Abstract: A transmitting apparatus includes a plurality of code spreaders different in spreading code, a reception processing unit that selectively distributes transmission data to the plurality of code spreaders, a plurality of optical transmitters each of which that transmit a code-spread signal to an optical fiber as a CDMA optical signal of a carrier wavelength different from that of the other optical transmitters, and a signal multiplexing unit that selectively supplies outputs of the plurality of code spreaders to the plurality of optical transmitters, and a receiving apparatus includes an optical receiver that receives a wavelength-division-multiplexed CDMA optical signal from the optical fiber, and a plurality of despreaders connected to the optical receiver and different in spreading code, wherein each of the despreaders reproduces a CDMA signal corresponding to its spreading code from an output signal of the optical receiver.

Abstract: In a passive optical network system, a parent station includes a reception circuit that receives an optical signal from each of child stations using a threshold used to identify if the optical signal is 0 or 1; a bandwidth setting unit that determines a time at which each child station sends an optical signal; a storage unit that stores thresholds and intensities of optical signals received from the child stations; and a control unit that sets a threshold, stored corresponding to a sending time, in,the reception circuit to control a reception of an optical signal. The control unit has a function that compares an intensity of a signal received from each child station at an optical signal reception time with information stored in the storage unit to detect and determine a fault in the child station or in the optical fiber connected to the child station.

Abstract: Provided is an ONU that suppresses transmission of a useless multicast control message to a PON section and enables a communication bandwidth of the PON section to be effectively used. The ONU of the PON system has a multicast group management table that shows a correspondence between a multicast group identifier and an address of a user terminal participating in a multicast group. When the ONU receives a request message of participation in the multicast group from the user terminal, the ONU registers the correspondence between the multicast group identifier indicated by the received message and the user terminal address. A new received message is deleted without being sent to the OLT if another user terminal address is registered already, along with a correspondence with the same multicast group identifier, in the multicast group management table.

Abstract: A PON system capable of utilizing the bandwidth of an optical transmission channel in the PON section. In a PON system including an OLT and a plurality of ONUs, the OLT has: a downstream frame processing unit that removes at least part of the header information in a layer 2 header from a downstream frame received from a wide area network, and converts the remaining frame portion into a frame having a header specific to the PON section; and a downstream frame processing unit that extracts a downstream frame portion to be transferred to a user terminal, from a received frame from a PON, and adds the layer 2 header information deleted in the OLT.

Abstract: In a PON system, an OLT periodically transmits a channel resource information block specifying a carrier wavelength and a spreading code on a first downstream channel to which a spread-spectrum spreader having a first spreading code is applied; one of ONUs receives the channel resource information block with a spread-spectrum despreader having the first spreading code and transmits a connection request to the OLT, using the carrier wavelength and the spreading code specified by the channel resource information block; the OLT having received the connection request transmits a new channel resource information block specifying a carrier wavelength and a spreading code to be used on an upstream data channel to the requester ONU through the first channel; and the requester ONU transmits data, using the carrier wavelength and the spreading code specified by the new channel resource information block.

Abstract: Disclosed herewith is a PON system and a bandwidth controlling method capable of controlling congestion with use of an upstream bandwidth in a PON section efficiently when congestion occurs in a gateway (GW) connected to an OLT. An OLT connected to a plurality of ONUs through a passive optical network (PON) and to a gateway (GW) through a communication line, when receiving a congestion occurrence notice indicating a congestion occurred output number from a GW, identifies the identifier of the ONU that is using a GW output line having the congestion output port number and shifts the bandwidth controlling of the PON section in a normal mode for allocating a bandwidth to each ONU normally to that in a bandwidth suppression mode for allocating a congestion time allowable bandwidth that is less than the current bandwidth to the ONU having the identified ONU identifier and a bandwidth to each of other ONUs according to its transmission queue length.

Abstract: Provided is an ONU that suppresses transmission of a useless multicast control message to a PON section and enables a communication bandwidth of the PON section to be effectively used. The ONU of the PON system has a multicast group management table that shows a correspondence between a multicast group identifier and an address of a user terminal participating in a multicast group. When the ONU receives a request message of participation in the multicast group from the user terminal, the ONU registers the correspondence between the multicast group identifier indicated by the received message and the user terminal address. A new received message is deleted without being sent to the OLT if another user terminal address is registered already, along with a correspondence with the same multicast group identifier, in the multicast group management table.

Abstract: 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.

Abstract: A communication system is provided which allows synchronous devices in different synchronous communication networks to have synchronous communications with one another via an asynchronous communication network. In the communication system of the present invention, a master communication device generates a master clock based on a reference clock which is provided by a clock supplier. The master communication device sends a synchronization information frame, which contains information about the generated master clock, to plural slave communication devices via the asynchronous communication network. The slave communication devices each reproduce the master clock from the received synchronization information frame.

Abstract: A shaping apparatus comprising a plurality of buffer memories allocated for different flows, bandwidth control units associated with the buffer memories, and a read control unit, wherein each of the bandwidth control units issues a first frame output request based on a maximum allowed bandwidth and a second frame output request based on a minimum guaranteed bandwidth, and the read control unit selects a bandwidth control unit to be permitted for frame output execution out of bandwidth control units that are issuing the first or second frame output request, giving priority to the second frame output request.

Abstract: Disclosed herewith is a PON system and a bandwidth controlling method capable of controlling congestion with use of an upstream bandwidth in a PON section efficiently when congestion occurs in a gateway (GW) connected to an OLT. An OLT connected to a plurality of ONUs through a passive optical network (PON) and to a gateway (GW) through a communication line, when receiving a congestion occurrence notice indicating a congestion occurred output number from a GW, identifies the identifier of the ONU that is using a GW output line having the congestion output port number and shifts the bandwidth controlling of the PON section in a normal mode for allocating a bandwidth to each ONU normally to that in a bandwidth suppression mode for allocating a congestion time allowable bandwidth that is less than the current bandwidth to the ONU having the identified ONU identifier and a bandwidth to each of other ONUs according to its transmission queue length.

Abstract: A packet forwarding apparatus and network system for providing different types of bandwidth control services to the user; in which a packet forwarding apparatus for transferring data comprises an interface unit for sending and receiving packets, and a traffic shaper for controlling the packet transmission timing and a packet switch for sending an output to the interface unit as the destination of the received packet; and the traffic shaper uses a token bucket algorithm when transmitting a packet to guarantee the minimum frame rate, and uses a leaky bucket algorithm when limiting the peak frame rate.

Abstract: To prevent, in using a multicast DA in an OAM frame, an increase in the network bandwidth usage and in the load of node processing and a degradation of the network reliability caused by a frame being transmitted to all routes in a broadcast domain. A MAC address and other basic frame information and the MEGID are associated with each other, and the MEGID information is added to the OAM frame, and these information are transmitted from an edge node serving as an end point of an ME. In a relay node of the ME, a route control table used for OAM frame control is provided, and a filter is generated by snooping of the OAM frame. Furthermore, when the relay node does not support the OAM function, the MEGID is denoted by a VLAN tag and the route control is made using the snooping function of each VLAN tag.

Abstract: An optical access system capable of avoiding cutoffs or interruption in the periodically transmitted signals that occur during the ranging time is provided. A first method to avoid signal cutoffs is to stop periodic transmit signals at the transmitter during the ranging period, and transmit all the periodic transmit signals together when the ranging ends, and buffer the signals at the receiver to prepare for ranging. A second method is to fix definite periods ahead of time for performing ranging, then cluster the multiple periodic transmit signals together in sets at the transmitter and send them, and then disassemble those sets back into signals at the receiver. The transmitting and receiving is then controlled so that the transmit periods do not overlap with the ranging periods. In this way an optical access system is provided that can send and receive signals requiring periodic transmissions without interruption even during ranging operation.

Abstract: In order to specify a data discarding point in a network, provided is a network system for collecting, in the network including an access network and a transport network, pieces of statistical information including a traffic amount of the network, including: an access terminal coupled to the access network; and an edge node for interconnecting the access network and the transport network, in which: the access terminal is configured to: measure pieces of statistical information including a traffic amount in the access terminal; and notify the edge node of the measured pieces of statistical information; and the edge node collects the pieces of statistical information notified by the access terminal.

Abstract: A bit synchronization circuit comprising an initial phase determining unit for rapidly determining, during a period of receiving a preamble of burst data, a clock with a phase synchronized with received burst data from among multi-phase clocks having the same frequency as an internal reference clock and a phase tracking unit for modifying the synchronized phase clock responsive to phase variation of received data during a period of receiving a payload of burst data by taking the synchronized phase clock determined by the initial phase determining unit as an initial phase. The bit synchronization circuit retimes burst data with a data retiming clock having a predetermined phase relation with the synchronized phase clock and outputs the burst data in synchronization with the internal reference clock.

Abstract: A transmission device uses transmission delay time of reciprocation with the terminal and time information of the transmission device to create a correction value of time information of the terminal and transmits it to the terminal. The terminal includes expected arrival time information based on the time information of the terminal and the correction value received from the transmission device in a frame transmitted to the transmission device. The transmission device compares reception time of the frame with the expected arrival time information in the frame. If they match, the time information of the terminal synchronizes with the time information of the transmission device. If they do not match, the transmission device transmits a new correction value to the terminal. The terminal transmits a frame including expected arrival time information using the new correction value to the transmission device.

Abstract: A bit synchronization circuit comprising an initial phase determining unit for rapidly determining, during a period of receiving a preamble of burst data, a clock with a phase synchronized with received burst data from among multi-phase clocks having the same frequency as an internal reference clock and a phase tracking unit for modifying the synchronized phase clock responsive to phase variation of received data during a period of receiving a payload of burst data by taking the synchronized phase clock determined by the initial phase determining unit as an initial phase. The bit synchronization circuit retimes burst data with a data retiming clock having a predetermined phase relation with the synchronized phase clock and outputs the burst data in synchronization with the internal reference clock.

Abstract: Disclosed herewith is a packet transfer apparatus that carries out 1+1 protection switching for traffics to be received variably in both length and cycle. The apparatus enables flows to be multiplexed and the link usage efficiency to be improved without generating any buffer overflow errors. The data transfer apparatus, upon receiving the third sequentially numbered data from the first communication route before receiving the preceding second sequentially numbered data, stores the received third data in a buffer. And upon receiving the second sequentially numbered data from the second communication route, the apparatus sends the second and third data sequentially. Then, upon receiving the third sequentially numbered data from the second communication route before receiving the second sequentially numbered data, the apparatus sends the third data when a predetermined waiting time expires.

Abstract: A packet transfer apparatus connects two networks of different protocols. The packet transfer apparatus, connected to a first communication network and a second communication network, performs the steps of: storing first destination correspondence information; receiving a packet of the first communication protocol; based on the first destination correspondence information, determining destination information of a packet of the second communication protocol corresponding to destination information of the received packet of the first communication protocol; generating the header of the packet of the second communication protocol, based on the determined destination information of the packet of the second communication protocol; converting the received one or more packets of the first communication protocol into one or more packets of the third communication protocol; and adding the generated header of the packet of the second communication protocol to the packets of the third communication protocol.