KR20220054194A - Method and appratus for simultaneous transmission and reception operation in communication system - Google Patents

Abstract

Disclosed is a simultaneous transmission/reception operation technology in a communication system to prevent occurrence of power imbalance between received signals. According to the present invention, a method of operating an integrated access and backhaul (IAB) node of a communication system comprises the following steps: receiving a first signal from a first node and receiving a second signal from a second node to measure a power difference between the received first signal and second signal; controlling transmission power of each of the first node and the second node on the basis of the power difference; generating scheduling information allowing the first node and the second node to simultaneously transmit signals; transmitting the scheduling information to the first node and the second node; and receiving signals simultaneously transmitted according to the scheduling information from the first node and the second node.

Description

Simultaneous transmission and reception operation method and apparatus in a communication system

The present invention relates to a technology for simultaneous transmission and reception in a communication system, and more particularly, to a non-TDM (non-time division multiplexing) method in integrated access and backhaul (IAB) so that an IAB node can transmit and receive data at the same time It relates to a technology for simultaneous transmission and reception in a communication system.

With the development of information and communication technology, various wireless communication technologies may be developed. As a representative wireless communication technology, there may be long term evolution (LTE), new radio (NR), etc. defined in a 3rd generation partnership project (3GPP) standard. LTE may be one of 4G (4th Generation) wireless communication technologies, and NR may be one of 5G (5th Generation) wireless communication technologies.

For the processing of wireless data rapidly increasing after commercialization of a 4G communication system (eg, a communication system supporting LTE), a frequency band of a 4G communication system (eg, a frequency band of 6 GHz or less) as well as a 4G communication system A 5G communication system (eg, a communication system supporting NR) using a higher frequency band (eg, a frequency band of 6 GHz or higher) than the frequency band of may be being considered. The 5G communication system may support enhanced Mobile BroadBand (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and Massive Machine Type Communication (mMTC).

Such a 5G communication system uses a high-frequency band such as millimeter wave that can utilize a wide bandwidth in addition to the low-frequency band below 6 GHz supported by the existing 4G communication system in order to satisfy the ever-increasing user requirements for mobile communication. method was introduced. The newly introduced millimeter wave may have a smaller cell coverage due to its strong propagation characteristics, which may lead to a closer arrangement between cells, which may significantly increase the cost of optical cable construction. On the other hand, according to the integrated access and backhaul (IAB) technology, it can be flexible for a 5G cell that can use a wide band, and a wireless backhaul link and an access link to enable dense deployment. IAB nodes that integrally support can be formed. In such an IAB environment, when an IAB node transmits and receives data simultaneously to a parent node and a child node in a non-TDM (non-TDM) method rather than a time division multiplexing (TDM) method, interference may occur. In order to solve this problem, a non-TDM-based resource multiplexing method applicable to a process in which an IAB node transmits/receives a signal to/from a parent node and a child node, and detailed technology required therefor may be required.

An object of the present invention for solving the above problems is to provide a resource multiplexing method for simultaneously transmitting and receiving data to and from an IAB node in a non-TDM manner with a parent node and a child node, and a detailed technology necessary therefor, in a communication system To provide a method and apparatus for simultaneous transmission and reception of

A method for simultaneously operating transmission and reception in a communication system according to a first embodiment of the present invention for achieving the above object is a method of operating an integrated access and backhaul (IAB) node of a communication system, comprising: a first signal received from a first node; measuring a power difference of a second signal received from a second node; controlling each transmit power of the first node and the second node based on the power difference; generating scheduling information for allowing the first node and the second node to simultaneously transmit signals; transmitting the scheduling information to the first node and the second node; and receiving signals simultaneously transmitted according to the scheduling information using the transmission power from the first node and the second node.

Here, the controlling of the transmit power may include: determining whether the power difference exceeds a first threshold; recognizing first headroom information of the first node and second headroom information of the second node when the power difference exceeds the first threshold value; determining the transmit power of the first node based on the first headroom information and determining the transmit power of the second node based on the second headroom information; and transmitting the determined transmission power information to each of the first node and the second node.

Here, the controlling of the transmit power may include: determining whether the power difference exceeds a second threshold; and when the power difference exceeds a second threshold, switching the transmission method of the first node and the transmission method of the second node from a non-time division multiplexing (TDM) method to a TDM method. there is.

Here, the controlling of the transmit power may include: determining whether the power difference exceeds a first threshold; transmitting a request signal instructing adjustment to a first power adjustment range and a transmission power within the first power adjustment range to the first node when the power difference exceeds the first threshold value; and receiving a response signal including information indicating that the transmit power of the first node is adjusted to the transmit power within the first power adjustment range.

Here, the controlling of the transmit power may include: determining whether the power difference exceeds a first threshold; transmitting a request signal of a second power adjustment range to the first node when the power difference exceeds the first threshold; receiving a response signal including the second power adjustment range from the first node; checking the second power adjustment range in the response signal; and selecting a transmission power from the checked second power adjustment range and transmitting a signal instructing adjustment to the selected transmission power to the first node.

On the other hand, in order to achieve the above object, a method for simultaneous transmission and reception in a communication system according to a second embodiment of the present invention is a method of operating an integrated access and backhaul (IAB) node of a communication system, a downlink signal transmitted to a child node determining a downlink minimum power of calculating uplink available power based on the downlink minimum power; informing a parent node of information on the uplink available power; receiving information on transmit power selected within the uplink available power from the parent node; and transmitting an uplink signal to the parent node using the transmission power selected by the parent node.

Here, the determining of the downlink minimum power may include: receiving a sounding reference signal from the child node; and determining the downlink minimum power based on the received signal strength of the sounding reference signal.

Here, the determining of the downlink minimum power may include: transmitting a downlink reference signal to the child node; receiving received signal strength information of the downlink reference signal from the child node; and determining the minimum downlink power based on the received signal strength information.

Here, in the calculating of the uplink available power, the uplink available power may be calculated by subtracting the downlink minimum power from an uplink maximum power that is a maximum power usable for the uplink.

On the other hand, the simultaneous transmission and reception operation method in the communication system according to the third embodiment of the present invention for achieving the above object is a method of operating an IAB node of the communication system, the first time based on the round trip delay time of the first node determining; A second time for making the start time of the symbols of the first uplink signal transmitted from the first time to the first node coincide with the start time of the symbols of the second uplink signal received from the second node in the time domain calculating ; transmitting the calculated second time information to the second node; and receiving the second uplink signal from the second node when the second time is added to the timing at which the first node receives the first uplink signal, wherein the second time is It is calculated by subtracting a remainder value obtained by dividing the first time by the symbol length from the symbol length, and the second uplink signal may be transmitted based on the second time.

Here, the method further comprising transmitting the first uplink signal to the first node at a time point obtained by subtracting the first time from the timing at which the first node receives the first uplink signal, In the symbols at which one uplink signal is transmitted, a start time of at least one symbol may coincide with a reception time of the second uplink signal.

Here, identifying first positions of the first reference signals included in the first uplink signal and second positions of the second reference signals included in the second uplink signal; calculating a first offset of the second reference signals based on the first positions and the second positions; transmitting the calculated first offset information to the second node; and receiving, from the second node, a third uplink signal comprising third reference signals disposed according to the first offset, the portion of the first locations disposed according to the first offset. Some of the third positions of the third reference signals may be aligned in the time domain.

Here, the calculating of the first offset includes counting the number of symbols arranged between a symbol start time of each of the first reference signals and a symbol start time of a second reference signal closest to each of the first reference signals. to calculate counting values; and determining, as the first offset, a counting value most repeated among the counting values.

Here, the information of the second time may be transmitted through downlink control information or a medium access control (MAC) control element (CE).

Here, the method of operating the IAB node includes: receiving a first downlink signal from the first node; determining a second offset such that a position of a first reference signal in fourth reference signals included in the first downlink signal coincides with a start time of the second uplink signal; transmitting the information of the second offset to the first node; receiving a second downlink signal including fourth reference signals arranged according to the second offset from the first node; checking fourth positions of fourth reference signals included in the second downlink signal and second positions of second reference signals included in the second uplink signal; calculating a third offset of the second reference signals included in the second uplink signal based on the second positions and the fourth positions; transmitting the calculated third offset information to the second node; and receiving, from the second node, a fourth uplink signal including fifth reference signals disposed according to the third offset, wherein a portion of fourth positions of the fourth reference signals and the fifth Some of the fifth positions of the reference signals may be aligned in the time domain.

In the present application, the IAB node performs power control so that the received power difference between signals received from communication nodes (eg, a parent node, a child node, a terminal) is within a certain range to generate a power imbalance between the received signals can prevent

In addition, the IAB node may prevent the occurrence of a power imbalance between the transmitted signals by performing power control so that the power difference between the signals transmitted from the child node and the terminal is within a predetermined range.

In addition, the IAB node may align the uplink reception timing of the IAB node with the uplink transmission timing by allowing one or more connected child nodes to transmit an uplink signal based on timing advanced (TA).

In addition, the IAB node may facilitate the detection of the reference signal by allowing the reception timing of the reference signal of the uplink transmission signal transmitted to the parent node and the uplink reception signal received from the child node to be aligned in the time domain.

1 is a conceptual diagram illustrating a first embodiment of an IAB network structure.
2 is a block diagram illustrating a first embodiment of an IAB node included in an IAB network.
3 is a conceptual diagram illustrating a first embodiment of a connection relationship of an IAB network.
4 is a block diagram illustrating a first embodiment of a multi-hop structure of an IAB network.
5 is a conceptual diagram illustrating a first embodiment of radio channel resource multiplexing between a parent link and a child link of an IAB node.
6 is a conceptual diagram illustrating interference occurring when an IAB node performs communication in a full-duplex communication scheme in an in-band scheme.
7 is a conceptual diagram illustrating a first embodiment of a non-TDM-based resource multiplexing scheme in an IAB node.
8 is a conceptual diagram illustrating a second embodiment of a non-TDM-based resource multiplexing scheme in an IAB node.
9 is a conceptual diagram illustrating a third embodiment of a non-TDM-based resource multiplexing scheme in an IAB node.
10 is a conceptual diagram illustrating a fourth embodiment of a non-TDM-based resource multiplexing scheme in an IAB node.
11 is a conceptual diagram illustrating a first embodiment when power control is required in an IAB node.
12 is a flowchart illustrating a first embodiment of a power control method in an IAB node.
13 is a conceptual diagram illustrating a second embodiment when power control is required in an IAB node.
14 is a flowchart illustrating a second embodiment of a power control method in an IAB node.
15 is a flowchart illustrating a third embodiment of a power control method in an IAB node.
16 is a conceptual diagram illustrating a third embodiment when power control is required in an IAB node.
17 is a flowchart illustrating a fourth embodiment of a power control method in an IAB node.
18 is a conceptual diagram illustrating a first embodiment of an IAB node timing alignment method.
19 is a flowchart illustrating a first embodiment of an IAB node timing alignment method.
20 is a conceptual diagram illustrating a second embodiment of an IAB node timing alignment method.
21 is a flowchart illustrating a second embodiment of an IAB node timing alignment method.
22 is a conceptual diagram illustrating a first embodiment when reference signals are not aligned in an IAB node.
23 is a flowchart illustrating a first embodiment of a method for aligning a reference signal of an IAB node.
24 is a conceptual diagram illustrating a first embodiment of a method for aligning a reference signal of an IAB node.
25 is a flowchart illustrating a second embodiment of a method for aligning a reference signal of an IAB node.
26 is a conceptual diagram in which an IAB node moves a reference signal of an uplink signal to be transmitted to a parent node.
27 is a conceptual diagram illustrating a second embodiment of a method for aligning a reference signal of an IAB node.
28 is a conceptual diagram illustrating a second embodiment when reference signals are not aligned in an IAB node.
29 is a flowchart illustrating a third embodiment of a method for aligning a reference signal of an IAB node.
30 is a conceptual diagram illustrating a third embodiment of a method for aligning a reference signal of an IAB node.
31 is a flowchart illustrating a fourth embodiment of a method for aligning a reference signal of an IAB node.
32 is a conceptual diagram when an IAB node receives a downlink signal to which a reference signal is moved from a parent node.
33 is a conceptual diagram illustrating a fourth embodiment of a method for aligning a reference signal of an IAB node.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

In embodiments of the present application, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B”. Also, in the embodiments of the present application, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B”.

When an element is referred to as being “connected” or “connected” to another element, it is understood that it may be directly connected or connected to the other element, but other elements may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Throughout the specification, a network is, for example, a wireless Internet such as WIFI, a wireless broadband internet (WiBro) or a portable Internet such as a world interoperability for microwave access (WiMax), a global system for mobile communication (GSM), or a code (CDMA). 3G mobile communication network such as division multiple access) or CDMA2000, 3.5G (3.5 ^th generation) mobile communication network such as high speed downlink packet access (HSDPA) or high speed uplink packet access (HSUPA), long term evolution (LTE) network or LTE - It may include a 4G (4th generation) mobile communication network, such as Advanced, and a ^5G ( ^5th generation) mobile communication network.

Throughout the specification, a terminal refers to a mobile station, a mobile terminal, a subscriber station, a portable subscriber station, a user equipment, and an access terminal. and the like, and may include all or some functions of a terminal, a mobile station, a mobile terminal, a subscriber station, a portable subscriber station, a user device, an access terminal, and the like.

The above-mentioned terminal is a desktop computer capable of communication, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a smart phone, a smart watch (smart watch), smart glass, e-book reader, PMP (portable multimedia player), portable game console, navigation device, digital camera, DMB (digital multimedia broadcasting) player, digital voice Users of mobile communication services such as digital audio recorders, digital audio players, digital picture recorders, digital picture players, and digital video players It can mean various devices that can.

Throughout the specification, a base station is an access point, a radio access station, a node B, an evolved node B, a base transceiver station, MMR - May refer to BS (Mobile Multi-hop Relay - Base Station), etc., and may include all or part of functions such as base station, access point, wireless access station, NodeB, eNodeB, transceiver base station, MMR-BS, etc. there is.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, a 3GPP NR system as well as a 3GPP LTE/LTE-A system may be described as an example of a radio access system in which embodiments of the present application can be used. Hereinafter, in order to clarify the description of the present application, the description is based on a 3GPP communication system (LTE, NR, etc.), but the technical spirit of the present application is not limited thereto.

The following techniques are code division multiple access (CDMA). It can be used in various access communication systems, such as frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple access (SC-FDMA).

Hereinafter, preferred embodiments of the present application will be described in more detail with reference to the accompanying drawings. In order to facilitate the overall understanding in describing the present application, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

1 is a conceptual diagram illustrating a first embodiment of an IAB network structure.

Referring to FIG. 1 , an IAB network 100 of a mobile communication system may include an IAB donor and/or at least one or more IAB nodes. The IAB donor may communicate with at least one or more IAB nodes via a backhaul link. In addition, the IAB donor may communicate with at least one or more terminals through an access link. The IAB node may be connected to at least one or more other IAB nodes through a backhaul link. The aforementioned IAB node may relay communication between the IAB donor and other IAB nodes. The IAB node may be connected to at least one terminal through an access link. The above-described IAB node may relay communication between the IAB donor and the terminal. The above-described IAB node may relay communication between the IAB donor and other IAB nodes and/or terminals. For example, the IAB donor may communicate with IAB Node A over a backhaul link, and the IAB donor may communicate with terminal A over an access link.

In an embodiment, the IAB node A may be connected to the IAB donor through a backhaul link, and the IAB node A may be connected to the terminal B through an access link. IAB Node A may relay communication between the IAB Donor and UE B. The IAB donor may communicate with the terminal B through the relay of the IAB node A.

In another embodiment, the IAB Node B may be connected to the IAB donor through a backhaul link, and the IAB Node B may be connected to the UE C through an access link.

The present application is not limited to the above-described IAB network structure, and various IAB network topologies to which a technique for relaying communication between at least one IAB donor, at least one IAB node, and/or at least one terminal in a mobile communication system can be applied It can be applied to the IAB network having The IAB donor is connected to the IAB node through a backhaul, and can make a relay connection to the terminals. A multi-hop connection communicating via at least one node may be possible between IAB nodes.

2 is a block diagram illustrating a first embodiment of an IAB node included in an IAB network.

Referring to FIG. 2 , the IAB node 200 of the mobile communication system includes at least one processor 210 , a memory 220 and/or a transmission and/or receive module 230 . may include The above-described processor receives information on a plurality of time resources divided into a plurality of time resources through a transmission/reception module in order to transmit/receive a signal, and transmits the above-described signal in one time resource among the time resources divided into a plurality of times through a transmission/reception module, , one time resource described above may be determined based on the IAB node list. The above-described transceiver 230 may be referred to as a transceiver, a radio frequency (RF) unit, an RF module, or the like. In addition, the IAB node 200 may further include an input interface device 240 , an output interface device 250 and/or a storage device 260 , and the like. Each of the components included in the IAB node 200 may be connected by a bus 270 to communicate with each other.

However, each component included in the IAB node 200 may not be connected to the common bus 270 but to the processor 210 through an individual interface or an individual bus. 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/or the storage device 260 through a dedicated interface. may be

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260 . The processor 210 may mean a central processing unit (CPU), a graphics processing unit (GPU), and/or a dedicated processor on which methods according to embodiments of the present application are performed. The memory 220 and/or the storage device 260 may be configured as at least one of a volatile storage medium and/or a non-volatile storage medium. For example, the memory 220 may be configured as a read only memory (ROM) and/or a random access memory (Random Access memory).

3 is a conceptual diagram illustrating a first embodiment of a connection relationship of an IAB network.

Referring to FIG. 3 , an IAB network of a mobile communication system may include an IAB donor and/or at least one or more IAB nodes. When an IAB node is connected to a plurality of other IAB nodes through a backhaul link, an IAB node having the smallest number of hops from an IAB donor among the above-described plurality of IAB nodes may be referred to as a parent IAB node. Among the above-described plurality of IAB nodes, an IAB node having the smallest number of hops from an IAB donor may be referred to as a child IAB node. An IAB node may have a plurality of child IAB nodes, but may not have a plurality of parent IAB nodes.

The IAB node may transmit data to at least one or more child IAB nodes via a downlink backhaul link, and the IAB node may receive data from at least one or more child IAB nodes via an uplink backhaul link. The IAB node may perform the same role as the base station for at least one or more child IAB nodes. That is, the IAB node controls the transmission rate of data to the child IAB node, routing, HARQ (Hybrid automatic repeat and request) retransmission, synchronization signal transmission, reference signal transmission, scheduling (scheduling) ), channel control, mobility management, and the like. In addition, at least one or more IAB nodes may receive data from a parent IAB node through a downlink backhaul link, and at least one or more IAB nodes may transmit data to a parent IAB node through an uplink backhaul link. At least one or more IAB nodes may perform the same role as a terminal with respect to a parent IAB node.

4 is a block diagram illustrating a first embodiment of a multi-hop structure of an IAB network.

4, the protocol structure of the IAB donor may be composed of a CU (Central Unit) and a DU (Distributed Unit) depending on the function to be performed, and the protocol structure of the IAB node is DU and MT (Mobile Terminal). can be composed of The CU of the IAB donor may be connected to the base station, and the DU of the IAB donor may perform a function of a base station for at least one or more other IAB nodes and/or at least one or more terminals. The DU of the IAB node may serve as a base station for at least one or more other IAB nodes, and the MT of the IAB node may perform the role of a terminal for at least one or more other IAB nodes.

The MT of at least one or more IAB nodes may serve as a terminal for the DU of the IAB donor, and the DU of the IAB donor may perform the role of a base station for the MT of at least one or more IAB nodes. The IAB network may transmit data through a resource request and allocation procedure between the MT (Mobile Terminal) of the IAB node and the DU of the parent IAB node. In addition to the above-described IAB multi-hop structure, the present application may be applied to a mobile communication network having various IAB multi-hop structures.

For example, the MT of the IAB node A may serve as a terminal for the IAB donor, and the DU of the IAB donor may perform the role of a base station for the IAB node A. Also, the MT of the IAB Node B may serve as a terminal for the DU of the IAB Node A, and the DU of the IAB Node A may serve as a base station for the MT of the IAB Node B. Referring to FIG. 4 , an IAB node and/or an IAB donor has assumed a separate structure of DU, MT, and/or CU, but the present application may be applied even when each of the IAB node and/or IAB donor does not have a separate structure.

On the other hand, the radio backhaul link frequency of the NR IAB can largely support both an in-band scheme and an out-band scheme.

5 is a conceptual diagram illustrating a first embodiment of radio channel resource multiplexing between a parent link and a child link of an IAB node.

Referring to FIG. 5 , the IAB node may support three radio channel resource multiplexing schemes between a parent link and a child link. In FIG. 5 , the X axis may be time. FIG. 5A is an orthogonal radio channel resource multiplexing method supported by an IAB node between a parent link and a child link, and radio channel resources may not overlap each other because radio resources are not reused. And, (b) of FIG. 5 is a radio channel resource multiplexing method of a partial reuse method supported by an IAB node between a parent link and a child link, and radio channel resources may partially overlap by partially reusing radio resources.

Finally, FIG. 5C shows a radio channel resource multiplexing scheme of a full reuse method supported by an IAB node between a parent link and a child link, and all radio channel resources may overlap by reusing all of the radio resources. Here, the orthogonal radio channel resource multiplexing method may be an out-band method. In addition, the radio channel resource multiplexing method of the partial reuse method and the radio channel resource multiplexing method of the full reuse method may be an in-band method.

When the IAB node operates in the radio channel resource multiplexing method of the partial reuse method corresponding to the in-band method and the radio channel resource multiplexing method of the full reuse method, multiplexing restrictions and interference problems between the access link and the backhaul link can be considered.

6 is a conceptual diagram illustrating interference occurring when an IAB node performs communication in a full-duplex communication scheme in an in-band scheme.

Referring to FIG. 6 , when an IAB node performs communication from an in-band method to a full-duplex communication method, inter-node interference and intra-node interference may occur. As an example, the IAB node may operate in a reception mode in which the MT receives a signal transmitted from a parent node at a transmission power f _p at a time t ₁ as represented by a solid line 610 , and the DU is transmitted at a time t ₁ . Communication can be performed using a full-duplex communication method that can operate in a transmission mode that transmits a signal to a child node with power f _c . In this case, the transmission signal of the parent node may cause inter-node interference with the reception signal of the child node.

In addition, the DU transmission signal may cause intra-node interference with the MT reception signal. On the other hand, the IAB node may operate in a transmission mode in which the MT transmits a signal to the parent node with the transmission power f _p at time t ₂ as represented by the dotted line 620 , and the transmission power f at time t ₂ from the child node It operates in a reception mode in which the DU receives a signal transmitted to _c to perform communication in a full-duplex communication mode. In this case, the transmission signal of the parent node may cause inter-node interference with the reception signal of the child node. In addition, the DU transmission signal may cause intra-node interference with the MT reception signal.

In such a situation, inter-node interference may be similar to interference in a general multiple-input and multiple-output (MIMO) environment, so that it may be relatively easy for the IAB node to manage the interference. Alternatively, in case of intra-node interference, the IAB node may receive the transmitted signal again. In this way, when the signal transmitted from the IAB node is received, the strength of the received signal may be much greater than the strength of the signal received from other nodes.

As a result, the AGC of the IAB node may far exceed the acceptable range, and demodulation of the received signal may be difficult due to very severe interference effects. On the other hand, the IAB node may be transmitted by the MT, and in this case, the DU may also be transmitted. Alternatively, the IAB node may receive the MT, in which case the DU may also be received. At this time, when the IAB node performs a downlink (DL) and an uplink (UL) using the same radio resource (eg, a frequency resource and a space resource), cross-link interference (CLI) This can happen. For this reason, the NR IAB of Rel-16 (Release 16) supports only a multiplexing technique based on time division multiplexing (TDM).

Meanwhile, the Rel-17 IAB WI (work item), which started with the first meeting of RAN1#102-e (radio access network 1#102-e) in August 2020, can further increase spectral efficiency and reduce the delay time of FR1 ( It aims to provide various technical improvements applicable to the frequency range 1) and FR2. In this regard, the RAN working group 1 (working group1) may focus on the advancement of the duplexing method, and standardization is in progress. To this end, the detailed goals pursued by the RAN Working Group 1 largely include the following two.

● Detailed Goal 1: Development of standards for improving resource multiplexing method between child link and parent link of IAB node

● Target 2: Development of specifications including timing mode, downlink/uplink power control, and backhaul link interference measurement to support simultaneous operation of child link and parent link of an IAB node

As can be seen from the detailed goal above, RAN Working Group 1 intends to develop a non-TDM (non-TDM)-based resource multiplexing method applicable to the child link and parent link of the IAB node, and a specification supporting the detailed technology required for this. The non-TDM-based resource multiplexing scheme to be developed in RAN Working Group 1 is largely under discussion on the following four schemes.

7 is a conceptual diagram illustrating a first embodiment of a non-TDM-based resource multiplexing scheme in an IAB node.

Referring to FIG. 7, in the non-TDM-based resource multiplexing scheme in the IAB node, the MT may operate in a transmission mode in which a signal is transmitted to a parent node at time t ₁ , and the DU also transmits a signal to a child node at time t ₁ It can operate in a transmit mode that transmits.

8 is a conceptual diagram illustrating a second embodiment of a non-TDM-based resource multiplexing scheme in an IAB node.

Referring to FIG. 8, in the non-TDM-based resource multiplexing scheme in the IAB node, the MT may operate in a transmission mode for transmitting a signal to the parent node at time t ₁ , and the DU transmits a signal from the child node at time t ₁ It can operate in a receiving receiving mode.

9 is a conceptual diagram illustrating a third embodiment of a non-TDM-based resource multiplexing scheme in an IAB node.

Referring to FIG. 9 , in the IAB node, in a non-TDM-based resource multiplexing scheme, the MT may operate in a reception mode in which a signal is received from a parent node at time t ₁ , and the DU transmits a signal to a child node at time t ₁ It can operate in a transmit mode that transmits.

10 is a conceptual diagram illustrating a fourth embodiment of a non-TDM-based resource multiplexing scheme in an IAB node.

Referring to FIG. 10, in the non-TDM-based resource multiplexing scheme in the IAB node, the MT may operate in a reception mode in which a signal is received from a parent node at time t ₁ , and the DU also receives a signal from a child node at time t ₁ It can operate in a receiving receiving mode.

In order for the IAB node to support the various simultaneous operation methods shown in FIGS. 7 to 10, power control between the child link and the parent link of the IAB node, power control, transmission/reception timing alignment (TX/RX timing alignment), and reference It may be necessary to additionally introduce various communication methods and procedures such as reference signal assignment.

1. Power Control

In order for the IAB node to perform simultaneous operation between the parent link and the child link, power control between the child link and the parent link may be required. There are three cases where power control is required.

11 is a conceptual diagram illustrating a first embodiment when power control is required in an IAB node.

Referring to FIG. 11 , when power control is required in the IAB node, the IAB node may simultaneously receive a UL signal from a child node and a terminal (ie, at time t ₁ ). In this case, since the power of the child node is generally much greater than the power of the terminal, power imbalance may occur between UL signals received by the IAB node. If the power imbalance between the two signals received by the IAB node is severe, the signal is distorted in the AGC, which may seriously affect the reception performance. Here, when power control is required in the IAB node, it is assumed that the IAB node simultaneously receives the UL signal from the child node and the terminal (ie, at time t1), but at the same time (ie, at time t1) from the child node and another child node. ) may be the same when receiving a UL signal.

12 is a flowchart illustrating a first embodiment of a power control method in an IAB node.

Referring to FIG. 12 , the UE may periodically transmit a sounding reference signal (SRS) to the IAB node (S1201). In this case, the UE may transmit an uplink power headroom (PH) report and a buffer state report (BSR) together to the IAB node. Then, the IAB node may receive a sounding reference signal, an uplink power headroom report, a buffer status report, and the like from the terminal. In addition, the IAB node may measure the received signal strength of the sounding reference signal. Here, the received signal strength may be a received signal strength indication (RSSI) or the like. Here, the headroom (PH) may indicate an amount of additionally available transmission power in addition to the power currently used by the UE for UL transmission.

Meanwhile, the child node may periodically transmit a sounding reference signal (SRS) to the IAB node (S1202). Here, the child node may be another IAB node connected to the DU of the IAB node. In this case, the child node may transmit an uplink power headroom (PH) report and a buffer status report (BSR) together to the IAB node. Then, the IAB node may receive a sounding reference signal, an uplink power headroom report, a buffer status report, and the like from the child node. In addition, the IAB node may measure the received signal strength of the sounding reference signal. Here, the received signal strength may be a received signal strength index (RSSI) or the like. In this case, the headroom (PH) may indicate an amount of additionally available transmission power in addition to the power currently used by the child node for UL transmission.

를 측정할 수 있다(S1203). 그리고, IAB 노드는 자식 노드와 단말로부터 수신한 헤드룸 정보를 고려하여 단말의 송신 전력을 결정할 수 있고, 자식 노드의 송신 전력을 결정할 수 있다(S1204). 이때, IAB 노드는 단말이 결정된 송신 전력을 사용하여 신호를 송신할 수 있고, 자식 노드가 결정된 송신 전력을 사용하여 IAB로 신호를 송신할 수 있는 경우에 IAB 노드가 단말과 자식 노드로부터 수신한 2개의 신호의 수신 신호 전력 차이가 AGC(automatic gain control)에서 신호가 왜곡되지 않도록 하는 제1 임계값

을 초과하지 않도록 송신 전력들을 결정할 수 있다. As such, the IAB node may receive a signal from the terminal and measure the received signal strength, receive a signal from the child node to measure the received signal strength, and use the measured received signal strengths to measure the received power difference between the two signals

can be measured (S1203). Then, the IAB node may determine the transmission power of the terminal in consideration of the child node and the headroom information received from the terminal, and may determine the transmission power of the child node (S1204). At this time, when the IAB node can transmit a signal using the determined transmission power of the terminal and the child node can transmit a signal to the IAB using the determined transmission power, the IAB node receives 2 received from the terminal and the child node. A first threshold value for preventing the signal from being distorted in AGC (automatic gain control) by the difference in received signal power of the signals

It is possible to determine the transmit powers so as not to exceed .

Thereafter, the IAB node may schedule the terminal and the child node to simultaneously perform uplink transmission (S1205). Then, the IAB node may transmit scheduling information to the terminal and the child node (S1206, S1207). In addition, the IAB node may inform the determined transmission power information to the terminal and the child node (S1208, S1209). Here, the IAB node is implemented to separately transmit the scheduling information and the transmission power information to the terminal and the child node, but it may be implemented to transmit them simultaneously. Thereafter, the IAB node may receive uplink signals transmitted by using the transmit power determined from the terminal and the child node (S1210, S1211).

를 주기적으로 측정할 수 있다. 그리고, IAB 노드는 측정한 수신 전력 차이 값이

값을 초과하지 않도록 단말과 자식 노드에 대한 상향 링크 전력 제어를 주기적으로 수행할 수 있다. 하지만 IAB 노드는 수신 전력 차이가 상향 링크 전력 제어를 통해 극복할 수 없는 제2 임계값을 초과한 경우에는 두 링크를 비-TDM방식에서 TDM 방식으로 전환할 수 있다.On the other hand, the IAB node receives a difference in reception power that changes as the terminal or child node moves from the time when simultaneous reception is started.

can be measured periodically. And, the IAB node is the measured received power difference value

Uplink power control for the terminal and the child node may be periodically performed so as not to exceed the value. However, when the received power difference exceeds a second threshold that cannot be overcome through uplink power control, the IAB node may switch the two links from the non-TDM scheme to the TDM scheme.

Here, when power control is required in the IAB node, it is assumed that the IAB node simultaneously receives the UL signal from the child node and the terminal (ie, at time t1), but at the same time (ie, at time t1) from the child node and another child node. ) may be the same when receiving a UL signal.

13 is a conceptual diagram illustrating a second embodiment when power control is required in an IAB node.

Referring to FIG. 13 , when power control is required in the IAB node, the IAB node may simultaneously receive the DL of the parent node and the UL of the child node (ie, at time t ₁ ). Here, the parent node may be another IAB node connected to the MT of the IAB node. And, the child node may be another IAB node connected to the DU of the IAB node. At this time, since the DU (of the parent node) can operate higher transmit power than the MT (of the child node), the IAB node can receive the DL signal from the parent node with higher strength than the UL signal from the child node. , and this may cause a power imbalance problem, and may distort the signal in the AGC.

가 제1 임계값

을 초과하는 경우(

>

)) DL과 UL을 동시에 수신하도록 스케쥴링을 하기 전에 부모 노드에 DL 전력 제어 가능 여부에 대한 요청(request)을 전달할 수 있고, 이에 대한 응답과 조정 가능한 DL 전력 범위에 대한 정보를 DL 제어 정보를 통해 수신할 수 있다. IAB 노드는 부모 노드로부터 전력 제어가 가능하다는 응답을 받을 수 있고, 조정 가능한 DL 전력 제어 범위에 대한 정보와 자식 노드의 헤드룸(PH) 정보를 고려하여 적절한 전력 제어를 통해

가

를 초과하지 않도록 할 수 있다. 이후에, IAB 노드는 자식 노드의 UL을 부모 노드의 DL과 동시에 스케쥴링할 수 있다.In this case, the IAB node can solve the power imbalance problem by allowing one of the parent node and the child node to increase or decrease the transmit power. To this end, the IAB node may periodically compare the received signal strengths of the parent node and the child node measured in the MT and the DU, respectively, and may receive headroom (PH) information from the child node. When the measured received signal strengths are unbalanced (that is, the received signal strength of the UL and the received signal strength of the DL, the received power difference

is the first threshold

If it exceeds (

>

)) Before scheduling to receive DL and UL at the same time, a request for whether DL power can be controlled can be transmitted to the parent node, and information on the response and adjustable DL power range can be provided through DL control information. can receive The IAB node may receive a response that power control is possible from the parent node, and through appropriate power control considering information on the adjustable DL power control range and the child node's headroom (PH) information

go

may not be exceeded. Thereafter, the IAB node may schedule the UL of the child node and the DL of the parent node at the same time.

14 is a flowchart illustrating a second embodiment of a power control method in an IAB node.

Referring to FIG. 14 , the parent node may periodically transmit a sounding reference signal (SRS) to the IAB node (S1401). Then, the IAB node may receive the sounding reference signal from the parent node. In addition, the IAB node may measure the received signal strength of the sounding reference signal. Here, the received signal strength may be a received signal strength index (RSSI) or the like. Here, the parent node may be another IAB node connected to the MT of the IAB node.

Meanwhile, the child node may periodically transmit a sounding reference signal (SRS) to the IAB node (S1402). Here, the child node may be another IAB node connected to the DU of the IAB node. In this case, the child node may transmit an uplink power headroom (PH) report and a buffer status report (BSR) together to the IAB node. Then, the IAB node may receive a sounding reference signal, an uplink power headroom report, a buffer status report, and the like from the child node. In addition, the IAB node may measure the received signal strength of the sounding reference signal. Here, the received signal strength may be a received signal strength index (RSSI) or the like. In this case, the headroom (PH) may indicate an amount of additionally available transmission power in addition to the power currently used by the child node for UL transmission.

를 측정할 수 있다(S1403). 이때, IAB 노드는 수신 전력 차이가 제1 임계값

을 초과하는지를 판단할 수 있다. IAB 노드는 판단 결과, 수신 전력 차이가 제1 임계값을 초과하면 자식 노드로부터 수신한 헤드룸 정보를 고려하여 수신 전력 차이가 제1 임계값을 초과하지 않도록 자식 노드의 송신 전력을 조정할 수 있다(S1404). As such, the IAB node may receive a signal from the parent node to measure the received signal strength, receive a signal from the child node to measure the received signal strength, and use the measured received signal strengths to measure the received signal strength difference between the two signals

can be measured (S1403). At this time, the IAB node receives the power difference is the first threshold

It can be determined whether or not As a result of the determination, when the received power difference exceeds the first threshold value, the IAB node may adjust the transmit power of the child node so that the received power difference does not exceed the first threshold value in consideration of the headroom information received from the child node ( S1404).

Thereafter, the IAB node may schedule the parent node and the child node to simultaneously perform transmission (S1405). Then, the IAB node may transmit the scheduling information to the parent node and the child node (S1406, S1407). In addition, the IAB node may inform the adjusted transmit power information to the child node (S1408). Thereafter, the IAB node may receive a downlink signal from the parent node (S1409). Also, the IAB node may receive an uplink signal from the child node (S1410).

가

를 초과할 수 있다. 또한, IAB 노드가 자식 노드의 헤드룸 정보 등을 통하여 자식 노드의 송신 전력을 조정하여 전력 불균형이 해결하였으나, 수신 전력 차이가 아래 수학식1과 같이 제1 임계값에 거의 근사할 수 있고, 수신 전력 차이가 제1 임계값에 근사한 기간이 일정 시간 동안 지속될 수 있다. 여기서, α는 α≤0일 수 있고, 절대값이 큰 값이 아닐 수 있다(일 예로, 5 미만). 이와 같은 경우에 IAB 노드는 다음 도 15와 같은 동작할 수 있다.On the other hand, the IAB node adjusts the transmit power of the child node through the headroom information of the child node, but the power imbalance occurs again.

go

can exceed In addition, the power imbalance was solved by the IAB node adjusting the transmit power of the child node through the headroom information of the child node, etc., but the received power difference can be approximately approximated to the first threshold value as shown in Equation 1 below, A period in which the power difference approximates the first threshold value may last for a predetermined time. Here, α may be α≤0, and the absolute value may not be a large value (for example, less than 5). In this case, the IAB node may operate as shown in FIG. 15 below.

15 is a flowchart illustrating a third embodiment of a power control method in an IAB node.

Referring to FIG. 15 , the parent node may periodically transmit a sounding reference signal (SRS) to the IAB node (S1501). Then, the IAB node may receive the sounding reference signal from the parent node. In addition, the IAB node may measure the received signal strength of the sounding reference signal. Here, the received signal strength may be a received signal strength index (RSSI) or the like. Here, the parent node may be another IAB node connected to the MT of the IAB node.

Meanwhile, the child node may periodically transmit a sounding reference signal (SRS) to the IAB node (S1502). Here, the child node may be another IAB node connected to the DU of the IAB node. In this case, the child node may transmit an uplink power headroom (PH) report and a buffer status report (BSR) together to the IAB node. Then, the IAB node may receive a sounding reference signal, an uplink power headroom report, a buffer status report, and the like from the child node. In addition, the IAB node may measure the received signal strength of the sounding reference signal. Here, the received signal strength may be a received signal strength index (RSSI) or the like. In this case, the headroom (PH) may indicate an amount of additionally available transmission power in addition to the power currently used by the child node for UL transmission.

를 측정할 수 있다(S1503). 이때, IAB 노드는 수신 전력 차이가 제1 임계값을 초과하는지를 판단할 수 있다. IAB 노드는 판단 결과, 수신 전력 차이가 제1 임계값을 초과하면 자식 노드로부터 수신한 헤드룸 정보를 고려하여 수신 전력 차이가 제1 임계값을 초과하지 않도록 자식 노드(또는 단말)의 송신 전력을 상향하도록 조정할 수 있다. As such, the IAB node may receive a signal from the parent node to measure the received signal strength, receive a signal from the child node to measure the received signal strength, and use the measured received signal strengths to measure the received signal strength difference between the two signals

can be measured (S1503). In this case, the IAB node may determine whether the received power difference exceeds the first threshold. As a result of the determination, when the received power difference exceeds the first threshold, the IAB node increases the transmit power of the child node (or terminal) so that the received power difference does not exceed the first threshold in consideration of the headroom information received from the child node. It can be adjusted upwards.

가

를 초과할 수 있거나, 수신 전력 차이가 수학식 1과 같이 제1 임계값에 거의 근사할 수 있고, 수신 전력 차이가 제1 임계값에 근사한 기간이 일정 시간 동안 지속될 수 있다. 이 경우에, IAB 노드는 부모 노드로 전력 제어 요청을 할 수 있다(S1504). 이 때, IAB 노드가 부모 노드로 전송하는 전력 제어 요청에는 조정 가능한 전력 조정 범위 정보와 전력 조정 범위내로 송신 전력의 조정을 지시하는 내용이 포함될 수 있다. However, even if the IAB node adjusts the transmit power of the child node through the headroom information of the child node, power imbalance occurs again

go

may exceed, or the received power difference may be approximately close to the first threshold as in Equation 1, and a period in which the received power difference approximates the first threshold may be continued for a predetermined time. In this case, the IAB node may make a power control request to the parent node (S1504). In this case, the power control request transmitted from the IAB node to the parent node may include adjustable power adjustment range information and a content instructing adjustment of transmit power within the power adjustment range.

Accordingly, the parent node may receive, from the IAB node, a power control request including information on the power adjustment range to be adjusted and content instructing to adjust the transmit power within the power adjustment range. In addition, when it is possible to adjust the transmit power within the power adjustment range requested by the IAB node, the parent node may adjust the transmit power to the transmit power within the requested power adjustment range, and power control indicating that the adjustment of transmit power is completed to the IAB node A response may be transmitted (S1505). Accordingly, the IAB node may receive the power control response, and may confirm the completion of the transmission power adjustment in the received power control response. Thereafter, the IAB node may schedule the parent node and the child node to transmit signals at the same time (S1506).

Then, the IAB node may transmit scheduling information to the parent node and the child node (S1507, S1508). Thereafter, the IAB node may receive a downlink signal from the parent node (S1509). Also, the IAB node may receive an uplink signal from a child node (S1510). In this case, the parent node may transmit a signal to the IAB node using the adjusted transmit power.

Here, the parent node receives the power adjustment range from the IAB node and adjusts the transmit power within the received power adjustment range, but the IAB node receives the adjustable power adjustment range from the parent node and transmits in the received power adjustment range By selecting a power, the selected transmission power may be informed to the parent node. To this end, the IAB node may include a request for a power adjustment range and an inquiry as to whether transmission power can be adjusted in the power control request transmitted to the parent node in S1504.

Accordingly, the parent node may receive a power control request including a request for a power adjustment range and an inquiry as to whether transmission power can be adjusted with a transmission power within the power adjustment range. In addition, when the power adjustment range information requested by the IAB node and transmission power can be adjusted, the parent node may transmit a power control response including the information to the IAB node. Accordingly, the IAB node may receive the power control response, and may check the response that the power adjustment range and the transmission power can be adjusted in the received power control response.

Thereafter, the IAB node may select the transmit power from the power adjustment range received from the parent node so that the received power difference does not exceed the first threshold. In addition, the IAB node may instruct the transmission power to be adjusted while notifying the selected transmission power to the parent node. Then, the parent node may adjust the transmit power according to the instruction received from the IAB node. Thereafter, the IAB node may schedule the parent node and the child node to simultaneously perform transmission. In addition, the IAB node may transmit scheduling information to the parent node and the child node. In addition, the IAB node may inform the adjusted transmit power information to the parent node. Thereafter, the IAB node may receive signals from the parent node and the child node. In this case, the parent node may transmit a signal to the IAB node using the adjusted transmit power.

Meanwhile, as described above, the IAB node may request power control from the parent node through the uplink control channel to lower the downlink transmission power of the parent node. The IAB node may periodically make such a power control request to the parent node. Accordingly, the parent node may periodically receive a power control request from the IAB node, and may adjust power by the requested amount. When the parent node exceeds the adjustable range, it may notify the IAB node again. Then, the IAB node may stop scheduling concurrent operations. In this case, the parent node may directly give a stop command to the IAB node.

On the other hand, unlike this, the IAB node may inform the parent node of the measured uplink and downlink signal quality (or received power difference) and headroom (PH) information. Then, the parent node may receive the signal quality (or received power difference) and headroom (PH) information of the uplink and the downlink from the IAB node. In addition, the parent node may determine the transmission power of the parent node and the transmission power of the child node based on the signal quality and headroom information received from the IAB node.

In addition, the parent node may transmit the transmission power determined for the child node to the child node through the IAB node. In addition, the parent node may schedule simultaneous transmission to the IAB node and the child node, and may transmit scheduling information to the IAB node and the child node. At this time, the parent node transmits the UL grant of the second stage, that is, the primary UL grant (transfer from the parent node to the IAB node) and the secondary UL grant (transfer from the IAB node to the child node). It is possible to schedule the UL of the receiving child node.

16 is a conceptual diagram illustrating a fourth embodiment when power control is required in an IAB node.

Referring to FIG. 16 , when power control is required in the IAB node, the IAB node may simultaneously transmit the UL of the parent node and the DL of the child node (ie, at time t ₁ ). Here, the parent child node may be another IAB node connected to the MT of the IAB node. The child node may be another IAB node connected to the DU of the IAB node. In this case, since the power of the signal transmitted to the parent node is generally much greater than the power of the signal transmitted to the child node, a power imbalance between the UL signal and the DL signal may occur in the IAB node.

If the power imbalance between the two signals transmitted by the IAB node is severe, the signal is distorted in the AGC, which may seriously affect the reception performance. In such a case, if the parent node increases or decreases the uplink transmit power of the IAB node, the downlink transmit power of the IAB node may decrease or increase. may need to be considered. This may generally occur when the MT and DU of the IAB node use the same antenna panel.

17 is a flowchart illustrating a third embodiment of a power control method in an IAB node.

을 결정할 수 있다(S1702). 그리고, IAB 노드는 상향 링크에 사용할 수 있는 최대 전력인 상향 링크 최대 전력

에서 하향 링크 최소 전력

을 감산하여 상향 링크 가용 전력

을 산출할 수 있다(S1703). Referring to FIG. 17 , in the power control method in the IAB node, the child node may periodically transmit a sounding reference signal (SRS) to the IAB node ( S1701 ). In addition, the IAB node may measure the received signal strength of the sounding reference signal. Here, the received signal strength may be a received signal strength index (RSSI) or the like. Accordingly, the IAB node determines the minimum downlink minimum power required for downlink transmission based on the measured received signal strength.

can be determined (S1702). And, the IAB node has the maximum power available for the uplink, which is the uplink maximum power.

Downlink Minimum Power at

uplink available power by subtracting

can be calculated (S1703).

Thereafter, the IAB node may inform the parent node of available uplink power through uplink control information (eg, UCI) (S1704). Accordingly, the parent node may receive uplink control information from the IAB node and may check available uplink power included in the received uplink control information. Thereafter, the parent node selects a transmit power within a range that does not exceed the available uplink power, and informs the IAB node of information on the selected transmit power to perform power control ( S1705 ). Accordingly, the IAB node may transmit an uplink signal using the transmit power according to the selected transmit power information received from the parent node.

에 추가적으로 앞서 설명한

값을 고려하여 헤드룸(PH)을 계산할 수 있고, 이를 부모 노드에 알려줄 수 있다. On the other hand, the IAB node may use a method of reporting the headroom (PH) differently from the method described above. In this case, when the IAB node calculates the headroom (PH) to be reported to the parent node, as shown in Equation 3, the power currently being used by the IAB node for uplink transmission

In addition to the previously described

The headroom (PH) may be calculated in consideration of the value, and this may be reported to the parent node.

은 앞서 설명하였듯이, IAB 노드가 자식 노드와의 상향 링크 채널 품질을 측정함으로써 결정할 수도 있다. 하지만, 이와 달리 자식 노드가 하향 링크 신호(예: 하향 링크 참조 신호)를 측정하여 IAB 노드에 보고할 수 있고, IAB 노드는 자식 노드로부터 수신한 하향 링크 신호에 대한 측정값을 기반으로 결정할 수 있다. 즉, IAB 노드는 자식 노드에게 하향 링크 참조 신호를 전송할 수 있다. 그러면, 자식 노드는 하향 링크 참조 신호를 수신하여 수신 신호 세기를 측정할 수 있다. 그리고, 자식 노드는 측정한 수신 신호 세기를 IAB 노드에 알려줄 수 있다. here,

As described above, the IAB node may determine by measuring the uplink channel quality with the child node. However, unlike this, the child node may measure a downlink signal (eg, a downlink reference signal) and report it to the IAB node, and the IAB node may determine it based on the measurement value of the downlink signal received from the child node. . That is, the IAB node may transmit a downlink reference signal to the child node. Then, the child node may measure the received signal strength by receiving the downlink reference signal. In addition, the child node may inform the IAB node of the measured received signal strength.

2. Align IAB Node Timing

According to section 7.4 of 38.874 technical report (TR) 38.874 of 3GPP Rel-16 NR IAB study item, in NR IAB, out of 7 timing alignment cases, the IAB node corresponding to case 1 and the IAB donor Transmission timing alignment may be supported natively. That is, both the IAB donor and the IAB node may have the same DL transmission timing. On the other hand, in Rel-17 IAB, as shown in FIGS. 7 to 10, the IAB node is under discussion to support four non-TDM-based multiplexing schemes.

Meanwhile, referring back to FIG. 8 , in the non-TDM-based resource multiplexing method of FIG. 8, the IAB node may operate in a transmission mode for transmitting a signal to a parent node, and operates in a reception mode for receiving a signal from a child node can do. In such a non-TDM-based resource multiplexing scheme, the transmission timing when the IAB node transmits a signal to the parent node may be matched with the reception timing when receiving the signal from the child node. In this case, the IAB node may need to inform the parent node of the change because the uplink transmission timing is changed according to the uplink reception timing of the child node. In addition, when there are a plurality of child nodes, the IAB node may have a disadvantage in that reception timing cannot be matched with all child nodes. Accordingly, the IAB node can adjust the reception timing when receiving a signal from the child node to the transmission timing when transmitting the signal to the parent node. In this case, the IAB node may align the uplink reception timing with the uplink timing of the IAB node by allowing one or more connected child nodes to transmit an uplink signal through timing advanced (TA).

18 is a conceptual diagram illustrating a first embodiment of an IAB node timing alignment method.

Referring to FIG. 18 , in the IAB node timing alignment method, the IAB node forwards the backhaul uplink transmission timing (T) by T1 so that the parent node can receive the backhaul uplink subframe 1820b at the backhaul uplink reception timing T. -T1) can be transmitted. Then, the parent node may receive the backhaul uplink subframe 1810a at the backhaul uplink reception timing T. Here, the time T1 may be determined using a round trip time (RTT) between the parent node and the IAB node. The parent node may determine T1 of the IAB node through a random access channel (RACH) procedure or the like.

Accordingly, the parent node may inform T1 as the IAB node. Here, although the parent node is configured to inform the IAB node of T1, the IAB node may receive the backhaul downlink subframe 1810b from the parent node to determine the time T1. That is, the parent node may include the backhaul downlink transmission timing T in the backhaul downlink subframe 1810b and transmit it to the IAB node. Then, the IAB node may receive the backhaul downlink subframe 1820c at a time delayed by time T1, and may know the transmission timing T in the received backhaul downlink subframe 1820c to determine the time T1. .

Here, the backhaul uplink subframe 1810a and the backhaul uplink subframe 1820b may be the same, and the backhaul downlink subframe 1810b and the backhaul downlink subframe 1820c may be the same.

Meanwhile, the child node transmits the backhaul uplink subframe 1830a ahead of time T by T1+T2 so that the IAB node can receive the backhaul uplink reception timing (T-T1) ahead of time T by T1. (T-T1-T2) can be transmitted. Then, the IAB node may receive the backhaul uplink subframe 1820a at the backhaul uplink reception timing (T-T1) earlier by T1 at time T. Here, the time T2 may be determined based on the round trip delay time (RTT) of the IAB node and the child node. As such, the IAB node may identify T2 through a random access channel (RACH) procedure or the like.

Accordingly, the IAB node may inform T2 as a child node. Here, although the IAB node is configured to inform the child node of T2, the child node may receive the backhaul downlink subframe 1820d from the IAB node to determine the time T2. That is, the IAB node may include the backhaul downlink transmission timing T in the backhaul downlink subframe 1820d and transmit it to the child node. Then, the child node may receive the backhaul downlink subframe 1830b at a time delayed by time T2, and may know the transmission timing T in the received backhaul downlink subframe 1830b to determine the time T2. . Here, the backhaul uplink subframe 1820a and the backhaul uplink subframe 1830a may be the same, and the backhaul downlink subframe 1820d and the backhaul downlink subframe 1830b may be the same.

19 is a flowchart illustrating a first embodiment of an IAB node timing alignment method.

Referring to FIG. 19 , in the IAB node timing alignment method, the parent node may perform a RACH procedure with the IAB node ( S1901 ). Then, the IAB node may determine the round-trip delay time (RTT) through the RACH procedure, and may determine T1 from the identified round-trip delay time (S1902). On the other hand, the IAB node may proceed with the RACH procedure with the child node (S1903). Then, the child node may determine the round-trip delay time (RTT) through the RACH procedure, and may determine T2 from the identified round-trip delay time (RTT) (S1904). And, the IAB node may inform T1 as a child node (S1905).

Then, the child node can transmit the backhaul uplink subframe, which is the backhaul uplink signal, to the IAB node by adding the time T2 to the time T1 and shifting the transmission timing forward by the added time T1 + T2 (S1906). Then, the IAB node may receive the backhaul uplink subframe from the child node at a time point ahead of time T by T1. Meanwhile, the IAB node may transmit a backhaul uplink subframe, which is a backhaul uplink signal, to the parent node at a transmission timing ahead of time T1 by time T ( S1907 ). Then, the parent node may receive the backhaul uplink subframe from the IAB node at time T.

Meanwhile, when the IAB node moves or is reconnected to another parent node, T1 may be changed, and the uplink transmission timing of the corresponding IAB node may be changed. This may mean that the uplink reception timing of the corresponding IAB node should also be changed accordingly.

을 하향링크 제어 정보(downlink control information, DCI) 또는 MAC(medium access control) CE(control element)를 통해 주기적으로 자식 노드들과 단말들에게 알려줄 수 있다. 여기서, 새로운 T1을

이라 할 수 있고, 이전의 T1을

라고 할 수 있으며,

는 다음 수학식 4와 같이 계산될 수 있다.However, one or more child nodes or terminals connected to the corresponding IAB node may not be able to know this information. Therefore, the IAB node moves or the timing difference of T1 changes as it accesses another parent node (timing difference)

may be periodically notified to child nodes and terminals through downlink control information (DCI) or medium access control (MAC) control element (CE). Here, the new T1

It can be said that the former T1

can be said,

can be calculated as in Equation 4 below.

가 너무 커서 IAB 노드가 자식 노드에게 알려줄 수 있는 TA값의 범위를 벗어나는 경우에는 변경된

를 다른 형태의 하향 링크 제어 정보 또는 MAC CE와 같은 방법으로 자식 노드들에게 알려줄 수 있거나, 자식 노드가 다시 RACH 절차를 통한 왕복 지연 시간을 이용하여 T1을 파악할 수 있도록 지시할 수 있다.Alternatively, the IAB node may periodically inform the child nodes and terminals of T1, which is changed as it moves or accesses another parent node, through downlink control information (DCI) or MAC CE. If the time difference of T1

If is too large and out of the range of TA values that the IAB node can inform its child nodes, the changed

may be informed to the child nodes in another form of downlink control information or MAC CE, or may instruct the child node to determine T1 again using the round trip delay time through the RACH procedure.

Meanwhile, referring back to FIG. 18 , when the uplink transmission timing of the IAB node and the downlink reception timing are aligned, a case may occur in which a child node or a terminal excessively advances the transmission timing. In order to solve such a problem, the parent node and the IAB node may use the method shown in FIG. 20 .

20 is a conceptual diagram illustrating a second embodiment of an IAB node timing alignment method.

Referring to FIG. 20 , in the IAB node timing alignment method, the IAB node forwards the backhaul uplink subframe 2020b by T1 in the backhaul uplink reception timing T so that the parent node can receive the backhaul uplink subframe 2020b at the backhaul uplink reception timing T. It can be transmitted at the link transmission timing (T-T1). Then, the parent node may receive the backhaul uplink subframe 2010a at the backhaul uplink reception timing T.

Here, the time T1 may be determined using a round-trip delay time (RTT) between the parent node and the IAB node. The parent node may determine T1 of the IAB node through the RACH procedure or the like. Accordingly, the parent node may inform T1 as the IAB node. Here, the parent node is configured to inform the IAB node of T1, but the IAB node may also receive the backhaul downlink subframe 2010b from the parent node to determine the time T1. That is, the parent node may transmit to the IAB node including the downlink transmission timing T in the backhaul downlink subframe 2010b.

Then, the IAB node may receive the backhaul downlink subframe 2020c at a time delayed by time T1, and may know the transmission timing T in the received backhaul downlink subframe 2020c to determine the time T1. . Here, the backhaul uplink subframe 2010a and the backhaul uplink subframe 2020b may be the same, and the backhaul downlink subframe 2010b and the backhaul downlink subframe 2020c may be the same.

On the other hand, the child node transmits the backhaul uplink subframe 2030a at the transmission timing earlier by T2-T3 at time T so that the IAB node can receive the backhaul uplink reception timing (T+T3) delayed by T3 at time T can Accordingly, the IAB node may receive the backhaul uplink subframe 2020a at the backhaul uplink reception timing (T+T3) delayed by T3 at time T.

Here, the time T2 may be determined using the round-trip delay time (RTT) of the IAB node and the child node. The IAB node may identify T2 through a random access channel (RACH) procedure or the like. Accordingly, the IAB node may inform T2 as a child node. Here, although the IAB node is configured to inform the child node of T2, the child node may receive the backhaul downlink subframe 2020d from the IAB node to determine the time T2.

That is, the IAB node may include the downlink transmission timing T in the backhaul downlink subframe 2020d and transmit it to the child node. Then, the child node can receive the backhaul downlink subframe 2030b at a time delayed by time T2, and can know the transmission timing T in the received backhaul downlink subframe 2030b, so that the time T2 can be grasped. . Here, the backhaul uplink subframe 2020a and the backhaul uplink subframe 2030a may be the same, and the backhaul downlink subframe 2020d and the backhaul downlink subframe 2030b may be the same.

은 심볼의 길이일 수 있다. Meanwhile, time T3 may be expressed by Equation 5 below. Here, mod may be a modular operation. And,

may be the length of a symbol.

In this way, the time T3 can be calculated by subtracting the remainder obtained by dividing T1 by the symbol length from the symbol length. Accordingly, the backhaul uplink reception timing of the IAB node may coincide with the start time of any one symbol of the uplink subframe 2020b transmitted according to the backhaul uplink transmission timing T1 of the IAB node.

21 is a flowchart illustrating a second embodiment of an IAB node timing alignment method.

Referring to FIG. 21 , in the IAB node timing alignment method, the parent node may perform a RACH procedure with the IAB node (S2101). Then, the IAB node may determine the round-trip delay time (RTT) through the RACH procedure, and may determine T1 from the identified round-trip delay time (RTT) (S2102). The IAB node may determine T3 by calculating T3 by subtracting the residual value obtained by dividing T1 by the symbol length from the symbol length (S2103).

On the other hand, the IAB node may proceed with the RACH procedure with the child node (S2104). Then, the child node may determine the round-trip delay time (RTT) through the RACH procedure, and may determine T2 from the identified round-trip delay time (RTT) ( S2105 ). And, the IAB node may inform T1 and T3 as child nodes (S2106). Then, the child node can calculate T2-T3 by subtracting time T3 from time T2 ( S2107 ). On the other hand, the IAB node may start transmitting the backhaul uplink subframe, which is the backhaul uplink signal, to the parent node at a transmission timing ahead of time T1 by time T ( S2108 ).

In this case, the child node may transmit the backhaul uplink subframe, which is the backhaul uplink signal, to the IAB node by shifting the transmission timing forward by T2-T3 (S2109). Then, the IAB node may receive the backhaul uplink subframe from the child node while transmitting the backhaul uplink subframe to the parent node. Accordingly, the IAB node may transmit the backhaul uplink subframe transmitted to the parent node by including some data in the backhaul uplink subframe received from the child node.

3. How to assign a reference signal

When the IAB node can transmit a signal to the parent node and receive a signal from the child node, the signal transmitted to the parent node may interfere with the signal received from the child node. A reference signal (eg, a demodulation reference signal (DMRS), a sounding reference signal (SRS)) carried in a signal transmitted by the IAB node to a parent node and a reference signal carried in a signal received by the IAB node from a child node are orthogonal can do.

Then, the IAB node may estimate the channel of the uplink transmission signal of the MT of the IAB node received in the DU of the IAB node or may measure the channel quality. The IAB node may make the two reference signals orthogonal by applying a time division multiplexing (TDM) and a frequency division multiplexing (FDM) method, but may be inefficient. Accordingly, the IAB node may set the reference signal of the uplink transmission signal of the MT of the IAB node and the uplink reception signal of the DU of the IAB node to have the same pattern in time and frequency axes.

22 is a conceptual diagram illustrating a first embodiment when reference signals are not aligned in an IAB node.

22, the IAB node can transmit a backhaul uplink subframe 2020b including reference signals R21 to R24 in the 2nd symbol, the 5th symbol, the 8th symbol, and the 11th symbol to the parent node. there is. Then, the parent node may receive the backhaul uplink subframe 2010a including the reference signals R21 to R24 in the 2nd symbol, the 5th symbol, the 8th symbol, and the 11th symbol from the IAB node. In this case, the child node may transmit a backhaul uplink subframe 2030a including reference signals R11 to R14 in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node.

Accordingly, the IAB node may receive the backhaul uplink subframe 2020a including the reference signals R11 to R14 in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the child node. In such a situation, the reference signals R11 to R14 carried in the backhaul uplink subframe 2020b transmitted by the IAB node to the parent node are reference signals carried in the backhaul uplink subframe 2020a received from the child node ( It can be seen that R21 to R24) do not match.

To solve this, the IAB node may maintain the reference signal settings of the reference signals R11 to R14 carried in the backhaul uplink subframe 2020b transmitted to the parent node, and the backhaul uplink subframe received from the child node. Reference signals R21 to R24 carried in 2020a may be moved.

23 is a flowchart illustrating a first embodiment of a method for aligning a reference signal of an IAB node.

Referring to FIG. 23 , the IAB node may transmit a backhaul uplink subframe that is an uplink signal including reference signals to a parent node. Then, the parent node may receive a backhaul uplink subframe, which is an uplink signal including reference signals, from the IAB node (S2301). As an example, the IAB node may transmit a backhaul uplink subframe including reference signals in the second symbol, the fifth symbol, the eighth symbol, and the eleventh symbol to the parent node.

Then, the parent node may receive a backhaul uplink subframe including reference signals in the 2nd symbol, the 5th symbol, the 8th symbol, and the 11th symbol from the IAB node. In this case, the child node may transmit a backhaul uplink subframe that is an uplink signal including reference signals to the IAB node. Accordingly, the IAB node may receive a backhaul uplink subframe that is an uplink signal including reference signals from the child node (S2302). In this case, as an example, the child node may transmit a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node.

Accordingly, the IAB node may receive a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the child node. On the other hand, the IAB node determines the interval between the start times of the reference signals for each of the reference signals carried in the backhaul uplink subframe transmitted to the parent node from the nearest reference signal carried in the backhaul uplink subframe received from the child node. The number of symbols in between can be calculated as a counting value.

At this time, the IAB node ignores any one reference signal carried in the backhaul uplink subframe transmitted to the parent node if the interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node is 3 or more. The interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node for the next reference signal may be calculated as a counting value by counting the number of symbols between the start times of the reference signals. .

Looking at this process with reference to FIG. 22, the IAB node receives the backhaul uplink subframe (R11) of the second symbol carried in the backhaul uplink subframe 2020b transmitted to the parent node from the child node ( 2020a), the number of symbols between the reference signal R21 and the third symbol, which is the nearest reference signal, may be counted. At this time, the IAB node can count 4, and it becomes 3 or more and can be ignored.

Next, the IAB node receives the closest reference in the backhaul uplink subframe 2020a received from the child node with respect to the reference signal R12 of the 5th symbol carried in the backhaul uplink subframe 2020b transmitted to the parent node. The number of symbols between the reference signal R22 and the reference signal R22 of the third symbol, which is a signal, may be counted, and in this case, the counting value may be 1. In addition, the IAB node receives the nearest reference signal carried in the backhaul uplink subframe 2020a received from the child node with respect to the reference signal R13 of the 8th symbol carried in the backhaul uplink subframe 2020b transmitted to the parent node. The number of symbols between the start times of the reference signal R23 of the 6th symbol may be counted, and in this case, the counting value may be 1.

In addition, the IAB node receives the nearest reference signal carried in the backhaul uplink subframe 2020a received from the child node with respect to the reference signal R14 of the 11th symbol carried in the backhaul uplink subframe 2020b transmitted to the parent node. The number of symbols between the start times of the reference signal R24 of the ninth symbol may be counted, and in this case, the counting value may be 1.

Again, referring to FIG. 23, the IAB node may determine the offset based on 1, which is the most repeated counting value among the counting values calculated through this process (S2303). Here, the offset may be a two-valued offset obtained by subtracting 1 from the original offset 3 of the backhaul uplink subframe 2020b.

Then, the IAB node may transmit a symbol movement indication message including an offset to the child node and indicating symbol movement (S2304). Then, the child node may receive a symbol movement indication message including the offset from the IAB node. Accordingly, the child node may move the reference signals in the backhaul uplink subframe transmitted to the IAB node to satisfy the offset in the symbol movement indication message received from the IAB node (S2305). Then, the child node may transmit a backhaul uplink subframe in which the reference signals are shifted to satisfy the offset in the symbol movement indication message received from the IAB node to the IAB node (S2306).

24 is a conceptual diagram illustrating a first embodiment of a method for aligning a reference signal of an IAB node.

Referring to FIG. 24 , the IAB node may transmit a backhaul uplink subframe that is an uplink signal including reference signals to a parent node. Then, the parent node may receive a backhaul uplink subframe that is an uplink signal including reference signals from the IAB node. As an example, the IAB node may transmit a backhaul uplink subframe including reference signals R11 to R14 in the 2nd symbol, the 5th symbol, the 8th symbol, and the 11th symbol to the parent node.

Then, the parent node may receive a backhaul uplink subframe including reference signals R11 to R14 in the 2nd symbol, the 5th symbol, the 8th symbol, and the 11th symbol from the IAB node. In this case, the child node may transmit to the IAB node the backhaul uplink subframe in which the reference signals are shifted to satisfy the offset in the symbol movement indication message received from the IAB node.

That is, the child node moves the reference signal R21 in the 3rd symbol to the 2nd symbol with respect to the backhaul uplink subframe 2030a of FIG. 22, and transfers the reference signal R22 in the 6th symbol to the 5th symbol. Backhaul including reference signals R21a to R24a in which the reference signal R23 in the 9th symbol is moved to the 8th symbol and the reference signal R24 in the 12th symbol is moved to the 11th symbol An uplink subframe 2030a may be generated and transmitted to the IAB node.

Then, the IAB node may receive a backhaul uplink subframe 2020a having reference signals R21a to R24a in the 2nd symbol, the 5th symbol, the 8th symbol, and the 11th symbol from the child node. Accordingly, some of the reference signals R12 to R14 among the reference signals R11 to R14 carried in the backhaul uplink subframe 2020b transmitted by the IAB node to the parent node are the backhaul uplink subframes received from the child node. Some of the reference signals R21a to R24a shown in 2020a may coincide with some reference signals R21a to R23a.

However, even when the child node moves the reference signals to satisfy the offset in the symbol movement indication message received from the IAB node, some of the reference signals may not match. That is, with respect to the reference signal in the second symbol of the backhaul uplink subframe transmitted by the IAB node to the parent node, there may not be a reference signal matching the backhaul uplink subframe received by the IAB node from the child node.

Also, with respect to the reference signal in the 11th symbol of the backhaul uplink subframe received by the IAB node to the child node, there may not be a matching reference signal in the backhaul uplink subframe transmitted by the IAB node to the parent node. In order to resolve such discrepancy, the IAB node may move the symbol of the backhaul uplink subframe transmitted to the parent node.

25 is a flowchart illustrating a second embodiment of a method for aligning a reference signal of an IAB node.

Referring to FIG. 25 , the IAB node may transmit a backhaul uplink subframe that is an uplink signal including reference signals to a parent node. Then, the parent node may receive a backhaul uplink subframe that is an uplink signal including reference signals from the IAB node ( S2501 ). As an example, the IAB node may transmit a backhaul uplink subframe including reference signals in the second symbol, the fifth symbol, the eighth symbol, and the eleventh symbol to the parent node.

Then, the parent node may receive a backhaul uplink subframe including reference signals in the 2nd symbol, the 5th symbol, the 8th symbol, and the 11th symbol from the IAB node. In this case, the child node may transmit a backhaul uplink subframe that is an uplink signal including reference signals to the IAB node. Accordingly, the IAB node may receive a backhaul uplink subframe that is an uplink signal including reference signals from the child node (S2502).

In this case, as an example, the child node may transmit a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node. Accordingly, the IAB node may receive a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the child node.

Meanwhile, the IAB node may calculate an offset for moving the reference signals carried in the backhaul uplink subframe transmitted to the parent node (S2503). As an example, the IAB node may calculate an offset to move the first reference signal from among the reference signals carried in the backhaul uplink subframe transmitted to the parent node to be located at the first symbol of the backhaul uplink subframe received from the child node. .

Thereafter, the IAB node may transmit a symbol movement permission request message including the offset to the parent node to the parent node in order to determine whether the reference signal can be moved according to the calculated offset (S2504). Accordingly, the parent node may receive a symbol movement permission request message including the offset from the IAB node. In addition, when symbol movement is possible, the parent node may transmit a symbol movement permission request response message to the IAB node to inform that symbol movement is possible (S2505).

Then, the IAB node may receive a symbol movement permission request response message from the parent node. Accordingly, the IAB node may generate a backhaul uplink subframe in which reference signals are moved according to the calculated offset as shown in FIG. 26 .

26 is a conceptual diagram in which an IAB node moves a reference signal of an uplink signal to be transmitted to a parent node.

Referring to FIG. 26 , the IAB node receives the first reference signal R11a among the reference signals carried in the backhaul uplink subframe 2020b transmitted to the parent node from the child node. It can be moved to be located at the first symbol. In addition, the IAB node may equally move the remaining reference signals R12a to R14a carried in the backhaul uplink subframe 2020b transmitted to the parent node.

For each of the reference signals carried in the backhaul uplink subframe 2020b transmitted to the parent node, the IAB node sets the interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node between the start times. The number of symbols can be calculated as a counting value. In this regard, the IAB node receives the closest reference in the backhaul uplink subframe 2020a received from the child node with respect to the reference signal R11a of the fourth symbol carried in the backhaul uplink subframe 2020b transmitted to the parent node. The number of symbols between the reference signal R21 of the third symbol that is a signal may be counted. In this case, the IAB node may count 2.

Next, the IAB node receives the closest reference carried in the backhaul uplink subframe 2020a received from the child node with respect to the reference signal R12a of the 7th symbol carried in the backhaul uplink subframe 2020b transmitted to the parent node. The number of symbols between the reference signal R22 and the reference signal R22 of the 6th symbol, which is a signal, may be counted, and the counting value may be 2. In addition, the IAB node receives the nearest reference signal carried in the backhaul uplink subframe 2020a received from the child node with respect to the reference signal R13a of the 10th symbol carried in the backhaul uplink subframe 2020b transmitted to the parent node. The number of symbols between the ninth symbol and the reference signal R23 may be counted, and in this case, the counting value may be 2.

In addition, the IAB node receives the nearest reference signal carried in the backhaul uplink subframe 2020a received from the child node with respect to the reference signal R14a of the 13th symbol carried in the backhaul uplink subframe 2020b transmitted to the parent node. The number of symbols between the twelfth symbol and the reference signal R24 may be counted, and in this case, the counting value may be 2.

Referring back to FIG. 25 , the IAB node may determine the offset based on 2, which is the most repeated counting value among the counting values calculated through this process (S2506). Here, the IAB node may determine the offset to be 0. In addition, the IAB node may transmit a symbol movement indication message including an offset to the child node and indicating symbol movement (S2507). Then, the child node may receive a symbol movement indication message including the offset from the IAB node.

Accordingly, the child node may move the reference signals in the backhaul uplink subframe transmitted to the IAB node to satisfy the offset in the symbol movement indication message received from the IAB node (S2508). Then, the child node may transmit a backhaul uplink subframe in which the reference signals are shifted to satisfy the offset in the symbol movement indication message received from the IAB node to the IAB node (S2506).

27 is a conceptual diagram illustrating a second embodiment of a method for aligning a reference signal of an IAB node.

Referring to FIG. 27, the IAB node moves the offset so that the first reference signal among the reference signals carried in the backhaul uplink subframe transmitted to the parent node is located at the first symbol of the backhaul uplink subframe received from the child node. can be calculated. Thereafter, the IAB node may receive a symbol movement permission request response message from the parent node by transmitting a symbol movement permission request message including the offset to the parent node in order to determine whether the reference signal can be moved according to the calculated offset.

Accordingly, the IAB node may generate the backhaul uplink subframe 2020b to be transmitted to the parent node to which the reference signals are moved according to the calculated offset. In addition, the IAB node counts the number of symbols for each of the reference signals carried in the backhaul uplink subframe transmitted to the parent node and the interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node. can be calculated as The IAB node may be determined as an offset based on the counting value most repeated among the calculated counting values, and may be determined as 0 here.

In addition, the IAB node may transmit a symbol movement indication message including an offset to the child node and indicating symbol movement. Then, the child node may receive a symbol movement indication message including the offset from the IAB node. Accordingly, the child node may shift the reference signals in the backhaul uplink subframe transmitted to the IAB node by the offset in the symbol movement indication message received from the IAB node. In addition, the child node may generate the backhaul uplink subframe 2030a in which the reference signals are moved to satisfy offset 0 in the symbol movement indication message received from the IAB node.

Thereafter, the child node may transmit to the IAB node the backhaul uplink subframe 2030a in which the reference signals are shifted to satisfy the offset in the symbol movement indication message received from the IAB node. The IAB node may receive the backhaul uplink subframe 2020a in which the reference signals from the child node are shifted to satisfy the offset in the symbol movement indication message received from the IAB node. In this situation, the reference signals R11a to R14a carried in the backhaul uplink subframe 2020b transmitted by the IAB node to the parent node are reference signals carried in the backhaul uplink subframe 2020a received from the child node ( It can be aligned with R21b~R24b) in the time domain.

On the other hand, when the IAB node can receive a signal from the parent node and receive a signal from the child node, the signal received from the parent node may interfere with the signal received from the child node. Accordingly, the IAB node may set the reference signal of the downlink reception signal of the MT of the IAB node and the uplink reception signal of the DU of the IAB node to have the same pattern in time and frequency axes.

28 is a conceptual diagram illustrating a second embodiment when reference signals are not aligned in an IAB node.

Referring to FIG. 28 , the parent node can transmit a backhaul downlink subframe 2810b including reference signals R31 to R34 in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node. there is. Then, the IAB node may receive a backhaul downlink subframe 2820c including reference signals R31 to R34 in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the parent node.

In this case, the child node may transmit a backhaul uplink subframe 2830a that is an uplink signal including reference signals to the IAB node. Accordingly, the IAB node may receive a backhaul uplink subframe 2820a that is an uplink signal including reference signals from the child node. In this case, as an example, the child node may transmit a backhaul uplink subframe including reference signals R41 to R44 in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node.

Accordingly, the IAB node may receive a backhaul uplink subframe including reference signals R41 to R44 in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the child node. In this situation, the reference signals R31 to R34 carried in the backhaul downlink subframe 2820c received by the IAB node from the parent node are reference signals carried in the backhaul uplink subframe 2820a received from the child node ( It can be seen that R41 to R44) do not match.

To solve this, the parent node may maintain the reference signal settings of the reference signals R31 to R34 carried in the backhaul downlink subframe 2810a transmitted to the IAB node, and the backhaul uplink subframe received from the child node. Reference signals R41 to R44 loaded on 2820a may be moved.

29 is a flowchart illustrating a third embodiment of a method for aligning a reference signal of an IAB node.

Referring to FIG. 29 , a parent node may transmit a backhaul downlink subframe, which is a downlink signal including reference signals, to an IAB node. Then, the IAB node may receive a backhaul downlink subframe that is a downlink signal including reference signals from the parent node (S2901). For example, the parent node may transmit a backhaul downlink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the child node. Then, the IAB node may receive a backhaul downlink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the parent node.

In this case, the child node may transmit a backhaul uplink subframe that is an uplink signal including reference signals to the IAB node. Accordingly, the IAB node may receive a backhaul uplink subframe that is an uplink signal including reference signals from the child node (S2902). In this case, as an example, the child node may transmit a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node. Accordingly, the IAB node may receive a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the child node.

On the other hand, the IAB node sets the interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node for each of the reference signals carried in the backhaul downlink subframe received from the parent node between symbol start times. It can be calculated as a counting value that counts the number.

At this time, the IAB node ignores any one reference signal carried in the backhaul downlink subframe received from the parent node if the interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node is 3 or more. The interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node for the next reference signal may be calculated as a counting value by counting the number of symbols between the start times of the reference signals. .

Looking at this process with reference to FIG. 28, the IAB node receives the backhaul uplink subframe from the child node with respect to the reference signal R31 of the third symbol carried in the backhaul downlink subframe 2820c received from the parent node 2820a), the number of symbols between the start times of the reference signal R41 of the third symbol, which is the nearest reference signal, may be counted.

In this case, the IAB node may count 1. Next, the IAB node receives the closest reference carried in the backhaul uplink subframe 2820a received from the child node with respect to the reference signal R32 of the 6th symbol carried in the backhaul downlink subframe 2820c received from the parent node. The number of symbols between the reference signal R42 and the reference signal R42 of the sixth symbol may be counted, and the counting value may be 1.

In addition, the IAB node receives the nearest reference signal carried in the backhaul uplink subframe 2820a received from the child node with respect to the reference signal R33 of the ninth symbol carried in the backhaul downlink subframe 2820c received from the parent node. The number of symbols between the ninth symbol and the reference signal R43 may be counted, and in this case, the counting value may be 1.

In addition, the IAB node receives the closest reference signal carried in the backhaul uplink subframe 2820a received from the child node with respect to the reference signal R34 of the 12th symbol carried in the backhaul uplink subframe 2820c received from the parent node. The number of symbols between the twelfth symbol and the reference signal R44 may be counted, and in this case, the counting value may be 1.

Referring again to FIG. 29 , the IAB node may determine the offset based on the most repeated counting value among the counting values calculated through this process ( S2903 ). Then, the IAB node may transmit a symbol movement indication message including an offset to the child node and indicating symbol movement (S2904).

Then, the child node may receive a symbol movement indication message including the offset from the IAB node. Accordingly, the child node may move the reference signals in the backhaul uplink subframe transmitted to the IAB node to satisfy the offset in the symbol movement indication message received from the IAB node (S2905). Then, the child node may transmit a backhaul uplink subframe in which the reference signals are shifted to satisfy the offset in the symbol movement indication message received from the IAB node to the IAB node (S2906).

30 is a conceptual diagram illustrating a third embodiment of a method for aligning a reference signal of an IAB node.

Referring to FIG. 30 , the parent node may transmit a backhaul downlink subframe 2810b that is a downlink signal including reference signals to the IAB node. Then, the IAB node may receive a backhaul downlink subframe 2820c that is a downlink signal including reference signals from the parent node. For example, the parent node may transmit a backhaul downlink subframe including reference signals R31 to R34 in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node.

Then, the IAB node may receive a backhaul downlink subframe including reference signals R31 to R34 in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the parent node. In this case, the child node may transmit a backhaul uplink subframe 2830a that satisfies the offset in the symbol movement indication message received from the IAB node to the IAB node.

That is, the child node moves the reference signal in the 3rd symbol to the 5th symbol, the reference signal in the 6th symbol to the 8th symbol with respect to the backhaul uplink subframe 2830a of FIG. 28, and the 9th symbol. The backhaul uplink subframe 2830a in which the reference signal in the symbol is moved to the 11th symbol and the reference signal is moved to the 14th symbol in the 12th symbol may be transmitted.

Then, the IAB node may receive a backhaul uplink subframe 2820a having reference signals R41a to R44a in the 5th symbol, the 8th symbol, the 11th symbol, and the 14th symbol from the child node. In this situation, the reference signals R31 to R34 carried in the backhaul downlink subframe 2820c received by the IAB node from the parent node are reference signals carried in the backhaul uplink subframe 2820a received from the child node ( R41a to R44a).

Meanwhile, the reference signal in the backhaul uplink subframe 2820a received by the IAB node from the child node as shown in FIG. 30 may be biased too far to the right, resulting in performance degradation. Accordingly, the IAB node may request the parent node through the uplink to pull the reference signal forward. When the IAB node receives an allow response to such a request through downlink control information, it can push the reference signal back to the child node by one symbol from the point in time negotiated with the parent node so that the two reference signals overlap.

31 is a flowchart illustrating a fourth embodiment of a method for aligning a reference signal of an IAB node.

Referring to FIG. 31 , a parent node may transmit a backhaul downlink subframe, which is a downlink signal including reference signals, to an IAB node. Then, the IAB node may receive a backhaul downlink subframe that is a downlink signal including reference signals from the parent node (S3101). As an example, the parent node may transmit a backhaul downlink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node. Then, the IAB node may receive a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the parent node. In this case, the child node may transmit a backhaul uplink subframe that is an uplink signal including reference signals to the IAB node.

Accordingly, the IAB node may receive a backhaul uplink subframe that is an uplink signal including reference signals from the child node (S3102). In this case, as an example, the child node may transmit a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol to the IAB node. Accordingly, the IAB node may receive a backhaul uplink subframe including reference signals in the 3rd symbol, the 6th symbol, the 9th symbol, and the 12th symbol from the child node.

Meanwhile, the IAB node may calculate an offset for moving the reference signals carried in the backhaul downlink subframe received from the parent node (S3103). As an example, the IAB node calculates an offset that moves the first reference signal from among the reference signals carried in the backhaul downlink subframe received from the parent node to be closer to the first reference signal of the backhaul uplink subframe received from the child node. and, as an example, offset 2 may be determined.

Thereafter, the IAB node may transmit a symbol movement request message including the offset to the parent node in order to determine whether the reference signal can be moved according to the calculated offset (S3104). Accordingly, the parent node may receive the symbol movement request message including the offset from the IAB node. In addition, when symbol movement is possible, the parent node may transmit a symbol movement request response message to the IAB node to inform that symbol movement is possible (S3105). Then, the IAB node may receive a symbol movement request response message from the parent node. Thereafter, the parent node may transmit the backhaul downlink subframe in which the reference signals are moved according to the offset to the IAB node. Accordingly, the IAB node may receive the backhaul downlink subframe in which the reference signals are moved according to the offset as shown in FIG. 32 from the parent node.

32 is a conceptual diagram when an IAB node receives a downlink signal to which a reference signal is moved from a parent node.

Referring to FIG. 32 , the parent node receives the first reference signal R31 from among the reference signals carried in the backhaul downlink subframe 2820c transmitted to the IAB node, the first reference signal of the backhaul uplink subframe ( It can be moved to approach R41). In addition, the parent node may move the remaining reference signals R32 to R34 in the same manner.

The IAB node determines the interval from the nearest reference signal carried in the backhaul uplink subframe received from the child node for each of the reference signals carried in the backhaul downlink subframe received to the parent node, the number of symbols between the start times of the reference signals. can be calculated as a counting value.

At this time, the IAB node ignores any one reference signal carried in the backhaul uplink subframe transmitted to the parent node if the interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node is 3 or more. The interval with the nearest reference signal carried in the backhaul uplink subframe received from the child node for the next reference signal may be calculated as a counting value by counting the number of symbols between the start times of the reference signals. .

In this regard, the IAB node has the closest reference carried in the backhaul uplink subframe 2820a received from the child node with respect to the reference signal R31a of the second symbol carried in the backhaul downlink subframe 2820c received from the parent node. A symbol between the start times of the reference signal R41 of the third symbol that is a signal may be counted. In this case, the IAB node may count 1. Next, the IAB node receives the closest reference carried in the backhaul uplink subframe 2820a received from the child node with respect to the reference signal R32a of the 5th symbol carried in the backhaul downlink subframe 2820c received from the parent node. The number of symbols between the reference signal R42 and the reference signal R42 of the sixth symbol may be counted, and the counting value may be 1.

In addition, the IAB node receives the nearest reference signal carried in the backhaul uplink subframe 2820a received from the child node with respect to the reference signal R33a of the 8th symbol carried in the backhaul downlink subframe 2820c received from the parent node. The number of symbols between the ninth symbol and the reference signal R43 may be counted, and in this case, the counting value may be 1. In addition, the IAB node receives the nearest reference signal carried in the backhaul uplink subframe 2820a received from the child node with respect to the reference signal R34a of the 11th symbol carried in the backhaul downlink subframe 2820c received from the parent node. The number of symbols between the twelfth symbol and the reference signal R44 may be counted, and in this case, the counting value may be 1.

Referring again to FIG. 31 , the IAB node may determine the offset based on the most repeated counting value among the counting values calculated through this process ( S3106 ). Here, the IAB node may determine the offset to be 4. In addition, the IAB node may transmit a symbol movement indication message including an offset to the child node and indicating symbol movement (S3107).

Then, the child node may receive a symbol movement indication message including the offset from the IAB node. Accordingly, the child node may move the reference signals in the backhaul uplink subframe transmitted to the IAB node to satisfy the offset in the symbol movement indication message received from the IAB node (S3108). Then, the child node may transmit a backhaul uplink subframe in which the reference signals are moved to satisfy the offset in the symbol movement indication message received from the IAB node to the IAB node (S3109).

33 is a conceptual diagram illustrating a fourth embodiment of a method for aligning a reference signal of an IAB node.

Referring to FIG. 33 , the parent node may transmit a backhaul downlink subframe, which is a downlink signal including reference signals, to the IAB node. In this case, the IAB node calculates an offset that moves the first reference signal from among the reference signals carried in the backhaul downlink subframe received from the parent node to approximate the first reference signal of the backhaul uplink subframe received from the child node. there is. Here, the offset may be 2.

Thereafter, the IAB node may transmit a symbol movement request message including the offset to the parent node to determine whether the reference signal can be moved according to the calculated offset. Accordingly, the parent node may receive the symbol movement request message including the offset from the IAB node. In addition, when symbol movement is possible, the parent node may transmit a symbol movement request response message to the IAB node to inform that symbol movement is possible.

Then, the IAB node may receive a symbol movement request response message from the parent node. Thereafter, the parent node may generate a backhaul downlink subframe 2810b in which reference signals are moved according to the offset and transmit it to the IAB node. Accordingly, the IAB node may receive the backhaul downlink subframe 2820c in which the reference signals are moved according to the offset from the parent node.

Meanwhile, in the IAB node, for each of the reference signals R31a to R34a carried in the backhaul uplink subframe to be received from the parent node, the interval from the nearest reference signal carried in the backhaul uplink subframe to be received from the child node may be calculated as a counting value obtained by counting the number of symbols between start times of reference signals. At this time, in the IAB node, with respect to any one reference signal carried in the backhaul uplink subframe transmitted to the parent node, the interval between the start times of the nearest reference signal carried in the backhaul uplink subframe received from the child node is 3 or more This can be ignored, and the interval between the next reference signal and the nearest reference signal carried in the backhaul uplink subframe received from the child node can be calculated as a counting value obtained by counting the number of symbols between the reference signals. The IAB node may determine the offset based on the counting value most repeated among the calculated counting values. Here, the offset may be 4.

In addition, the IAB node may transmit a symbol movement indication message including an offset to the child node and indicating symbol movement. Then, the child node may receive a symbol movement indication message including the offset from the IAB node. Accordingly, the child node may move the reference signals in the backhaul uplink subframe transmitted to the IAB node to satisfy the offset in the symbol movement indication message received from the IAB node.

In addition, the child node may generate a backhaul uplink subframe 2830a including the reference signals R41a to R44a shifted to satisfy the offset in the symbol movement indication message received from the IAB node. Thereafter, the child node may transmit the backhaul uplink subframe 2830a including the reference signals R41a to R44a shifted to satisfy the offset in the symbol movement indication message received from the IAB node to the IAB node.

The IAB node may receive the backhaul uplink subframe 2820a in which the reference signals R41a to R44a from the child node are shifted to satisfy the offset in the symbol movement indication message received from the IAB node. In this situation, the reference signals R31a to R34a carried in the backhaul uplink subframe 2820b transmitted by the IAB node to the parent node are reference signals carried in the backhaul uplink subframe 2820a received from the child node ( R41a to R44a) may be identical.

The methods according to the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. Examples of computer-readable media may include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions may include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as at least one software module to perform the operations of the present invention, and vice versa.

In addition, the above-described method or apparatus may be implemented by combining all or part of its configuration or function, or may be implemented separately. Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that it can be done.

Claims (15)

A method of operating an integrated access and backhaul (IAB) node of a communication system, comprising:
measuring a power difference between the first signal received from the first node and the second signal received from the second node;
controlling each transmit power of the first node and the second node based on the power difference;
generating scheduling information for allowing the first node and the second node to simultaneously transmit signals;
transmitting the scheduling information to the first node and the second node; and
and receiving signals simultaneously transmitted according to the scheduling information using the transmission power from the first node and the second node. The method according to claim 1,
The step of controlling the transmission power,
determining whether the power difference exceeds a first threshold;
recognizing first headroom information of the first node and second headroom information of the second node when the power difference exceeds the first threshold value;
determining the transmit power of the first node based on the first headroom information and determining the transmit power of the second node based on the second headroom information; and
Comprising the step of transmitting information of the determined transmission power to each of the first node and the second node, the operating method of the IAB node. 3. The method according to claim 2,
The step of controlling the transmission power,
determining whether the power difference exceeds a second threshold; and
When the power difference exceeds a second threshold, switching the transmission scheme of the first node and the transmission scheme of the second node from a non-time division multiplexing (TDM) scheme to a TDM scheme, IAB How the node works. The method according to claim 1,
The step of controlling the transmission power,
determining whether the power difference exceeds a first threshold;
transmitting a request signal instructing adjustment to a first power adjustment range and a transmission power within the first power adjustment range to the first node when the power difference exceeds the first threshold value; and
and receiving a response signal including information indicating that the transmit power of the first node is adjusted to the transmit power within the first power adjustment range. The method according to claim 1,
The step of controlling the transmission power,
determining whether the power difference exceeds a first threshold;
transmitting a request signal of a second power adjustment range to the first node when the power difference exceeds the first threshold;
receiving a response signal including the second power adjustment range from the first node;
checking the second power adjustment range in the response signal; and
Selecting a transmission power from the checked second power adjustment range and transmitting a signal instructing adjustment to the selected transmission power to the first node, the operating method of the IAB node. A method of operating an integrated access and backhaul (IAB) node of a communication system, comprising:
determining a downlink minimum power of a downlink signal transmitted to a child node;
calculating uplink available power based on the downlink minimum power;
informing a parent node of information on the uplink available power;
receiving information on transmit power selected within the uplink available power from the parent node; and
and transmitting an uplink signal to the parent node by using the transmission power selected by the parent node. 7. The method of claim 6,
The step of determining the downlink minimum power comprises:
receiving a sounding reference signal from the child node; and
The method of operating an IAB node comprising determining the downlink minimum power based on the received signal strength of the sounding reference signal. 7. The method of claim 6,
The step of determining the downlink minimum power comprises:
transmitting a downlink reference signal to the child node;
receiving received signal strength information of the downlink reference signal from the child node; and
The method of operating an IAB node comprising determining the downlink minimum power based on the received signal strength information. 8. The method of claim 7,
In the calculating of the uplink available power, the uplink available power is calculated by subtracting the downlink minimum power from the uplink maximum power that is the maximum power usable for the uplink. . A method of operating an IAB node of a communication system, comprising:
determining a first time based on a round trip delay time of the first node;
A second time for making the start time of the symbols of the first uplink signal transmitted from the first time to the first node coincide with the start time of the symbols of the second uplink signal received from the second node in the time domain calculating ;
transmitting the calculated second time information to the second node; and
and receiving the second uplink signal from the second node when the second time is added to a timing at which the first node receives the first uplink signal, wherein the second time is a symbol The method is calculated by subtracting a residual value obtained by dividing the first time by the symbol length from the length, and the second uplink signal is transmitted based on the second time. 11. The method of claim 10,
The method further comprising: transmitting the first uplink signal to the first node at a time point obtained by subtracting the first time from the timing at which the first node receives the first uplink signal;
In the symbols at which the first uplink signal is transmitted, a start time of at least one symbol coincides with a reception time of the second uplink signal. 12. The method of claim 11,
checking first positions of first reference signals included in the first uplink signal and second positions of second reference signals included in the second uplink signal;
calculating a first offset of the second reference signals based on the first positions and the second positions;
transmitting the calculated first offset information to the second node; and
Receiving a third uplink signal including third reference signals arranged according to the first offset from the second node,
and a portion of the first positions and a portion of the third positions of the third reference signals arranged according to the first offset are aligned in the time domain. 13. The method of claim 12,
Calculating the first offset comprises:
calculating counting values by counting the number of symbols disposed between a symbol start time of each of the first reference signals and a symbol start time of a second reference signal closest to each of the first reference signals; and
Comprising the step of determining a counting value that is most repeated in the counting values as the first offset, the operating method of the IAB node. 11. The method of claim 10,
The information of the second time is transmitted through downlink control information or MAC (medium access control) CE (control element), the operation method of the IAB node. 11. The method of claim 10,
The operation method of the IAB node,
receiving a first downlink signal from the first node;
determining a second offset such that a position of a first reference signal in fourth reference signals included in the first downlink signal coincides with a start time of the second uplink signal;
transmitting the information of the second offset to the first node;
receiving a second downlink signal including fourth reference signals arranged according to the second offset from the first node;
checking fourth positions of fourth reference signals included in the second downlink signal and second positions of second reference signals included in the second uplink signal;
calculating a third offset of the second reference signals included in the second uplink signal based on the second positions and the fourth positions;
transmitting the calculated third offset information to the second node; and
Receiving a fourth uplink signal including fifth reference signals arranged according to the third offset from the second node,
and a portion of the fourth positions of the fourth reference signals and a portion of the fifth positions of the fifth reference signals are aligned in the time domain.

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