tegrated Small Cell). We discuss typical scale/dimensioning for each of these solutions, as well as some of the implementation choices that the hardware/systems architect has. Implementation options evolve over time, as silicon technology improves. This makes way for the possibility that any device performance claims made in this chapter are likely to be outdated as soon as they are written down. So we aim to stay away from calling out any specific devices or device vendors but instead stay in generic vendor-independent terminology. Scalability Depending on the scale of the deployment, we consider the following architectural options (in order from large-scale to small-scale). These four examples will be covered in more depth later. Data Center-connecting tens of cell sites and potentially 100 S of radios. Fronthaul bandwidth is in the order of Tbps maximum and aggregate MAC/PHY throughput is 10 Gbps. Cell Site Solution-connecting single cell tower with multiple (3, 9, 6, 12) sectors. Fronthaul bandwidth is in the order of 100 Gbps maximum and aggregate MAC/PHY throughput is in the order of 20 Gbps. Central Unit/Distributed Unit (CU/DU) based small cell solution-distributed small cells, for example, for indoor deployment as picked for the example in Chapter 1, O-RAN Overview. Fronthaul bandwidth is in the order of 25-50 Gbps and aggregate MAC/PHY throughput is in the order of 5-10 Gbps. Integrated Small Cell-all-in-one solution with optimized power/cost. Aggregate MAC/ PHY throughput is <1-5 Gbps. The scalability aspect is important to take note of here. Overall fronthaul bandwidth and MAC/PHY throughput scale is up to one hundred times! Clearly, a single solution does not match all deployment options. Scalability was a key target of 5 G standards development, and we can see some of this at work here. Now, on the other hand, let's look at how scalability works from a component/system point of view. Let's look at some Open Radio Access Network (O-RAN) Systems Architecture and Design. DOI: https://doi.org/10.1016/B9