Carrier phase positioning techniques

Abstract

An example discloses a method of operating a communication node, in particular a UE or an access node (AN), the method comprising: receiving a location determination signal (LDS), in particular a positioning reference signal (PRS), on at least a first subcarrier and a second subcarrier on a wireless channel; and providing, to a location server node (LN), a message indicating a receive phase of the LDS on the first subcarrier. Further examples disclose a method of operating a location server node, the method comprising obtaining a message from a communication node indicating a receive phase of a location determination signal on a first subcarrier. Some examples disclose a location server node that includes control circuitry configured to perform the foregoing method. Further examples disclose a communication node comprising a control circuit configured to perform the above method.

Description

Technical Field

[0001] Various examples generally relate to determining a location of a wireless device. Background Art

[0002] The positioning functions and services specified by the 3rd Generation Partnership Project (3GPP), particularly in 3GPP TS 38.305 v17.1.0, have been designed to support positioning services in many commercial and public safety use cases involving wireless devices (also known as user equipment UE) operating in a communication network. Summary of the invention

[0003] Therefore, techniques that allow for even greater positioning accuracy and / or integrity may be needed.

[0004] Said need has been solved by the subject matter of the independent claims. Advantageous embodiments are described in the dependent claims.

[0005] An example discloses a method of operating a communication node (particularly a UE or an access node (AN)), the method comprising: receiving a location determination signal (LDS) (particularly a positioning reference signal (PRS)) on at least a first subcarrier and a second subcarrier on a wireless channel; and providing a message indicating a reception phase of the LDS on the first subcarrier to a location server node (LN).

[0006] A further example discloses a method of operating a location server node, the method comprising obtaining, from a communication node, a message indicating a received phase of a position determination signal on a first subcarrier.

[0007] Some examples disclose a location server node comprising control circuitry configured to perform the aforementioned method.

[0008] A further example discloses a communication node comprising a control circuit configured to perform the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A communication network is schematically shown.

[0010] Figure 2 The method of determining the distance is schematically shown.

[0011] Figure 3 Carriers and subcarriers are schematically shown.

[0012] Figure 4 The integer ambiguities and phases for different frequencies are schematically shown.

[0013] Figure 5 The signaling is shown schematically.

[0014] Figure 6 The signaling is shown schematically.

[0015] Figure 7 A method of operating a communication node is schematically illustrated. DETAILED DESCRIPTION

[0016] Some examples of the present disclosure generally provide multiple circuits or other electrical devices. All references to circuits and other electrical devices and the functions provided by each electrical device are not intended to be limited to only cover the contents shown and described herein. Although specific labels can be assigned to the various circuits or other electrical devices disclosed, such labels are not intended to limit the scope of operation of circuits and other electrical devices. Based on the desired specific type of electrical implementation, such circuits and other electrical devices can be combined with each other and / or separated in any way. It should be recognized that any circuit or other electrical device disclosed herein may include any number of microcontrollers, graphics processor units (GPUs), integrated circuits, memory devices (e.g., flash memory, random access memory (RAM), read-only memory (ROM), electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM) or other suitable variants thereof) and software that cooperates with each other to perform the operations disclosed herein. In addition, any one or more of the electrical devices may be configured to execute a program code embodied in a non-transitory computer-readable medium programmed to perform any number of functions as disclosed.

[0017] Hereinafter, examples of the present disclosure will be described in detail with reference to the accompanying drawings. It should be understood that the following description of the examples should not be construed as limiting. The scope of the present disclosure is not intended to be limited by the examples or drawings described below, which are to be considered illustrative only.

[0018] The drawings should be considered as schematic representations, and the elements shown in the drawings are not necessarily shown to scale. Instead, the various elements are represented so that their functions and generality become apparent to those skilled in the art. Any connection or coupling between the functional blocks, devices, components or other physical or functional units shown in the drawings or described herein may also be achieved by indirect connection or coupling. Coupling between components may also be established by wireless connection. Functional blocks may be implemented in hardware, firmware, software or a combination thereof.

[0019] Figure 1A communication environment 100 is shown that includes a wireless device 120, an access node (AN) 130, and a location server node (LN) 110. The wireless device 120 includes a control circuit implemented by a processor 121, a non-volatile memory 122, and an interface 123 that can access and control one or more antennas 124. Similarly, the AN 130 includes a control circuit implemented by a processor 131, a non-volatile memory 132, and an interface 133 that can access and control one or more antennas 134. The location server node (LN 110) may correspond to the LMF as specified in 3GPP TS38.305 V17.1.0. The LN 110 may also include a control circuit implemented by a processor 111, a non-volatile memory 112, and an interface 113 that provides a wired or wireless link to the AN 130.

[0020] Figure 2 The possibility of determining the distance d between the AN and the UE from the wavelength c / f of the carrier frequency f of the signal traveling between the AN and the UE at the speed of light c is shown. In particular, the distance d can be determined by the integer multiple N of the wavelength c / f of the signal and the reception phase The N calculated at the receiver can also be called an integer ambiguity.

[0021] Specifically, the distance d can be determined as follows:

[0022]

[0023] The transmitted signal may be used to determine the location and / or position of the UE and may be referred to as a location determination signal (LDS). However, due to the basic properties of trigonometric functions (i.e. ), the integer number of periods N cannot be obtained from the received phase alone.

[0024] At the receiver, the signal received at radio frequency (RF) is down-converted to baseband frequency. The receive phase measurement can be performed in baseband after an analog-to-digital converter (ADC). Therefore, the receive phase measurement can be digitally processed. In an example, the receive phase measurement can be performed using a conventional RF receiver of a communication node (particularly a UE or AN).

[0025] In some examples, the LDS may correspond to a positioning reference signal (PRS). The LDS signal may be an orthogonal frequency division multiplexing (OFDM) signal. In a conventional 3GPP New Radio (NR) system, it may be a downlink (DL) PRS or an uplink (UL) sounding reference signal (SRS).

[0026] The passband of the kth subcarrier frequency of the LDS OFDM signal can be modeled as:

[0027]

[0028] Among them, A k is the complex amplitude of the modulating signal, is the signal phase. is the frequency (f c +f k ), where f c is the carrier frequency, f k is the subcarrier frequency, and is the initial phase from the communication node transmitting the LDS signal. can be assumed to be constant.

[0029] Received signal Can be expressed as LDS and channel impulse response The convolution is as follows:

[0030]

[0031] Among them, h k is the complex channel coefficient at time delay τ.

[0032] In order to pass the signal Down-convert to baseband signal y k , the LDS receiver can perform a multiplication between the passband signal and the corresponding complex conjugate mixer signal:

[0033]

[0034] in, and is the phase error from the receiver side.

[0035] Afterwards, the estimated phase of each subcarrier fraction can be directly obtained from the baseband y k Obtained as follows:

[0036]

[0037] where arg(.) is a function that returns a complex-valued phase angle.

[0038] However, the above method only enables the reception phase to be obtained. The value of N is still unknown.

[0039] The value of N must be obtained by other means. In the example, the value of N can be obtained by obtaining the phase of the virtual frequency.

[0040] The LDS receiver can obtain the estimated received phase for different subcarriers k

[0041] Figure 3 Shown with its corresponding frequency f k Carriers and subcarriers, where k∈1,...,c,…,K. Carrier f c Located at the center of frequency f.

[0042] It can be used for carrier frequencies including f c Each frequency f k Estimated receive phase For each frequency f k , the receiving phase satisfies the following equation:

[0043]

[0044] Among them, N k refers to the corresponding integer ambiguity.

[0045] Then the difference for each k∈2,...,c,…,K is read as follows

[0046]

[0047] Among them, N k,1 represents the difference between the first integer ambiguity and the kth integer ambiguity, and f SCS is the subcarrier spacing. The term (k-1)*f SCS Can be thought of as a virtual frequency with increased frequency value.

[0048] The lowest virtual frequency 1*f can be used SCS To compute an initial (rough) distance estimate Usually, 1*f SCS is corresponding to long wavelength Assume that the wavelength is longer than the distance between the communication nodes, that is, This leads to N 2,1 =0.

[0049] exist Use N 2,1 = 0 allows obtaining a first (rough) distance estimate

[0050]

[0051] After this, the first (rough) distance Can be used for higher frequencies 2*f SCS The corresponding N 3,1 Provide estimates as follows:

[0052]

[0053] [*] indicates rounding operation, which can output the nearest integer.

[0054] can then be used to determine a new second distance estimate according to

[0055]

[0056] Then Can be used again to target Determine the estimate, Used for Wait until the final estimate for N K,1 =N K Estimates are obtained and the problem is actually solved.

[0057] Therefore, receiving the LDS on the first subcarrier and the second subcarrier and determining the received phase of the LDS may allow for improved positioning accuracy. In particular, it may enable integer ambiguity problems to be resolved.

[0058] This method uses low frequency (f low ), intermediate frequency (f middle ) and high frequency (f high ) different characteristics, such as Figure 4 As shown. Low frequencies correspond to long wavelengths, for which integer ambiguities are easy to resolve, but fractional phase accuracy is poor. For example, in frequency range 1 (FR1) of 5G New Radio (5G NR) specified by 3GPP, one of the SCSs is 30 kHz, which corresponds to a wavelength of approximately 10 km. The distance between a communication node sending an LDS and a communication node receiving an LDS does not exceed the 10 km range. Therefore, the assumption of zero integer ambiguity used above is reasonable.

[0059] On the other hand, the accuracy of the range estimate mainly relies on the received phase measurement, which may not be very accurate for low (virtual) frequencies. However, high frequencies have much shorter wavelengths, e.g., about 0.05 m for a 6 GHz carrier frequency of FR1. Therefore, the corresponding range estimate can be very accurate, since the integer ambiguities can be resolved using the method described above.

[0060] Figure 5 The signaling between LN 501, AN 502 and UE 503 is shown, which can be used to determine the position of UE 503 based on the received phase of LDS. In fact, there may be multiple ANs involved in the UE positioning process, including serving and neighboring ANs. Therefore, LN 501 can perform multi-point positioning for UE positioning estimation.

[0061] Many wireless communication systems (e.g., 5G NR wireless communication systems) are based on multi-carrier transmission. Orthogonal frequency division multiplexing (OFDM) can be used to transmit signals between communication nodes in a wireless communication system. Broadband transmission can be divided into multiple subcarriers, each with a narrow bandwidth. In the 5G NR wireless communication system, the bandwidth of each subcarrier is also referred to as subcarrier spacing (SCS). Receive phase measurements (or carrier phase measurements CPM) on multiple subcarriers can implement carrier phase positioning (CPP) techniques, resulting in improved positioning. A single CPP together with other positioning techniques may have helped to improve positioning. Using several CPPs may lead to even better results, and since the propagation of LDS on the wireless channel is typically affected by multipath propagation and noise as well as hardware defects on the receiver and transmitter sides, positioning is more robust to errors.

[0062] LN 501 may provide message 511 to UE 503 for requesting UE 503 to provide information about the capabilities of the UE. Depending on the UE design complexity and cost, various UEs in 5G NR may have different capabilities. Specifically, LN 501 may request whether UE 503 is capable of performing receive phase measurement. LN 501 may also request whether UE 503 is capable of obtaining the propagation distance of LDS based on the receive phase of LDS on the first subcarrier and the receive phase of LDS on the second subcarrier.

[0063] Obtaining the propagation distance of the LDS based on the receive phase of the LDS on the first subcarrier and the receive phase of the LDS on the second subcarrier may require a large amount of calculations. For example, resolving integer ambiguities as described above may cause a high computational load. Therefore, in some cases, it may be beneficial for the UE 503 to measure only the receive phases on two or more subcarriers and send a message indicating the corresponding receive phases to the LN 501, which can then perform the necessary calculations to obtain the propagation distance of the LDS. In other scenarios, it may be advantageous for a UE 503 with better UE capabilities to perform the calculations because sending a message indicating the propagation distance of the LDS may require fewer radio resources (i.e., due to a smaller report size) than sending a message indicating all receive phase measurements.

[0064] LN 501 may specifically obtain a message 512 from UE 503 indicating that the UE is capable of performing reception phase measurement. Message 512 may also indicate the ability of UE 503 to obtain the propagation distance of LDS based on the reception phase of LDS on the first subcarrier and the reception phase of LDS on the second subcarrier. Message 512 may also indicate the ability of UE 503 to handle the number of subcarriers. It may be a subcarrier set within a positioning frequency layer (PFL) or a subcarrier set in more than one PFL.

[0065] At 521, AN 502 may determine a configuration of LDS 518 to be later sent from AN 502 to UE 503. The configuration may indicate subcarriers to be used to send the LDS. The configuration of the LDS may correspond to the configuration of a downlink positioning reference signal (DL-PRS).

[0066] The LN 501 may provide the AN 502 with a message 513 requesting information on the configuration of the LDS 518, and in response, obtain a message 514 indicating the configuration of the LDS 518. The LN 501 may provide the UE 503 with a message 515 indicating the configuration of the LDS.

[0067] UE 503 may obtain a message 516 from LN 501 that triggers UE 503 to perform phase measurement on the first subcarrier and the second subcarrier. Message 516 may correspond to a positioning request.

[0068] Additionally, UE 503 may obtain a message 517 from LN 501 with assistance data related to CPP operation.

[0069] UE 503 may receive LDS 518 from AN 502. At 522, UE 503 may perform CPM, such as measuring a receive phase of LDS 518 on a first subcarrier and a receive phase of LDS 518 on a second subcarrier. Some other UEs, particularly UEs with better capabilities, may perform additional operations, such as calculation of propagation distances. In some scenarios, UE 503 may receive LDS from more than one AN. Determining the propagation distances relative to several ANs may allow the location of UE 503 to be determined based on triangulation.

[0070] LN 501 obtains message 519 indicating the reception phase of LDS 518 on the first subcarrier from UE 503. Message 519 may also indicate the reception phase of LDS on the second subcarrier. In some examples, message 519 may indicate the propagation distance of LDS expressed in multiples of the wavelength of the first subcarrier.

[0071] Figure 6 Signaling between LN 601, AN 602 and UE 603 ​​in another scenario is shown.

[0072] LN 601 may provide message 611 to AN 602 for requesting AN 602 to provide information about the capabilities of the AN. Specifically, LN 601 may request AN 602 whether it is capable of performing reception phase measurement. LN 601 may also request AN 602 whether it is capable of obtaining the propagation distance of the LDS based on the reception phase of the LDS on the first subcarrier and the reception phase of the LDS on the second subcarrier.

[0073] AN 602 may provide LN 601 with a message 612 indicating that AN 612 is capable of performing reception phase measurement. Message 612 may also indicate the ability of AN 602 to obtain the propagation distance of the LS based on the reception phase of the LDS on the first subcarrier and the reception phase of the LDS on the second subcarrier.

[0074] LN 601 may provide message 613 to AN 602, which triggers AN 602 to configure resources for transmitting LDS. In response, AN 602 may configure resources for transmitting LDS at 621. UE 603 ​​may obtain message 614 indicating the configured resources from AN 602. Likewise, AN 602 may provide message 615 indicating that resources for LDS have been configured to LN 601.

[0075] AN 602 may obtain a message 616 requesting AN 602 to perform reception phase measurement from LN 601. LN 601 may provide AN 602 with a message 617 having assistance data for performing reception phase measurement and / or for obtaining a propagation distance.

[0076] UE 603 ​​sends LDS 618 to AN 602 according to the configured resources. At 622, AN 602 performs a receive phase measurement. AN 602 then provides LN 601 with a message 619 indicating the receive phase of the LDS on the first subcarrier. As described above, message 619 may also indicate the propagation distance of the LDS expressed in multiples of the wavelength of the first subcarrier. More than one AN may receive the LDS from UE 601 and perform receive phase measurements independently of each other. This may allow the propagation distance of the LDS from UE 603 ​​to several ANs 602 to be obtained, and thus the position of UE 603 ​​to be estimated by triangulation.

[0077] In particular, it is proposed that a communication node receiving LDS reports the result of carrier phase measurement, ie, the received phase, based on the subcarrier level.

[0078] There may be two options for providing such carrier phase measurement reports. According to an example, a communication node receiving LDS reports a set of receive phases (eg, a vector of fractional phase measurements).

[0079] Another example may provide that a communication node reports a single value representing a receive phase measurement, where the single value is obtained by further post-processing of a previously obtained receive phase. The single value may include an integer portion and a decimal portion. For example, a communication node may report a carrier phase measurement of '76.45', where 76 represents an integer ambiguity and 0.45 represents a receive phase that is a fraction of 2π.

[0080] The carrier phase measurement format may vary in different positioning schemes.

[0081] For downlink time difference of arrival (DL-TDOA), the UE may report the carrier phase difference between the carrier phase from the reference AN and the carrier phase from the neighboring AN. This measurement may be considered as the counterpart of reference signal time difference (RSTD).

[0082] For a multi-cell round trip time (multi-RTT) positioning scheme, the receiver reports the sum of the carrier phase from the received signal and the carrier phase from the transmitted signal. This measurement can be considered the counter part of the RTT measurement.

[0083] As described above, the LN may provide assistance data to the communication node performing the receive phase measurement. For example, the LN may provide assistance data in the form of a rough position estimate of the communication node whose position is to be estimated. In other examples, the LN may provide a rough range estimate of the communication node whose position is to be estimated. This may help resolve integer ambiguities. The LN may also report uncertainty along with the rough position and / or range estimate. As an example, in the case of reporting a heading range estimate, the LN may report the heading range estimate in the form of {distance ± uncertainty}.

[0084] In addition, the assistance data may include an indication of line of sight (LOS) between communication nodes exchanging LDS. The LN may have historical data indicating that a wireless communication node is in LOS. In this case, the LN may indicate that a pair of wireless communication nodes in LOS may exchange LDS and perform CPM. In addition, the assistance data may include an indication of a preferred AN to be used for CPP operation.

[0085] Due to hardware limitations, some UEs may not be able to perform proper CPM, such as an RF chain with large phase noise, which will result in a poor positioning estimate. Therefore, the UE may provide information about its capabilities to the LN. For example, the UE may provide capability information related to UE deficiencies. For example, in order to initiate receive phase measurements, the LN may need to request deficiencies capability information from the UE. If the UE fails to meet the requirements of the CPP, the UE decides to abort the measurement and may notify the LN accordingly.

[0086] The receive phase measurement may be performed with downlink (DL) and uplink (UL) transmissions. For example, the AN may send LDS and the UE may perform receive phase measurement (CPM), or the UE may send LDS and the AN may perform receive phase measurement.

[0087] A communication node may indicate which type of receive phase measurement reporting it supports. In some examples, the communication network (i.e., AN and UE) may be configured to support at least one option. A communication node may selectively report carrier phase measurements based on signal quality. This may be helpful if receive phase measurements are to be performed in a wideband channel. Frequency selective fading may exist in a wideband channel. Therefore, reporting carrier phase measurements of subcarriers in deep fades will not be beneficial.

[0088] The communication node may be configured to perform CPM only or to perform CPM together with other positioning methods (eg, CPM together with DL-TDOA or CPM together with UL-TDOA or Multi-RTT).

[0089] Thus, a communication node may report only carrier phase measurements, or a communication node may report carrier phase measurements and other positioning measurements (eg, RSTD).

[0090] The communication node may be configured to perform CPM based on a given positioning reference signal (eg, which may be a subset of PRSs (from a portion of a given bandwidth), or a given frequency layer from a plurality of frequency layers).

[0091] The message indicating the receive phase of the LDS on the first subcarrier may include additional information. For example, the message may include parameters indicating the quality of the carrier phase measurement. These parameters may include a signal-to-noise ratio (SNR) and / or a LOS indicator. The message may also indicate the hardware condition of the communication node when performing the receive phase measurement. For example, if the receiver gets hot, it may affect the oscillator drift, which may increase the measurement error.

[0092] The communication node may be configured to perform or report CPP based on the signal quality (or LOS / NLOS indication) from a given base station or from a selected base station (e.g., best N). Here, the measurement reports may be sorted based on signal quality (prioritization). Measurement reports from poor measurements may be omitted.

[0093] Figure 7 A method of operating a communication node is briefly shown. At 701, the communication node receives a location determination signal LDS, in particular a positioning reference signal PRS, on a wireless channel at least on a first subcarrier and a second subcarrier. At 702, the communication node provides a message to a location server node LN indicating a reception phase of the LDS on the first subcarrier.

[0094] In summary, at least the following examples have been described above:

[0095] Example 1. A method of operating a communication node, in particular a wireless device UE or an access node AN, the method comprising:

[0096] - receiving a location determination signal LDS, in particular a positioning reference signal PRS, on a radio channel at least on a first subcarrier and a second subcarrier; and

[0097] - Providing a message to the location server node LN indicating the reception phase of the LDS on the first subcarrier.

[0098] Example 2. A method of operating a communication node according to Example 1, wherein the message indicating the reception phase of the LDS on the first subcarrier also indicates the reception phase of the LDS on the second subcarrier.

[0099] Example 3. A method of operating a communication node according to Example 1 or 2, wherein the message indicating the reception phase of the LDS on the first subcarrier also indicates the propagation distance of the LDS expressed in multiples of the wavelength of the first subcarrier.

[0100] Example 4. A method of operating a communication node according to any one of Examples 1 to 3, the method further comprising:

[0101] - Providing a message to the LN indicating the capability of the communication node to perform phase measurements on the first subcarrier and the second subcarrier.

[0102] Example 5. A method of operating a communication node according to any one of Examples 1 to 4, the method further comprising:

[0103] - Providing a message to the LN indicating the ability of the communication node to obtain the propagation distance of the LDS based on the reception phase of the LDS on the first subcarrier and the reception phase of the LDS on the second subcarrier.

[0104] Example 6. A method of operating a communication node according to any one of Examples 1 to 5, the method further comprising:

[0105] - Obtaining from the LN a message that triggers the communication node to perform phase measurement on the first subcarrier and the second subcarrier. Example 7. A method of operating a communication node according to any one of Examples 1 to 6, the method further comprising:

[0106] - Get auxiliary data from LN.

[0107] Example 8. A method of operating a communication node according to any one of Examples 1 to 7, wherein the message indicating the reception phase of the LDS on the first subcarrier indicates the signal quality of the LDS.

[0108] Example 9. A method of operating a communication node according to any one of Examples 1 to 8, wherein providing the message indicating the reception phase of the PRS on the first subcarrier is selectively performed based on the determined signal quality of the LDS.

[0109] Example 10. A method of operating a communication node according to any of Examples 1 to 9, wherein the message indicating the reception phase of the LDS on the first subcarrier indicates line-of-sight (LOS) reception of the LDS.

[0110] Example 11. A method of operating a communication node according to any one of Examples 1 to 10, the method further comprising:

[0111] - Obtain a message indicating a position estimate of a communication node.

[0112] Example 12. A method of operating a communication node according to any one of Examples 1 to 11, the method further comprising:

[0113] - Obtain a message indicating a position estimate of the transmitter of the LDS.

[0114] Example 13. A communication node, the communication node comprising a control circuit, wherein the control circuit is configured to perform a method according to any one of Examples 1 to 12.

[0115] Example 14. A method of operating a location server node LN, the method comprising:

[0116] - Obtaining a message from the communication node indicating a received phase of the position determination signal on the first subcarrier.

[0117] Example 15 A location server node LN, comprising a control circuit, wherein the control circuit is configured to perform the method according to Example 14.

Claims

1. A method of operating a communication node, in particular a wireless device UE or an access node AN, the method comprising: - receiving a location determination signal LDS, in particular a positioning reference signal PRS, on a radio channel at least on a first subcarrier and a second subcarrier; as well as - providing a message to a location server node LN indicating the reception phase of said LDS on said first subcarrier.

2. The method of operating a communication node according to claim 1, in, The message indicating a reception phase of the LDS on the first subcarrier also indicates a reception phase of the LDS on the second subcarrier.

3. A method for operating a communication node according to claim 1 or 2, in, The message indicating the reception phase of the LDS on the first subcarrier also indicates the propagation distance of the LDS expressed in multiples of the wavelength of the first subcarrier.

4. The method for operating a communication node according to any one of claims 1 to 3, the method further comprising: - providing a message to the LN indicating the capability of the communication node to perform phase measurements on the first subcarrier and the second subcarrier.

5. The method for operating a communication node according to any one of claims 1 to 4, the method further comprising: - providing a message to the LN indicating the communication node's ability to obtain the propagation distance of the LDS based on the reception phase of the LDS on the first subcarrier and the reception phase of the LDS on the second subcarrier.

6. The method for operating a communication node according to any one of claims 1 to 5, the method further comprising: - Obtaining from the LN a message triggering the communication node to perform phase measurement on the first subcarrier and the second subcarrier.

7. The method for operating a communication node according to any one of claims 1 to 6, the method further comprising: - Acquiring assistance data from the LN.

8. A method of operating a communication node according to any one of claims 1 to 7, in, The message indicating the reception phase of the LDS on the first subcarrier indicates a signal quality of the LDS.

9. A method of operating a communication node according to any one of claims 1 to 8, in, Providing a message indicating a receive phase of the PRS on a first subcarrier is selectively performed based on the determined signal quality of the LDS.

10. A method of operating a communication node according to any one of claims 1 to 9, in, The message indicating the reception phase of the LDS on the first subcarrier indicates line-of-sight (LOS) reception of the LDS.

11. The method for operating a communication node according to any one of claims 1 to 10, the method further comprising: - obtaining a message indicating a position estimate of said communication node.

12. The method for operating a communication node according to any one of claims 1 to 11, the method further comprising: - Obtain a message indicating a position estimate of the transmitter of said LDS.

13. A communication node, comprising a control circuit, wherein: The control circuit is configured to perform the method according to any one of claims 1 to 12.

14. A method of operating a location server node LN, the method comprising: - Obtaining a message from the communication node indicating a received phase of the position determination signal on the first subcarrier.

15. A location server node LN, comprising a control circuit, wherein: The control circuit is configured to perform the method according to claim 14.

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