WO2019194574A1

WO2019194574A1 - Method and apparatus for supporting relay operation for urllc in wireless communication system

Info

Publication number: WO2019194574A1
Application number: PCT/KR2019/003942
Authority: WO
Inventors: Yunjung Yi
Original assignee: Lg Electronics Inc.
Priority date: 2018-04-03
Filing date: 2019-04-03
Publication date: 2019-10-10

Abstract

A method and apparauts supporting a relaying operation for ultra-reliable and low latency communications (URLLC) service is provided. A user equipment (UE) receives data via a physical downlink shared channel (PDSCH) from a network, receives an uplink (UL) grant from the network, copying the data to a physical uplink shared channel (PUSCH) scheduled by the UL grant, and transmits the copied data to a target UE via the PUSCH. That is, L1-type relaying operation is supported for the URLLC service.

Description

METHOD AND APPARATUS FOR SUPPORTING RELAY OPERATION FOR URLLC IN WIRELESS COMMUNICATION SYSTEM

The present invention relates to wireless communications, and more particularly, to a method and apparatus for supporting a relay operation for ultra-reliable and low latency communications (URLLC) in a new radio access technology (RAT) 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.

URLLC correspond to services for latency sensitive devices for applications like factory automation, autonomous driving, and remote surgery. These applications require sub-millisecond latency with error rates that are lower than 1 packet loss in 10⁵ packets.

The present invention discusses mechanisms to provide high reliability and low latency services via relay operation.

In an aspect, a method for performed by a relay user equipment (UE) in a wireless communication system is provided. The method includes receiving data via a physical downlink shared channel (PDSCH) from a network, receiving an uplink (UL) grant from the network, copying the data to a physical uplink shared channel (PUSCH) scheduled by the UL grant, and transmitting the copied data to a target UE via the PUSCH.

In another aspect, a relay user equipment (UE) in a wireless communication system is provided. The relay UE includes a memory, a transceiver, and a processor, operably coupled to the memory and the transceiver, and configured to control the transceiver to receive data via a physical downlink shared channel (PDSCH) from a network, control the transceiver to receive an uplink (UL) grant from the network, copy the data to a physical uplink shared channel (PUSCH) scheduled by the UL grant, and control the transceiver to transmit the copied data to a target UE via the PUSCH.

In another aspect, a processor for a wireless communication device in a wireless communication system is provided. The processor is configured to control the wireless communication device to receive data via a physical downlink shared channel (PDSCH) from a network, receive an uplink (UL) grant from the network, copy the data to a physical uplink shared channel (PUSCH) scheduled by the UL grant, and transmit the copied data to a target UE via the PUSCH.

The spectral efficiency can be increased by relay operation.

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

FIG. 2 shows another example of a wireless communication system to which technical features of the present invention can be applied.

FIG. 3 shows an example of a frame structure to which technical features of the present invention can be applied.

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

FIG. 5 shows an example of a subframe structure used to minimize latency of data transmission when TDD is used in NR.

FIG. 6 shows an example of a resource grid to which technical features of the present invention can be applied.

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

FIG. 8 shows an example of a frequency allocation scheme to which technical features of the present invention can be applied.

FIG. 9 shows an example of multiple BWPs to which technical features of the present invention can be applied.

FIG. 10 shows an example of transmission of two data with different latency requirement.

FIG. 11 shows an example of relaying operation by the relay UE according to an embodiment of the present invention.

FIG. 12 shows an example of a method for performing relaying operation by a relay UE according to an embodiment of the present invention.

FIG. 13 shows a UE to implement an embodiment of the present invention.

FIG. 14 shows more detailed UE to implement an embodiment of the present invention.

FIG. 15 shows a network node or target UE to implement an embodiment of the present invention.

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 (DL). 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."

FIG. 1 shows an example of a wireless communication system to which technical features of the present invention can be applied. Specifically, FIG. 1 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. 1, the wireless communication system includes one or more user equipment (UE; 10), an E-UTRAN and an evolved packet core (EPC). The UE 10 refers to a communication equipment carried by a user. The UE 10 may be fixed or mobile. The UE 10 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 E-UTRAN consists of one or more base station (BS) 20. The BS 20 provides the E-UTRA user plane and control plane protocol terminations towards the UE 10. The BS 20 is generally a fixed station that communicates with the UE 10. The BS 20 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 BS may be referred to as another terminology, such as an evolved NodeB (eNB), a base transceiver system (BTS), an access point (AP), etc.

A downlink (DL) denotes communication from the BS 20 to the UE 10. An uplink (UL) denotes communication from the UE 10 to the BS 20. A sidelink (SL) denotes communication between the UEs 10. In the DL, a transmitter may be a part of the BS 20, and a receiver may be a part of the UE 10. In the UL, the transmitter may be a part of the UE 10, and the receiver may be a part of the BS 20. In the SL, the transmitter and receiver may be a part of the UE 10.

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 30 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 UE 10 is connected to the BS 20 by means of the Uu interface. The UEs 10 are interconnected with each other by means of the PC5 interface. The BSs 20 are interconnected with each other by means of the X2 interface. The BSs 20 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 BSs.

FIG. 2 shows another example of a wireless communication system to which technical features of the present invention can be applied. Specifically, FIG. 2 shows a system architecture based on a 5G new radio access technology (NR) system. The entity used in the 5G NR system (hereinafter, simply referred to as "NR") may absorb some or all of the functions of the entities introduced in FIG. 1 (e.g. eNB, MME, S-GW). The entity used in the NR system may be identified by the name "NG" for distinction from the LTE.

In the following description, for NR, 3GPP TS 38 series (3GPP TS 38.211, 38.212, 38.213, 38.214, 38.331, etc.) can be referred to in order to facilitate understanding of the following description.

Referring to FIG. 2, the wireless communication system includes one or more UE 11, 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 BS 20 shown in FIG. 1. The NG-RAN node consists of at least one gNB 21 and/or at least one ng-eNB 22. The gNB 21 provides NR user plane and control plane protocol terminations towards the UE 11. The ng-eNB 22 provides E-UTRA user plane and control plane protocol terminations towards the UE 11.

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, protocol data unit (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 and ng-eNBs are interconnected with each other by means of the Xn interface. The gNBs and ng-eNBs 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. physical uplink shared channel (PUSCH), physical downlink shared channel (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. 3 shows an example of a frame structure to which technical features of the present invention can be applied. In FIG. 3, a subcarrier spacing is 15 kHz, which corresponds to μ=0.

FIG. 4 shows another example of a frame structure to which technical features of the present invention can be applied. In FIG. 4, 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. radio resource control (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.

FIG. 5 shows an example of a subframe structure used to minimize latency of data transmission when TDD is used in NR. The subframe structure shown in FIG. 5 may be called a self-contained subframe structure.

Referring to FIG. 5, 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).

FIG. 6 shows an example of a resource grid to which technical features of the present invention can be applied. An example shown in FIG. 6 is a time-frequency resource grid used in NR. An example shown in FIG. 6 may be applied to UL and/or DL.

Referring to FIG. 6, 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.

FIG. 7 shows an example of a synchronization channel to which technical features of the present invention can be applied. Referring to FIG. 7, 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 synchronization signal (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. 7, 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.

FIG. 8 shows an example of a frequency allocation scheme to which technical features of the present invention can be applied. Referring to FIG. 8, 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. 8 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. 8, 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.

FIG. 9 shows an example of multiple BWPs to which technical features of the present invention can be applied. Referring to FIG. 9, 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).

If data with higher importance of latency (e.g. ultra-reliable low-latency communication (URLLC) data) and data with relatively lower importance of latency (e.g. enhanced mobile broadband (eMBB) data) can be multiplexed and transmitted on the same frequency resources of the same cell, collision of transmission resources between two data may occur. Since transmission of data in which latency is important is prioritized generally, referring to FIG. 10, the data with higher importance of latency (PDSCH 2) may be transmitted by puncturing resources for the data with lower importance of latency (PDSCH 1). In this case, the data with lower importance of latency (PDSCH 1) is generally transmitted with a longer TTI length than the data with higher importance of latency (PDSCH 2), so that some OFDM symbols of the data with lower importance of latency (PDSCH 1) is punctured for transmission of the data with higher importance of latency (PDSCH 2). In this case, data of which some resource is punctured experiences interference in the corresponding resource, resulting in a large performance degradation.

In the present invention, for convenience of description, a channel through which DL data is transmitted is referred to as a PDSCH, and a channel through which UL data is transmitted is referred to as a PUSCH. The present invention will be described mainly in DL environment (transmission of PDSCH) for convenience of explanation, but it is obvious that the present invention can also be applied to UL environment (transmission of PUSCH).

To provide reliable communication with low latency, particularly, for high-medium traffic rate, it is essential to achieve reasonable spectral efficiency. The relay operation can provide reliability, particularly, for a UE in the coverage edge. There are cases where a UE requires URLLC services while the UE is located at the edge of cell boundary. In such case, enhancements on reliability require some techniques to further reduce either interference or enhance the signal strength. To reduce the interference, inter-cell interference coordination may be performed, and UE in coverage edge can be supported with reduced interference (and thus enhance signal to interference and noise ratio (SINR)). However, performing inter-cell interference coordination may not be effective for low latency cases, since coordinated resources for low interference may not occur very often. To achieve ultra-reliability with low latency, it is thus necessary to enhance signal strength. One of candidate mechanism to enhance signal strength is to forward data via relaying operation. Generally, relaying operation requires special equipment like relay NodeB (NB) or UE-relay nodes. However, this requires extra hardware which may not be so effective for infrequent URLLC use cases.

Thus, the present invention proposes relaying technique which requires low specification and hardware impact to balance cost and required quality of service (QoS). In other words, the present invention proposes mechanisms to utilize existing UEs with minimal changes to support relaying operation. To support the relaying operation according to the present invention, the network may schedule different resources for DL/UL scheduling for relaying operation, and the relay UE may repeat received UL or DL data on the scheduled DL/UL resource for relaying operation.

To support such a low cost/impact relaying operation, the present invention proposes a few mechanisms as follows, which focuses on UE-type relaying operation instead of gNB-type relaying operation. For UE-type relaying operation, the present invention further focuses on L1-type relaying operation, which means that the relaying operation would occur at physical layer of the relay UE. That is, the relay UE receives data from the network, and just repeats the received data to transmit to the target UE for relaying operation. Compared to existing relaying operation, the present invention offers unique benefits as follows:

- As relaying operation occurs at the physical layer, the latency can be reduced by reducing forward latency.

- Relaying operation is based on network scheduling by using regular PUSCH for forwarding to the target UE. Thus, resource allocation and/or resource sharing between access link (i.e. link between the relay UE and the target UE) and backhaul link (i.e. link between the gNB and the relay UE) can be simplified. No complicated resource sharing mechanism is not needed.

- For at least DL relaying operation, regular PUSCH and PDSCH are used between the relay UE and the target UE and/or between the gNB and the relay UE. Thus, additional impact on the relay UE beyond regular UE can be minimized.

FIG. 11 shows an example of relaying operation by the relay UE according to an embodiment of the present invention. In FIG. 11, it is assumed that only data is forwarded by the relay UE to the target UE, whereas other signals (e.g. control signals) are transmitted by the gNB directly to the target UE. This is to minimize the impact on the relay UE. Moreover, this example can be working for URLLC use case, in which high data reliability is needed for application but other signals to maintain connectivity, such as time/frequency tracking reference signal (RS), measurement RS, control signal (e.g. RRC signaling) may not require extremely high reliability.

Referring to FIG. 11, in relaying operation via the relay UE for DL transmission, scheduling grant is transmitted directly by the gNB to the target UE, and data is relayed via the relay UE utilizing PUSCH structure. It is assumed that PUSCH structure is same as PDSCH structure from the target UE perspective by aligning waveform, demodulation reference signal (DM-RS) pattern, etc. In other words, it is assumed that the target UE can receive the relayed DL data from the relay UE via the forwarded PUSCH, as if the target UE receives the DL data via a regular PDSCH.

Alternatively, separate DM-RS pattern, layer mapping, etc., may be considered for relayed data compared to regular PDSCH from gNB directly. In this case, a channel on which the target UE receives the relayed DL data may be called as "PXSCH". The PXSCH may have the similar/equivalent format to PDSCH and PUSCH by utilizing CP-OFDM waveform.

FIG. 12 shows an example of a method for performing relaying operation by a relay UE according to an embodiment of the present invention. According to the embodiment of the present invention, relaying operation by the relay UE is performed via PUSCH. The target UE receives the relayed DL data from the relay UE via the PUSCH. Meanwhile, the embodiment of the present invention in FIG. 12 is merely exemplary, and the present invention is not limited thereto. For example, the present invention can be applied to relaying of UL data.

In step S1200, the relay UE receives data via a PDSCH from a network. In step S1210, the relay UE receives UL grant from the network. In step S1220, the relay UE copies the data to a PUSCH scheduled by the UL grant. In step S1230, the relay UE transmits the copied data to a target UE via the PUSCH.

There may be no UL data to be transmitted to the network via the PUSCH. The UL grant may include information on a same TBS as the PDSCH. The UL grant may include information on a dedicated HARQ process ID reserved for relaying operation. The UL grant may include indication of relaying operation. The UL grant may include information on a beam direction for the PUSCH.

The PDSCH may be a most recent PDSCH among multiple PDSCHs. The PDSCH may be scheduled by DCI received from the network. The relay UE may transmit the DCI to the target UE. Or, the DCI may be transmitted from the network to the target UE.

The PUSCH may have higher priority than UCI transmission and/or other PUSCH transmission. The PUSCH may be scheduled within DL BWP of the target UE. Or, the PUSCH may be scheduled within UL BWP of the relay UE.

Detailed description related to the embodiment of the present invention shown in FIG. 12 will be described below.

The network may schedule PDSCH and PUSCH to the relay UE at the same time. Or, the network may schedule PDSCH and PUSCH to the relay UE separately. Upon receiving the UL grant, the relay UE may copy the DL data on the most recently received PDSCH if one or more of the following conditions are met.

(1) There is no UL data to transmit even if the UE has received the UL grant.

(2) The UL grant indicates the same transport block size (TBS) as at least one PDSCH received during [T, T-d], where T is the time when the UE is supposed to transmit PUSCH scheduled by the UL grant, and d is the duration of checking DL data to be relayed. If there are multiple PDSCHs satisfying the condition, the most recently received PDSCH may be selected for relaying operation. Alternatively, the UL grant may be used for relaying operation only if the same TBS of the most recent PDSCH to the UL grant has been received.

In addition to TBS, relay condition may be further restricted. For example, such as the same hybrid automatic repeat request (HARQ) identifier (ID) and/or same modulation and coding scheme (MCS), and/or same set of frequency resources, and/or same set of reserved resources, and/or same set of DM-RS patterns, and/or same RNTI used between received PDSCH for relaying and PUSCH for transmission.

(3) The UL grant uses the dedicated HARQ process ID. The dedicated HARQ process ID may be reserved for relaying operation. If TBS is different, it may be considered as error.

(4) The UL grant explicitly indicates relaying operation. In this case, the relay UE may perform relaying operation for the UL grant instead of transmitting uplink shared channel (UL-SCH) to the gNB.

Hereinafter, for the convenience of explanation, the PUSCH used for relaying operation, which will carry relayed DL data either by copying the DL data RE mapping directly or remapping, may be called as relay PUSCH. Details on data mapping will be further discussed below.

Uplink control information (UCI) may not be piggybacked on the relay PUSCH. In other words, the relay PUSCH is not considered as regular PUSCH for UCI piggyback. If the UE does not support PUCCH/PUSCH simultaneous transmission and/or PUCCH and PUSCH are multiplexed by time division multiplexing (TMD) in the same slot, and when the UE has UCI to transmit, the UE may drop the relay PUSCH. In other words, the relay PUSCH may have lower priority than other regular UCI transmission, including scheduling request (SR), HARQ-acknowledgement (ACK) and/or CSI.

Alternatively, if collision between the relay PUSCH transmission and the regular UCI transmission occurs, the relay PUSCH transmission may have higher priority than the regular UCI transmission if there is explicit indication of high importance on the UL grant. For example, for URLLC traffic relay or deterministic data transmission via relaying operation, relaying operation may be considered as more important than other transmission. In such case, the relay PUSCH may have the highest priority except for physical random access channel (PRACH). In general, if the relay PUSCH does not have high importance, an example of the priority order of UL transmission may be 'PRACH > UCI > relay PUSCH > regular PUSCH' or 'PRACH > UCI > regular PUSCH > relay PUSCH'. If the relay PUSCH has high importance, an example of the priority order of UL transmission may be 'PRACH > relay PUSCH > UCI > regular PUSCH'.

For power control for the relay PUSCH, semi-statically configured power may be used. The semi-statically configured power for the relay PUSCH may be separately configured from regular power control toward the gNB. This can be done by configuring separate P0 and/or associated power parameters. In other words, separate power control may be used for the relay PUSCH. The power for the relay PUSCH may be configured by the gNB. The UL grant scheduling the relay PUSCH may include transmit power command (TPC) field, which can be used for power control for the relay PUSCH power control separately from regular PUSCH. If TPC is not used for power control for the relay PUSCH, the TPC field in the UL grant may be reserved or used for some other purpose. For example, the TPC field in the UL grant may be used to indicate relay-related parameter (e.g. absolute TPC value for the relay PUSCH).

For beam configuration for the relay PUSCH, as beam direction/configuration can be different between the regular PUSCH (i.e. to gNB) and the relay PUSCH, beam direction for the relay PUSCH may also be dynamically indicated in the UL grant. Beam direction of the relay PUSCH may be determined based on the indication of beam direction in the UL grant. Or, the beam direction may be configured semi-statically, and the UE may select the semi-statically configured beam direction for the relay PUSCH. The semi-statically configured beam direction for the relay PUSCH may or may not be different from beam direction for the regular PUSCH.

For timing advance (TA) handling, based on the assumption of the propagation delay p between the gNB and the relay UE, TA value of the relay UE may be 2*p, generally. If TA of 2*p is used, from the target UE which is located near to the relay UE (i.e. propagation delay between the relay UE and the target UE is very small), there is a gap between reception of data/RS from the gNB directly and reception of the relayed data from the relay UE. To mitigate this gap, only p, not 2*p, may be used for timing delay for relaying operation. In other words, TA/2 may be used for timing delay value in case of forwarding. That is, data is transmitted from the relay UE to the target UE without considering TA value, but by delaying by TA/2. However, the target UE may also know whether signal/packet has been relayed by the relay UE or directly transmitted by the gNB. In terms of time/frequency tracking, the target UE may perform any tracking based on signals/packets directly transmitted by the gNB.

To minimize the impact from perspective of reception of the target UE, the relay PUSCH needs to be considered like a regular PDSCH. In NR, most transmission schemes are common to both DL and UL. However, for PDSCH, it is necessary to have also accompanied scheduling DCI. To transmit accompanied scheduling DCI, the following approaches may be considered.

(1) The relay UE may transmit DCI in addition to the relay PUSCH. However, this approach may require the relay UE to implement control channel transmission.

(2) The gNB may transmit DCI simultaneously or before the relay PUSCH transmission. Therefore, the target UE can receive control signal from the gNB and the relayed data from the relay UE. In other words, the transmitter of control signal and data can be different from each other. For scheduling control channel, the gNB may indicate beam information on where the relay UE can receive data. The beam information for the data may be different from the beam information for control channel.

In either approach, it is essential to use the same waveform, scrambling, data mapping, interleaver design, BWP assumption, etc., between PDSCH and the relayed PUSCH for the target UE. In terms of scrambling, interleaver design in consideration of BWP, the followings may be considered.

(1) The relay PUSCH may be scheduled/scrambled/interleaved within the DL BWP of the target UE. If there are multiple target UEs utilizing different DL BWPs, the relay PUSCH may use different BWP depending on the target UE.

(2) The relay PUSCH may be scheduled/scrambled/interleaved within the UL BWP of the relay UE. The target UE may assume that DL BWP is same as the UL BWP of the relay UE. In other words, the gNB may configure the same BWP between the relay UE and the target UE such that each UE can assume UL BWP and DL BWP respectively.

(3) For scrambling, interleaving parameters, and/or data mapping order/mechanisms, the relay UE may be configured with separate configuration for the relay PUSCH different from the regular PUSCH. Moreover, it is also possible to configure separate configuration for each target UE by the same relay UE.

In addition to data, other transmission including channel feedback may be done based on signals transmitted by the gNB to the target UE. Additionally, CSI feedback based on RS may be transmitted by the relay UE to measure the channel more accurately. In this case, CSI feedback may be done as follows.

(1) The relay UE may transmit CSI-RS (zero-power (ZP) and/or non-zero-power (NZP)) to the target UE. Therefore, the target UE can perform CSI feedback based on CSI-RS. The target UE can be configured with multiple CSI-RS/report configuration between CSI for the gNB and for the relay UE. CSI feedback itself will be transmitted to the gNB such that the gNB can indicate the UL grant appropriately.

(2) The relay UE may transmit sounding reference signal (SRS) to the target UE. The target UE may report reference signal received quality (RSRQ) and/or reference signal received power (RSRP) based on the SRS instead of CSI feedback. Moreover, the target UE may perform CSI measurement based on SRS transmitted by the relay UE. In this case, the transmission side can have lower complexity, while receiver side can have higher impact to perform CSI based on new signals.

(3) The relay UE may perform measurement based on SRS from the target UE assuming channel reciprocity.

For efficient relaying operation, the relay UE should be selected among UEs around the target UE which affect the target UE considerably. The relay UE may be selected based on CSI feedback (e.g. precoding matrix indicator (PMI)) by the network or the target UEs may perform UE-to-UE measurement in addition to CSI feedback. The main purpose of UE-to-UE measurement is to identify potential relay UEs which have potentially high interference if the relay UE transmits PUSCH while the target UE receives the replay PUSCH. The potential relay UEs may transmit SRS which may or may not be the same as regular SRS. Target UEs may perform UE-to-UE measurement based on the SRS transmitted by the relay UEs. This may be called as cross-link-interference RSRP.

PDSCH transmitted from the gNB and the relay PUSCH transmitted from the relay UE may be jointly received. For this, the gNB may transmit the PDSCH to the target UE at the same time as the relay PUSCH. Therefore, the target UE can perform joint reception on both channels (PDSCH transmitted from the gNB and the relay PUSCH transmitted from the relay UE).

Repetition on the PDSCH transmitted from the gNB and the relay PUSCH transmitted from the relay UE may be combined. Repetition on the PDSCH transmitted from the gNB and the relay PUSCH transmitted from the relay UE may be related to data scrambling, control resource configuration, resource schedule. Repetition on the PDSCH transmitted from the gNB and the relay PUSCH transmitted from the relay UE may be related to HARQ/retransmission.

For relaying operation for UL data to be transmitted from the target UE, similar approach to relaying operation for DL data may be considered. In other words, the target UE may transmit a PUSCH targeted for the relay UE. In this sense, this can be viewed as if the target UE transmits the relay PUSCH to the relay UE, and the relay UE transmits PUSCH to the gNB. Techniques used by the relay UE for the relay PUSCH in DL relaying operation described above may be used for the target UE to initiate UL transmission. The relay UE may transmit regular PUSCH which carries copy of recently received PUSCH from the target UE. To determine whether to copy recently received PUSCH or UL-SCH, similar mechanism to determine relaying operation for DL data may be considered.

According to embodiment of the present invention shown in FIG. 12, relay operation can be performed efficiently for specific type of service, e.g. URLLC. The latency can be reduced by reducing forward latency as compared to other existing relaying operation. Furthermore, resource allocation and/or resource sharing between access link (i.e. link between the relay UE and the target UE) and backhaul link (i.e. link between the gNB and the relay UE) can be simplified. Furthermore, additional impact on the relay UE beyond regular UE can be minimized.

FIG. 13 shows a UE to implement an embodiment of the present invention. The present invention described above for relay UE side may be applied to this embodiment.

A UE 1300 includes a processor 1310, a memory 1320 and a transceiver 1330. The processor 1310 may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of the radio interface protocol may be implemented in the processor 1310.

Specifically, the processor 1310 is configured to control the transceiver 1330 to receive data via a PDSCH from a network. The processor 1310 is configured to control the transceiver 1330 to receive UL grant from the network. The processor 1310 is configured to copy the data to PUSCH scheduled by the UL grant. The processor 1310 is configured to control the transceiver 1330 to transmit the copied data to a target UE via the PUSCH.

The memory 1320 is operatively coupled with the processor 1310 and stores a variety of information to operate the processor 1310. The transceiver 1330 is operatively coupled with the processor 1310, and transmits and/or receives a radio signal.

The processor 1310 may include application-specific integrated circuit (ASIC), other chipset, logic circuit and/or data processing device. The memory 1320 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and/or other storage device. The transceiver 1330 may include baseband circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in the memory 1320 and executed by the processor 1310. The memory 1320 can be implemented within the processor 1310 or external to the processor 1310 in which case those can be communicatively coupled to the processor 1310 via various means as is known in the art.

According to embodiment of the present invention shown in FIG. 13, relay operation can be performed efficiently for specific type of service, e.g. URLLC. The latency can be reduced by reducing forward latency as compared to other existing relaying operation. Furthermore, resource allocation and/or resource sharing between access link (i.e. link between the relay UE and the target UE) and backhaul link (i.e. link between the gNB and the relay UE) can be simplified. Furthermore, additional impact on the relay UE beyond regular UE can be minimized.

FIG. 14 shows more detailed UE to implement an embodiment of the present invention. The present invention described above for relay UE side may be applied to this embodiment.

A UE includes a processor 1310, a power management module 1311, a battery 1312, a display 1313, a keypad 1314, a subscriber identification module (SIM) card 1315, a memory 1320, a transceiver 1330, one or more antennas 1331, a speaker 1340, and a microphone 1341.

The processor 1310 may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of the radio interface protocol may be implemented in the processor 1310. The processor 1310 may include ASIC, other chipset, logic circuit and/or data processing device. The processor 1310 may be an application processor (AP). The processor 1310 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), a modem (modulator and demodulator). An example of the processor 1310 may be found in SNAPDRAGON^TM series of processors made by Qualcomm^®, EXYNOS^TM series of processors made by Samsung^®, A series of processors made by Apple^®, HELIO^TM series of processors made by MediaTek^®, ATOM^TM series of processors made by Intel^® or a corresponding next generation processor.

The processor 1310 is configured to control the UE to receive data via PDSCH from a network, receive UL grant from the network, copy the data to PUSCH scheduled by the UL grant, and transmit the copied data to a target UE via the PUSCH.

The power management module 1311 manages power for the processor 1310 and/or the transceiver 1330. The battery 1312 supplies power to the power management module 1311. The display 1313 outputs results processed by the processor 1310. The keypad 1314 receives inputs to be used by the processor 1310. The keypad 1314 may be shown on the display 1313. The SIM card 1315 is an　integrated circuit　that is intended to　securely store the　international mobile subscriber identity　(IMSI) number and its related　key, which are used to identify and authenticate subscribers on　mobile telephony　devices (such as　mobile phones　and　computers). It is also possible to store contact information on many SIM cards.

The memory 1320 is operatively coupled with the processor 1310 and stores a variety of information to operate the processor 1310. The memory 1320 may include ROM, RAM, flash memory, memory card, storage medium and/or other storage device. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in the memory 1320 and executed by the processor 1310. The memory 1320 can be implemented within the processor 1310 or external to the processor 1310 in which case those can be communicatively coupled to the processor 610 via various means as is known in the art.

The transceiver 1330 is operatively coupled with the processor 1310, and transmits and/or receives a radio signal. The transceiver 1330 includes a transmitter and a receiver. The transceiver 1330 may include baseband circuitry to process radio frequency signals. The transceiver 1330 controls the one or more antennas 1331 to transmit and/or receive a radio signal.

The speaker 1340 outputs sound-related results processed by the processor 1310. The microphone 1341 receives sound-related inputs to be used by the processor 1310.

According to embodiment of the present invention shown in FIG. 14, relay operation can be performed efficiently for specific type of service, e.g. URLLC. The latency can be reduced by reducing forward latency as compared to other existing relaying operation. Furthermore, resource allocation and/or resource sharing between access link (i.e. link between the relay UE and the target UE) and backhaul link (i.e. link between the gNB and the relay UE) can be simplified. Furthermore, additional impact on the relay UE beyond regular UE can be minimized.

FIG. 15 shows a network node or target UE to implement an embodiment of the present invention. The present invention described above for network side or target UE side may be applied to this embodiment.

A network node or target UE 1500 includes a processor 1510, a memory 1520 and a transceiver 1530. The processor 1510 may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of the radio interface protocol may be implemented in the processor 1510. The memory 1520 is operatively coupled with the processor 1510 and stores a variety of information to operate the processor 1510. The transceiver 1530 is operatively coupled with the processor 1510, and transmits and/or receives a radio signal.

The processor 1510 may include ASIC, other chipset, logic circuit and/or data processing device. The memory 1520 may include ROM, RAM, flash memory, memory card, storage medium and/or other storage device. The transceiver 1530 may include baseband circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in the memory 1520 and executed by the processor 1510. The memory 1520 can be implemented within the processor 1510 or external to the processor 1510 in which case those can be communicatively coupled to the processor 1510 via various means as is known in the art.

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

A method for performed by a relay user equipment (UE) in a wireless communication system, the method comprising:

receiving data via a physical downlink shared channel (PDSCH) from a network;

receiving an uplink (UL) grant from the network;

copying the data to a physical uplink shared channel (PUSCH) scheduled by the UL grant; and

transmitting the copied data to a target UE via the PUSCH.
The method of claim 1, wherein there is no UL data to be transmitted to the network via the PUSCH.
The method of claim 1, wherein the UL grant includes information on a same transport block size (TBS) as the PDSCH.
The method of claim 1, wherein the UL grant includes information on a dedicated hybrid automatic repeat request (HARQ) process identifier (ID) reserved for relaying operation.
The method of claim 1, wherein the UL grant includes indication of relaying operation.
The method of claim 1, wherein the UL grant includes information on a beam direction for the PUSCH.
The method of claim 1, wherein the PDSCH is a most recent PDSCH among multiple PDSCHs.
The method of claim 1, wherein the PDSCH is scheduled by downlink control information (DCI) received from the network.
The method of claim 8, further comprising transmitting the DCI to the target UE.
The method of claim 8, wherein the DCI is transmitted from the network to the target UE.
The method of claim 1, wherein the PUSCH has higher priority than uplink control information (UCI) transmission and/or other PUSCH transmission.
The method of claim 1, wherein the PUSCH is scheduled within a downlink (DL) bandwidth part (BWP) of the target UE.
The method of claim 1, wherein the PUSCH is scheduled within a UL BWP of the relay UE.
A relay user equipment (UE) in a wireless communication system, the relay UE comprising:

a memory;

a transceiver; and

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

control the transceiver to receive data via a physical downlink shared channel (PDSCH) from a network,

control the transceiver to receive an uplink (UL) grant from the network,

copy the data to a physical uplink shared channel (PUSCH) scheduled by the UL grant, and

control the transceiver to transmit the copied data to a target UE via the PUSCH.
A processor for a wireless communication device in a wireless communication system,

wherein the processor is configured to control the wireless communication device to:

receive data via a physical downlink shared channel (PDSCH) from a network,

receive an uplink (UL) grant from the network,

copy the data to a physical uplink shared channel (PUSCH) scheduled by the UL grant, and

transmit the copied data to a target UE via the PUSCH.