Multiplex communications – Fault recovery – Bypass an inoperative switch or inoperative element of a...
Reexamination Certificate
1998-08-21
2001-05-29
Hsu, Alphus H. (Department: 2662)
Multiplex communications
Fault recovery
Bypass an inoperative switch or inoperative element of a...
C370S370000, C370S373000
Reexamination Certificate
active
06240063
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a time-division switch control system of a digital switching system, and more specifically, to a switch control system for a T-S-T (time switch-space switch-time switch) 3-staged structure switching network controlled by a plurality of control processors (a multi-processor type digital switching system.)
2. Description of the Related Art
In the digital switching system, data to be switched is flowed into the switching network in the form of series of time slots through an incoming highway, and necessary switching operation for each time slot is performed and output from the switching network through an outgoing highway.
FIG. 5
is a block diagram illustrating the principle of time slot switching by a T-S-T 3-staged structure switching network which can provides a large capacity switching network. The incoming highway from a line circuit
310
-
31
N is coupled to a first stage time switch
110
-
11
N, and junctor highways HW
10
-HW
1
N from each of first stage time switches
110
-
11
N are coupled to a second stage space switch
200
. Each of junctor highways HW
20
-HW
2
N from the second stage space switch
200
are coupled to each of third stage time switches
120
-
12
N respectively. The outgoing highway from a third stage time switch
120
-
12
N is coupled to a line circuit
320
-
32
N. Each line circuit is coupled to a subscriber terminal
1
-N, or
10
-
1
N.
Under these configurations, the principle of switching is like this; the time switch exchanges data in a certain time slot number to a different time slot number, and the space switch exchanges data in a certain time slot number of a certain junctor highway number to a same time slot number of a different junctor highway number.
For more detail, operation performed by the T-S-T 3-staged structure switching network will be explained with reference to FIG.
5
.
It is assumed that a communication path is to be established between a subscriber terminal
1
connected to the line circuit
310
and a subscriber terminal
1
L connected to the line circuit
32
L.
In the digital switching system, a time slot number of the originating subscriber (subscriber terminal
1
) on the incoming highway is known as the originating subscriber accommodated position which has informed by a peripheral unit of the digital switching system at the time of call origination request by the subscriber terminal
1
, and the time slot number on the incoming highway is assumed as No. k. And also, a time slot number of the terminating subscriber (subscriber terminal
1
L) on the outgoing highway and the junctor highway number corresponding to the outgoing highway are known as the result of analysis of the dialled number by the subscriber terminal
1
, and the time slot number on the outgoing highway is assumed as No.
1
and the corresponding junctor highway number is assumed as No. HW
2
L. Therefore, switching is to be performed by exchanging data in the time slot number k on the incoming highway corresponding to the junctor highway HW
10
to the time slot number
2
on the outgoing highway corresponding to junctor highway HW
2
L.
The digital switching system searches a time slot number which is idle state on both junctor highways HW
10
and HW
2
L, and it is assumed that time slot number
2
is available for both junctor highways and the time slot number
2
is reserved for communication path establishment.
After that, the digital switching system instructs the first stage time switch
110
to exchange data in the time slot number k on the incoming highway from the subscriber terminal
1
to the time slot number
2
on the junctor highway HW
10
, instructs the second stage space switch
200
to exchange data in the time slot number
2
from the junctor highway HW
10
to the junctor highway HW
2
L, and also instructs the third stage time switch
12
L to exchange data in the time slot number
2
on the junctor highway HW
2
L to the time slot number
1
on the outgoing highway to the subscriber terminal
1
L.
The T-S-T 3-staged structure switching network of a conventional multi-processor type digital switching system employs such a configuration, as shown in
FIG. 6
, that the first stage time switch
110
and the third stage time switch
120
are equipped in a one time switch module
100
together with a control processor
130
for controlling those time switches, and a plurality of time switch modules
100
-
10
N are provided depending on number of subscriber terminals
1
-N,
10
-
1
N and junction circuits (not shown) to/from other switching systems which are accommodated in this digital switching system, and also a plurality of second stage space switches
210
-
21
N are equipped in a space switch module
200
together with a control processor
230
for controlling those space switches. That is, a plurality of control processors
130
-
13
N,
230
are installed in a distributed manner in each time switch module
100
-
10
N or a space switch module
200
respectively.
Each first stage time switch
110
-
11
N is connected to all of second stage space switches
210
-
21
N by a respective junctor highway HW
10
-HW
1
N, and each second space switch
210
-
21
N is connected each third stage time switch
120
-
12
N respectively by a junctor highway HW
20
-HW
2
N. Control processors
130
-
13
N,
230
are connected each other by a processor bus
400
.
A communication path establishment from a subscriber terminal
1
accommodated in the line circuit
310
connected to the time switch module
100
to a subscriber terminal
1
N accommodated in the line circuit
32
N connected to the time switch module
10
N will now be considered.
In this communication path establishment, such a connection is required from the first stage time switch
110
via the junctor highway HW
10
, the second stage space switch
21
N, and the junctor highway HW
2
N to the third stage time switch
12
N. First, the control processor
130
makes an inquiry about an idle time slot number available on both junctor highways HW
10
and HW
2
N to the control processor
230
in the space switch module
200
. The control processor
230
searches an idle time slot available on both junctor highways HW
10
and HW
1
N, and then selects one of available time slot number. The control processor
230
, which has found an idle time slot, reserves this idle time slot and notifies this information to the control processor
130
. The control processor
130
instructs the time switch
110
to perform a time slot exchange operation from an incoming time slot to the time slot which has been informed by the control processor
230
, also, the control processor
130
instructs the control processor
230
and the control processor
13
N to perform path establishment in the space switch
21
N and in the time switch
12
N respectively. In the space switch
21
N, the time slot which has been reserved on the junctor highway HW
10
is switched to the same time slot on the junctor highway HW
2
N, and also, in the time switch
12
N, a time slot exchange operation from the time slot on the junctor highway HW
2
N, informed by the control processor
130
, to the time slot on the outgoing highway corresponding to the subscriber terminal
1
N is performed.
As a result, the switching operation of the communication path from the subscriber terminal
1
to the subscriber terminal
1
N has been completed.
In Japanese Patent Application Laid-Open No. sho. 63-50293, similar T-S-T structure switching network model of combining time switches and a space switch is described. In this publication, a configuration of a distributed switching network system which is constituted by coupling a plurality of switch modules, each switch module includes time switches and space switch, is proposed for improving independent characteristics of the control processor in respective switch modules, and it is proposed that highway from other switch module is connected to the space switch via the additional time switch. That is, the proposed configuration, which is a
Ho Duc
Hsu Alphus H.
McGuireWoods LLP
NEC Corporation
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