nd CP addition Digital Analog Conversion Analog beamforming * 8 stream is mandatory; > 8 stream is optional. Figure 4.5.2 Downlink split description, NR, Category "A" Radio. (Source: Reproduced by permission of © O-RAN). 4 NG-RAN Architecture Dotted line blocks PDCCH PDSCH are optional. Signal CSI-RS Scrambling Scrambling Scrambling generation generation generation generation Generation generation Modulation Modulation Modulation Modulation Modulation Modulation Modulation Modulation Modulation Layer Mapping RE Mapping IQ Compression O-RAN FH IQ Decompression Precoding and Precoding and Precoding and Precoding and Beamforming Beamforming Beamforming Beamforming Beamforming iFFT and CP addition Digital Analog Conversion Analog beamforming Figure 4.5.3 Downlink split description, NR, Category "B" Radio. (Source: Reproduced by permission of O-RAN). PUxCH PRACH Descrambling Demodulation (PHY part) Equalization, iDFT Channel Detection Channel Estimation Estimation RE demapping RE demapping RE demapping IQ Decompression Decompression Decompression O-RAN FH IQ Compression IQ Compression Compression Digital Digital Digital Beamforming Beamforming Beamforming *for PRACH, Filtering block includes CP FFT and CP removal Filtering* removal, decimation filtering, and a smaller FFT or a Analog to Digital larger FFT and PRACH subcarrier Analog Analog Analog Dotted-line blocks selection Beamforming Beamforming Beamforming are optional Figure 4.5.4 Uplink split block diagram. (Source: Reproduced by permission of © O-RAN). 4.5.3.3 Latency Management The move to Ethernet-based fronthaul simplifies implementation and is cost-effective; however, it also brings additional challenges. One of the issues is latency, which is caused by packetizing the radio data in Ethernet transport network (for additional details, see Section 6.6). For RAN, the end-to-end latency includes the delay of radio data during Ethernet encapsulation, data transmission between O-RU and O-DU, and the O-RU processing. The total latency budget also restrains the phy