Nippon Telegraph and Telephone Corporation

Yoichi Fukada

Hiroyuki Uzawa

Jun Terada

Naotaka Shibata

Takahiro Kubo

Daisuke Hisano

Yu Nakayama

Tomoaki Yoshida

Hirotaka Ujikawa

Hiroaki Katsurai

Toshiaki Shitaba

Kyo Minoguchi

Akihiro Tanabe

A signal converting apparatus includes a conversion unit, a measurement unit, and a control unit. The conversion unit performs FM batch conversion on an input signal containing a plurality of carrier signals, to generate an FM signal. The measurement unit measures the carrier levels of the plurality of carrier signals contained in the input signal, and the maximum frequency of the input signal. The control unit calculates the frequency deviation amount of the entire input signal, on the basis of the measured carrier levels of the respective carrier signals. Using the calculated frequency deviation amount and the measured maximum frequency, the control unit calculates a center frequency for the FM signal, and controls the conversion unit so that the center frequency of the FM signal to be generated by the FM batch conversion becomes equal to the calculated center frequency.

Signal converting apparatus and signal converting method

A light receiving portion of a photodiode is connected to an external light source via an optical transmission line. A power storage unit stores electrical energy generated by the photodiode. A bias circuit takes out electrical energy corresponding to the amount of stored power from the power storage unit, and applies a voltage to the cathode of the photodiode.

Optical power reception apparatus, communication apparatus and optical power reception method

There are included a control unit configured to, when detecting that no high priority traffic frame arrives for a frame interval threshold or longer in the period that allows high priority traffic frames to be transmitted, release the period that allows high priority traffic frames to be transmitted and allocate the released period to the period that allows low priority traffic frames to be transmitted, a frame arrival time information acquisition unit configured to obtain information of frame arrival times of high priority traffic frames, a frame interval calculation unit configured to calculate, in accordance with the information of frame arrival times obtained by the frame arrival time information acquisition unit, frame intervals between frames of the high priority traffic frames input in chronological order, a frame interval threshold calculation unit configured to calculate a new frame interval threshold in accordance with the frame intervals, and a frame interval threshold configuration unit configured to change the frame interval threshold to the new frame interval threshold.

Signal transfer device, signal transfer method, signal transfer control device, signal transfer control method and signal transfer program

In a communication control system having a plurality of layer 2 switches and a network controller, the network controller includes a determination unit and an instruction unit, the determination unit being configured to determine whether or not a transfer communication flow feature indicating a feature of a communication flow transferred by a layer 2 switch of the plurality of layer 2 switches is similar to an abnormal communication flow feature indicating a feature of a communication flow when an abnormality occurs; and the instruction unit being configured to: output to the layer 2 switch, when the determination unit determines that the transfer communication flow feature is similar to the abnormal communication flow feature, a first instruction to lower priority of transfer processing for the communication flow and a second instruction to duplicate the communication flow to the layer 2 switch; or output the first instruction to the layer 2 switch, and output, to a server detecting a malicious attack, identification information identifying the communication flow having the transfer communication flow feature.

Communication control system, network controller and computer program

A signal forwarding system includes: a plurality of signal forwarding devices forming a plurality of communication routes between a slave station and a master station; and a route control device that determines a communication route, wherein the route control device includes at least: a communication route calculation unit that calculates a communication route in response to a route switching request; and a forward destination setting instruction unit that outputs forward destination setting information based on the communication route, the signal forwarding devices include at least: a forward destination setting instruction acquisition unit that acquires the forward destination setting information; a forward destination set unit that changes a forward destination based on the forward destination setting information; and a forward unit that outputs input traffic based on the forward destination, and any of the route control device and the signal forwarding devices includes: a traffic monitor unit; a non-signal period estimation unit that estimates a non-signal period in which the traffic does not flow; and a switching timing control unit that controls a switching timing to perform route switching in the non-signal period.

Signal transfer system, signal transfer device, route control device and signal transfer method

A path control method of controlling a communication path in a network including a plurality of wireless devices communicating with a terminal in a wireless manner and a plurality of wireless control devices communicating with any one of the plurality of wireless devices through a plurality of signal transfer devices includes searching for available communication paths and listing the available communication paths for individual combinations of a wireless device of the plurality of wireless devices and a wireless control device of the plurality of wireless control devices, and selecting a combination of communication paths in which a maximum value of the number of communications passing through the same output port of a signal transfer device of the plurality of signal transfer devices is minimized from among the listed available communication paths.

Route control method and route control device

A communication control system includes a plurality of layer 2 switches (SWs); and a communication control device that controls communication of the SWs. Each SW includes one or more queues that each have a variable queue length for accumulating input frames, and a transmission unit that has a shaping function of transmitting the frames accumulated in the queues to a desired destination at a desired rate. The communication control device includes a correction processing unit that acquires an amount of discarded data generated in each queue of the SW, and multiplies the acquired amount of discarded data by a correction coefficient weighted by the cumulative number of times of discarding occurrences for which the amount of discarded data is not 0 to obtain a corrected amount of discarded data; and an adjustment processing unit that determines adjustment values for the queue length of each queue and shaping rate of the SW based on the corrected amount of discarded data, and notifies each SW of the adjustment values.

Communication control system, communication control method, communication control apparatus and communication control program

Provided is a path control method of controlling a path of communication in a network including a high priority device dealing with high priority traffic, a high priority control device communicating with the high priority device through a plurality of signal transfer devices transferring signals by periodically repeating a high priority signal transmissible period in which high priority traffic is transmissible and a low priority signal transmissible period in which low priority traffic is transmissible, a low priority device dealing with the low priority traffic, and a low priority control device communicating with the low priority device through the plurality of signal transfer devices, the path control method including calculating a low priority signal transmissible period in each of paths between the low priority device and the low priority control device, and performing setting for switching the path between the low priority device and the low priority control device so that the low priority traffic is transmitted in any one of the calculated low priority signal transmissible periods.

A communication control apparatus includes an observed data rate acquiring unit configured to acquire observed data rates indicating input data rates of queues, the observed data rates being observed in a layer 2 switch, a threshold value storage unit configured to store predetermined threshold values of the queues, a shaping rate determination unit configured to determine a shaping rate of each queue based on both observed data based on an observed data rate of the observed data rates acquired by the observed data rate acquiring unit and a threshold value of the predetermined threshold values stored in the threshold value storage unit, and a shaping rate setting unit configured to set, in the layer 2 switch, the shaping rate of each queue determined by the shaping rate determination unit.

Communication control apparatus and communication control method

A communication control system is a communication control system including: a plurality of layer 2 switches; and a control apparatus. Each of the plurality of layer 2 switches includes a queue having a queue length being adjustable for each of transfer routes of data, and a transmission unit configured to transmit the data stored in the queue for each of the transfer routes to a subsequent destination of the data at a data rate being adjustable for each of the transfer routes. The control apparatus includes an adjustment processing unit configured to acquire information representing a discarded data amount being a data amount of the data discarded in the queue from one of the plurality of layer 2 switches having discarded the data, and adjust the queue length and the data rate of each of the plurality of layer 2 switches for each of the transfer routes, based on the discarded data amount.

Communication control system and communication control method

A data collection unit of an NW controller () collects, from an L2SW () constituting an L2NW (), uplink observation data indicating traffic volume of a session request packet addressed to an application serverand downlink observation data indicating traffic volume of a session response packet transmitted from the application server, which are acquired by observing packets input to the L2SW (). A control unit changes shaping rate of the packets addressed to the application server () through the L2SW () included in the L2NW () based on a ratio between the traffic volume indicated by the uplink observation data and the traffic volume indicated by the downlink observation data, or a ratio between an increment of the traffic volume acquired from the uplink observation data and an increment of the traffic volume acquired from the downlink observation data.

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Tokyo, Japan

Yoichi Fukada