Communication device and method for transmitting packet in wireless communication system

Abstract

This communication device configured to perform functions of a central unit (CU) comprises: a communication circuit; a memory for storing instructions; and at least one processor comprising a plurality of processing units. The instructions, when executed by the at least one processor, may cause the communication device to: determine the network quality regarding a communication path between the CU and a distributed unit (DU) connected to the CU on the basis of the communication circuit; determine whether the network quality is greater than or equal to a threshold value; transmit data packets for downlink transmission to the DU by using one processing unit accordingly; determine the number of packets that can be transmitted per processing unit on the basis of a packet loss rate regarding transmission from the CU to the DU according to the determination that the network quality is less than the quality threshold value; and perform processing unit-based scheduling on the basis of the number of packets that can be transmitted per processing unit, thereby transmitting data packets for the downlink transmission to the DU by using at least one processing unit.

Description

Communication device and method for transmitting packets in a wireless communication system

[0001] The present disclosure relates to a communication device and method for transmitting packets in a wireless communication system.

[0002] A base station can provide an access network to a terminal. To provide an access network, the base station may be implemented in a distributed deployment according to communication protocols, consisting of a central unit (CU) configured to perform upper layer functions and a distributed unit (DU) configured to perform lower layer functions.

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

[0004] According to embodiments of the present disclosure, a communication device configured to perform the functions of a central unit (CU) is provided. The communication device may include a communication circuit; a memory for storing instructions; and at least one processor comprising a plurality of processing units. When the above instructions are executed by the at least one processor, the communication device determines the network quality for a communication path between the CU and a DU (distributed unit) connected to the CU based on the communication circuit, determines whether the network quality is above a quality threshold, transmits data packets for downlink transmission to the DU through the communication circuit using one of the processing units based on the determination that the network quality is above the quality threshold, determines the number of packets that can be transmitted per processing unit based on the packet loss rate for transmission from the CU to the DU based on the determination that the network quality is below the quality threshold, and schedules on a processing unit basis based on the determined number of packets that can be transmitted per processing unit, thereby causing at least one of the processing units to transmit data packets for downlink transmission to the DU through the communication circuit.

[0005] According to embodiments of the present disclosure, a method is provided by a communication device configured to perform the functions of a central unit (CU). The method may include: determining a network quality for a communication path between the CU and a distributed unit (DU) connected to the CU; determining whether the network quality is above a quality threshold; transmitting data packets for downlink transmission to the DU using one of a plurality of processing units of the CU in accordance with the determination that the network quality is above the quality threshold; determining the number of packets that can be transmitted per processing unit based on a packet loss rate for transmission from the CU to the DU in accordance with the determination that the network quality is below the quality threshold; and transmitting data packets for downlink transmission to the DU using at least one of a plurality of processing units by scheduling on a processing unit basis based on the determined number of packets that can be transmitted per processing unit.

[0006] Figure 1 shows an example of a wireless communication system.

[0007] Figure 2a shows an example of a control plane (C-plane).

[0008] Figure 2b shows an example of a user plane (U-plane).

[0009] Figures 3a and 3b show examples of function splitting.

[0010] Figure 4 shows examples of distributed network deployments.

[0011] Figure 5 shows an example of signaling between a central unit (CU) and a distributed unit (DU).

[0012] Figure 6 shows an example of a communication path between a CU and a DU.

[0013] Figure 7 shows examples of components of a communication device.

[0014] Figures 8a and 8b show examples of comparisons between the transmission of packets according to the burst transmission method and the transmission of packets according to the pacing transmission method.

[0015] Figure 9 shows the operation flow of a communication device for determining a transmission method.

[0016] Figure 10 shows the operation flow of a communication device for a pacing transmission method.

[0017] Figure 11 shows an example of the performance of the pacing transmission method.

[0018] Figure 12 shows an example of the performance of the pacing transmission method.

[0019] The terms used in this disclosure are used merely to describe specific embodiments and are not intended to limit the scope of other embodiments. A singular expression may include a plural expression unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art described in this disclosure. Terms used in this disclosure that are defined in a general dictionary may be interpreted as having the same or similar meaning as they have in the context of the relevant technology, and are not to be interpreted in an ideal or overly formal sense unless explicitly defined in this disclosure. In some cases, even terms defined in this disclosure are not to be interpreted to exclude the embodiments of this disclosure.

[0020] In the various embodiments of the present disclosure described below, a hardware-based approach is described as an example. However, since the various embodiments of the present disclosure include techniques using both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0021] Terms used in the following description to refer to signals (e.g., signal, information, message, signaling), terms to refer to data (e.g., packet, user stream, information, bit, symbol, codeword), terms to refer to resources (e.g., symbol, slot, subframe, radio frame, frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), occasion), terms for operation states (e.g., step, operation, procedure), terms to refer to data (e.g., packet, user stream, protocol data unit (PDU), service data unit (SDU), information, bit, symbol, codeword), terms to refer to channels, terms to refer to network entities, terms to refer to device components, etc. are examples provided for the convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. Additionally, terms such as '...part', '...device', '...body' used below may refer to at least one shape structure or a unit that processes a function.

[0022] Additionally, in this disclosure, expressions of "greater than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled; however, this is merely for the purpose of expressing an example and does not exclude descriptions of "greater than" or "less than." Conditions described as "greater than" may be replaced with "greater than," conditions described as "less than" may be replaced with "less than," and conditions described as "greater than and less than" may be replaced with "greater than and less than." Furthermore, "A" to "B" below refer to at least one of elements from A (including A) to B (including B). Below, "C" and / or "D" refers to including at least one of "C" or "D," i.e., {"C", "D", "C" and "D"}.

[0023] This disclosure describes various embodiments using terms used in some communication standards (e.g., 3GPP (3rd Generation Partnership Project), ETSI (European Telecommunications Standards Institute), xRAN (extensible radio access network), O-RAN (open-radio access network), but these are merely illustrative examples. Various embodiments of this disclosure can be easily modified and applied to other communication systems.

[0024] Figure 1 shows an example of a wireless communication system.

[0025] Referring to FIG. 1, FIG. 1 illustrates a base station (110) and a terminal (120) as part of nodes using a wireless channel in a wireless communication system. FIG. 1 illustrates only one base station, but the wireless communication system may include other base stations identical or similar to the base station (110).

[0026] A base station (110) is a network infrastructure that provides wireless access to a terminal (120). The base station (110) has coverage defined based on the distance over which it can transmit signals. In addition to being a base station, the base station (110) may be referred to as a 'RAN (radio access network) node', 'access point (AP)', 'eNodeB (eNB)', '5G node (5th generation node)', 'next generation nodeB (gNB)', 'wireless point', 'transmission / reception point (TRP)', 'communication node', 'communication device', 'electronic device', 'wireless communication device', 'wireless communication equipment', 'network node', 'network entity', or other terms having an equivalent technical meaning.

[0027] A terminal (120) is a device used by a user and communicates with a base station (110) via a wireless channel. The link from the base station (110) to the terminal (120) is referred to as a downlink (DL), and the link from the terminal (120) to the base station (110) is referred to as an uplink (UL). Additionally, although not shown in FIG. 1, the terminal (120) and another terminal can communicate with each other via a wireless channel. In this case, the link between the terminal (120) and another terminal (device-to-device link, D2D) is referred to as a sidelink, and the sidelink may be used interchangeably with the PC5 interface. In some other embodiments, the terminal (120) may be operated without user involvement. According to one embodiment, the terminal (120) is a device that performs machine type communication (MTC) and may not be carried by the user. Additionally, according to one embodiment, the terminal (120) may be a narrowband (NB)-Internet of Things (IoT) device.

[0028] The terminal (120) may be referred to as 'user equipment (UE)', 'customer premises equipment (CPE)', 'mobile station', 'subscriber station', 'remote terminal', 'wireless terminal', 'communication device', 'electronic device', or 'user device' or other terms having an equivalent technical meaning.

[0029] The base station (110) can perform beamforming with the terminal (120). The base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively low frequency band (e.g., FR 1 (frequency range 1) of NR). Additionally, the base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively high frequency band (e.g., FR 2 (or FR 2-1, FR 2-2, FR 2-3), FR 3) of NR) and a millimeter wave (mmWave) band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz)). To improve channel gain, the base station (110) and the terminal (120) can perform beamforming. Here, beamforming may include transmit beamforming and receive beamforming. The base station (110) and the terminal (120) can impart directivity to the transmitted signal or the received signal. To this end, the base station (110) and the terminal (120) can select serving beams through a beam search or beam management procedure. After the serving beams are selected, subsequent communication can be performed through a resource that has a QCL relationship with the resource that transmitted the serving beams.

[0030] The network between the base station (110) and the terminal (120) may be referred to as an access network or a RAN (radio access network). A set of network entities connected to the base station (110) may be referred to as a core network. For example, the core network may be a 5G core (5GC). For example, the core network may be an EPC (evolved packet core).

[0031] FIG. 2a shows an example of a control plane (C-plane). As a base station (110), a gNB is described as an example. As a terminal (120), a UE is described as an example.

[0032] Referring to FIG. 2a, in the C-plane, the UE (120) and the access and mobility management function (AMF) (235) can perform non-access stratum (NAS) signaling. The AMF (235) can provide functions related to mobility management of the UE (120), user registration, authentication, connection establishment, and / or release. In the C-plane, the UE (120) and the gNB (110) can perform communication according to a specified protocol at the radio resource control (RRC) layer, packet data convergence protocol (PDCP) layer, radio link control (RLC) layer, medium access control (MAC) layer, and physical (PHY) layer, respectively.

[0033] The main functions of the RRC layer may include at least some of the following functions.

[0034] - Broadcasting system information related to AS (Access Stratum) and NAS

[0035] - Paging initiated by 5GC (5G Core) or NG-RAN (Next Generation-Radio Access network)

[0036] - Establishment, maintenance, and release of the RRC connection between the UE and NG-RAN, including, specifically, control over RLC, MAC, and PHY:

[0037] - Adding, modifying, and removing Carrier Aggregation

[0038] - Add, modify, and disable dual connectivity between NR or E-UTRA and NR.

[0039] - Security features including Key Management;

[0040] - Setup, configuration, maintenance, and release of SRB (Signaling Radio Bearer) and DRB (Data Radio Bearer)

[0041] - Movement functions including the following:

[0042] - Handover and context transfer;

[0043] - UE cell selection and re-selection and cell selection and re-selection control;

[0044] - Mobility between RATs.

[0045] - QoS (quality of service) management function;

[0046] - UE measurement reporting and control of reporting;

[0047] - Radio link failure detection and recovery

[0048] - Send messages from / to UE to / from NAS.

[0049] The main functions of the PDCP layer may include at least some of the following functions.

[0050] - Header compression and decompression features (ROHC only)

[0051] - User data transfer function (Transfer of user data)

[0052] - Sequential delivery function (In-order delivery of upper layer PDU (protocol data unit)s)

[0053] - Out-of-order delivery of upper layer PDUs

[0054] - Reordering function (PDCP PDU reordering for reception) (hereinafter, reordering)

[0055] - Duplicate detection function (Duplicate detection of lower layer SDUs)

[0056] - Retransmission of PDCP SDUs

[0057] - Encryption and decryption functions (Ciphering and deciphering)

[0058] - Timer-based SDU discard in uplink.

[0059] The main functions of an RLC layer may include at least some of the following functions.

[0060] - Data transfer function (Transfer of upper layer PDUs)

[0061] - Sequential delivery function (In-sequence delivery of upper layer PDUs)

[0062] - Out-of-sequence delivery of upper layer PDUs

[0063] - ARQ function (Error Correction through ARQ)

[0064] - Concatenation, segmentation, and reassembly functions of RLC SDUs

[0065] - Re-segmentation function (Re-segmentation of RLC data PDUs)

[0066] - Reordering function (Reordering of RLC data PDUs)

[0067] - Duplicate detection

[0068] - Error detection function (Protocol error detection)

[0069] - RLC SDU discard function

[0070] RLC re-establishment function

[0071] The MAC layer can be connected to multiple RLC layer devices configured in a terminal, and the main functions of the MAC may include at least some of the following functions.

[0072] - Mapping function between logical channels and transport channels

[0073] - Multiplexing and demultiplexing of MAC SDUs

[0074] - Scheduling information reporting function

[0075] Error correction through HARQ

[0076] - Priority handling between logical channels of one UE

[0077] - Priority handling between UEs by means of dynamic scheduling

[0078] - MBMS service identification function

[0079] - Transport format selection function

[0080] - Padding

[0081] The physical layer can perform operations such as channel coding and modulating upper layer data, converting it into OFDM symbols for transmission over the wireless channel, or demodulating OFDM symbols received through the wireless channel, channel decoding, and transmitting them to the upper layer.

[0082] FIG. 2b shows an example of a user plane (U-plane). As a base station (110), a gNB is described as an example. As a terminal (120), a UE is described as an example.

[0083] Referring to FIG. 2b, in the U-plane, the UE (120) and gNB (110) can communicate according to a specified protocol in each of the SDAP layer, PDCP layer, RLC layer, MAC layer, and PHY layer. For the PDCP layer, RLC layer, MAC layer, and PHY layer, excluding the SDAP layer, the description of FIG. 2a may be referenced.

[0084] The SDAP layer can provide the QoS flow of 5GC. A single protocol entity of SDAP can be configured for each individual PDU session, and the functions of the SDAP layer may include at least some of the following functions.

[0085] - Mapping between QoS flow and data wireless bearer;

[0086] - Displays QoS flow ID (identifier) ​​(QFI) in both DL and UL packets.

[0087] FIGS. 3a and 3b illustrate examples of function splitting. A base station (e.g., base station (110)) may operate as an eNB or a gNB depending on the radio access technology (RAT) provided. For example, the base station may be referred to as an NG-RAN node. The base station may be implemented in a distributed deployment according to a central unit (CU) configured to perform the functions of the upper layers of the access network (e.g., packet data convergence protocol (PDCP), radio resource control (RRC)) and a distributed unit (DU) configured to perform the functions of the lower layers.

[0088] Referring to FIG. 3a, in the control plane, a CU (310) is connected to one or more DUs (e.g., DU (320)) and can perform functions of a layer higher than the DU. For example, the CU (310) can perform the functions of the RRC layer (311) and the PDCP layer (312). The CU (310) can transmit or receive messages through the F1 interface (340) with the DU (320). In the control plane, the DU (320) can perform the functions of the RLC layer (321), the MAC layer (322), and the PHY layer (323). To explain the functions of the RRC layer (311) of the CU (310), the description of the RRC layer in FIG. 2a may be referenced. To explain the functions of the PDCP layer (312) of the CU (310), the description of the PDCP layer in FIG. 2a may be referenced. For an explanation of the functions of the RLC layer (321) of the DU (320), the description of the RLC layer in FIG. 2a may be referenced. For an explanation of the functions of the MAC layer (322) of the DU (320), the description of the MAC layer in FIG. 2a may be referenced. For an explanation of the functions of the PHY layer (323) of the DU (320), the description of the PHY layer in FIG. 2a may be referenced. The DU (320) can perform the operation of channel coding and modulating upper layer data through the physical layer (323), creating OFDM symbols and transmitting them over a wireless channel, or demodulating OFDM symbols received through the wireless channel and channel decoding them to transmit them to the upper layer.

[0089] Referring to FIG. 3b, in the user plane, a CU (310) is connected to one or more DUs (e.g., DU (320)) and can perform functions of a layer higher than the DU. For example, the CU (310) can perform functions of the SDAP layer (361) and the PDCP layer (362). The CU (310) can send or receive messages through the DU (320) and the F1 interface (350) (e.g., F1-U). The CU (310) can be referenced as a node hosting PDCP entities for the PDCP layer (362) in terms of performing functions for the PDCP layer (362). The DU (320) can be referenced as a node interacting with the node hosting the PDCP entities for flow control. In the user plane, the DU (320) can perform the functions of the RLC layer (371), MAC layer (372), and PHY layer (373). To explain the functions of the SDAP layer (361) of the CU (310), the description of the SDAP layer in FIG. 2b may be referenced. To explain the functions of the PDCP layer (362) of the CU (310), the description of the PDCP layer in FIG. 2b may be referenced. To explain the functions of the RLC layer (321) of the DU (320), the description of the RLC layer in FIG. 2b may be referenced. To explain the functions of the MAC layer (322) of the DU (320), the description of the MAC layer in FIG. 2b may be referenced. To explain the functions of the PHY layer (323) of the DU (320), the description of the PHY layer in FIG. 2b may be referenced.

[0090] In FIG. 3a and FIG. 3b, a DU (e.g., DU (320)) is depicted as being responsible for the physical layer (e.g., physical layer (323), physical layer (373)), but embodiments of the present disclosure are not limited thereto. According to an embodiment, the DU (320) may perform some functions of the physical layer (high PHY), and the RU connected to the DU (320) may be responsible for the remaining functions of the physical layer (low PHY). Additionally, as an example, the DU (digital unit) may be included in the DU (distributed unit) (320) according to the distributed deployment implementation of the base station. As an example, the DU (digital unit) may refer to an entity including the CU and the DU (distributed unit) in a structure arranged in the order of CU, DU (distributed unit), and RU.

[0091] In FIG. 3a and 3b, the CU (310) configured to perform the functions of the control plane layer is described as performing the functions of the user plane layer, but the embodiments of the present disclosure are not limited thereto. As a non-limiting example, a node configured to perform the functions of the control plane layer and a node configured to perform the functions of the user plane layer may be implemented separately. For example, a node configured to perform the functions of the control plane layer may operate as CU-CP (control plane), and a node configured to perform the functions of the user plane layer may operate as CU-UP (user plane).

[0092] Figure 4 shows examples of distributed network deployments. In communication systems with a relatively large cell radius of base stations, each base station (e.g., base station (110)) is installed to include the functions of a digital processing unit (or distributed unit (DU)) and a radio frequency (RF) processing unit (or radio unit (RU)). However, as high frequency bands are used in 4G (4th generation) and / or subsequent communication systems (e.g., 5G) and the cell coverage of base stations decreases, the number of base stations required to cover a specific area has increased. The burden of installation costs for operators to install base stations has also increased. To minimize the installation costs of base stations, a structure has been proposed in which the DU and RU of a base station are separated, with one or more RUs connected to a single DU via a wired network, and one or more geographically distributed RUs deployed to cover a specific area. Below, FIG. 4 illustrates the distribution according to the placement of a CU (e.g., CU (310)), a DU (e.g., DU (320)), and an RU. Scenarios of the deployment are described.

[0093] Referring to FIG. 4, network nodes for providing an access network to a terminal (e.g., terminal (120)) may include a CU (310), a DU (320), and a RU (430). According to one embodiment, in example (400a), each node of the network nodes for said purpose may be arranged independently. The CU (310) may be connected via a backhaul network to a network entity associated with a core network (440) (e.g., 5GC (5th generation core)) (e.g., an access and mobility management function (AMF) (e.g., AMF (235)), a user plane function (UPF), a mobility management entity (MME) or a serving gateway (S-GW) in the case of an evolved packet core (EPC).

[0094] The communication path between the CU (310) and the DU (320) may be referred to as a midhaul network. The CU (310) and the DU (320) may be connected via an F1 interface. The F1 interface may include an F1-C interface for the control plane (e.g., F1 interface (340)) and an F1-U interface for the user plane (e.g., F1 interface (350)). For signaling between the CU (310) and the DU (320) in the user plane, the descriptions of FIG. 5 described below may be referenced. To connect the CU (310) and the DU (320), the communication path may include at least one routing node (which may be referred to by technical terms other than routing node, such as router, relay node, node, switch, path switch, and / or equivalent). In terms of communication protocols, the CU (310) and the DU (320) communicate through the F1 interface, but data transmitted from the CU (310) to the DU (320) may be provided to the DU (320) through at least one routing node between the CU (310) and the DU (320). As an example, but not limited to, the CU (310) may include, as separate entities, CU-CP for the F1-C interface and CU-UP for the F1-U interface.

[0095] The DU (320) and RU (430) can be connected via a fronthall interface. For the implementation of the fronthall interface, an interface such as eCPRI (enhanced common public radio interface) or ROE (radio over ethernet) may be used. In a deployment such as a C-RAN (centralized / cloud radio access network), the CU (310) may be configured to perform functions related to GTP (GPRS Tunneling Protocol) and / or functions of the PDCP layer. The DU (320) may be implemented to perform some of the functions of the RLC (radio link control) layer, MAC (media access control) layer, and PHY (physical) layer, and the RU (430) may be implemented to perform other parts of the PHY layer functions in addition to RF (radio frequency) functions. Some of the functions of the PHY layer of the DU (320) are performed at a higher level among the functions of the PHY layer, and may include, for example, channel encoding (or channel decoding), scrambling (or descrambler), modulation (or demodulation), and layer mapping (or layer demapping). Other of the functions of the PHY layer of the RU (330) are performed at a relatively lower level than that of the DU (320), and may include, for example, iFFT transform (or FFT transform), CP (cyclic prefix) insertion (CP removal), and digital beamforming.

[0096] According to one embodiment, in example (400a), the CU (310), DU (320), and RU (430) may each be implemented as independent nodes. According to another embodiment, in example (400b), the DU (320) and RU (430) may be implemented in a single device (e.g., DU (digital unit)). The DU (320) and RU (430) are logically distinct, and communication between the DU (320) and RU (430) may be performed within the device. According to yet another embodiment, in example (400c), the CU (310) and DU (320) may be implemented in a single device (e.g., RAN node, gNB, base station (110)). The CU (310) and DU (320) are logically distinct, and communication between the CU (310) and DU (320) may be performed within the device. According to another embodiment, in example (400d), the CU (310), DU (320), and RU (430) can be implemented in a single device (e.g., RAN node, gNB, base station (110)).

[0097] FIG. 5 illustrates an example of signaling between a central unit (CU) and a distributed unit (DU). FIG. 5 describes examples of messages on an F1 interface (350) (e.g., F1-U) between a CU (310) and a DU (320) in the user plane (U-plane). Identical reference numbers may denote identical descriptions.

[0098] Referring to FIG. 5, the DU (320) can send a status message (510) to the CU (310).

[0099] 1. Transmission of status messages

[0100] The DU (320) may transmit a status message (510) to the CU (310) via the F1 interface (350) (e.g., F1-U). According to one embodiment, the status message (510) may include a downlink data delivery status (DDDS). The procedure for transmitting the status message (510) allows the CU (310) to control the downlink user data flow of each data radio bearer (DRB) by providing feedback from the DU (320) to the CU (310). The procedure for transmitting the status message (510) may be used to provide feedback from the DU (320) to the CU (310) to allow the CU (310) to control the successful delivery of downlink control data. As a non-limiting example, the DU (320) may transmit uplink user data of the associated data wireless bearer to the CU (310) via a status message (510). In this case, the data wireless bearer of the uplink user data and the wireless bearer of the status message (510) may be associated with the same PDU (protocol data unit).

[0101] The status message (510) may include various information. For example, in RLC AM (acknowledged mode), the status message (510) may include the highest NR PDCP PDU sequence number that was successfully delivered sequentially to the UE among the PDCP PDUs received from the CU (310). Here, retransmitted NR PDCP PDUs among the PDUs may be excluded. For example, the status message (510) may include information regarding the desired buffer size for the corresponding data radio bearer or MRB (multicast / broadcast service radio bearer). The desired buffer size may be indicated in bytes. For example, the status message (510) may optionally include information regarding the desired data rate associated with a specific data radio bearer configured for the UE or MRB. The desired data rate may be indicated in bytes. The value indicated in the above byte units may represent the amount of transmission per unit time (e.g., 1 second). For example, the status message (510) may include information about an NR-U packet that has been declared "lost" and has not yet been reported to the CU (310) within the status message (510) (e.g., the Downlink Data Transfer Status (DDDS) frame of [Table 1]). For example, the status message (510) may include information about the NR PDCP PDU sequence number associated with the highest NR-U sequence number among the retransmitted NR PDCP PDUs successfully delivered to the UE in the order of NR-U sequence numbers when a retransmitted NR PDCP PDU is delivered.For example, the status message (510) may include information regarding the NR PDCP PDU sequence number associated with the highest NR-U sequence number among the retransmitted NR PDCP PDUs transmitted to the lower layer in the order of NR-U sequence numbers when a retransmitted NR PDCP PDU is transmitted to the lower layer. For example, the status message (510) may include information regarding the highest NR PDCP PDU sequence number transmitted to the lower layer among the NR PDCP PDUs received from the CU (310). Here, the retransmitted NR PDCP PDUs among the PDUs may be excluded. For example, in an RLC AM, the status message (510) may include information regarding the NR PDCP PDU sequence number that was successfully delivered to the UE without order among the NR PDCP PDUs received from the CU (310). Here, the retransmitted NR PDCP PDUs among the PDUs may be excluded.

[0102] A status message (510) may be triggered based on an event. For example, when the DU (320) detects successful RACH (random access channel) access by a UE (e.g., terminal (120)) to the corresponding data wireless bearer, the DU (320) may send a status message (510) to the CU (310). The CU (310) may start downlink data transmission before receiving the status message (510). For example, the status message (510) may have the following format, referred to as a downlink data transmission status (DDDS) frame.

[0103]

[0104] Referring to [Table 1], when the status message (510) is the last downlink status report, the status message (510) may include a separate indicator (e.g., Final Frame Ind.). Upon receiving the indicator, the CU (310) may consider that no further UL or DL ​​data transmission is expected between the DU (320) and the terminal (120). The status message (510) may include a detected indicator of a radio link outage or radio link resume for the relevant data radio bearer. For example, a specific value of a parameter (e.g., "Cause Value") may indicate a radio link outage (e.g., a parameter value '1' indicates a radio link outage) or a radio link resume (e.g., a parameter value '2' indicates a radio link resume). For example, through the value of the above parameter, wireless link interruption or wireless link resumption may be directed by both the downlink and the uplink, by only the downlink, or by only the uplink.

[0105] Referring to [Table 1], 'Desired buffer size for the data radio bearer' can represent the desired buffer size in bytes for the associated data radio bearer. 'Desired buffer size for the data radio bearer' has a 4-octet structure and can have a value between 0 and 232-1. For example, 'Desired Data Rate' represents the amount of data desired to be received in bytes during a specific time (e.g., 1 second). 'Desired Data Rate' has a 4-octet structure and can have a value between 0 and 232-1.

[0106] The CU (310) can receive a status message (510) from the DU (320). The CU (310) can determine the amount of data to be transmitted from the CU (310) by a desired buffer size (e.g., 'Desired buffer size for the data radio bearer') and a data rate (e.g., 'Desired Data Rate'). If the value of the desired buffer size is 0, the CU (310) can stop the transmission of data to the corresponding bearer. If the value of the desired buffer size is greater than 0, the CU (310) can transmit data up to the amount of data indicated by the desired buffer size per bearer. For example, the data may include data to be retransmitted. In addition to the retransmitted data, the above data may include new data starting from the last "highest successfully delivered NR PDCP sequence number" for RLC AM (e.g., 'Highest successfully delivered NR PDCP Sequence Number') or the last "highest transmitted NR PDCP sequence number" for RLC UM (e.g., 'Highest transmitted NR PDCP Sequence Number'). The value of the requested data rate indicates the amount of data desired to be received for approximately 1 second. The information regarding the requested buffer size and the information regarding the requested data rate may remain valid until the next status message is received.

[0107] 2. Transmission of user data

[0108] The CU (310) can transmit user data (520) to the DU (320). The purpose of the transmission procedure for user data (520) is to provide NR-U specific sequence number information when transmitting user data (520) carrying a DL NR PDCP PDU from the CU (310) to the DU (320). In the downlink, an NR user plane protocol instance using the transmission procedure for user data (520) can be connected to only a single wireless bearer. The CU (310) can assign a successive NR-U sequence number to each transmitted NR-U packet. A new NR-U sequence number must be assigned to a retransmitted NR PDCP PDU. The CU (310) can inform the DU (320) whether this NR-U packet is a retransmission of an NR PDCP PDU. CU (310) may instruct DU (320) to discard all NR PDCP PDUs, including defined DL discard NR PDCP PDU SN, or to discard one or more downlink NR PDCP PDU blocks.

[0109] For example, user data (520) may have the following format.

[0110]

[0111] Referring to Table 2, for example, 'NR-U Sequence Number' represents an NR-U sequence number assigned by CU (310). 'NR-U Sequence Number' has a 3-octet structure and can have a value of 0 to 224-1. For example, 'DL discard NR PDCP PDU SN' can represent the SN when PDUs up to NR PDCP PDU SN are discarded. 'DL discard NR PDCP PDU SN' has a 3-octet structure and can have a value of 0 to 218-1. For example, 'DL discard Number of blocks' represents downlink blocks that are discarded. 'DL discard Number of blocks' has a 1-octet structure and can have a value of 1 to 244. For example, 'DL discard NR PDCP PDU SN start' indicates the starting SN in the block to be discarded, and 'Discarded Block size' indicates the number of PDCP PDUs to be discarded starting from the starting SN.

[0112] In FIG. 5, NR PDCP PDUs are described as examples of downlink packets, but the embodiments of the present disclosure are not limited thereto. PDCP PDUs on the W1 interface between the eNB-DU and the eNB-CU may also be subject to the embodiments of the present disclosure. In other words, downlink packets include PDCP PDUs in an LTE network, and the CU (310) and DU (320) may correspond to the eNB-CU and eNB-DU constituting the eNB, respectively. The following description of the F1 interface (350) (e.g., F1-U) may be equally applied to the W1 interface between the eNB-CU and the eNB-DU.

[0113] FIG. 6 shows an example of a communication path between a CU (e.g., CU (310)) and a DU (e.g., DU (320)). The communication path between the CU (310) and the DU (320) can be used as a transmission path for packets for the F1 interface between the CU (310) and the DU (320). The communication path can be determined according to the operator's communication network.

[0114] Referring to FIG. 6, the communication path between the CU (310) and the DU (320) may include multiple paths and at least one routing node. If the distance between the CU (310) and the DU (320) is significantly long, it may be difficult to connect the two nodes with a single path. A routing node may be used to connect multiple paths. The routing node may be placed between the paths and function as a data hub. In Example (601), the communication path between the CU (310) and the DU (320) may include a first path (671), a second path (672), and a third path (673). The first path (671) and the second path (672) may be connected through a first routing node (650). The first routing node (650) may include a buffer (651). The second path (672) and the third path (673) may be connected through the second routing node (660). The second routing node (660) may include a buffer (661). In example (602), the communication path between the CU (310) and the DU (320) may include the first path (681) and the second path (682). The first path (618) and the second path (682) may be connected through the routing node (690). The routing node (690) may include a buffer (691). The components of the communication path for the connection between the CU (310) and the DU (320) may differ depending on the operator. The components of the communication path may affect the transmission performance between the CU (310) and the DU (320). For example, the presence of routing nodes (e.g., first routing node (650), second routing node (660), routing node (690)) can cause a difference between data packets provided from the CU (310) and data packets received from the DU (320). Additionally, the number of routing nodes included in the communication path or the capability of each routing node can affect transmission performance.

[0115] For example, the CU (310) and the DU (320) can be connected via a communication path such as example (601). The CU (310) can transmit data packets for downlink transmission to the DU (320). The CU (310) can transmit the data packets to the DU (320) through at least one routing node (e.g., first routing node (650), second routing node (660)). The CU (310) can transmit data packets to the first routing node (650). The CU (310) can transmit 10 data packets to the DU (320) at a time. Meanwhile, the first routing node (650) can output 6 data packets at a time. The size of the buffer (651) within the first routing node (650) may not be sufficient to accommodate four data packets (e.g., processing speed issues of the first routing node (650), performance issues of the cable of the second path (672). In such cases, the first routing node (650) may find it difficult to process all received data packets. Packets that are not stored in the buffer (651) may be lost. If the capacity of the buffer is insufficient to compensate for the difference between the transmission speed at the CU (310) and the output speed at the first routing node (650), packet loss may occur at the first routing node (650). The lost packets may be difficult to recover sufficiently even through a retransmission algorithm (e.g., ARQ (automatic repeat request)).

[0116] For example, the CU (310) and the DU (320) may be connected via a communication path such as example (602). The CU (310) may transmit data packets for downlink transmission to the DU (320). The CU (310) may transmit the data packets to the DU (320) through at least one routing node (e.g., routing node (690)). The CU (310) may transmit data packets to the routing node (690). The CU (310) may transmit 10 data packets to the DU (320) at a time. Even if the routing node (690) outputs 6 data packets at a time, the buffer (691) of the routing node (690) may be configured to accommodate 5 data packets. The size of the buffer (691) within the routing node (690) may be sufficient to compensate for the difference between the output speed of the routing node (690) and the transmission speed of the CU (310). Therefore, even if 10 data packets are transmitted at once from the CU (310), packet loss may not occur at the routing node (690).

[0117] The separated structure in which the CU (310) and DU (320) are separated has various structural advantages. However, the components of the communication path for connecting the CU (310) and DU (320) differ from operator to operator, and the actual transmission performance may vary depending on which communication path is used. For example, in a situation where the CU (310) transmits a large volume of burst traffic, if a communication network that cannot fully utilize the traffic volume (e.g., the communication path between the CU (310) and DU (320)) is used, traffic loss may occur. Even if a recovery algorithm is used, continuous traffic loss can cause not only quality degradation due to packet loss but also delays in communication services due to the reordering timer timeout. Since each operator has an independent communication network, each operator may have different transmission performance. Therefore, a uniform transmission technique can cause significant traffic loss in communication networks that provide relatively low quality. In addition, if the operations of the CU (310) are designed based on a communication network providing low quality, the operator will transmit packets at a lower transmission performance even though it is capable of transmitting packets at a higher transmission performance, which is inefficient. To resolve the above-mentioned problems, a communication device (e.g., CU (310)) according to the embodiments of the present disclosure can adaptively operate a conventional burst transmission method (indicating the transmission of data packets in a single pass) or a pacing transmission method (indicating the transmission of data packets in separate passes) based on the network quality of each operator. As a result, stable and efficient data performance can be achieved in any operator network.

[0118] Hereinafter, in order to explain the burst transmission method and the pacing transmission method, CU (310) and DU (320) are described as examples of network nodes using a communication network. However, the embodiments of the present disclosure are not limited thereto. In addition to separation such as CU (310) and DU (320), in a distributed deployment scenario including any upper network node and any lower network, any transmission between an upper network node and a lower network node can be understood as an embodiment of the present disclosure.

[0119] FIG. 7 illustrates examples of components of a communication device (e.g., CU (310)). The communication device may be configured to perform the functions of the CU (310). Terms such as '...part', '...device', '...circuit', '...module' used below refer to a unit that processes at least one function or operation, which may be implemented in hardware or a combination of hardware and software.

[0120] Referring to FIG. 7, the communication device may include a communication circuit (710), a memory (720), and a processing circuit (730). The communication circuit (710) may perform functions for transmitting and receiving signals in a wired communication environment. The communication circuit (710) may include a wired interface for controlling a direct connection between devices through a transmission medium (e.g., copper wire, optical fiber). For example, the communication circuit (710) may transmit an electrical signal to another device through a copper wire or perform conversion between an electrical signal and an optical signal. According to one embodiment, the communication device may communicate with a distributed unit (DU) (e.g., DU (320)) through the communication circuit (710). The communication circuit (710) may also perform functions for transmitting and receiving signals in a wireless communication environment. For example, the communication circuit (710) may perform conversion between a baseband signal and a bit sequence according to the physical layer specifications of the system. For example, when transmitting data, the communication circuit (710) generates complex symbols by encoding and modulating the transmitted bit sequence. Also, when receiving data, the communication circuit (710) restores the received bit sequence by demodulating and decoding the baseband signal. Additionally, the communication circuit (710) may include a plurality of transmission and reception paths. The communication circuit (710) transmits and receives signals as described above. Accordingly, all or part of the communication circuit (710) may be referred to as a 'communication unit', 'transmitter unit', 'receiver unit', 'transmitter and receiver unit', or 'transmitter and receiver'. According to one embodiment, the communication circuit (710) may include a network interface card (NIC). The NIC may be connected to the DU (320) via a communication path.

[0121] The memory (720) can store data such as basic programs, application programs, and setting information for the operation of the communication device. The memory (720) may be referred to as a storage unit. The memory (720) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. Additionally, the memory (720) may provide stored data upon request from the processing circuit (730). As a functional component, the memory (720) may represent a storage space. For example, the memory (720) may be understood not only as representing a memory (e.g., hard disk, flash memory, RAM) placed as a component within the communication device, but also as representing a space for storing instructions and / or programs.

[0122] The processing circuit (730) controls the overall operations of the communication device. The processing circuit (730) may include at least one processor. The processing circuit (730) may be referred to as a control unit. For example, the processing circuit (730) transmits and receives signals through the communication circuit (710). Additionally, the processing circuit (730) writes and reads data to and from memory (920). Furthermore, the processing circuit (730) can perform functions of the protocol stack required by the communication standard (e.g., functions according to the protocol layers of FIG. 2a, FIG. 2b, FIG. 3a, and FIG. 3b).

[0123] According to embodiments of the present disclosure, the processing circuit (730) may include a plurality of processing units (e.g., processing unit #1, processing unit #2, ..., processing unit #N). For example, a processing unit may represent a physical circuit unit capable of independently performing operations (e.g., operations related to transmission operations). Each processing unit may correspond to a core. For example, the core may be hardware and may include various physical components (e.g., an arithmetic logic unit (ALU), registers, and / or control units). According to one embodiment, the processing unit may represent a unit for controlling the transmission of data packets to the DU (320). An operation of one processing unit may be performed for one transmission. The processing circuit (730) may schedule the processing unit to transmit data packets. The processing circuit (730) may use the processing unit to transmit data packets through the communication circuit (710). According to one embodiment, in a burst transmission method, the processing circuit (730) may schedule one processing unit for the transmission of all data packets for downlink transmission. The scheduled processing unit may transmit all data packets without delay within a limited time through the communication circuit (710). According to one embodiment, in a pace transmission method, the processing circuit (730) may adaptively adjust the number of packets that can be transmitted per unit. The processing circuit (730) may distribute the data packets for downlink transmission to processing units based on the number of packets that can be transmitted per processing unit (e.g., N, where N is a natural number). For example, the processing circuit (730) may schedule processing unit #1 to transmit N data packets.Using processing unit #1, the N data packets are transmitted through the communication circuit (710), and the processing circuit (730) can schedule processing unit #2 for the transmission of the next N packets. The processing circuit (730) can divide the data into intervals and transmit them. Through the divided transmission, the burden of data processing at the receiving nodes (e.g., first routing node (650), second routing node (660), routing node (690)) can be reduced.

[0124] The components of the communication device illustrated in FIG. 7 are merely examples, and examples of components of the communication device for carrying out embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 7. In some embodiments, some components may be added, deleted, or changed.

[0125] Figures 8a and 8b show examples of comparisons between the transmission of packets according to the burst transmission method and the transmission of packets according to the pacing transmission method.

[0126] Referring to FIG. 8a, the CU (310) can transmit data packets for downlink transmission to the DU (320). A communication device (e.g., CU (310)) according to embodiments of the present disclosure can transmit data packets via burst transmission or pacing transmission. To explain burst transmission and pacing transmission methods, the communication path of the example (601) of FIG. 6 is described as an example. The communication path between the CU (310) and the DU (320) may include a first path (671), a second path (672), and a third path (673). The first path (671) and the second path (672) may be connected through a first routing node (650). The first routing node (650) may include a buffer (651). The second path (672) and the third path (673) may be connected through a second routing node (660). The second routing node (660) may include a buffer (661). The CU (310) may transmit the data packets to the DU (320) through the first routing node (650) and the second routing node (660). The CU (310) may transmit data packets to the first routing node (650). The first routing node (650) may transmit data packets to the second routing node (660). The second routing node (660) may transmit data packets to the DU (320).

[0127] According to the burst transmission method, the CU (310) can transmit all data packets in one go. For example, as in example (801), the CU (310) can transmit the data packets (e.g., 12 data packets) by using one processing unit (e.g., Core #1) among a plurality of processing units (e.g., Cores). The first routing node (650) can output three data packets in one go. The first routing node (650) can store up to four data packets in the buffer (651). However, the first routing node (650) may find it difficult to store data packets starting from the eighth data packet. The eighth data packet may be lost. Afterward, the first routing node (650) can process the packets stored in the buffer (651) sequentially. The CU (310) can continuously transmit the 9th data packet, the 10th data packet, the 11th data packet, and the 12th data packet. Even if the first routing node (650) processes the packets stored in the buffer (651) sequentially, additional packet loss may occur because the output speed from the first routing node (650) to the second routing node (660) is slower than the input speed from the CU (310). To resolve this problem, a phase transmission method may be required, which transmits only a certain number of packets and then transmits the remaining packets. As there is a time interval between the two transmissions, the available capacity of the buffer of the receiving node (e.g., the first routing node (650), the second routing node (660)) may increase. By the node outputting data packets during the time interval, the packet loss rate may be reduced.

[0128] According to embodiments of the present disclosure, the CU (310) can identify one of a burst transmission method and a pacing transmission method based on the network quality of the communication path. According to one embodiment, the CU (310) can determine (or measure) the network quality of the communication path between the CU (310) and the DU (320). The communication path may include wired paths and / or at least one routing node deployed by the business operator. For example, the network quality may include the packet loss rate on the communication path. For example, the network quality may include the transmission speed of packets on the communication path. For example, the network quality may include the delay parameter of packets on the communication path. The CU (310) can determine whether the network quality is above a quality threshold value in order to determine the transmission method of packets according to the network environment of the business operator.

[0129] According to one embodiment, the CU (310) may determine a burst transmission method based on the determination that the network quality is above the quality threshold. Based on the burst transmission method, the CU (310) may transmit data packets for downlink transmission to the DU (320) using one of the processing units among the processing units of the processing circuit (730). In the burst transmission method, all data packets that can be transmitted at maximum from the CU (310) are transmitted, and the receiving node (e.g., first routing node (650), routing node (690)) accepts all of the data packets, so sufficient communication quality can be guaranteed.

[0130] According to one embodiment, the CU (310) may determine a pacing transmission method based on the determination that the network quality is below the quality threshold. The CU (310) may determine the number of packets that can be transmitted per processing unit based on the loss rate between the CU (310) and the DU (320). The CU (310) may transmit data packets for downlink transmission to the DU (320) by scheduling on a processing unit basis based on the determined number of packets that can be transmitted per processing unit. If the network quality of the operator network is poor, even if the CU (310) transmits all possible data packets, it may be difficult for the routing node to accommodate all of the data packets. This is because the speed at which data packets are output or the capacity of the routing node's buffer is insufficient. Since it is difficult for the DU (320) to accommodate all the maximum number of data packets that can be transmitted from the CU (310), for pace control, it may be required to transmit packets in increments equal to the number of packets that can be transmitted per processing unit. Because the number of data packets is limited, the nodes receiving the data packets (e.g., first routing node (650), routing node (690)) can accommodate all of the limited number of data packets based on a buffer (e.g., buffer (651), buffer (691)).

[0131] As in Example (802), the CU (310) can determine the number of packets that can be transmitted per processing unit to be 4 (e.g., N=4) based on the loss rate between the CU (310) and the DU (320). The CU (310) can schedule the transmission of 4 packets (e.g., packets #1, #2, #3, #4) to a processing unit (e.g., core #1) and transmit the 4 packets using the scheduled processing unit. Afterward, the CU (310) can schedule the transmission of the next 4 packets (e.g., packets #5, #6, #7, #8) to a processing unit (e.g., core #2). The 4 packets can be transmitted using the scheduled processing unit. Afterward, CU (310) can schedule the transmission of the next four packets (e.g., packets #9, #10, #11, #12) to a processing unit (e.g., core #3). The four packets can be transmitted using the scheduled processing unit.

[0132] Meanwhile, the first routing node (650) can output three data packets at a time. The first routing node (650) can store up to four data packets in the buffer (651). The first routing node (650) can transmit three data packets (e.g., packet #1, packet #2, packet #3) and store packet #4 in the buffer (651). The buffer (651) of the first routing node (650) can accommodate three packets as a remaining capacity. Subsequently, at a transmission opportunity, the first routing node (650) can output packet #4. After CU (310) transmits packet #4 to the first routing node (650), it does not transmit the next packets immediately but transmits them after a certain period of time (e.g., scheduling time for core #1), so that the first routing node (650) can process and output the packets (e.g., packet #4) stored in the buffer for the said certain period of time. In this way, the first routing node (650) can transmit all packets received from CU (310) to the next node (e.g., second routing node (660)) without any packets being lost.

[0133] Referring to FIG. 8b, Example (851) illustrates a packet transmission flow of a burst transmission method. A transmission unit according to the burst transmission method may be referred to as a burst transmission. Example (852) illustrates a packet transmission flow of a pacing transmission method. A transmission unit according to the pacing transmission method may be referred to as a pacing transmission. In Example (851), the first burst transmission (881) may include the transmission of 12 packets. The second burst transmission (882) may include the transmission of 12 packets. In Example (852), the first pacing transmission (891) may include the transmission of 4 packets. The second pacing transmission (892) may include the transmission of 4 packets. The third pacing transmission (893) may include the transmission of 4 packets. The fourth pacing transmission (894) may include the transmission of 4 packets. In each of the example (851) and example (852), the number of packets transmitted during the transmission interval (860) may be the same. Based on the transmission interval (860), the data rate in the burst transmission method and the data rate in the pacing transmission method may be the same. However, if the quality of the network constituting the communication path (e.g., average data rate over a certain interval, packet loss rate) is low, the packet loss rate may be reduced. As the number of lost packets decreases, the quality of service is improved, and the number of timeouts of the reordering timer in the PDCP layer is reduced, thereby reducing the delay.

[0134] In FIG. 8b, to explain the pacing transmission method, an example is described in which different cores are each used for the transmission of four packets, but the embodiments of the present disclosure are not limited thereto. If one core is used to handle one transmission according to the limited number of packets, it may be understood as an embodiment of the present disclosure. For example, the CU (310) may transmit four packets using Core #1 and then transmit the next four packets using Core #1 again. As another example, the CU (310) may transmit four packets using Core #1, then transmit the next four packets using Core #2, and then transmit the next four packets using Core #1 again.

[0135] According to embodiments of the present disclosure, the CU (310) can determine how many data packets (e.g., 4 data packets) to transmit in one transmission opportunity when transmitting packets according to the pacing transmission method. In other words, the CU (310) can set the number of packets that can be transmitted per processing unit. By limiting the number of packets that can be transmitted per processing unit, the CU (310) can reduce the packet loss rate at each routing node. Below, a technique for adaptively adjusting the number of packets that can be transmitted per processing unit in the pacing transmission method is described.

[0136] FIG. 9 illustrates the operation flow of a communication device (e.g., CU (310)) for determining a transmission method. The communication device may correspond to an upper network node among upper network nodes and lower network nodes of a distributed arrangement of an access network. For example, the communication device may be a CU (310).

[0137] Referring to FIG. 9, in operation (901), the communication device can determine the network quality for a communication path between the CU and the DU. According to one embodiment, the communication path may include one path physically connecting the CU and the DU and at least one routing node. Each path may represent a physical wiring connecting the nodes. The routing node may include a buffer for receiving data packets as a hub to which the paths are connected. According to one embodiment, the network quality may be determined based on at least one parameter for indicating the network status of the operator. For example, the network quality may be a packet loss rate. For example, the network quality may be the number of packets that can be transmitted per unit time, i.e., the packet rate. For example, the network quality may be a delay parameter. For example, the network quality may be determined based on the time during which a specified number of packets are transmitted. For example, the network quality may be determined based on the number of buffer overflows and the number of transmitted packets.

[0138] In operation (903), the communication device can determine whether the network quality is above a quality threshold. Even if the allowable speeds between the paths connected to the routing node (e.g., the first routing node (650)) differ, the packet loss rate may be reduced as packets waiting to be processed are stored in the buffer (e.g., buffer (651)) of the routing node (e.g., the first routing node (650)). However, if more packets than the capacity of the buffer (e.g., buffer (651)) are received, an overflow may occur. The overflow may cause packet loss. To reduce the frequency of packet loss, the communication device can determine whether the network quality, which indicates the network status for each operator, is above the quality threshold. According to one embodiment, the quality threshold may be predefined. As an example, the quality threshold may be set differently for each operator. The quality threshold may be set by the user of the communication device. As an example, the quality threshold may be determined based on the DU connected through the communication path.

[0139] The communication device may perform an operation (905) based on a determination that the network quality is above a quality threshold. According to one embodiment, the communication device may transmit packets in a burst transmission manner based on a determination that the network quality is above a quality threshold. The communication device may perform an operation (907) based on a determination that the network quality is below a quality threshold. According to one embodiment, the communication device may transmit packets in a pacing transmission manner based on a determination that the network quality is below a quality threshold.

[0140] In operation (905), the communication device can transmit data packets for downlink transmission using a single processing unit. The communication device can schedule the single processing unit among a plurality of processing units to transmit data packets for downlink transmission. Since the communication device has determined that the network condition of the communication path between the CU (310) and the DU (320) provides sufficient network quality for burst transmission, the communication device can schedule the single processing unit to transmit the data packets. For example, if the total number of packets for downlink transmission to be transmitted from the CU (310) to the DU (320) is 12, the communication device can transmit the 12 data packets using the single processing unit. As a single processing unit is used, the data packets can be output through the communication path between the CU (310) and the DU (320) in a single transmission without separate split transmission.

[0141] In operation (907), the communication device can transmit data packets by scheduling them on a per-processing unit basis based on the number of packets that can be transmitted per processing unit. Since the communication device determines that the network condition of the communication path between the CU (310) and the DU (320) does not provide sufficient network quality for burst transmission, the communication device can use a pacing transmission method.

[0142] According to embodiments of the present disclosure, the communication device can determine the packet loss rate for transmission from the CU (310) to the DU (320). According to one embodiment, the communication device can determine the packet loss rate based on a DDDS message from the DU (320). A specific description of the DDDS message is provided through FIG. 10.

[0143] According to embodiments of the present disclosure, the communication device may determine the number of packets that can be transmitted per processing unit based on the packet loss rate. The number of packets that can be transmitted per processing unit refers to the number of packets that are allowed to be processed for transmission in a single processing unit. In other words, the communication device may limit the number of packets allowed to be processed in a single processing unit in a pacing transmission method. As the number of packets allowed to be processed in a single processing unit is limited, the number of packets output by the communication device in a single transmission may be reduced. For example, the number of packets that can be transmitted per processing unit may be 4. A single transmission of 12 packets may be divided into three transmissions of 4 packets. In this case, overhead (or delay) due to scheduling on the processing unit side may increase, but the burden on data processing and buffer capacity on the receiving side (e.g., first routing node (650), second routing node (660), routing node (690)) may be reduced through the gap between transmissions. As a non-limiting example, for example, even if the number of packets that can be transmitted per processing unit is 5, the communication device may divide the 12 packets into 4 / 4 / 4 instead of dividing them into 5 / 5 / 2.

[0144] According to embodiments of the present disclosure, the communication device may schedule in units of processing units based on the number of packets transmittable per processing unit determined. The communication device may schedule at least one processing unit among a plurality of processing units to transmit data packets for the downlink transmission. The scheduled processing unit may be configured to transmit packets no more than the number of packets transmittable per processing unit determined through a communication circuit (e.g., communication circuit (710)). For example, a single transmission of a plurality of packets may be divided into a plurality of transmissions. One transmission among the plurality of transmissions may be referred to as a set of packets. Scheduling may be required for each transmission. The communication device requires at least one processing unit for the plurality of transmissions. For example, the communication device may identify three processing units. The communication device may schedule processing unit #1 to transmit a first set of packets. The communication device may schedule processing unit #2 to transmit the first set of packets and to transmit the second set of packets. After transmitting the second set of packets, the communication device may schedule processing unit #3 to transmit the third set of packets. As an example, but not limited to, one processing unit #1 may be scheduled two or more times.

[0145] According to embodiments of the present disclosure, the communication device can transmit data packets for downlink transmission through the at least one processing unit. By performing scheduling and transmission of a set of packets on a processing unit basis, a transmission pacing effect (e.g., reducing packet loss and delay by transmitting data at a limited rate) can be achieved. Traffic can be transmitted evenly so that losses due to burst traffic can be prevented.

[0146] FIG. 10 illustrates the operation flow of a communication device (e.g., CU (310)) for a pacing transmission method. The communication device may correspond to an upper network node among upper network nodes and lower network nodes of a distributed arrangement of an access network. For example, the communication device may be a CU (310). The operations of FIG. 10 may correspond to the operations (907) of FIG. 9.

[0147] Referring to FIG. 10, in operation (1001), the communication device may measure the packet loss rate based on a DDDS message. The communication device may receive the DDDS message from the DU (320). For the DDDS message, [Table 1] may be referenced. According to one embodiment, the communication device may identify the number of lost packets based on the NR-U SNs received through the DDDS message. The communication device may measure the packet loss rate based on the number of packets. The packets for measuring the packet loss rate may be retransmitted packets. To measure the packet loss rate, the communication device may use the IEs of the DDDS message. For example, the communication device may use the "Number of lost NR-U Sequence Number ranges reported" IE of the DDDS message. The IE may indicate the number of NR-U sequence number ranges reported as lost. For example, the communication device may use the "Start of lost NR-U Sequence Number range" IE of the DDDS message. The IE may indicate the starting number of the NR-U sequence number range to be reported as lost. For example, the communication device may use the "End of lost NR-U Sequence Number range" IE of the DDDS message. The IE may indicate the ending number of the NR-U sequence number range to be reported as lost.

[0148] In operation (1003), the communication device can determine whether the packet loss rate is greater than or equal to a reference loss rate. In a pacing transmission method, if the number of packets that can be transmitted per processing unit is infinite or a very large value (e.g., 10,000), the pacing transmission can be understood as being the same as a burst transmission method. Based on this principle, the larger the number of packets in a single transmission, the higher the probability of packet loss at the routing node. The communication device can determine whether the number of packets that can be transmitted per processing unit currently set is suitable for the network conditions of the operator by comparing the packet loss rate with the reference loss rate. According to one embodiment, the reference loss rate may be predefined. As an example, but not limited to, the reference loss rate may be determined according to the network conditions or requirements of each operator or predefined by user settings.

[0149] In accordance with the determination that the above packet loss rate is greater than or equal to the reference loss rate, the communication device may perform an operation (1005). In accordance with the determination that the above packet loss rate is less than the reference loss rate, the communication device may perform an operation (1007).

[0150] In operation (1005), the communication device may perform reduction control on the number of packets that can be transmitted per processing unit. The reduction control means adjusting the value to a value smaller than the current value or setting it to the minimum value if the currently set value is not the minimum value. If the packet loss rate is greater than or equal to the reference loss rate, the communication device may determine that the number of packets that can be transmitted per processing unit, currently set, is greater than or equal to the number of packets that can be transmitted once per the operator's network condition. Therefore, the reduction control may be performed to reduce the number of packets that can be transmitted per processing unit. According to one embodiment, the minimum value may be predefined. As an example not limited to, the minimum value may be determined by the core performance of each processor within the communication device or predefined by user settings.

[0151] In operation (1007), the communication device may perform increase control on the number of packets that can be transmitted per processing unit. Increase control means adjusting the value to a value greater than the current value or setting it to the maximum value if the currently set value is not the maximum value. If the packet loss rate is less than the reference loss rate, it can be understood that the number of packets that can be transmitted per processing unit, currently set, is smaller than the number of packets that can be transmitted once per the operator's network condition. Therefore, to increase the number of packets that can be transmitted per processing unit, the communication device may perform increase control. According to one embodiment, the maximum value may be predefined. As an example not limited to, the maximum value may be determined by the core performance of each processor within the communication device or predefined by user settings.

[0152] In FIG. 10, an example is described in which a currently set value is adjusted as the number of packets that can be transmitted per processing unit based on a comparison between the packet loss rate and a reference loss rate, but the embodiments of the present disclosure are not limited thereto. According to one embodiment, the number of packets that can be transmitted per processing unit may be set as a value corresponding to the packet loss rate measured among a plurality of candidate values. The communication device can obtain a pacing effect on the F1-U interface (e.g., reducing packet loss and delay by transmitting data at a limited speed) by limiting the number of packets that can be transmitted per processing unit to a value corresponding to the packet loss rate measured among a plurality of candidate values.

[0153] Figure 11 shows an example of the performance of the pacing transmission method.

[0154] Referring to FIG. 11, the graph (1100) represents the number of packet retransmissions (e.g., number of retransmitted packets) over time on the F1-U interface. The horizontal axis of the graph (1100) represents time, and the vertical axis of the graph (1100) represents the number of retransmissions. The first line (1101) represents the number of packet retransmissions in the first region, the second line (1102) represents the number of packet retransmissions in the second region, the third line (1103) represents the number of packet retransmissions in the third region, and the fourth line (1104) represents the number of packet retransmissions in the fourth region. When packets are transmitted in the first region, the pacing transmission technique may be applied. Referring to the first line (1101), the number of packet retransmissions may be reduced as the pacing transmission technique is applied. When transmitting packets in other regions, the above pacing transmission technique may not be used (i.e., burst transmission technique is used). Referring to the graph (1100), the number of retransmissions can be reduced by adjusting the amount of adaptive traffic according to the operator's network conditions according to the pacing transmission technique. Since packets are not lost, the frequency of packet retransmission by the CU (310) can be reduced. In other words, as the loss rate decreases, unnecessary retransmissions are reduced, so the quality of service can be improved.

[0155] Figure 12 shows an example of the performance of the pacing transmission method.

[0156] Referring to FIG. 12, the graph (1200) represents the number of lost packets (hereinafter referred to as lost packets) over time on the F1-U interface. The horizontal axis of the graph (1100) represents time, and the vertical axis of the graph (1100) represents the number of lost packets. The first line (1201) represents the number of lost packets resulting from the transmission of packets in the first region, the second line (1202) represents the number of lost packets resulting from the transmission of packets in the second region, the third line (1203) represents the number of lost packets resulting from the transmission of packets in the third region, and the fourth line (1204) represents the number of lost packets resulting from the transmission of packets in the fourth region. When transmitting packets in the first region, the pacing transmission technique may be applied. Referring to the first line (1201), the number of lost packets may be reduced as the pacing transmission technique is applied. When transmitting packets in other regions, the above-mentioned pacing transmission technique may not be used (i.e., the burst transmission technique is used). Referring to the graph (1200), the number of lost packets can be reduced by adjusting the amount of adaptive traffic according to the operator's network conditions using the pacing transmission technique. The number of lost packets per unit time can be referred to as the packet loss rate. Due to the low packet loss rate, the quality of service can be improved.

[0157] According to embodiments of the present disclosure, a communication device configured to perform the functions of a CU (310) (central unit) is provided. The communication device may include a communication circuit; a memory for storing instructions; and at least one processor comprising a plurality of processing units. The above instructions, when executed by the at least one processor, may cause the communication device to determine the network quality for a communication path between the CU (310) and the DU (320) (distributed unit) connected to the CU (310) based on the communication circuit, determine whether the network quality is above a quality threshold, and, in accordance with the determination that the network quality is above the quality threshold, to transmit data packets for downlink transmission to the DU (320) through the communication circuit using one of the processing units, and in accordance with the determination that the network quality is below the quality threshold, to determine the number of packets that can be transmitted per processing unit based on the packet loss rate for transmission from the CU (310) to the DU (320), and to schedule on a processing unit basis based on the determined number of packets that can be transmitted per processing unit, thereby causing the communication device to transmit data packets for downlink transmission to the DU (320) using at least one of the processing units.

[0158] For example, the above instructions may cause the communication device to transmit a first set of data packets corresponding to the number of packets transmittable per processing unit, and then schedule a second set of data packets different from the first set of data packets among the data packets for downlink transmission, in order to transmit data packets for downlink transmission using the at least one processing unit when executed by the at least one processor. The number of data packets for downlink transmission may be greater than the number of packets transmittable per processing unit determined. A time interval may be formed between the transmission of the first set of data packets and the transmission of the second set of data packets.

[0159] For example, the network quality may be determined based on the packet loss rate of packets transmitted through the communication path between the CU (310) and the DU (320). The communication path between the CU (310) and the DU (320) may each include at least one routing node including a buffer.

[0160] For example, the communication circuit may include a network interface card (NIC). The NIC may be connected to the DU (320) through the communication path. The quality threshold may be a predefined value or may be determined according to the communication path.

[0161] For example, when executed by the at least one processor, the above instructions may cause determining whether the packet loss rate is greater than or equal to a reference loss rate to determine the number of packets that can be transmitted per processing unit based on the packet loss rate, and, in accordance with the determination that the packet loss rate is greater than or equal to the reference loss rate, to adjust the number of packets that can be transmitted per processing unit to a value smaller than a currently set value or to a minimum value, and in accordance with the determination that the packet loss rate is less than the reference loss rate, to adjust the number of packets that can be transmitted per processing unit to a value larger than a currently set value or to a maximum value.

[0162] For example, the above instructions may cause the DU (320) to receive a DDDS (downlink data delivery status) message through the communication circuit to determine the number of packets that can be transmitted per processing unit based on the packet loss rate when executed by the at least one processor, and to determine the packet loss rate based on the DDDS message.

[0163] For example, the above reference loss rate, and the minimum and maximum values ​​of the number of packets that can be transmitted per processing unit may be predefined.

[0164] For example, when executed by the at least one processor, the above instructions may cause to identify a limit value corresponding to the packet loss rate among a plurality of candidate values ​​representing the number of packets allowed to be transmitted per processing unit based on the packet loss rate, and to set the number of packets possible to be transmitted per processing unit with the limit value, in order to determine the number of packets possible to be transmitted per processing unit based on the packet loss rate.

[0165] For example, the CU (310) may be configured to perform the functions of the PDCP (packet data convergence protocol) layer. The DU (320) may be configured to perform the functions of the RLC (radio link control) layer and the MAC (medium access control) layer. Packets between the CU (310) and the DU (320) may be transmitted according to the F1-U protocol.

[0166] For example, the above instructions may cause the communication device to transmit a first set of data packets among the data packets for downlink transmission to the DU (320) through the communication circuit by using a first processing unit scheduled among the plurality of processing units, and after transmitting the first set of data packets, to transmit a second set of data packets among the data packets for downlink transmission to the DU (320) through the communication circuit by using a second processing unit scheduled among the plurality of processing units, in order to transmit data packets for downlink transmission when executed by the at least one processor. The number of data packets in the first set of data packets may be less than or equal to the number of packets transmittable per processing unit. The number of data packets in the second set of data packets may be less than or equal to the number of packets transmittable per processing unit.

[0167] According to embodiments of the present disclosure, a method is provided that is performed by a communication device configured to perform the functions of a CU (310) (central unit). The above method may include an operation to determine network quality for a communication path between the CU (310) and a DU (320) (distributed unit) connected to the CU (310); an operation to determine whether the network quality is above a quality threshold; an operation to transmit data packets for downlink transmission to the DU (320) using one of the processing units of the CU (310) based on the determination that the network quality is above the quality threshold; an operation to determine the number of packets that can be transmitted per processing unit based on the packet loss rate for transmission from the CU (310) to the DU (320) based on the determination that the network quality is below the quality threshold; and an operation to transmit data packets for downlink transmission to the DU (320) using at least one of the processing units by scheduling on a processing unit basis based on the determined number of packets that can be transmitted per processing unit.

[0168] For example, the operation of transmitting data packets for downlink transmission using at least one processing unit may include transmitting a first set of data packets corresponding to the number of packets transmittable per processing unit, and then scheduling second data packets different from the first set of data packets among the data packets for downlink transmission. The number of data packets for downlink transmission may be greater than the number of packets transmittable per processing unit determined. A time interval may be formed between the transmission of the first set of data packets and the transmission of the second set of data packets.

[0169] For example, the network quality may be determined based on the packet loss rate of packets transmitted through the communication path between the CU (310) and the DU (320). The communication path between the CU (310) and the DU (320) may each include at least one routing node including a buffer.

[0170] For example, the CU (310) may be connected to the DU (320) through the communication path. The quality threshold may be a predefined value or determined according to the communication path.

[0171] For example, the operation of determining the number of packets that can be transmitted per processing unit based on the above packet loss rate may include the operation of determining whether the packet loss rate is greater than or equal to a reference loss rate, the operation of adjusting the number of packets that can be transmitted per processing unit to a value smaller than a currently set value or setting it to a minimum value according to the determination that the packet loss rate is greater than or equal to the reference loss rate, and the operation of adjusting the number of packets that can be transmitted per processing unit to a value larger than a currently set value or setting it to a maximum value according to the determination that the packet loss rate is less than or equal to the reference loss rate.

[0172] For example, the operation of determining the number of packets that can be transmitted per processing unit based on the above packet loss rate may include the operation of receiving a DDDS (downlink data delivery status) message from the DU (320) and the operation of determining the packet loss rate based on the DDDS message.

[0173] For example, the above reference loss rate, and the minimum and maximum values ​​of the number of packets that can be transmitted per processing unit may be predefined.

[0174] For example, the operation of determining the number of packets that can be transmitted per processing unit based on the above packet loss rate may include the operation of identifying a limit value corresponding to the packet loss rate among a plurality of candidate values ​​representing the number of packets allowed to be transmitted per processing unit, and the operation of setting the number of packets that can be transmitted per processing unit with the limit value.

[0175] For example, the CU (310) may be configured to perform the functions of the PDCP (packet data convergence protocol) layer. The DU (320) may be configured to perform the functions of the RLC (radio link control) layer and the MAC (medium access control) layer. Packets between the CU (310) and the DU (320) may be transmitted according to the F1-U protocol.

[0176] For example, the operation of transmitting data packets for downlink transmission through at least one processing unit may include the operation of transmitting a first set of data packets among the data packets for downlink transmission to the DU (320) using a first processing unit scheduled among the plurality of processing units, and after transmitting the first set of data packets, transmitting a second set of data packets among the data packets for downlink transmission to the DU (320) using a second processing unit scheduled among the plurality of processing units. The number of data packets in the first set of data packets may be less than or equal to the number of packets that can be transmitted per processing unit. The number of data packets in the second set of data packets may be less than or equal to the number of packets that can be transmitted per processing unit.

[0177] According to embodiments of the present disclosure, burst transmission techniques and pacing transmission techniques may be adaptively utilized depending on the network conditions of the operator. When a pacing transmission technique is utilized, buffer overflow, jitter, and / or packet loss of traffic may be reduced by limiting the number of packets that can be processed (i.e. transmitted) per core. Due to the reduced packet loss rate, a stable service of high quality may be provided.

[0178] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0179] For one or more embodiments, at least one of the components described in one or more of the prior art drawings may be configured to perform one or more operations, techniques, processes and / or methods as described in the present disclosure. For example, a processor (e.g., a baseband processor) described in the present disclosure in relation to one or more of the prior art drawings may be configured to operate according to one or more examples described in the present disclosure. As another example, circuits associated with user equipment (UE), a base station, a network element, etc., as described above in relation to one or more of the prior art drawings may be configured to operate according to one or more examples described herein.

[0180] Any of the embodiments described above may be combined with any other embodiment (or combination of embodiments) unless otherwise explicitly stated. The foregoing description of one or more embodiments is for illustrative and explanatory purposes only, and is not intended to limit or exhaust the scope of the embodiments in the exact form disclosed. Modifications and variations are possible in light of the foregoing teachings or may be obtained from the practice of various embodiments.

[0181] Methods according to the claims or embodiments described in the specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0182] When implemented in software, a computer-readable storage medium (e.g., a non-transient computer-readable storage medium) storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to the claims or embodiments described in the specification of this disclosure. The one or more programs may be provided as a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or distributed online (e.g., download or upload) through an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0183] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disc storage devices, compact disc-ROM (CD-ROM), digital versatile discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0184] Additionally, the program may be stored on an attachable storage device that can be accessed via a communication network such as the Internet, Intranet, LAN (local area network), WAN (wide area network), or SAN (storage area network), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present disclosure.

[0185] In the specific embodiments of the present disclosure described above, the components included in the disclosure are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed of a singular form, and even if a component is expressed in the singular form, it may be composed of a plural form.

[0186] According to the embodiments, one or more of the aforementioned components or operations may be omitted, or one or more other components or operations may be added. Generally or additionally, a plurality of components (e.g., a module or a program) may be integrated into a single component. In this case, the integrated component may perform one or more functions of each of the plurality of components in the same or similar manner as those performed by the corresponding component among the plurality of components prior to the integration. According to the embodiments, operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0187] Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, it is understood that various modifications are possible within the scope of the present disclosure.

Claims

1. In a communication device configured to perform the functions of a CU (central unit), Communication circuit; Memory for storing instructions; and It includes at least one processor comprising a plurality of processing units, and When the above instructions are executed by the above at least one processor, the communication device: Based on the above communication circuit, determine the network quality for the communication path between the CU and the DU (distributed unit) connected to the CU, and Determine whether the above network quality is above a quality threshold, and Based on the determination that the network quality is above the quality threshold, data packets for downlink transmission are transmitted to the DU through the communication circuit using one of the plurality of processing units, and Based on the determination that the above network quality is below the above quality threshold: The number of packets that can be transmitted per processing unit is determined based on the packet loss rate for transmission from the above CU to the above DU, and By scheduling on a processing unit basis based on the number of packets transmittable per processing unit determined above, causing at least one processing unit among the plurality of processing units to transmit data packets for the downlink transmission to the DU through the communication circuit, Communication device.

2. In Claim 1, When the above instructions are executed by the at least one processor, the communication device for transmitting data packets for the downlink transmission using the at least one processing unit: After transmitting a first set of data packets corresponding to the number of packets transmittable per processing unit, cause to schedule a second set of data packets different from the first set of data packets among the data packets for downlink transmission, and The number of data packets for the above downlink transmission is greater than the number of packets transmittable per the above-determined processing unit, and A time interval is formed between the transmission of the first set of data packets and the transmission of the second set of data packets. Communication device.

3. In Claim 2, The above network quality is determined based on the packet loss rate of packets transmitted through the communication path between the CU and the DU, and The communication path between the CU and the DU each includes at least one routing node including a buffer, Communication device.

4. In Claim 3, The above communication circuit includes a NIC (network interface card), and The above NIC is connected to the above DU through the above communication path, and The above quality threshold is a predefined value or is determined according to the above communication path, Communication device.

5. In Claim 1, The above instructions, when executed by the at least one processor, are for determining the number of packets that can be transmitted per processing unit based on the packet loss rate, Determine whether the above packet loss rate is greater than or equal to the reference loss rate, and Based on the determination that the above packet loss rate is greater than or equal to the reference loss rate, the number of packets that can be transmitted per processing unit is adjusted to a value smaller than the currently set value or set to a minimum value, and Causing the number of packets transmittable per processing unit to be adjusted to a value greater than the currently set value or set to the maximum value, based on the determination that the above packet loss rate is less than the above reference loss rate. Communication device.

6. In Claim 5, The above instructions, when executed by the at least one processor, are for determining the number of packets that can be transmitted per processing unit based on the packet loss rate, Receive a DDDS (downlink data delivery status) message from the above DU through the communication circuit, and Causing to determine the packet loss rate based on the above DDDS message, Communication device.

7. In Claim 5, The above reference loss rate, the minimum and maximum values ​​of the number of packets transmittable per processing unit are predetermined, Communication device.

8. In Claim 1, The above instructions, when executed by the at least one processor, are for determining the number of packets that can be transmitted per processing unit based on the packet loss rate, Identifying a limit value corresponding to the packet loss rate among a plurality of candidate values ​​representing the number of packets allowed to be transmitted per processing unit, and Causing to set the number of packets transmittable per processing unit with the above limit value, Communication device.

9. In Claim 1, The above CU is configured to perform the functions of the PDCP (packet data convergence protocol) layer, and The above DU is configured to perform the functions of the RLC (radio link control) layer and the MAC (medium access control) layer, and The packets between the above CU and the above DU are transmitted according to the F1-U protocol, Communication device.

10. In Claim 1, When the above instructions are executed by the at least one processor, the communication device for transmitting data packets for the downlink transmission using the at least one processing unit: Using a first processing unit scheduled among the plurality of processing units, a first set of data packets among the data packets for the downlink transmission are transmitted to the DU through the communication circuit, and After transmitting the first set of data packets, using a second processing unit scheduled among the plurality of processing units, cause the second set of data packets among the data packets for the downlink transmission to be transmitted to the DU through the communication circuit, and The number of data packets in the first set of data packets is less than or equal to the number of packets that can be transmitted per processing unit, and The number of data packets in the second set of data packets is less than or equal to the number of packets transmittable per processing unit, Communication device.

11. A method performed by a communication device configured to perform the functions of a CU (central unit), An operation to determine the network quality of a communication path between the above CU and a DU (distributed unit) connected to the above CU, and An operation to determine whether the above network quality is above a quality threshold, and An operation of transmitting data packets for downlink transmission to the DU using one of the processing units among the plurality of processing units of the CU, based on a determination that the network quality is above the quality threshold; and Based on the determination that the above network quality is below the above quality threshold: An operation to determine the number of packets that can be transmitted per processing unit based on the packet loss rate for transmission from the above CU to the above DU, and The operation of transmitting data packets for downlink transmission to the DU using at least one processing unit among the plurality of processing units by scheduling on a processing unit basis based on the number of packets transmittable per processing unit determined above, method.

12. In Claim 11, The operation of transmitting data packets for the downlink transmission using the above at least one processing unit is: After transmitting a first set of data packets corresponding to the number of packets transmittable per processing unit, the method includes the operation of scheduling second data packets different from the first set of data packets among the data packets for downlink transmission. The number of data packets for the above downlink transmission is greater than the number of packets transmittable per the above-determined processing unit, and A time interval is formed between the transmission of the first set of data packets and the transmission of the second set of data packets. method.

13. In Claim 12, The above network quality is determined based on the packet loss rate of packets transmitted through the communication path between the CU and the DU, and The communication path between the CU and the DU each includes at least one routing node including a buffer, method.

14. In Claim 13, The above CU is connected to the above DU through the above communication path, and The above quality threshold is a predefined value or is determined according to the above communication path, method.

15. In Claim 11, The operation of determining the number of packets that can be transmitted per processing unit based on the above packet loss rate is: An operation to determine whether the above packet loss rate is greater than or equal to a reference loss rate, and An operation to adjust the number of packets transmittable per processing unit to a value smaller than the currently set value or to a minimum value, based on a determination that the above packet loss rate is greater than or equal to the reference loss rate, and Based on the determination that the above packet loss rate is less than the above reference loss rate, the operation includes adjusting the number of packets transmittable per processing unit to a value greater than the currently set value or setting it to the maximum value. method.

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