Mantra: A 5G gNB can be decomposed into two logical components, gNB-CU and gNB-DU.
Brief Explanation. In 5G, the next-generation Node B (gNB) and the User Equipment (UE) communicate with each other using the New Radio (NR) air interface protocol stack. The gNB can be decomposed into gNB-Central Unit (gNB-CU) and gNB-Distributed Unit (gNB-DU). The gNB-CU implements the upper layers of the NR radio protocol stack such as RRC, SDAP, and PDCP, while the gNB-DU implements the lower layers such as RLC, MAC, and PHY. One gNB-CU could control numerous (e.g., hundreds of) gNB-DUs. The decomposed gNB reduces the equipment costs, reduces transport bandwidth requirements, provides flexibility of vendor selection, and facilitates independent evolution and upgrades of gNB-CU and gNB-DU.