Nec Corporation

Shigekazu Harada

Akio Tajima

Takahide Sugita

Toshiaki Arikawa

Hidetoshi Shinoda

Ryuuichi Ikematsu

Akihiro Tanaka

Takeshi Takeuchi

Wakako Maeda

Hajime Ishikawa

Hajima Ishikawa

There is provided a wavelength division multiplexing transmission system and apparatuses used therein, in which a remote apparatus to be newly added to a station apparatus autonomously sets a wavelength to be used in the remote apparatus, thereby avoiding the need for presetting a wavelength to be used in the remote apparatus. The remote apparatus includes wavelength determining means that determines an available wavelength on the basis of an optical signal received from the station apparatus. The wavelength determining means may determine the wavelength of an unreceived optical signal as the available wavelength or may determine the wavelength of a received optical signal as the available wavelength, and may set that wavelength as a transmission and reception wavelength to be used in the remote apparatus.

Wavelength division multiplexing transmission system and remote apparatus and station apparatus used therein

Disclosed are the multiplex communication system and the method therefore. A fault detection part of a duplex switching device detects it as generation of fault when recognizable signals are not detected from a connected line within a prescribed time. When the fault detection part detects the generation of fault in the present system line, the line switching part switches the lines from the present line to the standby line to perform communication between a terminal device and another terminal device therethrough. Also, the fault detection part notifies the generation of fault to the other duplex switching device after a prescribed switching protection time has passed from the time of the fault detected by the fault detection part, so the selection of the lines becomes consistent.

Optical transmission switching device

A transmitter-receiver having a means for automatically determining the status of transmission medium such as optical fiber, and a means for automatically setting and resetting the transmission rate and/or output power according to the status of the transmission medium, a transmission loss and gain measurement method, and a transmitting-receiving system. A transmitter-receiver comprises at least: an output power controller for controlling the output power of a transmitter; an input power measuring section for measuring the strength of input signals; and an information processor for deriving the loss or gain of a path to change the output power of the transmitter and/or the rate of data transmission according to the derived loss or gain of the path. A transmission loss and gain measurement method applied to a system comprising transmission media and a plurality of the transmitter-receivers connected via the transmission media, comprises the steps of: transmitting information on the output power of a first transmitter-receiver from the first transmitter-receiver to a second transmitter-receiver; measuring reception strength by the second transmitter-receiver when the second transmitter-receiver receives the output power information; reading the output power information by the second transmitter-receiver; and comparing the reception strength with the output power information to calculate a transmission loss or gain by the second transmitter-receiver.

Transmission method, transmitter-receiver, and transmitting-receiving system

Multiplex communication system and method

A wavelength division-multiplexing system is provided that uses wavelength grids in conformity with the ITU-T Recommendation G.692 and that is realizable at lower costs. In the system, the wavelengths of signal light beams transmitted from plural optical transmitters are respectively spaced apart in such a manner that multiplexed wavelengths are set at regular intervals within the band range of the optical amplifier. The wavelength range of each laser beam covers at least two grids including neighboring grids. The wavelength demultiplexeron the receiving side has the passband passing the wavelengths in a laser wavelength range corresponding to each channel.

Wavelength division-multiplexing optical transmission system

A transmission system includes a plurality of remote units in communication with a station unit, wherein communication is with fixed length cells in the upward direction from the remote units to the station unit by a TDMA system, and in the downward direction from the station unit to the remote units by a TDM system. The station unit is adapted to detect whether one of the plurality of remote units is in a standby state and is responsive to a detection of one of the plurality of the remote units being in a standby state to allocate bands of communication from the remote unit in the standby state to a remote unit in a normal state.

Transmission system, and station unit and remote units to be used therein

For enabling to obtain automatically a proper identifier of a remote terminal and to assign an identification number to the remote terminal in order to performing supple communication control of a data transmission system wherein upward communication is performed according to a TDMA system and downward communication is performed according to a TDM system making use of cells having fixed length; a local station of the system comprises: a command-cell generation timer (112) for generating a command-cell generation trigger periodically, a command-cell generating unit (113) for generating a command cell to be downward transmitted every time the command-cell generation trigger is supplied by writing an available identification number therein, a window generation timer (111) for enabling a window signal every time the command-cell generation trigger is supplied for inhibiting transmission of upward cells from the remote terminals whereto identification numbers are assigned, a control-data-cell generating/terminating unit (107) for detecting a newly installed remote terminal by receiving a control data cell during the window signal is enabled, wherein a proper identifier of the newly installed remote terminal is written, and a terminal management unit (109) for assigning the available identification number to the newly installed remote terminal.

Growing community of inventors

Tokyo, Japan

Shigekazu Harada