WO1997008875A1

WO1997008875A1 - Method of reducing rejects of service requests made by a terminal to an atm network

Info

Publication number: WO1997008875A1
Application number: PCT/DE1996/001549
Authority: WO
Inventors: Christoph Thomas; Thomas Runkler
Original assignee: Siemens Aktiengesellschaft
Priority date: 1995-08-24
Filing date: 1996-08-21
Publication date: 1997-03-06

Abstract

The invention reduces the probability of the refusal of a service request [DA(pi)] made by a terminal (EG) to an ATM network (AN), and/or reduces the transmission costs, by modifying the ATM transmission parameters (pi). The modification of the transmission parameters (pi) can be done using prior knowledge in the form of old service requests stored in a memory.

Description

description

Method for reducing the rejection of service requests from a terminal to an ATM network

In future, broadband communication networks based on ATM technology (Asynchronous Transfer Mode) will increasingly be used to transmit data and messages.

In ATM technology, a participant, e.g. B. a natural person, or a computer application, e.g. B. a program, the ATM network via the respective terminal, this can, for. B. a telephone, a fax machine, a personal computer, or the like, its transmission request with, together with the desired usage parameters for the respective transmission.

The usage parameters are, for example, the average data rate at which the requested transmission is to take place, the peak data rate, the burst length, or also a tolerable loss probability and similar parameters.

The actually available usage parameters have not yet been standardized, since the entire ATM technology has not yet been standardized either. For this reason, only usage parameters are spoken of in general, since it is not yet possible to determine special properties based on actual usage parameters.

For each transmission request that the ATM network receives, the ATM access control decides whether the transmission can be offered or not. The decision depends on the usage parameters that the transmission request contains and on the current network load. If a transmission request cannot be made possible due to excessive network load, the transmission request is rejected by the ATM access control. This manifests itself for the terminal in the form of a "busy line".

In the following, each transmission request of a terminal to an ATM network is referred to as a service request of a terminal to an ATM network.

The usage parameters of a transmission request sought or requested by a terminal are referred to below as ATM transmission parameters.

The problem underlying the invention is to reduce the rejection of service requests by an ATM network.

The problem is solved by the method according to claim 1.

By varying the ATM transmission parameters for a service request, the probability of the service network rejecting the service request can be reduced if the ATM transmission parameters are changed in such a way that the probability of rejecting the service request is reduced. So is z. If, for example, the average data rate of the transmission is regarded as an ATM transmission parameter, this is reduced in the service request so that not so much transmission capacity is "requested" within a short time interval, the probability of acceptance of the transmission request increases.

Since the ATM technology is based on the transmission of data packets, in this case, if a lower average data rate is requested, the service request could be made more likely to have sufficient transmission capacity available than in the case of a service request with a higher average data rate than ATM transmission parameters.

This also enables a more even utilization of the ATM network.

The further developments of the method according to claims 2 to 4 allow taking into account "knowledge" of previous service requests with their ATM transmission parameters when varying the current ΑTM transmission parameters of the current service request. This creates a more efficient possibility of changing the ATM Transmission parameters, since prior knowledge of previous service requirements is taken into account.

Further developments of the invention result from the dependent claims.

A preferred embodiment of the invention is shown in the drawings and is described in more detail below.

Show it

FIG. 1 shows a sketch showing the sequence of service requests with assigned ATM transmission parameters to an ATM network, some service requests being rejected by the ATM network and the last service request by the ATM network is accepted, whereupon the data of the respective service request are transmitted;

FIG. 2 shows a flowchart that describes the interaction of the terminal with the ATM network for “negotiating the service request” in detail;

FIG. 3 shows a sketch in which a parameter space of two ATM transmission parameters is shown, one showing accepted service requests and the other rejecting service requests, which are used as prior knowledge when varying the ATM transmission parameters.

The method according to the invention is further explained on the basis of FIGS. 1 to 3.

FIG. 1 shows a rough schedule of the communication between a terminal EG and an ATM network AN.

The communication between the terminal EG and the ATM network AN takes place in such a way that the terminal EG sends a service request DA (pi) to the ATM network AN.

The service request DA (pi) specifies for which application, ie. H. for which application a transmission request is directed to the ATM network AN. The service request DA (pi) is assigned ATM transmission parameters pi, which contain the usage parameters described in the previous section which are desired for the service request.

Since the exact ATM transmission parameters pi have not yet been determined by standardization, only ATM transmission parameters pi can be spoken of in general in this preferred exemplary embodiment, and the principle of the exemplary embodiment is illustrated with the aid of some exemplary exemplary ATM transmission parameters pi.

However, the specific examples used to illustrate the ATM transmission parameters pi do not limit the general validity of the method according to the invention, as is immediately apparent to any person skilled in the art.

In general, an index i uniquely designates each ATM transmission parameter pi, the index i being any number corresponding to the number of ATM transmission parameters considered. The ATM network AN responds to each service request DA (pi) of the terminal EG with a response, in which the ATM network AN informs the terminal EG whether the service request DA (pi) can be fulfilled by the ATM network AN.

If the ATM network AN notifies the terminal EG in the response or that the service request DA (pi) cannot be accepted, the terminal EG sends a further service request DA (pi) to the if the service is still required ATM network ON.

The service request DA (pi) can be the same service request DA (pi) that was previously rejected by the ATM network AN.

This can e.g. B. make sense if, in one of the ways described below, for example, “knowledge” about periods in which an inexpensive transmission is possible is stored. In this case, it is also provided that the same service request DA (pi ) is sent to the ATM network AN again at a later point in time, preferably at a “cost-effective” point in time. This variant of the method achieves considerable cost savings in transmission costs without the ATM transmission parameters pi having to be varied.

As described further below, the terminal EG can also vary the ATM transmission parameters pi, so that the probability of rejection by the ATM network AN is reduced.

For each service request DA (pi), the ATM network AN uses the current network load to check whether the service request DA (pi) can be met pi with the requested ATM transmission parameters. If the service request DA (pi) can be fulfilled, the ATM network AN notifies the terminal EG of this with a positive response. After the terminal EG has received or received a response in which the service request DA (pi) was accepted, the terminal EG sends the data to the ATM network AN which have been “announced” by the service request DA (pi).

It is even possible here, as in (G. Sigmund, ATM - The Technology of Broadband ISDN, Decker Verlag, Heidelberg, ISBN 3-7685-3994-6, p.220-222, 1994; and T. Ndousse, Fuzzy Neural Control of Voice Cells in ATM-Networks, IEEE Journal on Selected Areas in Communications, Vol. 12, No. 9, pp. 1488-1494, December 1994, 1994) that the actual ATM transmission parameters that used for the transmission of the data represent a higher load for the network than the ATM transmission parameters pi, which were approved or approved by the ATM network AN through the response.

This need not automatically lead to a rejection of the transmission of the data by the ATM network AN, but can be tolerated if the current network load allows it.

FIG. 2 shows a flow chart that describes the method in more detail.

As described above, the service request DA (pi) is sent 1 from the terminal EG to the ATM network AN.

A check is now made in the ATM network AN as to whether the service requirement DA (pi) is currently being met on the basis of the current network load and can therefore be accepted by the ATM network AN 2.

If the ATM network AN comes to the conclusion that the service request DA (pi) can be accepted with the ATM transmission parameters pi, the ATM network AN sends a response or the content ok, with which it Terminal EG announces that the service request DA (pi) is accepted with the ATM transmission parameters pi 4.

If, however, the ATM network AN comes to the conclusion based on the current network utilization that the service request DA (pi) cannot be met, the ATM network AN rejects the service request DA (pi) by answering or by means of the negative message no notifies the terminal EG that the service request DA (pi) is rejected 5.

The response resp, is formed in the ATM network AN, coded, and sent 6 to the terminal EG.

The terminal EG receives or decodes the coded response, and evaluates it by checking whether the content of the response or the positive message is ok or the negative message is no 7.

If the answer or the positive message is ok, the requested service is carried out by the terminal EG sending the data to the ATM network AN which it had previously “announced” by the service request DA (pi) 8.

If the answer is respectively negative, it shows the negative

Message no, a new service request DA (pi) is sent if there is still a need to perform the service.

Here, the terminal EG changes the ATM transmission parameters pi in such a way that the probability of rejecting the new service request DA (pi) is reduced 9.

However, the ATM transmission parameters pi do not necessarily have to be changed. It is also envisaged to change the ATM transmission parameters pi already at the first service request DA (pi) in such a way that the probability of rejecting the service request DA (pi) is low.

However, this is subject to the respective framework conditions that are imposed on the requested service.

The following example is given to illustrate this situation:

If a user of a fax machine knows from the outset that the transmission time for the transmission of a fax is not particularly important in one case, the user can, for example, B. request a lower average data rate for fax transmission than is usually the case. The lower requested average data rate reduces the likelihood that the transmission of the fax with a lower average data rate will be rejected. It also reduces the cost of fax transmission.

However, each application is subject to certain framework conditions. Possible framework conditions for the example described above are the maximum duration of transmissions, since new fax transmissions may be necessary after a certain time.

In the variant described above, that cost aspects also play a role in taking "knowledge" into account, this can mean, for example, that if the fax to be transmitted is not urgent, the terminal device stores the data to be transmitted and only then transmits to the ATM network AN at an inexpensive point in time, ie at a point in time at which data transmission is cheaper. Provision is also made, for example, to buffer the data and only ever send parts of the data to be transmitted to the ATM network AN, thereby reducing costs by avoiding burstiness transmission "peaks" and on the other hand the likelihood of rejection of the service request DA (pi) is reduced, since the individual “partial” service requests for the ATM network AN are more likely to be met than the original “large” service request.

The change in the ATM transmission parameters pi should take place in such a way that with further service requests DA (pi) the change targeted improvements in the probability of the service request DA (pi) also being “approved” by the ATM network AN, cause.

This can be accomplished in several ways.

All options that will be described in the following have in common that knowledge about previous service requests and their ATM transmission parameters pi are stored by the terminal EG and the change in the ATM transmission parameters pi for the current service request DA (pi) is carried out on the basis of the stored data becomes.

One way of storing knowledge about previous service requests is to save the last time service request with the requested ATM transmission parameter pi, which was either accepted by the ATM network AN or rejected, in order to provide an indication of the Obtaining change in the ATM transmission parameters pi.

Another possibility is to set up a separate table for each different service, in which the last service request with the requested ATM transmission parameter pi is included for at least each service the information as to whether the respective service request was accepted or rejected.

A third possibility is to set up a history space for the ATM transmission parameters pi taken into account, in which the rejected as well as the accepted service requests from the past are plotted.

The history space can be set up together with the time and location information of the past service requests, for example the time of day, the day of the week on which the respective service request DA (pi) was made to the ATM network AN, or the location of the destination address to gain further knowledge of the state of the ATM network.

An example of such a history space is shown in FIG. 3 for the case of two ATM transmission parameters p1 and p2.

Accepted service requests are OK in Figure 3 with the

Symbol marked x, rejections ZW with the symbol o.

In this case, one possibility of reducing the probability of the number of rejections of service requests DA (pi) is to find a limit history GH which clearly separates all rejected service requests from the accepted service requests.

In the vicinity of the limit history GH, the combination of the reduction in the probability of rejection ZW of the service request DA (pi) and the maximum permissible ATM transmission parameters pi is then optimal.

A simplification of the method described above is possible by checking for each rejection ZW whether any ATM transmission parameter pi is smaller than the values of the stored ATM transmission parameters of the previous rejections ZW. In the case of rejections, only the service requests are saved in which at least one ATM transmission parameter pi represents a minimum.

For accepted service requests OK, only the values are correspondingly stored in which at least one ATM transmission parameter pi has a maximum compared to accepted service scan requests OK that have already been stored.

The "learning" described above can also be extended to the situations in which actual services are used, in which the service request DA (pi) has been accepted by the ATM network AN, but the actual service with ATM transmission parameters pi was carried out, which required an increased transmission capacity than was approved by the ATM network AN.

In this case, the “tolerance of the ATM network AN can also be“ learned ”. In addition to reducing the probability of rejecting the service request DA (pi), the procedure described in the foregoing also reduces the costs for each Transmission causes.

Claims

claims

1. A method for reducing rejections of service requests (DA (pi)) of a terminal (EG) to an ATM network (AN), in which at least one ATM transmission parameter (pi; i = 1) is sent by the terminal (EG) ..n) is varied in such a way that the probability that a service request (DA (pi)) is rejected is reduced.

2. The method according to claim 1,

- With the parameter at least one previous service request (DA (PI)) are stored in the terminal (EG), and

- In which the at least one ATM transmission parameter (pi) is changed by the terminal (EG) in the service request (DA (pi)) taking into account the stored parameters of the at least one service request (DA (pi)) so that the The likelihood that the service request (DA (pi)) will be rejected is reduced.

3. The method according to claim 2, in which the ATM transmission parameters (pi) of at least one previous service request (DA (pi)) are stored in a table.

4. The method according to claim 2, in which only ATM transmission parameters (pi) of previous accepted service requests (DA (pi)) are stored which have a maximum value in at least one value of an ATM transmission parameter (pi) and / or only ATM transmission parameters (pi) of previous rejected service requests (DA (pi)) are stored which have a maximum value in at least one value of an ATM transmission parameter (pi).

5. The method according to any one of claims 1 to 4, in which additionally information about previous accepted Service requests (DA (pi)) that were accepted, although they were originally approved with a set of ATM transmission parameters (pi) that required a lower transmission capacity than the previous service requests (DA (pi)) that were actually carried out, are stored become.

6. The method according to any one of claims 2 to 5, wherein the service request (DA (pi)) is only sent to the ATM network (AN) at a time at which the transmission is cheaper than when the service request (DA (pi)).

7. The method according to any one of claims 2 to 6, in which parts of the service request (DA (pi)) are buffered in the terminal (EG).

8. The method according to any one of claims 2 to 7,

- in which the service request (DA (pi)) is divided into smaller parts, and

- In which the parts of the service request (DA (pi)) are sent one after the other as separate service requests (DA (pi)).