ample #2 (Equal Priority Equal Bandwidth LTE Layers) The case where LTE carrier frequencies are assigned to high- and low-priority layers has one major shortcoming. While UE is always being served by the highest priority layer satisfying the minimum required RSRP/RSRQ, this does not guarantee that it receives the best available service level since there could be a strong good quality cell available on a lower priority layer. If both layers have the same system bandwidth and their path loss difference is not large (e.g. 1.8 GHz VS. 2.1 GHz), a more suitable approach may be to assign them the same priority, which leads to a different design of mobility parameters based on classical best server-based serving cell selection. Figure 15.15 sets the background for this section. Both LTE layers have the same system bandwidth and the path loss difference between the 1.8 GHz and 2.6 GHz carrier frequencies is about 3 dB. In this case assigning different priorities to the layers may not produce any benefit but a simple equal priority layering scheme may be sufficient and be easier to operate and optimize. In the baseline case with low network load, the mobility is based simply on the best server selection with some hysteresis, that is, A3 offset and idle mode hysteresis. There is no need to define any exit or entry point parameters for intra-LTE mobility. For moving to the UMTS LTE2600 20 MHz layer, priority = 5 LTE entry point LTE1800 20 MHz layer, priority = 5 LTE exit point Hysteresis UMTS900 layer, priority = 2 Loss of network service Figure 15.15 Network with two equal priority LTE layers Inter-layer Mobility Optimization coverage layer an exit and an entry point are still needed since different RATs cannot have the same priority. This can be based on the minimum service-level requirement discussed earlier, for example, for 2 Mbps uplink throughput target RSRP should not be less than - 112 dBm (other assumptions as in the previous section). For intra-LTE mobility basically only hysteresis and timers need to be determin