 though the goal of the eCPRI and related standards is to run IQ traffic on a standard Ethernet/Internet Protocol (IP) network, minimum throughput and maximum latency bounds are still required for support of IQ sample-based communication. Besides support for 802.1 cm and other quality of service stan- dards as we discussed before, this means we need to provision minimum IO bandwidth requirements at the DU and RU, as well as the Ethernet network between these two units. The goal of this chapter is to define the required bandwidths for various use-cases/configurations. 5G bandwidth examples 5G fronthaul bandwidth can be estimated by calculating the aggregate number of (frequency domain occupied) IQ samples that are carried over the fronthaul link. This is defined by the air interface bandwidth, number of antennas (RU Type A), or layers (RU type B) carried as well as the subcarrier spacing which defines the slot time, given that each slot constitutes 14 symbols. 5G car- rier bandwidths and the number of occupied IQ samples per 3GPP are copied below (Table -1): As an example, assuming 30KHz subcarrier spacing, per baseline unit of 100 MHz occupied bandwidth, a single layer corresponds to 3276 (occupied subcarriers) X 14 (symbols/slot) X 2000 (slot/second) X 32b (uncompressed IQ data) = 2.93 Gbps. We multiply this by the number of layers to define the transmit or receive bandwidth requirements. The fronthaul bandwidth can optionally be reduced by using IQ compression techniques such as modulation, Block Float, a-law/u-law and other compression techniques as defined in the O-RAN CUS Plane fronthaul specification. 16 to 9- or 12-bit compression are often used in O-RAN implementations, depending on the use-case defined. Scaling up to the defined use-cases, (peak) bandwidths are summarized in below tables for some low-end and higher-end examples (Tables 3-2 and 3-3). Table 3-1 Number of 5G/NR occupied subcarriers for 30KHz subcarrier spacing for different RF bandwidths. 5G b/w Carriers Chapter 3 Hardware system dimensioni