ease during the mass event compared to the normal traffic time, the uplink inter-cell interference limits the performance. Therefore, the power LTE Small Cell Optimization RRC connection setup attempts Total UL data volume RRC conenction setup success rate Random access setup success rate RSSI change relative to lowest value SINR change relative to highest value 400,000 350,000 300,000 250,000 200,000 150,000 100,000 50,000 Figure 13.8 Impact of aggressive uplink power control on RRC and random access setup success rates and PUSCH RSSI and SINR. Statistics (15-minute samples) are averaged over cluster of cells for which RRC connection setup attempts are the highest during the peak time control strategy of physical uplink shared channel (PUSCH) and physical uplink control channel (PUCCH) needs to be set SO that inter-cell interference is always minimized. In aggressive uplink power control strategy is used, to achieve maximum uplink throughput, all the UEs will transmit with extremely high power regardless of the location under the cell. This causes the uplink received signal strength indicator (RSSI) to increase and the signal to interference and noise ratio (SINR) decrease with increasing traffic (uplink data volume and/or signalling). Degraded PUSCH SINR in turn causes the degradation of random access setup success rate and RRC connection setup success rate and causes poor end-user experience as shown in Figure 13.8. Note that the RRC and random access setup success rate performance indicators used in Figure 13.8 are introduced in Chapter 12. As it can be seen from Figure 13.8 the PUSCH RSSI increase and PUSCH SINR decrease start when signalling (in terms of number of RRC attempts) increases. The lowest PUSCH SINR value and lowest random access setup success rate occur at the highest level of RRC connection setup attempts (at sample 45). At this point also the RRC setup success rate is at lowest level and PUSCH RSSI is highest. Then RRC connection setup attempts start to decrease and that causes PUSCH SINR to i