Fujitsu Corporation

Nec Infrontia Corporation

Masato Hori

Yoshikazu Kobayashi

Akira Oshima

Takashi Sasaki

Yasuhiro Arai

Kenichi Miyama

Kumiko Maruo

Yoichi Ueda

Makoto Shimizu

Kentaro Fukushima

Noriyasu Suzuki

A transmission apparatus includes a logic circuit for performing a predetermined process, and outputting a logic output signal depending on the process, an open-drain signal generation circuit, connectable at an input terminal to the logic circuit and at an output terminal to a pull-up resistor, and a transmission path failure determination circuit for determining whether there is a failure in a transmission path which transmits a signal outputted from the logic circuit via the open-drain signal generation circuit, wherein the transmission path failure determination circuit includes an edge waveform information obtaining circuit for obtaining edge waveform information indicating a waveform of at least one of a rising edge and a falling edge of an application signal, and a failure determination circuit for determining whether the edge waveform information satisfies a predetermined condition, and outputting a failure signal indicating that there is a failure in the transmission path.

Transmission apparatus and transmission method

A control apparatus that controls one or more first communication apparatuses and one or more second communication apparatuses configured to identify a logic level of a signal, the control apparatus includes a memory; and a processor coupled to the memory and configured to: acquire, from one of the one or more second communication apparatuses, a length of an undefined time period during which a level of the signal is undefined; determine, based on the length of the undefined time period, a length of a protection time period indicating a time period during which a logic level of the signal received by the second communication apparatus is maintained at a same level; and determine, based on the length of the protection time period, a rate of a signal transmitted to one of the one or more second communication apparatuses by one of the one or more first communication apparatuses.

Control apparatus, electronic device, and control method

A clock conversion apparatus comprising, an elastic store memory in which data are written in synchronization with a first clock and from which data are read out in synchronization with a second clock, a phase comparator for detecting phase difference between a third clock obtained by imparting a first variable phase shift to a divided clock of the first clock and a fourth clock obtained by imparting a second variable phase shift to a divided clock of the second clock, and an oscillator for generating a clock having frequency in accordance with the phase difference as the second clock.

Clock conversion apparatus with an elastic store memory from which data is written in synchronization with a first clock and read out in synchronization with a second clock

A critical threshold value of the number of connections of VoIP communication by a wireless LAN is set to an access point apparatus. The access point apparatus records identification information of terminals each of which has transmitted a request for connection of VoIP communication. After the number of terminals whose identification information have been recorded reaches the critical threshold value, the access point apparatus transmits a packet indicating release an association to a terminal whose identification information is newly recorded.

VoIP communication control method and access point apparatus

A VoIP system has a VoIP server and plural clients. The client transmits paging data as multicast packets addressed at a specific multicast address, to other clients. In response to a request from the client, the VoIP server transmits multicast packets of MOH data to the other clients. At this time, whether the other clients can receive multicast packets is determined. To the clients that are determined to be capable of receiving multicast packets, transmission data is sent in the form of multicast packets. To the client which belongs to a router and is determined to be incapable of receiving multicast packets, the transmission data is sent as unicast packets. It is thus possible for the VoIP system to support paging and MOH in the form of multicast packets, with respect to clients incapable of receiving multicast.

VoIP system, VoIP server and client, and multicast packet communication method

According to an embodiment, previous data group input time is subtracted from current data group input time in order to obtain a difference time each time a data group is input. The difference time is subtracted from a packet transmission interval in order to obtain an interval difference. The interval difference is added to a total difference time. If the total difference time is not greater than the first predetermined value, then the input data group is transmitted as a packet. Otherwise, the input data group is discarded and the total difference time is initialized to a value obtained by subtracting the packet transmission interval from the first predetermined value, if the total difference time is greater than the first predetermined value.

Packet transmission control method, packet transmission control apparatus and packet transmission control program product

A first wireless LAN base station is in an active state. A second wireless LAN base station is in a power off state or a power save mode. The first wireless LAN base station and the second wireless LAN base station are disposed in the same support area. When a fault occurs in the first wireless LAN base station and a communication state of the wireless LAN deteriorates, the first wireless LAN base station detects the fault and places the second wireless LAN base station in the active state. When the first wireless LAN base station confirms that the second wireless LAN base station has been placed in the active state, the first wireless LAN base station sends setting thereof to the second wireless LAN base station. When the first wireless LAN base station confirms that the setting of the second wireless LAN base station is the same as the setting of the first wireless LAN base station, the first wireless LAN base station enters the power off state or the power save mode.

Duplex system of wireless LAN base stations

In a wireless LAN communication system, a communication mode is automatically switched between an infrastructure mode and an ad-hoc mode. Communication between two stations is started in the infrastructure mode. Packets transmitted in an infrastructure network are monitors to detect a packet transmitted to an access point and addressed, as a final destination, to one's own station or a destination station. If such a packet is detected, it is determined that a transmitting or source station is in a state that allows an ad-hoc communication. A channel searcher of the access point searches for available channels of an ad-hoc network. A switching controller selects one of the available channels and transmits information indicating the selected channel to the source and destination stations. In response to receiving the information indicating the selected channel, the source and destination stations starts direct communication using the selected channel of the ad-hoc network. The selection of the channel may be performed by a station. Associated data may be stored in a temporary data storage unit.

Wireless LAN communication system

Prior to the initialization, CPU of information processing equipment makes a decision about whether a communication line has been connected to a connector or not. When the two are connected, the CPU does not carry out the initialization and shifts xDSL modem to lower power consumption mode. The connection is checked as follows. A test signal is transmitted through the xDSL modem. This signal is reflected by the connector and reflection is received by hybrid circuit. When the energy of this echo is large it means that the communication line it not connected to the connector, when the energy is small it means that the two are connected.

Information processing equipment, signal transformation equipment, method of communications, and computer product

An xDSL transceiver comprising a transmission unit for transmitting a DMT-modulated signal through a subscriber line as a transmission path and a receiving unit for receiving the DMT-modulated signal from the subscriber line. The xDSL transceiver further comprises an echo signal suppression unit for suppressing the echo signal from the transmission unit to the receiving unit by matching the phase between the frame of the transmission signal and the frame of the receiving signal.

xDSL transceiver

An ADSL modem connected to the telephone line is disclosed, which even in the case where a plurality of ADSL modems are connected to a single telephone line installed in a SOHO application or in the home of an ordinary user, a stable high-speed data communication can be realized without superposing the signals between the ADSL models or without causing any impedance mismatch. An ADSL band signal detector ( ) detects whether the ADSL frequency band is occupied by another ADSL modem connected to the telephone line or not. Upon detection that the ADSL frequency is so occupied, a control unit ( ) suppresses the application of the signal energy to the ADSL frequency band.

ADSL modem

The process in an xDSL transceiver transfers into a fast retraining sequence when the cause of an error on a telephone circuit is a change from an off hook state to an on hook state of a telephone instrument, a signal indicating an inversion of polarity of a signal on the telephone circuit, a change from an on hook to an off hook and when a handshake waiting time has passed without detecting a predetermined signal on the telephone circuit, or when the predetermined signal is detected within the handshake waiting time. The handshake waiting time can be updated in accordance with a dial pulse width, the maximum number of digits in the dial pulse signal, and the maximum number of pulses in one digit, or depending on whether or not the dial pulse comes from NTT.

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Kawasaki, Japan

Masato Hori