A method in a user equipment (110, 112), the method comprising: receiving, in a subframe, a grant for transmitting physical uplink shared channel on a serving cell operating on an unlicensed carrier; determining a set of subframes for possible transmission of the physical uplink shared channel; performing listen before talk, LBT, on the unlicensed carrier to determine an earliest unoccupied subframe in the set of subframes; and transmitting physical uplink shared channel transmissions in multiple subframes for which LBT is successful within the set of subframes on the unlicensed carrier, starting with the earliest unoccupied subframe, in response to receiving the grant; wherein the grant comprises a first grant for transmitting physical uplink shared channel including a hybrid automatic repeat request identifier, wherein the method further comprises: determining a new hybrid automatic repeat request identifier for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes made in response to the grant, where the new hybrid automatic repeat request identifier is determined based on the received hybrid automatic repeat request identifier and a subframe index of each subframe of the multiple subframes; receiving, after receiving the first grant, a second grant requesting a retransmission, where the second grant includes at least one new hybrid automatic repeat request identifier that was previously determined by the user equipment (110, 112); and transmitting physical uplink shared channel in response to the second grant to retransmit the data that is associated with the same new hybrid automatic repeat request identifier. receiving, in a subframe, a grant for transmitting physical uplink shared channel on a serving cell operating on an unlicensed carrier; determining a set of subframes for possible transmission of the physical uplink shared channel; performing listen before talk, LBT, on the unlicensed carrier to determine an earliest unoccupied subframe in the set of subframes; and transmitting physical uplink shared channel transmissions in multiple subframes for which LBT is successful within the set of subframes on the unlicensed carrier, starting with the earliest unoccupied subframe, in response to receiving the grant; wherein the grant comprises a first grant for transmitting physical uplink shared channel including a hybrid automatic repeat request identifier, wherein the method further comprises: determining a new hybrid automatic repeat request identifier for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes made in response to the grant, where the new hybrid automatic repeat request identifier is determined based on the received hybrid automatic repeat request identifier and a subframe index of each subframe of the multiple subframes; receiving, after receiving the first grant, a second grant requesting a retransmission, where the second grant includes at least one new hybrid automatic repeat request identifier that was previously determined by the user equipment (110, 112); and transmitting physical uplink shared channel in response to the second grant to retransmit the data that is associated with the same new hybrid automatic repeat request identifier. determining a new hybrid automatic repeat request identifier for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes made in response to the grant, where the new hybrid automatic repeat request identifier is determined based on the received hybrid automatic repeat request identifier and a subframe index of each subframe of the multiple subframes; receiving, after receiving the first grant, a second grant requesting a retransmission, where the second grant includes at least one new hybrid automatic repeat request identifier that was previously determined by the user equipment (110, 112); and transmitting physical uplink shared channel in response to the second grant to retransmit the data that is associated with the same new hybrid automatic repeat request identifier.