 femto cells) into the group of small cells [20], where micro cells typically are used outside the urban areas. Other classifications state that small cells are mainly hotspot and pico cells [12]. Small cells have multiple benefits. They provide better signal to noise ratio for users all cell locations, including cell edges. They require lower transmitting power of mobile devices due to lower distances to the base stations, which saves battery power and hence gives better QoE for use of the mobile services. Also, small cells decrease the interference due to lower transmitting power in both directions (downlink and uplink) and hence improve network performances and with that QoS. However, the number of small cells and their sizes depends on the projected number of active users (e.g. it is different when small cells are used in enterprise environments on one side and rural areas on the other). With the frequency reuse on smaller distances, small cells add capacity with the same spectrum. Additionally, small cells provide the possibility to use millimeter wave spec- trum (above 6 GHz, such as the 24-86 GHz spectrum in different bands), due to smaller distances and the possibility of line-of-sight communication between the mobile net- work equipment (e.g. radio units) and the mobile devices. Regarding spectrum type, small cells can be deployed in both the licensed and unli- censed spectrums, unlike macro cells which can utilize only the licensed (i.e. reserved) spectrum. The mobile networks have entered the unlicensed spectrum with the LTE standards for such a case. If one compares LTE VS. WiFi in the unlicensed spectrum [21], LTE gives better QoS due to its radio interface, which is well designed and standardized to guarantee QoS to substantial numbers of users in different traffic scenarios. However, to have QoS in mobile networks with small cells, the backhauling for small cells is also very important, i.e. their connection toward the operator's core network. The following requirements exist for small cells backha