rios. When used in conjunction with CSI acquisition, the beam management allows the network to establish a seamless and low-latency link with the UE for data transmission. This is specifi- cally important for over-6 GHz where a large number of narrow analog beams are used for data transmission, which in some scenarios requires frequent beam switching. Once the link is established via beam management, CSI acquisition can assist the network in link adaptation. 4.1 Downlink Physical Layer Functions and Procedures 4.1.1 Overall Description of Downlink Physical Layer The NR downlink physical layer consists of higher layer configurable functional blocks and protocols that are configured according to the downlink physical channel characteristics, use case, deployment scenario, etc. As shown in Fig. 4.1, the downlink physical layer proces- sing generally includes receiving higher layer data [e.g., MAC PDUs in the case of down- link shared channel or master information block (MIB) in the case of physical broadcast channel (PBCH)]; cyclic redundancy check (CRC) calculation and attachment; channel encoding and rate matching; modulation; mapping to physical resources and antennas; multi-antenna processing; and support of layer-1 control and HARQ-related signaling. It was mentioned in Chapter 3 that OFDM was chosen as the default waveform in NR for both downlink and uplink directions due to its robustness to multipath delay spread and frequency-selectivity of wireless channels as well as scheduling flexibility for transmission of different channels and signals. Unlike LTE, the DFT-precoded OFDM is an optional transmission scheme in NR uplink that is used in link-budget-limited use cases. While the use of DFT-precoded OFDM in the uplink has certain advantages in reducing the PAPR (and alternatively the cubic metric) and achieving higher power-amplifier efficiency, it has several drawbacks including limitation in the use of spatial multiplexing, asymmetric downlink/uplink transmissions which would limit the sidelink operation, 