KR101470575B1 - Network connecting device and method for controlling packet transmission and reception - Google Patents

Abstract

The present invention relates to a method for solving the TCP transmission degradation problem due to a wireless network characteristic by a local retransmission in a network interworking device, and a method for solving the caching memory problem of the TCP snoop, Technology. The present invention measures RSSI, forwards a packet transmitted from a fixed host to a wireless terminal for forwarding a packet loss occurring in a wireless network, or forwards a packet transmitted from a wireless terminal to a fixed host, If the RSSI is decreased by a certain amount or more than the previous RSSI, the packet is copied to the buffer and forwarded to the wireless terminal or the fixed host.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a network linking apparatus and method for controlling packet transmission /

The present invention relates to a network interworking apparatus and method for controlling packet transmission and reception, and more particularly, to a network interworking apparatus and a network interworking apparatus for controlling transmission and reception of a packet based on RSSI (Received Signal Strength Indication) ≪ / RTI >

The purpose of TCP congestion control is to detect the occurrence of congestion in the network during data transmission and to control the amount of TCP data transmission. However, in a wireless environment, data may be lost even in a non-congested network. In such a situation, TCP congestion control technology should be operated to prevent deterioration of transmission performance.

There are various technologies to solve the TCP transmission performance of the wireless network, and there are four major fields. (2) the end-to-end TCP congestion control algorithm that reflects wireless characteristics, (3) the method through local loss recovery, (4) the cause of packet loss, To the packet transmission side.

First, the method of separating the wired and the wireless is to establish the TCP connection of the wired network and the TCP connection of the wireless network in the access point (AP), respectively, so that the loss of the wireless network is not transferred to the wired network.

Next, a typical example of an end-to-end TCP congestion control algorithm that reflects wireless characteristics is TCP Westwood. This technique measures the bandwidth of the wireless network and uses it as a threshold for the TCP congestion control algorithm. In this way, the TCP transmission rate can be adjusted based on the wireless bandwidth, and the loss rate is reduced in the wireless network by applying the TCP transmission rate based on the wireless network bandwidth.

Next, a typical example of a method through local loss recovery is TCP Snoop. This scheme caches all TCP packets transmitted from the APs, and notifies the APs of lost packets in the wireless network, instead of transmitting redundant ACKs to the packet senders. In this case, the TCP congestion control algorithm operates Do not.

In this connection, Korean Patent Publication No. 10-2004-0067343 (entitled: Network Interworking Device for Controlling TCP Transmission Between a Wired Network and a Wireless Network) describes a TCP snoop technique.

Finally, the method of informing the sender of the cause of the packet loss is to prevent the congestion control operation in case of packet loss in the wireless network by informing the packet transmission side whether the packet loss section is wired or wireless. Method. This is a method for retransmitting a lost packet without decreasing the congestion window at the time of radio section loss.

There are the following reasons that techniques for improving the transmission performance of the wireless network TCP are difficult to be practically applied. First, the technique of separating the wired and the wireless has to establish the TCP connection between the wireless network and the wired section for all the TCP connections at the AP, but it is difficult to perform all connection processing at the AP. In addition, end-to-end algorithms require modification of TCP modules of all terminals, and it is difficult to modify TCP of all terminals already listed. Also, there is a memory problem that requires a caching and management of all data at the AP. The method of informing the packet transmission side of the cause of the packet loss has a problem that the TCP of all the terminals must be corrected as in the end-to-end method.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a network interworking apparatus and method for controlling packet transmission and reception by adjusting the amount of packets copied to a buffer according to RSSI measured and transmitting the packets to a packet receiving side .

According to an aspect of the present invention, there is provided a mobile communication system comprising: a wired network interworking unit connected to a fixed network to exchange data packets with a fixed host; A wireless mesh network coupled to the wireless network for exchanging data packets with the wireless network; A measuring unit measuring RSSI of the wireless terminal; And a controller for forwarding a packet transmitted from the fixed host to the wireless terminal for retransmission of a packet loss occurring in the wireless network or forwarding a packet transmitted from the wireless terminal to the fixed host, The control unit copies the packet to the buffer and forwards the packet to the wireless terminal or the fixed host when the RSSI measured by the measurement unit has decreased by a predetermined amount or more than the previous RSSI.

According to another aspect of the present invention, there is provided a method for receiving a packet, the method comprising: receiving a packet from a fixed host or a wireless terminal; And forwarding the packet to the fixed host when the packet is received from the fixed host, or when the packet is received from the wireless terminal, forwarding the packet to the fixed host, Measuring RSSI; Copying the packet to a buffer if the measured RSSI has decreased by a predetermined amount or more than the previous RSSI; And forwarding to the wireless terminal or the fixed host.

According to the present invention, the transmission performance of a wireless network TCP can be improved by applying the present invention to a network interworking apparatus without modification of all terminals.

According to a preferred embodiment of the present invention, a TCP congestion control algorithm operation is prevented at a TCP packet transmission side due to a wireless network loss, and a TCP transmission rate is controlled based on an RSSI. Therefore, can do. Therefore, TCP transmission performance can be optimized.

FIG. 1 illustrates a structure in which a network interworking device according to an embodiment of the present invention is connected to a fixed host and a wireless terminal.
FIG. 2 illustrates a network interworking apparatus according to an embodiment of the present invention.
FIG. 3 is a graph showing an example of the relationship between RSSI and data throughput.
4 shows a flowchart of a method for controlling data transmission / reception of a network interworking device according to an embodiment of the present invention.
FIG. 5 shows a flowchart of a method for controlling a data packet transmission / reception by a network interworking device according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between .

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The word " step (or step) "or" step "used to the extent that it is used throughout the specification does not mean" step for.

Throughout this specification, when a component is referred to as " caching ", it is meant to temporarily store instructions and data in a cache memory or disk cache, and a central processing unit (CPU) Means a way to improve the performance of a computer by reducing it to several times faster or closer to the CPU's speed than reading from disk or writing data to main memory or disk. According to one embodiment of the present disclosure, the cache memory may be described as a buffer.

The conventional TCP Snoop technique caches all TCP packets received by the AP and notifies the packet transmission side of the lost packet in the wireless network, TCP congestion control algorithm is not operated.

This method of recovering the local loss has an excessive caching problem that requires that all packets transmitted for all TCP sessions of all wireless terminals connected to the AP be stored. The present invention relates to a method for solving such problems of the prior art.

In the present invention, the conventional TCP snoop technique is modified to facilitate practical application. The TCP snoop caches all the transmitted TCP data. In the present invention, a memory problem is solved in the snoop technique, which is a loss recovery method, and a TCP transmission rate is calculated based on RSSI (received signal strength, RECEIVED SINNAL STRING INDICATION) Thereby improving the transmission performance of the wireless network TCP.

FIG. 1 illustrates a structure in which a network interworking device according to an embodiment of the present invention is connected to a fixed host and a wireless terminal.

2 is a block diagram of a network interworking apparatus according to an embodiment of the present invention.

The network interworking device 3 is a device that connects the fixed network used by the fixed host 1 and the wireless network used by the wireless terminal 2 to exchange data packets between the fixed host 1 and the wireless terminal 2. For example, a base station (BS) or an access point (AP).

A host is a computer connected to an Internet network and capable of communicating with another Internet host. A host is both the source and destination of a packet. A host is both a client and a server. In an Internet network, a host is identified by an Internet name and an Internet address.

The term "fixed host (1) " as referred to throughout the present specification refers to a host that transmits a data packet to a wired network, for example, a server. The fixed host 1 can transmit or receive a packet to another host, and thus can be a packet transmitting side or a packet receiving side.

The term "wireless terminal 2 " referred to throughout the present specification refers to a host that transmits data packets to a wireless network and may be, for example, a mobile terminal, a mobile phone, a smart phone, a tablet pc, It may also be referred to as a mobile host. As in the fixed host 1, since the packet can be transmitted or received to another host, it can be a packet transmitting side and can be a packet receiving side.

In the present specification, however, the fixed host 1 and the wireless terminal 2 transmit and receive data packets using the network interworking device 3, so that when the fixed host 1 becomes a packet transmitting side, And the fixed host 1 becomes the packet receiving side, the wireless terminal 2 becomes the packet transmitting side.

The network interworking apparatus 3 according to an embodiment of the present invention includes a wired network interworking unit 10, a wireless mesh network 11, a measurement unit 12, and a control unit 13.

Hereinafter, the function of each component and its operation process will be described in detail.

The wired network interworking unit 10 is connected to a wired network for exchanging data packets with the fixed host 1.

The wireless network connection unit 11 is connected to a wireless network for exchanging data packets with the wireless terminal 2. [

The measurement unit 12 measures the RSSI (Reciever Signal Strength Indicator), which is the strength of the radio signal received from the wireless terminal. The RSSI has a maximum value of 30 and a minimum value of -10. If it is close to the communication equipment, the maximum value may be 30, but it can be adjusted to 0 automatically due to the power control function in the communication equipment.

The controller 13 controls the fixed host 1 or the wireless terminal 2 to transmit a packet transmitted from the packet transmitting side to the wireless terminal 2 or the fixed host (1), i.e., to the packet receiving side.

The fixed host 1 or the wireless terminal 2 for transmitting a packet is referred to as a packet transmitting side and the wireless terminal 2 or the fixed host 1 for receiving a packet is referred to as a packet receiving side. For example, when the fixed host 1 is a packet transmission side and the wireless terminal 2 is a packet reception side, the network interworking apparatus 3 receives a packet from the packet transmission side via the wired network interworking unit 10, And transmits the packet to the packet receiving side through the network connecting section 11. [ The network interworking device 3 may also receive a normal reception message (e.g., an ACK message) indicating that the packet has been normally received from the wireless network interframe 11.

Hereinafter, it will be assumed that the packet transmitting side is the fixed host 1 and the packet receiving side is the wireless terminal 2. [ In addition, the packet transmission side may be the wireless terminal 2 and the packet transmission side may be the fixed host 1.

First, when the RSSI of the wireless terminal measured by the measuring unit 12 is decreased by a certain amount or more than the previous RSSI, the control unit 13 copies the packet transmitted from the packet transmitting side 1 to the buffer. The process of copying may be referred to as caching. This is a prerequisite for retransmission of packet loss in the wireless network. Then, the control unit 13 forwards the transmitted packet to the packet receiving side 2.

In this case, according to an embodiment of the present invention, the predetermined amount may be a difference between the RSSI in the steady state measured by the measuring unit 12 and the RSSI when the loss of the wireless network occurs. It may also be determined by the control unit 13.

The reason for measuring the RSSI in this manner is that the RSSI is related to the throughput of the network. Table 1 shows the results of experiments on the relationship between RSSI and data throughput. The experimental environment is as follows. The user wants to download the file from the FTP server, and the wireless network is used to connect the user to the AP and the wired network to connect the FTP server and the AP. WireShark software was used to measure the data throughput of the network (with different RSSI) according to the user's location.

Figure 3 shows Table 1 in the form of a graph.

According to FIG. 3, as the RSSI value increases, the data throughput also increases proportionally. Therefore, the present invention aims to improve TCP performance of a wireless network based on the relationship between RSSI and data throughput.

 Meanwhile, the controller 13 according to an embodiment of the present invention may determine whether the received packet is a new packet not in the buffer before determining whether the RSSI has decreased by a predetermined amount or more than the previous RSSI, , The packet is forwarded to the packet receiving side 2 without having to copy it to the buffer because it is a retransmitted packet. However, if the received packet is a new packet, it is not a retransmitted packet, so it copies the packet to the buffer and forwards it to the packet receiving side 2. According to an embodiment of the present invention, a sequence number of a packet can be checked to determine whether the packet is a new packet.

In addition, the control unit 13 according to another embodiment of the present invention can determine whether the received packet is in a proper order before determining whether the RSSI has decreased by a predetermined amount or more than the previous RSSI. There is a way to check the sequence number. When receiving a packet whose order has changed, the control unit 13 marks the packet, thereby preventing unnecessary retransmission due to the packet. For example, the conventional TCP congestion control technique retransmits a packet after waiting for ACK three times. According to the present invention, even if two ACKs occur, the packet transmission side 1 performs ACK by marking the corresponding packet You do not have to wait three times.

In addition, the process of determining whether the received packets match the order can be performed after the process of determining whether the received packet is a new packet not in the buffer.

4 shows a flowchart of a method for controlling data transmission / reception of a network interworking device according to an embodiment of the present invention.

First, the network interworking device receives a packet from the packet transmission side (S1110).

In step S1160, the network interrogator measures the RSSI of the wireless network. If the measured RSSI has decreased by a predetermined amount or more than the previous RSSI (S1160), the network interworking apparatus copies the received packet to the buffer and forwards the packet. That is, the current data throughput change of the wireless network is measured to decide whether or not to cache it. At this time, a certain amount can be determined experimentally. The difference between the RSSI at the time of normal packet transmission and the RSSI at the time when the packet is not normally received due to loss of the wireless network is an embodiment. However, if the measured RSSI is not decreased by more than a predetermined amount of the RSSI (S1170), since the quality of the radio network is not deteriorated, the packet is normally forwarded.

However, if the RSSI is reduced below the minimum threshold, the wireless terminal is no longer in the area where the network interworking device provides the service, so that the network interworking device only copies the received packet to the buffer and forwards the packet to the wireless terminal I never do that.

Meanwhile, FIG. 5 shows a flowchart of a method of controlling data transmission / reception by a network interworking device according to an embodiment of the present invention.

According to another embodiment of the present invention, the network interworking device may determine whether the received packet is a new packet not in the buffer before measuring RSSI (S1120).

If the received packet is a new packet not in the buffer, the RSSI is measured as described above. If the measured RSSI has decreased by a predetermined amount or more than the previous RSSI (S1160), the packet is copied to the buffer and forwarded (S1180). However, if the measured RSSI is not decreased by more than a predetermined amount of the RSSI (S1170), since the quality of the radio network is not deteriorated, the packet is normally forwarded. However, if the received packet has already been copied to the buffer, the received packet is forwarded to the packet receiving side without having to copy it back to the buffer because it is a retransmitted packet (S1130). According to an embodiment of the present invention, a sequence number of a packet can be checked to determine whether the packet is a new packet not copied to a buffer

In addition, according to another embodiment of the present invention, the network interworking apparatus determines whether the received packet is an ordered packet before measuring RSSI (S1140). However, the process of determining whether the packet is in the above-described order may be included after the process of determining whether the received packet is a new packet not in the buffer (S1120).

On the other hand, when the packet receiving side receives a packet satisfying the sequence (there is also a method of confirming the sequence number), the RSSI is measured as described above, and if the measured RSSI is more than a predetermined amount If it is decreased (S1160), the packet is copied to the buffer and forwarded (S1180). However, if the measured RSSI is not decreased by more than a predetermined amount of the RSSI (S1170), since the quality of the radio network is not deteriorated, the packet is normally forwarded. However, if the packet does not match the order, the packet is marked and forwarded to the packet receiving side (S1150). So that the network interworking device does not retransmit the packet even after receiving the duplicate ACK message due to the packet.

Meanwhile, according to an embodiment of the present invention, when the network interworking device receives a normal reception message (for example, an ACK message) that the packet reception side wants to transmit to the packet transmission side, the network interworking device first measures the RSSI of the wireless terminal do. This is for the purpose of determining if the wireless terminal is in the range where the network interworking device provides the service. If the RSSI is below the minimum threshold, the process does not proceed because it is no longer the service area of the network interworking device. However, if the RSSI indicates a value greater than the minimum limit, the network interworking device determines whether the message is a new message. Then, in case of a new normal received message, the buffer in which the packet is copied is emptied and the normal received message is forwarded to the packet transmitting side. However, if it is not a new normal reception message, it means that the packet reception side has not normally received the packet, so the following process is performed.

If the packet receiver does not normally receive the packet (for example, when the packet receiver side transmits a DupACK message), the network interworking device compensates the packet loss by retransmitting the copied packet to the packet receiver.

As described above, since the RSSI is measured and the transmission rate of a packet (for example, a TCP packet) is controlled, the caching memory of a predetermined amount or more can be prevented from accumulating in a normal case. If the situation of the wireless network is bad, RSSI will be bad, and by selectively caching packets in such a situation, unnecessary waste of memory can be reduced.

Also, the apparatus and method for controlling the transmission rate of the TCP network can improve transmission performance of the wireless network TCP by applying the present invention only to a network interworking device (e.g., an AP) without modification of all terminals. In addition, the operation of the TCP congestion control algorithm at the packet transmission side due to the wireless network loss is prevented, and the packet transmission performance is controlled based on the RSSI, thereby optimizing the packet transmission performance.

For reference, the components according to embodiments of the present invention refer to hardware components such as software, a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC), and perform predetermined roles.

However, 'components' are not meant to be limited to software or hardware, and each component may be configured to reside on an addressable storage medium and configured to play one or more processors.

Thus, by way of example, an element may comprise components such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, Routines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables.

The components and functions provided within those components may be combined into a smaller number of components or further separated into additional components.

Meanwhile, each component of the present invention can be composed of a kind of 'module'. A "module" refers to a hardware component such as software or a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), and the module performs certain roles. However, a module is not limited to software or hardware. A module may be configured to reside on an addressable storage medium and may be configured to execute one or more processors. The functionality provided by the components and modules may be combined into a smaller number of components and modules or further separated into additional components and modules.

One embodiment of the present invention may also be embodied in the form of a recording medium including instructions executable by a computer, such as program modules, being executed by a computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, the computer-readable medium may include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically includes any information delivery media, including computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transport mechanism.

The network interworking apparatus and the transmission / reception control method according to the present invention can be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording media storing data that can be decoded by a computer system. For example, it may be a ROM (Read Only Memory), a RAM (Random Access Memory), a magnetic tape, a magnetic disk, a flash memory, an optical data storage device, or the like. In addition, the computer-readable recording medium may be distributed and executed in a computer system connected to a computer network, and may be stored and executed as a code readable in a distributed manner.

While the invention has been described in conjunction with specific embodiments thereof, some or all of those elements or operations may be implemented using a computer system having a general purpose hardware architecture

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

1: fixed host
2: wireless terminal
3: Network interlocking device

Claims (8)

A network interworking apparatus for controlling transmission and reception of packets, comprising:
A wired network interworking unit connected to a wired network for exchanging data packets with a fixed host;
A wireless mesh network coupled to the wireless network for exchanging data packets with the wireless network;
A measurement unit measuring a received signal strength indication (RSSI) of the mobile station; And
And a controller for forwarding a packet transmitted from the fixed host to the wireless terminal or forwarding a packet transmitted from the wireless terminal to the fixed host for retransmission of a packet loss occurring in the wireless network,
Wherein,
If the measured RSSI is less than a predetermined amount less than a previous RSSI, the measuring unit forwards the packet without copying the packet to the buffer,
And if the RSSI measured by the measurement unit is smaller than a previous RSSI by a predetermined amount or more, the packet is copied to the buffer and then forwarded,
Wherein the measuring unit does not forward the packet after copying the packet to the buffer if the measured RSSI is less than a minimum threshold value.
The method according to claim 1,
Wherein,
And copying the packet to the buffer and forwarding the packet to the wireless terminal or the fixed host when the packet is a new packet not in the buffer and the RSSI has decreased by a certain amount or more than the previous RSSI. The method according to claim 1,
Wherein the packet is a new packet not included in the buffer and is a packet satisfying the order and the RSSI is decreased by a predetermined amount or more than the previous RSSI, the packet is copied to the buffer and forwarded to the wireless terminal or the fixed host, .
The method according to claim 1,
Wherein,
Wherein the measurement unit measures the RSSI of the steady state measured by the measurement unit and the RSSI difference when the loss of the wireless network occurs to determine the predetermined amount.
A method of controlling transmission and reception of packets,
Receiving a packet from a fixed host or a wireless terminal;
Measuring an RSSI of the wireless terminal;
Comparing the measured RSSI with a previous RSSI and a minimum threshold, respectively;
The method comprising: forwarding a packet received from the fixed host to the wireless terminal or copying a packet received from the wireless terminal to the fixed host without copying the packet to the buffer when the measured RSSI is less than a predetermined amount less than the previous RSSI; Forwarding;
If the measured RSSI is smaller than the previous RSSI by a predetermined amount or more, copying the packet to the buffer, then forwarding the packet received from the fixed host to the wireless terminal, or forwarding the packet received from the wireless terminal to the fixed host ; And
And not forwarding the packet after copying the packet to the buffer if the measured RSSI has decreased below the minimum threshold value.
6. The method of claim 5,
Before the measuring step,
Further comprising determining whether the packet is a new packet not in the buffer,
Wherein the measuring step and the copying step comprise:
If the packet is a new packet not in the buffer
Wherein the RSSI is measured and the measured RSSI is decreased by a predetermined amount or more than the previous RSSI, the packet is copied to the buffer.
6. The method of claim 5,
Before the measuring step,
Further comprising the step of determining whether the packet is an ordered packet,
Wherein the measuring step and the copying step comprise:
If the packet meets the order,
Wherein the RSSI is measured and the measured RSSI is decreased by a predetermined amount or more than the previous RSSI, the packet is copied to the buffer.
6. The method of claim 5,
In the copying step,
Wherein the predetermined amount is a difference between an RSSI in a steady state measured in the measuring step and an RSSI when loss of a wireless network occurs.

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