Nec Corporation

Nippon Electric Co., Ltd.

Ryuhei Fujiwara

Toshiyuki Sashihara

Seiji Shimizu

Tomokazu Kai

Keiko Shimada

Kenichi Ariga

Takashi Asano

Shuuji Suzuki

Hidetoshi Nakahara

Yasuo Fukazawa

Yukitsune Furuya

A visible light communication apparatus enables an operator to visually recognize a communication state during visual light communication. The apparatus includes a light emitting section which emits visible light and which includes a modulator, a visible light emitter, a light emitting element and an emission control section which includes a controller and which controls an emission state of the visible light from the light emitting section. The apparatus controls the emission state according to the communication state. It is hence possible for the operator to visually perceive the communication state during the visible light communication.

Apparatus, system, method, and program for visible light communication

There is provided a visible light control apparatus including: a modulation unit (corresponding to a PPM signal generation circuit, a subcarrier generation circuit, and a first AND circuit) that modulates a subcarrier and thereby generates a modulated signal; a visible light control unit (corresponding to a driving circuit) that controls blinking of visible light which contains information based on the modulated signal modulated by the modulation unit and allows the visible light to be emitted at a predetermined emission time ratio; and an emission time ratio control unit (corresponding to a dimming signal generation circuit, an inverting circuit, a second AND circuit, and an OR circuit) that changes the predetermined emission time ratio and allows the visible light to be emitted at the changed emission time ratio.

Visible light control apparatus, visible light control circuit, visible light communication apparatus, and visible light control method

Private data in an EEPROM () is erased in a data erasing procedure when pulling out an SIM card () from a mobile telephone (). Before being erased, the private data is encrypted in an encryption procedure and it is transferred and recorded to an external memory (). The private data encrypted and recorded to the external memory can be reused when the SIM card is used in another mobile telephone. Furthermore, it is possible to prevent the external memory from being left behind when the SIM card is pulled out by interfacing a lock mechanism of a card mounting section () with that of a memory mounting section ().

Mobile telephone using subscriber card

In a data distribution method of distributing data selected for each of a plurality of user terminals from a distribution center to each user terminal through a communication network, the distribution center is notified of the contents of user operation for the data distributed to the user terminal. The distribution center receives a notification from the user terminal. Data to be subsequently distributed to the user terminal is selected by using the contents of the user operation contained in the notification from the user terminal. The selected data is distributed to the user terminal. A data distribution system, data distribution apparatus, and recording medium are also disclosed.

Data distribution method, system, and apparatus and recording medium recording method

Disclosed is a service identification tag for being used in accessing an information transmission server on the Internet. The tag is formed combining an exclusive graphic pattern that can be recognized by a human, and an identification code that can be read by a reading unit. Also disclosed is a communications system having: a service server provided with an identification code/URL conversion table; an information transmission server provided with an information storage; and a terminal unit that is connected through a radio or wire communication network to the information transmission server, the terminal unit having a function for communicating with a Web server. The terminal unit makes a unique link to the service server, reads the identification code from a service identification tag, sends the identification code to the service server, and receives the URL information of the information transmission server corresponding to the identification code from service server.

Service identification tag and communications system using the same

A portable information terminal is connected through a radio base station and the like to the Internet. Furthermore, a music server, a mail server and a distribution center are connected to the Internet. The distribution center distributes data stored in the music server and mail server. The distribution center includes a distribution server, a distribution data store memory in which data for the distribution is transiently stored and a radio unit which wirelessly distributes data to the portable information terminal. When accesses are concentrated on the music server from the distribution information terminals, the music server transfers a file including music data to the distribution center. The distribution center wirelessly transfers the file to each of the portable information terminals with temporal dispersion. Thus, even if the accesses for the communications are temporarily concentrated on the particular apparatuses such as the server, employing the above structure allows the communication system to avoid the occurrence of an overload condition.

Communication system capable of reducing communication load

A radio wave from a base station, which is received in a radio unit (TRX) of a terminal, contains an identification signal of the base station. A base station identification signal detecting unit detects the base station, from which the radio wave is received, and the CPU makes a judgment. The input level of the received radio wave and the time can be known from an electric field intensity measuring unit and a clock , respectively. The terminal has a table, in which times and places meeting communication conditions are registered. A communication time is predicted from the data quantity to be transmitted, and the time and place of the connection trial start are selected. A link is set up periodically at a time and a place meeting conditions, which are determined with reference to the table, thus permitting automatic exchange of data, if any, to the terminal or link destination.

Automatic call making system and a mobile radio terminal

A radio information terminal comprises a radio unit, functioning as a proxy server to a portable computer when it is connected to the portable computer and unable to receive a control radio wave from a base station, and synchronizing information received from the portable computer with information of an original server via the base station when it comes to receive the control radio wave from the base station.

Radio information terminal capable of facilitating on-line operation by a portable computer

When receiving voice mail data from a server 11, a terminal 13 or 14 stores the voice mail data in a memory. Subsequently, the data is read, converted to a voice and outputted. Furthermore, when inputting a voice mail during the output of the voice, the terminal 13 or 14 generates a signal including a voice mail data reading position of the memory at the time of input, data of the inputted voice mail and a self terminal identification number as a mail editing signal to transmit the signal to the server 11. When receiving the mail editing signal, the server 11 inserts or attaches and re-accumulates the voice mail data in the mail editing signal to a position indicated by the mail editing signal of a memory region of a memory 15 allocated to a transmitting-end terminal.

Voice mail system

In a radio packet communication system between a master station and a plurality of slave stations, a contention mode is switched to a polling mode or vice versa in accordance with the amount of transmission data reserved by the slave stations to the master station.

Radio packet communication system capable of avoiding transmission

In a radio broadcast system constituted by a base station and a plurality of subsidiary stations located at various portions around the base station, each subsidiary station includes a detection unit for detecting an error in received data, and a unit for transmitting a burst retransmission request signal (NAK signal) upon detecting an error in the received data, and transmits no signals for a predetermined limited time, except the NAK signal for indicating reception of broadcast data containing an error. The base station either detects the NAK signal within the limited time or regards detection of a radio carrier having a predetermined time length as detection of the NAK signal.

Radio broadcast system with improved reception of an NAK code

There is disclosed a method for controlling the position of a mobile host in a local area network (LAN), whereby the movement of the mobile host out of a certain LAN can be quickly detected even when the mobile host transmits no frames and invalid traffic can be reduced. A server 3 duplicates a learning function table in a bridge device 2 at each specified time. Location confirmation is performed for the currently connected mobile host based on this duplicated information at each specified time. If the mobile host gives no response to the location confirmation, the movement of this mobile host is determined and the learning function table in the bridge device 2 is renewed. Thus, even when the mobile host is moved out of the LAN and no frames are transmitted therefrom, the movement of the mobile host can be quickly detected and invalid traffic can be reduced.

Method and device employing location confirmation by a server or a

In a radio conference system of the present invention, a hub station 1 sends information to a plurality of terminal stations 2 while adding an error checking code thereto. The terminal stations 2 each sends, on detecting an error out of the information received from the hub station 1, a resend request signal including an ID (Identification) code assigned to the terminal station. The hub station 1 counts the number of times of receipt of the resend request signal on a terminal station basis. When the number of the resend request signals received from any one of the terminal stations 2 exceeds a preselected value, the hub station 1 displays alarm information indicative of the above terminal station.

Radio conference system and terminal unit therefor

In an echo suppressor for suppressing an echo resulting from acoustic coupling in a telephone apparatus, an attenuator attenuates a transmission signal level with reference to a first level signal representative of a level of a reception speech signal which is supplied to the telephone apparatus. Supplied with the reception speech signal through an input terminal, the first detecting arrangement detects the reception speech signal to produce the first level signal. It is a matter of course that a receiver converts the reception speech signal into a reception speech sound. A microphone produces a transmission speech signal in response to a transmission speech sound.

Echo suppressor capable of suppressing an echo resulting from acoustic

In a speech decoding apparatus (100) supplied with an input speech signal (101) comprising successive blocks, each comprising a digital speech signal and an error detecting code signal, an error detector (8) detects an error in the digital speech signal by the error detecting code signal for each block to produce error detection pulses whenever the error detector detects the error. The error detector also produces the digital speech signals of the blocks. A speech decoder (9) decodes the digital speech signals of the blocks into an analog speech signal. A measuring circuit (102) measures, as a measured value, the number of the error detection pulses during a predetermined time interval. A comparator (15) compares the measured value with a reference value to produce a command signal when the measured value is greater than the reference value. A generator (12) generates an alarm signal in response to the command signal.

Growing community of inventors

Tokyo, Japan

Ryuhei Fujiwara