Multiplex communications – Data flow congestion prevention or control – Flow control of data transmission through a network
Reexamination Certificate
2000-03-16
2004-05-25
Pham, Chi (Department: 2667)
Multiplex communications
Data flow congestion prevention or control
Flow control of data transmission through a network
C370S335000, C370S468000, C370S471000
Reexamination Certificate
active
06741567
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention lies in the communications and signal processing fields. More specifically, the invention refers to a method and circuit configuration for making data signal connections between data terminals, particularly computers and PCs, which are connected to a circuit-switched switching center, and/or between these data terminals and a separate data network, in particular the Internet data network, which is connected to the circuit-switched switching center via one or more connecting nodes. The term “circuit-switched switching center” as used herein means a switching center which is appropriately designed to carry out circuit switching processes.
In the types of data signal connections considered above a transmission capacity of 56 kbit/s maximum has heretofore been usually available in analog circuit-switched networks. A transmission rate of 64 kbit/s maximum per connection has usually been available in digital circuit-switched networks. The protocol which is used for data signal transmission is mostly the so-called point-to-point protocol (PPP-RFC 1661).
To increase the transmission capacity, it is also possible in a digital circuit-switched network, in the case of an ISDN basic rate access with two B channels, to achieve a maximum transmission rate of 128 kbit/s, if both B channels are used for data signal transmission (see Protocol RFC 1717). There, two physical connections are available for the relevant data signal transmission.
The data network accesses which have been used heretofore are all based on the classical switched connection service, which was designed above all for transmission of telephone signals. This service is wherein a defined transmission bandwidth is guaranteed to a subscriber for the duration of the connection, and in that an existing connection is not in general ended from the network which is used. For this classical service, the technical implementation and dimensioning of the switching centers have been organized from the point of view of the highest availability and reliability. Very low network load is then the result of this over-dimensioning. The result would be the same if broadband switched data signal connections with the same availability and reliability were provided.
SUMMARY OF THE INVENTION
The object of the invention is to provide a method and a circuit for setting up data signal connections, which overcome the above-noted deficiencies and disadvantages of the prior art devices and methods of this kind, and which lead a way to providing the respective optimum transmission capacity for each of the data signal connections to be provided, without the network infrastructure having to be dimensioned differently from the given conditions for normal connections.
With the above and other objects in view there is provided, in accordance with the invention, a method of establishing data signal connections between data terminals (e.g. PCs) connected to a circuit-switched switching center, and/or between the data terminals and a separate data network (e.g. Internet) connected to the circuit-switched switching center via one or more connecting nodes, which comprises:
defining a normal transmission capacity in a circuit-switched switching center available for normal data signal connections;
defining a first traffic load threshold and a second traffic load threshold in the switching center (the second traffic threshold may be equal to the first traffic threshold);
if a traffic load in the circuit-switched switching center or a network including the switching center lies below the first traffic load threshold, providing additional transmission capacity for the data signal connections to be established in the switching center, in addition to the normal transmission capacity available in the switching center for the normal connections;
if the traffic load exceeds the first traffic load threshold, providing only a transmission capacity currently available for normal data signal connections for the data signal connections to be established;
after the traffic load undershoots the second traffic load threshold, providing additional transmission capacity in addition to the normal transmission capacity available for the normal connections for the data signal connections to be established.
In other words, the above objects are satisfied in that, if a traffic load below a first traffic load threshold V
1
is present in the circuit-switched switching center and/or in the network which includes it, additional transmission capacity is provided for the data signal connections to be made in this switching center, in addition to the transmission capacity which is available in this switching center for normal connections (for telephone, fax, narrowband or X.25 connections). If, thereby, the above-mentioned first traffic load threshold V
1
is exceeded by the relevant traffic load, only the transmission capacity which is currently available for normal connections is provided for the data signal connections which are then to be made, and in that only after the above-mentioned traffic load undershoots a second traffic load threshold V
2
, which at most corresponds to the first traffic load threshold V
1
, additional transmission capacity to that which is available for normal connections is again provided for the data signal connections which are then to be made.
The invention has the advantage that the transmission capacity which is available in the circuit-switched switching center can be made usable for data signal connections in a relatively simple way, and the usefulness which is thus created is directed at the traffic load of the relevant switching center. This means that in every case normal connections, i.e. usually telephone and fax connections or narrowband or X.25 connections, obtain the transmission capacity which they require for their signal transmission, and that only after that is additional transmission capacity provided for the data signal connections, if such capacity is still available. In this way the transmission capacity of the circuit-switched switching center is optimal, i.e. it can be exploited better than previously. It should be noted here that data applications in general are insensitive to variations or changes in the transmission capacity. It should also be noted that the method according to the invention can be used advantageously even if the first traffic load threshold V
1
is set to infinity.
In accordance with an added feature of the invention, if the traffic load in the network including the circuit-switched switching center exceeds a third traffic load threshold (above, between, or below the first and second thresholds), the additional transmission capacity previously provided for data signal connections is removed from at least some existing connections.
This action, which occurs additionally to the action which was taken when the first traffic load threshold V
1
was exceeded, has the advantage that, as the traffic load in the circuit-switched switching center increases, the normal connections to be set up there can be given priority in every case over the data signal connections with increased data transmission capacity. In the case that the third traffic load threshold V
3
is between or below the first and second traffic load thresholds V
1
, V
2
, the resulting advantage is that additional transmission capacity can be provided for new data signal connections relatively quickly, after it has been removed from existing data signal connections. If the third traffic load threshold V
3
is below the second traffic load threshold V
2
, the resulting advantage is a purely precautionary removal of additional transmission capacity which was previously provided.
In accordance with an additional feature of the invention, the additional transmission capacity for data signal connections is removed selectively in dependence on a relevant connection duration and/or of subscriber data of the data terminals participating in the connection. This means that the additional transmission capacit
Mayback Gregory L.
Pham Chi
Qureshi Afser M
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