tor channel (PCFICH), synchronization channels and paging channel are transmitted during ABS. When the interference from the macro cell is reduced during ABS, the pico cell is able to serve UEs which are further away from the pico cell. The ABS muting pattern is periodical with 40 subframes for FDD mode, while the value in Dedicated small cell frequency Macro Co-channel deployment Macro Figure 7.7 Small cell coverage area with dedicated frequency and co-channel deployment LTE Small Cell Optimization = Sub-frame with normal transmission = Almost blank sub-frame (ABS) = Sub-frames with less interference Sub-frame (1 ms) Macro Pico cell can serve more Pico cell can serve UEs UEs during ABS with that are close to pico cell range extension during non-ABS Figure 7.8 eICIC interference coordination in time domain TDD mode depends on the uplink/downlink configuration. The periodicity of 40 subframes for FDD has been selected to maximize the protection of common channels, including uplink hybrid automatic repeat request (HARQ) performance. For maximum benefit from eICIC, eNodeBs in a given local area are recommended to use overlapping and coordinated ABS muting patterns. The inter-eNodeB X2 application protocol offers support for adjusting the ABS muting pattern [2]. However, the process of adjustment can be too slow as compared to the rapid fluctuations of the traffic. For those cases more dynamic solutions will be discussed in Section 'Fast Dynamic eICIC'. When the macro cell uses ABS, the pico users are obviously exposed to much less inter- ference, which allows the pico cell to serve users from a larger geographical area as would otherwise have been feasible. This is illustrated in Figure 7.9, where the pico cell uses a large value of the so-called range extension (RE) to increase its service area. Hence, the use of ABS at the macro cell offers enhanced opportunities for load balancing between the macro and pico cell. Macro Range extension Figure 7.9 Range extension with ABS Small Cell Interference Management In order