 mainly specified in 3GPP Rel-9, which included optimization of coverage, capacity, handover, and interference. Mobility load balancing is a feature where cells experiencing congestion can transfer excess load to other cells which have available resources. Mobility load balancing fur- ther allows the eNBs to exchange information about the load level and the available capacity. The report can contain computational load, S1 transport network load, and radio resource availability status. There are separate radio resource status reports for the uplink and downlink, which may include the total allocated resources, guaranteed bit rate (GBR) and non-guaranteed bit rate traffic statistics, the percentage of allocated physical resources relative to total resources, and the percentage of resources available for load balancing. Mobility load balancing can also be used across different radio access technologies. In case of inter-RAT, the load reporting RAN information man- agement protocol will be used to transfer the information via the core network between the base stations of different radio technologies. A cell capacity class value, 52 Chapter 1 set by the operation and management system, is used to relatively compare the capaci- ties of different radio access technologies. A handover due to load balancing is per- formed as a regular handover; however, it may be necessary to set the parameters such that the UE cannot return to the [congested] source cell. Mobility robustness optimization is a solution for automatic detection and correction of errors in the mobility configuration which may cause radio link failure as a result of unsuccessful handover. Self-healing: Features for automatic detection and removal of failures and automatic adjustment of parameters were mainly specified in 3GPP Rel-10. Coverage and capacity optimization enables automatic correction of capacity problems due to variations of the environment. The minimization of drive tests was a feature that enables normal UEs to provide the same type of informat