Method and apparatus for contention based early data transmission

Abstract

A method and an apparatus for contention based early data transmission are disclosed. The method of a terminal for contention based early data transmission comprises the steps of: receiving, from a base station, an uplink (UL) resource and transmission reference information for a random access (RA) procedure; on the basis of the transmission reference information, transmitting, to the base station, a contention based-Msg3 (CB-Msg3) including uplink data through at least one from among a plurality of transmission occasions of the UL resource; determining the occurrence of a transmission error for the CB-Msg3; and retransmitting the CB-Msg3 to the base station on the basis of the transmission reference information according to the occurrence of the transmission error for the CB-Msg3.

Description

Method and device for collision-based fast data transmission

[0001] The present disclosure relates to uplink (UL) data transmission technology for a terminal in a non-terrestrial network, and more specifically, to a method and apparatus for contention-based early data transmission (CB-EDT) of uplink data.

[0002] Communication networks can be classified into terrestrial networks and non-terrestrial networks. Non-terrestrial networks may be referred to as NTN (non-terrestrial network). In terrestrial networks, communication services for terminals may be provided by base stations located on the ground. In non-terrestrial networks, communication services for terminals may be provided by base stations located off-ground (e.g., satellites, UAVs (unmanned aerial vehicles), drones, etc.). Communication in terrestrial and non-terrestrial networks may be performed based on NR (New Radio) communication technology.

[0003] Generally, in terrestrial networks, a connection procedure can be performed between a base station and a terminal using a four-step random access (RA) procedure. However, compared to terrestrial networks, non-terrestrial networks have longer signal transmission delays, and a single base station (e.g., a satellite) may cover a large cell area. Therefore, when performing a four-step RA procedure between a satellite and a base station in a non-terrestrial network, the efficiency of data transmission and reception may be degraded. To address this problem, a method of performing the RA procedure between a base station and a terminal using early data transmission (EDT) technology is being proposed. Research is being conducted on RA procedures utilizing this EDT technology as a way to improve efficiency by simplifying the existing four-step RA procedure into a two-step procedure.

[0004] However, even if an EDT-based two-stage RA procedure is applied in non-terrestrial networks, preamble transmission (e.g., Msg 3 or MsgA) and random access response (RAR) transmission (e.g., Msg4 or MsgB) may be required between the terminal and the base station (e.g., satellite). As a result, transmission delays between the base station and the terminal in non-terrestrial networks may be prolonged, which can increase the consumption of radio resources for the RA procedure. Therefore, there is a need for measures to increase the efficiency of the RA procedure between the base station and the terminal in non-terrestrial networks.

[0005] The objective of the present disclosure to address the above-mentioned requirements is to provide a method and apparatus for collision-based fast data transmission in a non-terrestrial network.

[0006] A method for a terminal for collision-based fast data transmission according to an embodiment of the present disclosure for achieving the above objective may include: receiving uplink (UL) resources and transmission reference information for a random access (RA) procedure from a base station; transmitting a collision-based Msg3 (CB-Msg3, contention based-Msg3) containing uplink data to the base station through at least one of a plurality of transmission occasions of the UL resources based on the transmission reference information; determining the occurrence of a transmission error for the CB-Msg3; and retransmitting the CB-Msg3 to the base station based on the transmission reference information based on the occurrence of a transmission error for the CB-Msg3.

[0007] The above transmission reference information may include at least one of coverage enhancement (CE) level reference information, channel status reference information, or transmission error count reference information.

[0008] The step of transmitting the above CB-Msg3 to the base station may include the step of replicating and transmitting the above CB-Msg3 through at least one transmission opportunity based on at least one of the transmission reference information or the measurement result of the terminal.

[0009] The measurement result of the above terminal may include at least one of the signal quality measurement result of the above terminal, the path loss measurement result, or the transmission error count measurement result of the above CB-Msg3.

[0010] The step of determining a transmission error of the above CB-Msg3 may include: a step of monitoring the reception of CB-Msg4 from the base station based on collision resolution window information of the transmission reference information; and a step of determining that a transmission error of the above CB-Msg3 has occurred based on the determination that the above CB-Msg4 has not been received.

[0011] The step of retransmitting the CB-Msg3 to the base station may include the step of retransmitting the CB-Msg3 through at least one additional transmission opportunity based on backoff transmission information of the transmission reference information when the number of transmission errors of the CB-Msg3 is greater than or equal to a transmission error threshold value.

[0012] The step of retransmitting the CB-Msg3 to the base station may include the step of retransmitting the CB-Msg3 after a backoff time based on backoff transmission information of the transmission reference information when the number of transmission errors of the CB-Msg3 is greater than or equal to a transmission error threshold value.

[0013] The step of retransmitting the above CB-Msg3 to the base station may include the step of retransmitting the above CB-Msg3 through at least one of a plurality of transmission opportunities of a new UL resource based on fallback transmission information of the transmission reference information.

[0014] A method of a base station for collision-based fast data transmission according to an embodiment of the present disclosure for achieving the above objective may include: receiving a collision-based Msg3 (CB-Msg3, contention based-Msg3) containing uplink (UL) data from each of a plurality of terminals; determining whether a collision of UL data has occurred between the plurality of CB-Msg3s; decoding at least one UL data that has not collided based on the fact that a collision of UL data has occurred between some of the plurality of CB-Msg3s; performing successive interference cancellation (SIC) on the UL data that has collided using the decoded UL data; and decoding the UL data in which the collision has been resolved by the SIC.

[0015] The method of the base station above may further include the step of transmitting UL resources and transmission reference information for a random access (RA) procedure to each of the plurality of terminals.

[0016] The step of receiving the above CB-Msg3 may include the step of receiving at least one replicated CB-Msg3 through at least one of the plurality of transmission occasions of the UL resource from each of the plurality of terminals.

[0017] The step of receiving the above CB-Msg3 may include receiving at least one CB-Msg3 that has been retransmitted from each of the plurality of terminals based on a transmission error determination result for the CB-Msg3.

[0018] The method of the base station may further include the steps of: setting each individual collision-based early data transmission-radio network temporary identifier (CB-EDT-RNTI) corresponding to each of the plurality of CB-Msg3s based on the decoded UL data; scrambling a physical downlink shared channel (PDSCH) containing CB-Msg4 of each of the plurality of terminals based on the plurality of individual CB-EDT-RNTIs; and transmitting the scrambled CB-Msg4 to each of the plurality of terminals.

[0019] The step of scrambling each CB-Msg4 of the plurality of terminals may further include: selecting a first CB-EDT-RNTI corresponding to the first CB-Msg3 among the plurality of individual CB-EDT-RNTIs; and scrambling a PDSCH containing each CB-Msg4 of the plurality of terminals based on the first CB-EDT-RNTI.

[0020] The method of the base station may further include the steps of: setting a common CB-EDT-RNTI corresponding to all of the plurality of CB-Msg3s based on the decoded UL data; scrambling a PDSCH containing a CB-Msg4 of each of the plurality of terminals based on the common CB-EDT-RNTI; and transmitting the scrambling CB-Msg4 to each of the plurality of terminals.

[0021] A terminal for collision-based fast data transmission according to an embodiment of the present disclosure for achieving the above objective may include at least one processor. The at least one processor may cause the terminal to receive uplink (UL) resources and transmission reference information for a random access (RA) procedure from a base station, transmit a collision-based Msg3 (CB-Msg3, contention based-Msg3) containing uplink data to the base station through at least one of a plurality of transmission occasions of the UL resources based on the transmission reference information, determine the occurrence of a transmission error for the CB-Msg3, and cause the CB-Msg3 to be retransmitted to the base station based on the transmission reference information based on the occurrence of a transmission error for the CB-Msg3.

[0022] The above transmission reference information may include at least one of coverage enhancement (CE) level reference information, channel status reference information, or transmission error count reference information.

[0023] In order to transmit the above CB-Msg3 to the base station, the at least one processor may cause the terminal to duplicate and transmit the above CB-Msg3 through at least one transmission opportunity based on at least one of the transmission reference information or the measurement result of the terminal.

[0024] The measurement result of the above terminal may include at least one of the signal quality measurement result of the above terminal, the path loss measurement result, or the transmission error count measurement result of the above CB-Msg3.

[0025] To determine a transmission error of the above CB-Msg3, the at least one processor may cause the terminal to monitor the reception of CB-Msg4 from the base station based on collision resolution window information of the transmission reference information, and to determine that a transmission error of the above CB-Msg3 has occurred based on the determination that the above CB-Msg4 has not been received.

[0026] In order to retransmit the above CB-Msg3 to the base station, the at least one processor may cause the terminal to retransmit the above CB-Msg3 through at least one additional transmission opportunity based on backoff transmission information of the transmission reference information when the number of transmission errors of the above CB-Msg3 is greater than or equal to a transmission error threshold value.

[0027] In order to retransmit the above CB-Msg3 to the base station, the at least one processor may cause the terminal to retransmit the above CB-Msg3 after a backoff time based on the backoff transmission information of the transmission reference information when the number of transmission errors of the above CB-Msg3 is greater than or equal to a transmission error threshold value.

[0028] In order to retransmit the above CB-Msg3 to the base station, the at least one processor may cause the terminal to retransmit the above CB-Msg3 through at least one of a plurality of transmission opportunities of a new UL resource based on fallback transmission information of the transmission reference information.

[0029] According to the present disclosure, a terminal can improve wireless resource usage efficiency by simplifying the random access procedure in a non-terrestrial network environment by performing a two-stage random access procedure with a base station through collision-based fast data transmission.

[0030] In addition, the terminal can reduce the probability of collision of uplink data and increase the transmission success rate of uplink data by replicating and transmitting a collision-based Msg3 containing the same uplink data through multiple transmission opportunities in the RA procedure with the base station.

[0031] FIG. 1 is a drawing showing a first embodiment of a non-ground network.

[0032] FIG. 2 is a drawing showing a second embodiment of a non-ground network.

[0033] FIG. 3 is a block diagram showing an example of a communication node of a non-terrestrial network.

[0034] FIG. 4 is a flowchart illustrating an example of a collision-based fast data transmission method for uplink data.

[0035] FIG. 5 is a flowchart illustrating an example of setting uplink resources and transmission standards of a base station.

[0036] FIG. 6 is a conceptual diagram showing an example of uplink shared resource configuration.

[0037] FIG. 7 is a conceptual diagram showing an example of uplink resource configuration of a terminal based on uplink shared resources.

[0038] FIG. 8 is a flowchart illustrating an example of setting transmission standards for a base station.

[0039] FIG. 9 is a conceptual diagram showing an example of data replication transmission of a terminal according to transmission standard settings.

[0040] FIG. 10 is a conceptual diagram showing an embodiment of a replication transmission window according to transmission criteria settings.

[0041] FIG. 11 is a conceptual diagram showing another embodiment of a replication transmission window according to transmission standard settings.

[0042] FIG. 12 is a conceptual diagram showing an embodiment of a collision resolution window according to transmission standard settings.

[0043] FIG. 13 is a conceptual diagram showing another embodiment of a collision resolution window according to the operation standard setting.

[0044] FIG. 14 is a conceptual diagram showing an embodiment of a backoff transmission operation of a terminal according to a transmission standard setting.

[0045] FIG. 15 is a conceptual diagram showing another embodiment of the backoff transmission operation of a terminal according to the transmission standard setting.

[0046] FIG. 16 is a flowchart illustrating an example of an uplink data decoding method of a base station.

[0047] FIG. 17 is a conceptual diagram showing an example of an uplink data decoding method of a base station.

[0048] The present disclosure is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present disclosure to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present disclosure.

[0049] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0050] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0051] The terms used in this disclosure are used merely to describe specific embodiments and are not intended to limit this disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this disclosure, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0052] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this disclosure pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this disclosure.

[0053] A communication network to which embodiments according to the present disclosure are applied will be described. The communication network may be a non-terrestrial network (NTN), a 4G communication network (e.g., a long-term evolution (LTE) communication network), a 5G communication network (e.g., a new radio (NR) communication network), a B5G mobile communication network (e.g., a 6G mobile communication network), etc. 4G communication networks and 5G communication networks may be classified as terrestrial networks.

[0054] In an embodiment, "an operation (e.g., a transmission operation) being set in a communication node" may mean that "setting information for said operation (e.g., an information element, a parameter)" and / or "information directing the execution of said operation" is signaled to said communication node. In other words, "an operation (e.g., a transmission operation) being set in a communication node" may mean that said communication node receives "setting information for said operation (e.g., an information element, a parameter)" and / or "information directing the execution of said operation." "An information element (e.g., a parameter) being set in a communication node" may mean that said information element is signaled to said communication node (e.g., said communication node receiving said information element). The signaling may be at least one of SI (system information) signaling (e.g., transmission of SIB (system information block) and / or MIB (master information block)), RRC signaling (e.g., transmission of RRC parameters and / or upper layer parameters), MAC CE (control element) signaling, or PHY signaling (e.g., transmission of DCI (downlink control information), UCI (uplink control information), and / or SCI (sidelink control information).

[0055] In the present disclosure, even when a method performed at a first communication node among the communication nodes (e.g., transmission or reception of a signal) is described, the corresponding second communication node may perform a method corresponding to the method performed at the first communication node (e.g., reception or transmission of a signal). For example, when the operation of a terminal is described, the base station corresponding to the terminal may perform an operation corresponding to the operation of the terminal. Conversely, when the operation of a base station is described, the terminal corresponding to the base station may perform an operation corresponding to the operation of the base station. Furthermore, when the operation of a first terminal is described, the second terminal corresponding to the first terminal may perform an operation corresponding to the operation of the first terminal. Conversely, when the operation of a second terminal is described, the first terminal corresponding to the second terminal may perform an operation corresponding to the operation of the second terminal.

[0056] Throughout the specification, the term "terminal" may refer to a mobile station, mobile terminal, subscriber station, portable subscriber station, user equipment, access terminal, etc., and may include all or part of the functions of a terminal, mobile station, mobile terminal, subscriber station, portable subscriber station, user equipment, access terminal, etc.

[0057] Here, a desktop computer, laptop computer, tablet PC, wireless phone, mobile phone, smartphone, smart watch, smart glass, e-book reader, PMP (portable multimedia player), portable game console, navigation device, digital camera, DMB (digital multimedia broadcasting) player, digital audio recorder, digital audio player, digital picture recorder, digital picture player, digital video recorder, digital video player, etc., capable of communicating with a terminal can be used.

[0058] Throughout the specification, the term "base station" may refer to an access point, a radio access station, a node B, an evolved node B, a base transceiver station, a mobile multihop relay (MMR)-BS, etc., and may include all or part of the functions of a base station, access point, radio access station, node B, eNodeB, base transceiver station, MMR-BS, etc.

[0059] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding of the present disclosure, the same reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0060] FIG. 1 is a drawing showing a first embodiment of a non-ground network.

[0061] Referring to FIG. 1, the non-ground network (100) of the present embodiment may be a communication network based on at least one satellite (110). The non-ground network (100) may include a satellite (110), a communication node (120), a gateway (130), a data network (140), etc. The non-ground network (100) of FIG. 1 may be a non-ground network based on a transparent payload.

[0062] The satellite (110) can operate as a non-ground base station in a non-ground network. Such a satellite (110) may be a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, a high elliptical orbit (HEO) satellite, or an unmanned aircraft system (UAS) platform. A UAS platform may include a high altitude platform station (HAPS).

[0063] The communication node (120) may include a communication node located on the ground and a communication node located off the ground. The communication node located on the ground may be a UE (user equipment) or a terminal, etc. The communication node located off the ground may be an airplane or a drone, etc.

[0064] A service link may be established between the satellite (110) and the communication node (120). The service link may be a radio link. The satellite (110) may provide communication services to the communication node (120) using one or more beams. The shape of the beam footprint of the satellite (110) may be elliptical. One of the beam footprints of the satellite (110) may have a range of 500 to 1,000 km, and multiple communication nodes (120) may be located within one beam footprint.

[0065] A communication node (120) can perform downlink or uplink communication with a satellite (110) using LTE technology or NR technology. Communication between the satellite (110) and the communication node (120) can be performed using an NR-Uu interface. If dual connectivity (DC) is supported, the communication node (120) can be connected not only to the satellite (110) but also to another base station (e.g., a base station supporting LTE or NR functions), and can perform DC operations based on technology defined in the LTE or NR specifications.

[0066] The gateway (130) may be located on the ground, and a feeder link may be established between the satellite (110) and the gateway (130). The feeder link may be a wireless link. The gateway (130) may be referred to as a non-terrestrial network (NTN) gateway. Communication between the satellite (110) and the gateway (130) may be performed based on an NR-Uu interface or a satellite radio interface (SRI). The gateway (130) may be connected to a data network (140).

[0067] A core network may exist between the gateway (130) and the data network (140). In this case, the gateway (130) may be connected to the core network, and the core network may be connected to the data network (140). The core network may support NR technology. For example, the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc. Communication between the gateway (130) and the core network may be performed based on an NG-C / U interface.

[0068] Alternatively, a ground base station and a core network may exist between the gateway (130) and the data network (140). In this case, the gateway (130) may be connected to the ground base station, the ground base station may be connected to the core network, and the core network may be connected to the data network (140). The ground base station and the core network may support NR technology. Communication between the gateway (130) and the ground base station may be performed based on an NR-Uu interface, and communication between the ground base station and the core network may be performed based on an NG-C / U interface.

[0069] FIG. 2 is a drawing showing a second embodiment of a non-ground network.

[0070] Referring to FIG. 2, the non-ground network (200) of the present embodiment may be a communication network based on a plurality of satellites (211, 212). The non-ground network (200) may include a first satellite (211), a second satellite (212), a communication node (220), a gateway (230), a data network (240), etc.

[0071] The non-ground network (200) illustrated in FIG. 2 may be a non-ground network based on a regenerative payload. For example, each of the first satellite (211) and the second satellite (212) may perform a regenerative operation on a payload received from another entity constituting the non-ground network (200), such as a communication node (220) or a gateway (230), and may transmit the regenerated payload. Here, the regenerative operation may be a demodulation operation, a decoding operation, a re-coding operation, a re-modulation operation, or a filtering operation.

[0072] The first satellite (211) and the second satellite (212) may be LEO satellites, MEO satellites, GEO satellites, HEO satellites, or UAS platforms. The UAS platform may include HAPS. The first satellite (211) may be connected to the second satellite (212), and an inter-satellite link (ISL) may be established between the first satellite (311) and the second satellite (212). The ISL may operate in a radio frequency (RF) band or an optical band. The ISL may be set optionally.

[0073] The communication node (220) may include a communication node located on the ground and a communication node located off the ground. The communication node located on the ground may be a UE (user equipment) or a terminal, etc. The communication node located off the ground may be an airplane or a drone, etc.

[0074] A service link may be established between the first satellite (211) and the communication node (220). The service link may be a radio link. The first satellite (211) may provide communication services to the communication node (220) using one or more beams. The shape of the reception range of the beam of the first satellite (211) may be elliptical.

[0075] The communication node (220) can perform downlink communication or uplink communication with the first satellite (211) using LTE technology or NR technology. Communication between the first satellite (211) and the communication node (220) can be performed using an NR-Uu interface. If DC is supported, the communication node (220) can be connected to the first satellite (211) as well as other base stations that support LTE or NR functions, and can perform DC operations based on technology defined in the LTE or NR specifications.

[0076] The gateway (230) may be located on the ground. A feeder link may be established between the first satellite (211) and the gateway (230) or between the second satellite (212) and the gateway (230). The feeder link may be a wireless link. If an ISL is not established between the first satellite (211) and the second satellite (212), a feeder link between the first satellite (211) and the gateway (230) may be established mandatorily. Communication between the first satellite (211) and the second satellite (212), respectively, and the gateway (230) may be performed based on an NR-Uu interface or SRI.

[0077] A core network may exist between the gateway (230) and the data network (240). In this case, the gateway (230) may be connected to the core network, and the core network may be connected to the data network (240). The core network may support NR technology. For example, the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc. Communication between the gateway (230) and the core network may be performed based on an NG-C / U interface.

[0078] Alternatively, a ground base station and a core network may exist between the gateway (230) and the data network (240). In this case, the gateway (230) may be connected to the ground base station, the ground base station may be connected to the core network, and the core network may be connected to the data network (240). The ground base station and the core network may support NR technology. Communication between the gateway (230) and the ground base station may be performed based on an NR-Uu interface, and communication between the ground base station and the core network may be performed based on an NG-C / U interface.

[0079] FIG. 3 is a block diagram showing an example of a communication node of a non-terrestrial network.

[0080] Referring to FIG. 3, the communication node (300) may include at least one processor (310), a memory (320), and a transceiver (330) that is connected to a network to perform communication. Additionally, the communication node (300) may further include an input interface device (340), an output interface device (350), a storage device (360), etc. Each component included in the communication node (300) may be connected by a bus (370) to communicate with one another.

[0081] However, each component included in the communication node (300) may be connected via individual interfaces or individual buses centered around the processor (310), rather than via a common bus (370). For example, the processor (310) may be connected via a dedicated interface to at least one of a memory (320), a transmission / reception device (330), an input interface device (340), an output interface device (350), or a storage device (360).

[0082] The processor (310) can execute a program command stored in at least one of memory (320) or storage device (360). The processor (310) may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the methods according to embodiments of the present disclosure are performed.

[0083] Each of the memory (320) and the storage device (360) may be composed of at least one of a volatile storage medium or a non-volatile storage medium. For example, the memory (320) may be composed of at least one of read-only memory (ROM) or random access memory (RAM).

[0084] FIG. 4 is a flowchart illustrating an example of a collision-based fast data transmission method for uplink data.

[0085] The base station illustrated in FIG. 4 may be a satellite of a non-terrestrial network, and the terminal may be an Internet of Things (IoT) terminal. According to an embodiment, the satellite may be a transparent satellite capable of receiving a signal from a ground station (e.g., a gateway) via a feeder link and transmitting it to the terminal, or a regenerative satellite capable of communicating with the terminal by including the functions of a base station. According to an embodiment, the terminal may include a sensor or a data collection device capable of collecting data for various IoT applications, such as temperature, humidity, atmospheric pressure, and environment.

[0086] Referring to FIG. 4, the base station and the terminal can perform a two-stage random access (RA) procedure according to the contention-based early data transmission (CB-EDT) method. CB-EDT may be a method in which the terminal can reduce the probability of data collision by duplicating or repeatedly transmitting the same data to multiple resource slots (or transmission opportunities). For the CB-EDT-based RA procedure with the terminal, the base station may set uplink (UL) resources or criteria for message transmission for the transmission of the terminal's message, e.g., CB-Msg3 or CB-MsgA (S410). The base station may transmit the set UL resource or transmission criteria information to the terminal (S420). The base station may transmit (or broadcast) the UL resource and transmission criteria information to the terminal by including them in a system information block (SIB). The base station may repeatedly transmit the SIB containing the UL resource and transmission criteria information to the terminal at set intervals. According to an embodiment, the base station can transmit UL resource and transmission reference information to the terminal through a radio resource control (RRC) reconfiguration message.

[0087] According to an embodiment, CB-Msg3 may be in the form of an RRC Early Data Request message of the existing Early Data Transmission (EDT) method. CB-Msg3 may include information entities such as a temporary mobile subscriber identity (S-TMSI), a contention resolution identity, an establishment cause, or dedicated NAS information (dedicatedInfoNas). S-TMSI is a temporary identifier of a terminal managed by an MME and may consist of an MME code and M-TMSI (Mobile TMSI). The MME code may be an identification code of the MME to which the terminal is connected, and M-TMSI may be a value that temporarily identifies a specific terminal. The contention resolution identifier is information used to determine whether a collision has been resolved upon receiving CB-msg4 and may be included in CB-Msg3 through a MAC information entity (e.g., MAC CE).

[0088] FIG. 5 is a flowchart illustrating an example of setting uplink resources and transmission standards of a base station.

[0089] Referring to FIG. 5, the base station can configure UL resources for the transmission of CB-Msg3 of the terminal based on a shared resource configuration (S510). The shared resources may include time domain resources and frequency domain resources.

[0090] FIG. 6 is a conceptual diagram showing an example of an uplink shared resource, and FIG. 7 is a conceptual diagram showing an example of an uplink resource setting of a terminal based on an uplink shared resource.

[0091] Referring to FIG. 6, the UL shared resource may include a plurality of transmission resource (or resource) sets for CB-Msg3 transmission of the terminal. Each of the plurality of transmission resource sets may include at least one transmission opportunity, and each transmission opportunity may include a plurality of frequency transmission opportunities. For example, the plurality of transmission resource sets may include a first transmission resource set and a second transmission resource set. The first transmission resource set and the second transmission resource set may be repeated in a set resource set cycle. The first transmission resource set may include four transmission opportunities, and the second transmission resource set may include two transmission opportunities. The transmission opportunities of each transmission resource set may have a set transmission opportunity cycle. Each transmission opportunity of the first transmission resource set and the second transmission resource set may include n frequency resource transmission opportunities (R0 to Rn-1).

[0092] Referring to FIG. 7, a base station can set UL resources for at least one terminal in each transmission resource set based on the UL shared resource configuration illustrated in FIG. 6. For example, the base station can set the UL resources of the terminal through time domain resource configuration and frequency domain resource configuration in at least one transmission resource set of the UL shared resource configuration. The base station can transmit information about the set UL resources to the terminal. The UL resource information may include time domain resource configuration information and frequency domain resource configuration information.

[0093] Time domain resource configuration information may include at least one of a start time, a periodicity, or a number of transmission opportunities. The start time may define the start time of a UL resource available for the terminal's CB-Msg3 transmission. The periodicity may include a resource set periodicity and a transmission opportunity periodicity. The number of transmission opportunities may be the number of transmission opportunities included in a single transmission resource set.

[0094] Frequency domain resource configuration information may include at least one of a starting resource block (starting RB) or an allocated resource block (allocated RB). The starting resource block may be defined as an index for the frequency resource. The allocated resource block may be defined as a bitstream for the frequency resource. According to an embodiment, the frequency domain resource configuration information may further include orthogonal cover code (OCC) configuration information. OCC may be used to reduce the probability of collision resulting from multiple terminals multiplexing in the same frequency domain resource. The OCC configuration information may include at least one of an OCC sequence length or a sequence value. According to an embodiment, the UL resource information may further include at least one of a repetition number or a replica number for the terminal's CB-Msg3. The repetition number may be the number of transmission resource sets in which the terminal can transmit a CB-Msg3 containing the same data. The number of replicated transmissions may be the number of replicated transmissions in which the terminal can transmit CB-Msg3 to at least one transmission opportunity of the transmission resource set.

[0095] Referring again to FIG. 5, the base station can set a CB-Msg3 transmission standard for the terminal (S520). The transmission standard may include at least one of coverage enhancement (CE) level standard information, channel state standard information, transmission error count standard information, or replication transmission window information for the CB-Msg3 replication transmission operation of the terminal. According to an embodiment, the transmission standard may include at least one of collision resolution window information, backoff transmission information, or fallback transmission information for the operation after the CB-Msg3 replication transmission of the terminal.

[0096] FIG. 8 is a flowchart illustrating an example of setting transmission standards for a base station.

[0097] Referring to FIG. 8, the base station can set CE level reference information for CB-Msg3 replication transmission of the terminal (S810). The CE level reference information may include at least one CE level distinguished based on the signal quality measurement of the terminal. Each CE level may be distinguished based on a threshold value corresponding to a signal quality measurement value such as the RSRP (reference signal received power) or SNR (signal to noise ratio) of the terminal, as shown in [Table 1] below.

[0098] CE Level RSRP Range (dBm) SNR Range (dB) 0> -110> 01 -120 ~ -110 ~ 02< -120< -5

[0099] According to an embodiment, the base station may set at least one of the number of repeated transmissions or duplicate transmissions of CB-Msg3 for each CE level, as shown in [Table 2] below, corresponding to each CE level. The base station may set the number of repeated transmissions or duplicate transmissions of CB-Msg3 by the terminal to increase as the CE level increases.

[0100] CE Level CB-Msg3 Repeat Transfers CB-Msg3 Replication Transfers 01 ~ 2118 ~ 322264 ~ 1284

[0101] According to an embodiment, the base station may set at least one of the number of CB-Msg3 clone transmissions or the clone transmission ratio for each CE level, as shown in [Table 3] below, corresponding to each CE level. The base station may set the number of CB-Msg3 clone transmissions or the clone transmission ratio to increase as the CE level decreases. Here, the clone transmission ratio may be the ratio of the actual clone transmission opportunity to the total transmission opportunity for which the terminal can perform CB-Msg3 clone transmission. For example, if the total transmission opportunity (or number) for which the terminal can perform CB-Msg3 clone transmission is 10 and the clone transmission ratio according to the CE level is 50%, the terminal may perform 5 clone transmissions for CB-Msg3.

[0102] CE Level CB-Msg3 Replication Transfer Count CB-Msg3 Replication Transfer Rate (%) 0 1 0 1 0 0 1 5 5 0 2 3 3 0

[0103] The base station can transmit the set CE level reference information to the terminal (S820). The base station can transmit the CE level reference information to the terminal via an SIB or RRC reset message.

[0104] The base station can transmit a reference signal (RS) to the terminal for measuring the signal quality of the terminal (S830). The base station can repeatedly transmit the RS to the terminal according to a set period.

[0105] The terminal can measure the signal quality of the RS received from the base station, for example, RSRP or SNR (S840). The terminal can compare the measurement result with CE level reference information and select one CE level based on the comparison result (S850). Based on the selected CE level, the terminal can determine the replication transmission method of Msg3, for example, the number of replication transmissions or the number of repeated transmissions (S860).

[0106] FIG. 9 is a conceptual diagram showing an example of data replication transmission of a terminal according to transmission standard settings.

[0107] Referring to FIG. 9, the base station can set UL resources and transmission criteria for CB-Msg3 clone transmission of the terminal. The UL resources may include sets of seven transmission resources. Each set of transmission resources may include six transmission opportunities, and each transmission opportunity may include four frequency transmission opportunities. The transmission criteria may include at least one of channel state reference information or transmission error count reference information for CB-Msg3 clone transmission.

[0108] Channel state reference information may include at least one path loss (PL) level distinguished based on the channel state of the terminal. Each PL level may include at least one of a transmission resource set selection parameter or a transmission opportunity selection parameter per PL level, as shown in [Table 4] below. Here, each PL level may be defined based on a pre-set threshold range.

[0109] PL Level Transfer Resource Set Select Transfer Opportunity Select A11B0.50.5C0.30.5

[0110] The transmission error count reference information may include at least one transmission error threshold value distinguished based on the terminal's CB-Msg3 transmission error (or, failure) detection time and the number of transmission errors. Each transmission error threshold value may include at least one of a backoff resource set selection parameter or a transmission opportunity selection parameter per transmission error threshold value, as shown in [Table 5] below.

[0111] Transmission error threshold Backoff Resource set selection Transmission chance selection 001120.5330.1

[0112] Hereinafter, the CB-EDT-based CB-Msg3 replication transmission operation of the terminal will be described when the base station transmits a transmission standard including channel state reference information to the terminal. The base station may transmit the configured UL resource and channel state reference information to the terminal via a SIB or RRC reset message. In addition, the base station may transmit at least one RS to the terminal for determining the channel state of the terminal.

[0113] The terminal can measure the RSRP for the received RS and determine the path loss based on the measurement result. The path loss can be determined as shown in [Equation 1] below, based on the terminal's maximum transmission power and RS reception strength.

[0114]

[0115] Here, Pmax can be the maximum transmission power, and RSRP can be the measured RS reception strength.

[0116] The terminal can select one PL level from at least one PL level of channel state reference information based on the determined path loss. For example, the terminal can select the corresponding PL level based on the range to which the determined path loss value belongs within the threshold value range of each PL level. The terminal can determine the replication transmission method of CB-Msg3 based on the selected PL level.

[0117] According to an embodiment, if the PL level determined at the terminal corresponds to PL level A of [Table 4], the terminal can perform duplicate transmission of CB-Msg3 in all slots of the set of 7 transmission resources shown in FIG. 9, that is, in all transmission opportunities.

[0118] According to an embodiment, if the PL level determined at the terminal corresponds to PL level B of [Table 4], the terminal may perform duplicate transmission of CB-Msg3 in 50% of the transmission resource sets of the seven transmission resource sets shown in FIG. 9 and in 50% of the transmission opportunities of the said transmission resource sets. For example, the terminal may perform duplicate transmission of CB-Msg3 in the odd-numbered transmission opportunities of the odd-numbered transmission resource sets among the entire transmission resource sets.

[0119] Hereinafter, the CB-Msg3 replication transmission operation of the terminal will be described when the base station transmits a transmission standard including transmission error count standard information to the terminal. The base station may transmit the configured UL resource and transmission error count standard information to the terminal via an SIB or RRC reset message.

[0120] As described above, the transmission error count reference information may include the CB-Msg3 transmission error detection time of the terminal. The terminal may determine the number of CB-Msg3 transmission errors during the set transmission error detection time. The terminal may determine the number of CB-Msg3 transmission errors when a response to CB-Msg3, for example, CB-Msg4, is not received from the base station.

[0121] Referring to FIG. 9, the terminal can perform CB-Msg3 replication transmission in transmission resource set #1. The terminal may not receive a response to the CB-Msg3 transmission, e.g., CB-Msg4, from the base station during a preset transmission error detection time. Based on the failure to receive CB-Msg4, the terminal can increment an internal transmission error counter by 1. Based on the counter value, the terminal can select a transmission error threshold having a value less than or equal to the counter value from transmission error count reference information. Based on the selected transmission error threshold, the terminal can determine the CB-Msg3 replication transmission method.

[0122] According to an embodiment, when the transmission error threshold selected by the terminal corresponds to 1 in [Table 5], the terminal may determine a CB-Msg3 replication transmission method based on a backoff resource set 2 and a transmission opportunity selection 0.5 corresponding to the transmission error threshold. The terminal may not transmit CB-Msg3 during transmission resource sets #2 and #3 shown in FIG. 9. The terminal may perform CB-Msg3 replication transmission by applying 50% of the transmission opportunity of transmission resource set #4.

[0123] According to an embodiment, the transmission error count reference information may include a transmission opportunity selection parameter corresponding to each of at least one transmission error threshold value. As described above, the terminal may perform CB-Msg3 replication transmission in transmission resource set #1, and if it fails to receive CB-Msg4 from the base station during the transmission error detection time, it may increase the transmission error counter by 1. The terminal may select a transmission error threshold value based on the counter value. If the selected transmission error threshold value corresponds to 1 in [Table 5], the terminal may determine a CB-Msg3 replication transmission method based on a transmission opportunity selection of 0.5 corresponding to the transmission error threshold value. For example, the terminal may perform CB-Msg3 replication transmission by applying a transmission opportunity of 50% in each of the seven transmission resource sets shown in FIG. 9.

[0124] FIG. 10 is a conceptual diagram showing one embodiment of a replication transmission window according to transmission criteria settings, and FIG. 11 is a conceptual diagram showing another embodiment of a replication transmission window according to transmission criteria settings.

[0125] Referring to FIGS. 10 and 11, the base station may set replication transmission window information as a transmission standard for the CB-Msg3 replication transmission, along with UL resources for the CB-Msg3 replication transmission of the terminal. Based on the replication transmission window information, the terminal may select at least one transmission opportunity for the CB-Msg3 replication transmission.

[0126] According to an embodiment, the replication transmission window may be a fixed replication transmission window. The fixed replication transmission window may be in a form where the starting transmission opportunity (or starting slot) for the CB-Msg3 replication transmission of the terminal is fixedly allocated according to the set transmission opportunity cycle.

[0127] For example, as illustrated in FIG. 10, one transmission resource set of UL resources may include 15 transmission opportunities, of which 8 transmission opportunities may be configured for the transmission of CB-Msg3 of the terminal. One transmission resource set may include 3 replication transmission windows. The size (or number of transmission opportunities) of each replication transmission window may be 5. Each replication transmission window may be a fixed replication transmission window in which the starting transmission opportunity is fixedly allocated. For example, the starting transmission opportunity of each replication transmission window may be fixedly allocated to #0, #5, and #10, respectively, among the total transmission opportunities of the transmission resource set. Thus, each replication transmission window may not overlap with one another within one transmission resource set.

[0128] According to an embodiment, the replication transmission window may be a variable replication transmission window. The variable replication transmission window may be in a form where a starting transmission opportunity (or, starting slot) for CB-Msg3 replication transmission is allocated to a transmission opportunity selected by the terminal.

[0129] For example, as illustrated in FIG. 11, one transmission resource set of UL resources may include 15 transmission opportunities, of which 8 transmission opportunities may be configured for the terminal's CB-Msg3 transmission. One transmission resource set may include two duplicate transmission windows. The size (or number of transmission opportunities) of each duplicate transmission window may be 5. Each duplicate transmission window may have a starting transmission opportunity selected by the terminal. For example, the starting transmission opportunity of each duplicate transmission window may be variably allocated as #2 or #5 among the total transmission opportunities of the transmission resource set per terminal. Accordingly, each duplicate transmission window may partially overlap within one transmission resource set.

[0130] A base station may transmit a transmission standard to each of a plurality of terminals, the transmission standard including information on at least one of a fixed replication transmission window or a variable replication transmission window. Each of the plurality of terminals may determine whether to replicate transmission of CB-Msg3 in the corresponding replication transmission window based on the start transmission opportunity of the replication transmission window information. Each of the plurality of terminals may perform replication transmission of CB-Msg3 through the selected replication transmission window according to the determination result.

[0131] FIG. 12 is a conceptual diagram showing one embodiment of a collision resolution window according to transmission standard settings, and FIG. 13 is a conceptual diagram showing another embodiment of a collision resolution window according to transmission standard settings.

[0132] Referring to FIGS. 12 and 13, the base station may set collision resolution window information as a transmission standard for the period following the CB-Msg3 replication transmission, along with UL resources for the terminal's CB-Msg3 replication transmission. The terminal may monitor the reception of CB-Msg4 from the base station based on the collision resolution window information. The collision resolution window information may include a collision resolution window defined as a specific time interval for monitoring the reception of CB-Msg4. The start time of the collision resolution window may be determined by considering the transmission delay between the base station and the terminal based on the terminal's CB-Msg3 transmission time. The transmission delay may be determined as the sum of the terminal's round trip time (RTT) and an offset. Here, the offset may be a time value for considering the base station's CB-Msg3 processing time or scheduling delay.

[0133] According to an embodiment, the collision resolution windows may be composed of a plurality of windows. As illustrated in FIG. 12, each of the plurality of collision resolution windows may be defined corresponding to each of the duplicated transmitted CB-Msg3s. For example, collision resolution window #0 may be defined corresponding to the CB-Msg3 transmitted in transmission opportunity #0, and collision resolution window #1 may be defined corresponding to the CB-Msg3 transmitted in transmission opportunity #1. The start time of each collision resolution window may be determined based on the transmission delay (RTT + offset) for the CB-Msg3 relative to the time when the corresponding CB-Msg3 is transmitted.

[0134] According to an embodiment, the collision resolution window may be configured as a single window. As illustrated in FIG. 13, the single collision resolution window may be defined corresponding to all duplicated transmitted CB-Msg3s. For example, the single collision resolution window may be defined corresponding to the CB-Msg3 transmitted in transmission opportunity #0 and the CB-Msg3 transmitted in transmission opportunity #1. The collision resolution window may have a start time determined based on the transmission delay (RTT + offset) for all CB-Msg3s relative to the time when the corresponding CB-Msg3 was transmitted.

[0135] According to an embodiment, the collision resolution window may be composed of a single collision resolution window, and the entire section of the single collision resolution window may be divided according to the number of CB-Msg3s. The terminal may monitor the reception of CB-Msg4 corresponding to CB-Msg3s in each section of the collision resolution window. For example, the terminal may determine whether Msg4 is received by monitoring a terminal-specific temporary identifier, for example, an RNTI (radio network temporary identifier), in each section of the collision resolution window.

[0136] As described above, the base station may transmit a transmission standard including collision resolution window information to the terminal along with UL resources allocated for the terminal's CB-Msg3 replication transmission. The collision resolution window information may include at least one of the window type, window size, round-trip delay time, or offset information of the said collision resolution window.

[0137] FIG. 14 is a conceptual diagram showing one embodiment of a backoff transmission operation of a terminal according to a transmission standard setting, and FIG. 15 is a conceptual diagram showing another embodiment of a backoff transmission operation of a terminal according to a transmission standard setting.

[0138] Referring to FIGS. 14 and 15, the base station may set backoff transmission information as a transmission standard for the period following the CB-Msg3 replication transmission, along with UL resources for the CB-Msg3 replication transmission of the terminal. Backoff transmission may be a method of retransmitting the CB-Msg3 at a specific point in time when a CB-Msg3 transmission error (or failure) of the terminal occurs.

[0139] According to an embodiment, backoff transmission information may include a retransmission parameter for retransmitting the CB-Msg3 using an additional transmission opportunity when a CB-Msg3 transmission error occurs at the terminal. The retransmission parameter may include at least one of the terminal's CB-Msg3 initial transmission resource information (e.g., a transmission resource set or a transmission opportunity), the terminal's CB-Msg3 retransmission resource information (e.g., an additional transmission resource set or an additional transmission opportunity), or a transmission error threshold. For example, as illustrated in FIG. 14, a CB-Msg3 transmission error may occur at the terminal in transmission resource sets #1 to #3. The terminal may determine backoff transmission for the corresponding CB-Msg3 when the number of transmission errors is greater than or equal to the transmission error threshold of the retransmission parameter. Based on the retransmission resource information, the terminal may retransmit the CB-Msg3 to the base station using at least one additional transmission resource set or transmission opportunity allocated.

[0140] According to an embodiment, backoff transmission information may include a retransmission parameter for retransmitting the CB-Msg3 after a certain delay time (backoff time) when a CB-Msg3 transmission error occurs at the terminal. The retransmission parameter may include at least one of the terminal's CB-Msg3 transmission resource information (e.g., transmission resource set or transmission opportunity), backoff time information, or a transmission error threshold. For example, as illustrated in FIG. 15, a CB-Msg3 transmission error may occur at the terminal in transmission resource sets #1 to #3. The terminal may determine backoff transmission for the CB-Msg3 when the number of transmission errors is greater than or equal to the transmission error threshold of the retransmission parameter. The terminal may stop transmitting the CB-Msg3 for a certain period of time based on the backoff time information. After the backoff time has ended, the terminal may retransmit the CB-Msg3 to the base station using the transmission resource set or transmission opportunity based on the transmission resource information.

[0141] Meanwhile, if the transmission failure of CB-Msg3 retransmitted to the base station based on backoff transmission information is repeated, the terminal may consider fallback transmission. Fallback transmission may be a method in which the terminal retransmits CB-Msg3 to the base station through a transmission resource other than the current transmission resource. The base station may set a transmission standard including the terminal's fallback transmission information and transmit it to the terminal along with UL resource information set for the terminal's CB-Msg3 transmission. The fallback transmission information may include at least one of UL carrier information of a frequency band different from the currently used UL carrier, transmission setting information corresponding to an upgraded CE level, or resource information for a random access procedure based on a physical random access channel (PRACH). According to an embodiment, the terminal may select a carrier with a different frequency band based on the UL carrier information of the fallback transmission information and retransmit CB-Msg3 to the base station using it. According to an embodiment, the terminal can retransmit CB-Msg3 to the base station through a transmission resource with a high transmission probability by applying a transmission setting corresponding to an elevated CE level. According to an embodiment, the terminal can retransmit CB-Msg3 to the base station by performing a PRACH-based 4-step RA procedure.

[0142] Referring again to FIG. 4, the terminal can transmit a collision-based Msg3 (CB-Msg3) containing uplink data to the base station based on UL resources and transmission reference information received from the base station (S430). For example, the terminal can duplicate-transmit CB-Msg3 through a preset UL resource based on at least one of the CE level reference information, channel state reference information, transmission error count reference information, or duplicate transmission window information of the transmission reference information.

[0143] The terminal can determine that the transmission of CB-Msg3 has failed (S440). For example, the terminal can monitor the reception of CB-Msg4 from the base station based on the collision resolution window information of the transmission reference information. The terminal can determine that the transmission of CB-Msg3 has failed if CB-Msg4 has not been received from the base station.

[0144] The terminal can retransmit CB-Msg3 to the base station. The retransmitted CB-Msg3 may contain the same data as the previously transmitted CB-Msg3 (S450). For example, the terminal can retransmit CB-Msg3 based on at least one of backoff transmission information or fallback transmission information of the transmission reference information.

[0145] The base station can perform data collision resolution and decoding on the received CB-Msg3 (S460). For example, the base station may receive a CB-Msg3 containing multiple uplink data transmitted by each of multiple terminals using the same UL resource (e.g., the same transmission opportunity). The base station may decode the data in which a collision occurred among the multiple uplink data of the received CB-Msg3 through collision resolution.

[0146] FIG. 16 is a flowchart illustrating an example of an uplink data decoding method of a base station, and FIG. 17 is a conceptual diagram illustrating an example of an uplink data decoding method of a base station.

[0147] Referring to FIGS. 16 and 17, a base station can receive a CB-Msg3 containing uplink data from each of a plurality of terminals. For example, as shown in FIG. 17, the base station can receive a CB-Msg3 of terminal #8 at frequency resource R0 of transmission opportunity #0 of a UL resource, receive CB-Msg3s of terminal #6 and terminal #12 respectively at frequency resource R1, and receive a CB-Msg3 of terminal #2 at frequency resource R3. The base station can receive a CB-Msg3 of terminal #7 at frequency resource R0 of transmission opportunity #1 of a UL resource, receive CB-Msg3s of terminal #1, terminal #3, and terminal #6 respectively at frequency resource R2, and receive CB-Msg3s of terminal #9, terminal #10, and terminal #11 respectively at frequency resource R3. The base station can receive the CB-Msg3 of terminal #9 and terminal #11 respectively from frequency resource R1 of transmission opportunity #2 of the UL resource, can receive the CB-Msg3 of terminal #3 from frequency resource R2, and can receive the CB-Msg3 of terminal #1 from frequency resource R3.

[0148] The base station can determine whether there is a collision regarding the uplink data of CB-Msg3 received at the frequency resource of each of the multiple transmission opportunities (S1610). If no data collision occurs at the frequency resource of each transmission opportunity, the base station can decode the corresponding uplink data (S1620). If a data collision occurs at the frequency resource of each transmission opportunity, the base station can resolve the data collision by performing successive interference cancellation (SIC) (S1630). For example, the base station can perform successive interference cancellation on the uplink data where a collision occurred using the previously decoded uplink data, that is, the decoded data of the uplink data where no collision occurred. The base station can decode the data where the collision has been resolved (S1640).

[0149] For example, the base station can determine that no data collision occurred in frequency resources R0 and R3 of transmission opportunity #0 and can decode the uplink data of terminal #8 and terminal #2, respectively, in those frequency resources. The base station can determine that no data collision occurred in frequency resource R0 of transmission opportunity #1 and can decode the uplink data of terminal #7 in those frequency resources. The base station can determine that no data collision occurred in frequency resources R2 and R3 of transmission opportunity #2 and can decode the uplink data of terminal #3 and terminal #1, respectively, in those frequency resources.

[0150] Additionally, the base station can determine that a data collision has occurred in frequency resource R1 of transmission opportunity #0, determine that a data collision has occurred in frequency resources R2 and R3 of transmission opportunity #1, and determine that a data collision has occurred in frequency resource R1 of transmission opportunity #2. When the decoding of uplink data for which no collision has occurred in each of the total transmission opportunities is completed, the base station can resolve the data collision by performing successive interference cancellation on the collision data in each transmission opportunity.

[0151] For example, the base station can perform continuous interference cancellation on frequency resource R2 of transmission opportunity #1 using the decoded data of terminal #1 and terminal #3 decoded on frequency resources R2 and R3 of transmission opportunity #2. Through continuous interference cancellation, the base station can eliminate interference from terminal #1 and terminal #3 on frequency resource R2 of transmission opportunity #1 to resolve collisions and can decode the uplink data of terminal #6. Additionally, the base station can perform continuous interference cancellation on frequency resource R1 of transmission opportunity #0 using the decoded data of terminal #6 decoded on frequency resource R2 of transmission opportunity #1. Through continuous interference cancellation, the base station can eliminate interference from terminal #6 on frequency resource R1 of transmission opportunity #0 to resolve collisions and can decode the uplink data of terminal #12. Therefore, the base station can additionally decode the uplink data of terminal #6 and terminal #12, respectively, through continuous interference cancellation.

[0152] Referring again to FIG. 4, the base station can transmit a CB-Msg4 to each of at least one terminal based on the decoded uplink data (S470). The base station can set a temporary identifier for the terminal corresponding to the decoded data, for example, a contention-based-early data transmission-radio network temporary identifier (CB-EDT-RNTI). The base station can set a terminal-specific CB-EDT-RNTI using at least one of time resource information, frequency resource information, or index information of an orthogonal cover code. Based on the CB-EDT-RNTI, the base station can scramble the terminal-specific CB-Msg4 and transmit the scrambled CB-Msg4 to at least one terminal. In other words, the base station can apply the CB-EDT-RNTI to each terminal to scramble the physical downlink shared channel (PDSCH) containing the CB-Msg4 of the corresponding terminal. CB-Msg4 may include downlink control signals or downlink data.

[0153] According to an embodiment, CB-Msg4 may be in the form of an RRC Early Data Request message of the existing Early Data Transmission (EDT) method. CB-Msg4 may include information entities such as MAC control elements (e.g., MAC CE) or dedicated NAS information (dedicatedInfoNas). The base station may transmit the RRC Early Data Complete message and the MAC CE to the terminal as a single message, or transmit them to the terminal as separate messages. According to an embodiment, if there is no downlink data in CB-Msg4, the base station may receive a message from the terminal containing a contention resolution identity MAC CE. The terminal may receive a message containing a contention resolution identity MAC CE identical to the contention resolution identity transmitted via CB-Msg3 from the base station, determine that the collision has been resolved based on the received message, and stop monitoring the collision resolution window.

[0154] According to an embodiment, a base station may set an individual CB-EDT-RNTI for each of at least one cloned CB-Msg3 received from a terminal. The base station may receive cloned CB-Msg3 through at least one of different subframe numbers, system frame numbers (SFN), or hyper-system frame numbers (HSFN). The base station may set a CB-EDT-RNTI corresponding to each cloned CB-Msg3 based on the time resource information of the frame in which each cloned CB-Msg3 was received. The base station may scramble a CB-Msg4 for the terminal using the set CB-EDT-RNTI.

[0155] According to an embodiment, the base station may set an individual CB-EDT-RNTI for each of at least one received clone CB-Msg3 and select one of the set individual CB-EDT-RNTIs. For example, the base station may select the CB-EDT-RNTI set from the first clone CB-Msg3. The base station may scramble the CB-Msg4 for the corresponding terminal using the selected CB-EDT-RNTI.

[0156] According to an embodiment, a base station may set a common CB-EDT-RNTI for each of at least one duplicate CB-Msg3 received from a terminal. The base station may scramble a CB-Msg4 for the terminal using the common CB-EDT-RNTI.

[0157] According to an embodiment, the base station may set a subframe-based individual CB-EDT-RNTI for each cloned CB-Msg3 received from the terminal as shown in [Equation 2] below. In [Equation 2] below, the last term may be omitted if an orthogonal cover code is not used.

[0158]

[0159] Here, tid may be the subframe number (or index) of the CB-Msg3 transmitted, fid may be an index representing the frequency offset of the resource used for CB-Msg3 transmission, oid may be an orthogonal cover code index, and oN may be the square of the orthogonal cover code length.

[0160] According to an embodiment, the base station may set a system frame-based individual CB-EDT-RNTI for each cloned CB-Msg3 received from the terminal as shown in [Equation 3] below. In [Equation 3] below, the last term may be omitted if an orthogonal cover code is not used.

[0161]

[0162] Here, tid may be the system frame number (or index) in which CB-Msg3 was transmitted, fid may be an index representing the frequency offset of the resource used for CB-Msg3 transmission, oid may be an orthogonal cover code index, and oN may be the square of the orthogonal cover code length.

[0163] According to an embodiment, the base station may set a hypersystem frame-based individual CB-EDT-RNTI for each cloned CB-Msg3 received from the terminal as shown in [Equation 4] below. In [Equation 4] below, the last term may be omitted if an orthogonal cover code is not used.

[0164]

[0165] Here, tid may be the hypersystem frame number (or index) in which CB-Msg3 was transmitted, fid may be an index representing the frequency offset of the resource used for CB-Msg3 transmission, oid may be an orthogonal cover code index, and oN may be the square of the orthogonal cover code length.

[0166] The operation of the method according to an embodiment of the present disclosure can be implemented as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes all types of recording devices in which information that can be read by a computer system is stored. Additionally, the computer-readable recording medium may be distributed across networked computer systems, and the computer-readable program or code may be stored and executed in a distributed manner.

[0167] In addition, computer-readable recording media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Program instructions may include machine code, such as that generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc.

[0168] Some aspects of the present disclosure have been described in the context of a device, but may also be described according to a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described according to a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, at least one of the most important method steps may be performed by such a device.

[0169] In the embodiments, a programmable logic device (e.g., a field-programmable gate array) may be used to perform some or all of the functions of the methods described herein. In the embodiments, a field-programmable gate array may operate with a microprocessor to perform one of the methods described herein. Generally, it is preferable that the methods be performed by some hardware device.

[0170] Although the present disclosure has been described with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the present disclosure without departing from the spirit and scope of the present disclosure as set forth in the following claims.

Claims

By means of the terminal, A step of receiving uplink (UL) resources and transmission reference information for a random access (RA) procedure from a base station; A step of transmitting a collision-based Msg3 (CB-Msg3, contention-based-Msg3) containing uplink data to the base station through at least one of a plurality of transmission occasions of the UL resource based on the transmission reference information; A step of determining the occurrence of a transmission error for the above CB-Msg3; and Based on the occurrence of a transmission error regarding the above CB-Msg3, the method comprises the step of retransmitting the above CB-Msg3 to the base station based on the transmission reference information. Method of the terminal. In claim 1, The above transmission reference information includes at least one of coverage enhancement (CE) level reference information, channel state reference information, or transmission error count reference information, and The step of transmitting the above CB-Msg3 to the base station is, A step comprising replicating and transmitting the CB-Msg3 through at least one transmission opportunity based on at least one of the transmission reference information or the measurement result of the terminal. Method of the terminal. In claim 2, The measurement result of the above terminal is, including at least one of the signal quality measurement result of the terminal, the path loss measurement result, or the transmission error count measurement result of the CB-Msg3. Method of the terminal. In claim 1, The step of determining the transmission error of the above CB-Msg3 is, A step of monitoring the reception of CB-Msg4 from the base station based on the collision resolution window information of the transmission reference information; and A step comprising determining that a transmission error of the CB-Msg3 has occurred based on the determination that the CB-Msg4 was not received, Method of the terminal. In claim 1, The step of retransmitting the above CB-Msg3 to the base station is, If the number of transmission errors of the CB-Msg3 is greater than or equal to a transmission error threshold, the method comprises the step of retransmitting the CB-Msg3 through at least one additional transmission opportunity based on backoff transmission information of the transmission reference information. Method of the terminal. In claim 1, The step of retransmitting the above CB-Msg3 to the base station is, If the number of transmission errors of the above CB-Msg3 is greater than or equal to a transmission error threshold, the method includes the step of retransmitting the above CB-Msg3 after a backoff time based on backoff transmission information of the above transmission reference information. Method of the terminal. In claim 1, The step of retransmitting the above CB-Msg3 to the base station is, A method comprising the step of retransmitting the CB-Msg3 through at least one of a plurality of transmission opportunities of a new UL resource based on fallback transmission information of the above transmission reference information. Method of the terminal. By the base station method A step of receiving a contention-based Msg3 (CB-Msg3, contention based-Msg3) containing uplink (UL) data from each of a plurality of terminals; A step of determining whether a UL data conflict occurs between the plurality of CB-Msg3s; A step of decoding at least one UL data that has not collided, based on the occurrence of a collision of the UL data between some of the plurality of CB-Msg3s; A step of performing successive interference cancellation (SIC) on the UL data where a collision occurred using the above decoded UL data; and A step comprising decoding UL data in which the collision has been resolved by the above SIC, Base station method. In claim 8, The method further includes the step of transmitting UL resources and transmission reference information for a random access (RA) procedure to each of the plurality of terminals. The step of receiving the above CB-Msg3 is, The step of receiving at least one replicated CB-Msg3 through at least one of a plurality of transmission occasions of the UL resource from each of the plurality of terminals, Base station method. In claim 8, The step of receiving the above CB-Msg3 is, A method comprising the step of receiving at least one CB-Msg3 retransmitted from each of the plurality of terminals based on a transmission error determination result for the CB-Msg3. Base station method. In claim 8, A step of setting each individual collision-based early data transmission-radio network temporary identifier (CB-EDT-RNTI) corresponding to each of the plurality of CB-Msg3s based on the decoded UL data; A step of scrambling a PDSCH (physical downlink shared channel) containing a CB-Msg4 of each of the plurality of terminals based on the plurality of individual CB-EDT-RNTIs; and The method further comprises the step of transmitting the scrambled CB-Msg4 to each of the plurality of terminals. Base station method. In claim 11, The step of scrambling the CB-Msg4 of each of the plurality of terminals is, A step of selecting a first CB-EDT-RNTI corresponding to the first CB-Msg3 among the plurality of individual CB-EDT-RNTIs; and The method further comprises the step of scrambling a PDSCH containing a CB-Msg4 of each of the plurality of terminals based on the first CB-EDT-RNTI. Base station method. In claim 8, A step of setting a common CB-EDT-RNTI corresponding to all of the plurality of CB-Msg3s based on the above decoded UL data; A step of scrambling a PDSCH containing a CB-Msg4 of each of the plurality of terminals based on the above common CB-EDT-RNTI; and The method further comprises the step of transmitting the scrambled CB-Msg4 to each of the plurality of terminals. Base station method. As a terminal, It includes at least one processor, The above at least one processor is, the terminal, Receive uplink (UL) resources and transmission reference information for random access (RA) procedures from a base station, and Based on the above transmission reference information, a collision-based Msg3 (CB-Msg3, contention based-Msg3) including uplink data is transmitted to the base station through at least one of a plurality of transmission occasions of the UL resource, and Determine the occurrence of a transmission error for the above CB-Msg3, and, Based on the occurrence of a transmission error regarding the above CB-Msg3, causing the above CB-Msg3 to be retransmitted to the base station based on the above transmission reference information, Terminal. In claim 14, The above transmission reference information includes at least one of coverage enhancement (CE) level reference information, channel state reference information, or transmission error count reference information, and In order to transmit the above CB-Msg3 to the base station, the at least one processor, the terminal, Causing to duplicate transmit the CB-Msg3 through at least one transmission opportunity based on at least one of the above transmission reference information or the measurement result of the terminal, Terminal. In claim 15, The measurement result of the above terminal is, including at least one of the signal quality measurement result of the terminal, the path loss measurement result, or the transmission error count measurement result of the CB-Msg3. Terminal. In claim 14, To determine the transmission error of the above CB-Msg3, the at least one processor, the terminal, Based on the collision resolution window information of the above transmission reference information, the reception of CB-Msg4 from the base station is monitored, and, Based on the determination that the above CB-Msg4 was not received, causing to determine that a transmission error of the above CB-Msg3 has occurred, Terminal. In claim 14, In order to retransmit the above CB-Msg3 to the base station, the at least one processor, the terminal, When the number of transmission errors of the above CB-Msg3 is greater than or equal to a transmission error threshold, causing the above CB-Msg3 to be retransmitted through at least one additional transmission opportunity based on backoff transmission information of the above transmission reference information, Terminal. In claim 14, In order to retransmit the above CB-Msg3 to the base station, the at least one processor, the terminal, When the number of transmission errors of the above CB-Msg3 is greater than or equal to a transmission error threshold, causing the above CB-Msg3 to be retransmitted after a backoff time based on the backoff transmission information of the above transmission reference information, Terminal. In claim 14, In order to retransmit the above CB-Msg3 to the base station, the at least one processor, the terminal, Causing the CB-Msg3 to be retransmitted through at least one of a plurality of transmission opportunities of a new UL resource based on fallback transmission information of the above transmission reference information, Terminal.

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