Hitachi, Ltd.

Hitachi Vlsi Engineering Corp.

Takanori Miyamoto

Toshiro Suzuki

Tohru Kazawa

Takashi Morita

Kazuhiro Kondo

Takashi Nishikado

Ichiro Masse

Eiichi Amada

Kenji Kawakita

Kazuo Nakata

Shigeo Nishita

Souichi Yamashita

Toshiroh Suzuki

Mutsumi Abe

Yuichi Taguchi

Takahiro Yamada

Akira Ichikawa

Kenichi Wada

Mitsuru Ikezawa

Kuniaki Tabata

Hirotoshi Shirasu

Yoshiro Suzuki

Yoshiaki Asakawa

Tatsuya Kameyama

Hiroshi Takatori

Taminori Tomita

Masami Yamagishi

Shigeaki Kinoshita

Ryujiro Muramatsu

Katsuyuki Miyazaki

Sumie Nakabayashi

Makoto Noumi

Shinichi Niina

Ichiro Mass'e

Toru Setoyama

Douglas Cardwell

Makoto Ujiie

Tomoharu Maehara

Masahumi Hino

Tomoshisa Kohiyama

A communication network including connection switching exchanges, such as an ATM, a connection management apparatus is provided in a network management unit of a communication network. A group of logical connections with a fixed group size and consecutive identifiers assigned to the connections is treated as a unit. The number of logical connections in the group is an integer with a power of 2. The logical connections and connection identifiers assigned to the logical connections are set up and released in connection setting units each equal to a multiple of the group size in a unitary manner across the network. A priority level is assigned to each connection setting unit. When logical connections have been set for connection setting units sharing the same connection identifiers, logical connections with the shared connection identifiers pertaining to a connection setting unit with a smaller size is considered to be valid.

Connection switching apparatus, connection switching network contol system and connection switching network control method

In a communication network constituted of relay nodes and edge nodes interconnected by communication lines and a network manager, the network manager manages relay nodes and edge nodes connected to the network manager by operation management communication lines. The network manager requests to set a logical connection between an ingress and an egress of the connection, and in response to this request, relay nodes and edge nodes set a logical connection specifying at least one of a transmission source and a destination.

Network manager, nodes and network management system

In a communication network including connection switching exchanges such as an ATM, a connection management means is provided in a network management unit of the communication network. A group of logical connections with a fixed group size and consecutive identifiers assigned to the connections is treated as a unit. The number of logical connections in such a group is an integer with power of 2. Logical connections in the communication network and connection identifiers assigned to the logical connections are set up and released in connection setting units each equal to a multiple of the group size in a unitary manner across the whole communication network. A priority level is assigned to each connection setting unit. When logical connections have been set for a plurality of connection setting units sharing the same connection identifiers, logical connections with the shared connection identifiers pertaining to a connection setting unit with a smallest size is considered to be valid.

Connection switching apparatus, connection switching network control system and connection switching network control method

A bidirectional communication system in which dial-up connection for transmitting communication data may be disconnected when not used, and may be insured to be reconnected when needed. Also, the system includes an arrangement in which availability of connection with dial-up may be notified/determined in advance. The bidirectional communication system includes a first communication station and one or more second communication stations, the second communication stations receiving information delivery service from the first communication station, and the second communication stations performing data communication with the first communication station by means of dial-up link. The first communication station includes: an assignor assigning to the second communication station a protocol identifier of a network layer; a connector/disconnector for connecting/disconnecting the communication link according to respectively the presence and absence of communication data from the second communication station; and a storage holding the protocol identifier of the network layer assigned to the second communication station during the information delivery service from the second communication station.

Bidirectional communication system

A multimedia system capable of readily permitting expansion of its display memory as well as its compression/expansion function and other features as desired. The multimedia system is implemented by an information processing apparatus which includes a controller which controls the apparatus, an extended input/output bus for connecting with the controller, and interface device which interfaces with the extended input/output bus, at least one function extending device which extends the functionality of the controller and a local bus for permitting data exchanges between the interface device and the function extending device.

Motion image display apparatus

In a subscriber information service system including a plurality of terminal equipment, and an information server for presenting personal information of a called subscriber to user at each of the terminal equipment, the information server being connected to the plurality of terminal equipment through a communication network, the information server has a subscriber information table consisting of a plurality of personal records each including a personal identifier assigned to a subscriber, a name of the subscriber, status information of the subscriber, and a name and an equipment address of the communication equipment which can be utilized by a user, and a facility of transmitting content data of the personal record of the specific subscriber registrated in the subscriber information table to each of the terminal equipment. Prior to the communication with the called subscriber, the user at each of the terminal equipment requests the information server to transmit the personal record of the called subscriber, and determines both the status of the called subscriber and the optimal communication equipment by referring to the contents of the personal record received from the information server.

Information network with server, call blocking, subscriber status, and

A screen communication method and system for communicating screen data between a plurality of interconnected terminal units each having a display part and an input part, wherein each time screen modifying data is input from the display part, each of the terminal units transmits a modifying right request to another terminal unit before transmitting the screen modifying data, and obtains a modifying right under such a condition that each terminal unit receives no screen modifying request from another terminal unit within a predetermined period of time after the transmission of the first modifying right request.

Screen communications system granting screen modifying requests if no

A multi-media server for treating multi-media information including video and voice information and a communication system including the multi-media server are provided. The multi-media server is suitable for the application and the system architecture for the multi-media information, a mail system utilizing animation and an application for editing a document. The multi-media server includes an interface circuit connected to a communication network and for controlling send/receive operations of a transmission frame, table memories for recording attribute information of each user terminal, a decoding circuit for decoding multi-media information included in the transmission frame received from the interface circuit by referring to the attribute information of the table memory, an information processing circuit for processing the decoded multi-media information according to the content of a header of the transmission frame, a coding circuit for coding the processed multi-media information according to the content of the header of the transmission frame, a memory unit for recording the coded multi-media information, and a controller for controlling the decoding circuit and the coding circuit to perform the processing for the kind of the multi-media information according to the content of the header of the transmission frame.

Multi-media server for treating multi-media information and

A digital communications system suitable for high-speed data transmission includes a transmitter and a receiver providing the ability to selectively switch between multiple coding and decoding methods. The transmitter includes a plurality of trellis coders, each of which performs a different type of coding on a transmission signal. The receiver includes a plurality of Viterbi decoders, corresponding to the different types of coders in the transmitter, for decoding the transmission signal. The receiver also includes a selector for determining which of the decoder outputs to choose from based on the frequency of code violations detected in the transmission signal. The present invention thus provides a flexible apparatus for improving the quality of high-speed data transmissions.

Digital communication system

Correlation code transmission system

Clock timing is extracted from N level, multilevel codes of megabits per second data by determining a baud clock among the N-1 possible clocks synchronized to all the level cross points. A discriminator is used with a clock and if correct information is not obtained, the clock is changed.

Timing extraction method and communication system

In a speech coding method and system in which a speech signal is analyzed in each frame so as to be separated into spectral envelope information and excitation information and both of the information are coded, each frame is divided into a plurality of sub-frames and a pulse of the maximum-amplitude is extracted from pulses within each sub-frame in order to provide large-amplitude pulses from each frame, thereby greatly reducing the number of pulse extracting processing steps.

Speech coding system and method

A speech coding system includes apparatus for generating a variable threshold dependent upon the power of an input speech signal, and a comparator for comparing the power of the input speech signal with the variable threshold value to generate a discriminating signal for discriminating between a period when a speech continues and a period when the speech pauses, to change the coding operation for the input speech signal in accordance with the level of the discriminating signal, thereby forming voiced and unvoiced frames independently of each other.

Speech coding system using variable threshold values for noise reduction

An echo suppressor for a communication system wherein a signal sent to a transmitting line is returned to a receiving line with some delay. The suppressor comprises an attenuator for attenuating the amplitude of a received speech signal. The transmitting speech signal amplitude level is compared to the amplitude of a receiving speech signal, and according to the result obtained, a signal for controlling the signal attenuation of the attenuator is generated. The delay time, until the attenuation control signal operates on the attenuator according to a change in the amplitude level of the receiving speech signal, is controlled. The controlled delay time is normally held at a predetermined maximum value, and is minimized when a change in amplitude of the receiving speech signal indicates a beginning of speech. Thus, an echo of the speech uttered by a near end user can be suppressed without impairing a beginning of the speech signal uttered by a far end user.

Echo suppressor

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Fuchu, Japan

Takanori Miyamoto