Methods and apparatus for retransmitting packets in dual-connectivity networks

Abstract

A data transmission method is provided, the data transmission method comprising: obtaining from a core network (CN) at least one packet to be transmitted to a user equipment via a first cell group or a second cell group; determining, among the at least one packet, a packet to be transmitted via the second cell group; transmitting the determined packet to the user equipment via the second cell group; obtaining packet delivery status information of the first cell group and packet delivery status information of the second cell group; determining, based on the packet delivery status information of the first cell group and the packet delivery status information of the second cell group, whether to retransmit the transmitted packet; and retransmitting, via the first cell group, the determined packet to be retransmitted to the user equipment.

Description

Technical Field

[0001] This disclosure relates to a data transmission method and apparatus using a split bearer, and more specifically, to a method and apparatus for retransmitting packets with transmission delays by using a split bearer when transmission delays occur. Background Technology

[0002] Dual connectivity refers to a standardized technique used in the Long Term Evolution (LTE) system of fourth-generation (4G) communications to improve the performance of small cells, in which the bearer is split to send data to two or more cell groups.

[0003] User equipment (UE) performs reordering to process received packets in the order they were transmitted. When a packet is not received, the UE sets a reordering timer and waits for that packet to be received. In this scenario, if a packet is not received before the reordering timer expires for some reason, large-scale data loss and reduced transmission rates may subsequently occur. Summary of the Invention

[0004] Technical issues

[0005] According to embodiments of this disclosure, a system and method are provided in which, in a dual-connectivity network environment, packet delays caused by reordering delays occurring when user equipment delivers packets to higher layers in order are prevented, and packet loss caused by reordering timer expiration is prevented.

[0006] Technical solution

[0007] The representative features disclosed herein for solving the above problems are as follows.

[0008] According to embodiments of this disclosure, a data transmission method is provided, the data transmission method comprising: obtaining from a core network (CN) at least one packet to be transmitted to a user equipment via a first cell group or a second cell group; determining, among the at least one packet, a packet to be transmitted via the second cell group; transmitting the determined packet to the user equipment via the second cell group; obtaining packet delivery status information of the first cell group and packet delivery status information of the second cell group; determining, based on the packet delivery status information of the first cell group and the packet delivery status information of the second cell group, whether to retransmit the transmitted packet; and retransmitting, via the first cell group, the determined packet to be retransmitted to the user equipment.

[0009] According to another embodiment of this disclosure, determining a retransmission may include: predicting the expiration of the reordering timer of the user equipment; and determining the packet to be retransmitted when the expiration of the reordering timer is anticipated.

[0010] According to another embodiment of this disclosure, predicting the expiration of the reordering timer may include setting T... reordertimer -(T real -T reorder ) is compared with a certain threshold, and T reordertimer T can represent the time that the user equipment waits for the transmitted packet. real It can represent the current time, and T reorder This can indicate the time when the reordering timer is started in the user equipment.

[0011] According to another embodiment of this disclosure, determining retransmission may include inputting the current packet delivery status information of the first cell group and the current packet delivery status information of the second cell group into an artificial intelligence (AI) model trained based on the packet delivery status information of the first cell group and the packet delivery status information of the second cell group.

[0012] According to another embodiment of this disclosure, the packet delivery status information of the first cell group and the packet delivery status information of the second cell group can be determined based on feedback information received from the user equipment.

[0013] According to another embodiment of this disclosure, the packet delivery status information of the first cell group may include the downlink data delivery status (DDDS) of the radio link control (RLC) layer of the first cell group, and the packet delivery status information of the second cell group may include the DDDS of the RLC layer of the second cell group.

[0014] According to another embodiment of this disclosure, the packets determined for retransmission may include packets that are determined to be retransmitted and sent with priority over other packets.

[0015] According to embodiments of this disclosure, a data transmission apparatus is provided, the data transmission apparatus comprising: a communicator; a memory storing a plurality of instructions; and at least one processor configured to execute the plurality of instructions, wherein the at least one processor is further configured to: obtain from a core network (CN) at least one packet to be transmitted to a user equipment via a first cell group or a second cell group; determine, among the at least one packet, a packet to be transmitted via the second cell group; transmit the determined packet to the user equipment via the second cell group; obtain packet delivery status information of the first cell group and packet delivery status information of the second cell group; and determine, based on the packet delivery status information of the first cell group and the packet delivery status information of the second cell group, whether to retransmit the transmitted packet; and the communicator is configured to transmit the determined packet to the user equipment via the second cell group, and to retransmit the determined packet to be retransmitted to the user equipment via the first cell group.

[0016] According to embodiments of the present disclosure, a computer-readable recording medium is provided that records a program for performing the data transmission method.

[0017] Furthermore, other methods, other systems, and computer-readable recording media containing computer programs for implementing the present disclosure may be provided, the computer programs being used to perform the data transmission methods.

[0018] Beneficial effects

[0019] According to this disclosure, in a dual-connectivity network environment, the expiration of the user equipment's reordering timer can be predicted to avoid loss caused by it, thereby preventing large-scale data loss and a sharp decrease in transmission rate. Attached Figure Description

[0020] Figure 1 A dual-connectivity wireless communication system is shown;

[0021] Figure 2a This illustrates a network deployment of Evolved Universal Terrestrial Radio Access (E-UTRA)-New Radio (NR) Dual Connectivity (DC) (EN-DC) among network deployment options based on the fifth-generation (5G) standard.

[0022] Figure 2b The network deployment of Next Generation Radio Access Network (NG-RAN) E-UTRA-NR DC (NGEN-DC) is shown among the network deployment options according to the 5G standard.

[0023] Figure 2cThe network deployment of NR E-UTRA DC (NE-DC) is shown among the network deployment options according to the 5G standard.

[0024] Figure 2d The diagram illustrates NR-DC network deployment among network deployment options based on 5G standards.

[0025] Figure 3 Various bearer types for dual connections are shown;

[0026] Figure 4 An embodiment of the 5G NGEN-DC non-standalone (NSA) network architecture is shown;

[0027] Figure 5a It shows in Figure 4 In the embodiment shown, the packet reception status of the NR Packet Data Convergence Protocol (PDCP) layer 510 of the user equipment 500 when the reception of packet 4 is delayed;

[0028] Figure 5b It shows in Figure 5a The state of the received packet in the NR PDCP layer 510 of user equipment 500 after the reception delay of packet 7;

[0029] Figure 5c It shows in Figure 5b After the state of receiving packet 4, the NRPDCP layer 510 of user equipment 500 receives the packet state;

[0030] Figure 5d It shows in Figure 5c Following the state of the NRPDCP layer 510 of user equipment 500, the receive packet state will be determined when the reordering timer expires.

[0031] Figure 5e It shows Figure 5d The received packet status of the Transmission Control Protocol (TCP) / Internet Protocol (IP) layer 570 of the user equipment 500 in the illustrated embodiment;

[0032] Figure 6 This is an operation flowchart of a wireless communication system according to an embodiment of the present disclosure;

[0033] Figure 7 An embodiment of split bearer in an NGEN-DC NSA network according to an embodiment of the present disclosure is shown;

[0034] Figure 8a It shows Figure 7 Downlink packet states managed in PDCP 110 in the illustrated embodiment;

[0035] Figure 8b It is used to describe in Figure 7 The illustrated embodiment shows a view of the downlink packet state managed in PDCP 110 being updated;

[0036] Figure 8c It is used to describe in Figure 7 The illustrated embodiment is a view of a method for copying and retransmitting packets based on the downlink packet state managed in PDCP 110 before the reordering timer expires;

[0037] Figure 8d It is used to describe in Figure 8c The illustrated embodiment shows a view of the downlink packet state managed in PDCP 110 after packet retransmission;

[0038] Figure 9 This is a view used to describe a method for determining cell group copy and retransmit packets according to embodiments of the present disclosure;

[0039] Figure 10 This is a view used to describe a method for retransmitting duplicated packets in a cell group according to embodiments of the present disclosure;

[0040] Figure 11 This is a flowchart of a data transmission method according to embodiments of the present disclosure; and

[0041] Figure 12 This is a block diagram of a data transmission apparatus according to an embodiment of the present disclosure.

[0042] Best practice

[0043] A data transmission method according to an embodiment of the present disclosure includes: obtaining from a core network (CN) at least one packet to be transmitted to a user equipment via a first cell group or a second cell group; determining, among the at least one packet, a packet to be transmitted via the second cell group; transmitting the determined packet to the user equipment via the second cell group; obtaining packet delivery status information of the first cell group and packet delivery status information of the second cell group; determining, based on the packet delivery status information of the first cell group and the packet delivery status information of the second cell group, whether to retransmit the transmitted packet; and retransmitting, via the first cell group, the packet to be retransmitted to the user equipment. Detailed Implementation

[0044] Hereinafter, various embodiments of the present disclosure will be disclosed with reference to the accompanying drawings.

[0045] When describing embodiments of this disclosure, technical matters well-known in the art and not directly related to this disclosure will not be described. By omitting any unnecessary descriptions, the subject matter of this disclosure will be described more clearly and without ambiguity.

[0046] For the same reasons, some elements in the accompanying drawings will be exaggerated, omitted, or simplified. The size of each element does not perfectly reflect its actual size. In each drawing, the same or corresponding elements will be referred to by the same reference numeral.

[0047] See below and appendix Figure 1 The advantages and features of this disclosure, as well as methods of implementing them, will become clear from the embodiments described herein. However, this disclosure is not limited to the disclosed embodiments, but can be implemented in various ways, and the embodiments are provided to complete the disclosure and to enable those skilled in the art to understand the scope of this disclosure, which is defined by the scope of the claims. Throughout this specification, the same reference numerals will indicate the same elements.

[0048] Furthermore, it is known to those skilled in the art that flowchart blocks and combinations of flowcharts can be represented and executed by computer program instructions. These computer program instructions can also be stored in a processor of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that the instructions implemented by the processor of the computer or programmable data processing apparatus create means for performing the functions specified in the flowchart and / or block diagram blocks. These computer program instructions can also be stored in a computer-usable or computer-readable storage medium that can instruct the computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-usable or computer-readable storage medium create an article of writing including instructions for implementing the functions specified in the flowchart and / or block diagram blocks. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions executing the computer or other programmable apparatus can provide steps for implementing the functions specified in the flowchart and / or block diagram blocks.

[0049] Additionally, each block represents a module, segment, or section of code that includes one or more operable instructions for implementing the specified logical function. It should also be noted that in other implementations, the functions indicated in the blocks may not occur in the indicated order. For example, depending on the functions involved, two blocks shown sequentially may actually be executed substantially concurrently, or sometimes in reverse order.

[0050] In the current embodiments, the term "~cell" as used herein refers to a software or hardware component, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC), that performs certain tasks. However, the meaning of "~cell" is not limited to software or hardware. A "~cell" can advantageously be configured to reside on an addressable memory medium and to reproduce one or more processors. Thus, as examples, a cell can include components (such as software components, object-oriented software components, class components, and task components), processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided in components and "~cells" can be combined into fewer components and "~cells" or further divided into additional components and "~cells." Additionally, components and "~cells" can be implemented to run one or more CPUs in a device or secure multimedia card. In embodiments of this disclosure, a "~cell" can include one or more processors.

[0051] The artificial intelligence (AI) related functions disclosed herein are executed via a processor and memory. The processor may include one or more processors. In this case, the one or more processors may include general-purpose processors such as CPUs, application processors (APs), digital signal processors (DSPs), graphics-specific processors such as GPUs, vision processing units (VPUs), or AI-specific processors such as neural processing units (NPUs). The one or more processors can control the processing of data according to predefined operating rules or AI models stored in memory. When one or more processors include an AI-specific processor, the AI-specific processor can be designed as a hardware architecture specifically for processing a particular AI model.

[0052] Predefined operating rules or AI models can be developed through training. Here, when predefined operating rules or AI models are developed through training, it can mean that the basic AI model is trained using a learning algorithm with multiple training data sets, thus establishing predefined operating rules or AI models set to operate on the desired characteristics (or objectives). This training can be performed by a device implementing the AI ​​according to this disclosure, or by a separate server and / or system. Examples of learning algorithms can include, but are not limited to, supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning.

[0053] AI models can include multiple neural network layers. Each of these layers can have multiple weight values, and neural network operations are performed through operations between the results of operations in the previous layer and these weight values. The weight values ​​of the multiple neural network layers can be optimized using the training results of the AI ​​model. For example, the weight values ​​can be updated to reduce or minimize the loss or cost values ​​acquired in the AI ​​model during training. Examples of artificial neural networks can include, but are not limited to, convolutional neural networks (CNNs), deep neural networks (DNNs), recurrent neural networks (RNNs), restricted Boltzmann machines (RBMs), deep belief networks (DBNs), bidirectional recurrent deep neural networks (BRDNNs), or deep Q-networks.

[0054] The present disclosure will now be described in detail with reference to the accompanying drawings.

[0055] Before the description in this specification, the fourth-generation (4G) Long Term Evolution (LTE) system, the fifth-generation (5G) New Radio (NR) system, and Dual Connectivity (DC) will be described.

[0056] A base station, as an entity that communicates with user equipment, can be represented as BS, node, NodeB, Node, NodeB(NB), eNodeB(eNB), gNodeB(gNB), access point (AP), etc.

[0057] User equipment, which is the entity that communicates with the base station, can be referred to as UE, user terminal, mobile station (MS), mobile device (ME), equipment, terminal, etc.

[0058] Broadband wireless technology has evolved to meet the needs of a growing number of broadband subscribers and provide better applications and services.

[0059] 4G wireless communication systems have been developed to provide high-speed data services, but they are now hampered by a shortage of resources to meet the growing demand for such services.

[0060] In this regard, 5G wireless communication systems have been developed to meet the growing demand for high-speed data services and support applications with ultra-reliability and low latency.

[0061] 5G wireless communication systems can be implemented in higher frequency (millimeter wave) bands (e.g., 10 GHz to 100 GHz band) as well as in lower frequency bands to achieve higher data rates.

[0062] To reduce propagation loss of radio waves and increase transmission distance, beamforming, multiple-input multiple-output (MIMO), full-dimensional MIMO, array antennas, and beamforming schemes have been considered in the design of 5G wireless communication systems.

[0063] For ease of description, this section will primarily focus on 4G wireless communication systems; however, unless otherwise specified, the corresponding technologies can also be applied to 5G wireless communication systems.

[0064] In 4G wireless communication systems, user equipment can communicate with eNBs, while in 5G wireless communication systems, user equipment can communicate with gNBs.

[0065] In a 4G wireless communication system, the wireless protocol stack used for communication between a user equipment and an eNB may include a packet data convergence protocol (PDCP), radio link control (RLC), media access control (MAC), and a physical (PHY) sublayer. One or more data radio bearers (DRBs) can be established between the user equipment and the eNB to exchange user plane packets.

[0066] Each data radio bearer can be associated with one PDCP entity and one or more RLC entities, and each data radio bearer can be associated with a logical channel in the MAC sublayer. In the user equipment, there is one MAC entity for the eNB.

[0067] The main services and functions of the MAC sublayer may include: mapping between logical channels and transport channels; multiplexing / demultiplexing of MAC Service Data Units (SDUs) belonging to one or different logical channels to transport blocks (TBs) (the transport blocks (TBs) are delivered to / from the physical channels on the transport channels); scheduling information reporting; error correction based on Hybrid Automatic Repeat Request (HARQ); priority processing between logical channels of a user equipment; priority processing between user equipments based on dynamic scheduling; and transmission format selection and padding.

[0068] The main services and functions of the user plane in the PDCP sublayer may include: header compression and decompression: Robust Header Compression Only (ROHC); transmission of user data; in the case of split bearers in DC (only Radio Link Control Acknowledgment Mode (RLC AM) is supported), in the PDCP reconstruction process for RLC AM, in the case of PDC PDU routing for transmission and PDCP PDU reordering for reception; redundancy detection of lower layer SDUs in the PDCP reconstruction process for RLC AM; retransmission of PDCP PDUs in the case of PDCP SDUs in handover and split bearers in DC, in the case of PDCP SDUs, in the PDCP data recovery process; encryption and decryption; and timer-based discarding of SDUs in the uplink (UL).

[0069] The functions of the PDCP sublayer can be performed by PDCP entities. Each PDCP entity can carry data for one radio bearer.

[0070] Due to the mobility of user equipment, user equipment can switch from one eNB to another.

[0071] In dual-connectivity operation mode due to user equipment mobility, user equipment can switch from one primary eNB (MeNB) to another MeNB or perform a secondary cell group (SCG) change from one secondary eNB (SeNB) to another SeNB.

[0072] An eNB can support multiple cells, and user equipment can switch from one cell of the same eNB to another cell of the same eNB.

[0073] Figure 1 A dual-connectivity wireless communication system is shown.

[0074] Dual connectivity, as a standardized technology for improving small cell performance in LTE and 4G communication systems, aims to improve the throughput of user equipment by using radio resources across multiple carriers, similar to carrier aggregation (CA).

[0075] According to the 4G communication standard, 3GPP 36.300, DC is an operating mode in which a user equipment capable of performing multiple transmit / receive in Radio Resource Control (RRC) connection mode is configured to use the radio resources of each scheduler located in two eNBs (primary eNB and secondary eNB), and the two eNBs are connected via the X2 interface in a non-ideal backhaul.

[0076] For a user equipment (UE), an eNB can perform different functions independent of its power level. The role of an eNB can vary depending on the UE. For example, even if the first eNB acts as the primary eNB and the second eNB acts as the secondary eNB for the first UE, the second eNB can also act as the primary eNB and the first eNB can also act as the secondary eNB for the second UE. Dual connectivity is used as a fundamental concept for deploying Multiple Radio Access Technology (RAT) mobile networks in 5G communications. Multiple RAT Dual Connectivity (MR-DC) is a general term referring to various dual connectivity configurations related to 5G communications. A primary Radio Access Network (RAN) node (or primary NodeB) can operate by using a secondary RAN node (or secondary NodeB) as a control entity to obtain additional data capacity through MR-DC.

[0077] LTE's eNB and NR's gNB can be collectively referred to as NB, that is, a node (or NodeB).

[0078] A cell group, which is a collection of serving cells controlled by the same base station, may include a primary cell group (MCG) and a secondary cell group (SCG), and each cell group may include one cell. The cell constituting the cell group may be either an eNodeB for LTE or a gNodeB for NR.

[0079] A primary cell group can refer to a group of serving cells associated with a primary node that includes a primary cell (PCell) and optionally one or more secondary cells (SCells), and a secondary cell group can refer to a group of serving cells associated with a secondary node that includes a PCell and optionally one or more SCells.

[0080] PCell and SCell are terms indicating the type of serving cell configured for a user equipment. Several differences exist between PCell and SCell; for example, a PCell can always remain active, while an SCell can be active or inactive according to instructions from the base station. User equipment mobility can be controlled based on PCell, and an SCell can be understood as an additional serving cell used for data transmission and reception. The PCell and SCell used in this disclosure can refer to PCell and SCell as defined in LTE standards, 5G standards, etc.

[0081] Reference Figure 1 The wireless communication system providing dual connectivity according to embodiments of the present disclosure may include a first NodeB 100 constituting a macro cell, a second NodeB 300 constituting a small cell, and a user equipment 500.

[0082] Macro cells, controlled by macro base stations, can provide service over relatively large areas. Conversely, small cells can provide service over much smaller areas than typical macro cells. While there are no strict guidelines for distinguishing between macro cells and small cells, the area served by a macro cell can typically have a radius of about 500 meters, while the area served by a small cell can typically have a radius of about tens of meters. Here, the terms "pico cell" and "small cell" can be used interchangeably.

[0083] In networks including macrocells, because user equipment located at the cell edge is far from the base station, the quality of the received signal may degrade due to the low strength of the received signal. On the other hand, in networks including small cells, even though user equipment located at the cell edge is close to the base station, making the mutual signal strength measurable as high, the frequent handover between cells may cause system load due to the handover.

[0084] like Figure 1As shown, in a dual-connectivity network between small and macro cells, handover can be performed when user equipment moves between macro cells, while a simple cell change process can be performed when moving between small cells, thereby reducing system load. Furthermore, macro-cell-based connectivity is maintained, allowing for stable cell changes between small cells.

[0085] When using dual connectivity, user equipment throughput can be improved through inter-node radio resource aggregation (INRA), and mobility robustness can be enhanced through RRC diversity.

[0086] like Figure 1 As shown, INRA can provide services to user equipment 500 for user plane transmission by aggregating radio resources provided by one or more NodeBs for user plane data transmission. For this purpose, the second NodeB 300 constituting the macro cell can be configured as a mobility anchor to reduce signaling overhead relative to the core network (CN).

[0087] RRC diversity is a technique that involves sending / receiving RRC signaling related to handover between the source cell and the target cell. Using this technique, user equipment 500 can maintain a connection with at least one cell, thereby minimizing radio link failures (RLF) and improving handover performance.

[0088] In this scenario, the first NodeB 100 and the second NodeB 300 can be either an LTE eNB or an NR gNB. One of the first NodeB 100 and the second NodeB 300 can be a primary node (MN), while the other can be a secondary node (SN). For ease of description, the description of control plane data is omitted in the accompanying drawings.

[0089] Control plane data can be transmitted via signaling from the master node, and control channels can be configured between the master and slave nodes to exchange signaling via the X2 interface. As a master node of an eNB or gNB, it can interwork with a Mobility Management Entity (MME) or Access and Mobility Function (AMF), where the interworking entity and target in the 5G network are determined based on the network deployment scenario. The network deployment scenario will be described later.

[0090] User equipment 500, which is dual-connected with the first NodeB 100 and the second NodeB 300, can receive user plane data from the first NodeB 100 via the first carrier F1 and from the second NodeB 300 via the second carrier F2. In dual connectivity, user plane data can be split from the PDCP layer of the primary or secondary node, and MCG bearers, SCG bearers, or split bearers can be used as data radio bearers (DRBs). The protocols and bearers used for user plane data processing in dual connectivity will be described later.

[0091] Figures 2a to 2d An embodiment for supporting dual connectivity among network deployment options according to the 5G standard is shown.

[0092] In the deployment options according to 5G standard version 15, base station types can include eNB, ng-eNB, en-gNB, and gNB. eNB can refer to an LTE eNB used as a 4G base station, while ng-eNB can refer to an eNB interoperable with 5G Core (5GC) and gNB. en-gNB can refer to a gNB interoperable with Evolved Packet Core (EPC) and eNB, and gNB can refer to an NR gNB used as a base station interoperable with 5G NR and 5GC.

[0093] Among the deployment options based on 5G standard version 15, four options support dual connectivity: Evolved Universal Terrestrial Radio Access (E-UTRA)-NR DC (EN-DC), NG-RAN E-UTRA-NR DC (NGEN-DC), NR-E-UTRA DC (NE-DC), and NR-NR DC (NR-DC).

[0094] Figure 2a The network deployment of EN-DC is shown among the network deployment options according to the 5G standard.

[0095] EN-DC corresponds to deployment option 3 according to 5G standard version 15, where the eNB is the master node, the gNB is the slave node, and the core network is the EPC.

[0096] Option 3 corresponds to the scenario where a gNB is introduced into an existing LTE infrastructure. The core network is the EPC, and the gNB is an en-gNB interoperable with both the EPC and the eNB. Dual connectivity (EN-DC) is supported between the eNB and the en-gNB, with the eNB as the master node. The eNB, acting as the control anchor for the en-gNB, handles control signaling for user equipment network access, connection configuration, handover, etc., and delivers user plane data via the eNB and / or the en-gNB. Due to the use of the LTE system, Option 3 corresponds to Non-Standalone (NSA).

[0097] Option 3 can include three deployment types based on the user plane data splitting scheme: Option 3 / 3a / 3x. Option 3 / 3x can use split bearers, while Option 3a can choose not to use split bearers.

[0098] Option 3: The eNB connects to the EPC, and the en-gNB connects to the eNB. User plane data can be split from the master node and transmitted simultaneously via LTE and NR.

[0099] - Option 3a: Both the eNB and gNB are connected to the EPC, allowing user plane data to be delivered directly from the EPC to the gNB and to either LTE or NR.

[0100] - Option 3x: This is a combination of Option 3 and Option 3a, and the difference from Option 3 is that the user plane data is split from the secondary node.

[0101] Figure 2b The network deployment of NGEN-DC is shown among the network deployment options according to the 5G standard.

[0102] NGEN-DC can correspond to deployment option 7 according to 5G standard version 15, where the eNB is the master node, the gNB is the slave node, and the core network is 5GC.

[0103] The core network can be 5GC, and the eNB can be an ng-eNB interoperable with both 5GC and gNB. Dual connectivity (NGEN-DC) can be supported between the ng-eNB and gNB, with the eNB as the master node. 5GC features can be used, and when 5G coverage is still insufficient, the eNB can provide service continuity by using the eNB as the master node, as in Option 3. Option 7 can correspond to NSA due to the use of the LTE system.

[0104] Option 7 can include three options: 7 / 7a / 7x, based on the user plane data splitting scheme. Options 7 / 7x can use split bearers, while option 7a can choose not to use split bearers.

[0105] Figure 2c The diagram illustrates the NE-DC network deployment option among network deployment options based on the 5G standard.

[0106] NE-DC can correspond to deployment option 4 according to 5G standard version 15, where gNB is the primary node, eNB is the secondary node, and the core network is 5GC.

[0107] 5GC is introduced and NE-DC still interoperates with LTE, but standalone 5G communication can also be performed. The core network can be 5GC, and the eNB can be an ng-eNB interoperable with both 5GC and gNB. Dual connectivity (NE-DC) can be supported between ng-eNB and gNB, and the master node can be a gNB. In this case, 5G NR coverage is sufficiently extended, and LTE can be used as a capacity enhancer. Option 4 can include two types: Option 4 / 4a.

[0108] Figure 2d The diagram illustrates the NR-DC network deployment option among network deployment options based on the 5G standard.

[0109] NR-DC can correspond to deployment option 2 according to 5G standard version 15, where the primary and secondary nodes are gNBs and the core network is 5GC.

[0110] This option can be a deployment option that can provide standalone 5G services using only 5G systems (5GC and gNB), and can be standalone (SA). Ultra-reliable low-latency communication (URLLC) and massive machine-type communication (mMTC) in addition to enhanced mobile broadband (eMBB) can be possible, and 5G features such as network slicing and mobile edge computing (MEC) support can be used, where full 5G services can be provided and the NR-DC can be a single RAT.

[0111] Figure 3 Various bearer types for dual connections are shown.

[0112] User equipment can be configured to operate in dual connectivity mode, wherein when a bearer (or data radio bearer) established on the serving cell of the primary node has a PDCP anchor point that terminates in the primary node, the bearer can be referred to as an MN-terminated MCG bearer, and when the bearer has a PDCP anchor point that terminates in the secondary node, the bearer can be referred to as an SN-terminated MCG bearer.

[0113] Alternatively, when a bearer established on the serving cell of a secondary node has a PDCP anchor that terminates in the secondary node, the bearer can be referred to as an SN-terminated SCG bearer, and when the bearer has a PDCP anchor that terminates in the primary node, the bearer can be referred to as an MN-terminated SCG bearer.

[0114] User equipment may include a split bearer in which PDCP PDUs can be sent through two RLC entities established in the primary and secondary nodes for the purpose of splitting the bearer.

[0115] The PDCP anchor point of a split-bearer can be configured to terminate in either the primary or secondary node, and the node in which the PDCP anchor point terminates can be determined by the primary node.

[0116] When the PDCP termination point of a split bearer is the primary node, the bearer can be called an MCG split bearer, while when the PDCP termination point of a split bearer is the secondary node, the bearer can be called an SCG split bearer.

[0117] In the case of interoperability between LTE and NR based on dual connectivity, that is, in the EN-DC operation mode where the primary node is an LTE eNB and the secondary node is an NR gNB, the MCG bearer can include either LTE PDCP or NR PDCP, the SCG bearer can be configured for NR PDCP, and the split bearer can be configured for NR PDCP, regardless of the PDCP termination point.

[0118] However, for user equipment, there are three types of bearers: MCG bearers, SCG bearers, and split bearers. Split bearers can be terminated on the primary node or on the secondary node based on the determination of the primary node.

[0119] In EN-DC, split bearers can include NR PDCP containers, RLC, MAC and LTE configuration on the physical layer, RLC, MAC and NR configuration containers on the physical layer, etc.

[0120] A split bearer with its PDCP termination point located in the primary node can be referred to as an MN-terminated split bearer or an MCG split bearer. A split bearer with its PDCP termination point located in the secondary node can be referred to as an SN-terminated split bearer or an SCG split bearer.

[0121] Figure 4 An example of a 5G NGEN-DC NSA network architecture is shown.

[0122] Reference Figure 4 The NGEN-DC NSA network architecture can include a core network 700, user equipment 500, gNB 100, and eNB 300.

[0123] In the NGEN-DC network architecture, gNB 100 can correspond to the master node, and the NR PDCP 110 of gNB 100 can split user plane data. gNB 100 may include NR PDCP 110, NR RLC 130, and NR MAC 150, while eNB300 may include NR PDCP (not shown), LTE RLC 330, and LTE MAC 350. For other terminals where eNB 300 is the master node, the NR PDCP of eNB 300 can be used as a split bearer, but in... Figure 4 The description of NR PDCP for eNB 300 has been omitted.

[0124] In the NGEN-DC network architecture, the core network 700 can correspond to 5GC and its architecture will not be described in detail.

[0125] User equipment 500 may include: NRMAC 551 and NR RLC 531 corresponding to the protocol stack for processing data received from gNB 100, and LTEMAC 552 and LTE RLC 532 corresponding to the protocol stack for processing data received from eNB 300. User equipment 500 may also include a higher-level protocol stack of NR PDCP 510 and Transmission Control Protocol (TCP) / Internet Protocol (IP) 570.

[0126] Assume that NR PDCP 110 receives 10 packets from core network 700 and the split ratio of the bearer is α = 0.7. For ease of description, the packets are numbered from 1 to 10 according to their transmission order.

[0127] The split ratio, referring to the proportion of data to be sent to the primary and secondary nodes, can be determined based on the amount of data to be sent, the service provider, the type of service, the transmission rates of the primary and secondary nodes, channel conditions, etc., and can be implemented in various ways. When the split ratio is determined incorrectly, reordering delays occur due to packet reception delays, resulting in increased packet latency. Such increased packet latency can cause data loss based on the expiration of the reordering timer, which will be described later.

[0128] The NR PDCP 110 can determine, based on the split ratio α, which packets to be transmitted to the user equipment (not shown) via the gNB 100 and which packets to be transmitted to the user equipment (not shown) via the eNB 300. Figure 4 In the illustrated embodiment, packets 2, 3, 5, 6, 8, 9, and 10 can be delivered from NR PDCP 110 to NR RLC 130, while packets 1, 4, and 7 can be delivered from NR PDCP 110 to LTE RLC 330.

[0129] The NR RLC 130 can deliver packets 2, 3, 5, 6, 8, 9, and 10 to the NR MAC 350, while the LTE RLC 330 can deliver packets 1, 4, and 7 to the LTE MAC 350.

[0130] User equipment 500 can identify packets received via the PHY layer based on the transmission entity to deliver packets 2, 3, 5, 6, 8, 9 and 10 sent from gNB 100 to NR MAC 551 and packets 1, 4 and 7 sent from eNB 300 to LTE MAC 552.

[0131] NR MAC 551 and LTE MAC 552 can deliver the obtained packets to NR RLC 531 and LTE RLC 532, which in turn can deliver the obtained packets to NR PDCP 510.

[0132] The NR PDCP 510 of the user equipment 500 can reorder the acquired packets so that the acquired packets are in the order they were delivered in the sending PDCP rather than in the order they were received; and can deliver the reordered packets to the TCP / IP layer.

[0133] Figures 5a to 5e This is a view used to describe a situation where the reordering timer of a user equipment according to an embodiment of the present disclosure expires due to packet reception delay.

[0134] exist Figure 4 In the illustrated embodiment, when the NR PDCP 110 of gNB 100 delivers packets 2, 3, 5, 6, 8, 9, and 10 to NR RLC 130 and packets 1, 4, and 7 to LTE RLC 330, NR RLC 130 and LTE RLC 330 can store the received packets in a buffer and deliver these packets to NR RLC 130 and LTE RLC 330 according to the system state. Figures 5a to 5e In one embodiment, every three packets received by user equipment 500 can be grouped in NR PDCP 510 and delivered to TCP / IP 570.

[0135] Figure 5a It shows in Figure 4 The embodiment shown illustrates the received packet state of the NR PDCP510 layer of the user equipment 500 when there is a delay in receiving packet 4.

[0136] Reference Figure 5aThe delivery of packet 4 is delayed in the LTE RLC 330 of eNB 300, and as a result, NR PDCP 510 of user equipment 500 has received packets 1, 2, 3, and 5. Therefore, NR PDCP 510 of user equipment 500 can deliver the received packets 1, 2, and 3 to TCP / IP 570, where packet 5 was received before packet 4 was received, allowing user equipment 500 to start a reordering timer from the time packet 5 was received and wait for the reception of packet 4.

[0137] When user equipment 500 waits for unreceived packets in order to deliver them to higher layers in sequence, a reordering timer can be used to determine the time for waiting for packets. The reordering timer can be set when an unreceived packet occurs, and if the packet is not received within a preset time, the reordering timer can expire, and user equipment 500 can abandon receiving the packet and process it later.

[0138] However, in Figures 5a to 5e The description uses an example where the delay in receiving packets in user equipment 500 is caused by buffering at the sending end (e.g., gNB 100 or eNB 300), but this disclosure is not limited thereto.

[0139] Figure 5b It shows in Figure 5a The state after which the NR PDCP layer 510 of user equipment 500 receives packets when there is a delay in receiving packet 7.

[0140] Reference Figure 5b The delivery of packet 7 is delayed in the LTE RLC 330 of eNB 300, and NR PDCP 510 of user equipment 500 has received packets 5, 6, and 8. In this case, packets 1, 2, and 3, which have already been delivered to TCP / IP 570, will not be described.

[0141] The earliest of the unreceived packets (packets 4 and 7) is still not received, so the reordering timer continues and the NR PDCP 510 of user equipment 500 can continue to wait for the reception of packet 4.

[0142] Figure 5c It shows in Figure 5b After the state of receiving packet 4, the NR PDCP layer 510 of user equipment 500 receives packet 4.

[0143] Reference Figure 5c ,exist Figure 5bAfter the status is reached, packet 4 can be delivered from the LTE RLC 330 of eNB 300 to the LTE MAC 350, and then the NR PDCP 510 of user equipment 500 may have successfully received packet 4.

[0144] User equipment 500's NR PDCP 510 can deliver received packets 4, 5, and 6 to TCP / IP 570 when it receives packet 4, which user equipment 500 is waiting to receive. Since the reception of packet 4 has triggered a reordering timer, user equipment 500 can reset the reordering timer and wait for the reception of packet 7. The reference time for reordering the timer can be set to the time when packet 8, immediately following the unreceived packets, is received.

[0145] Figure 5d It shows in Figure 5c After the state of the NRPDCP layer 510 of user equipment 500 expires, the receive packet state will be determined.

[0146] Reference Figure 5d Even in Figure 5c Following this state, the delivery of packet 7 was also continuously delayed in the LTE RLC 330 of the eNB 300, while the NR PDCP 510 of the user equipment 500 had already received packets 8, 9, and 10. Similarly, the description of packets 1, 2, 3, 4, 5, and 6, which have already been delivered to TCP / IP 570, will be omitted.

[0147] If packet 7 is not received before the reordering timer, which started from the time packet 8 was received, expires, the NR PDCP 510 of user equipment 500 may abandon the reception of packet 7 and deliver subsequent packets 8, 9 and 10 to TCP / IP 570 due to the extended reception delay of packet 7.

[0148] Figure 5e It shows Figure 5d The TCP / IP 570 layer receive packet status of user equipment 500 in the illustrated embodiment.

[0149] After the NR PDCP 510 of User Equipment 500 abandons the reception of packet 7 due to the expiration of the reordering timer for packet 7 and delivers packets 8, 9, and 10 to TCP / IP 570, packet 7 is lost in TCP / IP 570. When the reordering timer expires, not only packet 7 but also consecutive packets sent after packet 7 through the same cell group are discarded together, causing large-scale data loss at the receiving end.

[0150] Furthermore, when packets are lost due to the reordering timer expiring, the TCP congestion control algorithm runs due to a retransmission timeout (RTO) at the sender, which drastically reduces TCP throughput.

[0151] When the expiration of the reordering timer is anticipated, retransmission of packets that trigger the reordering timer (i.e., packets with reception delay) through a node different from the existing node can prevent the expiration of the reordering timer in the user equipment and reduce large-scale data loss and transmission rate loss caused by the expiration of the reordering timer.

[0152] Figure 6 This is an operation flowchart of a wireless communication system according to an embodiment of the present disclosure.

[0153] Reference Figure 6 The wireless communication system according to embodiments of the present disclosure may include a first cell group 100, a second cell group 300, and a user equipment 500.

[0154] In a dual-connectivity environment, User Equipment 500 can connect to two cell groups, which can be controlled and managed by a split bearer. Splitting, i.e., data splitting, can be performed in PDCP, and the split data can be delivered via the RLC, MAC, and PHY of each of the two cell groups.

[0155] In embodiments of this disclosure, PDCP may be included in either the first cell group 100 or the second cell group 300, but in Figure 3 In this context, PDCP can be included in the first cell group 100.

[0156] In operation S610, the first cell group 100 can obtain at least one packet to be sent from the core network (not shown) to the user equipment 500.

[0157] The core network can refer to the higher-level network of the RAN, and can be either the EPC or the 5GC.

[0158] In operation S620, the first cell group 100 can determine from the packets obtained from the core network (not shown) which packets to be sent to the user equipment 500 via the first cell group 100 and which packets to be sent to the user equipment 500 via the second cell group 300.

[0159] The split bearer can classify the data to be sent to the first cell group 100 and the data to be sent to the second cell group 300 based on the data split comparison.

[0160] The data split ratio can be determined based on at least one of the following: parameters for quality of service or parameters for system requirements (Quality of Service (QoS) Class Identifier (QCI)), Guaranteed Bit Rate (GRP), Allocation and Reservation Priority (ARP), Maximum Bit Rate (MBR), Access Point Name-Aggregated Maximum Bit Rate (APN-AMBR), or User Equipment-Aggregated Maximum Bit Rate (UE-AMBR).

[0161] As mentioned above, in Figure 6 In the illustrated embodiment, the PDCP can be included in the first cell group 100, and the split bearer can perform data replication and routing in the sending PDCP entity (i.e., the PDCP of the first cell group 100).

[0162] In operation S621, the first cell group 100 (e.g., PDCP) may deliver (S621) packets to be sent to the user equipment 500 via the second cell group 300 (e.g., RLC) to the second cell group 300, and deliver (not shown) packets to be sent to the user equipment 500 via the first cell group 100 to the lower layer (e.g., RLC) of the first cell group 100.

[0163] When a PDCP PDU is requested to be submitted from a lower layer in a split bearer, the sending PDCP entity can deliver data to both Acknowledgment Mode (AM) RLCs by using the protocols defined in the system.

[0164] In operation S630, the second cell group 300 can obtain packets to be sent to the user equipment 500 via the second cell group 300, and in operation S631, the second cell group 300 can send the obtained packets to the user equipment 500 via MAC and PHY.

[0165] In operation S631, user equipment 500 can receive packets from second cell group 300 and receive (not shown) packets from first cell group 100.

[0166] The receiving PDCP entity (i.e., the PDCP of user equipment 500) can perform reordering of received data and discarding data that has been fully delivered to higher layers.

[0167] According to embodiments of this disclosure, packets transmitted from the core network to the user equipment 500 can be sent from the first cell group 100 and the second cell group 300 to the user equipment 500 during the above-described process. In this case, the wireless network environment between the first cell group 100 and the user equipment 500 and the wireless network environment between the second cell group 300 and the user equipment 500 can be different from each other. Even within a single cell group and the user equipment 500, the wireless network environment for delivering the time-frequency resource blocks of each packet can differ.

[0168] Therefore, each packet can have a different time delay depending on the wireless network environment, and the order in which packets are received in the user equipment 500 may differ from the order in which they are sent. The user equipment 500 can process the received packets through the user plane protocols PHY, MAC, RLC, PDCP, and TCP / IP. In this case, the PDCP of the user equipment 500 can reorder the received packets so that their order follows the order in which they were delivered in the sending PDCP rather than the order in which they were received; and the reordered packets can be delivered to the TCP / IP layer.

[0169] In operation S640, when there is a packet that has not been received from the second cell group 300, the user equipment 500 can wait for the reception of the unreceived packet and set a reordering timer to deliver the received packet to the TCP / IP layer in order.

[0170] In operation S641, user equipment 500 may feed back information about the status of packets received from second cell group 300 to second cell group 300. According to embodiments of this disclosure, the information about the status of packets received from second cell group 300 fed back by user equipment 500 may include HARQ feedback during the HARQ process.

[0171] In operation S650, the second cell group 300 can update the packet delivery status information of the second cell group 300 based on the information about the packet status fed back from the user equipment 500.

[0172] According to embodiments of this disclosure, packet delivery status information may include downlink data delivery status (DDDS). DDDS may include information delivered from the distribution unit (DU) of the NodeB to the central unit (CU), and may refer to periodic feedback information that enables the NR PDCP included in the CU to control the user data flow via the DU.

[0173] Each node (i.e., each base station) can be split into two parts, a CU and a DU, which are connected via an F1 interface. For example, in a 5G network, the PDCP layer can be included in the CU and the RLC, MAC, and PHY layers can be included in the DU, but the configuration of the CU and DU is not limited to this and can vary depending on how the system is implemented. According to another embodiment of this disclosure, the base station can be split into a CU, a DU, and a radio unit (RU).

[0174] By identifying CU and DU, network functions can be virtualized, leading to improved system implementation flexibility and reduced costs. For example, even when low-level virtualization is difficult to implement, low-level (DU) and high-level (CU, e.g., a layer higher than PDCP) layers can be separated, allowing the high-level layers to be implemented as an open protocol stack.

[0175] In operation S651, the second cell group 300 can send updated packet delivery status information to the first cell group 100.

[0176] In operation S660, the first cell group 100 can determine whether to perform packet retransmission based on the packet delivery status information of the second cell group 300.

[0177] More specifically, the RLC of the first cell group 100 can deliver packet delivery status information obtained from the second cell group 300 to the PDCP, and the PDCP that has obtained the packet delivery status information of the second cell group 300 from the RLC can determine whether to retransmit packets that have not been received in the user equipment 500, i.e., packets that the user equipment 500 is waiting to receive, based on the packet delivery status information of the second cell group 300.

[0178] When a packet is not received and therefore the user equipment 500 waits for its reception in order to deliver it in order, the unconditional waiting for the packet to be received can be inefficient for the management of wireless communication resources. Therefore, if no packet is received until a certain time has elapsed after the reordering timer is set, the user equipment 500 can discard the packet without waiting for its reception and process subsequent packets.

[0179] However, in this scenario, not only the packet but also subsequent packets sent through the same cell group may be dropped together, causing large-scale data loss at the receiving end. Furthermore, when packets are lost due to reordering timer expiration, the TCP congestion control algorithm may run due to RTO occurring at the sending end, drastically reducing TCP throughput.

[0180] TCP congestion control algorithms can refer to techniques used to control the operation of each entity to prevent it from exacerbating network congestion by determining that packet loss is caused by network congestion.

[0181] A limited congestion control scheme can apply the Karn algorithm by taking into account the round-trip time (RTT) deviation and double the RTO time used for congestion control by operating on retransmissions.

[0182] The integrated congestion control scheme can operate in a slow-start mode when an RTO occurs, delivering data at a low data transmission rate in the early stages of the connection and gradually increasing the amount of data transmitted, thereby suppressing segmented transmission rates in advance. Subsequently, congestion avoidance, fast retransmission, and fast recovery can be used together to control the data transmission rate.

[0183] Therefore, the TPC transmission rate drops sharply when the reordering timer expires, allowing PDCP to retransmit packets before the reordering timer expires so that the user equipment can receive packets.

[0184] A detailed method for determining whether to retransmit a packet according to embodiments of this disclosure will be described later.

[0185] When packet retransmission is determined in operation S660, the first cell group 100 can send the packet determined to be retransmitted to the user equipment 500 via the first cell group 100 in operation S661.

[0186] More specifically, when packet retransmission is determined, PDCP can duplicate the packet to send the determined packet via the first cell group 100 and send the packet via the user plane protocol of the first cell group 100.

[0187] In operation S670, a user equipment 500 that has received a retransmitted packet from the first cell group 100 can deliver the retransmitted packet to a higher layer and deliver subsequent packets to the higher layer in sequence.

[0188] The receiving PDCP entity (i.e., the PDCP of user equipment 500) can perform reordering of received data and discarding of received data.

[0189] For example, when delivering PDUs from a lower layer to the PDCP, the user equipment 500 can determine the order of the received packets based on the PDCP sequence number (SN) of the packets received in the data PDU, the PDCP SN of the preceding packet, and the PDCP SN of the next packet.

[0190] In this case, the reordering timer set in operation S640 can be reset (or restarted), and the reordering timer can be reset when a packet reception wait occurs for in-order delivery.

[0191] Despite Figure 6Although not shown in the diagram, packets determined to be transmitted via the first cell group 100 in operation S620 can be sent to the user equipment 500 via the RLC, MAC, and PHY of the first cell group 100. When no packet to be transmitted to the user equipment 500 via the first cell group 100 is received, the user equipment 500 can feed back information about the status of the received packet to the first cell group 100.

[0192] The first cell group 100 can update its packet delivery status information based on packet status information received from the user equipment 500, and can determine whether to retransmit the packet based on the updated packet delivery status information. When it is determined that the packet should be retransmitted, the first cell group 100 can copy the packet to be retransmitted and deliver the packet to the second cell group 300, which can then retransmit the packet to the user equipment 500.

[0193] In other words, according to embodiments of this disclosure, based on whether the transmission of the PDCP PDU delivered from the RLC to the PDCP via DDDS is successful, the state of packets can be managed in the PDCP, the expiration of the reordering timer can be predicted, and when the expiration of the reordering timer is expected, the packets that caused the reordering timer to be started can be copied and retransmitted, thereby preventing packet loss.

[0194] Figures 7 to 8d This is a view used to describe a data transmission method in a wireless communication system according to embodiments of the present disclosure.

[0195] Figure 7 An embodiment of split bearer in an NGEN-DC NSA network according to an embodiment of the present disclosure is shown.

[0196] Reference Figure 7 The wireless communication system according to embodiments of this disclosure may include a gNB 100 and an eNB 300, and due to the NGEN-DC network architecture, an NR PDCP for data splitting may be included in the gNB 100. The gNB 100 may include an NR PDCP 110, an NR RLC 130, and an NR MAC 150, while the eNB 300 may include an NR PDCP (not shown), an LTE RLC 330, and an LTE MAC 350. For other terminals where the eNB 300 is the master node, the NR PDCP of the eNB 300 can be used as a splitting bearer, but in... Figure 7 The description of NR PDCP for eNB 300 has been omitted.

[0197] Although the description herein will be made with reference to a particular network (e.g., NGEN-DC NSA) for convenience, the network architecture to which this disclosure applies is not limited thereto, and this disclosure applies to any network system that supports dual connectivity and uses split bearers.

[0198] Assume that NR PDCP 110 receives 10 packets from the core network (not shown) and the split ratio of the split bearer is α = 0.4. For ease of description, the packets are numbered from 1 to 10 according to their transmission order.

[0199] The NR PDCP 110 can determine, based on the split ratio α, which packets to be transmitted to the user equipment (not shown) via the gNB 100 and which packets to be transmitted to the user equipment (not shown) via the eNB 300. Figure 7 In the illustrated embodiment, packets 2, 4, 5, and 10 can be delivered to NRRLC 130, and packets 1, 3, 6, 7, 8, and 9 can be delivered to LTE RLC 330.

[0200] The NR RLC 130 can deliver packets 2, 4, 5, and 10 to the NR MAC 350 and store the packet delivery status in the DDDS. Subsequently, when information about the reception status of each packet is fed back from the user equipment (not shown), the DDDS can be updated based on the fed-back information, and the updated DDDS can be delivered to the NR PDCP 110.

[0201] Similarly, the LTE RLC 330 can deliver packets 1, 3, 6, 7, 8, and 9 to the LTE MAC 350 and store the packet delivery status in the DDDS. Subsequently, when information about the reception status of each packet is fed back from the user equipment (not shown), the DDDS can be updated based on the fed-back information, and the updated DDDS can be delivered to the NR PDCP 110.

[0202] The NR PDCP 110, which has obtained DDDS for NR RLC 130 and DDDS for LTE RLC 330, can manage downlink packet status based on DDDS for NR RLC 130 and DDDS for LTE RLC 330.

[0203] [Formula 1]

[0204] T reordertimer -(T real -T reorder ) <TH duplication

[0205] exist Figure 8c In the embodiment shown, T real It can be approximately 46ms, Treorder It can be approximately 16ms, and T reorder It can take about 50ms.

[0206] Therefore, the left side of Equation 1 can be equal to approximately 20ms, and this value is less than the threshold TH set in the system. duplication At this time, the NR PDCP can copy packet 2 that caused the reception delay and retransmit packet 2 to the gNB. The 833 can indicate the status of each of the first to tenth packets after the packet retransmission at the current time of 46 ms. For ease of description, packets are numbered from 1 to 10 according to the transmission order of each packet.

[0207] It is anticipated that the reordering timer will expire after 20 ms, enabling the data transmission apparatus according to an embodiment of the present disclosure to copy packet 2, which was delayed upon reception, in the user equipment and retransmit packet 2 to gNB 100.

[0208] Figure 8d It is used in Figure 8c The illustrated embodiment describes a view of the downlink packet state managed in the NR PDCP 110 after packet retransmission.

[0209] exist Figure 8c In the illustrated embodiment, NR PDCP 110 can copy packet 2 that is delayed upon reception in the user equipment and retransmit packet 2 to gNB 100. The user equipment can receive packet 2 and send an acknowledgment (ACK) of the reception of packet 2 back to gNB 100, and NR RLC 130 can deliver an updated DDDS based on the feedback information to NR PDCP 110.

[0210] Subsequently, it can be seen from the downlink packet status 841 managed by PDCP 110 at the current time of 56 ms that the status of packet 2, which was delayed at the time of reception, and the status of packet 3, which was waiting to be delivered in order, have been updated to the in-order delivery completed status.

[0211] Figure 9 This is a view used to describe a method for determining cell group copy and retransmit packets according to embodiments of the present disclosure.

[0212] Figure 8c This shows the duration of the reordering (i.e., the elapsed time since the start of the reordering) T. reorder -T real Greater than the reordering timer setting value T reordertime With a certain threshold TH duplication An example of replicating packets with transmission delays between time differences.

[0213] According to another embodiment of this disclosure, split bearer (or NR PDCP) can determine whether to duplicate packets with transmission delays by using an artificial intelligence (AI) model. In this case, the AI ​​model can determine whether to duplicate packets by receiving information about the current packet transmission status (e.g., Figure 8c The 831) was used as input for training, and the trained AI model was used to determine whether to replicate the group (e.g., Figure 8c (833). The RLC buffer state can be used as an additional input.

[0214] Figure 10 This is a view used to describe a method for retransmitting duplicated packets in a cell group according to embodiments of the present disclosure.

[0215] The packets identified as needing to be copied using the above method are likely to cause the reordering timer to expire due to reception delays in the user equipment. Therefore, when the expiration of the reordering timer is anticipated, transmission priority can be given to the packets that are likely to cause the reordering timer to expire.

[0216] In this scenario, the PDCP can indicate that the packet is a duplicate and deliver the duplicate packet to the RLC. The RLC can recognize this indication and insert the packet at the front of its buffer queue to prioritize sending duplicate packets over other packets. A separate control bit can be added to indicate that the packet is a duplicate.

[0217] Figure 11 This is a flowchart of a data transmission method according to an embodiment of the present disclosure.

[0218] Below, in Figure 11 In the description, omission and Figure 6 The description is redundant and lacks detailed description.

[0219] Figure 11 Each operation can be performed by the cell group that includes the split bearer in the first cell group and the second cell group that are dual-connected to the user equipment, and for the sake of convenience, the split bearer is assumed to be included in the first cell group.

[0220] In operation S1110, the first cell group can obtain at least one packet to be sent to the user equipment from the core network. The core network can be either EPC or 5GC, and can be determined according to the network deployment scenario.

[0221] In operation S1120, the first cell group can determine from the packets obtained from the core network which packets to be sent to the user equipment via the second cell group. Similarly, the first cell group can determine from the packets obtained from the core network which packets (not shown) to be sent to the user equipment via the first cell group.

[0222] In operation S1130, the first cell group (e.g., PDCP) may deliver packets determined to be transmitted to the user equipment via the second cell group (e.g., RLC). Similarly, the first cell group may deliver packets determined to be transmitted to the user equipment via the first cell group to a lower layer (e.g., RLC) of the first cell group (not shown).

[0223] Packets destined for the second cell group can be delivered to the user equipment via the RLC, MAC, and PHY layers of the second cell group. The user equipment that has received a packet can provide an ACK (e.g., HARQ) regarding the packet reception to both the first and second cell groups, and the second cell group can update the packet delivery status (e.g., DDDS) based on the feedback signal received from the user equipment. Similarly, the first cell group can update the packet delivery status (e.g., DDDS) based on the feedback signal received from the user equipment.

[0224] In operation S1140, the first cell group can obtain the packet delivery status of the first cell group and the packet delivery status of the second cell group.

[0225] For example, the NR PDCP of the first cell group can periodically receive the DDDS of the first cell group from the RLC of the first cell group, and periodically receive the DDDS of the second cell group from the RLC of the second cell group.

[0226] In operation S1150, the first cell group can determine whether to perform packet retransmission based on the packet delivery status of the first cell group and the packet delivery status of the second cell group.

[0227] For example, when the reordering timer expires as expected for a packet transmitted via a second cell group, the first cell group can determine to retransmit the packet. According to embodiments of this disclosure, the decision to retransmit the packet can be based on the duration of the reordering timer, the reordering timer expiration setting time, and a certain threshold.

[0228] When a packet retransmission is determined in operation S1150, in operation S1160, the first cell group can send the packet to be retransmitted to the user equipment via the first cell group.

[0229] More specifically, when a packet retransmission is determined, the PDCP of the first cell group can duplicate the packet to send the determined packet via the first cell group, and the packet can be sent via the user plane protocol of the first cell group. According to embodiments of this disclosure, the packet determined to be retransmitted can be duplicated and sent quickly over other packets.

[0230] Figure 12This is a block diagram of a data transmission apparatus 1200 according to an embodiment of the present disclosure.

[0231] like Figure 12 As shown, the data transmission apparatus 1200 according to this disclosure may include a processor 1210, a communicator 1220, a memory 1230 and an interface 1240 as a cell group including split bearers.

[0232] However, the components of the data transmission device 1200 are not limited to the examples described above. For instance, the data transmission device 1200 may include more or fewer components than those described above. Furthermore, the processor 1210, communicator 1220, memory 1230, and interface 1240 may be implemented on a single chip. Figure 12 In the data transmission device 1200, components related to this embodiment are shown. Therefore, those skilled in the art will understand that, in addition to Figure 12 Other general components besides those shown may also be included in the data transmission device 1200.

[0233] Processor 1210 can control Figures 1 to 11 The series of processes described herein for sending data (e.g., packets).

[0234] More specifically, processor 1210 can control components of data transmission device 1200 to predict the expiration of the user equipment's reordering timer and copy and retransmit packets that triggered the reordering timer's receive delay. Multiple processors 1210 may be provided, and processor 1210 can perform the above-described retransmission operation by executing multiple instructions (or programs) stored in memory 1230.

[0235] According to embodiments of this disclosure, processor 1210 can control Figures 1 to 11 The illustrated cell group or split bearer can be used to execute a series of processes. For example, the cell group or split bearer can be implemented as multiple instructions (or programs). The processor 1210 can perform cell group or split bearer operations by executing multiple instructions (or programs).

[0236] The processor 1210 can control the overall functions of the data transmission device 1200. For example, the processor 1210 can typically control the data transmission device 1200 by running a program stored in the memory 1230 included in the data transmission device 1200. The processor 1210 can be implemented using, but is not limited to, a central processing unit (CPU), a graphics processing unit (GPU), an application processor (AP), etc., included in the data transmission device 1200.

[0237] The communicator 1220 can establish a connection with another device and send and receive data by using a wired / wireless communication module.

[0238] Communicator 1220 can transmit signals to and receive signals from external devices (e.g., user equipment), networks (e.g., core networks), or other data transmission devices (e.g., cell groups). The signals transmitted and received by communicator 1220 may include control information and data. Communicator 1220 may include an RF transmitter and an RF receiver, wherein the RF transmitter up-converts and amplifies the frequency of the transmitted signal, and the RF receiver amplifies the received signal with low noise and down-converts the frequency. However, this is merely an example of communicator 1220, and the components of communicator 1220 are not limited to RF transmitters and RF receivers.

[0239] The communicator 1220 can receive signals through a wireless channel and output the received signals to the processor 1210, and also transmit signals output from the processor 1210 through a wireless channel.

[0240] According to embodiments of this disclosure, the communicator 1220 can send data or signals to and receive data or signals from external devices, networks, or other data transmission devices under the control of the processor 1210.

[0241] The memory 1230 can be hardware that stores various types of data processed in the data transmission device 1200, and for example, the memory 1230 can store data received, processed, or to be processed by the communicator 1220.

[0242] According to embodiments of this disclosure, multiple instructions (or programs) and data required for the operation of the data transmission device 1200 may also be stored in the memory 1230. The memory 1230 may also store control information or data included in signals sent and received by the data transmission device 1200. The memory 1230 may include storage media such as or combinations thereof: read-only memory (ROM), random access memory (RAM), hard disk, optical disc (CD)-ROM, digital versatile disc (DVD), etc. Multiple memories 1230 may be provided. The interface 1240 can send and receive data and commands for interoperability between internal components of the data transmission device 1200.

[0243] The methods according to embodiments of this disclosure described in the claims or specification of this disclosure may be implemented as hardware, software, or a combination thereof.

[0244] When the method is implemented as software, a computer-readable storage medium or computer program product may be provided in which one or more programs (software modules) are stored. One or more programs stored in the computer-readable storage medium or computer program product may be configured to be executed by one or more processors in an electronic device. One or more programs include instructions that cause the electronic device to perform the method according to embodiments of this disclosure as described in the claims or specification of this disclosure.

[0245] These programs (software modules and software) can be stored in the following: RAM, non-volatile memory including flash memory, ROM, electrically erasable programmable ROM (EEPROM), disk storage devices, CD-ROMs, DVDs, other types of optical storage devices, or magnetic tape cartridges. Programs can be stored in memories configured through some or all of these storage devices. Additionally, each memory can be provided in multiple locations.

[0246] The program can be stored in an attachable storage device of an electronic device that is accessible via a communication network such as the Internet, intranet, local area network (LAN), wireless local area network (WLAN), or storage area network (SAN), or a communication network formed by combining these networks. The storage device can access a device executing embodiments of this disclosure via an external port. Furthermore, a separate storage device within the communication network can access a device executing embodiments of this disclosure.

[0247] In this disclosure, the terms "computer program product" or "computer-readable medium" can be used to generally refer to memory, hard disks mounted in hard disk drives, signals, etc. According to this disclosure, such "computer program product" or "computer-readable medium" can be a means of providing software including instructions for setting the length of a timer for receiving lost data packets in a computer system based on network metrics corresponding to determined events.

[0248] Machine-readable storage media can be provided in the form of non-transitory storage media. The term "non-transitory storage media" simply means that the storage media is a tangible device and does not include signals (e.g., electromagnetic waves), but this term does not distinguish between cases where data is stored semi-permanently and cases where data is stored temporarily. For example, a "non-transitory storage media" may include a buffer in which data is temporarily stored.

[0249] According to embodiments of this disclosure, methods according to various embodiments of this disclosure can be included and provided in a computer program product. The computer program product can be traded as a product between a seller and a buyer. The computer program product can be distributed in the form of a machine-readable storage medium (e.g., an optical disc read-only memory (CD-ROM)) or via an app store (e.g., the Play Store). TM Online distribution (e.g., downloading or uploading) of computer program products, or direct distribution between two user devices (e.g., smartphones). When distributed online, at least a portion of the computer program product (e.g., a downloadable app) may be temporarily generated or at least temporarily stored in a machine-readable storage medium such as the memory of a manufacturer's server, an app store's server, or a relay server.

[0250] In the detailed embodiments of this disclosure, the components included in this disclosure have been expressed as singular or plural. However, for the purposes of description, singular or plural representations have been suitably chosen, and this disclosure is not limited to singular or plural components; a component expressed as plural may be configured as a single component, or a component expressed as singular may be configured as a plural component.

[0251] While embodiments of the present disclosure have been described, various changes may be made without departing from the scope of the disclosure. Therefore, the scope of the disclosure should be defined by the appended claims and their equivalents, and not by the described embodiments.

Claims

1. A data transmission method performed by a node of a dual-connection DC, the data transmission method comprising: Obtain at least one packet from the core network CN to be sent to the user equipment UE via the first or second node; Determine a first packet to be sent via the first node from among the at least one packet; Obtain first packet delivery status information corresponding to the first node generated at the Radio Link Control (RLC) layer of the first node, wherein the first packet delivery status information indicates that the first packet was not received at the UE; Obtain the second packet delivery status information corresponding to the second node generated at the RLC layer of the second node; Based on the first packet delivery status information and the second packet delivery status information, predict the expiration of the UE's timer related to packet delay; and In response to the predicted expiration of the timer, a determination is made as to whether to retransmit the first packet to the UE via the second node. Wherein, the node is either the first node or the second node. Wherein, the timer of the UE related to the packet delay is the UE's reordering timer, and The prediction of the UE's reordering timer expiration includes setting T... reordertimer -(T real -T reorder ) is compared with a certain threshold, and T reordertimer T represents the time the UE waits for the transmitted packet. real T represents the current time. reorder This indicates the time when the reordering timer is started in the UE.

2. The data transmission method according to claim 1, wherein, Predicting the expiration of the UE's timer related to the packet delay includes: inputting the current first packet delivery status information and the current second packet delivery status information into an artificial intelligence (AI) model trained based on the first packet delivery status information and the second packet delivery status information.

3. The data transmission method according to claim 1, wherein, The first packet delivery status information and the second packet delivery status information are determined based on feedback information received from the UE.

4. The data transmission method according to claim 1, wherein, The first packet delivery status information includes the downlink data delivery status (DDDS) of the RLC layer of the first node, and The second packet delivery status information includes the DDDS of the RLC layer of the second node.

5. The data transmission method according to claim 1, wherein, The first packet is retransmitted via the second node with priority over other packets.

6. A data transmission node for a dual-connection DC, the data transmission node comprising: transceiver; processor; as well as A memory storing instructions that, when executable by the processor, configure the data transfer node to: Obtain at least one packet from the core network (CN) to be transmitted to the user equipment (UE) via the first or second node. Among the at least one packet, determine the first packet to be sent via the first node. Obtain first packet delivery status information corresponding to the first node, generated at the Radio Link Control (RLC) layer of the first node, wherein the first packet delivery status information indicates that the first packet was not received at the UE. Obtain the second packet delivery status information corresponding to the second node generated at the RLC layer of the second node. The expiration of the UE timer related to packet delay is predicted based on the first packet delivery status information and the second packet delivery status information, and In response to the prediction that the timer of the UE is about to expire, it is determined whether to retransmit the first packet to the UE via the second node. The data transmission node is either the first node or the second node. Wherein, the timer of the UE related to the packet delay is the UE's reordering timer, and The data transmission node is further configured to transmit T reordertimer -(T real -T reorder The timeout of the UE's reordering timer is predicted by comparing it with a certain threshold, and T reordertimer T represents the time the UE waits for the transmitted packet. real T represents the current time. reorder This indicates the time when the reordering timer is started in the UE.

7. The data transmission node according to claim 6, wherein, The data transmission node is also configured to predict the expiration of the UE's timer related to the packet delay based on the output of an artificial intelligence (AI) model trained on the first and second packet delivery status information, which is input into the current first packet delivery status information and the current second packet delivery status information.

8. The data transmission node according to claim 6, wherein, The first packet delivery status information and the second packet delivery status information are determined based on feedback information received from the UE.

9. The data transmission node according to claim 6, wherein, The first packet delivery status information includes the downlink data delivery status (DDDS) of the first node's Radio Link Control (RLC) layer, and The second packet delivery status information includes the DDDS of the RLC layer of the second node.

10. The data transmission node according to claim 6, wherein, The first packet is retransmitted via the second node with priority over other packets.

11. A computer-readable recording medium having a computer program recorded thereon, the computer program being used to perform the data transmission method according to claim 1.

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