User equipment assisted time synchronization between trps

Abstract

Systems and method are disclosed that relate to User Equipment (UE) assisted time synchronization between Transmission and Reception Points (TRPs). In one embodiment, a method performed by a network node comprises any one or more of the following: obtaining, from a User Equipment (UE), information about a downlink time delay difference between reception of a first downlink reference signal associated to a first TRP and reception of a second downlink reference signal associated to a second TRP; receiving, from the UE, an uplink reference signal at both the first TRP and the second TRP; determining an uplink time delay difference between reception of the uplink reference signal at the first TRP and reception of the uplink reference signal at the second TRP; and determining a timing offset between the first TRP and the second TRP based on the determined uplink time delay difference and the determined downlink time delay difference.

Description

USER EQUIPMENT ASSISTED TIME SYNCHRONIZATION BETWEEN TRPSRELATED APPLICATIONS

[0001] This application claims the benefit of provisional patent application serial number PCT / CN2024 / 130823, filed November 8, 2024, the disclosure of which is hereby incorporated herein by reference in their entirety.TECHNICAL FIELD

[0002] The present disclosure relates to a wireless communication network and, in particular, time synchronization between multiple Transmission and Reception Points (TRPs) used, for example, Coherent Joint Transmission (CJT).BACKGROUND

[0003] Similar to 3rdGeneration Partnership Project (3GPP) Long Term Evolution (LTE), the 5thGeneration (5G) mobile systems or New Radio (NR) uses Orthogonal Frequency Division Multiplexing (OFDM) in the downlink (i.e., from a network node, gNodeB (gNB), evolved NodeB (eNB), or base station, to a User Equipment or UE). In the uplink (i.e., from UE to gNB), both OFDM and Discrete Fourier Transform (DFT)-spread OFDM (DFT-S-OFDM) are supported. The basic NR physical resource can thus be seen as a time-frequency grid as illustrated in Figure 1, where a Resource Block (RB) in a 14-symbol slot is shown. An RB corresponds to twelve (12) contiguous subcarriers in the frequency domain. RBs are numbered in the frequency domain, starting with 0 from one end of the system bandwidth. Each resource element corresponds to one OFDM subcarrier during one OFDM symbol interval.

[0004] Different subcarrier spacings are supported in NR. The supported subcarrier spacings (also referred to as numerologies) are given by A = (15 X 2^) kilohertz (kHz) where is a nonnegative integer and can be one of {0,1, 2, 3, 4}. A = 15kHz (e.g., = 0) is the basic (or reference) subcarrier spacing that is also used in LTE. is also referred to as the numerology.

[0005] In the time domain, downlink and uplink transmissions in NR are organized into equally-sized subframes of 1 millisecond (ms) each. A subframe is further divided into multiple slots of equal duration. The slot length is dependent on the subcarrier spacing or numerology and is given by — ms. Each slot consists of 14 OFDM symbols for normal Cyclic Prefix (CP).

[0006] Data scheduling in NR can be in slot basis. Downlink (DL) transmissions can be dynamically scheduled, i.e., in each slot the gNB transmits Downlink Control Information (DCI) about which UE data is to be transmitted to and which resource blocks in the current downlink slotthe data is transmitted on. The control information is carried on Physical Downlink Control Channel (PDCCH), and data is carried on Physical Downlink Shared Channel (PDSCH). A UE first detects and decodes PDCCH and, if a PDCCH is decoded successfully, the UE then decodes the corresponding PDSCH based on the decoded control information in the PDCCH.

[0007] Uplink (UL) data transmission can also be dynamically scheduled using PDCCH. Similar to downlink, a UE first decodes uplink grants in PDCCH and then transmits data over the Physical Uplink Shared Channel (PUSCH) based the decoded control information in the uplink grant such as modulation order, coding rate, uplink resource allocation, and etc.

[0008] In 3GPP NR Rel-18, Channel State Information (CSI) feedback for Coherent Joint PDSCH Transmission (CJT) over multiple Transmission and Reception Points (TRPs) was introduced. In CJT, each Multiple Input Multiple Output (MIMO) layer of PDSCH is transmitted from multiple TRPs to a UE in a same time and frequency resource. Before the transmission, each MIMO layer is phase adjusted at each TRP such that they are phase aligned when reaching the UE and, thus, are coherently combined to enhance signal quality.

[0009] An example of CJT over two TRPs is shown in Figure 2, where a PDSCH with r layers, i.e., s = [s1(s2, ... , sr]T, is transmitted from two TRPs after being precoded by a precoding matrix at TRP#1 and a precoding matrix W2at TRP#2. Each element of the precoding matrices is a complex coefficient. The precoding helps to achieve coherent (or constructive) combining of signals from the two TRPs at the UE for each layer.

[0010] The precodersand W2can be reported by the UE as part of a CSI report for CJT, which was introduced in Rel-18, or determined by the network (NW) based on UL reference signals transmitted from the UE in Time Division Duplexing (TDD) systems assuming channel reciprocity. The latter is referred to as reciprocity based CJT. A CJT CSI typically comprises a rank (i.e., number of layers) indicator (RI), a channel quality indicator (CQI), and a precoding matrix indicator (PMI).and W2would be indicated by the PMI.

[0011] In NR Rel-18 CJT CSI, ideal synchronization between TRPs is assumed. In other words, the symbol / slot / frame timing and carrier frequency are assumed to be the same in different TRPs. However, in practice, some level of timing and carrier frequency offsets do exist across different TRPs. The issue has been recognized and is addressed in NRRel-19 via UE measurement and reporting of time and frequency differences between TRPs (see 3GPP RANI Chair Notes, RAN1#116bis, section 9.2.2 on CJT, 3GPP RANI Chair Notes, RAN1#117, section 9.2.2 on CJT, 3GPP RANI Chair Notes, RAN1#118, section 9.2.2 on CJT, and 3GPP RANI Chair Notes, RANl#118bis, section 9.2.2 on CJT). The reporting will be a standalone report, meaning that it will not be combined with legacy CSI reports.

[0012] In reciprocity based CJT transmission to a UE, the DL precoding matrices associated to the multiple TRPs are determined by the network based on uplink channel estimation due to channel reciprocity. The UL channel estimation can be done at each TRP based on UL reference signals (RS) such as Sounding Reference Signal (SRS) or Demodulation Reference Signal (DMRS) transmitted from the UE.

[0013] To be able to obtain DL channel estimation from UL channel estimation, the receive and transmit circuitries at each TRP is typically calibrated such that the same gain and phase are maintained across different receive and transmit circuitries associated to different antennas. There exists, however, an unknown residual absolute phase at each TRP after calibration. This means that there is an unknown phase difference between the estimated DL channel and the actual DL channel. This is not a problem in the cases with single TRP. With two or more TRPs, however, there is an unknown phase difference between any two estimated DL channels associated to two TRPs in a system with multiple TRPs (see Rl-2400753, CSI enhancements for large antenna arrays and CJT, Ericsson, 3GPP TSGRAN WG1 #116, Athens, Greece, Feb 26th - Mar 1st, 2024.). The issue is also recognized and is addressed in NR Rel-19 via UE reporting of phase differences between TRPs (see 3GPP RANI Chair Notes, RANl#116bis, section 9.2.2 on CJT, 3GPP RANI Chair Notes, RAN1#117, section 9.2.2 on CJT, 3GPP RANI Chair Notes, RAN1#118, section 9.2.2 on CJT, and 3GPP RANI Chair Notes, RAN1#118bis, section 9.2.2 on CJT).SUMMARY

[0014] Systems and method are disclosed that relate to User Equipment (UE) assisted time synchronization between Transmission and Reception Points (TRPs). In one embodiment, a method performed by a network node comprises any one or more of the following: obtaining, from a User Equipment (UE), information about a downlink time delay difference between reception of a first downlink reference signal associated to a first TRP and reception of a second downlink reference signal associated to a second TRP; receiving, from the UE, an uplink reference signal at both the first TRP and the second TRP; determining an uplink time delay difference between reception of the uplink reference signal at the first TRP and reception of the uplink reference signal at the second TRP; and determining a timing offset between the first TRP and the second TRP based on the determined uplink time delay difference and the determined downlink time delay difference. In this manner, the network is enabled to, for example, improve time synchronization between TRPs or simplify phase offset feedback for reciprocity based joint transmission.

[0015] In one embodiment, the method further comprises performing one or more actions based on the determined timing offset and / or using the determined timing offset.

[0016] In one embodiment, the uplink reference signal is a Sounding Reference Signal (SRS), a Demodulation Reference Signal (DMRS) of a Physical Uplink Shared Channel (PUSCH), or a DMRS of a Physical Uplink Control Channel (PUCCH).

[0017] In one embodiment, the uplink reference signal is a SRS transmitted by the UE on a single SRS port.

[0018] In one embodiment, the uplink reference signal is a SRS transmitted by the UE on multiple SRS ports, and determining the uplink time delay difference comprises combining (e.g., averaging, computing the mean of, or computing a median of) estimated uplink time delay measurements obtained for the multiple SRS ports.

[0019] In one embodiment, determining the uplink time delay difference comprises determining (Fig. 4, 404) the uplink time delay difference, DUL, as:^DUL= DUL2— DUL1where DUL2is an uplink time delay at the second TRP and DUL1is an uplink time delay at the first TRP. In one embodiment, determining (Fig. 4, 405) the timing offset between the first TRP (302-1) and the second TRP (302-2) comprises determining (Fig. 4, 405) the timing offset, AT, between the first TRP (302-1) and the second TRP (302-2) as:wherein DULis the determined uplink time delay difference and DDLis the downlink time delay difference obtained from the UE (306).

[0020] In one embodiment, the method further comprises repeating, for one or more additional UEs, the steps of obtaining information about a downlink time delay difference between reception of a first downlink reference signal (e.g., TRS, CSI-RS, DMRS, or the like) associated to the first TRP and reception of a second downlink reference signal associated to the second TRP, receiving an uplink reference signal at both the first TRP and the second TRP, determining an uplink time delay difference between reception of the uplink reference signal at the first TRP and reception of the uplink reference signal at the second TRP, and determining a timing offset between the first TRP and the second TRP based on the determined uplink time delay difference and the determined downlink time delay difference, thereby obtaining one or more additional timing offsets; and combining (e.g., averaging, compute mean of, compute media of, or any other kind of joint processing of) the timing offset obtained for the UE and at least one of the one or more additional timing offsets to provide a combined timing offset. In one embodiment, at least one timing offset from among a set of timing offsets consisting of the timing offset computed for the UE and the one or more additional timing offsets computed for the one or more additional UEs is excludedfrom consideration when combining to provide the combined timing offset. In one embodiment, the excluded timing offset(s) is(are) those timing offsets from among the set of timing offsets that: is(are) associated to an uplink received power that is less than an uplink received power threshold (e.g., a predefined or configured threshold); is(are) associated to a reported downlink reference signal received power that is less than a downlink reference signal received power threshold (e.g., a predefined or configured threshold); is(are) associated with a downlink reference signal SINR that is less than a downlink SINR threshold (e.g., a predefined or configured SINR threshold); has(have) a value that is different than the other timing offsets in the set by more than a threshold amount (e.g., a predefined or configured threshold amount)l is(are) associated to an uplink received power that is less than uplink received power(s) associated with one or more other UEs by a threshold (e.g., a predefined or configured threshold); is(are) associated to a reported downlink reference signal received power that is less than downlink reference signal received power(s) associated with one or more other UEs by a threshold (e.g., a predefined or configured threshold); or is(are) associated with a downlink reference signal SINR that is less than downlink SINR(s) associated with one or more other UEs by a threshold (e.g., a predefined or configured SINR threshold).

[0021] In one embodiment, the number of additional UEs is dynamically adapted (e.g., by the network node).

[0022] In one embodiment, combining the timing offset obtained for the UE and at least one of the one or more additional timing offsets to provide the combined timing offset comprises computing a weighted average of the timing offset obtained for the UE and the one or more additional timing offsets to provide the combined timing offset. In one embodiment, weights are assigned to the timing offsets based on assessed accuracy of the timing offsets. In one embodiment, weights are assigned to the timing offsets based on any one or more of the following criteria: reference signal bandwidth of downlink reference signals used for determining the downlink time delay difference; reference signal bandwidth of the uplink reference signal used for determining the uplink time delay difference; channel characteristics of the wireless channels between the first and second TRPs and the associated UE; whether the time offset is based on a set of signals (e.g., averaging of measurements for multiple SRS ports) or a single signal; delay between downlink signals at the UE from the first and second TRPs; reporting quantization errors (e.g., for the reporting of the downlink time delay difference); and received signal quality of the downlink reference signals at the UE and / or of the uplink reference signal at the first and the second TRPs, where the signal quality can be received signal power and / or signal to interference plus noise ratio.

[0023] In one embodiment, the method further comprises performing one or more actions based on the combined timing offset and / or using the combined timing offset.

[0024] In one embodiment, the network node comprises a network controller, the first TRP, and the second TRP.

[0025] Corresponding embodiments of a network node that performs the method in accordance with any of the aforementioned embodiments are also disclosed.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0027] Figure 1 illustrates the basic 3rdGeneration Partnership Project (3GPP) New Radio (NR) physical resource;

[0028] Figure 2 illustrates an example of Coherent Joint Transmission (CJT) of Physical Downlink Shared Channel (PDSCH);

[0029] Figure 3 illustrates one example of a network in which embodiments of the present disclosure may be implemented;

[0030] Figure 4 is a flow chart that illustrates a procedure performed by the network of Figure 3 for estimating the timing offset, AT, between the two Transmission and Reception Points (TRPs), in accordance embodiments of the present disclosure;

[0031] Figure 5 illustrates an example of estimating downlink time delay difference between two TRPs, in accordance with embodiments of the present disclosure;

[0032] Figure 6 illustrates an example of estimating uplink time delay different between two TRPs in accordance with embodiments of the present disclosure;

[0033] Figure 7 illustrates the effect of timing offset in downlink and uplink;

[0034] Figure 8 illustrates an example of wideband phase feedback based on timing offset pre-compensated reference signals;

[0035] Figure 9 shows an example of a communication system in accordance with some embodiments of the present disclosure;

[0036] Figure 10 shows a User Equipment device (UE) in accordance with some embodiments of the present disclosure;

[0037] Figure 11 shows a network node in accordance with some embodiments of the present disclosure; and

[0038] Figure 12 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized in accordance with some embodiments of the present disclosure.DETAILED DESCRIPTION

[0039] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0040] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0041] There currently exist certain challenge(s). When timing offsets between Transmission and Reception Points (TRPs) are present, the phase differences between TRPs would increase or decrease linearly over frequency or subcarriers within a signal bandwidth and sending feedback for a single phase per TRP is not enough (see R1 -2405005). To solve the problem, subband phase offset reporting is introduced in 3rdGeneration Partnership Project (3GPP) New Radio (NR) Rel- 19 ( see 3GPP RANI Chair Notes, RAN1#116bis, section 9.2.2 on CJT, 3GPP RANI Chair Notes, RAN1#117, section 9.2.2 on CJT, 3GPP RANI Chair Notes, RAN1#118, section 9.2.2 on CJT, and 3GPP RANI Chair Notes, RANl#118bis, section 9.2.2 on CJT) where up to 16 subbands can be configured and the subband size is also configurable from 1 Resource Block (RB) to 16 RBs.

[0042] More subbands implies large feedback overhead, while fewer subbands means less measurement samples available and, thus, less estimation accuracy for the phase offset. Another issue is on subband size configuration. For larger timing offsets, the phase changes faster over frequency and, thus, smaller subband size is needed in order to prevent phase wrap around within a subband. On the other hand, for smaller timing offsets, the phase changes slowly over frequency and, thus, larger subband size is needed to have more measurement samples to improve estimation accuracy. In practice, the range of the timing offsets is generally unknown by the network. It is very difficult to have one configuration to meet different timing offset ranges and this is a problem.

[0043] In general, it is desirable to have as small timing offsets between TRPs as possible. If the timing offsets between TRPs can be estimated, then they can be adjusted or pre-compensated at the network. How to estimate the timing offsets is another problem.

[0044] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. Embodiments of a method of estimating a timing offset between two TRPs are proposed. In one embodiment, the method comprises any one or more of the following steps at the network (e.g., performed by a network node such as, e.g., a base station or other RAN node associated to the first and second TRPs):• 401: Requesting a UE to report a downlink time delay difference between a first DL reference signal and a second DL reference signal, where the first DL reference signal and the second DL reference signal are transmitted from a first TRP and a second TRP, respectively. Alternatively, the network may request a UE to report downlink time delay difference between a first set of DL reference signals and a second set of DL reference signals, where the first set of DL reference signals and the second set of DL reference signals are transmitted from a first TRP and a second TRP, respectively.• 402: Receiving, from the UE, a downlink time delay difference report, i.e., a report on a downlink time delay difference between the first and the second DL reference signals received at the UE. Alternatively, the network receives from the UE a report on a downlink time delay difference between the first and the second sets of DL reference signals received at the UE.• 403: Receiving from the UE an uplink reference signal at both the first TRP and the second TRP.• 404: Estimating an uplink time delay difference between reception of the uplink reference signal at the first TRP and reception of the uplink reference signal at the second TRP.• 405: Computing a timing offset between the first and the second TRPs based on the estimated uplink time delay difference and the UE reported downlink time delay difference.

[0045] In one embodiment, the network may determine the timing offset from joint processing, e.g., averaging, outlier rejection, of the measurements obtained via multiple UEs.

[0046] Moreover, computing the timing offset between the TRPs may result in a number of actions at the network side, such as aligning the timing at the two TRPs and / or to simplifying the phase offset compensation procedure by, e.g., considering only the wideband phase offset reporting.

[0047] Embodiments of the solution described herein provide estimation of a timing offset between two TRPs at the network by combining a UE reported DL time delay offset between the two TRPs and a UL time delay offset estimated by the network based on an uplink reference signal transmitted by the UE.

[0048] Moreover, joint processing of the measurements obtained from multiple UEs may be used to improve the estimation accuracy, in some embodiments.

[0049] Certain embodiments may provide one or more of the following technical advantage(s). The method enables the network to improve time synchronization between TRPs or simplify phase offset feedback for reciprocity based joint transmission. The teachings of certain embodiments may improve the data rate, latency, and / or power consumption of the RAN.

[0050] Figure 3 illustrates one example of a network 300 in which embodiments of the present disclosure may be implemented. The example network 300 includes two TRPs 302-1 and 302-2, where a timing offset is present between the two TRPs 302-1 and 302-2. The TRPs 302-1 and 302-2 are under the control of a network controller 304. For example, together, the TRPs 302-1 and 302-2 and the network controller 304 may form a network node such as, e.g., a base station (e.g., a gNB to 6G base station). A UE 306 is served by the network 300 via the two TRPs 302-1 and 302-2. The two TRPs 302-1 and 302-2 are not perfectly time synchronized, and there exists a timing offset, AT, between the two TRPs 302-1 and 302-2. The propagation delay between the first TRP 302-1 (also referred to herein as TRP#1) and the UE 306 is denoted as T15and the propagation delay between the second TRP 302-2 (also referred to herein as TRP#2) and the UE 306 is denoted as T2- HI and H2arethe wireless channels between the TRP 302-1 (TRP#1) and the UE 306 and between the TRP 302-2 (TRP#2) and the UE 306, respectively. Each of the two TRPs 302-1 and 302-2 may be equipped with one or more antennas to transmit signals to the UE 306 and receive signals from the UE 306.

[0051] The unknown timing offset AT can be an issue for joint data transmission from the two TRPs 302-1 and 302-2 to the UE 306, particularly for reciprocity based coherent joint transmission for example, if it is not accounted for.

[0052] Figure 4 is a flow chart that illustrates a procedure performed by the network 300 (e.g., by the network controller 304 and the first and second TRPs 302-1 and 302-2) for estimating the timing offset, AT, between the two TRPs 302-1 and 302-2, in accordance with embodiments of the present disclosure. Note that the network 300 may also be referred to herein as a “network node” that includes the network controller 304 and the first and second TRPs 302-1 and 302-2, where this network node may be, for example, a base station (e.g., a gNB or 6G base station) or other Radio Access Network (RAN) node. In Figure 4, optional steps are represented by dashed lines / boxes. Also, while the steps of the procedure are illustrated in Figure 4 as being performed in a particular order, the steps may be performed in any desired order and steps or aspects of certain steps may be performed in parallel. As one example of how the steps of the procedure of Figure 4 may vary from what is shown in the figure is that the order of Steps 401 to 404 may be re-arranged, e.g., Steps 403 & 404 may occur before Steps 401 and 402. Also note that, while the procedure is described for two TRPs, the same approach can be applied for the cases with multiple TRPs, e.g., up to 4 TRPs. The steps of the procedure of Figure 4 are as follows:• Step 401: The network 300 (e.g., the network controller 304) sends, to the UE 306 (e.g., via one or both of the TRPs 302-1 and 302-2), a request for the UE 306 to report a downlink time delay difference between a first DL reference signal and a second DL reference signal, where the first DL reference signal and the second DL reference signal are transmitted from the first TRP 302-1 and the second TRP 302-2, respectively. Alternatively, the network 300 (e.g., the network controller 304) may send, to the UE 306 (e.g., via one or both of the TRPs 302-1 and 302-2), a request for the UE 306 to report downlink time delay difference between a first set of DL reference signals and a second set of DL reference signals, where the first set of DL reference signals and the second set of DL reference signals are transmitted from the first TRP 302-1 and the second TRP 302-2, respectively.• Step 402: The network 300 (e.g., the network controller 304) receives, from the UE 306 (e.g., via one or both of the TRPs 302-1 and 302-2), a report on the downlink time delay difference between the first and the second DL reference signals received at the UE 306. Alternatively, the network 300 (e.g., the network controller 304) receives, receives from the UE 306 (e.g., via one or both of the TRPs 302-1 and 302-2), a report on a downlink time delay difference between the first set and the second sets of DL reference signals received at the UE 306.• Step 403: The network 300 receives, from the UE 306, an uplink reference signal at both the first and the second TRPs 302-1 and 302-2.• Step 404: The network 300 (e.g., the network controller 304) estimates an uplink time delay difference between the uplink reference signal received at the first TRP 302-1 and the uplink reference signal received at the second TRP 302-2. In other words, the network 300 (e.g., the network controller 304) estimates the uplink time delay difference between reception of the uplink reference signal at the first TRP 302-1 and reception of the uplink reference signal at the second TRP 302-2.• Step 405: The network 300 (e.g., the network controller 304) computes a timing offset between the first and the second TRPs 302-1 and 302-2 based on the estimated uplink time delay difference estimated in Step 404 and the UE reported downlink time delay difference received in Step 402.• Step 406 (Optional): The network 300 may repeat Steps 401 to 405 for one or more additional UEs, thereby obtaining multiple timing offset values and combine (e.g., average,mean, median, or any other type of joint processing) the timing offset value obtained for the initial iteration of Steps 401 to 405 for the UE and the additional timing offset value(s) obtained for the additional UE(s) in the additional iteration(s) of Steps 401 to 405 to thereby provide a combined (e.g., averaged, mean, median) timing offset across multiple UEs.• 407 (Optional): The network 300 (e.g., the network controller 304) may then perform one or more actions based on the computed timing offset between the first and second TRPs 302-1 and 302-2 (from 405 or 406) or otherwise use the computed timing offset (from Step 405 or Step 406) between the first and second TRPs 302-1 and 302-2. For example, the network 300 may perform one or more actions to align the timing at the TRPs 302-1 and 302-2 based on the computed timing offset. As another example, the network 300 may use the computed timing offset to simplify phase offset compensation by, e.g., considering only wideband phase offset reporting.

[0053] The details of each steps are further discussed below.

[0054] Step 401 and Step 402 can, for example, be done according to the existing procedure of NR Rel-19 delay offset reporting, where the first and second DL reference signals can be a first and a second Tracking Reference Signal (TRS). Alternatively, the first and second DL reference signals can be respectively replaced by a first set of DL reference signals and a second set of DL reference signals. In this alternative approach, the first and second DL reference signals correspond to the first and the second TRSs, respectively. In another alternative, the downlink delay offsets may be measured based on other DL reference signals, e.g., such as those defined in 3GPP 6thGeneration (6G). The UE estimates a time delay offset, DDL1, associated to the first TRS and a time delay offset, DDL2, associated to the second TRS, as illustrated in Figure 5. The downlink time delay offset between the first and second TRSs can be calculated as DDL= DDL2~ DDL1which contains both the timing offset, AT, as well as the propagation delay difference, T2— Ti> between the two TRPs, i.e., DDL= AT + T2— Ti- DDLis then reported by the UE 306 in the report received by the network 300 in 402. For simplicity, the first TRP 302-1 is considered as the reference herein, but in practice, the reference TRP is, for example, selected and reported by the UE 306.

[0055] In some embodiments, the first downlink reference signal and second downlink reference signal are transmitted with same time resource but different frequency resources.

[0056] In some embodiment, the first and second DL reference signals used to estimate the time delay can also be other DL RSs, e.g., DL DMRSs from the first and second TRPs 302-1 and 302-2.

[0057] In another embodiment, the network 300 may receive a measurement quality index indication and / or measurement accuracy capability for measured accuracy level.

[0058] Step 403. The uplink reference signal transmitted by the UE 306 and received at the first and second TRPs 302-1 and 302-2 can be, for example, an existing NR Sounding Reference Signal (SRS) or a DeModulation Reference Signal (DMRS) of Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH), or an uplink reference signal defined in 6G.

[0059] In some embodiments, the UE 306 may transmit a single SRS port. Alternatively, the UE 306 may transmit multiple SRS ports. In this case, the network 300 (e.g., the network controller 304) may average the estimated DUL(see 404) obtained from the multiple SRS ports to improve the accuracy of uplink time delay offset. In some alternative embodiments, the network 300 (e.g., the network controller 304) may determine the UL delay offset using mean or median of multiple measurements / reports (e.g., from the same and / or different UEs).

[0060] In some embodiments, the UL reference signal for estimation of UL channel and UL delay offset can be periodic, semi-persistent, or aperiodic.

[0061] Step 404. As illustrated in Figure 6, the uplink reference signal is received at both TRP#1 and TRP#2. The network 300 (e.g., the network controller 304 or the first and second TRPs 302-1 and 302-2) estimates a time delay offset, DUL1, at the first TRP 302-1 and the time delay offset, DUL2, at the second TRP 302-2. The uplink time delay offset, or difference, between the first and second TRPs 302-1 and 302-2 can be calculated (e.g., by the network controller 304) as DUL= DUL2~ DUL1.

[0062] Note that the received uplink reference signal at the first TRP 302-1 has a propagation delay T15i.e., DUL1=while the received uplink reference signal at the second TRP 302-2 has an equivalently a propagation delay of T2—T, i.e., DUL2= T2— AT. This is illustrated in Figure 7, where T2= 0 is assumed for simplicity. Note that the effect of AT in uplink is different from that in the downlink. In the downlink, AT is equivalent to a delay, while in the UL it is equivalent to a time advance.

[0063] Therefore, the uplink time delay difference, DUL, between the SRS received at the first TRP 302-1 and the SRS received at the second TRP 302-2 is then given by DUL= DUL2— DUL1= T2— AT — T1

[0064] Step 405: The timing offset, AT, can be computed (e.g., by the network 300 such as, e.g., by the network controller 304) as

[0065] Step 406 (Optional): Since AT is common to all UEs served by the TRPs 302-1 and 302-2, the estimation of AT can be improved by averaging (or, in general joint processing) over multiple UEs. Thus, in one word, the network 300 may perform one or more additional iterations of Steps 401 to 405 for one or more additional UEs, respectively, and then combine (e.g., average, compute mean of, compute median of) the time offset values from the initial and additional iterations of Steps 401 to 405 to provide a combined (e.g., average, mean, median) time offset.

[0066] In one embodiment, in the cases with multiple UEs, the network 300 may perform outlier rejection methods to reject, e.g., the measurements associated with low SRS received power, low reported downlink Reference Signal Received Power (RSRP) / Signal to Interference plus Noise Ratio (SINR), or considerably different values of AT compared to other reported values. For instance, if the SRS received power associated with a UE in one or both of the TRPs 302-1 and 302-2 is below a threshold, e.g., X dB, the network 300 (e.g., the network controller 304) may reject the results obtained from that UE and does not consider it in, e.g., the averaging. As another example, if the received power of the DL-RSs transmitted from the first TRP 302-1 and / or the second TRP 302-2 to a UE is below a threshold, e.g., Y dB, the results obtained from that UE are not considered in, e.g., the averaging. In another example, if the difference between the AT obtained via a UE’s assistance and those obtained from one or more other UEs exceeds a threshold, e.g., | AT; — AT| > X with AT; being the timing offset value obtained via the z-th UE and AT being the average timing offset obtained from the other UEs, the network 300 (e.g., the network controller 304) may reject the measurement obtained via the z-th UE, i.e., AT;. In another example, if the RSRP(s) associated with measurement from a UE is less than the RSRP(s) associated with measurements from one or more other UEs by a threshold, e.g., Z dB, the network 300 (e.g., the network controller 304) may reject the results obtained from that UE and does not consider it in, e.g., the averaging. In another example further aspects like UE measurement capability, reference signal bandwidth (BW), channel characteristics (e.g., delay spread and DL / UL reciprocity), if UE measurements based on averaging or single measurements, delay between DL and related UL measurements, reporting limitations (quantization level and dynamic range) can be used to determine contribution from different UEs.

[0067] Here, the network 300 (e.g., the network controller 304) may dynamically adapt the number of reports to be jointly processed. For instance, if there are few stationary UEs available, reports from those few stationary UEs may be enough for averaging. Otherwise, the network 300 may consider multiple UEs’ reports. Moreover, the thresholds mentioned above may be fixed or varying depending on, e.g., the number of considered UEs, measurement values, resolution of themeasurement values, etc. Such averaging / outlier rejection / weighting methods reduce the effect of, e.g., quantization errors, measurement errors and / or the resolution issues.

[0068] In another embodiment, instead of rejecting measurements, different weights are applied to results from different UEs based on assessed time offset accuracy.

[0069] The selection or weighting could further use the following information alone or in combination.• Reference signal bandwidth (e.g., reference signal bandwidth of downlink reference signals used for determining the downlink time delay difference and / or reference signal bandwidth of the uplink reference signal used for determining the uplink time delay difference);• Channel characteristics where a channel with close in multi path could be less accurate (BW related) (e.g., channel characteristics of the wireless channels between the first and second TRPs 302-1 and 302-2 and the associated UE);• If measurements are based on a set of signals (averaging) or single signals (e.g., whether the time offset is based on a set of signals (e.g., averaging of measurements for multiple SRS ports for the uplink time delay difference) or a single signal);• Delay between DL signals (e.g., delay between DL signals at the UE from the first and second TRPs 302-1 and 302-2);• Reporting quantization errors (quantization level and dynamic range) (e.g., for the reporting of the downlink time delay difference);• Received signal quality of the downlink reference signals at the UE and / or of the uplink reference signal at the first and the second TRPs, where the signal quality can be received signal power and / or signal to interference plus noise ratio.

[0070] The network 300 can, based on such known information, assess the quality of the derived inter TRP time offset and use it to optimize the service e.g. for more optimal tuning of reporting overhead. In addition to UE reporting quality, the number of reporting UEs will also impact the quality, e.g. impact from reporting quantization errors would reduce with more reporting UEs. The measurement periodicity could be determined based on combination of such assessment and results from historical measurements.

[0071] Step 407 (optional): The actual benefit of a derived time offset would depend on its accuracy level. A more accurate time offset would allow, e.g., a higher level of reporting overhead reduction and / or increased feature performance. The network 300 (e.g., the network controller 304) could assess the expected accuracy based on estimated individual UE measurement andcombined measurements from multiple UEs. A quality index could be sent to an application together with derived time offset.

[0072] In Step 407, the network 300 (e.g., the network controller 304) may, for example, dynamically change the periodicity of repeated time offset measurements over time dependent on derived historical time offsets, assessed time offset accuracy, and required accuracy level, if margins measurements could be performed less frequent.

[0073] Example Applications (e.g., Example Actions that may be performed in Step 407):

[0074] With the estimated AT from Step 405 or Step 406 above, the network 300 (e.g., the network controller 304) can adjust the timing at either the first TRP 302-1 or the second TRP 302- 2 to align the timing at the two TRPs 302-1 and 302-2. In another scenario, it can be used to simplify phase offset feedback in reciprocity based CJT transmission to a UE from the two TRPs 302-1 and 302-2.

[0075] In reciprocity-based DL transmission, to be able to obtain DL channel from UL channel estimation, the receive and transmit circuitries at each TRP 302-1 and 302-2 is typically calibrated such that the same gain and phase are maintained across different receive and transmit circuitries associated to different antennas. There exists, however, an unknown residual absolute phase at each TRP 302-1 and 302-2 after calibration. This means that there is an unknown phase difference between the estimated downlink channel and the actual DL channel and, thus, there is an unknown phase difference between the two estimated DL channels associated to the two TRPs 302-1 and 302-2, and this is a problem. With the presence of the timing offset AT, the unknown phase difference also varies over the signal bandwidth. To address the problem, subband phase offset was introduced in 3GPP Release 19 with configurable subband size. However, depending on the number of configured subbands, the feedback overhead can be large and some tradeoff between number of subbands and subband size is needed, which is difficult in practice when AT is unknown. And large time offset AT may cause phase wrap around in a subband or across consecutive subbands, which can lead to wrong phase offset estimation.

[0076] With estimated timing offset AT available at the network 300, AT (together with channel phase) can be pre-compensated before a reference signal (e.g., CSLRS) is transmitted from each TRP 302-1 and 302-2 for phase offset feedback. As a result, only a wideband phase offset feedback is needed. This is particularly useful because not all UEs support subband phase offset reporting. Hence, the proposed solution alleviates the need to configure, trigger, and / or receive subband phase offsets from UEs. As a result, the proposed solution can reduce reporting overhead due to subband phase offset reporting. This is illustrated in Figure 8, which shows wideband phase feedback based on AT pre-compensated reference signals.

[0077] If subband phase reporting is supported by a UE, the proposed scheme makes it possible to reduce its overhead by considering, e.g., a limited number of subbands (and, e.g., combine the result of the proposed scheme with those obtained by subband reporting on a limited number of subbands).

[0078] Other applications and features like positioning could also benefit from a derived timing offset either directly if used to synchronize the TRPs or, e.g., in positioning algorithms as applied post compensation.

[0079] Although the discussions above are based on two TRPs, the embodiments are equally applicable to more than two TRPs.

[0080] Figure 9 shows an example of a communication system 900 in accordance with some embodiments.

[0081] In the example, the communication system 900 includes a telecommunication network 902 that includes an access network 904, such as a Radio Access Network (RAN), and a core network 906, which includes one or more core network nodes 908. The access network 904 includes one or more access network nodes, such as network nodes 910A and 910B (one or more of which may be generally referred to as network nodes 910), or any other similar Third Generation Partnership Project (3GPP) access nodes or non-3GPP Access Points (APs). Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 902 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 902 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 902, including one or more network nodes 910 and / or core network nodes 908.

[0082] Examples of an ORAN network node include an Open Radio Unit (O-RU), an Open Distributed Unit (O-DU), an Open Central Unit (O-CU), including an O-CU Control Plane (O- CU-CP) or an O-CU User Plane (O-CU-UP), a RAN intelligent controller (near-real time or non- real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such asan Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the 0-RAN Alliance or comparable technologies. The network nodes 910 facilitate direct or indirect connection of User Equipment (UE), such as by connecting UEs 912A, 912B, 912C, and 912D (one or more of which may be generally referred to as UEs 912) to the core network 906 over one or more wireless connections.

[0083] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 900 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 900 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0084] The UEs 912 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 910 and other communication devices. Similarly, the network nodes 910 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 912 and / or with other network nodes or equipment in the telecommunication network 902 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 902.

[0085] In the depicted example, the core network 906 connects the network nodes 910 to one or more hosts, such as host 916. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 906 includes one more core network nodes (e.g., core network node 908) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 908. Example core network nodes include functions of one or more of a MobileSwitching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-Concealing Function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0086] The host 916 may be under the ownership or control of a service provider other than an operator or provider of the access network 904 and / or the telecommunication network 902, and may be operated by the service provider or on behalf of the service provider. The host 916 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0087] As a whole, the communication system 900 of Figure 9 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system 900 may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable Second, Third, Fourth, or Fifth Generation (2G, 3G, 4G, or 5G) standards, or any applicable future generation standard (e.g., Sixth Generation (6G)); Wireless Local Area Network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any Low Power Wide Area Network (LPWAN) standards such as LoRa and Sigfox.

[0088] In some examples, the telecommunication network 902 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunication network 902 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 902. For example, the telecommunication network 902 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing enhanced Mobile Broadband (eMBB) services to other UEs, and / or massive Machine Type Communication (mMTC) / massive Internet of Things (loT) services to yet further UEs.

[0089] In some examples, the UEs 912 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 904 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 904. Additionally, a UE may be configured for operating in single- or multi -Radio Access Technology (RAT) or multi -standard mode. For example, a UE may operate with any one or combination of WiFi, New Radio (NR), and LTE, i.e. being configured for Multi -Radio Dual Connectivity (MR-DC), such as Evolved UMTS Terrestrial RAN (E-UTRAN) NR - Dual Connectivity (EN-DC).

[0090] In the example, a hub 914 communicates with the access network 904 to facilitate indirect communication between one or more UEs (e.g., UE 912C and / or 912D) and network nodes (e.g., network node 910B). In some examples, the hub 914 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 914 may be a broadband router enabling access to the core network 906 for the UEs. As another example, the hub 914 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 910, or by executable code, script, process, or other instructions in the hub 914. As another example, the hub 914 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 914 may be a content source. For example, for a UE that is a Virtual Reality (VR) headset, display, loudspeaker or other media delivery device, the hub 914 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 914 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 914 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0091] The hub 914 may have a constant / persistent or intermittent connection to the network node 910B. The hub 914 may also allow for a different communication scheme and / or schedule between the hub 914 and UEs (e.g., UE 912C and / or 912D), and between the hub 914 and the core network 906. In other examples, the hub 914 is connected to the core network 906 and / or one or more UEs via a wired connection. Moreover, the hub 914 may be configured to connect to a Machine-to-Machine (M2M) service provider over the access network 904 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 910 while still connected via the hub 914 via a wired or wireless connection. In some embodiments, the hub 914 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 910B. In otherembodiments, the hub 914 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and the network node 910B, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0092] Figure 10 shows a UE 1000 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged, and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, Voice over Internet Protocol (VoIP) phone, wireless local loop phone, desktop computer, Personal Digital Assistant (PDA), wireless camera, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), smart device, wireless Customer Premise Equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3 GPP, including a Narrowband Internet of Things (NB-IoT) UE, a Machine Type Communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0093] A UE may support Device-to-Device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), Vehi cl e-to- Vehicle (V2V), Vehicle-to-Infrastructure (V2I), or Vehicle- to-Everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0094] The UE 1000 includes processing circuitry 1002 that is operatively coupled via a bus 1004 to an input / output interface 1006, a power source 1008, memory 1010, a communication interface 1012, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 10. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0095] The processing circuitry 1002 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions storedas machine-readable computer programs in the memory 1010. The processing circuitry 1002 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general purpose processors, such as a microprocessor or Digital Signal Processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 1002 may include multiple Central Processing Units (CPUs).

[0096] In the example, the input / output interface 1006 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 1000. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0097] In some embodiments, the power source 1008 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 1008 may further include power circuitry for delivering power from the power source 1008 itself, and / or an external power source, to the various parts of the UE 1000 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1008. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1008 to make the power suitable for the respective components of the UE 1000 to which power is supplied.

[0098] The memory 1010 may be or be configured to include memory such as Random Access Memory (RAM), Read Only Memory (ROM), Programmable ROM (PROM), Erasable PROM (EPROM), Electrically EPROM (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1010 includes one or more application programs 1014, such as an operating system, web browser application, a widget, gadgetengine, or other application, and corresponding data 1016. The memory 1010 may store, for use by the UE 1000, any of a variety of various operating systems or combinations of operating systems.

[0099] The memory 1010 may be configured to include a number of physical drive units, such as Redundant Array of Independent Disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, High Density Digital Versatile Disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, Holographic Digital Data Storage (HDDS) optical disc drive, external mini Dual In-line Memory Module (DIMM), Synchronous Dynamic RAM (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a tamper resistant module in the form of a Universal Integrated Circuit Card (UICC) including one or more Subscriber Identity Modules (SIMs), such as a Universal SIM (USIM) and / or Internet Protocol Multimedia Services Identity Module (ISIM), other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as a ‘SIM card.’ The memory 1010 may allow the UE 1000 to access instructions, application programs, and the like stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system, may be tangibly embodied as or in the memory 1010, which may be or comprise a device-readable storage medium.

[0100] The processing circuitry 1002 may be configured to communicate with an access network or other network using the communication interface 1012. The communication interface 1012 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1022. The communication interface 1012 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 1018 and / or a receiver 1020 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1018 and receiver 1020 may be coupled to one or more antennas (e.g., the antenna 1022) and may share circuit components, software, or firmware, or alternatively be implemented separately.

[0101] In the illustrated embodiment, communication functions of the communication interface 1012 may include cellular communication, WiFi communication, LPWAN communication, data communication, voice communication, multimedia communication, short- range communications such as Bluetooth, NFC, location-based communication such as the use of the Global Positioning System (GPS) to determine a location, another like communicationfunction, or any combination thereof. Communications may be implemented according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband CDMA (WCDMA), GSM, LTE, NR, UMTS, WiMax, Ethernet, Transmission Control Protocol / Intemet Protocol (TCP / IP), Synchronous Optical Networking (SONET), Asynchronous Transfer Mode (ATM), Quick User Datagram Protocol Internet Connection (QUIC), Hypertext Transfer Protocol (HTTP), and so forth.

[0102] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1012, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected, an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0103] As another example, a UE comprises an actuator, a motor, or a switch related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0104] A UE, when in the form of an loT device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application, and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a television, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or VR, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence of the intendedapplication of the loT device in addition to other components as described in relation to the UE 1000 shown in Figure 10.

[0105] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3 GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship, an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0106] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g., by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator and handle communication of data for both the speed sensor and the actuators.

[0107] Figure 11 shows a network node 1100 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged, and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment in a telecommunication network. Examples of network nodes include, but are not limited to, APs (e.g., radio APs), Base Stations (BSs) (e.g., radio BSs, Node Bs, evolved Node Bs (eNBs), NR Node Bs (gNBs)), and 0-RAN nodes or components of an 0-RAN node (e.g., 0-RU, 0-DU, O-CU).

[0108] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an 0-RAN access node), and / or Remote Radio Units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such RRUs may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a Distributed Antenna System (DAS).

[0109] Other examples of network nodes include multiple Transmission Point (multi-TRP) 5G access nodes, Multi -Standard Radio (MSR) equipment such as MSR BSs, network controllers such as Radio Network Controllers (RNCs) or BS Controllers (BSCs), Base Transceiver Stations (BTSs), transmission points, transmission nodes, Multi-Cell / Multicast Coordination Entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0110] The network node 1100 includes processing circuitry 1102, memory 1104, a communication interface 1106, and a power source 1108. The network node 1100 may be composed of multiple physically separate components (e.g., a NodeB component and an RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 1100 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair may in some instances be considered a single separate network node. In some embodiments, the network node 1100 may be configured to support multiple RATs. In such embodiments, some components may be duplicated (e.g., separate memory 1104 for different RATs) and some components may be reused (e.g., a same antenna 1110 may be shared by different RATs). The network node 1100 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1100, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, Long Range Wide Area Network (LoRaWAN), Radio Frequency Identification (RFID), or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within the network node 1100.[OHl] The processing circuitry 1102 may comprise a combination of one or more of a microprocessor, controller, microcontroller, CPU, DSP, ASIC, FPGA, or any other suitable computing device, resource, or combination of hardware, software, and / or encoded logic operable to provide, either alone or in conjunction with other network node 1100 components, such as the memory 1104, to provide network node 1100 functionality.

[0112] In some embodiments, the processing circuitry 1102 includes a System on a Chip (SOC). In some embodiments, the processing circuitry 1102 includes one or more of Radio Frequency (RF) transceiver circuitry 1112 and baseband processing circuitry 1114. In some embodiments, the RF transceiver circuitry 1112 and the baseband processing circuitry 1114 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. Inalternative embodiments, part or all of the RF transceiver circuitry 1112 and the baseband processing circuitry 1114 may be on the same chip or set of chips, boards, or units.

[0113] The memory 1104 may comprise any form of volatile or non-volatile computer- readable memory including, without limitation, persistent storage, solid state memory, remotely mounted memory, magnetic media, optical media, RAM, ROM, mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD), or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device- readable, and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1102. The memory 1104 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1102 and utilized by the network node 1100. The memory 1104 may be used to store any calculations made by the processing circuitry 1102 and / or any data received via the communication interface 1106. In some embodiments, the processing circuitry 1102 and the memory 1104 are integrated.

[0114] The communication interface 1106 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1106 comprises port(s) / terminal(s) 1116 to send and receive data, for example to and from a network over a wired connection. The communication interface 1106 also includes radio front-end circuitry 1118 that may be coupled to, or in certain embodiments a part of, the antenna 1110. The radio front-end circuitry 1118 comprises filters 1120 and amplifiers 1122. The radio front-end circuitry 1118 may be connected to the antenna 1110 and the processing circuitry 1102. The radio front-end circuitry 1118 may be configured to condition signals communicated between the antenna 1110 and the processing circuitry 1102. The radio front-end circuitry 1118 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 1118 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of the filters 1120 and / or the amplifiers 1122. The radio signal may then be transmitted via the antenna 1110. Similarly, when receiving data, the antenna 1110 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1118. The digital data may be passed to the processing circuitry 1102. In other embodiments, the communication interface 1106 may comprise different components and / or different combinations of components.

[0115] In certain alternative embodiments, the network node 1100 does not include separate radio front-end circuitry 1118; instead, the processing circuitry 1102 includes radio front-endcircuitry and is connected to the antenna 1110. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1112 is part of the communication interface 1106. In still other embodiments, the communication interface 1106 includes the one or more ports or terminals 1116, the radio front-end circuitry 1118, and the RF transceiver circuitry 1112 as part of a radio unit (not shown), and the communication interface 1106 communicates with the baseband processing circuitry 1114, which is part of a digital unit (not shown).

[0116] The antenna 1110 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1110 may be coupled to the radio front-end circuitry 1118 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1110 is separate from the network node 1100 and connectable to the network node 1100 through an interface or port.

[0117] The antenna 1110, the communication interface 1106, and / or the processing circuitry 1102 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node 1100. Any information, data, and / or signals may be received from a UE, another network node, and / or any other network equipment. Similarly, the antenna 1110, the communication interface 1106, and / or the processing circuitry 1102 may be configured to perform any transmitting operations described herein as being performed by the network node 1100. Any information, data, and / or signals may be transmitted to a UE, another network node, and / or any other network equipment.

[0118] The power source 1108 provides power to the various components of the network node 1100 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1108 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1100 with power for performing the functionality described herein. For example, the network node 1100 may be connectable to an external power source (e.g., the power grid or an electricity outlet) via input circuitry or an interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1108. As a further example, the power source 1108 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0119] Embodiments of the network node 1100 may include additional components beyond those shown in Figure 11 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1100 may include userinterface equipment to allow input of information into the network node 1100 and to allow output of information from the network node 1100. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1100. In some embodiments providing a core network node, such as core network node 108 of FIG. 9, some components, such as the radio front-end circuitry 1118 and the RF transceiver circuitry 1112 may be omitted.

[0120] Figure 12 is a block diagram illustrating a virtualization environment 1200 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices, and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more Virtual Machines (VMs) implemented in one or more virtualization environments 1200 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, a UE, a core network node, or a host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1200 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface. Virtualization may facilitate distributed implementations of a network node, a UE, a core network node, or a host.

[0121] Applications 1202 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 1200 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0122] Hardware 1204 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, an input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1206 (also referred to as hypervisors or Virtual Machine Monitors (VMMs)), provide VMs 1208A and 1208B (one or more of which may be generally referred to as VMs 1208), and / or perform any of the functions, features, and / or benefits described in relation with some embodiments describedherein. The virtualization layer 1206 may present a virtual operating platform that appears like networking hardware to the VMs 1208.

[0123] The VMs 1208 comprise virtual processing, virtual memory, virtual networking, or interface and virtual storage, and may be run by a corresponding virtualization layer 1206. Different embodiments of the instance of a virtual appliance 1202 may be implemented on one or more of VMs 1208, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as Network Function Virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers and customer premise equipment.

[0124] In the context of NFV, a VM 1208 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1208, and that part of the hardware 1204 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1208 on top of the hardware 1204 and corresponds to the application 1202.

[0125] The hardware 1204 may be implemented in a standalone network node with generic or specific components. The hardware 1204 may implement some functions via virtualization. Alternatively, the hardware 1204 may be part of a larger cluster of hardware (e.g., such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1210, which, among others, oversees lifecycle management of the applications 1202. In some embodiments, the hardware 1204 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1212 which may alternatively be used for communication between hardware nodes and radio units.

[0126] Although the computing devices described herein (e.g., UEs, network nodes) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions, and methods disclosed herein. Determining, calculating,obtaining, or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0127] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0128] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

CLAIMS1. A method performed by a network node (300; 302-1; 302-2), the method comprising any one or more of the following: obtaining (401 and 402), from a User Equipment, UE, (306), information about a downlink time delay difference between reception of a first downlink reference signal associated to a first Transmission and Reception Point, TRP, (302-1) and reception of a second downlink reference signal associated to a second TRP (302-2); receiving (403), from the UE (306), an uplink reference signal at both the first TRP (302-1) and the second TRP (302-2); determining (404) an uplink time delay difference between reception of the uplink reference signal at the first TRP (302-1) and reception of the uplink reference signal at the second TRP (302-2); and determining (405) a timing offset between the first TRP (302-1) and the second TRP (302-2) based on the determined uplink time delay difference and the determined downlink time delay difference.

2. The method of claim 1, further comprising performing (407) one or more actions based on the determined timing offset and / or using the determined timing offset.

3. The method of claim 1 or 2, wherein the uplink reference signal is a Sounding Reference Signal, SRS, or a Demodulation Reference Signal, DMRS, of a Physical Uplink Shared Channel, PUSCH, or a DMRS of a Physical Uplink Control Channel, PUCCH.

4. The method of claim 1 or 2, wherein the uplink reference signal is a Sounding Reference Signal, SRS, transmitted by the UE (306) on a single SRS port.

5. The method of claim 1 or 2, wherein the uplink reference signal is a Sounding Reference Signal, SRS, transmitted by the UE (306) on multiple SRS ports, wherein determining (404) the uplink time delay difference comprises combining (e.g., averaging, computing the mean of, or computing a median of) estimated uplink time delay measurements obtained for the multiple SRS ports.

6. The method of any of claims 1 to 5, wherein determining (404) the uplink time delay difference comprises determining (404) the uplink time delay difference, DUL, as:^DUL— DUL2DUL1where DUL2is an uplink time delay at the second TRP (302-2) and DUL1is an uplink time delay at the first TRP (302-1).

7. The method of claim 6, wherein determining (405) the timing offset between the first TRP (302-1) and the second TRP (302-2) comprises determining (405) the timing offset, AT, between the first TRP (302-1) and the second TRP (302-2) as:wherein DULis the determined uplink time delay difference and DDLis the downlink time delay difference obtained from the UE (306).

8. The method of any of claims 1 to 7, comprising:Repeating (406), for one or more additional UEs, the s of obtaining (401 and 402) information about a downlink time delay difference between reception of a first downlink reference signal (e.g., TRS, CSI-RS, DMRS, or the like) associated to the first TRP (302-1) and reception of a second downlink reference signal associated to the second TRP (302-2), receiving (403) an uplink reference signal at both the first TRP (302-1) and the second TRP (302-2), determining an uplink time delay difference between reception of the uplink reference signal at the first TRP (302-1) and reception of the uplink reference signal at the second TRP (302-2), and determining (405) a timing offset between the first TRP (302-1) and the second TRP (302-2) based on the determined uplink time delay difference and the determined downlink time delay difference, thereby obtaining one or more additional timing offsets; and combining (e.g., averaging, compute mean of, compute media of, or any other kind of joint processing of) (406) the timing offset obtained for the UE (306) and at least one of the one or more additional timing offsets to provide a combined timing offset.

9. The method of claim 8, wherein at least one timing offset from among a set of timing offsets consisting of the timing offset computed for the UE (306) and the one or more additional timing offsets computed for the one or more additional UEs is excluded from consideration when combining (406) to provide the combined timing offset.

10. The method of claim 9, wherein the excluded timing offset(s) is(are) those timing offsets from among the set of timing offsets that: is(are) associated to an uplink received power that is less than an uplink received powerthreshold (e.g., a predefined or configured threshold), or is(are) associated to a reported downlink reference signal received power that is less than a downlink reference signal received power threshold (e.g., a predefined or configured threshold), or is(are) associated with a downlink reference signal SINR that is less than a downlink SINK threshold (e.g., a predefined or configured SINR threshold), or has(have) a value that is different than the other timing offsets in the set by more than a threshold amount (e.g., a predefined or configured threshold amount), or is(are) associated to an uplink received power that is less than uplink received power(s) associated with one or more other UEs by a threshold (e.g., a predefined or configured threshold), or is(are) associated to a reported downlink reference signal received power that is less than downlink reference signal received power(s) associated with one or more other UEs by a threshold (e.g., a predefined or configured threshold), or is(are) associated with a downlink reference signal SINR that is less than downlink SINR(s) associated with one or more other UEs by a threshold (e.g., a predefined or configured SINR threshold).

11. The method of any of claims 8 to 10, wherein the number of additional UEs is dynamically adapted (e.g., by the network node (300)).

12. The method of claim 8, wherein combining (406) the timing offset obtained for the UE (306) and at least one of the one or more additional timing offsets to provide the combined timing offset comprises computing a weighted average of the timing offset obtained for the UE (306) and the one or more additional timing offsets to provide the combined timing offset.

13. The method of claim 12, wherein weights are assigned to the timing offsets based on assessed accuracy of the timing offsets.

14. The method of claim 12, wherein weights are assigned to the timing offsets based on any one or more of the following criteria: reference signal bandwidth of downlink reference signals used for determining the downlink time delay difference;reference signal bandwidth of the uplink reference signal used for determining the uplink time delay difference; channel characteristics of the wireless channels between the first and second TRPs (302-1 and 302-2) and the associated UE; whether the time offset is based on a set of signals (e.g., averaging of measurements for multiple SRS ports) or a single signal; delay between downlink signals at the UE from the first and second TRPs (302-1 and 302- 2); reporting quantization errors (e.g., for the reporting of the downlink time delay difference); received signal quality of the downlink reference signals at the UE and / or of the uplink reference signal at the first and the second TRPs, where the signal quality can be received signal power and / or signal to interference plus noise ratio.

15. The method of any of claims 8 to 14, further comprising performing (407) one or more actions based on the combined timing offset and / or using the combined timing offset.

16. The method of any of claims 1 to 15, wherein the network node comprises a network controller (304), the first TRP (302-1), and the second TRP (302-2).

17. A network node (300; 1100) comprising: processing circuitry (1102) configured to cause the network node to perform any of the s of any of claims 1 to 16; and power supply circuitry (1108) configured to supply power to the processing circuitry.

18. A network node (300; 1100) adapted to perform the method of any of claims 1 to 16.

19. A computer program comprising instructions which, when executed on at least one processor, cause the processor to carry out the method according to any of claims 1 to 16.

20. A carrier containing the computer program of claim 19, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium.

21. A non-transitory computer-readable medium comprising instructions executable by processing circuitry of a network node (300), whereby the network node (300) is operable to perform the method of any of claims 1 to 16.

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