2020年IAB 5G回传技术创新白皮书 - 5G Americas（英文版）（62页）.pdf

1、5G Americas | Innovations in 5G Backhaul Technologies: IAB, HFC the number of MIMO layers; the maximum supported modulation scheme; the number of transmit and receive antennas; and the use cases that need to be supported by the network. The distribution of radio access network (RAN) functions betwee

2、n the radio antenna site and central locations also plays a pivotal role in the transport requirements. These functions include radio frequency (RF) signal processing and other layers of the protocol stack, including: the physical (PHY); medium access control (MAC); radio link control (RLC); packet

3、data convergence protocol (PDCP); and radio resource control (RRC) layers. Figure 2 shows the relationship between the RAN functions and the 5G core network (5GC) and end user equipment (UE). In 2, the Third Generation Partnership Project (3GPP) defined a next generation RAN (NG-RAN) architecture wh

4、ere 5G NR base station (gNB) functionality is split between two logical units: a central unit (CU) and a distributed unit (DUs). In the 3GPP model, the CU is connected to the 5G core (5GC) via the NG interface and the CU is connected to the DU via the F1 interface, as shown below in Figure 3. Figure

5、 2 - Radio access network functions Figure 3 - 3GPP NG-RAN Architecture The 3GPP studied several different functional splits between the CU and DU in 2. In total, 8 possible split options were considered, including 5 high level split (HLS) options and 3 low level split (LLS) options. The different s

6、plit options are shown in Figure 4 below. Figure 4 - Functional split between central and distributed units 5G Americas | Innovations in 5G Backhaul Technologies: IAB, HFC (b) IAB node using EN-DC (NSA mode) Figure 13 - IAB CU/DU architecture 2.2.1 IAB-donor As shown in Figure 11, an IAB-donor is a