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edge LTE-Advanced UEs are assigned to only one CC, which results in the same coverage andperformance compared with Rel-8 UEs.Figure 11. 5-Percentile Cell Edge User Throughput under Different Traffic Loads in Different Scenarios.Figure 12 shows the average user throughput versus the offered load in different scenarios. The averageuser throughput for LTE-Advanced UEs can always achieve better performance than Rel-8 UEsregardless of the setting of power back-off. In one possible CC selection algorithm, power-limited LTE-Advanced UEs are assigned to one CC and therefore will not experience any loss from being scheduledover multiple CCs. Meanwhile LTE-Advanced UEs not operating close to their maximum transmissionpower are assigned to both CCs so that they can benefit from CA’s advantages. The gain is high in lowload but decreases as the offered load increases.For example, the average throughput gain with CA is 64 percent in low load (62 percent PRB utilization)and 41 percent in high load (98 percent PRB utilization) for the case of Pbackoff = 4 dB. The PRButilization versus the offered load is depicted in Figure 13. For a given offered load, the averagethroughput of LTE-Advanced UEs decreases with the increase of power back-off. This is because the ULis power limited. The increase of power back-off will cause further reduction of the maximum UEtransmission power, which results in a decreasing probability of being assigned to multiple CCs for LTE-Advanced UEs.4G Americas LTE Carrier Aggregation October 2014 27