Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Norihiro Sakamoto

Tohru Kazawa

Yusuke Yajima

Masaki Ohira

Akihiko Tsuchiya

Yoshihiro Ashi

Kenichi Sakamoto

Masayuki Takase

Masahiko Mizutani

Atsushi Iwamura

Masatoshi Takihiro

Provided is a passive optical network system, wherein the electric power to be consumed is reduced on the basis of the quantity of signal to be transmitted downstream in a WDM-PON where signals having different transmission rates for wavelengths are mixed. In the passive optical network system, an OLT () and a plurality of ONUes () are connected by an optical fiber network including an optical splitter () and a plurality of optical fibers (and). The OLT () indicates to the ONUes () the wavelength to be used, in addition to the timing for transmission to the ONUes (). A format for signal transmission from the OLT () to the ONUes () comprises both the region, in which the timing for transmission to the ONUes () indicated by the OLT () to the ONUes () is stored, and the region, by which the wavelength to be used in the communication in the direction from the OLT () to the ONUes () is indicated.

Optical multiplexing terminal device, wavelength multiplexing passive optical network system and downlink wavelength transmission method

Provided is a passive optical network system for operating a mixture of PONs with differing transmission speeds and is capable of reducing power consumption on the basis of the amount of signals being transmitted. The master station of the passive optical network system, which determines the amount and timing of signals sent thereto by each of a plurality of slave stations on the basis of the requests of the plurality of slave stations and receives signals from the plurality of slave stations via an optical fiber network, is equipped with a control unit that determines in each set cycle the amount, transmission timing, and transmission speed of the signals that each slave station is permitted to transmit to said master station on the basis of the amount of signals that each of the plurality of slave stations has requested to transmit, and that notifies such to each slave station. Additionally, each of the plurality of slave stations is equipped with a control unit that transmits signals to the master station at a first transmission speed or a second transmission speed that is faster than the first transmission speed, and is configured to transmit signals with either the first transmission speed or the second transmission speed on the basis of notifications from the master station.

Passive optical network system and operating method thereof

There is provided an encryption apparatus including an idle data inserting unit that takes input of a frame including a fixed-length header and a variable-length payload and an encrypting unit that receives an output of the idle data inserting unit. If the length of a block to be processed, included in the payload, is less than a predetermined value, the idle data inserting unit appends idle data following the block and transmits the frame including the block padded with the idle data to the encrypting unit.

Encryption apparatus

A passive optical network system such that the power consumption can be reduced as much as possible according to the end-user traffic. An OLT uses the DBA function thereof and sequentially uses frequencies in ascending order of transmission rate in order to sequentially allocate bands to ONUs in ascending order of the requested bandwidth. At this time, a frequency to be allocated is selected so that the bandwidth allocated to each ONU is narrower than a maximum bandwidth through which transmission using the allocated wavelength is enabled. An OLT uses a grant area to specify the transmission timing of the secondary station and to inform the specified transmission timing to the secondary station. In addition, an area is set for storing information used to inform the secondary station of a new frequency to be used.

Optical multiplexing terminating device, passive optical network system and method for allocating wavelength

A master station includes an optical transmission interface for transmitting signals to a plurality of slave stations at a first transfer rate or a second transfer rate which is higher than the first one, packet buffers for accumulating the signals addressed to each of the plurality of slave stations, and a control unit for determining transmission timings and transfer rates of the signals on the basis of an amount of the signals accumulated in the packet buffers, transmitting the signals with the determined timings and rates, and notifying each of the slave stations about the determined timings and rates. Each of the slave stations includes an optical reception interface for receiving the signals of the first transfer rate or the second transfer rate, and a control unit for controlling the optical reception interface on the basis of the timings and rates which the slave stations is notified.

Passive optical network system and operation method thereof

In order to be able to moderate the inclination of the PON burst reception characteristics and to improve the FEC effect, a first offset is used in a ranging window field, and a second offset, which is lower than the first offset value, is used in a burst data field other than the ranging window field.

Passive optical network system and optical line terminal

A station-side communication device connected to subscriber-side communication devices via an optical combining device; sending, to the subscriber-side communication devices, a distance measurement request signal; computing transmission delay times of optical signals from the individual subscriber-side communication devices by receiving distance measurement signals, and including: a threshold control part identifying the level of distance measurement signals; a signal detection part detecting breaks in the distance measurement signals from the threshold control part; a transmission granting part determining the timing at which transmission of optical signals is granted, and a reset timing generation part that, there is notification of detection of a break in the distance measurement signal from the signal detection part while it is being notified that distance measurement is carried out to and from the subscriber-side communication devices from the transmission granting part, sends a reset signal indicating that the voltage level is reset to the threshold control part.

Passive optical network system and ranging system thereof

A transmission apparatus for use in fixed bandwidth communications and variable bandwidth communications. The transmission apparatus has a memory unit, which stores information contained in a frame and indicating the amount of data to be transmitted from a terminal device, a computing unit, which calculates a bandwidth amount to be assigned to the terminal device based on the data amount, and a transmission unit, which sends the calculated assigned bandwidth amount to the terminal device. The transmission apparatus is characterized in that the computing unit calculates bandwidth amounts to be assigned to different types of flow of which different transmission qualities are requested according to a priority level that is set to each flow type. The transmission apparatus is also characterized in that bandwidth is controlled by designating, instead of a necessary bandwidth amount, transmission starting timing and transmission ending timing, particularly for fixed bandwidth communication data.

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Yokohama, Japan

Norihiro Sakamoto