n the two cells or eNodeBs and there is no existing X2AP link between the two. Considering that the X2AP links that can be maintained by an eNodeB are often limited, there needs to be some mechanism for the eNodeB to decide on maintaining an X2 link with one eNodeB over another. One way to achieve this is for the eNodeB to maintain a priority tag against each neighbor in the NRT and update it at a predetermined interval based on the number of handovers performed between the two eNodeBs and the percentage of handover failure for the pair and the operator to which the neighboring eNodeB belongs. With this combination, the eNodeB should be able to use the X2 links only between high-priority neighbors and release the X2 link for the lower-priority neighbor. A sample NRT is shown in Figure 2-11 with some useful information for each of the neighbors. SON and Self-Optimization Motivation of Intercell Interference Coordination The LTE systems operate mainly with a reuse 1 factor, as this helps maximize the capacity and bandwidth usage. However, this also means that there is a very high scope of interference for the UEs that are at the cell edge. Depending on the measured signal strength from the neighboring cell at the cell edge, the interference can lead to a high performance or throughput loss for the cell edge users. In turn, this will lead to a drop in spectral efficiency for the entire network. Intercell interference coordination (ICIC) solutions try to bring balance between the cell throughput and cell edge users' data rate. CHAPTER 2 SELF-ORGANIZING NETWORKS IN LTE DEPLOYMENT Principle of ICIC and Frequency Reuse Frequency reuse is one of the best means to reduce intercell interference. The frequency reuse coefficient can be 1, 3 or 7. When the reuse coefficient equals 1 (i.e., adjacent cells are using the same frequency resource), at the cell edge, interference would be serious. A larger reuse coefficient can reduce intercell interference further, but care should be taken when doing this, as it will directly resu