9x + 10.517 y = - -1.0361x + 15.649 y = -0.8474x + 13.533 Average channel quality indicator Figure 13.40 Average aggregation level as a function of average channel quality indicator for three different bands using 15-minute statistics loaded cells per different frequency bands and bandwidths. As it can be seen the high carrier frequency band has lower average aggregation level compared to the low carrier frequency band allocations. As can be seen from Figure 13.40 the average aggregation level of high band 20 MHz bandwidth allocation increases much faster compared to the high band 10 MHz bandwidth allocation. This is due to the fact that 20 MHz bandwidth has double capacity for PDCCH compared to 10 MHz bandwidth and this double capacity means that necessity for lowering the aggregation level by power increase is much lower hence the average aggregation level can be increased for more UEs compared to the 10 MHx bandwidth. 13.5 Signalling Load and Number of Connected Users Dimensioning The signalling load and number of connected users per eNodeB and cell during the mass event has to be carefully dimensioned. Each eNodeB has limited signalling load capacity given, for example, in terms of call setups per second or control plane actions per second. In case the signalling load capacity of eNodeB is exceeded then depending on the eNodeB overload control efficiency either the call setup success rate and dropped call rate degrade or eNodeB collapses out of service. Latter scenario in case of no proper overload control needs to be avoided by proper dimensioning. Each cell or eNodeB also has upper limit of number of supported simultaneously RRC- connected state users for which PUCCH capacity is allocated (CQI and scheduling request transmissions) and synchronization with eNodeB maintained. Exceeding this capacity limit would cause call setup rejections at RRC connection setup phase. Any rejected RRC connection setup leads to re-attempt by the terminal which in turn causes increase in random access procedures and uplink int