Hi,
Yes, you should specify the BS antenna panel orientation to define a sector while configuring the physical layer. In a hexagonal network layout with 3 sectors, the BS antenna panel should be oriented towards each sector. The Receive Array Orientation and Transmit Array Orientation parameters can be used to specify the orientation of the antenna panel for each sector.
If the UEs are in one sector only, you do not need to specify multiple orientations of the antenna panel for all UEs. The antenna orientation is determined by the BS sector and is fixed for all UEs within that sector. However, you would need to ensure that the UE is connected to the appropriate BS in that sector.
In the 5G NR standard, the downlink and uplink channels have different characteristics and are subject to different types of impairments, such as path loss, shadowing, fading, and interference. Therefore, different channel models are used for the downlink and uplink transmissions.