Abstract: Radio resources are utilized efficiently and the communication quality is improved by flexibly adapting to the state of radio waves at a base station varying every moment or the topology of the distribution area of contents in multicast communication. The base station (100) stores information including the flow distribution starting time, the error rate measuring period, the threshold in an intra-base station flow management table. When detecting that it becomes the time before the error rate measuring period from the flow distribution starting time, the reception quality of radio terminals in the communication area of the base station (100) is measured. A base station (100-b) where the reception quality exceeds the threshold redundantly transmits multicast data assigned to a plurality of radio resources (800-b1, 800-b3, 800-b5). A base station (100-a) where the reception quality does not exceed the threshold transmits multicast data assigned to a single radio resource (800-a1).

Abstract: In a PON system, a PON-ID assigned to a connected ONU before replacement is assigned to a newly connected ONU after the replacement and, setting data before the replacement is succeeded also after the replacement. An OLT includes a PON-ID state where a management state of the PON-ID is stored, a PON-ID management table where the PON-ID and an ONU serial number of the connected ONU and setting data are correspondingly stored and, a delete ONU table where the PON-ID and an ONU serial number of a replacement object are correspondingly stored. When the OLT receives an ONU replacement instruction from an operation system, the PON-ID assigned to the ONU of the replacement object is assigned to an ONU newly connected during the ONU replacement.

Abstract: In an MPLS or GMPLS network, links for hops of a communication path and adaptation to be implemented on the border of management domains or layers are automatically appropriately selected based on a service type or a requirement for maintenance. First, a unit that appends an identifier of a service to be provided and an attribute of the service to a communication path establishment control message, and requests path establishment is installed in a source node. Secondly, a unit that determines a requirement for maintenance of the communication path and adaptation on the basis of the service identifier and/or service attribute is installed in each node. Thirdly, maintenance attributes of network resources are compared with the requirement for maintenance in order to determine links and nodes through which the communication path passes. The determined links, nodes, and adaptation are designated as action parameters for a switching unit and/or interface unit.

Abstract: L2TP packet forwarding apparatus to be connected to at least two LACs (L2TP Access Concentrators) via L2TP sessions to receive packets transmitted from a gateway, which accommodates user terminals, in the form of a L2TP packet encapsulated in Bridge over PPP, has a lookup table indicating the correspondence of tunnel ID/session ID pairs to an identifier (VPN-IDs) of a wide area network to which a plurality of user terminals belong. The packet forwarding apparatus specifies an VPN-ID from the lookup table based on the tunnel ID and the session ID of a received packet and forwards, if it is confirmed that another tunnel ID/session ID pair associated with the same VPN-ID exists in the lookup table, the received packet to another L2TP session identified by the another tunnel ID/session ID pair in the form of a L2TP packet.

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: Part of an inputted optical add signal 118 is reflected by a mirror 117, and is thereby inputted into an optical wavelength multiplexer 105 in the reverse direction so that the optical add signal is returned to paths 115-1 through 115-16 corresponding to wavelengths ?1 through ?16. If the returned optical add signal is an optical add signal having a correct wavelength, the optical signal enters its corresponding backward direction optical detector 113-16. Accordingly, it is possible to check whether or not a wavelength of the optical add signal is correct.

Abstract: A low-cost configuration of, and at the same time to control the variable dispersion compensator at a high speed in a variable dispersion compensator for compensating the wavelength dependent accumulated dispersion resulting from the wavelength dependency of the transmission fiber and fixed dispersion compensator in a long-distance high-speed WDM transmission system. In order to achieve the object mentioned above, the wavelength dependent representative characteristic of the transmission fibers 4-1 . . . n, and the wavelength dependent representative characteristic of the DCFs 13-1 . . . n are recorded and maintained in advance in the dispersion control circuit 5-1 . . .

Abstract: In a network for forwarding user packets by a tunneling protocol, an egress edge node to which tunnels concentrate from a plurality of ingress edge nodes allocates a bandwidth to each of sessions multiplexed through each of the tunnels and notifies each of the ingress edge nodes of the allocated bandwidth, and the ingress node notifies private routers or terminal devices of the allocated bandwidth.

Abstract: Heretofore, it was necessary to individually locate an optical switch, an optical switch control circuit, and the like, before and after an optical transceiver that performs optical protection. As a result, costs and the space for implementation increase, and a delay in services is also caused, which were the problems. For the purpose of solving the above problems, the present invention provides a simple optical protection method used in an optical add-drop multiplexer. Add switches 105-1 through 105-N and drop switches 103-1 through 103-N for optical signals corresponding to each wavelength in an optical add-drop multiplexer 100 are made controllable independently of one another. Add switches and drop switches of the active-side and backup-side optical add-drop multiplexers are switched by optical switch control circuits 106-1 through 106-N respectively to make a detour around a failure so that the optical protection is achieved.

Abstract: A base station control portion selects one or multiple signals in accordance with the state of radio waves from signals received through multiple communication paths. A wireless communication apparatus communicates with a wireless terminal and a wired communication network at multiple frequencies. In response to a request for software upgrading from a network management device, the wireless communication apparatus selects one frequency, controls the state of transmission waves of a wireless interface such that a communication path in which a communication service is being provided can be switched to another communication network without interruption, rewrites software for each wireless interface to software received through a wired interface in advance, and returns the state of transmission waves of the wireless interface. Thus, the software can be upgraded without blackouts of the communication service to the wireless terminal.

Abstract: A BAS/load balancer which combines the functions of a BAS (Broadband Access Server) providing a dynamic network connection to a user network, and a load balancing relaying the communications traffic of the user network to one of plural load balancing target apparatuses, and which can apply an arbitrary load balancing algorithm. When the BAS/load balancer of the invention sets up a dynamic connection between the user networks, the balancer determines the load balancing target apparatus which is a relay destination using an arbitrary load balancing algorithm for both send and receive communications traffic in the user network.

Abstract: The present invention relates to an optical modulator that generates quaternary amplitude modulated light without inter-symbol-interference by splitting input light into three optical paths, generating a continuous wave signal in a first optical path, generating binary phase modulated lights using a single drive MZ type optical phase modulator in second and third optical paths, and interfering them at in-phase and at field amplitude 1:a:b.

Abstract: A wireless communication which suppresses radio interference between wireless base stations and improves the channel efficiency is implemented. In the wireless communication system including a central base station, a plurality of remote base stations having a direction-variable antenna, and a plurality of mobile stations to communicate with the remote base stations, the central base station performs centralized management of radio-wave beam patterns to be sent to the plurality of mobile stations which will communicate with remote base stations and performs packet scheduling of the mobile stations in such a manner that radio waves sent from the remote base stations will not cause strong interference at the mobile stations.

Abstract: A base station control portion 200 selects one or plural signals from signals received by plural settable communication paths in accordance with the state of the wave. A wireless communication apparatus 110 communicates with a wireless terminal 300 and a wired communication network. When the wireless communication apparatus 110 receives a request for upgrading software from a network management device 250, the wireless communication apparatus 110 controls the state of the transmission wave of a wireless interface so as to switch a communication path in which communication services are being provided to another wireless communication apparatus 110 without blackouts, rewrites the set software to software having been received through a wired interface in advance, returns the state of the transmission wave of the wireless interface and upgrades software without blackouts of the supply of communication services to the wireless terminal 300.

Abstract: The signal quality of ultra high-speed signals such as 40 Gbit/s and 100 Gbit/s are significantly degraded due to wavelength dispersion and nonlinear effects in an optical fiber. Thus, there is provided a transponder unit in which a light source is polarization multiplexed in a direction mutually orthogonal to a signal direction, in order to reduce the nonlinear effects in the optical fiber and improve the signal quality. At the same time, it is possible to monitor an amount of the wavelength dispersion in the optical fiber, allowing for more precise dispersion compensation design.

Abstract: Any or unique VLAN ID is dynamically assigned to a user terminal connected to a network, and communication by the assigned VLAN ID is enabled. A connection request from a user terminal is directed to L2GWs by a tagged VLAN frame having a common VLAN ID on the network. The L2GWs determine whether the connection request can be met, obtain a VLAN ID that can be assigned to the user terminal from a VLAN ID management server, configure themselves to communicate by the assigned VLAN ID, and report the VLAN ID to the user terminal. The user terminal performs subsequent communication by the reported VLAN ID. L2SWs monitor communication between the user terminal and the L2GWs and configure themselves to allow communication between the user terminal and the L2GWs by the VLAN ID assigned to the user terminal.

Abstract: An error correction decoder possessing a decoding method with high error correction performance and capable of operating at a low operating frequency and on a reduced circuit scale. A decoding method based on the SOVA method for improving error correction performance and boosting reliability of the soft decision output by allowing branching of paths other than the survival path at trace-back is achieved by preparing a trace-back circuit for each state, and selecting an output from that output and survival state (survival state+difference of likelihood).

Abstract: There is provided admission control in view of wireless resources. A base station 120 obtains a down wireless resource available rate (available rate of slot allocation) based on a down QoS requested bandwidth Bi requested by a terminal i during QoS communication and a data rate Ri which the terminal can receive. A down wireless resource usage rate necessary to ensure the requested bandwidth B is obtained by dividing a down QoS requested bandwidth B requested by the terminal trying to perform QoS communication by the data rate R which the terminal can receive. The base station 120 obtains an up wireless resource available rate based on ROT of an up channel and a threshold value T1 indicating an allowable upper limit of the ROT. Besides, an up wireless resource usage rate necessary to ensure an up requested bandwidth requested by the terminal is obtained.

Abstract: Provided is a network system including a start device and multiple end devices. A point-to-point (P-to-P) logical path is set to be used for unicast communication between the start device and each of the end devices. A first point-to-multipoint (P-to-M) logical path and a second P-to-M logical path are set to be used for multicast communication from the start device to the multiple end devices. The start device transmits data over the first P-to-M logical path. When one of the end devices detects a defect along the first P-to-M logical path, the end device that has detected the defect transmits a switch request over the P-to-P logical path set between this end device and the start device. The start device receives the switch request and transmits data over the second P-to-M logical path.

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.