KR20060098212A - Transmission power control method of wireless LAN device - Google Patents

Abstract

Disclosed is a transmission power control method of a wireless LAN device. The method for controlling the transmission power of a wireless LAN device according to the present invention includes the steps of establishing a direct connection link so that an access point (AP) can communicate between two wireless LAN devices in a peer-to-peer manner; When the connection link is established, each wireless LAN device extracts at least one channel rate commonly supported by the opposite wireless LAN device, obtaining a link margin of the opposite wireless LAN device for each extracted channel rate, and the obtained wireless wireless device. And comparing a link margin of the LAN device with a predetermined minimum required link margin, and performing a transmission power adaptation process of adjusting a transmission power for data packet transmission to a counterpart wireless LAN device according to the comparison result. According to the present invention, by using only the minimum transmission power in communication between two WLAN devices, coexistence with other WLAN devices using the same frequency band can be improved.

WLAN, transmit power, TPC, link margin, channel rate

Description

Method for controlling transmission power of wireless local area network device

1 is a block diagram showing the structure of a wireless LAN system according to an embodiment of the present invention;

2 is a flowchart illustrating a method for controlling transmission power of a wireless LAN device according to the present invention;

3 is a message sequence chart illustrating a TPC information exchange process according to the present invention;

4 is a flowchart illustrating a transmission power adaptation process of FIG. 3;

FIG. 5 is a flowchart for explaining an operation of lowering transmission power in FIG. 4.

FIG. 6 is a flowchart for describing an operation of increasing transmission power in FIG. 4.

Explanation of symbols on the main parts of the drawings

100: AP 200: STA1

300: STA2

The present invention relates to a transmission power control method of a wireless LAN device. More particularly, in performing data communication between wireless LAN devices employing IEEE 802.11e / h, other wireless devices using the same frequency band are used. The present invention relates to a transmission power control method of a wireless LAN device capable of improving coexistence with the LAN device.

The Institute of Electrical and Electronics Engineers (IEEE) 802.11e is an enhancement to the quality of service (QoS) capabilities of the existing wireless LAN standard (IEEE 802.11). In the IEEE 802.11 standard, a basic service set (BSS) including an access point (AP) is called an infrastructure structure mode, and a station (STA) which is a wireless node in the infrastructure mode. Since communication between them is performed only through the AP, there is a disadvantage of wasting radio resources.

To compensate for this, IEEE 802.11e introduces Direct Link Set-up (DLS). When DLS is set up between two stations (eg, STA1 and STA2), the two stations STA1 and STA2 can transmit and receive data packets through a peer-to-peer without passing through an AP, thereby efficiently transmitting radio resources. Can be used.

On the other hand, ERC / DEC / (99) 23 is forced to use a transmit power control (TPC) in a Radio Local Area Network (RLAN) operating in the 5Ghz band, which is reflected by the IEEE IEEE 802.11h. TPC provides a protocol for the process of limiting the maximum regulator transmit power and local transmit power and adapting the transmit power according to the available information. However, IEEE 802.11h provides a protocol for adapting a transmission power, but does not provide a transmission power adaptation algorithm.

The biggest problem of these WLAN devices is a power problem. In particular, since portable wireless LAN devices use a battery rather than an AC power source, there is a sensitive requirement for power consumption. That is, in the case of a portable WLAN device, there is a general problem that the use time is limited due to the limitation of the battery capacity.

In particular, a wireless LAN device employing an IEEE 802.11a wireless LAN has a shorter operating time than a device employing an IEEE 802.11b or an IEEE 802.11g wireless LAN. In addition, since the WLAN device divides the limited radio resource from the WLAN device using the 5GHz band ISM (Industrial Scientific Medical) band including other WLAN devices, the other WLAN device is used when more than the required transmission power is used. A problem causing interference occurs.

Therefore, in communicating between WLAN devices, a method for improving coexistence with other WLAN devices using the same frequency band while maintaining an appropriate level of communication quality is required.

The technical problem to be achieved by the present invention is to reduce the power consumption of the WLAN-based device sensitive to power consumption by maintaining the transmission power for data packet transmission within a range that satisfies the minimum required link margin in communication between the WLAN devices. In addition, the present invention provides a method of controlling transmission power of a WLAN device to improve coexistence with other WLAN devices.

In order to solve the above technical problem, a method of controlling a transmission power of a wireless LAN device according to the present invention, an access point (AP) to communicate between two wireless LAN devices in a peer-to-peer (peer-to-peer) Establishing a direct connection link; If the direct connection link is established, extracting at least one channel rate of each of the WLAN devices in common with the other WLAN device; Obtaining a link margin of the counterpart wireless LAN device for each extracted channel rate; And comparing the obtained link margin of the opposite wireless LAN device with a preset minimum required link margin, and performing a transmission power adaptation process of adjusting transmission power for data packet transmission to the opposite wireless LAN device according to the comparison result. It is made, including.

The step of obtaining the link margin of the other party's WLAN device may be performed by performing a TPC (Transmit Power Control) information exchange process supported by IEEE 802.11h to obtain link margin information of the other party's WLAN device.

The TPC information exchange process includes transmitting a TPC information request frame for requesting a link margin to the counterpart WLAN device and a TPC report frame including link margin information of the counterpart WLAN device in response to the TPC information request frame. It characterized in that it comprises a process of receiving.

Meanwhile, the opposite wireless LAN device may obtain the link margin based on a difference between a received signal strength measured at the time of receiving the TPC information request frame and a preset received signal strength threshold.

In the transmission power adaptation process, a process of lowering or increasing the currently set transmission power to adjust the transmission power for data packet transmission to the opposite wireless LAN device to an optimal transmission power satisfying the minimum required link margin according to the comparison result is performed. It is characterized by including.

The process of lowering the transmission power is performed when it is determined that the link margin of the other wireless LAN device is greater than or equal to the minimum required link margin, and the process of increasing the transmission power is performed by the link margin of the other wireless LAN device being the minimum required link. It is characterized in that it is performed when it is judged to be smaller than the margin.

Preferably, the step of lowering the transmission power comprises: setting a level of the transmission power to the lowest level among the N levels; Calculating a new link margin of the other wireless LAN device by subtracting a difference value between a currently set transmission power and a transmission power corresponding to the set level from the link margin of the other wireless LAN device; Determining whether the new link margin is greater than the minimum required link margin; And when it is determined that the new link margin is larger than the minimum required link margin, setting a transmission power value corresponding to the set level as a transmission power for data packet transmission to the counterpart WLAN device.

In addition, the process of lowering the transmission power may include: increasing the set level by one level when it is determined that the new link margin is less than or equal to the minimum required link margin; Determining whether the increased level is equal to or greater than a level corresponding to the currently set transmission power; And when it is determined that the increased level is equal to or greater than a level corresponding to the currently set transmission power, setting a transmission power value corresponding to the increased level as a transmission power for data packet transmission to the counterpart WLAN device. It includes more.

On the other hand, the process of increasing the transmission power, the step of setting the level of the transmission power one level higher than the level corresponding to the currently set transmission power; Determining whether the set level is higher than the highest level among adjustable levels; If it is determined that the set level is lower than the highest level among the adjustable levels, the link margin of the other wireless LAN device and the difference value between the currently set transmission power and the transmission power corresponding to the set level are added. Calculating a new link margin of the opposite wireless LAN device; Determining whether the new link margin is greater than the minimum required link margin; And when it is determined that the set level is greater than or equal to the highest level among the adjustable levels, or when the new link margin is determined to be greater than the minimum required link margin, the transmission power value corresponding to the set level is determined. Setting transmission power for data packet transmission to the device.

In addition, the step of increasing the transmission power, if it is determined that the new link margin is less than the minimum required link margin, increasing the set level by one level; Determining whether the increased level is the highest of the adjustable levels; And when it is determined that the increased level is the highest level among the adjustable levels, a transmission power value corresponding to the increased level is set as a transmission power for data packet transmission to the counterpart WLAN device. It further comprises the step.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail. However, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 is a block diagram showing the structure of a wireless LAN system according to a preferred embodiment of the present invention.

As shown in FIG. 1, the WLAN system according to the present invention is configured as an infrastructure network including an access point 100 (hereinafter referred to as an "AP"). However, the wireless LAN system according to the present invention is a direct link set-up (hereinafter referred to as direct link set-up) so that two WLAN devices (STA1 and STA2) 200 and 300 can communicate in a peer-to-peer manner. Since the IEEE 802.11e wireless LAN supporting the " DLS " function is adopted, the AP 100 only plays a role of establishing DLS between the STA1 200 and the STA2 300. When the DLS is set between the STA1 200 and the STA2 300 by the AP 100, the STA1 200 and the STA2 300 may directly communicate with each other without passing through the AP 100.

In addition, the WLAN system according to the present invention adopts IEEE 802.11h to perform data communication between the STA1 200 and the STA2 300, and transmits transmission power information and link margin information to each other. The transmission power can be adjusted to reduce the power consumption of the WLAN device sensitive to power consumption without interfering with other WLAN devices using the same frequency band.

Hereinafter, referring to FIGS. 2 to 6, two STA1 200 and STA2 300 communicate with each other to control transmission power so as not to interfere with other wireless LAN devices while maintaining appropriate communication quality. Explain how.

First, FIG. 2 is a flowchart illustrating a method for controlling transmission power of a wireless LAN device according to the present invention. The transmission power control process according to the present invention is performed in both STA1 (200) and STA2 (300), in the present embodiment will be described based on the STA1 (200).

Referring to FIG. 2, first, when the AP 100 receives a communication request signal from the STA1 200 or the STA2 300, the AP 100 sets the DLS to enable direct communication between the STA1 200 and the STA2 300 ( S410). Here, since the DLS configuration process is based on the DLS function supported by IEEE 802.11e, a detailed description thereof will be omitted. During this process, the STA1 200 and the STA2 300 exchange channel rate information supported by the STA1 200 and the STA2 300. That is, STA1 200 transmits CR information supported by itself to STA2 300, and STA2 300 also transmits CR information supported by STA2 200 to STA1 200. Accordingly, the STA1 200 and the STA2 300 may know the CR supported by the counterpart STA.

When the DLS is set between the STA1 200 and the STA2 300 through the step 410, the STA1 200 extracts a CR common to the STA2 300 (S420). At this time, if the CRs supported by the STA1 200 are referred to as "Rates_STA1_SET", and the CRs supported by the STA2 300 as "Rates_STA2_SET", Rate_SET, which is a common CR to be used during mutual communication, is obtained by the following.

Rate_SET = Rates_STA1_SET ∩ Rates_STA2_SET

For example, if Rates_STA1_SET = {6Mbps, 9Mbps, 24Mbps, 48Mbps}, and Rates_STA2_SET = {9Mbps, 24Mbps}, Rate_SET = {9Mbps, 24Mbps).

After extracting the commonly supported CR through the step 420, the STA1 200 obtains link margin information of the STA2 300 to determine the transmission power for each extracted CR (S430). In this case, the link margin information for the STA2 300 may be obtained through a transmit power control (“TPC”) protocol provided by IEEE 802.11h.

3 is a message sequence chart illustrating a TPC information exchange process according to the present invention.

Referring to FIG. 3, the STA1 200 first selects a measurement target CR (hereinafter referred to as “CR1”) among extracted common CRs and records a transmission power value for the selected CR1 (S431). The STA1 200 transmits a TPC Request Frame (TPC Request Frame) requesting a link margin to CR1 (eg, 9 Mbps) to the STA2 300 (S432).

Upon receiving the TPC information request frame transmitted from the STA1 200, the STA2 300 calculates a link margin for the CR1 (STA2_CR1_Link_Margin) (S433). The STA2 300 calculates a link margin based on a difference between the received signal strength RSSI_RECV_STA1_CR1 and the preset received signal strength threshold RecvSensitivty measured when the TPC information request frame is received. Since the link margin STA2_CR1_Link_Margin calculated by the STA2 300 is a link margin according to the transmission power of the STA1 200, the link margin is changed according to the transmission power of the STA1 200.

The STA1 200 and the STA2 300 have a lookup table that records threshold values (RecvSensitivty) and minimum required link margin (MinDesiredLinkMargin) information on received signal strength according to reception sensitivity for each CR. The information stored in this lookup table can be used to know the received signal strength required to maintain the optimum communication quality. For example, if -72dBm is set as the received signal strength threshold (RecvSensitivty) for CR1 and 6dB is set as the minimum required link margin (MinDesiredLinkMargin), it is required to receive -72dBm for CR1. In order to maintain optimum communication quality, it means that received signal strength of -66dBm or more is required.

After step 433, the STA2 300 transmits a TPC report frame including the transmission power (TxPower_STA2_CR1) information and the calculated link margin (STA2_CR1_Link_Margin) information for the CR1 to the STA1 200 (S434).

Upon receiving the TPC report frame, the STA1 200 obtains link margin information for the STA2 300 using the information included in the TPC report frame (S435). Through this process, the STA1 200 transmits (TxPower_STA1_CR1) of the STA1 200 to the CR1 among the CRs commonly supported by the STA1 200, the transmit power of the STA2 300 (TxPower_STA2-CR1), and STA2. At 300, link margin (STA2_CR1_Link_Margin) information at the time of packet transmission can be known.

On the other hand, although not shown, through the above process, STA2 (300) also to the transmission power of the STA1 (200), the transmission power of the STA2 (300) and STA1 (200) for CR commonly supported by the STA1 (200) Link margin information at the time of packet transmission can be known.

Referring back to FIG. 2, the STA1 200 transmits power to transmit a data packet to the STA2 300 based on the link margin (STA2_CR1_Link_Margin) information of the STA2 300 for the CR1 obtained through the step 430 (TxPower_STA1_CR1). A transmit power adaptation process of adjusting the transmit power is performed (S440).

4 is a flowchart illustrating a transmission power adaptation process of FIG. 3.

Referring to FIG. 4, first, the STA1 200 reads minimum required link margin information (MinDesiredLinkMargin) information recorded in the lookup table (S441).

Next, the STA1 200 determines whether the link margin STA2_CR1_Link_Margin of the STA2 300 obtained through the step 430 is greater than or equal to the minimum required link margin Read (MinDesiredLinkMargin) (S445).

If it is determined in step 445 that the link margin STA2_CR1_Link_Margin of the STA2 300 is greater than or equal to the minimum required link margin, the STA1 200 performs an operation of lowering the currently set transmission power (S500). If it is determined that the link margin STA2_CR1_Link_Margin of the STA2 300 is smaller than the minimum required link margin (MinDesiredLinkMargin), an operation of increasing the currently set transmission power is performed (S600).

FIG. 5 is a flowchart for describing an operation of lowering transmission power in FIG. 4.

First, when the STA1 200 adjusts the transmit power level to N level, the level corresponding to the currently set transmit power (TxPower_STA1_CR1), that is, when the STA1 200 transmits the TPC information request frame to the STA2 300. A level corresponding to the set transmission power is called an original (orig) level, and a level newly set for power transmission power adjustment is defined as n level.

Referring to FIG. 5, the STA1 200 sets the transmit power level n to the lowest level among adjustable N levels (S510). The STA1 200 subtracts a difference value between the currently set transmission power TxPower_STA1_CR1 from the link margin STA2_CR1_Link_Margin of the STA2 300 and the transmission power STA1_Power_Level_SET [n] to be changed. It is determined whether the minimum required link margin is greater than MinDesiredLinkMargin (S520). Here, the value obtained by subtracting the difference between the currently set transmission power TxPower_STA1_CR1 and the transmission power STA1_Power_Level_SET [n] from the link margin STA2_CR1_Link_Margin of STA2 300 is subtracted from the new link margin value of STA2 300. it means. Meanwhile, in the present embodiment, it is assumed that the minimum required link margin (MinDesiredLinkMargin) of the STA1 200 and the STA2 300 is the same.

As a result of the determination of step 520, a value obtained by subtracting the difference between the currently set transmission power TxPower_STA1_CR1 and the transmission power STA1_Power_Level_SET [n] to be changed from the link margin STA2_CR1_Link_Margin of STA2 300 is the minimum value of STA2 300. When it is determined that it is larger than the required link margin (MinDesiredLinkMargin), the STA1 200 transmits a transmission power value corresponding to the currently set transmission power level STA1_Power_Level_SET [n] to the STA2 300 to transmit power (TxPower) for data packet transmission. Set to). Accordingly, the transmission power of the STA1 200 is set to a value lower than the previously set transmission power value.

On the other hand, as a result of the determination in step 520, the value obtained by subtracting the difference between the currently set transmission power (TxPower_STA1_CR1) and the transmission power (STA1_Power_Level_SET [n]) to be changed from the link margin STA2_CR1_Link_Margin of the STA2 300 is STA2 (300). If less than or equal to the minimum required link margin (MinDesiredLinkMargin), STA1 (200) increases the current transmission power level by one level (S540).

Thereafter, the STA1 200 determines whether the level n increased by one level is equal to or greater than the original (orig) level (S550).

When it is determined in step 550 that the level n increased by one level is equal to or greater than the original orig level, the STA1 200 transmits the power value STA1_Power_Level_SET [orig] corresponding to the original level to the STA2 300. A transmission power (TxPower) for data packet transmission is set (S560). That is, the transmission power of the STA1 200 maintains the transmission power value TxPower_STA1_CR1 set when transmitting the TPC information request frame.

On the other hand, STA1 (200) when the determination result of step 550, the level is increased by one level is determined to be smaller than the original (orig) level to switch to step 520. If it is determined whether the condition of step 520 is satisfied, and if the condition of step 520 is not satisfied, the transmission power level is increased by one level until the condition of step 550 or the condition of step 520 is satisfied. The operation of step 540 is repeated.

6 is a flowchart illustrating an operation of increasing transmission power in FIG. 4.

First, when the STA1 200 adjusts the adjustable transmit power level to N level, the level corresponding to the currently set transmit power (TxPower_STA1_CR1) is referred to as the original (orig) level, and the newly set level for adjusting the transmit power is n level. This is defined as.

 Referring to FIG. 6, the STA1 200 sets a transmission power level n to a level increased by one level from the original (orig) level (S610). The STA1 200 determines whether the currently set level n is higher than or equal to the highest level N among adjustable levels (S620).

If it is determined in step 620 that the currently set level n is smaller than the highest level N, the STA1 200 attempts to change the link margin of the STA2 300 and the currently set transmit power TxPower_STA1_CR1. It is determined whether the value obtained by adding the difference value of the transmission power STA1_Power_Level_SET [n] is larger than the minimum required link margin (MinDesiredLinkMargin) of the STA2 300 (S630).

As a result of the determination in step 630, a value obtained by adding a difference value between the currently set transmission power TxPower_STA1_CR1 and the transmission power STA1_Power_Level_SET [n] to be changed from the link margin STA2_CR1_Link_Margin of the STA2 300 is the minimum value of the STA2 300. If it is determined to be less than or equal to the required link margin MinDesiredLinkMargin, the STA1 200 increases the currently set transmission power level by one level (S640).

Then, the STA1 200 determines whether the level n increased by one level is the highest level N among the adjustable levels (S650).

If it is determined in step 650 that the level n increased by one level is smaller than the highest level N among the adjustable levels, the control proceeds to step 630.

On the other hand, when it is determined in step 650 that the level n increased by one level is the highest level N among the adjustable levels, the STA1 200 transmits STA1_Power_Level_SET corresponding to the level increased by one level. [n]) is set to a transmit power (TxPower) for data packet transmission to the STA2 300 (S660).

On the other hand, when the determination result of the step 620 is determined that the current level (n) is higher than the highest level (N) of the adjustable level, or the determination result of the step 630 link margin (STA2_CR1_Link_Margin) of the STA2 (300), If the value obtained by adding the difference between the currently set transmission power (TxPower_STA1_CR1) and the transmission power (STA1_Power_Level_SET [n]) to be changed is greater than the minimum required link margin (MinDesiredLinkMargin) of the STA2 (300), The corresponding transmit power value is set to transmit power (TxPower) for data packet transmission to the STA2 300. That is, the transmission power TxPower of the STA1 200 is set to a transmission power value corresponding to a level one level larger than the original level.

Meanwhile, the method of controlling the transmission power set in the STA1 200 has been described above, but the transmission power set in the STA2 300 may be controlled by the same method as described above. In addition, in the above, only the process of determining the transmission power for any one CR (eg, CR1) among the CRs common to STA2 300 has been described. However, the same process as described above is performed to transmit all the common CRs. Of course, the power can be determined.

In addition, the terms used in the present invention (terminology) are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a person skilled in the art, and the definitions are used throughout the present invention. It should be based on.

On the other hand, the present invention has been described in detail through a representative embodiment, but those skilled in the art to which the present invention pertains various modifications within the scope of the present invention without departing from the scope of the present invention. I will understand what is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

As described above, according to the present invention, the power consumption of the WLAN device can be reduced by using the transmission power satisfying the minimum required link margin required for communication between the two WLAN devices. In particular, when one of the communication target devices is a portable wireless LAN device that is operated by a battery, the battery consumption can be reduced to increase the operation time.

In addition, according to the present invention, by using only the minimum transmission power in communication between two WLAN devices, by reducing interference with other WLAN devices using the same frequency band to improve coexistence, it is possible to efficiently use radio resources. Can be used.

Claims (10)

Establishing a direct connection link so that an access point (AP) can communicate in a peer-to-peer between two WLAN devices; If the direct connection link is established, extracting at least one channel rate of each of the WLAN devices in common with the other WLAN device; Obtaining a link margin of the counterpart wireless LAN device for each extracted channel rate; And Comparing the obtained link margin of the opposite wireless LAN device with a preset minimum required link margin, and performing a transmission power adaptation process of adjusting transmission power for data packet transmission to the opposite wireless LAN device according to the comparison result; Transmission power control method of a wireless LAN device comprising a. The method of claim 1, The step of obtaining a link margin of the opposite side wireless LAN device, Transmitting power control method of a wireless LAN device, characterized in that to obtain link margin information of the wireless LAN device by performing a transmit power control (TPC) information supported by IEEE 802.11h. The method of claim 2, The TPC information exchange process, Transmitting a TPC information request frame for requesting a link margin to the counterpart WLAN device and receiving a TPC report frame including link margin information of the counterpart WLAN device in response to the TPC information request frame; Transmission power control method of a wireless LAN device, characterized in that. The method of claim 3, wherein The counterpart wireless LAN device calculates the link margin based on a difference value between a received signal strength measured at the time of receiving the TPC information request frame and a preset received signal strength threshold value. The method of claim 1, The transmission power adaptation process, And reducing or increasing the currently set transmission power to adjust the transmission power for data packet transmission to the opposite wireless LAN device to an optimum transmission power satisfying the minimum required link margin according to the comparison result. Transmission power control method of LAN device. The method of claim 5, The process of lowering the transmission power is performed when it is determined that the link margin of the other wireless LAN device is greater than or equal to the minimum required link margin, and the process of increasing the transmission power is performed by the link margin of the other wireless LAN device being the minimum required link. The transmission power control method of a wireless LAN device, characterized in that performed when it is determined that the margin is smaller than. The method of claim 6, The process of lowering the transmission power, Setting a level of transmit power to the lowest level among the N levels; Calculating a new link margin of the other wireless LAN device by subtracting a difference value between a currently set transmission power and a transmission power corresponding to the set level from the link margin of the other wireless LAN device; Determining whether the new link margin is greater than the minimum required link margin; And If it is determined that the new link margin is larger than the minimum required link margin, setting a transmission power value corresponding to the set level as a transmission power for data packet transmission to the counterpart WLAN device. Transmission power control method of a wireless LAN device. The method of claim 7, wherein The process of lowering the transmission power, If the new link margin is determined to be less than or equal to the minimum required link margin, increasing the set level by one level; Determining whether the increased level is equal to or greater than a level corresponding to the currently set transmission power; And If it is determined that the increased level is equal to or greater than a level corresponding to the currently set transmission power, setting a transmission power value corresponding to the increased level as a transmission power for data packet transmission to the counterpart WLAN device; Transmission power control method of a wireless LAN device further comprising. The method of claim 6, The process of increasing the transmission power, Setting a level of transmission power one level higher than a level corresponding to a currently set transmission power; Determining whether the set level is higher than the highest level among adjustable levels; If it is determined that the set level is lower than the highest level among the adjustable levels, the link margin of the other wireless LAN device and the difference value between the currently set transmission power and the transmission power corresponding to the set level are added. Calculating a new link margin of the opposite wireless LAN device; Determining whether the new link margin is greater than the minimum required link margin; And When it is determined that the set level is equal to or higher than the highest level among the adjustable levels, or when the new link margin is determined to be larger than the minimum required link margin, the transmission power value corresponding to the set level is determined. And setting the transmission power for data packet transmission to the wireless LAN device. The method of claim 9, The process of increasing the transmission power, If it is determined that the new link margin is less than or equal to the minimum required link margin, increasing the set level by one level; Determining whether the increased level is the highest of the adjustable levels; And If it is determined that the increased level is the highest level among the adjustable levels, setting a transmission power value corresponding to the increased level as a transmission power for data packet transmission to the counterpart WLAN device. Transmission power control method of a wireless LAN device, characterized in that it further comprises.

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