A method, an apparatus, and a computer program product for wireless communication are provided. A base station transmits a provisional grant uplink assignment to a set of UEs. When a UE receives the provisional grant uplink assignment, the UE performs a clear channel assessment (CCA) operation on a secondary component carrier (SCC) based on the provisional grant UL assignment, the SCC being a contention-based carrier. Then, the UE transmits a schedule request (SR) on the SCC when the CCA operation succeeds. The base station transmits grant confirmation(s) on the SCC in response to the detected SR(s). Once the UE receives a grant confirmation on the SCC in response to the SR, the UE transmits data on the SCC.