WO2021026699A1

WO2021026699A1 - Prs resource mapping and configuration based on grouping

Info

Publication number: WO2021026699A1
Application number: PCT/CN2019/100082
Authority: WO
Inventors: Yan Meng; Tao Tao; Jianguo Liu; Gang Shen
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2019-08-09
Filing date: 2019-08-09
Publication date: 2021-02-18
Also published as: CN114208326A

Abstract

Embodiments of the present disclosure relate to methods, apparatuses and computer readable storage media of positioning reference signal (PRS) resource mapping and configuration based on grouping. In example embodiments, a location server determines a group of adjacent base stations based on geographical locations of the base stations. The location server allocates at least one time-domain resource and a group of frequency-domain resources for a group of PRSs to be transmitted by the group of adjacent base stations. The location server further sends an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.

Description

PRS RESOURCE MAPPING AND CONFIGURATION BASED ON GROUPING

FIELD

Embodiments of the present disclosure generally relate to the field of communications, and in particular, to methods, apparatuses and computer readable storage media of positioning reference signal (PRS) resource mapping and configuration based on grouping.

BACKGROUND

Observed Time Difference of Arrival (OTDOA) is a downlink positioning technology in Long Term Evolution (LTE) Release 9 (Rel-9) . This technology employs a multilateration approach in which User Equipment (UE) measures time of arrival (TOA) of signals received from a plurality of base stations (for example, eNBs) . In LTE, positioning reference signals (PRS) have been introduced to allow proper timing measurements of a UE for signals from base stations to improve OTDOA positioning performance.

Positioning technologies for a New Radio (NR) system are being developed in the third generation partner project (3GPP) standardization. The positioning technologies need to enable Radio Access Technology (RAT) dependent positioning to operate in both Frequency Range 1 (or FR1, also referred to as a sub 6 Ghz range) and Frequency Range 2 (or FR2, also referred to as a millimeter wave range) . However, there is no applicable PRS design in the NR system to enable the OTDOA positioning algorithms to achieve high positioning accuracy.

SUMMARY

In general, example embodiments of the present disclosure provide methods, apparatuses and computer readable storage media of positioning reference signal (PRS) resource mapping and configuration based on grouping.

In a first aspect, a location server is provided which comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the location server to determine a group of adjacent base stations based on geographical locations of the base stations. The location server is caused to allocate at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by the group of adjacent base stations. The location server is further caused to send an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.

In a second aspect, user equipment is provided which comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the user equipment to receive an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group of adjacent base stations. The user equipment is caused to determine a beam direction for receiving the group of positioning reference signals. The user equipment is further caused to receive the group of positioning reference signals in the beam direction on the time-domain resource and the group of frequency-domain resources.

In a third aspect, a base station is provided which comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the base station to receive, from a location server, an indication for indicating at least a time-domain resource and a frequency-domain resource for transmitting a position reference signal. The base station is further caused to transmit the position reference signal on the time-domain resource and the frequency-domain resource.

In a fourth aspect, a method is provided. In the method, a location server determines a group of adjacent base stations based on geographical locations of the base stations. The location server allocates at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by the group of adjacent base stations. The location server further sends an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.

In a fifth aspect, a method is provided. In the method, user equipment receives an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group of adjacent base stations. The user equipment determines a beam direction for receiving the group of positioning reference signals. The user equipment further receives the group of positioning reference signals in the beam direction on the time-domain resource and the group of frequency-domain resources.

In a sixth aspect, a method is provided. In the method, a base station receives, from a location server, an indication for indicating at least a time-domain resource and a frequency-domain resource for transmitting a position reference signal. The base station further transmits the position reference signal on the time-domain resource and the frequency-domain resource.

In a seventh aspect, there is provided an apparatus comprising means for performing the method according to the third or fourth aspect.

In a eighth aspect, there is provided a computer readable storage medium that stores a computer program thereon. The computer program, when executed by a processor of a device, causes the device to perform the method according to the third or fourth aspect.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, where:

FIG. 1 illustrates example PRS resource mapping in LTE;

FIG. 2 illustrates example PRS resource configuration in LTE;

FIG. 3 illustrates an example scenario where gNBs are geographically far away from each other;

FIG. 4 illustrates an example environment in which embodiments of the present disclosure can be implemented;

FIG. 5 illustrates a flowchart of an example method according to some example embodiments of the present disclosure;

FIG. 6 illustrates a flowchart of an example method according to some other example embodiments of the present disclosure;

FIG. 7 illustrates example usage of a group ID in accordance with some example embodiments of the present disclosure;

FIG. 8 illustrates a flowchart of an example method according to some other example embodiments of the present disclosure;

FIG. 9 illustrates an example signaling flow 800 between a location server, base stations and a UE according to some example embodiments of the present disclosure;

FIG. 10 illustrates an example scenario of grouping-based PRS transmission according to some example embodiments of the present disclosure;

FIG. 11 illustrates an example scenario of grouping-based PRS transmission according to some other example embodiments of the present disclosure; and

FIG. 12 illustrates a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term “base station” (BS) refers to a device via which user equipment (UE) can access the communication network. Examples of the base station include a relay, an access point (AP) , a transmission point (TRP) , a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a New Radio (NR) NodeB (gNB) , a Remote Radio Module (RRU) , a radio header (RH) , a remote radio head (RRH) , a low power node such as a femto, a pico, and the like.

As used herein, the term “user plane function” (UPF) refers to a device, functionality or component for providing various functions in user plane in the core network. The UPF may provide interconnection, packet routing and forwarding and the like between mobile infrastructure and a data network.

As used herein, the term “user equipment” (UE) refers to a terminal device capable of wireless communications with each other with an end station of time-sensitive communication (TSC) or with the base station. The communications may involve transmitting and/or receiving wireless signals using electromagnetic signals, radio waves, infrared signals, and/or other types of signals suitable for conveying information over air. Examples of the UE include, but are not limited to, smart phones, wireless-enabled tablet computers, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , and/or wireless customer-premises equipment (CPE) .

As used herein, the term “location server” refers to a device, functionality or entity capable of providing location services or management to the UE. As an example, the location server may be a device in a core network of the communication network, such as an Evolved Serving Mobile Location Center (E-SMLC) which may communicate with a base station. As another example, the location server may be integrated with a base station.

As used herein, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) : (i) a combination of analog and/or digital hardware circuit (s) with software/firmware and (ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

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. The term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to” . The term “based on” is to be read as “based at least in part on” . The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment” . The term “another embodiment” is to be read as “at least one other embodiment” . Other definitions, explicit and implicit, may be included below.

As used herein, the terms “first” , “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

OTDOA as a mature positioning technology has been specified in LTE standardization. In OTDOA positioning, the UE needs to measure time differences for receiving PRS signals from two or more base stations. In LTE, the PRS resources of multiple cells are multiplexed in a frequency domain in one sub-frame. A cell-specific frequency shift is introduced in PRS mapping rules.

By way of example,

mod6 where v _shift represents a frequency shift,

represents a physical cell identity (PID) and mod represents a modulus operation. In this case, there are six possible frequency shift patterns to achieve the multiplexing of six cells in the frequency domain. The value of mod (PCI, 6) determines one of the six possible frequency arrangements. Accordingly, a frequency-domain resource of a PRS can be determined for a cell by mod (PCI, 6) .

FIG. 1 shows example PRS resource mapping 100. In this example, three base stations, represented by gNB#1, gNB#2 and gNB#3, transmit PRSs on the same time-domain resource, such as a symbol 105, but on different time-domain resources to achieve the multiplexing in the frequency domain. The frequency-domain resources of these base stations may be identified by different mod (PCI, 6) values.

In addition, the PRSs may be transmitted in pre-defined positioning subframes grouped by several consecutive subframes, which are termed “positioning occasions” . Positioning occasions occur periodically with a certain periodicity. The PRS sub-frame configuration such as a sub-frame offset, the number of downlink (DL) consecutive sub-frames and a PRS period may be configured by each base station individually.

The PRS sub-frame configuration may also involve PRS muting. As described above, the frequency-domain resource of the PRS may be determined by mod (PCI, 6) in the case that six cells are multiplexed in the frequency domain. Accordingly, if the cells have the same mod (PCI, 6) values (for example, PCI=0 and PCI=6) , the PRSs would collide and no longer be orthogonal. In such cases, PRS muting can be introduced to make the PRS occasions orthogonal to each other.

The PRS muting requires that PRSs in certain positioning occasions are transmitted with zero power. If a (strong) PRS received by the UE from its serving base station, for example, is muted, the (weak) PRS (s) from the neighbor base station (s) (with the same frequency shift) may be detected by the UE more easily. The PRS muting may be configured by a central node.

FIG. 2 illustrates example PRS resource configuration 200 in LTE. As shown in FIG. 2, with respect to a reference time 205 when subframe number (SFN) = 0 and slot number = 0, a PRS subframe offset 210 is configured by a base station. The base station also configures the number of consecutive subframes in a PRS occasion 215 and a PRS periodicity 220. In the example, six cells are multiplexed, for PCI=0, PCI=6, PCI=12 and PCT=18, the PRSs may collide. The PRS muting patterns for these PCIs are configured to be {1000} , {0100} , {0010} and {0001} , respectively, where “1” indicates the muting of the PRS transmission in the corresponding transmission occasion 215.

Conventionally, in LTE, the frequency-domain resource of a PRS may be determined by the cell ID. The time-domain resource for the PRS may be autonomously configured by the base station without any coordination with neighbor cells or neighbor base stations.

In NR, beamforming has been agreed to improve the hearability especially at least for a high frequency band. For example, in a NR system, receiver (Rx) beamforming needs to be supported to achieve the high hearability in the high frequency band. In this case, the PRS resource configuration in LTE seems to be not efficient for the NR system if Rx beamforming is used at a UE side.

For example, with the PRS resource mapping 100 as shown in FIG. 1, the PRS signals of three gNBs have been configured to transmit at one sub-frame 105 with different sub-carriers. The PRS configuration may be autonomously determined by one of the gNBs without considering geographic locations of the gNBs. If these three gNBs are geographically far away from each other, the UE can only receive one of PRS signal at one time occasion by using one receiving beam direction.

FIG. 3 shows an example scenario 300 where gNBs are geographically far away from each other.

As shown in FIG. 3, three

gNBs

305, 310 and 315 (represented by gNB#1, gNB#2 and gNB#3) transmit the PRSs at the same time instance as shown in FIG. 1. In this case, a UE 320 can only receive one of the PRSs at one time occasion by using one of receiving

beam directions

325, 330 and 335. As a result, the UE 320 needs several time occasions to receive all the PRSs of the three

gNBs

305, 310 and 315, which leads to the resource waste.

By now, there is no applicable PRS design in the NR system to enable the OTDOA positioning algorithms to achieve high positioning accuracy.

Embodiments of the present disclosure provide a novel PRS resource mapping and configuration scheme to improve the resource efficiency in Rx beamforming for the NR system, for example. This scheme proposes PRS configuration based on grouping of base stations. With the scheme, a location server divides base stations into different groups of adjacent base stations based on geographical locations of the base stations. For one group of adjacent base stations, the location server allocates at least one time-domain resource and a group of different frequency-domain resources for transmission of PRSs. The number of time-domain resources may depend on the number of base stations in the group.

In this way, a group of PRSs can be transmitted by a group of base stations using different frequency-domain resources at one time instance. Accordingly, a UE can receive one group of PRSs from a plurality of cells in one beam direction. Compared with autonomous PRS configuration of the base stations in LTE, the PRS configuration scheme according to example embodiments of the present disclosure ensures adjacent gNBs to transmit the PRSs at one time occasion under the control of the location server. As such, the UE can simultaneously receive the maximum number of PRSs, thereby achieving the high resource efficiency.

FIG. 4 shows an example environment 400 in which embodiments of the present disclosure can be implemented. The environment 400, which is a part of a communication network, comprises a UE 410 and a plurality of base stations 420-1, 420-2 …420-N (where N represents a positive integer) . For the purpose of discussion, the base stations will be collectively or individually referred to as a base station 420. The environment 400 also comprises a location server 430 which can communicate with the base stations 420 and with the UE 410 via the base stations 420 to provide location services to the UE 410.

It is to be understood that the number of base stations, UEs and location servers are shown in FIG. 4 only for the purpose of illustration without suggesting any limitation to the scope of the present disclosure. The environment 400 may comprise any suitable number of base stations, UEs and location servers adapted for implementing embodiments of the present disclosure.

The UE 410 can communicate with the base station 420 or via the base stations 420 with a further terminal device or the location server 430 or other network entities. The communications between the UE 410 and the base station 420 may follow any suitable wireless communication standards or protocols such as Universal Mobile Telecommunications System (UMTS) , long term evolution (LTE) , LTE-Advanced (LTE-A) , the fifth generation (5G) NR, Wireless Fidelity (Wi-Fi) and Worldwide Interoperability for Microwave Access (WiMAX) standards, and employs any suitable communication technologies, including, for example, Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiplexing (OFDM) , time division multiplexing (TDM) , frequency division multiplexing (FDM) , code division multiplexing (CDM) , Bluetooth, ZigBee, and machine type communication (MTC) , enhanced mobile broadband (eMBB) , massive machine type communication (mMTC) and ultra-reliable low latency communication (uRLLC) technologies.

The location server 430 can communicate with the base stations 420. The communications between the location server 430 and the base stations 420 may utilize any suitable communication technology. In some example embodiments, the location server 430 and the base station 420 may communicate in a cable.

As shown in FIG. 4, base stations 420-1…420-N are geographically adjacent to each other. The location server 430 clusters these base stations 420 into a group 440. It is to be understood that one group 440 is shown in the environment 400 only for the purpose of illustration without suggesting any limitation. The environment 400 may comprise any suitable number of groups 440 of adjacent base stations. For the group 440 of adjacent base stations, the location server 430 allocates the same time-domain resource and different frequency-domain resources for transmission of the PRSs. The UE 410 can use one beam direction 450 to receive the PRSs from the group 440 of base stations.

FIG. 5 shows a flowchart of an example method 500 in accordance with some example embodiments of the present disclosure. The method 500 can be implemented by the location server 430 as shown in FIG. 4. For the purpose of discussion, the method 500 will be described with reference to FIG. 4.

As shown, at block 505, the location server 430 determines a group 440 of adjacent base stations based on geographical locations of the base stations. The geographical locations of the base stations 420 may be determined by the location server 430 based on geographical information received or collected from these base stations 420. In some example embodiments, the location server 430 may collect positioning assisted information from surrounding base stations. The positioning assisted information may comprise geographical coordinates of the surrounding base stations as the geographical information about these base stations. Based on the geographical coordinates, the location server 430 may determine which base stations are adjacent to each other and then determine that these base stations form a group of adjacent base stations.

The location server 430 may determine the adjacency of the base stations 420 based on comparison of the geographical distances between these base stations and a threshold distance. The threshold distance may be pre-configured according to the network deployment and actual requirements. For example, in the example embodiments where the location services 430 obtains the geographical coordinates of the base station 420 as the geographical information, the location server 430 may determine the geographical distances between these base stations based on the corresponding geographical coordinates and then compare the geographical distances with the threshold distance. If the geographical distances between these base stations 420 are below the threshold distance, the location server 430 may determine that these base stations 420 are adjacent to each other.

At block 510, the location server 430 allocates at least one time-domain resource and a group of frequency-domain resources for a group of PRSs to be transmitted by the group of adjacent base stations 420. The number of time-domain resources allocated by the location server 430 may depend on the number of base stations in the group 440. For example, when the number of base stations in one group is larger than a threshold number, more than one time-domain resources may be allocated to the group. The threshold number may rely on the multiplexing of the base stations or PRSs in the frequency domain. For example, in the case that six base stations are multiplexed in the frequency domain, the threshold number may be set as 6. Based on the time and frequency resource allocation, a plurality of PRSs may be transmitted by a plurality of adjacent base station 420 using different frequency-domain resources at the same time instance.

The time-domain resource may comprise any suitable resource in the time domain. For example, the time-domain resource may comprise a transmission occasion for a PRS. The location server 430 may allocate one transmission occasion for the group of adjacent base stations. The frequency-domain resource may comprise any suitable resource in the frequency domain. For example, the frequency-domain resource may comprise a sub-carrier, a sub-band and a bandwidth part in the frequency domain. In the example embodiments where the location server 430 may allocate different sub-carriers to the adjacent base stations in the group, one group of adjacent base stations would transmit the PRSs on different sub-carriers but at the same time instance.

In addition, the time and frequency resource may involve any other suitable resource configurations. For example, the time-domain resource may comprise duration of the transmission occasion, a location of the transmission occasion and the periodicity of transmission occasions. The frequency-domain resources may comprise a cell-specific frequency shift and a PRS bandwidth. In the case that the sub-carriers are allocated, the frequency shift may implicitly indicate a sub-carrier index.

In some example embodiments, for different groups of base stations, the location server 430 may allocate different time-domain resources such as transmission occasions. Accordingly, different groups of bases stations transmit the PRSs on the different time-domain resources.

At block 515, the location server 430 sends an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group 440 of adjacent base stations. The indication may be sent to the group 440 of adjacent base stations by using LTE Positioning Protocol A (LPPa) or any other suitable protocols that exists already or will be developed in the future.

In some example embodiments, the location server 430 may send an indication for indicating the at least one time-domain resource and the group of frequency-domain resources towards the UE 410, for example, via a serving cell of the UE 410. For example, the location server 430 may include the information about both the time-domain and frequency-domain resources into the assistance data of the UE 410. The indication may be sent by reusing an existing signaling such as a ProvideAssitanceData message using LTE Positioning Protocol (LPP) . By reusing the existing signaling to transfer the time and frequency resources from the location server 430 to the group of base stations, no additional signaling is introduced to provide the backward compatibility. It is to be understood that any other suitable signaling may be used. With the time and frequency resources, the UE 410 may receive the group of PRSs from the group 440 of adjacent base stations in one beam direction 450.

In some example embodiments, the location server 430 may configure a group identity (ID) to the group 440 of adjacent base stations and send the group ID to the group 440 of adjacent base stations. Similar to the indication for indicating the time-domain and frequency-domain rsources, the group ID may be indicated to the base stations 420 using the LPP or any other suitable protocols.

In some example embodiments, the location server 430 may send an indication of the group ID towards the UE 410. The indication may also be included in the assistance data of the UE 410. In this way, when the number of base stations in the group 440 is larger and these base stations 420 are configured with more than one time-domain resources, the UE 410 can still determine, based on the group ID, that the same beam direction 450 would be used for receiving the PRSs from these base stations 420.

Based on the PRS configuration determined by the location server 430, the base stations 420 transmit the PRS on the configured time and frequency resources. The UE 410 receives the PRSs on the configured time and frequency resources by using Rx beamforming.

FIG. 6 shows a flowchart of an example method 600 in accordance with some example embodiments of the present disclosure. The method 600 can be implemented by the UE 410 as shown in FIG. 4. For the purpose of discussion, the method 600 will be described with reference to FIG. 4.

At block 605, the UE 410 receives, from the location server 420, an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group 440 of adjacent base stations. As described above, in some example embodiments, the indication may be received from the location server 430 via the serving cell in a PrivideAssistanceData message using LPP.

At block 610, the UE 410 determines a beam direction 450 for receiving the group of positioning reference signals. The beam direction may be determined by beam sweeping in a PRS receiving procedure. The UE 410 may determine the beam direction using any suitable beam training approach that already exists or will be developed in the future.

In some example embodiments, the Rx beamforming can be triggered on some conditions. For example, if the UE 410 is located outside the group 440, the Rx beamforming would be preferred. If the UE 410 is located inside of the group 440, an omnidirectional antenna would be better because the UE 410 cannot receive one group of PRS at the same time instance in one beam direction in this case.

The UE 410 may determine the location with respect to a group 440 of adjacent base stations 420 by measuring received signal strength of the group of PRSs from the base station 420. The received signal strength may comprise a signal to noise ratio (SNR) , for example. If the received signal strength of PRS is lower than the threshold strength, the UE 410 can be determined to be outside of the group 440. Then, the Rx beamforming is triggered to facilitate the receiving of the group of PRSs to achieve the high hearability. If the received signal strength of the PRSs exceeds the threshold strength, the UE 410 would adaptive switch the RX antenna mode from a directional mode to an omnidirectional mode to improve the performance of PRS reception further to enhance the positioning accuracy.

In the example embodiments where the group IDs are configured for the individual groups of adjacent base stations, the UE 410 may determine the grouping of the base stations based on the group IDs. For example, the UE 410 may receive the group ID for the group 440 of adjacent base stations from the location server 430. Based on the group ID, the UE 410 can determine that one beam direction will be used to detect or receive a group of PRSs.

To reduce the overhead of beam sweeping, the UE 410 only needs to perform the beam sweeping once time for each group of PRSs. In the example embodiments where the group ID is indicated to the UE 410, the UE 410 may be aware of the relationship between the group 440 and the time-domain resource such as the transmission occasions to avoid duplicate beam sweeping. The configuration of group ID may save energy at the UE 410 by avoiding repeated the Rx beam sweeping procedure.

FIG. 7 shows example usage of a group ID in accordance with some example embodiments of the present disclosure.

As shown, the UE 410 receives PRSs from Group#1 on a time occasion 705 and a time occasion 710 in the same beam direction 450-1. The UE 410 receives PRSs from Group#2 on a time occasion 715 in a beam direction 450-2.

Still with reference to FIG. 6, at block 615, the UE 410 receives the group of positioning reference signals in the beam direction 450 on the time-domain resource and the group of frequency-domain resources.

FIG. 8 shows a flowchart of an example method 800 in accordance with some example embodiments of the present disclosure. The method 800 can be implemented by one of the base stations 420 as shown in FIG. 4. For the purpose of discussion, the method 800 will be described with reference to FIG. 4.

At block 805, the base station 420 receives, from the location server 420, an indication for indicating at least a time-domain resource and a frequency-domain resource for transmitting a PRS. In some example embodiments, the indication may be received from the location server 430 by using LPPa or any other suitable protocols.

In some example embodiments, the indicated time-domain resource may be one of at least one time-domain resource allocated by the location server 430 for a group of positioning reference signals to be transmitted by a group 440 of adjacent base stations. The indicated frequency-domain resource may be a frequency-domain resource of a group of frequency-domain resources allocated by the location server 430 for the group 440 of adjacent base stations.

In some example embodiments, the indication may indicate to the base station 420 the time-domain and frequency-domain resources allocated for the whole group 440. It would be possible that the indication indicates other configurations related to the base station 420.

At block 810, the base station 420 transmits the PRS on the time-domain resource and the frequency-domain resource.

In some example embodiments, the base station 420 may receive an indication of a group ID for the group 440 of adjacent base stations from the location server 430. The indication may also be received by using LPPa or any other suitable protocols.

In some example embodiments, the base station 420 may send geographical information, such as its geographical coordinate, to the location server 430. Accordingly, the location server 430 may determine which base stations can be clustered into a goup 440 based on the geographical locations of the individual base stations 420.

All operations and features as described above with reference to FIGS. 4 to 7 are likewise applicable to the method 800 and have similar effects. For the purpose of simplification, the details will be omitted.

FIG. 9 shows an example signaling flow 900 between the location server 430, the base stations 420 (for example, gNB) and the UE 410 according to some example embodiments of the present disclosure.

In the flow 900, the base stations 420 provide (905) geographical coordinates to the location server 430. The location server 430 determines (910) PRS grouping and PRS resource configurations. The location server 430 indicates (915) the PRS configurations to the respective groups of base stations 420. The location server 430 also indicates (920) the PRS configurations to the UE 410. The base stations 420 perform (925) PRS transmission using the PRS resource configurations. The UE 410 performs (930) PRS receiving, accordingly.

FIG. 10 shows an example scenario 1000 of grouping-based PRS transmission according to some example embodiments of the present disclosure.

As shown, three adjacent base stations 420-1, 420-2 and 420-3 (labeled as gNB#1, gNB#2, gNB#3) form one group 440-1 (labeled as group #1) . Three adjacent base stations 420-4, 420-5 and 420-6 (labeled as gNB#4, gNB#5, gNB#6) for another group 440-2 (labeled as group #2) . These two groups are allocated to

different transmission occasions

1005 and 1010. The PRSs of group #1 (gNB#1, gNB#2, gNB#3) are simultaneously transmitted on the transmission occasion 1005, and the PRSs of group #2 (gNB#4, gNB#5, gNB#6) are also simultaneously transmitted one the transmission occasion 1010. The PRSs of the base stations 410 in one group 440 are transmitted on the different frequencies such as

sub-carriers

1015, 1020 and 1025.

In this scenario 1000, the UE 410 is outside of the groups 440-1 and 440-2. Thus, the Rx beamforming is triggered at the UE 410. The UE 410 may use one beam direction 450-1 to receive one group of PRSs at one transmission occasion 1005 and use another beam direction 450-2 to receive another group of PRSs at another transmission occasion 1010.

FIG. 11 shows an example scenario 1100 of grouping-based PRS transmission according to some other example embodiments of the present disclosure.

In the scenario 1100, the grouping of the base stations and the PRS mapping per group is the same as the scenario 1000. For the purpose of simplicity, the details thereof will not be repeated. As shown, in this example, the UE 410 is located inside the group 440-1. In this case, the UE 410 may detect that the receiving SNRs of PRSs are higher. Then, the UE 410 uses the omnidirectional antenna to receive the PRSs from the group 440-1 on the transmission occasion 1005 in an omnidirectional mode 1105.

For the PRSs of the group 440-2, the UE could still use the Rx beamforming in the beam direction 450-2 since the UE is outside of the group 440-2. For example, the UE 410 may determine that the measured SNRs of the PRSs from the group 440-2 are lower than a threshold SNR, and the Rx beamforming could be triggered to improve the PRS hearability and positioning accuracy. Accordingly, a group of PRSs can be received from the group 440-2 of base stations at one time instance.

The grouping-based PRS resource configuration mechanism can be used in the case that the UE 410 is located outside of any group 440, in order to receive one group of PRSs at one time by using the Rx beamforming. This mechanism can also be used in the case that the UE 410 is located inside one group 440 of base stations. In this case, the UE 410 may switch the antenna mode from a directional antenna to the omnidirectional antenna for PRS reception according to the measured SNR to guarantee the PRS receiving performance.

FIG. 12 is a simplified block diagram of a device 1200 that is suitable for implementing embodiments of the present disclosure. The device 1200 can be implemented by the location server 430, the UE 410 or the base station 420 as shown in FIG. 4.

As shown, the device 1200 includes a processor 1210, a memory 1220 coupled to the processor 1210, a communication module 1230 coupled to the processor 1210, and a communication interface (not shown) coupled to the communication module 1230. The memory 1220 stores at least a program 1240. The communication module 1230 is for bidirectional communications, for example, via multiple antennas. The communication interface may represent any interface that is necessary for communication.

The program 1240 is assumed to include program instructions that, when executed by the associated processor 1210, enable the device 1200 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to FIGS. 4-11. The embodiments herein may be implemented by computer software executable by the processor 1210 of the device 1200, or by hardware, or by a combination of software and hardware. The processor 1210 may be configured to implement various embodiments of the present disclosure.

The memory 1220 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 1220 is shown in the device 1200, there may be several physically distinct memory modules in the device 1200. The processor 1210 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1200 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

When the device 1200 acts as the location server 430 or a part of the location server 430, the processor 1210 and the communication module 1230 may cooperate to implement the method 500 as described above with reference to FIG. 5. When the device 1200 acts as the UE 410 or a part of the UE 410, the processor 1210 and the communication module 1230 may cooperate to implement the method 600 as described above with reference to FIG. 6. When the device 1200 acts as the base station 420 or a part of the base station 420, the processor 1210 and the communication module 1230 may cooperate to implement the method 800 as described above with reference to FIG. 8. All operations and features as described above with reference to FIGS. 4-11 are likewise applicable to the device 1200 and have similar effects. For the purpose of simplification, the details will be omitted.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the

methods

500, 600 and 800 as described above with reference to FIGS. 4-8. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable media and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , Digital Versatile Disc (DVD) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Various embodiments of the techniques have been described. In addition to or as an alternative to the above, the following examples are described. The features described in any of the following examples may be utilized with any of the other examples described herein.

In some aspects, a location server comprises: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the location server to: determine a group of adjacent base stations based on geographical locations of the base stations; allocate at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by the group of adjacent base stations; and send an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.

In some example embodiments, the location server is caused to determine the group of adjacent base stations by: receiving, from a plurality of base stations, geographical information about the plurality of base stations; determining, based on the received geographical information, that the plurality of base stations are adjacent; and clustering the plurality of base stations into the group of adjacent base stations.

In some example embodiments, one of the at least one time-domain resource comprises a time occasion of a positioning reference signal in a time domain.

In some example embodiments, a frequency-domain resource in the group of frequency-domain resources comprises at least one of a subcarrier, a sub-band and a bandwidth part in a frequency domain.

In some example embodiments, the location server is further caused to: send an indication for indicating the at least one time-domain resource and the group of frequency-domain resources towards user equipment.

In some example embodiments, the location server is further caused to: allocate a group identity for the group of adjacent base stations; and send an indication of the group identity to the group of adjacent base stations.

In some example embodiments, the location server is further caused to: send an indication of the group identity towards user equipment.

In some aspects, user equipment comprises: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the user equipment to: receive, from a location server, an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group of adjacent base stations; determine a beam direction for receiving the group of positioning reference signals; and receive the group of positioning reference signals in the beam direction on the time-domain resource and the group of frequency-domain resources.

In some example embodiments, the user equipment is caused to determine the beam direction by: measuring received signal strength of the group of positioning reference signals; determining whether the received signal strength is lower than threshold strength; and in response to determining that the received signal strength is lower than the threshold strength, determining the beam direction for receiving the group of positioning reference signals.

In some example embodiments, the user equipment is further caused to: in response to determining that the received signal strength exceeds the threshold strength, receive the group of positioning reference signals using an omnidirectional antenna.

In some example embodiments, the user equipment is further caused to: receive from the location server, an indication of a group identity for the group of adjacent base stations.

In some aspects, a base station comprises: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the base station to: receive, from a location server, an indication for indicating at least a time-domain resource and a frequency-domain resource for transmitting a position reference signal and transmit the position reference signal on the time-domain resource and the frequency-domain resource.

In some example embodiments, the time-domain resource comprises one of at least one time-domain resource allocated by the location server for a group of positioning reference signals to be transmitted by a group of adjacent base stations, and the frequency-domain resource comprises a frequency-domain resource of a group of frequency-domain resources allocated by the location server for the group of positioning reference signals.

In some example embodiments, the base station is further caused to: receive, from the location server, an indication of a group identity for the group of adjacent base stations.

In some example embodiments, the base station is further caused to: send, to the location server, geographical information about the base station.

In some aspects, a method comprises: determining, by a location server, a group of adjacent base stations based on geographical locations of the base stations; allocating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by the group of adjacent base stations; and sending an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.

In some example embodiments, determining the group of adjacent base stations comprises: receiving, from a plurality of base stations, geographical information about the plurality of base stations; determining, based on the received geographical information, that the plurality of base stations are adjacent; and clustering the plurality of base stations into the group of adjacent base stations.

In some example embodiments, the method further comprises: sending an indication for indicating the at least one time-domain resource and the group of frequency-domain resources towards user equipment.

In some example embodiments, the method further comprises: allocating a group identity for the group of adjacent base stations; and sending an indication of the group identity to the group of adjacent base stations.

In some example embodiments, the method further comprises: sending an indication of the group identity towards user equipment.

In some aspects, a method comprises: receiving, by user equipment, from a location server, an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group of adjacent base stations; determining a beam direction for receiving the group of positioning reference signals; and receiving the group of positioning reference signals in the beam direction on the time-domain resource and the group of frequency-domain resources.

In some example embodiments, determining the beam direction comprises: measuring received signal strength of the group of positioning reference signals; determining whether the received signal strength is lower than threshold strength; and in response to determining that the received signal strength is lower than the threshold strength, determining the beam direction for receiving the group of positioning reference signals.

In some example embodiments, the method further comprises: in response to determining that the received signal strength exceeds the threshold strength, receiving the group of positioning reference signals using an omnidirectional antenna.

In some example embodiments, the method further comprises: receiving, from the location server, an indication of a group identity for the group of adjacent base stations.

In some example embodiments, a method comprises: receiving, by a base station, from a location server, an indication for indicating at least a time-domain resource and a frequency-domain resource for transmitting a position reference signal; and transmitting the position reference signal on the time-domain resource and the frequency-domain resource.

In some example embodiments, the method further comprises: sending, to the location server, geographical information about the base station.

In some aspects, an apparatus comprises: means for determining, by a location server, a group of adjacent base stations based on geographical locations of the base stations; means for allocating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by the group of adjacent base stations; and means for sending an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.

In some example embodiments, the means for determining the group of adjacent base stations comprises: means for receiving, from a plurality of base stations, geographical information about the plurality of base stations; means for determining, based on the received geographical information, that the plurality of base stations are adjacent; and means for clustering the plurality of base stations into the group of adjacent base stations.

In some example embodiments, the apparatus further comprises: means for sending an indication for indicating the at least one time-domain resource and the group of frequency-domain resources towards user equipment.

In some example embodiments, the apparatus further comprises: means for allocating a group identity for the group of adjacent base stations; and means for sending an indication of the group identity to the group of adjacent base stations.

In some example embodiments, the apparatus further comprises: means for sending an indication of the group identity towards user equipment.

In some aspects, an apparatus comprises: means for receiving, by user equipment, from a location server, an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group of adjacent base stations; means for determining a beam direction for receiving the group of positioning reference signals; and means for receiving the group of positioning reference signals in the beam direction on the time-domain resource and the group of frequency-domain resources.

In some example embodiments, the means for determining the beam direction comprises: means for measuring received signal strength of the group of positioning reference signals; means for determining whether the received signal strength is lower than threshold strength; and means for in response to determining that the received signal strength is lower than the threshold strength, determining the beam direction for receiving the group of positioning reference signals.

In some example embodiments, the apparatus further comprises: means for in response to determining that the received signal strength exceeds the threshold strength, receiving the group of positioning reference signals using an omnidirectional antenna.

In some example embodiments, the apparatus further comprises: means for receiving, from the location server, an indication of a group identity for the group of adjacent base stations.

In some example embodiments, an apparatus comprises: means for receiving, by a base station, from a location server, an indication for indicating at least a time-domain resource and a frequency-domain resource for transmitting a position reference signal; and means for transmitting the position reference signal on the time-domain resource and the frequency-domain resource.

In some example embodiments, the apparatus further comprises: means for sending, to the location server, geographical information about the base station.

In some aspects, a computer readable storage medium comprises program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method according to some example embodiments of the present disclosure.

Claims

A location server, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the location server to:

determine a group of adjacent base stations based on geographical locations of the base stations;

allocate at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by the group of adjacent base stations; and

send an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.
The location server of claim 1, wherein the location server is caused to determine the group of adjacent base stations by:

receiving, from a plurality of base stations, geographical information about the plurality of base stations;

determining, based on the received geographical information, that the plurality of base stations are adjacent; and

clustering the plurality of base stations into the group of adjacent base stations.
The location server of claim 1, wherein one of the at least one time-domain resource comprises a time occasion of a positioning reference signal in a time domain.
The location server of claim 1, wherein a frequency-domain resource in the group of frequency-domain resources comprises at least one of a subcarrier, a sub-band and a bandwidth part in a frequency domain.
The location server of claim 1, wherein the location server is further caused to:

send an indication for indicating the at least one time-domain resource and the group of frequency-domain resources towards user equipment.
The location server of claim 1, wherein the location server is further caused to:

allocate a group identity for the group of adjacent base stations; and

send an indication of the group identity to the group of adjacent base stations.
The location server of claim 6, wherein the location server is further caused to:

send an indication of the group identity towards user equipment.
User equipment, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the user equipment to:

receive, from a location server, an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group of adjacent base stations;

determine a beam direction for receiving the group of positioning reference signals; and

receive the group of positioning reference signals in the beam direction on the time-domain resource and the group of frequency-domain resources.
The user equipment of claim 8, wherein the user equipment is caused to determine the beam direction by:

measuring received signal strength of the group of positioning reference signals;

determining whether the received signal strength is lower than threshold strength; and

in response to determining that the received signal strength is lower than the threshold strength, determining the beam direction for receiving the group of positioning reference signals.
The user equipment of claim 9, wherein the user equipment is further caused to:

in response to determining that the received signal strength exceeds the threshold strength, receive the group of positioning reference signals using an omnidirectional antenna.
The user equipment of claim 8, wherein the user equipment is further caused to:

receive, from the location server, an indication of a group identity for the group of adjacent base stations.
A base station, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the base station to:

receive, from a location server, an indication for indicating at least a time-domain resource and a frequency-domain resource for transmitting a position reference signal; and

transmit the position reference signal on the time-domain resource and the frequency-domain resource.
The base station of claim 12, wherein the time-domain resource comprises one of at least one time-domain resource allocated by the location server for a group of positioning reference signals to be transmitted by a group of adjacent base stations, and the frequency-domain resource comprises a frequency-domain resource of a group of frequency-domain resources allocated by the location server for the group of positioning reference signals.
The base station of claim 12, wherein the base station is further caused to:

receive, from the location server, an indication of a group identity for the group of adjacent base stations.
The base station of claim 12, wherein the base station is further caused to:

send, to the location server, geographical information about the base station.
A method comprising:

determining, by a location server, a group of adjacent base stations based on geographical locations of the base stations;

allocating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by the group of adjacent base stations; and

sending an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.
The method of claim 16, wherein determining the group of adjacent base stations comprises:

receiving, from a plurality of base stations, geographical information about the plurality of base stations;

determining, based on the received geographical information, that the plurality of base stations are adjacent; and

clustering the plurality of base stations into the group of adjacent base stations.
The method of claim 16, wherein one of the at least one time-domain resource comprises a time occasion of a positioning reference signal in a time domain.
The method of claim 16, wherein a frequency-domain resource in the group of frequency-domain resources comprises at least one of a subcarrier, a sub-band and a bandwidth part in a frequency domain.
The method of claim 16, further comprising:

sending an indication for indicating the at least one time-domain resource and the group of frequency-domain resources towards user equipment.
The method of claim 16, further comprising:

allocating a group identity for the group of adjacent base stations; and

sending an indication of the group identity to the group of adjacent base stations.
The method of claim 16, further comprising:

sending an indication of the group identity towards user equipment.
A method comprising:

receiving, by user equipment, from a location server, an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group of adjacent base stations;

determining a beam direction for receiving the group of positioning reference signals; and

receiving the group of positioning reference signals in the beam direction on the time-domain resource and the group of frequency-domain resources.
The method of claim 23, wherein determining the beam direction comprises:

measuring received signal strength of the group of positioning reference signals;

determining whether the received signal strength is lower than threshold strength; and

in response to determining that the received signal strength is lower than the threshold strength, determining the beam direction for receiving the group of positioning reference signals.
The method of claim 24, further comprising:

in response to determining that the received signal strength exceeds the threshold strength, receiving the group of positioning reference signals using an omnidirectional antenna.
The method of claim 23, further comprising:

receiving, from the location server, an indication of a group identity for the group of adjacent base stations.
A method, comprising:

receiving, by a base station, from a location server, an indication for indicating at least a time-domain resource and a frequency-domain resource for transmitting a position reference signal; and

transmitting the position reference signal on the time-domain resource and the frequency-domain resource.
The method of claim 27, wherein the time-domain resource comprises one of at least one time-domain resource allocated by the location server for a group of positioning reference signals to be transmitted by a group of adjacent base stations, and the frequency-domain resource comprises a frequency-domain resource of a group of frequency-domain resources allocated by the location server for the group of positioning reference signals.
The method of claim 27, further comprising:

receiving, from the location server, an indication of a group identity for the group of adjacent base stations.
The method of claim 27, further comprising:

sending, to the location server, geographical information about the base station.
An apparatus comprising:

means for determining, by a location server, a group of adjacent base stations based on geographical locations of the base stations;

means for allocating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by the group of adjacent base stations; and

means for sending an indication for indicating the at least one time-domain resource and the group of frequency-domain resources to the group of adjacent base stations.
An apparatus comprising:

means for receiving, by user equipment, from a location server, an indication for indicating at least one time-domain resource and a group of frequency-domain resources for a group of positioning reference signals to be transmitted by a group of adjacent base stations;

means for determining a beam direction for receiving the group of positioning reference signals; and

means for receiving the group of positioning reference signals in the beam direction on the time-domain resource and a group of frequency-domain resources.
An apparatus comprising:

means for receiving, by a base station, from a location server, an indication for indicating a time-domain resource and a frequency-domain resource for transmitting a position reference signal; and

means for transmitting the position reference signal on the time-domain resource and the frequency-domain resource.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 16-22.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 23-26.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 27-30.