Method and apparatus for controlling power of IAB node in wireless communication system

The disclosure relates to a communication technique for convergence between an IoT technology and a 5G communication system for supporting a higher data transmission rate beyond a 4G system, and a system thereof. The disclosure may be applied to intelligence services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail businesses, security and safety related services, etc.) according to a 5G communication system and an IoT related technology. In addition, the disclosure provides a method and an apparatus for controlling power of an IAB node in a wireless communication system.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2020-0130324, filed on Oct. 8, 2020, in the Korean Intellectual Property Office, the disclosure of which is herein incorporated by reference in its entirety.

BACKGROUND

The disclosure relates to a method and an apparatus for controlling power of an integrated access and backhaul (IAB) node in a wireless communication system.

2. Description of Related Art

As coverage is limited due to attenuation of a propagation path in a super-high frequency band (a band of 6 GHz or greater or an mmWave band) which can be used in the 5G system, research into an integrated access and backhaul (IAB) technology of transmitting or receiving backhaul data to or from a base station and finally transmitting or receiving access data to or from a terminal through multiple relays, by using a broadband radio frequency resource, has been conducted.

SUMMARY

In the 5G system, coverage may be limited due to attenuation of a propagation path while a base station transmits or receives data to or from a terminal in a band of 6 GHz or greater, specifically, in an mmWave band. Problems caused by the limitation of coverage may be resolved by closely arranging multiple relays on a propagation path between the base station and the terminal, but there may be a serious cost problem for installing an optical cable for backhaul connection between the relays.

Accordingly, instead of installing the optical cable between the relays, broadband radio frequency resources available in mmWave may be used to transmit or receive backhaul data between the relays, whereby the cost problem of installing the optical cable can be solved and the mmWave band can be more efficiently used. A technology of transmitting or receiving backhaul data to or from a base station by using mmWave and finally transmitting or receiving access data to or from a terminal through multiple relays is referred to as integrated access and backhaul (IAB), and a relay node for transmitting or receiving data to or from the base station via wireless backhaul is referred to as an IAB node. When the IAB node transmits or receives the backhaul data, data needs to be received from the base station and access data needs to be transmitted to the terminal by using the same frequency band, and due to characteristics of the IAB node of receiving the access data from the terminal and transmitting the backhaul data to the base station, the IAB node has unidirectional transmission/reception characteristics at an instant.

Accordingly, as a method for reducing transmission/reception delay caused by the unidirectional transmission/reception characteristics of the IAB node, frequency domain multiplexing (FDM) or spatial domain multiplexing (SDM) may be performed on backhaul data (downlink data received by the IAB node from a parent IAB node and uplink data received by the IAB node from a child IAB node) and access data (uplink data received by the IAB node from the terminal) from the terminal when the IAB node receives data. In this case, when the IAB node receives the data by including only one radio frequency (RF), access data reception is difficult when adaptive gain control (AGC) or analog-to-digital converter (ADC) is performed due to a power difference between backhaul reception and the access reception. Accordingly, an embodiment of the disclosure provides a power control scheme required when receiving backhaul downlink data.

In addition, when the IAB node transmits the data, FDM/SDM may be performed on backhaul data (uplink data from the IAB node to the parent IAB node and downlink data from the IAB node to the child IAB node) and access data (downlink data from the IAB node to the terminal) to the terminal. Here, when the IAB node transmits the data by including only one RF, power of the IAB node may be limited, and in this case, operations of the IAB node need to be defined. Accordingly, an embodiment of the disclosure provides an operation of an IAB node during the transmission power limitation above.

In addition, when the IAB node has bidirectional transmission and reception characteristics and transmits or receives data, FDM/SDM may be simultaneously performed on signals (downlink data/control signal from a DU of a parent IAB node to an MT of the IAB node and uplink data/control signal from the MT of the IAB node to the DU of the parent IAB node) of a parent backhaul link and a signal (uplink data/control signal from an MT of a child IAB node to a DU of the IAB node and downlink data/control signal from the DU of the IAB node to the MT of the child IAB node) of a child backhaul link or a signal (uplink data/control signal from the terminal to the IAB node and downlink signal from the IAB node to the terminal) of an access link with the terminal. In this case, when the MT and the DU of the IAB node simultaneously perform transmission and reception, a method for controlling power by the IAB node is required to reduce an effect of an interference signal to a reception signal. Accordingly, an embodiment of the disclosure provides a method and an apparatus for controlling power of an IAB node to reduce self-interference when IAB performs bidirectional transmission and reception as described above.

An embodiment of the disclosure provides a scheme of controlling power required to receive backhaul downlink data. In addition, an embodiment of the disclosure provides an operation of an IAB node when transmission power is limited. In addition, an embodiment of the disclosure provides a power control operation of an IAB node for reduction of self-interference when an IAB node performs bidirectional transmission and reception.

In accordance with an aspect of the disclosure, a method for an integrated access and backhaul (IAB) node in a communication system is provided. The method comprises identifying whether a transmission and a reception are performed simultaneously; identifying a maximum power associated with a simultaneous transmission and reception of the IAB node, in case that the transmission and the reception are performed simultaneously; determining a power for the transmission based on the maximum power; and transmitting a signal based on the determined power for the transmission.

In accordance with another aspect of the disclosure, an integrated access and backhaul (IAB) node in a communication system is provided. The IAB node comprises a transceiver; and a controller configured to: identify whether a transmission and a reception are performed simultaneously; identify a maximum power associated with a simultaneous transmission and reception of the IAB node, in case that the transmission and the reception are performed simultaneously; determine a power for the transmission based on the maximum power; and transmit a signal based on the determined power for the transmission.

DETAILED DESCRIPTION

Wireless communication systems have expanded beyond the original role of providing a voice-oriented service and have evolved into wideband wireless communication systems that provide a high-speed and high-quality packet data service according to, for example, communication standards such as high-speed packet access (HSPA), long-term evolution (LTE or evolved universal terrestrial radio access (E-UTRA)), LTE-Advanced (LTE-A), and LTE-Pro of 3GPP, high-rate packet data (HRPD) and a ultra-mobile broadband (UMB) of 3GPP2, and 802.16e of IEEE.

As a representative example of the broadband wireless communication systems, in the LTE system, an orthogonal frequency-division multiplexing (OFDM) scheme has been adopted for a downlink (DL), and a single carrier frequency division multiple access (SC-FDMA) scheme have been adopted for an uplink (UL). The uplink indicates a radio link through which data or a control signal is transmitted from a terminal (a user equipment (UE) or a mobile station (MS)) to a base station (an eNode B, or a base station (BS)), and the downlink indicates a radio link through which data or a control signal is transmitted from a base station to a terminal. In the above-mentioned multiple-access scheme, normally, data or control information is distinguished according to a user by assigning or managing time-frequency resources for carrying data or control information of each user, wherein the time-frequency resources do not overlap, that is, orthogonality is established.

A future communication system subsequent to the LTE, that is, a 5G (or NR) communication system, has to be able to freely reflect various requirements from a user, a service provider, and the like, and thus service satisfying all of the various requirements needs to be supported. The services considered for the 5G communication system include enhanced mobile broadband (eMBB), massive machine-type communication (mMTC), ultra-reliable low-latency communication (URLLC), etc.

eMBB aims to provide a data rate superior to the data rate supported by the existing LTE, LTE-A, or LTE-Pro. For example, in the 5G communication system, eMBB may be able to provide a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the viewpoint of one base station. In addition, the 5G communication system may be able to provide not only the peak data rate but also an increased user-perceived terminal data rate. In order to satisfy such requirements, improvement of various transmitting and receiving technologies including a further improved multi-input multi-output (MIMO) transmission technology may be required. In addition, a signal is transmitted using a transmission bandwidth of up to 20 MHz in the 2 GHz band used by the current LTE, but the 5G communication system uses a bandwidth wider than 20 MHz in the frequency band of 3 to 6 GHz or 6 GHz or higher, thereby satisfying the data rate required in the 5G communication system.

In addition, mMTC is being considered to support application services such as the Internet of Things (IoT) in the 5G communication system. mMTC may be required to support access by a large number of terminals in a cell, coverage enhancement of a terminal, improved battery time, and cost reduction of a terminal in order to efficiently provide the IoT. The IoT needs to be able to support a large number of terminals (for example, 1,000,000 terminals/km2) in a cell because it is attached to various sensors and devices to provide communication functions. Furthermore, a terminal supporting mMTC is more likely to be located in a shaded area that is not covered by a cell due to the nature of services, such as a basement of a building, and thus the terminal requires wider coverage than other services provided in the 5G communication system. The terminal supporting mMTC needs to be configured as an inexpensive terminal and may require a very long battery lifetime, such as 10 to 15 years, because it is difficult to frequently replace the battery of the terminal.

Finally, URLLC is a cellular-based wireless communication service used for mission-critical purposes. For example, services used for remote control for a robot or machinery, industrial automation, an unmanned aerial vehicle, remote health care, an emergency alert, or the like may be considered. Accordingly, the communication provided by URLLC may provide very low latency and very high reliability. For example, a service that supports URLLC needs to satisfy air interface latency of less than 0.5 milliseconds, and may also have requirements of a packet error rate of 10-5% or lower. Therefore, for the service that supports URLLC, the 5G system needs to provide a transmission time interval (TTI) smaller than those of other services, and design matters for allocating wide resources in the frequency band in order to secure reliability of the communication link may also arise.

The above-described three services considered in the 5G communication system, that is, eMBB, URLLC, and mMTC, may be multiplexed and transmitted in a single system. Here, in order to satisfy the different requirements of each of the services, different transmission or reception techniques and different transmission and reception parameters may be used for the services.

In the 5G system, coverage may be limited due to attenuation of a propagation path while a base station transmits or receives data to or from a terminal in a band of 6 GHz or greater, specifically, in an mmWave band. Problems caused by the limitation of coverage may be resolved by closely arranging multiple relays on a propagation path between the base station and the terminal, but there may be a serious cost problem for installing an optical cable for backhaul connection between the relays.

Accordingly, instead of installing the optical cable between the relays, broadband radio frequency resources available in mmWave may be used to transmit or receive backhaul data between the relays, whereby the cost problem of installing the optical cable can be solved and the mmWave band can be more efficiently used. A technology of transmitting or receiving backhaul data to or from a base station by using mmWave and finally transmitting or receiving access data to or from a terminal through multiple relays is referred to as integrated access and backhaul (IAB), and a relay node for transmitting or receiving data to or from the base station via wireless backhaul is referred to as an IAB node. When the IAB node transmits or receives the backhaul data, data needs to be received from the base station and access data needs to be transmitted to the terminal by using the same frequency band, and due to characteristics of the IAB node of receiving the access data from the terminal and transmitting the backhaul data to the base station, the IAB node has unidirectional transmission/reception characteristics at an instant.

Accordingly, as a method for reducing transmission/reception delay caused by the unidirectional transmission/reception characteristics of the IAB node, frequency domain multiplexing (FDM) or spatial domain multiplexing (SDM) may be performed on backhaul data (downlink data received by the IAB node from a parent IAB node and uplink data received by the IAB node from a child IAB node) and access data (uplink data received by the IAB node from the terminal) from the terminal when the IAB node receives data. In this case, when the IAB node receives the data by including only one radio frequency (RF), access data reception is difficult when adaptive gain control (AGC) or analog-to-digital converter (ADC) is performed due to a power difference between backhaul reception and the access reception. Accordingly, an embodiment of the disclosure provides a power control scheme required when receiving backhaul downlink data.

In addition, when the IAB node transmits the data, FDM/SDM may be performed on backhaul data (uplink data from the IAB node to the parent IAB node and downlink data from the IAB node to the child IAB node) and access data (downlink data from the IAB node to the terminal) to the terminal. Here, when the IAB node transmits the data by including only one RF, power of the IAB node may be limited, and in this case, operations of the IAB node needs to be defined. Accordingly, an embodiment of the disclosure provides an operation of an IAB node during the transmission power limitation above.

In addition, when the IAB node has bidirectional transmission and reception characteristics and transmits or receives data, FDM/SDM may be simultaneously performed on signals (downlink data/control signal from a DU of a parent IAB node to an MT of the IAB node and uplink data/control signal from the MT of the IAB node to the DU of the parent IAB node) of a parent backhaul link and a signal (uplink data/control signal from an MT of a child IAB node to a DU of the IAB node and downlink data/control signal from the DU of the IAB node to the MT of the child IAB node) of a child backhaul link or a signal (uplink data/control signal from the terminal to the IAB node and downlink signal from the IAB node to the terminal) of an access link with the terminal. In this case, when the MT and the DU of the IAB node simultaneously perform transmission and reception, a method for controlling power by the IAB node is required to reduce an effect of an interference signal to a reception signal. Accordingly, an embodiment of the disclosure provides a method and an apparatus for controlling power of an IAB node to reduce self-interference when IAB performs bidirectional transmission and reception as described above.

First, a communication system in which IAB is managed is described with reference toFIG.1.

FIG.1illustrates a communication system in which IAB is managed according to an embodiment of the disclosure.

InFIG.1, a gNB101is a general base station, and is called a base station or a donor base station in the disclosure. An IAB node1111and an IAB node2121are IAB nodes transmitting or receiving a backhaul link in an mmWave band. A terminal1102transmits or receive access data to or from the gNB101through an access link103. The IAB node1111transmits or receive backhaul data to or from the gNB101through a backhaul link104. A terminal2112transmits or receives access data to or from the IAB node1111through an access link113. The IAB node2121transmits or receives backhaul data to or from the IAB node1111through a backhaul link114. Accordingly, the IAB node1111is an upper IAB node of IAB node2121and is called a parent IAB node, and the IAB node2121is a lower IAB node of IAB node1111and is called a child IAB node. A terminal3122transmits or receives access data to or from the IAB node2121through an access link123.

Next, multiplexing of a backhaul link between the base station and the IAB node or between the IAB node and the IAB node and an access link between the base station and the terminal or between the IAB node and the terminal in an IAB technology provided in the disclosure is described in detail with reference toFIGS.2,3, and4.

FIG.2illustrates time-division, frequency-division, and spatial-division multiplexing of an access link and a backhaul link in IAB according to an embodiment of the disclosure.

The top ofFIG.2illustrates time-division multiplexing of an access link and a backhaul link in the IAB. The middle ofFIG.2illustrates frequency-division multiplexing of an access link and a backhaul link in IAB. The bottom ofFIG.2illustrates spatial-division multiplexing of an access link and a backhaul link in IAB.

The top ofFIG.2illustrates time-division multiplexing (TDM) of a backhaul link203between the base station and the IAB node or between the IAB node and the IAB node and an access link202between the base station and the terminal or between the IAB node and the terminal in a wireless resource201. Accordingly, no data is transmitted or received between the base station and the IABs in the time division in which the base station or the IAB node transmits or receives data to or from the terminal, and the base station or the IAB node transmits or receives no data to the terminal in the time division in which data transmission or reception is performed between the base station and the IAB nodes.

The middle ofFIG.2illustrates frequency-division multiplexing (FDM) of a backhaul link213between the base station and the IAB node or between the IAB node and the IAB node and an access link212between the base station and the terminal or between the IAB node and the terminal in a wireless resource211. Accordingly, it is possible to perform data transmission or reception between the base station and the IAB nodes in the time division in which the base station or the IAB node transmits or receives data to the terminal. If an IAB node has unidirectional transmission or reception capability (for example, when information relating to capability indicating that a DU and an MT within an IAB node cannot simultaneously perform transmission and reception is indicated to a parent IAB node or a donor base station by the IAB node), only data transmission in the same direction is allowed. That is, in the time division in which one IAB node receives data from the terminal, the IAB node can only receive backhaul data from another IAB node or the base station.

In addition, in the time division in which one IAB node transmits data to the terminal, the IAB node can only transmit backhaul data to another IAB node or the base station. If the IAB node has bidirectional transmission or reception capability (for example, information relating to capability indicating that a DU and an MT within an IAB node can simultaneously perform transmission and reception is indicated to a parent IAB node or a donor base station by the IAB node), bidirectional data transmission or reception is possible. That is, in the time division in which one IAB node receives data from the terminal, the IAB node can transmit backhaul data to another IAB node or the base station. In addition, in the time vision in which one IAB node transmits data to the terminal, the IAB node can receive backhaul data from another IAB node or the base station.

The bottom ofFIG.2illustrates spatial-division multiplexing (SDM) of a backhaul link223between the base station and the IAB node or between the IAB node and the IAB node and an access link222between the base station and the terminal or between the IAB node and the terminal in a wireless resource221. Accordingly, it is possible to perform data transmission or reception between the base station and the IAB nodes in the time division in which the base station or the IAB node transmits or receives data to the terminal. However, if an IAB node has unidirectional transmission or reception capability (for example, when information relating to capability indicating that a DU and an MT within an IAB node cannot simultaneously perform transmission and reception is indicated to a parent IAB node or a donor base station by the IAB node), only data transmission in the same direction is allowed. That is, in the time division in which one IAB node receives data from the terminal, the IAB node can only receive backhaul data from another IAB node or the base station.

In addition, in the time division in which one IAB node transmits data to the terminal, the IAB node can only transmit backhaul data to another IAB node or the base station. If the IAB node has bidirectional transmission or reception capability (for example, information relating to capability indicating that a DU and an MT within an IAB node can simultaneously perform transmission and reception is indicated to a parent IAB node or a donor base station by the IAB node), bidirectional data transmission or reception is possible. That is, in the time division in which one IAB node receives data from the terminal, the IAB node can transmit backhaul data to another IAB node or the base station. In addition, in the time vision in which one IAB node transmits data to the terminal, the IAB node can receive backhaul data from another IAB node or the base station.

When the IAB node performs initial access, a multiplexing technique to be used among the TDM, FDM, and SDM, whether unidirectional transmission or reception is possible, or whether simultaneous bi-direction transmission and reception is possible may be received through an RRC signal or system information from an accessing base station or upper IAB nodes. Alternatively, when the IAB node transmits information on the capability to the upper IAB node or the base station through the RRC signal, the IAB node may add the multiplexing technique or capability information on unidirectional/bidirectional transmission or reception, and may also receive related configuration information from the accessing base station or upper IAB nodes through the system information or the RRC signal, or may also receive related configuration information from the base station or upper IAB nodes through a backhaul link.

FIG.3illustrates time-division multiplexing of an access link and a backhaul link in IAB according to an embodiment of the disclosure.

The top ofFIG.3illustrates that an IAB node302communicates with a parent node301, a child IAB node303, a terminal304. Each link between nodes is described in more detail below. The parent node301transmits a backhaul downlink signal to the IAB node302through a backhaul downlink (LP,DL), and the IAB node302transmits a backhaul uplink signal to the parent node301through a backhaul uplink (LP,UL). The IAB node302transmits an access downlink signal to the terminal304through an access downlink (LA,DL), and the terminal304transmits an access uplink signal to the IAB node302through an access uplink (LA,UL). The IAB node302transmits a backhaul downlink signal to the child node303through a backhaul downlink (LC,DL), and the child IAB node303transmits a backhaul uplink signal to the IAB node302through a backhaul uplink (LC,UL). In the above notation, P indicates, as a backhaul link with a parent node, a parent link in the perspective of one IAB node302. A indicates an access link with a terminal, and C indicates a backhaul link with a child node. Links of A and C may be included in a child link in the perspective of one IAB node302.

These link relationships are described with reference to the IAB node302, and in the perspective of the child IAB node303, the IAB node302corresponds to a parent node, and there may be another child IAB node as a lower node of the child IAB node303. In addition, in the perspective of the parent node301, the IAB node302corresponds to a child node, and there may be another IAB parent node as an upper node of the parent node301.

The signal described above includes data and control information, a channel for transmitting data and control information, a reference signal required to decode data and control information, or reference signals for identifying channel information.

The bottom ofFIG.3illustrates multiplexing of the links in all divisions. The bottom ofFIG.3illustrates multiplexing of a backhaul downlink (LP,DL)311, a backhaul downlink (LC,DL)313, an access downlink (LA,DL)316, an access uplink (LA,UL)315, a backhaul uplink (LC,UL)314, and a backhaul uplink (LP,UL)312in a time sequence. The temporal order between the links illustrated inFIG.3is just an example, and any other temporal order may be applied without problems.

InFIG.3, the links are multiplexed in the time division according to a time sequence, and thus the multiplexing shown inFIG.3corresponds to a multiplexing scheme consuming the longest time to transmit a signal from the parent node301to the child IAB node303through the IAB node302, and also transmit the signal to the terminal. Accordingly, in order to reduce latency when transmitting the signal from the parent node301to the final terminal, a method for multiplexing the backhaul link and the backhaul link or the backhaul link and the access links in the frequency division or the spatial division and transmitting the same at the same time may be considered.

FIG.4illustrates the first example of frequency-division and spatial-division multiplexing of an access link and a backhaul link in IAB according to an embodiment of the disclosure.

A method for reduction of latency by multiplexing the backhaul link and the backhaul link or the backhaul link and the access links in the frequency division or the spatial division is described with reference toFIG.4.

The top ofFIG.4illustrates that an IAB node402communicates with a parent node401, a child IAB node403, and a terminal404. Each link between nodes is described in more detail below. The parent node401transmits a backhaul downlink signal to the IAB node402through a backhaul downlink (LP,DL), and the IAB node402transmits a backhaul uplink signal to the parent node401through a backhaul uplink (LP,UL). The IAB node402transmits an access downlink signal to the terminal404through an access downlink (LA,DL), and the terminal404transmits an access uplink signal to the IAB node402through an access uplink (LA,UL). The IAB node402transmits a backhaul downlink signal to the child IAB node403through a backhaul downlink (LC,DL), and the child IAB node403transmits a backhaul uplink signal to the IAB node402through a backhaul uplink (LC,UL). In the above notation, P indicates a backhaul link with a parent node, A indicates an access link with a terminal, and C indicates a backhaul link with a child node.

These link relationships are described with reference to the IAB node402, and in the perspective of the child IAB node403, the IAB node402corresponds to a parent node, and there may be another child IAB node as a lower node of the child IAB node403. In addition, in the perspective of the parent node401, the IAB node402corresponds to a child node, and there may be another IAB parent node as an upper node of the parent node401.

The signal described above includes data and control information, a channel for transmitting data and control information, a reference signal required to decode data and control information, or reference signals for identifying channel information.

Next, a scheme of multiplexing the above-described links in the frequency division and the spatial division is described with reference to the bottom ofFIG.4.

When an IAB node has a unidirectional transmission or reception feature at a moment, signals allowing frequency-division multiplexing or spatial-division multiplexing are restricted. In a case of considering the unidirectional transmission or reception feature of the IAB node402, a link which can be multiplexed in the time division in which the IAB node can perform transmission includes a backhaul uplink (LP,UL)412, a backhaul downlink (LC,DL)413, and an access downlink (LA,DL)416. Accordingly, when the links are multiplexed in the frequency division or the spatial division, the IAB node402may transmit all the links in the same time division as shown in421. In addition, a link which can be multiplexed in the time division in which the IAB node can perform reception includes a backhaul downlink (LP,DL)411, a backhaul uplink (LC,UL)414, and an access uplink (LA,UL)415. Accordingly, when the links are multiplexed in the frequency division or the spatial division, the IAB node402may receive all the links in the same time division as shown in422.

Multiplexing of the links provided inFIG.4is an example, and it is also possible to multiplex only two links among three links multiplexed in the frequency or spatial division.

FIG.5illustrates the second example of frequency-division and spatial-division multiplexing of an access link and a backhaul link in IAB according to an embodiment of the disclosure.

Specifically, a case in which an IAB node has bidirectional transmission or reception feature, unlike the case inFIG.4, is described.

A method for reduction of latency by multiplexing the backhaul link and the backhaul link or the backhaul link and the access links in the frequency division or the spatial division is described with reference toFIG.5.

The top ofFIG.5illustrates that an IAB node502communicates with a parent node501, a child IAB node503, and a terminal504. Each link between nodes is described in more detail below. The parent node501transmits a backhaul downlink signal to the IAB node502through a backhaul downlink (LP,DL), and the IAB node502transmits a backhaul uplink signal to the parent node501through a backhaul uplink (LP,UL). The IAB node502transmits an access downlink signal to the terminal504through an access downlink (LA,DL), and the terminal504transmits an access uplink signal to the IAB node502through an access uplink (LA,UL). The IAB node502transmits a backhaul downlink signal to the child IAB node503through a backhaul downlink (LC,DL), and the child IAB node503transmits a backhaul uplink signal to the IAB node502through a backhaul uplink (LC,UL). In the above notation, P indicates a backhaul link with a parent node, A indicates an access link with a terminal, and C indicates a backhaul link with a child node.

These link relationships are described with reference to the IAB node502, and in the perspective of the child IAB node503, the IAB node502corresponds to a parent node, and there may be another child IAB node as a lower node of the child IAB node503. In addition, in the perspective of the parent node501, the IAB node502corresponds to a child node, and there may be another IAB parent node as an upper node of the parent node501.

The signal described above includes data and control information, a channel for transmitting data and control information, a reference signal required to decode data and control information, or reference signals for identifying channel information.

Next, a scheme of multiplexing the above-described links in the frequency division and the spatial division is described with reference to the bottom ofFIG.5.

As described above, inFIG.5, unlike the case inFIG.4, when an IAB node has a bidirectional transmission or reception feature at a moment, there may be no restrictions on signals allowing frequency-division multiplexing or spatial-division multiplexing. As a link which can be multiplexed by the IAB node in a specific time division, links such as a backhaul uplink (LP,UL)512, a backhaul downlink (LC,DL)513, an access downlink (LA,DL)516, a backhaul downlink (LP,DL)511, a backhaul uplink (LC,UL)514, and an access uplink (LA,UL)515may be mixed. Accordingly, when the links are multiplexed in the frequency division or the spatial division, the IAB node502may multiplex and simultaneously transmit or receive the above six links or some of the links in the same time division as shown in521and522.

In the perspective of one IAB node inFIG.4, when links in the same direction in terms of transmission or reception are multiplexed in the frequency division or the spatial division, latency can be reduced when transmitting a signal from a parent node to a final terminal, compared to a case of multiplexing all links in the time division inFIG.3. Alternatively, in the perspective of one IAB node inFIG.5, when bidirectional links are multiplexed in the frequency division or the spatial division regardless of transmission or reception, latency can be more reduced when a signal is transmitted from a parent node to a final terminal, compared to the multiplexing method inFIG.4.

FIG.6illustrates multiplexing of a parent link (a backhaul link with a parent IAB node) and a child link (a backhaul link with a child IAB or an access link with a terminal) by using FDM/SDM in an IAB node as shown inFIG.4orFIG.5.

In601, Case A shows that both an MT and a DU within one IAB node perform a transmission operation by using FDM/SDM.

In602, Case B shows that both an MT and a DU within one IAB node perform a reception operation by using FDM/SDM.

In603, Case C illustrates that both an MT and a DU within one IAB node perform reception and transmission operations by using FDM/SDM, wherein the MT performs the reception operation and the DU performs the transmission operation.

In604, Case D illustrates that both an MT and a DU within one IAB node perform reception and transmission operations by using FDM/SDM, wherein the MT performs the transmission operation and the DU performs the reception operation.

As shown inFIG.4,FIG.5, orFIG.6, the following three problems may occur when simultaneous transmission, simultaneous reception, and simultaneous transmission and reception are performed using FDM/SDM.

As the first problem, a case in which an IAB node (402ofFIG.4) has only one RF and the IAB node may perform reception in a specific time interval as shown in Case B602inFIG.6is described. In the above case, the indication indicating whether the IAB node may perform reception or transmission in the specific time interval may be received from a parent IAB node or a donor gNB (401ofFIG.4) through X2 signaling, an upper-layer signal, or a physical single. As shown in422ofFIG.4, when the backhaul downlink (LP,DL)411, the backhaul uplink (LC,UL)414, the access uplink (LA,UL)415, and the like go through FDM/SDM, the IAB node may simultaneously receive signals of the links. In this case, if the IAB node has only one RF and receives the signals of the links, due to a power difference between reception of a backhaul link (e.g., the backhaul downlink411) and reception of an access link (e.g., the access uplink415), it is difficult to receive the access link when the IAB node operates an adaptive gain control (AGC) or an analog-to-digital converter (ADC). That is, when the AGC controls a gain and the ADC converts an analog signal to a digital signal, the granularity for the intensity of an input signal is configured to convert the input signal having a specific intensity into an output which can be processed in hardware. In this case, when the granularity of the input signal is configured with a signal intensity of a backhaul link, there may be a problem that the granularity cannot distinguish a signal intensity of an access link since the signal intensity of the access link is much less. Accordingly, data reception performance and reception throughput of the access link may deteriorate.

Therefore, in the disclosure, the following embodiments are provided as a scheme of preventing deterioration of data reception performance and reception throughput of the access link.

In Embodiment 1, in order to ensure data reception performance of an access uplink (415ofFIG.4) in an IAB node (402ofFIG.4), reception power of a backhaul downlink (411ofFIG.4) or a backhaul uplink (414ofFIG.4) can be adjusted according to reception power of an access uplink (415ofFIG.4).

FIG.7illustrates Embodiment 1 provided in the disclosure for protection of an access uplink from a terminal in IAB according to an embodiment of the disclosure.

InFIG.7, in order to adjust the reception power of the backhaul downlink (411ofFIG.4) according to the reception power of the access uplink (415ofFIG.4), the maximum value (Pmax) of transmission power of the backhaul downlink (411ofFIG.4) from the parent IAB node may be reduced to a specific range (e.g., 23 dBm≤A≤24 dBm) or a specific value (e.g., A=24 dBm) (701). Alternatively, the maximum value may be adjusted to the level of the above-described “A” through an offset value corresponding to a targeted reduction level compared to originally transmittable maximum transmission power. The specific range and the specific value or the offset value may be coordinated between a parent node (401ofFIG.4) and an IAB node (402ofFIG.4), and the coordination may be performed when the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) transmit or receive the information through X2 signaling or a higher-layer signal.

In addition, in order to adjust the reception power of the backhaul uplink (414ofFIG.4) according to the reception power of the access uplink (415ofFIG.4), the same type of power control as that of the access uplink may be performed for the backhaul uplink (414ofFIG.4). That is, the maximum value (Pmax or PCMAX,f,c(i)) of transmission power of the backhaul uplink (414ofFIG.4) may be reduced to a specific range (e.g., 23 dBm≤A≤24 dBm) or a specific value (e.g., A=24 dBm). Alternatively, the maximum value may be adjusted to the level of the above-described “A” through an offset value corresponding to a targeted reduction level compared to originally transmittable maximum transmission power. In the above-described PCMAX,f,c(i) indicating the maximum value, f indicates a carrier index, c indicates a cell index, and i indicates a transmission occasion (or a transmission moment or a transmission slot). The specific range and the specific value or the offset value may be coordinated between a parent node (401ofFIG.4) and an IAB node (402ofFIG.4), and the coordination may be performed when the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) transmit or receive the information through X2 signaling or a higher-layer signal.

In addition, the maximum value (PCMAX,f,c(i)) of the transmission power, the specific range and the specific value, or the offset value may be transmitted from the IAB node (402ofFIG.4) to a child node (403ofFIG.4) through X2 signaling or a higher-layer signal. The child node (403ofFIG.4) may determine transmission power of the backhaul uplink (414ofFIG.4) according to the maximum value (PCMAX,f,c(i)) of the transmission power, the specific range and the specific value, or the offset value, and transmit a signal of the backhaul uplink (414ofFIG.4) by applying the determined transmission power.

Embodiment 1 is advantageous in that reception of an access link is ensured in all time intervals in which a backhaul link and an access link go through FDM/SDM. However, Embodiment 1 is disadvantageous in that power of the backhaul link may be always reduced and thus the performance of the backhaul link may deteriorate. Accordingly, Embodiment 2 for ensuring the performance of the backhaul link for a predetermined time will be provided according to the second embodiment.

Embodiment 2 provides a method for adjusting reception power of a backhaul downlink (411ofFIG.4) or a backhaul uplink (414ofFIG.4) according to reception power of an access uplink (415ofFIG.4) during a specific configured time interval, and increasing reception power of the backhaul downlink (411ofFIG.4) or the backhaul uplink (414ofFIG.4) to the original level during a time interval other than the configured time interval, so as to maintain the performance of a backhaul link for a predetermined time while also ensuring the performance of data reception performance of the access uplink (415ofFIG.4) in an IAB node (402ofFIG.4).

FIG.8illustrates Embodiment 2 provided in the disclosure for protection of an access uplink from a terminal in IAB according to an embodiment of the disclosure.

InFIG.8, a time interval for adjusting the reception power of the backhaul downlink (411ofFIG.4) according to the reception power of the access uplink (415ofFIG.4) is configured as shown in801and803. During the configured time intervals801and803, the maximum value of transmission power of the backhaul downlink (411ofFIG.4) may be reduced to a specific range (e.g., 23 dBm≤A≤24 dBm) or a specific value (e.g., A=24 dBm). Alternatively, the maximum value may be adjusted to the level of the above-described “A” through an offset value corresponding to a targeted reduction level compared to originally transmittable maximum transmission power. During the time intervals802and804other than the configured time intervals, the maximum value of the transmission power of the backhaul downlink (411ofFIG.4) may be increased to the original level B. For example, 38 dBm that is greater than 24 dBm may be applied as the transmission power of the backhaul downlink (411ofFIG.4) by a parent node (401ofFIG.4), and during this time interval, the performance of the backhaul link can be ensured. During the time interval, an IAB node (402ofFIG.4) may perform scheduling to restrict transmission of an access uplink (415ofFIG.4), or may perform scheduling of the transmission of the access uplink by considering that the performance of the access uplink is not ensured during the time interval.

The time interval, the specific range and the specific value, or the offset value may be coordinated between a parent node (401ofFIG.4) and an IAB node (402ofFIG.4), and the coordination may be performed when the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) transmit or receive the information through X2 signaling or a higher-layer signal.

In addition, in order to adjust the reception power of the backhaul uplink (414ofFIG.4) according to the reception power of the access uplink (415ofFIG.4) during the configured time intervals801and803, the same type of power control as that of the access uplink may be performed for the backhaul uplink (414ofFIG.4). That is, the maximum value (PCMAX,f,c(i)) of transmission power of the backhaul uplink (414ofFIG.4) may be reduced to a specific range (e.g., 23 dBm≤A≤24 dBm) or a specific value (e.g., A=24 dBm). Alternatively, the maximum value may be adjusted to the level of the above-described “A” through an offset value corresponding to a targeted reduction level compared to originally transmittable maximum transmission power.

In the above-described PCMAX,f,c(i) indicating the maximum value, f indicates a carrier index, c indicates a cell index, and i indicates a transmission occasion (or a transmission moment or a transmission slot). The time interval, the specific range and the specific value, or the offset value may be coordinated between a parent node (401ofFIG.4) and an IAB node (402ofFIG.4), and the coordination may be performed when the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) transmit or receive the information through X2 signaling or a higher-layer signal. In addition, the maximum value (PCMAX,f,c(i)) of the transmission power, the time interval, the specific range and the specific value, or the offset value may be transmitted from the IAB node (402ofFIG.4) to a child node (403ofFIG.4) through X2 signaling or a higher-layer signal. During the time intervals802and804other than the configured time intervals, the maximum value of the transmission power of the backhaul uplink (414ofFIG.4) may be increased to the original level B.

For example, 38 dBm that is greater than 24 dBm may be applied as the transmission power of the backhaul uplink (414ofFIG.4) by an IAB node (402ofFIG.4), and during this time interval, the performance of the backhaul link can be ensured. During the time interval, an IAB node (402ofFIG.4) may perform scheduling to restrict transmission of an access uplink (415ofFIG.4), or cannot secure the performance of the access uplink even though the transmission of the access uplink is scheduled during the time interval. The child node (403ofFIG.4) may determine transmission power of the backhaul uplink (414ofFIG.4) according to the maximum value (PCMAX,f,c(i)) of the transmission power, the time interval, the specific range and the specific value, or the offset value, and transmit a signal of the backhaul uplink (414ofFIG.4) by applying the determined transmission power.

Embodiment 2 is advantageous in that reception of an access link is ensured in a specific time interval in which a backhaul link and an access link go through FDM/SDM, and power of the backhaul link can be recovered to the original level during the other time intervals, whereby the performance of the backhaul link can be maintained. However, Embodiment 2 is disadvantageous in that reception of the access link is ensured only in a specific time division even though FDM/SDM of the backhaul link and the access link is possible, thereby substantially brining the same effect as TDM of the backhaul link and the access link. Accordingly, Embodiment 3 for substantially enabling FDM/SDM of the backhaul link and the access link and ensuring the performance of the access link will be provided according to the third embodiment.

Embodiment 3 describes a case in which FDM/SDM of a backhaul link and an access link is substantially enabled while data reception performance of an access uplink (415ofFIG.4) in an IAB node (402ofFIG.4) is also ensured. Embodiment 3 provides a method for controlling transmission power of a backhaul downlink in real time in order to adjust reception power of the backhaul downlink (411ofFIG.4) according to reception power of the access uplink (415ofFIG.4).

In Embodiment 3, there may be two options of controlling transmission power of the backhaul downlink (411ofFIG.4) in real time.

In the first option, transmission power of the backhaul downlink (411ofFIG.4) may be controlled by a parent node (401ofFIG.4) and information relating to the controlled transmission power may be indicated to an IAB node (402ofFIG.4).

In the first option, when the parent node (401ofFIG.4) transmits a signal in the backhaul downlink (411ofFIG.4) to the IAB node (402ofFIG.4), as described in Embodiment 1, coordination between the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) may be required to maintain the maximum value (Pmax) of transmission power of the backhaul downlink (411ofFIG.4) within a specific value by using a specific range (e.g., 23 dBm≤A≤24 dBm), a specific value (e.g., A=24 dBm), or an offset value corresponding to a targeted reduction level compared to originally transmittable maximum transmission power. Accordingly, the specific range, the specific value, or the offset value may be coordinated between the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) in advance, and the coordination may be performed when the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) transmit or receive the information through X2 signaling or a higher-layer signal.

When transmitting a signal in the backhaul downlink (411ofFIG.4) to the IAB node (402ofFIG.4), the parent node (401ofFIG.4) controls transmission power according to the coordinated value and transmits the signal in the backhaul downlink (411ofFIG.4). In this case, information on transmission power of signals, which have failed to be transmitted in real time in the backhaul downlink (411ofFIG.4), for example, a synchronous signal, a reference signal for channel estimation, a physical control channel, and the like may be transmitted from the parent node (401ofFIG.4) to the IAB node (402ofFIG.4) through a higher-layer signal in advance, and information on transmission power of a signal such as a physical data channel which can be scheduled in real time in the backhaul downlink (411ofFIG.4) may be transmitted from the parent node (401ofFIG.4) to the IAB node (402ofFIG.4) through a bit field of the physical control channel. The IAB node (402ofFIG.4) can receive a signal in the backhaul downlink (411ofFIG.4) by using the transmission power information, thereby protecting the access uplink (415ofFIG.4).

The second option is identical to the first option in that transmission power of backhaul downlink (411ofFIG.4) is controlled by the parent node (401ofFIG.4), but differs from the first option in that required transmission power information may be transmitted from the IAB node (402ofFIG.4) to the parent node (401ofFIG.4).

In the second option, the IAB node (402ofFIG.4) transmits information on transmission power of the backhaul downlink (411ofFIG.4), required to protect the access uplink (415ofFIG.4), to the parent node (401ofFIG.4). In this case, the transmission power information may be transmitted to the parent node (401ofFIG.4) through an uplink control signal. For example, transmission power information such as a specific value (e.g., A=24 dBm) or an offset value corresponding to a targeted reduction level compared to originally transmittable maximum transmission power may be transmitted. An uplink control signal related to the transmission power information may be periodically or aperiodically transmitted. When transmitting a signal of the backhaul downlink (411ofFIG.4) to the IAB node (402ofFIG.4), the parent node (401ofFIG.4) may control transmission power of the backhaul downlink (411ofFIG.4) according to the transmission power information and transmit the signal.

In Embodiment 3, in order to adjust the reception power of the backhaul uplink (414ofFIG.4) according to the reception power of the access uplink (415ofFIG.4), the same type of power control as that of the access uplink may be performed for the backhaul uplink (414ofFIG.4). That is, the maximum value (PCMAX,f,c(i)) of transmission power of the backhaul uplink (414ofFIG.4) may be reduced to a specific range (e.g., 23 dBm≤A≤24 dBm) or a specific value (e.g., A=24 dBm). Alternatively, the maximum value may be adjusted to the level of the above-described “A” through an offset value corresponding to a targeted reduction level compared to originally transmittable maximum transmission power.

In the above-described PCMAX,f,c(i) indicating the maximum value, f indicates a carrier index, c indicates a cell index, and i indicates a transmission occasion (or a transmission moment or a transmission slot). The specific range and the specific value or the offset value may be coordinated between the parent node (401ofFIG.4) and the IAB node (402ofFIG.4), and the coordination may be performed when the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) transmit or receive the information through X2 signaling or a higher-layer signal. In addition, the maximum value PCMAX,f,c(i) of the transmission power may be transmitted from the IAB node (402ofFIG.4) to the child node (403ofFIG.4) through X2 signaling or a higher-layer signal.

In addition, transmission power control information may be transmitted through a bit field of a physical control channel of the backhaul downlink (413ofFIG.4) transmitted from the IAB node (402ofFIG.4) to the child node (403ofFIG.4). The child node (403ofFIG.4) may determine transmission power of the backhaul uplink (414ofFIG.4) according to the maximum value (PCMAX,f,c(i)) of the transmission power and the transmission power control information, and transmit a signal of the backhaul uplink (414ofFIG.4) by applying the determined transmission power.

In Embodiment 3, when the parent node (401ofFIG.4) transmits a signal of the backhaul downlink (411ofFIG.4) by controlling transmission power in real time, the transmission power control may affect transmission power of an access downlink of the parent node (401ofFIG.4), transmitted in another frequency area. Accordingly, reception of system information or a synchronous signal of a terminal connected to the parent node (401ofFIG.4) may be affected. Therefore, when the first option or the second option of Embodiment 3 is applicable during a specific time interval only. The time interval may be configured as a time interval in which no system information or synchronous signal of the terminal is transmitted. The parent node (401ofFIG.4) may transmit a signal of the backhaul downlink (411ofFIG.4) by applying the first option or the second option of Embodiment 3 in the time interval only, and transmit a signal of the backhaul downlink (411ofFIG.4) without applying Embodiment 3 in a time interval other than the time interval. The time interval may be coordinated between the parent node (401ofFIG.0.4) and the IAB node (402ofFIG.4), and the coordination may be performed when the parent node (401ofFIG.4) and the IAB node (402ofFIG.4) transmit or receive the information through X2 signaling or a higher-layer signal.

Next, the second problem to be solved in a case where FDM/SDM is performed is described.

The second problem is described with reference to Case A (601) inFIG.6in which an IAB node (402ofFIG.4) includes only one RF, and the IAB node may perform transmission in a specific time interval. In the case above, indication relating to whether the IAB node may perform reception or transmission in the specific time interval may be received from a parent IAB node or a donor gNB (401ofFIG.4) through X2 signaling or a higher-layer or physical signal. As shown in421ofFIG.4, when FDM/SDM is performed for the backhaul uplink (LP,UL)412, the backhaul downlink (LC,DL)413, the access downlink (LA,DL)416, and the like, the IAB node can simultaneously transmit signals of the links. In this case, when the IAB node includes only one RF and transmits the signals of the links, power of the IAB node may be restricted. For example, when the IAB node402is indicated by the parent node401so as to use the maximum transmission power for transmission of the backhaul uplink (LP,UL)412, a transmission power value which can be used by the IAB node is limited, and thus transmission power which can used for transmission of the backhaul downlink (LC,DL)413, the access downlink (LA,DL)416, and the like may be restricted. Alternatively, an example of the opposite case may occur. Accordingly, an embodiment of the disclosure provides a specific embodiment for an operation of an IAB during the transmission power restriction above.

Embodiment 4 provides a method for determining a link which is to be prioritized to be transmitted, according to a priority rule. That is, as shown in421ofFIG.4, when FDM/SDM is performed for the backhaul uplink (LP,UL)412, the backhaul downlink (LC,DL)413, the access downlink (LA,DL)416, or the like, and two or more links may be simultaneously transmitted, transmission or transmission power of a link, which is to be prioritized, is determined according to transmission information or a transmission channel of the link. For example, the priority rule of the transmission channel or the transmission information may be determined as follows, but is a mere example, and the disclosure is not limited thereto:

First priority: Synchronous signal, TRS for channel phase estimation, or synchronous signal or CSI-RS transmitted for discovery of IAB nodes;

Second priority: Uplink control information including HARQ-ACK;

Third priority: Uplink data channel including HARQ-ACK; and

The first priority corresponds to a channel or information which may be prioritized, and the importance of a lower priority decreases compared to a higher priority. The above priority rule is an example, information or a channel to be prioritized may be determined differently, and the transmission priority as described above may be determined according to a standard. In the description above, being prioritized means that when the transmission power is limited, the transmission power transmission power is given first, or transmission is always performed. Conversely, not being prioritized means that when the transmission power is limited, transmission power is reduced compared to that of a higher priority, or transmission is dropped.

The transmission channel or transmission information includes a channel or information which can be transmitted in the backhaul uplink (LP,UL)412, the backhaul downlink (LC,DL)413, and the access downlink (LA,DL)416, and when the same channel or information is transmitted through two different links, a backhaul link may be prioritized, or an access link may be prioritized. In addition, the transmission waveform of the links may be configured as CP-OFDM or DFT-S-OFDM through a higher-layer signal or X2 signaling. In the case above, when two different links are transmitted with different waveforms, DFT-S-OFDM may be prioritized over CP-OFDM.

According to the rule above, transmitting, to the IAB node402, a link including a channel or information having a higher priority, is prioritized to be transmitted in terms of transmission power or transmission, and when transmission power of the IAB node402is insufficient, transmission power for a link including a channel or information having a lower priority may be reduced, or transmission may be dropped.

The third problem to be solved in a case where FDM/SDM is performed is described.

The third problem is described with reference to Cases C and D (603and604) inFIG.6in which an IAB node (502ofFIG.5) simultaneously perform reception and transmission. In the cases above, indication relating to whether an MT in the IAB node may perform reception or transmission in a specific time interval may be received from a parent IAB node or a donor gNB (501ofFIG.5) through X2 signaling or a higher-layer or physical signal. In addition, whether a DU in the IAB node may perform transmission or reception may be determined by the DU itself through X2 signaling or a higher-layer or physical signal from an IAB node or a donor gNB (501ofFIG.5) according to an uplink, a downlink, or a flexible slot and hard/soft/unavailable types of each slot. In this case, when the MT performs reception and the DU performs transmission, or when the MT performs transmission and the DU performs transmission, the interference due to the transmission of the IAB affects the reception of the IAB, and thus the access or backhaul data reception performance or reception throughput may deteriorate.

Accordingly, the disclosure provides a scheme of solving the problem in a case where the transmission of the IAB MT causes interference in the reception of the IAB, specifically, the reception of the IAB DU, through embodiments below.

Embodiment 5 provides a scheme of reducing transmission power of a backhaul uplink (512ofFIG.5) of an IAB MT to ensure reception performance of an IAB DU in the IAB node (502ofFIG.5). That is, in order to reduce the maximum value (Pmax or PCMAX,f,c(i))) of transmission power of the backhaul uplink (512ofFIG.5), new maximum power reduction (MRP) which is applicable at the time of transmission of the IAB MT can be applied. The MPR is applicable when transmission and reception are simultaneously performed in one IAB node, such as a case where the IAB DU performs reception and the IAB MT performs transmission. Alternatively, the MPR is applicable to a case where self-interference (SI) removal is applied in a DU receiver of the IAB node when transmission and reception are simultaneously performed. Alternatively, different MPR values are applicable according to the size of the SI. Alternatively, different MPR values are applicable according to the distance between antenna panels included in the DU and the MT of the IAB node. Alternatively, different MPR values are applicable according to whether timings of the MT transmission and the DU reception of the IAB node coincide in a CP interval.

The MPR values may be coordinated between the parent IAB node or the gNB (501ofFIG.5) and the IAB node (502ofFIG.5), and the coordination may be performed when the parent node or the gNB (501ofFIG.5) and the IAB node (502ofFIG.5) transmit or receive the information through X2 signaling or a higher-layer signal. Alternatively, the IAB node may apply the MPR value according to the defined standard.

For example, a maximum value of transmission power, which is obtained after applying the MPR to the maximum value (Pmax or PCMAX,f,c(i))) of the transmission power by the IAB node, is as follows:
PCMAX,f,c(i))maximum value after applying MPR=PCMAX,f,c(i))maximum value before applying MPR−MPR.

If the IAB node has failed to receive, in real time, scheduling of simultaneously performing transmission and reception, or when it is determined that transmission and the reception are not simultaneously performed, MPR=0 may be applicable to the corresponding slot or the corresponding transmission occasion. Information on an interval in which transmission and reception are simultaneously performed or an interval in which transmission and reception are not simultaneously performed may be coordinated between the parent node or the gNB (501ofFIG.5) and the IAB node (502ofFIG.5), and the coordination may be performed when the parent node or the gNB (501ofFIG.5) and the IAB node (502ofFIG.5) transmit or receive the interval information through X2 signaling or a higher-layer signal.

Embodiment 6 provides, as a scheme of reducing transmission power of a backhaul uplink (512ofFIG.5) of an IAB MT to ensure reception performance of an IAB DU in the IAB node (502ofFIG.5), a method for applying a new maximum value PCMAX,SI for transmission of the IAB MT instead of a maximum value (Pmax or PCMAX,f,c(i)) of the transmission of the backhaul uplink (512ofFIG.5).

The PCMAX,SI is applicable when transmission and reception are simultaneously performed in one IAB node, such as a case where the IAB DU performs reception and the IAB MT performs transmission. Alternatively, the PCMAX,SI is applicable to a case where self-interference (SI) removal is applied in a DU receiver of the IAB node when transmission and reception are simultaneously performed. Alternatively, different PCMAX,SI values are applicable according to the size of the SI. Alternatively, different PCMAX,SI values are applicable according to the distance between antenna panels included in the DU and the MT of the IAB node. Alternatively, different PCMAX,SI values are applicable according to whether timings of the MT transmission and the DU reception of the IAB node coincide in a CP interval.

The PCMAX,SI values may be coordinated between the parent IAB node or the gNB (501ofFIG.5) and the IAB node (502ofFIG.5), and the coordination may be performed when the parent node or the gNB (501ofFIG.5) and the IAB node (502ofFIG.5) transmit or receive the information through X2 signaling or a higher-layer signal. Alternatively, the IAB node may apply the PCMAX,SI value according to the defined standard.

For example, a power value obtained by applying the PCMAX,SI to the maximum value (Pmax or PCMAX,f,c(i))) of the transmission power by the IAB MT, is as follows:
PMT(i)=min{PCMAX,f,c(i)),PCMAX,SI,P0+α·PL+f(i,1)+Δ(i)}.

If the PCMAX,SI is not configured for the IAB node, the IAB node may apply PCMAX,SI according to PCMAX,SI=PCMAX,f,c(i)).

The structures of a terminal and a base station including a transmitter, a receiver, and a controller for performing the embodiments of the disclosure are illustrated inFIGS.9and10. In addition, a device of an IAB node is illustrated inFIG.11. Detailed embodiments describe a transmission or reception method of a base station (a donor base station) which performs transmission or reception of a backhaul link with an IAB node through an mmWave and a terminal which performs transmission or reception of an access link with the IAB node, when the backhaul link and the access link perform transmission or reception through the IAB node in a 5G communication system, and a transmitter, a receiver, and a processor of an IAB node of each of a terminal and a base station may operate to perform the detailed embodiments.

Specifically,FIG.9illustrates a structure of a terminal according to an embodiment of the disclosure.

As shown inFIG.9, the terminal of the disclosure may include a terminal processor901, a terminal receiver902, and a terminal transmitter903.

The terminal processor901may control a series of processes that the terminal can operate according to the above-described embodiment of the disclosure. For example, the terminal processor901may differently control backhaul link transmission or reception and access link transmission or reception with an IAB node, etc., according to an embodiment of the disclosure. The terminal receiver902and the terminal transmitter903may be commonly called a transceiver in an embodiment of the disclosure. The transceiver may transmit and receive a signal to and from a base station or an IAB node. The signal may include control information and data. To this end, the transceiver may include an RF transmitter configured to up-convert and amplify the frequency of a transmitted signal and an RF receiver configured to low-noise amplify a received signal and to down-convert a frequency, etc. In addition, the transceiver may receive a signal through a radio channel, transmit the signal to the terminal processor901, and transmit a signal output from the terminal processor901, through a radio channel.

FIG.10illustrates a structure of a base station (for example, a donor base station) according to an embodiment of the disclosure.

As shown inFIG.10, the base station of the disclosure may include a base station processor1001, a base station receiver1002, and a base station transmitter1003.

The base station processor1001may control a series of processes that the base station can operate according to the above-described embodiment of the disclosure. For example, the base station processor1001may differently control access link transmission or reception with an IAB node, etc., according to an embodiment of the disclosure. The base station receiver1002and the base station transmitter1003may be commonly called a transceiver in an embodiment of the disclosure. The transceiver may transmit and receive a signal to and from a terminal or an IAB node. The signal may include control information and data. To this end, the transceiver may include an RF transmitter configured to up-convert and amplify the frequency of a transmitted signal and an RF receiver configured to low-noise amplify a received signal and to down-convert a frequency, etc. In addition, the transceiver may receive a signal through a radio channel, transmit the signal to the base station processor1001, and transmit a signal output from the base station processor1001, through a radio channel.

FIG.11illustrates a structure of an IAB node according to an embodiment of the disclosure.

As shown inFIG.11, the IAB node of the disclosure may include a base station function processor1101, a base station function receiver1102, and a base station function transmitter1103of an IAB node for transmitting or receiving to or from a lower IAB node through a backhaul link. In addition, the IAB node may include a terminal function processor1111, a terminal function receiver1112, and a terminal function transmitter1113of an IAB node for performing initial access to an upper IAB node and a donor base station, performing upper signal transmission or reception before transmission or reception through a backhaul link, and performing backhaul transmission or reception with an upper IAB node and a donor base station.

The base station function processor1101of the IAB node may control a series of processes that the IAB node can operate like a base station according to the above-described embodiment of the disclosure. For example, the base station function processor1101may differently control backhaul link transmission or reception with a lower IAB node, access link transmission or reception with a terminal, etc., according to an embodiment of the disclosure. The base station function receiver1102and the base station function transmitter1103may be commonly called a transceiver in an embodiment of the disclosure. The transceiver may transmit and receive a signal to and from a lower IAB node and a terminal. The signal may include control information and data. To this end, the transceiver may include an RF transmitter configured to up-convert and amplify the frequency of a transmitted signal and an RF receiver configured to low-noise amplify a received signal and to down-convert a frequency, etc.

In addition, the transceiver may receive a signal through a radio channel, transmit the signal to the base station function processor1101, and transmit a signal output from the base station function processor1101, through a radio channel. The terminal function processor1111of the IAB node may control a series of processes that a lower IAB node can operate like a terminal in order for the lower IAB node to perform data transmission or reception with the donor base station or the upper IAB node according to the above-described embodiment of the disclosure.

For example, the terminal function processor1111may differently control backhaul link transmission or reception, etc., with a donor base station and an upper IAB node according to an embodiment of the disclosure. The terminal function receiver1112, the IAB node, and the terminal function transmitter1113may be commonly called a transceiver in an embodiment of the disclosure. The transceiver may transmit and receive a signal to and a donor base station and an upper IAB node. The signal may include control information and data. To this end, the transceiver may include an RF transmitter configured to up-convert and amplify the frequency of a transmitted signal and an RF receiver configured to low-noise amplify a received signal and to down-convert a frequency, etc. In addition, the transceiver may receive a signal through a radio channel, transmit the signal to the terminal function processor1111, and transmit a signal output from the terminal function processor1111, through a radio channel.

The embodiments of the disclosure described and shown in the specification and the drawings are merely specific example that have been presented to easily explain the technical contents of the disclosure and help understanding of the disclosure, and are not intended to limit the scope of the disclosure. That is, it will be apparent to those skilled in the art that other variants may be implemented based on the technical idea of the disclosure. Further, the above respective embodiments may be employed in combination, as necessary.