on is used: Serving cell is LTE800 (priority 5). Neighbour LTE layers are LTE1800 (priority 7) and LTE2600 (priority 6). Neighbour UTRA layers are UMTS900 (priority 3) and UMTS2100 (priority 4). The received level and quality from serving cell is less than intra- and non-intra search thresholds. In other words, the UE will search all layers using expedited search schedule for the higher priority layers and will also search all lower priority layers. Idle mode DRX cycle is 1.28 seconds. It can be seen that in this case the UE searches for new intra-frequency cells once every 15.36 seconds (12 DRX cycles). Inter-layer cell search is done every 30.72 seconds (24 DRX cycles). The cells found in these searches are then added to the list of cells to measure. All LTE Small Cell Optimization LTE layers are measured once every DRX cycle. UTRA FDD layers on the other hand are measured at the interval of four DRX cycles. The nominal requirement for the inter-layer search of LTE cells is 20 DRX cycles. Since there are two LTE layers, the UE should search each layer at least once every 40 DRX cycles. It can be seen that the UE in this case searches both layers once every 24 DRX cycles, and hence performs better than required by the specification. Assuming a single layer the LTE inter-frequency cell detection time requirement for the 1.28-second DRX cycle is 32 seconds from Table 15.5 and since there are two such layers the detection time requirement in this case is 64 seconds. Since the UE searches both inter-frequency lay- ers at a period of 30.72 seconds this leaves ample time to make measurements and eval- uate the cell reselection criteria. The same applies for UTRA FDD layers for which the detection time requirement is 30 seconds multiplied by the number of layers (60 seconds in this case). So far only the steps leading to cell reselection decision in the source cell have been discussed. Successful camping in the new cell still requires reading all SIBs (unless pre-stored in UE memory), and possibly a successful Tracking