Hitachi, Ltd.

Hitachi Software Engineering Company, Ltd.

Hitachi Communication Systems, Inc.

Hitachi Communications Systems, Inc.

Masashi Hiraiwa

Atsuo Hatono

Shinichi Hamamoto

Kenji Kawakita

Tatsuo Mochinaga

Satoru Inazawa

Yoshiaki Asambo

Noboru Mizuhara

A regulation apparatus for ATM cell delay variation includes a variation regulating buffer for temporarily storing cells transferred thereto, a variation waiting timer for controlling a waiting time which extends from reception of the first cell to read-out of cells from the buffer, a read-out timer for controlling intervals at which cells are read from the buffer, a latest cell preservation memory for storing the latest cell transferred from a VPI/VCI demultiplexing unit and, a selector for selecting a cell stored in the buffer or in the memory to transfer the selected cell to a cell reproduction unit. The invention further includes a communication type discriminator for discriminating a communication type in a call set-up phase upon starting a communication and for calculating a variation waiting time in accordance with the discriminated communication type to set the calculated variation waiting time to the variation waiting timer, and a dummy cell inserting circuit for inserting the last reaching cell as a dummy cell if a cell delay time cannot be regulated by the variation waiting time in a communication of sound or moving images.

Regulation method and apparatus for ATM cell delay variation

A cell/packet assembly and disassembly apparatus is provided for efficiently connecting a line in a line switching system to an ATM network or a packet network, without causing congestion, to transmit and receive cells or packets therebetween. The cell/packet assembly and disassembly apparatus, upon detecting a call setting request outputted from a line switch board in response to a call originated from a terminal, starts cell assembly and cell disassembly of user information transmitted and received between a channel on a line in the line switching system corresponding to the call setting request and a virtual channel on the ATM network assigned to the channel. Also, when detecting a call setting request outputted from a predetermined virtual channel in the ATM network, the packet or cell assembly and disassembly apparatus starts cell assembly and cell disassembly of user information transmitted and received between the virtual channel on the ATM network corresponding to this call setting request and a channel on a line in the channel switching system assigned to the virtual channel.

Cell/packet assembly and disassembly apparatus and network system

A regulation apparatus for ATM cell delay variation includes a variation regulating buffer for temporarily storing cells transferred thereto, a variation waiting timer for controlling a waiting time which extends from reception of the first cell to read-out of cells from the buffer, a read-out timer for controlling intervals at which cells are read from the buffer, a latest cell preservation memory for storing the latest cell transferred from a VPI/VCI demultiplexing unit and, a selector for selecting a cell stored in the buffer or in the memory to transfer the selected cell to a cell reproduction unit. The invention further includes, a communication type discriminator for discriminating a communication type in a call set-up phase upon starting a communication and for calculating a variation waiting time in accordance with the discriminated communication type to set the calculated variation waiting time to the variation waiting timer, and a dummy cell inserting circuit for inserting the last reaching cell as a dummy cell if a cell delay time cannot be regulated by the variation waiting time in a communication of sound or moving images.

An ATM switch system having a traffic control function to reduce cell loss probability and delay of cells communicated through a network to be equal to or less than acceptable values, respectively. To achieve traffic control function, the invention provides a circuit to observe the queue of cells in the buffer, and an overflow testing circuit for obtaining a distribution of the queue size according to observed values of the queue and testing to decide, according to the distribution, whether an event has occurred that the cell loss probability is shifted due to the input cells to a distribution related to a cell loss probability exceeding an upper-limit value of acceptable cell loss probability. The invention also provides an underflow testing circuit for testing, according to the distribution, whether an event has occurred that the cell loss probability is shifted to a distribution related to a cell loss probability less than a lower-limit value of acceptable cell loss probability such that the read delay and interval of input cells are altered according to outputs from the overflow and underflow testing circuits.

ATM exchange, ATM multiplexer and network trunk apparatus

A cell/packet assembly and disassembly apparatus is provided for efficiently connecting a line in a line switching system to an ATM network or a packet network, without causing congestion, to transmit and receive cells or packets therebetween. The cell/packet assembly and disassembly apparatus, upon detecting a call setting request outputted from a line switch board in response to a call originated from a terminal, starts cell assembly and cell disassembly of user information transmitted and received between a channel on a line in the line switching system corresponding to the call setting request and a virtual channel on the ATM network assigned to the channel. Also, when detecting a call setting request outputted from a predetermined virtual channel in the ATM network, the packet or cell assembly and disassembly apparatus starts cell assembly and cell disassembly of user information transmitted and received between the virtual channel on the ATM network corresponding to this call setting request and a channel on a line in the channel switching system assigned to the virtual channel. Further, when detecting the reception of a call disconnect request from the line switch board or from a predetermined virtual channel in the ATM network, the packet or cell assembly and disassembly apparatus stops the cell assembly and the cell disassembly of the user information transmitted and received between the corresponding virtual channel and the channel on the line in the line switching system.

Cell/ packet assembly and disassembly apparatus and network system

A switching system between two offices connected by plural digital lines and an outband channel. Each digital line has plural channels, and each channel has a corresponding basic bit rate and is able to multiplex plural sub-rate channels so as to accommodate sub-rate calls. When one of the offices requests the setting of a sub-rate call, a digital interface system designates to the other office, through the outband channel, a sub-rate channel to be used and attribute information concerning the sub-rate channel. If the designated sub-rate channel is not usable by the receiving office, a control unit at the receiving office selects a usable sub-rate channel and informs the originating office that the sub-rate channel is changed to the usable sub-rate channel.

Digital interface system for offices connected by plural digital lines

A method and system for arranging a common channel signal through an ISDN in a switching network. In the switching network, a signal is transferred between the switching stations in a common channel signalling manner. This method and system serves to allocate a signal path between the stations through the ISDN without having to provide a dedicated channel between the stations as a common channel signal path. Then, the method and system establishes a temporary connection between the stations through the ISDN using a channel in the ISDN (for example, D channel) used for controlling the call setup between the ISDN and a terminal and transfers a common channel signal between the stations by transferring transparent user information to the ISDN. In the common channel signal network in which a common channel signal is transferred through a leased line, the signal transfer is switched from the leased line to the ISDN when failure takes place in the common channel signal path.

Method and system for arranging common channel signal network through

Sub-rate calls of 8.sup.k .times.n bps (where n=1, 2, . . . ) are multiplexed in any combination on a digital transmission path having a basic (unit) bit-rate (64 kbps) as a unit. In order to set a sub-rate call of 8.sup.k .times.n bps in response to a call setting request from a low-speed data terminal, if a circuit switching call of 64 kbps is already set between the switching offices and the multiplex communication can be made at a rate required by the sub-rate call, the multiplex operation is made on 64 kbps circuit switching call to set the sub-rate call between terminals. On the other hand, if the sub-rate call can not be set, a circuit switching call having a new basic bit rate (64 kbps) is set between the switching offices at a time of occurrence of the sub-rate call if necessary to set the sub-rate call between the terminals.

Digital interface system

A switching control system is provided for an electronic switcher employing a common channel signalling. This system is designed to keep the common channel signalling for a speech path in parallel to the associated signalling system, invalidate the speech information in the associated signalling system for a speech path if the signal link is in a normal state and control the speech path in the common channel signalling system, and if failure takes place on the signal link, control the speech path in the associated signalling system.

Switching system for electronic switcher

An exchanging system in which data is transferred between a plurality of exchange offices connected to a switch network such that data is transferred between files associated with the respective exchange offices. The exchanging system includes a user process for outputting an input/output request to a file of a particular exchange office of a user, an input/output control unit operative in response to the input/output request from the user process for outputting an access request to an exchanging system of another particular communicating exchange office to which the file belongs, and a signal connection unit operative based on the access request for outputting signal connection control information to the particular exchange office to establish a connection to the exchange office to which the particular file belongs.

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Yokohama, Japan

Masashi Hiraiwa