1. A method performed by a wireless transmit/receive unit (WTRU), the method comprising:
utilizing, by the WTRU, carrier aggregation with an uplink primary component carrier in licensed spectrum and an uplink secondary component carrier in unlicensed spectrum;
receiving, by the WTRU on a physical downlink control channel (PDCCH) signal on a downlink component carrier, a grant for physical uplink shared channel (PUSCH) transmission on the uplink secondary component carrier, wherein the grant includes a resource allocation for a subframe set;
wherein the subframe set includes a first subframe resource and another subframe resource following the subframe resource; and
sensing, by the WTRU during a sensing time prior to utilization of the subframe resource, that the unlicensed spectrum is available; and
transmitting, based on the sensing, data on the subframe resource and the another subframe resource, wherein the data is transmitted on the another subframe resource without further sensing.
2. The method of claim 1, wherein at least one of timing and frequency synchronization for the uplink secondary component carrier utilizes at least one of a frame preamble, periodic beacons, or primary and secondary synchronization symbols.
3. A wireless transmit/receive unit (WTRU) comprising:
a processor, electrically coupled to a transceiver, configured to utilize carrier aggregation with an uplink primary component carrier in licensed spectrum and an uplink secondary component carrier in unlicensed spectrum;
the transceiver configured to receive, on a physical downlink control channel (PDCCH) signal on a downlink component carrier, a grant for physical uplink shared channel (PUSCH) transmission on the uplink secondary component carrier, wherein the grant includes a resource allocation for a subframe set;
wherein the subframe set includes a subframe resource and another subframe resource following the subframe resource; and
the processor configured to sense, during a sensing time prior to utilization of the subframe resource, that the unlicensed spectrum is available; and
the transceiver configured to transmit, based on the sense that the unlicensed spectrum is available, data on the subframe resource and the another subframe resource, wherein the data is transmitted on the another subframe resource without further sensing.
4. The method of claim 1, wherein the sensing time is prior to a start of a subframe with which the sensing time is associated or at a start of a subframe with which the sensing time is associated.
5. The WTRU of claim 3, wherein the sensing time is prior to a start of a subframe with which the sensing time is associated or at a start of a subframe with which the sensing time is associated.
6. The method of claim 1 further comprising transmitting on a PUSCH of the uplink primary component carrier without performing carrier sensing.
7. The WTRU of claim 3 further comprising the transceiver configured to transmit on a PUSCH of the uplink primary component carrier without performing carrier sensing.