ds on the density of pico cells and their location. For more details, see [4,5]. In general, the more picos that benefit the macro cell using ABS, the higher is the gain from eICIC. Furthermore, the gain from eICIC is generally highest for the cases where both macro and pico cells are outdoor; the gain is reduced for scenarios where the pico cells are indoor. The reason is that the indoor users tend to be served by the indoor pico cells, while the interference from the macro layer is suppressed by the in-building penetration loss. The third factor that impacts the eICIC performance is the UE capabilities, resulting in the highest gain for Release 11 UEs, while worthwhile gains are also achievable for UEs of earlier releases [6]. Finally, eICIC naturally starts to offer benefits when the offered traffic load raises to the point where inter-cell interference between macro and pico cells starts to be a performance limiting factor [2]. The gain eICIC mechanism is further illustrated in Figure 7.12, where it is pictured how multiple picos benefit from each subframe where the macro uses ABS. This represents an attractive net benefit as the aggregated performance gain of the picos exceeds the loss from muting at the macro. Therefore, we can expect that eICIC provides more gains when the number of pico cells increases. Furthermore, as the use of muting at the macro allows offloading more users to the picos, eICIC also offers a net benefit for the remaining macro-users, given that the fraction of offloaded users from applying eICIC exceeds the percentage of subframes ABS adaptation and load balancing Fast and accurate ABS muting pattern adjustment and dynamic load balancing maximize the benefits of eICIC Small cell placement and density Highest eICIC gain observed for cases with outdoor dense small cell deployment. Moderate eICIC gain for cases with indoor cells Terminal support Moderate gain for pre-Release 10 UEs. Clear gain for Release 10 UEs and even higher gain for Release 11 UEs Offered traffic load Hardly any gain 