lt is that for the given throughput targets, path loss imbalance is 10 dB in favour of downlink. This implies that the mobility threshold design will most likely have to be based on uplink performance. Moreover, it can be already seen that RSRP should not be less than about -115 dBm since this is the RSRP level below which a noise-limited system cannot meet the uplink throughput requirement due to path loss. the downlink transmission power was higher or RS power boosting was used, the imbalance would also increase correspondingly. With the given uplink throughput target PUCCH does not limit the coverage. Recall that for simplicity the term 'path loss' is in this chapter used in the 3GPP sense, that is, reference signal power per subcarrier minus RSRP. Thus it includes antenna system gain. LTE Small Cell Optimization Layer RSRP Exit Point for Network with Interference As was seen, in the noise-limited case RSRP can be used as the mobility trigger since it can be converted to SINR in a straightforward way. For the case with other cell interference a similar approach can be used for the uplink, if the average uplink noise rise is taken into account. For downlink, the situation is more complicated since the downlink noise rise depends on the location of the UE relative to the interfering eNodeBs; near the cell centre downlink noise rise is much lower than at cell edge. For this reason the mapping of RSRP to SINR will depend not only on network load, but on the RSRP level itself (user location in the cell). If a curve similar to Figure 15.10 is available, RSRP threshold configuration could in principle be based on that. However, the drawback of such an RSRP versus SINR mapping is that it presents the behaviour under a static network load whereas in reality the RF utilization of cells in the network fluctuates constantly. RSRQ in turn can track the dynamic load fluctuations, but on the other hand it necessitates long time to trigger to avoid unnecessary cell changes. In some cases, such as high-rise buildings and cells