Patent Publication Number: US-2017374682-A1

Title: Data Transmission Method and Station

Description:
TECHNICAL FIELD 
     The present disclosure relates to, but is not limited to, a Wireless Local Area Network (WLAN) technology. 
     BACKGROUND 
     At present, WLAN-based data communications have become very common, and global demands for WLAN coverage are increasing. The industrial specification group of the Institute of Electrical and Electronic Engineers (IEEE802.11) defines a series of standards such as 802.11a/b/g/n/ac in sequence to meet increasing communication demands, where a dynamic channel detection threshold, serving as an alternative technology for improving the channel multiplexing rate and solving the network efficiency, draws wide attention and research. 
     In common WLANs, a Basic Service Set (BSS) may be constituted by an Access Point (AP) and multiple Stations (STAs) associated therewith. At present, 802.11 supports two clear channel determination methods, namely physical carrier detection and virtual carrier detection, and after both the physical carrier detection and the virtual carrier detection determine a clear channel, allocated STAs can compete for sending. Herein, the physical carrier detection refers to a Clear Channel Assessment (CCA) channel detection technology, namely, the associated STAs perform detection through a signal strength over a medium, and determine whether a channel is busy or clear in combination with a CCA threshold value. Usually, the CCA threshold value is fixedly set according to receiving sensitivity under a minimum modulation coding rate to ensure a maximum receiving coverage range. The virtual carrier detection refers to as that when a third-party associated STA except two communication parties receives a radio frame whose receiving address is not the a third-party associated STA, a local Network Allocation Vector (NAV) value is set according to a value of a duration field in the radio frame, herein the NAV is a counter, and when the NAV is not zero, it is considered that the channel is busy and the a third-party associated STA does not compete for sending. 
     All the time, the CCA channel detection technology adopts a fixed threshold value as a standard for determining whether a channel is busy or clear. Thus, in some scenarios, channel access opportunities are reduced. As shown in  FIG. 1 , an STA 1  is associated with an AP 1 , and an STA 2  is associated with an AP 2 . In  FIG. 1 , a solid single-arrow line represents that a radio frame is sent to a target receiving STA, and a dashed single-arrow line represents that a radio frame signal reaches a third-party STA. Although the STA 1  and the STA 2  can successfully send data to respective APs, when the STA 1  sends a radio frame to the AP 1 , due to a conservative CCA threshold value (i.e., −82 dBm), the signal strength of the STA 1  monitored by the STA 2  is −70 dBm, which is greater than the CCA threshold (−82 dBm), and the STA 2  considers that the channel is busy. However, actually, a signal sent to the AP 2  by the STA 2  cannot cause inference on receiving of the AP 1  due to the fact that the strength of the signal from the STA 2  reaching the AP 1  is much lower than the strength of the signal from the STA 1  reaching the AP 1 , and the AP 2  can successfully receive the signal of the STA 2 . However, under this scenario, it is impossible for the STA 2  to send a radio frame to the AP 2 , so multiplexing transmission is held back, that is to say, a too low CCA threshold reduces the sending opportunity of the STA 2 . 
     For the above situation, a concept of Dynamic Sensitivity Control (DSC)/dynamic channel detection is provided in a current discussion. That is, a channel detection threshold of an STA is no longer a fixed value, but an own channel detection threshold of an STA is dynamically adjusted according to a Received Signal Strength Indicator (RSSI) of a beacon frame of an AP. In another word, if the STA is closer to the AP, the channel detection threshold is greater, thus shielding a signal lower than a detection threshold, to improve the channel access efficiency of the STA. As shown in  FIG. 1 , before the STA 1  sends data to the AP 1 , it is detected that a signal RSSI currently sent by the STA 2  is −70 dB, and the channel detection threshold is greater than −70 dB after the STA 1  performs DSC. Therefore, the STA 1  ignores the signal of the STA 2 , to access a channel and transmit data to the AP 1 . 
     However, when an STA adjusts a CCA detection threshold by means of DSC (here, the STA is also referred to as a DSC STA) to improve a channel access opportunity, a probability of collision with other equipment will certainly be increased. Particularly, when an STA out of a range that can be detected by the DSC STA is using a channel, the STA cannot be listened by the DSC STA, and if the DSC STA uses the channel at this time, data transmission of the STA may be interfered, and when the distance therebetween is smaller, the possibility of being interfered will be larger. When there are more similar STAs, the probability of collision will be larger, thus reducing the reliability of current transmission in the data transmission of the dynamic channel detection. 
     SUMMARY 
     The following is a summary of a subject described herein in detail. The summary is not intended to limit the scope of protection of claims. 
     The present document provides a data transmission method and an STA, capable of improving a multiplexing transmission opportunity in data transmission of dynamic channel detection and ensuring the reliability of current transmission. 
     A data transmission method includes: a source STA has data to be sent, and detects, in a back-off process, that a radio channel is busy and a physical frame header part of a radio frame is successfully received; 
     the source STA determines that a medium currently carrying wireless transmission can be multiplexed according to receiver Identification (ID) information carried in the received physical frame header part of the radio frame, and the source STA competes for a multiplexing transmission opportunity; and 
     the source STA sends a radio frame to a destination STA after acquiring the multiplexing transmission opportunity. 
     In an exemplary embodiment, the receiver ID information includes one or more pieces of the following information: a BSS color, a Basic Service Set Identification (BSSID), an Association ID (AID), part of the BSSID and part of the AID. 
     In an exemplary embodiment, that the source STA sends the radio frame to a destination STA includes: 
     the source STA sends a multiplexing transmission request to the destination STA, and sends the radio frame carrying data to the destination STA after correctly receiving a multiplexing transmission response frame from the destination STA; 
     or, the source STA directly sends the radio frame carrying data to the destination STA. 
     In an exemplary embodiment, before a source STA has data to be sent, and detects, in a back-off process, that a radio channel is busy and a physical frame header part of a radio frame is successfully received, the method further includes: the source STA monitors and parses a received radio frame, and records a sender ID and/or sender address of the monitored radio frame in a surrounding STA information list of the source STA. 
     In an exemplary embodiment, that the source STA monitors and parses a received radio frame and records a sender ID and/or sender address of the monitored radio frame in a surrounding STA information list of the source STA includes: 
     the source STA monitors and parses a received Request to Send (RTS) frame, and identifies, according to the received RTS frame, an ID and/or address of a corresponding STA that sends the RTS frame, and an ID and/or address of an STA that receives the RTS frame. 
     In an exemplary embodiment, after the source STA monitors and parses a received RTS frame, and identifies, according to the received RTS frame, an ID and/or address of a corresponding STA that sends the RTS frame, and an ID and/or address of an STA that receives the RTS frame, the method further includes: recording a sender ID and/or sender address allowed to send a Clear To Send (CTS) radio frame and corresponding to the monitored RTS frame. 
     In an exemplary embodiment, before recording a sender ID and/or sender address allowed to send a CTS radio frame and corresponding to the monitored RTS frame, the method further includes: 
     the source STA acquires a sending power of the monitored CTS frame, and a reaching power of the monitored CTS frame reaching the source STA, and the acquired reaching power is greater than a preset threshold. 
     In an exemplary embodiment, before recording a sender ID and/or sender address of the monitored radio frame, the method further includes: 
     the source STA acquires a sending power of a sender of the monitored radio frame, and a reaching power of the monitored radio frame reaching the source STA, and the acquired reaching power is greater than a preset threshold. 
     In an exemplary embodiment, the source STA acquires a transmission time length of the radio frame by decoding the received physical frame header of the radio frame. 
     In an exemplary embodiment, transmission multiplexing transmission time length of the source STA does not exceed a transmission ending time point of the acquired radio frame. 
     In an exemplary embodiment, that the source STA determines that a medium currently carrying wireless transmission can be multiplexed according to receiver ID information carried in the received physical frame header part of the radio frame includes: 
     the source STA detects that a target receiving STA of the radio frame currently transmitted is not in the surrounding STA information list of the source STA. 
     In an exemplary embodiment, a multiplexing transmission request frame carries an ID and/or sender address of the target receiving STA carrying the radio frame currently transmitted. 
     In an exemplary embodiment, that the source STA competes for a multiplexing transmission opportunity includes: 
     the source STA performs back-off by using a dynamic CCA threshold, and acquires the multiplexing transmission opportunity after back-off is ended; 
     or, the source STA acquires the multiplexing transmission opportunity after a random time length. 
     In an exemplary embodiment, before the source STA starts to compete for the multiplexing transmission opportunity, a local channel appointment timer of the source STA is 0. 
     A data transmission method includes: 
     a destination STA receives a multiplexing transmission request; and the destination STA detects that a medium currently carrying wireless transmission can be multiplexed, and returns a multiplexing transmission response frame to a source STA. 
     In an exemplary embodiment, before a destination STA receives a multiplexing transmission request, the method further includes: the destination STA monitors and parses a received radio frame, and records a sender ID and/or sender address of the monitored radio frame in a surrounding STA information list of the destination STA. 
     In an exemplary embodiment, before recording a sender ID and/or sender address of the monitored radio frame, the method further includes: 
     the destination STA acquires a sending power of a sender of the monitored radio frame, and a reaching power of the monitored radio frame reaching the destination STA, and the acquired reaching power is greater than a preset threshold. 
     In an exemplary embodiment, that the destination STA detects that a medium currently carrying wireless transmission can be multiplexed includes: 
     the destination STA detects that a target receiving STA of the radio frame currently transmitted is not in the surrounding STA information list of the destination STA. 
     An STA includes: a recording module, a first determination module and a transmission module. 
     The recording module is configured to, in a back-off process, detect that a radio channel is busy and a physical frame header part of a radio frame is successfully received when there are data to be sent. 
     The first determination module is configured to: determine that a medium currently carrying wireless transmission can be multiplexed according to receiver ID information carried in the received physical frame header part of the radio frame, compete for a multiplexing transmission opportunity, and notify the transmission module when acquiring the multiplexing transmission opportunity. 
     The transmission module is configured to receive a notification from the first determination module, and send a radio frame to a destination STA. 
     In an exemplary embodiment, the first determination module is configured to send a multiplexing transmission request to the destination STA, and notify the transmission module after correctly receiving a multiplexing transmission response frame from the destination STA; and 
     the STA further includes: a second determination module, configured to receive a multiplexing transmission request frame from the source STA, detect that the medium currently carrying the wireless transmission can be multiplexed, and return the multiplexing transmission response frame to the source STA. 
     In an exemplary embodiment, the recording module is configured to parse the received radio frame, and record a sender ID and/or sender address of the monitored radio frame in a surrounding STA information list. 
     In an exemplary embodiment, the recording module is further configured to acquire a sending power of a sender of the monitored radio frame, and a reaching power of the monitored radio frame reaching the source STA, and the acquired reaching power is greater than a preset threshold. 
     In an exemplary embodiment, the first determination module is configured to detect that the medium currently carrying the wireless transmission can be multiplexed when detecting that a target receiving STA of the radio frame currently transmitted is not in the surrounding STA information list of the source STA. 
     In an exemplary embodiment, the second determination module is configured to return the multiplexing transmission response frame to the source STA when detecting that a target receiving STA of the radio frame currently transmitted is not in the surrounding STA information list of the source STA. 
     A computer-readable storage medium stores a computer-executable instruction, and the computer-executable instruction is used for executing any one of the above methods. 
     Compared with the existing art, the technical solution in the present disclosure includes: a source STA has data to be sent, and detects, in a back-off process, that a radio channel is busy and a physical frame header part of a radio frame is successfully received; the source STA determines that a medium currently carrying wireless transmission can be multiplexed according to receiver ID information carried in the received physical frame header part of the radio frame, and the source STA competes for a multiplexing transmission opportunity; and the source STA sends a radio frame to a destination STA after acquiring the multiplexing transmission opportunity. According to the embodiments of the present disclosure, in data transmission of dynamic channel detection, two parties for a multiplexing transmission respectively determine whether the medium currently carrying the wireless transmission can be multiplexed, and when detecting that the medium currently carrying the wireless transmission can be multiplexed, the multiplexing transmission will be performed. Thus, on one hand, the multiplexing transmission opportunity is improved, and on the other hand, the reliability of current transmission is ensured. 
     After the drawings and the detailed descriptions are read and understood, other aspects can be understood. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram of an example for a channel detection threshold situation in the related art. 
         FIG. 2  is a flowchart of a data transmission method according to an embodiment of the present disclosure. 
         FIG. 3  is a structure diagram of an STA according to an embodiment of the present disclosure. 
         FIG. 4  is a diagram of an example for data transmission according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments of the present disclosure will be illustrated hereinbelow with the drawings in detail. It is important to note that embodiments in the present disclosure and characteristics in the embodiments may be mutually combined under the condition of no conflicts. 
       FIG. 2  is a flowchart of a data transmission method according to an embodiment of the present disclosure. As shown in  FIG. 2 , the method at least includes the steps as follows. 
     In step  200 , a source STA has data to be sent, and detects, in a back-off process, that a radio channel is busy and the source STA successfully receives a physical frame header part of a radio frame. 
     In step  201 , the source STA determines that a medium currently carrying wireless transmission can be multiplexed according to receiver ID information carried in the received physical frame header part of the radio frame, and the source STA competes for a multiplexing transmission opportunity. 
     The receiver ID information may include one or more pieces of the following information: a BSS color, a BSSID, an Association ID (AID), part of the BSSID and part of the AID and so on. 
     Before the step  200 , the method may further include: the source STA monitors and parses the received radio frame, and records sender information of the monitored radio frame, such as a sender ID and/or a sender address, in a surrounding STA information list of the source STA. 
     In an exemplary embodiment, before the source STA records a sender ID and/or sender address of the monitored radio frame, the method further includes: 
     the source STA acquires a sending power of the sender of the monitored radio frame, and a reaching power of the monitored radio frame reaching the source STA, and determines that the acquired reaching power is greater than a preset threshold. 
     The surrounding STA information list at least includes: the sender ID and/or sender address of the monitored radio frame, and may further include: the sending power of the sender of the monitored radio frame, the reaching power of the monitored radio frame reaching the local source STA, and the like, herein these parameters are in one-to-one correspondence to the sender ID and/or sender address of the monitored radio frame. 
     It is important to note that every time the source STA receives a radio frame, it is indicated that a sender of the radio frame is around the source STA. The source STA can receive the radio frame that is sent by the sender of the radio frame only when the sender of the radio frame is around the source STA. 
     In another embodiment, that the source STA monitors and parses the received radio frame and records the sender ID and/or sender address of the monitored radio frame in the surrounding STA information list of the source STA includes: 
     the source STA monitors and parses a received RTS frame, and identifies, according to the received RTS frame, an ID and/or address of a corresponding STA that sends the RTS frame, and an ID and/or address of an STA that receives the RTS frame. 
     In addition, the source STA records a sender ID and/or sender address allowed to send a CTS radio frame and corresponding to the monitored RTS frame. 
     Herein, before recording a sender ID and/or sender address allowed to send a CTS radio frame and corresponding to the monitored RTS frame, the method further includes: 
     the source STA acquires a sending power of the monitored CTS frame, and a reaching power of the monitored CTS frame reaching the source STA, and the acquired reaching power is greater than a preset threshold. 
     That the source STA detects that a medium currently carrying wireless transmission can be multiplexed in the step includes: 
     the source STA detects that a target receiving STA of the radio frame currently transmitted is not in the surrounding STA information list of the source STA, and detects that the medium currently carrying the wireless transmission can be multiplexed. A multiplexing transmission request frame carries an ID and/or sender address of the target receiving STA carrying the radio frame currently transmitted. 
     Herein, the source STA can compete for the multiplexing transmission opportunity by means of a competition back-off process. For example, back-off is performed by using a dynamic CCA threshold, and the multiplexing transmission opportunity is acquired after back-off is ended. Or, the source STA may acquire the multiplexing transmission opportunity after a random time length, herein the random time length may be zero. 
     Before the source STA competes for the multiplexing transmission opportunity, a local channel appointment timer of the source STA is 0. 
     In step  202 , the source STA sends a radio frame to a destination STA after acquiring the multiplexing transmission opportunity. 
     The step includes: the source STA sends a multiplexing transmission request to the destination STA, and sends the radio frame carrying data to the destination STA after correctly receiving a multiplexing transmission response frame from the destination STA; 
     or, the source STA directly sends the radio frame carrying data to the destination STA. 
     The source STA acquires a transmission time length of the radio frame by decoding the received physical frame header of the radio frame. The multiplexing transmission time length of the source STA does not exceed a transmission ending time point of the acquired radio frame. 
     The method in the embodiments of the present disclosure further includes: 
     a destination STA receives a multiplexing transmission request; and 
     the destination STA detects that a medium currently carrying wireless transmission can be multiplexed, and returns a multiplexing transmission response frame to a source STA. 
     Before a destination STA receives a multiplexing transmission request, the method further includes: the destination STA monitors and parses a received radio frame, and records a sender ID and/or sender address of the monitored radio frame in a surrounding STA information list of the destination STA. 
     Before the destination STA records a sender ID and/or sender address for the monitored radio frame, the method further includes: 
     the destination STA acquires a sending power of a sender of the monitored radio frame, and a reaching power of the monitored radio frame reaching the destination STA, and the acquired reaching power is greater than a preset threshold. 
     That the destination STA detects that a medium currently carrying wireless transmission can be multiplexed in the step includes: 
     the destination STA detects that a target receiving STA of the radio frame currently transmitted is not in the surrounding STA information list of the destination STA. 
     If the destination STA is interfered by the radio frame currently received and cannot monitor a multiplexing transmission request frame from the source STA, multiplexing transmission fails to be established, and the flow is ended. 
     A sender carries sending power information in a service field of the sent radio frame. 
       FIG. 3  is a structure diagram of an STA according to an embodiment of the present disclosure. As shown in  FIG. 3 , the STA at least includes: a recording module  31 , a first determination module  32  and a transmission module  33 . 
     The recording module  31  is configured to, when there are data to be sent, in a back-off process detect that a radio channel is busy and a physical frame header part of a radio frame is successfully received. 
     The first determination module  32  is configured to, determine that a medium currently carrying wireless transmission can be multiplexed according to receiver ID information carried in the received physical frame header part of the radio frame, compete for a multiplexing transmission opportunity, and notify the transmission module when acquiring the multiplexing transmission opportunity. 
     The transmission module  33  is configured to receive a notification from the first determination module, and send a radio frame to a destination STA. 
     The recording module  31 , the first determination module  32  and the transmission module  33  are modules of the STA serving as a source STA. 
     The first determination module  32  is configured to send a multiplexing transmission request to the destination STA, and notify the transmission module after correctly receiving a multiplexing transmission response frame from the destination STA. 
     The STA in the embodiments of the present disclosure further includes: a second determination module  34 , configured to, receive a multiplexing transmission request frame from the source STA, detect that the medium currently carrying the wireless transmission can be multiplexed, and return the multiplexing transmission response frame to the source STA. 
     The second determination module  34  is a module of the STA serving as a destination STA. 
     Herein, 
     the recording module  31  is configured to parse the received radio frame, and record a sender ID and/or sender address of the monitored radio frame in a surrounding STA information list of itself. 
     The recording module  31  is further configured to acquire a sending power of a sender of the monitored radio frame, and a reaching power of the monitored radio frame reaching the source STA, and the acquired reaching power is greater than a preset threshold. 
     Herein, the first determination module  32  is configured to detect that the medium currently carrying the wireless transmission can be multiplexed when detecting that a target receiving STA of the radio frame currently transmitted is not in the surrounding STA information list of the source STA. 
     The second determination module  34  is configured to return the multiplexing transmission response frame to the source STA when detecting that a target receiving STA of the radio frame currently transmitted is not in the surrounding STA information list of the destination STA. 
     In a first embodiment and in combination with  FIG. 4 , it is supposed that an STA S 1  and an STA D 1  are a first STA  1  and a destination STA  1  which are currently transmitting DATA 1  (data  1 ), and an STA S 2  and an STA D 2  are a first STA  2  and a destination STA  2  which are competing for multiplexing, and the S 2  is performing a back-off process. Herein, the S 2  and the D 2  collect their surrounding STA addresses and establish surrounding STA information lists respectively. In the first embodiment, if the D 1  is not in the surrounding STA list of the S 2 , that is to say, the S 2  supposes that it is far away from the D 1 , then the S 2  will suspend the current back-off process and start to attempt multiplexing transmission. 
     When the S 1  transmits the DATA 1  to the D 1 , the S 2  discovers that a receiving STA of DATA 1 , namely the D 1 , is not in the surrounding STA information list of S 2  after parsing a preamble of the DATA 1 , and then the S 2  starts to perform back-off by using a dynamic CCA threshold after acquiring the transmission time length of DATA 1 , and sends a multiplexing transmission request frame to the D 2  after back-off is ended. 
     Here, it is important to note that if the DATA 1  power received by the S 2  is greater than the dynamic CCA threshold, back-off is not performed, and the flow is ended. A local NAV may be updated according to the transmission time length of the radio frame in the existing art. 
     The multiplexing transmission request frame carries information about the D 1 , such as address information of the D 1 . 
     As shown in  FIG. 4 , after receiving the multiplexing transmission request frame from the S 2 , the D 2  discovers that the D 1  is not in the surrounding STA information list of the D 2 , and returns a multiplexing transmission response frame to S 2 ; and after receiving the multiplexing transmission response frame from the D 2 , the S 2  sends DATA 2  to the D 2 , and the time length of communication with the D 2  does not exceed a transmission ending time point of the DATA 1 . 
     It is important to note that if the D 2  is interfered by the DATA 1  and cannot monitor the multiplexing transmission request frame, the present multiplexing transmission fails to be established, and the flow is ended. 
     In a second embodiment and in combination with  FIG. 4 , it is supposed that an STA S 1  and an STA D 1  are a first STA  1  and a destination STA  1  which are currently transmitting DATA 1 , and an STA S 2  and an STA D 2  are a first STA  2  and a destination STA  2  which are competing for multiplexing. Herein, the S 2  and the D 2  periodically collect their surrounding STA addresses according to preset time and respectively establish surrounding STA information lists, including parameters such as address information of surrounding STAs, a sending power and a reaching power and so on. In the present embodiment, it is supposed that multiplexing transmission parties namely the S 2  and the D 2  are not symmetric to current communication parties namely the S 1  and the D 1  in power. 
     When the S 1  transmits the DATA 1  to the D 1 , the S 2  discovers that a receiving STA of DATA 1 , namely the D 1 , is in the surrounding STA information list of the S 2  after parsing a preamble of the DATA 1 . At this time, if a reaching power of a signal, sent by the S 2 , reaching the D 1  is lower than a minimum demodulation threshold (−82 dBm), the S 2  starts to perform back-off by using a dynamic CCA threshold after acquiring a transmission time length of DATA 1 , and sends a multiplexing transmission request frame to the D 2  after back-off is ended. 
     Here, it is important to note that if the power of DATA 1  received by the S 2  is greater than the dynamic CCA threshold, back-off is not performed, and the flow is ended. A local NAV may be updated according to the transmission time length of a radio frame in the existing art. 
     The multiplexing transmission request frame carries information, such as address information of the D 1 , the sending power of the S 1 , the sending power of the S 2 , and the demodulation threshold of the S 2  and so on. 
     As shown in  FIG. 4 , after receiving the multiplexing transmission request frame from the S 2 , the D 2  discovers that the D 1  is in the surrounding STA information list of the D 2 , adjusts its own sending power according to the sending power of the S 2  and the demodulation threshold of the S 2  carried in the multiplexing transmission request frame, and returns a multiplexing transmission response frame if the adjusted sending power is lower than a preset threshold; and after receiving the multiplexing transmission response frame from the D 2 , the S 2  sends DATA 2  to the D 2 , and the time length of communication with the D 2  does not exceed a transmission ending time point of the DATA 1 . 
     It is important to note that if the D 2  is interfered by the DATA 1  and cannot monitor the multiplexing transmission request frame, the present multiplexing transmission fails to be established, and the flow is ended. 
     A third embodiment elaborates a multiplexing transmission process inside a BSS. When an AP transmits DATA 1  to an STA 1 , an STA 2 , an STA 3 , the AP and the STA 1  are located in the same BSS, and the STA 2  desires to transmit DATA 2  to the STA 3  by multiplexing transmission. If the STA 2  discovers that a receiving STA of DATA 1 , namely the STA 1 , is not in a surrounding STA information list of the STA 2  after parsing a preamble of the DATA 1 , the S 2  starts to perform back-off by using a dynamic CCA threshold after acquiring a transmission time length of DATA 1 , and sends a multiplexing transmission request frame to the D 2  after back-off is ended. 
     Here, it is important to note that if the power of DATA 1  received by the STA 2  is greater than the dynamic CCA threshold, back-off is not performed, and the flow is ended. A local NAV may be updated according to a transmission time length of a radio frame in the existing art. 
     The multiplexing transmission request frame carries information about the STA 1  such as address information of the STA 1 . 
     After receiving the multiplexing transmission request frame from the STA 2 , the STA 3  discovers that the STA 1  is not in the surrounding STA information list of the STA 3 , and returns a multiplexing transmission response frame to the STA 2 ; and after receiving the multiplexing transmission response frame from the STA 3 , the STA 2  sends DATA 2  to the STA 3 , and a time length of communication with the STA 3  does not exceed a transmission ending time point of the DATA 1 . 
     A fourth embodiment elaborates a multiplexing transmission process outside a BSS. When an AP 1  transmits DATA 1  to an STA 1 , an AP 2  discovers that a receiving STA of DATA 1 , namely the STA 1 , is not in an surrounding STA information list of the AP 2  after parsing a preamble of the DATA 1 , and then the AP 2  starts to perform back-off by using a dynamic CCA threshold after acquiring a transmission time length of DATA 1 , and sends a multiplexing transmission request frame to an STA 2  after back-off is ended. 
     Here, it is important to note that if the power of DATA 1  received by the AP 2  is greater than the dynamic CCA threshold, back-off is not performed, and the flow is ended. A local NAV may be updated according to a transmission time length of a radio frame in the existing art. 
     The multiplexing transmission request frame carries information about the STA 1  such as address information of the STA 1 . 
     After receiving the multiplexing transmission request frame from the STA 2 , an STA 3  discovers that the STA 1  is not in the surrounding STA information list of the STA 3 , and returns a multiplexing transmission response frame to the STA 2 ; and after receiving the multiplexing transmission response frame from the STA 3 , the STA 2  sends DATA 2  to the STA 3 , and a time length of communication with the STA 3  does not exceed a transmission ending time point of the DATA 1 . 
     A fifth embodiment elaborates a process where a source STA performs multiplexing transmission with a next radio frame after receiving a radio frame currently transmitted. When an S 1  transmits DATA 1  to a D 1 , an S 2  discovers that a receiving STA of DATA 1 , namely the D 1 , is not in a surrounding STA information list of the S 2  after parsing a preamble of the DATA 1 , and DATA 1  transmission time length is not enough for the S 2  to send DATA 3  to an S 3 . But, the S 2  learns that the S 1  will send DATA 2  to the D 1  subsequently after parsing the DATA 1 , so the S 2  performs back-off by using a dynamic CCA threshold, and the STA S 2  parses a preamble in the DATA 2 , acquires a transmission time length of DATA 2 , and sends a multiplexing transmission request frame to the STA D 2  after back-off is ended. Back-off is performed by using the dynamic CCA threshold after the transmission time length of DATA 2  is acquired, and the multiplexing transmission request frame is sent to the STA D 2  after back-off is ended. 
     Here, it is important to note that if the power of DATA 2  received by the S 2  is greater than the dynamic CCA threshold, back-off is not performed, and the flow is ended. A local NAV may be updated according to a transmission time length of a radio frame in the existing art. 
     The multiplexing transmission request frame carries information about the D 1  such as address information of the D 1 . 
     After receiving the multiplexing transmission request frame from the S 2 , the D 2  discovers that the D 1  is not in the surrounding STA information list of the D 2 , and returns a multiplexing transmission response frame to the S 2 ; and after receiving the multiplexing transmission response frame from the D 2 , the S 2  sends DATA 3  to the D 2 , and a time length of communication with the D 2  does not exceed a transmission ending time point of the DATA 2 . 
     In a sixth embodiment, an S 2  and a D 2  collect their surrounding STA addresses and respectively establish surrounding STA information lists, including address information of surrounding STAs. In the collection process, both an S 1  and a D 1  have sent radio frames, and after receiving the radio frames sent by the S 1  and the D 1 , the S 2  and the D 2  discover that reaching powers are lower than a preset threshold, so address information of the S 2  and the D 2  is not recorded in the surrounding STA information lists. Then, the STA S 1  and the STA D 1  are a first STA  1  and a destination STA  1  which are currently transmitting DATA 1 , and the STA S 2  and the STA D 2  are a first STA  2  and a destination STA  2  which are competing for multiplexing. Herein, the S 2  and the D 2  periodically collect their surrounding STA addresses according to preset time and respectively establish surrounding STA information lists. In the first embodiment, if the D 1  is not in the surrounding STA list of the S 2 , that is to say, the S 2  considers that it is far away from the D 1 , the S 2  will start to attempt multiplexing transmission. 
     When the S 1  transmits DATA 1  to the D 1 , the S 2  discovers that a receiving STA of DATA 1 , namely the D 1 , is not in the surrounding STA information list of the S 2  after parsing a preamble of the DATA 1 , and the S 2  starts to perform back-off by using a dynamic CCA threshold after acquiring a transmission time length of DATA 1 , and sends a multiplexing transmission request frame to the D 2  after back-off is ended. 
     Here, it is important to note that if the power of DATA 1  received by the S 2  is greater than the dynamic CCA threshold, back-off is not performed, and the flow is ended. A local NAV may be updated according to a transmission time length of a radio frame in the existing art. 
     The multiplexing transmission request frame carries information about the D 1  such as address information of the D 1 . 
     As shown in  FIG. 4 , after receiving the multiplexing transmission request frame from the S 2 , the D 2  discovers that the D 1  is not in the surrounding STA information list of the D 2 , and returns a multiplexing transmission response frame; and after receiving the multiplexing transmission response frame from the D 2 , the S 2  sends DATA 2  to the D 2 , and a time length of communication with the D 2  does not exceed a transmission ending time point of the DATA 1 . 
     It is important to note that if the D 2  is interfered by the DATA 1  and cannot monitor the multiplexing transmission request frame, the present multiplexing transmission fails to be established, and the flow is ended. 
     In a seventh embodiment, to send data DATA 1  to an STA D 1  to compete for a channel sending opportunity first, an STA S 1  sends an RTS frame to the STA D 1 , and the STA D 1  returns a CTS frame to the STA S 1  after receiving the RTS frame. 
     An STA S 2  monitors the RTS frame and identifies addresses of the STA S 1  and the STA D 1  carried in the RTS frame. If a receiving power of the identified RTS frame is greater than a preset threshold, the STA S 2  records the STA S 1 . If the receiving power of the identified RTS frame is smaller than the preset threshold, the STA S 2  does not record the STA S 1 . 
     If the STA S 2  also monitors the CTS frame and a receiving power of the CTS frame is smaller than the preset threshold, the STA S 2  does not record the STA D 1 . If the receiving power of the CTS frame is greater than the preset threshold, the STA S 2  records the STA D 1 . 
     If the STA S 2  monitors only the CTS frame, no record is made. 
     If the STA S 2  monitors sending of a radio frame after monitoring the RTS frame for an interval of a 2*SIF+CTS frame, the STA S 2  determines whether to start a multiplexing transmission process according to received physical frame header information. 
     The multiplexing transmission process includes dynamic channel detection and back-off processes. 
     Those of ordinary skilled in the art may understand that all or some of the steps of the above-mentioned embodiment may be implemented by using a computer program flow. The computer program may be stored in a computer-readable storage medium. The computer program is executed on a corresponding hardware platform (such as system, equipment, device or apparatus or the like). During execution, the computer program includes one of the steps of the method embodiment or a combination thereof. 
     In an exemplary embodiment, all or some of the steps of the above-mentioned embodiment may also be implemented by using an integrated circuit. These steps may be manufactured into integrated circuit modules respectively, or a plurality of modules or steps therein are manufactured into a single integrated circuit module. 
     The device/functional module/functional unit in the above-mentioned embodiment may be implemented by using a general computation device. They may be centralized on a single computation device or may be distributed on a network composed of a plurality of computation devices. 
     When the device/functional module/functional unit in the above-mentioned embodiment is implemented in a form of a software function module and is sold or used as an independent product, they may also be stored in a computer-readable storage medium. The above-mentioned computer-readable storage medium may be a read-only memory, a magnetic disk or an optical disk or the like. 
     INDUSTRIAL APPLICABILITY 
     According to the embodiments of the present disclosure, in data transmission of dynamic channel detection, two parties for a multiplexing transmission respectively determine whether a medium currently carrying wireless transmission can be multiplexed, and when detecting that the medium currently carrying the wireless transmission can be multiplexed, the multiplexing transmission will be performed. Thus, on one hand, a multiplexing transmission opportunity is improved, and on the other hand, the reliability of current transmission is ensured.