F1: Licensed carrier(s) Ideal/non-ideal Ideal/nonideal backhaul F2: Licensed backhaul carrier(s) Small-cell Small-cell Cluster Cluster F3: Unlicensed carrier(s) Ideal backhaul Ideal backhaul (co-located) F3: Unlicensed (co-located) carrier(s) Small-cell Small-cell Cluster Cluster Scenario 3 Scenario 4 Figure 8.4 LAA deployment scenarios [12]. Operation in Unlicensed and Shared Spectrum 855 context of the carrier aggregation through ideal backhaul with a licensed cell. In scenarios where carrier aggregation is used within the small cell with carriers in both licensed and unlicensed bands, the backhaul between macrocell and small cell can be ideal or non-ideal. The deployment scenarios depicted in Fig. 8.4 can be described as follows. In scenario 1, carrier aggregation between licensed macrocell (F1) and unlicensed small cell (F3) is used, whereas in scenario 2, carrier aggregation between licensed small cell (F2) and unlicensed small cell (F3) without macrocell coverage is intended. In scenario 3, licensed macrocell and small cell (F1) with carrier aggregation between licensed small cell (F1) and unlicensed small cell (F3) is utilized, and in scenario 4, licensed macrocell (F1), licensed small cell (F2), and unlicensed small cell (F3) and further carrier aggregation between licensed small cell (F2) and unlicensed small cell (F3) is used. In the latter scenario, if there is ideal back- haul between macrocell and small cell, there can be carrier aggregation between macrocell (F1), licensed small cell (F2), and unlicensed small cell (F3). If dual connectivity is enabled, there can be dual connectivity between macrocell and small cell. In the study to support deployment in the unlicensed spectrum for the above scenarios, carrier aggregation functionalities are used as a baseline to aggregate PCell/PSCell6 on a licensed carrier and SCell on an unlicensed car- rier. When non-ideal backhaul is applied between a macrocell and a small cell cluster in scenar- ios 3 and 4, a small cell on an unlicensed carrier must be aggreg