Observed time difference of arrival angle of arrival discriminator
View Patent ↗A method, user equipment (UE) and location server for estimating position of a UE based on observed angles of arrival. According to one embodiment, angles of arrival of signals from a plurality of base stations are received by a UE are observed by scanning for position reference signals (PRS) by adjusting a phase difference between antennas to cause a null of a beam of the UE to be incremented through an angular sector. For each of a plurality of base stations, an angle of arrival at which the null is steered when a PRS is suppressed by the null and a reference signal time difference, RSTD, are determined. Each angle of arrival and corresponding RSTD is transmitted to a location server which estimates UE position based on the observed angles of arrival. Further, the location server may instruct the UE to suppress a non-line-of-sight PRS signal.
1. A method, performed by a location server, of estimating a position of a user equipment (UE) in a wireless communication system, the method comprising:
receiving from the UE:
a plurality of reference signal time differences (RSTDs), the plurality of RSTDs being based on a plurality of distinct position reference signals (PRSs), respectively, wherein the plurality of distinct PRSs are received by the UE from a plurality of base stations, respectively; and
a plurality of observed angles of arrival (AOAs), each of the plurality of observed AOAs corresponding to a different one of the plurality of RSTDs;
determining a first estimated position of the UE using multilateration, based on the plurality of RSTDs and known locations of the plurality of base stations;
performing a weighting process to the plurality of RSTDs, the weighting process comprising:
determining an estimated AOA for a first RSTD of the plurality of RSTDs based on the first estimated position of the UE and the known locations of the plurality of base stations;
comparing the observed AOA corresponding to the first RSTD to the estimated AOA; and
assigning a weight to the first RSTD, a magnitude of the assigned weight being inversely proportional to a difference between the estimated AOA and the observed AOA corresponding to the first RSTD; and
determining a second estimated position of the UE based on at least three weighted received RSTDs having highest weights and the known locations of the plurality of base stations.
2. The method of claim 1 , wherein the weighted first RSTD corresponds to a line-of-sight angle of arrival.
3. The method of claim 1 , further comprising
sending an instruction to the UE to suppress, a particular PRS arriving at an observed angle of arrival, based on a determination that the particular PRS corresponds to an observed angle of arrival that differs from its corresponding estimated angle of arrival by more than a threshold.