Wireless synchronization

Abstract

In accordance with an example aspect of the present disclosure, there is provided an apparatus configured to act at least as a node in a wireless communication system, participate in a synchronization procedure with at least one target node in the wireless communication system, where the apparatus is configured to transmit, via node-to-node signaling, the at least one target node in the wireless communication system as part of the synchronization procedure. A reference signal is transmitted at a time specified in assistance information received from the wireless communication system, and a reception time of a signal from each of the at least one target node is reported to the wireless communication system as part of a synchronization procedure.

Description

Technical Field

[0001] The present disclosure relates to wireless synchronization, for example for wireless positioning. Background Art

[0002] Synchronization between devices (such as user equipment, UE) is of interest in several applications (such as messaging, streaming, and positioning UE). For example, positioning of a UE in a cellular network involves deriving an estimate of the current position of the user equipment. The position estimate can be relative or absolute, which means that the position estimate is expressed in terms of other units or geographical coordinates, respectively. Various mechanisms are used in cellular networks (NW) to derive an estimate of the current position. For example, an estimate can be derived from the time difference of arrival information, and / or a detectable short-range network (such as a wireless local area network, WLAN, hotspot) can be used to assist the estimate. Summary of the invention

[0003] According to some aspects, the subject matter of independent claims is provided. Some embodiments are defined in the dependent claims. The scope of protection sought for various embodiments of the invention is set forth by the independent claims. The embodiments, examples and features described in this specification that do not fall under the scope of the independent claims (if any) are interpreted as examples useful for understanding the various embodiments of the invention.

[0004] According to a first aspect of the present disclosure, there is provided a device comprising at least one processing core and at least one memory storing instructions, wherein when the instructions are executed by the at least one processing core, the device at least: acts as a node in a wireless communication system, participates in a synchronization process with at least one target node in the wireless communication system, wherein the device is configured to, as part of the synchronization process, send a reference signal at a time specified in auxiliary information received from the wireless communication system via node-to-node signaling, and, as part of the synchronization process, report to the wireless communication system the reception time of a signal from each of the at least one target node.

[0005] According to a second aspect of the present disclosure, a device is provided, comprising at least one processing core and at least one memory storing instructions, wherein the instructions, when executed by the at least one processing core, cause the device to at least: act as a node of a wireless communication system, participate in a synchronization process, wherein the device is configured to provide first auxiliary information to at least one other node and to provide second auxiliary information to a target node, the first auxiliary information instructing when to send a reference signal via node-to-node signaling, the second auxiliary information instructing when to send a signal in an uplink or a sidelink, and as part of the synchronization process, receive an indication from at least one other node, and receive at least one indication from the target node, indicating when each of the at least one other node receives a signal from the target node, and at least one indication regarding when the target node receives each of the reference signals.

[0006] According to a third aspect of the present disclosure, a device is provided, comprising at least one processing core and at least one memory storing instructions, wherein the instructions, when executed by the at least one processing core, cause the device to at least: act as a node of a wireless communication system, participate in a synchronization process, wherein the device is configured to provide first auxiliary information to at least one other node and to provide second auxiliary information to a target node, the first auxiliary information instructing when to send a reference signal via node-to-node signaling, the second auxiliary information instructing when to send a signal in an uplink or a sidelink, and as part of the synchronization process, receive an indication from at least one other node, and receive at least one indication from the target node, indicating when each of the at least one other node receives a signal from the target node, and at least one indication regarding when the target node receives each of the reference signals.

[0007] According to a fourth aspect of the present disclosure, a method is provided, comprising: acting as a node of a wireless communication system, participating in a synchronization process with at least one target node of a cellular communication system, wherein the synchronization process comprises sending a reference signal at a time specified in auxiliary information received from the wireless communication system via node-to-node signaling, and reporting, as part of the synchronization process, to the wireless communication system the reception time of a signal from each of the at least one target node.

[0008] According to a fifth aspect of the present disclosure, a method is provided, comprising: acting as a node of a wireless communication system, participating as a target node in a synchronization process with at least one other node of the wireless communication system, wherein the other nodes of the wireless communication system are notified of the reception time of a reference signal from each of the at least one other node via node-to-node signaling, and as part of the synchronization process, sending a signal in an uplink or a side link at a time specified in auxiliary information received from the wireless communication system.

[0009] According to a sixth aspect of the present disclosure, a method is provided, comprising: acting as a node of a wireless communication system, participating in a synchronization process, wherein first auxiliary information is provided to at least one other node, the first auxiliary information instructing when to send a reference signal via node-to-node signaling, and wherein second auxiliary information is provided to a target node, the second auxiliary information instructing when to send a signal in an uplink or a sidelink, and as part of the synchronization process, receiving an indication from at least one other node, and receiving at least one indication from the target node, indicating when each of the at least one other node receives a signal from the target node, and at least one indication regarding when the target node receives each of the reference signals.

[0010] According to a seventh aspect of the present disclosure, a device is provided, comprising: a component for acting as a node of a wireless communication system, a component for participating in a synchronization process with at least one target node of the wireless communication system, wherein the synchronization process includes sending a reference signal at a time specified in auxiliary information received from the wireless communication system via node-to-node signaling, and a component for reporting the reception time of a signal from each of the at least one target node to the wireless communication system as part of the synchronization process.

[0011] According to an eighth aspect of the present disclosure, there is provided an apparatus comprising: a component for acting as a node of a wireless communication system, a component for participating as a target node in a synchronization process with at least one other node of a cellular communication system, wherein the other nodes of the wireless communication system are notified of the reception time of a reference signal from each of the at least one other node via node-to-node signaling, and a component for sending a signal in an uplink or a sidelink at a time specified in auxiliary information received from the wireless communication system as part of the synchronization process.

[0012] According to a ninth aspect of the present disclosure, there is provided an apparatus comprising: a component for acting as a node of a wireless communication system, a component for participating in a synchronization process, wherein first auxiliary information is provided to at least one other node, the first auxiliary information instructing when to send a reference signal via node-to-node signaling, and wherein second auxiliary information is provided to a target node, the second auxiliary information instructing when to send a signal in an uplink or a sidelink, and a component for receiving, as part of the synchronization process, indications from at least one other node and at least one indication from the target node, indicating when each of the at least one other node receives a signal from the target node, and at least one indication regarding when the target node receives each of the reference signals.

[0013] According to the tenth aspect of the present disclosure, a non-transitory computer-readable medium is provided, on which a set of computer-readable instructions is stored. When the computer-readable instruction set is executed by at least one processor, the device at least: acts as a node of a wireless communication system, participates in a synchronization process with at least one target node in the wireless communication system, wherein the device is configured to send a reference signal at a time specified in auxiliary information received from the wireless communication system via node-to-node signaling as part of the synchronization process, and reports to the wireless communication system the reception time of the signal from each of the at least one target node as part of the synchronization process.

[0014] According to the eleventh aspect of the present disclosure, a non-transitory computer-readable medium is provided, on which a set of computer-readable instructions is stored, and when the computer-readable instruction set is executed by at least one processor, the device at least: acts as a node of a cellular communication system, participates as a target node in a synchronization process with at least one other node of the cellular communication system, wherein the device is configured to notify other nodes of the wireless communication system of the reception time of a reference signal from each of the at least one other node via node-to-node signaling, and as part of the synchronization process, sends a signal in an uplink or a sidelink at a time specified in auxiliary information received from the wireless communication system.

[0015] According to the twelfth aspect of the present disclosure, a non-transitory computer-readable medium is provided, on which a set of computer-readable instructions is stored, and when the computer-readable instruction set is executed by at least one processor, the device at least: acts as a node of a wireless communication system, participates in a synchronization process, wherein the device is configured to provide first auxiliary information to at least one other node and provide second auxiliary information to a target node, the first auxiliary information instructing when to send a reference signal via node-to-node signaling, the second auxiliary information instructing when to send a signal in an uplink or a side link, and as part of the synchronization process, receiving an indication from at least one other node, and receiving at least one indication from the target node, indicating when each of the at least one other node receives a signal from the target node, and at least one indication regarding when the target node receives each of the reference signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 An example system is shown in accordance with at least some embodiments of the present invention;

[0017] Figure 2 illustrates signal timing according to at least some embodiments of the present invention;

[0018] Figure 3 An example apparatus capable of supporting at least some embodiments of the present invention is shown;

[0019] Figure 4 shows signaling according to at least some embodiments of the present invention, and

[0020] Figure 5 is a flow chart of a method according to at least some embodiments of the present invention. Example

[0021] This article describes a process for achieving more accurate device or UE synchronization that can be used in several applications, such as message reception and positioning based on observed arrival time difference OTDOA. In detail, as part of the synchronization process, a group of anchor UEs transmit reference signals, and a target UE or a group of multiple target UEs transmit signals in an uplink or sidelink. As part of the synchronization process, the target UE reports the reception timestamp of the reference signal at the target UE, and the anchor UE reports the reception timestamp of the signal from the target UE. The timestamp indicates the reception moment in terms of the clock of the receiving UE. The timestamp is reported to a node such as a core network node to derive an estimate of the synchronization parameters between the anchor UEs. This enables, for example, OTDOA positioning to have an accuracy with an uncertainty that is up to one order of magnitude lower than that without using signals from the target UE. A reference signal is transmitted from an anchor UE or from at least one anchor device in a sidelink, which means direct UE-to-UE communication, in which a wireless signal is transmitted from a first UE and received in a second UE, and the signal is not retransmitted along the way by any other node (e.g., a base station). The signal from the target UE can be transmitted in a sidelink or an uplink. Although this document is mainly discussed in terms of UE, in general other types of nodes or devices may also be configured to use the synchronization and / or positioning mechanisms disclosed herein. A UE is an illustrative example of such a node or device.

[0022] Figure 1 An example system according to at least some embodiments of the present invention is shown. The cellular communication system includes a radio access network and a cellular core network 130. The radio access network includes at least one base station 120, and it may include hundreds or even thousands of base stations. The base stations may be configured to control at least one cell respectively. Examples of cellular communication systems include fifth generation 5G systems, wideband code division multiple access WCDMA systems, and long term evolution LTE systems.

[0023] User equipment (UE) 112, 114, 116 is communicatively coupled to base station 120 via a wireless link 121 to achieve interoperability, and the wireless link 121 conforms to the same communication standard as UE 112, 114, 116 and base station 120. The wireless link 121 may include a downlink DL involving communication from the base station to the UE and an uplink UL involving communication from the UE to the base station. If applicable, UE 112, 114, 116 may each include a smart phone, a cellular phone, a tablet, an IoT node, a laptop or desktop computer, or, for example, a connected car communication module. UEs do not have to be of the same type. Typically, a UE may be a mobile device, such as a personal media device, or it may be fixedly mounted, such as when the UE is a smart metering device that is mounted to read and provide information about water flow or electricity usage to a backend server. In some embodiments, depending on which specific technology is employed, different terms from UE may be used, and in most general terms, a device configured to perform as described herein may be a node of a wireless communication network. An external network 140 , such as the Internet, may be accessed via the core NW 130 .

[0024] exist Figure 1 , a group 160 of UEs 112, 114 forms a group of anchor UEs. These UEs are close to each other, that is, for example, they are within the detection range of the target UE 116, and are able to communicate with the target UE 116 via direct UE-to-UE communication without using a base station (such as base station 120) or a relay device. Such communication may be referred to as sidelink SL communication. However, in some embodiments, sidelink relays may be employed in sidelink communications, wherein a sidelink signal is transmitted by a node such as a UE, received and retransmitted by a sidelink relay, and received by a second node such as a second UE, so that the signal does not pass through the base station. For example, the sidelink communication resources used for communicating in the sidelink via the sidelink relay may be different from the uplink communication resources. The detection range refers to the distance within which the UE can detect other UEs and at least partially determine the direction and distance to these other UEs. Typically, not all UEs 112, 114, 116 need to have the same serving base station 120, although in Figure 1 This is the case for clarity of illustration.

[0025] The anchor UEs 112, 114 forming the anchor UE group 160 may each have a known location, or they may have precise positioning capabilities. In some cases, the anchor UE is an ordinary UE that is assigned to participate in a synchronization process or a positioning process including a synchronization process as the role of an anchor UE. For example, the precise positioning capability may include multi-constellation satellite positioning or an interface to an airspace control system. The anchor UE is capable of sending and receiving electromagnetic pulses that can be used to estimate the distance from the UE to another UE. These pulses may be included in the side link SL communication between the UEs involved. Side link refers to device-to-device (such as UE-to-UE) communication that does not pass through a base station device, in which one device sends electromagnetic energy that is received by a receiver included in a receiving device. In other words, the communication is direct without passing through any other nodes, such as a base station or a relay.

[0026] The anchor UE may be configured to provide positioning measurements, such as reference signal time difference RSTD, reference signal received power RSRP, and / or receive-transmit Rx-Tx time difference. For example, for the OTDOA positioning process, the anchor UE is configured to send a side link positioning reference signal PRS for detection by the UE to be positioned. The UE to be positioned in the positioning process is called the target UE. The anchor UE may be configured by a core network node (such as a location management function LMF), where this configuration may take the form of auxiliary information provided from the core network node to each anchor UE. If the process is a positioning process, the auxiliary information is positioning auxiliary information. The auxiliary information defines when each anchor UE sends its reference signal in the side link, and optionally also defines which transmission resources the anchor UE is to use for the transmission of the reference signal. Examples of transmission resources are frequency bands and spreading codes. Auxiliary information may also be provided to the target UE to enable it to detect the SL reference signal sent by the anchor UE. In some cases, a single anchor UE is used, for example where the serving base station of the target UE also participates in the positioning process, effectively performing the role of the anchor UE by sending reference signals in the downlink.

[0027] OTDOA positioning can be performed such that the anchor UEs transmit their reference signals in the sidelink, the target UE receives each of them, and a timestamp of the moment each reference signal is received is recorded in the circuitry of the target UE. These timestamps can then be reported from the target UE to the cellular system, such as to a core network node, such as to the LMF, which can use them to determine the difference in signal propagation time between the target UE and each anchor UE to estimate their relative positions. Given the absolute position of the anchor UE, an absolute position estimate of the target UE can also be determined. OTDOA is an attractive method of low complexity, known from base station-based positioning, which can be advantageously operated on both the uplink and downlink.

[0028] The challenge in sidelink-based OTDOA positioning lies in the synchronization of anchor UEs. High-precision OTDOA requires precise timing synchronization between participating anchor UEs, which makes it challenging to directly apply the OTDOA approach to wireless sidelink scenarios. More specifically, in base station-based OTDOA scenarios, fiber links can be used to achieve synchronization by using, for example, WhiteRabbit synchronization technology, while in sidelink scenarios, synchronization is typically performed only with an accuracy of one cyclic prefix CP order of magnitude relative to the serving base station. The error in the cyclic prefix order of magnitude is multiple orders of magnitude larger than the typical 0.5-2 meter positioning target accuracy.

[0029] It has been found that synchronization between anchor UEs can be significantly enhanced by supplementing a synchronization mechanism (e.g., a synchronization process forming part of an OTDOA positioning process) with a signal sent from a target UE. In detail, the auxiliary information provided from the cellular system defines the transmission time and, optionally, the transmission resources of the signal from the target UE in addition to defining the transmission time of the reference signal from the anchor UE. This enables the detection of the signal from the target UE in the anchor UE, wherein each anchor UE records a timestamp of the moment when the signal from the target UE is received in the circuit system of the anchor UE. These timestamps are reported from the anchor UE to the cellular system, for example to the core network, for example to the LMF. Therefore, more information can be used to determine the synchronization between anchor UEs, significantly improving the synchronization accuracy, which in turn significantly improves the accuracy of processes that rely on synchronization between anchor UEs (such as positioning processes, such as OTDOA positioning processes).

[0030] The signal sent from the target UE may include an automatic gain control (AGC) symbol. The AGC symbol is used for power level control in the side link. In detail, in order to successfully decode the received signal, the receiver must receive the signal at a sufficiently strong power level, which is higher than the minimum power threshold, but within the saturation limit of its power amplifier, because too strong signals will be clipped. Therefore, in order to adapt the receiver circuit system to signals of different strengths, because the receiver cannot know in advance how strong the incoming signal is, AGC is used. More specifically, the first symbol (AGC symbol) in the transmitted sequence has a known structure and power, and the receiver can be configured to use it to calibrate its circuit system in order to correctly receive subsequent symbols. The AGC symbol itself does not carry actual data. The AGC symbol is useful because the participating UEs, anchor points, and targets do not necessarily know how far apart they are from each other before the positioning process ends. The signal from the target UE can be sent in the uplink or side link. As long as the anchor UE is able to receive the uplink transmission, the uplink can be used for the signal from the target UE. Therefore, the AGC symbol can also be provided in the uplink signal, although it is usually not done because the uplink uses a separate power control mechanism. In some embodiments, AGC is implemented through a previous transmission in the sidelink resource pool, for example as a sidelink control information SCI grant containing an ACG component or an SCI grant for a UL SRS signal in the SL resource pool.

[0031] Since the purpose of the signal from the target UE is to enhance synchronization, it is advantageous to transmit it as a transient signal, which corresponds to using a wide bandwidth to send it. For example, the signal can occupy the entire preconfigured bandwidth used for synchronization and / or direct UE-to-UE signaling in the OTDOA positioning process. Therefore, using a wider bandwidth provides the effect of enhancing synchronization / positioning accuracy. In some embodiments, the signal from the target UE is both a wideband signal and includes AGC symbols.

[0032] The signal from the target UE may be sent before the reference signal from the anchor UE, or after the reference signal. It may also be sent within the reference signal. For example, when sent in the side link, the signal may take the form of a positioning reference signal, or when sent in the uplink, the signal may take the form of an uplink sounding reference signal SRS. The timestamp from the anchor UE indicating the moment of reception of the signal from the target UE at the anchor UE, together with the timestamp indicating the moment of reception of the reference signal from the anchor UE at the target UE, enables determination of the timing offset of each anchor UE relative to the target UE's clock. The timestamp may also be used to correct the anchor UE timing offset relative to the target UE to achieve inter-anchor OTDOA synchronization for precise OTDOA positioning.

[0033] The correction based on the timestamp indicating the reception time of the signal from the target UE can be performed directly in the anchor UE clock, such as in the case of a single target UE to be located, or indirectly as part of the OTDOA post-processing, such as when there are several target UEs to be located by the same anchor UE group 160. The periodic repetition of the synchronization scheme allows synchronization and associated positioning tracking even under mobility conditions. The synchronization scheme is inherently distributed and does not require centralized processing and / or centralized parameter control.

[0034] In addition to the case of only one target UE, there may also be multiple target UEs forming a group of target UEs. Each target UE in the group of target UEs is configured to send the above-mentioned signal by auxiliary information from the cellular system. The auxiliary information defines the time when the transmission should be performed for each target UE to prevent the target UEs from sending their signals at the same time when these signals use the same resources. The signal from the target UE can identify the target UE that sent the signal, especially in the case where there is more than one target UE in the group of target UEs.

[0035] Whether in the case of single or multiple target UEs, a core network node (such as an LMF) first establishes a sidelink OTDOA positioning session via the serving base station 120, where as part of the establishment, an anchor UE is selected for a given target UE, and all PRS and / or SL PRS resources are allocated and activated. All participating UEs (including the anchor UE) have basic synchronization with the network, for example by maintaining the UL timing advance value of the serving base station. However, in the sidelink scenario, in the traditional scenario, they do not have OTDOA level mutual synchronization. This is due to the non-negligible delay in the propagation of the reference signal, and the impact is that the mutual synchronization that the UEs have is not sufficient for accurate OTDOA positioning with a resolution of 1-2 meters.

[0036] As part of the initiation of the positioning session, the core network node (such as LMF) distributes positioning assistance information to the anchor UE and the target UE. The assistance information describes the specific parameters SL PRS resource configuration to all UEs, such as the transmission time of the signal. In the case where the base station participates in the process as an anchor, its DL PRS parameters are also defined by the core network node (such as LMF). In the case where the signal from (multiple) target UEs is an uplink signal, the assistance information also defines the UL SRS signal (or another UL signal) of the target UE, the transmission of which will be used to achieve high-precision OTDOA synchronization of the anchor UE. In the case where the target UE uses a sidelink to send its signal as part of the positioning process, the assistance information can also be used to define the sidelink-based signal from the target UE.

[0037] Once the positioning session is configured and activated, the anchor point participates in sending its SL PRS signal configured by the assistance information. In the case where the base station 120 is one of the anchor points, it also sends its PRS as defined in the assistance information, for example, from the core network. Typically, these transmissions can be repeated to achieve OTDOA-based position tracking. A core network node (such as an LMF) can be configured to ensure that the target UE sends a UL SRS signal or a sidelink positioning signal in response to a batch of OTDOA SL PRS signals (e.g., the first one) or before this signal by appropriately compiling the assistance information.

[0038] Figure 2 1 shows signal timing in accordance with at least some embodiments of the present invention. On the vertical axis are arranged anchor UE 112 and target UE 116. Time progresses from top towards bottom.

[0039] In the synchronization process shown, the auxiliary information defines that the anchor UE 112 will send its reference signal using the side link at time T. Figure 2 The auxiliary information also defines that the target UE 116 will send its signal at time TT. Figure 2 , represents "UL RS" because in this example, this is an uplink signal, not a sidelink signal. E represents the synchronization difference between the anchor UE 112 and the target UE 116. The reception timestamp of the reference signal is "T+pE", where p is the signal propagation time between the anchor UE and the target UE, and the reception timestamp of the signal from the target UE 116 at the anchor UE 112 is "TT+E+p".

[0040] Each anchor UE reports the local reception timestamp of the signal from the target UE to, e.g., the LMF. The target UE itself reports the local reception timestamp of the anchor UE SL reference signal to, e.g., the LMF. Given the knowledge of the transmit timing of the reference signal and the target UE signal, the node to which the timestamps are reported (e.g., the LMF) can then calculate the timing error "E" between the target UE and each individual anchor UE. These also enable the determination of timing correction factors, i.e., synchronization, between the anchors via the target UE clock reference.

[0041] More specifically, the target UE reports (in addition to the standard OTDOA measurements) the local reception time "T+pE" of each anchor UE SL reference signal, where T represents the local transmission time of the SL reference signal from the anchor UE, and p is the propagation delay, as described above. Similarly, the anchor UE reports the local reception time TT+E+p of a signal from the target UE that was sent by the target UE at local time TT+E, where TT represents the transmission time according to the clock of the anchor UE 112.

[0042] Given an anchor UE input TT+E+p and T, and a target UE input TT+E and T+p, the node to which the timestamp is reported (e.g., LMF) can first calculate the propagation time p for the associated anchor as p=[(TT+E+p)-(T)-((TT+E)-(T+p)] / 2

[0043] The propagation time p is then used in the node (e.g. LMF) to which the timestamp is reported, or directly in the anchor UE as a timing offset correction term. In the former case, the node (e.g. LMF) calculates the correction difference between the anchor UEs, which is added to the OTDOA report by the target UE. This method may be useful when the same set of anchor UEs is used simultaneously by multiple target UEs and physical correction of their clocks by using multiple timing advances is not possible. However, if only one target UE is active, the node (e.g. LMF) can also instruct each anchor UE to set its clock so that when the reference signal is received, the clock indicates the time T+p. This is equivalent to the correction of the error E when the time T+pE is set equal to the time T+p.

[0044] It is irrelevant whether the signal from the target UE is sent before or after the reference signal from the anchor UE. In some embodiments, the signal from the target UE is sent before the reference signal transmission, or between the reference signal transmissions. All this is about is accurately reporting the transmission and reception times of these signals, the order in which the various signals are transmitted is irrelevant.

[0045] Figure 3An example device capable of supporting at least some embodiments of the present invention is shown. Illustrated is a device 300, which may include, for example, a mobile communication device (such as a UE), or a core network node (such as an LMF) in an applicable portion. Included in the device 300 is a processor 310, which may include, for example, a single-core or multi-core processor, wherein a single-core processor includes one processing core, and a multi-core processor includes more than one processing core. The processor 310 may generally include a control device. The processor 310 may include more than one processor. When the processor 310 includes more than one processor, the device 300 may be a distributed device in which the processing of tasks occurs in more than one physical unit. The processor 310 may be a control device. The processing core may include, for example, a Cortex-A8 processing core manufactured by ARM Holdings, or a Zen processing core designed by Advanced MicroDevices Corporation. The processor 310 may include at least one QualcommSnapdragon and / or Intel Atom processor. The processor 310 may include at least one application-specific integrated circuit ASIC. The processor 310 may include at least one field programmable gate array FPGA. Processor 310 may be a means for performing method steps (eg, acting, participating, reporting, providing, receiving, and / or transmitting) in device 300. Processor 310 may be configured, at least in part, by computer instructions to perform actions.

[0046] The processor may include or be configured as a circuit system or multiple circuit systems that are configured to perform the stages of the method according to the embodiments described herein. As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) a hardware circuit implementation only (such as an implementation in analog and / or digital circuits only) and (b) a combination of hardware circuits and software, such as (as applicable): (i) a combination of (multiple) analog and / or digital hardware circuits with software / firmware and (ii) any portion of (multiple) hardware processors with software (including (multiple) digital signal processors), software and (multiple) memories, which work together to enable the device (such as a mobile phone or server) to perform various functions) and (c) (multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or parts of (multiple) microprocessors, which require software (e.g., firmware) to operate, but the software may not be present when the software is not required to operate.

[0047] The definition of circuitry applies to all uses of the term in this application, including any claims. As yet another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example (and if applicable to a particular claim element), a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0048] Device 300 may include memory 320. Memory 320 may include random access memory and / or permanent memory. Memory 320 may include at least one RAM chip. Memory 320 may include, for example, solid-state, magnetic, optical and / or holographic memory. Memory 320 may be at least partially accessible by processor 310. Memory 320 may be at least partially included in processor 310. Memory 320 may be a component for storing information. Memory 320 may include computer instructions that processor 310 is configured to execute. When computer instructions configured to cause processor 310 to perform certain actions are stored in memory 320, and device 300 is generally configured to run under the direction of processor 310 using computer instructions from memory 320, processor 310 and / or at least one of its processing cores may be considered to be configured to perform the certain actions. Memory 320 may be at least partially included in processor 310. Memory 320 may be at least partially external to device 300, but accessible by device 300. Memory 320 may be non-transitory. The term "non-transitory" as used herein is a limitation of the medium itself (ie, tangible, not a signal), not a limitation on data storage persistence (eg, RAM vs. ROM).

[0049] The device 300 may include a transmitter 330. The device 300 may include a receiver 340. The transmitter 330 and the receiver 340 may be configured to transmit and receive information, respectively, according to at least one cellular or non-cellular standard. The transmitter 330 may include more than one transmitter. The receiver 340 may include more than one receiver. The transmitter 330 and / or the receiver 340 may be configured to operate according to the following standards, such as the Global System for Mobile Communications GSM, Wideband Code Division Multiple Access WCDMA, 5G, Long Term Evolution LTE, IS-95, Wireless Local Area Network WLAN, Ethernet and / or Worldwide Interoperability for Microwave Access WiMAX standards.

[0050] The device 300 may include a near field communication NFC transceiver 350. The NFC transceiver 350 may support at least one NFC technology, such as NFC, Bluetooth, Wibree, or similar technology.

[0051] The device 300 may include a user interface UI 360. The UI 360 may include at least one of a display, a keyboard, a touch screen, a vibrator arranged to signal a user by vibrating the device 300, a speaker, and a microphone. The user may be able to operate the device 300 via the UI 360, such as accepting an incoming phone call, making a phone call or video call, browsing the Internet, managing digital files stored in the memory 320 or on a cloud accessible via the transmitter 330 and the receiver 340, or via the NFC transceiver 350, and / or playing games.

[0052] The device 300 may include or be arranged to receive a user identity module 370. The user identity module 370 may include, for example, a subscriber identification module SIM card that may be installed in the device 300. The user identity module 370 may include information identifying a subscription of a user of the device 300. The user identity module 370 may include cryptographic information that may be used to verify the identity of the user of the device 300 and / or to facilitate encryption of communicated information and billing of the user of the device 300 for communications achieved via the device 300.

[0053] The processor 310 may be equipped with a transmitter arranged to output information from the processor 310 to other devices included in the device 300 via electrical leads inside the device 300. Such a transmitter may include a serial bus transmitter, which is arranged to output information to the memory 320 for storage therein, for example, via at least one electrical lead. As an alternative to the serial bus, the transmitter may include a parallel bus transmitter. Likewise, the processor 310 may include a receiver, which is arranged to receive information in the processor 310 from other devices included in the device 300 via electrical leads inside the device 300. Such a receiver may include a serial bus receiver, which is arranged to receive information from the receiver 340, for example, via at least one electrical lead, for processing in the processor 310. As an alternative to the serial bus, the receiver may include a parallel bus receiver.

[0054] The device 300 may include Figure 3 Other devices not shown in the figure. For example, where the device 300 comprises a smart phone, it may include at least one digital camera. Some devices 300 may include a rear camera and a front camera, wherein the rear camera may be intended for digital photography and the front camera is used for video telephony. The device 300 may include a fingerprint sensor arranged to at least partially authenticate a user of the device 300. In some embodiments, the device 300 lacks at least one of the above devices. For example, some devices 300 may lack an NFC transceiver 350 and / or a user identity module 370.

[0055] The processor 310, the memory 320, the transmitter 330, the receiver 340, the NFC transceiver 350, the UI 360 and / or the user identity module 370 may be interconnected in a variety of different ways via electrical leads inside the device 300. For example, each of the above devices may be connected to a main bus inside the device 300, respectively, to allow the devices to exchange information. However, as will be appreciated by those skilled in the art, this is only an example, and various ways of interconnecting at least two of the aforementioned devices may be selected depending on the embodiment without departing from the scope of the present invention.

[0056] Figure 4 Signaling according to at least some embodiments of the present invention is shown. On the vertical axis, the LMF, the serving base station 120, the anchor UEs 112 and 114 are arranged from the left, and finally the target UE 116 is arranged on the right. Time advances from the top toward the bottom. In the example shown, the serving base station 120 acts as one of the anchors. In some other embodiments, only the UE is used as an anchor.

[0057] In stage 410, an OTDOA positioning process is established based on the existing coarse anchor synchronization. In stage 420, assistance information (in this case positioning assistance information) is disseminated by the LMF to the UEs and base stations 120 participating in the positioning process. As described above, the positioning assistance information defines when positioning reference signals PRS are to be sent by the base station 120 and the anchor UEs 112, 114, and when the target UE 116 should send its signals as part of the positioning process. The assistance information also facilitates the reception of these signals. The positioning assistance information can also define the transmission resources for these reference signals from the point anchor and the signals from the target UE. In the process shown, the base station 120 participates as an anchor point and the signals from the target UE 116 are uplink signals, but as described above, the signals from the target UE can also be sidelink signals, especially if the serving base station does not participate in the positioning process as an anchor point.

[0058] In stage 430, base station 120 transmits in the downlink to provide a PRS signal to target UE 116. In stages 440 and 450, anchor UEs 112 and 114 respectively transmit sidelink PRS signals to target UE 116. Target UE 116 records a timestamp indicating the moment of receipt of the signals of stages 430, 440, and 450 at target UE 116. The signals of stages 430, 440, and 450 are transmitted at the times defined in the positioning assistance information propagated in stage 420.

[0059] In phase 460, the target UE 116 sends its signal, in this case an uplink signal, as instructed in the positioning assistance information. Its reception moment is recorded as a timestamp in each anchor UE 112 and 114 and in the base station 120. In phase 470, the target UE 116 reports the reception timestamps of the signals of phases 430, 440 and 450 to the LMF. In phases 480 and 490, the anchor UEs 114 and 112 report to the LMF the reception timestamps of their signals from the target UE 116, respectively (phase 460). In addition, the base station 120 reports to the LMF when it receives the signal of phase 460.

[0060] In stage 4100, the LMF determines the anchor UE timing offset based on the timestamps reported to it by the base station in stages 470, 480 and 490, and in stage 4110, performs timing offset correction based on the determination reached in stage 4100. High precision OTDOA positioning may then be performed after stage 4110.

[0061] Figure 5 is a flow chart of a method according to at least some embodiments of the present invention. The stages of the method shown may be performed, for example, in an anchor UE, or in a control device configured to control its functions when installed therein.

[0062] Stage 510 includes acting as a node of a wireless communication system, such as a user equipment UE. The wireless communication system may be a cellular communication system. Stage 520 includes participating in a synchronization process with at least one target node in the wireless communication system, wherein the synchronization process includes sending a reference signal at a time specified in the auxiliary information received from the wireless communication system via node-to-node signaling. The node-to-node signaling may be direct node-to-node signaling, such as direct UE-to-UE signaling. Finally, stage 530 includes reporting, as part of the synchronization process, to the wireless communication system a reception time of a signal from each of the at least one target node.

[0063] It should be understood that the disclosed embodiments of the invention are not limited to the specific structures, processing steps or materials disclosed herein, but extend to their equivalents, as will be recognized by those of ordinary skill in the relevant art. It should also be understood that the terminology employed herein is only used for the purpose of describing specific embodiments and is not intended to be limiting.

[0064] References throughout this specification to an embodiment or an embodiment mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the invention. Thus, the phrases "in one embodiment" or "in an embodiment" that appear in various places throughout this specification do not necessarily all refer to the same embodiment. Where reference values ​​are made using terms such as, for example, about or substantially, the exact values ​​are also disclosed.

[0065] As used herein, for convenience, multiple items, structural elements, constituent elements and / or materials may be presented in a common list. However, these lists should be interpreted as each member of the list being individually identified as a separate and unique member. Therefore, a single member of such a list should not be interpreted as being actually equivalent to any other member of the same list based solely on their presentation in a common group without an indication to the contrary. In addition, various embodiments and examples of the present invention may be mentioned herein together with alternatives of its various components. It should be understood that such embodiments, examples and alternatives should not be interpreted as actually equivalent to each other, but are considered to be separate and autonomous representations of the present invention.

[0066] In addition, in one or more embodiments, the described features, structures or characteristics may be combined in any suitable manner. In the foregoing description, many specific details, such as examples of length, width, shape, etc., are provided to provide a thorough understanding of embodiments of the present invention. However, those skilled in the relevant art will recognize that the present invention may be practiced without one or more specific details or using other methods, components, materials, etc. In other examples, well-known structures, materials or operations will not be shown or described in detail to avoid covering up relevant aspects of the present invention.

[0067] Although the foregoing examples illustrate the principles of the present invention in one or more specific applications, it is apparent to those skilled in the art that many modifications may be made in form, use, and implementation details without practicing the present invention and without departing from the principles and concepts of the present invention. Therefore, it is not intended to limit the present invention except as limited by the claims set forth below.

[0068] The verbs "comprise" and "include" are used in this document as open limitations that neither exclude nor require the presence of unrecited features. Unless explicitly stated otherwise, the features recited in the dependent claims are mutually freely combinable. Furthermore, it should be understood that the use of "a" or "an" throughout this document, i.e. the singular, does not exclude a plurality. Industrial Applicability

[0069] At least some embodiments of the present invention find industrial application in synchronization management in wireless networks. List of abbreviations 5G Fifth Generation AGC Automatic Gain Control DL Downlink PRS Positioning Reference Signal LMF Location Management Function LTE Long Term Evolution NW Network OTDOA Observed Time Difference of Arrival RS reference signal SL Side Link SRS Sounding Reference Signal UE User Equipment UL Uplink WCDMA Wideband Code Division Multiple Access Reference numerals list 112,114 Anchor UE 116 Target UE 120 Base Station 121 Wireless Link 130 Core Network 140 External Network 300-370 Figure 3 The structure of the device 410-4110 Figure 4 Stages of the process Technical terms:

[0070] Clause 1. An apparatus comprising at least one processing core and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus to at least: - Act as a node in a wireless communication system; - participating in a synchronization procedure with at least one target node in the wireless communication system, wherein the apparatus is configured to, as part of the synchronization procedure, transmit a reference signal via node-to-node signaling at a time instant specified in assistance information received from the wireless communication system, and - as part of the synchronization process, reporting to the wireless communication system a time of reception of a signal from each of the at least one target node.

[0071] Clause 2. An apparatus according to clause 1, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the at least one target node is located in the OTDOA positioning process, wherein the reference signal is a positioning reference signal, and wherein the assistance information is positioning assistance information.

[0072] Clause 3. An apparatus as described in clause 1 or clause 2, wherein each of the signals from the at least one target node comprises an automatic gain control symbol sent at a preconfigured power.

[0073] Clause 4. An apparatus as described in clause 2 or clause 3 as dependent on clause 2, wherein each of the signals from the at least one target node occupies the entire preconfigured bandwidth used for node-to-node signaling in the OTDOA positioning process.

[0074] Clause 5. An apparatus as described in any of clauses 1 to 4, wherein each of the signals from the at least one target node is an uplink signal or a sidelink signal.

[0075] Clause 6. An apparatus as described in any of clauses 1 to 5, wherein the apparatus is configured to receive the signal from the at least one target node before sending the reference signal.

[0076] Clause 7. An apparatus as described in any of clauses 1 to 5, wherein the apparatus is configured to receive the signal from the at least one target node after sending the reference signal.

[0077] Clause 8. An apparatus comprising at least one processing core and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus to at least: - Act as a node in a wireless communication system; - participating as a target node in a synchronization procedure with at least one further node of the wireless communication system, wherein the apparatus is configured to inform the further nodes of the wireless communication system of a reception time instant of a reference signal from each of the at least one further node via node-to-node signaling, and - As part of the synchronization process, sending a signal in an uplink or a sidelink at a time instant specified in assistance information received from the wireless communication system.

[0078] Clause 9. An apparatus according to clause 8, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the target node is positioned in the OTDOA positioning process, wherein each reference signal is a positioning reference signal, and wherein the assistance information is positioning assistance information.

[0079] Clause 10. An apparatus according to clause 8 or 9, wherein the apparatus is configured to transmit the signal in the uplink or the sidelink such that the signal comprises automatic gain control symbols transmitted at a preconfigured power.

[0080] Clause 11. An apparatus according to any of clauses 8 to 10, wherein the apparatus is configured to send the signal in the uplink or the sidelink such that the signal occupies the entire preconfigured bandwidth used for node-to-node signaling in the synchronization process.

[0081] Clause 12. An apparatus comprising at least one processing core and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus to at least: - Act as a node in a wireless communication system; - participate in a synchronization procedure, wherein the apparatus is configured to provide first assistance information to at least one further node and to provide second assistance information to a target node, the first assistance information instructing when to send a reference signal via node-to-node signaling, the second assistance information instructing when to send a signal in an uplink or a sidelink, and - as part of the synchronization process, receiving an indication from the at least one further node and receiving at least one indication from the target node, the indication regarding when each of the at least one further node receives the signal from the target node, the at least one indication regarding when the target node receives each of the reference signals.

[0082] Clause 13. An apparatus according to clause 12, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the target node is located in the OTDOA positioning process, wherein each reference signal is a positioning reference signal, and wherein the first assistance information and the second assistance information are positioning assistance information.

[0083] Clause 14. A method comprising: - Act as a node in a wireless communication system; - participating in a synchronization procedure with at least one target node of the cellular communication system, wherein the synchronization procedure comprises sending a reference signal at a time instant specified in assistance information received from the wireless communication system via node-to-node signaling, and - as part of the synchronization process, reporting to the wireless communication system a time of reception of a signal from each of the at least one target node.

[0084] Clause 15. A method according to clause 14, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the at least one target node is positioned in the OTDOA positioning process, wherein the reference signal is a positioning reference signal, and wherein the assistance information is positioning assistance information.

[0085] Clause 16. The method of clause 14 or 15, wherein each of the signals from the at least one target node comprises an automatic gain control symbol transmitted at a preconfigured power.

[0086] Clause 17. A method as described in clause 15 or clause 16 when dependent on clause 15, wherein each of the signals from the at least one target node occupies the entire preconfigured bandwidth used for node-to-node signaling in the OTDOA positioning process.

[0087] Clause 18. A method as described in any of clauses 14 to 17, wherein each of the signals from the at least one target node is an uplink signal or a sidelink signal.

[0088] Clause 19. The method of any of clauses 14 to 18, wherein the receiving of the signal from the at least one target node occurs before sending the reference signal.

[0089] Clause 20. The method of any of clauses 14 to 19, wherein the reception of the signal from the signal from the at least one target node occurs after sending the reference signal.

[0090] Clause 21. A method comprising: - Act as a node in a wireless communication system; - participating as a target node in a synchronization procedure with at least one further node of the wireless communication system, wherein the further nodes of the wireless communication system are informed of the reception time instant of a reference signal from each of the at least one further node via node-to-node signaling, and - As part of the synchronization process, sending a signal in an uplink or a sidelink at a time instant specified in assistance information received from the wireless communication system.

[0091] Clause 22. A method according to clause 21, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the target node is positioned in the OTDOA positioning process, wherein each reference signal is a positioning reference signal, and wherein the assistance information is positioning assistance information.

[0092] Clause 23. A method according to clause 21 or 22, wherein the sending of the signal in the uplink or the sidelink occurs such that the signal comprises automatic gain control symbols sent at a preconfigured power.

[0093] Clause 24. A method according to any one of clauses 21 to 23, wherein the sending of the signal in the uplink or the sidelink occurs such that the signal occupies the entire preconfigured bandwidth used for node-to-node signaling in the synchronization process.

[0094] Clause 25. A method comprising: - Act as a node in a wireless communication system; - participating in a synchronization procedure, wherein first assistance information is provided to at least one further node, said first assistance information instructing when to send a reference signal via node-to-node signaling, and wherein second assistance information is provided to a target node, said second assistance information instructing when to send a signal in an uplink or a sidelink, and - as part of the synchronization process, receiving an indication from the at least one further node and receiving at least one indication from the target node, the indication regarding when each of the at least one further node receives the signal from the target node, the at least one indication regarding when the target node receives each of the reference signals.

[0095] Clause 26. A method according to clause 25, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the target node is located in the OTDOA positioning process, wherein each reference signal is a positioning reference signal, and wherein the first assistance information and the second assistance information are positioning assistance information.

[0096] Clause 27. An apparatus comprising: -Components for acting as nodes of a wireless communication system; - means for participating in a synchronization procedure with at least one target node of the wireless communication system, wherein the synchronization procedure comprises sending a reference signal at a time instant specified in assistance information received from the wireless communication system via node-to-node signaling, and - means for reporting, as part of said synchronization process, to said wireless communication system a time of reception of a signal from each of said at least one target node.

[0097] Clause 28. An apparatus comprising: -Components for acting as nodes of a wireless communication system; - means for participating as a target node in a synchronization procedure with at least one further node of the cellular communication system, wherein the further nodes of the wireless communication system are informed of the time instant of reception of a reference signal from each of the at least one further node via node-to-node signaling, and - means for sending a signal in uplink or sidelink at a time instant specified in assistance information received from said wireless communication system as part of said synchronization procedure.

[0098] Clause 29. An apparatus comprising: -Components for acting as nodes of a wireless communication system; - means for participating in a synchronization procedure, wherein first assistance information is provided to at least one further node, said first assistance information instructing when to send a reference signal via node-to-node signaling, and wherein second assistance information is provided to a target node, said second assistance information instructing when to send a signal in an uplink or a sidelink, and - means for receiving, as part of the synchronization process, indications from the at least one further node as to when the signal from the target node was received by each of the at least one further node and at least one indication from the target node as to when each of the reference signals was received by the target node.

[0099] Clause 30. A non-transitory computer-readable medium having stored thereon a set of computer-readable instructions that, when executed by at least one processor, cause an apparatus to at least: - Act as a node in a wireless communication system; - participating in a synchronization procedure with at least one target node in the wireless communication system, wherein the apparatus is configured to, as part of the synchronization procedure, transmit a reference signal via node-to-node signaling at a time instant specified in assistance information received from the wireless communication system, and - as part of the synchronization process, reporting to the wireless communication system a time of reception of a signal from each of the at least one target node.

[0100] 31. A non-transitory computer readable medium having stored thereon a set of computer readable instructions which, when executed by at least one processor, cause an apparatus to at least: - Act as a node in a cellular communication system; - participating as a target node in a synchronization procedure with at least one further node of the cellular communication system, wherein the apparatus is configured to inform the further nodes of the wireless communication system of a time instant of reception of a reference signal from each of the at least one further node via node-to-node signaling, and - As part of the synchronization process, sending a signal in an uplink or sidelink at a time instant specified in assistance information received from the wireless communication system.

[0101] Clause 32. A non-transitory computer-readable medium having stored thereon a set of computer-readable instructions that, when executed by at least one processor, cause an apparatus to at least: - Act as a node in a wireless communication system; - participate in a synchronization procedure, wherein the apparatus is configured to provide first assistance information to at least one further node and to provide second assistance information to a target node, the first assistance information instructing when to send a reference signal via node-to-node signaling, the second assistance information instructing when to send a signal in an uplink or a sidelink, and - as part of the synchronization process, receiving an indication from the at least one further node and receiving at least one indication from the target node, the indication regarding when each of the at least one further node receives the signal from the target node, the at least one indication regarding when the target node receives each of the reference signals.

Claims

1. An apparatus comprising at least one processing core and at least one memory storing instructions, wherein the instructions, when executed by the at least one processing core, cause the apparatus to at least: - Act as a node in a wireless communication system; - participating in a synchronization procedure with at least one target node in the wireless communication system, wherein the apparatus is configured to, as part of the synchronization procedure, transmit a reference signal via node-to-node signaling at a time instant specified in assistance information received from the wireless communication system, and - as part of the synchronization process, reporting to the wireless communication system a time of reception of a signal from each of the at least one target node.

2. The apparatus according to claim 1, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the at least one target node is located in the OTDOA positioning process, wherein the reference signal is a positioning reference signal, and wherein the assistance information is positioning assistance information.

3. An apparatus according to claim 1 or claim 2, wherein each of the signals from the at least one target node comprises an automatic gain control symbol transmitted at a preconfigured power.

4. An apparatus according to claim 2 or claim 3 as appended to claim 2, wherein each of the signals from the at least one target node occupies the entire preconfigured bandwidth used for node-to-node signaling in the OTDOA positioning process.

5. The apparatus according to any one of claims 1 to 4, wherein each of the signals from the at least one target node is an uplink signal or a sidelink signal.

6. The apparatus according to any one of claims 1 to 5, wherein the apparatus is configured to receive the signal from the at least one target node before sending the reference signal.

7. The apparatus according to any one of claims 1 to 5, wherein the apparatus is configured to receive the signal from the at least one target node after sending the reference signal.

8. An apparatus comprising at least one processing core and at least one memory storing instructions, wherein the instructions, when executed by the at least one processing core, cause the apparatus to at least: - Act as a node in a wireless communication system; - participating as a target node in a synchronization procedure with at least one further node of the wireless communication system, wherein the apparatus is configured to inform the further nodes of the wireless communication system of a reception time instant of a reference signal from each of the at least one further node via node-to-node signaling, and - As part of the synchronization process, sending a signal in an uplink or a sidelink at a time instant specified in assistance information received from the wireless communication system.

9. The apparatus of claim 8, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the target node is positioned in the OTDOA positioning process, wherein each reference signal is a positioning reference signal, and wherein the assistance information is positioning assistance information.

10. The apparatus according to claim 8 or 9, wherein the apparatus is configured to transmit the signal in the uplink or the sidelink such that the signal comprises automatic gain control symbols transmitted at a preconfigured power.

11. The apparatus according to any one of claims 8 to 10, wherein the apparatus is configured to send the signal in the uplink or the sidelink such that the signal occupies the entire preconfigured bandwidth used for node-to-node signaling in the synchronization process.

12. An apparatus comprising at least one processing core and at least one memory storing instructions, wherein the instructions, when executed by the at least one processing core, cause the apparatus to at least: - Act as a node in a wireless communication system; - participate in a synchronization procedure, wherein the apparatus is configured to provide first assistance information to at least one further node and to provide second assistance information to a target node, the first assistance information instructing when to send a reference signal via node-to-node signaling, the second assistance information instructing when to send a signal in an uplink or a sidelink, and - as part of the synchronization process, receiving an indication from the at least one further node and receiving at least one indication from the target node, the indication regarding when each of the at least one further node receives the signal from the target node, the at least one indication regarding when the target node receives each of the reference signals.

13. The apparatus of claim 12, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the target node is positioned in the OTDOA positioning process, wherein each reference signal is a positioning reference signal, and wherein the first assistance information and the second assistance information are positioning assistance information.

14. A method comprising: - Act as a node in a wireless communication system; - participating in a synchronization procedure with at least one target node of the cellular communication system, wherein the synchronization procedure comprises sending a reference signal at a time instant specified in assistance information received from the wireless communication system via node-to-node signaling, and - as part of the synchronization process, reporting to the wireless communication system a time of reception of a signal from each of the at least one target node.

15. The method of claim 14, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the at least one target node is positioned in the OTDOA positioning process, wherein the reference signal is a positioning reference signal, and wherein the assistance information is positioning assistance information.

16. The method of claim 14 or 15, wherein each of the signals from the at least one target node comprises an automatic gain control symbol transmitted at a preconfigured power.

17. A method according to claim 15 or claim 16 when dependent on claim 15, wherein each of the signals from the at least one target node occupies the entire preconfigured bandwidth used for node-to-node signaling in the OTDOA positioning process.

18. The method according to any one of claims 14 to 17, wherein each of the signals from the at least one target node is an uplink signal or a sidelink signal.

19. The method of any one of claims 14 to 18, wherein the receiving of the signal from the at least one target node occurs before sending the reference signal.

20. The method of any one of claims 14 to 19, wherein the reception of the signal from the signal from the at least one target node occurs after the transmission of the reference signal.

21. A method comprising: - Act as a node in a wireless communication system; - participating as a target node in a synchronization procedure with at least one further node of the wireless communication system, wherein the further nodes of the wireless communication system are informed of the reception time instant of a reference signal from each of the at least one further node via node-to-node signaling, and - As part of the synchronization process, sending a signal in an uplink or a sidelink at a time instant specified in assistance information received from the wireless communication system.

22. The method of claim 21, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the target node is positioned in the OTDOA positioning process, wherein each reference signal is a positioning reference signal, and wherein the assistance information is positioning assistance information.

23. The method according to claim 21 or 22, wherein the sending of the signal in the uplink or the sidelink occurs such that the signal comprises automatic gain control symbols sent at a preconfigured power.

24. The method according to any one of claims 21 to 23, wherein the sending of the signal in the uplink or the sidelink occurs such that the signal occupies the entire preconfigured bandwidth used for node-to-node signaling in the synchronization process.

25. A method comprising: - Act as a node in a wireless communication system; - participating in a synchronization procedure, wherein first assistance information is provided to at least one further node, said first assistance information instructing when to send a reference signal via node-to-node signaling, and wherein second assistance information is provided to a target node, said second assistance information instructing when to send a signal in an uplink or a sidelink, and - as part of the synchronization process, receiving an indication from the at least one further node and receiving at least one indication from the target node, the indication regarding when each of the at least one further node receives the signal from the target node, the at least one indication regarding when the target node receives each of the reference signals.

26. The method of claim 25, wherein the synchronization process is included in an observed time difference of arrival (OTDOA) positioning process, wherein the target node is positioned in the OTDOA positioning process, wherein each reference signal is a positioning reference signal, and wherein the first assistance information and the second assistance information are positioning assistance information.

27. An apparatus comprising: -Components for acting as nodes of a wireless communication system; - means for participating in a synchronization procedure with at least one target node of the wireless communication system, wherein the synchronization procedure comprises sending a reference signal at a time instant specified in assistance information received from the wireless communication system via node-to-node signaling, and - means for reporting, as part of said synchronization process, to said wireless communication system a time of reception of a signal from each of said at least one target node.

28. An apparatus comprising: -Components for acting as nodes of a wireless communication system; - means for participating as a target node in a synchronization procedure with at least one further node of the cellular communication system, wherein the further nodes of the wireless communication system are informed of the time instant of reception of a reference signal from each of the at least one further node via node-to-node signaling, and - means for sending a signal in uplink or sidelink at a time instant specified in assistance information received from said wireless communication system as part of said synchronization procedure.

29. An apparatus comprising: -Components for acting as nodes of a wireless communication system; - means for participating in a synchronization procedure, wherein first assistance information is provided to at least one further node, said first assistance information instructing when to send a reference signal via node-to-node signaling, and wherein second assistance information is provided to a target node, said second assistance information instructing when to send a signal in an uplink or a sidelink, and - means for receiving, as part of the synchronization process, indications from the at least one further node as to when the signal from the target node was received by each of the at least one further node and at least one indication from the target node as to when each of the reference signals was received by the target node.

30. A non-transitory computer readable medium having stored thereon a set of computer readable instructions which, when executed by at least one processor, cause an apparatus to at least: - Act as a node in a wireless communication system; - participating in a synchronization procedure with at least one target node in the wireless communication system, wherein the apparatus is configured to, as part of the synchronization procedure, transmit a reference signal via node-to-node signaling at a time instant specified in assistance information received from the wireless communication system, and - as part of the synchronization process, reporting to the wireless communication system a time of reception of a signal from each of the at least one target node.

31. A non-transitory computer readable medium having stored thereon a set of computer readable instructions which, when executed by at least one processor, cause an apparatus to at least: - Act as a node in a cellular communication system; - participating as a target node in a synchronization procedure with at least one further node of the cellular communication system, wherein the apparatus is configured to inform the further nodes of the wireless communication system of a time instant of reception of a reference signal from each of the at least one further node via node-to-node signaling, and - As part of the synchronization process, sending a signal in an uplink or a sidelink at a time instant specified in assistance information received from the wireless communication system.

32. A non-transitory computer readable medium having stored thereon a set of computer readable instructions which, when executed by at least one processor, cause an apparatus to at least: - Act as a node in a wireless communication system; - participate in a synchronization procedure, wherein the apparatus is configured to provide first assistance information to at least one further node and to provide second assistance information to a target node, the first assistance information instructing when to send a reference signal via node-to-node signaling, the second assistance information instructing when to send a signal in an uplink or a sidelink, and - as part of the synchronization process, receiving an indication from the at least one further node and receiving at least one indication from the target node, the indication regarding when each of the at least one further node receives the signal from the target node, the at least one indication regarding when the target node receives each of the reference signals.

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