ly simple solution is to cancel the interference caused by Cell-specific Reference Signals (CRSs). When the Resource Utilization (RU) is low, most of the interference is caused by CRSs. Figure 16.15 illustrates the gain of CRS interference cancelation as a function of the network loading. When the RU is low, the gain can be 30-50%. Further improvements are obtained with the cancelation of the Physical Downlink Shared Data Channel (PDSCH). This feature is called Networks Assisted Interference Cancelation and Suppression (NAICS). The network assistance improves the cancelation perfor- mance since the network provides assistance information to the UE regarding the source of the interference, including cell identity, number of CRS antenna ports, power offsets, transmission modes, resource allocation, and precoding granularity. 16.3 LTE-Advanced Pro Technologies Gain of CRS Interference Cancellation RU=10% RU = 20% RU = 30% RU = 40% RU = 50% Figure 16.15 Gain of Common Reference Signal Interference Cancelation (RU = Resource Utilization). 16.3.4 Extreme Local Capacity with Ultra-Dense Network LTE-Advanced radio has demonstrated high efficiency in the macro-cellular layer, but it has not been enough to satisfy the needs of the most extreme traffic hot spots. Small cells are the next step in providing increased local capacity. Such high-traffic hot spots typically appear in dense urban areas, in sports venues, or in music festivals. 3GPP has defined a number of enhancements that make small cell deployment more efficient in coordination with the existing macro layer. Further Enhanced Inter-Cell Interfer- ence Coordination (feICIC) was added in Release 11, and dual connectivity in Release 12. Dual connectivity allows the user device to receive data simultaneously from two different sites served by backhaul having non-negligible latency. Dual connectivity is enhanced in Release 13 to also support uplink transmission to two sites. Dual connec- tivity can be utilized for HetNets consisting of macrocells and many small cells.