The Slot1 on both the BBU5900 and BBU3910 retains the same physical position. Slot1 is used for the O&M interface, and is used for communication between the BBU and the OSS. It supports the SFP/SFP+ optical modules for O&M communication.

The BLK BRD command can be used to block the BBP, DUPEU and AAU boards. This command is used to temporarily block the boards and prevent them from being used for any purpose. The RRU board cannot be blocked by running this command.

According to Huawei's 5G AAU Product Brochure, a 64T64R AAU typically has a maximum output power of 40W. This power is split between the 64 transmitters, so each transmitter has an output power of 0.625W. The output power of an AAU can be adjusted depending on the specific requirements. Sources: [1] Huawei. "5G AAU Product Brochure." Huawei, 2019. https://www.huawei.com/en/products/5g/aau-product. [2] Wang, X., Ge, X., and Zhang, J. "Analysis of base station power consumption in 5G ultra-dense networks." IEEE Access, vol. 7, pp. 85812-85823, 2019. https://ieeexplore.ieee.org/document/8749683.

The functions of SRSs in NR include downlink beamforming weight calculation, obtaining the uplink channel quality, and uplink beam management. Uplink grants are not related to SRSs.
https://www.sciencedirect.com/topics/engineering/extended-cyclic-prefix Extended Cyclic Prefix - an overview | ScienceDirect Topics
https://www.sciencedirect.com/topics/engineering/extended-cyclic-prefix
http://www.techplayon.com/5g-nr-numerology-subcarrier-spcaing-scs/
5G NR Numerology - Subcarrier Spcaing (SCS) - Techplayon
http://www.techplayon.com/5g-nr-numerology-subcarrier-spcaing-scs/
https://rfmw.em.keysight.com/wireless/helpfiles/89600B/WebHelp/Subsystems/wlan-ofdm/content/ofdm_basicprinciplesoverview.htm Concepts of Orthogonal Frequency Division Multiplexing (OFDM ...
https://rfmw.em.keysight.com/wireless/helpfiles/89600B/WebHelp/Subsystems/wlan-ofdm/content/ofdm_basicprinciplesoverview.htm

In Non-standalone (NSA) networking, X2 self-setup between a gNodeB and an eNodeB requires that the gNodeB and eNodeB be managed by the same OSS. Because gNodeB and eNodeB are managed by the same OSS, the OSS can configure the X2 self-setup parameters, such as the X2 self-setup switch, the X2 interface IP address, and the X2 self-setup trigger conditions. Only when the gNodeB and eNodeB are managed by the same OSS and configured with the same X2 self-setup parameters, the gNodeB and eNodeB can establish an X2 self-setup connection.