the data channel and receives and/or sends data) changes quite a lot compared to the normal day as depicted in Figure 13.5. The QCI1 (VoLTE) E-RAB session time is reduced during the event time compared to the normal day and this is most likely due to the fact that end users seldom make any voice calls Capacity Optimization Amount of E-RAB setup attempts per subscriber Relative (min = 1) E-RAB setup attempts, non-GBR Amount of E-RAB setup attempts per subscriber Relative (min = 1) E-RAB setup attempts, non-GBR Figure 13.4 Average E-RAB setup attempts per subscriber in mass event area during (a) normal day and (b) mass event day per 15-minute data samples during the actual mass event and rather send some social media updates. The non-GBR E-RAB session time has a sharp peak exactly at the event time. This is due to the fact that the activity is heavily uplink dominated and as the uplink is having, in general, lower spectral efficiency compared to downlink it takes longer time to deliver similar amount of data in uplink than in downlink. Also uplink is very sensitive to interference and UE power control as shown in Section 13.3. The user behaviour, that is, amount of data calls and amount of data volume per each of the call, changes heavily during the day even if there are no special events. Figures 13.6 and 13.7 show per registered user the amount of E-RABs requested per hour versus downlink and uplink data volume per hour. Figures 13.6 and 13.7 are based on whole network level hourly statistics averaged over several normal days, that is, there are no special events occurring during the analysed days. LTE Small Cell Optimization Average session time per E-RAB (QCI1) (s) Average session time per E-RAB (non-GBR) (s) Average session time per E-RAB (QCI1) (s) Average session time per E-RAB (non-GBR) (s) Figure 13.5 Average session time per E-RAB in mass event area during (a) normal day and (b) mass event day per 15-minute data sample DL data volume per hour (MB) Figure 13.6 User activity during a normal working day vers