Abstract: Access routers making up a LAC device or LNS device are given virtual router functions. The virtual routers are associated with either physical interfaces or fixed logical interfaces, L2TP tunnels, or PPP sessions. This allows one LAC device or LNS device to be connected with a plurality of L2TP transfer networks or ISP networks managed by different carriers.

Abstract: Since in a system of the invention comprising a TU portion 1b for accommodating general extension telephones 5 and PSTN 8, and a TM portion 1a for performing a call control with a packet network, call control information from the PSTN 8 and the like to the packet network is received by the TU portion 1b and then transferred to the TM portion 1a and converted into call control data adapted to the packet network, and voice data from the PSTN 8 and the like to the packet network is received by the TU portion 1b and then converted into voice data adapted to the packet work, it is possible to use a packet network such as the Internet, convert voice data into IP packet data and thereby provide a communication service equivalent to a conventional circuit switching service at low cost.

Abstract: 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 t

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 radio communication system includes a grouping unit for grouping a plurality of base stations into a plurality of groups (Soft Handoff Groups) and a determining unit for selecting base stations belonging to one and the same group selected from the groups produced by the grouping unit and for determining the base stations as base stations to send communication packets to an access terminal.

Abstract: An optical signal connection apparatus for connecting first and second optical signal transmission lines to first and second routers, respectively, is disclosed. The first and second routers are configured to handle both optical signals and electrical signals. The optical signal connection apparatus comprises a first node and a second node.

Abstract: An access network system connected to an ISP network including a subscriber authentication server comprised of a plurality of packet forwarding apparatuses each for connecting user terminals to an Internet network via the ISP network and an address pool management server having an address pool management table for holding, as a sub-address pool, a plurality of IP addresses usable over the ISP network. Each of the packet forwarding apparatuses acquires from the address pool management server an IP address to be allocated to the user terminal having requested connection to the Internet when the subscriber authentication server has succeeded in authentication of the user terminal.

Abstract: A listening-or-viewing charge is differentiated with bit rates depending on distributed programs. A broadband access server for holding user channels by PPP and replicating and transferring multicast packets have a counter for counting the number of distributed multicast packets and the number of distributed bytes at each multicast group address. The counter values (byte counts and packet counts) when a user joins a multicast group and when the user leaves the multicast group and a multicast session ID containing a PPP user ID and a multicast group address are sent to a multicast accounting radius server. The multicast accounting server provides an accounting on a basis of the byte counts, the packet counts, or a bit rate.

Abstract: 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 t

Abstract: An optical transmission apparatus comprising a first detector for detecting the power of the supervisory signal light separated from received wavelength-division multiplexed signal lights; a second detector for detecting the power of the wavelength-division multiplexed signal lights after the separation of the supervisory signal light; a gain-controlled type optical amplifier for amplifying the wavelength-division multiplexed signal lights; an optical attenuator coupled to the amplifier; and a control unit for controlling the optical amplifier and the optical attenuator so as to keep the output level of the wavelength-division multiplexed signal lights to a predetermined target value, wherein the control unit restrains automatic output level control by the optical attenuator when the supervisory signal light power fluctuates within its permissible range and fluctuations in the signal light power have deviated from its permissible range.

Abstract: An optical access network system having a function of correcting upstream signal waveform distortions occurring in the PON section, wherein a central office side apparatus comprises a main controller to notify each subscriber connection apparatus of a transmission grant period, an equalizer of a tap gain adaptive control type to correct waveform distortions of signals received from the subscriber connection apparatuses, an equalizer controller, and a parameter table for storing, for each subscriber connection apparatus, the initial values of tap gains to be set for the equalizer. The main controller issues a switchover request for switching the equalization characteristic to the equalizer controller each time notifying a subscriber connection apparatus of a transmission grant period, and the equalizer controller retrieves the initial values of the tap gains for the subscriber connection apparatus from the parameter table in response to the switchover request, and sets these values to the equalizer.

Abstract: An access server starts the individual collection of communication statistics information on each of LCP sessions upon the establishment of a data link, individually collects communication statistics information on each of NCP sessions established on the LCP session, notifies a RADIUS server of the statistics information on the LCP session when the data link is released, and notifies, when the NCP session is released, the RADIUS server of the statistics information on the released NCP session.

Abstract: A variable dispersion slope compensator with a high-accuracy and a low-cost structure for compensating the dispersion slope compensation error accompanying variations in the zero-dispersion wavelength in transmission fibers in long-distance, high-speed WDM (wavelength division multiplexing) transmission systems.

Abstract: A signal transmission and reception method, and a base station and a mobile terminal therefor are disclosed. In a communication system including a base station and at least a mobile terminal, the transmission of the data signal from the base station to each mobile terminal is controlled in accordance with the manner in which the pilot signal transmitted from the base station to each mobile terminal is received by the mobile terminal. In the signal transmission method, the proper one of a plurality of signal multiplexing schemes is selected based on the control signal received from each mobile terminal, and the transmission signal is multiplexed by the selected signal multiplexing scheme and transmitted to each mobile terminal. The transmission signal includes the data signal and the dedicated pilot signal transmitted to the mobile terminal.

Abstract: In the bias stabilization control using average optical power of signal light, there is a case where a control algorithm (maximum control or minimum control) changes depending on the amplitude of clock voltage, or it becomes out of control. In an optical modulation device for performing CSRZ optical modulation on outgoing light from an optical source, control light inputted from a control light input path is inputted into an LN-MZ optical modulator having traveling-wave type modulating electrodes from a direction opposite to signal light, and the average optical power is detected by a photodetector. A bias-voltage Vb is so generated that this optical power may be minimized, and is applied to a bias input terminal, whereby automatic bias stabilization control is performed.

Abstract: Disclosed is an optical cross connect apparatus that is applicable to an end office node and relay node in a path. The optical cross connect apparatus includes an optical switch for generating plural optical output signals from plural optical input signals; an optical level monitor section for detecting the optical levels of the optical input signals; and a control section that is connected to the optical switch and the optical level monitor section, includes a path switching management section for retaining a path switching management table, references the path switching management table when the optical input signals detected by the optical level monitor section are found to be OFF, and judges whether the optical switch should be operated.

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: In working path setting, a backup path is previously prepared assuming a link failure, and a demultiplexer of a bypass link is connected to a wavelength conversion repeater through an optical switch. Upon occurrence of a link failure, the wavelength conversion repeater is connected to a multiplexer of the bypass link by means of the optical switch to forward an in-channel control signal to the wavelength conversion repeater of an adjacent node where the in-channel control signal is sequentially forwarded to reserve a backup bandwidth. Then, output wavelengths and targets are exchanged between a wavelength tunable transponder and the wavelength tunable repeater.

Abstract: An optical switch having plural input terminals and plural output terminal, plural dispersion compensators, and a controller for monitoring the change-over state of the optical switch and the dispersion compensation quantities of the plural dispersion compensators and controlling the setting of the optical switch are provided. In response to a request for setting dispersion compensation, the optical switch is set according to the dispersion compensation quantity of each dispersion compensator and the change-over state of the optical switch.

Abstract: Repeating device connected to a local area network (LAN) which connects a plurality of telephones and relays communication between first and second telephones. The repeating devices include a unit for requesting during communication a response from another receiver-side telephone indicating its availability to receive a call, and a unit for notifying the address of the receiver-side telephone that responded to the caller-side telephone.