ic access class barring for mobile-originated data call attempt according to Reference 8 management entity (MME) statistics by calculating the ratio between registered users, which is the number of subscribers, and number of connected users, which is the number of evolved packet system connection management connected users. Figure 13.47 shows one example result of ratio of RRC-connected users and MME-registered users which can then be used to estimate subscriber amount based on the RRC-connected users. It should be noted that the inactivity timer setting, that is, how long the RRC-connected users is kept connected without any uplink or downlink traffic, plays a significant role in the ratio of connected users and registered users. Figure 13.42 can then be updated based on Figure 13.47 as shown in Figure 13.48 which shows that with high number of subscribers per cell around 3.4 RRC setups are generated per subscriber per 15 minutes. Then all types of signalling events per subscriber can be derived and used together with peak to average ratio calculations based on Figure 13.41 to estimate signalling load per eNodeB for mass event. 13.6 Load Balancing Load balancing functionality can be activated between the different frequency band cells (or also between same carrier band cells) to balance the load. Idle mode load balancing algorithm typically directs certain amount of RRC-connected users for which the RRC connection release message is about to be sent (and RRC connection released), from one carrier frequency to another. Similar load balancing functionality can be done during RRC-connected state using measurements and handovers. But as in case of special event analysed here each carrier Capacity Optimization Figure 13.47 Hourly ratio between RRC-connected users and mobility management entity (MME)- registered users based on MME statistics over 8 days (RRC connection inactivity timer = 10 seconds) frequency has full coverage and users are mainly outdoors there is no need to perform any target frequency (inter-freque