WO2006012772A1

WO2006012772A1 - A method of transmission in wlan

Info

Publication number: WO2006012772A1
Application number: PCT/CN2004/000891
Authority: WO
Inventors: Feng Li; Fengguo Ma; Bin Duan; Bo Sun; Gonghang Sun; Yin Gao
Original assignee: Zte Corporation
Priority date: 2004-08-06
Filing date: 2004-08-06
Publication date: 2006-02-09
Also published as: CN100525191C; CN1977492A

Abstract

The invention discloses a method for transmitting data in WLAN. It includes: sending a sending frame from the sender to the receiver at the current rate; returning the information about the transmission rate or the channel quality from the receiver to the sender; adjusting the current rate according to the above-mentioned information about the transmission rate or the channel quality; and sending the next sending frame from the sender to the receiver at the adjusted current rate.

Description

Wireless local area network transmission method

Technical field

Field of the Invention This invention relates generally to wireless communication technologies and, more particularly, to a wireless local area network multi-rate transmission method. Background technique

The WLAN is usually based on the Carrier Sense Multiple Access Protocol (CSMA). The improvements are as follows: split-channel reservation multiple access (SRMA), multiple access with collision (MAC) (multiple access with collision) Avoidance), improved collision avoidance multiple access protocol (MACAW), bottom acquisition multiple access (FAMA), and 802.11. The wireless local area network referred to in the present invention is generally in the CSMA protocol. Multi-rate transmission in a WLAN requires two major issues to be addressed: channel shield estimation and rate selection. The channel quality estimation mainly uses the statistics of signal-to-noise ratio, signal strength, bit error rate, symbol error rate or frame error rate as the decision measure to measure the transmission quality of the channel. At present, there are many implementation methods and mature.

In wireless LANs, there are currently two current rate selection methods: one is the "Auto Rate Fallback Protocol" and the other is the "Receiver Based Auto Rate" protocol. . The automatic rate stimuli protocol was proposed by Eddie Camoman et al. The core idea is to adjust the transmission rate based on the number of successes and failures of previous transmissions. This is actually a rate adjustment system based on the frame rate. After a certain number of successful transmissions between stations, the channel quality is considered to be reliable and the transmission rate is increased step by step. Conversely, if the transmission between stations fails, the channel shield is considered to be degraded. Level reduces the transmission rate. According to the protocol, the transmission rate of each frame in the same transmission process is constant, so multi-rate transmission does not cause a change in duration, and is suitable when the channel change between stations is slow. However, it does not apply to the wireless mobile channel environment, because in the wireless mobile channel, the channel quality changes faster, and the channel is coherent. The time is short, and the data transmission interval of several successes or failures is used as the channel shield time window time is too long, so that the channel quality statistics are unreliable and the transmission throughput rate is decreased. The receiver-based automatic rate protocol was proposed by Gavin Holland, Natin Weidya and Pavlo Barr, which overcomes the shortcomings of automatic rate-strain protocols that cannot accommodate wireless mobile channels. Its core idea is

The transmission rate and frame length of the frame are inserted in the duration subfield of the MAC frame header. At the initial transmission, the transmitting station transmits a "transmission request frame" at a rate of a basic rate concentration, and the receiving station estimates channel quality information according to the received signal, and then adaptively adjusts the transmission rate, and the transmitting station receives the acknowledgement frame returned by the station. The transmission rate transmits the next frame, and the node that does not participate in the communication corrects the network allocation vector in real time according to the data transmission rate and frame length of the received signal. Since the time interval of the channel quality is measured by one frame transmission interval in one transmission process, the protocol rate change is real-time and suitable for the wireless mobile channel. The main disadvantage of this protocol is that the sending station always sends the data frame at the sending rate of the acknowledgment frame returned by the receiving node. The sending station or the receiving station cannot predetermine the transmission rate when sending the next frame, so it cannot be accurately set. At the end of the entire transmission, the duration field content has to be changed to the transmission rate and the transmission frame length so that the node that does not participate in the communication corrects the network allocation vector. In addition to large-scale fading, the wireless channel also has small-scale fading. When the node moves at high speed, the channel state information of the physical channel changes rapidly. For reliable communication, there is a certain limit on the transmission frame length, and a longer MAC frame. It is often divided into multiple small segments. The network allocation vector correction method based on the receiver's automatic rate protocol is not only inferior to the existing protocol, but also because its duration field does not have the reservation effect on the next frame transmission channel and is not suitable for multi-segment transmission. In addition, the frame length of the acknowledgement frame returned by the receiving node is usually much smaller than the length of the data frame sent by the transmitting station. In the case of the same bit error rate, the frame error rate increases as the frame length increases, so that the receiving frame can reliably return the acknowledgement frame. Sending data frames at the transmission rate is not statistically reliable. Therefore, the protocol is not applicable to wireless high-speed mobile channels and has poor compatibility.

In addition to the above two multi-rate transmission protocols, there is also a dual-channel slotted ALOHA multi-rate transmission protocol in the WLAN. The protocol uses an independent control channel for the transmission rate setting. Due to the excessive use of channel resources, it is very practical. Use less. Summary of the invention

In order to solve the above problems in the prior art, the present invention provides a method for transmitting data in a wireless local area network, including: transmitting a transmission frame from a transmitting direction to a receiving side at a current rate; and returning and transmitting a transmission rate from a receiving direction to a transmitting side Or channel shield related information; adjust the current rate according to the above information related to the transmission rate or the amount of information; and send the next transmission frame from the transmitting direction to the receiver at the adjusted current rate.

Preferably, the step of returning information related to the transmission rate or the channel quality includes: returning, by the returning frame corresponding to the foregoing transmission frame, information related to the transmission rate or the channel quality from the receiving direction.

Preferably, the one transmission frame sent by the receiving direction from the transmitting direction is an RTS frame; wherein, the step of returning information related to the transmission rate or the channel quality from the receiving direction to the transmitting side comprises: using the CTS frame corresponding to the RTS frame to return and Information about the transmission rate or channel shield.

Preferably, the one transmission frame sent by the receiving direction from the transmitting direction is a data frame; wherein, the step of returning information related to the transmission rate or the channel quality from the receiving direction to the transmitting side comprises: using an Ack frame corresponding to the data frame to return and Information about transmission rate or channel quality.

Preferably, the method for transmitting data in the WLAN further includes: repeating the step of returning the information related to the transmission rate or the channel quality, the step of adjusting the current rate, and the step of transmitting the next sending frame until the end of the data transmission .

Preferably, the return frame is also transmitted at the current rate.

Preferably, the transmission rate is divided into a plurality of levels VI ~ VP, where VI is the base rate and VP is the highest rate.

Preferably, the current rate is set to the base rate when a transmission is initiated.

Preferably, at the start of a transmission, the current rate according to the statistical information of the channel quality is set to a rate higher than the basic rate.

Preferably, the foregoing information about the transmission rate or the channel quality includes: information indicating one of the V1 to VP multi-level transmission rates; the step of adjusting the current rate includes: indicating according to the foregoing information related to the transmission rate or the channel quality. The rate level adjusts the current rate.

Preferably, the foregoing information about the transmission rate or the channel quality includes: indicating a signal to noise ratio, Information of one or more of signal strength, bit error rate, symbol error rate, and frame error rate.

Preferably, each of the transmitting frames sent from the transmitting direction includes: a step of setting a duration for the transmitting frame.

Preferably, the step of setting a duration for the sending frame comprises: calculating the sending according to a time taken to transmit a return frame corresponding to the sending frame, a next sending frame, and a return frame corresponding to the next sending frame at a current rate. The duration of the frame; and setting the calculated duration of the transmitted frame in the duration field of the transmitted frame.

Preferably, returning each return frame from the receiving direction to the sender includes: a step of setting a duration for the return frame.

Preferably, the step of setting a duration for the return frame comprises: calculating a frame length of the next transmission frame according to the received duration of the transmission frame corresponding to the return frame, a current rate, and a frame length of the return frame; The duration of the return frame, the duration of the return frame corresponding to the time taken to transmit the next received frame and the corresponding return frame according to the adjusted transmission rate; and setting the calculated duration of the returned frame at The return frame is in the duration field.

Preferably, the method for transmitting data in the wireless local area network further comprises: other nodes not participating in the communication maintaining the network allocation vector according to the duration in the sending frame and the returning frame.

Preferably, the step of returning information related to the transmission rate or the channel quality includes: receiving the foregoing transmission frame; determining channel quality according to the reception result; selecting an optimal transmission rate according to the channel quality; and using the return corresponding to the foregoing transmission frame The frame returns information indicating the optimal transmission rate from the receiving side to the sender.

Preferably, the step of returning information related to a transmission rate or a channel shield includes: receiving the transmission frame; determining a channel quality according to the reception result; and returning from the receiving direction to the sender by using a return frame corresponding to the transmission frame Information indicating the quality of the channel.

Preferably, the step of adjusting the current rate includes: selecting an optimal transmission rate as the current rate according to the information of the channel shield in the returned frame. DRAWINGS

It is believed that the description of the specific embodiments of the present invention can be made more The above features, advantages and objects of the present invention are well understood.

1 is a flow chart showing a method of transmitting data in a wireless local area network according to an embodiment of the present invention;

2 is a detailed flow chart showing a method of transmitting data in a wireless local area network according to an embodiment of the present invention;

3A and 3B are diagrams for explaining a format of a physical frame of a return frame according to an embodiment of the present invention;

4 is a diagram for explaining a calculation duration and a maintenance network allocation vector (NAV) situation according to an embodiment of the present invention. detailed description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, various preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

A flow diagram of a method of transmitting data in a wireless local area network in accordance with one embodiment of the present invention is shown.

As shown in FIG. 1, in the method for transmitting data in the wireless local area network of this embodiment, first, in step 101, a transmission frame is transmitted from the transmitting direction to the receiving side at the current rate. Specifically, in the present application, a frame transmitted from a transmitting side to a receiving side is referred to as a "sending frame", and a frame returned from a receiving side to a transmitting side is referred to as a "returning frame". As is known to those skilled in the art, transmitting a frame in a wireless local area network (WLAN) may include: an RTS (Request To Send) frame, a data frame, etc.; respectively, corresponding to the transmitted frame, the return frame may include: CTS (Clear To Send) frame, ACK (acknowledgement) frame, etc.

Next, at step 105, the sender returns information related to the transmission rate or channel quality from the receiving side. Specifically, the receiving party may receive the transmission frame sent by the sender, evaluate the channel quality according to the result of the reception, and then determine an optimal transmission rate and return the information of the optimal transmission rate to the sender. Alternatively, the receiver may simply return the channel quality information to the sender, and then the sender determines the optimal transmission rate based on the channel shield.

Here, the present invention is not particularly limited as to how to evaluate the channel quality and how to determine the optimum transmission rate according to the channel quality, and any method known to those skilled in the art can be employed. Rear Some methods are exemplarily enumerated in the preferred embodiment of the invention described above, but the invention is not limited to the method.

Next, at step 110, the current rate is adjusted based on the returned information related to the transmission rate or channel quality. Specifically, corresponding to the step of returning information before, if the channel quality information is returned from the receiver, the sender further determines an optimal transmission rate according to the quality information to adjust the current rate; if the return from the receiver is The information indicating the optimal transmission rate is updated by the sender directly according to the information.

Then, in step 115, the next transmission frame is transmitted from the transmitting direction to the receiver at the adjusted current rate.

Thus, the method of transmitting data in the wireless local area network of the present embodiment can transmit data at different rates according to the channel state, thereby adapting to changes in channel quality due to movement or other reasons.

2 is a detailed flow chart showing a method of transmitting data in a wireless local area network in accordance with a preferred embodiment of the present invention. Preferred embodiments of the present invention will now be described with reference to the drawings.

As shown in Fig. 2, after starting a data transfer, first at step 205, the initial current rate is set. In this embodiment, the transmission rate is divided into, the transmission rate is divided into a plurality of levels VI ~ VP, where VI is the basic rate (lowest rate) and VP is the highest rate.

Here, the initial current rate can be set to the base rate VI. Preferably, if the sender has statistical information of the channel shield amount, a rate higher than the basic rate may be selected as the initial current rate according to the statistical information. However, the precondition is to fully guarantee that the first transmitted frame can be correctly transmitted at the initial current rate.

Next, in step 210, the RTS frame is transmitted from the transmitting direction to the receiver at the initial current rate. As is known to those skilled in the art, a data transfer is typically initiated in the WLAN, first by the sender sending an RTS frame as a request.

Next, in step 215, after receiving the RTS request, the receiver returns a CTS frame at the initial current rate. Specifically, the receiver receives the RTS frame sent by the sender, evaluates the channel quality according to the received result, and then determines an optimal transmission rate (for example, V5), and includes a representation in the CTS return frame returned to the sender. The information of the optimal transmission rate. here, In determining the optimal transmission rate, the characteristics of the transmitted data (eg, frame length, code rate, etc.) and channel shield characteristics (eg, signal-to-noise ratio, signal strength, bit error rate, symbol error rate, etc.) should be considered. ) to determine an optimal transmission rate.

In addition, in the preferred solution, the sender determines that the rate should be strictly enforced by the sender, otherwise the receiver's reservation time for the channel is not accurate, and it is difficult to avoid collision.

Here, the joint diagrams 3A and 3B illustrate a specific manner in which the optimum transmission rate information is returned to the sender in accordance with a preferred embodiment of the present invention. According to the preferred embodiment, the optimal transmission rate information is included in the physical frame header of the return frame and returned to the sender. 3A and 3B are diagrams for explaining the format of a physical frame of a return frame according to an embodiment of the present invention.

The structure of the current 802.11a physical layer frame is as shown in FIG. 3A, wherein the "RATE" field indicates the transmission rate of the physical layer frame "DATA" (data portion), and the "SERVICE" field is 16 bits, wherein 7 bits indicate scrambling generation. Polynomial, the remaining 9 bits are reserved. According to the preferred embodiment, 4 bits out of the reserved 9 bits are named "rRATE" field to indicate the above optimum transmission rate information (see Fig. 3B).

Next, at step 220, the sender adjusts the current rate (e.g., V5) based on the optimal transmission rate information in the CTS frame.

Next, in step 225, a data frame is transmitted from the transmitting direction to the receiver at the adjusted current rate.

Next, at step 230, the sender returns an Ack frame from the receiving direction at the adjusted current rate. As with the aforementioned step 215, the receiver receives the data frame sent by the sender, evaluates the channel quality based on the received result, and then determines an optimal transmission rate, and includes the representation in the Ack return frame returned to the sender. The information of the optimal transmission rate. Similarly, the characteristics of the transmitted data (eg, frame length, code rate, etc.) and channel quality characteristics (eg, signal-to-noise ratio, signal strength, bit error rate, missymbol) should be considered together when determining the optimal transmission rate. Rate, etc.) to determine an optimal transfer rate.

Next, at step 235, it is determined whether there are still data frames to be transmitted. If the determination is "Yes", proceed to step 240, according to the optimal transmission rate information in the Ack frame, the sender adjusts the current rate (same as the aforementioned step 220); then, returns to step 225 to repeat the steps. 225 - 240, until no data frames need to be sent.

If the decision at step 235 is "NO", then the process ends at step 245.

The manner in which the duration of the transmission frame and the return frame in the embodiment of the present invention and the manner in which other nodes participating in the data transmission maintain the network allocation vector (NAV) will be described below with reference to FIG.

As is known to those skilled in the art, in the conventional data communication of a wireless local area network, in order to reduce the loss of collision and the influence of hidden terminals, etc., the reserved time length information (RTS is 20 bytes) is stored in the RTS and CTS frames. CTS is 14 bytes). Other nodes that are not involved in data transmission receive the RTS/CTS frame, update the NAV (network allocation vector) value after obtaining the reserved duration information, and reserve the channel bandwidth for the data exchange between the sender and the receiver of the contention channel. , As shown in Figure 4.

This is feasible in the case where the transmission rate is constant in the past. However, if the method of the present invention is employed, since the transmission rate is varied, it is not sufficient to rely solely on the duration information of the RTS and CTS frames, which may result in inaccurate updating of NAV values of other nodes, resulting in wasted resources or increased collisions.

In accordance with a preferred embodiment of the present invention, the duration of the transmission frame is set when each of the transmission frames is transmitted from the transmitting direction (e.g., steps 105, 115 of Figure 1 and steps 210, 225 of Figure 2). Specifically, the duration of the transmission frame is first calculated based on the time taken to transmit the return frame corresponding to the transmission frame, the next transmission frame, and the return frame corresponding to the next transmission frame at the current rate. Then, the calculated duration of the transmission frame is set in the duration field (field) of the transmission frame.

For example, when calculating the duration of the RTS frame in step 210 of FIG. 2, it should calculate that the CTS return frame corresponding to the RTS and the next data transmission frame are transmitted at the initial current rate (the data frame to be transmitted in step 225). The time taken to return the frame corresponding to the next transmitted frame, of course, should also include the interval between these frames (SIFS).

For another example, when calculating the duration of the data transmission frame in step 225 of FIG. 2, it should calculate that the Ack return frame corresponding to the data transmission frame and the next data transmission frame are transmitted at the adjusted current rate (if any) Then, the next cycle performs the data frame processed in step 225) and The time taken by the Ack corresponding to the next transmitted frame to return the frame, of course, should also include the interval between these frames (SIFS).

Further, according to the preferred embodiment, the duration is set for the return frame when returning from the receiving direction to each of the return frames (e.g., in steps 215, 230 of Fig. 2). Specifically, first, the frame length of the next transmission frame is calculated according to the received duration of the transmission frame corresponding to the return frame, the current rate, and the frame length of the returned frame. Then, the duration of the return frame is calculated, the duration of the return frame corresponding to the time taken to transmit the next received frame and the corresponding return frame according to the transmission rate indicated by the information related to the transmission rate or channel quality. Finally, the calculated duration of the return frame is set in the duration field of the return frame.

For example, when calculating the duration of the CTS frame in step 215 of FIG. 2, first, the duration (D1) in the RTS frame transmitted according to step 210, the initial current rate (VI), and the frame length of the CTS frame (L1) The frame length (L2) of the next transmission frame (the frame to be transmitted in step 225) is calculated and can be calculated by the following formula: L2 = (D1 - 3 * SIFS) * V1 _ 2 * L1. When there are no subsequent data frames (can be known by the status of the More Frag field), L2=0. .

Then, calculating the duration of the CTS frame, the duration of the CTS frame corresponding to transmitting the next received frame (the data frame to be transmitted in step 225) and the corresponding return frame according to the adjusted current rate (step 230 is to return The time taken by the Ack frame) should of course also include the interval between these frames (SIFS).

In the meantime, according to the preferred embodiment, other nodes in the network that are not participating in the communication listen to each of the transmission frame and the return frame in the channel, and update the NAV value according to the duration recorded therein. In this way, even in the case of a change in the transmission rate, an accurate update of the NAV value of each node in the WLAN can be ensured, and further resources can be saved while avoiding collisions.

As can be seen from the above description, according to the above embodiment of the present invention, in the data transmission process, the transmission rate can be adaptively changed according to the channel state according to the physical frame segment, so that it can be applied to the high-speed mobile wireless fading channel.

The embodiment of the present invention adopts the exchange technology of rate information (or channel quality information), and the exchange of rate information and the exchange of channel quality information are equivalent, and the sender can efficiently connect The data is sent at a rate that the receiver can receive reliably.

The preferred embodiment of the present invention employs a rate setting method when the rate is variable, the method making the duration in the current segment have a reservation function for transmitting the next segment channel, and thus is suitable for segmentation transmission of data frames. .

According to the above embodiment of the present invention, since the transmission rate in the data frame transmitted by the sender and the transmission rate of the corresponding return frame are always equal, the transmission of the channel by the sender can be ensured, and the pair can be released in time at the end of the communication. The occupation of the channel.

Further, according to a modification of the present invention, the above-described optimum rate information may not be recorded in the physical frame header, but may be recorded in a MAC frame, for example, a "Frame Control" field.

According to another variant of the invention, the information contained in the return frame is not the optimum rate information but one or more of the signal to noise ratio, the signal strength, the bit error rate, the symbol error rate and the frame error rate. For example, a combination of one or more of signal to noise ratio, signal strength, bit error rate, symbol error rate, and frame error rate may be hierarchically defined and then returned to the sender via a return frame. In this way, the sender can select the optimum transmission rate based on the characteristics of the channel quality and the characteristics of the data to be transmitted.

Although the method for transmitting data in the wireless local area network of the present invention has been described in detail through some exemplary embodiments, the above embodiments are not exhaustive, and those skilled in the art can implement the spirit and scope of the present invention. Various changes and modifications. Therefore, the invention is not limited to the embodiments, and the scope of the invention is only limited by the appended claims.

Claims

Rights request

A method for transmitting data in a wireless local area network, comprising:

Sending a transmission frame from the transmitting direction to the receiver at the current rate;

Returning, from the receiving direction, information related to the transmission rate or the channel shield amount; adjusting the current rate according to the above information related to the transmission rate or channel quality; and transmitting the next transmission from the transmitting direction to the receiving side at the adjusted current rate frame.

The method for transmitting data in a wireless local area network according to claim 1, wherein the step of returning information related to a transmission rate or a channel quality comprises: transmitting, by using a return frame corresponding to the foregoing transmission frame, from a receiving direction The party returns information related to the transmission rate or channel quality.

The method for transmitting data in a wireless local area network according to claim 1, wherein a transmission frame sent by the receiver from the transmitting direction is an RTS frame;

The step of returning information related to the transmission rate or channel quality from the receiving side to the transmitting side includes: returning information related to the transmission rate or channel quality using the CTS frame corresponding to the RTS frame.

The method for transmitting data in a wireless local area network according to claim 1, wherein one of the transmission frames sent from the transmitting direction to the receiving side is a data frame;

The step of returning information related to the transmission rate or the channel quality from the receiving side to the transmitting side includes: returning information related to the transmission rate or the channel quality by using the Ack frame corresponding to the above data frame.

The method for transmitting data in a wireless local area network according to any one of claims 1 to 4, further comprising:

The above steps of returning information related to the transmission rate or channel quality, the step of adjusting the current rate, and the step of transmitting the next transmission frame are repeatedly performed until the end of the data transmission.

6. The method of transmitting data in a wireless local area network according to claim 2, wherein said return frame is also transmitted at a current rate.

7. The data transmission in a wireless local area network according to any one of claims 1 to 6. The method, wherein the transmission rate is divided into multiple levels VI ~ VP, where VI is the basic rate and VP is the highest rate.

8. The method of transmitting data in a wireless local area network according to claim 7, wherein the current rate is set to a base rate when a transmission is started.

9. The method of transmitting data in a wireless local area network according to claim 7, wherein, at the time of starting a transmission, the current rate of the statistical information according to the channel shield is set to a rate higher than the basic rate.

The method for transmitting data in a wireless local area network according to claim 7, wherein the information related to the transmission rate or the channel quality comprises: information indicating one of VI to VP multi-level transmission rates;

The step of adjusting the current rate includes: adjusting the current rate according to the rate level indicated by the information about the transmission rate or the channel quality.

The method for transmitting data in a wireless local area network according to claim 1, wherein the information about the transmission rate or the channel quality comprises: a signal to noise ratio, a signal strength, a bit error rate, a symbol error rate, and a frame error rate. Information about one or more of them.

The method for transmitting data in a wireless local area network according to any one of claims 1 to 11, wherein, when transmitting each of the transmission frames from the transmitting direction, the receiving unit includes: a step of setting a duration for the transmitting frame.

13. The method of transmitting data in a wireless local area network according to claim 12, wherein the step of setting a duration for the transmission frame comprises:

Calculating the duration of the transmission frame according to the time taken to transmit the return frame corresponding to the transmission frame, the next transmission frame, and the return frame corresponding to the next transmission frame at the current rate;

The calculated duration of the transmitted frame is set in the duration field of the transmitted frame.

14. The method of transmitting data in a wireless local area network according to claim 13, wherein the returning from the receiving direction to each of the return frames includes: a step of setting a duration for the return frame.

15. The method of transmitting data in a wireless local area network according to claim 14, wherein the step of setting a duration for the return frame comprises: Calculating a frame length of the next transmission frame according to the received duration of the transmission frame corresponding to the return frame, the current rate, and the frame length of the returned frame;

Calculating a duration of the return frame, the duration of the return frame corresponding to the time taken to transmit the next received frame and the corresponding return frame according to the adjusted transmission rate;

The calculated duration of the return frame is set in the duration field of the return frame.

16. The method of transmitting data in a wireless local area network according to claim 15, further comprising: other nodes not participating in the communication updating the network allocation vector in real time according to the duration in the transmitting frame and the returning frame.

The method for transmitting data in a wireless local area network according to claim 1, wherein the step of returning information related to a transmission rate or channel quality comprises:

Receiving the above transmitted frame;

Judging the channel quality based on the reception result;

Select the optimal transmission rate based on channel quality;

The returning frame corresponding to the above-mentioned transmission frame is used to return information indicating the optimum transmission rate from the receiving side to the transmitting side.

The method for transmitting data in a wireless local area network according to claim 1, wherein the step of returning information related to a transmission rate or a channel quality comprises:

Receiving the above transmitted frame;

Determining the channel quality based on the reception result;

The returning frame corresponding to the above-mentioned transmission frame returns information indicating the channel quality from the receiving side to the transmitting side.

The method for transmitting data in a wireless local area network according to claim 18, wherein the step of adjusting the current rate comprises:

The optimal transmission rate is selected as the current rate based on the information of the channel quality in the returned frame.