| 摘要 |
The data flow is composed of data cells which are each transmitted via one of said transmission channels and which each comprise a control word group containing one or more control words and also an information word group containing one or more information words. A number of variables is maintained which, on arrival of a data cell at a certain location, are each altered in accordance with a alteration algorithm and are then processed in accordance with an evaluation algorithm to produce an evaluation signal. One or more of such evaluation signals are processed in accordance with a combination algorithm to produce a control signal and in which method a data cell is, or is not, transmitted, depending on the value of the control signal. . One of a plurality of quality classes is assigned to each of the data cells and for each quality class, a first variable is maintained which relates to the number of data cells having the respective quality class, which first variable is altered in accordance with a first alteration algorithm when a data cell arrives at a first location (I) and is processed in accordance with a first evaluation algorithm to produce a first evaluation signal. . Each of the virtual transmission channels is divided into one or more groups which each comprise one or more of said transmission channels and which each comprise those virtual transmission channels which make use of a particular potential congestion point in the transmission system and for each group of virtual transmission channels, a second variable is maintained which relates to the number of data cells to be transmitted via the respective group of transmission channels, which second variable is altered in accordance with a second alteration algorithm when a data cell arrives at a second location (I,II,III) and is then processed in accordance with a second evaluation algorithm to produce a second evaluation signal. . Depending on the value of the second evaluation signal and depending on the value of the respective quality class, the first alteration algorithm or the first evaluation algorithm or both are controlled in a manner such that, if the number of data cells of the respective group of channels is relatively large, the number of data cells transmitted is reduced and this will be the more so, the lower the quality class is.
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