What is CTF (Channel transfer function)?

The 5G BTS gNB can be separated into two entities that are Centralized Unit and Distributed Unit. CU offers assistance for the higher layers of the protocol stack, for example, SDAP, PDCP while DU offers assistance for the lower layers of the protocol. SDAP layer will not be available in the CU is associated with a 4G Core network, 5G core network is used to support SDAP. There is a solitary CU for each gNB, but one CU manages multiple DUs.