Question: In DL-TDOA (Downlink Time Difference of Arrival) positioning for User Equipment (UE) in NG-RAN, which of the following measurements is mandatorily utilized by the UE to determine its location relative to neighboring Transmitter Positions (TPs)?
Option 1: DL-PRS-RSRP (Downlink Positioning Reference Signal Received Power)
Option 2: DL-RSCPD (Downlink Reference Signal Carrier to Noise, Power Density, and other optional parameters)
Option 3: DL RSTD (Downlink Reference Signal Time Difference)
Option 4: CSI-RS (Channel State Information Reference Signal) measurements
Explanation: The correct answer is DL RSTD because the DL-TDOA positioning method fundamentally relies on measuring the time difference of arrival of downlink signals from multiple TPs to calculate the UE's location. While DL-PRS-RSRP, DL-PRS-RSRPP, and DL-RSCPD are optionally utilized to enhance positioning accuracy or provide additional data, the DL RSTD is the mandatory measurement for the basic operation of DL-TDOA positioning, as it directly relates to the time difference of arrival principle.