rrier is ~3 Gbps at baseband and higher after up-conversion. Note that the beamforming component is optional. The O-RAN fronthaul specifications define Type A and Type B RU options where the Type B RU includes beamforming in the RU that otherwise (Type A) would be in the DU. Type B RUs are intended for systems where the number of transmission layers is smaller than the number of physical antennas. For these systems, doing beamforming in the RU allows the fronthaul interface bandwidth to remain limited. Typically, remainder processing functions are grouped or clustered into few as possible components to reduce IO bandwidth. Typically, this includes channelization and up/down- conversion up to and including crest factor (CF) reduction (CFR), digital predistortion (DPD), and additional filtering and sample rate adaptation components. The analog-to-digital converter (ADC)/digital-to-analog converter (DAC) can be either on-chip (e.g., Xilinx RFSoC3 or NXP Layerscape Access4 or connected over a JEDEC Standards (JESD) interface. JESD is a standardized IQ + synchronization interface that is designed for the purpose of ADC/DAC communication for telecommunication applications. Remainder components are in the analog domain and can be either integrated with the ADC/ DAC or implemented using discrete components, up to the power amplifier and Low Noise Amplifier (LNA) stages which are implemented as discrete components of their own or come pre- integrated in a front-end module. More information can be found in the chapter 4. Digital beamforming and fast Fourier transform The transmit and receive processing is straightforwardly defined as a (matrix) multiplication operation to apply the per user/antenna weights to the received IQ stream. The theoretical baseline processing required can be calculated from the required operation which is a matrix 78 Open Radio Access Network (O-RAN) Systems Architecture and Design multiplication between an antenna X layer matrix and a frequency domain input vector. This matrix multiplication can 