Fujitsu Corporation

Tohoku Electric Power Company, Inc.

Aomori Telemessage, Inc.

Toshihiro Yabe

Norio Sasaki

Ryota Akiyama

Makoto Takahashi

Kazutoshi Motohashi

Hirokazu Murakami

Masaru Ohmori

Masatoshi Nakada

Masanori Takano

A wireless communication system containing at least one transmission apparatus and at least one communication terminal. The transmission apparatus transmits a wireless signal representing a bit sequence containing at least a predetermined number of bit errors, to the communication terminal. The communication terminal receives the wireless signal to regenerate the bit sequence. The communication terminal then examines the bit sequence represented by a received wireless signal to determine whether or not the number of bit errors contained in the bit sequence is equal to or greater than a predetermined number. When it is determined that at least the predetermined number of bit errors are contained in the bit sequence represented by a received wireless signal, the operation of the communication terminal is made inactive. Further, the transmission apparatus may transmit a wireless signal representing a bit sequence containing no pattern coinciding with a predetermined frame synchronization pattern, to the communication terminal. The communication terminal receives the wireless signal to regenerate the bit sequence. The communication terminal then examines the bit sequence represented by a received wireless signal to determine whether or not the bit sequence contains the predetermined frame synchronization pattern. When it is determined that the bit sequence does not contain the predetermined frame synchronization pattern, the operation of the communication terminal is made inactive.

Wireless communication system compulsively turning remote terminals into

A radio calling system includes a central control station simultaneously broadcasting a calling signal of an arbitrary pager terminal, and a plurality of radio transmitting stations coupled to the central control station. The plurality of radio transmitting stations simultaneously transmit the calling signal received from the central control station at the same radio frequency. The calling signal transmitted from the radio transmitting stations reach the arbitrary pager terminal and at least a neighboring one of the radio transmitting stations. At least an arbitrary one of the radio transmitting stations includes a first relay for relaying the calling signal received from the central control station, a second relay which has a receiver part for receiving the calling signal transmitted from a radio transmitting station other than the arbitrary radio transmitting station, and a storage relay part for storing the calling signal received by the receiver part and for transmitting the stored calling signal during a time in which no transmission is made by the radio transmitting stations other than the arbitrary radio transmitting station. A switching circuit coupled to the first and second relays carries out switching to enable one of the first and second relays, depending on whether or not a communication failure exists between the central control station and the arbitrary radio transmitting station.

Radio transmitting system having back-up radio receiver operable in

A control channel monitoring system is for a mobile communication system in which base stations independently control radio zones which are arranged in a cellular array. A mobile station accesses the base station using at least one control channel. Each of the base stations constantly transmits using the control channel in common according to a time division multiple access. A voice signal is transmitted between an arbitrary base station and the mobile station according to the time division multiple access via a speech channel. The control channel monitoring system includes a monitoring part for carrying out a monitoring operation in which a transmission quality of the radio zones is monitored by monitoring the control channel. A selection standard is obtained for the radio zone as the mobile station moves. A silence judging part determines whether the voice signal indicates a silent state based on a level of the voice signal. A monitor control part monitors the result of the silence judging part for the voice signal which is exchanged via the speech channel within a certain time which combines each time slot of the control channel corresponding to the adjacent radio zone and a time it takes for the frequency synthesizer to switch the speech and control channels before and after each time slot. The monitor control part switches the oscillation frequency of the frequency synthesizer to a specified frequency in the time slot based on the monitored result to start the monitor process of the monitoring part.

Control channel monitoring system

Prior to the sale of a personal communication terminal, a secret key is generated and stored in the personal communication terminal in accordance with an application made from the manufacturer to the carrier. At this time, the communication between the manufacturer and the carrier is performed in the form of secret communication with a signature that conforms to a public key system. After the sale, an identification number encrypted with the same key as the secret key is transmitted to the personal communication terminal in accordance with an application made from the user to the carrier. Using the stored secret key, the personal communication terminal decrypts the received identification number for storage therein.

Method of registering identification number in personal communication

A line control method is applied to a mobile communication system in which a mobile station communicates with one of a plurality of base stations which are installed within the same zone via a speech channel of the one base station, where the base stations have a common control channel. The line control method includes the steps of (a) storing timing information which indicates access timings of the mobile station with respect to each of the base stations and is received via the control channel, and (b) receiving control information which indicates a result of allocation of free speech channels in an arbitrary base station with respect to each call based on a predetermined call processing procedure of the arbitrary base station via the control channel, and switching the access timing of the mobile station from an access timing with respect to the arbitrary base station to an access timing with respect to one of the base stations other than the arbitrary base station and stored in the step (a), so that the mobile station communicates with the one of the base stations via a speech channel which is determined by the control information.

Line control method and system

An in-house paging system includes a call controller connected to an in-house switching unit for providing an interfacing process in response to a call request from an extension terminal. A plurality of transmitting units are connected to the call controller through a signal line and a power source line. A pager terminal is provided for notifying a maintenance staff of a call signal from a transmitting unit on receipt of the signal. The transmitting unit comprises a detecting unit for detecting whether or not an abnormal condition arises in a signal line or a power source line to a call controller and a signal/power-source line abnormal signal transmitting unit for transmitting abnormal condition information to the pager terminal when the detecting unit detects an abnormal condition in the signal line or the power source line. A battery as a backup power supply unit is used in case of power disconnection.

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Kawasaki, Japan

Toshihiro Yabe