KR20220072386A - Method for improving performance of multi-path transmission control protocol in wireless communication environment - Google Patents

Abstract

A method for improving the performance of a multi-path transmission control protocol in a wireless communication environment is provided. The method includes measuring a round trip delay time of each of a plurality of communication interfaces, a window size of a transmission/reception side, and a transmission packet amount; selecting any one of the plurality of communication interfaces in the transmitting terminal by learning the round trip delay time, the window size of the transmitting/receiving side, and the amount of transport packets; and transmitting a packet to a receiving terminal based on the selected communication interface.

Description

Method for improving the performance of multi-path transmission control protocol in wireless communication environment

The present invention relates to a method for improving the performance of a multi-path transmission control protocol in a wireless communication environment.

Multipath TCP (MPTCP) is a protocol for controlling data transmission through multiple paths, and it is a protocol that allows data transmitted through an existing TCP session to be transmitted through multiple paths. MPTCP is used as a means of providing stable services in a congested wireless network environment by simultaneously using the user terminal's wireless interface while increasing the mobile data rate or maintaining an invisible auxiliary connection.

However, MPTCP according to the prior art has a problem in that the performance is deteriorated due to packet loss or a difference in transmission speed between interfaces used.

Laid-open Patent Publication No. 10-2015-0123185 (2015.11.03)

The problem to be solved by the present invention is to improve the performance of the multi-path transmission control protocol by scheduling packets to be transmitted through the multi-path by predicting the state of the network used when communicating using the wireless communication interface in the multi-path transmission control protocol. aim to

However, the problems to be solved by the present invention are not limited to the problems described above, and other problems may exist.

A method for improving the performance of a multi-path transmission control protocol in a wireless communication environment according to an aspect of the present invention for solving the above problems is to measure the round-trip delay time of each of a plurality of communication interfaces, the window size of the transmission/reception side, and the amount of transmission packets. step; selecting any one of the plurality of communication interfaces in the transmitting terminal by learning the round trip delay time, the window size of the transmitting/receiving side, and the amount of transport packets; and transmitting a packet to a receiving terminal based on the selected communication interface.

In some embodiments of the present invention, the step of measuring the round-trip delay time of each of the plurality of communication interfaces, the size of the transmission/reception side window, and the amount of transport packets includes the round-trip delay based on the SYN packet and the ACK packet between the transmitting terminal and the receiving terminal. It is possible to measure the time, the window size of the transmitting/receiving side, and the amount of transport packets.

In some embodiments of the present invention, the step of selecting any one of the plurality of communication interfaces by learning the round trip delay time, the transmission/reception side window size and the amount of transport packets comprises: a round trip delay among a plurality of communication interfaces in the transmitting terminal The communication interface with the lowest round-trip latency can be selected.

In some embodiments of the present invention, the step of measuring the round-trip delay time of each of the plurality of communication interfaces, the size of the transmission/reception side window, and the amount of transmission packets comprises: transmitting the packet from the transmitting terminal to the receiving terminal through the plurality of communication interfaces. The round trip delay time may be measured based on the time and the time at which the ACK packet transmitted by the receiving terminal is received.

In some embodiments of the present invention, the step of measuring the round-trip delay time of each of the plurality of communication interfaces, the size of the transmission/reception side window, and the amount of transport packets comprises the transmitting terminal and the receiving terminal during communication based on the multi-path transmission control protocol. The window size of the transmitting and receiving side may be measured based on the window size value and the window size scaling value stored in the header of the TCP packet exchanged with each other.

In some embodiments of the present invention, the step of measuring the round-trip delay time of each of the plurality of communication interfaces, the size of the transmission/reception side window, and the amount of transport packets comprises the transmitting terminal and the receiving terminal during communication based on the multi-path transmission control protocol. The amount of the transport packet may be measured based on a sequence number stored in a header of a TCP packet exchanged with each other.

In some embodiments of the present invention, the step of selecting any one of the plurality of communication interfaces by learning the round-trip delay time, the transmission/reception side window size, and the transmission packet amount includes the round-trip delay time, the transmission/reception side window size and the transmission packet amount. As a result of learning the quantity based on the Q-Learning reinforcement learning algorithm, the communication interface with the largest reward value stored in the Q-table can be selected.

In some embodiments of the present invention, the step of selecting any one of the plurality of communication interfaces by learning the round trip delay time, the transmission/reception side window size and the transmission packet amount includes: the receiving side window size corresponding to the selected communication interface; comparing sizes of packets transmitted through the selected communication interface; and when the size of the receiving-side window is smaller as a result of the comparison, additionally selecting a communication interface having a sequentially large compensation value from among the plurality of communication interfaces.

In some embodiments of the present invention, when the transmitting terminal does not receive an ACK packet for a predetermined time from the receiving terminal or receives a retransmission request ACK, the time and the transmitting side at which the packet is transmitted to the receiving terminal through the plurality of communication interfaces The method may further include updating at least one of the window sizes.

A computer program according to another aspect of the present invention for solving the above problems is combined with a computer that is hardware to execute a method for improving the performance of a multi-path transmission control protocol in the wireless communication environment, and is stored in a computer-readable recording medium do.

Other specific details of the invention are included in the detailed description and drawings.

According to the present invention described above, it is possible to effectively use the network while learning the state of multiple air interfaces in a terminal using MPTCP.

That is, there is an advantage in that traffic can be efficiently transmitted by more accurately determining network conditions by collecting and learning the round trip delay time as well as the window size of the transmitting and receiving side, and the amount of transmission packets, and determining the subflow to deliver the next packet.

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a diagram for explaining a packet processing method in MPTCP.
2 is a diagram for explaining a packet reassembly process.
3 is a diagram illustrating a system for a multi-path transmission control protocol according to an embodiment of the present invention.
4 is a flowchart of a method for improving the performance of a multi-transmission path control protocol according to an embodiment of the present invention.
5 is a diagram for explaining a case in which packet retransmission occurs during communication.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains. It is provided to fully understand the scope of the present invention to those skilled in the art, and the present invention is only defined by the scope of the claims.

The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless otherwise specified in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components. Like reference numerals refer to like elements throughout, and "and/or" includes each and every combination of one or more of the recited elements. Although "first", "second", etc. are used to describe various elements, these elements are not limited by these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first component mentioned below may be the second component within the spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein will have the meaning commonly understood by those of ordinary skill in the art to which this invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless specifically defined explicitly.

The present invention relates to a method for improving the performance of a multi-path transmission control protocol in a wireless communication environment.

1 is a diagram for explaining a packet processing method in MPTCP. 2 is a diagram for explaining a packet reassembly process.

Since a general Transmission Control Protocol (TCP) communicates using only a single-path, there is a limitation in that a communication terminal having multiple interfaces, such as a smart phone, cannot efficiently use network resources. Therefore, in order to solve this limitation, a multi-path transmission control protocol (MPTCP) has been developed.

MPTCP transmits and receives data by simultaneously utilizing all communication interfaces that communication terminals with multiple communication interfaces can utilize, and it is possible to show an improved transmission speed compared to the existing TCP. There are advantages to reducing it. In addition, since it was developed using the TCP option field existing in the TCP header field, it has the advantage of supporting backward compatibility with the existing TCP.

In MPTCP, the TCP traffic that is divided and transmitted through each communication interface is called a subflow. As shown in FIG. 1, packets transmitted by the sender through a plurality of communication interfaces are transferred to the upper layer after the first and second reassembly processes in the buffer for each subflow of the receiver. The reason for the occurrence is as shown in FIG. 2 .

First, the reason that the primary reassembly occurs is because of packet loss that occurs in the existing TCP. That is, if the packet transmitted first is lost, the lost packet is retransmitted later, so the order of the packets is reversed and reassembly in the subflow buffer is required.

In addition, the reason for the secondary reassembly, which does not exist in the existing TCP, occurs because of the difference in the transmission speed of the communication interface used. Since the packet arrives later than the packet sent to the fast subflow, a process of reassembling it is necessary.

For this reason, when the characteristics (bandwidth, delay, transmission speed, etc.) of the communication interfaces possessed by the communication terminal are different from each other, the secondary reassembly process inevitably occurs frequently, which is a major cause of lowering the overall performance of the MPTCP. In addition, in order to obtain a stable and improved transmission speed compared to the existing TCP, the characteristics of the interfaces used should be similar.

In addition, MPTCP is mainly used to solve a bottleneck that occurs because the transmission speed of Wi-Fi and LTE, which are communication interfaces used in wireless communication terminals such as smartphones, is slower than that of wired communication interfaces. Such radio waves have a problem in that it is difficult to expect stable communication performance due to the occurrence of refraction, reflection, scattering, diffraction, interference, etc.

In order to solve such a problem, an embodiment of the present invention provides a round-trip delay time (RTT), a window size on the transmission/reception side, and an actual transmitted packet in a multi-path transmission control protocol environment using a wireless communication interface. The performance of the multi-path transmission control protocol can be improved by learning and predicting the state of the network through the amount of , and scheduling packets to be transmitted through the multi-path.

3 is a diagram illustrating a system for a multi-path transmission control protocol according to an embodiment of the present invention.

In the system according to an embodiment of the present invention, as shown in FIG. 3 , a transmitting terminal and a receiving terminal communicate using a multi-path transmission control protocol through a plurality of communication interfaces. At this time, although Wi-Fi and LTE communication interfaces are exemplified in FIG. 3 as a plurality of communication interfaces, the present invention is not limited thereto. In addition, although only two communication interfaces are illustrated in FIG. 3 , a situation in which more communication interfaces are provided is also applicable.

3 is a situation in which a transmitting terminal (smartphone) having a Wi-Fi and LTE communication interface communicates with a receiving terminal (server) using a multi-path transmission control protocol. At this time, a kernel patch is applied so that the smartphone and the server can use MPTCP. The communication section using the wireless interface is from the smartphone to the Wi-Fi Access Point and from the smartphone to the LTE base station, and from then on, the wired interface is used.

In addition, only two Wi-Fi subflows and two LTE subflows are expressed between the network and the server, but what the two subflows mean is that there are two logical paths used in MPTCP, and there are actually two or two physical interfaces. It doesn't mean to go.

In MPTCP, a scheduling algorithm that selects which communication interface (subflow) to transmit the packet to operates to transmit the packet. In an embodiment of the present invention, the performance can be improved by more accurately learning and predicting the wireless network state in MPTCP by utilizing the round-trip delay time, the size of the window on the transceiver side, and the amount of packets to be transmitted.

4 is a flowchart of a method for improving the performance of a multi-transmission path control protocol according to an embodiment of the present invention. 5 is a diagram for explaining a case in which packet retransmission occurs during communication.

Meanwhile, each step shown in FIG. 4 may be understood to be performed by the transmitting terminal, but is not necessarily limited thereto.

A method for improving the performance of a multi-transmission path control protocol according to an embodiment of the present invention comprises the steps of: measuring a round-trip delay time of each of a plurality of communication interfaces, a window size of a transmission/reception side, and a transmission packet amount; It is performed including the step of selecting one of the plurality of communication interfaces in the transmitting terminal by learning the size and the amount of transmission packets, and transmitting the packet to the receiving terminal based on the selected communication interface.

First, it is checked whether the transmitting terminal and the receiving terminal communicate for the first time (S105), and when the first communication is performed (S105-Y), the transmitting terminal that occurs in the handshake process for establishing a session between TCP and MPTCP Based on the SYN packet and the ACK packet between the terminal and the receiving terminal, the round-trip delay time, the window size of the transmitting/receiving side, and the amount of transmission packets are measured (S110).

However, since the amount of packets generated during the handshake process is very small, it is difficult to derive meaningful results through learning. Accordingly, an embodiment of the present invention compares round-trip delay times of communication interfaces possessed by the transmitting terminal in the initial communication process, selects a communication interface having the smallest round-trip delay time as a result of the comparison, and transmits the packet to the receiving terminal. (S115, S120).

Conversely, in the case of non-first communication (S105-N), it is necessary to measure the round trip delay time of each communication interface used in MPTCP, the window size of the transmission/reception side, and the amount of packets to be transmitted (S125).

In one embodiment, the round trip delay time may be measured based on a time when a packet is transmitted from a transmitting terminal to a receiving terminal through a plurality of communication interfaces and a time at which an ACK packet transmitted by the receiving terminal is received in response thereto.

In this case, the ACK packet means a packet that the receiving terminal transmits back to the transmitting terminal in the sense that it has successfully received the packet when it is received from the transmitting terminal.

A high round-trip delay time measured in this way generally means that the number of packets transmitted to the network is large, but in a wireless network environment, instantaneous refraction, reflection, scattering, diffraction, interference, or Line of Sight (LoS) There is also the possibility that the reason is not secured.

In an embodiment, the window size on the transmission/reception side may be measured based on a window size value and a window size scaling value stored in a header of a TCP packet exchanged between a transmitting terminal and a receiving terminal during communication based on a multi-path transmission protocol.

The transmit/receive side window size refers to the maximum data size that the transmitting terminal and the receiving terminal can see, receive, and process at once. The transmit/receive-side window size may be calculated and stored by using a window size value and a window size scaling value stored in a header of a TCP packet exchanged between a transmitting terminal and a receiving terminal during MPTCP communication.

Finally, the amount of transport packets can be measured based on the sequence number stored in the header of the TCP packet that the sending terminal and the receiving terminal exchange with each other during communication based on the multi-path transmission control protocol.

In addition, according to an embodiment of the present invention, when the transmitting terminal does not receive an ACK packet for a certain period of time from the receiving terminal due to packet loss or network congestion occurring during communication with the receiving terminal or receives an ACK requesting retransmission, the corresponding packet can be retransmitted to update the packet transmission time, which has been stored for calculation of round-trip delay time.

Next, one communication interface is selected from among the plurality of communication interfaces by learning the round-trip delay time, the window size of the transmission/reception side, and the amount of transport packets.

In this step, the network state is learned by applying the Q-Learning reinforcement learning algorithm based on previously collected network environment information.

The Q-Learning reinforcement learning algorithm takes an action in a given state, obtains a reward according to the action taken, and stores it in the Q-table. That is, the Q-Learning reinforcement learning algorithm repeats the above-described series of actions, updates the reward value stored in the Q-table, and performs an action that can obtain the highest reward value in a given environment.

An action in an embodiment of the present invention means selecting one communication interface through which a packet is to be transmitted among various communication interfaces (subflows) possessed by the transmitting terminal, and a round trip in each communication interface collected in the previous step The delay time, the window size of the transmitting/receiving side, and the amount of packets to be transmitted not only mean the current state, but are also compensation values due to the selected action in the previous state.

In a general case, the communication interface having the largest compensation value stored in the Q-table is selected by the Q-Learning algorithm (S130).

However, as a result of comparing the size of the receiving window corresponding to the selected communication interface with the size of packets transmitted through the selected communication interface (S135), when the receiving window size is smaller (S135-Y), among the plurality of communication interfaces A communication interface having a larger compensation value may be additionally selected in the next order ( S140 ).

That is, when the transmitting terminal has a lot of data to be transmitted to the receiving terminal, only the communication interface having the highest compensation value cannot be selected and used. And even if the transmitting terminal selects the communication interface with the highest compensation value and transmits a packet, it cannot transmit a packet larger than the receiving window size until it receives an ACK packet indicating that the corresponding packet has been successfully received from the receiving terminal.

Therefore, according to an embodiment of the present invention, when it is determined that the corresponding communication interface can no longer be used by comparing the size of the receiving-side window of the selected communication interface with the size of the packets transmitted to the communication interface because the compensation value is high, the next compensation value is Choose a higher communication interface.

Meanwhile, according to an embodiment of the present invention, as shown in FIG. 5 , when the transmitting terminal fails to receive an ACK packet from the receiving terminal for a predetermined time or receives an ACK packet requesting retransmission from the receiving terminal, a plurality of communication interfaces are configured. It is possible to update the time at which the packet is transmitted to the receiving terminal and the window size of the sender.

According to this embodiment of the present invention, when a terminal having multiple air interfaces, such as a smart phone, uses the multi-path transmission control protocol (MPTCP), it is possible to effectively use the network while learning the state of the multi-air interface.

There are three major scheduling methods used in the existing MPTCP: 1) selecting a subflow with the lowest round-trip latency, 2) using all subflows equally once, 3) copying and sending the same packet to all subflows In most cases, the first method, the method of selecting the subflow with the lowest round-trip latency, is used.

However, since a wireless terminal using a wireless interface is used while moving rather than being used in a fixed place, the signal strength changes depending on the communication location that changes every moment, and the round-trip delay time also changes accordingly. is not suitable for This is because it is difficult to determine whether the signal strength is changed because the network is congested or the communication location is changed because the reason that the round trip delay time increases and decreases, which is the most important factor in determining the subflow to transmit the next packet, is changed.

On the other hand, according to an embodiment of the present invention, when determining a subflow to deliver the next packet by collecting and learning not only the round trip delay time, but also the sending-side window size, the receiving-side window size, and the amount of transmitted packets, the conventional method It is possible to efficiently transmit traffic by judging the network condition more accurately than compared to the previous model.

The method for improving the performance of a multi-path transmission control protocol in a wireless communication environment according to an embodiment of the present invention described above may be implemented as a program (or application) and stored in a medium to be executed in combination with a computer, which is hardware. have.

The above-mentioned program, in order for the computer to read the program and execute the methods implemented as a program, C, C++, JAVA, Ruby, which the processor (CPU) of the computer can read through the device interface of the computer; It may include code coded in a computer language such as machine language. Such code may include functional code related to a function defining functions necessary for executing the methods, etc., and includes an execution procedure related control code necessary for the processor of the computer to execute the functions according to a predetermined procedure. can do. In addition, the code may further include additional information necessary for the processor of the computer to execute the functions or code related to memory reference for which location (address address) in the internal or external memory of the computer to be referenced. have. In addition, when the processor of the computer needs to communicate with any other computer or server located remotely in order to execute the above functions, the code uses the communication module of the computer to determine how to communicate with any other computer or server remotely. It may further include a communication-related code for whether to communicate and what information or media to transmit and receive during communication.

The storage medium is not a medium that stores data for a short moment, such as a register, a cache, a memory, etc., but a medium that stores data semi-permanently and can be read by a device. Specifically, examples of the storage medium include, but are not limited to, ROM, RAM, CD-ROM, magnetic tape, floppy disk, and an optical data storage device. That is, the program may be stored in various recording media on various servers accessible by the computer or in various recording media on the computer of the user. In addition, the medium may be distributed in a computer system connected to a network, and a computer-readable code may be stored in a distributed manner.

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims (1)

A method for improving the performance of a multi-path transmission control protocol in a wireless communication environment, the method comprising:
measuring a round trip delay time of each of a plurality of communication interfaces, a window size of a transmission/reception side, and an amount of transmission packets;
selecting any one of the plurality of communication interfaces in the transmitting terminal by learning the round trip delay time, the window size of the transmitting/receiving side, and the amount of transport packets; and
transmitting a packet to a receiving terminal based on the selected communication interface;
A method for improving the performance of a multi-path transmission control protocol in a wireless communication environment.

Images