Method and apparatus for area-based relay communication

Abstract

The present invention discloses a method and apparatus for area-based relay communication. The working method of the source node includes: the step of generating SCI, wherein the SCI includes resource allocation information of data, feedback timing indicating the transmission time of HARQ response for the data, and relay timing indicating the execution time of relay communication; the step of transmitting the SCI to the destination node; the step of transmitting the data to the destination node at the resource indicated by the resource allocation information; and the step of performing monitoring work to receive the HARQ response at the resource indicated by the feedback timing.

Description

Technical Field

[0001] The present invention relates to a relay communication technology in a communication system, and more particularly, to a zone-based relay communication technology in a communication system. Background Art

[0002] In order to handle the surge in wireless data, a communication system (e.g., NR (new radio) communication system) is considering using a frequency band (e.g., a frequency band above 6 GHz) higher than the frequency band of LTE (long term evolution) (or LTE-A, advanced long term evolution) (e.g., a frequency band below 6 GHz). The NR communication system can support not only frequency bands below 6 GHz, but also frequency bands above 6 GHz, and can support various communication services and scenarios compared to the LTE communication system. For example, the usage scenarios of the NR communication system may include eMBB (enhanced Mobile Broad Band), URLLC (Ultra Reliable Low Latency Communication), mMTC (massive Machine Type Communication), etc. Communication technologies are needed to meet the various requirements of eMBB, URLLC and mMTC.

[0003] A communication system (e.g., an LTE communication system, an NR communication system) may support sidelink communication. Sidelink communication may be performed based on the zone in which the terminal is located. For example, a transmitting terminal may transmit SCI (sidelink control information) including information about the zone in which it is located (e.g., a zone ID (identifier)) to a receiving terminal, and sidelink communication between the transmitting terminal and the receiving terminal may be performed taking into account the zone in which each terminal is located.

[0004] On the other hand, relay technology may be used to expand the communication service area and / or increase the communication capacity. Side link communication may be performed based on relaying, in which case technology for area-based relay communication is required. Summary of the invention

[0005] (Problems to be solved by the invention)

[0006] An object of the present invention to solve the above-mentioned problems is to provide a method and apparatus for zone-based relay communication in a communication system.

[0007] (Measures taken to solve the problem)

[0008] The working method of the source node according to the first embodiment of the present invention for achieving the above-mentioned purpose includes: the step of generating SCI, wherein the above-mentioned SCI (sidelink control information) includes resource allocation information of data, feedback timing indicating the transmission time of HARQ (hybrid automatic repeat request) response for the above-mentioned data, and relay timing indicating the execution time of relay communication; the step of transmitting the above-mentioned SCI to the destination node; the step of transmitting the above-mentioned data to the above-mentioned destination node at the resources indicated by the above-mentioned resource allocation information; and the step of performing monitoring work in order to receive the above-mentioned HARQ response at the resources indicated by the above-mentioned feedback timing.

[0009] Here, the working method of the above-mentioned source node may further include: a step of estimating the distance between the above-mentioned source node and the above-mentioned destination node before generating the above-mentioned SCI; a step of comparing the estimated distance with the communication coverage of the above-mentioned source node; and if the estimated distance exceeds the above-mentioned communication coverage, a step of determining to perform the above-mentioned relay communication. In the case where it has been determined to perform the above-mentioned relay communication, the above-mentioned SCI can be generated to include one or more information elements (information elements) for the above-mentioned relay communication, and information indicating the above-mentioned communication coverage can be included in the above-mentioned SCI.

[0010] Here, the distance may be estimated using the zone ID (identifier) ​​of the destination node.

[0011] Here, when direct communication without passing through a relay node is performed, the relay timing may be set to 0, and when relay communication is performed, the relay timing may be set to a natural number.

[0012] Here, the SCI may further include a relay indicator. The relay indicator set to a first value may indicate that the relay communication is not to be performed, and the relay indicator set to a second value may indicate that the relay communication is to be performed.

[0013] Here, the SCI may further include information indicating one or more relay nodes that perform the relay communication, and the information indicating the one or more relay nodes may be updated based on a measurement result of a reference signal received from an adjacent relay node.

[0014] Here, when "the HARQ response is not received from the destination node at the feedback timing and ACK (acknowledgement) for the data is received from the relay node" or "NACK (negative ACK) for the data is received from the destination node at the feedback timing and ACK for the data is received from the relay node", it can be determined that the relay communication is performed by the relay node.

[0015] Here, when "NACK for the above data is received from the above destination node at the above feedback timing and NACK for the above data is received from the relay node" or "the above HARQ response is not received from the above destination node at the above feedback timing and NACK for the above data is received from the above relay node", it can be determined that the above relay communication is not performed by the above relay node.

[0016] Here, when a relay transmission request is received from the destination node at the feedback timing, it can be determined that the destination node requests the relay communication.

[0017] The working method of the relay node according to the second embodiment of the present invention aimed at achieving the above-mentioned purpose includes: the step of receiving SCI from a source node, wherein the above-mentioned SCI includes resource allocation information of data, feedback timing indicating the transmission time of the HARQ response to the above-mentioned data, and relay timing indicating the execution time of relay communication; the step of receiving the above-mentioned data from the above-mentioned source node at the resources indicated by the above-mentioned resource allocation information; and the step of transmitting the above-mentioned SCI and the above-mentioned data to the destination node at the resources indicated by the above-mentioned feedback timing.

[0018] Here, the relay timing may be adjusted according to a TA (timing advance) value determined in consideration of the reception timing of the destination node.

[0019] Here, the relay timing may be an offset between a time slot when the SCI is received from the source node and a time slot when the SCI is transmitted to the destination node.

[0020] Here, the SCI may further include a relay indicator, and the relay indicator set to a first value may indicate that the relay communication is not to be performed, and the relay indicator set to a second value may indicate that the relay communication is to be performed.

[0021] Here, the SCI may further include information indicating one or more relay nodes that perform the relay communication, and the relay node may perform the relay communication if it belongs to the one or more relay nodes.

[0022] Here, the working method of the relay node may further include the step of transmitting an ACK for the data to the source node at the feedback timing when the data is successfully received.

[0023] The source node according to the third embodiment of the present invention for achieving the above-mentioned purpose includes: a processor; a memory that communicates with the above-mentioned processor in an electronic manner; and instructions that are stored in the above-mentioned memory. When the above-mentioned instructions are executed by the above-mentioned processor, the operation of the above-mentioned instructions causes the above-mentioned source node to perform the following operations: generate SCI, the above-mentioned SCI includes resource allocation information of data, feedback timing indicating the transmission time of the HARQ response to the above-mentioned data, and relay timing indicating the execution time of relay communication; transmit the above-mentioned SCI to the destination node; transmit the above-mentioned data to the above-mentioned destination node at the resources indicated by the above-mentioned resource allocation information; and perform monitoring work in order to receive the above-mentioned HARQ response at the resources indicated by the above-mentioned feedback timing.

[0024] Here, when performing direct communication without passing through a relay node, the relay timing can be set to 0, and when performing the relay communication, the relay timing can be set to a natural number. The relay timing can be the offset between the time slot for transmitting the SCI and the execution time of the relay communication.

[0025] Here, the SCI may further include a relay indicator. The relay indicator set to a first value may indicate that the relay communication is not to be performed, and the relay indicator set to a second value may indicate that the relay communication is to be performed.

[0026] Here, when "the HARQ response is not received from the destination node at the feedback timing and an ACK for the data is received from the relay node" or "NACK for the data is received from the destination node at the feedback timing and an ACK for the data is received from the relay node", it can be determined that the relay communication is performed by the relay node.

[0027] Here, when "NACK for the above data is received from the above destination node at the above feedback timing and NACK for the above data is received from the relay node" or "the above HARQ response is not received from the above destination node at the above feedback timing and NACK for the above data is received from the above relay node", it can be determined that the above relay communication is not performed by the above relay node.

[0028] (Effects of the Invention)

[0029] According to the present invention, the source node can transmit SCI (sidelink control information) including various information elements required for relay communication, and relay communication can be performed based on the information elements included in the SCI. In addition, the TA (timing advance) value can be appropriately adjusted at the relay node, and the list of relay nodes can be updated in consideration of RSRP (reference signal received power). Therefore, relay communication can be effectively performed, and transmission delay caused by relay communication can be reduced. That is, the performance of the communication system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0031] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0032] Figure 3 is a conceptual diagram illustrating a first embodiment of relay communication.

[0033] Figure 4a is a conceptual diagram illustrating a first embodiment of an L1 relay.

[0034] Figure 4b is a conceptual diagram illustrating a first embodiment of an L2 relay.

[0035] Figure 4c is a conceptual diagram illustrating a first embodiment of an L3 relay.

[0036] Figure 5 is a conceptual diagram illustrating a first embodiment of zones in a communication system.

[0037] Figure 6 is a flow chart illustrating a first embodiment of a zone-based relay communication method in a communication system.

[0038] Figure 7is a timing diagram illustrating a first embodiment of a direct communication method in a communication system.

[0039] Figure 8 is a timing diagram illustrating a first embodiment of a relay scenario 1 in a communication system.

[0040] Fig. 9 is a timing diagram illustrating a second embodiment of a relay scenario 1 in a communication system.

[0041] Fig.10 is a timing diagram illustrating a first embodiment of a relay scenario 2 in a communication system.

[0042] Fig.11 is a timing diagram illustrating a first embodiment of a method for adjusting a TA value in a communication system.

[0043] Fig.12 is a timing chart illustrating a first embodiment of transmission / reception timing of packets in the communication system. DETAILED DESCRIPTION

[0044] The present invention can be implemented in a variety of ways and can have various embodiments, so each specific embodiment will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific implementation, but should be understood to include all changes, equivalents and even substitutes that fall within the concept and technical scope of the present invention.

[0045] The terms "first" and "second" can be used to describe a variety of constituent elements, but the above constituent elements shall not be limited by the above terms. The above terms are only used to distinguish one constituent element from other constituent elements. For example, the first constituent element can be named as the second constituent element without departing from the scope of the present invention, and similarly, the second constituent element can also be named as the first constituent element. The term "and / or" includes a combination of multiple associated and recorded items or a certain item among multiple associated and recorded items.

[0046] When it is mentioned that a certain component is "connected" or "coupled" to another component, although it is possible to be directly connected or coupled to the other component, it should be understood that other components may exist between the two. On the contrary, when it is mentioned that a certain component is "directly connected" or "directly coupled" to another component, it should be understood that no other components exist between the two.

[0047] The terms used in this application are only used to illustrate specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless they have a significantly different meaning in the context. In this application, the terms "including" or "having" are intended to specify the existence of features, numbers, steps, actions, constituent elements, parts or combinations thereof recorded in the specification, and should be understood as not excluding in advance the existence or additional possibility of one or more other features or numbers, steps, actions, constituent elements, parts or combinations thereof.

[0048] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by those of ordinary skill in the art. Terms as defined in commonly used dictionaries should be interpreted as having the same meaning as that in the context of the relevant art and should not be interpreted as having an ideal or excessive formal meaning unless explicitly defined in this application.

[0049] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In the process of describing the present invention, in order to facilitate overall understanding, the same reference numerals are used for the same components in the drawings, and repeated descriptions of the same components are omitted.

[0050] A communication system applicable to an embodiment of the present invention will be described. The communication system may be a 4G communication system (e.g., LTE (long-term evolution) communication system, LTE-A communication system), a 5G communication system (e.g., NR (new radio) communication system), etc. The 4G communication system can support communication in a frequency band below 6 GHz, and the 5G communication system can support communication not only in a frequency band below 6 GHz, but also in a frequency band above 6 GHz. The communication system applicable to an embodiment of the present invention is not limited to the content described below, and the embodiment of the present invention may be applicable to various communication systems. Here, the communication system may be used in the same meaning as a communication network, "LTE" may indicate a "4G communication system", "LTE communication system" or "LTE-A communication system", and "NR" may indicate a "5G communication system" or "NR communication system".

[0051] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0052] Reference Figure 1, the communication system 100 may include multiple communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6. In addition, the communication system 100 may further include a core network (e.g., S-GW (serving-gateway), P-GW (PDN (packet data network)-gateway), MME (mobility management entity)). When the communication system 100 is a 5G communication system (e.g., NR (new radio) system), the core network may include AMF (access and mobility management function), UPF (user plane function), SMF (session management function), etc.

[0053] Multiple communication nodes 110 to 130 can support communication protocols specified in the 3GPP (3rd generation partnership project) standard (for example, LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.). The plurality of communication nodes 110 to 130 may support CDMA (code division multiple access) technology, WCDMA (wideband CDMA) technology, TDMA (time division multiple access) technology, FDMA (frequency division multiple access) technology, OFDM (orthogonal frequency division multiplexing) technology, filtered OFDM (Filtered OFDM) technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA technology, NOMA (Non-orthogonal Multiple Access) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filterbank Multi-carrier (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (Space Division Multiple Access) technology, etc. Each of the multiple communication nodes may have the following structure.

[0054] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0055] Reference Figure 2The communication node 200 may include at least one processor 210, a memory 220, and a sending / receiving device (transceiver) 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, etc. The various components included in the communication node 200 may be connected via a bus 270 to perform communication with each other.

[0056] The processor 210 may execute program commands stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor that executes the method according to an embodiment of the present invention. The memory 220 and the storage device 260 may each be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may be composed of at least one of a read-only memory (ROM) and a random access memory (RAM).

[0057] Re-reference Figure 1 , the communication system 100 may include multiple base stations 110-1, 110-2, 110-3, 120-1, 120-2, and multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6. The first base station 110-1, the second base station 110-2, and the third base station 110-3 may each form a macro cell. The fourth base station 120-1 and the fifth base station 120-2 may each form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5 and the sixth terminal 130-6 may be within the cell coverage of the third base station 110-3. The first terminal 130-1 may be within the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may be within the cell coverage of the fifth base station 120-2.

[0058] Here, the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may each be referred to as NB (NodeB), eNB (evolved NodeB), gNB, ABS (advanced base station), HR-BS (high reliability-base station), BTS (base transceiver station), radio base station, radio transceiver, access point, access node, RAS (radio access station), MMR-BS (mobile multihop relay-base station), RS (relay station), ARS (advanced relay station), HR-RS (high reliability-relay station), HNB (home NodeB), HeNB (home eNodeB), and RSU (road side unit, roadside unit), RRH (radio remote head), TP (transmission point), TRP (transmission and reception point), etc.

[0059] Multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may each be referred to as UE (user equipment), TE (terminal equipment), AMS (advanced mobile station), HR-MS (high reliability-mobile station), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, OBU (on board unit), etc.

[0060] On the other hand, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can operate in different frequency bands, or can operate in the same frequency band. Each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can be connected to each other through an ideal backhaul link or a non-ideal backhaul link, and can exchange information with each other through the ideal backhaul link or the non-ideal backhaul link. Each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can be connected to the core network through an ideal backhaul link or a non-ideal backhaul link. Each of the multiple base stations 110-1, 110-2, 110-3, 120-1, 120-2 can transmit signals received from the core network to the corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6, and can transmit signals received from the corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 to the core network.

[0061] In addition, multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can each support MIMO (multiple-input and multiple-output) transmission (for example, SU (single user)-MIMO, MU (multi user)-MIMO, massive MIMO, etc.), CoMP (coordinated multi point) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, direct communication between terminals (device to device communication, D2D) (or ProSe (proximity services)), IoT (Internet of Things) communication, dual connectivity (DC), etc. Here, multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 can each perform work corresponding to base stations 110-1, 110-2, 110-3, 120-1, 120-2, and can perform work supported by base stations 110-1, 110-2, 110-3, 120-1, 120-2. For example, the second base station 110-2 can transmit a signal to the fourth terminal 130-4 based on the SU-MIMO method, and the fourth terminal 130-4 can receive a signal from the second base station 110-2 through the SU-MIMO method. Alternatively, the second base station 110-2 can transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO method, and the fourth terminal 130-4 and the fifth terminal 130-5 can each receive a signal from the second base station 110-2 through the MU-MIMO method.

[0062] The first base station 110-1, the second base station 110-2, and the third base station 110-3 can each transmit a signal to the fourth terminal 130-4 based on the CoMP method, and the fourth terminal 130-4 can receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 through the CoMP method. Multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can each send and receive signals with terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 within the coverage area of ​​their own cells based on the CA method. The first base station 110-1, the second base station 110-2 and the third base station 110-3 can each control the D2D between the fourth terminal 130-4 and the fifth terminal 130-5, and the fourth terminal 130-4 and the fifth terminal 130-5 can each perform D2D through the control of the second base station 110-2 and the third base station 110-3.

[0063] A communication system (e.g., LTE communication system, NR communication system) can support a terminal-to-terminal communication method (e.g., direct communication method) for vehicle communication outside a network service area (e.g., network coverage). The terminal-to-terminal communication method can be performed without a network. The direct communication link between the terminals can be referred to as a sidelink. In LTE Release 12, the LTE sidelink was introduced for the purpose of D2D (device-to-device) communication. Even if the terminal is out of network coverage, communication between the terminals can be performed using the LTE sidelink.

[0064] In LTE Release 14, the sidelink technology was improved to be suitable for V2X (vehicle to everything) communication. LTE V2X (e.g., 3GPP V2X) communication is designed to send / receive ITS (Intelligent Transport system) messages specified by ETSI (European Telecommunication Standards Institute) for vehicle safety.

[0065] 3GPP V2X communication can be divided into V2X communication between the network and the terminal and V2X communication between the terminals. V2X communication between the network and the terminal can include V2I (vehicle to infrastructure) communication and V2N (vehicle to network) communication. V2X communication between the terminals can include V2V (vehicle to vehicle) communication and V2P (vehicle to pedestrian) communication. V2V communication and V2P communication can be sidelink communication.

[0066] In order to support V2X services such as autonomous driving, vehicle entertainment, and cluster driving, the standard for LTE V2X communication was specified in Release 15, but the standard did not meet the relevant requirements. In order to eliminate these problems, the standard for NR V2X communication was discussed in Release 16.

[0067] On the other hand, in a communication system (e.g., an LTE communication system, an NR communication system), relay technology can be used to expand the communication service area and / or increase the communication capacity. The use of relay technology can be used to eliminate shadow areas within a cell, expand cell coverage, and / or increase throughput.

[0068] Figure 3 is a conceptual diagram illustrating a first embodiment of relay communication.

[0069] Reference Figure 3 , the source node can transmit signals and / or channels to the destination node. In an embodiment, the signal may refer to "signal (e.g., reference signal, synchronization signal)", "channel (e.g., physical channel)" or "signal and channel". When the distance between the source node and the destination node is greater than the communication coverage range of the source node (e.g., cell coverage range), the destination node may not receive the signal transmitted by the source node. In order to solve this problem, relay technology can be used. The relay node can receive the signal from the source node and transmit the signal to the final destination, i.e., the destination node.

[0070] There may be multiple relay nodes between the source node and the destination node. For example, the number of the multiple relay nodes may be M. M may be a natural number. The best relay node among the M relay nodes may relay the communication between the source node and the destination node.

[0071] The source node may be a base station, and the destination node may be a terminal. Alternatively, the source node may be a terminal, and the destination node may be a base station. Alternatively, the source node may be a transmitting terminal, and the destination node may be a receiving terminal. The source node, the relay node, and the destination node may each be the same as shown in FIG. Figure 2 The communication nodes 200 are constructed identically or similarly.

[0072] The link between the source node and the relay node (e.g., a backhaul link) can be a wireless link. Therefore, there is no need to add a new source node (e.g., a base station) or set up a wired backhaul. The link between the relay node and the destination node can be an access link. According to the function of the protocol layer, the relay can be classified into an L1 relay (e.g., an L0 / L1 relay), an L2 relay, and an L3 relay.

[0073] Figure 4a is a conceptual diagram illustrating a first embodiment of an L1 relay, Figure 4b is a conceptual diagram illustrating a first embodiment of an L2 relay, Figure 4c is a conceptual diagram illustrating a first embodiment of an L3 relay.

[0074] Reference Figure 4a In the case of using L1 relay, the relay node may perform the function of layer 1 (eg, PHY (physical) layer). For example, the relay node may perform the function of layer 1 to relay communication between a source node and a destination node.

[0075] Reference Figure 4b In the case of using L2 relay, the relay node can perform the functions of layer 1 and layer 2 (e.g., MAC (medium access control) layer, RLC (radio link control) layer). For example, the relay node can perform the functions of layer 1 and layer 2 to relay the communication between the source node and the destination node.

[0076] Reference Figure 4c In the case of using L3 relay, the relay node can perform layer 1, layer 2, and layer 3 (e.g., PDCP (packet data convergence protocol) layer, IP (internet protocol) layer) functions. For example, the relay node can perform layer 1, layer 2, and layer 3 functions to relay communications between a source node and a destination node.

[0077] On the other hand, a wireless backhaul supporting multi-hop can be used in the NR communication system. In the wireless backhaul, an IAB (integrated access and backhaul) node that supports wireless connection operation can be used, and IAB-based relay communication can be performed. In order to perform side link-based relay communication and / or IAB-based relay communication, it may be necessary to study the selection method of relay nodes (e.g., V2X nodes, IAB nodes), relay transmission methods, and detailed technologies for relay communication. The V2X node can be a terminal located in the vehicle, an OBU (on board unit), an RSU (road side unit), etc.

[0078] In sidelink communication, the transmitting terminal may transmit SCI (sidelink control information). SCI may be transmitted via PSCCH (physical sidelink control channel) and / or PSSCH (physical sidelink shared channel). SCI may include a first step (1st stage) SCI and / or a second step (2nd stage) SCI. The first step SCI may include SCI format 1-A, and the second step SCI may include SCI format 2-A and SCI format 2-B. SCI may include an area ID (identifier) ​​field, and the area ID field may indicate the location information of the transmitting terminal. The location information of the transmitting terminal may be identification information (e.g., area ID) of the area where the transmitting terminal is located. The size of the area ID field may be 12 bits. The receiving terminal may receive SCI from the transmitting terminal, and may confirm the location of the transmitting terminal based on the area ID indicated by the area ID field included in the SCI.

[0079] Figure 5 is a conceptual diagram illustrating a first embodiment of zones in a communication system.

[0080] Reference Figure 5, a specific geographical area can be divided into multiple zones, and an ID can be set for each zone. For example, the transmitting terminal can be located in zone #0, and the receiving terminal can be located in zone #12. The transmitting terminal can generate an SCI including a zone ID field indicating the zone #0 in which it is located, and can transmit the SCI to the receiving terminal. The zone ID field may be included in the second step SCI (e.g., SCI format 2-B). The receiving terminal can receive the SCI from the transmitting terminal, and can determine that the transmitting terminal is located in zone #0 based on the zone ID field included in the SCI. The receiving terminal can estimate the distance between itself and the transmitting terminal based on the zone ID of the transmitting terminal, and can determine whether to send a HARQ (hybrid automatic repeat request) response (e.g., ACK (acknowledgement) or NACK (negative ACK)) based on the estimated distance.

[0081] In the embodiments, various area-based relay communication methods will be described. A communication system applicable to the embodiments is shown in FIG. Figure 3 A communication system may include a source node, one or more relay nodes, and a destination node. The source node may be a communication node that transmits a packet (e.g., data). The relay node may be referred to as a candidate relay node. The relay node may relay the communication between the source node and the destination node. The destination node may be a communication node that receives a packet (e.g., data). That is, the final destination of the packet may be the destination node. The source node, the relay node, and the destination node may each be a vehicle terminal, a user terminal, a base station, a fixed relay, a mobile relay, etc.

[0082] Figure 6 is a flow chart illustrating a first embodiment of a zone-based relay communication method in a communication system.

[0083] Reference Figure 6 , a communication system may include a source node, a relay node (eg, a candidate relay node), and a destination node. Figure 6 The source node can be shown in Figure 3 The source node of . Figure 6 The relay node can be shown in Figure 3 In addition, the diagram is shown in Figure 6 The relay node can support Figure 4a Layer 1 relay communication, shown in Figure 4b Layer 2 relay communications and / or diagrams are shown in Figure 4c Layer 3 relay communication. Figure 6 The destination node can be shown in Figure 3The source node, the relay node, and the destination node can each be connected to the Figure 2 The communication nodes 200 are constructed identically or similarly.

[0084] The source node performs sensing work before transmitting a packet (e.g., data), so that it can obtain the area ID of the destination node (e.g., identification information of the area where the destination node is located) (S601). The source node can estimate the distance between itself and the destination node based on its own position and the area ID of the destination node (S602). For example, the source node can use GPS (global positioning system) to obtain its own position information (e.g., coordinates), and can obtain the position information (e.g., coordinates) of the destination node based on the area ID of the destination node. The coordinates of the destination node can be used to estimate the center coordinates of the area where the destination node is located. The source node can use its own coordinates and the coordinates of the destination node to estimate the distance between itself and the destination node.

[0085] The source node may compare its own communication coverage with the estimated distance and select a communication method (e.g., a direct communication method or a relay communication method) (S603). The direct communication method may refer to a side link communication between the source node and the receiving node. When the direct communication method is used, the packet may be transmitted without passing through a relay node. The relay communication method may refer to relay communication through a relay node. When the communication coverage of the source node is greater than the estimated distance, the source node may select a direct communication method. The source node may transmit the packet to the destination node using the direct communication method (S604). The destination node may receive a packet from the source node based on the direct communication method.

[0086] In the case where the communication coverage of the source node is less than the estimated distance, the source node may select a relay communication mode. The source node may use the relay communication mode to transmit the packet to the destination node (S605). For example, the source node may transmit the packet to the relay node, and the relay node may receive the packet from the source node. The relay node may transmit the packet to the destination node as the destination (e.g., the final destination). The destination node may receive the packet from the relay node.

[0087] As another embodiment, the relay communication mode and the direct communication mode may be used together in step S605. In this case, the source node may transmit the packet to the destination node using the direct communication mode, and the relay node may transmit the packet received from the source node to the destination node as the destination. The destination node may receive the packet from the source node and / or the relay node.

[0088] [Direct communication method]

[0089] Pictured at Figure 6 Step S604 (eg, direct communication method) may be performed as follows.

[0090] Figure 7 is a timing diagram illustrating a first embodiment of a direct communication method in a communication system.

[0091] Reference Figure 7 , the source node may generate SCI (e.g., first step SCI and / or second step SCI) and may transmit SCI in time slot #n. SCI may include various information elements required for sending / receiving data (e.g., SL (sidelink) data). The various information elements required may include priority, frequency resource allocation information, time resource allocation information, resource reservation period, DMRS (demodulation reference signal) mode, second step SCI format information, number of DMRS ports, MCS (modulation and coding scheme) information, additional MCS table indicator, PSFCH (physical side link feedback channel) overhead indication, HARQ process number, NDI (new data indicator), RV (redundancy version), source ID, destination ID, HARQ feedback enabled / disabled indicator, cast type indicator, CSI (channel state information) request, area ID (e.g., area ID of the source node and / or area ID of the destination node) and / or communication range requirement.

[0092] The first step SCI can be transmitted on the PSCCH in time slot #n, and the second step SCI can be transmitted on the PSSCH in time slot #n. The scheduling information of the data (e.g., frequency allocation information, time allocation information, etc.) can be included in the first step SCI. The source node can transmit the data scheduled by SCI on the PSSCH in time slot #n. In this case, SCI and data can be transmitted in the same time slot, and the second step SCI and data can be multiplexed on the PSSCH in the same time slot. The receiving node performs monitoring work in time slot #n, so that it can receive SCI from the source node, and can receive data in time slot #n based on the information elements (e.g., scheduling information) included in the SCI.

[0093] The SCI may further include the information elements listed in the following Table 1. The information elements listed in Table 1 may be included in the first step SCI and / or the second step SCI.

[0094] Table 1

[0095]

[0096]

[0097] In the case of using a direct communication method, the relay timing field may not be included in the SCI. Alternatively, the relay timing field included in the SCI may be set to 0. In this case, the destination node will determine that relay communication is not performed. In the case where "the SCI includes a relay timing field and the relay indicator included in the SCI indicates that relay communication is not performed", the destination node may determine that relay communication is not performed, and the value indicated by the relay timing field may be ignored. In the case where "the SCI includes a relay timing field and the relay indicator included in the SCI indicates that relay communication is performed", the destination node may determine that relay communication is performed in the time slot indicated by the relay timing field.

[0098] In the case of using a direct communication mode, the candidate relay node information field may not be included in the SCI. In the case of using a relay communication mode, the relay node may receive the SCI from the source node, and may compare its own ID with the ID indicated by the candidate relay node information field included in the SCI. In the case where the ID indicated by the candidate relay node information field included in the SCI is the same as the ID of the relay node, the relay node may determine that it has been designated as a relay node (e.g., a candidate relay node) that relays communication between the source node and the destination node.

[0099] In this case, the relay node may transmit a HARQ response to the data related to the SCI to the source node at the feedback timing k1 indicated by the SCI. It is possible that the relay node designated as a candidate relay node by the source node cannot perform relay transmission at the relay timing k2 indicated by the SCI. In this case, even if the data related to the SCI is successfully received from the source node, the relay node may transmit a NACK to the source node instead of an ACK at the feedback timing k1 indicated by the SCI.

[0100] In the case where the source node is unknown to the area ID of the destination node, the coverage field may be included in the SCI. The coverage field may be included in the SCI transmitted to the destination node together with the relay indicator field. The coverage indicated by the coverage field included in the SCI may be the maximum coverage that can receive data (e.g., packets) transmitted from the source node. The maximum coverage may be the maximum distance that can be communicated between the source node and the destination node.

[0101] The value indicated by the coverage field included in the SCI may be different depending on the size of the data to be transmitted. The larger the size of the data, the smaller the value of the coverage field. The smaller the size of the data, the larger the value of the coverage field.

[0102] On the other hand, the destination node can receive the SCI from the source node, and can confirm the area ID field (e.g., the area ID of the source node), the relay indicator field, and the coverage field included in the SCI. The destination node can estimate the distance between itself and the source node based on the area ID of the source node, and can compare the estimated distance with the coverage indicated by the coverage field. The destination node can determine whether relay communication is required based on the comparison result of the estimated distance and the coverage. In the case where it is determined that "the reception (e.g., decoding) of data transmitted from the source node by direct communication fails and relay communication is required", the destination node can transmit NACK and a relay transmission request at the feedback timing k1 indicated by the SCI. Alternatively, the destination node can transmit only a relay transmission request at the feedback timing k1 indicated by the SCI.

[0103] [Relay communication method]

[0104] Pictured at Figure 6Step S605 (e.g., relay communication mode) may be performed as follows. Relay scenarios may be classified into relay scenario 1 and relay scenario 2. Relay scenario 1 may be relay communication performed when the source node knows the "area ID of the destination node" and / or the "distance between the source node and the destination node". Relay scenario 2 may be relay communication performed when the source node does not know the "area ID of the destination node" or the "distance between the source node and the destination node".

[0105] Relay Scenario 1

[0106] Figure 8 is a timing diagram illustrating a first embodiment of a relay scenario 1 in a communication system.

[0107] Reference Figure 8 , the source node may know the "area ID of the destination node" and / or the "distance between the source node and the destination node". The sensing process may be performed to obtain the area ID of the destination node. The source node may generate an SCI including existing information elements and / or information elements defined in Table 1, and may transmit the SCI in time slot #n. For example, the SCI may include scheduling information, the area ID of the source node, feedback timing k1, relay timing k2, relay indicator, candidate relay node information, etc. The source node may transmit data in time slot #n based on the information elements included in the SCI.

[0108] In the case where the distance between the source node and the destination node exceeds the communication coverage, the destination node may not receive SCI and / or data from the source node. In this case, the destination node may not transmit the HARQ response to the data in the time slot #n+k1 indicated by the SCI. In the case where the relay node is located within the communication coverage of the source node, the relay node can receive SCI from the source node in time slot #n. In the case where "the relay indicator included in the SCI indicates that relay transmission is performed and the candidate relay node ID indicates the relay node", the relay node can determine that it performs relay communication itself. The relay node can receive data from the source node in time slot #n based on the information element included in the SCI. In the case where the data has been successfully received, the relay node can transmit the HARQ response (e.g., ACK) to the data to the source node in time slot #n+k1 indicated by the SCI.

[0109] The source node can determine to perform relay communication when "no HARQ response (e.g., ACK) is received from the destination node in time slot #n+k1 and no NACK is received from all candidate relay nodes in time slot #n+k1 (e.g., ACK is received from at least one relay node in time slot #n+k1)".

[0110] The relay node may transmit the SCI to the destination node in the time slot #n+k2 indicated by the relay timing k2 included in the SCI received from the source node. The information elements included in the SCI transmitted from the relay node may be the same or similar to the information elements included in the SCI transmitted from the source node. The SCI transmitted from the relay node in the time slot #n+k2 may include scheduling information, the area ID of the source node, feedback timing k1, relay timing k2, relay indicator, candidate relay node information, etc. Here, the relay timing k2 may be set to 0. Alternatively, the SCI transmitted in the time slot #n+k2 may not include the relay timing k2. The relay node may transmit data to the destination node in the time slot #n+k2 based on the information elements included in the SCI.

[0111] The destination node may receive the SCI from the relay node at time slot #n+k2, and may confirm the information element included in the SCI. The destination node may receive data from the relay node at time slot #n+k2 based on the information element included in the SCI. The destination node may transmit a HARQ response (e.g., ACK or NACK) for the data to the relay node at time slot #n+k2+k1 indicated by the feedback timing k1 included in the SCI received from the relay node.

[0112] The relay node may receive a HARQ response for the data from the destination node in time slot #n+k2+k1 and may transmit the HARQ response to the source node. The source node may receive the HARQ response from the relay node and may confirm whether the data has been successfully received at the destination node based on the HARQ response.

[0113] Fig. 9 is a timing diagram illustrating a second embodiment of a relay scenario 1 in a communication system.

[0114] Reference Fig. 9 , the source node may know the "area ID of the destination node" and / or the "distance between the source node and the destination node". The sensing process may be performed to obtain the area ID of the destination node. The source node may generate an SCI including existing information elements and / or information elements defined in Table 1, and may transmit the SCI in time slot #n. For example, the SCI may include scheduling information, the area ID of the source node, feedback timing k1, relay timing k2, relay indicator, candidate relay node information, etc. The source node may transmit data in time slot #n based on the information elements included in the SCI.

[0115] The destination node may receive the SCI from the source node at time slot #n, and may perform a data reception operation at time slot #n based on the information element included in the SCI. In the event that reception (e.g., decoding) of the data fails, the destination node may transmit a NACK for the data to the source node at time slot #n+k1 indicated by the feedback timing k1 included in the SCI. The source node may receive a NACK from the destination node at time slot #n+k1. In this case, the source node may determine that reception of the data at the destination node fails.

[0116] The relay node may receive SCI from the source node in time slot #n. In the case where "the relay indicator included in the SCI indicates that relay transmission is performed and the candidate relay node ID indicates the relay node", the relay node may determine that it performs relay communication itself. The relay node may perform data reception work in time slot #n based on the information element included in the SCI. In the case of a failure in receiving data, the relay node may transmit a NACK for the data to the source node in time slot #n+k1 indicated by the SCI.

[0117] When "NACK is received from the destination node in time slot #n+k1 and NACK is received from all candidate relay nodes in time slot #n+k1 (for example, ACK is not received from the candidate relay nodes in time slot #n+k1)", the source node can judge that there is no appropriate relay node (for example, the best relay node) to perform relay communication. That is, the source node can judge that relay communication cannot be performed. In this case, the source node can re-perform direct communication in time slot #n+k2 (for example, the time slot indicated by the relay timing k2 included in the SCI transmitted in time slot #n). The source node can transmit SCI in time slot #n+k2, and can transmit data in time slot #n+k2 based on the information elements included in the SCI. The information elements included in the SCI transmitted in time slot #n+k2 can be the same as or similar to the information elements included in the SCI transmitted in time slot #n. The data transmitted in time slot #n+k2 can be the same as or similar to the data included in the SCI transmitted in time slot #n.

[0118] In the case where the distance between the source node and the destination node exceeds the communication coverage, the destination node may not receive SCI and / or data from the source node. In this case, the destination node may not transmit the HARQ response to the data in the time slot #n+k2+k1 indicated by the SCI. The relay node can receive SCI from the source node in the time slot #n+k2. In the case where "the relay indicator included in the SCI indicates that relay transmission is performed and the candidate relay node ID indicates the relay node", the relay node can determine that it performs relay communication itself. The relay node can receive data from the source node in the time slot #n+k2 based on the information element included in the SCI. In the case of successfully receiving the data, the relay node can transmit the HARQ response (e.g., ACK) to the data to the source node in the time slot #n+k2+k1 indicated by the SCI.

[0119] When "no HARQ response (e.g., ACK) is received from the destination node in time slot #n+k2+k1 and no NACK is received from all candidate relay nodes in time slot #n+k2+k1 (e.g., ACK is received from at least one relay node in time slot #n+k2+k1)", the source node can determine to perform relay communication.

[0120] The relay node may transmit the SCI to the destination node in the time slot #n+k2+k2 indicated by the relay timing k2 included in the SCI received from the source node. The information elements included in the SCI transmitted from the relay node may be the same or similar to the information elements included in the SCI transmitted from the source node. The SCI transmitted from the relay node in the time slot #n+k2+k2 may include scheduling information, the area ID of the source node, feedback timing k1, relay timing k2, relay indicator, candidate relay node information, etc. Here, the relay timing k2 may be set to 0. Alternatively, the SCI transmitted in the time slot #n+k2+k2 may not include the relay timing k2. The relay node may transmit data to the destination node in the time slot #n+k2+k2 based on the information elements included in the SCI.

[0121] The destination node may receive the SCI from the relay node at time slot #n+k2+k2, and may confirm the information element included in the SCI. The destination node may receive data from the relay node at time slot #n+k2+k2 based on the information element included in the SCI. The destination node may transmit a HARQ response (e.g., ACK or NACK) for the data to the relay node at time slot #n+k2+k2+k1 indicated by the feedback timing k1 included in the SCI received from the relay node.

[0122] The relay node may receive a HARQ response for the data from the destination node in time slot #n+k2+k2+k1 and may transmit the HARQ response to the source node. The source node may receive the HARQ response from the relay node and may confirm whether the data has been successfully received at the destination node based on the HARQ response.

[0123] Relay Scenario 2

[0124] Fig.10 is a timing diagram illustrating a first embodiment of a relay scenario 2 in a communication system.

[0125] Reference Fig.10 , the source node may not know the "area ID of the destination node" or the "distance between the source node and the destination node". In this case, the source node may communicate with the destination node using a direct communication method. In the case where a relay transmission request is received from the destination node during the communication process according to the direct communication method, the source node may perform communication based on the relay communication method. The source node may generate an SCI including existing information elements and / or information elements defined in Table 1, and may transmit the SCI in time slot #n. For example, the SCI may include scheduling information, the area ID of the source node, feedback timing k1, relay timing k2, a relay indicator, candidate relay node information, coverage range, etc. The relay indicator included in the SCI may indicate that relay communication is not performed. Alternatively, the SCI may not include a relay indicator. The source node may transmit data in time slot #n based on the information elements included in the SCI.

[0126] The destination node may receive SCI from the source node in time slot #n, and may confirm the area ID field (e.g., the area ID of the source node), the relay indicator field, the coverage field, etc. included in the SCI. The destination node may estimate the distance between itself and the source node based on the area ID of the source node, and may compare the estimated distance with the coverage indicated by the coverage field. The destination node may determine whether relay communication is required based on the comparison result of the estimated distance and the coverage. In the case where it is determined that "the reception (e.g., decoding) of data transmitted from the source node by direct communication fails and relay communication is required", the destination node may transmit NACK and a relay transmission request in time slot #n+k1 indicated by the feedback timing k1 included in the SCI. Alternatively, the destination node may transmit only a relay transmission request to the source node without NACK in time slot #n+k1. The source node and / or the relay node may receive a relay transmission request from the destination node in time slot #n+k1. In this case, the source node and / or the relay node may determine that the destination node has requested relay transmission.

[0127] The source node and / or the relay node may continuously perform monitoring work to receive a relay transmission request from the destination node. The relay transmission request may be set to be transmitted according to a preset period. Alternatively, the relay transmission request may be set to be transmitted at a feedback timing k1 indicated by the SCI. Alternatively, the destination node may transmit the relay transmission request to the source node at a desired time.

[0128] In the case where the destination node requests relay transmission, the relay node may transmit the SCI to the destination node in time slot #n+k2 indicated by the relay timing k2 included in the SCI received from the source node. The information elements included in the SCI transmitted from the relay node may be the same or similar to the information elements included in the SCI transmitted from the source node. The SCI transmitted from the relay node in time slot #n+k2 may include scheduling information, the area ID of the source node, feedback timing k1, relay timing k2, relay indicator, candidate relay node information, etc. Here, the relay indicator may indicate that relay transmission is performed, and the relay timing k2 may be set to 0. Alternatively, the SCI transmitted in time slot #n+k2 may not include relay timing k2. The relay node may transmit data to the destination node in time slot #n+k2 based on the information elements included in the SCI.

[0129] The destination node may receive the SCI from the relay node at time slot #n+k2, and may confirm the information element included in the SCI. The destination node may receive data from the relay node at time slot #n+k2 based on the information element included in the SCI. The destination node may transmit a HARQ response (e.g., ACK or NACK) for the data to the relay node at time slot #n+k2+k1 indicated by the feedback timing k1 included in the SCI received from the relay node.

[0130] The relay node may receive a HARQ response for the data from the destination node in time slot #n+k2+k1 and may transmit the HARQ response to the source node. The source node may receive the HARQ response from the relay node and may confirm whether the data has been successfully received at the destination node based on the HARQ response.

[0131] As another embodiment, the destination node may request relay transmission in other time slots (e.g., time slot #n+k3) instead of time slot #n+k2 indicated by relay timing k2 included in the SCI. In this case, the source node and / or the relay node may select a time slot from time slot #n+k2 and time slot #n+k3, and may perform relay transmission in the selected time slot. The destination node may receive the SCI in time slot #n+k2 and / or time slot #n+k3, and may determine in which time slot the relay transmission is performed based on the information element (e.g., relay indicator) included in the SCI.

[0132] [Synchronous method]

[0133] In the diagram Figure 3 In a communication system, the destination node further performs a synchronization process so that the reception timing of a relay packet (e.g., a packet transmitted through a relay node) can be reset. In this case, a transmission delay may occur. In order to reduce the transmission delay, the TA (timing advance) value can be adjusted in the relay node without changing the reception timing. The area ID can be used to adjust the TA value.

[0134] Fig.11 is a timing diagram illustrating a first embodiment of a method for adjusting a TA value in a communication system.

[0135] Reference Fig.11 , the source node can be 1 Transmit packets (e.g., data). A relay node can 1 +τ 1 (i.e., t 2 ) receives a packet from a source node. In the case of direct communication, the destination node can 1 +τ 3 (i.e., t 3 ) receives packets from the source node. In the case of using relay communication, the relay node can 1 +τ 1 (i.e., t 2 ) receives the packet from the source node and can transmit the packet to the destination node. In this case, the destination node can 1 +τ 1 +τ 2 Receive packets from the source node from the relay node. 1 +τ 2 " can be "τ 3 "above.

[0136] In this case, the difference (τ diff ) can be “τ 1 +τ 2 -τ 3 "In τ diff is the length of the CP (cyclic prefix) (L CP ) or less, if the sending time of the relay node (t relay ) is set to t 2 No problem will occur. diff Exceeding the length of CP (LCP ), if the sending time of the relay node (t relay ) is set to t 2 ISI (inter-symbol interference) will occur. In this case, the destination node must adjust the reception timing to receive the relay packet. Alternatively, the relay node must adjust the TA value. Various methods for the relay node to adjust the TA value will be described in the following embodiments.

[0137] The relay node performs a process of synchronizing with the source node (e.g., a process of transmitting / receiving a synchronization signal), thereby being able to confirm the time (e.g., absolute reception time) at which the relay node receives the packet. 2 The relay node can estimate the propagation delay time τ between the relay node and the source node based on its own location information (e.g., coordinates) and the area ID of the source node. 1 The relay node can be based on the propagation delay time τ 1 It is estimated that t is the time when the source node sends the packet (for example, the absolute sending time). 1 (=t 2 -τ 1 ).

[0138] The relay node can estimate the propagation delay time τ between the source node and the destination node using the area ID of the source node and the area ID of the destination node. 3 The area ID of the source node and the area ID of the destination node can be confirmed from the SCI. The relay node can be based on the propagation delay time τ 3 It is estimated that t is the time when the packet is received at the destination node (for example, the absolute reception time). 3 (=t 1 +τ 3 ).

[0139] The relay node can transfer the sending time (t relay ) is set to "t 3 -τ 2 The relay node may calculate τ based on its own location information (eg, coordinates) and the area ID of the destination node included in the SCI. 2 The TA value applied based on the receiving time of the relay node, i.e., δ TA It can be defined as the following mathematical formula 1.

[0140]

Mathematical formula 1

[0141]

[0142] Fig.12 is a timing chart illustrating a first embodiment of transmission / reception timing of packets in the communication system.

[0143] Reference Fig.12 , the relay node can receive packets from the source node, and the destination node may not receive packets from the source node. The relay node can adjust the TA value to relay the communication between the source node and the destination node. The number of GS (guard symbols) required to adjust the TA value, i.e., N GS It can be defined as the following mathematical formula 2.

[0144]

Mathematical formula 2

[0145]

[0146] Among them, L symb Can be the length of an OFDM symbol. others It may be the time required for other purposes (e.g., transmission / reception switching) other than TA. Since the relay node calculates τ using the area ID of the source node and the area ID of the destination node 3 , so the calculation accuracy may be reduced. To solve this problem, the source node can use its own accurate location information (e.g., coordinates) and the area ID of the destination node to calculate the accurate τ 3 , and can include τ 3 The SCI is transmitted to the relay node. The relay node can receive the SCI from the source node and can confirm the τ included in the SCI. 3 , and can use the confirmed τ 3 .

[0147] On the other hand, each communication node (e.g., source node, relay node, destination node) performs sensing work, thereby being able to receive reference signals from adjacent communication nodes, and being able to measure RSRP (reference signal received power), RSRQ (reference signal received quality), and / or RSSI (received signal strength indicator) for the reference signal. Each communication node can periodically update the link status with the adjacent communication node based on RSRP, RSRQ, and / or RSSI, and can update the list of communication nodes that are conducive to relaying packets (e.g., a list of relay nodes) based on the updated link status.

[0148] When using a direct communication method, the destination node may not receive a packet from the source node. In this case, the destination node may transmit a NACK and / or a list of relay nodes to the source node. The NACK and / or the list of relay nodes may be transmitted to the source node via the PSFCH or PSCCH. The source node may receive a NACK and / or a list of relay nodes from the destination node. In this case, the source node may determine that the packet reception at the destination node has failed, and may determine to use a relay communication method instead of the direct communication method. The source node may select an appropriate relay node considering the list of relay nodes obtained from the destination node, and may perform relay communication through the relay node.

[0149] The list of relay nodes may be updated by performing “demodulation of the SCI of the relay nodes adjacent to the destination node” and / or “measurement of the RSRP, RSRQ and / or RSSI between the destination node and the relay node”. Each communication node may obtain the area ID through the SCI of the adjacent communication node. Therefore, in the case where it is difficult to measure RSRP, RSRQ and / or RSSI, the list of relay nodes may be updated using the area ID of the source node and the area ID of the relay node (e.g., candidate relay node) included in the SCI of the source node. The number of relay nodes may be increased or decreased according to max(PL s,i , PL i,d ) is used to determine the priority of the relay node using the area ID. max(PL s,i , PL i,d ) is smaller, the higher the priority of the relay node will be. The relay node can be selected based on the following mathematical formula 3.

[0150]

Mathematical formula 3

[0151]

[0152] Among them, PL s,i It can be the PL (path loss) between the source node and the i-th relay node. i,d It can be the PL between the i-th relay node and the destination node.

[0153] The various methods according to the present invention are specifically implemented in the form of program instructions that can be executed by various computer devices and can be recorded in a computer-readable medium. The computer-readable medium can include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded in the computer-readable medium can be program instructions specially designed and constructed for the present invention, or can also be program instructions that are well known and can be used by technicians in the field of computer software.

[0154] Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as read-only memory (ROM), random access memory (RAM), and flash memory. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc. The above-mentioned hardware devices can be configured to operate with at least one software module to perform the work of the present invention, and vice versa.

[0155] Although the above description is made with reference to the embodiments, those skilled in the art will appreciate that various modifications and changes can be made to the present invention without departing from the scope of the idea and field of the present invention as described in the appended claims.

Claims

1. A source node working method, which is a source node working method in a communication system, wherein the source node working method is characterized in that it includes: The step of generating SCI (sidelink control information), wherein the SCI includes resource allocation information of the data, feedback timing indicating a time of transmitting a HARQ response to the data, and relay timing indicating a time of executing relay communication; The step of transmitting the SCI to a destination node; The step of transmitting the data to the destination node using the resources indicated by the resource allocation information; and The step of performing monitoring operation in order to receive the above-mentioned HARQ response at the resource indicated by the above-mentioned feedback timing.

2. The working method of the source node according to claim 1, wherein: The working method of the source node further includes: The step of estimating the distance between the source node and the destination node before generating the SCI; The step of comparing the estimated distance with the communication coverage of the source node; and If the estimated distance exceeds the communication coverage, the step of executing the relay communication is determined. In a case where it is determined to perform the relay communication, the SCI is generated to include one or more information elements for the relay communication, and information indicating the communication coverage is included in the SCI.

3. The working method of the source node according to claim 2, wherein: The distance is estimated using the area ID of the destination node.

4. The working method of the source node according to claim 1, wherein: When direct communication without passing through a relay node is performed, the relay timing is set to 0, and when the relay communication is performed, the relay timing is set to a natural number.

5. The working method of the source node according to claim 1, wherein: The SCI further includes a relay indicator, wherein the relay indicator set to a first value indicates that the relay communication is not to be performed, and the relay indicator set to a second value indicates that the relay communication is to be performed.

6. The working method of the source node according to claim 1, wherein: The SCI further includes information indicating one or more relay nodes that perform the relay communication, and the information indicating the one or more relay nodes is updated based on a measurement result of a reference signal received from an adjacent relay node.

7. The working method of the source node according to claim 1, wherein: When the HARQ response is not received from the destination node at the feedback timing and ACK for the data is received from the relay node, or when NACK for the data is received from the destination node at the feedback timing and ACK for the data is received from the relay node, it is determined that the relay communication is performed by the relay node.

8. The working method of the source node according to claim 1, wherein: When NACK for the data is received from the destination node and NACK for the data is received from the relay node at the feedback timing, or when the HARQ response is not received from the destination node and NACK for the data is received from the relay node at the feedback timing, it is determined that the relay communication is not performed by the relay node.

9. The working method of the source node according to claim 1, wherein: When a relay transmission request is received from the destination node at the feedback timing, it is determined that the destination node requests the relay communication.

10. A relay node operation method, which is a relay node operation method for relaying communication between a source node and a destination node in a communication system, wherein the relay node operation method is characterized by comprising: The step of receiving SCI (sidelink control information) from the source node, wherein the SCI includes resource allocation information of the data, feedback timing indicating a time of transmitting a HARQ response to the data, and relay timing indicating a time of executing relay communication; The step of receiving the data from the source node at the resource indicated by the resource allocation information; and The step of transmitting the SCI and the data to the destination node at the resource indicated by the feedback timing.

11. The working method of the relay node according to claim 10, wherein: The relay timing is adjusted according to a TA (timing advance) value determined in consideration of the reception timing of the destination node.

12. The working method of the relay node according to claim 10, wherein: The relay timing is an offset between a time slot when the SCI is received from the source node and a time slot when the SCI is transmitted to the destination node.

13. The working method of the relay node according to claim 10, wherein: The SCI further includes a relay indicator, wherein the relay indicator set to a first value indicates that the relay communication is not to be performed, and the relay indicator set to a second value indicates that the relay communication is to be performed.

14. The working method of the relay node according to claim 10, wherein: The SCI further includes information indicating one or more relay nodes that perform the relay communication, and the relay node performs the relay communication if it belongs to the one or more relay nodes.

15. The working method of the relay node according to claim 10, wherein: The working method of the relay node further includes the step of transmitting an ACK for the data to the source node at the feedback timing when the data is successfully received.

16. A source node, which is a source node in a communication system, wherein the source node is characterized in that it comprises: processor; a memory in electronic communication with the processor; as well as Instructions, which are stored in the above-mentioned memory, When the above-mentioned instructions are executed by the above-mentioned processor, the operation of the above-mentioned instructions causes the above-mentioned source node to perform the following operations: generate SCI (sidelink control information), the above-mentioned SCI includes resource allocation information of data, feedback timing indicating the time of transmission of HARQ response to the above-mentioned data, and relay timing indicating the time of execution of relay communication; transmit the above-mentioned SCI to the destination node; transmit the above-mentioned data to the above-mentioned destination node on the resources indicated by the above-mentioned resource allocation information; and perform monitoring work in order to receive the above-mentioned HARQ response on the resources indicated by the above-mentioned feedback timing.

17. The source node according to claim 16, wherein: When direct communication without passing through a relay node is performed, the relay timing is set to 0. When relay communication is performed, the relay timing is set to a natural number. The relay timing is the offset between the time slot for transmitting the SCI and the execution time of the relay communication.

18. The source node according to claim 16, wherein: The SCI further includes a relay indicator, wherein the relay indicator set to a first value indicates that the relay communication is not to be performed, and the relay indicator set to a second value indicates that the relay communication is to be performed.

19. The source node according to claim 16, wherein: When the HARQ response is not received from the destination node at the feedback timing and ACK for the data is received from the relay node, or when NACK for the data is received from the destination node at the feedback timing and ACK for the data is received from the relay node, it is determined that the relay communication is performed by the relay node.

20. The source node according to claim 16, wherein: When NACK for the data is received from the destination node and NACK for the data is received from the relay node at the feedback timing, or when the HARQ response is not received from the destination node and NACK for the data is received from the relay node at the feedback timing, it is determined that the relay communication is not performed by the relay node.

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