A user equipment operable to dynamically alter HARQ mapping for carrier aggregation, having computer circuitry configured to: transmit a HARQ-ACK feedback in a PUCCH resource; characterized in that the computer circuitry is configured to: determine a secondary HARQ bundling window size for a SCell, when a primary HARQ bundling window size for a PCell is zero; and determine said PUCCH resource for transmission of the HARQ-ACK feedback using the secondary HARQ bundling window size; wherein the PUCCH resource n PUCCH 1 p ̃ for transmission of the HARQ-ACK in a subframe n for a p̃ mapped to an antenna port p for a 3GPP LTE standard Release 11 PUCCH format 1a or 1b, is represented by: for antenna port p 0 for TDD when the secondary HARQ bundling window size Ms = 1 and the primary HARQ bundling window size Mp = 0, where a HARQ bundling window size M = Ms, n CCE is a first CCE index number used for transmission of a corresponding PDCCH in subframe n - k m and the corresponding m, where k m is the smallest value in set K such that UE detects a PDCCH in subframe n - k m, N c = max 0 ⌊ N RB DL ⋅ N sc RB ⋅ c − 4 / 36 ⌋ where c is a value out of {0, 1, 2, 3} such that N c ≤ n CCE < N c +1, N RB DL is a downlink bandwidth configuration, expressed in units of N sc RB, N sc RB is a resource block size in the freqUE ncy domain, expressed as a number of subcarriers, and N PUCCH 1 is a starting PUCCH channel index for a PUCCH region in an uplink subframe and is configured by high layers for each UE; and for antenna port p 1 for TDD when the secondary HARQ bundling window size Ms = 1 and primary HARQ bundling window size Mp = 0 and a two port transmission is configured. transmit a HARQ-ACK feedback in a PUCCH resource; characterized in that the computer circuitry is configured to: determine a secondary HARQ bundling window size for a SCell, when a primary HARQ bundling window size for a PCell is zero; and determine said PUCCH resource for transmission of the HARQ-ACK feedback using the secondary HARQ bundling window size; determine a secondary HARQ bundling window size for a SCell, when a primary HARQ bundling window size for a PCell is zero; and determine said PUCCH resource for transmission of the HARQ-ACK feedback using the secondary HARQ bundling window size; wherein the PUCCH resource n PUCCH 1 p ̃ for transmission of the HARQ-ACK in a subframe n for a p̃ mapped to an antenna port p for a 3GPP LTE standard Release 11 PUCCH format 1a or 1b, is represented by: for antenna port p 0 for TDD when the secondary HARQ bundling window size Ms = 1 and the primary HARQ bundling window size Mp = 0, where a HARQ bundling window size M = Ms, n CCE is a first CCE index number used for transmission of a corresponding PDCCH in subframe n - k m and the corresponding m, where k m is the smallest value in set K such that UE detects a PDCCH in subframe n - k m, N c = max 0 ⌊ N RB DL ⋅ N sc RB ⋅ c − 4 / 36 ⌋ where c is a value out of {0, 1, 2, 3} such that N c ≤ n CCE < N c +1, N RB DL is a downlink bandwidth configuration, expressed in units of N sc RB, N sc RB is a resource block size in the freqUE ncy domain, expressed as a number of subcarriers, and N PUCCH 1 is a starting PUCCH channel index for a PUCCH region in an uplink subframe and is configured by high layers for each UE; and for antenna port p 1 for TDD when the secondary HARQ bundling window size Ms = 1 and primary HARQ bundling window size Mp = 0 and a two port transmission is configured.