Abstract: An optical signal connection apparatus includes first and second routers configured to handle optical signals and electrical signals. A first node includes a first port coupled to the first router and is configured to handle a first type of optical signals associated with the first route; a first line-setting unit configured to couple the first and second nodes for data communication between the first and second nodes; a first control unit to control setting an optical communication link between the first and second nodes; and a first signal-type storage unit. A second node includes a second port coupled to the second router and configured to handle a second type of optical signals, wherein the first information is compared with second information on the second type of optical signal to determine whether the first and second communication links are compatible to each other.

Abstract: A packet transfer apparatus which can switch a communication path for each of a plurality of users using the same L2TP tunnel is provided. Packet transfer apparatuses terminating L2TP contain a table specifying a flow threshold level and a priority level of each subscriber; the amount of packet flow of each subscriber is measured in accordance with the information in the table; if the threshold level is exceeded, the packet communication path is switched in accordance with the priority level specified for each subscriber. The OSPF protocol is used to manage the path information, and the information of a plurality of paths to a destination is stored in a path management table. The path is switched by specifying destination routers with the source routing option in the IP header of a packet after L2TP encapsulation.

Abstract: A method and apparatus for controlling the power of a signal transmitted between a base station and a mobile terminal which constitute a mobile communication system. At least one of the base station and the mobile terminal has functions to compare a predetermined reference value and a necessary transmission power obtained as a result of transmission power control in order to compensate for a signal intensity fluctuation occurring on a link between the base station and the mobile terminal, temporarily stopping the transmission if the necessary transmission power is larger than a predetermined permissible value, and transmit the signal if the necessary transmission power is equal to or smaller than the predetermined permissible value.

Abstract: A Layer 2 switch manages distribution destinations of a multicast packet and distributes a copy of the multicast packet, so that the bandwidth wasted in a network is reduced. The Layer 2 switch is disposed between a user terminal and a packet transfer apparatus, which are connected by P2P, has a function to manage connected multicast users, receives a multicast packet on behalf of the users, and distributes a copy, to reduce the bandwidth wasted between the Layer 2 switch and the packet transfer apparatus.

Abstract: A dispersion compensating fiber whose chromatic dispersion is positive and a negative dispersion compensating fiber whose chromatic dispersion is negative are prepared, and division-multiplexed optical signals, after being guided to either dispersion compensating fiber to once shift the whole wavelength band to positivity or negativity, are subjected to fine adjustment with a dispersion compensating fiber of a reverse sign.

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: A network management apparatus inputs a plurality of work dates and time periods to update software in a base station. The apparatus obtains an n-week average of the numbers of connection calls during each of the input time periods for each day of the week, based on statistical information about connection with a wireless terminal in each base station. The apparatus obtains an m-month average of the numbers of connection calls during each of the input time periods for each date, based on the statistical information. The apparatus calculates, for each of the time periods for a work date, an average or a weighted average of the n-week average and the m-month average to obtain a degree of impact upon a communication service. A processing section selects a work date and a time period having the minimum degree of impact and updates the software.

Abstract: Mobile terminals have the problem of large packet loss during movement because the mobile terminal has no opportunity to detect movement and generate a new care-of address until a new router advertisement is received, and also cannot register the position in the home agent. The present invention is characterized in including a means to automatically collect network information on access router devices in the vicinity of a particular access router device, and a means to send information in the router advertisement including information on at least one or more adjacent access router devices. The mobile terminal selects an access router device to become the next movement destination, and the most essential characteristic is a means to register the position information beforehand in the home agent.

Abstract: An LAC manages multicast destinations, and forms and distributes copies of the multicast packets. An L2TP tunnel and an L2TP session are formed between LAC 1-i and LNS 2-i, and LNS 2-i is connected to network NW2 such as the Internet. Data is transferred between a subscriber and the network through the L2TP connection. LNS 2-i and sever S1 are connected through network NW2 which has routers. A packet transfer apparatus enables LAC 1-i to manage subscriber information and to form and distribute copies of the packets to the subscribers when server S1 on network NW2 distributes multicast packets of a program or the like to the subscribers.

Abstract: The linearity of a transmission signal is improved in a wireless communication device by adjusting a delay difference between paths of two signals that are combined into one after modulation through the paths of different delay amounts, such as an r signal and a ? signal in EER. A transmitter includes: a DA converter unit which converts, into analog signals, separated input digital signals; a combiner which combines the analog signals obtained through the DA conversion with each other; an distributor which extracts a feedback signal; an AD converter which converts the feedback signal into a digital signal; an oscillator unit which supplies clock signals to the converters; a first separation unit which separates the feedback signal; and a comparator unit which compares the input signal and the feedback signal, wherein the oscillator unit controls the output clock signals based on a result of the comparison.

Abstract: In the case of radio base stations of different kinds, a synchronization in a radio section cannot be established so that the efficiently effective use of electric waves cannot be retained. According to the invention, therefore, there is provided a TDMA type mobile communication system 100 comprising: a plurality of radio base stations of different system kinds (i.e., a general type radio base station 1, an IP connection type radio base station 10 and a main digital cordless phone 2); mobile phones 5A and 5B wirelessly connected with the plural radio base stations; and a private branch exchange 4 wired with the radio base stations. The radio base station receives, when a synchronized operation mode is decided, a frame signal containing a control CH signal, from a reference radio base station (i.e.

Abstract: A radio communication terminal, being used in a radio communication systems in which the transmission rate varies depending on radio wave conditions and communication statuses of other users, comprises a reception module which receives packets transmitted by a base station in an idle state of the radio communication terminal, a signal processing module which estimates a transmission rate available in communication based on the packets received by the reception module, and a display module which displays information indicating the transmission rate estimated by the signal processing module.

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: A radio communication terminal, being used in a radio communication systems in which the transmission rate varies depending on radio wave conditions and communication statuses of other users, comprises a reception module which receives packets transmitted by a base station in an idle state of the radio communication terminal, a signal processing module which estimates a transmission rate available in communication based on the packets received by the reception module, and a display module which displays information indicating the transmission rate estimated by the signal processing module.

Abstract: The normality verification and radio characteristics test of a radio communication system are executed. RF-SWs (radio-frequency coaxial switches) change-over the paths of signals which are transmitted to and received from an access terminal function portion included in an access point. RF-SWs connect the access terminal function portion 122 with a desired one of radio analog portions. A test function controller controls the changeover operations of the RF-SWs in accordance with information designated by a maintenance apparatus (OMC).

Abstract: Adaptive modulation/demodulation method in a radio communication system is provided. A modulation multi-level number in a transmission device and a demodulation multi-level number in a reception device are judged independently from each other according to a propagation condition and communication is performed by controlling the likelihood when the multi-level numbers of the transmission side and the reception side are different. The reception device can perform operation by controlling likelihood information on lower bit of the multi-level modulation even when the modulation multi-level number and the demodulation multi-level number used at the transmission side are different. Moreover, the transmission device and the reception device independently decide the modulation multi-level number and the demodulation multi-level number, thereby following an instantaneous propagation fluctuation and improving the throughput.

Abstract: A radio communication apparatus enhances cell throughput by adaptive selection of spatially multiplexed channels in consideration of interferences in a local cell and reducing load for calculation of array weights by storing them in advance as fixed values and outputting fixed beams. To reduce the calculation load for the adaptive selection of spatially multiplexed channels that takes interferences within the local cell into consideration, the radio communication apparatus adopts a packet scheduling method that selects a combination of fixed beams and determines the number of spatially multiplexed channels, based on the fixed beams for mobile apparatuses with packets waiting to be transmitted and pre-calculated correlative quantities of inter-beam interferences between these fixed beams.

Abstract: In a time-interleaved AD converter which combines together low-speed high-resolution AD converters for effective high speed operation, various deterioration factors possessed by each of the converters, including DC offset, conversion gain error, sampling timing error, and a frequency characteristic, need to be compensated. The compensation is performed through nonlinear filter operation in which a constant term is added to linear filter operation. A high-speed low-resolution AD converter is separately used, and through adaptive signal processing in which an output signal thereof is defined as an instruction signal, a compensation coefficient is calculated. In this condition, the compensation can be performed without the influence of quantization noise attributable to the high-speed low-resolution AD converter.

Abstract: A telephone applicable to PSTN and IP network having functions of obtaining, when a call is originated by entering a PSTN telephone number, an IP network telephone number of a destination telephone corresponding to the PSTN telephone number from a telephone number translation server connected to the IP network, obtaining IP address information of the destination telephone corresponding to the IP network telephone number from a call agent connected to the IP network, establishing call connection with the destination telephone via the IP network by using the IP address information, and establishing call connection with the destination telephone via the PSTN if the IP network telephone number of the destination telephone cannot be obtained from the telephone number translation server.

Abstract: A reception sensitivity is measured at a high precision. An access terminal function portion includes the transmitter part and receiver part of a communication terminal in a radio communication system. A path switch part effects switching so as to connect the input ends of receivers to antennas or to terminate them. The path switch part switches the paths of a signal from a transmitter and signals toward the receivers. An access point controller adjusts a packet error rate into a predetermined range, and obtains the reception sensitivity on the transmission power of the access terminal function portion after the adjustment.