Patent Description:
An example of a cellular communication system is an architecture that is being standardized by the 3rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node AP or Evolved Node B (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations are referred to as user equipments (UE). LTE has included a number of improvements or developments.

<NUM> New Radio (NR) development is part of a continued mobile broadband evolution process to meet the requirements of <NUM>, similar to earlier evolution of <NUM> & <NUM> wireless networks. In addition, <NUM> is also targeted at the new emerging use cases in addition to mobile broadband. A goal of <NUM> is to provide significant improvement in wireless performance, which may include new levels of data rate, latency, reliability, and security. <NUM> NR may also scale to efficiently connect the massive Internet of Things (IoT), and may offer new types of mission-critical services. Ultra-reliable and low-latency communications (URLLC) devices may require high reliability and very low latency. <NPL> discusses observed time difference of arrival (OTDOA) related techniques. It is proposed that when measuring reference signal time difference (RSTD) from different reference signal beam, a user equipment should consider removing the time difference between different receiving beams. <CIT> discloses techniques for range measurement between one or more wireless stations and a first access point. The clocks are synchronized between the access points. The access point transmits to the wireless station one or more broadcast time of departure frames, each of them including a time of departure of the frame from the first access point.

A method, according to claim <NUM>, apparatus, according to claim <NUM>, and a computer-readable storage medium, according to claim <NUM>, are provided for correcting time of departure of positioning reference signals (PRRs) used in estimating location of a user equipment in wireless networks. In particular, the method includes receiving, by a user equipment (UE), one or more positioning reference signals (PRSs) from each cell of a plurality of cells. In the method, a second positioning reference signal (PRS) of the one or more positioning reference signals (PRSs) from a cell of the plurality of cells includes a second time of departure of the second positioning reference signal (PRS), the second time of departure being relative to a first time of departure of a first reference positioning reference signal (PRS) received from the cell, the first reference positioning reference signal (PRS) being a reference positioning reference signal (PRS) of the plurality of one or more positioning reference signals (PRSs) that is transmitted first from the cell. The method further includes determining, by the user equipment (UE), arrival times of positioning reference signals (PRSs) from different cells of the plurality of cells; and transmitting, by the user equipment (UE), reference signal time difference (RSTD) values, a reference signal time difference (RSTD) value of the reference signal time difference (RSTD) values being determined based at least on the first and second times of departure and the arrival times of positioning reference signals (PRSs) from different cells of the plurality of cells.

<FIG> is a block diagram of a wireless network <NUM> according to an example implementation. In the wireless network <NUM> of <FIG>, user devices (UDs) <NUM>, <NUM>, <NUM> and <NUM>, which may also be referred to as mobile stations (MSs) or user equipment (UEs), may be connected (and in communication) with a base station (BS) <NUM>, which may also be referred to as an access point (AP), an enhanced Node B (eNB) or a network node. At least part of the functionalities of an access point (AP), base station (BS) or (e)Node B (eNB) may also be carried out by any node, server or host which may be operably coupled to a transceiver, such as a remote radio head. BS (or AP) <NUM> provides wireless coverage within a cell <NUM>, including to user devices <NUM>, <NUM>, <NUM> and <NUM>. Although only four user devices are shown as being connected or attached to BS <NUM>, any number of user devices may be provided. BS <NUM> is also connected to a core network <NUM> via a S1 interface <NUM>. This is merely one simple example of a wireless network, and others may be used.

A user device (user terminal, user equipment (UE)) may refer to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and/or touch screen computer, a tablet, a phablet, a game console, a notebook, and a multimedia device, as examples, or any other wireless device.

In addition, by way of illustrative example, the various example implementations or techniques described herein may be applied to various types of user devices or data service types, or may apply to user devices that may have multiple applications running thereon that may be of different data service types. New Radio (<NUM>) development may support a number of different applications or a number of different data service types, such as for example: machine type communications (MTC), enhanced machine type communication (eMTC), Internet of Things (IoT), and/or narrowband IoT user devices, enhanced mobile broadband (eMBB), and ultra-reliable and low-latency communications (URLLC).

IoT may refer to an ever-growing group of objects that may have Internet or network connectivity, so that these objects may send information to and receive information from other network devices. For example, many sensor type applications or devices may monitor a physical condition or a status, and may send a report to a server or other network device, e.g., when an event occurs. Machine Type Communications (MTC or machine to machine communications) may, for example, be characterized by fully automatic data generation, exchange, processing and actuation among intelligent machines, with or without intervention of humans. Enhanced mobile broadband (eMBB) may support much higher data rates than currently available in LTE.

Ultra-reliable and low-latency communications (URLLC) is a new data service type, or new usage scenario, which may be supported for New Radio (<NUM>) systems. This enables emerging new applications and services, such as industrial automations, autonomous driving, vehicular safety, e-health services, and so on. 3GPP targets in providing up to e.g., <NUM> U-Plane (user/data plane) latency connectivity with <NUM>-1e-<NUM> reliability, by way of an illustrative example. Thus, for example, URLLC user devices/UEs may require a significantly lower block error rate than other types of user devices/UEs as well as low latency. Thus, for example, a URLLC UE (or URLLC application on a UE) may require much shorter latency, as compared to a eMBB UE (or an eMBB application running on a UE).

The various example implementations may be applied to a wide variety of wireless technologies or wireless networks, such as LTE, LTE-A, <NUM>, IoT, MTC, eMTC, eMBB, URLLC, etc., or any other wireless network or wireless technology. These example networks, technologies or data service types are provided only as illustrative examples.

Multiple Input, Multiple Output (MIMO) may refer to a technique for increasing the capacity of a radio link using multiple transmit and receive antennas to exploit multipath propagation. MIMO may include the use of multiple antennas at the transmitter and/or the receiver. MIMO may include a multi-dimensional approach that transmits and receives two or more unique data streams through one radio channel. For example, MIMO may refer to a technique for sending and receiving more than one data signal simultaneously over the same radio channel by exploiting multipath propagation. According to an illustrative example, multi-user multiple input, multiple output (multi-user MIMIO, or MU-MIMO) enhances MIMO technology by allowing a base station (BS) or other wireless node to simultaneously transmit or receive multiple streams to different user devices or UEs, which may include simultaneously transmitting a first stream to a first UE, and a second stream to a second UE, via a same (or common or shared) set of physical resource blocks (PRBs) (e.g., where each PRB may include a set of time-frequency resources).

Also, a BS may use precoding to transmit data to a UE (based on a precoder matrix or precoder vector for the UE). For example, a UE may receive reference signals or pilot signals, and may determine a quantized version of a DL channel estimate, and then provide the BS with an indication of the quantized DL channel estimate. The BS may determine a precoder matrix based on the quantized channel estimate, where the precoder matrix may be used to focus or direct transmitted signal energy in the best channel direction for the UE. Also, each UE may use a decoder matrix to determine, e.g., where the UE may receive reference signals from the BS, determine a channel estimate of the DL channel, and then determine a decoder matrix for the DL channel based on the DL channel estimate. For example, a precoder matrix may indicate antenna weights (e.g., an amplitude/gain and phase for each weight) to be applied to an antenna array of a transmitting wireless device. Likewise, a decoder matrix may indicate antenna weights (e.g., an amplitude/gain and phase for each weight) to be applied to an antenna array of a receiving wireless device. This applies to UL as well when a UE is transmitting data to a BS.

For example, according to an example aspect, a receiving wireless user device may determine a precoder matrix using Interference Rejection Combining (IRC) in which the user device may receive reference signals (or other signals) from a number of BSs (e.g., and may measure a signal strength, signal power, or other signal parameter for a signal received from each BS), and may generate a decoder matrix that may suppress or reduce signals from one or more interferers (or interfering cells or BSs), e.g., by providing a null (or very low antenna gain) in the direction of the interfering signal, in order to increase a signal-to interference plus noise ratio (SINR) of a desired signal. In order to reduce the overall interference from a number of different interferers, a receiver may use, for example, a Linear Minimum Mean Square Error Interference Rejection Combining (LMMSE-IRC) receiver to determine a decoding matrix. The IRC receiver and LMMSE-IRC receiver are merely examples, and other types of receivers or techniques may be used to determine a decoder matrix. After the decoder matrix has been determined, the receiving UE/user device may apply antenna weights (e.g., each antenna weight including amplitude and phase) to a plurality of antennas at the receiving UE or device based on the decoder matrix. Similarly, a precoder matrix may include antenna weights that may be applied to antennas of a transmitting wireless device or node. This applies to a receiving BS as well.

The present disclosure is related to Observed Time Difference of Arrival (OTDOA) and/or as Downlink Time Difference of Arrival (DL-TDOA) positioning based on specific reference signals, referred to as positioning reference signals (PRSs), used exclusively for positioning purposes in wireless networks.

The PRSs are transmitted from separate physical location points (e.g., cells, base stations, transmission points, gNB, etc.) and are measured by a user equipment (UE) with respect to differences in arrival times at the UE. That is, a UE measures the time differences in the arrival of two PRSs (e.g., PRS <NUM> and PRS <NUM>) and reports the respective reference signal time difference (RSTD) value that equals the time difference of arrival corresponding to the two PRSs to the network. Then, based on this report and other additional reports associated with other physical location points, the network may be able to estimate the location of the UE.

However, the procedure described above to determine OTDOA and/or DL-TDOA is time-sensitive. For example, the location of the UE is estimated based on the reported time of arrival, or more precisely, time difference of arrival of PRSs. This implies that the PRSs should be transmitted from different physical location points in a synchronized manner. But, if the PRSs are not completely synchronized, the network should know, at least, the time difference of transmission of the respective PRSs so that the network can correct the differences when generating a reference signal time difference (RSTD) report.

In LTE, such synchronization is relatively easy since a) the location server (e.g., located at the core network) is aware of the potential synchronization differences of the different transmission points and therefore corrections to the RSTD values can be made; and b) each transmission point transmits a single PRS. However, in New Radio (NR)/<NUM>, features such as beam-specific PRS and/or dynamic PRS complicate this process.

For example, in <NUM>/NR, multiple PRSs may be transmitted from a transmission point, with each PRS corresponding to a different beam, where such different beams are transmitted in different time instances according to a process known as "beam sweeping. " That is, in beamformed systems, each beam, transmitted at a distinct time instance and sequentially one after another, conveys a separate PRS, associated with a different PRS ID. A downlink (DL) PRS resource may be defined as a set of resource elements used for NR DL PRS transmission that can span multiple PRBs within one or more consecutive symbol(s) within a slot. For NR DL PRS resource design, a PRS resource should have a PRS resource ID and a PRS sequence should have a PRS sequence ID. A typical assumption is that PRS resource IDs transmitted by the same physical location are assigned the same PRS sequence ID.

The transmission of multiple PRSs per transmission point by means of beam-specific PRS IDs results in a non-efficient resource usage. In this regard, there is a need that PRSs are configured and transmitted in a dynamic fashion. This means that in situations where higher accuracy is needed, the PRSs are transmitted with increased resources, e.g., higher bandwidth and/or periodicity. More importantly, since in beamformed scenarios PRSs are sent in a beam-sweeping manner, less or even zero PRS resources should be allocated to beams which do not correspond to any UE requesting a positioning service. In other words, this means that NR should be able to exclude certain beams from transmitting PRS at given time instances, resulting in an overall non-uniform allocation of PRS across beams.

There are various problems associated with dynamic PRS allocation in beamformed setups. For instance, in dynamic PRS scenarios, the time sequence of PRS IDs across different beams is not static. This means that the UE does not know (nor can it straightforwardly infer) the time sequence of the PRS IDs. As a result, the UE is not aware of the transmission time of the PRS IDs it receives, such that even if it forms the RSTD based on the time-difference of the reception time of such received PRS IDs, this RSTD cannot be used as such unless additional processing is applied.

It is noted that if the feature of dynamic PRS is not included, but instead there is a static PRS allocation, then the problem of correcting the transmission times of PRS transmitted from different beams would still exist. This is because there will still be differences in the transmission times of different PRS resource IDs.

The present disclosure proposes a mechanism that would assign the PRS Resource IDs in a sequential manner, and transmit the sequence of PRS Resource IDs via the LPP protocol as part of the location assistance information. In one example implementation, the technical solution to the problem described above may include a method that provides the UE with the necessary information for correcting the time-difference of departure of the PRS Resource IDs the UE receives. The inventive step thus relates to adding to the PRS Resource IDs additional information which reflects the time of departure of the given PRS Resource ID. In another example implementation, this information on the time of departure of the respective PRS Resource IDs may be encoded into the PRS Resource ID number itself.

<FIG> is a block diagram illustrating transmission of positioning reference signals (PRSs) from a cell (e.g., cell <NUM>), according to an example implementation. In some implementations, the cell may be also referred to as a base station, physical location point, transmission point, gNB (next generation NB/gNB or <NUM> NB), or an eNB.

As shown in <FIG>, cell <NUM> may be configured to transmit one or more PRSs. In an example implementation, cell <NUM> may be configured to transmit PRSs <NUM>-<NUM>. Each of the PRSs <NUM>-<NUM> may be associated with different PRS Resource IDs and may be further associated with different beams transmitted from the cell. For example, in a beamformed system as shown in <FIG>, the beams may be transmitted from the cell one after the other and each beam may transmit its own PRS and associated with a different PRS Resource ID. In some implementations, the beams may be transmitted in a beam sweeping order which indicates that the beams (and therefore the PRSs) are transmitted in a given order. In the present disclosure, the term PRS may be interchangeably used with PRS Resource ID. For example, PRS <NUM> may be also referred to as PRS resource ID <NUM>, etc..

In addition, in some implementations, PRS Resource IDs may be associated with a PRS Cell ID. For example, PRS Resource IDs <NUM>-<NUM> may be associated with PRS Cell ID # <NUM>, as shown in <FIG>. That is, a set of PRS Resource IDs may be grouped together as a set and associated with a PRS Cell ID (e.g., Cell ID value of <NUM>). In some implementations, this may allow for indicating a time of departure (or time of departure information) of a PRS Resource ID, from a cell, in relative terms (and not in absolute terms). In other words, the time of departure of a PRS/PRS Resource ID may be expressed as time of departure relative to a time of departure of a first PRS Resource ID transmitted from the cell and the number of time units (e.g., milliseconds, ms) between consecutive PRS Resource IDs of a PRS Cell ID. In some implementations, the PRS Cell ID may be referred to as PRS Cell identifier, PRS Sequence ID, etc. In some implementations, the association between PRS Resource ID, PRS Cell ID, and relative time information may be relayed to a UE via Observed Time Difference of Arrival (OTDOA) in LTE or Downlink Time Difference of Arrival (DL-TDOA) assistance information in <NUM>/LTE.

In some implementations, although cell <NUM> is configured to support transmitting PRSs <NUM>-<NUM>, cell <NUM> (PRS Cell ID # <NUM>) may not transmit all PRSs (PRSs <NUM>-<NUM>) all the time. Cell <NUM>, in some implementations, may support transmitting PRSs in a dynamic manner. For example, in some implementations, cell <NUM> may transmit PRS Resource IDs <NUM>, <NUM>, and <NUM>, as shown in <FIG>. In other words, in some implementations, cell <NUM> may skip transmitting some beams (and therefore corresponding PRSs) from the cell.

In some implementations, a PRS/PRS Resource ID transmitted from a cell may include (or convey) the following information: i) a PRS Cell ID associated with the PRS Resource ID and ii) time of departure of the PRS Resource ID from the cell. The time of departure of the PRS Resource ID may be indicated as a time of departure relative to a time of departure of a first PRS Resource ID that is transmitted from the cell (e.g., time of departure of a PRS Resource ID relative to a time of departure of a PRS Resource ID <NUM> (in the example scenario of <FIG>) that is transmitted first from the cell (e.g., prior to any other PRS Resource IDs from transmitted from the cell).

In some implementations, for example, as shown in <FIG>, cell <NUM> may transmit PRSs/PRS Resource IDs <NUM>, <NUM>, and <NUM>, in a dynamic manner and in a beam sweeping order. For example, PRS Resource ID <NUM> may include information that PRS resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be zero as PRS Resource ID <NUM> is the first PRS Resource ID transmitted from cell <NUM>. It should be noted that, although cell <NUM> may be configured with ten PRSs (PRSs <NUM>-<NUM>), only PRSs <NUM>, <NUM>, and <NUM> are transmitted from PRS Cell ID # <NUM> at a given occasion, e.g., a PRS positioning occasion. In some implementations, for example, in another positioning occasion, the PRSs transmitted from PRS Cell ID #<NUM> may change, for instance, from PRSs <NUM>, <NUM>, and <NUM> to PRSs <NUM> and <NUM> depending on the number (e.g., less or more) of UEs in the area requesting positioning services. In some implementations, for example, PRS Resource ID <NUM> may include information that PRS Resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be 1X as PRS Resource ID <NUM> is the second PRS Resource ID transmitted from PRS Cell ID <NUM>, where X represents the time difference between consecutive PRS Resource ID transmissions from PRS Cell ID # <NUM>. Similarly, in some implementations, for example, PRS Resource ID <NUM> may include information that PRS Resource ID <NUM> is associated with PRS Cell ID # <NUM> and the relative time of departure of PRS Resource ID <NUM>, which may be 2X as PRS Resource ID <NUM> is the third PRS Resource ID transmitted from PRS Cell ID # <NUM> (e.g., X representing the time difference between consecutive PRS Resource ID transmissions).

In some implementations, a PRS Resource ID may be modified such that the PRS Resource ID includes the value of a PRS Index (or a PRS Index value). The PRS Index may be considered as a counter which may be specific to each cell (e.g., specific to each PRS Cell ID) and/or to each PRS Resource ID. For example, the PRS Index may be an integer which may be increased by a value of one each time a new PRS Resource ID is transmitted from the cell. In some implementations, each time the first PRS Resource ID (also referred to as a reference PRS Resource ID) is transmitted from the cell, the PRS Index may be reset to zero.

In some implementations, the PRS Index may convey the time of departure information of a PRS Resource ID. The time of departure information may be relative to the time of departure of the reference PRS Resource ID (e.g., first PRS Resource ID transmitted from a cell prior to the transmission of any other PRS Resource IDs from the cell). In other words, each PRS Resource ID that is transmitted from a cell may contain information on how much time has elapsed after the transmission of first PRS Resource ID from the cell and before the current PRS Resource ID is being transmitted (in other words, time in between). For example, as shown in <FIG>, the PRS Index values transmitted from PRS Cell ID # <NUM> may be shown as below:.

The above examples indicate that PRS Resource IDs <NUM>, <NUM>, and <NUM> are transmitted from PRS Cell ID # <NUM> and that PRS Resource ID <NUM> is the first PRS Resource ID being transmitted from the cell. The PRS Index values <NUM>, <NUM>, and <NUM> indicate time differences of <NUM>, 1X, and 2X, based on a time difference of X (ms) between consecutive PRS transmissions from PRS Cell ID # <NUM>.

<FIG> is a block diagram illustrating transmission of positioning reference signals (PRSs) or PRS Resource IDs from a plurality of cells, e.g., cells <NUM>, <NUM>, and <NUM>, according to an example implementation.

In some implementations, UE <NUM> (which may be same or similar to user devices <NUM>-<NUM> of <FIG>) may receive PRSs from cells <NUM>, <NUM>, and/or <NUM>. A Location Server (also referred to as Location Management Function (LMF) in <NUM>/NR or a Gateway Mobile Location Centre (GMLC) in LTE) may rely on information from these cells (e.g., a serving cell and two neighbor cells) to estimate the location of the UE. In some implementations, a UE, e.g., UE <NUM>, may determine RSTD values and report them to a network entity (for example, via a serving cell) that resides in the core network. Such a core network entity, for example, may be referred to as a Location Server (e.g., Gateway Mobile Location Centre (GMLC) in LTE; Location Management Function (LMF) in <NUM>/NR). In addition to the information received from a UE, the Location Sever may rely on information related to the physical locations of the cells and calculate (e.g., determine, compute, etc.) the estimated location of a UE. It should be noted that the communication between a UE and a Location Server is established via Non-Access Stratum (NAS) of a serving cell of the UE (e.g., cell <NUM>/PRS Cell ID # <NUM>). In an example implementation, <FIG> illustrates PRSs/PRS Resource IDs transmitted from three cells, cells <NUM>, <NUM>, and <NUM> with PRS Cell IDs of <NUM>, <NUM>, and <NUM>, respectively. In some implementations, a UE may report RSTD values to a network entity that resides in the radio access network (RAN) which may be configured with location management capabilities as described above (for example, a local LMF residing in the RAN). In such example implementations, the communication between the UE and the RAN-based entity may be established, e.g., via Radio Resource Control (RRC) protocol.

In some implementations, for example, as shown in <FIG> (and described in detail in reference to <FIG> above), PRS Cell ID # <NUM> may transmit PRSs/PRS Resource IDs <NUM>, <NUM>, and <NUM>, in a dynamic manner and in a beam sweeping order. For example, PRS Resource ID <NUM> may include information that PRS resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be zero as PRS Resource ID <NUM> is the first PRS Resource ID transmitted from PRS Cell ID # <NUM>. It should be noted that, although PRS Cell ID # <NUM> may be configured with ten PRSs (PRSs <NUM>-<NUM>), only PRS Resource IDs <NUM>, <NUM>, and <NUM> may be transmitted from PRS Cell ID # <NUM> at a given occasion, e.g., a PRS positioning occasion. In some implementations, for example, in another positioning occasion, the PRSs transmitted from PRS Cell ID #<NUM> may change, for instance, from PRSs <NUM>, <NUM> and <NUM> to PRSs <NUM> and <NUM>, depending on the number (e.g., less or more) of UEs in the area requesting positioning services. In addition, in some implementations, for example, PRS Resource ID <NUM> may include information that PRS resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be 1X as PRS <NUM> is the second PRS Resource ID transmitted from PRS Cell ID # <NUM>, where X represents the time difference between consecutive PRS Resource ID transmissions of PRS Cell ID # <NUM>. Similarly, in some implementations, for example, PRS Resource ID <NUM> may include information that PRS resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be 2X as PRS <NUM> is the third PRS Resource transmitted from PRS Cell ID # <NUM> (X representing the time difference between consecutive PRS Resource ID transmissions of PRS Cell ID # <NUM>).

Similarly, in some implementations, for example, as shown in <FIG>, PRS Cell ID # <NUM> may transmit PRSs/PRS Resource IDs <NUM>, <NUM>, <NUM>, and <NUM>, in a dynamic manner and in a beam sweeping order. For example, PRS Resource ID <NUM> may include information that PRS Resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be zero as PRS <NUM> is the first PRS Resource ID transmitted from PRS Cell ID # <NUM>. It should be noted that, although PRS Cell ID # <NUM> may be configured to transmit ten PRSs (PRSs <NUM>-<NUM>), only PRSs <NUM>, <NUM>, <NUM>, and <NUM> are transmitted from PRS Cell ID # <NUM>, in the example implementation of <FIG>. In addition, in some implementations, for example, PRS Resource ID <NUM> may include information that PRS resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be 1Y as PRS Resource ID <NUM> is the second PRS Resource ID transmitted from PRS Cell ID # <NUM>, where Y represents the time difference between consecutive PRS Resource ID transmissions of PRS Cell ID # <NUM>. Similarly, in some implementations, for example, PRS Resource ID <NUM> may include information that PRS resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be 2Y as PRS <NUM> is the third PRS Resource ID transmitted from PRS Cell ID # <NUM> (Y representing the time difference between consecutive PRS Resource ID transmissions of PRS Cell ID # <NUM>).

Similarly, in some implementations, for example, as shown in <FIG>, PRS Cell ID # <NUM> may transmit PRSs/PRS Resource IDs <NUM> and <NUM>, in a dynamic manner and in a beam sweeping order. For example, PRS Resource ID <NUM> may include information that PRS Resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be zero as PRS Resource ID <NUM> is the first PRS Resource ID transmitted from PRS Cell ID # <NUM>. It should be noted that, although PRS Cell ID # 30may be transmitted with ten PRSs (PRSs <NUM>-<NUM>), only PRS Resource IDs <NUM> and <NUM> may be transmitted from PRS Cell ID # <NUM>. In addition, in some implementations, for example, PRS Resource ID <NUM> may include information that PRS resource ID <NUM> is associated with PRS Cell ID # <NUM> and relative time of departure of PRS Resource ID <NUM>, which may be 1Z as PRS <NUM> is the second PRS Resource ID transmitted from PRS Cell ID # <NUM>, where Z represents the time difference between consecutive PRS Resource ID transmissions of PRS Cell ID # <NUM>.

For example, in some implementations, UE <NUM> may receive PRS Resource IDs <NUM> and <NUM> from PRS Cell ID # <NUM> and PRS Cell ID # <NUM>, respectively (e.g., from cells <NUM> and <NUM>, respectively), as shown below:.

Upon receiving the above mentioned PRS Resource IDs, UE <NUM> may determine that PRS Resource ID <NUM> is transmitted second from PRS Cell ID # <NUM> nd PRS Resource ID <NUM> is transmitted second from Cell ID <NUM>. The PRS Resource IDs may further indicate X and Y values (e.g., via OTDOA/DL-TDOA assistance information) representing the time difference between consecutive PRS transmissions from PRS Cell ID # <NUM> and PRS Cell ID # <NUM>, respectively. UE <NUM> determines the arrival times of PRS Resource ID <NUM> and PRS Resource <NUM> as T<NUM> and T<NUM>, respectively, and determines the RSTD value associated with these PRS Resource IDs as shown below, where "a" and "b" (e.g., obtained from PRS Index values using the formula a=PRS Index (<NUM>, <NUM>) -<NUM>; b=PRS Index (<NUM>, <NUM>) -<NUM>) represent the relative time differences with the reference PRSs in PRS Cell IDs <NUM> and <NUM>, respectively: <MAT>.

In a similar example, UE <NUM> may determine RSTD value associated with PRS Resource IDs <NUM> and <NUM> as shown below, where T<NUM> represents the arrival time of PRS Resource ID <NUM>.

In a further similar example, UE <NUM> may determine RSTD value associated with PRS Resource IDs <NUM> and <NUM> as shown below, where T<NUM> represents the arrival time of PRS Resource ID <NUM>. It is noted that in the example of <FIG>, since PRS Index(<NUM>, <NUM>) = <NUM>, there are zero time units corrected from T<NUM>, as shown below <MAT>.

In the above mentioned examples, RSTD values (RSTD<NUM>, <NUM> and RSTD<NUM>, <NUM>) may be sufficient to provide a two-dimensional estimation of the location of a UE that receives the corresponding PRSs from the corresponding cells.

In some implementations, the UE (e.g., UE <NUM>) may report the above determined RSTD values to the network, for example, to an entity that resides in the core network. In an example implementation, such core network entity may be a Location Server, which may be referred to Gateway Mobile Location Centre (GMLC) and Location Management Function (LMF) in <NUM>/NR. In some implementations, a UE may report RSTD values to a network entity that resides in the radio access network (RAN) which may be configured with location management capabilities as described above (for example, a local LMF residing in the RAN). In such example implementations, the communication between the UE and the RAN-based entity may be established, e.g., via Radio Resource Control (RRC) protocol. As the Location Server knows the physical locations of the cells, the Location Server estimates the location of UE <NUM> based on the RSTD reports it receives from UE <NUM>.

Therefore, the above described mechanism provides the capability for estimating location of UEs to provide better services.

<FIG> is a flow chart <NUM> illustrating transmission of reference signal time difference (RSTD) values from a user equipment (UE), e.g., UE <NUM>, according to an example implementation.

At block <NUM>, a UE may receive one or more PRSs from each cell of a plurality of cells. For example, in some implementations, UE <NUM> may receive one or more PRSs from each cell of a plurality of cells (e.g., cells <NUM>, <NUM>, and <NUM>) as shown in <FIG>. In some implementations, as described above, UE <NUM> may receive at least one PRS from three different cells, including a serving cell (e.g., cell <NUM>) and two neighbor cells (e.g., cells <NUM> and <NUM>).

In an example implementation, as shown in <FIG>, UE <NUM> may receive the following PRS Resource IDs: <NUM>, <NUM>, and <NUM> from PRS Cell ID # <NUM>; <NUM>, <NUM>, <NUM>, and <NUM> from PRS Cell ID # <NUM>; and <NUM> and <NUM> from PRS Cell ID # <NUM>. As described above in reference to <FIG> and <FIG>, each PRS Resource ID may convey a PRS Cell ID that indicates a cell the PRS Resource ID is transmitted from and the relative time of departure of the PRS Resource ID from the cell.

For example, in an implementation, PRS Resource ID <NUM> may relay that PRS Resource ID <NUM> is from PRS Cell ID # <NUM> and relative time of departure as 1X µs; PRS Resource ID <NUM> may relay that PRS Resource ID <NUM> is from PRS Cell ID # <NUM> and a relative time of departure as 1Y µs; and PRS Resource ID <NUM> may relay that PRS Resource ID <NUM> is from PRS Cell ID # <NUM> and relative time of departure as <NUM>.

UE <NUM> may receive this information via the PRS Resource IDs based on the index values. For example, in some implementations, the PRS Resource IDs may be configured in such a way that they convey the index values of each of the PRS Resource IDs from the cells.

At block <NUM>, the UE may determine arrival times of PRSs from different cells of the plurality of cells. For example, in some implementations, as described above, UE <NUM> may determine arrival times (e.g., T1, T2, T3, T4, etc.), as described above. The arrival times are the "timestamps" that the UE assigns to the events of receiving a PRS. That is, the UE may use its own clock to mark the time instances that the PRSs are received from different cells. Then, for forming the RSTD, the UE compares such timestamps.

At block <NUM>, the UE may transmit RSTD values. The RSTD values may be determined as described above in reference to <FIG> and <FIG>.

<FIG> is a block diagram of a wireless station (e.g., user equipment (UE)/user device or AP/gNB/MgNB/SgNB) <NUM> according to an example implementation. The wireless station <NUM> may include, for example, one or more RF (radio frequency) or wireless transceivers 502A, 502B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit/entity (controller) <NUM>/<NUM> to execute instructions or software and control transmission and receptions of signals, and a memory <NUM> to store data and/or instructions.

Processor <NUM> may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor <NUM>, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver <NUM> (502A or 502B). Processor <NUM> may control transmission of signals or messages over a wireless network, and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver <NUM>, for example). Processor <NUM> may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor <NUM> may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination of these. Using other terminology, processor <NUM> and transceiver <NUM> together may be considered as a wireless transmitter/receiver system, for example.

Moreover, a storage medium may be provided that includes stored instructions, which when executed by a controller or processor may result in the processor <NUM>, or other controller or processor, performing one or more of the functions or tasks described above.

According to another example implementation, RF or wireless transceiver(s) 502A/502B may receive signals or data and/or transmit or send signals or data. Processor <NUM> (and possibly transceivers 502A/502B) may control the RF or wireless transceiver 502A or 502B to receive, send, broadcast or transmit signals or data.

The aspects are not, however, restricted to the system that is given as an example, but a person skilled in the art may apply the solution to other communication systems. Another example of a suitable communications system is the <NUM> concept. It is assumed that network architecture in <NUM> will be quite similar to that of the LTE-advanced. <NUM> is likely to use multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

It should be appreciated that future networks will most probably utilize network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations may be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It should also be understood that the distribution of labor between core network operations and base station operations may differ from that of the LTE or even be non-existent.

Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Implementations may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, a data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. Implementations may also be provided on a computer readable medium or computer readable storage medium, which may be a non-transitory medium. Implementations of the various techniques may also include implementations provided via transitory signals or media, and/or programs and/or software implementations that are downloadable via the Internet or other network(s), either wired networks and/or wireless networks. In addition, implementations may be provided via machine type communications (MTC), and also via an Internet of Things (IOT).

Furthermore, implementations of the various techniques described herein may use a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers,. ) embedded in physical objects at different locations. The rise in popularity of smartphones has increased interest in the area of mobile cyber-physical systems. Therefore, various implementations of techniques described herein may be provided via one or more of these technologies.

Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

Claim 1:
A method (<NUM>) of communications, comprising:
receiving (<NUM>), by a user equipment, UE (<NUM>), one or more positioning reference signals, PRSs (<NUM>, <NUM>), from each cell of a plurality of cells (<NUM>, <NUM>, <NUM>), a second positioning reference signal, PRS (<NUM>), of the one or more positioning reference signals, PRSs, from a cell (<NUM>) of the plurality of cells includes a second time of departure of the second positioning reference signal, PRS, the second time of departure being relative to a first time of departure of a first reference positioning reference signal, PRS (<NUM>), received from the cell (<NUM>), the first reference positioning reference signal, PRS, being the first positioning reference signal, PRS, transmitted from the cell (<NUM>);
determining (<NUM>), by the user equipment, UE (<NUM>), arrival times of positioning
reference signals, PRSs, from different cells of the plurality of cells; and
transmitting (<NUM>), by the user equipment, UE (<NUM>), reference signal time difference, RSTD, values, a reference signal time difference, RSTD, value of the reference signal time difference, RSTD, values being determined by subtracting the second times of departure from the arrival times of PRSs from different cells of the plurality of cells (<NUM>, <NUM>, <NUM>), wherein the RSTD is calculated by: <MAT> wherein
T<NUM> is an arrival time of a reference signal from a first cell among the plurality of cells;
aX is the second time of departure of the reference signal from the first cell:
T<NUM> is an arrival time of a reference signal from a second cell among the plurality of cells; and
bY is the second time of departure of the reference signal from the second cell.