Hitachi Telecom Technologies, Ltd

Tatsuhiko Ando

Toru Watanabe

Yuji Kobayashi

Masumi Kumakura

Kanichi Sato

Kan-ichi Sato

Opportunities to transmit ATM cells of identical level onto an ATM line are equally afforded to respective terminal side lines. In a cell assembler/disassembler, data from the terminal side linesare turned into ATM cells, and the ATM cells are assigned priority levels. Then, the ATM cells are stored in internal buffersrespectively corresponding to the terminal side lines. The priority controllerselects the ATM cells of the highest priority levels from within the respective internal buffers, and further selects the ATM cell of the highest priority level as an ATM cell to-be-transmitted from among the selected ATM cells. In the presence of a plurality of such ATM cells of the highest priority level, the priority controllerdetermines the ATM cell to-be-transmitted in accordance with the priority sequence of the internal buffers in which the ATM cells of the highest priority level are stored. Each time the priority controllerselects the ATM cell to-be-transmitted, it alters the priority sequence of the internal buffers so that the priority sequence of the internal buffer having stored the ATM cell to-be-transmitted therein may become the latest.

Multiplexer and priority control method for packet data transmissions

A circuit size of a multiplexing apparatus is reduced. In terminal interface unitsto, data from a terminal is received by each of terminal-side line interface sub-unit, and then celluralized by a cell assembly/disassembly sub-unit. The cell is transmitted directly to a priority control unit. In the priority control unit, the cell received from each of the terminal interface unitstois stored in each of priority control buffers, and then sent to an ATM network interface unitin the order of priorities sequentially. The cell is synchronized with a line of an ATM networkby a network synchronizing sub-unit, and transmitted to the line of the ATM network. With this constitution, an internal bus is unnecessary.

Multiplexing apparatus

A plurality of digital telephones 2A, 2B are provided in direct multiple connection with a digital line 4 introduced from a private branch exchanging system. Each of the digital telephones 2A, 2B sends a burst signal containing its own telephone call data, and burst signals from the telephones 2A, 2B are combined into a single burst signal on the digital line 4 to transmit communication data of the telephones 2A, 2B in the form of the single burst signal to the private branch exchanger 1.

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Koriyama, Japan

Tatsuhiko Ando