n sense other configured carriers with single interval LBT, only if the eNB com- pletes the LBT with random backoff on the designated carrier. In the second approach, the eNB performs LBT with random backoff on more than one unlicensed carriers and can transmit on the carriers that have completed the LBT with potential self-deferral to align transmissions over multiple carriers. An LTE eNB can access multiple carriers on which LAA SCell(s) transmis- sion(s) are performed using either Type A or Type B procedures as follows [4]: Type A multi-carrier access procedure: The eNB performs channel access on each car- rier CiEC, where C is a set of carriers on which the eNB intends to transmit and Operation in Unlicensed and Shared Spectrum 901 Ncarrier - 1 is the carrier index. The eNB transmission may include PDSCH/ PDCCH/ePDCCH on an LAA SCell(s) carrier(s), after sensing the channel to be idle during the slot durations of defer period Tdefer and after the counter N is initialized adjusted by sensing the channel for additional slot duration(s). The counter N is deter- mined for each carrier Cj and is denoted as Nci. In Type A1, the counter N is indepen- dently determined for each carrier. If the absence of another technology sharing the carrier cannot be guaranteed over a long period of time, and when the eNB stops trans- mission on any carrier CjECACi # Cj, it can continue to decrement Nci when idle slots are detected either after waiting for a duration of 4Ts or after reinitializing Nci. In Type A2, the counter Ncj is determined for the carrier CjEC, where Cj is the carrier that has the largest contention window CW value. For each carrier Ci, Nci = Ncj When the eNB stops transmission on any carrier for which Nci is determined, it reinitializes Nci for all carriers. Type B multi-carrier access procedure: A carrier CjEC is selected by the eNB by ran- domly choosing Cj from C before each transmission on multiple carriers CiECVi=0,1, Ncarrier - 1, or the eNB selects Cj less frequently, where C is a set of carriers on whi