WO2020055041A1

WO2020055041A1 - Method and apparatus for supporting resource sharing for relay nodes with multiple beams in wireless communication system

Info

Publication number: WO2020055041A1
Application number: PCT/KR2019/011487
Authority: WO
Inventors: Yunjung Yi
Original assignee: Lg Electronics Inc.
Priority date: 2018-09-10
Filing date: 2019-09-05
Publication date: 2020-03-19

Abstract

A method and apparatus for supporting resource sharing for relay nodes, e.g., integrated access and backhaul (IAB) nodes, with multiple beams in a wireless communication system is provided. A first node, which may be a first IAB node, receives a first preamble from a user equipment (UE), and receives a second preamble from a second node. The first node transmits a first random access response (RAR) addressed by a first random access radio network temporary identifier (RA-RNTI) as a response to the first preamble to the UE, and transmits a second RAR addressed by a second RA-RNTI as a response to the second preamble to the second node. A first set of RA-RNTIs to which the first RA-RNTI belongs and a second set of RA-RNTIs to which the second RA-RNTI belongs are not overlapped with each other.

Description

METHOD AND APPARATUS FOR SUPPORTING RESOURCE SHARING FOR RELAY NODES WITH MULTIPLE BEAMS IN WIRELESS COMMUNICATION SYSTEM

The present invention relates to wireless communications, and more particularly, to a method and apparatus for supporting resource sharing for relay nodes, e.g., integrated access and backhaul (IAB) nodes, with multiple beams in a wireless communication system.

3rd generation partnership project (3GPP) long-term evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.

Work has started in international telecommunication union (ITU) and 3GPP to develop requirements and specifications for new radio (NR) systems. 3GPP has to identify and develop the technology components needed for successfully standardizing the new RAT timely satisfying both the urgent market needs, and the more long-term requirements set forth by the ITU radio communication sector (ITU-R) international mobile telecommunications (IMT)-2020 process. Further, the NR should be able to use any spectrum band ranging at least up to 100 GHz that may be made available for wireless communications even in a more distant future.

The NR targets a single technical framework addressing all usage scenarios, requirements and deployment scenarios including enhanced mobile broadband (eMBB), massive machine-type-communications (mMTC), ultra-reliable and low latency communications (URLLC), etc. The NR shall be inherently forward compatible.

One of the potential technologies targeted to enable future cellular network deployment scenarios and applications is the support for wireless backhaul and relay links enabling flexible and very dense deployment of NR cells without the need for densifying the transport network proportionately.

Due to the expected larger bandwidth available for NR compared to LTE (e.g., mmWave spectrum) along with the native deployment of massive multiple-input multiple-output (MIMO) or multi-beam systems in NR creates an opportunity to develop and deploy integrated access and backhaul (IAB) links. This may allow easier deployment of a dense network of self-backhauled NR cells in a more integrated manner by building upon many of the control and data channels/procedures defined for providing access to UEs. Due to deployment of IAB links, relay nodes can multiplex access and backhaul links in time, frequency, or space (e.g., beam-based operation).

The present invention discusses procedures and associated signaling to efficiently coordinate resources between integrated access and backhaul (IAB) nodes with different hop (and also between backhaul link and access link).

In an aspect, a method performed by a first node in a wireless communication system is provided. The method includes receiving a first preamble from a user equipment (UE), receiving a second preamble from a second node, transmitting a first random access response (RAR) addressed by a first random access radio network temporary identifier (RA-RNTI) as a response to the first preamble to the UE, and transmitting a second RAR addressed by a second RA-RNTI as a response to the second preamble to the second node. A first set of RA-RNTIs to which the first RA-RNTI belongs and a second set of RA-RNTIs to which the second RA-RNTI belongs are not overlapped with each other.

In another aspect, a first node in a wireless communication system is provided. The first node includes a memory, a transceiver, and a processor, operably coupled to the memory and the transceiver The first node is configured to receive a first preamble from a user equipment (UE), receive a second preamble from a second node, transmit a first random access response (RAR) addressed by a first random access radio network temporary identifier (RA-RNTI) as a response to the first preamble to the UE, and transmit a second RAR addressed by a second RA-RNTI as a response to the second preamble to the second node. A first set of RA-RNTIs to which the first RA-RNTI belongs and a second set of RA-RNTIs to which the second RA-RNTI belongs are not overlapped with each other.

IAB can be supported efficiently.

FIG. 1 shows an example of a communication system to which the technical features of the present invention can be applied.

FIG. 2 shows an example of wireless devices to which the technical features of the present invention can be applied.

FIG. 3 shows an example of a signal processing circuit for a transmission signal to which the technical features of the present invention can be applied.

FIG. 4 shows another example of a wireless device to which the technical features of the present invention can be applied.

FIG. 5 shows an example of a wireless communication system to which the technical features of the present invention can be applied.

FIG. 6 shows another example of a wireless communication system to which the technical features of the present invention can be applied.

FIG. 7 shows an example of a frame structure to which technical features of the present invention can be applied.

FIG. 8 shows another example of a frame structure to which technical features of the present invention can be applied.

FIG. 9 shows an example of a subframe structure used to minimize latency of data transmission when TDD is used in NR.

FIG. 10 shows an example of a resource grid to which technical features of the present invention can be applied.

FIG. 11 shows an example of a synchronization channel to which technical features of the present invention can be applied.

FIG. 12 shows an example of a frequency allocation scheme to which technical features of the present invention can be applied.

FIG. 13 shows an example of multiple BWPs to which technical features of the present invention can be applied.

FIG. 14 shows an example of IAB links to which technical features of the present invention can be applied.

FIG. 15 shows an example of IAB links to which technical features of the present invention can be applied.

FIG. 16 shows an example of a method for performing initial access with UE and IAB node according to an embodiment of the present invention.

FIG. 17 shows an example of TDM pattern of a donor node and IAB nodes to which the technical features of the present invention can be applied.

The technical features described below may be used by a communication standard by the 3rd generation partnership project (3GPP) standardization organization, a communication standard by the institute of electrical and electronics engineers (IEEE), etc. For example, the communication standards by the 3GPP standardization organization include long-term evolution (LTE) and/or evolution of LTE systems. The evolution of LTE systems includes LTE-advanced (LTE-A), LTE-A Pro, and/or 5G new radio (NR). The communication standard by the IEEE standardization organization includes a wireless local area network (WLAN) system such as IEEE 802.11a/b/g/n/ac/ax. The above system uses various multiple access technologies such as orthogonal frequency division multiple access (OFDMA) and/or single carrier frequency division multiple access (SC-FDMA) for downlink (DL) and/or uplink (UL). For example, only OFDMA may be used for DL and only SC-FDMA may be used for UL. Alternatively, OFDMA and SC-FDMA may be used for DL and/or UL.

In this document, the term "/" and "," should be interpreted to indicate "and/or." For instance, the expression "A/B" may mean "A and/or B." Further, "A, B" may mean "A and/or B." Further, "A/B/C" may mean "at least one of A, B, and/or C." Also, "A, B, C" may mean "at least one of A, B, and/or C."

Further, in the document, the term "or" should be interpreted to indicate "and/or." For instance, the expression "A or B" may comprise 1) only A, 2) only B, and/or 3) both A and B. In other words, the term "or" in this document should be interpreted to indicate "additionally or alternatively."

An example of a communication system to which the technical features of the present invention can be applied is described.

Although not limited thereto, various descriptions, functions, procedures, suggestions, methods and/or operational flowcharts of the present invention disclosed herein can be applied to various fields requiring wireless communication and/or connection (e.g., 5G) between devices.

Hereinafter, the present invention will be described in more detail with reference to drawings. The same reference numerals in the following drawings and/or descriptions may refer to the same and/or corresponding hardware blocks, software blocks, and/or functional blocks unless otherwise indicated.

Referring to FIG. 1, a communication system 1 to which the technical features of the present invention can be applied includes a wireless device, a base station and a network. Here, the wireless device refers to a device that performs communication using a radio access technology (e.g., 5G new radio access technology (NR), long-term evolution (LTE)), and may be referred to as a communication / wireless / 5G device. Although not limited thereto, the wireless device may include a robot 100a, a vehicle 100b-1, 100b-2, an extended reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an internet of things (IoT) device 100f and an artificial intelligence (AI) device / server 400. For example, the vehicle may include a vehicle having a wireless communication function, an autonomous vehicle, a vehicle capable of performing inter-vehicle communication, etc. Here, the vehicle may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device may include augmented reality (AR) / virtual reality (VR) / mixed reality (MR) devices. The XR device may be implemented in the form of head-mounted device (HMD), head-up display (HUD) provided in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, a digital signage, a vehicle, a robot, etc. The hand-held device device may include a smartphone, a smart pad, a wearable device (e.g., a smart watch, smart glasses), a computer (e.g., a laptop, etc.). The home appliance may include a TV, a refrigerator, a washing machine, etc. The IoT device may include a sensor, a smart meter, etc. For example, the base station and the network may be implemented as a wireless device. A specific wireless device 200a may operate as a base station / network node to other wireless devices.

The wireless devices 100a to 100f may be connected to the network 300 through the base station 200. AI technology may be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI server 400 through the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network and/or a 5G (e.g., NR) network. The wireless devices 100a to 100f may communicate with each other via the base station 200 / network 300, but may also communicate directly (e.g., sidelink communication) without passing through the base station 200 / network 300. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). In addition, the IoT device (e.g., sensor) may directly communicate with another IoT device (e.g., sensor) or another wireless device 100a to 100f.

Wireless communication /

connections

150a, 150b, and 150c may be performed between the wireless devices 100a to 100f and the base station 200 and/or between the base stations 200. Here, the wireless communication / connection may be performed by various wireless access technologies (e.g., 5G NR) such as uplink / downlink communication 150a, sidelink communication (or device-to-device (D2D)) communication) 150b, inter-base station communication 150c (e.g., relay, integrated access and backhaul (IAB)), etc. The wireless device and the base station / wireless device and/or the base stations may transmit / receive radio signals with each other respectively through the wireless communication /

connection

150a, 150b, and 150c. For example, wireless communications /

connections

150a, 150b, and 150c may transmit / receive signals over various physical channels. To this end, based on various proposals of the present invention, at least some of various configuration information setting processes, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / de-mapping, etc.), and resource allocation process for transmitting / receiving a wireless signal may be performed.

Referring to FIG. 2, the first wireless device 100 and the second wireless device 200 may transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device 100 and the second wireless device 200} may correspond to {the wireless device 100x, the base station 200} and/or {the wireless device 100x, the wireless device 100x} in FIG. 1.

The first wireless device 100 may include one or more processors 102 and one or more memories 104. The first wireless device 100 may further include one or more transceivers 106 and/or one or more antennas 108. The processor 102 may control the memory 104 and/or the transceiver 106. The processor 102 may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein. For example, the processor 102 may process information in the memory 104 to generate the first information/signal, and then transmit a wireless signal including the first information/signal through the transceiver 106. In addition, the processor 102 may receive a wireless signal including the second information/signal through the transceiver 106 and then store information obtained from signal processing of the second information/signal in the memory 104. The memory 104 may be coupled to the processor 102 and may store various information related to the operation of the processor 102. For example, the memory 104 may include software code that includes instructions for performing some or all of the processes controlled by the processor 102 and/or for carrying out the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein. Here, processor 102 and memory 104 may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver 106 may be coupled with the processor 102 and may transmit and/or receive wireless signals via one or more antennas 108. The transceiver 106 may include a transmitter and/or a receiver. The transceiver 106 may be mixed with a radio frequency (RF) unit. In the present invention, a wireless device may mean a communication modem / circuit / chip.

The second wireless device 200 may include one or more processors 202 and one or more memories 204. The second wireless device 200 may further include one or more transceivers 206 and/or one or more antennas 208. The processor 202 may control the memory 204 and/or the transceiver 206. The processor 202 may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein. For example, the processor 202 may process information in the memory 204 to generate the third information/signal, and then transmit a wireless signal including the third information/signal through the transceiver 206. In addition, the processor 202 may receive a wireless signal including the fourth information/signal through the transceiver 206 and then store information obtained from signal processing of the fourth information/signal in the memory 204. The memory 204 may be coupled to the processor 202 and may store various information related to the operation of the processor 202. For example, the memory 204 may include software code that includes instructions for performing some or all of the processes controlled by the processor 202 and/or for carrying out the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein. Here, processor 202 and memory 204 may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver 206 may be coupled with the processor 202 and may transmit and/or receive wireless signals via one or more antennas 208. The transceiver 206 may include a transmitter and/or a receiver. The transceiver 206 may be mixed with an RF unit. In the present invention, a wireless device may mean a communication modem / circuit / chip.

Hereinafter, hardware elements of the

wireless devices

100, 200 will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or

more processors

102, 202. For example, one or

more processors

102, 202 may implement one or more layers (e.g., functional layers such as physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), radio resource control (RRC)). One or

more processors

102, 202 may generate one or more protocol data units (PDUs) and/or one or more service data units (SDUs) in accordance with the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein. One or

more processors

102, 202 may generate messages, control information, data, or information in accordance with the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein. One or

more processors

102, 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information in accordance with the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein, and provide to one or

more transceivers

106, 206. One or

more processors

102, 202 may receive signals (e.g., baseband signals) from one or

more transceivers

106, 206, and obtain PDUs, SDUs, messages, control information, data or information in accordance with the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein.

One or

more processors

102, 202 may be referred to as a controller, a microcontroller, a microprocessor, and/or a microcomputer. One or

more processors

102, 202 may be implemented by hardware, firmware, software, and/or a combination thereof. For example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), and/or one or more field programmable gate arrays (FPGAs) may be included in one or

more processors

102, 202. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein may be implemented using firmware and/or software, and the firmware and/or software may be implemented to include modules, procedures, functions, etc. Firmware and/or software configured to perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein may be included in one or

more processors

102, 202 or stored in one or

more memories

104, 204 and may be driven by one or

more processors

102, 202. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein may be implemented using firmware or software in the form of code, instructions and/or a set of instructions.

One or

more memories

104, 204 may be coupled with one or

more processors

102, 202 and may store various forms of data, signals, messages, information, programs, codes, instructions, and/or commands. One or

more memories

104, 204 may be comprised of a read-only memory (ROM), a random access memory (RAM), an erasable programmable read-only memory (EPROM), a flash memory, a hard drive, a register, a cache memory, a computer readable storage medium and/or combinations thereof. One or

more memories

104, 204 may be located inside and/or outside one or

more processors

102, 202. In addition, one or

more memories

104, 204 may be coupled to one or

more processors

102, 202 through various techniques, such as a wired and/or wireless connection.

One or

more transceivers

106, 206 may transmit user data, control information, wireless signals/channels, etc., as mentioned in the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein, to one or more other devices. One or

more transceivers

106, 206 may receive user data, control information, wireless signals/channels, etc., as mentioned in the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein, from one or more other devices. For example, one or

more transceivers

106, 206 may be coupled with one or

more processors

102, 202 and may transmit and/or receive wireless signals. For example, one or

more processors

102, 202 may control one or

more transceivers

106, 206 to transmit user data, control information, wireless signals/channels, etc., to one or more other devices. In addition, one or

more processors

102, 202 may control one or

more transceivers

106, 206 to receive user data, control information, wireless signals/channels, etc., from one or more other devices. In addition, one or

more transceivers

106, 206 may be coupled to one or

more antennas

108, 208. One or

more transceivers

106, 206 may be configured to transmit and/or receive user data, control information, wireless signals/channels, etc., as mentioned in the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein, through one or

more antennas

108, 208. In this document, one or

more antennas

108, 208 may be a plurality of physical antennas and/or a plurality of logical antennas (e.g., antenna ports). In order to process the received user data, control information, wireless signals/channels, etc., using one or

more processors

102, 202, one or

more transceivers

106, 206 may convert the received user data, control information, wireless signals/channels, etc., from an RF band signal to a baseband signal. One or

more transceivers

106, 206 may convert user data, control information, wireless signals/channels, etc., processed by using one or

more processors

102, 202, from a baseband signal to an RF band signal. To this end, one or

more transceivers

106, 206 may include (analog) oscillators and/or filters.

Referring to FIG. 3, the signal processing circuit 1000 may include a scrambler 1010, a modulator 1020, a layer mapper 1030, a precoder 1040, a resource mapper 1050, and a signal generator 1060. Although not limited thereto, operations/functions of FIG. 3 may be performed in

processors

102, 202 and/or

transceivers

106, 206 of FIG. 2. The hardware element of FIG. 3 may be implemented in

processors

102, 202 and/or

transceivers

106, 206 of FIG. 2. For example, blocks 1010 to 1060 may be implemented in

processors

102, 202 of FIG. 2. Further, blocks 1010 to 1050 may be implemented in

processors

102, 202 of FIG. 2, and block 1060 may be implemented in

transceivers

106, 206 of FIG. 2.

The codeword may be converted into a wireless signal via the signal processing circuit 1000 of FIG. 3. Here, the codeword is a coded bit sequence of the information block. The information block may include a transport block (e.g., an uplink shared channel (UL-SCH) transport block, a downlink shared channel (DL-SCH) transport block). The wireless signal may be transmitted through various physical channels (e.g., physical uplink shared channel (PUSCH), physical downlink shared channel (PDSCH)).

In detail, the codeword may be converted into a scrambled bit sequence by the scrambler 1010. The scramble bit sequence used for scrambling may be generated based on initialization value, and the initialization value may include ID information of the wireless device, etc. The scrambled bit sequence may be modulated into a modulation symbol sequence by the modulator 1020. The modulation scheme may include pi/2-binary phase shift keying (pi/2-BPSK), m-phase shift keying (m-PSK), m-quadrature amplitude modulation (m-QAM), etc. The complex modulation symbol sequence may be mapped to one or more transport layers by the layer mapper 1030. The modulation symbols of each transport layer may be mapped to the corresponding antenna port(s) by the precoder 1040 (precoding). The output z of the precoder 1040 may be obtained by multiplying the output y of the layer mapper 1030 with the precoding matrix W of N*M. Here, N is the number of antenna ports and M is the number of transport layers. Here, the precoder 1040 may perform precoding after performing transform precoding (e.g., discrete Fourier transform (DFT)) on the complex modulation symbols. Also, the precoder 1040 may perform precoding without performing transform precoding.

The resource mapper 1050 may map modulation symbols of each antenna port to time-frequency resources. The time-frequency resource may include a plurality of symbols (e.g., cyclic prefix based OFDMA (CP-OFDMA) symbols, DFT spread OFDMA (DFT-s-OFDMA) symbols) in the time domain, and may include a plurality of subcarriers in the frequency domain. The signal generator 1060 may generate a wireless signal from the mapped modulation symbols, and the generated wireless signal may be transmitted to another device through each antenna. To this end, the signal generator 1060 may include an inverse fast Fourier transform (IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analog converter (DAC), a frequency uplink converter, etc.

The signal processing procedure for a reception signal in the wireless device may be configured in the reverse of the signal processing procedure 1010 to 1060 of FIG. 3. For example, a wireless device (e.g., 100, 200 of FIG. 2) may receive a wireless signal from the outside through an antenna port/transceiver. The received wireless signal may be converted into a baseband signal through a signal recoverer. To this end, the signal recoverer may include a frequency downlink converter, an analog-to-digital converter (ADC), a CP canceller, and a fast Fourier transform (FFT) module. Thereafter, the baseband signal may be restored to a codeword through a resource de-mapper process, a postcoding process, a demodulation process, and a de-scrambling process. The codeword may be restored to the original information block through decoding. Thus, the signal processing circuit for the reception signal (not shown) may include a signal recoverer, a resource de-mapper, a postcoder, a demodulator, a de-scrambler and a decoder.

FIG. 4 shows another example of a wireless device to which the technical features of the present invention can be applied. The wireless device may be implemented in various forms depending on use cases / services (see FIG. 1).

Referring to FIG. 4, the

wireless devices

100, 200 may correspond to the

wireless devices

100, 200 of FIG. 2, and may be composed of various elements, components, units, and/or modules. For example, the

wireless device

100, 200 may include a communication unit 110, a control unit 120, a memory unit 130, and additional components 140. The communication unit 110 may include a communication circuitry 112 and transceiver(s) 114. For example, the communication circuitry 112 may include one or

more processors

102, 202 and/or one or

more memories

104, 204 of FIG. 2. For example, the transceiver(s) 114 may include one or

more transceivers

106, 206 and/or one or

more antennas

108, 208 of FIG. 2. The control unit 120 is electrically connected to the communication unit 110, the memory unit 130, and the additional components 140, and controls various operations of the

wireless device

100, 200. For example, the control unit 120 may control the electrical/mechanical operation of the

wireless device

100, 200 based on the program/code/command/information stored in the memory unit 130. In addition, the control unit 120 may transmit the information stored in the memory unit 130 to the outside (e.g., other communication devices) through the communication unit 110 through a wireless/wired interface, or may store the information received from the outside (e.g., other communication devices) through the wireless/wired interface through the communication unit 110 in the memory unit 130.

The additional components 140 may be variously configured according to the type of the

wireless device

100, 200. For example, the additional components 140 may include at least one of a power unit/battery, an input/output (I/O) unit, a driver, or a computing unit. Although not limited thereto, the

wireless devices

100, 200 may be implemented in the form of robots (FIG. 1, 100a), vehicles (FIG. 1, 100b-1, 100b-2), XR devices (FIG. 1, 100c), hand-held devices (FIG. 1, 100d), home appliances (FIG. 1, 100e), IoT devices (FIG. 1, 100f), terminals for digital broadcasting, hologram devices, public safety devices, machine-type communication (MTC) devices, medical devices, fin-tech devices (or financial devices), security devices, climate/environment devices, an AI server/devices (FIG. 1, 400), a base station (FIG. 1, 200), a network node, etc. The

wireless device

100, 200 may be used in a mobile or fixed location depending on use cases / services.

In FIG. 4, various elements, components, units, and/or modules within the

wireless device

100, 200 may be entirely interconnected via a wired interface, or at least a part of the

wireless device

100, 200 may be wirelessly connected through the communication unit 110. For example, in the

wireless device

100, 200, the control unit 120 and the communication unit 110 may be connected by wire, and the control unit 120 and the first unit (e.g., 130, 140) may be wirelessly connected through the communication unit 110. In addition, each element, component, unit, and/or module in the

wireless device

100, 200 may further include one or more elements. For example, the control unit 120 may be composed of one or more processor sets. For example, the control unit 120 may be configured as a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit 130 may include RAM, a dynamic RAM (DRAM), ROM, a flash memory, a volatile memory, a non-volatile memory, and/or combinations thereof.

Specifically, FIG. 5 shows a system architecture based on an evolved-UMTS terrestrial radio access network (E-UTRAN). The aforementioned LTE is a part of an evolved-UTMS (e-UMTS) using the E-UTRAN.

Referring to FIG. 5, the wireless communication system includes one or more user equipment (UE) 100, an E-UTRAN and an evolved packet core (EPC). The UE 100 refers to a communication equipment carried by a user. The UE 100 may be fixed or mobile. The UE 100 may be referred to as another terminology, such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, etc. The UE 100 may correspond to the wireless device 100x of FIG. 1, the first wireless device 100 of FIG. 2, or the wireless device 100 of FIG. 4.

The E-UTRAN consists of one or more evolved NodeB (eNB) 200. The eNB 200 provides the E-UTRA user plane and control plane protocol terminations towards the UE 100. The eNB 200 is generally a fixed station that communicates with the UE 100. The eNB 200 hosts the functions, such as inter-cell radio resource management (RRM), radio bearer (RB) control, connection mobility control, radio admission control, measurement configuration/provision, dynamic resource allocation (scheduler), etc. The eNB 200 may be referred to as another terminology, such as a base station (BS), a base transceiver system (BTS), an access point (AP), etc. The eNB 200 may correspond to the base station 200 of FIG. 1, the second wireless device 200 of FIG. 2, or the wireless device 200 of FIG. 4.

A downlink (DL) denotes communication from the eNB 200 to the UE 100. An uplink (UL) denotes communication from the UE 100 to the eNB 200. A sidelink (SL) denotes communication between the UEs 100. In the DL, a transmitter may be a part of the eNB 200, and a receiver may be a part of the UE 100. In the UL, the transmitter may be a part of the UE 100, and the receiver may be a part of the eNB 200. In the SL, the transmitter and receiver may be a part of the UEs 100.

The EPC includes a mobility management entity (MME), a serving gateway (S-GW) and a packet data network (PDN) gateway (P-GW). The MME hosts the functions, such as non-access stratum (NAS) security, idle state mobility handling, evolved packet system (EPS) bearer control, etc. The S-GW hosts the functions, such as mobility anchoring, etc. The S-GW is a gateway having an E-UTRAN as an endpoint. For convenience, MME/S-GW 300 will be referred to herein simply as a "gateway," but it is understood that this entity includes both the MME and S-GW. The P-GW hosts the functions, such as UE Internet protocol (IP) address allocation, packet filtering, etc. The P-GW is a gateway having a PDN as an endpoint. The P-GW is connected to an external network. The MME/S-GW 300 may correspond to the network 300 of FIG. 1.

The UE 100 is connected to the eNB 200 by means of the Uu interface. The UEs 100 are interconnected with each other by means of the PC5 interface. The eNBs 200 are interconnected with each other by means of the X2 interface. The eNBs 200 are also connected by means of the S1 interface to the EPC, more specifically to the MME by means of the S1-MME interface and to the S-GW by means of the S1-U interface. The S1 interface supports a many-to-many relation between MMEs / S-GWs and eNBs.

Specifically, FIG. 6 shows a system architecture based on a 5G NR. The entity used in the 5G NR (hereinafter, simply referred to as "NR") may absorb some or all of the functions of the entities introduced in FIG. 5 (e.g., eNB, MME, S-GW). The entity used in the NR may be identified by the name "NG" for distinction from the LTE/LTE-A.

Referring to FIG. 6, the wireless communication system includes one or more UE 100, a next-generation RAN (NG-RAN) and a 5th generation core network (5GC). The NG-RAN consists of at least one NG-RAN node. The NG-RAN node is an entity corresponding to the eNB 200 shown in FIG. 5. The NG-RAN node consists of at least one gNB 200 and/or at least one ng-eNB 200. The gNB 200 provides NR user plane and control plane protocol terminations towards the UE 100. The ng-eNB 200 provides E-UTRA user plane and control plane protocol terminations towards the UE 100. The gNB 200 and/or ng-eNB 200 may correspond to the base station 200 of FIG. 1, the second wireless device 200 of FIG. 2, or the wireless device 200 of FIG. 4.

The 5GC includes an access and mobility management function (AMF), a user plane function (UPF) and a session management function (SMF). The AMF hosts the functions, such as NAS security, idle state mobility handling, etc. The AMF is an entity including the functions of the conventional MME. The UPF hosts the functions, such as mobility anchoring, PDU handling. The UPF an entity including the functions of the conventional S-GW. The SMF hosts the functions, such as UE IP address allocation, PDU session control.

The gNBs 200 and ng-eNBs 200 are interconnected with each other by means of the Xn interface. The gNBs 200 and ng-eNBs 200 are also connected by means of the NG interfaces to the 5GC, more specifically to the AMF by means of the NG-C interface and to the UPF by means of the NG-U interface.

Hereinafter, frame structure/physical resources in NR is described.

In LTE/LTE-A, one radio frame consists of 10 subframes, and one subframe consists of 2 slots. A length of one subframe may be 1ms, and a length of one slot may be 0.5ms. Time for transmitting one transport block by higher layer to physical layer (generally over one subframe) is defined as a transmission time interval (TTI). A TTI may be the minimum unit of scheduling.

In NR, DL and UL transmissions are performed over a radio frame with a duration of 10ms. Each radio frame includes 10 subframes. Thus, one subframe corresponds to 1ms. Each radio frame is divided into two half-frames.

Unlike LTE/LTE-A, NR supports various numerologies, and accordingly, the structure of the radio frame may be varied. NR supports multiple subcarrier spacings in frequency domain. Table 1 shows multiple numerologies supported in NR. Each numerology may be identified by index μ.

μ	Subcarrier spacing (kHz)	Cyclic prefix	Supported for data	Supported for synchronization
0	15	Normal	Yes	Yes
1	30	Normal	Yes	Yes
2	60	Normal, Extended	Yes	No
3	120	Normal	Yes	Yes
4	240	Normal	No	Yes

Referring to Table 1, a subcarrier spacing may be set to any one of 15, 30, 60, 120, and 240 kHz, which is identified by index μ. However, subcarrier spacings shown in Table 1 are merely exemplary, and specific subcarrier spacings may be changed. Therefore, each subcarrier spacing (e.g., μ=0,1...4) may be represented as a first subcarrier spacing, a second subcarrier spacing...Nth subcarrier spacing.

Referring to Table 1, transmission of user data (e.g., PUSCH, PDSCH) may not be supported depending on the subcarrier spacing. That is, transmission of user data may not be supported only in at least one specific subcarrier spacing (e.g., 240 kHz).

In addition, referring to Table 1, a synchronization channel (e.g., a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH)) may not be supported depending on the subcarrier spacing. That is, the synchronization channel may not be supported only in at least one specific subcarrier spacing (e.g., 60 kHz).

One subframe includes N_symb ^subframe,μ = N_symb ^slot * N_slot ^subframe,μ consecutive OFDM symbols. In NR, a number of slots and a number of symbols included in one radio frame/subframe may be different according to various numerologies, i.e., various subcarrier spacings.

Table 2 shows an example of a number of OFDM symbols per slot (N_symb ^slot), a number of slots per radio frame (N_symb ^frame,μ), and a number of slots per subframe (N_symb ^subframe,μ) for each numerology in normal cyclic prefix (CP).

μ	Number of OFDM symbols per slot(N_symb ^slot)	Number of slots per radio frame (N_symb ^frame,μ)	Number of slots per subframe(N_symb ^subframe,μ)
0	14	10	1
1	14	20	2
2	14	40	4
3	14	80	8
4	14	160	16

Referring to Table 2, when a first numerology corresponding to μ=0 is applied, one radio frame includes 10 subframes, one subframe includes to one slot, and one slot consists of 14 symbols.

Table 3 shows an example of a number of OFDM symbols per slot (N_symb ^slot), a number of slots per radio frame (N_symb ^frame,μ), and a number of slots per subframe (N_symb ^subframe,μ) for each numerology in extended CP.

μ	Number of OFDM symbols per slot(N_symb ^slot)	Number of slots per radio frame (N_symb ^frame,μ)	Number of slots per subframe(N_symb ^subframe,μ)
2	12	40	4

Referring to Table 3, μ=2 is only supported in extended CP. One radio frame includes 10 subframes, one subframe includes to 4 slots, and one slot consists of 12 symbols.

In the present specification, a symbol refers to a signal transmitted during a specific time interval. For example, a symbol may refer to a signal generated by OFDM processing. That is, a symbol in the present specification may refer to an OFDM/OFDMA symbol, or SC-FDMA symbol, etc. A CP may be located between each symbol.

FIG. 7 shows an example of a frame structure to which technical features of the present invention can be applied. FIG. 8 shows another example of a frame structure to which technical features of the present invention can be applied.

In FIG. 7, a subcarrier spacing is 15 kHz, which corresponds to μ=0. In FIG. 8, a subcarrier spacing is 30 kHz, which corresponds to μ=1.

Meanwhile, a frequency division duplex (FDD) and/or a time division duplex (TDD) may be applied to a wireless communication system to which an embodiment of the present invention is applied. When TDD is applied, in LTE/LTE-A, UL subframes and DL subframes are allocated in units of subframes.

In NR, symbols in a slot may be classified as a DL symbol (denoted by D), a flexible symbol (denoted by X), and a UL symbol (denoted by U). In a slot in a DL frame, the UE shall assume that DL transmissions only occur in DL symbols or flexible symbols. In a slot in an UL frame, the UE shall only transmit in UL symbols or flexible symbols. The flexible symbol may be referred to as another terminology, such as reserved symbol, other symbol, unknown symbol, etc.

Table 4 shows an example of a slot format which is identified by a corresponding format index. The contents of the Table 4 may be commonly applied to a specific cell, or may be commonly applied to adjacent cells, or may be applied individually or differently to each UE.

Format

Symbol number in a slot

0

1

2

3

4

5

6

7

8

9

10

11

12

13

0

D

1

U

2

X

3

D

X

...

For convenience of explanation, Table 4 shows only a part of the slot format actually defined in NR. The specific allocation scheme may be changed or added.

The UE may receive a slot format configuration via a higher layer signaling (i.e., RRC signaling). Or, the UE may receive a slot format configuration via downlink control information (DCI) which is received on PDCCH. Or, the UE may receive a slot format configuration via combination of higher layer signaling and DCI.

The subframe structure shown in FIG. 9 may be called a self-contained subframe structure. Referring to FIG. 9, the subframe includes DL control channel in the first symbol, and UL control channel in the last symbol. The remaining symbols may be used for DL data transmission and/or for UL data transmission. According to this subframe structure, DL transmission and UL transmission may sequentially proceed in one subframe. Accordingly, the UE may both receive DL data and transmit UL acknowledgement/non-acknowledgement (ACK/NACK) in the subframe. As a result, it may take less time to retransmit data when a data transmission error occurs, thereby minimizing the latency of final data transmission.

In the self-contained subframe structure, a time gap may be required for the transition process from the transmission mode to the reception mode or from the reception mode to the transmission mode. For this purpose, some symbols at the time of switching from DL to UL in the subframe structure may be set to the guard period (GP).

An example shown in FIG. 10 is a time-frequency resource grid used in NR. An example shown in FIG. 10 may be applied to UL and/or DL.

Referring to FIG. 10, multiple slots are included within one subframe on the time domain. Specifically, when expressed according to the value of "μ", "14·2μ" symbols may be expressed in the resource grid. Also, one resource block (RB) may occupy 12 consecutive subcarriers. One RB may be referred to as a physical resource block (PRB), and 12 resource elements (REs) may be included in each PRB. The number of allocatable RBs may be determined based on a minimum value and a maximum value. The number of allocatable RBs may be configured individually according to the numerology ("μ"). The number of allocatable RBs may be configured to the same value for UL and DL, or may be configured to different values for UL and DL.

Hereinafter, a cell search in NR is described.

The UE may perform cell search in order to acquire time and/or frequency synchronization with a cell and to acquire a cell identifier (ID). Synchronization channels such as PSS, SSS, and PBCH may be used for cell search.

Referring to FIG. 11, the PSS and SSS may include one symbol and 127 subcarriers. The PBCH may include 3 symbols and 240 subcarriers.

The PSS is used for SS/PBCH block symbol timing acquisition. The PSS indicates 3 hypotheses for cell ID identification. The SSS is used for cell ID identification. The SSS indicates 336 hypotheses. Consequently, 1008 physical layer cell IDs may be configured by the PSS and the SSS.

The SS/PBCH block may be repeatedly transmitted according to a predetermined pattern within the 5ms window. For example, when L SS/PBCH blocks are transmitted, all of SS/PBCH block #1 through SS/PBCH block #L may contain the same information, but may be transmitted through beams in different directions. That is, quasi co-located (QCL) relationship may not be applied to the SS/PBCH blocks within the 5ms window. The beams used to receive the SS/PBCH block may be used in subsequent operations between the UE and the network (e.g., random access operations). The SS/PBCH block may be repeated by a specific period. The repetition period may be configured individually according to the numerology.

Referring to FIG. 11, the PBCH has a bandwidth of 20 RBs for the 2nd/4th symbols and 8 RBs for the 3rd symbol. The PBCH includes a demodulation reference signal (DM-RS) for decoding the PBCH. The frequency domain for the DM-RS is determined according to the cell ID. Unlike LTE/LTE-A, since a cell-specific reference signal (CRS) is not defined in NR, a special DM-RS is defined for decoding the PBCH (i.e., PBCH-DMRS). The PBCH-DMRS may contain information indicating an SS/PBCH block index.

The PBCH performs various functions. For example, the PBCH may perform a function of broadcasting a master information block (MIB). System information (SI) is divided into a minimum SI and other SI. The minimum SI may be divided into MIB and system information block type-1 (SIB1). The minimum SI excluding the MIB may be referred to as a remaining minimum SI (RMSI). That is, the RMSI may refer to the SIB1.

The MIB includes information necessary for decoding SIB1. For example, the MIB may include information on a subcarrier spacing applied to SIB1 (and MSG 2/4 used in the random access procedure, other SI), information on a frequency offset between the SS/PBCH block and the subsequently transmitted RB, information on a bandwidth of the PDCCH/SIB, and information for decoding the PDCCH (e.g., information on search-space/control resource set (CORESET)/DM-RS, etc., which will be described later). The MIB may be periodically transmitted, and the same information may be repeatedly transmitted during 80ms time interval. The SIB1 may be repeatedly transmitted through the PDSCH. The SIB1 includes control information for initial access of the UE and information for decoding another SIB.

Hereinafter, DL control channel in NR is described.

The search space for the PDCCH corresponds to aggregation of control channel candidates on which the UE performs blind decoding. In LTE/LTE-A, the search space for the PDCCH is divided into a common search space (CSS) and a UE-specific search space (USS). The size of each search space and/or the size of a control channel element (CCE) included in the PDCCH are determined according to the PDCCH format.

In NR, a resource-element group (REG) and a CCE for the PDCCH are defined. In NR, the concept of CORESET is defined. Specifically, one REG corresponds to 12 REs, i.e., one RB transmitted through one OFDM symbol. Each REG includes a DM-RS. One CCE includes a plurality of REGs (e.g., 6 REGs). The PDCCH may be transmitted through a resource consisting of 1, 2, 4, 8, or 16 CCEs. The number of CCEs may be determined according to the aggregation level. That is, one CCE when the aggregation level is 1, 2 CCEs when the aggregation level is 2, 4 CCEs when the aggregation level is 4, 8 CCEs when the aggregation level is 8, 16 CCEs when the aggregation level is 16, may be included in the PDCCH for a specific UE.

The CORESET is a set of resources for control signal transmission. The CORESET may be defined on 1/2/3 OFDM symbols and multiple RBs. In LTE/LTE-A, the number of symbols used for the PDCCH is defined by a physical control format indicator channel (PCFICH). However, the PCFICH is not used in NR. Instead, the number of symbols used for the CORESET may be defined by the RRC message (and/or PBCH/SIB1). Also, in LTE/LTE-A, since the frequency bandwidth of the PDCCH is the same as the entire system bandwidth, so there is no signaling regarding the frequency bandwidth of the PDCCH. In NR, the frequency domain of the CORESET may be defined by the RRC message (and/or PBCH/SIB1) in a unit of RB.

The base station may transmit information on the CORESET to the UE. For example, information on the CORESET configuration may be transmitted for each CORESET. Via the information on the CORESET configuration, at least one of a time duration of the corresponding CORESET (e.g., 1/2/3 symbol), frequency domain resources (e.g., RB set), REG-to-CCE mapping type (e.g., whether interleaving is applied or not), precoding granularity, a REG bundling size (when the REG-to-CCE mapping type is interleaving), an interleaver size (when the REG-to-CCE mapping type is interleaving) and a DMRS configuration (e.g., scrambling ID) may be transmitted. When interleaving to distribute the CCE to 1-symbol CORESET is applied, bundling of two or six REGs may be performed. Bundling of two or six REGs may be performed on the two symbols CORESET, and time first mapping may be applied. Bundling of three or six REGs may be performed on the three symbols CORESET, and a time first mapping may be applied. When REG bundling is performed, the UE may assume the same precoding for the corresponding bundling unit.

In NR, the search space for the PDCCH is divided into CSS and USS. The search space may be configured in CORESET. As an example, one search space may be defined in one CORESET. In this case, CORESET for CSS and CORESET for USS may be configured, respectively. As another example, a plurality of search spaces may be defined in one CORESET. That is, CSS and USS may be configured in the same CORESET. In the following example, CSS means CORESET in which CSS is configured, and USS means CORESET in which USS is configured. Since the USS may be indicated by the RRC message, an RRC connection may be required for the UE to decode the USS. The USS may include control information for PDSCH decoding assigned to the UE.

Since the PDCCH needs to be decoded even when the RRC configuration is not completed, CSS should also be defined. For example, CSS may be defined when a PDCCH for decoding a PDSCH that conveys SIB1 is configured or when a PDCCH for receiving MSG 2/4 is configured in a random access procedure. Like LTE/LTE-A, in NR, the PDCCH may be scrambled by a radio network temporary identifier (RNTI) for a specific purpose.

A resource allocation in NR is described.

In NR, a specific number (e.g., up to 4) of bandwidth parts (BWPs) may be defined. A BWP (or carrier BWP) is a set of consecutive PRBs, and may be represented by a consecutive subsets of common RBs (CRBs). Each RB in the CRB may be represented by CRB1, CRB2, etc., beginning with CRB0.

Referring to FIG. 12, multiple BWPs may be defined in the CRB grid. A reference point of the CRB grid (which may be referred to as a common reference point, a starting point, etc.) is referred to as so-called "point A" in NR. The point A is indicated by the RMSI (i.e., SIB1). Specifically, the frequency offset between the frequency band in which the SS/PBCH block is transmitted and the point A may be indicated through the RMSI. The point A corresponds to the center frequency of the CRB0. Further, the point A may be a point at which the variable "k" indicating the frequency band of the RE is set to zero in NR. The multiple BWPs shown in FIG. 12 is configured to one cell (e.g., primary cell (PCell)). A plurality of BWPs may be configured for each cell individually or commonly.

Referring to FIG. 12, each BWP may be defined by a size and starting point from CRB0. For example, the first BWP, i.e., BWP #0, may be defined by a starting point through an offset from CRB0, and a size of the BWP #0 may be determined through the size for BWP #0.

A specific number (e.g., up to four) of BWPs may be configured for the UE. Even if a plurality of BWPs are configured, only a specific number (e.g., one) of BWPs may be activated per cell for a given time period. However, when the UE is configured with a supplementary uplink (SUL) carrier, maximum of four BWPs may be additionally configured on the SUL carrier and one BWP may be activated for a given time. The number of configurable BWPs and/or the number of activated BWPs may be configured commonly or individually for UL and DL. Also, the numerology and/or CP for the DL BWP and/or the numerology and/or CP for the UL BWP may be configured to the UE via DL signaling. The UE can receive PDSCH, PDCCH, channel state information (CSI) RS and/or tracking RS (TRS) only on the active DL BWP. Also, the UE can transmit PUSCH and/or physical uplink control channel (PUCCH) only on the active UL BWP.

Referring to FIG. 13, 3 BWPs may be configured. The first BWP may span 40 MHz band, and a subcarrier spacing of 15 kHz may be applied. The second BWP may span 10 MHz band, and a subcarrier spacing of 15 kHz may be applied. The third BWP may span 20 MHz band and a subcarrier spacing of 60 kHz may be applied. The UE may configure at least one BWP among the 3 BWPs as an active BWP, and may perform UL and/or DL data communication via the active BWP.

A time resource may be indicated in a manner that indicates a time difference/offset based on a transmission time point of a PDCCH allocating DL or UL resources. For example, the start point of the PDSCH/PUSCH corresponding to the PDCCH and the number of symbols occupied by the PDSCH / PUSCH may be indicated.

Carrier aggregation (CA) is described. Like LTE/LTE-A, CA can be supported in NR. That is, it is possible to aggregate continuous or discontinuous component carriers (CCs) to increase the bandwidth and consequently increase the bit rate. Each CC may correspond to a (serving) cell, and each CC/cell may be divided into a primary serving cell (PSC)/primary CC (PCC) or a secondary serving cell (SSC)/secondary CC (SCC).

Hereinafter, integrated backhaul and access (IAB) is described.

Referring to FIG. 14, multiple nodes (i.e., node A/B/C) may multiplex access and backhaul links in time, frequency, or space (e.g., beam-based operation). Each node may provide access link to UE. Each node may provide backhaul to other node. Each node may referred to as relay transmission and reception point (rTRP).

The operation of the different links may be on the same or different frequencies (also termed 'in-band' and 'out-band' relays). While efficient support of out-band relays is important for some NR deployment scenarios, it is critically important to understand the requirements of in-band operation which imply tighter interworking with the access links operating on the same frequency to accommodate duplex constraints and avoid/mitigate interference.

In addition, operating NR systems in mmWave spectrum presents some unique challenges including experiencing severe short-term blocking that may not be readily mitigated by present RRC-based handover mechanisms due to the larger time-scales required for completion of the procedures compared to short-term blocking. Overcoming short-term blocking in mmWave systems may require fast RAN-based mechanisms for switching between nodes, which do not necessarily require involvement of the core network. The above described need to mitigate short-term blocking for NR operation in mmWave spectrum along with the desire for easier deployment of self-backhauled NR cells creates a need for the development of an integrated framework that allows fast switching of access and backhaul links. Over-the-air (OTA) coordination between nodes can also be considered to mitigate interference and support end-to-end route selection and optimization.

The following requirements and aspects should be addressed by the IAB for NR:

- Efficient and flexible operation for both in-band and out-band relaying in indoor and outdoor scenarios

- Multi-hop and redundant connectivity

- End-to-end route selection and optimization

- Support of backhaul links with high spectral efficiency

- Support of legacy NR UEs

In the present invention, a method for scheduling and/or coordinating transmission/reception directions and transmission/reception timing between links in an IAB environment is proposed. For the convenience, the present invention will be described on the assumption of an in-band environment, but the present invention can also be applied in an out-band environment. Also, the present invention will be described in consideration of an environment in which a donor node (e.g. donor gNB (DgNB)), a relay node (RN), and a UE operate in a half-duplex manner, but the present invention can also be applied in environments where DgNB, RN, and UE operate in a full-duplex manner.

In the present invention, when there are two nodes (DgNB, RN) and each node is node A and node B, and when node A schedules node B (i.e., node B is associated with node A), the backhaul link connecting the two nodes is referred to as nodeA-nodeB backhaul link. Similarly, when node A schedules UE 1 (i.e., UE 1 is associated with node A), the access link connecting node A and UE 1 is referred to as nodeA-UE1 access link. Node A may be called a parent node of node B. Node B may be called a child node of node A.

In the present invention, for convenience of description, backhaul links with IAB nodes scheduled by a specific IAB node are referred to as backhaul links of the corresponding IAB node, and an access link with a UE scheduled by a specific IAB node is referred to as an access link of the corresponding IAB node. For example, RN1-RN2 backhaul link and RN1-RN3 backhaul link become backhaul links of RN1, and RN1-UE2 access link and RN1-UE4 access link become access links of RN1.

In the present invention, for convenience of description, when there are RNs receiving and transmitting data from a specific DgNB to transmit/receive data to/from the UE, the backhaul links between the DgNB and the RNs are referred to as a backhaul link under the DgNB. Also, the access links between RNs connected by backhaul links under a particular DgNB and UEs are referred to as an access link under the DgNB.

Referring to FIG. 15, DgNB and UE1 is connected by access link, i.e., DgNB-UE1 access link. DgNB and RN1 is connected by backhaul link, i.e., DgNB-RN1 backhaul link. RN1 and UE2 is connected by access link, i.e., RN1-UE2 access link. RN1 and RN2 is connected by backhaul link, i.e., RN1-RN2 backhaul link. RN2 and UE3 is connected by access link, i.e., RN2-UE3 access link. Furthermore, the DgNB-RN1 backhaul link and the RN1-RN2 backhaul link become backhaul links under the DgNB. The DgNB-UE1 access link, the RN1-UE2 access link and the RN2-UE2 access link become access links under the DgNB.

In the present invention, the IAB node refers to a node, except the donor node, performing relaying operation between other IAB nodes and/or donor node. That is, the IAB node is connected by backhaul links with other IAB nodes and/or donor node, and connected by access link with UEs.

Hereinafter, various aspects of the present invention to support efficient IAB operation are described according to embodiments of the present invention.

1. Random access channel (RACH) configurations for IAB nodes

To support initial access for an IAB node, it is necessary to provide RACH resources. As the number of IAB nodes are relatively small compared to the number of UEs and also the latency required for IAB node's initial access can be larger than UE's initial access, efficient RACH resource configuration may seem necessary.

At least one of the following approaches may be considered for RACH configurations.

(1) RACH configurations for an IAB node may be shared with other configuration, and parameter 'X' may be further configured. In detail, one or a few preambles may be reserved for initial access of an IAB node. For example, at least one preamble configured for contention-free RACH procedure may be used for initial access of an IAB node. As preamble configured for contention-free RACH procedure are also needed for contention-free RACH procedure of a UE, a periodicity of the preamble used for initial access of an IAB node may be configured separately from a periodicity of the preamble used for contention-free RACH procedure of a UE. To this end, separate ratio parameter and/or times parameter (i.e., parameter 'X') may be configured. For example, the configured parameter X may be multiplied to the configured periodicity of RACH resources. In other words, RACH resources used for initial access of an IAB node may be present in every X times of physical random access channel (PRACH) occasion configured by the RACH configuration, which means that only a few preambles based on the RACH configuration may be used for initial access of an IAB node. As a new value set can be defined for the parameter X, it is not necessary to introduce a new RACH configuration used for initial access of an IAB node. The network may not allocate contention-free RACH resource of PRACH preamble which coincides.

(2) Separate RACH configurations may be configured for initial access of an IAB node. The separate RACH configurations for initial access of an IAB node may include at least one of the followings.

- PRACH format

- PRACH frequency locations (RACH occasions (ROs))

- Periodicity

(3) Separate initial UL BWP may be configured for initial access of an IAB node. The configuration for the separate initial UL BWP may include a separate PRACH configuration and/or other configurations related to the initial UL BWP. The initial UL BWP for IAB nodes may be defined which is superset of initial UL BWP of the UE. In other words, initial UL BWP for IAB node may be defined larger which still includes initial UL BWP of the UE.

Overall, resource sharing between PRACH resources for UEs and PRACH resources for IAB nodes may be achieved by the at least one of the following mechanisms.

(1) FDM: By allocating different number of FDM factors (e.g., msg1 -FrequencyStart, msg1 -FDM), PRACH resources for UEs and PRACH resources for IAB nodes may be separated. In computing/mapping between SS/PBCH block and PRACH RO, the IAB node may apply mapping between SS/PBCH block and PRACH RO separately based on the parameter for IAB nodes. If FDM starts from the lowest frequency of the active UL BWP, the IAB node may first map RACH resource of the UE, then map RACH resource of the IAB node. In other words, the lowest frequency to map RACH resource of the IAB node may be changed depending on PRACH configuration of the UE unless the first frequency for PRACH resource for IAB nodes is separately configured.

(2) Time division multiplexing (TDM): For TDM, separate configuration based on the current table may be used. However, this may have some restriction such that RACH resource for IAB node and UE may collide with each other. To address this issue, a new periodicity which may be larger than the currently supported periodicity. If the larger periodicity is configured, a new offset values may also be considered which is not used in PRACH configuration of the UE (e.g., offset = 3, 4...) in order to minimize the collision. If PRACH resources for IAB nodes and PRACH resources for UE collide with each other, colliding PRACH resources may be prioritized for access of UEs. In other words, PRACH resource for IAB nodes may become invalid if such collision occurs. This may be restricted only in the same frequency/time location or same preamble/frequency/time location or same time location.

(3) Spatial division multiplexing (SDM): Separating preambles may be considered. If this mechanism is used, as discussed before, impact on (legacy) UE should be minimized. For example, contention-free resource indication, or high speed related parameters may be used.

(4) FDM (and/or SDM) + TDM: combinations of the above mechanisms may also be considered.

To minimize confusion between random access response (RAR) for the UE and RAR for the IAB node (i.e., to minimize impact on access UEs), one or more of the following approaches may be considered.

(1) Random access RNTI (RA-RNTI): separate RA-RNTI for RAR for IAB nodes may be used. The RA-RNTI for RAR for IAB nodes may be configured/computed/determined separately from RA-RNTI for RAR for UEs.

For example, RA-RNTI may be determined by Equation 1.

[Equation 1]

RA_RNTI = 1 + s_id + 14*t_id+ 14*80*f_id + 14*80*8_ul_carrier_id

In Equation 1, s_id is the index of the first OFDM symbol of the PRACH occasion (0 ≤ s_id < 14), t_id is the index of the first slot of the PRACH occasion in a system frame (0 ≤ t_id < 80), where the subcarrier spacing to determine t_id is based on the value of μ configured by the higher layer. In Equation 1, f_id is the index of the PRACH occasion in the frequency domain (0 ≤ f_id < 8). In this case, f_id may be determined by msg1 -FDM for RACH configuration of the UE + f_id used in RACH resource of the IAB node. In other words, f_id for IAB node may have offset value for msg1 -FDM such that overlapping of RACH resources can be avoided. In Equation 1, ul_carrier_id is the UL carrier used for random access preamble transmission (0 for normal UL (NUL) carrier, and 1 for SUL carrier).

However, there may be confusion if the total number of PRACH resources for UE and PRACH resources for IAB nodes exceeds 8 for FDM. In such case, the following mechanism would be safer. It may also be considered to use different t_id or f_id or s_id. For example, the UE may use already defined range, e.g., t_id = 0...13 and t_id for IAB node may be one of 14, 15...27. For another example, f_id for UE may be one of 0...7 and f_id for IAB node may be one of 8...15.

For another example, RA-RNTI used for RAR for IAB nodes may be determined by Equation 2.

[Equation 2]

RA_RNTI = 1 + s_id + 14*t_id+ 14*80*f_id + 14*80*8_ul_carrier_id + 14*80*8*max_UL-carrier * 1 (or a constant value C)

In Equation 2, max_UL-carrier is the maximum number of UL carriers used for RACH procedure. In other words, this will allow different range of RA_RNTI between UEs and IAB nodes. If UL and SUL are only considered, max_UL-carrier may be 2. If there is only SUL without NUL for PCell or SCell with RACH transmission, the ul_carrier_id may be zero, and the max_UL-carrier may be 1.

(2) RAR window

At least in case UE and IAB node share the same RACH resources in time domain, RAR window may be separated without changing RA-RNTI. For example, RAR window starting time may be changed as the maximum RAR window of the UE. In other words, RAR window for IAB nodes may be constructed after completing RAR window for UEs. This may only be applied when RACH resources for IAB nodes and UEs are collided in time-domain and/or RA-RNTIs are shared between two.

(3) RAR search space

Separate RAR search space may be configured for UEs and IAB nodes. RAR search space for IAB nodes may be configured in SIB1 for RACH procedure of IAB nodes. In other words, RAR multiplexing between UE and IAB node may not be assumed.

The present invention described above may be applied to the embodiment shown in FIG. 16. In this example, the first node and the second node may be IAB nodes.

In step S1600, the first node receives a first preamble from a UE. In step S1610, the first node receives a second preamble from a second node.

A configuration related to the first preamble and the second preamble may be configured separately. The configuration may include at least one of a PRACH format for the first preamble and the second preamble, PRACH frequency location in which the first preamble and the second preamble are received, or a periodicity of the first preamble and the second preamble. An initial UL BWP in which the first preamble is received and an initial UL BWP in which the second preamble is received may be configured separately. A periodicity of the second preamble may be same as a periodicity of the first preamble multiplied by a ratio parameter. A resource for the first preamble and a resource for the second preamble may be multiplexed by at least one of FDM, TDM, or SDM.

In step S1620, the first node transmits a first RAR addressed by a first RA-RNTI as a response to the first preamble to the UE. In step S1630, the first node transmits a second RAR addressed by a second RA-RNTI as a response to the second preamble to the second node. A first set of RA-RNTIs to which the first RA-RNTI belongs and a second set of RA-RNTIs to which the second RA-RNTI belongs are not overlapped with each other.

More specifically, the first RA-RNTI may be determined based on an index of a PRACH occasion in a frequency domain (i.e., f_id), and the second RA-RNTI may be determined based on the index of the PRACH occasion in the frequency domain (i.e., f_id)and an offset value.

The first RA-RNTI may be determined based on a first index of a first symbol of a PRACH occasion (i.e., s_id) which is from a first set of symbol indices, and the second RA-RNTI may be determined based on a second index of the first symbol of the PRACH occasion (i.e., s_id) which is from a second set of symbol indices. The first set of symbol indices and the second set of symbol indices may not be overlapped with each other.

The first RA-RNTI may be determined based on a first index of a first slot of a PRACH occasion in a system frame (i.e., t_id) which is from a first set of slot indices, and the second RA-RNTI is determined based on a second index of the first slot of the PRACH occasion in the system frame (i.e., t_id) which is from a second set of slot indices. The first set of slot indices and the second set of slot indices may not be overlapped with each other.

The second RA-RNTI may be determined based on a maximum number of UL carriers.

A search space for the first RAR and a search space for the second RAR may be configured separately.

According to the embodiment of the present invention shown FIG. 16, RA-RNTI used for initial access of IAB node and RA-RNTI used for initial access of UE can be separated. Therefore, the parent node which receives random access preamble from both IAB node and UE can differentiate random access response for IAB node and random access response for UE, and therefore, RAR confusion can be avoided.

2. Dynamic resource sharing

Particularly, the present invention discusses how to maximize dynamic resource sharing (or, dynamic resource adaptation) among IAB nodes. The dynamic resource sharing means that a set of resources not used by parent node(s) are used by child node's access and/or backhaul links towards its child node(s) and UEs.

In general, TDM pattern for the dynamic resource sharing may be configured semi-statically, and each IAB node may perform transmission and/or reception based on the semi-statically configured resources. For example, if a semi-statically configured TDM pattern states 'DUDU' for each slot in every 4 slots, it may imply that an IAB node may perform transmission in the first and third slots whereas the IAB node may perform reception in the second and fourth slots. The semi-statically configured TDM pattern may be constructed by an IAB node and forwarded to its child node(s) and/or parent node(s) such that other IAB nodes can also determine its TDM pattern for the dynamic resource sharing. Or, an IAB and/or donor node may determine a TDM pattern for another IAB node and/or donor node and may inform the determined TDM pattern to other nodes. The semi-statically configured TDM pattern may be considered as an intended DL/UL resources and/or TX/RX resources, and actual usage of resources may be changed.

In detail, dynamic resource sharing among resources indicated as downlink (may be denoted as 'D') and/or flexible (may be denoted as 'X') by a parent node may be adapted to other resources by one of its child node(s) if the child node acquires information that the parent node is not going to transmit any data to itself. In other words, the child may not be required to monitor potential DL transmission from the parent node. To support this, at least one of the followings may be considered.

(1) A group common and/or UE-specific DCI may indicate intended beams (potentially) used in the current slot and/or in a set of slots (next slots potentially including the current slot). If there is no indication of the beam which is used to communicate between a parent node and a child node, the child node may assume there will be no DL transmission from the parent node during the indicated period. With the above assumption, the resource during the indicated period may be used for other purposes such as UL resources from its child node(s) or UEs and/or DL resources to its child node(s) or UEs.

(2) A group common and/or UE-specific DCI which indicates D/U resources on semi-statically configured flexible resources may indicate flexible resource, and the indicated flexible resource by dynamic indication may not be used. That is, if the parent nodes indicates a certain set of resources as flexible by dynamic indication/signaling, it may be considered that such indicated resources are not used by the parent node so that the child node can use the resources for DL and/or UL. The signaling may be UE-specific and/or beam-specific. The signaling may be transmitted per each beam.

(3) UE-specific cross-slot scheduling based approach may be used. At least for DL, if an IAB node/UE receives a cross-slot scheduling DCI for PDSCH, the IAB node/UE may assume that the resources located between end of the scheduling DCI and start of the scheduled PDSCH are not used for DL transmission. The IAB node/UE may be allowed to skip monitoring control channel during that interval.

If there is any semi-statically configured resources such as semi-persistent (SPS) PDSCH and/or semi-statically configured CSI RS transmission or SS/PBCH block transmission, at least one of the following approaches may be considered.

- During the interval, measurement and/or SPS PDSCH can also be allowed to be skipped.

- During the interval, only measurements may be allowed to be skipped, whereas SPS PDSCH may be expected to be monitored.

- During the interval, only SPS PDSCH may be expected to be skipped, whereas measurements may be expected to be performed.

- During the interval, all semi-statically configured DL resources may be considered as valid so that the IAB node/UE may be expected to monitor on the configured resources.

Whether the IAB node/UE can skip monitoring control channel during cross-slot scheduling may be configured explicitly or implicitly. For the explicit configuration, whether the IAB node/UE can skip monitoring control channel during cross-slot scheduling may also be configured per RNTI and/or CORESET and/or search space set. For an example of the implicit configuration, a certain set of RNTIs based scheduling may be associated with skipping monitoring control channel, and/or a set of search space or CORESET may be configured for skipping monitoring control channel.

In terms of HARQ-ACK codebook generation, particularly with semi-static codebook, it may be still assumed that all the configured search space and/or CORESET is valid regardless of whether the IAB node/UE skips monitoring on certain search space monitoring occasions or not.

Furthermore, duration of skipping monitoring control channel may be clarified by at least one of the followings.

(1) From the next symbol of the end of CORESET where the scheduling DCI is scheduled to the right before ODFM symbol of the first OFDM symbol of the scheduled PDSCH

(2) From next symbol of the end of monitoring chunk where the scheduling DCI is scheduled/included to the right before OFDM symbol of the first OFDM symbol of the scheduled PDSCH: The monitoring chunk may be defined as a set of contiguous OFDM symbols where one or more CORESETs are configured with one or more search space monitoring occasion. For example, if two CORESETs are configured with one symbol duration and each CORESET are consecutively configured to be monitored by two sets of search space, it may be considered as one monitoring chunk even though it includes more than one search space set.

(3) Additional gap may be added to the starting OFDM symbol mentioned above in (1) or (2). For example, since there may be latency of control channel decoding, it may be considered that an IAB node/UE is still expected to perform normal operation for the next few OFDM symbols which are needed for control channel decoding. The additional gap may be fixed (e.g., same size as the CORESET or monitoring chunk) and/or indicated by the IAB node/UE or configured by the parent node/donor node (or an IAB node for a UE).

More detail description for how to apply the present invention in different scenarios will be described below.

A. TDM approach 1: TDM between parent nodes and child nodes (or between gNB part (i.e., distributed unit (DU) of an IAB node) and UE part (i.e., mobile terminal (MT) part of an IAB node)

In this approach, resources may be partitioned when TDM is used within an IAB node based on its functionality, i.e., gNB functionality (DU part) vs UE functionality (MT part). As donor node does not have UE functionality, TDM may not be necessary for the donor node. If half-duplex constraints are needed as a single carrier is used for DL and UL spectrum, or the IAB node may only support half-duplex capability, TDM may be also constructed/established among DL and UL per each TDM unit (i.e., gNB functionality unit and UE functionality unit respectively).

Referring to FIG. 17, a TDM pattern for each node is configured as follows.

- Donor node: [DUDU] (DgNB (a) in FIG. 17)

- 1^st hop IAB node: [D_ue, U_ue, D_gnb, U_gnb] (RN (b) in FIG. 17)

- 2^nd hop IAB node: [D_gnb, U_gnb, D_ue, U_ue] (RN (c) in FIG. 17)

- 3^rd hop IAB node: [D_ue, U_ue, D_gnb, U_gnb] (RN (d) in FIG. 17)

To address cross-link interference, the following TDM pattern may be also considered

- Donor node: [DUXXDU]

- 1^st hop IAB node: [D_ue, U_ue, D_gnb, U_gnb, X, X]

- 2^nd hop IAB node: [X, X, D_ue, U_ue, D_gNB, U_gnb]

- 3rd hop IAB node: [D_gnb, U_gnb, D_ue, U_ue, X, X]

When such TDM patterns are used, mechanisms to dynamically utilize resources may be as follows. For convenience, RN (b) in FIG. 17 is exemplarily described. However, the same behavior may be applied to other IAB nodes where different timing may be assumed depending on the configured/assumed TDM pattern. As RN(b) is the first hop IAB node, TDM pattern may be assumed that “D_ue, U_ue, D_gnb, U_gnb”. In the slot(s) of “D_ue”, the RN (b) is expected to listen from its parent node (in this case, DgNB (a)). If the parent node does not have any data to transmit to the node, the resource allocated as D_ue can be wasted. Such resources can be used for access link (except for the node's child node(s) as its child node(s) are not listening on with resource allocation of D_gnb, U_gnb (i.e., support access UEs and child IAB nodes).

Two categories may be considered for resource partitioning mechanisms, i.e., (1) semi-static only configuration, and (2) semi-static configuration + dynamic configuration.

(1) Semi-static only configuration

At least one of the following approaches may be considered and one or more of combined approaches may be jointly used to indicate resources for IAB operation.

1) Each donor node and/or IAB node may determine DL/UL resources only for its child node(s) and UEs.

The information on DL/UL resources may be indicated by explicit signaling to its child node(s) and UEs. The information on DL/UL resources may also be forwarded to its parent node(s) such that parent node(s) can determine which resources are available for communicating with the child node. For example, such information may be indicated to UEs by slot format indicator (SFI), and may be indicated to IAB node(s) by semi-static signaling. Upon receiving the information from the parent node(s), an IAB node may determine its resources for its child node(s) and UEs. If a slot is indicated as 'D' by both a parent node and child node, it may imply that the indicated slot may be used only for access link, because the child node cannot listen on DL transmission of the parent node.

In the explicit indication on DL/UL resources, resources usable by child node(s) (and potentially UEs for sidelink operation, etc.) for its DL/UL operation may also be explicitly indicated. Flexible resource may be reused for indicating resources usable by child node(s) (and potentially UEs) or different resource type may be further defined (e.g., 'child node resource (C)'). Upon receiving the information, child node(s) (and potentially UE) may determine DL and UL resources for its child node(s) and UE(s) among resources indicated by its parent node(s). This approach is rather top-down. The flexible resources (F) or child node resource (C) may be only used by child node(s) (or UE(s)) for its operation of transmission/reception to/from non-parent node(s).

2) A parent node may indicate resource pattern for each child node. The resource pattern for the child node may include resources potentially used for backhaul DL for that child node, backhaul UL for that child node, DL resources for that child node for its child node(s) and UEs, UL resources for that child node for its child node(s) and UEs.

In other words, a parent node may determine resource pattern for each child node, and the child node may follow the indicated resource pattern. A child node may also determine resource patterns of its child node(s) based on the indicated resource pattern from its parent node. For example, resources not indicated as backhaul DL or backhaul UL may be allocated for a child node. If SDM and/or FDM is allowed between backhaul DL and access UL between links of parent node-specific node and specific node-child node, it may be considered that backhaul DL/UL from parent nodes may also be indicated as backhaul links for its child node(s). In other words, one IAB node may determine resources of its child IAB nodes based on multiplexing schemes (e.g., TDM, FDM, SDM) and the child node may use resources indicated by its parent node. The similar scheme may also be applied to the above mechanisms.

3) A donor node may determine all resources for its child nodes and grand-child nodes. The indication on resource allocation may include only information on resources used in each IAB node for gNB functionality and/or may include information on both backhaul and access resources.

In addition, for semi-static only configuration, resources indicated by semi-static configuration for DL or UL (or backhaul DL, backhaul UL, access DL, access UL), at least one of the following approaches may be considered.

1) Unless a parent node explicitly/implicitly indicates otherwise, the resources indicated as DL or UL may be used as DL or UL. Corresponding child node(s) or UEs may be expected to monitor in DL resources and may transmit data based on configuration or scheduling in UL resources.

2) Even though DL or uplink is indicated, unless configured/scheduled otherwise, it may be flexible for its child node(s). For example, even if resources are configured as DL in a set of slots, if there is no CORESET, RS, measurement, a configuration to utilize such DL resources or dynamic scheduling to utilize such DL resources in the set of slots, it is possible to utilize the resources for other purposes (e.g., access link of that node). If this approach is used, the following assumption may be further needed.

- The symbols where search space sets are configured in the indicated DL resources are considered as DL.

- The symbols where search space sets are configured in the indicated flexible resources or child node resource may be considered as invalid for link of parent node-child node.

- Additional T OFDM symbols after each search space set or search space burst (a set of consecutive OFDM symbols of search space sets) may be assumed to be DL in the resources which are indicated as DL. If the resources are indicated as flexible resources or child node resource, it may be considered invalid.

- OFDM symbols indicated as SPS PDSCH or scheduled PDSCH may be considered as DL in the configured DL resources. If the resources are indicated as flexible resources or child node resource, it may be considered invalid.

In the invalid resource, the scheduled or configured resources may be cancelled or it may be assumed that the configuration or scheduling may become ineffective.

(2) Semi-static configuration + dynamic configuration

In the semi-static configuration + dynamic configuration, the following approaches may be considered.

1) Semi-static configuration may indicate fixed DL or UL resource which are assumed to be used as DL or UL without modification, and dynamic configuration may indicate DL or UL resource for the resources indicated as flexible by semi-static configuration. In semi-statically configured DL/UL resources, dynamic usage may be determined as mentioned above. For dynamically indicated DL/UL resource, similar mechanisms as semi-statically configured resource may be applied for resource shift.

2) Semi-static configuration may indicate intended DL/UL configuration and/or intended resource partitioning, and the intended DL/UL configuration and/or intended resource partitioning may be updated based on the dynamic configuration. If there is no dynamic configuration, intended DL/UL configuration and/or intended resource partitioning may be used as it is. That is, the dynamic configuration may update semi-statically configured intended DL/UL configuration.

3) Semi-static configuration may indicate potential set of DL/UL configurations, and dynamic configuration may select one pattern/configuration among the semi-statically configured resources/patterns.

Dynamic configuration may include MAC control element (CE), group-common DCI or UE-specific DCI.

B. TDM approach 2: TDM between backhaul and access links

For this approach, similar scheme as "A. TDM approach 1" may be considered. In this case, instead that a slot or one resource unit can be used for DL to schedule both a child node and UE, the resource may be used for either child node(s) or UEs in DL. From an IAB node perspective, DL from a parent node and UL from a child node may be jointly received. In this sense, when a parent node indicates DL resource, the IAB node may also indicate UL resource of that resource to its child node(s). In this sense, it is more natural that each parent node determines a set of resources used for backhaul resources for DL and potentially UL from its child node.

In view of the exemplary systems described herein, methodologies that may be implemented in accordance with the disclosed subject matter have been described with reference to several flow diagrams. While for purposed of simplicity, the methodologies are shown and described as a series of steps or blocks, it is to be understood and appreciated that the claimed subject matter is not limited by the order of the steps or blocks, as some steps may occur in different orders or concurrently with other steps from what is depicted and described herein. Moreover, one skilled in the art would understand that the steps illustrated in the flow diagram are not exclusive and other steps may be included or one or more of the steps in the example flow diagram may be deleted without affecting the scope of the present disclosure.

Claims in the present description can be combined in a various way. For instance, technical features in method claims of the present description can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method.

Claims

A method performed by a first node in a wireless communication system, the method comprising:

receiving a first preamble from a user equipment (UE);

receiving a second preamble from a second node;

transmitting a first random access response (RAR) addressed by a first random access radio network temporary identifier (RA-RNTI) as a response to the first preamble to the UE; and

transmitting a second RAR addressed by a second RA-RNTI as a response to the second preamble to the second node,

wherein a first set of RA-RNTIs to which the first RA-RNTI belongs and a second set of RA-RNTIs to which the second RA-RNTI belongs are not overlapped with each other.
The method of claim 1, wherein the first RA-RNTI is determined based on an index of a physical random access channel (PRACH) occasion in a frequency domain, and

wherein the second RA-RNTI is determined based on the index of the PRACH occasion in the frequency domain and an offset value.
The method of claim 1, wherein the first RA-RNTI is determined based on a first index of a first symbol of a PRACH occasion which is from a first set of symbol indices,

wherein the second RA-RNTI is determined based on a second index of the first symbol of the PRACH occasion which is from a second set of symbol indices, and

wherein the first set of symbol indices and the second set of symbol indices are not overlapped with each other.
The method of claim 1, wherein the first RA-RNTI is determined based on a first index of a first slot of a PRACH occasion in a system frame which is from a first set of slot indices,

wherein the second RA-RNTI is determined based on a second index of the first slot of the PRACH occasion in the system frame which is from a second set of slot indices, and

wherein the first set of slot indices and the second set of slot indices are not overlapped with each other.
The method of claim 1, wherein the second RA-RNTI is determined based on a maximum number of uplink (UL) carriers.
The method of claim 1, wherein a search space for the first RAR and a search space for the second RAR are configured separately.
The method of claim 1, wherein a configuration related to the first preamble and the second preamble are configured separately.
The method of claim 7, wherein the configuration includes at least one of a PRACH format for the first preamble and the second preamble, PRACH frequency location in which the first preamble and the second preamble are received, or a periodicity of the first preamble and the second preamble.
The method of claim 1, wherein an initial UL bandwidth part (BWP) in which the first preamble is received and an initial UL BWP in which the second preamble is received are configured separately.
The method of claim 1, wherein a periodicity of the second preamble is same as a periodicity of the first preamble multiplied by a ratio parameter.
The method of claim 1, wherein a resource for the first preamble and a resource for the second preamble are multiplexed by at least one of a frequency division multiplexing (FDM), a time division multiplexing (TDM), or a spatial division multiplexing (SDM).
The method of claim 1, wherein the first node and the second node are integrated access and backhaul (IAB) nodes.
The method of claim 1, wherein the first node is in communication with at least one of a mobile device, a network, and/or autonomous vehicles other than the first node.
A first node in a wireless communication system, the first node comprising:

a memory;

a transceiver; and

a processor, operably coupled to the memory and the transceiver,

wherein the first node is configured to:

receive a first preamble from a user equipment (UE),

receive a second preamble from a second node,

transmit a first random access response (RAR) addressed by a first random access radio network temporary identifier (RA-RNTI) as a response to the first preamble to the UE, and

transmit a second RAR addressed by a second RA-RNTI as a response to the second preamble to the second node,

wherein a first set of RA-RNTIs to which the first RA-RNTI belongs and a second set of RA-RNTIs to which the second RA-RNTI belongs are not overlapped with each other.