ed occurs in the first subframe Occasion duration 1-5 ms to UE of DRS Occasion PSS / SSS CRS / CSI- RS UE : DMTC DMTC (gap) duration configuration DMTC periodicity is fixed to 6 ms configurable (40, 80, 160 ms supported) DMTC offset configurable (i.e. relative position) Figure 4.11 The structure of discovery deference signals and the related measurement timing in ordinary LTE operation. Additionally, a DRS Occasion may comprise of transmission of several CSI-RS resources, each typically corresponding to a transmission point. In other words, DRS occasion can be seen as a snapshot of an ordinary LTE transmission on an unloaded carrier. The UE performs discovery measurements according to eNodeB-given per-carrier Discov- ery Measurement Timing Configuration (DMTC). The DMTC indicates the time instances when the UE may assume DRS to be present for a carrier, a bit similar to measurement gap configuration used for inter-frequency RRM measurements. A DMTC occasion has a fixed duration of 6 ms and a configurable periodicity of 40, 80 or 160 ms. The network needs to ensure that the transmission times of DRS occasions of all cells on a given carrier frequency are aligned with the DMTC configuration in order to ensure those cells can be discovered. Hence, the network needs to be synchronized with the accuracy of approximately one sub-frame (or better) for the discovery procedure to work. Network may also not configure a UE to use DRS occasions for the DMTC. The DRS-based UE measurements differ slightly from legacy measurements. The UE may only assume presence of CRS/CSI-RS only during the DMTC. The DRS-based CRS (RSRP/RSRQ) measurements are done as in legacy LTE. This means the same measurement events (i.e. events A1-A6) are also applicable and all legacy options (e.g. cell-specific offsets) can be utilized. For the DRS-based CSI-RS measurements, only CSI-RS-based RSRP is supported. The network also explicitly configures the CSI-RS resources that the UE measures, and UE only triggers measurement reports for those CSI-RS res