However, it should be noted that some of the embodiments, when compared to current LTE operation, are further required to enable efficient operation taking into account the need for the eNB to perform LBT and obey discontinuous transmission requirements (DCT requirements).
FIG. 7 illustrates an example of Scell operation on an unlicensed carrier frequency. In FIG. 7, the eNB operates (i.e., performs the necessary steps to communicate with a UE) a Pcell 700 on a licensed carrier. The eNB also operates a Scell 702 (denoted as uScell in FIG. 7) on an unlicensed carrier. The UE receives transmissions from the eNB on both the Pcell and uScell 704 (only uScell reception is shown). Subframes indicated as “D” represent deactivated state subframes for the UE. Subframes indicated as “A” represent activated state subframes for the UE.
