d noise ratio (SINR), RACH setup success rate and RRC setup success rate of highest loaded cells for conservative uplink power control; 15-minute data samples are used Capacity Optimization Fibre Baseband Figure 13.26 Centralized RAN solution for stadium capacity 13.3.4 Centralized RAN The uplink capacity can be enhanced considerably by using coordinated multipoint (CoMP) reception in uplink. The solution for implementing CoMP is called here as centralized RAN (CRAN) because of centralized baseband location. A typical stadium installation is illustrated in Figure 13.26 where the stadium is covered by eight cells each with 2x2MIMO. The RF units are connected with fibre to the baseband unit. The traditional solution without uplink CoMP receives the UE transmission only via one cell while the UE transmission causes interference to the adjacent cells. The inter-cell interference is a problem especially in the open areas like stadiums where it is difficult to create clear dominance areas. The uplink CoMP solution can receive the UE transmission via multiple cells increasing the signal level and reducing the interference, which leads to a clear gain in the quality of the uplink signal. The traditional solution is shown in Figure 13.27 and the uplink CoMP solution in Figure 13.28. A number = Signal = Interference Baseband Figure 13.27 Traditional uplink reception via single cell = Signal Y Y Y Y Y Y Y Y Baseband Figure 13.28 Uplink CoMP reception via multiple cells LTE Small Cell Optimization Uplink throughput at stadium CRAN off CRAN on Open-loop PC Closed-loop PC Figure 13.29 Throughput gain with uplink CoMP in centralized RAN (CRAN) of stadiums already have such an installation. The gain of the uplink CoMP in throughput is shown in Figure 13.29, which illustrates the total uplink throughput with and without CRAN. The gain is more than 100% both with open-loop and with closed-loop power control. The uplink CoMP needs no support from the UEs. Actually, the UEs do not even know that uplink CoMP is being utilized. Theref