A method for reference signal time synchronization and calibration

Abstract

The present disclosure describes methods and systems for configuring, requesting, performing, and reporting timing measurements of reference signals in a wireless network for the purpose of time synchronization between various reference signal transmit - receive points in the wireless network. The reference signal timing measurements can be used to derive time offsets to perform time synchronization and calibration of the transmit - receive points, which helps to improve the geolocation of wireless devices in the wireless network.

Description

Technical Field

[0001] This disclosure relates to reference signal timing measurement, synchronization, and calibration in a wireless communication network. Background Art

[0002] Wireless communication technologies are driving the world towards rapidly growing network connectivity. In many applications, such as Industrial Internet of Things (IIoT) and Vehicle-to-X (V2X) applications (including vehicle-to-infrastructure, vehicle-to-network, vehicle-to-pedestrian applications, etc.), it is desired to accurately determine the locations of various wireless network nodes and devices. For example, the estimation of the location of a wireless network node or device in a wireless communication network can be determined based on the propagation time of a reference signal between the wireless network node and the device. The propagation time of the reference signal can be determined based on the measurements of the transmission time and reception time of the reference signal in different local time frames reported by various network nodes and devices. When the different local time frames of the network nodes and devices are not synchronized and the time offset between them is unknown, the propagation time of the reference signal determined in this way becomes distorted, resulting in an incorrect location estimate. Summary of the Invention

[0003] This disclosure describes reference signal timing measurement, synchronization, and calibration in a wireless communication network.

[0004] In one embodiment, a method for reference signal synchronization in a wireless network performed by a network node is disclosed. The method includes sending reference signal configuration information to a first transmission reception point (TRP 1) and a second transmission reception point (TRP 2) of the wireless network; according to the reference signal configuration information, sending a measurement request to trigger TRP 1 and / or TRP 2 to perform timing measurement of the reference signal transmitted between TRP 1 and TRP 2; receiving a measurement report of the timing measurement from TRP 1 and / or TRP 2; and generating time offset information for synchronization between TRP 1 and TRP 2.

[0005] In the above embodiment, the network node may include a reference signal scheduling entity, and TRP 1 and TRP 2 include radio base stations.

[0006] In any of the above embodiments, the reference signal configuration information may include at least one of the transmission period of the reference signal transmitted between TRP 1 and TRP 2, transmission radio resource information, sequence information, transmission and / or reception scheduling information, initialization time information of the system frame number (SFN), or transmission and / or reception beam information.

[0007] In any of the above embodiments, the transmission and / or reception scheduling information of each reference signal includes at least one of a SFN, a subframe number, a time slot number, a symbol number, a mini-time slot number, a symbol number or a symbol index.

[0008] In any of the above embodiments, the transmission wireless resource information includes at least one of the radio frequency, radio frequency bandwidth or subcarrier spacing of each reference signal.

[0009] In any of the above embodiments, the transmit and / or receive beam information of each reference signal includes a spatial filter. In any of the above embodiments, each measurement request includes at least one of a measurement period, a measurement type, a measurement time resolution, or a reference signal identifier. In any of the above embodiments, the measurement type indicates which timing values ​​of the reference signal need to be measured and reported by TRP 1 and TRP 2.

[0010] In any of the above embodiments, each measurement report may include at least one of a reference signal measurement time value, a corresponding reference signal identifier, a measurement timestamp, a measurement quality metric, or a measurement time resolution.

[0011] In any of the above embodiments, the measurement timestamp may include at least one of a system frame number, a subframe number, a timeslot number, a mini-timeslot number, a symbol number, or a symbol index. In any of the above embodiments, the measurement quality metric includes at least one of an average or a standard deviation of a plurality of measurements, or a measurement confidence level.

[0012] In any of the above embodiments, the reference signal scheduled by the reference signal configuration information may include: a first reference signal (Reference Signal, RS 1), measured at time TRP 1 trp1,RS1,tx The first reference signal (RS 1) is sent from TRP 1 and is measured at time T trp2,RS1,rx The first reference signal (RS1) is received by TRP 2; and the second reference signal (RS2) is received by TRP 2 at the time T trp2,RS2,tx The second reference signal (RS 2) is sent from TRP 2 and is measured at time T trp1,RS2,rx The second reference signal (RS 2) is received by TRP 1.

[0013] In any of the above embodiments, the measurement report from TRP 1 may include T trp1,RS1,tx , T trp1,RS2,rx , or T trp1,RS2,rx -T trp1,RS1,tx and the measurement report from TRP 2 includes Ttrp2,RS2,tx 、 T trp2,RS1,rx or T trp2,RS2,tx - or at least one of them. In addition, the generation time offset may include generating a time offset for synchronizing TRP 1 and TRP 2 based on at least one of T trp1,RS1,tx 、 T trp1,RS2,rx 、 T trp2,RS2,tx and T trp2,RS1,rx . In any of the above embodiments, the time offset is derived by the network node as [(T trp2,RS1,rx - T trp1,RS1,tx ) – (T trp1,RS2,rx - T trp2,RS2,tx )] / 2.

[0014] In any of the above embodiments, the time offset is derived by the network node as E sync_12 = T trp1,RS2,rx - T trp2,RS2,tx - R 12 / c or E sync_21 = T trp2,RS1,rx - T trp1,RS1,tx - R 12 / c, where R 12 represents the distance between TRP 1 and TRP 2, and c represents the signal propagation speed of the reference signal between TRP 1 and TRP 2.

[0015] In some other embodiments, a method for reference signal synchronization in a wireless network performed by a network node is disclosed. The method may include sending reference signal configuration information to a first transmission and reception point (TRP 1), a second transmission and reception point (TRP 2), and a third transmission and reception point (TRP 3) of the wireless network; sending a measurement request to trigger TRP 1, TRP 2, and / or TRP 3 to perform timing measurements on the reference signals transmitted between TRP 1, TRP 2, and TRP 3 according to the reference signal configuration information; receiving measurement reports of the timing measurements from TRP 1, TRP 2, and / or TRP 3; and generating time offset information for synchronizing TRP 1, TRP 2, and TRP 3.

[0016] In any of the above embodiments, the reference signal scheduled by the reference signal configuration information may include: a first reference signal (RS 1), at the time T measured by TRP 1 trp1,RS1,tx Transmit the first reference signal (RS 1) from TRP 1, and at the time T measured by TRP 2 trp2,RS1,rx Receive the first reference signal (RS 1) by TRP 2, and at the time T measured by TRP 3 trp3,RS1,rxThe first reference signal (RS 1) is received by TRP 3; the second reference signal (RS 2), at time T measured by TRP 2 trp2,RS2,tx The second reference signal (RS 2) is sent from TRP 2 and at time T measured by TRP 1 trp1,RS2,rx The second reference signal (RS 2) is received by TRP 1; and the third reference signal (RS 3), at time T measured by TRP 3 trp3,RS3,tx The third reference signal (RS 3) is sent from TRP 3 and at time T measured by TRP 1 trp1,RS3,rx The third reference signal (RS 3) is received by TRP 1.

[0017] In any of the above embodiments, the measurement report from TRP 1 may include T trp1,RS1,tx , T trp1,RS2,rx , or T trp1,RS2,rx -T trp1,RS1,tx at least one of; the measurement report from TRP 2 includes T trp2,RS2,tx , T trp2,RS1,rx or T trp2,RS2,tx -T trp2,RS1,rx at least one of; and the measurement report from TRP 3 includes T trp3,RS1,rx , T trp3,RS3,tx or T trp3,RS3,tx -T trp3,RS1,rx at least one of.

[0018] In any of the above embodiments, generating a time offset may include generating a time offset for synchronizing TRP 2 and TRP 3 based on at least one of T trp1,RS1,tx , T trp1,RS2,rx , T trp2,RS2,tx , T trp2,RS1,rx , T trp3,RS3,tx , and the reference signal time delay between RS 2 and RS 3 measured by TRP 1 and represented by T trp2,trp3,RSTD .

[0019] In any of the above embodiments, the time offset for synchronizing TRP 2 and TRP 3 is derived by a network node as:

[0020]

[0021] where:

[0022] T trp1,RS3,RS1 = T trp1,RS3,rx - T trp1,RS1,tx ;

[0023] T trp3,RS3,RS1 = T trp3,RS3,tx - Ttrp3,RS1,rx ;

[0024] T trp1,RS2,RS1 = T trp1,RS2,rx - T trp1,RS1,tx ; and

[0025] T trp2,RS2,RS1 = T trp2,RS2,tx - T trp2,RS1,rx .

[0026] In any of the above embodiments, the time offset for synchronizing TRP 2 and TRP 3 is derived by a network node as E sync_32 = (R 13 - R 12 ) / c - T trp2,trp3,RSTD , where R 12 represents the distance between TRP 1 and TRP 2; R 13 represents the distance between TRP 1 and TRP 3; and c represents the signal propagation speed of the reference signal among TRP 1, TRP 2, and TRP 3.

[0027] Also disclosed are various network nodes or devices. Each of these network nodes or devices includes a processor, where the processor is configured to implement any of the above methods.

[0028] Also disclosed is a computer-readable medium. Such a computer-readable medium includes instructions that, when executed by a computer, cause the computer to execute any of the above methods.

[0029] The above embodiments and other aspects and alternatives of their implementation are described in more detail in the following drawings, description, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Shows various network nodes in a part of a wireless communication network configured to transmit wireless reference signals and their configuration information.

[0031] Figure 2 Shows Figure 1 the timing of reference signal transmission and reception between respective network receiving points of the wireless communication network. DETAILED DESCRIPTION

[0032] The techniques and examples of the implementations and / or embodiments in this disclosure can be used to improve the performance of virtual networks in communication systems. The term "exemplary" is used to mean "an example of...", and unless otherwise stated, does not mean an ideal or preferred example, implementation, or embodiment. These implementations can be embodied in various different forms, and thus, the scope of the present disclosure or the claimed subject matter is intended to be construed as not limited to any of the embodiments described below. The various implementations can be embodied as methods, devices, components, or systems. Thus, the embodiments of the present disclosure can be, for example, in the form of hardware, software, firmware, or any combination thereof.

[0033] By way of introduction, many applications in the new generation of wireless communication networks require high-precision geolocation of various network devices. Such applications include, but are not limited to, industrial Internet of Things (IIoT) and V2X applications (including vehicle-to-infrastructure, vehicle-to-network, vehicle-to-pedestrian applications, etc.).

[0034] The geographical location of a wireless network device (mobile or fixed) can be obtained using hyperbolic, triangulation, or other methods that first determine its distance from other network devices with known locations. For example, such a distance can be obtained by measuring the time of flight of a wireless signal transmitted between network devices. A wireless signal designed for time-of-flight measurement can be referred to as a reference signal (as understood by those of ordinary skill in the art, such reference signals can be designed for purposes other than timing measurement, such as power control). Specifically, assuming a line-of-sight wireless signal propagation, the distance between two wireless devices can be estimated by multiplying the time of flight of the reference signal for communication between the two wireless devices by the propagation speed of the reference signal (e.g., close to the speed of light, denoted by c).

[0035] To determine the time of flight of the reference signal, the time when the reference signal is sent from a first transmitting network device and the time when the reference signal is received by a second receiving network device are required. The transmission time and the reception time can be measured, recorded, and reported by the first and second network devices, respectively.

[0036] The transmission time or reception time of a reference signal can be measured relative to the local time frames of a first transmitting network device and a second receiving network device, respectively. These local time frames may not be synchronized with sufficient accuracy. Therefore, the propagation time (referred to as the apparent time of flight) determined by the difference between the reception time of a reference signal measured using one local time frame and the transmission time of the same reference signal measured using another local time frame may include (or be embedded with) the time offset between the two local time frames due to the lack of synchronization. Without calibration, this time offset will cause a deviation or error between the measured apparent propagation time and the corresponding true (or actual) propagation time. This deviation will further lead to unacceptable errors in position estimation. By considering the time offset between the local time frames of the reference signal transmitting device and the receiving device, the apparent propagation time can be calibrated to obtain the true propagation time of the reference signal, thereby enabling more reliable position estimation.

[0037] In wireless networks such as Fourth Generation (4G) and Fifth Generation (5G) cellular networks, it is particularly important for base stations to determine the time offset between local time frames. Specifically, since the positioning of all mobile devices is usually based on triangulation with two or more base stations (or other reference signal transmission points) at known locations and relies on the Reference Signal Time Difference (RSTD) representing the time difference of reference signals arriving at the mobile device from two or more base stations, the time offset between the local time frames of these base stations cannot be ignored and needs to be continuously monitored and considered to achieve high-precision positioning of mobile devices.

[0038] The present disclosure generally relates to methods, devices, and systems for configuring, scheduling, and reporting timing measurements of reference signals transmitted and received between various transmit-receive points (or network nodes) in a wireless communication network, and for reference signal time synchronization and calibration purposes based on the timing measurements. Although the following exemplary embodiments may be provided from time to time in the context of base station synchronization / time offset estimation in 4G or 5G cellular networks for the specific purpose of improving position estimation accuracy, the basic principles of the present disclosure generally also apply to fixed or mobile wireless network nodes or devices other than base stations, wireless infrastructures other than 4G or 5G networks, and other purposes that require synchronization of reference signals.

[0039] Figure 1Shows various network nodes in a part of a wireless network, including network nodes in the form of three transmit-receive points (TRPs) TRP 1 (102), TRP 2 (104), and TRP 3 (107), which communicate wirelessly with each other and further communicate with a reference signal (RS) scheduling entity (SE) 101. The SE 101 can communicate with the TRPs in any way via any communication channel. The SE can be centralized or distributed in the wireless network.

[0040] In the context of 4G (including Long Term Evolution, LTE) or 5G cellular networks, the TRPs 102, 104, and 107 can include base stations and other wireless access points within a radio access network (RAN), such as 4G base stations, 5G NR (New Radio, NR) base stations, 5G central unit base stations, or 5G distributed unit base stations (various 5G base stations may alternatively be referred to as next generation node B or gNB). Using Figure 1 TRP 1 in as an example, each type of these TRPs can include a transceiver circuit 114 coupled to one or more antennas 116 to enable wireless communication with user equipment ( Figure 1 not shown in) and other TRPs. The transceiver circuit 114 can be coupled to one or more processors 120, which can also be coupled to a memory 122 or other storage devices. The memory 122 can store instructions or code therein, and when these instructions or code are read and executed by the processor 120, cause the processor 120 to implement various network functions. For example, these network functions can include functions related to time synchronization and calibration of the reference signals described below.

[0041] Furthermore, in the context of 4G or 5G cellular networks, the SE 101 can be implemented as one or more location servers or units or any other network node. The SE 101 can be part of the core network or the RAN. For example, the SE 101 can be integrated with any core network function. Alternatively, the SE 101 can be implemented as a processing unit within any TRP. As Figure 1 shown, the SE 101 can include one or more processors 110, which can further be coupled to a memory 112 or other storage devices. The memory 112 can store instructions or code therein, and when these instructions or code are read and executed by the processor 110, cause the processor 110 to implement various network functions. For example, these network functions can include functions related to time synchronization and calibration of the reference signals described below.

[0042] In some embodiments, as Figure 1 shown in 111, 113, and 115 of Figure 1 , SE 101 may transmit RS configuration information to TRPs 102, 104, and 107. As Figure 1 shown in 111, 113, and 115 of Figure 1 , when SE 101 or other network elements determine the time calibration and synchronization between the local time frames of the TRPs as needed, SE 101 may further transmit RS timing measurement requests to TRPs 102, 104, and 107. Alternatively, SE 101 may transmit RS timing measurement requests periodically or at any scheduled time.

[0043] After receiving the RS configuration information and RS timing measurement requests from SE 101, TRPs 102, 104, and 107 may send and receive reference signals among themselves according to the RS configuration information. For example, as Figure 1 shown in 121 and 125 of Figure 1 , TRP 1 (102) may transmit a first reference signal RS 1 according to a schedule, and RS 1 may then be received by TRP 2 (104) and TRP 3 (107). In response to receiving RS 1 or spontaneously, TRP 2 (104) and TRP 3 (107) may transmit reference signals RS 2 and RS 3 to TRP 1 (102) according to a schedule, as Figure 1 shown in 123 and 124 of Figure 1 . The TRPs may receive these reference signals, determine, and record the arrival times of reference signals RS 1, RS 2, and RS 3 relative to their respective local time frames.

[0044] After the timing measurement, TRPs 102, 104, and 107 may report various transmission times and reception times of reference signals RS 1, RS 2, and RS 3, as well as other information, to SE 101, as Figure 2 shown in 132, 134, and 136 of Figure 2 . After SE 101 receives the reports from TRPs 102, 104, and 107, it may continue to analyze the reported timing information and other information to estimate the time offsets between the local time frames of TRPs 102, 104, and 107.

[0045] Details involved in various steps performed by SE 101 and TRPs 102, 104, and 107 as described above and shown in Figure 2 are further provided below. Although Figure 1 illustrated with an example of three different TRPs, any other number of TRPs may be included and distributed in the wireless communication network 100.

[0046] RS Configuration Information

[0047] The RS configuration information sent from SE 101 to TRP 1, TRP 2, and TRP 3 is intended to provide the TRPs with the scheduling, radio resources, and signal configuration of the reference signals. The RS configuration information can be transmitted to the TRPs via any communication channel and in the form of any system message. Such information can include, but is not limited to, at least one of the following information items:

[0048] · Periodicity of the reference signal;

[0049] · RF (Radio Frequency) frequency (logical or physical) of the reference signal;

[0050] · RF bandwidth of the reference signal;

[0051] · Spacing of the subcarriers used for transmitting the reference signal,

[0052] · Sequence of the reference signal (e.g., OFDM (Orthogonal Frequency Division Multiplexing) symbol sequence);

[0053] · Scheduled transmission time of the reference signal in a time slot corresponding to the reference signal transmission time, e.g., in system frame number (SFN), subframe number, time slot number, mini-slot number, and symbol number or symbol index (e.g., OFDM symbol number);

[0054] · Scheduled reception time of the reference signal in a time slot corresponding to the reference signal reception time, e.g., in system frame number (SFN), subframe number, time slot number, mini-slot number, and symbol number or index (e.g., OFDM symbol number);

[0055] · SFN initialization time, e.g., Coordinated Universal Time (UTC) of the TRP; or

[0056] · Beam information for reference signal transmission and reception, e.g., spatial filter. The spatial filter used for receiving the reference signal and transmitting another reference signal by the same TRP can be the same. For example, for Figure 1The spatial filters for the TRP 1 to transmit RS 1 and receive RS 2 can be the same, and the spatial filters for the TRP 2 to receive RS 1 and transmit RS 2 can be the same. The spatial filter information can include any one of Quasi Co-Location (QCL) information, QCL type D information, Transmission Configuration Indicator (TCI), Sounding Reference Signal (SRS) resource indicator, Channel State Information Reference Signal (CSI-RS) resource indicator, beam group indicator, TCI status information, or TCI status group information.

[0057] The above RS configuration information provides a basis for the TRP to schedule and configure its reference signal transmission and reception.

[0058] RS Timing Measurement Request

[0059] The RS timing measurement requests sent from the SE 101 to the TRP 1, TRP 2, and TRP 3 are intended to trigger RS timing measurement and reporting. The RS timing measurement requests can be transmitted to the TRP via any communication channel and in the form of any system message. The RS timing measurement requests can be transmitted together with the RS configuration information message or separately. The information contained in the RS timing measurement requests includes, but is not limited to, the RS measurement period, the RS measurement type (e.g., specifying the timing value to be measured and reported), the RS timing measurement resolution, and at least one of the RS indices identifying the reference signals to be measured (e.g., Figure 1 the RS 1 sent from the TRP 1 and the RS 1 received by the TRP 2 in

[0060] Timing Measurement Performed by TRP

[0061] After receiving the RS configuration information and the RS timing measurement requests from the SE 101, the TRPs 102, 104, and 107 can transmit and receive reference signals 121, 125, 123, and 124, as Figure 1 shown. Each of the TRPs 102, 104, and 107 can measure the time when it transmits one or more reference signals and the time when it receives one or more reference signals. These times are measured relative to the local time frames of each of the TRPs 102, 104, and 107.

[0062] Figure 2 shows Figure 1Example timings for reference signal transmission and reception between TRPs 102, 104, and 107. The various local reference signal transmission times and reception times are as follows:

[0063] ·T trp1,RS1,tx : Transmission time of RS 1 at TRP 1, as shown in 202 of Figure 2 ;

[0064] ·T trp2,RS1,rx : Time of first detection of received RS 1 at TRP 2, as shown in 212 of Figure 2 ;

[0065] ·T trp3,RS1,rx : Time of first detection of received RS1 at TRP 3, as shown in 222 of Figure 2 ;

[0066] ·T trp2,RS2,tx : Transmission time of RS 2 at TRP 2, as shown in 214 of Figure 2 ;

[0067] ·T trp3,RS3,tx : Transmission time of RS 3 at TRP 3, as shown in 224 of Figure 2 ;

[0068] ·T trp1,RS2,rx : Time of first detection of received RS 2 at TRP 1, as shown in 204 of Figure 2 ; and

[0069] ·T trp1,RS3,rx : Time of first detection of received RS 3 at TRP 1, as shown in 206 of Figure 2 ;

[0070] Figure 2 The various differences between the local transmission times and reception times at the above TRPs are further illustrated as follows:

[0071] ·T trp1,RS2,RS1 : Difference between reception time and transmission time between RS 1 and RS 2 at TRP 1, i.e., T trp1,RS2,rx -T trp1,RS1,tx as shown in 208 of Figure 2 ;

[0072] ·T trp1,RS3,RS1 : Difference between reception time and transmission time between RS 3 and RS 1 at TRP 1, i.e., T trp1,RS3,rx -T trp1,RS1,tx as shown in 209 of Figure 2 ;

[0073] ·Ttrp2,RS2,RS1 : The time difference between the transmission time and the reception time between RS 2 and RS 1 at TRP 2, i.e., T trp2,RS2,tx -T trp2,RS1,rx , as Figure 2 shown in 218 of

[0074] ·T trp3,RS3,RS1 : The time difference between the transmission time and the reception time between RS 3 and RS 1 at TRP 3, i.e., T trp3,RS3,tx -T trp3,RS1,rx , as Figure 2 shown in 228 of

[0075] The time difference between the reception times of RS 2 and RS 3 at TRP 1 can be expressed as where or T trp1,RS3,rx -T trp1,RS2,rx , as Figure 1 indicated by 207 of. This time difference is substantially equal to the RSTD measured by TRP 1 based on the reference signals transmitted from TRP 2 and TRP 3, expressed as T trp2,trp3,RSTD . This RSTD is essentially the relative timing difference between TRP 3 and TRP 2, further defined as T SubframeRx3 -T SubframeRx2 . Where T SubframeRx3 is the time when TRP 1 receives the start of a subframe from TRP 3, and T SubframeRx2 is the corresponding start time of a subframe (closest in time to the subframe received from TRP 3) received by TRP 1 from TRP 2.

[0076] Measurement Report

[0077] After performing the reference signal timing measurement, the TRP can report the measurement to the SE 101. The RS timing measurement report can be transmitted to the SE 101 via any communication channel and in the form of any system message. The report can contain various information items. For example, in the Figure 1 and Figure 2 configuration, the RS timing measurement report from TRP 1 can contain information including but not limited to at least one of the following:

[0078] · Timing values, including T trp1,RS1,tx , T trp1,RS2,rx , T trp1,RS3,rx , T trp1,RS2,RS1 , T trp1,RS3,RS1 , T trp2,trp3,RSTD , or at least one of

[0079] ·One or more RS indexes that identify the measurement reference signal;

[0080] ·The timestamp of the measurement (e.g., the system frame number, subframe number, time slot number, mini-slot number, and symbol number / index in which the measurement is performed);

[0081] ·The measurement quality metric (e.g., when the measurement result is obtained based on multiple reference signal receptions, the measurement quality metric may include, for example, the average value and / or standard deviation of the measurement result, or the confidence level of the measurement result); or

[0082] ·The timing resolution of the RS timing measurement.

[0083] For example, the RS timing measurement report of TRP 2 from the Figure 1 and Figure 2 configurations may contain information including but not limited to at least one of the following:

[0084] ·The timing value, including at least one of T trp2,RS1,rx 、T trp2,RS2,tx or T trp2,RS2,RS1 ;

[0085] ·One or more RS indexes that identify the measurement reference signal;

[0086] ·The timestamp of the measurement (e.g., the system frame number, subframe number, time slot number, mini-slot number, and symbol number / index in which the measurement is performed);

[0087] ·The measurement quality metric (e.g., when the measurement result is obtained based on multiple reference signal receptions, the measurement quality metric may include, for example, the average value and / or standard deviation of the measurement result, or the confidence level of the measurement result); or

[0088] ·The timing resolution of the RS timing measurement.

[0089] For another example, the RS timing measurement report of TRP 2 from the Figure 1 and Figure 2 configurations may contain information including but not limited to at least one of the following:

[0090] ·The timing value, including at least one of T trp3,RS1,rx 、T trp3,RS3,tx or T trp3,RS3,RS1 ;

[0091] ·One or more RS indexes that identify the measurement reference signal;

[0092] ·The timestamp of the measurement (e.g., the system frame number, subframe number, time slot number, mini-slot number, and symbol number / index in which the measurement is performed);

[0093] · Measure a quality metric (e.g., when the measurement result is obtained based on multiple reference signal receptions, the quality metric may include, for example, the average value and / or standard deviation of the measurement result, or the confidence level of the measurement result); or

[0094] · The timing resolution of the RS timing measurement.

[0095] Synchronization Time Offset Estimation

[0096] After SE 101 receives the RS measurement reports from TRP 102, 104, and 107, it can continue to analyze the timing information reported in the local time frames of TRP 102, 104, and 107 to estimate the time offset between these local time frames.

[0097] Method 1

[0098] In some example embodiments, the synchronization time offset between the local time frames of TRP 1 and TRP 2 can be estimated by SE101 as:

[0099]

[0100] Or

[0101]

[0102] As Figure 2 shown, the relative time offset between the local time frames of TRP1 and TRP2 above is determined by the following considerations:

[0103] · The apparent propagation time of RS 1 measured from TRP 1 to TRP 2 (represented by T trp2,RS1,rx -T trp1,RS1,tx ) includes the actual propagation time corresponding to RS 1 and the local time frame offset of TRP2 - TRP1;

[0104] · The apparent propagation time of RS 2 measured from TRP 2 to TRP 1 (represented by T trp1,RS2,rx -T trp2,RS2,tx ) includes the actual propagation time corresponding to RS 2 and the local time frame offset of TRP1 - TRP2;

[0105] · The term (T trp1,RS2,RS1 -T trp2,RS2,RS1) ) / 2 represents Figure 2 the difference between 208 and 218 in

[0106] · Assume that the wireless transmission path from TPR1 to TRP2 and the reverse wireless transmission path from TRP2 to TRP1 are the same. Then, the actual propagation time (or, true propagation time) of RS 1 from TRP1 to TRP2 is the same as the actual propagation time of RS 2 from TRP2 to TRP1;

[0107] · Therefore, the average of the two apparent propagation times (T trp1,RS2,RS1 -T trp2,RS2,RS1) ) / 2 represents the actual propagation time of RS 1 or RS 2 between TRP 1 and TRP 2, where the time offset is eliminated; and

[0108] · Therefore, the difference between the apparent propagation time and the actual propagation time provides the relative time offset between the local time frames of TRP 1 and TRP 2, as represented by the time offset equation above.

[0109] Similarly, SE 101 can estimate the synchronization offset between the local time frames of TRP 1 and TRP 3 using a similar assumption as above, as follows:

[0110]

[0111] or

[0112]

[0113] In the above embodiments, as long as the forward path and the corresponding backward path between each pair of TRPs are the same, the time offset calculation is applicable regardless of whether the actual reference signal transmission path between the TRPs is a line-of-sight (LOS) path. In other words, these reference signal transmission paths can be non-line-of-sight (NLOS) paths, and the above time offset calculation still applies. In an actual wireless communication network, TRPs in the form of base stations can be designed and configured to communicate using the LOS path between them anyway.

[0114] Method 2

[0115] In some other embodiments, the exact relative distance between TRP 1 and TRP2 is known and represented as R 12 . Therefore, SE 101 can estimate the time offset between the local time frames of TRP 1 and TRP 2 as:

[0116] E sync_12 =T trp1,RS2,rx -T trp2,RS2,tx -R 12 / c,

[0117] or

[0118] E sync_21 = T trp2,RS1,rx - T trp1,RS1,tx - R 12 / c,

[0119] where c represents the speed of reference signal transmission.

[0120] In the above embodiments, it is assumed that TRP 1 and TRP 2 transmit and receive reference signals in line-of-sight, such that the apparent propagation time in the above equation is only affected by the time offset and not affected by any NLOS. For a TRP in the form of a base station, this is the most likely scenario because wireless networks are typically designed to maintain a direct LOS for the base station. As long as the NLOS path is similar enough to the direct LOS path (with differences on the order of or smaller than the positioning accuracy requirements), the above embodiments still apply in the presence of NLOS.

[0121] Similarly, when the exact relative distance between TRP 1 and TRP3, represented as R 13 is known, SE101 can estimate the synchronization time offset between the local time frames of TRP 1 and TRP 3 as:

[0122] E sync_13 = T trp1,RS3,rx - T trp3,RS3,tx - R 13 / c,

[0123] or

[0124] E sync_31 = T trp3,RS1,rx - T trp1,RS1,tx - R 13 / c.

[0125] For this estimate, it is assumed that TRP 1 and TRP 3 transmit and receive reference signals in line-of-sight, such that the apparent propagation time in the above equation is only affected by the time offset and not affected by any NLOS, which is the most likely scenario for a TRP in the form of a base station. As long as the NLOS path is similar enough to the direct LOS path (with differences on the order of or smaller than the positioning accuracy requirements), the above embodiments still apply in the presence of NLOS.

[0126] Method 3

[0127] In some embodiments, if SE 101 knows the exact relative distance between TRP 1 and TRP 2 (represented by R 12 ), as well as the exact relative distance between TRP 1 and TRP 3 (represented by R 13 ), then even according toFigure 2 No reference signal is sent between TRP 2 and TRP 3, and the time offset between the local time frames of TRP 2 and TRP 3 can also be estimated. Specifically, the synchronization offset between TRP 2 and TRP 3 can be estimated by SE 101 as:

[0128] E sync_32 =(R 13 -R 12 ) / c - T trp2,trp3,RSTD .

[0129] Basically, in the above equation, the first term represents the relative reference signal delay time between TRP 2 and TRP 3 at TRP 1, and there is no time offset between TRP 2 and TRP 3. The second term represents the signal delay measured by TRP 1, which includes the time offset between the local time frames of TRP 2 and TRP 3. Therefore, the difference between these two terms is the time offset between the local time frames of TRP 2 and TRP 3.

[0130] Similar to the above Method 2, this method assumes that, in terms of the required positioning accuracy, the influence of any NLOS signal path can be ignored.

[0131] Method 4

[0132] In some embodiments, the synchronization time offset between the local time frames of TRP 2 and TRP 3 can be estimated by SE 101 as:

[0133]

[0134] In the above estimation, the term (T trp1,RS2,RS1 -T trp2,RS2,RS1) ) / 2 or Figure 2 the difference between 208 and 218 in is the same as the last term of the TRP 1 - TRP 2 time offset estimation in Method 1, and as discussed above regarding Method 1, corresponds to the actual propagation time of the reference signal between TRP 1 and TRP 2. Similarly, the term (T trp1,RS3,RS1 -T trp3,RS3,RS1) ) / 2 or Figure 2 the difference between 209 and 228 in represents the actual propagation time of the reference signal transmitted between TRP 1 and TRP 3, similar to the last term of the TRP 1 - TRP 3 time offset estimation in Method 1. Therefore, the term [(T trp1,RS2,RS1 -T trp2,RS2,RS1) )-(T trp1,RS3,RS1 -T trp3,RS3,RS1))] / 2 represents the RSTD of the reference signals transmitted from TRP 2 and TRP 3 at TRP 1 (where the time offset between TRP 2 and TRP 3 is eliminated). Thus, the difference between it and the measured RSTD (represented by T trp2,trp3,RSTD will provide the synchronization time offset between TRP 2 and TRP 3, as shown in the equation above.

[0135] Similar to Method 1, in the implementation of Method 4 above, as long as the forward path and the corresponding backward path (except for the reverse) between each pair of TRPs are the same, the time offset calculation applies regardless of whether the actual reference signal transmission path between the TRPs is a line-of-sight (LOS) path. In other words, these reference signal transmission paths can be non-line-of-sight (NLOS) paths, and the above time offset calculation still applies. In an actual wireless communication network, a TRP in the form of a base station can be designed and configured to communicate using a line-of-sight path anyway.

[0136] In the various embodiments and methods above, only the behavior of two or three TRPs is described. The basic principle can be extended to perform synchronization between any number of TRPs. Therefore, all TRPs can be synchronized. For example, although Method 1 and Method 2 above are intended to determine the synchronization offset between TRP 1 and TRP 2, these methods can be used to similarly determine the synchronization offset between any TRP i and TRP j (where i and j represent any pair of TRPs in a wireless system that can transmit wireless reference signals to each other). One or more TRPs of a wireless system can be used as reference TRPs to determine the time offset of other TRPs using Method 1, Method 2, and other methods derivable therefrom. Similarly, although Method 3 and Method 4 above are used to determine the time offset between TRP 2 and TRP 3 via TRP 1, the time offset between any pair of TRPs including TRP i and TRP j can be determined via another TRP k (where i, j, and k represent any three TRPs in a wireless system that can transmit wireless reference signals to each other). TRP k can be referred to as a reference TRP via which the time offset between any other pair of TRPs (TRP i and TRP j) can be determined using Method 3, Method 4, and / or other methods derivable therefrom.

[0137] The above description and the accompanying drawings provide specific example embodiments and implementations. However, the subject matter described may be embodied in a variety of different forms, and thus, the subject matter covered or claimed is intended to be construed as not limited to any of the example embodiments described herein. The scope of the subject matter claimed or covered is quite broad. Among other things, for example, the subject matter may be embodied as a method, apparatus, component, system, or non-transitory computer-readable medium for storing computer code. Thus, embodiments may take, for example, the form of hardware, software, firmware, a storage medium, or any combination thereof. For example, the above method embodiments may be implemented by a component, device, or system including a memory and a processor by executing computer code stored in the memory.

[0138] Throughout the specification and claims, terms may have subtle meanings, either implicit or implied, in the context that go beyond the explicitly stated meanings. Similarly, the phrase "in one embodiment / implementation" as used herein does not necessarily refer to the same embodiment, and the phrase "in another embodiment / implementation" as used herein does not necessarily refer to a different embodiment. For example, the claimed subject matter includes combinations of all or part of the example embodiments.

[0139] Generally speaking, terms can be understood, at least in part, from their usage in the context. For example, terms such as "and", "or", or "and / or" as used herein can include multiple meanings, which depend, at least in part, on the context in which these terms are used. Generally, "or" if used to relate a list, such as A, B, or C, means A, B, and C when used in an inclusive sense, as well as A, B, or C when used in an exclusive sense. In addition, the term "one or more" as used herein, depending at least in part on the context, can be used to describe any feature, structure, or characteristic in a singular sense, or can be used to describe a combination of features, structures, or characteristics in a plural sense. Similarly, terms such as "a", "an", or "the" can be understood to denote either a singular or a plural usage, at least in part, depending on the context. In addition, the term "based on" can be understood to not necessarily intend to convey a set of exclusive factors and can allow for additional factors that are not necessarily explicitly described, at least in part, depending on the context.

[0140] References in this specification to features, advantages, or similar language do not mean that all features and advantages achievable by the solution should or are included in any single embodiment thereof. On the contrary, language referring to features and advantages is understood to mean that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the solution. Thus, discussions of features and advantages throughout the specification and similar language may, but do not necessarily, refer to the same embodiment.

[0141] Moreover, in one or more embodiments, the features, advantages, and characteristics of the present solution may be combined in any suitable manner. Based on the description herein, those of ordinary skill in the relevant art will recognize that the present solution may be practiced without one or more specific features or advantages of a particular embodiment. In other cases, additional features and advantages that may not exist in all embodiments of the present solution may be identified in certain embodiments.

Claims

1. A method for reference signal synchronization in a wireless network performed by a network node, comprising: Send reference signal configuration information to a first transmission reception point (TRP 1) and a second transmission reception point (TRP 2) of the wireless network; Send a measurement request to at least one of TRP 1 and TRP 2 to trigger timing measurement of reference signals transmitted between TRP 1 and TRP 2 according to the reference signal configuration information; Receive a measurement report of the timing measurement from at least one of TRP 1 and TRP 2, the measurement report including at least one reference signal timing value; And Based on a measurement quality metric associated with the timing measurement, select one or more timing values from the at least one reference signal timing value, and generate time offset information for synchronizing TRP 1 and TRP 2 from the selected one or more timing values.

2. The method according to claim 1, wherein, The network node includes a reference signal scheduling entity, and TRP 1 and TRP 2 include radio base stations.

3. The method according to claim 1, wherein, The reference signal configuration information includes at least one of a transmission period of a reference signal transmitted between TRP 1 and TRP 2, transmission radio resource information, sequence information, transmission and / or reception scheduling information, initialization time information of a system frame number (SFN), or transmission and / or reception beam information.

4. The method according to claim 3, wherein, The transmission and / or reception scheduling information of each reference signal includes at least one of SFN, subframe number, slot number, mini-slot number, or symbol number.

5. The method according to claim 3, wherein, The transmission radio resource information includes at least one of radio frequency, radio frequency bandwidth, or subcarrier spacing of each reference signal.

6. The method according to claim 3, wherein, The transmission and / or reception beam information of each reference signal includes a spatial filter.

7. The method according to claim 1, wherein, Each measurement request includes at least one of a measurement period, a measurement type, a measurement time resolution, or a reference signal identifier.

8. The method according to claim 7, wherein, The measurement type indicates which timing values of the reference signal need to be measured and reported by TRP 1 and TRP 2.

9. The method according to claim 1, wherein, Each measurement report includes at least one of a reference signal measurement time value, a corresponding reference signal identifier, a measurement timestamp, the measurement quality metric, or a measurement time resolution.

10. The method according to claim 9, wherein, The measurement timestamp includes at least one of a system frame number, a subframe number, a slot number, a mini-slot number, a symbol number, or a symbol index.

11. The method according to claim 9, wherein, The measurement quality metric includes at least one of an average value or a standard deviation of multiple measurement results, or a measurement result confidence level.

12. The method according to claim 1, wherein, The reference signals scheduled by the reference signal configuration information include: The first reference signal (RS1) at time T measured by the TRP 1 trp1,RS1,tx Transmit the first reference signal (RS1) from the TRP 1 and at time T measured by the TRP 2 trp2,RS1,rx Receive the first reference signal (RS1) by the TRP 2; and Second reference signal (RS2), at time T measured by the TRP 2 trp2,RS2,tx The second reference signal (RS2) is sent from the TRP 2 and at time T measured by the TRP 1 trp1,RS2,rx The second reference signal (RS2) is received by the TRP 1.

13. The method according to claim 12, wherein: The measurement report from the TRP 1 includes T trp1,RS1,tx , T trp1,RS2,rx or T trp1,RS2,rx -T trp1,RS1,tx at least one of; and The measurement report from the said TRP 2 includes T trp2,RS2,tx , T trp2,RS1,rx or T trp2,RS2,tx -T trp2,RS1,rx at least one of them.

14. The method according to claim 13, wherein, Generating a time offset includes generating, based on at least one of T trp1,RS1,tx , T trp1,RS2,rx , T trp2,RS2,tx and T trp2,RS1,rx , a time offset for synchronizing the TRP 1 and the TRP 2.

15. The method according to claim 14, wherein, The time offset is derived by the network node as [(T trp2,RS1,rx - T trp1,RS1,tx ) – (T trp1,RS2,rx - T trp2,RS2,tx )] / 2.

16. The method according to claim 14, wherein, The time offset is derived by the network node as E sync_12 = T trp1,RS2,rx - T trp2,RS2,tx - R 12 / c or E sync_21 = T trp2,RS1,rx - T trp1,RS1,tx - R 12 / c, where R 12 represents the distance between the TRP 1 and the TRP 2, and c represents the signal propagation speed of the reference signal between the TRP 1 and the TRP 2.

17. A method for reference signal synchronization in a wireless network performed by a network node, comprising: Send reference signal configuration information to a first transmission reception point (TRP 1), a second transmission reception point (TRP 2), and a third transmission reception point (TRP 3) of the wireless network; Send a measurement request to TRP 1, TRP 2, and TRP 3 to trigger timing measurement of reference signals transmitted between TRP 1, TRP 2, and TRP 3 according to the reference signal configuration information; Receive a measurement report of the timing measurement from at least one of TRP 1, TRP 2, and TRP 3, the measurement report including at least one reference signal timing value; And Select one or more timing values from the at least one reference signal timing value according to a measurement quality metric associated with the timing measurement, and generate time offset information for synchronizing the TRP 1, the TRP2, and the TRP 3 from the selected one or more timing values.

18. The method according to claim 17, wherein, The reference signals scheduled by the reference signal configuration information include: The first reference signal (RS1), at time T measured by the TRP 1 trp1,RS1,tx The first reference signal (RS1) is sent from the TRP 1 and at time T measured by the TRP 2 trp2,RS1,rx The first reference signal (RS1) is received by the TRP 2, and at time T measured by the TRP 3 trp3,RS1,rx The first reference signal (RS1) is received by the TRP 3; Second reference signal (RS2), at time T measured by the TRP 2 trp2,RS2,tx Transmit the second reference signal (RS2) from the TRP 2, and at time T measured by the TRP 1 trp1,RS2,rx Receive the second reference signal (RS2) by the TRP 1; and Third reference signal (RS 3) at time T measured by the TRP 3 trp3,RS3,tx The third reference signal (RS 3) is sent from the TRP 3 and at time T measured by the TRP 1 trp1,RS3,rx The third reference signal (RS 3) is received by the TRP 1.

19. The method according to claim 18, wherein: The measurement report from the said TRP 1 includes T trp1,RS1,tx , T trp1,RS2,rx or T trp1,RS2,rx -T trp1,RS1,tx at least one of; The measurement report from the said TRP 2 includes T trp2,RS2,tx , T trp2,RS1,rx or T trp2,RS2,tx -T trp2,RS1,rx at least one of; and The measurement report from the said TRP 3 includes T trp3,RS1,rx , T trp3,RS3,tx or T trp3,RS3,tx -T trp3,RS1,rx or at least one of them.

20. The method according to claim 19, wherein, Generating a time offset includes generating, based on at least one of T trp1,RS1,tx , T trp1,RS2,rx , T trp2,RS2,tx , T trp2,RS1,rx , T trp3,RS3,tx , T trp3,RS1,rx and the reference signal time delay between RS2 and RS3 measured by the TRP 1 and represented by T trp2,trp3,RSTD , a time offset for synchronizing the TRP 2 and the TRP 3.

21. The method according to claim 20, wherein, The time offset for synchronizing the TRP 2 and the TRP 3 is derived by the network node as: Where: T trp1,RS3,RS1 = T trp1,RS3,rx - T trp1,RS1,tx ; T trp3,RS3,RS1 = T trp3,RS3,tx - T trp3,RS1,rx ; T trp1,RS2,RS1 = T trp1,RS2,rx - T trp1,RS1,tx ; and T trp2,RS2,RS1 = T trp2,RS2,tx - T trp2,RS1,rx 。 22. The time offset for synchronizing the said TRP 2 and the said TRP 3 in the method according to claim 20 is derived by the network node as E sync_32 =(R 13 -R 12 ) / c - T trp2,trp3,RSTD , wherein: R 12 represents the distance between the said TRP 1 and the said TRP 2; R 13 represents the distance between the said TRP 1 and the said TRP 3; and c represents the signal propagation speed of the reference signal among the TRP 1, the TRP 2, and the TRP 3.

23. A network node comprising a processor, wherein, The processor is configured to implement the method according to any one of claims 1-22.

24. A computer program product comprising a non - transitory computer - readable program medium having computer code stored thereon, which when executed by a processor causes the processor to implement the method according to any one of claims 1 to 22.

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