A method for controlling the retransmission of data units in a wireless telecommunication system, comprising the steps of: receiving a plurality of data units from a transmitter at a receiver ; in response to the receipt of each of said plurality of data units, attempting to decode said data unit at said receiver , and: if said data unit is successfully decoded, transmitting positive feedback from said receiver to said transmitter , said positive feedback indicating to said transmitter that said data unit was successfully decoded by said receiver ; or, if said data unit is not successfully decoded, transmitting negative feedback from said receiver to said transmitter , said negative feedback indicating to said transmitter that said data unit was not successfully decoded by said receiver ; selecting a first radio channel for transmitting said positive or negative feedback, wherein said first radio channel differs from a second radio channel at least in terms of channel characteristics; and transmitting a Status Message on said second radio channel from said receiver to said transmitter , said status message comprising explicit information identifying one of said plurality of data units; the Status Message is transmitted on the second radio channel using a transmission method that is more reliable than a transmission method used on the first radio channel to ensure that the Status Message is correctly interpreted at the transmitter, and the method characterised in that said Status Message comprises a Cyclic Redundancy Check, CRC, value whereby said transmitter can verify that said Status Message is correctly received. receiving a plurality of data units from a transmitter at a receiver ; in response to the receipt of each of said plurality of data units, attempting to decode said data unit at said receiver , and: if said data unit is successfully decoded, transmitting positive feedback from said receiver to said transmitter , said positive feedback indicating to said transmitter that said data unit was successfully decoded by said receiver ; or, if said data unit is not successfully decoded, transmitting negative feedback from said receiver to said transmitter , said negative feedback indicating to said transmitter that said data unit was not successfully decoded by said receiver ; if said data unit is successfully decoded, transmitting positive feedback from said receiver to said transmitter , said positive feedback indicating to said transmitter that said data unit was successfully decoded by said receiver ; or, if said data unit is not successfully decoded, transmitting negative feedback from said receiver to said transmitter , said negative feedback indicating to said transmitter that said data unit was not successfully decoded by said receiver ; selecting a first radio channel for transmitting said positive or negative feedback, wherein said first radio channel differs from a second radio channel at least in terms of channel characteristics; and transmitting a Status Message on said second radio channel from said receiver to said transmitter , said status message comprising explicit information identifying one of said plurality of data units; the Status Message is transmitted on the second radio channel using a transmission method that is more reliable than a transmission method used on the first radio channel to ensure that the Status Message is correctly interpreted at the transmitter, and the method characterised in that said Status Message comprises a Cyclic Redundancy Check, CRC, value whereby said transmitter can verify that said Status Message is correctly received. <EOS>