Method and apparatus for avoiding transmission timing errors - Patents.com

Abstract

A method and apparatus for avoiding a transmission timing error are disclosed. The method for RUE includes receiving a first error measurement request message at a first base station, receiving a second error measurement request message at a second base station, receiving a first reference signal at the first base station based on the first error measurement request message, determining a first transmission timing of the first base station based on the first reference signal, receiving a second reference signal at the second base station based on the second error measurement request message, and determining a second transmission timing of the second base station based on the second reference signal.

Description

[Technical Field]

[0001] The present disclosure relates to absolute time synchronization (ATS) techniques, and more particularly to techniques for avoiding transmission timing errors that affect timing accuracy. [Background technology]

[0002] Wireless-based factory automation systems have many advantages over wired-based factory automation systems, such as enhanced flexibility, increased safety, better scalability, and ease of shifting between facilities.

[0003] To support the sophisticated motion-controlled conveyor belt manufacturing functions of wired-based factory automation systems with wireless-based factory automation systems, absolute time synchronization (ATS) technology may be necessary so that wireless devices (e.g., mobile robots, sensors, activators) can perform isochronous / sequential cooperative operations at a set time. ATS may refer to synchronization that provides the same absolute time or clock to wireless devices regardless of their locations.

[0004] To achieve ATS in a wireless-based factory automation system, timing errors can be a problem. Timing errors can include transmit timing errors and / or receive timing errors. Receive timing errors can be overcome to some extent. However, because transmit timing errors can vary due to inherent hardware damage in each communication node, it may be impossible to eliminate the transmit timing errors. A method for reducing the impact of transmit timing errors occurring between communication nodes (e.g., user equipment (UE)) is needed. Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve the above problems, an object of the present disclosure is to provide a method and apparatus for achieving absolute time synchronization (ATS) in a wireless-based factory automation system. [Means for solving the problem]

[0006] To achieve the above object, an RUE method according to an embodiment of the present disclosure includes the steps of receiving a first error measurement request message at a first base station, receiving a second error measurement request message at a second base station, receiving a first reference signal at the first base station based on the first error measurement request message, determining a first transmission timing of the first base station based on the first reference signal, receiving a second reference signal at the second base station based on the second error measurement request message, determining a second transmission timing of the second base station based on the second reference signal, calculating a difference between the first transmission timing and the second transmission timing, transmitting a first error measurement response message including information of the difference to the first base station, and transmitting a second error measurement response message including information of the difference to the second base station.

[0007] The first error measurement request message may include information on transmission resources for the first reference signal, and the second error measurement request message may include information on transmission resources for the second reference signal, and each of the first reference signal and the second reference signal may be one of DMRS, CSI-RS, PRS, or PT-RS.

[0008] Each of the first error measurement request message and the second error measurement request message may include a type field and a counterpart BS field, where the type field may indicate that the type of the error measurement message is an error measurement request, the counterpart BS field included in the first error measurement request message may be set to the ID of the second base station, which is the counterpart BS for which error measurement is desired, and the counterpart BS field included in the second error measurement request message may be set to the ID of the first base station, which is the counterpart BS for which error measurement is desired.

[0009] Each of the first error measurement response message and the second error measurement response message may include a type field, a counterpart BS field, a timing difference field, and a compensation BS field, where the type field may indicate that the type of the error measurement message is an error measurement response, the counterpart BS field included in the first error measurement response message may be set to the ID of the second base station which is the counterpart BS for which error measurement is desired, the counterpart BS field included in the second error measurement response message may be set to the ID of the first base station which is the counterpart BS for which error measurement is desired, the timing difference field may be set to the difference between the first transmission timing and the second transmission timing, and the compensation BS field may indicate the BS that will compensate for the difference between the transmission timings.

[0010] The first transmission timing may be determined by further considering a first propagation delay between the first base station and the RUE, and the second transmission timing may be determined by further considering a second propagation delay between the second base station and the RUE.

[0011] The RUEs may be common RUEs between one or more RUEs registered with the first base station and one or more RUEs registered with the second base station.

[0012] To achieve the above object, a method of a first base station according to an embodiment of the present disclosure includes the steps of transmitting a first error measurement request message to an RUE, transmitting a first reference signal to the RUE based on the first error measurement request message, transmitting an error measurement request message to a second base station, receiving a first error measurement response message at the RUE, the first error measurement response message including information on a difference between a first transmission timing of the first base station and a second transmission timing of the second base station, and performing downlink communication by compensating for the difference.

[0013] The method of the first base station may further include the steps of requesting one or more RUEs to transmit a BS registration list, receiving one or more BS registration lists at the one or more RUEs, and confirming a common RUE registered in common at the first base station and the second base station based on the one or more BS registration lists, and the RUE to which the first error measurement request message is transmitted may be the common RUE.

[0014] The method of the first base station may further include the steps of requesting one or more base stations to transmit an RUE registration list, receiving one or more RUE registration lists at the one or more base stations, and identifying the second base station among the one or more base stations in which the RUE is registered based on the one or more RUE registration lists, wherein the RUE may be a common RUE registered in common to the first base station and the second base station, and the error measurement request message may be transmitted to the second base station having the common RUE.

[0015] The method of the first base station may further include transmitting information of the difference between the first transmission timing of the first base station and the second transmission timing of the second base station to the second base station.

[0016] The first error measurement request message may include a type field and a counterpart BS field, where the type field may indicate that the type of the error measurement message is an error measurement request, and the counterpart BS field included in the first error measurement request message may be set to the ID of the second base station, which is the counterpart BS for which error measurement is desired.

[0017] The error measurement request message may request the second base station to transmit a second error measurement request message or a second reference signal to the RUE.

[0018] The first error measurement response message may include a type field, a counterpart BS field, a timing difference field, and a compensation BS field, where the type field may indicate that the type of the error measurement message is an error measurement response, the counterpart BS field included in the first error measurement response message may be set to the ID of the second base station, which is the counterpart BS for which error measurement is desired, the timing difference field may be set to the difference between the first transmission timing and the second transmission timing, and the compensation BS field may indicate the BS that compensates for the difference between the transmission timings.

[0019] The first transmission timing may be determined by further considering a first propagation delay between the first base station and the RUE, and the second transmission timing may be determined by further considering a second propagation delay between the second base station and the RUE.

[0020] To achieve the above object, a method of a first base station according to an embodiment of the present disclosure includes the steps of transmitting an error measurement request message to a second base station requesting transmission of a second reference signal, transmitting an error measurement request message to a RUE, transmitting a first reference signal to the RUE based on the error measurement request message, receiving an error measurement response message at the RUE including information on a difference between a first transmission timing of the first base station and a second transmission timing of the second base station, and performing downlink communication by compensating for the difference.

[0021] The error measurement request message may request simultaneous or sequential transmission of the first reference signal and the second reference signal, the error measurement request message may include transmission resource information for the second reference signal, and the second reference signal of the second base station may be transmitted to the RUE from a transmission resource indicated by the transmission resource information.

[0022] The error measurement request message may include transmission resource information of the first reference signal and transmission resource information of the second reference signal.

[0023] The first transmission timing may be determined by further considering a first propagation delay between the first base station and the RUE, and the second transmission timing may be determined by further considering a second propagation delay between the second base station and the RUE.

[0024] The method of the first base station may further include the steps of requesting one or more RUEs to transmit a BS registration list, receiving one or more BS registration lists at the one or more RUEs, and confirming a common RUE registered in common to the first base station and the second base station based on the one or more BS registration lists, and the RUE to which the error measurement request message is transmitted may be the common RUE.

[0025] The method of the first base station may further include the steps of requesting one or more base stations to transmit an RUE registration list, receiving one or more RUE registration lists at the one or more base stations, and identifying the second base station among the one or more base stations in which the RUE is registered based on the one or more RUE registration lists, wherein the RUE may be a common RUE registered in common to the first base station and the second base station, and the error measurement request message may be transmitted to the second base station having the common RUE. [Effects of the Invention]

[0026] According to the present disclosure, the transmission timing errors of different base stations can be adjusted to be the same, and the transmission timing errors of different controllers can be adjusted to be the same. In other words, absolute time synchronization (ATS) can be achieved between communication nodes (e.g., base stations, controllers, and transmission and reception points (TRPs)). Therefore, wireless devices can perform isochronous / sequential cooperative operations (e.g., ultra-precise application operations), and the performance of factory automation systems can be improved. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a conceptual diagram illustrating a first embodiment of a transmission timing error.

[0028] [Figure 2] FIG. 1 is a block diagram illustrating a first embodiment of a communication node.

[0029] [Figure 3] FIG. 1 is a conceptual diagram illustrating a first embodiment of a method for avoiding transmission timing errors.

[0030] [Figure 4] 4 is a flow chart illustrating a second embodiment of a method for avoiding transmission timing errors.

[0031] [Figure 5] FIG. 10 is a block diagram illustrating a first embodiment of Format 1 of an error measurement request message.

[0032] [Figure 6] FIG. 10 is a block diagram illustrating a first embodiment of Format 1 of an error measurement response message.

[0033] [Figure 7] FIG. 10 is a block diagram illustrating a first embodiment of Format 2 of an error measurement request message.

[0034] [Figure 8] FIG. 10 is a block diagram illustrating a first embodiment of Format 2 of an error measurement response message.

[0035] [Figure 9] 10 is a flow chart illustrating a third embodiment of a method for avoiding transmission timing errors.

[0036] [Figure 10] FIG. 10 is a block diagram illustrating a first embodiment of Format 3 of an error measurement request message.

[0037] [Figure 11] 10 is a flowchart illustrating a fourth embodiment of a method for avoiding transmission timing errors.

[0038] [Figure 12] 10 is a flowchart illustrating a fifth embodiment of a method for avoiding transmission timing errors.

[0039] [Figure 13] 1 is a flowchart illustrating a first embodiment of a method for exchanging a BS registration list.

[0040] [Figure 14] 1 is a flowchart illustrating a first embodiment of a method for exchanging an RUE registration list.

[0041] [Figure 15] FIG. 1 is a conceptual diagram illustrating a first example of a cooperation scenario between BSs.

[0042] [Figure 16a-16b] 1 is a flow chart illustrating a first embodiment of a method for measuring and communicating a difference in transmit timing error.

[0043] [Figure 17] FIG. 1 is a conceptual diagram illustrating a second example of a cooperation scenario between BSs.

[0044] [Figure 18a-18b] 10 is a flow chart illustrating a second embodiment of a method for measuring and communicating a difference in transmit timing error.

[0045] [Figure 19] 10 is a flowchart illustrating a sixth embodiment of a method for avoiding transmission timing errors.

[0046] [Figure 20] FIG. 1 is a conceptual diagram illustrating a first example of a cooperation scenario of a BS and a TRP.

[0047] [Figure 21a-21b] 10 is a flow chart illustrating a third embodiment of a method for measuring and communicating a difference in transmit timing error.

[0048] [Figure 22a-22b] 10 is a flow chart illustrating a fourth embodiment of a method for measuring and communicating a difference in transmit timing error.

[0049] [Figure 23] 10 is a flowchart illustrating a seventh embodiment of a method for avoiding transmission timing errors.

[0050] [Figure 24] FIG. 1 is a conceptual diagram illustrating a first embodiment of a collaboration scenario for TRP.

[0051] [Figure 25a-25b] 10 is a flowchart illustrating a fifth embodiment of a method for measuring and communicating a difference in transmit timing error. DETAILED DESCRIPTION OF THE INVENTION

[0052] While the present disclosure can be modified in various ways and can have various embodiments, specific embodiments will be illustrated in the drawings and described in detail, but it should be understood that this is not intended to limit the disclosure to the specific embodiments, and that all modifications, equivalents, and alternatives within the spirit and technical scope of the present disclosure are included.

[0053] Terms such as "first," "second," etc. may be used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one component from another. For example, a first component may be designated as a second component, and similarly, a second component may be designated as a first component, without departing from the scope of the present disclosure. The term "and / or" includes a combination of multiple associated listed items or any of multiple associated listed items.

[0054] In this disclosure, "at least one of A and B" may mean "at least one of A or B" or "at least one of a combination of one or more of A and B." Also, in this disclosure, "one or more of A and B" may mean "one or more of A or B" or "one or more of a combination of one or more of A and B."

[0055] In this disclosure, (re)transmission may mean "transmission," "retransmission," or "transmission and retransmission," (re)configuration may mean "configuration," "reconfiguration," or "configuration and reconfiguration," (re)connection may mean "connection," "reconnection," or "connection and reconnection," and (re)connection may mean "connection," "reconnection," or "connection and reconnection."

[0056] In this disclosure, time may mean a time point, and a time point may mean time. A transmission time may mean a transmission start time or a transmission end time, and a reception time may mean a reception start time or a reception end time.

[0057] When a component is said to be "coupled" or "connected" to another component, it should be understood that it may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is said to be "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0058] The terms used in this disclosure are merely used to describe specific embodiments and are not intended to limit the present disclosure. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this disclosure, terms such as "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0059] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms as defined in commonly used dictionaries should be interpreted to have a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as having an idealized or overly formal meaning unless expressly defined in this disclosure.

[0060] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. In describing the present disclosure, the same reference numerals will be used to designate the same components in the drawings to facilitate overall understanding, and redundant descriptions of the same components will be omitted.

[0061] A communication network to which an embodiment of the present disclosure is applied will now be described. The communication network to which an embodiment of the present disclosure is applied is not limited to the content described below, and the embodiment of the present disclosure may be applied to various communication networks. Here, the term "communication network" may be used interchangeably with the term "communication system." The term "communication network" may refer to a wireless communication network, and the term "communication system" may refer to a wireless communication system.

[0062] In the present disclosure, "configuring an operation (e.g., a transmission operation)" may mean that "configuration information (e.g., information elements, parameters) for the corresponding operation" and / or "information instructing the performance of the corresponding operation" is signaled. "Configuring an information element (e.g., a parameter)" may mean that the corresponding information element is signaled. In the present disclosure, the signaling may be at least one of system information (SI) signaling (e.g., transmission of a system information block (SIB) and / or a master information block (MIB)), RRC signaling (e.g., transmission of RRC parameters and / or higher layer parameters), MAC control element (CE) signaling, or PHY signaling (e.g., transmission of downlink control information (DCI), uplink control information (UCI), and / or sidelink control information (SCI)).

[0063] FIG. 1 is a conceptual diagram illustrating a first embodiment of a transmission timing error.

[0064] Referring to FIG. 1, timing errors can be a problem in achieving absolute time synchronization (ATS) in a wireless-based factory automation system (hereinafter referred to as a "wireless factory automation system"). A wireless factory automation system can be interpreted as a wireless communication system or a wireless communication network. Timing errors can include transmit timing errors and / or receive timing errors. A transmit timing error can refer to the difference between a transmission time point set for a transmission signal and the actual transmission time point of the transmission signal. The cause of the change in the actual transmission time point can be considered to be uncontrollable jitter, such as hardware impairment of the transmitter. A receive timing error can refer to the difference between the accurate reception time point and the reception time point obtained by reception timing estimation.

[0065] The transmission timing error may vary due to inherent hardware damage of each communication node (e.g., base station (BS), transmission and reception point (TRP), node, controller, wireless device, user equipment (UE)). It may be impossible to eliminate the transmission timing error with a single one-to-one link. There may be a UE1 managed and / or controlled by BS1, and there may be a UE2 managed and / or controlled by BS2. Each of UE1 and UE2 may be a wireless device. BS1 and BS2 may be connected by a wire. Synchronization between BS1 and BS2 may be ATS.

[0066] When BS1 transmits a signal to UE1, the propagation delay (τ BS1、UE1 ), there is a transmission timing error (e BS1、UE1、TX ) and the reception timing error (e BS1、UE1、RX) may exist. The propagation delay may be a radio propagation delay. The reception timing error may be overcome to some extent through a sophisticated design of the physical layer numerology. For example, a reception timing error of a length of several samples may occur through the design of a very short time resolution (e.g., a sample length in the time domain), and the impact of the reception timing error may be negligible. Since the transmission timing error is caused by inherent hardware damage of the communication node, BS1 and / or UE1 do not know the transmission timing error. Furthermore, BS1 and / or UE1 cannot control the transmission timing error.

[0067] When BS2 transmits a signal to UE2, the radio propagation delay (τ BS2、UE2 ), there is a transmission timing error (e BS2、UE2、TX ) and the reception timing error (e BS2、UE2、RX ) may exist. The receive timing error can be overcome to some extent through the sophisticated design of the physical layer numerology. The transmit timing error is caused by the inherent hardware damage of the communication node, so BS2 and / or UE2 do not know the transmit timing error. In addition, BS2 and / or UE2 cannot control the transmit timing error.

[0068] UEs managed and / or controlled by a BS may be affected by a common transmission timing error relative to the BS. The time of the UEs controlled by the BS may not coincide with the absolute time of the BS. The common transmission timing error may not affect the "operation performed by the UE isochronously / sequentially in absolute time(s)." Different transmission timing errors may occur between UEs belonging to different BSs. The transmission timing error may prevent isochronous / sequential operations from being performed in absolute time(s). In this disclosure, isochronous / sequential operation may refer to "isochronous operation," "sequential operation," or "isochronous and sequential operation." For ATS in a wireless factory automation system, a method for reducing the impact of transmission timing errors occurring between UEs belonging to different BSs, a method for reducing the impact of transmission timing errors occurring between UEs belonging to multiple TRPs belonging to one BS, etc., is needed.

[0069] FIG. 2 is a block diagram illustrating a first embodiment of a communication node.

[0070] 2, a communication node 200 may include at least one of a processor 210, a memory 220, or a transceiver 230 that is connected to a network and performs communication. The communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, etc. Each component included in the communication node 200 is connected to each other by a bus 270 and can perform communication with each other.

[0071] However, each component included in the communication node 200 may be connected through an individual interface or individual bus centered on the processor 210, rather than through the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transceiver 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface.

[0072] The processor 210 can execute program commands stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present disclosure are performed. The memory 220 and the storage device 260 may each be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may be composed of at least one of a read-only memory (ROM) and a random access memory (RAM).

[0073] Next, a method of operating a communication node will be described. Even when a method (e.g., signal transmission or reception) performed by a first communication node among communication nodes is described, a second communication node corresponding to the first communication node can perform a method (e.g., signal reception or transmission) corresponding to the method performed by the first communication node. In other words, when the operation of a base station is described, a terminal (e.g., UE) corresponding to the base station can perform an operation corresponding to the operation of the base station. Conversely, when the operation of a terminal is described, a base station corresponding to the terminal can perform an operation corresponding to the operation of the terminal.

[0074] In the present disclosure, an apparatus that manages and / or controls a wireless device (e.g., UE) may be a BS, a cell, a primary cell, a secondary cell, and / or a transmission and reception point (TRP).

[0075] To achieve ATS between UEs belonging to different BSs (or different TRPs) in a wireless factory automation system, a reference UE (RUE) can be introduced. The RUE can reduce the impact of transmission timing errors. The RUE can be expressed by various names (e.g., first UE, first terminal, reference terminal, reference unit, etc.).

[0076] FIG. 3 is a conceptual diagram illustrating a first embodiment of a method for avoiding transmission timing errors.

[0077] Referring to FIG. 3, BS1 and BS2 may be different BSs. BS1 may manage and / or control one or more UEs (e.g., UE1). BS2 may manage and / or control one or more UEs (e.g., UE2). When BS1 transmits a signal to UE1, a radio propagation delay (τ BS1、UE1 ), there is a transmission timing error (e BS1、UE1、TX ) and the reception timing error (e BS1、UE1、RX ) may exist. The receive timing error can be overcome to some extent through the sophisticated design of the physical layer numerology. The transmit timing error is caused by the inherent hardware damage of the communication node, so BS1 and / or UE1 do not know the transmit timing error. In addition, BS1 and / or UE1 cannot control the transmit timing error.

[0078] When BS2 transmits a signal to UE2, the radio propagation delay (τ BS2、UE2 ), there is a transmission timing error (e BS2、UE2、TX ) and the reception timing error (e BS2、UE2、RX ) may exist. The receive timing error can be overcome to some extent through the sophisticated design of the physical layer numerology. The transmit timing error is caused by the inherent hardware damage of the communication node, so BS2 and / or UE2 do not know the transmit timing error. In addition, BS2 and / or UE2 cannot control the transmit timing error.

[0079] When an RUE is located between BS1 and BS2, the transmission timing error generated by each BS cannot be determined, but the difference in transmission timing error between BS1 and BS2 can be determined using the RUE. BS1 and BS2 know the location of the RUE. The location of the RUE can be a location with good wireless fading channel quality for BS1 and BS2, a location with no change in the wireless fading channel quality, or a location with minimal change in the wireless fading channel quality. BS1 and / or the RUE can determine the propagation delay (τ BS1、RUE ) is known, and BS2 and / or RUE can determine the propagation delay (τ BS2、RUE ) can be understood.

[0080] The receive timing error (e BS1、RUE、RX , e BS2、RUE、RX ) may be nearly identical when the wireless link quality of each of BS1 and BS2 is equal to or exceeds a predefined standard. In this disclosure, BS1 and BS2 may be assumed to be connected by wire, and the synchronization between BS1 and BS2 may be assumed to be very precise absolute synchronization.

[0081] BS1 and BS2 can transmit signals for absolute synchronization simultaneously or at predefined times (e.g., sample time points). The signals for absolute synchronization can be referred to as absolute synchronization signals. The absolute synchronization signals can be transmitted periodically or aperiodically. RUE is the arrival time (T BS1、RUE ) and the arrival time (T BS2、RUE ) can be measured. In other words, RUE is the BS1、RUE -T BS2、RUE It is possible to measure T BS1、RUE T may mean the time when the absolute synchronization signal transmitted by BS1 arrives at RUE. BS2、RUE may mean the time when the absolute synchronization signal transmitted by the BS arrives at the RUE.

[0082]

number

[0083] The difference in propagation delay (τ BS1、RUE -τ BS2、RUE ) as A, the RUE can measure or estimate the difference between the transmission timing errors (B) based on the difference in arrival times and A. B can be defined as Equation 2 below.

[0084]

number

[0085] The RUE can transmit (e.g., signal) information related to B or B to BS1 and / or BS2. BS1 and / or BS2 can receive information related to B or B from the RUE. BS1 and / or BS2 can transmit information related to B or B to a control station (e.g., controller) that manages and / or controls the BSs. The control station can receive information related to B or B from BS1 and / or BS2. The control station can adjust the transmission time (e.g., sample time point) of BS1 and / or BS2 using the information related to B or B. Alternatively, the RUE can transmit (e.g., signal) information regarding the transmission time (e.g., sample time point) of BS1 and / or BS2 to BS1 and / or BS2 without a control station.

[0086] JPEG2025527888000004.jpg39162

[0087] BS2 can adjust the transmission time by adding the difference (B) in the transmission timing error to the existing transmission time. Through this operation, UE1 and UE2 can achieve ATS without being affected by the transmission timing error. Therefore, sophisticated cooperative operations can be performed.

[0088] When the controller or RUE transmits information requesting adjustment of the transmission time for each BS, the information may include a difference (B) in the transmission timing errors and / or a method for adjusting the transmission timing errors to be equal. The method for adjusting the transmission timing errors to be equal may be "adjusting the transmission time of BS1 by B / 2 earlier" and / or "adjusting the transmission time of BS2 by B / 2 later."

[0089] FIG. 4 is a flow chart illustrating a second embodiment of a method for avoiding transmission timing errors.

[0090] 4, RUE may be registered with BS1 and / or BS2, and RUE may know in advance propagation delay information for BS1 and / or propagation delay information for BS2. The positions of RUE, BS1, and BS2 may be fixed, and the distance between RUE and BS1 and the distance between RUE and BS2 may be determined based on the positions of RUE, BS1, and BS2, and the propagation delay may be determined based on the determined distance and the propagation speed in free space (e.g., the speed of light (c)).

[0091] BS1 may transmit an error measurement request message to the RUE (S401). After transmitting the error measurement request message, BS1 may transmit a reference signal for error measurement to the RUE (S403). BS2 may transmit an error measurement request message to the RUE (S402). After transmitting the error measurement request message, BS2 may transmit a reference signal for error measurement to the RUE (S404). The error measurement request message may include information about the reference signal (e.g., resource information, transmission resource information). The reference signal may be a demodulation reference signal (DMRS), a channel state information-reference signal (CSI-RS), a positioning reference signal (PRS), and / or a phase tracking-reference signal (PT-RS). The BS(s) may transmit the reference signal(s) simultaneously to the RUE. Alternatively, the BS(s) may transmit the reference signal(s) sequentially to the RUE.

[0092] The RUE may receive an error measurement request message from BS1 and / or BS2. If the error measurement request message is received, the RUE may determine that error measurement is requested. The RUE may receive reference signals from BS1 and BS2 based on the error measurement request message (e.g., resources indicated by the error measurement request message) and estimate timing based on the received reference signals. After estimating the timing for BS1 and BS2, the RUE may calculate the difference between the transmit timing error of BS1 and the transmit timing error of BS2 based on Equation 1 and Equation 2 (S405). The RUE may transmit an error measurement response message including the difference (e.g., delta) of the transmit timing error to BS1 (S406). The RUE may transmit an error measurement response message including the difference of the transmit timing error to BS2 (S407). The difference of the transmit timing error may indicate the difference between the transmit timing of BS1 and the transmit timing of BS2.

[0093] BS1 and BS2 can receive an error measurement response message from the RUE and can improve the accuracy of absolute synchronization based on the difference in transmission timing error included in the error measurement response message. For example, when UEs belonging to the BSs perform cooperative operation, each BS can transmit a signal earlier or later by the difference in transmission timing error to improve the accuracy of absolute synchronization. Each of the error measurement request message and the error measurement response message can be transmitted based on at least one of SI signaling, RRC signaling, MAC CE signaling, or PHY signaling.

[0094] FIG. 5 is a block diagram illustrating a first embodiment of Format 1 of the error measurement request message.

[0095] Referring to FIG. 5, the error measurement request message may include an error measurement message type field and an error measurement destination BS ID (identifier) ​​field. The error measurement message type field may be referred to as the "type field," and the error measurement destination BS ID field may be referred to as the "destination BS field." The type field may indicate the type of the message. A type field set to a first value (e.g., 0) may indicate an error measurement request message. In this case, the type of the error measurement message may be an error measurement request. A type field set to a second value (e.g., 1) may indicate an error measurement response message. In this case, the type of the error measurement message may be an error measurement response. A type field set to a third value (e.g., 2) may indicate an announcement message (e.g., an error measurement announcement message). In this case, the type of the error measurement message may be an error measurement announcement.

[0096] The remote BS field may be the ID of the remote BS for which error measurement is desired. The remote BS field may be set with information that can identify the BS (e.g., PCI (physical cell ID) or MAC address). For example, in the embodiment of FIG. 4, the remote BS field included in the error measurement request message transmitted by BS1 may be set with the ID of BS2, and the remote BS field included in the error measurement request message transmitted by BS2 may be set with the ID of BS1.

[0097] FIG. 6 is a block diagram illustrating a first embodiment of Format 1 of the Error Measurement Response Message.

[0098] 6, the error measurement response message may include an error measurement message type field, an error measurement partner BS ID field, a transmission timing error difference field, and an error compensation BS selection field. The error measurement message type field may be referred to as a "type field," the error measurement partner BS ID field may be referred to as a "partner BS field," the transmission timing error difference field may be referred to as a "timing difference field," and the error compensation BS selection field may be referred to as a "compensation BS field."

[0099] The type field may indicate that the message type is an error measurement response message. The destination BS field of the error measurement response message may be set to the same as the destination BS field of the error measurement request message. The timing difference field may indicate the transmission timing error difference with the destination BS. For example, the timing difference field may indicate the difference between the transmission timing errors measured by the RUE based on the reference signal received from the BS. The timing difference field may include information indicating whether the transmission timing of the BS is early or late, and the information may be a sign (e.g., +, -).

[0100] The Compensating BS field can indicate a BS that compensates for the difference in transmission timing error. When a difference in transmission timing error is received, the BS indicated by the Compensating BS field, either BS1 or BS2, can compensate for the difference in transmission timing error. If the BS that compensates for the difference in transmission timing error is pre-negotiated, the BS(s) can ignore the Compensating BS field. A Compensating BS field set to a first value (e.g., 0) can indicate that the other BS compensates for the difference in transmission timing error. A Compensating BS field set to a second value (e.g., 1) can indicate that the BS that transmitted the error measurement request message compensates for the difference in transmission timing error. A Compensating BS field set to a third value (e.g., 2) can indicate that the pre-negotiated BS compensates for the difference in transmission timing error. Alternatively, a Compensating BS field set to a third value (e.g., 2) can mean don't care.

[0101] FIG. 7 is a block diagram illustrating a first embodiment of Format 2 of the error measurement request message.

[0102] Referring to FIG. 7, the error measurement request message may include an error measurement message type field, multiple error measurement destination BS ID fields, and a message response request time field. The error measurement message type field may be referred to as the "type field," the error measurement destination BS ID field may be referred to as the "destination BS field," and the message response request time field may be referred to as the "request time field." Alternatively, the request time field may not be included in the error measurement request message. When a BS requests the difference in transmission timing errors for multiple BSs, the error measurement request message shown in FIG. 7 may be used. When there are multiple destination BSs for error measurement, the same number of destination BS fields as the number of destination BSs may be required. The request time field may indicate the time (e.g., end time) when the receiving operation of the error measurement response message is performed.

[0103] FIG. 8 is a block diagram illustrating a first embodiment of Format 2 of the Error Measurement Response Message.

[0104] 8, when the error measurement request message shown in FIG. 7 is received, the RUE may transmit the error measurement response message shown in FIG. 8. If the error measurement request message indicates multiple partner BSs for error measurement, the error measurement response message may include the difference in transmission timing error of each of the multiple partner BSs. If it is difficult to transmit the difference in transmission timing error of each of all partner BSs within the time indicated by the request time field, the error measurement response message may include the difference in transmission timing error of each of the partner BSs to which transmission is possible. Alternatively, if it is difficult to transmit the difference in transmission timing error of each of all partner BSs within the time indicated by the request time field, additional time for transmitting the difference in transmission timing error may be requested.

[0105] When the error measurement request message shown in Figure 7 and the error measurement response message shown in Figure 8 are used, the number of message exchanges for error measurement can be reduced. Therefore, radio resources can be used efficiently. When cooperative operation with the BS is required, the error measurement request message shown in Figure 7 and the error measurement response message shown in Figure 8 can be used.

[0106] In the embodiment of FIG. 4, BS1 and BS2 can each transmit an error measurement request message to the RUE without a request from the RUE. For cooperation, BS1 and BS2 can transmit error measurement request messages to the RUE simultaneously or sequentially. If the error measurement request messages are transmitted sequentially, the interval between the transmission of the error measurement request message by BS1 and the transmission of the error measurement request message by BS2 can be short. Only one of the BSs can transmit an error measurement request message. In the embodiment of FIG. 9 below, one of BS1 and BS2 can transmit an error measurement request message.

[0107] FIG. 9 is a flow chart illustrating a third embodiment of a method for avoiding transmission timing errors.

[0108] Referring to FIG. 9, BS1 may transmit an error measurement request message to an RUE (S901). The error measurement request message may include information on a reference signal (e.g., resource information, transmission resource information). After transmitting the error measurement request message, BS1 may transmit a reference signal for error measurement to the RUE (S902). The RUE may receive the error measurement request message from BS1. If the error measurement request message is received, the RUE may determine that error measurement is requested. The RUE may receive a reference signal from BS1 based on the error measurement request message (e.g., resources indicated by the error measurement request message) and estimate timing based on the received reference signal.

[0109] If an error measurement request message is not received from a counterpart BS (e.g., BS2) within a predetermined time from the time of receiving the error measurement request message from BS1, the RUE may request BS2 to transmit an error measurement request message or a reference signal (S903). If the RUE requests transmission of an error measurement request message, BS2 may transmit an error measurement request message to the RUE (S904). The error measurement request message may include information on the reference signal (e.g., resource information, transmission resource information). After transmitting the error measurement request message, BS2 may transmit a reference signal for error measurement to the RUE (S905). If the RUE requests transmission of a reference signal, BS2 may transmit a reference signal for error measurement to the RUE (S905). In other words, if the RUE requests transmission of a reference signal, BS2 may omit transmission of the error measurement request message.

[0110] Alternatively, when an RUE requests transmission of an error measurement request message or reference signal transmission, BS2 can perform "S904+S905" or only S905 as needed. When it is necessary to receive information on the difference in transmission timing error, BS2 can perform "S904+S905". When it is not necessary to receive information on the difference in transmission timing error, BS2 can only perform S905. In other words, when it is not necessary to receive information on the difference in transmission timing error, BS2 does not need to perform S904. The RUE can transmit information on the difference in transmission timing error only to the BS that transmitted the error measurement request message.

[0111] The RUE can receive a reference signal from BS2 and estimate timing based on the received reference signal. After estimating timing for BS1 and BS2, the RUE can calculate the difference between the transmit timing error of BS1 and the transmit timing error of BS2 based on Equations 1 and 2 (S906). The RUE can transmit an error measurement response message including the difference (e.g., delta) of the transmit timing error to BS1 (S907). If an error measurement request message from BS2 is received, the RUE can transmit an error measurement response message including the difference of the transmit timing error to BS2 (S908).

[0112] If the error measurement request message from BS2 is not received (e.g., if only the reference signal from BS2 is received), the RUE may not transmit an error measurement response message including the difference in transmission timing error to BS2. In this case, BS1 may receive the error measurement response message from the RUE, but BS2 may not receive the error measurement response message from the RUE. If the error measurement response message is transmitted only to BS1, the error compensation BS selection field included in the error measurement response message may indicate that BS1 performs compensation for the difference in transmission timing error.

[0113] BS1 and / or BS2 can receive an error measurement response message from the RUE and can improve the accuracy of absolute synchronization based on the difference in transmission timing error included in the error measurement response message. For example, when UEs belonging to the BSs perform cooperative operation, each BS can transmit a signal earlier or later by the difference in transmission timing error to improve the accuracy of absolute synchronization. In the embodiment of Figure 9, Format 3 of the error measurement request message can be used.

[0114] FIG. 10 is a block diagram illustrating a first embodiment of Format 3 of the error measurement request message.

[0115] 10, the error measurement request message may include an error measurement message type field, an error measurement destination BS ID field, an error measurement request to destination BS field, and an error compensation BS request field. The error measurement message type field may be referred to as a "type field," the error measurement destination BS ID field may be referred to as a "destination BS field," the error measurement request to destination BS field may be referred to as a "measurement request field," and the error compensation BS request field may be referred to as a "BS request field."

[0116] A measurement request field set to a first value (e.g., 0) can indicate "not to request the counterpart BS to transmit an error measurement request message or a reference signal." A measurement request field set to a second value (e.g., 1) can indicate "to request the counterpart BS to transmit an error measurement request message." A measurement request field set to a third value (e.g., 2) can indicate "to request the counterpart BS to transmit a reference signal."

[0117] The RUE can receive an error measurement request message from BS1 and can request BS2 to transmit an error measurement request message or a reference signal based on the value of the measurement request field included in the error measurement request message. Alternatively, the RUE can make no request to BS2 based on the value of the measurement request field included in the error measurement request message from BS1. In this case, the RUE can wait for reception of the error measurement request message or a reference signal from BS2 without making a request to BS2.

[0118] The BS Request field can indicate a BS (e.g., a primary BS) that will perform error (e.g., a difference in transmission timing error) compensation. A BS Request field set to a first value (e.g., 0) can indicate that the remote BS (e.g., BS2) will compensate for the difference in transmission timing error. A BS Request field set to a second value (e.g., 1) can indicate that BS1 will compensate for the difference in transmission timing error. The RUE can check the value of the BS Request field in the Error Measurement Request message(s) received from the BS(s) and set the value of the Error Compensation BS Selection field in the Error Measurement Response message based on the checked value.

[0119] In the embodiment of Figure 9, the RUE can request BS2 to transmit an error measurement request message or a reference signal for error measurement. For this operation, the RUE can use radio resources. In the embodiment of Figure 11 below, the "operation of the RUE requesting BS2 to transmit an error measurement request message or a reference signal for error measurement" can be omitted, thereby preventing waste of radio resources.

[0120] FIG. 11 is a flow chart illustrating a fourth embodiment of a method for avoiding transmission timing errors.

[0121] Referring to FIG. 11, BS1 may transmit an error measurement request message to an RUE (S1101). The error measurement request message may include information on a reference signal (e.g., resource information, transmission resource information). After transmitting the error measurement request message, BS1 may transmit a reference signal for error measurement to the RUE (S1102). The RUE may receive the error measurement request message from BS1. If the error measurement request message is received, the RUE may determine that error measurement is requested. The RUE may receive a reference signal from BS1 based on the error measurement request message (e.g., resources indicated by the error measurement request message) and estimate timing based on the received reference signal.

[0122] BS1 and BS2 may be connected by a wire. BS1 may transmit an error measurement request message to BS2 (S1103). The error measurement request message may request that the RUE transmit at least one of an error measurement request message or a reference signal. BS1 may immediately transmit the error measurement request message to BS2, thereby reducing the time required for the RUE to measure the difference in transmission timing error.

[0123] BS2 may receive an error measurement request message from BS1. If BS1 requests transmission of the error measurement request message, BS2 may transmit the error measurement request message to the RUE (S1104). The error measurement request message may include information on the reference signal (e.g., resource information, transmission resource information). After transmitting the error measurement request message, BS2 may transmit a reference signal for error measurement to the RUE (S1105). If BS1 requests transmission of a reference signal, BS2 may transmit a reference signal for error measurement to the RUE (S1105). In other words, if BS1 requests transmission of a reference signal, BS2 may omit transmission of the error measurement request message.

[0124] The format of the error measurement request message transmitted by BS1 may be format 3 shown in Figure 10. The error measurement request field for the peer BS included in the error measurement request message from BS1 may indicate that the RUE should not transmit any request to the peer BS (e.g., BS2). The error compensation BS request field included in the error measurement request message from BS1 may indicate that BS1 should compensate for the difference in transmission timing error.

[0125] The RUE can receive a reference signal from BS2 and estimate timing based on the received reference signal. After estimating timing for BS1 and BS2, the RUE can calculate the difference between the transmit timing error of BS1 and the transmit timing error of BS2 based on Equations 1 and 2 (S1106). The RUE can transmit an error measurement response message including the difference (e.g., delta) of the transmit timing error to BS1 (S1107). If an error measurement request message from BS2 is received, the RUE can transmit an error measurement response message including the difference of the transmit timing error to BS2 (S1109).

[0126] If the error measurement request message from BS2 is not received (e.g., if only the reference signal from BS2 is received), the RUE does not need to transmit an error measurement response message including the difference in transmission timing error to BS2. In this case, BS1 may receive the error measurement response message from the RUE, but BS2 may not receive the error measurement response message from the RUE.

[0127] BS1 may transmit the difference in transmission timing errors to BS2 (S1108). S1108 may be performed if BS2 does not receive an error measurement response message including the difference in transmission timing errors from the RUE. In other words, if the error measurement request message from BS1 requests the transmission of a reference signal in S1103, BS1 may predict that BS2 will not receive an error measurement response message including the difference in transmission timing errors from the RUE. In this case, BS1 may notify BS2 of the difference in transmission timing errors in S1108.

[0128] The accuracy of absolute synchronization between BSs can be improved based on the difference in transmission timing error included in the error measurement response message. For example, when UEs belonging to BSs perform cooperative operation, each BS can transmit a signal earlier or later by the difference in transmission timing error to improve the accuracy of absolute synchronization.

[0129] FIG. 12 is a flow chart illustrating a fifth embodiment of a method for avoiding transmission timing errors.

[0130] Referring to FIG. 12, BS1 may transmit an error measurement request message to BS2 (S1201). The error measurement request message may include information instructing simultaneous or sequential transmission of reference signals. If simultaneous transmission of reference signals is difficult, sequential transmission of reference signals may be performed. BS2 may receive the error measurement request message from BS1 and determine that simultaneous or sequential transmission of reference signals is requested based on the information included in the error measurement request message. In addition, the error measurement request message may include resource information for the reference signals, and the reference signal(s) of BS1 and / or BS2 may be transmitted using the resource indicated by the error measurement request message.

[0131] BS1 can reserve resources (e.g., radio resources) for simultaneous or sequential transmission of reference signals. BS1 can transmit an error measurement request message including resource reservation information for reference signals to the RUE (S1202). The error measurement request message can include resource reservation information (e.g., transmission resource information) for the reference signals of BS1 and / or resource reservation information (e.g., transmission resource information) for the reference signals of BS2. The RUE can receive the error measurement request message from BS1 and can confirm the resource reservation information for reference signals included in the error measurement request message. BS2 can also confirm the resource reservation information for reference signals by acquiring the error measurement request message from BS1.

[0132] BS1 may transmit a reference signal to the RUE using the error measurement request message and / or the resource indicated by the error measurement request message (S1203). BS2 may transmit a reference signal to the RUE from the error measurement request message and / or the resource indicated by the error measurement request message (S1204). The reference signal may be transmitted based on a simultaneous transmission scheme or a sequential transmission scheme.

[0133] The RUE may receive the reference signal of BS1 and the reference signal of BS2 from the resource indicated by the error measurement message. The RUE may estimate timing based on the received reference signals. After estimating the timing for BS1 and BS2, the RUE may calculate the difference between the transmit timing error of BS1 and the transmit timing error of BS2 based on Equations 1 and 2 (S1205). The RUE may transmit an error measurement response message to BS1, including the difference (e.g., delta) of the transmit timing errors (S1206). Since the error measurement request message has been received from BS1, the RUE may transmit the error measurement response message to BS1.

[0134] BS1 can receive an error measurement response message from the RUE and can confirm the difference in transmission timing error included in the error measurement response message. BS1 can notify BS2 of the difference in transmission timing error (S1207). BS2 can receive the difference in transmission timing error from BS1. The accuracy of absolute synchronization between BSs can be improved based on the difference in transmission timing error included in the error measurement response message. For example, when UEs belonging to BSs perform cooperative operation, each BS can transmit a signal earlier or later by the difference in transmission timing error to improve the accuracy of absolute synchronization.

[0135] In the above-described embodiments (e.g., the embodiments of FIGS. 5 to 11), an RUE can measure the difference in transmission timing error with respect to a peer BS at the request of a BS and report the difference in transmission timing error to the BS. When there are many cooperating BSs and many RUEs, a procedure may be necessary for a BS to check which RUEs registered with the BS are connected to a cooperating BS (e.g., a peer BS). A cooperating BS may be a BS that wishes to cooperate.

[0136] Cooperating BSs can exchange registered RUE lists and can select one RUE from among the common RUEs based on the registered RUE list. The registered RUE list can be referred to as an RUE registration list. The RUE registration list can contain information on one or more RUEs registered in a BS (e.g., a cooperative BS). An RUE can transmit the BS registration list to the BS(s) in which it is registered. In the error measurement request message transmission procedure, the BS(s) can select a partner BS by considering the BS registration list. The BS registration list can contain information on one or more BSs in which an RUE is registered.

[0137] FIG. 13 is a flowchart illustrating a first embodiment of a method for exchanging a BS registration list.

[0138] Referring to FIG. 13, a BS can request RUEs registered with it (e.g., RUE1, RUE2, and RUE3) to transmit a BS registration list (S1301). RUEs (e.g., RUE1, RUE2, and RUE3) can receive a request to transmit a BS registration list from the BS. In S1302, RUE1 can transmit a BS registration list including information on the BS(s) in which it is registered to the BS, RUE2 can transmit a BS registration list including information on the BS(s) in which it is registered to the BS, and RUE3 can transmit a BS registration list including information on the BS(s) in which it is registered to the BS. The BS can receive the BS registration list from the RUE. The BS can identify RUEs registered with cooperating BSs (e.g., partner BSs) based on the BS registration list and can transmit an error measurement request message to the identified RUEs. In other words, the first BS can identify common RUEs registered in both the first and second BSs based on the BS registration list.

[0139] FIG. 14 is a flowchart illustrating a first embodiment of a method for exchanging an RUE registration list.

[0140] Referring to FIG. 14, one or more RUEs may be registered with a BS. The BS may have an RUE registration list. The RUE registration list may include information on one or more RUEs registered with the BS. The BS may request neighboring BSs (e.g., BS2, BS3, and BS4) to transmit an RUE registration list (S1401). The neighboring BSs may receive a request to transmit an RUE registration list from BS1. In S1402, BS2 may transmit an RUE registration list including information on RUE(s) registered with it to BS1, BS3 may transmit an RUE registration list including information on RUE(s) registered with it to BS1, and BS4 may transmit an RUE registration list including information on RUE(s) registered with it to BS1.

[0141] BS1 can receive an RUE registration list from neighboring BSs. BS1 can check the RUEs registered with each BS based on the RUE registration list. BS1 can check BSs that have a common RUE based on the RUE registration list. For example, BS1 can determine that a common RUE exists between BS1 and BS2. In this case, BS1 can perform a method to avoid a transmission timing error with BS2. BSs (e.g., BS1, BS2, BS3, and BS4) can be connected via wired connections. Because the RUE registration list exchange procedure is performed via wired connections, no waste of radio resources occurs due to the RUE registration list exchange procedure.

[0142] As another method proposed in this disclosure, the primary BS can request a common RUE among the RUEs registered with neighboring BS(s) to measure the error. The primary BS can manage and / or control the cooperating BS(s) and can initiate the error measurement procedure. The neighboring BS(s) may be cooperating BS(s) with the primary BS. In other words, the neighboring BS(s) may be BS(s) with which the primary BS wishes to cooperate. A common RUE may refer to an RUE registered with a BS.

[0143] FIG. 15 is a conceptual diagram illustrating a first example of a cooperation scenario between BSs.

[0144] Referring to FIG. 15, among the BSs, BS1 may be a primary BS, and BS2, BS3, and BS4 may be cooperating BSs for BS1. BS1, BS2, BS3, and BS4 may be connected to an RUE. In other words, an RUE may be registered with BS1, BS2, BS3, and BS4. An RUE connected (e.g., registered) to BS1, BS2, BS3, and BS4 may be a common RUE. BS1 (e.g., a primary BS) may request the BSs to transmit reference signals. BS1 may request simultaneous or sequential transmission of reference signals. The BSs may transmit reference signals. The RUE may measure the reference signals received by each BS and calculate the difference in transmission timing error between the BSs based on the measurement results. The RUE may notify the BS(s) of the difference in transmission timing error.

[0145] 16a and 16b are a flow chart illustrating a first embodiment of a method for measuring and communicating differences in transmit timing errors.

[0146] 16a and 16b, the embodiments of FIG. 16a and 16b may be applied to the cooperative scenario illustrated in FIG. 15, the embodiment of FIG. 16a may be performed before the embodiment of FIG. 16b, and the embodiment of FIG. 16b may be performed after the completion of the embodiment of FIG. 16a. BS1 may be a primary BS, BS2, BS3, and BS4 may be cooperative BSs for BS1, and the RUE may be a common RUE for BS1, BS2, BS3, and BS4. The embodiments of FIG. 16a and 16b may be divided into a "configuration step for measuring the difference in transmission timing error (e.g., the embodiment of FIG. 16a)" and a "measurement / transmission step for measuring / transmitting the difference in transmission timing error (e.g., the embodiment of FIG. 16b)." In the configuration step for measuring the difference in transmission timing error, BS1 (e.g., the primary BS) may request the cooperative BSs (e.g., BS2, BS3, and BS4) to transmit an RUE registration list (S1601). The cooperating BSs may be neighboring BSs or partner BSs of BS1.

[0147] The cooperating BSs can receive a request to transmit an RUE registration list from BS1. In S1602, BS2 can transmit an RUE registration list containing information on RUE(s) registered with it to BS1, BS3 can transmit an RUE registration list containing information on RUE(s) registered with it to BS1, and BS4 can transmit an RUE registration list containing information on RUE(s) registered with it to BS1. BS1 can receive RUE registration lists from neighboring BSs. BS1 can check RUEs registered in common with the cooperating BSs and BS1 based on the RUE registration list. In other words, BS1 can check common RUEs registered with BS1, BS2, BS3, and BS4. BS1, BS2, BS3, and BS4 can be connected to a common RUE.

[0148] BS1 can negotiate with cooperating BSs about the time when reference signals can be transmitted and can reserve radio resources for transmitting the reference signals based on the negotiation result. BS1 can transmit reference signal information (e.g., resource reservation information, transmission resource information) to each cooperating BS (S1603). The reference signal information can include reference signal resource reservation information for each cooperating BS. The reference signal resource reservation information can indicate the radio resources reserved for transmitting the reference signals and / or the transmission time of the reference signals. The cooperating BSs can receive reference signal information from BS1 and can confirm the radio resources reserved for transmitting the reference signals and / or the transmission time of the reference signals based on the received information.

[0149] BS1 may transmit information about the reference signal (e.g., resource reservation information) to the RUE (e.g., common RUE) (S1604). The information about the reference signal transmitted in S1603 may be the same as the information about the reference signal transmitted in S1604. The RUE may receive the information about the reference signal from BS1 and, based on the received information, may determine the radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal.

[0150] In the transmission timing error difference measurement / transmission step, BS1, BS2, BS3, and BS4 may each transmit a reference signal to the RUE using the reserved radio resources (S1605). The reference signal may be transmitted based on a simultaneous transmission scheme or a sequential transmission scheme. The reference signal may be DMRS, CSI-RS, PRS, and / or PT-RS. The RUE may receive the reference signal using the reserved radio resources and calculate a transmission timing error difference based on the measurement result of the reference signal (S1606). For example, the RUE may calculate a transmission timing error difference between BSs based on Equation 1 and Equation 2. The RUE may calculate the transmission timing error difference between BS1 and BS2, the transmission timing error difference between BS1 and BS3, and the transmission timing error difference between BS1 and BS4.

[0151] The RUE can transmit information about the difference in transmission timing error to BS1 (S1607). BS1 can acquire information about the difference in transmission timing error from the RUE. BS1 can transmit information about the difference in transmission timing error to each cooperating BS (S1608). The accuracy of absolute synchronization between BSs can be improved based on the difference in transmission timing error. When BSs perform cooperative communication, the BSs can perform downlink transmission to the UE after compensating for the difference in transmission timing error. For example, each BS can transmit a signal earlier or later by the difference in transmission timing error to improve the accuracy of absolute synchronization.

[0152] FIG. 17 is a conceptual diagram illustrating a second example of a cooperation scenario between BSs.

[0153] Referring to FIG. 17, among the BSs, BS1 may be a primary BS, and BS2, BS3, BS4, and BS5 may be cooperating BSs for BS1. A common RUE for BS1, BS2, BS3, and BS4 may be RUE1. In other words, RUE1 may be connected to BS1, BS2, BS3, and BS4. A common RUE for BS1 and BS5 may be RUE2. In other words, RUE2 may be connected to BS1 and BS5. BS1 (e.g., a primary BS) may request the BSs connected to RUE1 and / or RUE2 to transmit reference signals. BS1 may request simultaneous or sequential transmission of reference signals. The BSs may transmit reference signals. RUE1 and RUE2 may measure the reference signals received at each BS and calculate the difference in transmission timing error between the BSs based on the measurement results. RUE1 and RUE2 may notify the BS(s) of the difference in transmission timing error.

[0154] 18a and 18b are a flow chart illustrating a second embodiment of a method for measuring and communicating differences in transmit timing errors.

[0155] 18a and 18b, the embodiments of FIG. 18a and 18b may be applied to the cooperative scenario illustrated in FIG. 17, and the embodiment of FIG. 18a may be performed before the embodiment of FIG. 18b, and the embodiment of FIG. 18b may be performed after the completion of the embodiment of FIG. 18a. BS1 may be a primary BS, and BS2, BS3, BS4, and BS5 may be cooperative BSs with BS1. RUE1 may be a common RUE for BS1, BS2, BS3, and BS4, and RUE2 may be a common RUE for BS1 and BS5. The embodiments of FIG. 18a and 18b may be divided into a "configuration phase for measuring the difference in transmission timing errors (e.g., the embodiment of FIG. 18a)" and a "measurement / transmission phase for measuring / transmitting the difference in transmission timing errors (e.g., the embodiment of FIG. 18b)." In the setup step for measuring the difference in transmission timing error, BS1 (e.g., primary BS) can request the transmission of RUE registration lists from cooperating BSs (e.g., BS2, BS3, BS4, BS5) (S1801). The cooperating BSs can be neighboring BSs of BS1 or partner BSs.

[0156] The cooperating BSs can receive a request to transmit an RUE registration list from BS1. In S1802, BS2 can transmit an RUE registration list containing information on the RUE(s) registered with it to BS1, BS3 can transmit an RUE registration list containing information on the RUE(s) registered with it to BS1, BS4 can transmit an RUE registration list containing information on the RUE(s) registered with it to BS1, and BS5 can transmit an RUE registration list containing information on the RUE(s) registered with it to BS1. BS1 can receive RUE registration lists from neighboring BSs. BS1 can identify RUEs commonly registered with the BSs based on the RUE registration lists. BS1 can determine RUE1 as a common RUE for BS1, BS2, BS3, and BS4, and BS1 can determine RUE2 as a common RUE for BS1 and BS5.

[0157] BS1 can set a first group including BS1, BS2, BS3, BS4, and RUE1, and a second group including BS1, BS5, and RUE2. BS1 can negotiate with cooperating BSs belonging to the first group about the time when reference signals can be transmitted and reserve radio resources for the reference signal transmission based on the negotiation result. BS1 can negotiate with cooperating BSs belonging to the second group about the time when reference signals can be transmitted and reserve radio resources for the reference signal transmission based on the negotiation result.

[0158] BS1 may transmit reference signal information (e.g., resource reservation information) to each cooperating BS (S1803). The reference signal information may be divided into reference signal information for the first group and reference signal information for the second group. The reference signal information may include reference signal resource reservation information for each cooperating BS. The reference signal resource reservation information may indicate radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal. The cooperating BS may receive reference signal information from BS1 and, based on the received information, may confirm radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal.

[0159] BS1 may transmit reference signal information (e.g., resource reservation information) for the first group to RUE1 (e.g., common RUE) (S1804). RUE1 may receive reference signal information from BS1 and, based on the received information, may determine the radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal. BS1 may transmit reference signal information (e.g., resource reservation information) for the second group to RUE2 (e.g., common RUE) (S1805). RUE2 may receive reference signal information from BS1 and, based on the received information, may determine the radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal.

[0160] In the transmission timing error difference measurement / transmission step, BS1, BS2, BS3, and BS4 may each transmit a reference signal to RUE1 using the reserved radio resources (S1806), and BS1 and BS5 may each transmit a reference signal to RUE2 using the reserved radio resources (S1807). The reference signals may be transmitted based on a simultaneous transmission scheme or a sequential transmission scheme. The reference signals may be DMRS, CSI-RS, PRS, and / or PT-RS. RUE1 may receive the reference signals using the reserved radio resources and calculate the transmission timing error difference based on the measurement results of the reference signals (S1808). RUE1 may calculate the transmission timing error difference between BS1 and BS2, the transmission timing error difference between BS1 and BS3, and the transmission timing error difference between BS1 and BS4. RUE2 may receive the reference signals using the reserved radio resources and calculate the transmission timing error difference based on the measurement results of the reference signals (S1809). RUE2 may calculate the transmission timing error difference between BS1 and BS5. RUE1 and RUE2 can calculate the difference in transmission timing error between the BSs based on Equations 1 and 2, respectively.

[0161] RUE1 may transmit information about the difference in transmission timing error to BS1 (S1810). BS1 may acquire information about the difference in transmission timing error from RUE1. RUE2 may transmit information about the difference in transmission timing error to BS1 (S1811). BS1 may acquire information about the difference in transmission timing error from RUE2. BS1 may transmit information about the difference in transmission timing error to each cooperating BS (S1812). The difference in transmission timing error transmitted to BS2, BS3, and BS4 belonging to the first group may be the difference in transmission timing error calculated by RUE1. The difference in transmission timing error transmitted to BS5 belonging to the second group may be the difference in transmission timing error calculated by RUE2. The accuracy of absolute synchronization between BSs may be improved based on the difference in transmission timing error. When BSs perform cooperative communication, the BSs may perform downlink transmission to UEs after compensating for the difference in transmission timing error. For example, each BS may transmit a signal earlier or later by the difference in transmission timing error to improve the accuracy of absolute synchronization.

[0162] Table 1 below may show the difference in transmission timing error measured by RUE1. The difference in transmission timing error in Table 1 may be the difference in transmission timing error that RUE1 reports to BS1. Table 1 may show the difference in transmission timing error measured with respect to BS1. Other BS(es) may perform transmission after compensating for the difference in transmission timing error with respect to BS1. Alternatively, the difference in transmission timing error with respect to BS2, BS3, or BS4 may be derived from Table 1. In this case, the other BS(es) may perform transmission after compensating for the difference in transmission timing error with respect to BS2, BS3, or BS4. The present disclosure may include not only a method for measuring / reporting the difference in transmission timing error with respect to BS1, but also a method for measuring / reporting the difference in transmission timing error with respect to other BSs (e.g., BS2, BS3, BS4).

[0163] [Table 1]

[0164] Table 2 below may show the difference in transmission timing error measured by RUE2. The difference in transmission timing error in Table 2 may be the difference in transmission timing error that RUE2 reports to BS1. Table 2 may show the difference in transmission timing error measured with BS1 as the reference. Other BS(es) may perform transmission after compensating for the difference in transmission timing error with BS1 as the reference. Alternatively, the difference in transmission timing error with respect to BS5 may be derived from Table 2. In this case, other BS(es) may perform transmission after compensating for the difference in transmission timing error with respect to BS5 as the reference. The present disclosure may include not only a method for measuring / reporting the difference in transmission timing error with respect to BS1, but also a method for measuring / reporting the difference in transmission timing error with respect to another BS (e.g., BS5).

[0165] [Table 2]

[0166] Cooperative communication between BSs can be performed in the cooperative scenario shown in Figure 17. In this case, BS2, BS3, BS4, and BS5 can perform downlink transmission after compensating for differences in transmission timing errors. Because downlink transmission is performed based on BS1, BS1 can perform downlink transmission without compensating for differences in transmission timing errors. Downlink transmission can be a transmission operation of downlink data.

[0167] According to the above-described embodiments (e.g., the embodiments of FIGS. 3 to 18), the influence of transmission timing errors between different BSs can be eliminated or reduced. To achieve ATS in a wireless factory automation system, the following embodiments (e.g., the embodiments of FIGS. 19 to 25) can be considered.

[0168] In the embodiments of Figures 3 to 18, even if the first UE (e.g., any UE) is not an RUE, if the first UE accurately knows the propagation delay (or distance) between the first UE and the BS(es), the first UE can act as an RUE.

[0169] To achieve ATS between UEs belonging to a single BS in a wireless factory automation system, a method of eliminating the effect of transmission timing errors by utilizing RUEs can be used.

[0170] FIG. 19 is a flow chart illustrating a sixth embodiment of a method for avoiding transmission timing errors.

[0171] Referring to FIG. 19, BS1 and TRP1 may exist, BS1 may be a single BS, TRP1 may be a single TRP, and TRP1 may belong to BS1. BS1 may be connected to multiple UEs. In other words, multiple UEs may exist within the coverage of BS1. When BS1 transmits a signal to UE1, a radio propagation delay (τ BS1、UE1 ), there is a transmission timing error (e BS1、UE1、TX ) and the reception timing error (e BS1、UE1、RX ) may exist. The receive timing error can be overcome to some extent through the sophisticated design of the physical layer numerology. The transmit timing error is caused by the inherent hardware damage of the communication node, so BS1 and / or UE1 do not know the transmit timing error. In addition, BS1 and / or UE1 cannot control the transmit timing error.

[0172] When TRP1 belonging to BS1 transmits a signal to UE2, the radio propagation delay (τ TRP1、UE2 ), the transmission timing error (e TRP1、UE2、TX ) and the reception timing error (e TRP1、UE2、RX) may exist. The receive timing error can be overcome to some extent through the careful design of the physical layer numerology. The transmit timing error is caused by inherent hardware damage of the communication node, so BS1, TRP1, and / or UE2 do not know the transmit timing error. In addition, BS1, TRP1, and / or UE2 cannot control the transmit timing error.

[0173] When RUE1 is located between BS1 and TRP1 (e.g., TRP1 belonging to BS1), the transmission timing error caused by BS1 and TRP1 cannot be determined, but the difference in transmission timing error between BS1 and TRP1 can be determined using RUE1. BS1 and TRP1 know the location of RUE1. The location of RUE1 can be a location with good wireless fading channel quality relative to BS1 and TRP1, a location with no change in the wireless fading channel quality, or a location with minimal change in the wireless fading channel quality. BS1 and / or RUE1 know the propagation delay (τ BS1、RUE1 ) is known, and TRP1 and / or RUE1 are the propagation delays from TRP1 to RUE1 (τ TRP1、RUE1 ) can be understood.

[0174] The receive timing error (e BS1、RUE1、RX , e TRP1、RUE1、RX ) may be nearly identical when the wireless link quality of each of BS1 and TRP1 is equal to or exceeds a predefined standard. In this disclosure, BS1 and TRP1 may be assumed to be connected by a wire, and the synchronization between BS1 and TRP1 may be assumed to be very precise absolute synchronization.

[0175] BS1 and TRP1 can transmit a signal for absolute synchronization simultaneously or at a predefined time (e.g., sample time point). The signal for absolute synchronization can be referred to as an absolute synchronization signal. The absolute synchronization signal can be transmitted periodically or aperiodically. RUE1 is the arrival time (T BS1、RUE1) and the arrival time (T TRP1、RUE1 ) can be measured. In other words, RUE1 is T BS1、RUE1 -T TRP1、RUE1 It is possible to measure T BS1、RUE1 T may mean the time when the absolute synchronization signal transmitted by BS1 arrives at RUE1. TRP1、RUE1 may mean the time when the absolute synchronization signal transmitted by TRP1 arrives at RUE1.

[0176]

number

[0177] The difference in propagation delay (τ BS1、RUE1 -τ TRP1、RUE1 ) as A, RUE1 can measure or estimate the difference (B) between the arrival times and the transmission timing error based on A. B can be defined as Equation 4 below.

[0178]

number

[0179] RUE1 can transmit (e.g., signal) information related to B or B to BS1 and / or TRP1. BS1 and / or TRP1 can receive information related to B or B from RUE1. BS1 and / or TRP1 can transmit information related to B or B to a control station (e.g., controller) that manages and / or controls the BS(es). The control station can receive information related to B or B from BS1 and / or TRP1. The control station can adjust the transmission time (e.g., sample time point) of BS1 and / or TRP1 using the information related to B or B. Alternatively, RUE1 can transmit (e.g., signal) information regarding the transmission time (e.g., sample time point) of BS1 and / or TRP1 to BS1 and / or TRP1 without a control station.

[0180] According to this operation, as shown in Equation 5 below, the transmission timing errors for UE1 and UE2 belonging to a single BS cannot be eliminated, but the transmission timing errors can be adjusted to be the same.

[0181]

number

[0182] According to Equation 5, TRP1 can adjust its transmission time by adding the difference (B) in the transmission timing error to the existing transmission time. This operation allows UE1 and UE2 to achieve ATS without affecting the transmission timing error. Therefore, sophisticated cooperative operations can be performed.

[0183] When a control station that manages and / or controls BS1, RUE1, or BS1 transmits information requesting a transmission time adjustment, the information may include the difference (B) in the transmission timing errors in Equation 5 and / or a method for adjusting the transmission timing errors to be equal. The method for adjusting the transmission timing errors to be equal may be "a method for adjusting the transmission time of BS1 earlier by B / 2" and / or "a method for adjusting the transmission time of TRP1 later by B / 2."

[0184] FIG. 20 is a conceptual diagram illustrating a first example of a cooperation scenario of a BS and a TRP.

[0185] Referring to FIG. 20, a BS may be wired to TRP1 and TRP2. UE1 may be registered with the BS, UE2 may be registered with TRP1, and UE3 may be registered with TRP2. A UE may be registered with the BS, TRP1, and TRP2. The BS may act as a digital unit (DU) for TRP1 and TRP2. For example, the BS may perform digital signal processing functions. The BS may also communicate with UE1 via a wireless access link. For cooperative communication, absolute synchronization must be achieved between UE1, UE2, and UE3. The BS, TRP1, and TRP2 may each acquire a difference in transmission timing error and compensate for the difference in transmission timing error before performing communication. According to the above operation, absolute synchronization between UE1, UE2, and UE3 may be achieved.

[0186] 21a and 21b are a flow chart illustrating a third embodiment of a method for measuring and communicating differences in transmit timing errors.

[0187] 21a and 21b, the embodiments of FIG. 21a and 21b may be applied to the cooperative scenario illustrated in FIG. 20, where the embodiment of FIG. 21a may be performed before the embodiment of FIG. 21b, and the embodiment of FIG. 21b may be performed after the completion of the embodiment of FIG. 21a. The embodiments of FIG. 21a and 21b may be divided into a "configuration step for measuring the difference in transmission timing errors (e.g., the embodiment of FIG. 21a)" and a "measurement / transmission step for measuring / transmitting the difference in transmission timing errors (e.g., the embodiment of FIG. 21b)." In the configuration step for measuring the difference in transmission timing errors, the BS may request the TRP (e.g., TRP1, TRP2) to transmit an RUE registration list (S2101). The BS may request the TRP in which the UE(s) targeted for cooperative communication are registered to transmit the RUE registration list.

[0188] The TRP can receive a request to transmit an RUE registration list from the BS. In S2102, TRP1 can transmit an RUE registration list containing information about the RUE(s) registered to it to the BS, and TRP2 can transmit an RUE registration list containing information about the RUE(s) registered to it to the BS. The BS can receive the RUE registration list from the TRP. The BS can check the RUEs commonly registered to the TRP and the BS based on the RUE registration list. In other words, the BS can check the common RUEs registered to the BS, TRP1, and TRP2. The BS, TRP1, and TRP2 can be connected to a common RUE.

[0189] The BS can negotiate with the TRP about the time when the reference signal can be transmitted and can reserve radio resources for transmitting the reference signal based on the negotiation result. The BS can transmit reference signal information (e.g., resource reservation information, transmission resource information) to each TRP (S2103). The reference signal information can include reference signal resource reservation information for each TRP. The reference signal resource reservation information can indicate the radio resources reserved for transmitting the reference signal and / or the transmission time of the reference signal. The TRP can receive reference signal information from the BS and can confirm the radio resources reserved for transmitting the reference signal and / or the transmission time of the reference signal based on the received information.

[0190] The BS may transmit information about the reference signal (e.g., resource reservation information) to the RUE (e.g., common RUE) (S2104). The information about the reference signal transmitted in S2103 may be the same as the information about the reference signal transmitted in S2104. The RUE may receive the information about the reference signal from the BS and, based on the received information, may determine the radio resources reserved for transmitting the reference signal and / or the transmission time of the reference signal.

[0191] In the transmission timing error difference measurement / transmission step, the BS, TRP1, and TRP2 may each transmit a reference signal to the RUE using the reserved radio resources (S2105). The reference signal may be transmitted based on a simultaneous transmission scheme or a sequential transmission scheme. The reference signal may be DMRS, CSI-RS, PRS, and / or PT-RS. The RUE may receive the reference signal using the reserved radio resources and calculate the transmission timing error difference based on the measurement result of the reference signal (S2106). For example, the RUE may calculate the transmission timing error difference between communication nodes based on Equation 3 and Equation 4 (or Equation 1 and Equation 2). The RUE may calculate the transmission timing error difference between the BS and TRP1 and the transmission timing error difference between the BS and TRP2.

[0192] The RUE can transmit information about the difference in transmission timing error to the BS (S2107). The BS can acquire information about the difference in transmission timing error from the RUE. The BS can transmit information about the difference in transmission timing error to each TRP (S2108). The accuracy of absolute synchronization between communication nodes (e.g., BS, TRP) can be improved based on the difference in transmission timing error. When the BS and TRP perform cooperative communication, each of the BS and TRP can perform downlink transmission to the UE after compensating for the difference in transmission timing error. For example, each communication node can transmit a signal earlier or later by the difference in transmission timing error to improve the accuracy of absolute synchronization.

[0193] 22a and 22b are a flow chart illustrating a fourth embodiment of a method for measuring and communicating differences in transmit timing errors.

[0194] 22a and 22b, the embodiments of FIG. 22a and 22b may be applied to the cooperative scenario illustrated in FIG. 20, and the embodiment of FIG. 22a may be performed before the embodiment of FIG. 22b, and the embodiment of FIG. 22b may be performed after the completion of the embodiment of FIG. 22a. The embodiments of FIG. 22a and 22b may be divided into a "configuration step for measuring the difference in transmission timing errors (e.g., the embodiment of FIG. 22a)" and a "measurement / transmission step for measuring the difference in transmission timing errors (e.g., the embodiment of FIG. 22b)." In the configuration step for measuring the difference in transmission timing errors, the BS may request the RUE to transmit a TRP registration list (S2201). The BS may request information on the TRP(s) to which the RUE is registered.

[0195] The RUE may receive a request for transmission of a TRP registration list from the BS. The RUE may transmit the TRP registration list including information on the TRP(s) to which it is registered to the BS (S2202). The BS may receive the TRP registration list from the RUE. The BS may select a TRP to which the UE(s) that are the target of cooperative communication are connected from among the TRPs indicated by the TRP registration list. For example, the BS may select TRP1 and TRP2. The UE(s) that are the target of cooperative communication may belong to TRP1 and TRP2.

[0196] The BS can negotiate with the TRP about the time when the reference signal can be transmitted and can reserve radio resources for transmitting the reference signal based on the negotiation result. The BS can transmit reference signal information (e.g., resource reservation information, transmission resource information) to each TRP (S2203). The reference signal information can include reference signal resource reservation information for each TRP. The reference signal resource reservation information can indicate the radio resources reserved for transmitting the reference signal and / or the transmission time of the reference signal. The TRP can receive reference signal information from the BS and can confirm the radio resources reserved for transmitting the reference signal and / or the transmission time of the reference signal based on the received information.

[0197] The BS may transmit information about the reference signal (e.g., resource reservation information) to the RUE (e.g., common RUE) (S2204). The information about the reference signal transmitted in S2203 may be the same as the information about the reference signal transmitted in S2204. The RUE may receive the information about the reference signal from the BS and, based on the received information, may determine the radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal.

[0198] In the transmission timing error difference measurement / transmission step, the BS, TRP1, and TRP2 may each transmit a reference signal to the RUE using the reserved radio resources (S2205). The reference signal may be transmitted based on a simultaneous transmission scheme or a sequential transmission scheme. The reference signal may be DMRS, CSI-RS, PRS, and / or PT-RS. The RUE may receive the reference signal using the reserved radio resources and calculate the transmission timing error difference based on the measurement result of the reference signal (S2206). For example, the RUE may calculate the transmission timing error difference between communication nodes based on Equation 3 and Equation 4 (or Equation 1 and Equation 2). The RUE may calculate the transmission timing error difference between the BS and TRP1 and the transmission timing error difference between the BS and TRP2.

[0199] The RUE can transmit information about the difference in transmission timing error to the BS (S2207). The BS can acquire information about the difference in transmission timing error from the RUE. The BS can transmit information about the difference in transmission timing error to each TRP (S2208). The accuracy of absolute synchronization between communication nodes (e.g., BS, TRP) can be improved based on the difference in transmission timing error. When the BS and TRP perform cooperative communication, each of the BS and TRP can perform downlink transmission to the UE after compensating for the difference in transmission timing error. For example, each communication node can transmit a signal earlier or later by the difference in transmission timing error to improve the accuracy of absolute synchronization.

[0200] Table 3 below may show the difference in transmission timing error measured by the RUE. The difference in transmission timing error in Table 3 may be the difference in transmission timing error reported by the RUE to the BS. The BS may share the difference in transmission timing error with TRP1 and TRP2. When the BS, TRP1, and TRP2 perform cooperative communication, TRP1 and TRP2 may each perform downlink transmission after compensating for the difference in transmission timing error in Table 3. Because downlink transmission is performed based on the BS, the BS may perform downlink transmission without compensating for the difference in transmission timing error. Downlink transmission may be a transmission operation of downlink data.

[0201] [Table 3]

[0202] FIG. 23 is a flow chart illustrating a seventh embodiment of a method for avoiding transmission timing errors.

[0203] Referring to FIG. 23, there may be a single BS, and multiple TRPs (e.g., TRP1 and TRP2) may belong to the BS. The BS may be connected to multiple TRPs. Each of TRP1 and TRP2 may be connected to multiple UEs. In other words, multiple UEs may exist within the coverage of each of TRP1 and TRP2. When TRP1 transmits a signal to UE1, the radio propagation delay (τ TRP1、UE1 ), the transmission timing error (e TRP1、UE1、TX ) and the reception timing error (e TRP1、UE1、RX ) may exist. The receive timing error can be overcome to some extent through the sophisticated design of the physical layer numerology. The transmit timing error is caused by the inherent hardware damage of the communication node, so TRP1 and / or UE1 do not know the transmit timing error. Also, TRP1 and / or UE1 cannot control the transmit timing error.

[0204] When TRP2 transmits a signal to UE2, the radio propagation delay (τ TRP2、UE2 ), the transmission timing error (e TRP2、UE2、TX ) and the reception timing error (e TRP2、UE2、RX ) may exist. The receive timing error can be overcome to some extent through the careful design of the physical layer numerology. The transmit timing error is caused by the inherent hardware damage of the communication node, so TRP2 and / or UE2 do not know the transmit timing error. Also, TRP2 and / or UE2 cannot control the transmit timing error.

[0205] FIG. 24 is a conceptual diagram illustrating a first embodiment of a cooperative scenario for TRP.

[0206] Referring to FIG. 24, multiple TRPs (e.g., TRP1, TRP2, TRP3, and TRP4) may be wired to one BS. TRP1, TRP2, and TRP3 may be connected to a common RUE, RUE1. TRP3 and TRP4 may be connected to a common RUE, RUE2. In the cooperative scenario of FIG. 24, a method for measuring / reporting the difference in transmission timing error between TRPs may be necessary for cooperative communication. Each TRP may be wired to the BS. Each TRP may receive reference signal information for measuring the difference in transmission timing error from the BS. In other words, the BS may request each TRP to transmit a reference signal.

[0207] The BS can acquire the difference in transmission timing errors for TRP1, TRP2, TRP3, and TRP4, which are connected to the BS and perform cooperative communication. The BS can transmit the difference in transmission timing errors to TRP1, TRP2, TRP3, and TRP4. TRP1, TRP2, TRP3, and TRP4 can perform transmission after compensating for the difference in transmission timing errors. TRP1, TRP2, and TRP3 can be connected to RUE1, and TRP3 and TRP4 can be connected to RUE2.

[0208] 25a and 25b are a flow chart illustrating a fifth embodiment of a method for measuring and communicating differences in transmit timing errors.

[0209] 25a and 25b, the embodiments of FIG. 25a and 25b may be applied to the cooperative scenario illustrated in FIG. 24, and the embodiment of FIG. 25a may be performed before the embodiment of FIG. 25b, and the embodiment of FIG. 25b may be performed after the completion of the embodiment of FIG. 25a. A BS may be connected to TRP1, TRP2, TRP3, and TRP4. The embodiments of FIG. 25a and 25b may be divided into a "configuration step for measuring the difference in transmission timing errors (e.g., the embodiment of FIG. 25a)" and a "measurement / transmission step for measuring / transmitting the difference in transmission timing errors (e.g., the embodiment of FIG. 25b)." In the configuration step for measuring the difference in transmission timing errors, the BS may request the TRPs (e.g., TRP1, TRP2, TRP3, and TRP4) performing cooperative communication to transmit RUE registration lists (S2501).

[0210] The TRP can receive a request to transmit an RUE registration list from the BS. In S2502, TRP1 can transmit an RUE registration list containing information about the RUE(s) registered to it to the BS, TRP2 can transmit an RUE registration list containing information about the RUE(s) registered to it to the BS, TRP3 can transmit an RUE registration list containing information about the RUE(s) registered to it to the BS, and TRP4 can transmit an RUE registration list containing information about the RUE(s) registered to it to the BS. The BS can receive the RUE registration list from the TRP. The BS can check the RUEs commonly registered to the TRPs based on the RUE registration list. The BS can determine RUE1 as a common RUE for TRP1, TRP2, and TRP3. The BS can determine RUE2 as a common RUE for TRP3 and TRP4.

[0211] The BS may configure a first group including TRP1, TRP2, TRP3, and RUE1. The BS may designate TRP1 as the primary TRP for the first group. The BS may configure a second group including TRP3, TRP4, and RUE2. The BS may designate TRP4 as the primary TRP for the second group. The primary TRP may perform radio resource reservation, reception of transmission timing error difference information, and / or transmission of transmission timing error difference information. TRP1 (e.g., the primary TRP) may negotiate with cooperating TRPs in the first group regarding the available time for reference signal transmission and reserve radio resources for reference signal transmission based on the negotiation result. TRP4 (e.g., the primary TRP) may negotiate with cooperating TRPs in the second group regarding the available time for reference signal transmission and reserve radio resources for reference signal transmission based on the negotiation result.

[0212] TRP1 may transmit reference signal information (e.g., resource reservation information) to each of TRP2 and TRP3 belonging to the first group (S2503). TRP4 may transmit reference signal information (e.g., resource reservation information, transmission resource information) to TRP3 belonging to the second group (S2504). The reference signal information may include reference signal resource reservation information for each TRP. The reference signal resource reservation information may indicate radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal. TRP2 and TRP3 may each receive reference signal information for the first group from TRP1 and determine the radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal based on the received information. TRP3 may receive reference signal information for the second group from TRP4 and determine the radio resources reserved for transmission of the reference signal and / or the transmission time of the reference signal based on the received information.

[0213] TRP1 may transmit reference signal information (e.g., resource reservation information, transmission resource information) for the first group to RUE1 (e.g., common RUE) (S2505). RUE1 may receive reference signal information from TRP1 and, based on the received information, may determine the radio resources reserved for transmitting the reference signal and / or the transmission time of the reference signal. TRP4 may transmit reference signal information (e.g., resource reservation information, transmission resource information) for the second group to RUE2 (e.g., common RUE) (S2506). RUE2 may receive reference signal information from TRP4 and, based on the received information, may determine the radio resources reserved for transmitting the reference signal and / or the transmission time of the reference signal.

[0214] In the transmission timing error difference measurement / transmission step, TRP1, TRP2, and TRP3 may each transmit a reference signal to RUE1 using the reserved radio resources (S2507), and TRP3 and TRP4 may each transmit a reference signal to RUE2 using the reserved radio resources (S2508). The reference signals may be transmitted based on a simultaneous transmission scheme or a sequential transmission scheme. The reference signals may be DMRS, CSI-RS, PRS, and / or PT-RS. RUE1 may receive the reference signals using the reserved radio resources and calculate a transmission timing error difference based on the measurement results of the reference signals (S2509). RUE1 may calculate a transmission timing error difference between TRP1 and TRP2 and a transmission timing error difference between TRP1 and TRP3. RUE2 may receive the reference signals using the reserved radio resources and calculate a transmission timing error difference based on the measurement results of the reference signals (S2510). RUE2 may calculate a transmission timing error difference between TRP4 and TRP3. RUE1 and RUE2 can calculate the difference in transmission timing error between the BSs based on Equations 1 and 2, respectively.

[0215] RUE1 can transmit information about the difference in transmission timing error to TRP1 (e.g., primary TRP) (S2511). TRP1 can acquire information about the difference in transmission timing error from RUE1. TPR1 can transmit information about the difference in transmission timing error to the BS (S2512). The BS can acquire information about the difference in transmission timing error from TRP1. RUE2 can transmit information about the difference in transmission timing error to TRP4 (e.g., primary TRP) (S2513). TRP4 can acquire information about the difference in transmission timing error from RUE2. TPR4 can transmit information about the difference in transmission timing error to the BS (S2514). The BS can acquire information about the difference in transmission timing error from TRP4.

[0216] The BS may generate a transmission timing error difference for all TRPs (e.g., TRP1, TRP2, TRP3, and TRP4) performing cooperative communication based on the transmission timing error difference of TRP1 and the transmission timing error difference of TRP4. In other words, the BS may interpolate the transmission timing error difference of TRP4 based on TRP1, and generate a transmission timing error difference for all TRPs (e.g., TRP1, TRP2, TRP3, and TRP4) performing cooperative communication based on the interpolated transmission timing error difference. The BS may transmit the transmission timing error difference to each TRP (S2515). Each TRP may obtain the transmission timing error difference from the BS. The accuracy of absolute synchronization between TRPs may be improved based on the transmission timing error difference. In cooperative communication, each TRP may perform downlink transmission after compensating for the transmission timing error difference based on TRP1. For example, each TRP may transmit a signal earlier or later by the transmission timing error difference to improve the accuracy of absolute synchronization.

[0217] Table 4 below may show the difference in transmission timing error measured by RUE1. The difference in transmission timing error in Table 4 may be the difference in transmission timing error reported by RUE1 to TRP1. Table 4 may show the difference in transmission timing error measured based on TRP1.

[0218] [Table 4]

[0219] Table 5 below may show the difference in transmission timing error measured by RUE2. The difference in transmission timing error in Table 5 may be the difference in transmission timing error reported by RUE2 to TRP4. Table 5 may show the difference in transmission timing error measured based on TRP4.

[0220] [Table 5]

[0221] The BS can interpolate the difference in transmission timing error in Table 5 based on TRP1, and can generate the difference in transmission timing error for all TRPs (e.g., TRP1, TRP2, TRP3, TRP4) performing cooperative communication by taking into account the interpolated difference in transmission timing error. Table 6 can show the difference in transmission timing error for all TRPs performing cooperative communication. The BS can derive the difference in transmission timing error between TRP1 and TRP4 based on the difference in transmission timing error measured by RUE1 and the difference in transmission timing error measured by RUE2. TRP1 may not be directly connected to TRP4.

[0222] [Table 6]

[0223] In the above-mentioned embodiments (e.g., the embodiments of Figures 19 to 25), even if the first UE (e.g., any UE) is not an RUE, if the first UE accurately knows the propagation delay (or distance) between the first UE and the BS(es), the first UE can act as an RUE.

[0224] The methods disclosed herein may be embodied in the form of program instructions that can be executed by various computer means and stored on a computer-readable medium. The computer-readable medium may include, alone or in combination with other program instructions, data files, data structures, and the like. The program instructions stored on the computer-readable medium may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the type well known and available to those skilled in the art of computer software.

[0225] Examples of computer-readable media include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, as well as machine code, such as produced by a compiler. The aforementioned hardware devices may be configured to operate with at least one software module to perform the operations of the present disclosure, and vice versa.

[0226] Although the present disclosure has been described with reference to the embodiments, it will be understood that those skilled in the art can make various modifications and variations to the present disclosure without departing from the spirit and scope of the present disclosure as set forth in the claims below.

Claims

1. 1. A reference user equipment (RUE) method, comprising: receiving a first error measurement request message at a first base station; receiving a second error measurement request message at a second base station; receiving a first reference signal at the first base station based on the first error measurement request message; determining a first transmission timing of the first base station based on the first reference signal; receiving a second reference signal at the second base station based on the second error measurement request message; determining a second transmission timing of the second base station based on the second reference signal; calculating a difference between the first transmit timing and the second transmit timing; transmitting a first error measurement response message including information of the difference to the first base station; and The method of the RUE includes transmitting a second error measurement response message including information of the difference to the second base station.

2. 2. The method of claim 1, wherein the first error measurement request message includes information on a transmission resource for the first reference signal, and the second error measurement request message includes information on a transmission resource for the second reference signal, and each of the first reference signal and the second reference signal is one of a demodulation reference signal (DMRS), a channel state information-reference signal (CSI-RS), a positioning reference signal (PRS), or a phase tracking-reference signal (PT-RS).

3. 2. The RUE method of claim 1, wherein the first error measurement request message and the second error measurement request message each include a type field and a corresponding BS (base station) field, the type field indicating that the type of the error measurement message is an error measurement request, the corresponding BS field included in the first error measurement request message is set to an ID (identifier) ​​of the second base station, which is a corresponding BS for which error measurement is desired, and the corresponding BS field included in the second error measurement request message is set to an ID of the first base station, which is a corresponding BS for which error measurement is desired.

4. 2. The method of claim 1, wherein the first error measurement response message and the second error measurement response message each include a type field, a counterpart BS field, a timing difference field, and a compensation BS field, wherein the type field indicates that the type of the error measurement message is an error measurement response, the counterpart BS field included in the first error measurement response message is set to an ID of the second base station that is a counterpart BS for which error measurement is desired, the counterpart BS field included in the second error measurement response message is set to an ID of the first base station that is a counterpart BS for which error measurement is desired, the timing difference field is set to the difference between the first transmission timing and the second transmission timing, and the compensation BS field indicates a BS that compensates for the difference between transmission timings.

5. 2. The method of claim 1, wherein the first transmission timing is determined by further considering a first propagation delay between the first base station and the RUE, and the second transmission timing is determined by further considering a second propagation delay between the second base station and the RUE.

6. The RUE method of claim 1 , wherein the RUE is a common RUE between one or more RUEs registered with the first base station and one or more RUEs registered with the second base station.

7. 1. A method of a first base station, comprising: transmitting a first error measurement request message to a reference user equipment (RUE); transmitting a first reference signal to the RUE based on the first error measurement request message; transmitting an error measurement request message to a second base station; receiving, at the RUE, a first error measurement response message including information of a difference between a first transmission timing of the first base station and a second transmission timing of the second base station; and The method of the first base station includes the step of performing downlink communication by compensating for the difference.

8. The method of the first base station includes: requesting one or more RUEs to transmit a base station (BS) registration list; receiving one or more BS registration lists at the one or more RUEs; and and further comprising: identifying a common RUE commonly registered in the first base station and the second base station based on the one or more BS registration lists; The method of claim 7, wherein the RUE to which the first error measurement request message is transmitted is the common RUE.

9. The method of the first base station includes: requesting one or more base stations to transmit an RUE registration list; receiving one or more RUE registration lists at the one or more base stations; and and further comprising identifying the second base station with which the RUE is registered among the one or more base stations based on the one or more RUE registration lists; The method of claim 7, wherein the RUE is a common RUE registered in common with the first base station and the second base station, and the error measurement request message is transmitted to the second base station having the common RUE.

10. The method of the first base station includes: The method of claim 7 , further comprising transmitting information of the difference between the first transmission timing of the first base station and the second transmission timing of the second base station to the second base station.

11. 8. The method of claim 7, wherein the first error measurement request message includes a type field and a counterpart BS field, the type field indicating that the type of the error measurement message is an error measurement request, and the counterpart BS field included in the first error measurement request message is set to an ID (identifier) ​​of the second base station, which is a counterpart BS for which error measurement is desired.

12. The method of claim 7, wherein the error measurement request message requests the second base station to transmit a second error measurement request message or a second reference signal to the RUE.

13. 8. The method of claim 7, wherein the first error measurement response message includes a type field, a counterpart BS field, a timing difference field, and a compensation BS field, wherein the type field indicates that the type of the error measurement message is an error measurement response, the counterpart BS field included in the first error measurement response message is set to an ID of the second base station, which is a counterpart BS for which error measurement is desired, the timing difference field is set to the difference between the first transmission timing and the second transmission timing, and the compensation BS field indicates a BS that compensates for the difference between the transmission timings.

14. 8. The method of claim 7, wherein the first transmission timing is determined by further considering a first propagation delay for the first base station and the RUE, and the second transmission timing is determined by further considering a second propagation delay for the second base station and the RUE.

15. 1. A method of a first base station, comprising: transmitting an error measurement request message to a second base station requesting transmission of a second reference signal; transmitting an error measurement request message to a reference user equipment (RUE); transmitting a first reference signal to the RUE based on the error measurement request message; receiving, at the RUE, an error measurement response message including information of a difference between a first transmission timing of the first base station and a second transmission timing of the second base station; and The method of the first base station includes the step of performing downlink communication by compensating for the difference.

16. 16. The method of claim 15, wherein the error measurement request message requests simultaneous or sequential transmission of the first reference signal and the second reference signal, the error measurement request message includes transmission resource information of the second reference signal, and the second reference signal of the second base station is transmitted to the RUE from a transmission resource indicated by the transmission resource information.

17. The method of claim 15, wherein the error measurement request message includes transmission resource information of the first reference signal and transmission resource information of the second reference signal.

18. 16. The method of claim 15, wherein the first transmission timing is determined by further considering a first propagation delay for the first base station and the RUE, and the second transmission timing is determined by further considering a second propagation delay for the second base station and the RUE.

19. The method of the first base station includes: requesting one or more RUEs to transmit a base station (BS) registration list; receiving one or more BS registration lists at the one or more RUEs; and and further comprising: identifying a common RUE commonly registered in the first base station and the second base station based on the one or more BS registration lists; The method of claim 15, wherein the RUE to which the error measurement request message is transmitted is the common RUE.

20. The method of the first base station includes: requesting one or more base stations to transmit an RUE registration list; receiving one or more RUE registration lists at the one or more base stations; and and further comprising identifying the second base station with which the RUE is registered among the one or more base stations based on the one or more RUE registration lists; The method of claim 15, wherein the RUE is a common RUE registered in common with the first base station and the second base station, and the error measurement request message is transmitted to the second base station having the common RUE.

Images