Communication device, method, and non-transitory computer-readable storage medium for transmitting data in wireless communication system

Abstract

According to one embodiment, a communication device for providing functions of a packet data convergence protocol (PDCP) entity may comprise: a transceiver; at least one processor including a processing circuit; and memory for storing instructions and including one or more storage media. The instructions, when executed individually or collectively by the at least one processor, may cause the communication device to: obtain first assistance information data (AID) related to a primary path for a split bearer and second AID related to a secondary path for the split bearer; obtain first wireless quality information related to the primary path and second wireless quality information related to the secondary path; identify that the size of data to be transmitted using the split bearer is smaller than a reference size for transmission through a single path; choose the secondary path as the path through which the data is to be transmitted; and transmit the data to a terminal by using the secondary path.

Description

Communication device, method, and non-transient computer-readable storage medium for transmitting data in a wireless communication system

[0001] The present disclosure relates to a communication device, a method, and a non-transient computer-readable storage medium for transmitting data in a wireless communication system.

[0002] In a wireless communication system, a split bearer can be used for dual connectivity. A base station can transmit data to a terminal through the split bearer. The base station can configure multiple paths for the split bearer. The base station can transmit data to the terminal through multiple paths.

[0003] The information described above may be provided as related art for the purpose of aiding understanding of the present disclosure. No claim or determination is made as to whether any of the foregoing may be applied as prior art related to the present disclosure.

[0004] According to one embodiment, a communication device providing functions of a PDCP (packet data convergence protocol) entity may include a transceiver, at least one processor including a processing circuit, and a memory including one or more storage media for storing instructions. The above instructions, when executed individually or collectively by the at least one processor, may cause the communication device to obtain a first AID (assistance information data) regarding a primary path for a split bearer and a second AID regarding a secondary path for the split bearer, obtain first radio quality information regarding the primary path based on the first AID, obtain second radio quality information regarding the secondary path based on the second AID, identify that the size of the data to be transmitted using the split bearer is smaller than a reference size for transmission through a single path, determine the path to transmit the data as the secondary path based on the first radio quality information and the second radio quality information, and transmit the data having a size smaller than the reference size to a terminal using the secondary path.

[0005] According to one embodiment, a method performed by a communication device providing functions of a packet data convergence protocol (PDCP) entity may include: obtaining a first assistance information data (AID) regarding a primary path for a split bearer and a second AID regarding a secondary path for said split bearer; obtaining first radio quality information regarding said primary path based on said first AID; obtaining second radio quality information regarding said secondary path based on said second AID; identifying that the size of data to be transmitted using said split bearer is smaller than a reference size for transmission through a single path; determining the path to transmit said data as said secondary path based on said first radio quality information and said second radio quality information; and transmitting said data having a size smaller than said reference size to a terminal using said secondary path.

[0006] According to one embodiment, a non-transient computer-readable storage medium may store one or more programs. The one or more programs may include instructions that, when executed individually or collectively by at least one processor of a communication device including the transceiver, obtain a first AID (assistance information data) regarding a primary path for a split bearer and a second AID regarding a secondary path for the split bearer, obtain first radio quality information regarding the primary path based on the first AID, obtain second radio quality information regarding the secondary path based on the second AID, identify that the size of data to be transmitted using the split bearer is smaller than a reference size for transmission through a single path, determine the path to transmit the data as the secondary path based on the first radio quality information and the second radio quality information, and cause the communication device to transmit the data having a size smaller than the reference size to a terminal using the secondary path.

[0007] In relation to the description of the drawings, the same or similar reference numerals may be used for identical or similar components.

[0008] Figure 1 illustrates an example of a wireless communication system.

[0009] Figure 2a illustrates an example of a protocol stack in the control plane.

[0010] Figure 2b illustrates an example of a protocol stack in the user plane.

[0011] FIGS. 3A and FIGS. 3B illustrate examples of dual connections in a wireless communication system.

[0012] FIGS. 4a and 4b illustrate examples of a method for transmitting downlink packets to a terminal through a split bearer by a PDCP entity.

[0013] Figure 5 illustrates an example of reordering performed at the PDCP layer.

[0014] Figure 6 illustrates a simplified block diagram of a communication device.

[0015] FIG. 7 illustrates an example in which a PDCP entity transmits data to a terminal through a split bearer.

[0016] FIG. 8 illustrates a flowchart regarding the operation of a PDCP entity for transmitting data to a terminal through a split bearer.

[0017] FIG. 9 illustrates a flowchart regarding the operation of a PDCP entity to determine the path to transmit data.

[0018] FIG. 10a illustrates a flowchart regarding the operation of a PDCP entity for setting the state of a basic path.

[0019] FIG. 10b illustrates a flowchart regarding the operation of a PDCP entity for setting the state of an auxiliary path.

[0020] FIG. 11 illustrates a flowchart regarding the operation of a PDCP entity for setting a path to transmit data.

[0021] FIG. 12 illustrates an example in which a terminal transmits data to a PDCP entity through a split bearer.

[0022] FIG. 13 illustrates a flowchart regarding the operation of a terminal for transmitting data to a PDCP entity through a split bearer.

[0023] The terms used in this disclosure are used merely to describe specific embodiments and are not intended to limit the scope of other embodiments. A singular expression may include a plural expression unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art described in this disclosure. Terms used in this disclosure that are defined in a general dictionary may be interpreted as having the same or similar meaning as they have in the context of the relevant technology, and are not to be interpreted in an ideal or overly formal sense unless explicitly defined in this disclosure. In some cases, even terms defined in this disclosure are not to be interpreted to exclude the embodiments of this disclosure.

[0024] In the various embodiments of the present disclosure described below, a hardware-based approach is described as an example. However, since the various embodiments of the present disclosure include techniques using both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0025] Terms referring to signals used in the following description (e.g., packet, message, signal, information, signaling), terms referring to resources (e.g., section, symbol, slot, subframe, radio frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), occasion)), terms for operation states (e.g., step, operation, procedure)), terms referring to data (e.g., packet, message, user stream, information, bit, symbol, codeword)), terms referring to channels, terms referring to network entities (DU (distributed unit), RU (radio unit), CU (central unit), CU-CP (control plane), CU-UP (user plane), O-DU (O-RAN (open radio access network) DU), O-RU (O-RAN RU), O-CU (O-RAN CU), Terms such as O-CU-UP (O-RAN CU-CP), O-CU-CP (O-RAN CU-CP), and terms referring to components of the device are examples provided for convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. Furthermore, terms such as '...part', '...device', '...object', '...body' used below may refer to at least one shape structure or a unit that processes a function.

[0026] Additionally, in this disclosure, expressions of "greater than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled; however, this is merely for the purpose of expressing an example and does not exclude descriptions of "greater than" or "less than." Conditions described as "greater than" may be replaced with "greater than," conditions described as "less than" may be replaced with "less than," and conditions described as "greater than and less than" may be replaced with "greater than and less than." Furthermore, "A" to "B" below refer to at least one of elements from A (including A) to B (including B). Below, "C" and / or "D" refers to including at least one of "C" or "D," i.e., {"C", "D", "C" and "D"}.

[0027] Figure 1 illustrates a wireless communication system.

[0028] Referring to FIG. 1, FIG. 1 illustrates a base station (110) and a terminal (120) as part of nodes using a wireless channel in a wireless communication system. FIG. 1 illustrates only one base station, but the wireless communication system may include other base stations identical or similar to the base station (110).

[0029] A base station (110) is a network infrastructure that provides wireless access to a terminal (120). The base station (110) has coverage defined based on the distance over which it can transmit signals. In addition to being a base station, the base station (110) may be referred to as an 'access point (AP)', 'eNodeB (eNB)', '5G node (5th generation node)', 'next generation nodeB (gNB)', 'wireless point', 'transmission / reception point (TRP)', or other terms having an equivalent technical meaning.

[0030] A terminal (120) is a device used by a user and communicates with a base station (110) via a wireless channel. The link from the base station (110) to the terminal (120) is referred to as a downlink (DL), and the link from the terminal (120) to the base station (110) is referred to as an uplink (UL). Additionally, although not shown in FIG. 1, the terminal (120) and another terminal can communicate with each other via a wireless channel. In this case, the link between the terminal (120) and another terminal (device-to-device link, D2D) is referred to as a sidelink, and the sidelink may be used interchangeably with the PC5 interface. In some other embodiments, the terminal (120) may be operated without user involvement. According to one embodiment, the terminal (120) is a device that performs machine type communication (MTC) and may not be carried by the user. Additionally, according to one embodiment, the terminal (120) may be a narrowband (NB)-Internet of Things (IoT) device. The terminal (120) may be referred to as 'user equipment (UE)', 'customer premises equipment (CPE)', 'mobile station', 'subscriber station', 'remote terminal', 'wireless terminal', 'electronic device', or 'user device' or other terms having an equivalent technical meaning.

[0031] The base station (110) can perform beamforming with the terminal (120). The base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively low frequency band (e.g., FR 1 (frequency range 1) of NR). Additionally, the base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively high frequency band (e.g., FR 2 (or FR 2-1, FR 2-2, FR 2-3), FR 3) of NR) and a millimeter wave (mmWave) band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz)). To improve channel gain, the base station (110) and the terminal (120) can perform beamforming. Here, beamforming may include transmit beamforming and receive beamforming. The base station (110) and the terminal (120) can impart directivity to the transmitted signal or the received signal. To this end, the base station (110) and the terminal (120) can select serving beams through a beam search or beam management procedure. After the serving beams are selected, subsequent communication can be performed through a resource that has a QCL relationship with the resource that transmitted the serving beams.

[0032] If large-scale characteristics of the channel that transmitted the symbol on the first antenna port can be inferred from the channel that transmitted the symbol on the second antenna port, the first antenna port and the second antenna port can be evaluated as being in a QCL relationship. For example, the large-scale characteristics may include at least one of a delay spread, a Doppler spread, a Doppler shift, an average gain, an average delay, and a spatial receiver parameter.

[0033] In FIG. 1, it is described that both the base station (110) and the terminal (120) perform beamforming, but the embodiments of the present disclosure are not necessarily limited thereto. In some embodiments, the terminal may or may not perform beamforming. Also, the base station may or may not perform beamforming. That is, either the base station or the terminal may perform beamforming, or neither the base station nor the terminal may perform beamforming.

[0034] In the present disclosure, a beam refers to a spatial flow of a signal in a wireless channel, formed by one or more antennas (or antenna elements), and this formation process may be referred to as beamforming. Beamforming may include at least one of analog beamforming or digital beamforming (e.g., precoding). A reference signal transmitted based on beamforming may include, for example, a demodulation-reference signal (DM-RS), a channel state information-reference signal (CSI-RS), a synchronization signal / physical broadcast channel (SS / PBCH), or a sounding reference signal (SRS). Additionally, an IE such as a CSI-RS resource or an SRS-resource may be used as a configuration for each reference signal, and such a configuration may include information associated with the beam. Information associated with a beam may refer to whether the configuration (e.g., CSI-RS resource) uses the same spatial domain filter as other configurations (e.g., other CSI-RS resources within the same CSI-RS resource set) or a different spatial domain filter, or which reference signal it is quasi-colocated with, and if so, what type (e.g., QCL type A, B, C, D).

[0035] Conventionally, in communication systems with a relatively large cell radius of base stations, each base station was installed to include the functions of a digital processing unit (or DU (distributed unit)) and an RF (radio frequency) processing unit (RF processing unit, or RU (radio unit)). However, as high frequency bands are used in 4G (4th generation) and / or subsequent communication systems (e.g., 5G) and the cell coverage of base stations decreases, the number of base stations required to cover a specific area has increased. Consequently, the burden of installation costs for operators to install base stations has also increased. To minimize base station installation costs, a structure has been proposed in which the DU and RU of a base station are separated, with one or more RUs connected to a single DU via a wired network, and one or more geographically distributed RUs deployed to cover a specific area. Below, base station deployment structures and extension examples according to various embodiments of the present disclosure are described with reference to FIGS. 2a and 2b.

[0036] Figure 2a illustrates an example of a protocol stack in the control plane.

[0037] Referring to FIG. 2a, in a communication system, the wireless protocol of the control plane of a terminal (120) may include a PHY (physical) layer (211), a MAC (medium access control) layer (212), an RLC (radio link control) layer (213), a PDCP (packet data convergence protocol) layer (214), and an RRC (radio resource control) layer (215). The wireless protocol of the control plane of a base station (110) may include a PHY layer (221), a MAC layer (222), an RLC layer (223), a PDCP layer (222), and an RRC layer (225).

[0038] The main functions of the RRC layer (215, 225) may include at least one of the following functions.

[0039] - Broadcast system information related to AS (Access Stratum) and NAS (Non Access Stratum)

[0040] - Paging initiated by 5GC or NG-RAN

[0041] - Establish, maintain, and release the RRC connection between the UE and NG-RAN, including the following:

[0042] 1) Adding, modifying, and removing carrier aggregation

[0043] 2) Add, modify, and disable Dual Connectivity within NR or between E-UTRA and NR.

[0044] - Security functions including key management

[0045] - Setup, configuration, maintenance, and release of SRB (Signaling Radio Bearer) and DRB (Data Radio Bearer)

[0046] - Mobility features including the following:

[0047] 1) Handover and context transfer

[0048] 2) UE cell selection and reselection and control of cell selection and reselection

[0049] 3) Inter-RAT mobility

[0050] - QoS (Quality of Service) management function

[0051] - UE measurement reporting and reporting control;

[0052] - Detection of and recovery from radio link failure

[0053] - Send messages from / to / from the UE to / from the NAS.

[0054] The main functions of the PDCP layer (214, 224) may include some of the following functions.

[0055] - Header compression and decompression features (ROHC only)

[0056] - User data transfer function (Transfer of user data)

[0057] - Sequential delivery function (In-sequence delivery of upper layer PDUs)

[0058] - Out-of-sequence delivery of upper layer PDUs

[0059] - Reordering function (PDCP PDU reordering for reception)

[0060] - Duplicate detection function (Duplicate detection of lower layer SDUs)

[0061] - Retransmission of PDCP SDUs

[0062] - Encryption and decryption functions (Ciphering and deciphering)

[0063] - Timer-based SDU discard in uplink.

[0064] In the above description, the reordering function of the PDCP layer (214, 224) may mean a function that reorders PDCP PDUs received from a lower layer in order based on the PDCP SN (sequence number). In one example, the reordering function of the PDCP layer (214, 224) may include a function that transmits data to an upper layer in the reordered order. In one example, the reordering function of the PDCP layer (214, 224) may include a function that transmits data to an upper layer without considering the order. In one example, the reordering function of the PDCP layer (214, 224) may include a function that records lost PDCP PDUs by reordering them. In one example, the reordering function of the PDCP layer (214, 224) may include a function that transmits a status report regarding lost PDCP PDUs to the transmitting side. In one example, the reordering function of the PDCP layer (214, 224) may include a function to request retransmission of lost PDCP PDUs.

[0065] The main functions of the RLC layer (213, 223) may include at least one of the following functions.

[0066] - Data transfer function (Transfer of upper layer PDUs)

[0067] - Sequential delivery function (In-sequence delivery of upper layer PDUs)

[0068] - Out-of-sequence delivery of upper layer PDUs

[0069] - ARQ function (Error Correction through ARQ)

[0070] - Concatenation, segmentation, and reassembly functions of RLC SDUs

[0071] - Re-segmentation function (Re-segmentation of RLC data PDUs)

[0072] - Reordering function (Reordering of RLC data PDUs)

[0073] - Duplicate detection

[0074] - Error detection function (Protocol error detection)

[0075] - RLC SDU discard function

[0076] RLC re-establishment function

[0077] In the above description, the in-sequence delivery function of the RLC layer (213, 223) may mean a function of delivering RLC SDUs received from a lower layer to an upper layer in order. When a single RLC SDU is received divided into multiple RLC SDUs, the in-sequence delivery function of the RLC layer (213, 223) may include a function of reassembling and delivering the multiple RLC SDUs. In one example, the in-sequence delivery function of the RLC layer (213, 223) may include a function of rearranging the received RLC PDUs based on an RLC SN or PDCP SN. In one example, the in-sequence delivery function of the RLC layer (213, 223) may include a function of recording lost RLC PDUs by rearranging the order. In one example, the sequential delivery function of the RLC layer (213, 223) may include a function to deliver a status report for lost RLC PDUs to the transmitting side. In one example, the sequential delivery function of the RLC layer (213, 223) may include a function to request retransmission of lost RLC PDUs. In one example, the sequential delivery function of the RLC layer (213, 223) may include a function to deliver only the RLC SDUs prior to the lost RLC SDU in order to the upper layer if there is a lost RLC SDU. In one example, the sequential delivery function of the RLC layer (213, 223) may include a function to deliver all RLC SDUs received before the timer started to the upper layer in order if a predetermined timer has expired even if there is a lost RLC SDU. In one example, the sequential delivery function of the RLC layer (213, 223) may include the function of delivering all RLC SDUs received up to now to the upper layer in order when a predetermined timer expires, even if there are lost RLC SDUs.

[0078] The RLC layer (213, 223) can process the RLC PDUs in the order they are received, regardless of the order of the SN (out of sequence delivery), and deliver them to the PDCP layer (214, 224).

[0079] When the RLC layer (213, 223) receives a segment, it can receive segments stored in a buffer or subsequent segments, reconstruct them into a single complete RLC PDU, and then transmit it to the PDCP layer (214, 224).

[0080] The RLC layer (213, 223) may or may not include a concatenation function. The concatenation function may be performed in the MAC layer (212, 222) or replaced by the multiplexing function of the MAC layer (212, 222).

[0081] The MAC layer (212, 222) may be connected to one or more RLC layers configured in the terminal (120), and the main function of the MAC layer (212, 222) may include at least one of the following functions.

[0082] - Mapping function (Mapping between logical channels and transport channels)

[0083] - Multiplexing and demultiplexing functions (Multiplexing / demultiplexing of MAC SDUs)

[0084] - Scheduling information reporting function

[0085] - HARQ function (Error correction through HARQ)

[0086] - Priority handling between logical channels of one UE

[0087] - Priority handling between UEs by means of dynamic scheduling

[0088] - MBMS service identification

[0089] - Transport format selection function

[0090] - Padding

[0091] The PHY layer (211, 221) can perform the operation of channel coding and modulating upper layer data, creating OFDM (orthogonal frequency division multiplexing) symbols and transmitting them to the wireless channel, or demodulating OFDM symbols received through the wireless channel and channel decoding them to transmit them to the upper layer.

[0092] Figure 2b illustrates an example of a protocol stack in the user plane.

[0093] Referring to FIG. 2b, the wireless protocol of the user plane of the terminal (120) may include a PHY (physical) layer (261), a MAC (medium access control) layer (262), an RLC (radio link control) layer (263), a PDCP (packet data convergence protocol) layer (264), and an SDAP (service data adaptation protocol) layer (265). The wireless protocol of the control plane of the base station (110) may include a PHY layer (271), a MAC layer (272), an RLC layer (273), a PDCP layer (274), and an SDAP layer (275).

[0094] The main functions of the SDAP layer (265, 276) may include at least one of the following functions.

[0095] - User data transfer function (transfer of user plane data)

[0096] - Mapping function between a QoS flow and a DRB for both DL and UL for uplink and downlink

[0097] - Marking QoS flow ID in both DL and UL packets for uplink and downlink

[0098] - Function to map reflective QoS flow to data bearers for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

[0099] For SDAP layers (265, 275), the terminal (120) may receive a radio resource control (RRC) message indicating whether to use the header of the SDAP layer (265, 275) or the function of the SDAP layer (265, 275) for each PDCP layer, for each bearer, or for each logical channel. If the SDAP header is set, the terminal (120) may be instructed to update or reset the mapping information for the QoS flows of the uplink and downlink and the data bearer using the NAS (non-access stratum) QoS (quality of service) reflective setting 1-bit indicator (NAS reflective QoS) and the AS (access stratum) QoS reflective setting 1-bit indicator (AS reflective QoS) of the SDAP header. The SDAP header may include QoS flow ID (identifier) ​​information indicating QoS. QoS information can be used for data processing priorities, scheduling information, etc., to support smooth service.

[0100] For the PDCP layers (264, 274) in the user plane, the contents of the PDCP layers (214, 224) in the control plane of FIG. 2a can be applied substantially identically. For the RLC layers (263, 273) in the user plane, the contents of the RLC layers (213, 223) in the control plane of FIG. 2a can be applied substantially identically. For the MAC layers (262, 272) in the user plane, the contents of the MAC layers (212, 222) in the control plane of FIG. 2a can be applied substantially identically. For the PHY layers (261, 271) in the user plane, the contents of the PHY layers (211, 221) in the control plane of FIG. 2a can be applied substantially identically.

[0101] Referring to FIGS. 2a and 2b, a radio protocol of a new radio (NR) communication system in a radio access network is described as an example, but the present disclosure is not limited thereto. For example, the description of FIGS. 2a and 2b may be applied to other communication systems (e.g., a long term evolution (LTE) communication system or a 6G (6th generation) communication system).

[0102] In FIG. 2a and FIG. 2b, a protocol stack of a base station (110) is illustrated, but the present disclosure is not limited thereto. For example, the base station (110) may be implemented in a distributed deployment according to a central unit (or control unit) configured to perform the functions of the upper layer (e.g., PDCP, RRC) of the access network and a distributed unit (DU) configured to perform the functions of the lower layer.

[0103] FIGS. 3A and FIGS. 3B illustrate examples of dual connections in a wireless communication system.

[0104] FIG. 3a illustrates an example (300) of dual connectivity (DC) between a terminal (120) and a plurality of base stations (110-1, 110-2). Referring to the example (300), the terminal (120) may be configured in a dual connectivity using a first base station (110-1) and a second base station (110-2). The dual connectivity technology is a technology that increases frequency usage efficiency by simultaneously connecting the terminal (120) to two independent heterogeneous or homogeneous radio communication cell groups having separate radio resource control entities, thereby utilizing frequency resources on the component carriers of cells within each cell group located in different frequency bands for the transmission and reception of signals. For example, a terminal (120) may be connected to two different radio resource entities (e.g., a first base station (110-1) and a second base station (110-2)) and may use radio resources allocated by each radio resource entity. In a multi-radio DC (MR-DC), a terminal (120) in a radio resource control (RRC) connection state (e.g., RRC_CONNECTED) may be configured to use radio resources provided by two independent schedulers. Each scheduler may be located at an NG-RAN node (e.g., a first base station (110-1), a second base station (110-2)). One of the nodes may be a master node (MN) and the other may be a secondary node (SN). The MN and the SN are connected via a network interface, and the MN may be connected to a core network (CN). The SN may be connected to the core network or may not be connected.

[0105] MN may provide a master cell group (MCG). In addition to MN, MN may be referred to as an M-NODE, M-NG-RAN node, or other terms having an equivalent technical meaning. MCG may include one or more cells. MCG may include a primary cell (PCell). MCG may include a plurality of aggregated cells. MCG may include a PCell and one or more secondary cells (SCell). SN may provide a secondary cell group (SCG). In addition to SN, SN may be referred to as an S-NODE, S-NG-RAN node, or other terms having an equivalent technical meaning. SCG may include one or more cells. SCG may include a plurality of aggregated cells. SCG, like MCG, may include a PCell and / or SCell. A cell functioning as a PCell within an SCG may be referred to as a primary secondary cell (PSCell). Hereinafter, the term SpCell (special cell) may be used as a term including PCell and PSCell. For example, SpCell in MCG may represent PCell, and SpCell in SCG may represent PSCell.

[0106] The types of DC can be defined as follows.

[0107] 1) EN-DC (EUTRA (evolved universal terrestrial radio access) NR (new radio) dual connectivity): dual connectivity in which an eNB is connected to an EPC (evolved packet core) and a terminal is connected to an Enb operating as an MN and a gNB operating as an SN (act as). The gNB may be referred to as an en-gNB, and the en-gNB may or may not be connected to an EPC.

[0108] 2) NGEN-DC: A dual connection in which an eNB is connected to a 5GC (5G core), and a terminal is connected to an eNB operating as an MN and a Gnb operating as an SN. Here, the eNB may be referred to as ng-eNB.

[0109] 3) NE-DC: A dual connection in which a gNB is connected to a 5GC, and a terminal is connected to a gNB operating as an MN and an eNB operating as an SN. Here, the eNB may be referred to as ng-eNB.

[0110] 4) NR-DC: A dual connection in which gNBs are connected to the 5GC, and terminals are connected to a gNB operating as an MN and a gNB operating as an SN. NR-DC can also be used when a UE is connected to a single gNB to perform both the roles of MN and SN and to configure both the MCG and SCG.

[0111] The terminal (120) may support MR-DC. The terminal (120) may be connected to a first base station (110-1) and a second base station (110-2). The first base station (110-1) may be connected to the terminal (120) as an MN and the second base station (110-2) as an SN. However, this is merely an example and the present disclosure is not limited thereto. For example, the first base station (110-1) may be connected to the terminal (120) as an SN and the second base station (110-2) as an MN.

[0112] FIG. 3b illustrates an example (350) of a dual connection between a terminal (120), a first DU (371), a second DU (372), and a CU (360). Referring to the example (350), base stations (e.g., base station (110), first base station (110-1), second base station (110-2)) may be separated into CUs and DUs. Unlike multiple independent base stations (e.g., first base station (110-1), second base station (110-2)) serving the terminal (120), one CU and multiple DUs may serve the terminal (120). For example, the CU (360) may be connected to the first DU (371) and the second DU (372). The CU (360) may be connected to each of the first DU (371) and the second DU (372) via an F1 interface. The first DU (371) may provide one or more cells. For example, one or more cells provided by the first DU (371) may be referred to as MCG (or SCG). The second DU (372) may provide one or more cells. For example, one or more cells provided by the second DU (372) may be referred to as SCG (or MCG). In terms of the terminal (120), the CU (360) and the first DU (371) may operate as logical nodes corresponding to one base station. In terms of the terminal (120), the CU (360) and the second DU (372) may operate as logical nodes corresponding to another base station different from the one base station.

[0113] In the present disclosure, base stations (e.g., base station (110), first base station (110-1), second base station (110-2)) may be implemented in a distributed arrangement according to a CU configured to perform upper-layer functions of an access network and a DU configured to perform lower-layer functions. The CU and DU may represent independent network entities (or network nodes, network equipment, network devices) for the access network. A CU may be connected to one or more DUs. A CU may perform functions of a higher layer than a DU (e.g., packet data convergence protocol (PDCP), radio resource control (RRC)). A DU may perform functions of a lower layer (e.g., radio link control (RLC), medium access control (MAC), and physical (PHY)).

[0114] FIGS. 4a and 4b illustrate examples of a method for transmitting downlink packets to a terminal through a split bearer by a PDCP entity.

[0115] FIG. 4a illustrates an example (400) of a base station (410) connected to an evolved packet core (EPC). Referring to the example (400), the base station (410) and the node (420) may be configured to provide dual connectivity (DC) (e.g., EN-DC) to a terminal (540). In the example (400), the base station (410) may be a gNB and the node (420) may be an eNB. However, the present disclosure is not limited thereto. For example, the base station (510) may be implemented as a central unit (CU) (or control unit) or a distributed unit (DU). The base station (410) may be connected to a serving-gateway (S-GW) (430) which is an entity of the EPC. For example, the S-GW (430) may be an entity (or node) that provides packets (or data) to the base station (410) in the user plane.

[0116] For example, a base station (410) may include NR (new radio) PDCP (packet data convergence protocol) (or, PDCP, PDCP layer) (411), NR RLC (radio link control) (or, RLC, RLC layer) (412), and NR MAC (medium access control) (or, MAC, MAC layer) (413). In example (400), the base station (410) is illustrated as including NR PDCP (411), NR RLC (412), and NR MAC (413), but the present disclosure is not limited thereto. For example, the base station (410) may further include at least one of NR RRC (radio resource control), NR SDAP (service data adaptation protocol), or NR PHY (physical). For NR PDCP (411), the contents of the PDCP layers (224, 274) of FIGS. 2a and 2b can be applied substantially identically. For NR RLC (412), the contents of the RLC layers (223, 273) of FIGS. 2a and 2b can be applied substantially identically. For NR MAC (413), the contents of the MAC layers (222, 272) of FIGS. 2a and 2b can be applied substantially identically.

[0117] For example, a node (420) may include an EUTRA (evolved universal terrestrial radio access) RLC (or, RLC, RLC layer) (422) and an EUTRA MAC (or, MAC, MAC layer) (423). In example (400), the node (420) is depicted as including an EUTRA RLC (422) and an EUTRA MAC (423), but the present disclosure is not limited thereto. For example, the node (420) may further include at least one of an EUTRA RRC, an EUTRA SDAP, an EUTRA PDCP, or an EUTRA PHY. For the EUTRA RLC (422), the contents regarding the RLC layer (223, 273) of FIG. 2B may be substantially applicable. For the EUTRA MAC (423), the contents regarding the MAC layer (222, 272) of FIG. 2B may be substantially applicable.

[0118] Referring to Example (400), to support a split bearer, the NR PDCP (411) of the base station (410) may be connected to the NR RLC (412) of the base station (410) and the EUTRA RLC (422) of the node (420). The base station (410) may perform packet distribution for the split bearer using the downlink data delivery status (DDDS) obtained from each of the NR RLC (412) and the EUTRA RLC (422). In one example, the DDDS may be referred to as PDU type 1. For example, the NR PDCP (411) of the base station (410) may obtain a first DDDS from the corresponding node, the NR RLC (412), via an uplink path (402). For example, the NR PDCP (411) of the base station (410) may obtain a second DDDS via the uplink path (402) from the corresponding node, the EUTRA RLC (422). For example, the DDDS may include a desired buffer size (DBS). For example, the DBS may indicate a buffer size for the data radio bearer (DRB). For example, the DBS may be used to identify the number of packets according to the buffer size in the NR PDCP (411). For example, the base station (410) (or the NR PDCP (411)) may perform distribution of downlink packets received from the S-GW (430) based on the first DBS of the first DDDS obtained from the NR RLC (412) and the second DBS of the second DDDS obtained from the EUTRA RLC (422).

[0119] The downlink path (401) may include paths for split bearers. For example, the paths for split bearers may include a first path (401-1) and a second path (401-2). The first path (401-1) may include an NR PDCP (411) of a base station (410), an NR RLC (412) of a base station (410), an NR MAC (413) of a base station (410), an NR MAC (441) of a terminal (440), an NR RLC (442) of a terminal (440), and an NR PDCP (445) of a terminal (440). The second path (401-2) may include the NR PDCP (411) of the base station (410), the EUTRA RLC (422) of the node (420), the EUTRA MAC (423) of the node (420), the EUTRA MAC (443) of the terminal (440), the EUTRA RLC (444) of the terminal (440), and the NR PDCP (445) of the terminal (440).

[0120] For example, the first path (401-1) may be associated with a cell group provided by the base station (410). For example, if the base station (410) is composed of a CU and a DU, the first path (401-1) may be associated with a cell group provided by the DU. For example, the cell group associated with the first path (401-1) may include a secondary cell group (SCG). For example, the second path (401-2) may be associated with a cell group provided by the node (420). For example, the cell group associated with the second path (401-2) may include a master cell group (MCG).

[0121] For example, the base station (410) (or, NR PDCP (411)) may provide downlink packets to the NR RLC (412) and EUTRA RLC (422) via a split bearer. The downlink packets provided from the NR PDCP (411) to the NR RLC (412) (or, EUTRA RLC (422)) may include a PDCP protocol data unit (PDU). The header of the PDCP PDU may include a PDCP sequence number (SN). The terminal (440) (or, NR PDCP (445)) may reorder downlink packets obtained via paths (401-1, 401-2) to the split bearer. For example, the terminal (440) (or NR PDCP (445)) can sort the order of downlink packets using the PDCP SN included in the acquired downlink packet.

[0122] In FIG. 4a, an example (400) of the user plane of a base station (410), a node (420), and a terminal (440) is illustrated, but the present disclosure is not limited thereto. For example, the base station (410), the node (420), and the terminal (440) may establish a connection in the control plane for dual connection. For example, the upper layer of the node (420) (e.g., RRC) may be connected to an entity of the EPC.

[0123] FIG. 4b illustrates an example (450) of a base station (460) connected to a 5th generation core (5GC). Referring to the example (450), the base station (460) and the node (470) may be configured to provide dual connectivity to a terminal (490). In the example (450), the base station (460) may be a gNB and the node (470) may be a gNB. However, the present disclosure is not limited thereto. For example, the base station (460) and / or the node (470) may be implemented as a CU and a DU. The base station (460) may be connected to a user plane function (UPF) (480) which is an entity of the 5GC. For example, the UPF (480) may be an entity (or node) that provides packets (or data) to the base station (460) in the user plane.

[0124] For example, the base station (460) may include NR PDCP (or, PDCP, PDCP layer) (461), NR RLC (or, RLC, RLC layer) (462), and NR MAC (or, MAC, MAC layer) (463). In example (450), the base station (460) is depicted as including NR PDCP (461), NR RLC (462), and NR MAC (463), but the present disclosure is not limited thereto. For example, the base station (460) may further include at least one of NR RRC, NR SDAP, or NR PHY. With respect to the NR PDCP (461), the contents of the PDCP layer (224, 274) of FIG. 2a and FIG. 2b may be applied substantially the same way. For NR RLC (462), the content of the RLC layers (223, 273) of FIG. 2a and FIG. 2b can be applied substantially the same way. For NR MAC (463), the content of the MAC layers (222, 272) of FIG. 2a and FIG. 2b can be applied substantially the same way.

[0125] For example, a node (470) may include an NR RLC (or, RLC, RLC layer) (472) and an NR MAC (or, MAC, MAC layer) (473). In example (450), the node (470) is depicted as including an NR RLC (472) and an NR MAC (473), but the present disclosure is not limited thereto. For example, the node (470) may further include at least one of an NR RRC, an NR SDAP, an NR PDCP, or an NR PHY. For the NR RLC (472), the details regarding the RLC layers (223, 273) of FIG. 2a and FIG. 2b may be substantially applicable. For the NR MAC (473), the details regarding the MAC layers (222, 272) of FIG. 2a and FIG. 2b may be substantially applicable.

[0126] Referring to example (450), to support a split bearer, the NR PDCP (461) of the base station (460) may be connected to the NR RLC (462) of the base station (460) and the NR RLC (472) of the node (470). The base station (460) may perform packet distribution for the split bearer using the DDDS obtained from each of the NR RLC (462) and the NR RLC (472). In one example, the DDDS may be referred to as PDU type 1. For example, the NR PDCP (461) of the base station (460) may obtain a first DDDS from the corresponding node, the NR RLC (462), via an uplink path (452). For example, the NR PDCP (461) of the base station (460) can obtain a second DDDS from the corresponding node, the NR RLC (472), via the uplink path (452). For example, the DDDS may include a DBS. For example, the DBS may indicate a buffer size for the DRB. For example, the DBS may be used to identify the number of packets according to the buffer size in the NR PDCP (461). For example, the base station (460) (or the NR PDCP (461)) may perform distribution for downlink packets received from the UPF (480) based on the first DBS of the first DDDS obtained from the NR RLC (462) and the second DBS of the second DDDS obtained from the NR RLC (472).

[0127] The downlink path (451) may include paths for a split bearer. For example, the paths for a split bearer may include a first path (451-1) and a second path (451-2). The first path (451-1) may include an NR PDCP (461) of a base station (460), an NR RLC (462) of a base station (460), an NR MAC (463) of a base station (460), an NR MAC (491) of a terminal (490), an NR RLC (492) of a terminal (490), and an NR PDCP (495) of a terminal (490). The second path (451-2) may include the NR PDCP (461) of the base station (460), the EUTRA RLC (472) of the node (470), the EUTRA MAC (473) of the node (470), the EUTRA MAC (493) of the terminal (490), the EUTRA RLC (494) of the terminal (490), and the NR PDCP (495) of the terminal (490).

[0128] For example, the first path (451-1) may be associated with a cell group provided by the base station (460). For example, if the base station (460) is composed of a CU and a DU, the first path (451-1) may be associated with a cell group provided by the DU. For example, the cell group associated with the first path (451-1) may include an SCG (or, MCG). For example, the second path (451-2) may be associated with a cell group provided by the node (470). For example, the cell group associated with the second path (451-2) may include an MCG (or, SCG).

[0129] For example, a base station (460) (or, NR PDCP (461)) may provide downlink packets to NR RLC (462) and NR RLC (472) via a split bearer. The downlink packets provided from NR PDCP (461) to NR RLC (462) (or, NR RLC (472)) may include a PDCP PDU. The header of the PDCP PDU may include a PDCP SN. A terminal (490) (or, NR PDCP (495)) may rearrange downlink packets obtained via paths (451-1, 451-2) to the split bearer. For example, a terminal (490) (or, NR PDCP (445)) may rearrange the order of downlink packets using the PDCP SN included in the obtained downlink packets.

[0130] In FIG. 4b, an example (450) of the user plane of the base station (460), node (470), and terminal (490) is illustrated, but the present disclosure is not limited thereto. For example, the base station (460), node (470), and terminal (490) may establish a connection in the control plane for dual connection. For example, the upper layer of the node (470) (e.g., RRC) may be connected to an entity of 5GC.

[0131] FIG. 5 illustrates an example of reordering performed at the PDCP layer. The PDCP (packet data convergence protocol) layer can provide a reordering function to ensure the packet order of uplink packets in the NR (new radio) standard. In referring to data at the PDCP layer, the terms SDU (service data unit) or PDU (protocol data unit) may be used. For example, data containing a PDCP header may be referred to as a PDU. For example, data not containing a PDCP header may be referred to as an SDU. Hereinafter, as a term to distinguish between data packets and control packets, a PDCP PDU may be a PDCP data PDU or a PDCP control PDU. In the present disclosure, unless otherwise specified, PDU and PDCP PDU may refer to a PDCP data PDU.

[0132] Referring to FIG. 5, communication can be performed between a transmitting PDCP entity (510) and a receiving PDCP entity (560). The transmitting PDCP entity (510) and the receiving PDCP entity (560) can be distinguished according to the entity transmitting the data and the entity receiving the data. For example, in downlink data transmission, the transmitting PDCP entity (510) corresponds to a base station (110) (e.g., a central unit (CU) (360) in FIG. 3b), and the receiving PDCP entity (560) corresponds to a terminal (120). For example, in uplink data transmission, the transmitting PDCP entity (510) corresponds to a terminal (120), and the receiving PDCP entity (560) corresponds to a base station (110) (e.g., a central unit (360) in FIG. 3b).

[0133] The transmitting PDCP entity (510) can obtain data (e.g., PDCP SDU) from an upper layer (e.g., SDAP (service data adaptation protocol) layer, RRC (radio resource control) layer). The transmitting PDCP entity (510) can perform sequence numbering (515). The transmitting PDCP entity (510) can determine a count value for the data through sequence numbering (515). For example, the transmitting PDCP entity (510) can determine a count value corresponding to the state variable 'TX_NEXT'. The transmitting PDCP entity (510) can associate the count value with the data. The transmitting PDCP entity (510) can determine a sequence number (SN) for the data. For example, the transmitting PDCP entity (510) can determine the SN of the PDCP PDU based on the state variable 'TX_NEXT' and a modulo operation. The SN may be an integer greater than or equal to 0 and less than [2[PDCP_size] - 1]. 'PDCP_size' may be configured by an upper layer (e.g., RRC). 'PDCP_size' may be 12-bit or 18-bit. For example, if the PDCP PDU is uplink data, the 'PDCP_size' for the uplink may be configured by an upper layer (e.g., RRC). For example, if the PDCP PDU is downlink data, the 'PDCP_size' for the downlink may be configured by an upper layer (e.g., RRC). Afterward, the transmitting PDCP entity (510) may increase the state variable 'TX_NEXT' by 1. That is, the status variable 'TX_NEXT' can be the count value of the next PDCP SDU to be transmitted.

[0134] Although not illustrated in FIG. 5, the transmitting PDCP entity (510) can perform various functions in addition to sequence numbering (515). For example, the transmitting PDCP entity (510) can perform header compression on the data using ROHC (robust header compression). For example, the transmitting PDCP entity (510) can perform integrity protection and ciphering. For example, the transmitting PDCP entity (510) can generate a PDCP PDU by adding a PDCP header to the data. The transmitting PDCP entity (510) can transmit the result of the functions performed (e.g., PDCP PDU) to the receiving PDCP entity (560). For example, the above results may be provided to other nodes (e.g., terminal (120) in the downlink, base station (110) in the uplink, CU (360)) via RLC entities, MAC entities, and wireless interfaces.

[0135] A receiving PDCP entity (560) can receive data (e.g., PDCP PDU) from a lower layer (e.g., RLC layer). Variables may be defined to describe the operations of the receiving PDCP entity (560).

[0136] - HFN (hyper frame number): The HFN portion of the state variable (i.e., the number of MSBs (most significant bits) equal to the HFN length)

[0137] - SN (sequence number): The SN portion of the state variable (i.e., the number of LSB (least significant bits) equal to the PDCP SN length)

[0138] - RCVD_SN: The PDCP SN of the received PDCP data PDU included in the PDU header

[0139] - RCVD_HFN: HFN of the received PDCP data PDU calculated by the receiving PDCP entity (560)

[0140] - RCVD_COUNT: COUNT of received PDCP data PDU = [RCVD_HFN, RCVD_SN].

[0141] A receiving PDCP entity (560) may receive a PDCP PDU from a lower layer (e.g., RLC). The PDCP PDU may be data transmitted from a transmitting PDCP entity (510). The receiving PDCP entity (560) may determine a count value (e.g., 'RCVD_COUNT') of the received PDCP PDU. After determining the count value (e.g., 'RCVD_COUNT') of the received PDCP PDU, the receiving PDCP entity (560) may perform deciphering and integrity verification. If the integrity verification fails, the receiving PDCP entity (560) may discard the PDCP PDU. The receiving PDCP entity (560) may discard the PDCP PDU if it has previously received a PDCP PDU corresponding to the count value, or if the count value is smaller than the count value ('RX_DELIV') (hereinafter, waiting start count value) of the first PDCP SDU that is still waiting and has not been passed to an upper layer (e.g., SDAP, RRC).

[0142] The receiving PDCP entity (560) can perform a sequential delivery function and a reordering procedure (565) for said sequential delivery function. The receiving PDCP entity (560) can store a PDCP SDU corresponding to the PDCP PDU in a receiving buffer if the PDCP PDU is not deleted by the procedures described above. The receiving PDCP entity (560) can determine whether the count value of the received PDCP PDU (e.g., 'RCVD_COUNT') is greater than or equal to the count value (RX_NEXT) of the PDCP SDU expected to be received (hereinafter, expected count value). If the count value of the received PDCP PDU (e.g., 'RCVD_COUNT') is greater than or equal to the expected count value (RX_NEXT), the receiving PDCP entity (560) may update the expected count value to the value of the received PDCP PDU (e.g., 'RCVD_COUNT') plus 1. This is because the receiving PDCP entity (560) expects the reception of PDCP SDUs having consecutive count values. The receiving PDCP entity (560) may determine whether the count value of the received PDCP PDU (e.g., 'RCVD_COUNT') is equal to the starting count value ('RX_DELIV'). The receiving PDCP entity (560) can forward all stored PDCP SDUs corresponding to consecutive count values ​​starting from the starting count value ('RX_DELIV') to the upper layer (e.g., SDAP, RRC) if the count value (e.g., 'RCVD_COUNT') of the received PDCP PDU is equal to the starting count value ('RX_DELIV'). The starting count value ('RX_DELIV') can be updated to the count value of the first PDCP SDU that is greater than the current starting count value ('RX_DELIV') and has not been forwarded to the upper layer (e.g., SDAP, RRC).

[0143] The receiving PDCP entity (560) may stop and reset the reorder timer if the reorder timer is running and the start count value is greater than or equal to the count value ('RX_REORD') (hereinafter referred to as the reorder start value) following the count value associated with the PDCP PDU that triggered the reorder timer. The receiving PDCP entity (560) may update the reorder start value ('RX_REORD') to the expected count value (RX_NEXT) if the reorder timer is not running and the start count value ('RX_DELIV') is less than the expected count value (RX_NEXT). If the start count value ('RX_DELIV') is less than the expected count value (RX_NEXT), the receiving PDCP entity (560) may start the reorder timer. Even though there is data that has not yet been transmitted to the upper layer (e.g., SDAP), since the expected count value points to the PDCP SDU following the data, the receiving PDCP entity (560) can start the reorder timer as a reorder procedure (465).

[0144] When the reorder timer expires, the receiving PDCP entity (560) may forward all stored PDCP SDUs associated with count values ​​smaller than the reorder start value ('RX_REORD') to the upper layer (e.g., SDAP, RRC). Even if the intended data (e.g., PDCP SDU) has not been received because the reorder timer has expired, the PDCP SDUs currently stored in the receiving buffer may be reported to the upper layer. When the reorder timer expires, the receiving PDCP entity (560) may forward all stored PDCP SDUs having consecutive count values ​​starting from the reorder start value ('RX_REORD') to the upper layer (e.g., SDAP, RRC). The start count value ('RX_DELIV') may be updated to the count value of the first PDCP SDU that is larger than the reorder start value ('RX_REORD') and has not been forwarded to the upper layer (e.g., SDAP, RRC). The receiving PDCP entity (560) can update the reorder start value ('RX_REORD') to the expected count value (RX_NEXT) if the start count value ('RX_DELIV') is less than the expected count value (RX_NEXT). If the start count value ('RX_DELIV') is less than the expected count value (RX_NEXT), the receiving PDCP entity (560) can start a reorder timer. Even though there is data that has not yet been delivered to the upper layer (e.g., SDAP, RRC), the expected count value points to the PDCP SDU following the data, so the receiving PDCP entity (560) can start the reorder timer as a reorder procedure (565).

[0145] When the reorder timer is reconfigured, the receiving PDCP entity (560) can update the reorder start value ('RX_REORD') to the expected count value (RX_NEXT). When the reorder timer is reconfigured, the receiving PDCP entity (560) can stop and restart the reorder timer.

[0146] The transmitting PDCP entity (510) can sequentially transmit data with count values ​​of 2, 3, 4, ..., 9. The receiving PDCP entity (560) can receive a PDCP PDU with a count value of '2'. The receiving PDCP entity (560) can obtain a PDCP SDU from the above PDCP PDU. The receiving PDCP entity (560) can forward the above PDCP SDU with a count value of '2' to an upper layer (e.g., SDAP, RRC). Subsequently, the receiving PDCP entity (560) can expect a PDCP PDU with a count value of '3'. The receiving PDCP entity (560) can receive a PDCP PDU with a count value of '3'. The receiving PDCP entity (560) can obtain a PDCP SDU from the above PDCP PDU. The receiving PDCP entity (560) can forward the PDCP SDU with a count value of '3' to an upper layer (e.g., SDAP, RRC). Subsequently, the receiving PDCP entity (560) can expect a PDCP PDU with a count value of '4'. The receiving PDCP entity (560) can receive a PDCP PDU with a count value of '4'. The receiving PDCP entity (560) can obtain a PDCP SDU from the PDCP PDU. The receiving PDCP entity (560) can forward the PDCP SDU with a count value of '4' to an upper layer (e.g., SDAP, RRC). Subsequently, the receiving PDCP entity (560) can set the starting count value ('RX_DELIV') to '5'. The receiving PDCP entity (560) can expect a PDCP PDU with a count value of '5'.

[0147] In Example (571), a situation is described where a PDCP PDU with a count value of '5' is lost. A receiving PDCP entity (560) may receive a PDCP PDU with a count value of '6' while expecting a PDCP PDU with a count value of '5'. Since a PDCP PDU with a count value of '6' has been received but the starting count value ('RX_DELIV') is '5', the receiving PDCP entity (560) may not perform data transfer to an upper layer (e.g., SDAP, RRC). This is because a PDCP SDU with a count value of '5' has not yet been received. The receiving PDCP entity (560) may store the PDCP SDU corresponding to the PDCP PDU with a count value of '6' in the receiving buffer (581). The receiving PDCP entity (560) may start a reordering timer. Since a PDCP PDU with a count value of '6' has been received, the receiving PDCP entity (560) can expect a PDCP PDU with a count value of '7'. For example, the receiving PDCP entity (560) can set the expected count value (RX_NEXT) to '7'. The receiving PDCP entity (560) can update the reorder start value ('RX_REORD') to the expected count value (RX_NEXT) (e.g., '7').

[0148] The receiving PDCP entity (560) may receive a PDCP PDU with a count value of '7' while expecting a PDCP PDU with a count value of '7'. Since the PDCP PDU with a count value of '7' has been received but the starting count value ('RX_DELIV') is '5', the receiving PDCP entity (560) may not perform data transfer to the upper layer (e.g., SDAP, RRC). This is because a PDCP SDU with a count value of '5' has not yet been received. The receiving PDCP entity (560) may store the PDCP SDU corresponding to the PDCP PDU with a count value of '7' in the receiving buffer (581). The reordering timer may be running. Since a PDCP PDU with a count value of '7' has been received, the receiving PDCP entity (560) may expect a PDCP PDU with a count value of '8'.

[0149] The receiving PDCP entity (560) may receive a PDCP PDU with a count value of '8' while expecting a PDCP PDU with a count value of '8'. Since the PDCP PDU with a count value of '8' has been received but the starting count value ('RX_DELIV') is '5', the receiving PDCP entity (560) may not perform data transfer to the upper layer (e.g., SDAP, RRC). This is because a PDCP SDU with a count value of '5' has not yet been received. The receiving PDCP entity (560) may store the PDCP SDU corresponding to the PDCP PDU with a count value of '8' in the receiving buffer (581). Afterward, the reorder timer may expire. When the above reorder timer expires, the receiving PDCP entity (560) may forward the stored PDCP SDU having a count value smaller than the reorder start value ('RX_REORD') (e.g., 7) (e.g., a PDCP SDU with a count value of 6) and the stored PDCP SDU having consecutive count values ​​greater than or equal to the reorder start value ('RX_REORD') '7' (e.g., a PDCP SDU with a count value of '7', a PDCP SDU with a count value of '8') to the upper layer (e.g., SDAP, RRC).

[0150] In Example (572), a situation is described where a PDCP PDU with a count value of '5' is received late. As in Example (571), the receiving PDCP entity (560) may receive a PDCP PDU with a count value of '6' while expecting a PDCP PDU with a count value of '5'. Since the PDCP PDU with a count value of '6' has been received but the starting count value ('RX_DELIV') is '5', the receiving PDCP entity (560) may not perform data transfer to the upper layer (e.g., SDAP, RRC). This is because the PDCP SDU with a count value of '5' has not yet been received. The receiving PDCP entity (560) may store the PDCP SDU corresponding to the PDCP PDU with a count value of '6' in the receiving buffer (582). The receiving PDCP entity (560) may start a reordering timer. Since a PDCP PDU with a count value of '6' has been received, the receiving PDCP entity (560) can expect a PDCP PDU with a count value of '7'. For example, the receiving PDCP entity (560) can set the expected count value (RX_NEXT) to '7'. The receiving PDCP entity (560) can update the reorder start value ('RX_REORD') to the expected count value (RX_NEXT) (e.g., '7').

[0151] The receiving PDCP entity (560) may receive a PDCP PDU with a count value of '7' while expecting a PDCP PDU with a count value of '7'. Since the PDCP PDU with a count value of '7' has been received but the starting count value ('RX_DELIV') is '5', the receiving PDCP entity (560) may not perform data transfer to the upper layer (e.g., SDAP, RRC). This is because a PDCP SDU with a count value of '5' has not yet been received. The receiving PDCP entity (560) may store the PDCP SDU corresponding to the PDCP PDU with a count value of '7' in the receiving buffer (582). The reordering timer may be running. Since a PDCP PDU with a count value of '7' has been received, the receiving PDCP entity (560) may expect a PDCP PDU with a count value of '8'.

[0152] The receiving PDCP entity (560) may receive a PDCP PDU with a count value of '5' while expecting a PDCP PDU with a count value of '8'. The receiving PDCP entity (560) may receive a PDCP PDU corresponding to the start count value ('RX_DELIV') before the reordering timer expires. Since the start count value ('RX_DELIV') is '5', the receiving PDCP entity (560) may perform data transfer to an upper layer (e.g., SDAP, RRC). The receiving PDCP entity (560) may store a PDCP SDU corresponding to the PDCP PDU with a count value of '5' in the receiving buffer (582). The receiving buffer (582) may store a PDCP SDU associated with a count value of '6', a PDCP SDU associated with a count value of '7', and a PDCP SDU associated with a count value of '5'. The receiving PDCP entity (560) can forward the stored PDCP SDUs to the upper layer (e.g., SDAP, RRC) in ascending order starting from '5'. Meanwhile, a PDCP PDU with a count value of '5' is received, but since the expected count value (RX_NEXT) is '8', the expected count value (RX_NEXT) is not updated.

[0153] The PDCP layer of the NR specification may provide a reordering function (e.g., reordering procedure (565)) that guarantees the packet order for uplink packets. The reordering function may be performed by a receiving PDCP entity (560). When the reordering timer expires or the intended PDCP PDU is received, the receiving PDCP entity (560) may correct the packet order by sorting the PDCP SDUs in ascending order of count values ​​(values ​​corresponding to SN) and delivering the sorted PDCP SDUs to the upper layer (e.g., SDAP, RRC). Referring to the usual procedures, if the PDCP SDU of a specific SN is not received while the reordering timer is operating, the receiving PDCP entity (560) may wait without delivering the PDCP SDU(s) to the upper layer until the reordering timer expires. Afterwards, when the reorder timer expires, the PDCP SDU(s) stored in the receive buffer of the receiving PDCP entity (560) can be transferred to the upper layer (e.g., SDAP, RRC).

[0154] FIG. 6 illustrates a simplified block diagram of a communication device. The communication device (610) may be configured to provide functions of a PDCP (packet data convergence protocol) layer (e.g., PDCP layer (411) in FIG. 4a, PDCP layer (461) in FIG. 4b). For example, the communication device (610) may correspond to a base station (110). In another example, the communication device (610) may correspond to an upper network node in a distributed deployment. In one example, the communication device (610) may be a CU (central unit) (or CU (control unit)) (360). In one example, the communication device (610) may correspond to a node for performing a reordering procedure in the user plane.

[0155] Referring to FIG. 6, the communication device (610) may include a processor (611), a memory (612), and a transceiver (613).

[0156] The processor (611) can control the overall operations of the communication device (610). The processor (611) may be referred to as a control unit. For example, the processor (611) can transmit and receive signals through the transceiver (613) (or through the backhaul communication unit). Additionally, the processor (611) can write and read data to and from memory (612). The processor (611) can perform functions of the protocol stack required by the communication standard (e.g., functions according to the protocol layer of FIG. 2a, FIG. 2b, FIG. 4a, and FIG. 4b, functions of the PDCP layer). Although only the processor (611) is shown in FIG. 6, according to other implementation examples, the communication device (610) may include two or more processors.

[0157] Memory (612) can store data such as basic programs, application programs, and configuration information for the operation of the communication device (610). Memory (612) may be referred to as a storage unit. Memory (612) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. Memory (612) may provide stored data upon request from the processor (611). Memory (612) may represent a storage space as a functional component. For example, memory (612) may be understood as representing a memory (e.g., hard disk, flash memory, RAM) placed as a component within the communication device (610), as well as a space for storing instructions and / or programs.

[0158] The transceiver (613) can perform functions for transmitting and receiving signals in a wired communication environment. The transceiver (613) may include a wired interface for controlling a direct connection between devices through a transmission medium (e.g., copper wire, optical fiber). For example, the transceiver (613) can transmit an electrical signal to another device through a copper wire or perform conversion between an electrical signal and an optical signal. According to one embodiment, the communication device (610) can communicate with a DU (distributed unit) (e.g., a first DU (371), a second DU (372)) through the transceiver (613). The transceiver (613) may also perform functions for transmitting and receiving signals in a wireless communication environment. For example, the transceiver (613) can perform conversion between a baseband signal and a bit sequence according to the physical layer specifications of the system. For example, when transmitting data, the transceiver (613) can generate complex symbols by encoding and modulating the transmitted bit sequence. Also, when receiving data, the transceiver (613) can restore the received bit sequence by demodulating and decoding the baseband signal. Additionally, the transceiver (613) may include multipath. According to one embodiment, the communication device (610) may be a base station (110) and may communicate with the terminal (120) directly through a wireless access network or through a radio unit (RU).

[0159] The transceiver (613) transmits and receives signals as described above. Accordingly, all or part of the transceiver (613) may be referred to as a 'communication unit', 'transmitter', 'receiver', or 'transmitter / receiver'. Furthermore, in the following description, transmission and reception performed via a wireless channel are used to mean that processing as described above is performed by the transceiver (613). Although only the transceiver (613) is shown in FIG. 6, according to other embodiments, the communication device (610) may include two or more transceivers.

[0160] The configuration of the communication device (610) shown in FIG. 6 is merely an example, and examples of components of the communication device for performing embodiments of the present disclosure are not limited to the configuration shown in FIG. 6. In some embodiments, some components may be added, deleted, or changed.

[0161] FIG. 7 illustrates an example in which a PDCP entity transmits data to a terminal through a split bearer.

[0162] Referring to FIG. 7, the communication device (610) of FIG. 6 described above may be configured to provide functions of the packet data convergence protocol (PDCP) layer. For example, the communication device (610) may correspond to a node hosting a PDCP entity (701). The PDCP entity (701) of the communication device (610) may be connected to a first RLC entity (702) and a second RLC entity (703) based on dual connectivity (DC). According to an embodiment, the communication device (610) may include the first RLC entity (702), and the other communication device may include the second RLC entity (703). However, this is merely an example and the present disclosure is not limited thereto. For example, a communication device (610) may include a second RLC entity (702), and another communication device may include a first RLC entity (702). In another example, both the first RLC entity (701) and the second RLC entity (702) may be configured within the communication device (610). In yet another example, the communication device (610) may be connected to a first DU (distributed unit) (e.g., the first DU (371) in FIG. 3b) containing the first RLC entity (701) and a second DU (e.g., the second DU (372) in FIG. 3b) containing the second RLC entity (702).

[0163] According to one embodiment, the communication device (610) may provide functions of the PDCP entity (701). Hereinafter, for convenience of explanation, the functions of the PDCP entity (701) provided through the communication device (610) will be described as being performed by the PDCP entity (701).

[0164] According to one embodiment, the PDCP entity (701) can perform the distribution of data (or packets) to be transmitted to the terminal (120) to the first RLC entity (702) of the master cell group (MCG) and the second RLC entity (703) of the secondary cell group (SCG) when split-barrier is configured. For example, the PDCP entity (701) can perform the distribution of data to be transmitted to transmit data (or packets) to the terminal (120) using multi-path.

[0165] According to one embodiment, the multiple paths may include a primary path and a secondary path. A PDCP entity (701) may transmit data (or packets) to a terminal (120) using at least one of path (710) and path (720). One of path (710) and path (720) may be set as the primary path. The other of path (710) and path (720) may be set as the secondary path. The primary path may be configured by RRC. The secondary path may be configured by RRC.

[0166] Below, an example will be described in which path (710) is set as an auxiliary path and path (720) is set as a primary path. However, it is not limited thereto. This is for the convenience of explanation, and path (710) may be set as a primary path and path (720) may be set as an auxiliary path.

[0167] According to one embodiment, the PDCP entity (701) can identify the size of the data to be transmitted to the terminal (120). The PDCP entity (701) can identify whether the size of the data to be transmitted to the terminal (120) is smaller than a reference size for transmission through a single path.

[0168] For example, if the size of the data to be transmitted to the terminal (120) is smaller than the reference size for transmission through a single path, the PDCP entity (701) can transmit the data to the terminal (120) through the path (720) set as the default path. For example, if the size of the data to be transmitted to the terminal (120) is smaller than the reference size, the PDCP entity (701) can submit the PDCP PDU to the second RLC entity (703) for the path (720) set as the default path.

[0169] For example, if the size of the data to be transmitted to the terminal (120) is greater than or equal to the reference size, the PDCP entity (701) can transmit the data to the terminal (120) through both the path (720) set as the primary path and the path (710) set as the secondary path. As an example, if the size of the data to be transmitted to the terminal (120) is greater than or equal to the reference size, the PDCP entity (701) can submit the PDCP PDU to the first RLC entity (702) and the second RLC entity (703).

[0170] According to the above-described embodiment, when TCP (transmission control protocol) traffic is first initiated and throughput is low, the PDCP entity (701) can transmit data to the terminal (120) using only the primary path so that PDCP reordering operations at the terminal (120) can be minimized. Accordingly, there is an effect of rapidly increasing throughput. According to the above-described embodiment, when the size of the data to be transmitted to the terminal (120) is greater than or equal to a reference size, the PDCP entity (701) can transmit data to the terminal (120) using both the primary path and the auxiliary path. Accordingly, there is an effect of increasing peak throughput.

[0171] According to the above-described embodiment, if the size of the data to be transmitted to the terminal (120) is smaller than the reference size, the PDCP entity (701) can transmit the data to the terminal (120) only through the path (720) set as the primary path. Even if the condition of the second channel (721) (or the wireless environment on the path (720)) on the path (720) set as the primary path is worse than the condition of the first channel (711) (or the wireless environment on the path (710)) on the path (710) set as the auxiliary path, the PDCP entity (701) can transmit the data to the terminal (120) through the path (710) set as the primary path.

[0172] In the specification below, specific operations of a PDCP entity (701) for transmitting data to a terminal (120) via only an auxiliary path when the size of the data to be transmitted to the terminal (120) is smaller than the reference size will be described later.

[0173] FIG. 8 illustrates a flowchart regarding the operation of a PDCP entity for transmitting data to a terminal through a split bearer. In the following embodiments, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed, and at least two operations may be performed in parallel.

[0174] Referring to FIG. 8, in operation 810, the PDCP entity (701) can obtain a first AID regarding the primary path and a second AID regarding the secondary path. For example, the PDCP entity (701) can receive the first AID regarding the primary path from the first RLC entity (702) via the primary path. The PDCP entity (701) can receive the second AID regarding the secondary path from the second RLC entity (703) via the secondary path. For example, the PDCP entity (701) can receive (or obtain) the first AID and the second AID based on a specified period (or specified time interval). For example, the PDCP entity (701) can request the first AID from the first RLC entity (702) via polling. The PDCP entity (701) may receive (or obtain) a first AID from the first RLC entity (702) based on the above request. The PDCP entity (701) may request a second AID from the second RLC entity (703) through polling. The PDCP entity (701) may receive (or obtain) a second AID from the second RLC entity (703) based on the above request.

[0175] According to one embodiment, the first AID and the second AID may have a frame format as shown in the table below. The AID described in the table below may be an example of the first AID and the second AID.

[0176]

[0177] Referring to Table 1, the AID may include a protocol data unit (PDU) type. For example, the PDU type may indicate the structure of a user plane frame. For example, if the value of the PDU type is 2, it may indicate that the frame has an AID format. Conversely, if the value of the PDCU type is 0, it may indicate that the frame has a downlink user data format. Or, if the value of the PDCU type is 1, it may indicate that the frame has a downlink data delivery status (DDDS) format. For example, the length of the PDU type may be 4 bits.

[0178] An AID may include an assistance information indication. For example, the assistance information indication may indicate whether there is a number of assistance information fields. For example, if the value of the assistance information indication is 0, it may indicate that there are no assistance information fields. Conversely, if the value of the assistance information indication is 1, it may indicate that there are assistance information fields. For example, the length of the assistance information indication may be 1 bit.

[0179] The AID may include the number of support information fields. For example, the number of support information fields may indicate the number of pairs of support information types and radio quality support information. For example, the number of support information sets may be determined by the number of support information fields. For example, a support information set may include pairs of support information types and radio quality support information. For example, the length of the number of support information fields may be 1 octet (or 8 bits).

[0180] An AID may include a support information type. The support information type may be used to indicate the type of radio quality support information. For example, if the value of the support information type is 1, the radio quality support information mapped to (or corresponding to, paired with) the support information type may indicate the value of the average CQI (channel quality indicator) (or CQI). For example, if the value of the support information type is 2, the radio quality support information may indicate the value of the average HARQ (hybrid automatic repeat and request) failures. For example, if the value of the support information type is 3, the radio quality support information may indicate the value of the average HARQ retransmissions. For example, if the value of the support information type is 4, the radio quality support information may indicate the downlink radio quality index. For example, if the value of the support information type is 5, the radio quality support information may indicate the uplink radio quality index. For example, if the value of the support information type is 6, the radio quality support information may indicate the power headroom report (PHR). For example, if the value of the support information type is 7, the radio quality support information may indicate the average number of HARQ transmissions. However, the present disclosure is not limited thereto. For example, depending on the value of the support information type, the radio quality support information may indicate other types of radio quality indicators (e.g., RSRP, RSRQ, RSSI, SINR, SNR, BLER). For example, the length of the support information type may be 1 octet.

[0181] The AID may include the number of octets for the radio quality support information fields. For example, the number of octets for the radio quality support information fields may be used to indicate the length of the existing radio quality support information. For example, for the average CQI, the number of octets for the radio quality support information fields may indicate 1. For example, for the average number of HARQ transmissions, the number of octets for the radio quality support information fields may indicate 4. For example, the length of the number of octets for the radio quality support information fields may be 1 octet.

[0182] The AID may include radio quality support information. For example, the radio quality support information may be referenced as radio quality information, radio quality values, or quality parameters. For example, the radio quality support information may indicate support information indicated by the support information type. For example, the radio quality support information may include an average CQI (or CQI). However, as described above, the radio quality support information may include other radio quality indicators. For example, the length of the radio quality support information may be one octet.

[0183] The AIDs shown in Table 1 are merely exemplary for convenience of explanation and the present disclosure is not limited thereto. For example, they may include additional information other than the information (or information element (IE)) included in the AID, or they may not include at least some of the information included in the AID in the table below. For example, the length (or number of bits) of the information included in the AID in Table 1 and the position within the frame are merely exemplary and the present disclosure is not limited thereto.

[0184] In operation 820, the PDCP entity (701) can obtain first radio quality information regarding the base path. For example, the PDCP entity (701) can obtain first radio quality information regarding the base path based on the first AID. For example, the first radio quality information may include an average CQI (channel quality indicator), an average HARQ (hybrid automatic repeat request) failure value, an average HARQ retransmission value, a downlink radio quality index, an uplink radio quality index, a power headroom report, an average number of HARQ transmissions, or a combination thereof.

[0185] In operation 830, the PDCP entity (701) may obtain second radio quality information regarding the primary path. For example, the PDCP entity (701) may obtain second radio quality information regarding the primary path based on the second AID. For example, the second radio quality information may include an average CQI (channel quality indicator), an average HARQ (hybrid automatic repeat request) failure value, an average HARQ retransmission value, a downlink radio quality index, an uplink radio quality index, a power headroom report, an average number of HARQ transmissions, or a combination thereof.

[0186] In operation 840, the PDCP entity (701) can identify whether the size of the data to be transmitted is smaller than the reference size for transmission through a single path. For example, the PDCP entity (701) can use a split bearer to identify whether the size of the data to be transmitted to the terminal (120) is smaller than the reference size for transmission through a single path.

[0187] According to one embodiment, the PDCP entity (701) can set a reference size for transmission through a single path. For example, the reference size can be used to determine one of a single path and a multipath. If the size of the data to be transmitted is smaller than the reference size, the data may be transmitted through a single path. If the size of the data to be transmitted is greater than or equal to the reference size, the data may be transmitted through a multipath. For example, the PDCP entity (701) may transmit data to the terminal (120) through a single path if the size of the data to be transmitted is smaller than the reference size in order to reduce waste of wireless resources.

[0188] According to one embodiment, if the size of the data to be transmitted is not smaller than the reference size for transmission through a single path, the PDCP entity (701) can perform operation 850. For example, the PDCP entity (701) can transmit data to a terminal using a primary path and a secondary path based on identifying that the size of the data to be transmitted is not smaller than the reference size for transmission through a single path.

[0189] In operation 860, if the size of the data to be transmitted is smaller than the reference size for transmission through a single path, the PDCP entity (701) may determine the path to transmit the data as an auxiliary path based on the first radio quality information and the second radio quality information. For example, the PDCP entity (701) may identify that the size of the data to be transmitted is smaller than the reference size for transmission through a single path. Based on the identification, the PDCP entity (701) may determine the path to transmit the data as an auxiliary path based on the first radio quality information and the second radio quality information.

[0190] According to one embodiment, the PDCP entity (701) can identify, based on the first wireless quality information and the second wireless quality information, that the state of the auxiliary path is more suitable for transmitting data than the state of the primary path. Based on identifying that the state of the auxiliary path is more suitable for transmitting data than the state of the primary path, the PDCP entity (701) can determine the path to transmit data as the auxiliary path. For example, the PDCP entity (701) can identify, based on the first wireless quality information and the second wireless quality information, that the channel state of the auxiliary path is better than the channel state of the primary path. Based on identifying that the channel state of the auxiliary path is better than the channel state of the primary path, the PDCP entity (701) can determine the path to transmit data as the auxiliary path.

[0191] For example, the PDCP entity (701) can identify the state of the primary path as one of a first state (e.g., 'strong') and a second state (e.g., 'weak') based on the first radio quality information. The PDCP entity (701) can identify the state of the secondary path as one of a first state (e.g., 'strong') and a second state (e.g., 'weak') based on the second radio quality information. The PDCP entity (701) can identify that the state of the primary path is the second state and the state of the secondary path is the first state. Based on identifying that the state of the primary path is the second state and the state of the secondary path is the first state, the PDCP entity (701) can determine the path to transmit data as the secondary path. Specific operations of the above-described example will be described later in FIGS. 9 to 10b.

[0192] In operation 870, the PDCP entity (701) can transmit data to the terminal (120) using an auxiliary path. According to one embodiment, the PDCP entity (701) can transmit a signal (or message) to the terminal (120) indicating that data will be transmitted through the auxiliary path. The PDCP entity (701) can transmit data to the terminal (120) using an auxiliary path through a designated resource.

[0193] The operations of FIG. 8 can be performed by the communication device (610) of FIG. 6. For example, at least some of the operations can be controlled by the processor (611) of the communication device (610).

[0194] FIG. 9 illustrates a flowchart regarding the operation of a PDCP entity for determining a path to transmit data. In the following embodiments, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed, and at least two operations may be performed in parallel.

[0195] Referring to FIG. 9, in operation 910, the PDCP entity (701) can identify the state of the base path as one of the first state and the second state based on the first radio quality information. For example, the PDCP entity (701) can identify the first radio quality information based on the first AID. The PDCP entity (701) can identify the state of the primary path as either "strong" or "weak" based on the first radio quality information. For example, the PDCP entity (701) can identify the state of the primary path as either a first state or a second state based on identifying whether a first value (e.g., average CQI of the primary path) according to the first radio quality information exceeds a first reference quality value. The PDCP entity (701) can identify the state of the primary path as a first state based on identifying that a first value (e.g., average CQI of the primary path) according to the first radio quality information exceeds a first reference quality value. The PDCP entity (701) can identify the state of the primary path as a second state based on identifying that a first value (e.g., average CQI of the primary path) according to the first radio quality information is less than or equal to a first reference quality value. Specific details of the PDCP entity (701) for identifying the state of the primary path The operation will be described later in Fig. 10a.

[0196] In operation 920, the PDCP entity (701) can identify the state of the auxiliary path as one of the first state and the second state based on the second radio quality information. For example, the PDCP entity (701) can identify the second radio quality information based on the first AID. The PDCP entity (701) can identify the state of the auxiliary path as either "strong" or "weak" based on the second radio quality information. For example, the PDCP entity (701) can identify the state of the auxiliary path as either a first state or a second state based on identifying whether a second value (e.g., average CQI of the auxiliary path) according to the second radio quality information exceeds a third reference quality value. The PDCP entity (701) can identify the state of the auxiliary path as a first state based on identifying that a second value (e.g., average CQI of the auxiliary path) according to the second radio quality information exceeds a third reference quality value. The PDCP entity (701) can identify the state of the auxiliary path as a second state based on identifying that a second value (e.g., average CQI of the auxiliary path) according to the second radio quality information is less than or equal to the third reference quality value. Specific details of the PDCP entity (701) for identifying the state of the auxiliary path The operation will be described later in Fig. 10b.

[0197] In operation 930, the PDCP entity (701) can identify whether the state of the base path is a second state. If the state of the base path is not a second state, the PDCP entity (701) can perform operation 940. If the state of the base path is a first state, the PDCP entity (701) can perform operation 940. Based on identifying that the state of the base path is a first state, the PDCP entity (701) can determine the path to transmit data as the base path.

[0198] In operation 950, the PDCP entity (701) can identify whether the state of the auxiliary path is a first state. If the state of the auxiliary path is not a first state, the PDCP entity (701) can perform operation 940. If the state of the auxiliary path is a second state, the PDCP entity (701) can perform operation 940. Based on identifying that the state of the auxiliary path is a second state, the PDCP entity (701) can determine the path to transmit data as the primary path.

[0199] In operation 960, if the state of the auxiliary path is the first state, the PDCP entity (701) can determine the path to transmit data as the auxiliary path. For example, the PDCP entity (701) can determine the path to transmit data as the auxiliary path based on identifying that the state of the auxiliary path is the first state.

[0200] According to FIG. 9, the PDCP entity (701) can determine the path to transmit data as the auxiliary path based on identifying that the state of the primary path is the second state and the state of the auxiliary path is the first state. The PDCP entity (701) can determine the path to transmit data as the primary path based on identifying that the state of the primary path is the second state and the state of the auxiliary path is not the first state. For example, the PDCP entity (701) can determine the path to transmit data as the auxiliary path if the wireless quality of the auxiliary path is better than the wireless quality of the primary path.

[0201] According to the above-described embodiment, the path determined by the state of the basic path and the state of the auxiliary path can be set as shown in the table below.

[0202] Primary Path Secondary Path Determined Path STRONG STRONG Primary Path STRONG WEAK Primary Path WEAK STRONG Secondary Path WEAK WEAK Primary Path

[0203] Referring to Table 2, the PDCP entity (701) can determine the path to transmit data as the auxiliary path only when the state of the auxiliary path is the first state (e.g., 'strong') and the state of the primary path is the second state (e.g., 'weak'). For example, if the quality of the channel regarding the auxiliary path (e.g., the first channel (711) in FIG. 7) is higher than the quality of the channel regarding the primary path (e.g., the second channel (721) in FIG. 7), the PDCP entity (701) can determine the path to transmit data as the auxiliary path. For example, if the state of the wireless environment (or air condition) regarding the auxiliary path is better than the state of the wireless environment (or air condition) regarding the primary path, the PDCP entity (701) can determine the path to transmit data as the auxiliary path.

[0204] The operations of FIG. 9 can be performed by the communication device (610) of FIG. 6. For example, at least some of the operations can be controlled by the processor (611) of the communication device (610).

[0205] FIG. 10a illustrates a flowchart regarding the operation of a PDCP entity for setting the state of a basic path.

[0206] FIG. 10b illustrates a flowchart regarding the operation of a PDCP entity for setting the state of an auxiliary path.

[0207] In the following embodiments, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed, and at least two operations may be performed in parallel.

[0208] Referring to FIG. 10a, in operation 1001, the PDCP entity (701) can identify a first value according to the first radio quality information. For example, the first radio quality information may include an average CQI (channel quality indicator), an average HARQ (hybrid automatic repeat request) failure value, an average HARQ retransmission value, a downlink radio quality index, an uplink radio quality index, a power headroom report, an average number of HARQ transmissions, or a combination thereof. The first value according to the first radio quality information may be one of the average CQI (channel quality indicator), an average HARQ (hybrid automatic repeat request) failure value, an average HARQ retransmission value, a downlink radio quality index, an uplink radio quality index, a power headroom report, an average number of HARQ transmissions, or a combination thereof.

[0209] According to one embodiment, a first reference quality value and a second reference quality value may be set to set (or identify, determine) the state regarding a basic path (e.g., path (720) of FIG. 7). For example, the first reference quality value may be set higher than the second reference quality value.

[0210] The PDCP entity (701) can set (or identify, determine) the state of the base path to one of the first state and the second state using the first reference quality value and the second reference quality value. When one reference quality value is set, if the first value is similar to the set reference quality value, repeated state changes may occur. Therefore, two reference quality values ​​may be set to identify the state of the base path.

[0211] In operation 1002, the PDCP entity (701) can identify whether the first value exceeds the first reference quality value.

[0212] For example, the PDCP entity (701) may perform action 1003 if the first value exceeds the first reference quality value. For example, the PDCP entity (701) may set (or identify, determine) the state regarding the base path to the first state (e.g., 'strong') based on identifying that the first value exceeds the first reference quality value.

[0213] In operation 1004, if the first value does not exceed the first reference quality value, the PDCP entity (701) can identify whether the first value is greater than or equal to the second reference quality value. For example, the PDCP entity (701) can identify whether the first value is greater than or equal to the second reference quality value based on identifying that the first value does not exceed the first reference quality value.

[0214] The PDCP entity (701) may perform operation 1005 if the first value is not greater than or equal to the second reference quality value. For example, the PDCP entity (701) may set (or identify, determine) the state regarding the base path to a second state (e.g., 'weak') based on identifying that the first value is not greater than or equal to the second reference quality value.

[0215] In operation 1006, if the first value is greater than or equal to the second reference quality value, the PDCP entity (701) may maintain the state regarding the default path. The PDCP entity (701) may maintain the state regarding the default path based on identifying that the first value is greater than or equal to the second reference quality value. For example, if the first value is less than or equal to the first reference quality value and greater than or equal to the second reference quality value, the PDCP entity (701) may maintain the state regarding the default path in the current state.

[0216] Referring to FIG. 10b, the PDCP entity (701) can perform operations corresponding to operations 1001 to 1006 of FIG. 10a for a second value according to the second wireless quality information. Operations 1011 to 1016 may correspond to operations 1001 to 1006 of FIG. 10a.

[0217] In operation 1011, the PDCP entity (701) can identify a first value according to second radio quality information. For example, the second radio quality information may include an average CQI (channel quality indicator), an average HARQ (hybrid automatic repeat request) failure value, an average HARQ retransmission value, a downlink radio quality index, an uplink radio quality index, a power headroom report, an average number of HARQ transmissions, or a combination thereof. The first value according to the second radio quality information may be one of an average CQI (channel quality indicator), an average HARQ (hybrid automatic repeat request) failure value, an average HARQ retransmission value, a downlink radio quality index, an uplink radio quality index, a power headroom report, an average number of HARQ transmissions, or a combination thereof.

[0218] According to one embodiment, a third reference quality value and a fourth reference quality value may be set to set (or identify, determine) the state regarding an auxiliary path (e.g., path (710) of FIG. 7). For example, the third reference quality value may be set higher than the fourth reference quality value.

[0219] The PDCP entity (701) can set (or identify, determine) the state of the auxiliary path to one of the first state and the second state using the third standard quality value and the fourth standard quality value. When one standard quality value is set, if the first value is similar to the set standard quality value, repeated state changes may occur. Therefore, two standard quality values ​​may be set to identify the state of the auxiliary path.

[0220] In operation 1012, the PDCP entity (701) can identify whether the second value exceeds the third standard quality value.

[0221] For example, the PDCP entity (701) may perform action 1013 if the second value exceeds the third standard quality value. For example, the PDCP entity (701) may set (or identify, determine) the state regarding the auxiliary path to the first state (e.g., 'strong') based on identifying that the second value exceeds the third standard quality value.

[0222] In operation 1014, if the second value does not exceed the third reference quality value, the PDCP entity (701) can identify whether the second value is greater than or equal to the fourth reference quality value. For example, the PDCP entity (701) can identify whether the second value is greater than or equal to the fourth reference quality value based on identifying that the second value does not exceed the third reference quality value.

[0223] The PDCP entity (701) may perform operation 1015 if the second value is not greater than or equal to the fourth reference quality value. For example, the PDCP entity (701) may set (or identify, determine) the state regarding the auxiliary path to the second state (e.g., 'weak') based on identifying that the second value is not greater than or equal to the fourth reference quality value.

[0224] In operation 1016, if the second value is greater than or equal to the fourth reference quality value, the PDCP entity (701) may maintain the state regarding the auxiliary path. The PDCP entity (701) may maintain the state regarding the auxiliary path based on identifying that the second value is greater than or equal to the fourth reference quality value. For example, if the second value is less than or equal to the third reference quality value and greater than or equal to the fourth reference quality value, the PDCP entity (701) may maintain the state regarding the auxiliary path in the current state.

[0225] Referring to FIGS. 10a and 10b, a first reference quality value for setting (or determining, identifying) the state regarding the primary path and a third reference quality value for setting (or determining, identifying) the state regarding the secondary path may be set differently. Depending on the embodiment, the first reference quality value and the third reference quality value may be set identically. For example, if the primary path is related to SCG, the first reference quality value may be referenced as HighAirConditionThresholdScg. HighAirConditionThresholdScg may be a reference value for identifying the channel state (or air condition) regarding SCG as 'strong'. If the secondary path is related to MCG, the third reference quality value may be referenced as HighAirConditionThresholdMcg. HighAirConditionThresholdMcg may be a reference value for identifying the channel state (or air condition) regarding MCG as 'strong'.

[0226] A second reference quality value for setting (or determining, identifying) the state regarding an auxiliary path and a fourth reference quality value for setting (or determining, identifying) the state regarding an auxiliary path may be set differently. Depending on the embodiment, the second reference quality value and the fourth reference quality value may be set identically. For example, if the primary path is related to SCG, the first reference quality value may be referenced as LowAirConditionThresholdScg. LowAirConditionThresholdScg may be a reference value for identifying the channel state (or air condition) regarding SCG as 'weak'. If the auxiliary path is related to MCG, the third reference quality value may be referenced as LowAirConditionThresholdMcg. LowAirConditionThresholdMcg may be a reference value for identifying the channel state (or air condition) regarding MCG as 'weak'.

[0227] The operations of FIGS. 10a and FIGS. 10b can be performed by the communication device (610) of FIG. 6. For example, at least some of the operations can be controlled by the processor (611) of the communication device (610).

[0228] FIG. 11 illustrates a flowchart regarding the operation of a PDCP entity for setting a path to transmit data. In the following embodiments, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed, and at least two operations may be performed in parallel.

[0229] Referring to FIG. 11, in operation 1110, the PDCP entity (701) can determine a path to transmit data as an auxiliary path. For example, operation 1100 may correspond to operation 960 of FIG. 9. For example, based on the operations according to FIG. 9, the PDCP entity (701) can determine a path to transmit data as an auxiliary path.

[0230] In operation 1120, the PDCP entity (701) can identify whether the size of the data to be transmitted is smaller than another reference size. For example, the PDCP entity (701) can identify whether the size of the data to be transmitted to the terminal (120) is smaller than another reference size that is less than the reference size.

[0231] For example, the PDCP entity (701) may set (or determine) the auxiliary path as the path to transmit data only when more restrictive conditions are satisfied. To set (or determine) the auxiliary path as the path to transmit data, the PDCP entity (701) may identify whether the size of the data to be transmitted is smaller than another reference size. For example, the other reference size may be distinguished from the reference size according to operation 840 of FIG. 8. The other reference size may be less than the reference size according to operation 840 of FIG. 8.

[0232] According to one embodiment, the PDCP entity (701) can identify that the size of the data has changed. The PDCP entity (701) can identify whether the size of the changed data is smaller than another reference size.

[0233] In operation 1130, if the size of the data is smaller than another reference size, the PDCP entity (701) may maintain the path for transmitting the data as a secondary path. The PDCP entity (701) may maintain the path for transmitting the data as a secondary path based on identifying that the size of the data is smaller than another reference size. According to one embodiment, the PDCP entity (701) may maintain the path for transmitting the data as a secondary path if the size of the changed data is smaller than another reference size.

[0234] In operation 1140, if the size of the data is greater than or equal to a different reference size, the PDCP entity (701) may set the path to transmit the data to a multi-path. The PDCP entity (701) may set the path to transmit the data to a multi-path based on identifying that the size of the data is greater than or equal to a different reference size. According to one embodiment, if the size of the changed data is smaller than a different reference size, the PDCP entity (701) may change the path to transmit the data from a secondary path to a multi-path.

[0235] For example, if the size of the data is greater than or equal to a different standard size, the PDCP entity (701) can set the path for transmitting the data as a primary path and a secondary path. The PDCP entity (701) can transmit data to the terminal (120) using both the primary path and the secondary path.

[0236] In FIGS. 7 to 11, an embodiment in which a path for transmitting downlink data to a terminal (120) is set is described, but is not limited thereto. The above-described embodiments may also be applied when a path for transmitting uplink data is set. In FIGS. 12 and 13, the operation of a terminal for setting a path for transmitting uplink data will be described.

[0237] FIG. 12 illustrates an example in which a terminal transmits data to a PDCP entity through a split bearer.

[0238] Referring to FIG. 12, the terminal (120) can be connected to a first RLC entity (702) and a second RLC entity (703) based on dual connectivity (DC). The PDCP entity (701) may correspond to the PDCP entity (701) of FIG. 7. The first RLC entity (702) may correspond to the first RLC entity (702) of FIG. 7. The second RLC entity (703) may correspond to the second RLC entity (703) of FIG. 7.

[0239] According to one embodiment, the terminal (120) can perform distribution of data (or packets) to be transmitted to the PDCP entity (701) to the first RLC entity (702) of the master cell group (MCG) and the second RLC entity (703) of the secondary cell group (SCG). For example, the terminal (120) can perform distribution of data to be transmitted to the PDCP entity (701) (or base station) using multiple paths.

[0240] According to one embodiment, the multiple paths may include a primary path and a secondary path. A terminal (120) may transmit data (or packets) to a PDCP entity (701) using at least one of path (1211) and path (1221). One of path (1210) and path (1220) may be set as the primary path. The other of path (1210) and path (1220) may be set as the secondary path. The primary path may be configured by RRC. The secondary path may be configured by RRC. For example, the direction of path (1210) may be opposite to the direction of path (710) of FIG. 7. The direction of path (1220) may be opposite to the direction of path (720) of FIG. 7. Path (1210) is a path through which uplink data is transmitted, and path (710) of FIG. 7 may be a path through which downlink data is transmitted. Path (1220) is a path through which uplink data is transmitted, and path (720) of FIG. 7 may be a path through which downlink data is transmitted.

[0241] Below, an example will be described in which path (1210) is set as an auxiliary path and path (1220) is set as a primary path. However, it is not limited thereto. This is for the convenience of explanation, and path (1210) may be set as a primary path and path (1220) may be set as an auxiliary path.

[0242] According to one embodiment, the terminal (120) can identify the size of data (e.g., uplink data) to be transmitted to the PDCP entity (701). The terminal (120) can identify whether the size of the data to be transmitted to the PDCP entity (701) is smaller than a reference size for transmission through a single path.

[0243] For example, if the size of the data to be transmitted to the PDCP entity (701) is smaller than the reference size for transmission through a single path, the terminal (120) can transmit the data to the PDCP entity (701) through the path (1220) set as the default path. For example, if the size of the data to be transmitted to the PDCP entity (701) is smaller than the reference size, the terminal (120) can submit the PDCP PDU to the second RLC entity (703) for the path (1220) set as the default path.

[0244] If the size of the data to be transmitted to the PDCP entity (701) is greater than or equal to the reference size, the terminal (120) can transmit the data to the PDCP entity (701) through both the path (1220) set as the primary path and the path (1210) set as the secondary path. For example, if the size of the data to be transmitted to the PDCP entity (701) is greater than or equal to the reference size, the terminal (120) can submit the PDCP PDU to the first RLC entity (702) and the second RLC entity (703).

[0245] According to the above-described embodiment, when the size of the data to be transmitted to the PDCP entity (701) is smaller than the reference size, the terminal (120) can transmit the data to the PDCP entity (701) only through the path (1220) set as the primary path. Even when the condition of the second channel (1221) (or the wireless environment on the path (1220)) on the path (1220) set as the primary path is worse than the condition of the first channel (1211) (or the wireless environment on the path (1210)) on the path (1210) set as the auxiliary path, the terminal (120) can transmit the data to the PDCP entity (701) through the path (1210) set as the primary path.

[0246] In the specification below, specific operations of a terminal (120) for transmitting data to a PDCP entity (701) via only an auxiliary path when the size of the data to be transmitted to a PDCP entity (701) is smaller than the reference size will be described later.

[0247] FIG. 13 illustrates a flowchart regarding the operation of a terminal for transmitting data to a PDCP entity through a split bearer. In the following embodiments, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed, and at least two operations may be performed in parallel.

[0248] Referring to FIG. 13, in operation 1310, the terminal (120) (or the processor of the terminal (120)) can identify a primary path and a secondary path. For example, the terminal (120) can identify a primary path and a secondary path based on RRC. The terminal (120) can identify a second RLC entity (703) regarding the primary path. The terminal (120) can identify a first RLC entity (702) regarding the secondary path. The terminal (120) can identify the path (1220) of FIG. 12 as the primary path. The terminal (120) can identify the path (1210) of FIG. 12 as the secondary path.

[0249] According to one embodiment, the terminal (120) can identify a transmission mode based on an RRC message. For example, the terminal (120) can identify one of a first transmission mode and a second transmission mode based on an RRC message. In the first transmission mode, the terminal (120) can transmit data to the PDCP entity (701) only through a primary path if the size of the data to be transmitted is smaller than the reference size for transmission through a single path. In the second transmission mode, the terminal (120) can transmit data to the PDCP entity (701) only through an auxiliary path even if the size of the data to be transmitted is smaller than the reference size for transmission through a single path. Based on identifying the transmission mode as the second transmission mode, the terminal (120) can perform operations 1320 to 1370.

[0250] In operation 1320, the terminal (120) can obtain first radio quality information regarding the basic path. For example, the terminal (120) can obtain (or receive) first radio quality information regarding the basic path based on a signal received from the second RLC entity (703). The terminal (120) can obtain first radio quality information regarding the basic path (e.g., CQI (channel quality indicator), precoding matrix indicator, RI (rank indicator)) based on a reference signal (e.g., CSI-RS) received through the basic path. According to an embodiment, the first radio quality information may correspond to the first radio quality information of operation 820 of FIG. 8.

[0251] In operation 1330, the terminal (120) can obtain second radio quality information regarding the auxiliary path. For example, the terminal (120) can obtain (or receive) second radio quality information regarding the auxiliary path based on a signal received from the first RLC entity (702). The terminal (120) can obtain second radio quality information regarding the primary path (e.g., CQI (channel quality indicator), PMI (precoding matrix indicator), RI (rank indicator)) based on a reference signal (e.g., CSI-RS) received through the auxiliary path. According to an embodiment, the second radio quality information may correspond to the second radio quality information of operation 830 of FIG. 8.

[0252] In operation 1340, the terminal (120) can identify whether the size of the data to be transmitted is smaller than the reference size for transmission through a single path. Operation 1340 may correspond to operation 840 of FIG. 8.

[0253] According to one embodiment, if the size of the data to be transmitted is not smaller than a reference size, the terminal (120) can perform operation 1350. For example, the terminal (120) can transmit data to a base station (e.g., PDCP entity (701)) using a reference path and an auxiliary path based on identifying that the size of the data to be transmitted is greater than or equal to the reference size.

[0254] In operation 1360, if the size of the data to be transmitted is smaller than the reference size, the terminal (120) may determine the path to transmit the data as an auxiliary path based on the first wireless quality information and the second wireless quality information. For example, the terminal (120) may identify that the size of the data to be transmitted is smaller than the reference size for transmission through a single path. Based on the identification, the terminal (120) may determine the path to transmit the data as an auxiliary path based on the first wireless quality information and the second wireless quality information.

[0255] According to one embodiment, the terminal (120) can identify, based on the first wireless quality information and the second wireless quality information, that the state of the auxiliary path is more suitable for transmitting data than the state of the primary path. Based on identifying that the state of the auxiliary path is more suitable for transmitting data than the state of the primary path, the terminal (120) can determine the path to transmit data as the auxiliary path. For example, the terminal (120) can identify, based on the first wireless quality information and the second wireless quality information, that the channel state of the auxiliary path is better than the channel state of the primary path. Based on identifying that the channel state of the auxiliary path is better than the channel state of the primary path, the terminal (120) can determine the path to transmit data as the auxiliary path.

[0256] For example, the terminal (120) can identify the state of the primary path as one of a first state (e.g., 'strong') and a second state (e.g., 'weak') based on the first wireless quality information. The terminal (120) can identify the state of the secondary path as one of a first state (e.g., 'strong') and a second state (e.g., 'weak') based on the second wireless quality information. The terminal (120) can identify that the state of the primary path is the second state and the state of the secondary path is the first state. Based on identifying that the state of the primary path is the second state and the state of the secondary path is the first state, the terminal (120) can determine the path to transmit data as the secondary path.

[0257] For example, if the first value according to the first wireless quality exceeds the first standard quality value, the terminal (120) may identify (or set, determine) the state regarding the basic path as the first state. If the first value according to the first wireless quality is less than the second standard quality value, the terminal (120) may identify (or set, determine) the state regarding the basic path as the second state. If the first value according to the first wireless quality is less than or equal to the first standard quality value and greater than or equal to the second standard quality value, the terminal (120) may maintain the state regarding the basic path.

[0258] For example, if the second value according to the second wireless quality exceeds the third standard quality value, the terminal (120) may identify (or set, determine) the state regarding the basic path as the second state. If the second value according to the second wireless quality is less than the fourth standard quality value, the terminal (120) may identify (or set, determine) the state regarding the basic path as the second state. If the second value according to the second wireless quality is less than or equal to the third standard quality value and greater than or equal to the fourth standard quality value, the terminal (120) may maintain the state regarding the basic path.

[0259] According to one embodiment, after determining a path to transmit data as an auxiliary path, the terminal (120) can identify whether the size of the data to be transmitted is smaller than another reference size that is less than a reference size. If the size of the data to be transmitted is less than a reference size, the terminal (120) can maintain the path to transmit data as an auxiliary path. If the size of the data to be transmitted is greater than or equal to a reference size, the terminal (120) can set (or change) the path to transmit data to a multiple path including a primary path and an auxiliary path.

[0260] In operation 1370, the terminal (120) may transmit data to a base station (e.g., PDCP entity (701) or second RLC entity (703)) using an auxiliary path. According to one embodiment, the terminal (120) may transmit a signal (or message) to the base station indicating that data will be transmitted through the auxiliary path. The terminal (120) may transmit data to the base station using the auxiliary path through a designated resource.

[0261] According to one embodiment, a communication device providing functions of a PDCP (packet data convergence protocol) entity may include a transceiver, at least one processor including a processing circuit, and a memory including one or more storage media for storing instructions. The above instructions, when executed individually or collectively by the at least one processor, may cause the communication device to obtain a first AID (assistance information data) regarding a primary path for a split bearer and a second AID regarding a secondary path for the split bearer, obtain first radio quality information regarding the primary path based on the first AID, obtain second radio quality information regarding the secondary path based on the second AID, identify that the size of the data to be transmitted using the split bearer is smaller than a reference size for transmission through a single path, determine the path to transmit the data as the secondary path based on the first radio quality information and the second radio quality information, and transmit the data having a size smaller than the reference size to a terminal using the secondary path.

[0262] For example, when the above instructions are executed individually or collectively by the at least one processor, the communication device may be caused to identify the state of the primary path as one of the first state and the second state based on the first wireless quality information, and identify the state of the auxiliary path as one of the first state and the second state based on the second wireless quality information.

[0263] For example, the above instructions may cause the communication device to identify that the state of the basic path is the second state and the state of the auxiliary path is the first state when executed individually or collectively by the at least one processor, and to determine the path to transmit the data as the auxiliary path based on the state of the basic path being the second state and the state of the auxiliary path being the first state.

[0264] For example, the above instructions may cause the communication device to be configured such that, when executed individually or collectively by the at least one processor, the state regarding the basic path is set to the first state based on identifying that the first value according to the first wireless quality information exceeds the first reference quality value, the state regarding the basic path is set to the second state based on identifying that the first value according to the first wireless quality information is less than the second reference quality value, and the state regarding the basic path is maintained based on identifying that the first value according to the first wireless quality information is less than or equal to the first reference quality value and the first value according to the first wireless quality information is greater than or equal to the second reference quality value.

[0265] For example, the above instructions may cause the communication device to be configured such that, when executed individually or collectively by the at least one processor, the state regarding the auxiliary path is set to the first state based on identifying that the second value according to the second wireless quality information exceeds the third reference quality value, the state regarding the auxiliary path is set to the second state based on identifying that the second value according to the second wireless quality information is less than the fourth reference quality value, and the state regarding the auxiliary path is maintained based on identifying that the second value according to the second wireless quality information is less than or equal to the third reference quality value and the second value according to the second wireless quality information is greater than or equal to the fourth reference quality value.

[0266] For example, when the above instructions are executed individually or collectively by the at least one processor, the communication device may be configured to determine the path to transmit the data as the auxiliary path based on the second state, which is the state of the primary path, and the first state, which is the state of the auxiliary path, whether the size of the data is smaller than another reference size that is less than the reference size, and based on the determination that the size of the data is smaller than the other reference size.

[0267] For example, the above instructions may cause the communication device to set the path for transmitting the data as a multiple path including the primary path and the auxiliary path, based on identifying that the size of the data is greater than or equal to the other reference size when executed individually or collectively by the at least one processor.

[0268] For example, the communication device may include a central unit (CU).

[0269] For example, the above primary path may correspond to a path between the PDCP entity and the terminal connected through a first RLC (radio link control) entity. The above auxiliary path may correspond to a path between the PDCP entity and the terminal connected through a second RLC entity distinct from the first RLC entity.

[0270] For example, each of the first radio quality information and the second radio quality information may include at least one of an average CQI (channel quality indicator), an average HARQ (hybrid automatic repeat request) failure value, an average HARQ retransmission value, a downlink radio quality index, an uplink radio quality index, a power headroom report, or an average number of HARQ transmissions.

[0271] According to one embodiment, a method performed by a communication device providing functions of a packet data convergence protocol (PDCP) entity may include: obtaining a first assistance information data (AID) regarding a primary path for a split bearer and a second AID regarding a secondary path for said split bearer; obtaining first radio quality information regarding said primary path based on said first AID; obtaining second radio quality information regarding said secondary path based on said second AID; identifying that the size of data to be transmitted using said split bearer is smaller than a reference size for transmission through a single path; determining the path to transmit said data as said secondary path based on said first radio quality information and said second radio quality information; and transmitting said data having a size smaller than said reference size to a terminal using said secondary path.

[0272] For example, the above method may include an operation of identifying the state of the basic path as one of the first state and the second state based on the first wireless quality information, and an operation of identifying the state of the auxiliary path as one of the first state and the second state based on the second wireless quality information.

[0273] For example, the above method may include an operation of identifying that the state of the basic path is the second state and the state of the auxiliary path is the first state, and an operation of determining the path to transmit the data as the auxiliary path based on the state of the basic path being the second state and the state of the auxiliary path being the first state.

[0274] For example, the above method may include an operation of setting the state regarding the basic path to the first state based on identifying that the first value according to the first wireless quality information exceeds the first reference quality value; an operation of setting the state regarding the basic path to the second state based on identifying that the first value according to the first wireless quality information is less than the second reference quality value; and an operation of setting the state regarding the basic path to be maintained based on identifying that the first value according to the first wireless quality information is less than or equal to the first reference quality value and the first value according to the first wireless quality information is greater than or equal to the second reference quality value.

[0275] For example, the above method may include an operation of setting the state regarding the auxiliary path to the first state based on identifying that the second value according to the second wireless quality information exceeds the third standard quality value; an operation of setting the state regarding the auxiliary path to the second state based on identifying that the second value according to the second wireless quality information is less than the fourth standard quality value; and an operation of setting the state regarding the auxiliary path to be maintained based on identifying that the second value according to the second wireless quality information is less than or equal to the third standard quality value and the second value according to the second wireless quality information is greater than or equal to the fourth standard quality value.

[0276] For example, the above method may include an operation of identifying whether the size of the data is smaller than another reference size that is less than the reference size, based on the state of the basic path which is the second state and the state of the auxiliary path which is the first state, and an operation of determining the path to transmit the data as the auxiliary path based on identifying that the size of the data is smaller than the other reference size.

[0277] For example, the above method may include an operation of setting a path to transmit the data as a multiple path including the basic path and the auxiliary path, based on identifying that the size of the data is greater than or equal to the other reference size.

[0278] For example, the above primary path may correspond to a path between the PDCP entity and the terminal connected through a first RLC (radio link control) entity. The above auxiliary path may correspond to a path between the PDCP entity and the terminal connected through a second RLC entity distinct from the first RLC entity.

[0279] For example, each of the first radio quality information and the second radio quality information may include at least one of an average CQI (channel quality indicator), an average HARQ (hybrid automatic repeat request) failure rate, an average HARQ retransmission rate, a downlink radio quality index, an uplink radio quality index, a power headroom index, or the average number of HARQ transmissions.

[0280] According to one embodiment, a non-transient computer-readable storage medium may store one or more programs. The one or more programs may include instructions that, when executed individually or collectively by at least one processor of a communication device including the transceiver, obtain a first AID (assistance information data) regarding a primary path for a split bearer and a second AID regarding a secondary path for the split bearer, obtain first radio quality information regarding the primary path based on the first AID, obtain second radio quality information regarding the secondary path based on the second AID, identify that the size of data to be transmitted using the split bearer is smaller than a reference size for transmission through a single path, determine the path to transmit the data as the secondary path based on the first radio quality information and the second radio quality information, and cause the communication device to transmit the data having a size smaller than the reference size to a terminal using the secondary path.

[0281] Methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0282] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of this disclosure. The one or more programs may be provided as a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or distributed online (e.g., download or upload) through an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0283] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disc storage devices, compact disc-ROM (CD-ROM), digital versatile discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0284] Additionally, the program may be stored on an attachable storage device that can be accessed via a communication network such as the Internet, Intranet, LAN (local area network), WAN (wide area network), or SAN (storage area network), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present disclosure.

[0285] In the specific embodiments of the present disclosure described above, the components included in the disclosure are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed of a singular form, and even if a component is expressed in the singular form, it may be composed of a plural form.

[0286] According to embodiments, one or more of the aforementioned components or operations may be omitted, or one or more other components or operations may be added. Generally or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In this case, the integrated component may perform one or more functions of each of the plurality of components in the same or similar manner as those performed by the corresponding component among the plurality of components prior to integration. According to embodiments, operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0287] Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, it is understood that various modifications are possible within the scope of the present disclosure.

Claims

1. In a communication device that provides the functions of a PDCP (packet data convergence protocol) entity, Transmitter / Receiver; At least one processor including a processing circuit; and Memory that stores instructions and includes one or more storage media, When the above instructions are executed individually or collectively by the at least one processor, Obtaining a first AID (assistance information data) regarding a primary path for a split bearer and a second AID regarding a secondary path for said split bearer, Based on the above first AID, first wireless quality information regarding the above basic path is obtained, and Based on the above second AID, second wireless quality information regarding the above auxiliary path is obtained, and Identify that the size of the data to be transmitted using the above split bearer is smaller than the reference size for transmission through a single path, and Based on the above first wireless quality information and the above second wireless quality information, the path to transmit the data is determined as the auxiliary path, and A communication device that causes the data having a size smaller than the reference size to be transmitted to a terminal using the above auxiliary path, Communication device.

2. In claim 1, when the instructions are executed individually or collectively by the at least one processor, Based on the above first wireless quality information, the state of the above basic path is identified as one of the first state and the second state, and A communication device that causes the state of the auxiliary path to be identified as one of the first state and the second state based on the second wireless quality information. Communication device.

3. In claim 2, when the instructions are executed individually or collectively by the at least one processor, Identifying that the state of the above basic path is the above second state and the state of the above auxiliary path is the above first state, and A communication device that causes the path to transmit the data to be determined as the auxiliary path based on the state of the basic path, which is the second state, and the state of the auxiliary path, which is the first state. Communication device.

4. In claim 3, when the instructions are executed individually or collectively by the at least one processor, Based on identifying that a first value according to the first wireless quality information exceeds a first reference quality value, the state regarding the basic path is set to the first state, and Based on identifying that the first value according to the first wireless quality information is less than the second standard quality value, the state regarding the basic path is set to the second state, and A communication device that causes to maintain the state regarding the basic path based on identifying that the first value according to the first wireless quality information is less than or equal to the first reference quality value and that the first value according to the first wireless quality information is greater than or equal to the second reference quality value. Communication device.

5. In claim 4, when the instructions are executed individually or collectively by the at least one processor, Based on identifying that the second value according to the second wireless quality information exceeds the third standard quality value, the state regarding the auxiliary path is set to the first state, and Based on identifying that the second value according to the second wireless quality information is less than the fourth standard quality value, the state regarding the auxiliary path is set to the second state, and A communication device that causes to maintain the state regarding the auxiliary path based on identifying that the second value according to the second wireless quality information is less than or equal to the third standard quality value and that the second value according to the second wireless quality information is greater than or equal to the fourth standard quality value. Communication device.

6. In claim 3, when the instructions are executed individually or collectively by the at least one processor, Based on the state of the basic path, which is the second state, and the state of the auxiliary path, which is the first state, it identifies whether the size of the data is smaller than another reference size that is less than the reference size, and Causing the communication device to determine the path to transmit the data as the auxiliary path based on identifying that the size of the data is smaller than the other reference size. Communication device.

7. In claim 6, when the instructions are executed individually or collectively by the at least one processor, A communication device that causes the path to transmit the data to be set as a multiple path including the primary path and the auxiliary path, based on identifying that the size of the data is greater than or equal to the other reference size. Communication device.

8. In Paragraph 1, The above communication device includes a CU (central unit), Communication device.

9. In claim 1, the basic path is, Corresponding to the path between the PDCP entity and the terminal connected through the first RLC (radio link control) entity, and The above auxiliary path is, Corresponding to the path of the PDCP entity and the terminal company connected through the second RLC entity distinguished from the first RLC entity, Communication device.

10. In claim 1, each of the first wireless quality information and the second wireless quality information is, at least one of the average CQI (channel quality indicator), the average HARQ (hybrid automatic repeat request) failure value, the average HARQ retransmission value, the downlink radio quality index, the uplink radio quality index, the power headroom report, or the average number of HARQ transmissions, Communication device.

11. A method performed by a communication device that provides the functions of a PDCP (packet data convergence protocol) entity, The operation of obtaining a first AID (assistance information data) regarding a primary path for a split bearer and a second AID regarding a secondary path for said split bearer; An operation to obtain first wireless quality information regarding the basic path based on the first AID above; An operation to obtain second wireless quality information regarding the auxiliary path based on the second AID above; An operation to identify that the size of the data to be transmitted using the above split bearer is smaller than the reference size for transmission through a single path; An operation to determine the path to transmit the data as the auxiliary path based on the first wireless quality information and the second wireless quality information; and The operation of transmitting the data having a size smaller than the reference size to the terminal using the above auxiliary path, method.

12. In claim 11, the above method is, An operation to identify the state of the basic path as one of a first state and a second state based on the first wireless quality information; and Based on the second wireless quality information, the operation of identifying the state of the auxiliary path as one of the first state and the second state, method.

13. In claim 12, the above method is, An operation to identify that the state of the above basic path is the above second state and the state of the above auxiliary path is the above first state; and Based on the state of the basic path, which is the second state, and the state of the auxiliary path, which is the first state, the path to transmit the data is determined as the auxiliary path, comprising an operation to determine the path to transmit the data as the auxiliary path. method.

14. In claim 13, the above method is, An operation to set the state regarding the basic path to the first state based on identifying that the first value according to the first wireless quality information exceeds the first reference quality value; An operation to set the state regarding the basic path to the second state based on identifying that the first value according to the first wireless quality information is less than the second reference quality value; and Based on identifying that the first value according to the first wireless quality information is less than or equal to the first reference quality value and that the first value according to the first wireless quality information is greater than or equal to the second reference quality value, the operation of setting to maintain the state regarding the basic path. method.

15. A non-transient computer-readable storage medium storing one or more programs, wherein the one or more programs, when executed individually or collectively by at least one processor of a communication device including the transceiver, Obtaining a first AID (assistance information data) regarding a primary path for a split bearer and a second AID regarding a secondary path for said split bearer, Based on the above first AID, first wireless quality information regarding the above basic path is obtained, and Based on the above second AID, second wireless quality information regarding the above auxiliary path is obtained, and Identify that the size of the data to be transmitted using the above split bearer is smaller than the reference size for transmission through a single path, and Based on the above first wireless quality information and the above second wireless quality information, the path to transmit the data is determined as the auxiliary path, and Instructions that cause the communication device to transmit the data having a size smaller than the reference size to the terminal using the above auxiliary path, Non-transient computer-readable storage media.

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