Fujitsu Corporation

Tetsuo Tachibana

Tetsuo Nishino

Osamu Isono

Toshimasa Fukui

Eisuke Iwabuchi

Ryuji Hyodo

Tatsuru Nakagaki

Satoshi Kakuma

Ryoichi Ishibashi

Kazuo Hajikano

Satoshi Kuroyanagi

Ryuichi Takechi

Takeshi Kawasaki

Masami Murayama

Hiroshi Tomonaga

Jyoei Kamoi

Toshio Shimoe

Toshio Irie

Emi Hata

Toshiyuki Hijikata

Tadahiro Takase

Masayuki Yamanaka

Teruaki Hagihara

Mikio Nakayama

Katsumi Oomuro

Yuzo Okuyama

Makoto Adachi

Katsutoshi Inoko

Naoyuki Miyamoto

Youzou Iketani

Hiroyuki Suzuki

Shunji Abe

Takashi Hatano

Kenji Nemoto

Hichiro Hayami

Hisakazu Ohmori

Koichi Ohno

Koso Murakami

Tsuyoshi Yoneta

Maki Takama

Satoshi Makuma

The object of the present invention is accomodating local connectionless information (data that is immediately transferred without establishing a path to a receive side), such as LAN data in a local area network, by an asynchronous transfer mode (ATM) network using a connection-oriented communication system (which makes data transfers after verifying that a path to the receive side has been established), thereby performing efficient, fast routing of connectionless information. A connectionless communication system of the present invention is equipped with connectionless information cell assembly/deassembly means for bi-directional conversion between variable-length connectionless information and fixed-length connectionless cells, routing control means for analyzing a destination address of information in connectionless cells and controlling the routing of the connectionless cells; and an ATM network for connecting the connectionless information cell assembly/deassembly means and the routing control means by a permanent virtual channel serving as a fixed path and connecting the routing control means together by a virtual channel serving as a semi-fixed path, whereby connectionless information is segmented into connectionless cells and the connectionless information is exchanged within the ATM network in connectionless cell units.

Connectionless communication system

A picture distribution service system carries out a distribution control of picture information service in a broadband transit switching network having a hierarchical structure. The system comprises a plurality of transit switches for switching transit lines through which picture information is transmitted from a source and distributed by a center switch, a first trunk part provided for each of the transit switches for distributing the picture information from the center switch to the transit lines, a plurality of subscriber switches for switching subscriber lines through which the picture information from each of the transit lines is transmitted to a plurality of subscriber terminals, and a second trunk part provided for each of the subsriber switches for distributing the picture information from each of the transit switches to the subscriber lines.

Picture distribution service system

By transmitting an analog CATV signal output from a CATV-HE (CAble TeleVision-Head End) to an HDT (Host Digital Terminal), an analog transmission channel for transmitting the analog CATV signal to an ONU (Optical Network Unit) is included in a path housing a digital transmission channel for transmitting a digital service signal for individual distribution service to the ONU. Furthermore, a digital service signal for multicast service is modulated and converted into an analog service signal by a modulator in the HDT. Then, the converted signal is mixed with the analog CATV signal, and transmitted to the ONU. Accordingly, each of the ONUs is equipped with only a built-in modulator for modulating the digital service signal for individual distribution service.

Mixed analog-digital service distribution system and method

Information selectively read out from an information source storing various types of information is repeatedly sent from a center office to a number of terminal equipment units with an error check code added on. The terminal equipment units use the error check code to detect if there is an error in the received information. If the information is received without error, the reception operation is ended for each terminal equipment unit. In this case, there is no interposition of a protocol for confirming if the transmission and reception of the information had been performed normally, so the load on the center office is lightened and it is possible for each of the terminal equipment units to receive the information without error.

Information broadcasting system confirming the reception of information

CPCS-UU in the CPCS-PDU trailer defined by the AAL Type 5 in an ATM network is used as a sequence number for error handling. CPCS-UU in the CPCS-PDU trailer is used as a sequence number of an MPEG-2 transport stream packet contained in CPCS-PDU; by monitoring the number of packets, and based on the check results of CRC-32, LI, and cell count, error handling is performed at the receiving end, and for corrupted packets, null packets are inserted in place of the corrupted packets.

Error handling in transmission of data that cannot be retransmitted

A media information distribution service system, such as a video-on-demand service system, is disclosed which, even if the capacity of a line is small and the number of lines connected to a media server, such as a video server, has to be increased accordingly, permits an uneconomical increase in the number of line circuits in the media server to be checked. In the system, a subscriber group that a distributor accommodates can be associated with a plurality of distributor-side paths on a distributor-side line. Each of the distributor-side paths is connected to a respective one of server-side paths on separate server-side lines connecting the media server and an exchange. In sending media information to a subscriber group, an in-server path control unit installed in the media server is permitted to select a free one out of server-side paths on server-side lines allocated for that subscriber group and activates a line interface corresponding to the free server-side path.

Media information distribution services system and method

A communication system for use with a network for transmitting fixed-length cells from a transmitting terminal via a virtual connection in the network to a receiving terminal. The communication system includes a converting device, connected to the transmitting terminal or the receiving terminal, for performing a bi-directional conversion between a variable-length packet and the fixed-length cells, the transmitting terminal or the receiving terminal outputting the variable-length packet, a buffer capacity monitoring device in the receiving terminal for monitoring a capacity of a buffer in the receiving terminal receiving the fixed-length cells and for outputting an alarm signal at the time of detecting a congestion state of the capacity of the buffer, a congestion state alerting device in the receiving terminal responsive to the alarm signal from the buffer capacity monitoring device for outputting an alert signal to the transmitting terminal, and a traffic transmission control device in the transmitting terminal responsive to the alert signal from the congestion state alerting device in the receiving terminal for controlling a transmission of the fixed-length cells to the receiving terminal.

An internal timing information producing portion produces internal timing information IRTS1 to IRTS4 which is the timing information on a data reception clock by using a network clock C.sub.N and the data reception clock C.sub.RU. A calculator calculates the difference between the internal timing information IRTS1 to IRTS4 and the transmission timing information RRTS1 to RRTS4 contained in a received cell, and a data reception clock producing portion adjusts the timing of the data reception clock C.sub.RU so that the difference is zero and outputs the adjusted timing. An ATM cell decomposing portion outputs the user data D.sub.RU in synchronism with the data reception clock C.sub.RU which is input from the data reception clock producing portion.

Interface device

A communication system for transmitting a fixed-length cell converted from a variable-length information including data and a destination of the data. The system includes a cell assembly/disassembly device for performing bi-directional conversion between the variable-length information and the fixed-length cell, a routing control device for receiving the fixed-length cell converted from the variable-length information by the cell assembly/disassembly device, for analyzing the destination of the data and for controlling a routing of the fixed-length cell based on the analyzed destination, and having an error detecting device for detecting an error of the variable-length information in the fixed-length cell, and a network for connecting the cell assembly/disassembly device and the routing control device by a fixed capacity path and for connecting the routing control device to another routing control device by the fixed capacity path or a variable capacity path.

A cell dropout preventing system includes a memory for temporarily storing cells which are obtained by dividing transmitting data into cells having a fixed length, an address generating part for generating a read address signal of the memory, a controlling part for controlling the address generating part based on a timing signal received from a line side and for transmitting to the line side the cell read from the memory by the read address signal generated from the address generating part, and a read completion detecting part for outputting a detection signal when it is detected that one cell is read completely from the memory. The controlling part controls the address generating part so that a cell which is the same as a previous cell is read from the memory and transmitted to the line side when no detection signal is received from the read completion detecting part.

System for preventing cell dropout on the transmitting side using timing

Information broadcasting system having reception error minimizing

The invention is to offer a technology with which a call process, a band setting process in particular, from a unit of terminal equipment to a network can be effectively performed, in relation to a communication system in which a communication band necessary for a unit of terminal equipment is secured by transmitting a SETUP message to a network from the terminal equipment as in the case of a call procedure in B-ISDN, etc. In the communication control of the terminal equipment connected to the network, when a call is made if the securing of a band in the network is impossible, the call is cut off, but if the band area in the network is insufficient for an initial band value stored in a SETUP message, a revised band value is produced by subtracting a certain value from the initial band value, and a SETUP message with the revised band value is retransmitted to the network.

Band management system in communication

Interface device between a network and an exchange for assembling

A length of an I field of an I frame in the data link layer is controlled in accordance with a rate of cells lost in an ATM layer. The loss rate of cells is calculated by watching sequence numbers included in the cells in an ATM adaptation layer.

Frame length control in data transmission using ATM network

An apparatus for controlling cells which are to be input to an ATM switch includes a buffer circuit for storing a cell directed to the ATM switch, and a memory for storing, for each of different calls, the number of cells which are in the ATM switch. The apparatus includes a periodic calculation circuit for periodically changing the number of cells for each of the different calls by an operation value, and a control part for determining whether the cell stored in the buffer circuit should be output to the ATM switch or discarded by referring to the number of cells which is stored in the memory and related to the cell stored in the buffer circuit.

Apparatus and method for controlling cells input to ATM network

Growing community of inventors

Kawasaki, Japan

Tetsuo Tachibana