ATM cell switching system

Details ATM cell switching system ATM cell switching system

1998-09-10

2003-09-30

Nguyen, Chau (Department: 2663)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

Reexamination Certificate

active

06628659

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ATM (Asynchronous Transfer Mode) cell switching system, and in particular to an ATM cell switching system which is implemented using a novel ATM cell switching technique.
2. Description of the Conventional Art
FIG. 1
is a block diagram illustrating a conventional line switching system.
As shown therein, the conventional line switching system includes a plurality of sub-switching systems
10
-
1
through
10
-n for switching local calls, and a main switching system
20
for controlling the whole switching systems and switching a global call among the sub-switching systems
10
-
1
through
10
-n.
The sub-switching system
10
-
1
through
10
-n each include a local CPU (Central Processing Unit)
11
for judging whether a subscriber's call is a local call or a global call, a local switching unit
12
for switching a local call in accordance with a result of the judgement, and a multiplexor/demultiplexor
13
connected between the local switching unit
12
and a link for multiplexing/demultiplexing the global call.
In addition, the main switching system
20
includes a main CPU
21
for managing all call information and a database, a main switching unit
22
for switching the global call in accordance with a control of the main CPU
21
, and multiplexor/demultiplexors
23
-
1
through
23
-n corresponding with the sub-switching systems
10
-
1
through
10
-n.
The local switching unit
12
is formed of a time switch, and the main switching unit
22
is formed of a time switch or a space switch. In addition, the time switch has a switching capacity corresponding to the number of subscribers, and the local and main switching units
12
and
22
are connected through a link.
The call set-up procedure of the conventional line switching system will be explained with reference to FIG.
1
.
First, the local call of the sub-switching system
10
-
1
and the global call between two sub-switching systems
10
-
1
and
10
-
2
will be explained.
1. Local Call
When a call generated by a subscriber
1
is inputted into the sub-switching system
10
-
1
through a PCM (Pulse Code Modulation) highway (hereinafter called as a highway) of 2 Mbps, the local CPU
11
judges whether the call corresponds to a global call between the sub-switching systems or a local call in each sub-switching system. At this time, the call judgement is implemented by detecting a key input, etc. of the subscriber.
As a result of the judgement, if the call is a local call, the local CPU
11
controls a time switch of the local switching unit
12
and outputs a corresponding setup information to the main CPU
21
of the main switching system
20
through a control line
33
, so that the main CPU
21
controls the switching state of the sub-switching system
10
-
1
. Therefore, a communication between the subscriber
1
and the subscriber n of the sub-switching system
10
-
1
is implemented based on a switching operation of the local switching unit
12
.
2. Global Call
In addition, as a result of the judgement, the call is a global call between the sub-switching systems
10
-
1
and
10
-
2
, the local CPU
11
controls the local switching unit
12
, and an identification number of the subscriber
1
and an identification number of the subscriber n are informed to the main CPU
21
through the control line
33
. Therefore, an audio data of the subscriber
1
switched by the local switching unit
12
is inputted into the multiplexor/demultiplexor
13
through a highway
31
, and the multiplexor/demultiplexor
13
multiplexes an audio data and transmits to the main switching system
20
through the link
32
.
At this time, the main CPU
21
of the main switching system
20
receives the identification numbers of the subscribers
1
and n inputted through the control line
33
and then recognizes the sub-switching system
10
-
2
of the subscriber n from the database for thereby controlling the main switching unit
22
and outputting an identification number of the subscriber n to the sub-switching system
10
-
2
through the control line
33
. In addition, the multiplexor/demultiplexor
23
-
1
demultiplexes the audio data of the subscriber
1
inputted through the link
32
and outputs to the main switching unit
22
.
Therefore, the main switching unit
22
switches a corresponding highway
31
in accordance with a control of the main CPU
21
, and the audio data of the subscriber
1
demultiplexed by the multiplexor/demultiplexor
23
-
1
is demultiplexed again by the multiplexor/demultiplexor
23
-
2
and then is transmitted to the sub-switching system through the link
32
.
The local CPU
11
of the sub-switching system
10
-
2
controls the local switching unit
12
in accordance with an identification information of the subscriber n inputted from the main CPU
21
, so that the highway
31
connected with the link
32
and the highway
31
connected with the subscriber are switched through the multiplexor/demultiplexor
13
for thereby forming a communication line (Global call setup), and thus the audio data of the subscriber
1
demultiplexed by the multiplexor/demultiplexor
13
is transferred to the subscriber n. In addition, the local CPU
11
outputs a corresponding Setup completeness information to the main CPU
21
through the control line
33
.
Therefore, a communication between the subscriber
1
of the switching system
10
-
1
and the subscriber n of the sub-switching system
10
-
2
is implemented through the above-described cell setup procedure. In addition, a local call between the sub-switching systems
10
-
3
through
10
-n and a global call between the sub-switching systems
10
-
3
through
10
-n and the main switching system
20
are implemented in the above-described manner.
However, the conventional line switching system has the following problems.
First, in the conventional line switching system, since a switching speed between the main switching unit and the local switching unit is 2 Mbps, a multimedia service requiring a high speed switching operation is not implemented.
Second, the conventional line switching system has additional control line. In particular, in order to implement a non-blocking line switching operation, the time switches of the main switching system and the sub-switching system should have a predetermined switching capacity corresponding to the number of subscribers. Therefore, the number of switching boards is increased for thereby complicating a system structure and increasing the price.
Third, the conventional line switching system has a plurality of local CPUs for thereby enabling a distributed control structure. However, in the conventional line switching system, since the main CPU manages all call information and a database inputted from the local CPU, the distributed control structure is not fully implemented. As a result, if an error occurs in the main CPU, the whole system may go down for thereby causing inconvenience and degrading the performance of the system.
Fourth, even though the conventional line switching system is capable of processing a large capacity data using a main switching unit, a switching capacity corresponding to the whole number of lines is not implemented due to a high price and limited installation space. As a result, in the case of the global call, since a blocking switch operation is not implemented due to the limited capacity of the switching operation, a traffic may be affected for thereby decreasing a reliability of the system.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an ATM cell switching system which overcomes the aforementioned problems encountered in the conventional art.
It is another object of the present invention to provide an ATM cell switching system which is capable of implementing various multimedia services based on a high speed switching operation by adapting an ATM cell switching technique to a conventional line switching system.
It is still another object of the present invention t

Affiliated with

Also associated with

Rating

ATM cell switching system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with ATM cell switching system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ATM cell switching system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3083341