A LOAD SENSITIVE SWITCHING NETWORK SYSTEM

• US 3,591,724 A
• Filed: 07/13/1967
• Issued: 07/06/1971
• Est. Priority Date: 07/15/1966
• Status: Expired due to Term

• Current Assignee: Fujiwara Kunihiko, Isizaki Shogo, Ohzeki Kazuya, Yaku Tadao, Yamaki Tatsumi
• Original Assignee: Fujiwara Kunihiko, Isizaki Shogo, Ohzeki Kazuya, Yaku Tadao, Yamaki Tatsumi
• Inventors: YAKU TADAO, ISIZAKI SHOGO, FUJIWARA KUNIHIKO, OHZEKI KAZUYA, YAMAKI TATSUMI
• Application Number:
  US04/653,212
• Time in Patent Office: 1,454 Days
• US Class Current: 379/137
• CPC Class Codes: H04Q 3/54 in which the logic circuitry controlling the exchange is centralised
• CPC Class Codes: H04Q 3/54591 Supervision, e.g. fault localisation, traffic measurements, avoiding errors, failure recovery, monitoring, statistical analysis

Abstract

A plurality of common control automatic switching offices are each provided with an '"'"''"'"''"'"''"'"'exchange-trunk information'"'"''"'"''"'"''"'"' unit for deriving exchange-trunk or load information representing the load or capacity of the exchange and the interoffice trunk groups extending from the exchange. One of the offices is equipped with an '"'"''"'"''"'"''"'"'availability information'"'"''"'"''"'"''"'"' unit for translating the exchange-trunk information sent from all the exchange-trunk information units into availability information representing whether the exchanges and the interoffice trunk line groups are available for new calls. Each office is further provided with means responsive to the availability information for controlling the establishment of the connection.

Claims

1. A switching network having a plurality of switching offices, each including switching means, a plurality of trunk lines, each extending between switching means in a predetermined two of said offices, wherein the improvement comprises:

a load information unit in at least two of said switching offices for producing, in response to interrogation, by the availability information unit a load information signal substantially representative of the number of unoccupied switching means and trunk lines thereat;

an availability information unit coupled in common to said load information units and including means for respectively translating said load information signals into availability information signals representative of the availability of said switching means and trunk lines in establishing a new connection; and

means at the switching offices having said load information units for controlling the switching means in response to said availability signal.

2. A switching network as claimed in claim 1, wherein said availability information unit further comprises means for supplying an interrogation signal, means for intermittently transmitting the interrogation signal from said source simultaneously to said load information units.

3. A switching network as claimed in claim 2, wherein said availability information unit further comprises:

a first memory for permanently storing criterion numbers for the respective interoffice trunk line groups to which the switching offices having the respective load information units are connected, each of said criterion numbers representing a standard for determining the relative availability of trunk line groups, an arithmetic unit for producing binary coded signals, each representing the difference between one of the numbers represented by said load information signals and the corresponding one of said criterion numbers, means for successively supplying said arithmetic unit with criterion signals representative of said criterion numbers simultaneously with the corresponding load information signals, a second memory for storing said binary coded signals generated by said arithmetic unit, and means for transmitting said binary coded signals, each representative of availability information associated with one of said load information units, from said second memory simultaneously to said load information units as availability information signals.

4. A switching network as claimed in claim 1, each of said switching offices having controlling means including connection control relays for extending a communication path from the associated office when there are some outgoing interoffice trunk lines available, from among the interoffice trunk line groups connected to said office, for extending said communication path in the last-mentioned interoffice trunk line groups, wherein said controlling means comprises:

terminals assigned to said switching offices, respectively, on a particular one of which a predetermined potential appears when the office the particular terminal is assigned to is called, connection inhibition relays for inhibiting, when energized, operation of the pertinent ones of said control relays, and switch means disposed between the terminals assigned to the switching offices having said load information units and said inhibition relays and operable by said availability information supplied from said availability information unit for energIzing one of said inhibition relays that inhibits operation of those control relays which would establish the communication path through the interoffice trunk line group whose availability information shows that the last-mentioned interoffice trunk line group is not available for any new call.