Fujitsu Corporation

Masahiro Yoshimoto

Futoshi Izumi

Makoto Takakuwa

Takahiro Hosokawa

Nobuhiro Rikitake

Motoshi Hamasaki

Motonori Inui

Toshifumi Yokoyama

A radio wave management method executed by a processor included in a radio wave management apparatus, the radio wave management method includes counting the number of first mobile terminals which exist in a first area corresponding to a measurement target of a radio wave situation; requesting second mobile terminals, which exist in a second area that is different from the first area, to move to the first area when the number of first mobile terminals is smaller than the predetermined number; requesting the first mobile terminals and the second mobile terminals to measure the radio wave situation when the second mobile terminals move to the first area; receiving the radio wave situation from the first mobile terminals and the second mobile terminals; and transmitting the received radio wave situation to a computer in response to a request from the computer which is coupled to the radio wave management apparatus.

Radio wave management method, radio wave management apparatus, and recording medium

A data transmitting device coupling to a plurality of nodes in a network includes a plurality of communication paths, the data transmitting device includes a memory and a processor coupled to the memory configured to set a routing table based on a command that designates a first communication path included in the plurality of communication paths, to detect a link failure occurred in the network, and when the link failure has occurred at a first location between the data transmitting device and a first node adjacent to the data transmitting device on the first communication path, to modify the routing table so that data are to be transmitted to a second node on a second communication path different from the first communication path, and when the link failure has occurred at a second location that differs from the first location in the network, to maintain the routing table.

Data transmitting device, data transmitting method and non-transitory computer-readable storage medium

In a transmission apparatus, a shaping circuit shapes a packet output from a switch in a band of predetermined granularity. A packet generation circuit generates a band correction packet in a band smaller than the band of the predetermined granularity of the shaping circuit and inputs the band correction packet to the shaping circuit.

Transmission apparatus with packet shaping capabilities, and interface card therefor

The present invention relates to serial asynchronous transmission of data of fixed length in which a start bit and a stop bit are inserted at the head and tail, respectively, of the data. The insertion of a fixed bit having a predetermined logical value every predetermined number of bits of the data allows an idle state period to be reduced up to the predetermined number of bits plus 1 bit, resulting in considerable improvement in transmission efficiency.

Method and circuit for asynchronous transmission

An optical transmission apparatus that improves the reliability of system operation by efficiently limiting the line speed of a signal sent from a user with a guard mechanism. An optical branching section makes an optical signal branch in two directions. A through branching line passes an optical signal in its original condition and sends the optical signal as a through optical branch signal. A delay branching line delays an optical signal by a delay amount set and sends the optical signal as a delayed optical branch signal. An optical multiplexing section combines the through optical branch signal and the delayed optical branch signal. A line speed limitation section limits acceptance of the line speed of the optical signal inputted by generating a multiplexed optical signal that meets a pulse mask standard for an optical signal to be passed for the optical signal which is sent at a line speed lower than or equal to a line speed settled under contract with a user and which is to be passed and by setting the delay amount for generating a multiplexed optical signal that does not meet a pulse mask standard for an optical signal acceptance of which is to be refused for the optical signal which is sent at a line speed higher than the line speed settled under contract with the user and acceptance of which is to be refused.

Optical transmission apparatus

A dispersion compensating method for carrying out automatic level control with the use of target output power and an ASE correction value corresponding to the number of wavelengths to multiplex and making output power of a wavelength multiplexed signal constant, comprising the steps of: switching into automatic gain control in which the output power of the wavelength multiplexed signal is made constant, to carry out increase/decrease of the wavelengths to multiplex; varying a dispersion compensating amount based on the increase/decrease of the wavelengths by the automatic gain control; calculating an ASE variation amount due to the change in the dispersion compensating amount; and reflecting the ASE variation amount on the ASE correction value and switching into the automatic level control.

Dispersion compensating method and dispersion compensating apparatus

A power-down delay unit for delaying cutoff of a voltage is provided in a power supply line which supplies electrical power to an optical module of a transponder unit for each optical wavelength. The power-down delay unit assigns different delays for each wavelength. The length of the delay is a time required by an AMP unit to change from an ALC mode to an AGC mode or longer. When the power sources for supplying electrical power to the transponder units becomes faulty and outputs of several wavelengths are simultaneously going to stop, the power-down delay unit delays cutoff of the supply voltage to the optical modules by keeping supply voltage for a while to the optical modules on behalf of power sources enabling the optical modules to operate after the power sources shutdown, so that the actual optical signals gradually stop one by one.

Wavelength division-multiplex system

A dispersion compensating method for compensating wavelength dispersion occurring in an optical transmission line, includes the steps of: a) performing dispersion compensation by causing an optical signal, supplied from the transmission line, to pass through a variable dispersion compensator; and b) controlling a dispersion compensating amount in the variable dispersion compensator according to code error information corresponding to a type of code in a received data signal obtained from receiving the optical signal having undergone the dispersion compensation.

Growing community of inventors

Kawasaki, Japan

Masahiro Yoshimoto