 of the receiver and wireless signal in real-time. This is typically possible only in case of static environments such as Fixed Wireless Access deployment. This can be looked at as a quasio- pen loop approach. On the other hand, automatic is a closed loop approach where Rx power is measured, and the receiver chain is tuned accordingly. Gain control needs to be balanced between quick con- version to the target value whilst avoiding overshoot. In OFDM system, gain changes should be applied on symbol boundaries (within the OFDM Cyclic Prefix) and thus requires timing control. Signal processing chains needed for gain control include digital Receive Signal Strength Indication (calculate the sum of I2 + Q2). Bursty traffic, dynamic user scheduling can drive very fluctuant power between slots. If user has some knowledge of this profile, it can use it to help ADC gain setting, which can lead to combined manual and automated gain control. References 1. LTE MAC Scheduler Interface Specification vl.11. 2. CPRI eCPRI Specification v2.0, "Common Public Radio Interface: eCPRI Interface Specification," May 2 2019. 3. Morgan, D., Ma, Z., Kim, J., Zierdt, M., Pastalan, J. A generalized memory polynomial model for digital predistortion of rf power amplifiers. IEEE Trans. Signal. Process. 2006, 54 (10). Chapter 6 User-plane application components Further reading ETSI. NR; Physical channels and modulation, 3GPP TS 38.211. ETSI. NR; Multiplexing and channel coding, 3GPP TS 38.212. ETSI. NR; Physical layer procedures for control, 3GPP TS 38.213. ETSI. NR; Physical layer procedures for data, 3GPP TS 38.214. ETSI. NR; Physical layer measurements, 3GPP TS 38.215. 5G FAPI: PHY API Specification, https://www.smallcellforum.org/5g-phy-api-release/ ETSI. NR; Requirements for support of radio resource management, 3GPP TS 38.133. ETSI. NR; Base Station (BS) radio transmission and reception, 3GPP TS 38.104. https://github.com/LITMUS-RT/cyclictest. https://www.enea.com/products/operating-systems/real-time-accelerated-linux/ https://www.6wind.com