KR20200061295A - Method for transmitting data packet at low latency and appratus therefor - Google Patents

Abstract

An operation method of a communication node is disclosed. According to an embodiment of the present invention, the operation method of the communication node may comprise the steps of: receiving a first data packet from a second communication node; estimating a congestion window size of the second communication node based on a size of the first data packet; determining whether the data reception rate of the first data packet is stable based on the estimated congestion window size; if it is determined that the data reception rate is stable, resetting a reception window size; transmitting a second data packet including information on the reception window size to the second communication node; and receiving a third data packet from the second communication node through the reception window.

Description

METHOD FOR TRANSMITTING DATA PACKET AT LOW LATENCY AND APPRATUS THEREFOR}

The present invention relates to a method and apparatus for transmitting data packets in a communication system, and more particularly, to a method and apparatus for transmitting low-latency data packets.

The 5th generation mobile communication, which aims to support Gbps (Giga bps) level, which is at least 10 to 100 times the data transfer rate than the 4th generation mobile communication, includes not only the existing mobile communication frequency band but also tens of GHz (Giga Herz) frequency band. . The 5th generation mobile communication provides not only enhanced mobile broadband (eMBB) for supporting ultra-high data rates, but also mass machine type communication (mMTC) for supporting the Internet of Things and ultra-reliable and low latency communication (URLLC). Aim to apply.

On the other hand, Transmission Control Protocol (TCP) technology for cellular networks may include User Datagram Protocol (UDP) based technologies such as Quick UDP Internet Connections (QUIC) and Channel Quality Indicator Control (CQIC), and PROXY based technologies. have.

In the case of UDP-based technology among TCP technologies, the receiving node can measure the channel quality and deliver it to the transmitting node. The transmitting node can determine the data packet transmission rate using the channel quality measured by the receiving node. However, in this case, a case in which the protocols of the transmitting node and the receiving node are changed may occur. Accordingly, effective control may be difficult in an environment in which a delay of acknowledgment (ACK) is large.

In addition, in the case of a proxy-based technology among TCP technologies, the receiving node may reset the size of the receiving window of the receiving node. However, in the case of a proxy-based technique, the number of congested data packets in a wired network may increase depending on the size of the reception window of the receiving node, or the efficiency may decrease due to a decrease in the use of the radio link. In the case of the current TCP technology, a delay time of data packet transmission may be increased, and a problem that a transmission rate is lowered may occur.

An object of the present invention for solving the above problems is to provide a method and apparatus for transmitting a low-latency data packet.

A method of operating a first communication node according to an embodiment of the present invention for achieving the above object comprises receiving a first data packet from a second communication node. Estimating the congestion window size of the second communication node based on the size of the first data packet, determining whether the data reception rate of the first data packet is stable based on the estimated congestion window size, the data If it is determined that the reception rate is stable, resetting the reception window size, transmitting a second data packet including information about the reception window size to the second communication node, and the second communication node through the reception window It may include the step of receiving a third data packet from.

According to the present invention, the transmission delay of the data packet can be reduced by the base station receiving the data packet from the core network and rapidly transmitting an acknowledgment (ACK).

In addition, according to the present invention, by improving the transmission performance of TCP (Transmission Control Protocol) by resetting the size of the receiving window, without modifying the protocol of the core network and the terminal, the transmission delay of the data packet can be reduced. .

Furthermore, according to the present invention, since the base station resets the size of the reception window in a manner that minimizes the queue size, it is possible to prevent congestion of data packets occurring in the wired network between the core network and the base station, The wireless network between the base station and the terminal can be used efficiently. Therefore, the performance of the communication system can be improved.

1 is a conceptual diagram showing a first embodiment of a communication system.
2 is a block diagram showing an embodiment of a communication node constituting a communication system.
3 is a conceptual diagram showing a second embodiment of a communication system.
4 is a flowchart illustrating a method for transmitting and receiving data packets in a communication system.
5 is a graph showing a queue prediction function in a communication system.
6 is a graph showing a queue prediction function in a communication system.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. The term and/or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but there may be other components in between. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “include” or “have” are intended to indicate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the overall understanding in describing the present invention, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted.

1 is a conceptual diagram showing a first embodiment of a communication system.

Referring to Figure 1, the communication system 100 is a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of terminals (user equipment, 30-1, 130-2, 130-3, 130-4, 130-5, 130-6). Also, although not shown in the drawings, the communication system 100 may include a core network.

Here, the communication system may be referred to as a "communication network". A plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5) , 130-6) and each of the core networks may support at least one communication protocol.

For example, a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (130-1, 130-2, 130-3, 130-4 , 130-5, 130-6) and the core network, respectively, a communication protocol based on code division multiple access (CDMA), a communication protocol based on wideband CDMA (WCDMA), a communication protocol based on time division multiple access (TDMA), and FDMA ( communication protocol based on frequency division multiple access, communication protocol based on orthogonal frequency division multiplexing (OFDM), communication protocol based on orthogonal frequency division multiple access (OFDMA), communication protocol based on single carrier (SC)-FDMA, and NOMA It can support communication protocol based on orthogonal multiple access (SDMA), communication protocol based on space division multiple access (SDMA). A plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5) , 130-6) and each of the core networks may have the following structure.

2 is a block diagram showing an embodiment of a communication node constituting a communication system.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, and the like. Each of the components included in the communication node 200 may be connected by a bus 270 to communicate with each other. However, each component included in the communication node 200 may be connected through a separate interface or a separate bus centered on the processor 210, not the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transceiver 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface. .

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be configured as at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may be configured as at least one of read only memory (ROM) and random access memory (RAM).

Referring back to FIG. 1, each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the coverage of the third base station 110-3. . The first terminal 130-1 may belong to the coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the coverage of the fifth base station 120-2.

Here, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) g node B (gNB; next generation Node B), Node B (NodeB), upgraded Node B (evolved NodeB), base transceiver station (BTS), radio base station, radio transceiver, access point, access node, road side unit (RSU), Referred to as a digital unit (DU), cloud digital unit (CDU), radio remote head (RRH), radio unit (RU), transmission point (TP), transmission and reception point (TRP), relay node, etc. You can. Each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) is a terminal, an access terminal, a mobile terminal, It may be referred to as a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, or the like.

A plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5) , 130-6) Cellular communication (e.g., LTE (Long Term Evolution), LTE-A (advanced), 5G NR (new RAT), etc., defined in the 3rd generation partnership project (3GPP) standard) Can support

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other through an ideal backhaul or a non-ideal backhaul, and the ideal backhaul Alternatively, information can be exchanged with each other through a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network (not shown) through an ideal backhaul or a non-ideal backhaul. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) receives a signal received from the core network corresponding to the terminal (130-1, 130-2, 130-3, 130) -4, 130-5, 130-6), and the core network receives signals received from the corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6. Can be transferred to.

Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can support OFDMA-based downlink transmission, and SC-FDMA-based uplink (uplink) ) Can support transmission. In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits multiple input multiple output (MIMO) (eg, single user (SU)-MIMO, MU (multi user)-MIMO, massive MIMO, etc., CoMP (coordinated multipoint) transmission, carrier aggregation (carrier aggregation) transmission, transmission in an unlicensed band (unlicensed band), device-to-device direct (device to device, D2D) ) Communication (or ProSe (proximity services), etc.), where a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) each base station (110-1, 110-2, 110-3, 120-1, 120-2) and corresponding operation, by the base station (110-1, 110-2, 110-3, 120-1, 120-2) Supported operations can be performed.

Core networks include application function (AF), access and mobility management function (AMF), authentication server function (AUSF), network exposure function (NEF), network repository function (NRF), network slice selection function (NSSF), and policy (PCF). control function (SMF), session management function (SMF), unified data management (UDM), and user plane function (UPF). The structure of the core network may be a structure in which AMF and SMF are separated from the core network.

The AMF can manage the location information and mobility information of the terminal. The AMF may be connected to the terminal through an N1 reference point, and may be connected through a base station (radio access network, (RAN)) and an N2 reference point. In addition, the AMF may transmit location information and mobility information of the terminal received from the base station and the terminal to the core network through the Namf basic interface connected to the core network.

The SMF can process a function of managing a PDU session, such as establishing, changing, and releasing a protocol data unit (PDU) session connected between the terminal and the base station and the core network. The SMF can be connected to the core network through the Nsmf basic interface, and can be connected through the UPF and N4 reference points. UPF can be connected through SMF and N4 reference point, and can establish a session between the terminal and the core network by approving the session connection request from SMF.

3 is a block diagram showing an embodiment of a communication system according to a second embodiment of the present invention.

Referring to FIG. 3, a communication system may include a core network 310, a base station 320, and a terminal 330. The core network 310, the base station 320, and the terminal 330 of FIG. 3 may be configured the same or similar to the core network, the base stations 110, 120, and the terminal 130 of FIG.

The core network 310 may include a serving gateway (S-GW) and a mobility management entity (MME) when the communication system is an LTE communication system. The core network 310 may communicate with the base station 320 through the S-GW for a data packet containing user data, and may communicate with a data packet containing control information through the MME. .

Meanwhile, when the communication system is an NR communication system, the core network 310 may perform communication on a data packet including user data through the base station 320 and UPF, and data including control information through SMF Packets can be communicated.

A Transmission Control Protocol (TCP) connection may be established between the core network 310 and the terminal 330. The core network 310 and the terminal 330 may establish a TCP connection through the base station 320. The core network 310 may transmit data packets to the base station 320. The core network 310 may transmit a data packet to the base station 320 through S-GW (for a LTE communication system) or UPF (for an NR communication system). The size of the data packet may be determined according to the congestion window size of the core network 310. The base station 320 may receive a data packet from the core network 310 and estimate the congestion window size of the core network 310 based on the data packet.

The base station 320 may generate a hybrid automatic repeat request (HARQ) response for the data packet and transmit it to the core network 310. Here, the HARQ response may be ACK (acknowledge). Even before the base station 320 transmits the data packet received from the core network 310 to the terminal 330, the base station 320 may generate an ACK and transmit it to the core network 310.

The core network 310 may receive an ACK from the base station 320. The core network 310 may receive an ACK from the base station 320 through S-GW (for a LTE communication system) or UPF (for an NR communication system).

 Upon receiving the ACK, the core network 310 may increase the congestion window size. Whenever the ACK is received from the base station 320, the core network 310 may increase the congestion window size. Accordingly, the size of a data packet that the core network 310 transmits to the base station 320 may also increase according to the number of times the ACK is received.

For example, the core network 310 can generate a first data packet. The congestion window size of the core network 310 may be 1, and the size of the first data packet may be 1. The core network 310 may transmit the first data packet to the base station 320. The core network 310 may receive an ACK from the base station 320. The core network 310 may increase the congestion window size to 2, and set the minimum value of the congestion window size to 1. The core network 310 may generate a second data packet. The size of the second data packet may be 2. The core network 310 may transmit a second data packet to the base station 320. In this way, whenever the ACK is received from the base station 320, the core network 310 may increase the congestion window size, and accordingly, the size of the data packet transmitted to the base station 320 may be increased. .

으로 증가 시킬 수 있고 혼잡 윈도우 크기의 최솟값을

로 설정할 수 있다. 코어 네트워크(310)는 크기가

인 N-1 번째 데이터 패킷을 생성할 수 있고, 기지국(320)에 N-1 번째 데이터 패킷을 전송할 수 있다. 기지국(320)은 코어 네트워크(310)로부터 N-1 번째 데이터 패킷을 수신할 수 있고, N번째 ACK를 전송할 수 있다.Meanwhile, the base station 320 may transmit an ACK so that the size of the data packet (the size of the congestion window of the core network) received from the core network 310 is maintained below the size of the reception window of the base station 320. For example, if the core network 310 receives the N-1 th ACK from the base station 320, the congestion window size is

And increase the minimum of the congestion window size.

Can be set to The core network 310 has a size

An N-1 th data packet may be generated, and the N-1 th data packet may be transmitted to the base station 320. The base station 320 may receive the N-1 th data packet from the core network 310 and may transmit the N th ACK.

로 증가 시킬 수 있고, 혼잡 윈도우 크기의 최솟값을

로 설정할 수 있다. 코어 네트워크(310)는 크기가

인 N 번째 데이터 패킷을 생성할 수 있고, 기지국(320)에 N 번째 데이터 패킷을 전송할 수 있다. 기지국(320)은 코어 네트워크(310)로부터 N 번째 데이터 패킷을 수신할 수 있다. 기지국(320)의 수신 윈도우의 크기가

미만인 경우, 기지국(320)은 데이터 패킷을 정상적으로 수신하지 못할 수 있고, ACK를 생성하지 않을 수 있다.The core network 310 may receive an N-th ACK from the base station 320. The core network 310 adjusts the congestion window size.

Can be increased to the minimum value of the congestion window size.

Can be set to The core network 310 has a size

An N-th data packet may be generated, and the N-th data packet may be transmitted to the base station 320. The base station 320 may receive an N-th data packet from the core network 310. The size of the reception window of the base station 320

If less than, the base station 320 may not receive the data packet normally, and may not generate an ACK.

로 설정할 수 있다. 즉, 코어 네트워크(310)의 혼잡 윈도우 크기는 기지국(320)의 초기 수신 윈도우의 크기에 의해 제한 될 수 있다. 이와 같이, 혼잡 윈도우 크기가 초기 수신 윈도우 크기에 의해 제한 되기 시작하는 시점부터, 기지국(320)의 데이터 수신율이 안정되었다고 판단할 수 있다. 여기에서, 데이터 수신율은 기지국(320)이 코어 네트워크(310)로부터의 수신하는 데이터 패킷의 수신율일 수 있다.When the ACK is not received from the base station 320, the core network 310 sets the congestion window size to the minimum value of the congestion window size.

Can be set to That is, the congestion window size of the core network 310 may be limited by the size of the initial reception window of the base station 320. As described above, it can be determined that the data reception rate of the base station 320 is stable from the time when the congestion window size starts to be limited by the initial reception window size. Here, the data reception rate may be a reception rate of a data packet that the base station 320 receives from the core network 310.

The initial state from the time when the TCP connection is established between the core network 310 and the terminal 330 to the time when the congestion window size of the core network 310 starts to be limited by the size of the initial reception window of the base station 320 It can be referred to as a (start-up phase), and can be referred to as a steady phase after the initial state has ended.

In the stable state, the maximum value of the congestion window size of the core network 310 may be reset by the size of the reception window of the base station 320. The base station 320 may transmit a data packet including information about the size of the reception window to the core network 310. The core network 310 may receive a data packet from the base station 320 and may reset the maximum value of the congestion window size based on information included in the data packet.

The base station 320 may include an LLTCP (Low Latency TCP) Agent. LLTCP may be a transport layer protocol for low-latency cellular networks. For example, LLTCP may be any one of TCP CUBIC and NewReno. The base station 320 may form a wireless network with the terminal 330. The base station 320 may transmit a data packet to the terminal 330. The base station 320 may transmit the data packet received from the core network 310 to the terminal 330.

The terminal 330 may receive a data packet from the base station 320. The terminal 330 may generate an HARQ response to the data packet, and may transmit an HARQ response to the base station 320. The base station 320 may receive an HARQ response from the terminal 330. The base station 320 may pass HARQ responses to the core network 310. The core network 310 may receive an HARQ response from the base station 320 through S-GW (for a LTE communication system) or UPF (for an NR communication system).

In the stable state, the base station 320 may reset the size of the reception window. The base station 320 may reset the size of the reception window to minimize the size of the queue. Here, the queue size may be the sum of the size of data packets that the base station 320 intends to transmit to the terminal 330, and the data packets may be data packets stored in the transmission buffer of the base station 320.

The base station 320 may reset the size of the reception window based on the change value of the data reception rate in the wireless network. Here, the data reception rate may be a reception rate of a data packet of the terminal 330 that the terminal 330 receives from the base station 320. The base station 320 may generate a data packet including information about the size of the reception window, and may transmit the data packet to the core network 310. The core network 310 may receive a data packet and reset the congestion window size based on information included in the data packet.

The terminal 330 may transmit a data packet to the base station 320. The base station 320 may receive a data packet from the terminal. The base station 320 may generate an HARQ response to the data packet, and may transmit an HARQ response to the terminal 330. The terminal 330 may receive an HARQ response from the base station 320. When the terminal 330 receives the ACK in response to the HARQ response from the base station 320, the terminal 330 may not retransmit the data packet to the base station 320. When the terminal 330 receives a negative ack (NACK) response as a HARQ response from the base station 320, the terminal 330 may retransmit a data packet to the base station 320.

4 is a flowchart illustrating a method for transmitting and receiving data packets in a communication system, and FIGS. 5 to 6 are graphs showing a queue prediction function in a communication system. 4 may include FIGS. 4A and 4B.

Referring to FIG. 4, the core network, terminal, and base station of FIG. 4 may be configured the same as or similar to the core network, terminal, and base station of FIG. 3. In FIG. 4, steps S405 to S450 may be initial stages, and steps S460 to S510 may be stable stages.

A TCP connection may be established between the terminal and the core network (S405). A TCP connection may be established between the terminal and the core network through a base station. In step S405, the size of the reception window of the base station may be the size of the initial reception window. The core network may generate a first data packet (S410). The size of the first data packet may be an initial congestion window size, and the first data packet may include data that the core network intends to transmit to the terminal. The core network may transmit the first data packet to the base station (S415). The core network may transmit the first data packet to the base station through S-GW (for a LTE communication system) or UPF (for an NR communication system).

The base station may receive the first data packet from the core network (S415). The base station may estimate the congestion window size based on the size of the first data packet (S420). If it is determined that the estimated congestion window size is equal to or less than the size of the initial reception window, the base station may generate an HARQ response itself (S425). Here, the HARQ response may be ACK. Even before transmitting the first data packet from the terminal, the base station can generate an ACK itself if it is determined that the estimated congestion window size is less than or equal to the size of the initial reception window. The base station may transmit the HARQ response to the core network (S430). Here, the HARQ response may be ACK.

The core network may receive an HARQ response (eg, ACK) from the base station (S430). The core network may receive an ACK from the base station through S-GW (for a LTE communication system) or UPF (for an NR communication system). Upon receiving the ACK, the core network may increase the congestion window size (S435). For example, if the congestion window size is the initial congestion window size, and the initial congestion window size is 1, the core network may increase the congestion window size to 2, and set the minimum value of the congestion window size to 1.

Meanwhile, the base station may transmit the first data packet to the terminal (S440). The base station may transmit the first data packet received from the core network to the terminal in step S415. The terminal may receive the first data packet from the base station (S440). The terminal may generate an HARQ response to the first data packet (S445). When the first data packet is normal, the UE may generate an ACK as an HARQ response, and when the first data packet is abnormal, an NACK as an HARQ response. The terminal may transmit the HARQ response to the base station (S450).

The base station may receive the HARQ response from the terminal (S450). The base station may not perform retransmission of the first data packet to the terminal when receiving the ACK in the HARQ response, and may perform retransmission of the first data packet to the terminal when receiving the NACK in the HARQ response. Meanwhile, the base station may determine whether the data reception rate is stable (S455). The data reception rate may be a reception rate of data packets that the base station receives from the core network. Steps S410 to S450 may be repeatedly performed, and the base station may determine whether the data reception rate is stable based on a result of the iteration (for example, a rate of change in the congestion window size).

For example, if the ACK is received from the base station, the core network may increase the congestion window size. The core network may generate data packets corresponding to the increased congestion window size, and may transmit data packets to the base station. Such a process may be repeatedly performed until the size of the data packet generated by the core network exceeds the size of the initial reception window of the base station.

The base station can receive the data packet from the core network, and when it is determined that the sum of the sizes of the received data packets is equal to or less than the size of the initial reception window, the base station may determine that the data reception rate is not stable. Meanwhile, the core network can generate a data packet and transmit the data packet to a base station. The size of the data packets may be the same as the size of the initial receive window. When the base station can receive a data packet and determines that the sum of the size of the received data packet is equal to the size of the initial reception window, the base station can determine that the data reception rate is stable.

If it is determined that the data reception rate is stable, the base station may reset the size of the reception window (S460). The base station may reset the size of the reception window to minimize the size of the queue (LLTCP's queue). The base station may reset the size of the reception window according to Equation 1 below.

[Equation 1]

은 변경된 수신 윈도우의 크기일 수 있고,

는 코어 네트워크와 기지국 사이의 최소 RTT(Round-Trip delay Time)일 수 있으며,

는 단말이 기지국으로부터 수신하는 데이터 패킷의 데이터 수신율일 수 있고,

는 수신 윈도우의 오프셋일 수 있다. 수신 윈도우의 오프셋의 초기값은 0일 수 있다. 한편, 기지국은 수신 윈도우의 오프셋을 조정하는 방식으로, 수신 윈도우의 크기를 재설정할 수 있다. 기지국은 대기열 크기를 기초로 수신 윈도우의 오프셋을 조정할 수 있다. 예를 들어, 기지국은 대기열 크기의 변화를 예측하여 수신 윈도우의 오프셋을 조정할 수 있다.From here,

Can be the size of the modified receive window,

May be the minimum round-trip delay time (RTT) between the core network and the base station,

Is a data reception rate of a data packet that the terminal receives from the base station,

May be the offset of the receiving window. The initial value of the offset of the reception window may be 0. Meanwhile, the base station may reset the size of the reception window by adjusting the offset of the reception window. The base station can adjust the offset of the reception window based on the queue size. For example, the base station can adjust the offset of the reception window by predicting a change in the queue size.

)부터 제2 시점(예를 들어,

)까지 단말이 기지국으로부터 수신하는 데이터 패킷의 데이터 수신율(

)이 변화하지 않은 경우, 제1 시점부터 제2 시점까지의 대기열 크기를 현재 대기열 크기의 예측 값으로 설정할 수 있다. 예를 들어, 제1 시점부터 제2 시점까지의 대기열 크기(

)가

인 경우, 기지국은 대기열 크기의 예측 값(

)을

으로 설정할 수 있다.A preset first time point (for example,

) To the second point (for example,

) To the data reception rate of the data packet that the terminal receives from the base station (

) Does not change, the queue size from the first time point to the second time point may be set as a predicted value of the current queue size. For example, the queue size from the first time point to the second time point (

)end

If is, the base station estimates the queue size (

)of

Can be set to

)이 변화한 경우, 기지국은 미리 설정된 대기열 예측 함수(예를 들어,

)에 의해 대기열 크기의 예측 값을 설정할 수 있다. 여기에서,

은

시점 이전에서의 데이터 수신율일 수 있고,

은

시점 이후에서의 데이터 수신율일 수 있으며,

은

에서 대기열 크기일 수 있고,

는

에서 대기열 크기일 수 있으며,

은

시점 이후에서 대기열 크기일 수 있다.Alternatively, the data reception rate between the first time point and the second time point (

) Is changed, the base station may set a preset queue prediction function (for example,

) To set the predicted value of the queue size. From here,

silver

It may be the data reception rate before the time point,

silver

It may be a data reception rate after the point in time,

silver

In queue size,

The

In queue size,

silver

It may be the queue size after the point in time.

)이 증가한 경우, 대기열 예측 함수는 도 5에 도시된 그래프와 같을 수 있고, 데이터 수신율(

)이 감소한 경우, 대기열 예측 함수는 도 6에 도시된 그래프와 같을 수 있다. 기지국은 대기열 크기의 예측 값(

)을 윈도우 오프셋의 예측 값(

)과 더할 수 있고, 그 결과(

+

)에서 현재 대기열 크기(

)를 뺄 수 있고, 그 결과(

+

-

)와 미리 설정한 제1 임계값(

)을 비교할 수 있다. 기지국은 비교 결과에 기초하여 수신 윈도우의 윈도우 오프셋의 변화 값(

)을 설정할 수 있다.Data reception rate (

) Increases, the queue prediction function may be the same as the graph shown in FIG. 5, and the data reception rate (

) Decreases, the queue prediction function may be the same as the graph shown in FIG. 6. The base station estimates the queue size (

) Is the predicted value of the window offset (

) And the result (

+

) To the current queue size (

) Can be subtracted, and the result (

+

-

) And a preset first threshold (

). The base station changes the window offset of the received window based on the comparison result (

) Can be set.

+

-

이

를 초과하면(

,

를 -1로 설정할 수 있고,

+

-

이

미만 이면(

,

를 1로 설정할 수 있으며. 차이값이

이상이고

이하인 경우(

,

를 0으로 설정할 수 있다.For example, the base station

+

-

this

If exceeds (

,

Can be set to -1,

+

-

this

Less than (

,

Can be set to 1. Difference value

Over

If less than (

,

Can be set to 0.

)와 미리 설정한 제2 임계값의 차이값(

-제2 임계값)과, 제1 임계값(

)를 비교하여, 윈도우 오프셋의 변화 값(

)을 설정할 수 있다. 예를 들어, 미리 설정한 제2 임계값은

에서의 대기열 크기인

일 수 있고 이때 차이값은

-

일 수 있다.Alternatively, the base station has the current queue size (

) And the preset second threshold value (

-Second threshold) and first threshold (

), and the change value of the window offset (

) Can be set. For example, the preset second threshold value is

The queue size at

And the difference value is

-

Can be

이

를 초과하면(

,

를 -1로 설정할 수 있고,

-제2 임계값이

미만 이면(

,

를 1로 설정할 수 있으며. 이

이상이고

이하인 경우(

,

를 0으로 설정할 수 있다.For example, the base station

this

If exceeds (

,

Can be set to -1,

-The second threshold

Less than (

,

Can be set to 1. this

Over

If less than (

,

Can be set to 0.

및 현재의 윈도우 오프셋 값(

) 기초로, 수신 윈도우의 윈도우 오프셋 값(

)을 조정할 수 있다. 기지국은

이 -1인 경우,

을

로 조정할 수 있고,

이 0인 경우,

을

로 조정할 수 있으며,

이 1인 경우,

을

로 조정할 수 있다.Base station set

And the current window offset value (

), based on the window offset value of the receive window (

) Can be adjusted. The base station

If is -1,

of

Can be adjusted to

If is 0,

of

Can be adjusted to

If 1,

of

Can be adjusted.

The base station may reset the size of the reception window according to Equation 1 based on the set window offset value. The base station may generate a second data packet (S465). In step S460, the second data packet may include information about the size of the reset reception window. The base station may transmit a second data packet to the core network (S470).

인 경우, 코어 네트워크는 혼잡 윈도우 크기의 최대 값은

이하로 제한할 수 있다.The core network may receive a second data packet from the base station (S470). The core network may receive a second data packet from the base station through S-GW (for a LTE communication system) or UPF (for an NR communication system). The core network may reset the maximum value of the congestion window size based on information on the size of the reception window included in the second data packet (S475). The core network may reset the congestion window size by limiting the congestion window size to the size of the reception window or less. For example, the size of the receiving window

If the core network is, the maximum value of the congestion window size is

It can be limited to the following.

이하 일 수 있다. 코어 네트워크는 제3 데이터 패킷을 기지국에 전송할 수 있다(S485). 코어 네트워크는 S-GW(LTE 통신 시스템인 경우) 또는 UPF(NR 통신 시스템인 경우)를 통해 기지국에 제3 데이터 패킷을 전송할 수 있다.The core network may generate a third data packet (S480). The sum of the sizes of the third data packets being transmitted in the core network may be equal to or less than the congestion window size reset in step S470. For example, the total sum of the third data packets being transmitted is

It can be below. The core network may transmit a third data packet to the base station (S485). The core network may transmit a third data packet to the base station through S-GW (for a LTE communication system) or UPF (for an NR communication system).

The base station may receive a third data packet from the core network (S485). The base station may transmit the third data packet to the terminal (S490). The terminal may receive the third data packet from the base station (S490). The terminal may generate an HARQ response corresponding to the third data packet received from the base station (S495). When the UE determines that the third data packet is normal, it may generate an ACK in response to the HARQ. If the UE determines that the third data packet is abnormal, it may generate a NACK in response to HARQ.

The terminal may transmit the HARQ response to the base station (S500). The base station may receive the HARQ response from the terminal (S500). The base station may transmit (pacing) the HARQ response received from the terminal to the core network (S505). That is, the base station may transmit the HARQ response to the core network without performing an operation according to the HARQ response (eg, when a NACK is received, a retransmission operation of a data packet).

The core network may receive the HARQ response from the base station (S505). The core network may receive an HARQ response from a base station through S-GW (for a LTE communication system) or UPF (for an NR communication system). The core network may check whether the third data packet is normal based on the HARQ response (S510). When the ACK is received in the HARQ response, the core network may confirm that the third data packet is normal, and when the NACK is received in the HARQ response, the third data packet may be abnormal.

example The methods according to the invention are implemented in the form of program instructions that can be executed through various computer means and can be recorded on a computer readable medium. Computer-readable media may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention or may be known and usable by those skilled in computer software.

Examples of computer-readable media include hardware devices specially configured to store and execute program instructions, such as roms, rams, flash memories, and the like. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, etc., as well as machine code such as that produced by a compiler. The above-described hardware device may be configured to operate with at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. Will be able to.

Claims (1)

As a method of operation of the first communication node,
Receiving a first data packet from a second communication node;
Estimating a congestion window size of the second communication node based on the size of the first data packet;
Determining whether the data reception rate of the first data packet is stable based on the estimated congestion window size;
If it is determined that the data reception rate is stable, resetting the reception window size;
Transmitting a second data packet including information on the reception window size to the second communication node; And
And receiving a third data packet from the second communication node through the reception window.

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