BR-112020001354-B1 - METHOD, IN A FIRST BASE STATION, TO SUPPORT POSITIONING OF A MOBILE DEVICE AND FIRST BASE STATION TO SUPPORT POSITIONING OF A MOBILE DEVICE

Abstract

Techniques are provided for positioning a mobile device in an unwired network using directional positional reference signals (PRSs), also referred to as a PRS beamforming. In an illustrative method, several directional PRSs (S1, S2) are generated for at least one cell for a base station (410), such that each of the several directional PRSs comprises at least one signal characteristic and a transmission direction, either or both being distinct or unique. The several directional PRSs are transmitted within at least one cell, such that each of the several directional PRSs is transmitted in the transmission direction. A mobile device (420) can acquire and measure at least one of the directional PRSs, which can be identified using the associated signal characteristic. The measurement can be used to assist positioning methods such as OTDOA and ECID and mitigate multipath.

Inventors

• STEPHEN WILLIAM EDGE
• Sven Fischer
• Rayman Pon

Assignees

• QUALCOMM INCORPORATED

Dates

Publication Date

20260317

Application Date

20180627

Priority Date

20180110

Claims (13)

1. 1. Method, at a first base station, for supporting positioning of a mobile device (420), the method characterized by comprising: generating a plurality of directional positioning reference signals, PRSs, for at least one cell to the first base station (410), wherein, to direct the mobile device (420) to measure at least one first directional PRS and not measure at least one second directional PRS from the plurality of PRSs, because the at least one second directional PRS is not expected to be transmitted in the direction of a line of sight between the first base station (410) and the mobile device (420), each of the plurality of directional PRSs comprises at least one signal characteristic and one transmission direction, wherein the at least one signal characteristic and the transmission direction for each of the plurality of directional PRSs are unique to any other directional PRS transmitted by the first base station (410) and other base stations near the first base station (410); and transmit each of the plurality of directional PRSs within at least one cell, wherein each of the plurality of directional PRSs is transmitted in its transmission direction; obtain at least one round-trip time measurement, RTT, from the mobile device (420) for at least one first directional PRS transmitted from the first base station; and obtain a position of the mobile device (420) based, at least in part, on at least one transmission direction and at least one RTT measurement for at least one directional PRS.
2. 2. A method according to claim 1, characterized in that at least one signal feature comprises a frequency, a frequency shift, a code sequence, a muting pattern, a transmission time, or any combination thereof.
3. 3. Method, according to claim 1, characterized by transmitting the plurality of directional PRSs within at least one cell comprising: directing the plurality of directional PRSs through a controllable antenna array configured to perform beamforming of each directional PRS in the transmission direction.
4. 4. Method according to claim 3, characterized in that the transmission direction comprises a continuous range of horizontal angles, a continuous range of vertical angles, or a combination thereof.
5. 5. Method, according to claim 1, characterized in that at least one first directional PRS is detectable by the mobile device (420) to facilitate location determination of the mobile device (420) on a location-capable device based on an observed time difference of arrival position method, OTDOA, a departure angle position method, AOD, or an enhanced cell ID position method, ECID, or any combination thereof.
6. 6. Method according to claim 5, characterized in that at least one first directional PRS is detectable by the mobile device (420) based on the transmission direction to the at least one first directional PRS, on at least one signal characteristic to the at least one first directional PRS, or on any combination thereof.
7. 7. Method according to claim 6, characterized by further comprising: sending at least one of the transmission directions to at least one first directional PRS or at least one signal feature to at least one first directional PRS to the mobile device (420).
8. 8. Method, according to claim 7, characterized in that the transmission is optionally based on broadcast within at least one cell.
9. 9. Method according to claim 5, characterized in that the determination of the location of the mobile device (420) in the location-capable device includes the determination of the presence or absence of multipath for at least one first or second directional PRS based on the transmission direction for at least one first or second directional PRS and an approximate location for the mobile device (420), wherein the determination of the location of the mobile device (420) in the location-capable device is based, at least in part, on the presence or absence of determined multipath.
10. 10. Method according to claim 9, characterized in that the approximate location for the mobile device (420) is based, at least in part, on a server cell for the mobile device (420).
11. 11. Method according to claim 5, characterized in that the location-capable device comprises the mobile device (420), a Location Management Function, LMF, or a second base station other than the first base station (410), and in which the method further comprises: sending the transmission direction to at least one first directional PRS to the location-capable device.
12. 12. Method according to claim 1, characterized in that at least one cell is a service cell for the mobile device (420).
13. 13. First base station to support positioning of a mobile device (420), characterized by being configured to perform the steps of the methods as defined in any of claims 1 to 12 to support positioning of the mobile device (420).

Description

BACKGROUND [0001] Obtaining the location or position of a mobile device accessing a wireless network can be useful for various applications, including, for example, emergency calls, personal navigation, asset tracking, locating a friend or family member, etc. Existing positioning methods include methods based on measuring radio signals transmitted from various devices, including satellite vehicles (SVs) and terrestrial radio sources on a wireless network, such as base stations and access points. In methods based on terrestrial radio sources, a mobile device can measure the timing of signals received from two or more base stations and determine arrival times, arrival time differences, and/or receive time-transmission differences. Combining these measurements with known locations for the base stations and known transmission times from each base station can allow mobile device location using such positioning methods as Observed Time of Arrival Difference (OTDOA) or Enhanced Cell ID (ECID). [0002] To further assist in determining location (e.g., for OTDOA), Positioning Reference Signals (PRS) can be transmitted by base stations to increase measurement accuracy and the number of different base stations from which timing measurements can be obtained by a mobile device. However, location accuracy can be compromised by several factors, including errors, imprecision in location measurements, and multipath effects, where a PRS signal can be reflected, refracted, or scattered by intervening obstacles such as trees, walls, buildings, and traffic. Methods and techniques to mitigate or overcome these factors can therefore be beneficial. SUMMARY [0003] An example of a method, at a first base station, to support the positioning of a mobile device, according to the disclosure, includes generating several directional positioning reference signals (PRSs) for at least one cell for the base station, such that each of the several directional PRSs comprises at least one signal characteristic and a transmission direction, and transmitting each of the several directional PRSs within at least one cell, such that each of the several directional PRSs is transmitted in the transmission direction. [0004] Implementations of such a method may include one or more of the following features. At least one signal feature may include a frequency, a frequency offset, a code sequence, a muting pattern, a transmission time, or any combination thereof. Transmitting the various directional PRSs within at least one cell may include directing the various directional PRSs through a controllable antenna array configured to beamform each directional PRS in the transmission direction. The transmission direction may include a continuous range of horizontal angles, a continuous range of vertical angles, or a combination thereof. At least one of the various directional PRSs may be detectable by the mobile device to facilitate the determination of the mobile device's location on a location-capable device based on an observed time-of-arrival difference (OTDOA) position method, an angle-of-departure (AOD) position method, or an Enhanced Cell ID (ECID) position method, or any combination thereof. At least one of several directional PRSs may be detectable by the mobile device based on the transmission direction for at least one of several directional PRSs, at least one signal characteristic for at least one of several directional PRSs, or a combination thereof. The method may additionally include sending at least one of the transmission directions for at least one of several directional PRSs or at least one signal characteristic for at least one of several directional PRSs to the mobile device. The transmission may be broadcast-based within at least one cell. Location determination on the location-capable device may include determining the presence or absence of multipath for at least one of several directional PRSs based on a transmission direction for at least one of several directional PRSs and an approximate location for the mobile device, such that the determination of the mobile device's location on the location-capable device is based, at least in part, on the determined presence or absence of multipath. The approximate location for the mobile device may be based, at least in part, on a server cell for the mobile device. The location-capable device may include a second base station different from the first base station, the mobile device, or a Location Management Function (LMF), and the method may additionally include sending the transmission direction to at least one of several directional PRSs for the location-capable device. At least one cell may be a server cell for the mobile device. At least one of the signal characteristics and the transmission direction for each of the several directional PRSs may be unique. [0005] An example of a method, in a mobile device, for supporting the positioning of the mobile device, according to the disclosure includes r