Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Tsuguhiro Hirose

Hiroshi Kobayashi

Hideaki Haruyama

Hideyuki Ueno

Yoshiharu Uetani

Yoshimitsu Shimojo

Yoshio Kojima

Tadahiro Oku

Yukio Kamatani

Mitsunori Omokawa

Jiro Kano

Toshihiko Muro

Katsunari Kodachi

Humio Takeda

Masahiro Takagi

Toshikazu Kodama

Takashi Kamitake

Chikara Yasuda

Ryuji Ito

Narito Kimura

Kazue Fujiwara

A video on demand system includes one or more hybrid fiber coax access networks connecting set top units to corresponding head end units. The head end unit for an access network is connected to an asynchronous transfer mode wide area network (ATM WAN). A hierarchical system of video servers, including at least one center server and at least one local server, or cache node, are also connected to the ATM WAN. When a user wishes to select a video, a service control unit coupled to the ATM WAN generates a selection list of proposed videos for which server and network resources are available to immediately serve the user-selected video. The service control unit determines whether server and network resources are available by sending separate queries to server and network resources management control units. Alternatively, the service control unit may generate the selection list based on whether the probability of a particular video being immediately served is greater than a threshold.

Video on demand system that presents users with a selection list of proposed videos for which server and network resources are available to immediately serve the selected video

A packet scheduling scheme capable of realizing a fair scheduling regardless of weights of connections. A packet scheduler has a plurality of packet queues for temporarily storing entered packets, to each of which a weight is set up; a packet input unit for entering packets into the packet queues; a scheduling information management unit for managing scheduling information for specifying an order to read out packets stored in the packet queues, according to a queue length of each packet queue and the weight set up for each packet queue; and a packet output unit for reading out and outputting desired packets from the packet queues according to the scheduling information. In a case of fixed length packets, the scheduling information management unit always holds as many scheduling information corresponding to one packet queue as a smaller one the queue length of that one packet queue and the weight set for that one packet queue, so as to make a processing time required for scheduling constant regardless of a number of connections.

Method and apparatus for packet scheduling using queue length and connection weight

An information transmit system includes a first communication element having a guaranteed quality required to transmit real-time information, and a second communication element different from the first communication element. The system also includes a transmission element for transmitting stored real-time information using the first communication element and for transmitting real-time data using the second communication element, where the real-time data using the second communication element has corresponding time stamps later in time than the real-time data transmitted by the first communication element. For example, a time stamp of the real-time data may be used to transmit the data in either a normal direction (using the first communication element), or in a retrospective direction (using the second communication element). The system also includes a storage element for storing the real-time data transmitted by at least the second communication element, and a switching element for monitoring a time stamp corresponding to the real-time data transmitted from the first communication element and a time stamp corresponding to the real-time data transmitted from the second communication element. The switching unit switches the output of the real-time information transmitted from the first communication element, to the output of the real-time data transmitted from the second communication element that is stored in the storage element, when the time stamp for reproducing the real-time data stored in the storage element has been reached.

Information transmission system utilizing both real-time data

A communication system housing a plurality of terminals capable of processing one or more media is provided with an available terminal information storage section for storing a terminal or terminals to be used for each user, an available media information storage section for storing a medium or media or a media realization scheme or schemes to be used for each terminal, a determination section for determining a combination of one or more media or one or more media realization schemes and a terminal combination of one or more terminals to be used by each user in accordance with the contents of the available terminal information storage section and the available media information storage section for each of users engaged in communications according to communication requests and a control section for controlling setting of call/connections based on the media combination and the terminal combination determined by the determination section.

Communication system and communication control method for the same

A panel for free access to a signal cable and a power cable is installed on the floor of an office room and forms a network of signal cables in an office. The posts of this panel are mounted on the floor. A floor plate is secured to the upper ends of the posts. A rack plate is arranged between the floor plate and the floor, and the rack plate is secured to the posts. The height of the floor plate and the rack plate is adjusted by adjusting the engaging position by rotating a leg to be engaged with the threaded holes of the posts. The floor plates are composed of a plate made of glass, reinforced cement mixed with foamable styrol or an aluminum honeycomb structure. The rack plate is composed of a transparent polypropylene plate. Further, the surface of the floor plate is covered with a surface material such as a carpet. The signal cables are arranged in the space between the floor plates and the rack plates. The power cables are arranged in the space between the rack plates and the floor. Electronic components are mounted on the rack plates. Therefore, the power cables, the signal cables and the other electronic components are completely isolated from each other, and the modification of the layout of office automation equipment can be readily carried out by an authorized person.

Panel for free access to signal cable and power cable

A traffic control method for controlling the traffic characteristics of fixed-length information units and transmitting the information units through a number of divided systems in a ATM communication network comprises a step for monitoring the information units to determine whether or not the information units are transmitted according to prescribed traffic characteristics at the inlets of a plurality of divided systems, a step for regulating the information unit which violates the prescribed traffic characteristics at the inlets of the divided systems, a step for monitoring the information units to determine whether or not the information units are transmitted according to prescribed traffic characteristics at the outlets of a plurality of divided systems, and a step for shaping the information unit which violates the prescribed traffic characteristics at the outlets of the divided systems.

Traffic control method and traffic control system for controlling cell

A time-division multiplexing communication network comprising a central station and a plurality of local stations, in which information signals are transmitted from the local stations to the central station on a time-division multiplexing basis, and the central station transmits information signals to the local stations on a time-division multiplexing basis. The central station sequentially requests that local stations transmit a test signal in order to prevent collision of transmission signals from the local stations. Each local station, of which a test signal transmission is requested, transmits the test signal to the central station. The central station sends back the test signal to the local station which transmitted this test signal. The local station measures transmission delay time from transmission to reception of the test signal, and adjusts transmission timing of the information signal to be transmitted to the central station based on the measured delay time.

System for adjusting signal transmission timing in time-division

An information transmission system in which a plurality of data terminal equipments (DTEs) are coupled with a communication medium through corresponding medium attachment units (MAUs). The DTE transmits and receives an information signal in a format having a preamble section including a predetermined bit pattern and a data section. The MAU modulates and demodulates the information signal. The MAU is arranged to replace part of the preamble with random data in order to quickly detect the collision of information signals from a plurality of DTEs on the communication medium.

Information transmission system in a local area network suitable for

In a communication network in which a plurality of information processors are coupled to a communication medium through medium attachment units (MAUs), a pilot signal generator sends a pilot signal of a reference level to a predetermined point of the communication medium. Each MAU has a gain controller to control the gains of transmission and reception amplifiers. This gain controller adjusts the gain of the reception amplifier when the pilot signal is received in accordance with the reception level thereof and then allows a test signal to be transmitted to the communication medium through the transmission amplifier. The gain of the transmission amplifier is adjusted in accordance with the reception level of this test signal such that the reception level of the test signal becomes equal to the reception level of the pilot signal. Each MAU is provided with a random number data generator and sets the transmission time slot of the test signal in dependence on random number data to prevent simultaneous transmission of test signals from MAUs.

Communication network having gain adjustment function of a transmission

A plurality of information processors are coupled by respective modems to a communication medium at points thereof. Transmission and reception of information signals among the modems are effected through a headed located at a predetermined point on the communication medium. A pilot signal generator is provided which sends out a pilot signal having a predetermined reference level through the headend to the communication medium. Each modem is arranged to properly adjust the gain of its transmitting amplifier according to a reception level of the pilot signal for an improvement of signal transmission quality and a reliable detection of a signal collision.

Information transmission system with modems coupled to a common

A local network, in which a plurality of data processors are coupled by modems to a communication medium, is disclosed. Each modem is arranged to shift a carrier frequency to a first and second frequency according to a digital signal from the associated data processor. In order to provide for reliable and quick detection of a collision of signals simultaneously transmitted from a plurality of modems to the communication medium, the difference between the first and second frequencies is set such that one cycle of a beat signal generated on the communication medium due to a collision of signals is not longer than one bit time length of the digital signal.

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Yokohama, Japan

Tsuguhiro Hirose