 centralized SON. Figure 2-2 presents a flowchart for the distributed SON. Central SON Element Management System Optimization decisions are made at each eNodeB and parameters are tuned Itf-N Distributed SON accordingly. ENodeB N Itf-N Itf-N Cell N+2 Cell N+1 Distributed SON Distributed SON X2-link ENodeB 1 ENodeB 2 Cell N Cell A Cell C Cell D Cell F Cell B Cell E Figure 2-2. Distributed SON example CHAPTER 2 SELF-ORGANIZING NETWORKS IN LTE DEPLOYMENT A distributed SON solution is preferred for the following LTE optimization features: Mobility robustness optimization Scheduler optimization for spectral efficiency VS. cell edge user throughput The reason that distributed SON is preferred for these features is because these optimizations do not impact the other cells in the network and would only optimize the cell or eNodeB to improve the KPIs of the cell. Also, the adaptations can be much faster when these optimization parameters exist on the distributed level. Hybrid SON Hybrid SON is a combination of centralized SON and distributed SON, wherein a part of the optimization algorithms is centrally located and another part exists at the element or nodal level in eNodeB. In hybrid SON, normally at the distributed level, algorithms and optimization schemes that exist are targeted to provide a quicker solution, whereas a detailed, well-educated solution algorithm normally resides on the centralized level. This kind of hybrid solution provides more flexibility to the network over that of a purely centralized or purely distributed SON solution, thereby making it practical for different types of optimizations. Figure 2-3 presents the flowchart for the hybrid SON. Central SON Some parts of the optimization decisions are Element made centrally and passed Management on to individual nodes. System Some parts of the optimization Itf-N Distributed SON decisions are taken on the ENodeB N individual node level. ltf N Itf N Cell N+2 Cell N+1 Distributed SON Distributed SON X2-link ENodeB 1 ENodeB 2 Cell N Cell A Cell C Cell D Cell 