Path finding system for time-division multiplexed telephone communication network

Claim 2

A path finding system for a time division multiplex communication network comprising a multi-stage switching arrangement including at least on input stage, intermediate stage and output stage, each stage being formed of a number of time switches, each having a number of incoming network lines and a number of outgoing network lines, each network line including a plurality of time channels and the switches having the same internal time division switching arrangement, said system comprising: a central storage means coupled to said intermediate stage for storing the busy or free condition of all the time channels of the incoming and ouTgoing network lines of each time switch in said intermediate stage; and means, coupled between said central storage means and said intermediate stage, for reading into said storage means the condition of each intermediate time switch and for writing in each intermediate time switch the busy or free condition of each time channel in the incoming and outgoing network lines.

Claim 3

A path finding system according to claim 1, wherein each time switch comprises n input network lines and m output lines; each intermediate time switch comprises p inputs and q outputs each output time switch comprises m inputs and n outputs; said input stage comprises n input time switches; said intermediate stage comprises m intermediate time switches; and said output stage comprises n output time switches, wherein each network line comprises the same number of time channels, there being the same number of intermediate incoming network lines between input time switches and said intermediate time switches, and the same number of intermediate outgoing network lines between said intermediate time switches and said output time switches, and wherein said storage means, by storing therein the condition of each intermediate time switch, can enable the establishment of two paths through said system, one in a direction from the calling party to the called party, the other in a direction from the called party to the calling party, when a communication is to be set up between calling and called subscribers through said network.

Claim 4

A path finding system according to claim 2, including means for effecting a communication path between the calling and called subscribers over two separate paths each of which traverses the input stage, intermediate stage and said output stage, in the same direction.

Claim 5

A path finding system according to claim 3 wherein each network line includes 32 time channels and wherein each intermediate time switch has the same number of inputs as outputs, thereby forming a square matrix switch, each intermediate time switch having n incoming intermediate network lines and n outgoing intermediate network lines, and wherein said central storage means comprises, for every intermediate time switch 2n words of 32 binary elements, so as to store the condition of one of said intermediate time switches.

Claim 6

A path finding system according to claim 3, wherein said network comprises only three stages, including an input stage comprising p input time switches each with n inputs and m outputs, an intermediate stage comprising m intermediate time switches each with p inputs and q outputs, an output stage comprising q output time switches each with m inputs and n outputs, each input time switch receiving n incoming network lines with x time channels and its m outputs being connected to respective inputs of the m intermediate time switches, each output time switch having n outgoing network lines with time channels, the m inputs of each output time switch being connected to the respective outputs of the m intermediate time switches, the p inputs and q outputs of each intermediate time switch being thus respectively connected to the p input time switches and the q output time switches, so that the network thus determined comprises n2 incoming lines and n2 outgoing lines, so that a connection between any time channel of the n2 incoming network lines and any time channel of the n2 outgoing network lines is possible, whereby a communication may be provided with or without blocking with respect to the number m of time switches in said intermediate stage.

Claim 7

A path finding system according to claim 3, wherein said system employs three stages, the input stage comprising n time switches with m inputs and (2n-1) outputs, the intermediate stage comprises (2n-1) time switches with n inputs and n outputs and the output stage comprises n time switches with (2n-1) inputs and outputs, a portion of said multiplex connections being connected between said (2n-1) outputs of each of said input time switches and the inputs of the (2n-1) intermediate time switches, while the other of said multiplex connections are connected between the (2n-1) inputs of each output time switch and the (2n-1) intermediate time switches, whereby a time division multiplex network is formed without blocking having n2 incoming network lines and n2 outgoing network lines.

Claim 8

A path finding system according to claim 3, wherein in response to the state of an incoming network line and one of the time channels associated therewith, and the state of an outgoing network line and one of the time channels associated therewith, a communication path is provided between the calling and called subscriber, whereby the coded signal transmitted by one subscriber toward the other subscriber over the communication network and the signal transmitted by said other subscriber to said one subscriber will be transmitted simultaneously if an identification code for the incoming network and its time channel are inversely identical with an identification code of the outgoing network and its associated time channel.

Claim 9

A path finding system according to claim 3, wherein each input time switch, output time switch and intermediate time switch comprises n input registers, each of which receive one network line, said n input registers being associated with one buffer memory, and n output registers, each of which is connected with one network line, said n output registers being connected with a respective storage device provided in each time switch, and wherein the storage device associated with said input time switch contains the address of a time channel of the output register associated with the incoming intermediate network line corresponding to the intermediate time switch, the storage device associated with said intermediate time switch the storage of a time channel of the output register associated with the outgoing intermediate network line connected with the output time switch and the storage device of the output time switch contains the address of a time channel associated with the outgoing network line, so as to effect a communication path through each of said stages.