The present invention relates to a method of exchanging data between a first station and a second station, said data being exchanged in packets. Said method comprises the steps of: receiving a packet from the second station; decoding said packet; —determining whether to transmit to the second station a resource allocation message on a signalling channel; if a said resource allocation message is transmitted, further transmitting to the second station a first indicator signal on an indicator channel; if both the decoding has not been successful and the said resource allocation message is not transmitted, transmitting to the second station a second indicator signal on the indicator channel.