C setup attempts rejections by eNodeB admission control. This means that the parameters limiting the number of RRC-connected users and corresponding PUCCH Capacity Optimization y = 74.412x-0.098 = Average number of RRC-connected users Figure 13.42 RRC connection setup attempts per average number of RRC-connected users versus average number of RRC-connected users per cell per 15 minutes capacity allocation parameter values should be set large enough to avoid any avalanche of RRC connection requests and RRC connection rejects. Figure 13.43 shows the average number of RRC-connected users versus maximum number of RRC-connected users per cell per 15 minutes in mass event area. As it can be seen there are two types of cells in the area: cells for which the max number of RRC-connected users is 700 and cells for which the max number of RRC-connected users is 580. When the maximum supported RRC-connected users limit Average number of RRC-connected users Figure 13.43 Average number of RRC-connected users versus maximum number of RRC-connected users per cell per 15 minute LTE Small Cell Optimization RRC connection setup rejections due to max number of RRC-connected users Figure 13.44 RRC connection setup rejections due to max number of RRC-connected users reached the maximum limit set for the cell versus maximum number of RRC-connected users per cell is reached the admission control of the eNodeB starts to reject the RRC connection setups. The rejection rate reaches extremely high values easily as shown in Figure 13.44. These admission control rejections will increase the total signalling load due to the terminals retrying until connection is established, that is, capacity granted by the eNodeB. Example of this is shown in Figure 13.45 which shows the number of preambles needed per RRC setup attempt for cells and times (15-minute samples) for which there are admission control rejections for RRC setup attempts because max number of RRC-connected users limit was reached. The increase in the number of preambles needed per RRC 