KR20070102847A - Apparatus and method for transmitting wireless data - Google Patents

Abstract

The present invention relates to an apparatus and a method for transmitting wireless data, wherein in a multi-channel environment, data is transmitted through one subchannel of a first channel and wireless of subchannels included in a first channel through a second channel. An apparatus and method for transmitting wireless data for transmitting data over an optimal detailed channel after checking the status.

An apparatus for transmitting wireless data according to an embodiment of the present invention includes a first physical unit for transmitting a radio signal for a data frame through a specific channel among a plurality of channels included in a predetermined frequency band, and during transmission of the radio signal. And a second physical unit for checking a network state of the remaining channels other than the specific channel among the plurality of channels, and a MAC unit for changing a channel through which the radio signal is transmitted according to the checking result.

Description

Apparatus and method for transmitting wireless data

1 is a conceptual diagram illustrating a structure of a communication module for channel search in the related art.

2 is a conceptual diagram illustrating that a frame is transmitted and received through a multi-channel according to an embodiment of the present invention.

3 is a conceptual diagram illustrating a communication layer according to an embodiment of the present invention.

4 is a block diagram illustrating an apparatus for transmitting wireless data according to an embodiment of the present invention.

5 is a conceptual diagram illustrating that a channel is divided according to an embodiment of the present invention.

6 illustrates a frame for channel search according to an embodiment of the present invention.

7 is a flowchart illustrating a process of transmitting wireless data according to an embodiment of the present invention.

<Explanation of symbols on main parts of the drawings>

410: CPU 420: memory

430 bus 440 MAC unit

450: first PHY unit 460: second PHY unit

453: first antenna 463: second antenna

The present invention relates to an apparatus and a method for transmitting wireless data. More particularly, the present invention relates to an apparatus for and method of transmitting wireless data, and more particularly, to determine an optimal channel after confirming wireless states of channels through another channel while simultaneously transmitting data through one channel. An apparatus and method for transmitting wireless data for transmitting data over a network are provided.

The basic building block of a network for data communication between wireless stations is called a basic service set (BBS), which is an independent basic service set and an infrastructure basic service set according to its characteristics. BBS).

In an independent basic service set, a station in a communication area is characterized by direct communication with another station, which is used for short service life and small network configuration. Meanwhile, the infrastructure basic service set is distinguished from the independent basic service set by using an access point. The access point is used in all communication processes including communication of the mobile station in the same service area. Therefore, since all communication is transmitted by the access point, the corresponding basic service area in the infrastructure basic service set is defined as an area capable of receiving a signal from the access point.

Communication between stations constituting the wireless network is basically configured through a scanning, authentication and association step. In this case, when a search is required, when initializing an independent basic service set network, finding and joining a network, finding a new access point, and dynamic frequency selection, etc. This includes.

Dynamic frequency selection is a method used to communicate through other better channels when the current communication channel is not in good condition, and transmits a probe request frame and responds to the probe response frame in response thereto. It is classified into an active method of receiving a Probe Response Frame and a passive method of receiving a Beacon frame.

The probe request frame includes a MAC header and a frame body. The frame body includes a service set identification field and a rate field supported by the data transmission apparatus.

The station receiving the probe request frame transmits a probe response frame. The responsibility for responding to the probe request frame is the last station sending the beacon, which is the access point in the infrastructure network, and the responsibility for transmitting the beacon is distributed in the independent basic service set network. After sending a beacon, the station is responsible for sending a probe response during the next beacon interval.

Beacon frames are transmitted periodically to not only match the parameters for the station to join the network, but also to find and recognize the network. In an infrastructure network, an access point is responsible for the transmission of beacon frames. The area in which the beacon frame appears defines the basic service area. Since all communication in the infrastructure network is through the access point, the stations in the network must be close enough to receive beacon frames.

1 is a conceptual diagram illustrating a structure of a communication module for conventional channel search, each of which includes one media access control (MAC) unit 11, a baseband processor 12, and a radio frequency (RF) unit 13. Indicates that data frame 21 is transmitted and channel search is performed.

The data frame 21 generated by the MAC unit 11 is transferred to the baseband processor 12 in the form of a MAC Protocol Data Unit (MPDU), and the baseband processor 12 transmits a signal field to the MPDU. And add a preamble to generate a PHY Protocol Data Unit (PPDU). The RF unit 13 converts the PPDU into a radio signal, and the radio signal is transmitted through an antenna.

At this time, if the state of the radio channel to which the radio signal for the data frame 21 is transmitted is not good, the MAC unit 11 performs a process of the baseband processor 12 and the RF unit 13 to search for a better channel. The channel is changed and a beacon frame or probe response frame 22 is received through the changed channel. However, as shown in FIG. 1, since the baseband processor 12 and the RF unit 13 are each one, transmission of the data frame 21 must be stopped to receive the beacon frame or the probe response frame 22. .

That is, in performing the dynamic frequency selection, the currently engaged channel must be released. Accordingly, data transmission can be stopped. Accordingly, there is a need for the emergence of an invention in which data transmission and channel search can be performed simultaneously.

The present invention transmits data through one subchannel of a first channel in a multi-channel environment and simultaneously checks the radio status of the subchannels included in the first channel through the second channel, and then transmits the data through the optimal subchannel. The purpose is to send a message.

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

In order to achieve the above object, an apparatus for transmitting wireless data according to an embodiment of the present invention includes a first physical unit for transmitting a radio signal for a data frame through a specific channel of a plurality of channels included in a predetermined frequency band; And a second physical unit for checking a network state of a channel other than the specific channel among the plurality of channels during the transmission of the wireless signal, and a MAC unit for changing a channel through which the wireless signal is transmitted according to the checking result. .

According to an embodiment of the present invention, a method of transmitting wireless data includes (a) transmitting a radio signal for a data frame through a specific channel among a plurality of channels included in a predetermined frequency band, and (b) the radio signal. Confirming the network status of the remaining channels other than the specific channel among the plurality of channels during the transmission of (c) and changing the channel through which the wireless signal is transmitted according to the checking result.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a conceptual diagram illustrating transmission and reception of a frame through a multi-channel according to an embodiment of the present invention. The data frame 211 is provided through one channel (hereinafter, referred to as a first channel) 201 among a plurality of communication channels. A radio signal of 212 is transmitted, and a frame 230 for confirming a network state of the first channel 201 is received through another channel (hereinafter referred to as a second channel) 202.

An apparatus for transmitting wireless data (hereinafter, referred to as a data transmitting apparatus) is an apparatus for receiving wireless data through a first channel 201 (hereinafter, referred to as a data receiving apparatus). I can send it. However, a predetermined interframe space (IFS) 250 exists between the plurality of data frames 211 and 212. The IFS 250 includes an extended interframe space (EIFS), a distributed interframe space (DIFS), and a point interframe (PIFS). Space or Short Interframe Space (SIFS).

In this case, the data frames 211 and 212 include a preamble, a signal field, and a payload. The preamble is a signal for synchronization and channel estimation of the PHY layer (physical layer), and consists of a plurality of short training signals and long training signals. Short training signals are used for signal detection, AGC (Auto Gain Control), fine time synchronization, and integer frequency error estimation. Long training signals are used for channel estimation and fractional frequency error estimation. In general, performing fast and accurate estimates can greatly affect overall system performance.

The signal field includes a RATE field indicating a transmission rate, a LENGTH field indicating a length of a PHY Protocol Data Unit (PPDU), and the like. In general, a signal field is encoded by one symbol.

The preamble and signal fields are called a PHY header. A payload is located after the PHY header.

As described above, the second channel 202 is a channel for receiving a frame for checking the network state of the first channel 201 and is a beacon frame or a probe response frame 230. This is the channel being received.

The beacon frame and the probe response frame 230 may be received from an access point in an infrastructure BBS network environment and from a data receiving device in an independent BBS network environment. Can be. Here, the probe response frame is a response frame to the probe request frame, and the probe request frame is also transmitted through the second channel 202.

In addition, the data transmission apparatus may be an access point, where the data transmission apparatus may receive the beacon frame or the probe response frame 230 from another station participating in the network.

The first channel 201 may be classified into a plurality of detailed channels 2011, 2012, and 2013, and the data frames 211 and 212 are transmitted through one of the detailed channels 2011. At the same time as the data frames 211 and 212 are transmitted, the data transmission apparatus receives the beacon frame or the probe response frame (hereinafter, referred to as a search frame) 230 through the second channel 202.

Here, the second channel 202 is a subchannel (2012, 2013) except for the subchannel (2011) in which the data frames (211, 212) are transmitted among the subchannels (2011, 2012, 2013) of the first channel (201). It is used to receive the search frame 230 for checking the network status of the), the data transmission apparatus checks the reception sensitivity of the search frame 230 received through each sub-channel (2012, 2013), Determine the detail channel with the highest reception sensitivity.

In FIG. 2, the detail channel having the highest reception sensitivity is the second detail channel 2012, and accordingly, the data transmission apparatus performs a second detail on the first detail channel 2011 currently transmitting the data frames 211 and 212. Change to channel 2012 and continue to transmit data frames 221 and 222 over second sub-channel 2012.

3 is a conceptual diagram illustrating a communication layer according to an embodiment of the present invention.

In general, the communication layer 300 begins with the channel layers 340 and 360, which represent the physical medium in the predetermined frequency band at which the radio signal propagates at the lowest level, and the radio frequency layers 332 and 352 and the base. PHY layers 330 and 350 including baseband layers 331 and 351, a media access control layer 320 and an upper layer 310. Here, the upper layer 310 may be a layer above the MAC layer 320 and may include an LLC layer, a network layer, a transport layer, an application layer, and the like.

However, according to the present invention, a wireless channel is classified into a first channel 201 and a second channel 202, and two PHY layers 330 and 350 respectively responsible for both channels 201 and 202 exist separately. However, although the PHY layers 330 and 350 are separately formed according to each channel, the layers 310 or more of the MAC layer 320 for media access control may be formed as one.

The first channel 201 and the second channel 202 may include a 2.4 GHz, 5 GHz or 60 GHz band, where the first channel 201 and the second channel 202 are considered to overlap each other in a similar frequency band. Can be. That is, the second channel 202 is used to receive the search frame 230 through a specific frequency band among the plurality of frequency bands (detailed channels) included in the first channel 201, and through this, the data transmission apparatus may receive the first frame. The network status of the detailed channels included in the one channel 201 can be checked.

4 is a block diagram illustrating an apparatus for transmitting wireless data according to an exemplary embodiment of the present invention. The apparatus for transmitting wireless data, that is, the data transmitting apparatus 400 may include a CPU 410, a memory 420, and a MAC unit ( 440, a first PHY unit 450, and a second PHY unit 460.

The CPU 410 controls other components connected to the bus 430 and is responsible for the tasks of the upper layers shown in FIG. Accordingly, the CPU 410 processes the received data (received MSDU; MAC Service Data Unit) provided from the MAC unit 440 or generates and provides the transmitted data (send MSDU) to the MAC unit 440.

The memory 420 serves to store data. The memory 420 may include a hard disk, an optical disk, a flash memory, a compact flash card, a secure digital card, a smart media card, a multimedia card, or a memory stick. As a module capable of inputting / outputting such information, the module may be provided inside the data transmission apparatus 400 or may be provided in a separate device.

The MAC unit 440 generates a MAC Protocol Data Unit (MPDU) by adding a MAC header to an MSDU, that is, data to be transmitted, provided from the CPU 410.

In addition, the MAC unit 440 checks the type of the frame to be transmitted and received and controls the path so that the frame can be transmitted and received through the corresponding PHY unit. For example, the MAC unit 440 allows the data stored in the memory 420 to be transmitted through the first PHY unit 450 and the search frame is transmitted through the second PHY unit 460.

The first PHY unit 450 converts the MPDU generated by the MAC unit 440 into a radio signal, and then transmits the signal through the first channel 201. To this end, the first PHY unit 450 includes a first baseband processor and a first Radio Frequency (RF) unit, and is connected to the first antenna.

The first baseband processor receives the MPDU generated by the MAC unit 440 and generates a PHY Protocol Data Unit (PPDU) by adding a signal field and a preamble. Then, the first RF unit converts the generated PPDU into a radio signal and transmits it through the first antenna.

As described above, the radio signal for the data frame is not transmitted through the entire first channel 201, but may be transmitted through a specific frequency band of the frequency bands of the first channel 201. That is, the first channel 201 is classified into a plurality of subchannels, and a radio signal is transmitted through one subchannel thereof. A detailed description of the detailed channel will be described later with reference to FIG. 5.

As a radio signal for a data frame is transmitted through the first channel 201, the data receiving apparatus transmits an acknowledgment frame (ACK frame) for each data frame. The acknowledgment frame is transmitted after the IFS has elapsed. Different values may be used for the IFS between the data frames and the IFS between the data frame and the acknowledgment frame.

As the acknowledgment frame is received, the MAC unit 440 is able to check the network status for a particular sub-channel of the first channel 201 where the radio signal for the current data frame is transmitted, which is not good. In this case, the search frame is received through the second channel 202. Here, since the data frame is transmitted through the first channel 201 and the search frame is received through the second channel 202, the transmission of the data frame and the reception of the search frame can be performed simultaneously.

The search frame is a beacon frame or a probe response frame and may be received for each frequency band. That is, the MAC unit 440 sequentially changes a plurality of reception frequency bands supported by the second PHY unit 460, so that the second PHY unit 460 may receive a search frame corresponding to the frequency band. It will be possible.

The MAC unit 440 which has received the received search frame checks the reception sensitivity of the search frame. Here, the reception sensitivity may be a received signal strength indicator (RSSI), a signal to noise ratio (SNR), a bit error rate (BER), a packet error rate (PER), a signal to interference ratio (SIR), or a carrier to interference ratio (CIR). It may be by.

Then, the MAC unit 440 checks the frequency band having the highest reception sensitivity with reference to the confirmed reception sensitivity, and then sends the detailed channel of the first channel 201 that transmits the radio signal of the current data frame to the identified frequency band. Change to the corresponding detail channel.

Accordingly, the data transmitting apparatus 400 may transmit the data frame and check the network status of the detailed channels at the same time, thereby transmitting the data frame through the channel having a better network status without interrupting the data frame transmission.

5 is a conceptual diagram illustrating that a channel is divided according to an embodiment of the present invention.

The first channel 500 may be classified into a plurality of subchannels 510, 520, and 530. The data transmission apparatus 400 may transmit a radio signal for a data frame through one of the subchannels. .

5 shows that the first channel 500 is classified into three subchannels 510, 520, and 530. At this time, when a radio signal for a data frame is being transmitted through the first detail channel 510, the MAC unit 440 may determine that the network state of the first detail channel 510 is changed using an acknowledgment frame for the data frame. Determine whether it is good or not.

Thus, if it is determined that the network state of the first detail channel 510 is not good, the MAC unit 440 checks the network state of the second detail channel 520 and the third detail channel 530. To this end, the MAC unit 440 sequentially changes the frequency band of the second PHY unit 460. That is, the second subchannel 520 and the third subchannel 530 may include a plurality of frequency bands 550 (551, 552, 553, 554, 555, 556, 557, and 558). 440 sequentially changes a plurality of frequency bands 550 included in each subchannel.

In FIG. 5, N frequency bands 550 included in the second sub-channel 520 and the third sub-channel 530 exist, and the second PHY unit 460 sequentially transmits the beacon frame or the beacon frame through the changed frequency band. Receive a probe response frame (search frame). Here, in order to receive the probe response frame, the second PHY unit 460 may transmit a probe request frame in advance.

Thus, the received search frame is delivered to the MAC unit 440, and the MAC unit 440 confirms the reception sensitivity of the search frame received in each frequency band. The MAC unit 440 confirming the reception sensitivity of all search frames identifies the frequency band having the highest reception sensitivity.

In FIG. 5, when the reception sensitivity of the search frame received through the third frequency band 553 is the highest, the MAC unit 440 has the highest network state of the second sub-channel 520 including the tooth 553. If it is determined that it is good, the subchannel for transmitting the data frame is changed from the first subchannel 510 to the second subchannel 520. That is, the frequency band of the first PHY unit 450 is changed.

Accordingly, radio signals for subsequent data frames are transmitted on the second subchannel 520.

6 illustrates a frame for channel search according to an embodiment of the present invention.

The frame for channel search, that is, the search frame 600 for checking the network status of a specific channel, includes a MAC header 610, a frame body 620, and a frame check sequence field 630. do.

Here, the MAC header 610 may include a frame control field 611, a persistent field 612, a destination address field 613, a source address field 614, a basic service set ID field 615, and a sequence control field 616. It is configured to include.

The frame control field 611 includes a Type field (not shown) and a Subtype field (not shown). The type field (not shown) is a type of frame (management frame, control frame or Data frame) and floating fields (not shown) represent details about types. In the present invention, since the search frame 600 corresponds to a management frame, a value of 00 is input in the type field (not shown), and a value of 0101 or 1000 indicating a probe response or beacon is input in the floating field (not shown). Can be.

In the destination address field 613, the address of the station that will receive the search frame 600 is input. The destination address, like Ethernet, is a 48-bit IEEE MAC identifier that corresponds to a station (final receiver) that forwards to the upper protocol layer for frame operations. Meanwhile, in the present invention, since the search frame 600 is preferably transmitted to all stations participating in the network, a broadcast address may be input to the destination address field 613.

In the frame body 620 of the search frame 600, a mandatory field 621 including a beacon interval field (not shown), a service set identification field (not shown), and the like, and values of various parameter sets are input. An optional field 622 is included that includes the fields that were assigned. Here, the presence or absence of a traffic indication map (not shown) in the optional field 622 is determined depending on whether the search frame 600 is a beacon frame or a probe response frame.

In addition, the search frame 600 according to an embodiment of the present invention may include a search time required field 6161, a search start time field 6162, and a channel switch time field 6163. The estimated time required for the data transmission apparatus 400 to check the status of the entire network is input in the search time required field 6161, and the time at which the network start time has been checked is input in the search start time field 6162. In the switching time field 6163, a time for which switching of the channel is expected to be performed is input.

The information (hereinafter, referred to as channel search information) input in the search time field 6161, the search start time field 6162, and the channel switch time field 6163 are notified to the stations participating in the network, and the corresponding channel for the corresponding period. It is to prevent the use of the and to allow the data receiving apparatus to switch the channel at the time of the channel switching so that the uninterrupted data transmission can be performed.

Meanwhile, such channel search information is generated by the data transmission apparatus 400. In order to notify all stations participating in the network, the data transmission apparatus 400 inserts the channel search information into a probe request frame or a separate frame. Then, by transmitting this to the access point, the access point can be transmitted to the beacon frame or probe response frame to all stations participating in the network, the data transmission apparatus 400 itself is a search frame containing the channel search information directly 600 may be sent to all stations participating in the network.

The frame check sequence entered in the frame check sequence field 630 is used to cause the station to check the integrity of the received frame. The frame check sequence is often referred to as a cyclic redundancy check due to its inherent theoretical construction, where the MAC header 610 and all fields in the frame body are included in the frame check sequence. The station receiving the frame compares the frame check sequence with the value obtained by a preset mathematical operation to determine whether there is an error in the frame.

In a wireless network, a receiving station must send an acknowledgment frame to a transmitting station for a frame that has passed the integrity check. If the acknowledgment frame is not transmitted, the transmitting station determines that an error has occurred in the frame or frame transmission and retransmits the frame. do.

In the present invention, the data transmission apparatus 400 may check the network state of the corresponding channel by using an acknowledgment frame for the transmitted data frame.

7 is a flowchart illustrating a process of transmitting wireless data according to an embodiment of the present invention.

In order to transmit a data frame through a channel having a better network state, the first PHY unit 450 of the data transmitting apparatus 400 firstly transmits the data frame through any of the plurality of detail channels included in the first channel. Transmit the radio signal for (S710).

Accordingly, the first PHY unit 450 receives an acknowledgment frame for the data frame from the data receiving device.

The acknowledgment frame is transmitted to the MAC unit 440. The MAC unit 440 checks the network state of the detailed channel through which the radio signal is transmitted with reference to the transmitted data frame and the received acknowledgment frame (S720). Thus, if the network condition is good, the radio signal for the data frame is continuously transmitted through the corresponding detail channel, and if the network condition is not good, the search frame 600 is received through the second channel.

That is, the MAC unit 440 sequentially changes a plurality of frequency bands supported by the second PHY unit 460 (S730). Accordingly, the second PHY unit 460 receives the search frame 600 through the changed frequency band (S740). Here, the frequency band for receiving the search frame 600 may be smaller than the frequency band by the detail channel of the first channel. That is, the second PHY unit 460 may receive the search frame 600 through a plurality of frequency bands included in one subchannel.

Meanwhile, in changing the frequency band of the second PHY unit 460, the MAC unit 440 may exclude the detailed channel on which the current data frame is being transmitted. Accordingly, the transmission of the data frame and the reception of the search frame 600 may be simultaneously performed.

The received search frame 600 is transmitted to the MAC unit 440, and the MAC unit 440 checks the reception sensitivity of the search frame 600 (S750). Here, the signal is caused by a received signal strength indicator (RSSI), a signal to noise ratio (SNR), a bit error rate (BER), a packet error rate (PER), a signal to interference ratio (SIR) or a carrier to interference ratio (CIR). Can be.

The MAC unit 440 checks whether a change to all frequency bands is performed (S760). If the change to all frequency bands is performed, the second PHY unit 460 detects the search frame 600 through each frequency band. Upon reception, the MAC unit 440 checks the frequency band providing the highest value among the confirmed reception sensitivity (S770).

The MAC unit 440 performs a channel change to a detailed channel including the identified frequency band among the detailed channels of the first PHY unit 450 (S780).

As a result, the first PHY unit 450 transmits the data frame through a channel having a better network condition.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

According to the apparatus and method for transmitting wireless data according to the present invention as described above, in a multi-channel environment, the subchannel included in the first channel through the second channel while transmitting data through one subchannel of the first channel. After confirming their wireless state, there is an advantage that the transmission of data through the first channel is not interrupted by transmitting data through the optimal subchannel.

Claims (16)

A first physical unit transmitting a radio signal for a data frame through a specific channel among a plurality of channels included in a predetermined frequency band; A second physical unit that checks a network state of channels other than the specific channel among the plurality of channels during transmission of the radio signal; And And a MAC unit for changing a channel through which the radio signal is transmitted according to the confirmation result. The method of claim 1, The second physical unit checks the network state using the reception sensitivity of the received beacon frame, or receives the probe response frame received in response to the probe request frame. And apparatus for transmitting wireless data using the sensitivity to confirm the network condition. The method of claim 2, The second physical unit transmits wireless data for confirming the network state by using the reception sensitivity of the beacon frame or the probe response frame received through a specific frequency band among a plurality of frequency bands included in each of the remaining channels. Device. The method of claim 2, And the MAC unit transmits radio data for changing a channel through which the radio signal is transmitted to a channel having the highest reception sensitivity among the reception sensitivity for each of the remaining channels. The method of claim 2, The reception sensitivity is determined by a received signal strength indicator (RSSI), a signal to noise ratio (SNR), a bit error rate (BER), a packet error rate (PER), a signal to interference ratio (SIR), or a carrier to interference ratio (CIR). Apparatus for transmitting wireless data, including by. The method of claim 2, And the destination address included in the probe request frame includes a broadcast address. The method of claim 2, Wherein the beacon frame or the probe response frame is received from an access point. The method of claim 2, The beacon frame or the probe response frame A search time field in which an estimated time for checking the network state is input; A search start time point field in which a time at which the network status is started to be checked is input; And And a channel switch time field input with an expected time at which the change is performed. (a) transmitting a radio signal for a data frame through a specific channel among a plurality of channels included in a predetermined frequency band; (b) checking a network state of channels other than the specific channel among the plurality of channels during transmission of the wireless signal; And and (c) changing a channel through which the radio signal is transmitted according to the confirmation result. The method of claim 9, In step (b), the network status is checked using the received sensitivity of the received beacon frame, or the probe response frame is received in response to the probe request frame. Identifying the network condition using sensitivity. The method of claim 10, The step (b) includes the step of checking the network state using the reception sensitivity of the beacon frame or the probe response frame received through a specific frequency band among a plurality of frequency bands included in each of the remaining channels. How to send data. The method of claim 10, And (c) changing the channel through which the wireless signal is transmitted to the channel having the highest reception sensitivity among the reception sensitivity for each of the remaining channels. The method of claim 10, The reception sensitivity is determined by a received signal strength indicator (RSSI), a signal to noise ratio (SNR), a bit error rate (BER), a packet error rate (PER), a signal to interference ratio (SIR), or a carrier to interference ratio (CIR). A method of transmitting wireless data, including by. The method of claim 10, And the destination address included in the probe request frame includes a broadcast address. The method of claim 10, The beacon frame or the probe response frame is received from an access point. The method of claim 10, The beacon frame or the probe response frame A search time field in which an estimated time for checking the network state is input; A search start time point field in which a time at which the network status is started to be checked is input; And And a channel switch time field inputted with an estimated time at which the change is performed.

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