Multiplex communications – Fault recovery – Bypass an inoperative station
Patent
1997-07-03
2000-03-07
Ton, Dang
Multiplex communications
Fault recovery
Bypass an inoperative station
370440, H04L 1228
Patent
active
060349441
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a communication system configured from a communication network which connects data generating sources and data receivers to data processing centers charged with the centralized control of these various devices when the data generating sources or data receivers are arranged in a straight line or a loop.
BACKGROUND ART
Typical examples of communication systems comprising data generating sources arranged in a straight line or a loop, these data generating sources being connected via transmission paths to data processing centers that centrally control these devices are railroad management systems, road management systems, sewer management systems, airport management systems, river management systems and subway management systems.
In a railroad management system, a control center exists within an administrative territory, monitoring cameras and train detection sensors are positioned along the railway within the administrative territory, and information from these cameras and sensors is collected at the control center. Signal devices and other means of communicating control information to trains are also positioned along the railway. Accident information from adjacent administrative territories is also collected at the control center, where various judgements are made using this information and the information from the administrative territory in question, and then based on the results of these judgements, the operation of the trains is controlled and other railway management procedures are implemented using signal devices and such.
As can be gleaned from this example of a railroad management system, with this type of communication system, information has been collected via communication lines connecting data generating sources to the control center on a one-to-one basis, and control of signal device displays has been implemented via communication lines running from the control center on a one-to-one basis. However, developments aimed at making asynchronous transfer mode (ATM) switching systems more practical have made rapid progress recently, and by applying this ATM technology to communication systems such as the one described above, it has become possible to construct flexible systems that make the most of the advantages offered by ATM.
FIG. 13 outlines the system configuration achieved by applying ATM technology to the various management systems described above, and more particularly, what happens when a fault occurs. This system is configured with a plurality of distributed switching components (92), which are connected to a center switching component (91) via transmission lines (93). If a fault (95) similar to the one indicated by the X in the figure were to occur in this system today, switching components (92-2 and 92-3) adjacent to the fault point (95) would each execute loopback, thereby making it possible for the system to autonomously recover communication functions via the route indicated in the figure by the dotted line.
Thus, it is possible for a system with the above-cited configuration to use loopback to maintain communications when a fault occurs, but when this communication system was applied to an actual railroad management system, the below-described problems arose. A railroad management system could be configured as shown in FIG. (14), comprising switching components (92-1-92-5) distributed along both sides of the railway (rail 100), a control center-based center switching component (91) that controls each of the switching components (92-1-92-5), this center switching component (91) being connected to each of the switching components (92-1.about.92-5) via loop-shaped transmission paths (93). Each of the switching components (92-1-92-5) is then equipped with input/output ports (94), with local communication terminals equivalent to the above-described monitoring cameras, train detection sensors and/or signal devices being supported via these input/output ports (94).
However, with this configuration, when an earthquake or some other disaster
REFERENCES:
patent: 4561088 (1985-12-01), Champlin et al.
patent: 5049871 (1991-09-01), Sturgis et al.
Kunikyou Tomoo
Obara Keiichi
Sakajiri Hirotaka
Seki Yutaka
Turuta Hidekazu
Ho Tuan Q
Kabushiki Kaisha Toshiba
Ton Dang
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