KR100942814B1 - Method for wireless lan communication supporting movability - Google Patents

Method for wireless lan communication supporting movability Download PDF

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Publication number
KR100942814B1
KR100942814B1 KR1020090009013A KR20090009013A KR100942814B1 KR 100942814 B1 KR100942814 B1 KR 100942814B1 KR 1020090009013 A KR1020090009013 A KR 1020090009013A KR 20090009013 A KR20090009013 A KR 20090009013A KR 100942814 B1 KR100942814 B1 KR 100942814B1
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South Korea
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data
wireless lan
wlan
rate
communication method
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KR1020090009013A
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Korean (ko)
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류창형
우희성
정현철
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코아글림 주식회사
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
    • H04L1/001—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding applied to control information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/025—Services making use of location information using location based information parameters
    • H04W4/027—Services making use of location information using location based information parameters using movement velocity, acceleration information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/02—Access restriction performed under specific conditions
    • H04W48/04—Access restriction performed under specific conditions based on user or terminal location or mobility data, e.g. moving direction, speed
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]

Abstract

Wireless LAN communication method of a mobile device according to an embodiment of the present invention includes the steps of calculating the maximum Doppler Frequency (Maximum Doppler Frequency) of the mobile; Calculating a time for which a channel characteristic function is valid through the maximum Doppler frequency; Determining a data rate; And determining the size of the transmitted data through the time when the channel characteristic function is valid and the data rate.

Description

Wireless LAN communication method supporting mobility {METHOD FOR WIRELESS LAN COMMUNICATION SUPPORTING MOVABILITY}

The present invention relates to a wireless LAN communication method supporting mobility, and more particularly, to calculate a valid time of a channel characteristic function through a maximum Doppler frequency reflecting a moving speed of a moving object, and to determine a data transmission rate. The present invention relates to a WLAN communication method that supports mobility for enabling wireless LAN communication to be performed at a good transmission rate through a process of calculating a size of transmission data using a valid time and the data transmission rate.

Wireless Local Area Network (WLAN) technology may be referred to as a wireless form of Ethernet, commonly referred to as a LAN. If a technology that enables high-speed Internet access using a LAN line in an office, home, or public place is Ethernet, the wireless LAN technology may be a technology that supports high-speed Internet access without a line.

Ethernet and WLAN technologies can perform multi-user access control in a relatively simple manner unlike mobile communication technologies such as cellular and WiBro. Multi-user access control is a matter of deciding who will use medium when using common medium. Ethernet and WLAN use the decentralized way that each device performs, while mobile communication technology Use a centralized way where the base station determines everything.

In a distributed fashion, multi-user access control techniques can be implemented relatively simply. Carrier Sensing Multiple Access (CSMA) technology senses the presence of a user by checking the presence of a carrier, delays access if a user already exists, and backs off if there is no user. Can be implemented. WLANs can also implement multi-user access control through this technology.

Unlike the centralized method, the distributed method cannot manage the system because a specific node is the center, so the system must be maintained through a relatively simple method and simple rules. The method taken by the distributed approach can also be simply implemented in a method for achieving the maximum data rate in wireless transmission. If the transmission is successful several times, it is determined that the channel state is good, the transmission speed is higher. On the contrary, if the transmission is not successive several times, it is determined that the channel state is bad and the transmission speed is lowered.

As such, the WLAN technology is commercially available for homes and offices because it can achieve high transmission speed at a very low price due to the advantage of maintaining the system through a relatively simple method and simple rules, compared to the cellular technology, which is a mobile communication technology. Although it is used, there is a disadvantage in that it does not support mobility compared to a mobile communication technology. Accordingly, there is a demand for the development of a technology capable of transmitting data without loss of data while maintaining the characteristics of achieving high transmission speed at a low cost.

The present invention has been made to improve the prior art vulnerable to the mobility support of the wireless LAN as described above, calculates the effective time of the channel characteristic function through the maximum Doppler frequency reflecting the moving speed of the moving object, and determines the data transmission speed After that, the channel characteristic function provides a WLAN communication method that supports mobility so that wireless LAN communication can be performed at a good transmission rate through a process of calculating a size of transmission data based on a valid time and the data transmission rate. It aims to do it.

In order to achieve the above object and to solve the problems of the prior art, a wireless LAN communication method of a mobile device according to an embodiment of the present invention comprises the steps of calculating the maximum Doppler Frequency (Maximum Doppler Frequency) of the mobile device; Calculating a time for which a channel characteristic function is valid through the maximum Doppler frequency; Determining a data rate; And determining the size of the transmitted data through the time when the channel characteristic function is valid and the data rate.

In addition, in the WLAN communication method of a mobile device according to an embodiment of the present invention, the effective time of the channel characteristic function is calculated as a value obtained by dividing a first constant by the maximum Doppler frequency, and the first constant is 0.423. It features.

In addition, in the wireless LAN communication method of a mobile device according to an embodiment of the present invention, the data transmission rate is any one of a signal-to-noise ratio (SNR) measurement method and an auto rate fallback method. Characterized in the above manner.

Further, in the WLAN communication method of a mobile device according to an embodiment of the present invention, the step of determining the size of the transmission data through the time when the channel characteristic function is valid and the data transmission rate, the time when the channel characteristic function is valid And calculating the product between the data transmission rates.

In addition, in the wireless LAN communication method of a mobile device according to an embodiment of the present invention, the wireless LAN is characterized in that any one of IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11n, and IEEE802.11p. do.

In addition, in a wireless LAN communication method of a mobile device according to an embodiment of the present invention, the data transmission rate is a coding rate, and the transmission data size is a packet size and a frame size. It characterized by including any one or more of.

In addition, in the wireless LAN communication method of a mobile device according to an embodiment of the present invention, the wireless LAN communication method is characterized in that performed in the MAC (MAC) layer.

According to the WLAN communication method supporting mobility of the present invention, by allowing the Internet access through a wireless LAN instead of a mobile communication method such as cellular or WiBro while moving, ensuring maximum transmission speed and stability at a minimum cost The effect of realizing the internet connection environment on the go is obtained.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a diagram illustrating a concept of a mobility support method of WLAN communication performed in a MAC layer according to an embodiment of the present invention.

Wireless LAN communication according to an embodiment of the present invention can be implemented through a wireless LAN module mounted on the mobile. The WLAN module may perform data transmission / reception with a WLAN module of a fixed station, or may perform data transmission / reception with a WLAN module mounted on another mobile.

First, data to be transmitted in a WLAN may be implemented as an IP packet having a variable size. When the data (IP packet) is transmitted to the WLAN, the data is transmitted to the medium through the multi-user access control. In this case, the following techniques may be used to maximize data transmission.

The Shannon Capacity method, which is widely used in the wireless communication field, may be used. Shannon capacity mode may be implemented as C = B log 2 (1 + S / N). In this case, the data transmission rate may be determined by measuring a signal noise ratio (SNR) in the above equation. In other words, knowing the signal-to-noise ratio, we can determine the maximum transmission rate that can be transmitted over bandwidth B at that moment.

Subsequently, when the receiver receives the data transmitted at the determined maximum transmission rate, the signal is generally attenuated or distorted according to the characteristics of the wireless channel, so that normal data recovery is difficult. In order to overcome this, a pilot signal or a preamble signal, which is a known signal, may be transmitted to determine the characteristics of the channel as a function, and then may be restored by applying it.

In the WLAN technology, the size of a frame transmitted through the physical layer during data transmission may be determined by the size of data determined at the network layer and the transmission rate determined at the data link layer. The transmission rate may be determined by dividing the data size by the transmission time.

If the WLAN module is installed in a fixed station and remains stationary without moving, the channel characteristic function measured using the preamble is valid for the time of transmitting the frame, so that no particular problem occurs. Therefore, it is not necessary to determine the transmission rate through the same value as the signal-to-noise ratio.In case of successful transmission, the success rate is increased by successively using ACK (Acknowledgement) signal. Auto rate fallback (ARF) may be used, which is a method of reducing the rate.

When the WLAN module is mounted on a moving object to maintain a moving state, the channel characteristic function may be measured by a maximum Doppler frequency reflecting the moving speed of the moving object, and the channel characteristic function may be measured by a first time (T). c ) is valid for. The first time T c may be implemented as in Equation 1.

Figure 112009007019572-pat00001

In Equation 1, f d means the maximum Doppler frequency of the moving body.

Therefore, when the first time T c elapses, since the channel characteristic function is no longer valid, it is attenuated or distorted, making it difficult to recover the received signal and thus cannot receive a normal signal. Therefore, since the receiving side does not transmit the acknowledgment (ACK) signal, the transmitting side determines that an error occurs in the transmission rate in the currently used WLAN communication method when the acknowledgment (ACK) signal is not transmitted from the receiving side several times. The transmission speed is lowered to retransmit. The result of this determination is only valid in the stationary state, but in the mobile state, the transmission time is further increased than the first time T c , causing a vicious cycle in which transmission is not completed again.

The problem of WLAN communication occurring during the movement can be solved according to the WLAN communication method supporting mobility according to the present invention.

As shown in FIG. 1, the WLAN communication method according to the present invention may be implemented through a MAC layer. In a typical mobile communication system, a hierarchical structure includes a physical layer (PHY Layer) for determining time at a maximum moving speed, a data layer for determining a rate by measuring a signal to interference plus noise ratio (SINR), and a variable size ( Network layer for a packet having a Variable Length).

The WLAN communication method supporting mobility according to an embodiment of the present invention may be implemented through a WLAN module mounted on a mobile body. As illustrated in FIG. 1, the WLAN module calculates a coherence time, which is a time when a channel characteristic function is valid, through a maximum Doppler frequency of the mobile body. The WLAN module may calculate the maximum Doppler frequency by measuring a moving speed of the moving object. The WLAN module may include a speed measuring module as a configuration for measuring the moving speed, and may control the moving speed of the moving object through a separate speed measuring module provided in the moving object.

Thereafter, the WLAN module determines a coding rate that is a data transmission rate through any one or more of a signal-to-noise ratio (SNR) measurement method and an auto rate fallback method. .
As described above, the WLAN module may determine a data transmission rate through a signal capacity ratio (SNR) measurement method of Shannon capacity, which is widely used in the wireless communication field. That is, the data transmission rate may be determined by measuring a signal noise ratio (SNR) at C = B log 2 (1 + S / N), which is a formula of Shannon capacitance method.
In addition, as described above, the WLAN module does not need to determine the transmission rate through a value such as a signal-to-noise ratio. It can also be determined through Auto Rate Fallback (ARF), which is a method of increasing the transmission rate and decreasing the transmission rate if the transmission fails continuously.

The WLAN module may determine a frame size, which is a data transmission size, based on the measured coherence time and the determined coding rate. That is, since "transmission rate = data size / transmission time", the frame size may be determined through a product of the coding rate and the coherence time.

2 is a flowchart illustrating a flow of a WLAN communication method according to an embodiment of the present invention.

The WLAN communication method according to an embodiment of the present invention may be implemented through a WLAN module mounted on a moving object. The WLAN module may perform WLAN communication of any one or more of IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11n, and IEEE802.11p. The WLAN module may be implemented to perform not only the communication scheme but also all WLAN communication based on IEEE802.11 with a WLAN module installed in a fixed station or another WLAN module mounted in a mobile station.

The WLAN module calculates a maximum Doppler frequency of the mobile unit (step 211). In step 211, the WLAN module may calculate the maximum Doppler frequency of the mobile unit by measuring the moving speed of the mobile unit.

The WLAN module calculates a time when a channel characteristic function is valid through the maximum Doppler frequency (step 212). In step 212, the WLAN module may calculate a time for which the channel characteristic function is valid through Equation 1 described above. That is, the WLAN module may calculate a time for which the channel characteristic function is valid by dividing a first constant which may be implemented by 0.423 by the maximum Doppler frequency.

The WLAN module determines the data transmission rate (step 213). In operation 213, the data transmission rate may be determined by one or more of a signal-to-noise ratio (SNR) measurement method and an auto rate fallback method. The data rate may be implemented at a coding rate.

The WLAN module determines the size of the transmission data through the time when the channel characteristic function is valid and the data transmission rate (step 214). In step 214, the WLAN module may determine the size of the transmission data through a product of the time when the channel characteristic function is valid and the data transmission rate. The transmission data size may be implemented to include any one or more of a packet size and a frame size.

The WLAN communication method according to the present invention may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. The medium may be a transmission medium such as an optical or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, or the like. Examples of program instructions include machine code, such as produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above-described embodiments, which can be variously modified and modified by those skilled in the art to which the present invention pertains. Modifications are possible. Accordingly, the spirit of the present invention should be understood only by the claims set forth below, and all equivalent or equivalent modifications thereof will belong to the scope of the present invention.

1 is a diagram illustrating a concept of a method for supporting mobility of WLAN communication performed at a MAC layer according to an embodiment of the present invention.

2 is a flow chart showing the flow of a wireless LAN communication method according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

211: Maximum Doppler Frequency Measurement Step

212: Time Calculation Step for which the Channel Characteristic Function is Valid

213: Determining data rate

214: Determining size of transmission data

Claims (7)

In the wireless LAN communication method of the mobile, Calculating a maximum Doppler Frequency of the moving body; Calculating a time period for which a channel characteristic function is valid by dividing a first constant by the maximum Doppler frequency; Determining a data transmission rate through any one or more of a signal noise ratio (SNR) measurement method and an auto rate fallback method; And Determining the size of the transmitted data through the time that the channel characteristic function is valid and the data rate; Including, The WLAN is a wireless LAN communication method of any one of IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11n, and IEEE802.11p. The method of claim 1, And the first constant is 0.423. delete delete The method of claim 1, The data transmission rate is a coding rate, and the transmission data size includes any one or more of a packet size and a frame size. The method of claim 1, The WLAN communication method is a wireless LAN communication method of the mobile, characterized in that performed in the MAC layer (MAC Layer). A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 1, 2, 5, and 6.
KR1020090009013A 2009-02-04 2009-02-04 Method for wireless lan communication supporting movability KR100942814B1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101741714B1 (en) * 2016-02-15 2017-05-31 한양대학교 산학협력단 Apparatus and method for transmitting data
KR20190103725A (en) * 2018-02-28 2019-09-05 홍익대학교 산학협력단 Data transmission system, data transmission method and recording medium

Citations (4)

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Publication number Priority date Publication date Assignee Title
JP2002044168A (en) 2000-07-26 2002-02-08 Matsushita Electric Ind Co Ltd Communication terminal, base station unit and communication method
KR20030058101A (en) * 2001-12-29 2003-07-07 엘지전자 주식회사 Method of estimating doppler shifting and transmitting data thereof
KR20060025197A (en) * 2003-06-30 2006-03-20 닛본 덴끼 가부시끼가이샤 Radio communication system and transmission mode selecting method
KR20060114648A (en) * 2005-05-02 2006-11-07 닛본 덴끼 가부시끼가이샤 Mobile communication network, mobile terminal transmission rate scheduling method, base station and recording medium that records program for computer to execute this method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002044168A (en) 2000-07-26 2002-02-08 Matsushita Electric Ind Co Ltd Communication terminal, base station unit and communication method
KR20030058101A (en) * 2001-12-29 2003-07-07 엘지전자 주식회사 Method of estimating doppler shifting and transmitting data thereof
KR20060025197A (en) * 2003-06-30 2006-03-20 닛본 덴끼 가부시끼가이샤 Radio communication system and transmission mode selecting method
KR20060114648A (en) * 2005-05-02 2006-11-07 닛본 덴끼 가부시끼가이샤 Mobile communication network, mobile terminal transmission rate scheduling method, base station and recording medium that records program for computer to execute this method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101741714B1 (en) * 2016-02-15 2017-05-31 한양대학교 산학협력단 Apparatus and method for transmitting data
KR20190103725A (en) * 2018-02-28 2019-09-05 홍익대학교 산학협력단 Data transmission system, data transmission method and recording medium
KR102050533B1 (en) 2018-02-28 2020-01-08 홍익대학교 산학협력단 Data transmission system, data transmission method and recording medium

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