阅读说明：本技术 用于定位目的的简化蜂窝小区位置信息共享 (Simplified cell location information sharing for positioning purposes ) 是由 A·马诺拉克斯 S·阿卡拉卡兰 J·B·索里亚加 骆涛 T·季 N·布衫 于 2019-09-05 设计创作，主要内容包括：公开了用于确定用户装备(UE)的定位的技术。在一方面,该UE从多个蜂窝小区接收多个定位参考信号(PRS)。该UE确定该多个PRS的多个抵达时间(TOA),并且基于该多个PRS来修剪该多个TOA。该UE随后从经修剪的TOA推导出抵达时间差(TDOA)向量。该TDOA向量包括多个蜂窝小区的多个与TOA相关的测量。该UE修剪这些TOA,以使得在该TDOA向量中表示的蜂窝小区在地理上足够分散以至少在2D中确定UE的定位。(Techniques for determining a location of a User Equipment (UE) are disclosed. In an aspect, the UE receives a plurality of Positioning Reference Signals (PRSs) from a plurality of cells. The UE determines a plurality of times of arrival (TOAs) of the plurality of PRSs and prunes the plurality of TOAs based on the plurality of PRSs. The UE then derives a time difference of arrival (TDOA) vector from the clipped TOAs. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells. The UE prunes the TOAs such that the cells represented in the TDOA vector are geographically dispersed enough to determine the location of the UE in at least 2D.)

1. A method of a User Equipment (UE), comprising:

receiving a plurality of Positioning Reference Signals (PRSs) from a plurality of cells,

the plurality of cells are grouped into one or more cell groups, each cell group including one or more member cells, each member cell being one of the plurality of cells,

each cell group is associated with a set of attributes including one or more attributes,

for each cell group, all member cells have all attributes of the associated set of attributes in common,

the plurality of PRSs includes a plurality of PRS IDs, and

for each cell group, the PRS ID of each member cell indicates the membership of that member cell in that cell group;

detecting a plurality of times of arrival (TOA) of the plurality of PRSs;

deriving a time difference of arrival (TDOA) vector from the plurality of TOAs; and

transmitting the TDOA vector to a network entity,

wherein the TDOA vector comprises a plurality of TOA-related measurements for a plurality of cells.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

wherein each cell associated with the TOA measurements in the TDOA vector is a cell of the plurality of cells, and

wherein the plurality of TOA-related measurements of the plurality of cells included in the TDOA vector are sufficient to determine a location of the UE in at least 2D.

3. The method of claim 1, wherein for each cell group, all attributes of the associated set of attributes are relative attributes.

4. The method of claim 1, further comprising:

pruning the plurality of TOAs based on the plurality of PRSs,

wherein the TDOA vector is derived from the clipped TOAs.

5. The method of claim 4, wherein pruning the plurality of TOAs comprises:

ranking the TOAs based on one or more quality metrics; and

prune the sorted TOAs.

6. The method of claim 4, wherein for at least one cell group, at least one attribute of the associated set of attributes is one of:

a co-location attribute indicating that all member cells of the at least one cell group are co-located,

a row attribute indicating that all member cells of the at least one cell group are in a row, an

A region boundary attribute indicating that all member cells of the at least one cell group are within a threshold region boundary.

7. The method of claim 6 wherein the plurality of TOAs are clipped such that the TDOA vector represents any one or more of:

at least three cells having different co-location properties,

at least two cells having different row attributes, an

At least two cells having different area boundary properties.

8. The method of claim 4, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

wherein the plurality of TOA-related measurements of the plurality of cells included in the TDOA vector are sufficient to determine a location of the UE in 3D, and

wherein for at least one cell group, at least one attribute of the associated set of attributes is one of:

an altitude attribute indicating altitudes of all member cells of the at least one cell group within a threshold altitude difference of each other, and

a plane attribute indicating that all member cells of the at least one cell group are on a 2D plane.

9. The method of claim 8 wherein the plurality of TOAs are clipped such that the TDOA vector represents one or both of:

at least two cells having different altitude attributes, an

At least two cells having different planar properties.

10. The method of claim 8, wherein the heights of the member cells of one cell group differ from the heights of the member cells of another cell group by at least a minimum group height difference.

11. The method of claim 1, wherein the plurality of PRS IDs comprises a plurality of scrambling IDs, each scrambling ID corresponding to one of the plurality of cells.

12. The method of claim 11, wherein the step of selecting the target,

wherein the bits of each scrambling ID are divided into one or more attribute bit ranges, each attribute bit range comprising one or more bits, each attribute bit range mapped to an attribute type of the one or more attribute types,

wherein for each cell, each attribute of that cell is encoded in the attribute bit range of the attribute type mapped to that attribute in the scrambling ID, and

wherein the method further comprises:

receiving scrambling ID information from the network entity, the scrambling ID information specifying a mapping between the one or more attribute bit ranges and the one or more attribute types.

13. The method of claim 1, wherein the plurality of PRS IDs comprises a plurality of resource IDs, each resource ID corresponding to one of the plurality of cells.

14. The method of claim 13, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

wherein the plurality of resource IDs are grouped into one or more resource ID groups, each resource ID group corresponding to a cell group of the one or more cell groups, an

Wherein the method further comprises one or both of:

retrieving default resource ID group information configured within the UE, the default resource ID group information identifying the one or more resource ID groups; and

receiving resource ID group information from the network entity, the resource ID group information identifying the one or more resource ID groups.

15. A method of a network entity, comprising:

configuring a plurality of cells to transmit a plurality of Positioning Reference Signals (PRSs) to a User Equipment (UE), the plurality of cells being grouped into one or more cell groups, each cell group comprising one or more member cells, each member cell being one of the plurality of cells, each cell group being associated with a set of attributes comprising one or more attributes, for each cell group all member cells having in common all attributes of the associated set of attributes, the plurality of PRSs comprising a plurality of PRS IDs, and for each cell group the PRS ID of each member cell indicating membership of that member cell in that cell group;

receiving a time difference of arrival (TDOA) vector from the UE; and

determining a location of the UE based on the TDOA vector,

wherein the TDOA vector comprises a plurality of TOA-related measurements for a plurality of cells,

wherein each cell associated with the TOA measurements in the TDOA vector is a cell of the plurality of cells, and

wherein the plurality of TOA-related measurements of the plurality of cells included in the TDOA vector are sufficient to determine a location of the UE in at least 2D.

16. The method of claim 15, wherein for each cell group, all attributes of the associated set of attributes are relative attributes.

17. The method of claim 15, wherein for at least one cell group, at least one attribute of the associated set of attributes is one of:

a co-location attribute indicating that all member cells of the at least one cell group are co-located,

a row attribute indicating that all member cells of the at least one cell group are in a row, an

A region boundary attribute indicating that all member cells of the at least one cell group are within a threshold region boundary.

18. The method of claim 17, wherein the step of selecting the target,

wherein the plurality of TOA-related measurements of the plurality of cells included in the TDOA vector are sufficient to determine a location of the UE in 3D, and

wherein for at least one cell group, at least one attribute of the associated set of attributes is one of:

an altitude attribute indicating altitudes of all member cells of the at least one cell group within a threshold altitude difference of each other, and

a plane attribute indicating that all member cells of the at least one cell group are on a 2D plane.

19. The method of claim 18, wherein the heights of the member cells of one cell group differ from the heights of the member cells of another cell group by at least a minimum group height difference.

20. The method of claim 15, wherein the plurality of PRS IDs comprises a plurality of scrambling IDs, each scrambling ID corresponding to one of the plurality of cells.

21. The method of claim 20, wherein the step of selecting the target,

wherein the bits of each scrambling ID are divided into one or more attribute bit ranges, each attribute bit range comprising one or more bits, each attribute bit range mapped to an attribute type of the one or more attribute types,

wherein for each cell, each attribute of that cell is encoded in the attribute bit range of the attribute type mapped to that attribute in the scrambling ID, and

wherein the method further comprises:

transmitting scrambling ID information to the UE, the scrambling ID information specifying a mapping between the one or more attribute bit ranges and the one or more attribute types.

22. The method of claim 15, wherein the plurality of PRS IDs comprises a plurality of resource IDs, each resource ID corresponding to one of the plurality of cells.

23. The method of claim 22, wherein the step of,

wherein the plurality of resource IDs are grouped into one or more resource ID groups, each resource ID group corresponding to a cell group of the one or more cell groups, an

Wherein the method further comprises:

transmitting resource ID group information to the UE, the resource ID group information identifying the one or more resource ID groups.

24. The method of claim 22, wherein the plurality of resource IDs are ordered such that, between any pair comprising a first cell group and a second cell group, the resource IDs of all member cells of the first cell group are less than the resource IDs of all member cells of the second cell group.

25. A User Equipment (UE), comprising:

a memory;

a transceiver; and

a processor coupled to the memory and the transceiver,

wherein the processor, the memory, and the transceiver are configured to:

receiving a plurality of Positioning Reference Signals (PRSs) from a plurality of cells, the plurality of cells being grouped into one or more cell groups, each cell group comprising one or more member cells, each member cell being one of the plurality of cells, each cell group being associated with a set of attributes comprising one or more attributes, for each cell group all member cells collectively having all attributes of the associated set of attributes, the plurality of PRSs comprising a plurality of PRS IDs, and for each cell group the PRS ID of each member cell indicating membership of that member cell in that cell group;

detecting a plurality of times of arrival (TOA) of the plurality of PRSs;

deriving a time difference of arrival (TDOA) vector from the plurality of TOAs; and

transmitting the TDOA vector to a network entity, an

Wherein the TDOA vector comprises a plurality of TOA-related measurements for a plurality of cells.

26. The UE according to claim 25, wherein the UE is further adapted to,

wherein the processor, the memory, and the transceiver are further configured to prune the plurality of TOAs based on the plurality of PRSs, and

wherein the TDOA vector is derived from the clipped TOAs.

27. The UE according to claim 26, wherein the UE is further adapted to,

wherein for at least one cell group, at least one attribute of the associated set of attributes is one of:

a co-location attribute indicating that all member cells of the at least one cell group are co-located,

a row attribute indicating that all member cells of the at least one cell group are in a row, an

A region boundary attribute indicating that all member cells of the at least one cell group are within a threshold region boundary, and

wherein the processor, the memory, and the transceiver are further configured to prune the plurality of TOAs such that the TDOA vector represents any one or more of:

at least three cells having different co-location properties,

at least two cells having different row attributes, an

At least two cells having different area boundary properties.

28. A network entity, comprising:

a memory;

a transceiver; and

a processor coupled to the memory and the transceiver,

wherein the processor, the memory, and the transceiver are configured to:

configuring a plurality of cells to transmit a plurality of Positioning Reference Signals (PRSs) to a User Equipment (UE), the plurality of cells being grouped into one or more cell groups, each cell group comprising one or more member cells, each member cell being one of the plurality of cells, each cell group being associated with a set of attributes comprising one or more attributes, for each cell group all member cells having in common all attributes of the associated set of attributes, the plurality of PRSs comprising a plurality of PRS IDs, and for each cell group the PRS ID of each member cell indicating membership of that member cell in that cell group;

receiving a time difference of arrival (TDOA) vector from the UE; and

determining a location of the UE based on the TDOA vector,

wherein the TDOA vector comprises a plurality of TOA-related measurements for a plurality of cells,

wherein each cell associated with the TOA measurements in the TDOA vector is a cell of the plurality of cells, and

wherein the plurality of TOA-related measurements of the plurality of cells included in the TDOA vector are sufficient to determine a location of the UE in at least 2D.

29. The network entity of claim 28, wherein for at least one cell group, at least one attribute of the associated set of attributes is one of:

a co-location attribute indicating that all member cells of the at least one cell group are co-located,

a row attribute indicating that all member cells of the at least one cell group are in a row, an

A region boundary attribute indicating that all member cells of the at least one cell group are within a threshold region boundary.

30. The network entity of claim 28, wherein,

wherein the plurality of TOA-related measurements of the plurality of cells included in the TDOA vector are sufficient to determine a location of the UE in 3D, and

wherein for at least one cell group, at least one attribute of the associated set of attributes is one of:

an altitude attribute indicating altitudes of all member cells of the at least one cell group within a threshold altitude difference of each other, and

a plane attribute indicating that all member cells of the at least one cell group are on a 2D plane.

Technical Field

Various aspects described herein relate generally to wireless communication systems, and more particularly, to simplified cell location information sharing for positioning purposes.

Background

Wireless communication systems have evolved over several generations, including first generation analog wireless telephone service (1G), second generation (2G) digital wireless telephone service (including transitional 2.5G and 2.75G networks), third generation (3G) internet-capable high-speed data wireless service, and fourth generation (4G) service (e.g., Long Term Evolution (LTE) or WiMax). There are many different types of wireless communication systems in use today, including cellular and Personal Communication Services (PCS) systems. Examples of known cellular systems include the cellular analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), global system for mobile access (GSM) TDMA variants, and the like.

Fifth generation (5G) mobile standards require higher data transfer speeds, a greater number of connections and better coverage, among other improvements. According to the next generation mobile network alliance, the 5G standard is designed to provide data rates of tens of megabits per second to each of thousands of users, and 1 gigabit per second to tens of employees on an office floor. Hundreds of thousands of simultaneous connections should be supported to support large sensor deployments. Therefore, the spectral efficiency of 5G mobile communication should be significantly improved compared to the current 4G standard. Furthermore, the signaling efficiency should be improved and the latency should be reduced substantially compared to the current standard.

Some wireless communication networks, such as 5G, support operation at very high frequency and even Extremely High Frequency (EHF) bands, such as the millimeter wave (mmW) band (in general, wavelengths of 1mm to 10mm, or 30GHz to 300 GHz). These very high frequencies can support very high throughput, such as up to six gigabits per second (Gbps). However, one of the challenges in wireless communication at very high or very high frequencies is that significant propagation losses may occur due to the high frequencies. As the frequency increases, the wavelength may decrease and the propagation loss may also increase. At the mmW band, propagation loss may be severe. For example, the propagation loss may be on the order of 22 to 27dB relative to that observed in the 2.4GHz or 5GHz bands.

Propagation loss is also a problem in multiple-input multiple-output (MIMO) and massive MIMO systems in any frequency band. The term MIMO as used herein will generally refer to both MIMO and massive MIMO. MIMO is a method for multiplying the capacity of a radio link by using multiple transmit and receive antennas to exploit multipath propagation. Multipath propagation occurs because Radio Frequency (RF) signals travel not only along the shortest path between the transmitting and receiving parties, which may be a line of sight (LOS) path, but also on several other paths, as these RF signals spread away from the transmitting party and are reflected by other objects (such as hills, buildings, water, etc.) on their way to the receiving party. A transmitting party in a MIMO system includes multiple antennas and exploits multipath propagation by orienting the antennas to each transmit the same RF signal on the same radio channel to a receiving party. The receiving party is also equipped with multiple antennas tuned to the radio channel, which can detect the RF signals transmitted by the transmitting party. When the RF signals reach the receiving party (some of the RF signals may be delayed due to multipath propagation), the receiving party may combine them into a single RF signal. Propagation loss is also a problem in MIMO systems because the transmitter transmits each RF signal at a lower power level than would otherwise be transmitted for a single RF signal.

To address propagation loss issues in mmW band systems and MIMO systems, the transmitting side may use beamforming to extend the RF signal coverage. In particular, transmit beamforming is a technique for transmitting an RF signal in a specific direction, and receive beamforming is a technique for improving the reception sensitivity of an RF signal arriving at a receiving side in a specific direction. Transmit beamforming and receive beamforming may be used in conjunction with or separately from each other, and references to "beamforming" may refer hereinafter to transmit beamforming, receive beamforming, or both. Conventionally, when a transmitting side broadcasts an RF signal, it broadcasts the RF signal in almost all directions determined by a fixed antenna pattern or an antenna radiation pattern. With beamforming, the transmitting party determines where a given receiving party is located relative to the transmitting party and projects a stronger downlink RF signal in that particular direction, thereby providing the receiving party with a faster (in terms of data rate) and stronger RF signal. In order to change the directivity of the RF signal at the time of transmission, the transmitting side may control the phase and relative amplitude of the RF signal broadcast by each antenna. For example, the transmitting party may use an antenna array (also referred to as a "phased array" or "antenna array") that produces beams of RF waves that can be "steered" to point in different directions without actually moving the antennas. Specifically, the RF currents are fed to the individual antennas in the correct phase relationship so that the radio waves from these separate antennas add together in the desired direction to increase radiation, while the radio waves from these separate antennas cancel in the undesired direction to suppress radiation.

To support position estimation in terrestrial wireless networks, a mobile device may be configured to measure and report observed time difference of arrival (OTDOA) or Reference Signal Timing Difference (RSTD) between reference RF signals received from two or more network nodes, e.g., different base stations or different transmission points (e.g., antennas) belonging to the same base station.

In case the transmitting party transmits RF signals using beamforming, the beam of interest for data communication between the transmitting party and the receiving party will be the beam carrying the RF signal with the highest received signal strength (or highest received signal to interference plus noise ratio (SINR), e.g. in case of directional interference signals). However, when the receiver relies on the beam with the highest received signal strength, the receiver's ability to perform certain tasks may be compromised. For example, in a scenario where the beam with the highest received signal strength travels on a longer than shortest path (i.e., LOS path or shortest non-LOS (NLOS) path), the RF signal may arrive later than the RF signal received on the shortest path due to propagation delays. Accordingly, if the receiving side is performing a task requiring accurate timing measurements and the beam with the highest received signal strength is affected by longer propagation delays, the beam with the highest received signal strength may not be optimal for the present task.

SUMMARY

The following presents a simplified summary in connection with one or more aspects disclosed herein. As such, the following summary should not be considered an extensive overview relating to all contemplated aspects, nor should the following summary be considered to identify key or critical elements relating to all contemplated aspects or to delineate the scope associated with any particular aspect. Accordingly, the sole purpose of the following summary is to present some concepts related to one or more aspects related to the mechanisms disclosed herein in a simplified form prior to the detailed description presented below.

An aspect relates to a method of a User Equipment (UE). The method includes receiving a plurality of Positioning Reference Signals (PRSs) from a plurality of cells. The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes. For each cell group, all member cells have all attributes of the associated set of attributes in common. The plurality of PRSs includes a plurality of PRS IDs. For each cell group, the PRS ID for each member cell indicates the membership of that member cell in that cell group. The method also includes detecting a plurality of times of arrival (TOAs) of the plurality of PRSs. The method further includes deriving a time difference of arrival (TDOA) vector from the plurality of TOAs and transmitting the TDOA vector to a network entity. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells.

One aspect relates to a method of a network entity. The method includes configuring a plurality of cells to transmit a plurality of Positioning Reference Signals (PRSs) to a User Equipment (UE). The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes. For each cell group, all member cells have all attributes of the associated set of attributes in common. The plurality of PRSs includes a plurality of PRS IDs. For each cell group, the PRS ID for each member cell indicates the membership of that member cell in that cell group. The method also includes receiving a time difference of arrival (TDOA) vector from the UE. The method further includes determining a location of the UE based on the TDOA vector. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells.

An aspect relates to a User Equipment (UE) that includes a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor, the memory, and the transceiver are configured to receive a plurality of Positioning Reference Signals (PRSs) from a plurality of cells. The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes. For each cell group, all member cells have all attributes of the associated set of attributes in common. The plurality of PRSs includes a plurality of PRS IDs. For each cell group, the PRS ID for each member cell indicates the membership of that member cell in that cell group. The processor, the memory, and the transceiver are further configured to detect a plurality of times of arrival (TOAs) of the plurality of PRSs. The processor, the memory, and the transceiver are further configured to derive a time difference of arrival (TDOA) vector from the plurality of TOAs. The processor, the memory, and the transceiver are yet further configured to transmit the TDOA vector to a network entity. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells.

One aspect relates to a network entity that includes a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor, the memory, and the transceiver are configured to configure a plurality of cells to transmit a plurality of Positioning Reference Signals (PRSs) to a User Equipment (UE). The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes. For each cell group, all member cells have all attributes of the associated set of attributes in common. The plurality of PRSs includes a plurality of PRS IDs. For each cell group, the PRS ID for each member cell indicates the membership of that member cell in that cell group. The processor, the memory, and the transceiver are also configured to receive a time difference of arrival (TDOA) vector from the UE. The processor, the memory, and the transceiver are further configured to determine a location of the UE based on the TDOA vector. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells.

An aspect relates to a User Equipment (UE). The UE includes means for receiving a plurality of Positioning Reference Signals (PRSs) from a plurality of cells. The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes. For each cell group, all member cells have all attributes of the associated set of attributes in common. The plurality of PRSs includes a plurality of PRS IDs. For each cell group, the PRS ID for each member cell indicates the membership of that member cell in that cell group. The UE also includes means for detecting a plurality of times of arrival (TOAs) of the plurality of PRSs. The UE further includes means for deriving a time difference of arrival (TDOA) vector from the plurality of TOAs, and means for transmitting the TDOA vector to a network entity. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells.

One aspect relates to a network entity. The network entity includes means for configuring a plurality of cells to transmit a plurality of Positioning Reference Signals (PRSs) to a User Equipment (UE). The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes. For each cell group, all member cells have all attributes of the associated set of attributes in common. The plurality of PRSs includes a plurality of PRS IDs. For each cell group, the PRS ID for each member cell indicates the membership of that member cell in that cell group. The network entity also includes means for receiving a time difference of arrival (TDOA) vector from the UE. The network entity further includes means for determining a location of the UE based on the TDOA vector. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells.

An aspect relates to a non-transitory computer-readable medium containing instructions stored thereon that are executable by a User Equipment (UE). The instructions cause the UE to receive a plurality of Positioning Reference Signals (PRSs) from a plurality of cells. The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes. For each cell group, all member cells have all attributes of the associated set of attributes in common. The plurality of PRSs includes a plurality of PRS IDs. For each cell group, the PRS ID for each member cell indicates the membership of that member cell in that cell group. The instructions also cause the UE to detect a plurality of times of arrival (TOAs) of the plurality of PRSs. The instructions further cause the UE to derive a time difference of arrival (TDOA) vector from the plurality of TOAs and send the TDOA vector to a network entity. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells.

An aspect relates to a non-transitory computer-readable medium comprising instructions stored thereon that are executable by a network entity. The instructions cause the network entity to configure a plurality of cells to transmit a plurality of Positioning Reference Signals (PRSs) to a User Equipment (UE). The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes. For each cell group, all member cells have all attributes of the associated set of attributes in common. The plurality of PRSs includes a plurality of PRS IDs. For each cell group, the PRS ID for each member cell indicates the membership of that member cell in that cell group. The instructions also cause the network entity to receive a time difference of arrival (TDOA) vector from the UE. The instructions further cause the network entity to determine a location of the UE based on the TDOA vector. The TDOA vector includes a plurality of TOA-related measurements for a plurality of cells.

Other objects and advantages associated with the aspects disclosed herein will be apparent to those skilled in the art based on the drawings and detailed description.

Brief Description of Drawings

A more complete appreciation of the various aspects described herein, and many of the attendant advantages thereof, will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, which are given by way of illustration only, and not by way of limitation, and wherein:

fig. 1 illustrates an example wireless communication system in accordance with various aspects;

fig. 2A and 2B illustrate example wireless network structures in accordance with various aspects;

fig. 3A illustrates an example base station and an example UE in an access network, in accordance with various aspects;

FIG. 3B illustrates an exemplary server in accordance with various aspects;

fig. 4 illustrates an example wireless communication system in accordance with various aspects;

fig. 5 illustrates an example wireless communication system in accordance with various aspects;

fig. 6A is a diagram illustrating RF channel response over time at a UE in accordance with various aspects of the present disclosure;

fig. 6B illustrates an exemplary separation of clusters at an angle of departure (AoD), in accordance with various aspects;

fig. 7 illustrates an example scenario for an observed time difference of arrival (OTDOA) based positioning estimation technique, in accordance with various aspects;

FIG. 8 is an example scenario for position estimation with beam sweep, in accordance with various aspects;

fig. 9 illustrates an example flow for location estimation in accordance with various aspects;

fig. 10 illustrates an example flow for selecting TOAs to improve positioning accuracy, in accordance with various aspects;

fig. 11 illustrates a scenario for pruning TOAs, in accordance with various aspects; and

fig. 12 illustrates a flow diagram of an example method of UE-assisted positioning determination, in accordance with various aspects.

Detailed Description

Various aspects described herein relate generally to wireless communication systems, and more particularly to phase difference of arrival (PDoA) and angle of departure (AoD) estimation. In an aspect, a network entity may provide a Base Station Almanac (BSA) to a UE. The BSA may indicate a set of transmission points associated with a base station, and the UE may perform measurements on signals transmitted from the set of transmission points. In particular, the UE may determine the PDoA of these signals. The UE may determine or estimate aods for the signals further based on the pdoas and/or may provide the pdoas to a network entity.

These and other aspects are disclosed in the following description and related drawings to illustrate specific examples related to various exemplary aspects. Alternative aspects will be apparent to those skilled in the relevant art(s) upon reading this disclosure, and may be constructed and practiced without departing from the scope or spirit of the disclosure. Additionally, well-known elements will not be described in detail or may be omitted so as not to obscure the relevant details of the aspects disclosed herein.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. Likewise, the term "aspect" does not require that all aspects include the discussed feature, advantage or mode of operation.

The terminology used herein describes only certain aspects and should not be read as limiting any of the aspects disclosed herein. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood by those within the art that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Further, various aspects may be described in terms of sequences of actions to be performed by, for example, elements of a computing device. Those skilled in the art will recognize that various actions described herein can be performed by specific circuits (e.g., Application Specific Integrated Circuits (ASICs)), by program instructions being executed by one or more processors, or by a combination of both. Additionally, these sequence of actions described herein can be considered to be embodied entirely within any form of non-transitory computer readable medium having stored thereon a corresponding set of computer instructions that upon execution would cause an associated processor to perform the functionality described herein. Thus, the various aspects described herein may be embodied in a number of different forms, all of which have been contemplated to be within the scope of the claimed subject matter. Additionally, for each aspect described herein, the corresponding form of any such aspect may be described herein as, for example, "logic configured to" perform the described action and/or other structural components configured to perform the described action.

As used herein, the terms "user equipment" (or "UE"), "user device," "user terminal," "client device," "communication device," "wireless communication device," "handheld device," "mobile terminal," "mobile station," "handset," "access terminal," "subscriber device," "subscriber terminal," "subscriber station," "terminal," and variations thereof, may interchangeably refer to any suitable mobile or stationary device capable of receiving wireless communication and/or navigation signals. These terms are also intended to include a device that is in communication with another device that is capable of receiving wireless communication and/or navigation signals (such as via a short-range wireless, infrared, wired, or other connection), regardless of whether satellite signal reception, assistance data reception, and/or positioning-related processing occurs at the device or at the other device. In addition, these terms are intended to include all devices, including wireless and wired communication devices, which are capable of communicating with a core network via a Radio Access Network (RAN), and through which a UE is capable of connecting with external networks, such as the internet, as well as with other UEs. Of course, other mechanisms of connecting to the core network and/or the internet are also possible for the UE, such as over a wired access network, a Wireless Local Area Network (WLAN) (e.g., based on IEEE 802.11, etc.), and so forth. The UE can be implemented by any of several types of devices, including but not limited to a Printed Circuit (PC) card, a compact flash device, an external or internal modem, a wireless or wired phone, a smart phone, a tablet, a tracking device, an asset tag, and so forth. The communication link through which the UE can send signals to the RAN is called an uplink channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc.). The communication link through which the RAN can send signals to the UEs is called a downlink or forward link channel (e.g., paging channel, control channel, broadcast channel, forward traffic channel, etc.). As used herein, the term Traffic Channel (TCH) may refer to an uplink/reverse traffic channel or a downlink/forward traffic channel.

According to various aspects, fig. 1 illustrates an example wireless communication system 100. The wireless communication system 100, which may also be referred to as a Wireless Wide Area Network (WWAN), may include various base stations 102 and various UEs 104. The base station 102 may include a macro cell (high power cellular base station) and/or a small cell (low power cellular base station), where the macro cell may include an evolved node B (eNB), where the wireless communication system 100 corresponds to an LTE network or G B node (gNB), where the wireless communication system 100 corresponds to a 5G network or a combination of both, and the small cell may include a femtocell, a picocell, a microcell, etc.

The base stations 102 may collectively form a Radio Access Network (RAN) and interface with an Evolved Packet Core (EPC) or Next Generation Core (NGC) over a backhaul link. Base station 102 may perform functions related to, among other functions, communicating user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, Multimedia Broadcast Multicast Service (MBMS), subscriber and equipment tracking, RAN Information Management (RIM), paging, positioning, and delivery of alert messages. The base stations 102 may communicate with each other directly or indirectly (e.g., through the EPC/NGC) over backhaul links 134, which backhaul links 134 may be wired or wireless.

The base station 102 may communicate wirelessly with the UE 104. Each base station 102 may provide communication coverage for a respective geographic coverage area 110. In an aspect, although not shown in fig. 1, coverage area 110 may be subdivided into multiple cells (e.g., three) or sectors, each cell corresponding to a single antenna or antenna array of base station 102. As used herein, the term "cell" or "sector" can correspond to one of multiple cells of base station 102 or base station 102 itself, depending on the context.

While neighboring macro cell geographic coverage areas 110 may partially overlap (e.g., in a handover region), some geographic coverage areas 110 may be substantially overlapped by larger geographic coverage areas 110. For example, the small cell base station 102 'may have a coverage area 110' that substantially overlaps with the coverage area 110 of one or more macro cell base stations 102. A network that includes both small cells and macro cells may be referred to as a heterogeneous network. The heterogeneous network may also include a home enb (HeNB) that may provide services to a restricted group referred to as a Closed Subscriber Group (CSG). The communication link 120 between base station 102 and UE 104 may include Uplink (UL) (also known as reverse link) transmissions from UE 104 to base station 102 and/or Downlink (DL) (also known as forward link) transmissions from base station 102 to UE 104. The communication link 120 may use MIMO antenna techniques including spatial multiplexing, beamforming, and/or transmit diversity. These communication links may be over one or more carriers. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL than UL).

The wireless communication system 100 may further include a Wireless Local Area Network (WLAN) Access Point (AP)150 in communication with a WLAN Station (STA)152 via a communication link 154 in an unlicensed spectrum (e.g., 5 GHz). When communicating in the unlicensed spectrum, the WLAN STA 152 and/or the WLAN AP150 may perform a Clear Channel Assessment (CCA) to determine whether the channel is available prior to communicating.

The small cell base station 102' may operate in licensed and/or unlicensed spectrum. When operating in unlicensed spectrum, the small cell base station 102' may employ LTE or 5G technology and use the same 5GHz unlicensed spectrum as used by the WLAN AP 150. A small cell base station 102' employing LTE/5G in unlicensed spectrum may boost coverage and/or increase capacity of an access network. LTE in unlicensed spectrum may be referred to as LTE unlicensed (LTE-U), Licensed Assisted Access (LAA), or MulteFire.

The wireless communication system 100 may further include a mmW base station 180, the mmW base station 180 operable in mmW frequencies and/or near mmW frequencies to be in communication with the UE 182. Extremely High Frequencies (EHF) are part of the RF in the electromagnetic spectrum. The EHF has a range of 30GHz to 300GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in this frequency band may be referred to as millimeter waves. Near mmW can be extended down to 3GHz frequencies with 100 mm wavelength. The ultra-high frequency (SHF) band extends between 3GHz to 30GHz, which is also known as a centimeter wave. Communications using the mmW/near mmW radio frequency band have high path loss and relatively short range. The mmW base station 180 may utilize beamforming 184 with the UE 182 to compensate for the very high path loss and short range. Further, it is to be appreciated that in alternative configurations, one or more base stations 102 may also transmit using mmW or near mmW and beamforming. Accordingly, it will be appreciated that the foregoing is merely an example and should not be construed as limiting the various aspects disclosed herein.

The wireless communication system 100 may further include one or more UEs, such as UE 190, indirectly connected to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links. In the embodiment of fig. 1, the UE 190 has a D2D P2P link 192 with one of the UEs 104 connected to one of the base stations 102 (e.g., the UE 190 may indirectly obtain cellular connectivity through it), and a D2D P2P link 194 with the WLAN STAs 152 connected to the WLAN AP150 (the UE 190 may indirectly obtain WLAN-based internet connectivity through it). In an example, the D2D P2P link 192 and 194 may be supported using any well-known D2D Radio Access Technology (RAT), such as LTE direct (LTE-D), WiFi direct (WiFi-D), bluetooth, etc.

According to various aspects, fig. 2A illustrates an example wireless network structure 200. For example, the Next Generation Core (NGC)210 may be functionally viewed as a control plane function 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and a user plane function 212 (e.g., UE gateway function, access to a data network, IP routing, etc.) that operate cooperatively to form a core network. A user plane interface (NG-U)213 and a control plane interface (NG-C)215 connect the gNB 222 to the NGC 210, in particular to the control plane functions 214 and the user plane functions 212. In an additional configuration, the eNB 224 may also connect to the NGC 210 via NG-C215 to the control plane function 214 and NG-U213 to the user plane function 212. Further, eNB 224 may communicate directly with the gNB 222 via backhaul connection 223. Accordingly, in some configurations, the new RAN 220 may have only one or more gnbs 222, while other configurations include one or more of enbs 224 and gnbs 222. The gNB 222 or eNB 224 may communicate with a UE 240 (e.g., any UE depicted in fig. 1, such as UE 104, UE 182, UE 190, etc.). Another optional aspect may include a location server 230 that may be in communication with the NGC 210 to provide location assistance for the UE 240. Location server 230 may be implemented as a plurality of structurally separate servers or, alternatively, may each correspond to a single server. The location server 230 may be configured to support one or more location services for the UE 240, the UE 240 being able to connect to the location server 230 via the core network, the NGC 210, and/or via the internet (not illustrated). Further, the location server 230 may be integrated into a component of the core network or alternatively may be external to the core network.

According to various aspects, fig. 2B illustrates another example wireless network structure 250. For example, Evolved Packet Core (EPC)260 may be functionally viewed as a control plane function, Mobility Management Entity (MME)264, and user plane function, packet data network gateway/serving gateway (P/SGW)262 that cooperatively operate to form a core network. The S1 user plane interface (S1-U)263 and S2 control plane interface (S1-MME)265 connect the eNB 224 to the EPC 260, and in particular to the MME 264 and the P/SGW 262. In an additional configuration, the gNB 222 may also connect to the EPC 260 via S1-MME 265 to connect to MME 264 and to the EPC 260 via S1-U263 to connect to the P/SGW 262. Further, eNB 224 may communicate directly with gNB 222 via backhaul connection 223, whether with or without gNB direct connectivity to EPC 260. Accordingly, in some configurations, the new RAN 220 may have only one or more gnbs 222, while other configurations include one or more of enbs 224 and gnbs 222. The gNB 222 or eNB 224 may communicate with a UE 240 (e.g., any UE depicted in fig. 1, such as UE 104, UE 182, UE 190, etc.). Another optional aspect may include location server 230 that may be in communication with EPC 260 to provide location assistance for UE 240. Location server 230 may be implemented as a plurality of structurally separate servers or, alternatively, may each correspond to a single server. Location server 230 may be configured to support one or more location services for UE 240, UE 240 being able to connect to location server 230 via a core network, EPC 260, and/or via the internet (not illustrated).

According to various aspects, fig. 3A illustrates an example base station 310 (e.g., eNB, gNB, small cell AP, WLAN AP, etc.) in a wireless network in communication with an example UE 350. In the DL, IP packets from the core network (NGC 210/EPC 260) may be provided to the controller/processor 375. Controller/processor 375 implements functionality for a Radio Resource Control (RRC) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, and a Medium Access Control (MAC) layer. Controller/processor 375 provides RRC layer functionality associated with broadcast of system information (e.g., MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-RAT mobility, and measurement configuration of UE measurement reports; PDCP layer functionality associated with header compression/decompression, security (ciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer Packet Data Units (PDUs), error correction by ARQ, concatenation, segmentation and reassembly of RLC Service Data Units (SDUs), re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, scheduling information reporting, error correction, priority handling, and logical channel prioritization.

The Transmit (TX) processor 316 and the Receive (RX) processor 370 implement layer-1 functionality associated with various signal processing functions. Layer-1, which includes the Physical (PHY) layer, may include error detection on the transport channel, Forward Error Correction (FEC) encoding/decoding of the transport channel, interleaving, rate matching, mapping onto the physical channel, modulation/demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 processes the mapping to the signal constellation based on various modulation schemes (e.g., Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to OFDM subcarriers, multiplexed with reference signals (e.g., pilots) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to generate a physical channel carrying a time-domain OFDM symbol stream. The OFDM stream is spatially precoded to produce a plurality of spatial streams. The channel estimates from channel estimator 374 may be used to determine coding and modulation schemes and for spatial processing. The channel estimate may be derived from a reference signal transmitted by the UE 350 and/or channel condition feedback. Each spatial stream may then be provided to one or more different antennas 320 via a separate transmitter 318 TX. Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to an RX processor 356. The TX processor 368 and the RX processor 356 implement layer-1 functionality associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined into a single OFDM symbol stream by the RX processor 356. RX processor 356 then transforms the OFDM symbol stream from the time domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by channel estimator 358. These soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 310 on the physical channel. These data and control signals are then provided to a controller/processor 359 that implements layer-3 and layer-2 functionality.

The controller/processor 359 can be associated with memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, cipher interpretation, header decompression, and control signal processing to recover IP packets from the core network. The controller/processor 359 is also responsible for error detection.

Similar to the functionality described in connection with the DL transmission by base station 310, controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression/decompression, and security (ciphering, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction by ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing MAC SDUs onto TBs, demultiplexing MAC SDUs from TBs, scheduling information reporting, error correction by HARQ, priority handling, and logical channel prioritization.

Channel estimates, derived by a channel estimator 358 from reference signals or feedback transmitted by base station 310, may be used by TX processor 368 to select appropriate coding and modulation schemes, as well as to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354 TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.

UL transmissions are processed at the base station 310 in a manner similar to that described in connection with receiver functionality at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to RX processor 370.

The controller/processor 375 can be associated with a memory 376 that stores program codes and data. Memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, cipher interpretation, header decompression, control signal processing to recover IP packets from the UE 350. IP packets from controller/processor 375 may be provided to a core network. Controller/processor 375 is also responsible for error detection.

Fig. 3B illustrates an exemplary server 300B. In an example, the server 300B may correspond to an example configuration of the location server 230 described above. The server 300B includes a processor 301B coupled to volatile memory 302B and a large capacity nonvolatile memory, such as a disk drive 303B. The server 300B may also include a floppy disk drive, Compact Disk (CD) or DVD disk drive 306B coupled to the processor 301B. The server 300B can also include a network access port 304B coupled to the processor 301B for establishing a data connection with a network 307B, such as a local area network coupled to other broadcast system computers and servers or to the internet.

Fig. 4 illustrates an example wireless communication system 400 in accordance with various aspects of the disclosure. In the example of fig. 4, the UE404 (which may correspond to any of the UEs described above with respect to fig. 1 (e.g., UE 104, UE 182, UE 190, etc.)) is attempting to compute an estimate of its location, or assists another entity (e.g., a base station or core network component, another UE, a location server, a third party application, etc.) in computing an estimate of its location. The UE404 may wirelessly communicate with multiple base stations 402a-d (collectively referred to as base stations 402) using RF signals and standardized protocols for modulating the RF signals and exchanging packets of information, the base stations 402 may correspond to any combination of base stations 102 or 180 and/or WLAN AP150 in fig. 1. By extracting different types of information from the exchanged RF signals and utilizing the layout of the wireless communication system 400 (i.e., base station location, geometry, etc.), the UE404 may determine its location or assist in determining its location in a predefined reference coordinate system. In an aspect, the UE404 may specify its location using a two-dimensional coordinate system; however, aspects disclosed herein are not so limited, and may also be applicable to determining a position fix using a three-dimensional coordinate system where additional dimensions are desired. Additionally, although fig. 4 illustrates one UE404 and four base stations 402, there may be more UEs 404 and more or fewer base stations 402, as will be appreciated.

To support positioning estimation, the base station 402 may be configured to broadcast a reference RF signal (e.g., a Positioning Reference Signal (PRS), a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), a synchronization signal, etc.) to each UE404 in its coverage area to enable the UE404 to measure a reference RF signal timing difference (e.g., OTDOA or RSTD) between each network node pair and/or identify a beam that best excites the LOS or shortest radio path between the UE404 and the transmitting base station 402. Identifying LOS/shortest path beams is of interest not only because these beams can then be used for OTDOA measurements between a pair of base stations 402, but also because identifying these beams can directly provide some positioning information based on beam direction. Furthermore, these beams can then be used for other positioning estimation methods that require accurate ToA, such as methods based on round trip time estimation.

As used herein, a "network node" may be a base station 402, a cell of the base station 402, a remote radio head, an antenna of the base station 402, wherein the antenna location of the base station 402 is different from the location of the base station 402 itself or any other network entity capable of transmitting reference signals. Further, as used herein, a "node" may refer to a network node or a UE.

A location server (e.g., location server 230) may transmit assistance data to UE404, the assistance data including: an identification of one or more neighbor cells of the base station 402, and configuration information regarding reference RF signals transmitted by each neighbor cell. Alternatively, the assistance data may originate directly from each base station 402 itself (e.g., in an overhead message that is periodically broadcast, etc.). Alternatively, the UE404 may detect the neighbor cells of the base station 402 itself without using assistance data. The UE404 (e.g., based in part on assistance data (if provided)) may measure and (optionally) report OTDOA from individual network nodes and/or RSTD between reference RF signals received from network node pairs. Using these measurements and the known locations of the measured network nodes (i.e., the base station(s) 402 or antenna(s) that transmitted the reference RF signal measured by the UE404), the UE404 or location server may determine the distance between the UE404 and the measured network nodes and calculate the location of the UE404 therefrom.

The term "location estimate" is used herein to refer to an estimate of the location of the UE404, which may be geographic (e.g., may include latitude, longitude, and possibly altitude) or municipal (e.g., may include a street address, a building name, or a precise point or area within or near a building or street address (such as a particular entrance to a building, a particular room or suite in a building), or a landmark (such as a civic square)). A position estimate may also be referred to as a "position," "fix," "position estimate," "fix estimate," or some other terminology. The manner in which the position estimate is obtained may be generally referred to as "positioning," addressing, "or" position fix. A particular solution for obtaining a location estimate may be referred to as a "location solution". A particular method for obtaining a location estimate as part of a location solution may be referred to as a "location method", or as a "position determination method".

The term "base station" may refer to multiple physical transmission points where a single physical transmission point may or may not be co-located. For example, where the term "base station" refers to a single physical transmission point, the physical transmission point may be a base station antenna corresponding to a cell of a base station (e.g., base station 402). Where the term "base station" refers to a plurality of co-located physical transmission points, these physical transmission points may be an antenna array of the base station (e.g., as in a MIMO system or where beamforming is employed by the base station). Where the term "base station" refers to a plurality of non-co-located physical transmission points, these physical transmission points may be Distributed Antenna Systems (DAS) (a network of spatially separated antennas connected to a common source via a transmission medium) or Remote Radio Heads (RRHs) (remote base stations connected to a serving base station). Alternatively, these non-collocated physical transmission points may be a serving base station that receives measurement reports from a UE (e.g., UE404) and a neighbor base station for which the UE is measuring its reference RF signals. Thus, fig. 4 illustrates an aspect in which base stations 402a and 402b form a DAS/RRH 420. For example, base station 402a may be a serving base station for UE404, and base station 402b may be a neighbor base station for UE 404. As such, base station 402b may be the RRH of base station 402 a. The base stations 402a and 402b may communicate with each other over a wired or wireless link 422.

In order to accurately determine the location of the UE404 using OTDOA and/or RSTD between received RF signals from various network node pairs, the UE404 needs to measure a reference RF signal received on a LOS path (or the shortest NLOS path if a LOS path is not available) between the UE404 and the network node (e.g., base station 402, antenna). However, RF signals not only travel along the LOS/shortest path between the transmitting and receiving parties, but also on several other paths, as the RF signals spread out from the transmitting party and are reflected by other objects (such as hills, buildings, water, etc.) on their way to the receiving party. Thus, fig. 4 illustrates several LOS paths 410 and several NLOS paths 412 between the base station 402 and the UE 404. In particular, fig. 4 illustrates base station 402a transmitting on LOS path 410a and NLOS path 412a, base station 402b transmitting on LOS path 410b and two NLOS paths 412b, base station 402c transmitting on LOS path 410c and NLOS path 412c, and base station 402d transmitting on two NLOS paths 412 d. As illustrated in fig. 4, each NLOS path 412 reflects from some object 430 (e.g., a building). As will be appreciated, each LOS path 410 and NLOS path 412 transmitted by the base station 402 can be transmitted by different antennas of the base station 402 (e.g., as in a MIMO system), or can be transmitted by the same antenna of the base station 402 (thereby illustrating propagation of RF signals). Furthermore, as used herein, the term "LOS path" refers to the shortest path between the transmitter and the receiver, and may not be the actual LOS path but the shortest NLOS path.

Each LOS path 410 and NLOS path 412 represents a path followed by an RF signal. The "RF signal" includes an electromagnetic wave that transmits information through a space between a transmitting side and a receiving side. As illustrated in fig. 4 and described further below, a receiving party (e.g., UE404) may receive multiple "RF signals" corresponding to each transmitted RF signal due to the propagation characteristics of the respective RF signals through the multipath channel. More specifically, when a transmitting party (e.g., base station 402) transmits an RF signal, the RF signal received at the receiving party (e.g., UE404) is the sum or accumulation of the RF signals received over multiple paths. For example, the UE404 may combine the RF signals received on the LOS path 410c and the NLOS path 412c into a single RF signal. Since the signal paths may have different lengths and arrive at the receiver from different directions, as illustrated in fig. 4, the RF signal from each path is delayed accordingly and arrives at an angle. At higher frequencies (such as mmW), this directional effect is more pronounced.

In receive beamforming, the receiving party uses a receive beam to amplify the RF signal detected on a given channel. For example, the receiving party may increase the gain setting of an antenna array (e.g., antenna 352 in fig. 3) and/or adjust the phase setting of the antenna array in a particular direction to amplify (e.g., increase the gain level of) the RF signal received from that direction. Thus, when a receiving party is said to be beamforming in a certain direction, this means that the beam gain in that direction is high relative to the beam gain in other directions, or the beam gain in that direction is highest relative to the beam gain in that direction for all other receive beams available to the receiving party. This results in a stronger received signal strength (e.g., RSRP, SINR, etc.) for the RF signal received from that direction.

Fig. 5 illustrates an example wireless communication system 500 in accordance with various aspects of the disclosure. In the example of fig. 5, the UE 504 (which may correspond to the UE404 in fig. 4) is attempting to compute an estimate of its location, or assisting another entity (e.g., a base station or core network component, another UE, a location server, a third party application, etc.) in computing an estimate of its location. The UE 504 may wirelessly communicate with a base station 502 (which may correspond to one of the base stations 402 in fig. 4) using RF signals and standardized protocols for modulation of the RF signals and exchange of information packets.

As illustrated in fig. 5, the base station 502 is utilizing beamforming to transmit multiple beams 511 and 515 of an RF signal. Each beam 511 and 515 may be formed and transmitted by an antenna array of the base station 502. Although fig. 5 illustrates the base station 502 transmitting five beams, as will be appreciated, there may be more or less than five beams, the beam shapes (such as peak gain, width, and side lobe gain) may differ between the transmitted beams, and some of the beams may be transmitted by different base stations.

A beam index may be assigned to each of the plurality of beams 511-515 for the purpose of distinguishing RF signals associated with one beam from RF signals associated with another beam. Further, the RF signal associated with a particular beam of the plurality of beams 511 and 515 may carry a beam index indicator. The beam index may also be derived from the transmission time (e.g., frame, slot, and/or number of OFDM symbols) of the RF signal. The beam index indicator may be, for example, a three-bit field for uniquely distinguishing up to eight beams. If two different RF signals with different beam indices are received, this would indicate that the RF signals were transmitted using different beams. If two different RF signals share a common beam index, this would indicate that the different RF signals were transmitted using the same beam. Another way to describe that two RF signals are transmitted using the same beam is: the antenna port(s) for transmission of the first RF signal are spatially co-located with the antenna port(s) for transmission of the second RF signal.

In the example of fig. 5, UE 504 receives NLOS stream 523 of RF signals transmitted on beam 513 and LOS stream 524 of RF signals transmitted on beam 514. Although fig. 5 illustrates NLOS stream 523 and LOS stream 524 as a single line (dashed and solid lines, respectively), as will be appreciated, NLOS stream 523 and LOS stream 524 may each include multiple rays (i.e., "clusters") up to the time they reach UE 504, e.g., due to the propagation characteristics of the RF signal through the multipath channel. For example, when an electromagnetic wave is reflected by multiple surfaces of an object and the reflections reach a receiving party (e.g., UE 504) from approximately the same angle, clusters of RF signals are formed, each reflection traveling several wavelengths (e.g., centimeters) more or less than the other reflections. A "cluster" of received RF signals generally corresponds to a single transmitted RF signal.

In the example of fig. 5, NLOS stream 523 is not initially directed to UE 504, although as will be appreciated it may initially be directed to UE 504, as is the RF signal on NLOS path 412 in fig. 4. However, it is reflected by the reflector 540 (e.g., a building) and reaches the UE 504 unimpeded, and thus may still be a relatively strong RF signal. In contrast, the LOS stream 524 is directed toward the UE 504, but passes through an obstacle 530 (e.g., vegetation, buildings, hills, disruptive environments such as clouds or smoke, etc.), which can significantly degrade the RF signal. As will be appreciated, although LOS stream 524 is weaker than NLOS stream 523, LOS stream 524 will arrive at UE 504 before NLOS stream 523 because it follows a shorter path from base station 502 to UE 504.

As mentioned above, the beam of interest for data communication between a base station (e.g., base station 502) and a UE (e.g., UE 504) is the beam carrying the RF signal that arrives at the UE with the highest signal strength (e.g., highest RSRP or SINR), while the beam of interest for location estimation is the beam carrying the RF signal that excites the LOS path and has the highest gain along the LOS path among all other beams (e.g., beam 514). That is, even if beam 513(NLOS beam) would weakly excite the LOS path (even if not focused along the LOS path due to the propagation characteristics of the RF signal), the weak signal (if any) of the LOS path of beam 513 may not be reliably detected (as compared to the LOS path from beam 514), thereby causing greater error in performing location measurements.

Although the beam of interest for data communication and the beam of interest for location estimation may be the same beam for some frequency bands, they may not be the same beam for other frequency bands (such as mmW). As such, referring to fig. 5, where the UE 504 is engaged in a data communication session with the base station 502 (e.g., where the base station 502 is the serving base station for the UE 504) and is not simply attempting to measure the reference RF signal transmitted by the base station 502, the beam of interest for the data communication session may be beam 513 because it is carrying an unblocked NLOS stream 523. However, the beam of interest for location estimation will be beam 514 because, although it is blocked, it carries the strongest LOS stream 524.

Fig. 6A is a diagram 600A illustrating RF channel response over time at a receiving party (e.g., UE 504) in accordance with aspects of the present disclosure. Under the channel illustrated in fig. 6A, the receiver receives a first cluster of two RF signals on the channel taps at time T1, a second cluster of five RF signals on the channel taps at time T2, a third cluster of five RF signals on the channel taps at time T3, and a fourth cluster of four RF signals on the channel taps at time T4. In the example of fig. 6A, because the first cluster of RF signals arrives first at time T1, it is assumed to be an LOS stream (i.e., a stream arriving on an LOS or shortest path) and may correspond to LOS stream 524. The third cluster at time T3 includes the strongest RF signal and may correspond to NLOS stream 523. Each cluster of received RF signals may include a portion of RF signals transmitted at a different angle from the transmitter side, and thus each cluster may be referred to as having a different angle of departure (AoD) from the transmitter side. Fig. 6B is a diagram 600B illustrating this separation of clusters by AoD. The RF signals transmitted in the AoD range 602a may correspond to one cluster (e.g., "cluster 1") in fig. 6A, while the RF signals transmitted in the AoD range 602b may correspond to a different cluster (e.g., "cluster 3") in fig. 6A. Note that although the AoD ranges of the two clusters depicted in fig. 6B are spatially isolated, the AoD ranges of some clusters may also partially overlap, even though the clusters are separated in time. This may occur, for example, when signals are reflected to the receiving side from two separate buildings at the same AoD of the transmitting side. Note that although fig. 6A illustrates clusters of two to five channel taps, as will be appreciated, the clusters may have more or fewer channel taps than the illustrated number of channel taps.

As in the example of fig. 5, the base station may utilize beamforming to transmit multiple beams of RF signals such that one of the beams (e.g., beam 514) is directed to the AoD range 602a of the first RF signal cluster and a different beam (e.g., beam 513) is directed to the AoD range 602b of the third RF signal cluster. The signal strength of each cluster in the beamformed channel response (i.e., the channel response when the transmitted RF signal is beamformed instead of omni-directionally) will scale with the beam gain along the AoD of each cluster. In this case, the beam of interest for positioning will be the beam pointing to the AoD of the first RF signal cluster because these RF signals arrive first, while the beam of interest for data communication may be the beam pointing to the AoD of the third RF signal cluster because these RF signals are the strongest.

In general, when transmitting RF signals, the transmitting party does not know which path it will follow to the receiving party (e.g., UE 504) or when it will arrive at the receiving party, and therefore transmits RF signals on different antenna ports with equal amounts of energy. Alternatively, the transmitting party may beamform the RF signal in different directions over multiple transmission occasions and obtain measurement feedback from the receiving party to determine the radio path explicitly or implicitly.

Note that while the techniques disclosed herein have been generally described in terms of transmissions from a base station to a UE, they are equally applicable to transmissions from a UE to a base station, where the UE is capable of MIMO operation and/or beamforming, as will be appreciated. Furthermore, although beamforming is generally described above in the context of transmit beamforming, in some embodiments, receive beamforming may also be used in conjunction with the transmit beamforming described above.

As discussed above, in some frequency bands, the shortest path (which, as mentioned above, may be an LOS path or the shortest NLOS path) may be weaker than an alternative longer (NLOS) path (on which the RF signal arrives later due to propagation delays). Thus, in the case where the transmitting party uses beamforming to transmit RF signals, the beam of interest for data communication-the beam carrying the strongest RF signal-may be different from the beam of interest for location estimation-the beam carrying the RF signal that excites the shortest detectable path. As such, it would be beneficial for a receiving party to identify and report beams of interest for location estimation to a transmitting party, such that the transmitting party can subsequently modify the transmitted set of beams to assist the receiving party in performing location estimation.

Fig. 7 illustrates an example scenario for an OTDOA-based positioning estimation technique. OTDOA is a multipoint positioning methodology in which a UE measures the time of arrival (TOA) of downlink reference signals (DL RS) received from multiple cells (base stations, enbs, gnbs, etc.). From a reference cell (eNB in FIG. 7)₁) The TOA from several neighboring cells are subtracted to form the OTDOA. Geometrically, a hyperbola is determined per time (or range) difference, and the point where these hyperbolas intersect is the estimated UE location.

To estimate a two-dimensional (2D) (x, y or latitude, longitude) position of a UE, a minimum of three timing measurements from geographically dispersed cells are necessary. In fig. 7, the UE measures and slaves to the cell eNB₁、eNB₂And eNB₃τ of three TOAs corresponding to a transmitted Positioning Reference Signal (PRS)₁、τ₂And τ₃. Suppose eNB₁Is a reference cell, two OTDOAs t_2，1＝τ₂-τ₁And t_3，1＝τ₃-τ₁Is formed by the UE. Each TOA measurementτ_iThere may be some amount of error/uncertainty and the hyperbola includes some width illustrating the measurement uncertainty. The estimated UE location is the intersection area of the hyperbolas.

The UE determines a Received Signal Time Difference (RSTD). RSTD is the time difference between the measured PRS from cell i and the PRS from the reference cell at the UE. The RSTD calculation is shown in equation 1.

In equation 1, (T)_i-T₁) Is the transmission time offset (also known as the Real Time Difference (RTD)), n, between cell i and the reference cell_iAnd n_iIs the measurement error and c is the speed of light.

Transmit beamforming at the cell (TX BF) and/or receive beamforming at the UE may enable improved accuracy at the cell edge. In addition, beam refinement may also take advantage of the channel reciprocity procedure in the New Radio (NR). The uplink time difference of arrival (UTDOA) technique is similar to the OTDOA technique, except that the measurements are based on uplink reference signals from the UEs.

Fig. 8 illustrates an example scenario for position estimation with beam sweep. In particular, a Tx beam sweep (e.g., at the gNB) for Positioning Reference Signals (PRS) is illustrated. In this example, assume that the network is configured with beamformed PRSs. Multiple instances of PRS allow sweeping across all departure angles (AoD) for a cell at full transmit power per beam (TxPwr). Fig. 8 illustrates a cell transmitting PRSs on beam 1 at time 1, on beam 2 at time 2, and so on. Each of the one or more cells of the network may transmit its own PRS on a different beam at a different time.

The UE monitors all cells configured to send PRSs across all instances. Specifically, the UE determines a Channel Energy Response (CER) based on the received PRS. The CER is then pruned across all cells based on some quality metrics. The CER is used to estimate the TOA by finding the earliest peak of the PRS. The UE may need several instances to see a sufficient number of cells for estimating the location of the UE. The TOA estimate may be used to estimate UE positioning. UE-based estimation is a case where the UE itself can estimate the positioning. UE-based estimation is possible if a Base Station Almanac (BSA) is provided to the UE. UE-assisted estimation is where the UE reports TOA-related measurements (e.g., OTDOA, RSTD, etc.) to the network (e.g., to a location server) and the network estimates the location of the UE.

In estimating the TOA from the CER, a first arrival path (i.e., LOS path) is determined using a noise-related quality threshold for the spurious local peak. The TOA estimate is chosen such that it is the earliest local maximum of the CER, such that 1) it is at least some threshold X dB above the median of the CER, and 2) it is at most some threshold Y dB below the dominant peak.

Fig. 9 illustrates an example flow for location estimation. In an aspect, the memory 360 of the UE 350 in fig. 3A may be an example of a computer-readable medium storing computer-executable instructions to perform the flow of fig. 9. In another aspect, means for performing the procedure of fig. 9 may include one or more of the TX processor 368, the controller/processor 358, the memory 360, the channel estimator 358, the RX processor 356, the transceiver 354 of the UE 350.

As seen in fig. 9, the UE estimates the CER from the PRS transmitted from the cell. The TOA is then estimated by determining the earliest local maximum CER. The collected estimated TOAs are then pruned to derive TDOA vectors, which are then used to estimate location (for UE-based) or reported back to the network (for UE-assisted).

Note that even with relatively high SINR, there are occasions when TOA is estimated incorrectly. One way to improve positioning accuracy is to select TOAs estimated from PRS transmitted from geographically dispersed cells. In an aspect, TOA ranking and pruning techniques may be used to improve positioning accuracy by selecting TOAs from geographically dispersed cells.

Fig. 10 illustrates an example flow for selecting TOAs to improve positioning accuracy. In an aspect, the memory 360 of the UE 350 in fig. 3A may be an example of a computer-readable medium storing computer-executable instructions to perform the flow of fig. 10. In another aspect, means for performing the procedure of fig. 10 may include one or more of the TX processor 368, the controller/processor 358, the memory 360, the channel estimator 358, the RX processor 356, the transceiver 354 of the UE 350.

As seen in fig. 10, the UE may order the TOAs based on one or more quality metrics of the corresponding CER. SINR (including SNR) is one example of a quality metric. Another example is the median/TOA peak ratio. Yet another example is the median/dominant peak ratio. The UE may then prune the TOAs based on the quality metrics while ensuring that a sufficient number of geographical cells are represented in the TDOA vector. In other words, the quality of the received PRS is not the only criterion for selecting TOA for pruning. Instead, the location of the cell is also considered in selecting the TOA.

Fig. 11 illustrates a scenario for pruning TOAs, in accordance with one or more aspects. In fig. 11, it is assumed that cells 1 and 2 are co-located, i.e. at the same site. Further assume that based on the measurements, the UE has determined that the quality of the PRS is in order from good to bad as the quality of the PRS from cell 1, the quality of the PRS from cell 2, the quality of the PRS from cell 3, and the quality of the PRS from cell 4. Recall that at least three TOA measurements are necessary in order to estimate the 2D positioning of a UE. If the TOAs are selected based on the quality metrics only, the three TOAs selected will be the TOAs of cells 1, 2, and 3. However, the TOAs of cells 1, 2, and 3 will not be sufficient because cells 1 and 2 are co-located, which means that the TOAs of cells 1 and 2 are actually the same. In this example, the TOA of cell 2 (or cell 1) may be pruned, and the TOA of cell 4 may be included, assuming that the TOA of cell 4 meets the quality metric requirements.

Of course, it is possible to exceed the minimum number of TOAs selected. For example, the TOAs of both cells 1 and 2 may be included, as long as the TOAs of cells 3 and 4 are also included in the TDOA vector. That is, in an aspect, the TOAs may be pruned in order to ensure that a sufficient number of geographically dispersed cells (e.g., at least three non-co-located cells for 2D positioning, at least four non-co-located cells for 3D positioning) are represented in the pruned TOAs. As will be explained more clearly below, whether the co-located attribute is only one of several attributes that may be considered in pruning the TOA.

Referring back to fig. 10, the UE may derive a time difference of arrival (TDOA) vector from the clipped TOAs. For example, the TOA with the highest quality metric may be identified as the reference TOA, and the RSTDs of other cells in the TDOA vector may be calculated relative to the reference TOA (e.g., see equation (1)).

As described above, the UE may be equipped to prune TOAs when the network notifies the UE of the location attribute of the cell. In one aspect, these location attributes or simply "attributes" are relative attributes (i.e., relative to each other). That is, the signaled attribute may not include any absolute location information of the cell (such as the x, y, z coordinates of the cell). Of course, the location server knows the actual x, y, z coordinates.

The following are some (not necessarily all) attributes of the cell that can be notified to the UE-co-located attribute, row attribute, area border attribute, altitude border attribute, and plane attribute. When a group of cells (e.g., two or more cells) have the same co-location attribute, the member cells of the group are co-located. When a group of cells (e.g., three or more cells) have the same row attributes, the member cells are on the same row. For example, the member cell may be on a row parallel to a train track. When a cell cluster (e.g., two or more cells) has the same area boundary attribute, the member cells are all located within a threshold area boundary (e.g., within a threshold distance of each other). When a cell group (e.g., two or more cells) has the same altitude attribute, the member cells are all at the same altitude. When a cell group (e.g., two or more cells) has the same altitude boundary attribute, the member cells are all within a threshold altitude boundary (e.g., within a threshold altitude of each other). When a cell group (e.g., two or more cells) has the same planar attributes, the member cells are all on the same 2D plane.

The signaling of the attributes from the network may be semi-static and may be sent to the UE along with the PRS configuration. In an aspect, the signaling may take the form of a set of PRS IDs, where common attributes (co-location, row, region boundary, altitude boundary, plane) are identified with a particular PRS ID. The signaling may be provided to the UE after the UE makes a request, after the network is configured, or when the network configures the maximum size of TOAs to be reported. Note that if the network requires 3D positioning, information related to altitude (e.g., altitude attribute, altitude boundary attribute, plane attribute) may be signaled.

The network may signal the attributes of the multiple cells to the UE, e.g., through a network entity such as a location server. In an aspect, the plurality of cells may be grouped into one or more cell groups, and each cell group may include one or more member cells. Each cell group may be associated with a set of attributes including one or more attributes such that all member cells of the cell group have all of the attributes of the associated set of attributes in common.

In an aspect, the PRS ID may include a scrambling ID, and the attribute information may be embedded in the scrambling ID of the PRS. The UE may use the scrambling ID of each PRS to identify a cell group to which the corresponding cell belongs. For example, for a scrambling ID of 16 bits, the last two bits (e.g., bits 1 and 0) may be used for the co-location attribute. In this example, the scrambling IDs of the two PRSs have the same last two bits, and it can then be assumed that the two corresponding cells are co-located. Conversely, if the last two bits are different, it can be assumed that the two cells are not co-located, i.e., are located at different locations. In this example, the last two bits are mapped to a co-located attribute type. As another example, bit 4-2 may be used for the height attribute. It may be assumed that two cells with the same value in bit 4-2 are at the same height. Instead, it may be assumed that two cells with different values in bit 4-2 are at different heights. In this example, bit 4-2 is mapped to the height attribute type.

In general, if the specified set of bits of the scrambling ID is the same for two or more cells, then the same two or more cells belong to a group of cells having the configured attributes, i.e., they are member cells of the group of cells. It can be said that the bits of each scrambling ID can be divided into one or more attribute bit ranges. Each attribute bit range may include one or more bits and may be mapped to an attribute type (e.g., co-located attribute type, row attribute type, region boundary attribute type, height boundary attribute type, plane attribute type, etc.). For each cell of the plurality of cells, each attribute of the cell may be encoded in an attribute bit range of an attribute type mapped to the attribute in the scrambling ID.

In another aspect, the attribute information may be embedded in the RRC configuration. The PRS may be configured with a resource ID. Further, different resource IDs may be associated with different attributes of the cell transmitting the PRS. For example, the UE may determine that every third resource ID is co-located. That is, the cell transmitting the PRS with resource ID 0-2 is a member cell of a group of cells co-located at one location, the cell with resource ID 3-5 is a member cell of a group of cells co-located at another location, and so on. Note that the actual x, y, z coordinates of the location need not be provided to the UE.

As another example, the UE may determine that the cell with resource IDs 10-15 is a member cell of a group of cells at one elevation, the cell with resource IDs 16-20 is a member cell of a group of cells at another elevation, and so on. Again, the UE does not need to know the actual height of the cell. However, the network entity may inform the UE that the heights of the member cells among the different cell height groups differ from each other by at least a minimum group height difference.

In general, the plurality of PRSs may include a plurality of resource IDs. The plurality of resource IDs may be grouped into one or more resource ID groups, and each resource ID group may correspond to a cell group. In other words, each resource ID cluster may correspond to a set of attributes of one or more attributes as described above.

In an aspect, a UE may be configured with a default resource ID grouping to associate different resource ID groups with different sets of attributes. Alternatively or additionally, resource ID group information may be received from a network entity (such as a location server). For example, when a UE receives resource ID group information from the network, the UE may overwrite any previous resource ID group information.

Fig. 12 illustrates a flow diagram of an example method 1200 for determining a location of a UE in accordance with an aspect of the disclosure. The method 1200 is an example of a UE-assisted technology and involves a UE and a network entity (e.g., a location server). At 1205, the network entity sends attributes and cell group information for a plurality of cells configured to transmit a corresponding plurality of PRSs. For example, the information may be sent to the UE along with the PRS configuration. As mentioned above, this information may be sent as a result of a request from the UE, after network configuration, or when the network configures the maximum size of TOAs reported back to the network from the UE. In an aspect, means for performing block 1205 may include one or more of the controller/processor 375, the memory 376, the TX processor 316, the transceiver 318, and/or the antenna 320 of the base station 310 illustrated in fig. 3A (e.g., when the base station 310 is acting as a location server). In another aspect, the means for performing block 1205 may include one or more of the processor 301B, the volatile memory 302B, the non-volatile memory 303B, the driver 306B, and/or the network access port 304B of the server 300B illustrated in fig. 3B.

The attributes and cell group information provide at least the following. The plurality of cells are grouped into one or more cell groups. Each cell group includes one or more member cells, where each member cell is one of the plurality of cells. Each cell group is associated with a set of attributes that includes one or more attributes (e.g., one or more of co-siting, rows, zone boundaries, altitude boundaries, and planes). For each cell group, all member cells of the cell group have all attributes of the associated set of attributes in common.

For example, if the set of attributes for a cell group includes row and altitude attributes, the UE may assume that all member cells of the cell group are in the same row and at the same altitude.

The transmitted plurality of PRSs includes a plurality of PRS IDs (e.g., scrambling IDs, resource IDs). In an aspect, the PRS IDs correspond to the plurality of cells. For each cell group, the PRS ID for each member cell indicates the membership of that cell in that cell group. For example, when using a scrambling ID, the bit value of the attribute range for an attribute in the scrambling ID is the same for all member cells.

At 1210, the UE receives the attributes and cell group information. In an aspect, means for performing block 1210 may include one or more of the controller/processor 359, the memory 360, the RX processor 356, the transceiver 354, and/or the antenna 352 of the UE 350 illustrated in fig. 3.

At 1215, the network entity may configure the plurality of cells to transmit a plurality of PRSs. In an aspect, means for performing block 1215 may comprise one or more of the controller/processor 375 and/or memory 376 of the base station 310 illustrated in fig. 3A (e.g., when the base station 310 is acting as a location server). In another aspect, means for performing block 1215 may include one or more of the processor 301B, the volatile memory 302B, the non-volatile memory 303B, and/or the driver 306B of the server 300B illustrated in fig. 3B.

At 1220, the UE receives the plurality of PRSs from the plurality of cells. In an aspect, means for performing block 1220 may include one or more of the controller/processor 359, memory 360, RX processor 356, transceiver 354, and/or antenna 352 of the UE 350 illustrated in fig. 3.

At 1230, the UE detects a plurality of TOAs of the received plurality of PRSs. For example, for each PRS, the corresponding TOA may be selected such that it is the earliest local maximum of the CER that meets a threshold requirement (e.g., at least some threshold dB above the median of the CER, and no more than some threshold dB below the primary peak of the CER). In an aspect, means for performing block 1220 may include one or more of the controller/processor 359 and/or the memory 360 of the UE 350 illustrated in fig. 3.

At 1240, the UE prunes the plurality of TOAs based on the plurality of PRSs. For example, the UE may rank the TOAs based on one or more quality metrics (e.g., estimated SINR or SNR, median/TOA-peak ratio, median/dominant-peak ratio, etc.). Subsequently, the sorted TOAs may be pruned. In an aspect, means for performing block 1240 may comprise one or more of the controller/processor 359 and/or memory 360 of the UE 350 illustrated in fig. 3.

At 1250, a TDOA vector may be derived from the clipped TOAs. In an aspect, means for performing block 1250 may comprise one or more of the controller/processor 359 and/or the memory 360 of the UE 350 illustrated in fig. 3. The UE orders the TOAs such that the resulting TDOA vector includes TOA-related measurements (e.g., TOAs, RSTDs) for a plurality of cells, where each cell represented in the TDOA vector is a cell of the plurality of cells.

Furthermore, the cell represented in the TDOA vector is sufficient to determine the location of the UE in at least 2D. For example, TOA pruning may cause the TDOA vector to include TOA-related measurements from at least three cells that are not co-located with each other. In other words, TDOA should represent at least three cells with different co-location attributes. This ensures that TOAs of PRSs from a sufficient number of geographically dispersed cells are considered for 2D positioning determination. Of course, more than three TOA related measurements may be included if the network allows it. Additional measurements may help reduce uncertainty.

If a cluster of cells with different row attributes is included, in an aspect, positioning accuracy may be enhanced by pruning the TOAs such that the TDOA vector represents multiple-at least two-cells with different row attributes. If a cluster of cells with different area boundary attributes is included, in an aspect, positioning accuracy may be enhanced by pruning the TOAs such that the TDOA vector represents multiple-at least two-cells with different area boundary attributes.

If the UE's location in 3D is desired, the TDOA should include TOA-related measurements from at least four geographically dispersed cells. In an embodiment, at least four cells that are not co-located with each other may be represented in the TDOA vector. In another embodiment, two of the cells may be within the same boundary area, but at different heights. Of course, it is preferred that these cells are located in different border areas and at different heights. That is, if a cluster of cells with different altitude attributes is included, in an aspect, positioning accuracy may be enhanced by pruning the TOAs such that the TDOA vector represents multiple-at least two-cells with different altitude attributes. Furthermore, if a cluster of cells with different planar attributes is included, in an aspect, positioning accuracy may be enhanced by pruning the TOAs such that the TDOA vector represents multiple-at least two-cells with different planar attributes. Of course, if the network allows, more than four TOA-related measurements may be included to reduce uncertainty.

At 1260, the UE transmits the TDOA vector to a network entity (e.g., a location server). In an aspect, means for performing block 1260 may include one or more of the controller/processor 359, memory 360, TX processor 368, transceiver 354, and/or antenna 352 of the UE 350 illustrated in fig. 3.

At 1265, a network entity (e.g., a location server) receives the TDOA vector. In an aspect, means for performing block 1265 may comprise one or more of the controller/processor 375, the memory 376, the RX processor 370, the transceiver 318, and/or the antenna 320 of the base station 310 illustrated in fig. 3A (e.g., when the base station 310 is acting as a location server). In another aspect, the means for performing block 1265 may comprise one or more of the processor 301B, the volatile memory 302B, the non-volatile memory 303B, the driver 306B, and/or the network access port 304B of the server 300B illustrated in fig. 3B.

Since the location server knows the x, y, z coordinates of the multiple cells at 1275, the location server determines or otherwise estimates the UE location based on the TDOA vector at 1275. In an aspect, means for performing block 1275 may include one or more of controller/processor 375, memory 376, RX processor 370, transceiver 318, and/or antenna 320 of base station 310 illustrated in fig. 3A (e.g., when base station 310 is acting as a location server). In another aspect, means for performing block 1275 may comprise one or more of the processor 301B, the volatile memory 302B, the non-volatile memory 303B, the driver 306B, and/or the network access port 304B of the server 300B illustrated in fig. 3B.

In an aspect, memory 376 of base station 310 in fig. 3A may be an example of a computer-readable medium storing computer-executable instructions for one or more of TX processor 316, controller/processor 375, channel estimator 374, and/or RX processor 370 of base station 310 to perform blocks 1205, 1215, 1265, and 1275 of method 1200 when base station 310 is acting as a location server. In another aspect, the volatile memory 302B, the non-volatile memory 303B, and/or the disk drive 304B of the server 300B may be examples of computer-readable media storing computer-executable instructions for one or more of the processors 301B and/or the network access ports 304B of the server 300B to perform blocks 1205, 1215, 1265, and 1275 of the method 1200.

In yet another aspect, the memory 360 of the UE 350 in fig. 3A may be an example of a computer-readable medium that stores computer-executable instructions for one or more of the TX processor 368, the controller/processor 358, the channel estimator 358, and/or the RX processor 356 of the UE 350 to perform blocks 1210, 1220, 1230, 1240, 1250, and 1260 of the method 1200.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Furthermore, those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the various aspects described herein.

The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or other such configuration).

The methods, sequences and/or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), flash memory, read-only memory (ROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk, a removable disk, a CD-ROM, or any other form of non-transitory computer-readable medium known in the art. An exemplary non-transitory computer readable medium may be coupled to the processor such that the processor can read information from, and write information to, the non-transitory computer readable medium. In the alternative, the non-transitory computer-readable medium may be integral to the processor. The processor and the non-transitory computer readable medium may reside in an ASIC. The ASIC may reside in a user equipment (e.g., UE) or a base station. Alternatively, the processor and the non-transitory computer readable medium may be discrete components in a user equipment or a base station.

In one or more exemplary aspects, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a non-transitory computer-readable medium. Computer-readable media may include storage media and/or communication media including any non-transitory medium that can facilitate transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. The terms disk and disc, which may be used interchangeably herein, include Compact Disc (CD), laser disc, optical disc, Digital Video Disc (DVD), floppy disk and blu-ray disc, which often reproduce data magnetically and/or optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

While the foregoing disclosure shows illustrative aspects, those skilled in the art will appreciate that various changes and modifications may be made therein without departing from the scope of the disclosure as defined by the appended claims. Furthermore, those of skill in the art will appreciate that the functions, steps, and/or actions recited in any of the above-described methods and/or in any of the appended method claims need not be performed in any particular order, in accordance with the various illustrative aspects described herein. Still further, to the extent that any element is recited in the above description or in the appended claims in the singular, those skilled in the art will appreciate that the singular also contemplates the plural unless limitation to the singular is explicitly stated.