Lte/lte-a uplink carrier aggregation using unlicensed spectrum

The methods, systems, and apparatus are described for wireless communication. In one method, an uplink grant can be received via the licensed spectrum. Clear Channel Assessment (CCA) that may be performed by unauthorized response to the uplink grant in order to determine the availability of the spectrum. CCA may be performed prior to transmission associated with the uplink grant. In another method, the scheduling information may be received via the licensed spectrum. The uplink grant may be transmitted on a grant spectrum. The uplink grant may be at least in part upon the scheduling information. The uplink grant may be of the unlicensed prior to transmission associated with the uplink grant to trigger the CCA to determine the availability of the spectrum.