Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1998-09-18
2001-07-03
Cumming, William (Department: 2684)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C380S029000
Reexamination Certificate
active
06256514
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to communications systems and more particularly to radio personal communications systems for use within wide area cellular networks.
BACKGROUND OF THE INVENTION
Radio communications systems are increasingly being used for wireless mobile communications. An example of a radio communications system is a cellular phone network. Cellular radio communications systems are wide area communications networks which utilize a frequency (channel) reuse pattern. The design and operation of an analog cellular phone system is described in an article entitled
Advanced Mobile Phone Service
by Blecher, IEEE Transactions on Vehicular Technology, Vol. VT29, No. 2, May, 1980, pp. 238-244. The analog mobile cellular system is also referred to as the “AMPS” system.
Recently, digital cellular phone systems have also been proposed and implemented using a Time-Division Multiple Access (TDMA) architecture. Standards have also been set by the Electronics Industries Association (EIA) and the Telecommunications Industries Association (TIA) for an American Digital Cellular (ADC) architecture which is a dual mode analog and digital system following EIA/TIA document IS-
54
B. Telephones which implement the IS-
54
B dual mode architecture are presently being marketed by the assignee of the present invention. Different standards have been promulgated for digital cellular phone systems in Europe. The European digital cellular system, also referred to as GSM, also uses a TDMA architecture.
Proposals have recently been made to expand the cellular phone network into a radio personal communications system. The radio personal communications system provides mobile radio voice, digital, video and/or multimedia communications using radio personal communications terminals. Thus, any form of information may be sent and received. Radio personal communications terminals include a radio telephone, such as a cellular telephone, and may include other components for voice, digital, video and/or multimedia communications.
A radio personal communications system includes at least one telephone base station, also referred to herein as a “base station”. A base station is a low power transceiver which communicates with a radio personal communications terminal such as a cellular telephone over a limited distance, such as tens of meters, and is also electrically connected to the conventional public wire telephone network. The base station allows the owner of a radio personal communications terminal to directly access the wire telephone network without passing through the cellular phone network, whose access rates are typically more costly. When located outside the range of the base station, the personal communications terminal automatically communicates with the cellular phone network at the prevailing access rates.
A major problem in implementing a radio personal communications system is security for communications between the base station and the personal communications terminal. Modern cellular telephone networks include security systems and methods to prevent eavesdropping and telephone fraud. Eavesdropping may be prevented by using encryption of radio transmissions between a cellular phone and a cellular network. Fraud may be prevented by preventing radio telephone transmissions between the cellular phone and the cellular network unless identification Information is successfully exchanged between the cellular phone and the cellular network. Existing cellular systems, such as the AMPS system, the ADC system, and the GSM system each include their own security systems and methods. Security should not be compromised by communications between the radio personal communications terminal and the base station of a radio personal communications system.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved radio personal communications system including a base station and a radio personal communications terminal, and methods for using the same.
It is another object of the present invention to provide radio personal communications systems which do not compromise security of a wide area cellular system with which they interact.
In the present invention, a base station connects a wire telephone network to a radio personal communications terminal, also referred to herein as a “cellular terminal” or simply a “terminal”, within a local region of a wide area cellular network. The base station includes a wire telephone network connector, for connecting the base station to the wire telephone network. The base station relays cellular verification signals between the wide area cellular network and a cellular terminal via the wire telephone network connector. Thus, wireless telephone calls which are routed to the cellular terminal via the base station, when the cellular terminal is within the local region covered by the base station, may be secured by exchange of data between the cellular network and cellular terminal over the wire telephone network via the wire telephone connector and the base station. Calls from the public switched telephone network including the wide area cellular network which are routed through the base station can thus employ the same security systems and methods which are employed by the wide area cellular network.
In a preferred embodiment, the telephone base station includes a coupler which is adapted for cooperatively mating with a cellular terminal which is parked in the base station. The coupler couples the cellular security information between the cellular terminal and the base station. Cellular security information can include encryption keys that are relayed from the wide area cellular network to the cellular terminal via the wire telephone connector for use in encrypting communications with the base station.
Enhanced security is provided by relaying the security information between the cellular terminal and the base station when the cellular terminal is parked in the base station, to avoid their radio frequency transmission. Exchanged security information can also include authentication signals that bilaterally verify both the identity of the cellular phone to the cellular network and the identity of the network to the phone, as described in U.S. Pat. No. 5,390,245 and U.S. Pat. No. 5,091,942, the disclosure of both of which are hereby incorporated herein by reference.
As an alternative to physically mating the terminal with the base however, signals may be relayed between the cellular terminal and the cellular network, via the base station and the wire network connector, by using radio frequency transmission over cellular frequencies, between the cellular terminal and the base station. This radio frequency transmission may be necessary when verification and encryption signals are exchanged upon reactivation of the base station, when the cellular terminal moves outside the local region and then returns to the local region. Telephone communication between the terminal and the public switched network via the base station is prevented unless the relayed cellular verification signals indicate that the radio telephone communication is authorized.
The base station and the cellular terminal may also exchange local verification information, separate from the cellular verification information, for communications between the base station and terminal when the terminal is within the local region and is receiving communications via the wire telephone network connector from the wire telephone network. Thus, the wide area cellular network need not be contacted in order to provide security for local communications between the cellular terminal and the base station within local region for calls originating from the wire telephone network.
It will be understood by those having skill in the art that the local authentication procedure preferably uses the same protocol as the cellular telephone verification procedure. The local authentication key is preferably exchanged when the cellular terminal is parked in the base station, via the coupler, but m
Dent Paul Wilkinson
Haartsen Jacobus Cornelius
Cumming William
Ericsson Inc.
Myers Bigel & Sibley & Sajovec
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