The present invention concerns a method and an arrangement to increase the data transmission flow rate in a communication system, preferably using Asynchronous Transfer Mode. 
In a communication system operating under the Asynchronous Transfer Mode (ATM), data is transmitted by packets or cells of fixed size and structure.  Such fixed cell size is of 53 octets (bytes) wherein 48 octets are allocated to code the data to be transmitted, in a part of the cell called payload (PL), and 5 octets are allocated to form a header (H) of the cell. 
A cell header carries the information necessary for the communication system to determine to which connection, and finally, to which address, each cell should be delivered.  In such a system, as in every communication system, it is desirable to increase the data flow rate by using the same communication resources.  Up to now, the usual way to achieve this goal is to use complex compression algorithms. 
The invention provides an increase of data flow rate without the necessity of using complex compression algorithms.