Method for executing RSTD measurement-related operation in wireless communication system
An embodiment of the present invention relates to a method for executing a reference signal time difference measurement (RSTD) measurement-related operation by a terminal in a wireless communication system, which is a measurement-related operation executing method comprising the steps of: receiving RSTD measurement information from two or more helper UEs (H-UEs); using the received RSTD measurement information to correct the RSTD measurement information measured by the terminal; and transmitting the corrected RSTD measurement information to a base station.
1. A method of, at a user equipment (UE), correcting a reference signal time difference (RSTD) measurement operation in a wireless communication system, the method comprising:
measuring, by the UE, first RSTD measurement information based on a positioning reference signal (PRS);
receiving second RSTD measurement information measured by H-UEs (helper UEs) from the H-UEs;
correcting the first RSTD measurement information using the received second RSTD measurement information; and
transmitting the corrected first RSTD measurement information to a base station,
wherein the correcting of the first RSTD measurement information is performed using a weighted average of the first RSTD measurement information measured by the UE and the received second RSTD measurement information, and
wherein, upon obtaining the weighted average, a weighted factor of an i-th UE is sqrt(RSTD quality_i)/sum(sqrt(RSTD quality_i)).
2. The method according to claim 1 , wherein the correcting of the first RSTD measurement information is performed using only vertical location information of the second RSTD measurement information from the H-UEs.
3. The method according to claim 1 , wherein the UE receives the second RSTD measurement information from the H-UEs through a discovery signal.
4. The method according to claim 1 , wherein the H-UEs are selected by the UE from among PH-UEs (potential helper UEs) discovered in a device-to-device (D2D) discovery process.
5. The method according to claim 4 , wherein the H-UEs have signal strengths equal to or greater than a predetermined level among the PH-UEs discovered in the D2D discovery process.
6. The method according to claim 4 , wherein the H-UEs are located at distances of a predetermined value or less among the PH-UEs discovered in the D2D discovery process.
7. The method according to claim 1 , wherein the H-UEs are selected by a network from among PH-UEs (potential helper UEs) based on device-to-device (D2D) discovery information reported by the UE.
8. The method according to claim 7 , wherein the H-UEs are UEs whose expected RSTD uncertainty is a predetermined value or less among the PH-UEs.
9. A user equipment (UE) device for correcting a reference signal time difference (RSTD) measurement operation in a wireless communication system, the UE device comprising:
a transmission module and a reception module; and
a processor configured to control the transmission module and the reception module,
wherein the processor measures first RSTD measurement information based on a positioning reference signal (PRS), receives second RSTD measurement information measured by H-UEs (helper UEs) from the H-UEs, corrects the first RSTD measurement information using the received second RSTD measurement information, and transmits the corrected first RSTD measurement information to a base station,
wherein the correcting of the first RSTD measurement information is performed using a weighted average of the first RSTD measurement information measured by the UE device and the received second RSTD measurement information, and
wherein, upon obtaining the weighted average, a weighted factor of an i-th UE is sqrt(RSTD quality_i)/sum(sqrt(RSTD quality_i)).