WO2025187957A1 - Apparatus, method, and storage medium for transmitting downlink packets using split bearer in wireless communication system - Google Patents

Abstract

This base station having a packet data convergence protocol (PDCP) for a split bearer may comprise: at least one processor; and a memory storing instructions. The instructions, when executed individually or collectively by the at least one processor, may instruct the base station to: acquire a first desired buffer size for the data radio bearer (DBS) of a first path for the split bearer and a second DBS of a second path for the split bearer; transmit, to a terminal, sequential first downlink packets corresponding to a reference number via the first path selected on the basis of the first DBS and the second DBS; and after transmitting the sequential first downlink packets, transmit, to the terminal, sequential second downlink packets corresponding to the reference number via a path selected, from among the first path and the second path, on the basis of the remaining DBS of the first DBS and the second DBS.

Description

Device, method, and storage medium for transmitting downlink packets using a split bearer in a wireless communication system

The following descriptions relate to a wireless communication system, and more specifically, to a device, method, and storage medium for transmitting a downlink packet using a split bearer in a wireless communication system.

In wireless communication systems, a split bearer may be utilized for dual connectivity. For example, the split bearer may be applied to a radio bearer. For example, the radio bearer may include a bearer between a base station and a terminal.

The above information may be provided as background art to aid in understanding the present disclosure. No claim or determination is made as to whether any of the above is applicable as prior art related to the present disclosure.

A base station having a packet data convergence protocol (PDCP) for a split bearer may include at least one processor including a processing circuit. The base station may include a memory including one or more storage media storing instructions. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to obtain a first desired buffer size for the data radio bearer (DBS) of a first path for the split bearer and a second DBS of a second path for the split bearer. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to transmit, to a terminal, a first consecutive downlink packet corresponding to a reference number through the first path selected based on the first DBS and the second DBS. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to transmit, to the terminal, consecutive second downlink packets corresponding to the reference number through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path, after transmitting the consecutive first downlink packets.

A method performed by a base station having a packet data convergence protocol (PDCP) for a split bearer may include an operation of obtaining a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer and a second DBS of a second path for the split bearer. The method may include an operation of transmitting, to a terminal, consecutive first downlink packets corresponding to a reference number through a first path selected based on the first DBS and the second DBS. The method may include an operation of transmitting, after transmitting the consecutive first downlink packets, consecutive second downlink packets corresponding to the reference number through a path selected based on a remaining DBS of the first DBS and the second DBS among the first path and the second path.

A non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by at least one processor of a base station having a packet data convergence protocol (PDCP) for a split bearer, cause the base station to obtain a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer and a second DBS of a second path for the split bearer. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the base station to transmit, to a terminal, consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the terminal to transmit, to the terminal, consecutive second downlink packets corresponding to the reference number, through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path, after transmitting the consecutive first downlink packets.

A device of a central unit (CU) having a packet data convergence protocol (PDCP) for a split bearer may include at least one processor including a processing circuit. The device may include a memory including one or more storage media storing instructions. The instructions, when individually or collectively executed by the at least one processor, may cause the device to receive a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer from a distributed unit (DU) connected to the CU. The instructions, when individually or collectively executed by the at least one processor, may cause the device to receive a second DBS of a second path for the split bearer from a node connected to the CU. The instructions, when individually or collectively executed by the at least one processor, may cause the device to transmit, to a terminal, consecutive first downlink packets corresponding to a reference number via the first path selected based on the first DBS and the second DBS. The instructions, when individually or collectively executed by the at least one processor, may cause the device to, after transmitting the consecutive first downlink packets, transmit, to the terminal, consecutive second downlink packets corresponding to the reference number via a path selected based on the remaining DBSs of the first DBS and the second DBS among the first path and the second path.

A method performed by a central unit (CU) having a packet data convergence protocol (PDCP) for a split bearer may include receiving a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer from a distributed unit (DU) connected to the CU. The method may include receiving a second DBS of a second path for the split bearer from a node connected to the CU. The method may include transmitting, to a terminal, consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS. The method may include an operation of transmitting, to the terminal, consecutive second downlink packets corresponding to the reference number through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path, after transmitting the consecutive first downlink packets.

A non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by at least one processor of a central unit (CU) having a packet data convergence protocol (PDCP) for a split bearer, cause the CU to receive a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer from a distributed unit (DU) connected to the CU. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the CU to receive a second DBS of a second path for the split bearer from a node connected to the CU. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the terminal to transmit, to the terminal, consecutive first downlink packets corresponding to a reference number, through the first path selected based on the first DBS and the second DBS. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the terminal to transmit, after transmitting the consecutive first downlink packets, consecutive second downlink packets corresponding to the reference number, through a path selected based on the remaining DBSs of the first DBS and the second DBS among the first path and the second path.

Figure 1 illustrates an example of a wireless communication system.

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

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

Figures 3a and 3b illustrate examples of dual connectivity in a wireless communication system.

Figure 4 illustrates an example of a functional configuration of an electronic device.

Figures 5a and 5b illustrate examples of how a base station transmits a downlink packet received from an entity of a core network to a terminal using a split bearer.

FIG. 6a illustrates an example of an operational flow for a method of transmitting consecutive downlink packets corresponding to a reference number through paths for a split bearer.

Figure 6b illustrates examples of how to transmit downlink packets over paths for a split bearer.

Figure 7 illustrates an example of an operational flow for a method of changing the number of continuously transmitted packets as DDDS (downlink data delivery status) is obtained.

Figures 8 and 9 illustrate examples of graphs of the performance of a terminal receiving downlink packets through paths for a split bearer.

Figure 10 illustrates an example of an operational flow for a method in which a base station transmits consecutive downlink packets corresponding to a reference number through paths for a split bearer.

The terms used in this disclosure are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this disclosure. Terms defined in general dictionaries among the terms used in this disclosure may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this disclosure. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude embodiments of the present disclosure.

The various embodiments of the present disclosure described below illustrate a hardware-based approach as an example. However, since the various embodiments of the present disclosure include techniques utilizing both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

In the following description, terms referring to signals (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 operational 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 (distributed unit (DU), radio unit (RU), central unit (CU), 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 Terms such as CU), O-CU-UP (O-RAN CU-CP), O-CU-CP (O-RAN CU-CP)), and components of the device are provided for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. In addition, terms such as '...part', '...machine', '...object', and '...body' used below may mean at least one shape structure or a unit that processes a function.

In addition, in the present disclosure, expressions such as "more than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled, but this is merely a description for expressing an example and does not exclude descriptions such as "more than" or "less than." A condition described as "more than" may be replaced with "more than," a condition described as "less than" may be replaced with "less than," and a condition described as "more than and less than" may be replaced with "more than and less than." In addition, hereinafter, "A" to "B" mean at least one of elements from A (including A) to B (including B). hereinafter, "C" and/or "D" mean at least one of "C" or "D," that is, including {"C", "D", "C" and "D"}.

Although this disclosure describes embodiments using terminology used in certain communication standards (e.g., 3rd Generation Partnership Project (3GPP)), this is merely an example for illustrative purposes. Embodiments of this disclosure can also be applied to other communication and broadcasting systems.

Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

In addition, standardization of wireless interface architecture/protocols is in progress for technologies such as intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) that simplifies random access procedures. Standardization is also in progress for system architecture/services such as 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal.

Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

While a 5G environment is described below as an example, this description does not limit the scope of the communication environment of the embodiments of the present disclosure. The technical principles according to the embodiments of the present disclosure can also be applied to 4G, 6G, and post-6G communication technologies and network environments.

Figure 1 illustrates an example of a wireless communication system.

Referring to FIG. 1, FIG. 1 illustrates a base station (110) and a terminal (120) as some of the nodes utilizing a wireless channel in a wireless communication system. Although FIG. 1 illustrates only one base station, the wireless communication system may further include other base stations identical or similar to the base station (110).

The base station (110) is a network infrastructure that provides wireless access to the terminal (120). The base station (110) has coverage defined based on the distance at which a signal can be transmitted. In addition to the base station, the base station (110) may be referred to as an 'access point (AP)', 'eNodeB (eNB)', '5th generation node', 'next generation nodeB (gNB)', 'wireless point', 'transmission/reception point (TRP)', or other terms having equivalent technical meanings.

The terminal (120) is a device used by a user and communicates with the 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). In addition, although not shown in FIG. 1, the terminal (120) and another terminal may 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 the involvement of a user. In 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 an NB (narrowband)-IoT (internet of things) device.

The terminal (120) may be referred to as a terminal, or other terms such 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 equivalent technical meanings.

The base station (110) and the terminal (120) can perform beamforming. 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). In addition, 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), 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, the beamforming can include transmission beamforming and reception beamforming. The base station (110) and the terminal (120) can impart directionality to the transmitted or 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 resources that have a QCL relationship with the resource that transmitted the serving beams.

The terminal (120) may be configured with cells of the base station (110) and carrier aggregation (CA). CA technology is a technology that increases the frequency usage efficiency of the terminal (120) and the base station (110) by connecting the terminal to a group of homogeneous wireless communication cells having a common radio resource control entity, and simultaneously using frequency resources on component carriers of each cell located in different frequency bands for signal transmission and reception. The cells configured for CA may include one PCell (primary cell) and one or more SCells (secondary cells).

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

Referring to FIG. 2A, in an NR communication system, a wireless protocol of a control plane of a terminal (120) (e.g., UE) may include PHY (211), MAC (212), RLC (213), PDCP (214), and RRC (215). In an NR communication system, a wireless protocol of a control plane of a base station (110) (e.g., gNB) may include PHY (221), MAC (222), RLC (223), PDCP (224), and RRC (225).

The main functions of RRC (215, 225) may include some of the following functions.

- Broadcast of system information related to AS (Access Stratum) and NAS (Non Access Stratum)

- Paging initiated by 5GC or NG-RAN

- Establishment, maintenance and release of RRC connection between UE and NG-RAN including:

1) Adding, modifying, and releasing carrier aggregation

2) Add, modify and remove Dual Connectivity within NR or between E-UTRA and NR.

- Security functions including key management

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

- Mobility features including:

1) Handover and context transfer

2) UE cell selection and reselection and control of cell selection and reselection

3) Inter-RAT mobility

- QoS (Quality of Service) management function

- UE measurement reporting and reporting control;

- Detection of and recovery from radio link failure

- Transmitting NAS messages from/to the UE to/from the NAS.

The main functions of PDCP (214, 224) may include some of the following functions:

- Header compression and decompression (ROHC only)

- User data transfer function

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- PDCP PDU reordering for reception

- Duplicate detection of lower layer SDUs

- Retransmission function (Retransmission of PDCP SDUs)

- Encryption and decryption functions (Ciphering and deciphering)

- Timer-based SDU discard in uplink.

In the above, the reordering function of the PDCP layer may refer to the function of reordering PDCP PDUs received from the lower layer in order based on the PDCP SN (sequence number). The reordering function of the PDCP layer may include the function of transmitting data to the upper layer in the reordered order, the function of transmitting data directly without considering the order, the function of recording lost PDCP PDUs by reordering the order, the function of reporting the status of lost PDCP PDUs to the transmitting side, and the function of requesting retransmission of lost PDCP PDUs.

The main functions of RLC (213, 223) may include some of the following functions:

- Data transfer function (Transfer of upper layer PDUs)

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- ARQ function (Error Correction through ARQ)

- Concatenation, segmentation and reassembly of RLC SDUs

- Re-segmentation of RLC data PDUs

- Reordering of RLC data PDUs

- Duplicate detection function

- Protocol error detection

- RLC SDU discard function

- RLC re-establishment function

In the above, the in-sequence delivery function of the RLC layer may refer to the function of sequentially delivering RLC SDUs received from lower layers to upper layers. If a single RLC SDU is originally received divided into multiple RLC SDUs, the in-sequence delivery function of the RLC layer may include the function of reassembling and delivering them.

The in-sequence delivery function of the RLC layer may include a function to reorder received RLC PDUs based on the RLC SN (sequence number) or PDCP SN (sequence number), a function to record lost RLC PDUs by reordering them, a function to report status of lost RLC PDUs to the transmitter, and a function to request retransmission of lost RLC PDUs.

The in-sequence delivery function of the RLC layer may include a function to sequentially deliver to the upper layer only the RLC SDUs up to the lost RLC SDU when there is a lost RLC SDU. In addition, the in-sequence delivery function of the RLC layer may include a function to sequentially deliver to the upper layer all RLC SDUs received before the timer starts if a predetermined timer has expired even if there is a lost RLC SDU. In addition, the in-sequence delivery function of the RLC layer may include a function to sequentially deliver to the upper layer all RLC SDUs received up to the present if a predetermined timer has expired even if there is a lost RLC SDU.

The RLC layer can process RLC PDUs in the order they are received (out-of-sequence delivery) and deliver them to the PDCP (405, 440) device, regardless of the order of the sequence number.

When the RLC layer receives a segment, it can receive segments that are stored in a buffer or will be received later, reconstruct them into a complete RLC PDU, and then transmit them to the PDCP device.

The RLC layer may not include concatenation functionality, and the function may be performed by the MAC layer or replaced by the multiplexing functionality of the MAC layer.

In the above, the out-of-sequence delivery function of the RLC layer may refer to the function of directly delivering RLC SDUs received from a lower layer to an upper layer regardless of the order. The out-of-sequence delivery function of the RLC layer may include the function of reassembling and delivering multiple RLC SDUs when an original RLC SDU is received fragmented into multiple RLC SDUs. The out-of-sequence delivery function of the RLC layer may include the function of storing and arranging the RLC SN or PDCP SN of the received RLC PDUs to record any lost RLC PDUs.

MAC (212, 222) can be connected to multiple RLC layer layers configured in one terminal, and the main functions of MAC can include some of the following functions.

- Mapping function (Mapping between logical channels and transport channels)

- Multiplexing/demultiplexing of MAC SDUs

- Scheduling information reporting function

- HARQ function (Error correction through HARQ)

- Priority handling between logical channels of one UE

- Priority handling between UEs by means of dynamic scheduling

- MBMS service identification function

- Transport format selection function

- Padding function

The PHY layer (211, 221) can perform operations of channel coding and modulating upper layer data, converting it into OFDM symbols and transmitting it through a wireless channel, or demodulating and channel decoding OFDM symbols received through a wireless channel and transmitting them to a higher layer.

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

Referring to FIG. 2b, the wireless protocol of the user plane of the terminal (120) (e.g., UE) may include PHY (261), MAC (262), RLC (263), PDCP (264), and SDAP (265). In an NR communication system, the wireless protocol of the user plane of the base station (110) (e.g., gNB) may include PHY (271), MAC (272), RLC (273), PDCP (274), and SDAP (275).

The main functions of SDAP (265, 275) may include some of the following functions:

- Transfer of user plane data

- Mapping function between QoS flow and data bearer for both DL and UL

- QoS flow ID marking function for uplink and downlink (marking QoS flow ID in both DL and UL packets)

- Ability to map reflective QoS flow to data bearer for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

For the SDAP layer, the terminal (120) can be configured by a Radio Resource Control (RRC) message for each PDCP layer, each bearer, or each logical channel to use the header of the SDAP layer or to use the function of the SDAP layer. When the SDAP header is configured, the terminal (120) can instruct the terminal (120) to update or reset the mapping information for the QoS flow and data bearer of the uplink and downlink using a 1-bit indicator (NAS reflective QoS) for reflecting the Non-Access Stratum (NAS) Quality of Service (QoS) of the SDAP header and a 1-bit indicator (AS reflective QoS) for reflecting the Access Stratum (AS) QoS. The SDAP header can include QoS flow ID information indicating QoS. The QoS information can be used as data processing priority, scheduling information, etc. to support a smooth service.

For PDCP (264, 274) in the user plane, reference may be made to the description of PDCP (214, 224) in the control plane. For RLC (263, 273) in the user plane, reference may be made to the description of RLC (213, 223) in the control plane. For MAC (262, 272) in the user plane, reference may be made to the description of MAC (212, 222) in the control plane. For PHY (261, 271) in the user plane, reference may be made to the description of PHY (211, 221) in the control plane.

Referring to FIGS. 2A and 2B , a wireless protocol of an NR communication system in a radio access network is described as an example; however, embodiments of the present disclosure are not limited thereto. For example, the descriptions of FIGS. 2A and 2B can be applied to other communication systems (e.g., an LTE communication system or a 6G communication system).

In FIGS. 2A and 2B, protocol stacks of the base station (110) are illustrated, but the present disclosure is not limited thereto. For example, the base station (110) may be implemented with a central unit (CU) (or a control unit (CU)) and a distributed unit (DU). For example, the CU may include an upper layer, and the DU may include a lower layer. For example, the upper layer of the CU may include RRC and PDCP in the control plane, and SDAP and PDCP in the user plane. For example, the lower layer of the DU may include RLC, MAC, and an upper PHY. The above examples are merely examples for convenience of description, and the present disclosure is not limited thereto.

Figures 3a and 3b illustrate examples of dual connectivity in a wireless communication system.

FIG. 3A illustrates an example (300) of dual connectivity (DC) between a terminal (120) and multiple base stations (110-1, 110-2). Referring to example (300), the terminal (120) can be configured in dual connectivity using a first base station (110-1) and a second base station (110-2). DC technology is a technology that increases frequency utilization efficiency by allowing a terminal to simultaneously connect to two independent heterogeneous or homogeneous wireless communication cell groups having separate radio resource control entities, and to use frequency resources on component carriers of cells within each cell group located in different frequency bands for signal transmission and reception. For example, a terminal (120) may be connected to two different radio resource entities (e.g., a first base station (110-1), a second base station (110-2)) and may utilize radio resources allocated by each radio resource entity. In MR-DC (multi-radio DC), a UE (e.g., terminal (120)) in a radio resource control (RRC) connected state (i.e., RRC_CONNECTED) may be configured to utilize radio resources provided by two independent schedulers. Each scheduler may be located in an NG-RAN node (e.g., a first base station (110-1), a second base station (110-2)). Here, one node is a master node (MN) and the other node is 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. The SN may or may not be connected to the core network.

The MN may provide a master cell group (MCG). The MN, in addition to the MN, may be referred to as an M-NODE or an M-NG-RAN node. The MCG may include one or more cells. The MCG may include a PCell (primary cell). The MCG may include multiple aggregated cells. The MCG may include a PCell and one or more secondary cells (SCells). The SN may provide a secondary cell group (SCG). The SN, in addition to the SN, may be referred to as an S-NODE or an S-NG-RAN node. The SCG may include one or more cells. The SCG may include multiple aggregated cells. Like the MCG, the SCG may include a PCell and/or an SCell. A cell functioning as a PCell within the SCG may be referred to as a PSCell (primary secondary cell). The secondary cell group may include a PSCell and one or more SCells. Hereinafter, the term "SpCell" (special cell) may be used to encompass PCell and PSCell. "SpCell" refers to the primary cell of an MCG or SCG. In other words, an MCG SpCell refers to a PCell, and an SCG SpCell refers to an SCell.

The possible types of DC can be defined as follows:

1) EN-DC: Dual connectivity in which the eNB is connected to the evolved packet core (EPC), and the UE is connected to the eNB acting as an MN and the gNB acting as an SN. Here, the gNB may be referred to as an en-gNB, and the en-gNB may or may not be connected to the EPC.

2) NGEN-DC: Dual connectivity in which the eNB is connected to the 5GC (5G core), and the terminal is connected to the eNB operating as an MN and the gNB operating as an SN. Here, the eNB may be referred to as ng-eNB.

3) NE-DC: Dual connectivity in which the gNB is connected to the 5GC, and the terminal is connected to the gNB operating as an MN and the eNB operating as an SN. Here, the eNB may be referred to as ng-eNB.

4) NR-DC: Dual connectivity where gNBs are connected to 5GC, and the UE is connected to a gNB that acts as an MN and a gNB that acts as an SN. NR-DC can also be used when a UE is connected to a single gNB that acts as both an MN and SN and configures both an MCG and an SCG.

The terminal (120) can support MR-DC. The terminal (120) can be connected to a first base station (110-1) and a second base station (110-2). The first base station (110-1) is an MN, and the second base station (110-2) is an SN, and can be connected to the terminal. DC technology can provide higher data rates. The first base station (110-1) and the second base station (110-2), as MN and SN, respectively, can transmit downlink traffic to the terminal (120) or receive uplink traffic from the terminal (120).

FIG. 3B illustrates an example (350) of dual connectivity between a terminal (120), multiple DUs (371, 372), and a CU (360). Referring to example (350), a base station (e.g., base station (110), a first base station (110-1), a second base station (110-2)) may be divided into CUs and DUs. Unlike multiple independent base stations (e.g., the first base station (110-1), the second base station (110-2)) that serve the terminal (120), one CU and multiple DUs may serve the terminal (120). For example, the CU (360) may be connected to DU #1 (371) and DU #2 (372). The CU (360) may be connected to each of DU #1 (371) and DU #2 (372) via an F1 interface. DU #1 (371) can provide one or more cells. For example, the one or more cells provided by DU #1 (371) can be referred to as MCG (or SCG). DU #2 (372) can provide one or more cells. For example, the one or more cells provided by DU #2 (372) can be referred to as SCG (or MCG). From the terminal (120) side, CU (360) and DU #1 (371) can operate as logical nodes (e.g., gNB) corresponding to one base station, and DU #2 (372) can operate as logical nodes (e.g., gNB) corresponding to another base station.

A cell can refer to an area (or coverage) that can be covered by one base station (e.g., gNB) (or one DU (distributed unit) (or DU (digital unit))). A cell can represent not only a geographical area but also an area that occupies a specific spectrum in the frequency domain. A DU (distributed unit) can cover one cell or multiple cells. Here, multiple cells can be distinguished by the frequency they support and the area of the sector they cover. A serving cell is a cell that provides terminals and upper layer signaling (e.g., RRC (radio resource control) signaling), and can refer to one cell or multiple cells.

In the present disclosure, a base station (e.g., a base station (110), a first base station (110-1), a second base station (110-2)) may be implemented in a distributed deployment according to a central unit (CU) (or a control unit (CU)) configured to perform functions of upper layers of an access network and a distributed unit (DU) configured to perform functions of lower layers. The CU and the DU may represent independent network entities (or may be referred to as network nodes, network equipment, or network devices) for an access network. The CU may be connected to one or more DUs and may be responsible for functions of a higher layer than the DU (e.g., a packet data convergence protocol (PDCP) protocol, a radio resource control (RRC) protocol). The DU may be responsible for functions of lower layers (e.g., a radio link control (RLC) layer, a medium access control (MAC) layer, and a physical (PHY) layer). Hereinafter, the operations of the CU and the DU are described, but the implementation method according to the embodiments of the present disclosure is not limited thereto. As a non-limiting example, the DU is connected to the RU (radio unit), the DU may perform some functions (high PHY) of the RLC (radio link control), MAC (media access control), and PHY (physical) layers, and the RU may be responsible for the remaining functions (low PHY) of the PHY layer.

Figure 4 illustrates an example of a functional configuration of an electronic device.

The configuration of the electronic device (400) illustrated in FIG. 4 can be understood as the configuration of the base station (110) of FIG. 1, the terminal (120) of FIG. 1, the base station (110-1 or 110-2) of FIG. 3A, the CU (360) of FIG. 3B, or the DU (371 or 372) of FIG. 3B. Terms such as "...unit" and "...unit" used hereinafter mean a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software.

Referring to FIG. 4, the electronic device (400) may include a transceiver (410), a memory (420), and a processor (430). However, the present disclosure is not limited thereto. For example, the electronic device (400) may not include at least some of the components illustrated in FIG. 4, or may further include components not illustrated in FIG. 4.

The transceiver (410) can perform functions for transmitting and receiving signals in a wired communication environment. The transceiver (410) can include a wired interface for controlling direct connections between devices via a transmission medium (e.g., copper wire, optical fiber). For example, the transceiver (410) can transmit electrical signals to other devices via copper wire, or perform conversion between electrical signals and optical signals.

The transceiver (410) may perform functions for transmitting and receiving signals in a wireless communication environment. For example, the transceiver (410) may perform a conversion function between baseband signals and bit streams according to the physical layer specifications of the system. For example, when transmitting data, the transceiver (410) generates complex-valued symbols by encoding and modulating the transmitted bit stream. Furthermore, when receiving data, the transceiver (410) restores the received bit stream by demodulating and decoding the baseband signal. Furthermore, the transceiver (410) may include multiple transmission and reception paths.

The transceiver (410) transmits and receives signals as described above. Accordingly, all or part of the transceiver (410) may be referred to as a "communication unit," a "transmitter," a "receiver," or a "transmitter-receiver unit." Furthermore, in the following description, transmission and reception performed via a wireless channel are used to mean that the transceiver (410) performs the processing described above.

Although not shown in FIG. 4, the transceiver (410) may further include a backhaul transceiver for connection to the core network or other base stations. The backhaul transceiver provides an interface for communicating with other nodes within the network. For example, the backhaul transceiver may be used for communicating with entities (or nodes) of the core network. That is, the backhaul transceiver converts a bit stream transmitted from the base station to another node, such as another access node, another base station, an upper node, the core network, etc., into a physical signal, and converts a physical signal received from another node into a bit stream.

The memory (420) stores data such as basic programs, application programs, and setting information for the operation of the electronic device (400). The memory (420) may be referred to as a storage unit. The memory (420) may be composed of volatile memory, nonvolatile memory, or a combination of volatile memory and nonvolatile memory. In addition, the memory (420) provides stored data upon request from the processor (430).

For example, the processor (430) may include various processing circuits and/or multiple processors. For example, the term "processor" as used herein, including in the claims, may include various processing circuits including at least one processor, one or more of which may be configured to individually and/or collectively perform the various functions described below in a distributed manner. As used herein, when "processor," "at least one processor," and "one or more processors" are described as being configured to perform various functions, these terms encompass, for example, and without limitation, situations where one processor performs some of the recited functions and other processor(s) perform other parts of the recited functions, and also situations where one processor may perform all of the recited functions. Additionally, the at least one processor may include a combination of processors that perform the various functions enumerated/disclosed, for example, in a distributed manner. At least one processor may execute program instructions to achieve or perform the various functions.

The processor (430) controls the overall operations of the electronic device (400). The processor (480) may be referred to as a control unit. For example, the processor (430) transmits and receives signals via the transceiver (410) (or via a backhaul communication unit). In addition, the processor (430) records and reads data from the memory (420). In addition, the processor (430) may perform functions of a protocol stack required by a communication standard. Although only the processor (430) is illustrated in FIG. 4, the electronic device (400) may include two or more processors according to other implementation examples.

The configuration of the electronic device (400) illustrated in FIG. 4 is merely an example, and examples of electronic devices (400) that perform embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 4. In some embodiments, some configurations may be added, deleted, or changed.

In a wireless communication system, a split bearer may be used for DC. For example, the split bearer may be applied to a radio bearer in the user plane. For example, the radio bearer may be referred to as an E-UTRAN radio access bearer (E-RAB), a data radio bearer, or an access network resource. For example, the data stream segmentation (or routing) for the split bearer may be performed in the PDCP layer (e.g., PDCP (274) in FIG. 2b). For example, the PDCP layer may be connected to the RLC layers (e.g., RLC (273) in FIG. 2b) of multiple nodes (e.g., base station (110-1) and base station (110-2), or DU #1 (371) and DU #2 (372)). The data path (or paths) of the split bearer may include layers of a protocol stack. For specific details on the path along which downlink packets are provided, reference may be made to the examples of FIGS. 5a and 5b below.

Figures 5a and 5b illustrate examples of how a base station transmits a downlink packet received from an entity of a core network to a terminal using a split bearer.

FIG. 5A illustrates an example (500) of a base station (510) connected to an evolved packet core (EPC). Referring to example (500), the base station (510) and a node (520) may be configured to provide DC (e.g., EN-DC) to a terminal (540). In example (500), the base station (510) may be a gNB, and the node (520) may be an eNB. However, the present disclosure is not limited thereto. For example, the base station (510) may be implemented as a CU and a DU. The base station (510) may be connected to a serving-gateway (S-GW) (530), which is an entity of the EPC. For example, the S-GW (530) may be an entity (or node) that provides packets (or data) to the base station (510) in the user plane. The base station (510) (or CU) of FIG. 5a may be included in the electronic device (400) of FIG. 4.

For example, the base station (510) may include NR PDCP (or PDCP, PDCP layer) (511), NR RLC (or RLC, RLC layer) (512), and NR MAC (or MAC, MAC layer). In the example (500), the base station (510) is illustrated as including NR PDCP (511), NR RLC (512), and NR MAC, but this is merely an example for convenience of description, and the present disclosure is not limited thereto. For example, the base station (510) may further include at least one of NR PHY, NR SDAP, or NR RRC. For specific details regarding the NR PDCP (511), reference may be made to the description of PDCP (274) in FIG. 2B. For specific details regarding the NR RLC (512), reference may be made to the description of RLC (273) in FIG. 2B. For specific details on NR MAC, reference may be made to the description of MAC (272) in FIG. 2b.

For example, node (520) may include EUTRA RLC (or RLC, RLC layer) (522) and EUTRA MAC (or MAC, MAC layer). In example (500), node (520) is illustrated as including EUTRA RLC (522) and EUTRA MAC, but this is merely an example for convenience of description, and the present disclosure is not limited thereto. For example, node (520) may further include at least one of EUTRA PHY, EUTRA PDCP, EUTRA SDAP, or EUTRA RRC. For specific details regarding EUTRA RLC (522), reference may be made to the description of RLC (273) in FIG. 2B. For specific details regarding EUTRA MAC, reference may be made to the description of MAC (272) in FIG. 2B.

Referring to example (500), in order to support split bearer, NR PDCP (511) of base station (510) can be connected to NR RLC (512) of base station (510) and EUTRA RLC (522) of node (520). Base station (510) can perform packet distribution for split bearer using DDDS (downlink data delivery status) obtained from each of NR RLC (512) and EUTRA RLC (522). For example, NR PDCP (511) of base station (510) can obtain first DDDS from corresponding node NR RLC (512). For example, NR PDCP (511) of base station (510) can obtain second DDDS from corresponding node EUTRA RLC (522). For example, the DDDS may include a DBS (desired buffer size for the data radio bearer) indicating the size of the data. For example, the DDDS may be transmitted from the RLC to the PDCP via the uplink path (502). For example, the DBS may indicate a buffer size for the radio bearer. For example, the DBS may indicate the number of packets according to the buffer size. For example, the base station (510) (or NR PDCP (511)) may perform distribution for downlink packets received from the S-GW (530) based on the first DBS of the first DDDS and the second DBS of the second DDDS. At this time, the distribution for the downlink packets may include selection of a path.

For example, the path may be referred to as a downlink path (501). For example, the downlink path (501) may include paths (501-1, 501-2) for a split bearer. For example, each of the paths (501-1, 501-2) for a split bearer may be used to transmit (or forward) downlink packets. For example, the first path (501-1) may include NR-PDCP (511), NR RLC (512), NR MAC of the base station (510), NR MAC of the terminal (540), NR RLC of the terminal (540), and NR PDCP (541). For example, the second path (501-2) may include NR-PDCP (511), EUTRA RLC (522), EUTRA MAC of node (520), EUTRA MAC of terminal (540), EUTRA RLC of terminal (540), and NR PDCP (541). In other words, terminal (540) may include EUTRA MAC, EUTRA RLC, NR MAC, NR RLC, and NR PDCP (541) to support split bearer.

For example, the first path (501-1) may be associated with a group of cells provided by the base station (510). For example, if the base station (510) is composed of a CU and a DU, the first path (501-1) may be associated with a group of cells provided by the DU. For example, the group of cells associated with the first path (501-1) may include an SCG. For example, the second path (501-2) may be associated with a group of cells provided by the node (520). For example, the group of cells associated with the second path (501-2) may include an MCG.

For example, when using a split bearer, the base station (510) (or NR PDCP (511)) can provide a downlink packet to an RLC (NR RLC (512) or EUTRA RLC (522)). At this time, the downlink packet provided from the NR PDCP (511) to the NR RLC (512) (or EUTRA RLC (522)) can include a PDCP data PDU (protocol data unit). At this time, the header of the PDCP data PDU can include a PDCP SN (sequence number). The terminal (540) (or NR PDCP (541)) can reorder the downlink packet provided through the paths (501-1, 501-2) for the split bearer. For example, the terminal (540) (or NR PDCP (541)) can sort the order of downlink packets using the PDCP SN included in the received downlink packet.

In FIG. 5A, an example (500) of a user plane of a base station (510), a node (520), and a terminal (540) is illustrated, but the present disclosure is not limited thereto. For example, the base station (510), the node (520), and the terminal (540) may establish a connection in the control plane for DC. For example, an upper layer (e.g., RRC) of the node (520) may be connected to an entity of the EPC.

Also, in FIG. 5A, an example (500) is illustrated in which a single base station (510) includes multiple layers (NR PDCP (511), NR RLC (512), and NR MAC), but the present disclosure is not limited thereto. For example, the base station (510) may be composed of a CU (or gNB-CU) and a DU (or gNB-DU). For example, the CU may include NR PDCP (511). For example, the DU may include NR RLC (512) and NR MAC. For example, a DC (e.g., EN-DC) using the split bearer may be provided between the base station (510) having NR PDCP (511) and a node (520) which is an eNB. Alternatively, for example, a DC (e.g., EN-DC) using the split bearer may be provided between a node (520) that is a DU and an eNB connected to a CU having NR PDCP (511).

FIG. 5B illustrates an example (550) of a base station (560) connected to a 5th generation core (5GC). Referring to example (550), the base station (560) and the node (570) may be configured to provide DC (e.g., NR-DC) to the terminal (590). In example (550), the base station (560) may be a gNB, and the node (570) may be a gNB. However, the present disclosure is not limited thereto. For example, the base station (560) and/or the node (570) may be implemented as a CU and a DU. The base station (560) may be connected to a user plane function (UPF) (580), which is an entity of the 5GC. For example, the UPF (580) may be an entity (or node) that provides packets (or data) to the base station (560) in the user plane. The base station (560) (or CU) of FIG. 5b may be included in the electronic device (400) of FIG. 4.

For example, the base station (560) may include NR PDCP (or PDCP, PDCP layer) (561), NR RLC (or RLC, RLC layer) (562), and NR MAC (or MAC, MAC layer). In the example (550), the base station (560) is illustrated as including NR PDCP (561), NR RLC (562), and NR MAC, but this is merely an example for convenience of description, and the present disclosure is not limited thereto. For example, the base station (560) may further include at least one of NR PHY, NR SDAP, or NR RRC. For specific details regarding the NR PDCP (561), reference may be made to the description of PDCP (274) in FIG. 2B. For specific details regarding the NR RLC (562), reference may be made to the description of RLC (273) in FIG. 2B. For specific details on NR MAC, reference may be made to the description of MAC (272) in FIG. 2b.

For example, the node (570) may include an NR RLC (or RLC, RLC layer) (572) and an NR MAC (or MAC, MAC layer). In the example (550), the node (570) is illustrated as including an NR PDCP (561), an NR RLC (562), and an NR MAC, but this is merely an example for convenience of description, and the present disclosure is not limited thereto. For example, the node (570) may further include at least one of an NR PDCP, an NR PHY, an NR SDAP, or an NR RRC. For specific details regarding the NR RLC (572), reference may be made to the description of the RLC (273) in FIG. 2B. For specific details regarding the NR MAC, reference may be made to the description of the MAC (272) in FIG. 2B.

Referring to example (550), in order to support split bearer, NR PDCP (561) of base station (560) can be connected to NR RLC (562) of base station (560) and NR RLC (572) of node (570). Base station (560) can perform packet distribution for split bearer using DDDS (downlink data delivery status) obtained from each of NR RLC (562) and NR RLC (572). For example, NR PDCP (561) of base station (560) can obtain first DDDS from corresponding node NR RLC (572). For example, NR PDCP (561) of base station (560) can obtain second DDDS from corresponding node NR RLC (572). For example, the DDDS may include a DBS (desired buffer size for the data radio bearer) indicating the size of the data. For example, the DDDS may be transmitted from the RLC to the PDCP via the uplink path (552). For example, the DBS may indicate a buffer size for the radio bearer. For example, the DBS may indicate the number of packets according to the buffer size. For example, the base station (560) (or NR PDCP (561)) may perform distribution for downlink packets received from the UPF (580) based on the first DBS of the first DDDS and the second DBS of the second DDDS. At this time, the distribution for the downlink packets may include selection of a path.

For example, the path may be referred to as a downlink path (551). For example, the downlink path (551) may include paths (551-1, 551-2) for a split bearer. For example, each of the paths (551-1, 551-2) for a split bearer may be used to transmit (or forward) downlink packets. For example, the first path (551-1) may include NR-PDCP (561), NR RLC (562), NR MAC of the base station (560), NR MAC of the terminal (590), NR RLC of the terminal (590), and NR PDCP (591). For example, the second path (551-2) may include NR-PDCP (561), NR RLC (572), NR MAC of node (570), NR MAC of terminal (590), NR RLC of terminal (590), and NR PDCP (591). In other words, terminal (590) may include multiple NR MACs, multiple NR RLCs, and NR PDCP (591) to support split bearer.

For example, the first path (551-1) may be associated with a group of cells provided by the base station (560). For example, if the base station (560) is composed of a CU and a DU, the first path (551-1) may be associated with a group of cells provided by the DU. For example, the group of cells associated with the first path (551-1) may include an SCG. For example, the second path (551-2) may be associated with a group of cells provided by the node (570). For example, if the node (570) is composed of a CU and a DU, the second path (551-2) may be associated with a group of cells provided by the DU. For example, the group of cells associated with the second path (551-2) may include an MCG.

For example, when using a split bearer, the base station (560) (or NR PDCP (561)) can provide a downlink packet to the RLC (NR RLC (562) or NR RLC (572)). At this time, the downlink packet provided from the NR PDCP (561) to the NR RLC (562) (or NR RLC (572)) can include a PDCP data PDU (protocol data unit). At this time, the header of the PDCP data PDU can include a PDCP SN (sequence number). The terminal (590) (or NR PDCP (591)) can reorder the downlink packet provided through the paths (551-1, 551-2) for the split bearer. For example, the terminal (590) (or NR PDCP (591)) can sort the order of downlink packets using the PDCP SN included in the received downlink packet.

In FIG. 5B, an example (550) of a user plane of a base station (560), a node (570), and a terminal (590) is illustrated, but the present disclosure is not limited thereto. For example, a connection can be established in the control plane for the DC between the base station (560), the node (570), and the terminal (590). For example, a higher layer (e.g., RRC) of the node (570) can be connected to an entity of the 5GC.

Also, in FIG. 5B, an example (550) is illustrated where a base station (560) includes multiple layers (NR PDCP (561), NR RLC (562), and NR MAC), but the present disclosure is not limited thereto. For example, the base station (560) may be composed of a CU (or gNB-CU) and a DU (or gNB-DU). For example, the CU may include NR PDCP (561). For example, the DU may include NR RLC (562) and NR MAC. In example (550), a node (570) that is a gNB is described, but the present disclosure is not limited thereto. For example, DC (e.g., NR-DC) using the split bearer may be provided between a base station (560) having NR PDCP (561) and a node (570) that is a gNB. Alternatively, for example, a DC (e.g., NR-DC) using the split bearer may be provided between a DU connected to a CU having NR PDCP (561) and another DU, a node (570). However, the present disclosure is not limited thereto. For example, the other DU, a node (570) connected to a CU having NR PDCP (561), may further include another CU.

As described above, when a split bearer is used for DC, downlink packets (or PDCP data PDUs) sequentially transmitted (or delivered, provided) from PDCP (e.g., NR PDCP (511) of FIG. 5A and NR PDCP (561) of FIG. 5B) of a base station (e.g., base station (510) of FIG. 5A or base station (560) of FIG. 5B) may be provided through different paths (e.g., first path (501-1) or second path (501-2) of FIG. 5A, first path (551-1) or second path (551-2) of FIG. 5B). Downlink packets provided through different paths may be received by terminals (e.g., terminals (540) of FIG. 5A and terminals (590) of FIG. 5B). Even if downlink packets are transmitted sequentially from the PDCP of the base station, the PDCP SNs of the downlink packets received at the terminal may not be sequential. Accordingly, the terminal may perform reordering in the PDCP of the terminal (e.g., NR PDCP (541) of FIG. 5a and NR PDCP (591) of FIG. 5b). When transmitting packets at a high speed, performing the reordering may cause an increase in the load of the terminal. For example, from the perspective of the terminal, depending on the result of performing the reordering, resources (or cycles) and memory (or buffer) as storage space for storing the sorted PDCP data PDUs (or packets) may be required. For example, the resources may include resources used in the chipset of the terminal. Specific examples related to the increase in the load of the terminal may be referred to the graphs of FIG. 8 below.

Hereinafter, the device, method, and storage medium according to the present disclosure propose a traffic distribution technique in DC using a split bearer. For example, the traffic distribution technique may be referred to as a packet distribution technique. For example, the device, method, and storage medium according to the present disclosure can continuously transmit downlink packets corresponding to a specified number through a path selected from among paths for a split bearer. In other words, the base station can continuously transmit downlink packets corresponding to a specified number through a specific path. Accordingly, the reordering performed at a terminal receiving consecutive downlink packets can be reduced. The device, method, and storage medium according to the present disclosure can cause a reduction in the load on the terminal and improve the throughput (or processing quality) of the terminal.

FIG. 6a illustrates an example of an operational flow for a method of transmitting consecutive downlink packets corresponding to a reference number through paths for a split bearer.

At least some of the methods of FIG. 6A may be performed by the electronic device (400) of FIG. 4. For example, at least some of the methods may be controlled by the processor (430) of the electronic device (400). 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. For example, the electronic device (400) may have a PDCP for a split bearer. For example, the electronic device (400) may include the base station (510) of FIG. 5A (or the base station (560) of FIG. 5B) having a PDCP for the split bearer. For example, the electronic device (400) may include a CU having a PDCP for the split bearer.

According to one embodiment, in operation (600), the electronic device (400) may obtain a DBS of a path. For example, the path may include a first path and a second path for the split bearer. For example, the first path may include an RLC of the electronic device (400) connected to the PDCP for the split bearer. For example, the first path may be related to a cell group (e.g., SCG) provided by the electronic device (400). For example, the second path may include an RLC of a node connected to the PDCP for the split bearer. For example, the node may be connected to the electronic device (400) to provide DC via the split bearer. For example, the second path may be related to a cell group (e.g., MCG) provided by the node.

For example, the electronic device (400) can obtain the first DBS of the first path. For example, the electronic device (400) can obtain the second DBS of the second path. For example, the first DBS can be included in the first DDDS provided from the RLC of the electronic device (400). For example, the second DBS can be included in the second DDDS provided from the RLC of the node. For example, the electronic device (400) can periodically obtain the DDDS of each path. For example, the DDDS can be transmitted from the RLC to the PDCP for the split bearer according to a specified time interval (e.g., 10 ms).

According to one embodiment, in operation (605), the electronic device (400) may receive a downlink packet. For example, the electronic device (400) may receive the downlink packet from an entity of the core network. For example, the core network may include an EPC or a 5GC. For example, the entity may include an entity for providing data in the user plane. For example, the entity may be an S-GW when the core network is an EPC. For example, the entity may be a UPF when the core network is a 5GC. In the above example, for convenience of explanation, a case where one downlink packet is received is illustrated, but the present disclosure is not limited thereto. For example, a plurality of downlink packets may be received sequentially. The following descriptions may be substantially equally applied to each of the downlink packets received sequentially.

According to one embodiment, the electronic device (400) may be in a state where there is no more than one downlink packet received before operation (605) in the buffer of the PDCP for the split bearer. For example, if there is more than one downlink packet remaining in the buffer of the PDCP when the DBSs are received in operation (600), the electronic device (400) may transmit the more than one downlink packet through a path of a DBS that was received first among the DBSs. In other words, if there is no packet in the buffer of the PDCP when the DBSs are received in operation (600), the electronic device (400) may transmit consecutive downlink packets through a path selected based on a comparison between the DBSs.

Although not illustrated in FIG. 6A, the electronic device (400) may perform operation (630) when there is no previously selected path (or when selecting the first path). In operation (630), the electronic device (400) may select a path based on the DBS. For example, the electronic device (400) may select a path to be used for transmitting a downlink packet based on the first DBS and the second DBS. In operation (635), the electronic device (400) may transmit the downlink packet through the selected path. In operation (640), the electronic device (400) may identify the remaining DBS and the number of continuously transmitted packets. For example, the remaining DBS may indicate the amount of remaining data (or buffer size, number of packets) depending on changes in the value of the DBS of each path. For example, the electronic device (400) can identify the remaining DBS by changing (or decreasing) the value of the DBS of the selected path by 1. For example, the electronic device (400) can identify the number of continuously transmitted packets by changing (or increasing) the value of the DBS of the selected path by 1. For example, the number of continuously transmitted packets can be referred to as the number of transmitted packets, the number of transmissions, the number of packets, the number of packets, the number of distributed packets, the number of distributions, or 'distributionContinuousNum'.

For example, after operation (640), the electronic device (400) may perform operation (605). In the re-performed operation (605), the electronic device (400) may receive a new downlink packet.

In FIG. 6A, operation (640) is depicted as being performed after operation (635), but the present disclosure is not limited thereto. For example, operation (640) may be performed concurrently with operation (635), or may be performed prior to operation (635) as a path is selected.

In one embodiment, in operation (610), the electronic device (400) may determine whether the remaining DBS of the previous path exceeds a reference value. For example, the reference value may include a value (e.g., 0) indicating whether the remaining DBS exists. In the example, the electronic device (400) may determine whether the remaining DBS (e.g., 499) of the first path exceeds the reference value.

For example, in operation (610), the electronic device (400) may perform operation (615) if the remaining DBS of the previous path exceeds the reference value (or the remaining DBS>0). The remaining DBS exceeding the reference value may indicate that there is an amount of data (or a buffer size) remaining that is required to be transmitted through the previous path having the remaining DBS. Conversely, in operation (610), the electronic device (400) may perform operation (630) if the remaining DBS of the previous path is less than or equal to the reference value (or the remaining DBS=0). For example, the remaining DBS being less than or equal to the reference value (or equal to the reference value) may indicate that there is no amount of data (or a buffer size, a number of packets) remaining that is required to be transmitted through the previous path having the remaining DBS.

According to one embodiment, in operation (615), the electronic device (400) may determine whether the number of continuously transmitted packets is less than a reference number (N). For example, the number of continuously transmitted packets may represent the number of downlink packets transmitted through the previous path. For example, the reference number (N) may indicate the number of continuous downlink packets to be transmitted through the previous path. For example, the reference number (N) may be a value set by the operator. Hereinafter, for convenience of explanation, it is assumed that the reference number is 5.

For example, in operation (615), the electronic device (400) may perform operation (620) if the number of the continuously transmitted packets is less than the reference number (N). For example, in operation (615), the electronic device (400) may perform operation (625) if the number of the continuously transmitted packets is greater than or equal to the reference number (N) (or equal to the reference number (N)).

According to one embodiment, in operation (620), the electronic device (400) may select the previous path. For example, if the number of the continuously transmitted packets is less than the reference number (N), the electronic device (400) may reselect the previous path as a path for transmitting the new downlink packet.

According to one embodiment, in operation (625), the electronic device (400) may set the number of the continuously transmitted packets to an initial value (e.g., 0). For example, the electronic device (400) may set (or initialize) the number of the continuously transmitted packets to the initial value if the number of the continuously transmitted packets through the previous path is greater than or equal to the reference number (or equal to the reference number). In other words, the electronic device (400) may initialize the number of the continuously transmitted packets before selecting a new path if downlink packets corresponding to the reference number have been transmitted through a specific path.

According to one embodiment, in operation (630), the electronic device (400) may select a path based on the DBS. For example, the electronic device (400) may select a path based on the remaining DBS of each path. The method of selecting a path based on the DBS may be referred to as a path selection algorithm.

According to one embodiment, in operation (635), the electronic device (400) may transmit a downlink packet through the selected path. In the above example, if the number of the continuously transmitted packets is less than the reference number, the electronic device (400) may transmit the new downlink packet to the terminal through the previous path. In addition, in the above example, if the number of the continuously transmitted packets is greater than or equal to the reference number (or equal to the reference number), the electronic device (400) may transmit the new downlink packet to the terminal through the path selected by the path selection algorithm.

According to one embodiment, in operation (640), the electronic device (400) can identify the remaining DBS and the number of continuously transmitted packets. For example, the remaining DBS can indicate the amount of remaining data (or buffer size, number of packets) according to the change in the value of the DBS of each path. For example, the electronic device (400) can identify the remaining DBS by changing (or decreasing) the value of the DBS of the selected path by 1. For example, the electronic device (400) can identify the number of continuously transmitted packets by changing (or increasing) the value of the DBS of the selected path by 1. For example, after operation (640), the electronic device (400) can perform operation (605). In operation (605) performed again, the electronic device (400) can receive a new downlink packet.

As described above, the electronic device (400) may repeatedly perform at least some operations (e.g., operations (605) to (640)) of the method of FIG. 6A whenever a new downlink packet is received. In the example of FIG. 6A, after transmitting a downlink packet in operation (635), the remaining DBS and the number of continuously transmitted packets are identified (or changed), but the present disclosure is not limited thereto. For example, the electronic device (400) may identify (or change) the remaining DBS and the number of continuously transmitted packets when selecting a path.

Referring to the above, the electronic device (400) can continuously transmit downlink packets corresponding to the reference number (N) through a specific path. Thereafter, the electronic device (400) can continuously transmit another downlink packet corresponding to the reference number (N) for a path selected based on the path selection algorithm. At this time, the selected path may be the same as or different from the specific path.

For example, assume that the first DBS indicates 500 packets and the second DBS indicates 100 packets. For example, the electronic device (400) may obtain the first DBS and the second DBS in operation (600). If there is no path previously used for transmission (or if the first path is selected), the electronic device (400) may select a path based on the path selection algorithm. For example, the electronic device (400) may select the first path among the first path and the second path for the split bearer based on the first DBS being larger than the second DBS. In this case, if the ratios of the remaining DBSs of the second DBS and the first DBS are the same, a path may be selected based on a comparison of the sizes of the DBSs. For example, the first ratio (e.g., 500/500) of the first DBS and the second ratio (100/100) of the second DBS may be the same.

For example, the electronic device (400) may transmit the received first downlink packet to the terminal through the first path. In addition, the electronic device (400) may identify the remaining DBS and the number of continuously transmitted packets. For example, the electronic device (400) may change (or decrease) the value of the first DBS from 500 to 499. For example, the remaining DBS of the first DBS may be identified as 499. For example, the electronic device (400) may change (or increase) the number of packets continuously transmitted through the first path from 0 to 1. For example, the number of packets continuously transmitted may be identified as 1.

For example, the electronic device (400) may receive a second downlink packet. For example, the electronic device (400) may determine whether the remaining DBS of the first path, which is a previous path, exceeds a reference value (e.g., 0). The electronic device (400) may determine that the remaining DBS (e.g., 499) of the first path exceeds the reference value. Based on the remaining DBS of the first path exceeding the reference value, the electronic device (400) may reselect the path for transmitting the second downlink packet as the first path. For example, the electronic device (400) may transmit the second downlink packet to the terminal through the first path. In addition, the electronic device (400) may identify the remaining DBS and the number of packets transmitted continuously. For example, the electronic device (400) can change (or decrease) the value of the first DBS from 499 to 498. For example, the remaining DBS of the first DBS can be identified as 498. For example, the electronic device (400) can change (or increase) the number of packets continuously transmitted through the first path from 1 to 2. For example, the number of packets continuously transmitted can be identified as 2.

By repeatedly performing the operations described above, the electronic device (400) can transmit consecutive downlink packets corresponding to a reference number (e.g., N=5) to the terminal through the first path. When the consecutive downlink packets corresponding to the reference number are transmitted, the remaining DBS of the first DBS can be identified as 495, and the number of consecutively transmitted packets can be identified as 5.

Thereafter, the electronic device (400) may receive a third downlink packet. For example, the electronic device (400) may determine whether the number of continuously transmitted packets (e.g., 5) is less than the reference number based on determining that the remaining DBS (e.g., 495) of the first path exceeds the reference value. The electronic device (400) may set the number of continuously transmitted packets to an initial value (e.g., 0) based on determining that the number of continuously transmitted packets (e.g., 5) is greater than or equal to the reference number (or equal to the reference number). The electronic device (400) may select a path on which to transmit the third downlink packet based on the path selection algorithm. In the above example, the electronic device (400) may select a path based on the remaining DBS (e.g., 495) of the first path and the DBS (e.g., 100) of the second path (or the remaining DBS (e.g., 100) of the second path). At this time, the electronic device (400) may select a path according to the ratio between the remaining DBS and the DBS of each path. For example, the first ratio for the first path may be 495/500. For example, the second ratio for the second path may be 100/100. For example, the electronic device (400) may select the second path corresponding to the second ratio having a larger value among the first ratio and the second ratio as the path for transmitting the third downlink packet.

For example, the electronic device (400) can transmit the third downlink packet to the terminal through the second path. In addition, the electronic device (400) can identify the remaining DBS and the number of continuously transmitted packets. For example, the electronic device (400) can change (or decrease) the value of the second DBS from 100 to 99. For example, the remaining DBS of the second DBS can be identified as 99. For example, the electronic device (400) can change (or increase) the number of packets continuously transmitted through the second path from 0 to 1. For example, the number of packets continuously transmitted can be identified as 1.

For example, the electronic device (400) may receive a fourth downlink packet. For example, the electronic device (400) may determine whether the remaining DBS of the second path, which is a previous path, exceeds a reference value (e.g., 0). The electronic device (400) may determine that the remaining DBS (e.g., 99) of the second path exceeds the reference value. Based on the fact that the remaining DBS of the second path exceeds the reference value, the electronic device (400) may reselect the second path as the path for transmitting the fourth downlink packet. For example, the electronic device (400) may transmit the fourth downlink packet to the terminal through the second path. In addition, the electronic device (400) may identify the remaining DBS and the number of packets transmitted continuously. For example, the electronic device (400) can change (or decrease) the value of the second DBS from 99 to 98. For example, the remaining DBS of the second DBS can be identified as 98. For example, the electronic device (400) can change (or increase) the number of packets continuously transmitted through the second path from 1 to 2. For example, the number of packets continuously transmitted can be identified as 2.

By repeatedly performing the operations described above, the electronic device (400) can transmit consecutive downlink packets corresponding to a reference number (e.g., N=5) to the terminal through the second path. When the consecutive downlink packets corresponding to the reference number are transmitted, the remaining DBS of the second DBS can be identified as 95, and the number of consecutively transmitted packets can be identified as 5.

Thereafter, the electronic device (400) may receive a fifth downlink packet. For example, the electronic device (400) may determine whether the number of continuously transmitted packets (e.g., 5) is less than the reference number based on determining that the remaining DBS (e.g., 95) of the second path exceeds the reference value. The electronic device (400) may set the number of continuously transmitted packets to an initial value (e.g., 0) based on determining that the number of continuously transmitted packets (e.g., 5) is greater than or equal to the reference number (or equal to the reference number). The electronic device (400) may select a path on which to transmit the fifth downlink packet based on the path selection algorithm. In the example, the electronic device (400) may select a path based on the remaining DBS (e.g., 495) of the first path and the remaining DBS (e.g., 95) of the DBS of the second path. At this time, the electronic device (400) may select a path based on the ratio between the remaining DBSs of each path. For example, the first ratio for the first path may be 495/500. For example, the second ratio for the second path may be 95/100. For example, the electronic device (400) may select the first path corresponding to the first ratio having a larger value between the first ratio and the second ratio as the path for transmitting the fifth downlink packet.

Referring to the above, the electronic device (400) can transmit consecutive downlink packets corresponding to a reference number through a selected path. A specific example of a method for transmitting consecutive downlink packets corresponding to a reference number through a specific path according to an embodiment of the present disclosure may be referred to in FIG. 6B below.

Figure 6b illustrates examples of how to transmit downlink packets over paths for a split bearer.

FIG. 6b illustrates an example (660) of a method for transmitting downlink packets through a path selected based on a DBS, and an example (670) of a method for transmitting consecutive downlink packets corresponding to a reference number through a specific path. In FIG. 6b, for convenience of explanation, it is assumed that the first DBS of the first path indicates 500 packets, and the second DBS of the second path indicates 100 packets.

Referring to example (660), the electronic device (400) can transmit downlink packets based on the DBSs of the paths. For example, the electronic device (400) can identify a ratio (e.g., 5:1) between the first DBS and the second DBS. For example, the electronic device (400) can select a path according to the ratio (5:1) and transmit downlink packets through the selected path. For example, the electronic device (400) can transmit five downlink packets (661) through the first path and one downlink packet (662) through the second path. For example, the electronic device (400) can transmit the downlink packet (662) through the second path and then transmit five downlink packets (663) through the first path. For example, the electronic device (400) may transmit five downlink packets (663) through the first path, and then transmit a downlink packet (664) through the second path. Thereafter, the electronic device (400) may repeatedly transmit downlink packets received from entities of the core network through alternately selected paths.

Referring to example (670), the electronic device (400) may transmit consecutive downlink packets corresponding to a reference number through each of the paths. For example, when selecting a first path, the electronic device (400) may select the first path based on a comparison between the first DBS and the second DBS. The electronic device (400) may transmit consecutive downlink packets (671) corresponding to a reference number (e.g., N=5) through the first path. Thereafter, the electronic device (400) may select the second path based on the remaining DBS of the first DBS (e.g., 495) and the second DBS (or the remaining DBS of the second DBS) (e.g., 100). For example, the second path may be selected based on a second ratio having a higher ratio among a first ratio (e.g., 495/500) for the first path and a second ratio (e.g., 100/100) for the second path. The electronic device (400) may transmit consecutive downlink packets (672) corresponding to a reference number (e.g., N=5) through the second path. Thereafter, the electronic device (400) may select the first path based on a remaining DBS (e.g., 495) of the first DBS and a remaining DBS (e.g., 95) of the second DBS. For example, the first path may be selected based on a first ratio having a higher ratio among a first ratio (e.g., 495/500) for the first path and a second ratio (e.g., 95/100) for the second path. The electronic device (400) can transmit consecutive downlink packets (673) corresponding to a reference number (e.g., N=5) through the first path. Thereafter, the electronic device (400) can select the first path based on the remaining DBS (e.g., 490) of the first DBS and the remaining DBS (e.g., 95) of the second DBS. For example, the first path can be selected based on the first ratio having a higher ratio among the first ratio (e.g., 490/500) for the first path and the second ratio (e.g., 95/100) for the second path. The electronic device (400) can transmit consecutive downlink packets (674) corresponding to a reference number (e.g., N=5) through the first path. After this, the electronic device (400) can transmit, through the selected path, as many consecutive downlink packets as correspond to a reference number among the downlink packets received from the entity of the core network.

Figure 7 illustrates an example of an operational flow for a method of changing the number of continuously transmitted packets as DDDS (downlink data delivery status) is obtained.

At least some of the methods of FIG. 7 may be performed by the electronic device (400) of FIG. 4. For example, at least some of the methods may be controlled by the processor (430) of the electronic device (400). 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. For example, the electronic device (400) may have a PDCP for a split bearer. For example, the electronic device (400) may include the base station (510) of FIG. 5A (or the base station (560) of FIG. 5B) having a PDCP for the split bearer. For example, the electronic device (400) may include a CU having a PDCP for the split bearer.

The method of FIG. 7 may include at least one operation performed by the electronic device (400) when a new DDDS is acquired while at least a portion of the method of FIG. 6A (e.g., operations (605) to (640)) is repeatedly performed.

According to one embodiment, in operation (700), the electronic device (400) may obtain a DDDS according to a specified period. For example, the specified period may be referred to as a specified time interval. For example, the electronic device (400) may obtain a first DDDS of a first path and a second DDDS of a second path. In one example, the first DDDS and the second DDDS may be obtained at the same timing or at different timings. Obtaining the first DDDS and the second DDDS may be referred to as performing operation (600) of FIG. 6A. Thereafter, the electronic device (400) may repeatedly perform operations (605) to (640).

According to one embodiment, while repeatedly performing operations (605) to (640), the electronic device (400) may acquire an additional DDDS. For example, the electronic device (400) may acquire a third DDDS of the first path. For example, the third DDDS may be acquired at a timing when the specified time interval has elapsed from the timing when the first DDDS is acquired. Alternatively, for example, the electronic device (400) may acquire a fourth DDDS of the second path. For example, the second DDDS may be acquired at a timing when the specified time interval has elapsed from the timing when the second DDDS is acquired.

According to one embodiment, in operation (705), the electronic device (400) may set the number of continuously transmitted packets as a reference number. For example, the reference number (N) may indicate the number of continuously downlink packets to be transmitted through the selected path. For example, the electronic device (400) may change (or set) the number of continuously transmitted packets to the reference number regardless of the actual number of continuously transmitted downlink packets. Accordingly, when the electronic device (400) receives a downlink packet through the core network, even if there is a remaining DBS of the selected path (or even if the remaining DBS of the selected path exceeds the reference value), since the number of continuously transmitted packets is equal to the reference number, the electronic device (400) may reset the number of continuously transmitted packets to an initial value. Thereafter, the electronic device (400) may perform a path selection algorithm (or path selection based on operation (630)).

Figures 8 and 9 illustrate examples of graphs of the performance of a terminal receiving downlink packets through paths for a split bearer.

FIG. 8 illustrates graphs (800, 830, 850) for the performance of a terminal that receives downlink packets transmitted according to the transmission method illustrated in example (660) of FIG. 6b. Graph (800) represents the performance of a PDCP of the terminal (e.g., NR PDCP (541) of FIG. 5a or NR PDCP (591) of FIG. 5b). The horizontal axis of graph (800) represents time, and the vertical axis represents throughput (unit: Mbps (mega bit per second)). Graph (830) represents the status of a first path for a split bearer (e.g., first path (501-1) of FIG. 5a or first path (551-1) of FIG. 5b). Graph (850) represents the status of a second path for a split bearer (e.g., second path (501-2) of FIG. 5A or second path (551-2) of FIG. 5B). The horizontal axis of graphs (830) and (850) may represent time, and the vertical axis may represent status values. For example, a first state among the status values may represent a normal state of the terminal load. For example, a second state among the status values may represent an abnormal state (or overload state) of the terminal load.

The first line (810) of the graph (800) may indicate the throughput (or PDCP throughput) of the terminal over time. For example, the first line (810) may have a throughput of about 700 Mbps to about 1 Gbps. The second line (820) of the graph (800) may indicate an average value for the first line (810). For example, the second line (820) may have a throughput of about 718 Mbps. When downlink packets provided through a split bearer are transmitted, the target performance of the terminal is about 2.4 Gbps, but the lines (810, 820) of the graph (800) may have values lower than the target performance.

Referring to graphs (830) and (850), the states of the first path and the second path may generally be in the second state within the time interval. In other words, the terminal may not be able to perform normal PDCP operation when performing reordering on downlink packets received at the PDCP of the terminal. In other words, the PDCP of the terminal may not be able to process packets for each of the first path and the second path.

In contrast, FIG. 9 shows graphs (900, 930, 950) of the performance of a terminal that has received consecutive downlink packets corresponding to the reference number transmitted according to the transmission method illustrated in the example (670) of FIG. 6b.

Graph (900) represents the performance of a PDCP of a terminal (e.g., NR PDCP (541) of FIG. 5A or NR PDCP (591) of FIG. 5B). The horizontal axis of graph (900) represents time, and the vertical axis represents throughput (unit: Mbps (mega bit per second)). Graph (930) represents the status of a first path for a split bearer (e.g., the first path (501-1) of FIG. 5A or the first path (551-1) of FIG. 5B). Graph (950) represents the status of a second path for a split bearer (e.g., the second path (501-2) of FIG. 5A or the second path (551-2) of FIG. 5B). The horizontal axes of graphs (930) and (950) may represent time, and the vertical axes may represent status values. For example, the first state among the state values may indicate that the terminal's load is normal. For example, the second state among the state values may indicate that the terminal's load is abnormal (or overloaded).

The first line (910) of the graph (900) may indicate the throughput (or PDCP throughput) of the terminal over time. For example, the first line (910) may have a throughput of about 1 Gbps to about 2.5 Gbps. The second line (920) of the graph (900) may indicate an average value for the first line (910). For example, the second line (920) may have a throughput of about 2.4 Gbps. The lines (910, 920) of the graph (900) may have values close to the target performance when downlink packets provided via a split bearer are transmitted.

Referring to graphs (930) and (950), compared to graphs (830) and (850) of FIG. 8, the states of the first path and the second path within the time interval may be generally the first state. In other words, the terminal may perform normal PDCP operations when performing reordering on downlink packets received at the PDCP of the terminal. In other words, the PDCP of the terminal may perform packet processing for each of the first path and the second path.

Referring to FIGS. 8 and 9 , the device, method, and storage medium according to the present disclosure can continuously transmit downlink packets corresponding to a specified number (e.g., a reference number) through a selected path among paths for a split bearer. In other words, the base station can continuously transmit downlink packets corresponding to a specified number through a specific path. Accordingly, the reordering performed at a terminal receiving consecutive downlink packets can be reduced. The device, method, and storage medium according to the present disclosure can cause a reduction in the load at the terminal and improve the throughput (or processing quality) of the terminal.

The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

Figure 10 illustrates an example of an operational flow for a method in which a base station transmits consecutive downlink packets corresponding to a reference number through paths for a split bearer.

At least some of the methods of FIG. 10 may be performed by the electronic device (400) of FIG. 4. For example, the electronic device (400) may be a base station (e.g., the base station (510) of FIG. 5A or the base station (560) of FIG. 5B). For example, at least some of the methods may be controlled by the processor (430) of the electronic device (400) (or the base station). 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. For example, the base station may have a PDCP for a split bearer. However, the present disclosure is not limited thereto. At least some of the methods of FIG. 10 may be performed by a CU. For example, the CU may have a PDCP for the split bearer.

According to one embodiment, in operation 1010, the base station may obtain a first DBS of a first path for the split bearer and a second DBS of a second path for the split bearer. For example, the first path may include an RLC of the base station connected to the PDCP for the split bearer. For example, the first path may be associated with a cell group (e.g., SCG) provided by the base station. For example, the second path may include an RLC of a node connected to the PDCP for the split bearer. For example, the node may be connected to the base station to provide DC via the split bearer. For example, the second path may be associated with a cell group (e.g., MCG) provided by the node.

According to one embodiment, in operation 1020, the base station may transmit consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS. For example, the base station may select the first path based on the first DBS having a larger value among the first DBS and the second DBS. For example, the base station may transmit the consecutive first downlink packets corresponding to the reference number to the terminal through the first path. For example, the terminal may support a split bearer.

According to one embodiment, the base station can identify the remaining DBS of the first DBS and the number of packets continuously transmitted through the first path as each of the consecutive first downlink packets is transmitted.

In one embodiment, the base station may determine whether the remaining DBS exceeds a threshold value. For example, the threshold value may include a value (e.g., 0) indicating whether the remaining DBS exists.

For example, the base station may perform a comparison between the number of continuously transmitted packets and the reference number when the remaining DBS of the first path exceeds the reference value (or the remaining DBS > 0). However, the present disclosure is not limited thereto. For example, the base station may not perform (or skip, refrain from, bypass) a comparison between the remaining DBS of the first path and the reference value. The remaining DBS exceeding the reference value may indicate that there remains an amount of data (or a buffer size) required to be transmitted through the first path having the remaining DBS. Alternatively, the base station may perform a path selection according to a path selection algorithm when the remaining DBS of the first path is less than or equal to the reference value (or the remaining DBS = 0). For example, if the remaining DBS is less than or equal to the reference value (or equal to the reference value), it may indicate that there is no amount of data (or buffer size, number of packets) remaining that is required to be transmitted through the first path having the remaining DBS.

In one embodiment, the base station may determine whether the number of continuously transmitted packets is less than the reference number (N). For example, the number of continuously transmitted packets may represent the number of downlink packets transmitted through the first path. For example, the reference number (N) may be a value set by the operator.

For example, the base station may select the first path as the path for transmitting the continuous first downlink packets when the number of the continuously transmitted packets is less than the reference number (N). Alternatively, the base station may set the number of the continuously transmitted packets to an initial value (e.g., 0) when the number of the continuously transmitted packets is greater than or equal to the reference number (N) (or is equal to the reference number (N)).

As described above, the base station can transmit the first downlink packets corresponding to the reference number to the terminal through the first path until the number of the continuously transmitted packets reaches the reference number.

According to one embodiment, in operation (1030), the base station may transmit consecutive second downlink packets corresponding to the reference number through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path. For example, the base station may perform a comparison between the remaining DBS of the first DBS and the second DBS (or the remaining DBS of the second DBS) according to the path selection algorithm.

For example, the base station may select a path based on a ratio between the remaining DBS and the DBS of each path. For example, the first ratio for the first path may represent a ratio between the remaining DBS of the first DBS and the first DBS. For example, the second ratio for the second path may represent a ratio between the remaining DBS of the second DBS and the second DBS. For example, the electronic device (400) may select the second path corresponding to the second ratio having a larger value among the first ratio and the second ratio as a path for transmitting the consecutive second downlink packets corresponding to the reference number. For example, the base station may transmit the consecutive second downlink packets corresponding to the reference number to the terminal through the second path.

For example, in operation (1020), the electronic device (400) may receive a first downlink packet among the consecutive first downlink packets from the entity and transmit the received first downlink packet through the first path. As the electronic device (400) transmits the first downlink packet, the electronic device (400) may identify the remaining DBS of the first DBS by decreasing the value of the first DBS, and may identify the number of packets continuously transmitted through the first path.

For example, the electronic device (400) may receive a second downlink packet following the first downlink packet from the entity. The electronic device (400) may determine whether the number of the continuously transmitted packets for the first path is less than a reference number. For example, if the number of the continuously transmitted packets of the first path is less than the reference number, the electronic device (400) may select the first path along which the second downlink packet included in the continuous first downlink packets is to be transmitted. Alternatively, if the number of the continuously transmitted packets of the first path is greater than or equal to the reference number (or equal to the reference number), the electronic device (400) may set the number of the continuously transmitted packets of the first path to an initial value. In addition, the electronic device (400) may select a path along which the second downlink packet included in the consecutive second downlink packets is to be transmitted based on the remaining DBS of the first DBS and the second DBS (or the remaining DBS of the second DBS) when the number of the continuously transmitted packets of the first path is greater than or equal to the reference number (or equal to the reference number). The path along which the second downlink packet is to be transmitted may be selected based on a first ratio between the first DBS and the remaining DBS of the first DBS and a second ratio between the second DBS and the remaining DBS of the second DBS. For example, when the first ratio is greater than or equal to the second ratio, the path may be selected as the first path. Conversely, when the first ratio is less than the second ratio, the path may be selected as the second path.

A base station having a packet data convergence protocol (PDCP) for a split bearer as described above may include at least one processor including a processing circuit. The base station may include a memory including one or more storage media storing instructions. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to obtain a first desired buffer size for the data radio bearer (DBS) of a first path for the split bearer and a second DBS of a second path for the split bearer. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to transmit, to a terminal, a first consecutive downlink packet corresponding to a reference number through the first path selected based on the first DBS and the second DBS. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to transmit, to the terminal, consecutive second downlink packets corresponding to the reference number through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path, after transmitting the consecutive first downlink packets.

In one embodiment, the first path may include an RLC (radio link control) of the base station connected to the PDCP. The second path may include an RLC of a node connected to the PDCP and connected to the base station.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the base station to obtain a first downlink data delivery status (DDDS) including the first DBS. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to obtain a second DDDS including the second DBS. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to select the first path from among the first path and the second path based on the first DBS being greater than the second DBS.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the base station to receive a first downlink packet of the consecutive first downlink packets from an entity of a core network connected to the base station. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to transmit the first downlink packet of the consecutive first downlink packets to the terminal via the first path. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to identify the remaining DBS of the first DBS by decreasing a value of the first DBS as the base station transmits the first downlink packet, and to identify a number of packets continuously transmitted via the first path.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the base station to determine, based on receiving a second downlink packet following the first downlink packet from the entity, whether the number of the continuously transmitted packets is less than the reference number. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to select the first path along which the second downlink packet included in the continuously transmitted first downlink packets is to be transmitted, if the number of the continuously transmitted packets is less than the reference number. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to set the number of the continuously transmitted packets to an initial value when the number of the continuously transmitted packets is greater than or equal to the reference number, and to select the path along which the second downlink packet included in the continuous second downlink packets is to be transmitted based on the remaining DBS of the first DBS and the second DBS.

In one embodiment, when the first ratio of the first DBS to the residual DBS of the first DBS is greater than or equal to the second ratio of the second DBS to the residual DBS of the second DBS, the path may be selected as the first path among the first path and the second path. When the first ratio is less than the second ratio, the path may be selected as the second path among the first path and the second path.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the base station to determine whether the remaining DBS of the first DBS is less than a reference value. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to select the path for transmission of the second downlink packet based on the remaining DBS of the first DBS and the second DBS when the remaining DBS of the first DBS is less than the reference value. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to determine whether the number of the continuously transmitted packets is less than the reference number when the remaining DBS of the first DBS is greater than or equal to the reference value.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the base station to obtain a third DDDS including a third DBS of the first path for the split bearer before receiving a second downlink packet following the first downlink packet from the entity. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to set a number of the continuously transmitted packets to the reference number upon obtaining the third DDDS. The instructions, when individually or collectively executed by the at least one processor, may cause the base station to select, after receiving the second downlink packet, the path along which the second downlink packet included in the consecutive second downlink packets is to be transmitted, based on the remaining DBS of the first DBS and the second DBS.

According to one embodiment, the base station may include a next generation Node B (gNB). An entity of a core network that provides the consecutive first downlink packets and the consecutive second downlink packets, and is connected to the base station, may include a user plane function (UPF) or a serving gateway (S-GW). A node associated with the second path and connected to the base station may include an evolved Node B (eNodeB) or a gNB.

In one embodiment, the first DBS may be used to indicate a data amount for a secondary cell group (SCG) associated with the first path. The second DBS may be used to indicate a data amount for a master cell group (MCG) associated with the second path.

A method performed by a base station having a packet data convergence protocol (PDCP) for a split bearer as described above may include an operation of acquiring a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer and a second DBS of a second path for the split bearer. The method may include an operation of transmitting, to a terminal, consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS. The method may include an operation of transmitting, after transmitting the consecutive first downlink packets, consecutive second downlink packets corresponding to the reference number through a path selected based on a remaining DBS of the first DBS and the second DBS among the first path and the second path.

The non-transitory computer-readable storage medium as described above may store one or more programs including instructions that, when individually or collectively executed by at least one processor of a base station having a packet data convergence protocol (PDCP) for a split bearer, cause the base station to obtain a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer and a second DBS of a second path for the split bearer. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the base station to transmit, to a terminal, consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the terminal to transmit, to the terminal, consecutive second downlink packets corresponding to the reference number, through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path, after transmitting the consecutive first downlink packets.

A device of a central unit (CU) having a packet data convergence protocol (PDCP) for a split bearer as described above may include at least one processor including a processing circuit. The device may include a memory including one or more storage media storing instructions. The instructions, when individually or collectively executed by the at least one processor, may cause the device to receive a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer from a distributed unit (DU) connected to the CU. The instructions, when individually or collectively executed by the at least one processor, may cause the device to receive a second DBS of a second path for the split bearer from a node connected to the CU. The instructions, when individually or collectively executed by the at least one processor, may cause the device to transmit, to a terminal, consecutive first downlink packets corresponding to a reference number via the first path selected based on the first DBS and the second DBS. The instructions, when individually or collectively executed by the at least one processor, may cause the device to, after transmitting the consecutive first downlink packets, transmit, to the terminal, consecutive second downlink packets corresponding to the reference number via a path selected based on the remaining DBSs of the first DBS and the second DBS among the first path and the second path.

In one embodiment, the first path may include a radio link control (RLC) of the DU. The second path may include an RLC of the node.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the device to receive, from the DU, a first downlink data delivery status (DDDS) comprising the first DBS. The instructions, when individually or collectively executed by the at least one processor, may cause the device to receive, from the node, a second DDDS comprising the second DBS. The instructions, when individually or collectively executed by the at least one processor, may cause the device to select the first path from among the first path and the second path based on the first DBS being greater than the second DBS.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the device to receive a first downlink packet of the consecutive first downlink packets from an entity of a core network connected to the CU. The instructions, when individually or collectively executed by the at least one processor, may cause the device to transmit the first downlink packet of the consecutive first downlink packets to the terminal via the first path. The instructions, when individually or collectively executed by the at least one processor, may cause the device to identify the remaining DBS of the first DBS by decreasing a value of the first DBS as the device transmits the first downlink packet, and to identify a number of packets continuously transmitted via the first path.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the device to determine, based on receiving a second downlink packet following the first downlink packet from the entity, whether the number of the continuously transmitted packets is less than the reference number. The instructions, when individually or collectively executed by the at least one processor, may cause the device to select the first path along which the second downlink packet included in the continuously transmitted first downlink packets is to be transmitted, if the number of the continuously transmitted packets is less than the reference number. The instructions, when individually or collectively executed by the at least one processor, may cause the device to set the number of the continuously transmitted packets to an initial value when the number of the continuously transmitted packets is greater than or equal to the reference number, and to select the path along which the second downlink packet included in the continuous second downlink packets is to be transmitted based on the remaining DBS of the first DBS and the second DBS.

In one embodiment, when the first ratio of the first DBS to the residual DBS of the first DBS is greater than or equal to the second ratio of the second DBS to the residual DBS of the second DBS, the path may be selected as the first path among the first path and the second path. When the first ratio is less than the second ratio, the path may be selected as the second path among the first path and the second path.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the device to determine whether the remaining DBS of the first DBS is less than a reference value. The instructions, when individually or collectively executed by the at least one processor, may cause the device to select the path for transmission of the second downlink packet based on the remaining DBS of the first DBS and the second DBS, if the remaining DBS of the first DBS is less than the reference value. The instructions, when individually or collectively executed by the at least one processor, may cause the device to determine whether the number of the continuously transmitted packets is less than the reference number, if the remaining DBS of the first DBS is greater than or equal to the reference value.

In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the device to receive, from the DU, a third DDDS including a third DBS of the first path for the split bearer before receiving a second downlink packet following the first downlink packet from the entity. The instructions, when individually or collectively executed by the at least one processor, may cause the device to set a number of the continuously transmitted packets to the reference number upon obtaining the third DDDS. The instructions, when individually or collectively executed by the at least one processor, may cause the device to select, after receiving the second downlink packet, the path along which the second downlink packet included in the consecutive second downlink packets is to be transmitted, based on the remaining DBS of the first DBS and the second DBS.

According to one embodiment, the entity of the core network that provides the consecutive first downlink packets and the consecutive second downlink packets and is connected to the CU may include a user plane function (UPF) or a serving gateway (S-GW). The node associated with the second path may include an evolved Node B (eNodeB).

In one embodiment, the first DBS may be used to indicate a data amount for a secondary cell group (SCG) associated with the DU. The second DBS may be used to indicate a data amount for a master cell group (MCG) associated with the node.

A method performed by a central unit (CU) having a packet data convergence protocol (PDCP) for a split bearer as described above may include receiving a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer from a distributed unit (DU) connected to the CU. The method may include receiving a second DBS of a second path for the split bearer from a node connected to the CU. The method may include transmitting, to a terminal, consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS. The method may include an operation of transmitting, to the terminal, consecutive second downlink packets corresponding to the reference number through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path, after transmitting the consecutive first downlink packets.

The non-transitory computer-readable storage medium as described above may store one or more programs including instructions that, when individually or collectively executed by at least one processor of a central unit (CU) having a packet data convergence protocol (PDCP) for a split bearer, cause the CU to receive a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer from a distributed unit (DU) connected to the CU. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the CU to receive a second DBS of a second path for the split bearer from a node connected to the CU. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the terminal to transmit, to the terminal, consecutive first downlink packets corresponding to a reference number, through the first path selected based on the first DBS and the second DBS. The non-transitory computer-readable storage medium may store one or more programs including instructions that, when individually or collectively executed by the at least one processor, cause the terminal to transmit, after transmitting the consecutive first downlink packets, consecutive second downlink packets corresponding to the reference number, through a path selected based on the remaining DBSs of the first DBS and the second DBS among the first path and the second path.

The 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.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present 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 commodity. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., Play Store™) or directly between two user devices (e.g., smart phones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily created in a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

These 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, or may be stored in memories formed by a combination of some or all of these. In addition, each configuration memory may include multiple copies.

Additionally, the program may be stored on an attachable storage device that is accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed singularly or plurally, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

According to embodiments, one or more of the components or operations of the aforementioned components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In such a case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. According to embodiments, the 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.

Meanwhile, although the detailed description of the present disclosure has described specific embodiments, it is obvious that various modifications are possible within the scope of the present disclosure.

Claims (15)

In a base station having PDCP (packet data convergence protocol) for split bearer, At least one processor comprising a processing circuit; and A memory comprising one or more storage media for storing instructions, The above instructions, when individually or collectively executed by the at least one processor, cause the base station to: Obtain a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer and a second DBS of a second path for the split bearer, Transmitting to a terminal consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS, and After transmitting the above-mentioned consecutive first downlink packets, causing the terminal to transmit the consecutive second downlink packets corresponding to the reference number through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path. Base station. In claim 1, The first path includes the RLC (radio link control) of the base station connected to the PDCP, and The second path includes the RLC of a node connected to the PDCP and connected to the base station. Base station. In claim 1, The above instructions, when individually or collectively executed by the at least one processor, cause the base station to: Obtaining a first DDDS (downlink data delivery status) including the first DBS, Obtaining a second DDDS including the second DBS, and Causing to select the first path among the first path and the second path based on the first DBS being greater than the second DBS, Base station. In claim 3, The above instructions, when individually or collectively executed by the at least one processor, cause the base station to: Receive a first downlink packet among the consecutive first downlink packets from an entity of a core network connected to the base station, Transmitting the first downlink packet among the consecutive first downlink packets to the terminal through the first path, and As the first downlink packet is transmitted: Identifying the residual DBS of the first DBS by decreasing the value of the first DBS, and causing the number of packets transmitted continuously through the first path to be identified, Base station. In claim 4, The above instructions, when individually or collectively executed by the at least one processor, cause the base station to: Based on receiving a second downlink packet following the first downlink packet from the entity, determining whether the number of continuously transmitted packets is less than the reference number, If the number of the continuously transmitted packets is less than the reference number, the first path along which the second downlink packet included in the continuous first downlink packets is to be transmitted is selected, and If the number of packets transmitted continuously is greater than or equal to the above standard number: The number of packets transmitted continuously is set as an initial value, and Based on the residual DBS of the first DBS and the second DBS, causing the path to be selected along which the second downlink packet included in the consecutive second downlink packets is to be transmitted. Base station. In claim 5, If the first ratio of the first DBS to the residual DBS of the first DBS is greater than or equal to the second ratio of the second DBS to the residual DBS of the second DBS, the path is selected as the first path among the first path and the second path, and If the first ratio is less than the second ratio, the path is selected as the second path among the first path and the second path. Base station. In claim 5, The above instructions, when individually or collectively executed by the at least one processor, cause the base station to: Determine whether the residual DBS of the first DBS is less than the reference value, If the residual DBS of the first DBS is less than the reference value, the path for transmission of the second downlink packet is selected based on the residual DBS of the first DBS and the second DBS, and If the remaining DBS of the first DBS is greater than or equal to the reference value, causing a determination to be made as to whether the number of continuously transmitted packets is less than or equal to the reference number, Base station. In claim 4, The above instructions, when individually or collectively executed by the at least one processor, cause the base station to: Before receiving a second downlink packet following the first downlink packet from the entity, acquire a third DDDS including a third DBS of the first path for the split bearer, Upon obtaining the third DDDS, the number of continuously transmitted packets is set to the reference number, and After receiving the second downlink packet, based on the remaining DBS of the first DBS and the second DBS, causing the path to be selected along which the second downlink packet included in the consecutive second downlink packets is to be transmitted. Base station. In claim 1, The above base station includes a gNB (next generation Node B), The entity of the core network connected to the base station provides the above-described consecutive first downlink packets and the above-described consecutive second downlink packets, and includes a user plane function (UPF) or a serving-gateway (S-GW), and In relation to the second path, the node connected to the base station includes an eNodeB (evolved Node B) or gNB. Base station. In claim 1, The first DBS is used to indicate the amount of data for the secondary cell group (SCG) associated with the first path, and The second DBS is used to indicate the amount of data for the MCG (master cell group) associated with the second path. Base station. A method performed by a base station having PDCP (packet data convergence protocol) for split bearer, An operation of obtaining a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer and a second DBS of a second path for the split bearer, An operation of transmitting, to a terminal, consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS, and After transmitting the above-described consecutive first downlink packets, an operation of transmitting, to the terminal, consecutive second downlink packets corresponding to the reference number through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path, method. In claim 11, The first path includes the RLC (radio link control) of the base station connected to the PDCP, and The second path includes the RLC of a node connected to the PDCP and connected to the base station. method. In claim 11, The above method is: An operation of obtaining a first DDDS (downlink data delivery status) including the first DBS; An operation of obtaining a second DDDS including the second DBS, and An operation of selecting the first path among the first path and the second path based on the first DBS being greater than the second DBS, method. In claim 13, The above method is: An operation of receiving a first downlink packet among the consecutive first downlink packets from an entity of a core network connected to the base station; An operation of transmitting the first downlink packet among the consecutive first downlink packets to the terminal through the first path, and As the first downlink packet is transmitted: An operation of identifying the remaining DBS of the first DBS by decreasing the value of the first DBS, and Including an operation of identifying the number of packets continuously transmitted through the first path, method. In a non-transitory computer-readable storage medium, when individually or collectively executed by at least one processor of a base station having a packet data convergence protocol (PDCP) for a split bearer, the base station: Obtain a first DBS (desired buffer size for the data radio bearer) of a first path for the split bearer and a second DBS of a second path for the split bearer, Transmitting to a terminal consecutive first downlink packets corresponding to a reference number through the first path selected based on the first DBS and the second DBS, and After transmitting the above-described consecutive first downlink packets, storing one or more programs including instructions causing the terminal to transmit consecutive second downlink packets corresponding to the reference number through a path selected based on the remaining DBS of the first DBS and the second DBS among the first path and the second path. Non-transitory computer-readable storage medium.