erage. The realization of outdoor small cells by micro base stations means CAPEX for compact micro equipment, but OPEX is very significant for backhaul and site rental. The IMPEX for site acquisition and deployment are also relevant cost factors. Micro cells should be deployed in dedicated spectrum if available. However, for low to medium traffic-density areas or already-deployed macro spectrum, in-band deployment is the preferred solution. Alternatively, small cells can be realized by sharing (or pooling) baseband functions with macro cells and deploying the outdoor small cell RF as a low-power Remote Radio Head (RRH) with a dedicated fibre-based fronthaul transport. Low power RRH does not include any dedicated baseband, which can save CAPEX and ease operations and maintenance. However, this is offset by the requirement to have a dark fibre between the RRH and macro baseband module. 5.7.3 Outdoor Pico Cluster For outdoor hot zones, pico cluster-based solution can provide a very economical approach compared to other traditional solutions and cell site splitting. A pico cluster solution helps to reduce TCO by simplifying backhaul, managing inter- and intra-layer interference to provide LTE Small Cell Optimization Indoor Macro Macro+Pico Macro+Pico Macro only Macro+Pico + Indoor Urban hotspot: Suburban: 4 macro sites 14 macro sites Figure 5.12 Total cost of ownership in different HetNet scenarios higher performance and limit the amount spectrum planning. The pico cluster provides vir- tually unlimited scalability, limiting the impact to the core network with local break out and simplifying the operations management and installation. 5.7.4 Indoor Offloading Wi-Fi is always a low-cost supplement to macro and micro cell deployments since the spectrum is freely available. However, the cost of Wi-Fi depends on the particular backhaul and site acquisition. Wi-Fi and small cells have very similar TCO performance, with similar CAPEX and almost identical installation and operational costs. Indoor small cells offer large ben