means when the cordless telephone is used to communicate with the base stations through the wireless terminal station and the radio transceiver.
In this way it is possible to provide mobility for fixed terminals that make use of wireless access in determined zones of coverage and even outside these zones. A given subscriber can have a fixed conventional telephone or, if he so prefers, a mobile telephone in the area of coverage of a base station system and in an area of coverage of a small repeater that allows a degree of local mobility.
In addition, by the use of radio transceivers of the type dislcosed herein, which incorporate directional antennas, it is possible to extend the area of coverage economically to any subscriber geographically isolated from the base stations, at the extremity of which a wireless terminal station is connected and to which a fixed telephone set is connected in a manner similar to that described above.
BRIEF DESCRIPTION OF THE DRAWING
The system so formed is of special application in the network access part where a wireless communications system of the DECT (Digital European Cordless Telecommunications) type is used.
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Garcia Pedraja Fidel
Gomez Solera José Luis
Redondo Iglesias Alfredo
ALCATEL N.V.
Korzuch William R.
Lerner Martin
Ware Fressola Van der Sluys & Adolphson LLP
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