Congestion control method and system in an exchange

Details Congestion control method and system in an exchange Congestion control method and system in an exchange

1998-10-13

2001-08-14

Kuntz, Curtis (Department: 2643)

Telephonic communications

With usage measurement

C379S133000, C379S196000, C379S230000, C455S453000

Reexamination Certificate

active

06275572

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to congestion control method and system in an exchange.
2. Description of the Related Art
FIG. 15
shows a normal status in case that is accommodated in a general exchange
1
. As shown in
FIG. 15
, in this case, the calling subscriber can talk with a desired subscriber if a trunk
3
on an output side of the exchange
1
is idle and the desired subscriber is not talking.
FIG. 16
shows a busy or congested status in the above-described case. If the trunk
3
is not idle because of call congestion, or a desired subscriber's phone is busy, as shown in
FIG. 16
, a congestion tone (CT) or busy tone (BT) is transmitted to the calling subscriber, and then, the calling subscriber can hear the tone.
In here, a flow chart for connecting a BT/CT is shown in FIG.
17
. As shown in
FIG. 17
, if a calling is incoming (STEP S
2
) when a trunk
3
is in an idle status (STEP S
1
), an exchange
1
receives a telephone number of the calling subscriber (STEP S
3
). Then, the exchange
1
judges whether or not there is an idle trunk
3
on its output side (STEP S
4
).
If there is an idle trunk
3
, channel connection can be performed. If not, the exchange
1
connects with a BT/CT transmitter
4
to send a congestion tone (CT) or busy tone (BT) to the calling subscriber.
In here, call congestion may be caused by that many subscribers try to send callings at the same time, and as shown in
FIG. 18
, repeat hanging and calling without waiting after they hear a congestion tone or busy tone (BT). Therefore, this situation makes the call congestion status be aggravated more, thus it becomes hard to connect with a desired subscriber.
It is a matter of frequent occurrence to experience a similar situation such that it becomes hard to connect to a specific line because many subscribers concurrently call one line up, especially in an emergency. The reason is because most of the subscribers repeat the above-described situation of FIG.
18
.
In such a situation, a congestion can be relieved by controlling the incoming to enable connection in order to solve the above-described problem till now. In the conventional method, a subscriber can not be connected to a specific channel, temporarily, and the specific channel is compulsorily made to an idle status to prevent from congestion.
However, in this method, congestion occurs again right away, in other words, a vicious cycle is repeated. Thereby, a quality of call connection service becomes lower. This means the conventional method is not preferable.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a congestion control method and system so as to maintain a quality of a call connection service, similarly in a normal status, even on encountering congestion and to flexibly relieve the congestion.
To achieve the aforementioned object, a first basic structure of the present invention includes the steps of generating a call pattern as time series data of calls from a subscriber, performing Fast Fourier transformation on the time series data of the calls to detect short periodic component of a frequency, comparing a number of the detected short periodical component with a prescribed threshold, and delaying a timing of sending a congestion tone (CT) or busy tone (BT) when the value of the short periodical component exceeds the prescribed threshold.
Further, to achieve the aforementioned object, a second basic structure of the present invention includes the steps of counting calls from subscribers in each prescribed channels, obtaining an amount of calls in certain interval from the counted number of the calls, and delaying a timing of sending a congestion tone (CT) or busy tone (BT) when the amount of calls in certain interval exceeds a predetermined threshold.
In one detailed mode on the above-described structure, subscribers are grouped according to a prescribed standard for changing and controlling so as to delay a timing of sending a congestion tone (CT) or busy tone (BT) in every grouped group.
Alternatively, subscribers are grouped according to a prescribed standard for changing and controlling so as to delay a timing of sending a congestion tone (CT) or busy tone (BT) to a subscriber joined in a specific one of the grouped groups.
Further, as a detailed method for grouping, the grouping is performed by transforming subscriber numbers into a hash function.
Alternatively, the grouping is performed according to a terminal number of the subscriber number. Additionally as the other method, the grouping is performed according to an attribute of the subscriber number.
Furthermore, an exchange system employing a common channel No. 7 signaling method includes a common channel signaling equipment including buffers, a network layer for detecting a congestion status when the levels of the buffers exceed a prescribed threshold and an application layer for delaying a timing of sending a congestion tone (CT) or busy tone (BT) when detecting a congestion status in the network layer.
As described above, the congestion can be prevented from repeating to send callings in a short time by controlling so as to delay a timing of sending a congestion tone (CT) or busy tone (BT) in a congestion status. Thereby, the congestion status can be relieved.
Further, other objects of the present invention become clear by the description for explaining embodiments according to the attached drawings.


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patent: 5291552 (1994-03-01), Kerrigan et al.
patent: 5400329 (1995-03-01), Tokura et al.
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patent: 5778057 (1998-07-01), Atai
patent: 5822401 (1998-10-01), Cave et al.
patent: 5933481 (1999-08-01), MacDonald
patent: 6011838 (2000-01-01), Cox
patent: 59-4258 (1984-01-01), None
patent: 59-25459 (1984-02-01), None
patent: 58-40957 (1998-03-01), None

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