Fujitsu Corporation

Fujiisu Limited

Keiji Fukuda

Kazuhiko Ito

Takeshi Uehara

Shigehiko Yazawa

Toru Tachibana

A control channel junction line system for use with a digital switching network wherein a talking channel used in a control channel is used in a high efficiency is disclosed. Each exchange of the system includes a digital junction line trunk, a low rate information multiplexing trunk, a low rate control channel processing section and a multiplexing/demultiplexing section. When the low rate information multiplexing trunk is connected to a channel on which the control channel is to be carried, one of the circuits corresponding to a time slot used for control channel information is disabled. Upon transmission, the control channel information from the low rate control channel processing section and information from the low rate information multiplexing trunk are multiplexed with each other by and sent out from the multiplexing/demultiplexing section. Upon reception, the control channel information and the information the low rate information multiplexing trunk are demultiplexed by the multiplexed/demultiplexing section. The control channel information is processed by the low rate control channel processing section while the information to the low rate information multiplexing trunk is inputted to the low rate information multiplexing trunk.

Exchange connected to a control channel junction line

The subrate control channel exchange system uses a part of bits in a control channel time slot, for example, an 8-bit time slot in transmitting communications control data, and uses the rest of the bits in transmitting communications data such as voice, etc. For example, even if the transmission speed of a transmission line is 64 kb/s, the present invention aims at improving the utilization of the line when a speed of approximately 16 kb/s is applicable. In an ISDN network, which establishes communications by multiplexing communications data applied from a source terminal unit to a destination terminal unit over an exchange network together with communications control data, the present invention comprises a subrate exchange trunk for multiplexing in a single time slot only significant bits in low speed data applied from a plurality of low speed terminals connected to the exchange network, and a bit unit exchange switching unit for multiplexing in a control channel time slot an output of the subrate exchange trunk together with control data of fewer than 8 bits.

Subrate control channel exchange system

A system includes private lines for carrying respective signals which each have at least one D channel for control information, and plural B channels for data. The system also includes a multiplexer connected to the private lines, which receives the signals and generates a multiplexed signal for transmission on a digital multiplex interface. The system further includes a demultiplexer which receives the multiplexed signal received from the digital multiplex interface, to generate signals for transmission on the private lines. The multiplexer and demultiplexer are designed so that the total number of D channels and B channels can be changed without requiring significant effort or modification of either the multiplexer or the demultiplexer. The system also includes a testing device which transmits and returns a multiplexed signal from the multiplexer, to the demultiplexer. The returned multiplexed signal can be used to test the system without requiring involvement of external devices.

Growing community of inventors

Kawasaki, Japan

Keiji Fukuda