A method in a cellular telecommunication network of preventing a codebook mismatch between a remote terminal and a base station, wherein the remote terminal and base station selectively operate in either a multiple-carrier mode utilizing a multiple-carrier HARQ-ACK codebook (312a, 312b) or in a single-carrier mode utilizing a single-carrier HARQ-ACK codebook (310a, 310b), the method comprising the steps of: storing in a memory in the remote terminal, a multiple-carrier HARQ-ACK codebook having a plurality of code words for various message combinations that the remote terminal sends, wherein the code word for an Acknowledgment, ACK, message and the code word for a Negative Acknowledgment, NACK, message in the multiple-carrier HARQ-ACK codebook are the same as the ACK and NACK code words in the single-carrier HARQ-ACK codebook; and when the remote terminal misses an order from the base station to switch from the multiple-carrier mode to the single-carrier mode, utilizing the multiple-carrier HARQ-ACK codebook by the remote terminal to transmit uplink ACK or NACK messages in response to single-carrier transmissions from the base station, wherein, since the code words for the ACK and NACK messages are the same in both the multiple-carrier HARQ-ACK codebook and the single-carrier HARQ-ACK codebook, a codebook mismatch at the base station is avoided, and wherein the multiple carrier HARQ-ACK codebook includes the following values: ACK/DTX = [1 1 1 1 1 1 1 1 1 1] NACK/DTX = [0 0 0 0 0 0 0 0 0 0] DTX/ACK = [1 1 1 1 1 0 0 0 0 0] DTX/NACK = [0 0 0 0 0 1 1 1 1 1] NACK/ACK = [0 0 1 1 0 0 1 1 0 0] ACK/NACK = [1 1 0 0 1 1 0 0 1 1] ACK/ACK = [1 0 1 0 1 0 1 0 1 0] NACK/NACK = [0 1 0 1 0 1 0 1 0 1], constituting an original codebook achieving a minimum Hamming distance of 4, or includes the values of a code book obtained by permuting the columns of the original codebook and/or by remapping the definition of code words of the original codebook and/or by applying a common mask to each of the code words of the original code book, while preserving a Hamming distance of 10 between code pairs DTX/ACK and DTX/NACK, between code pairs ACK/DTX and NACK/DTX, between code pairs ACK/NACK and NACK/ACK, and between code pairs ACK/ACK and NACK/NACK. storing in a memory in the remote terminal, a multiple-carrier HARQ-ACK codebook having a plurality of code words for various message combinations that the remote terminal sends, wherein the code word for an Acknowledgment, ACK, message and the code word for a Negative Acknowledgment, NACK, message in the multiple-carrier HARQ-ACK codebook are the same as the ACK and NACK code words in the single-carrier HARQ-ACK codebook; and when the remote terminal misses an order from the base station to switch from the multiple-carrier mode to the single-carrier mode, utilizing the multiple-carrier HARQ-ACK codebook by the remote terminal to transmit uplink ACK or NACK messages in response to single-carrier transmissions from the base station, wherein, since the code words for the ACK and NACK messages are the same in both the multiple-carrier HARQ-ACK codebook and the single-carrier HARQ-ACK codebook, a codebook mismatch at the base station is avoided, and wherein the multiple carrier HARQ-ACK codebook includes the following values: ACK/DTX = [1 1 1 1 1 1 1 1 1 1] NACK/DTX = [0 0 0 0 0 0 0 0 0 0] DTX/ACK = [1 1 1 1 1 0 0 0 0 0] DTX/NACK = [0 0 0 0 0 1 1 1 1 1] NACK/ACK = [0 0 1 1 0 0 1 1 0 0] ACK/NACK = [1 1 0 0 1 1 0 0 1 1] ACK/ACK = [1 0 1 0 1 0 1 0 1 0] NACK/NACK = [0 1 0 1 0 1 0 1 0 1], constituting an original codebook achieving a minimum Hamming distance of 4, or includes the values of a code book obtained by permuting the columns of the original codebook and/or by remapping the definition of code words of the original codebook and/or by applying a common mask to each of the code words of the original code book, while preserving a Hamming distance of 10 between code pairs DTX/ACK and DTX/NACK, between code pairs ACK/DTX and NACK/DTX, between code pairs ACK/NACK and NACK/ACK, and between code pairs ACK/ACK and NACK/NACK.