ologies. 11.5.2.3 Ultrahigh Density and Self-Backhaul Small cells are a very important aspect of the 5G network. The use of mmWave frequencies requires small cells because of their short range. Also, small cells are one of the most effective ways to improve the "capacity per area" of the network, an important 5G objective to handle the accelerating demand for more data. One of the biggest challenges in creating a dense network of small cells is the need for a dense transport network to support backhaul from the small cells. In 5G, each small cell will require backhaul speeds of tens of Gb/s. Self-backhaul is a technique that allows the 5G access radio to simultaneously provide access to users, and to make backhaul connections to access radios at other 5G cell sites, using the same spectrum. This can be a major factor in reducing the cost of deploying a very dense network of small cells, since fiber-based transport would not need to be deployed to each small cell location. Self-backhauling is a natural choice in the mmWave band. As shown in Figure 11.19, the beamforming phased array antenna panels can create separate beams ded- icated to backhaul with minimal interference to the access beams used to reach customers devices. The NFV and SDN capabilities of the new access architecture provide an excellent platform for implementing the self-backhaul capability. SDN can provide rapidly adaptable network configura- tions across a dynamic web of self-backhaul links that can adjust to changes in connectivity, and NFV can adjust resources between various access and backhaul links as needed to optimally handle changes in traffic patterns. 11.5.2.4 Flexible Carrier Configuration The key characteristic of 5G is its ability to support multiple types of traffic on a single network. Traffic types as diverse as eMBB, massive MTC, and critical MTC create very different types of demands on the resources of the radio network. In the past, efficiently supporting these traffic types would require separate independent radio networks a