The disclosure provides an acknowledgement of data received by a communication device, the data being received by data packets, with each data packet comprising a plurality of data blocks. The communication device determines, for a data packet, a number of data blocks whose data can be processed correctly. The communication device further sends an acknowledgement for at least one data block in the data packet if the number of data blocks whose data can be processed correctly is between a first and a second threshold. The communication device also sends, for the data packet, a piece of information at packet level representing the number of data blocks whose data can be processed correctly if the number of data blocks whose data can be processed correctly is lower than the first threshold or higher than the second threshold.