A method for wireless communications, performed by a base station of a cellular network, the method comprising: transmitting, over an unlicensed spectrum to a user equipment, UE, a request to send, RTS message, wherein the access to the unlicensed spectrum requires use of a contention-based protocol; receiving, over the unlicensed spectrum from the UE, a clear to send, CTS message to reserve an uplink portion of a transmission period (505, 605) to receive a group hybrid automatic repeat request, HARQ feedback message from the UE; transmitting, over the unlicensed spectrum to the user equipment, UE, during the transmission period (505, 605), a set of data subframes, wherein the transmission over the unlicensed spectrum uses an OFDMA communication signal; and receiving, over the unlicensed spectrum from the UE, during the transmission period, the group HARQ feedback message for a plurality of data subframes including at least one of the data subframes in the set of data subframes, wherein the reception over the unlicensed spectrum uses a SC-FDMA signal, wherein the group HARQ feedback message received during the transmission period comprises HARQ feedback information for a subset of the set of data subframes, wherein the subset of the set of data subframes excludes one or more data subframes from the transmitted set of data subframes, the method further comprising: receiving, over the unlicensed spectrum from the UE, a next group HARQ feedback message comprising HARQ feedback information for a remaining subset of the set of data subframes, the remaining subset of the set of data subframes including those one or more data subframes for which HARQ feedback information is not included in the HARQ feedback message received during the transmission period, the next group HARQ feedback message being received during a next transmission period. transmitting, over an unlicensed spectrum to a user equipment, UE, a request to send, RTS message, wherein the access to the unlicensed spectrum requires use of a contention-based protocol; receiving, over the unlicensed spectrum from the UE, a clear to send, CTS message to reserve an uplink portion of a transmission period (505, 605) to receive a group hybrid automatic repeat request, HARQ feedback message from the UE; transmitting, over the unlicensed spectrum to the user equipment, UE, during the transmission period (505, 605), a set of data subframes, wherein the transmission over the unlicensed spectrum uses an OFDMA communication signal; and receiving, over the unlicensed spectrum from the UE, during the transmission period, the group HARQ feedback message for a plurality of data subframes including at least one of the data subframes in the set of data subframes, wherein the reception over the unlicensed spectrum uses a SC-FDMA signal, wherein the group HARQ feedback message received during the transmission period comprises HARQ feedback information for a subset of the set of data subframes, wherein the subset of the set of data subframes excludes one or more data subframes from the transmitted set of data subframes, the method further comprising: receiving, over the unlicensed spectrum from the UE, a next group HARQ feedback message comprising HARQ feedback information for a remaining subset of the set of data subframes, the remaining subset of the set of data subframes including those one or more data subframes for which HARQ feedback information is not included in the HARQ feedback message received during the transmission period, the next group HARQ feedback message being received during a next transmission period.