Access method and device

Abstract

To provide a method for managing channel access to stations.SOLUTION: A method includes the steps of receiving a first frame including a field indicating information specifying an access method for a station from an access point (AP). The access method is a contention access method based on collision avoidance carrier detection multiple access or orthogonal frequency division multiple access, or orthogonal frequency division multiple access based on a scheduling access method. The method further includes the steps of: transmitting uplink multi-user transmission data by the station to the AP when a second frame carrying information about uplink transmission resources is received from the AP within an agreed period; and accessing, by the station, a channel using the contention access method based on CSMA / CA when the uplink multi-user transmission data is transmitted using uplink transmission resources or the second frame is not received within the agreed period.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] The present invention relates to the field of wireless communication technology, and in particular to an access method and device. [Background technology]

[0002] To solve the problem of WLAN Quality of Service (QoS), the Institute of Electrical and Electronics Engineers (IEEE) has introduced the IEEE 802.11e standard.

[0003] IEEE 802.11e extends the Distributed Coordination Function (DCF) channel access mechanism in the Media Access Control (MAC) layer of the original IEEE 802.11 to form Enhanced Distributed Channel Access (EDCA). EDCA extends the DCF mechanism to differentiate between the priorities of different service applications, guarantee channel access capability for high priority services, and guarantee some bandwidth for high priority services.

[0004] In the 802.11e protocol, there are four AC (Access Category) queues, including AC_BK (Background traffic), AC_BE (Best Effort traffic), AC_VI (Video traffic) and AC_VO (Voice Traffic), and different EDCA parameters may be set so that high priority AC queues have more transmission opportunities and smaller latency. In the protocol, an ACI (Access Category Index) is used to identify the aforementioned access categories. The queues are selected according to the priority carried in the data frames, thereby ensuring QoS in wireless local area network environments.

[0005] An Access Point (AP) may add information about an EDCA parameter set to a Beacon Frame, a Probe Response Frame, an Association Response Frame, or a Reassociation Response Frame, where the parameter set indicates parameters of an EDCA channel access method for different Access Categories, including AIFSN, ACM, ACI, ECWmin, ECWmax, and TXOP Limit.

[0006] A larger value of AIFSN (Arbitration InterFrame Spacing Number) indicates a longer idle wait time for the user.

[0007] ECWmin (Exponent form of CWmin) and ECWmax (Exponent form of CWmax) determine the average backoff time value, with larger values ​​of the two parameters indicating a longer average backoff time for the user.

[0008] TXOP Limit (Transmission Opportunity Limit) indicates the maximum duration for a user to occupy the channel after one successful contention. A larger value of TXOP Limit indicates a longer duration for a user to occupy the channel once. If the value is 0, only one packet can be transmitted each time after the channel is occupied, and the channel needs to be contended for again to transmit the packet again.

[0009] ACM (Admission Control Mandatory) indicates whether the access category requires admission control. If the bit is 0, the corresponding access category does not require admission control. If the bit is 1, admission control must be used before the access parameters of the access category can be used for transmission.

[0010] In current applications, the four EDCA parameter sets are configured by default to correspond to different queues separately, and each parameter set takes effect for the entire BSS (Basic Service Set), i.e., within a BSS, the QoS characteristics of all STAs are consistent, and when two STAs transmit data for the same queue, the STAs use the same EDCA parameters.

[0011] In existing applications, STAs can perform random access based on the time domain only on the main channel, and therefore the random access efficiency is relatively low. In uplink multi-user transmission, multiple stations can perform parallel random access simultaneously on multiple channels to improve random access efficiency. However, in this access scheme, multi-user transmission needs to be organized after the AP successfully acquires the channel through contention, and the probability of the AP successfully acquiring the channel through contention needs to be increased. Summary of the Invention

[0012] The embodiment of the present invention provides an access method and device, which allows multiple stations to perform parallel random access on multiple channels at the same time, and improves random access efficiency. In order to achieve the above objective, the following technical solutions are used in the embodiment of the present invention.

[0013] According to a first aspect, an embodiment of the present invention provides an access method, comprising: transmitting a first frame to an access point, the first frame carrying uplink transmission requirement information; transmitting uplink multi-user transmission data to the access point if a second frame carrying information about uplink transmission resources is received from the access point within the agreed period, the uplink multi-user transmission data being transmitted on the uplink transmission resources; or accessing the channel by the station in a contention access manner based on carrier sense CSMA / CA if the second frame is not received within the agreed period. Includes.

[0014] Referring to the first aspect, in a first implementation manner of the first aspect, the access method further includes the step of receiving a radio frame transmitted by an access point, the radio frame indicating a transmission time of a second frame (or may be called a target transmission time, i.e., a preset transmission time point of the second frame), and the radio frame being an association response frame, a beacon frame, or a response frame of the access point to the received data frame. Furthermore, the agreed-upon period may be obtained according to the transmission time point of the second frame.

[0015] According to a second aspect, an embodiment of the present invention provides an access method, comprising: receiving a wireless frame transmitted by an access point, the wireless frame indicating an access scheme for performing channel access, the wireless frame being an association response frame, a beacon frame or a response frame of the access point to the received data frame; transmitting uplink multi-user transmission data to the access point if a second frame carrying information about uplink transmission resources is received from the access point within the agreed period, the uplink multi-user transmission data being transmitted on the uplink transmission resources; or accessing the channel by the station in a contention access manner based on CSMA / CA if the second frame is not received within the agreed period. Includes.

[0016] Referring to the second aspect, in a first implementation scheme of the second aspect, the access scheme includes at least one of the following: a contention access scheme based on collision-avoidance carrier sense multiple access (CSMA / CA), a contention access scheme based on orthogonal frequency division multiple access (OFDMA), or a scheduling access scheme based on OFDMA.

[0017] With reference to the second aspect or the first implementation manner of the second aspect, in a second implementation manner of the second aspect, the second frame or the radio frame further includes indication information indicating the following, or the following is agreed upon in advance in the protocol: If the data frame carries a buffer status report BSR or does not contain an unfragmented data frame, the data frame is transmitted in the OFDMA contention access manner.

[0018] According to a third aspect, an embodiment of the present invention provides an access method, comprising: receiving a first frame from an access point, the first frame conveying information about uplink transmission resources; transmitting a second frame carrying uplink transmission requirement information to the access point and disabling a contention access scheme based on CSMA / CA or disabling a back-off timer; transmitting uplink multi-user transmission data to the access point if a third frame carrying information about uplink transmission resources is received from the access point within the agreed period, the uplink multi-user transmission data being transmitted on the uplink transmission resources; or accessing the channel by the station by enabling a contention access scheme based on CSMA / CA if the third frame is not received within the agreed period. Includes.

[0019] When there are many connected stations, many stations may participate in CSMA / CA contention and OFDMA contention. Therefore, the probability of collision between stations increases significantly, and the channel utilization rate decreases. Therefore, according to the access method provided in this embodiment of the present invention, the channel access mode can be managed, the system congestion can be reduced, and the channel utilization rate can be increased.

[0020] Optionally, in this embodiment of the present invention, the agreed period may be counted by using a timer, and the initial value of the timer is specified by the access point or agreed in the protocol. Furthermore, when the channel on which the uplink transmission resource is located is idle, the value of the timer is gradually decreased over time, or when the channel is busy, the gradually decreasing value of the timer is suspended. Furthermore, when the channel is busy, or a trigger frame carrying information about the uplink transmission resource is received, or a trigger frame for random access is received, or a trigger frame carrying a training sequence is received, the value of the timer is updated, and the manner of updating the value of the timer is to add a constant to the current value of the timer or to multiply the constant.

[0021] Optionally, the uplink transmission requirement information includes at least one of the following: packet inter-arrival time, packet size information, or traffic rate information.

[0022] Corresponding to the above method, the embodiment of the present invention further provides a corresponding method on the access point side.

[0023] According to a fourth aspect, an embodiment of the present invention provides an access method, comprising: receiving a first frame from a station, the first frame carrying uplink transmission requirement information; transmitting a second frame to the station, the second frame carrying information about uplink transmission resources; receiving uplink multi-user transmission data from the station, the uplink multi-user transmission data being transmitted on the uplink transmission resource; Includes.

[0024] According to a fifth aspect, an embodiment of the present invention provides an access method, comprising: transmitting a radio frame to the station, the radio frame indicating an access scheme for performing channel access (e.g., whether to use an OFDMA-based access scheme or whether to disable a CSMA / CA-based contention access scheme), the radio frame being an association response frame, a beacon frame, or an access point response frame to the received data frame; transmitting a second frame to the station, the second frame carrying information about uplink transmission resources; receiving uplink multi-user transmission data from the station, the uplink multi-user transmission data being transmitted on the uplink transmission resource; Includes.

[0025] In a fifth aspect, the access point may indicate an access scheme for performing channel access by using a radio frame according to the scenario information. For example, in a scenario of aggregated deployment (where the coverage areas of many stations or access points are heavily overlapped), the access point may instruct the station to disable the contention access scheme based on CSMA / CA. The access point may instruct the station to use the access scheme based on OFDMA. The contention collisions between stations can be reduced, and the throughput rate of the whole system can be improved. Otherwise, in a scenario with fewer stations, the access point may instruct the station to enable the contention access scheme based on CSMA / CA. The access point controls the access scheme of the station, and the system resources can be used efficiently.

[0026] According to a sixth aspect, an embodiment of the present invention provides an access method, comprising: transmitting a first frame to a station, the first frame carrying information about uplink transmission resources; receiving a second frame from the station, the second frame carrying uplink transmission requirement information; transmitting a third frame (such as a trigger frame) to the station carrying information about uplink transmission resources; receiving uplink multi-user transmission data from the station, the uplink multi-user transmission data being transmitted on the uplink transmission resource; Includes.

[0027] It should be noted that in the sixth aspect, the information about the uplink transmission resources in the third frame may further include identifiers of one or more stations using the uplink transmission resources.

[0028] Corresponding to the methods provided above, embodiments of the present invention further provide corresponding apparatuses.

[0029] According to a seventh aspect, an embodiment of the present invention provides an access device, comprising: a transmitting module configured to transmit a first frame carrying uplink transmission requirement information to an access point; a processing module configured to transmit uplink multi-user transmission data to the access point if a second frame carrying information about uplink transmission resources is received from the access point within the agreed period, and the uplink multi-user transmission data is transmitted on the uplink transmission resources or to access the channel by the station in a contention access manner based on carrier sense CSMA / CA if the second frame is not received within the agreed period; Includes.

[0030] According to an eighth aspect, an embodiment of the present invention provides an access device, comprising: a receiving module configured to receive a first frame from a station, the first frame carrying uplink transmission requirement information; a transmitting module configured to transmit a second frame to the station, the second frame carrying information about uplink transmission resources; The receiving module is further configured to receive uplink multi-user transmission data from the station, where the uplink multi-user transmission data is transmitted on the uplink transmission resource.

[0031] The transmission module is further configured to transmit the second frame to one or more stations, the second frame instructing the one or more stations to perform uplink multi-user transmission, the one or more stations including the station transmitting the first frame.

[0032] In the following, by using only the station side as an example, some devices corresponding to the method are provided. The devices on the access point side may be provided in a similar manner, and the details are not described here.

[0033] According to a ninth aspect, an embodiment of the present invention provides an access device, comprising: A receiving module configured to receive a wireless frame transmitted by an access point, the wireless frame indicating an access scheme for performing channel access, the wireless frame being an association response frame, a beacon frame, or a response frame of the access point to a received data frame; a processing module configured to transmit uplink multi-user transmission data to the access point if a second frame carrying information about uplink transmission resources is received from the access point within the agreed period, and the uplink multi-user transmission data is transmitted on the uplink transmission resources or to access the channel by the station in a contention access manner based on CSMA / CA if the second frame is not received within the agreed period; Includes.

[0034] According to a tenth aspect, an embodiment of the present invention provides an access device, comprising: a receiving module configured to receive a first frame from an access point, the first frame carrying information about uplink transmission resources; a transmitting module configured to transmit a second frame carrying uplink transmission requirement information to the access point; a processing module configured to disable a contention access scheme based on CSMA / CA or disable a back-off timer, and transmit uplink multi-user transmission data to the access point if a third frame carrying information about uplink transmission resources is received from the access point within the agreed period, the uplink multi-user transmission data being transmitted on the uplink transmission resources or to access the channel by the station by enabling the contention access scheme based on CSMA / CA if the third frame is not received within the agreed period; Includes.

[0035] Some technical features in the above-mentioned apparatus embodiments, such as timers, uplink transmission resources, trigger frames and radio frames, are similar to or correspond to some technical features in the above-mentioned method embodiments, and repeated descriptions will not be given here.

[0036] According to the embodiment of the present invention, it is possible as long as multiple stations can perform parallel random access on multiple channels at the same time, and random access efficiency is improved. There are two ways to increase the chance of an access point acquiring a channel. One is that the station delays contention or reduces the intensity with which the station contends for the channel; the other is that after acquiring a channel through contention, the station hands over control to the access point, and the access point sends a multi-user transmission trigger frame. [Brief description of the drawings]

[0037] The accompanying drawings, which are incorporated in and constitute a part of the specification, where like numerals refer to like components, illustrate embodiments of the invention and, together with the description, are intended to explain the principles of the invention. [Figure 1] 1 is a schematic flowchart of frame exchange for STA random access. [Diagram 2] 1 is a schematic diagram of the basic structure of an uplink random access packet. [Figure 3A] 1 is a schematic flowchart of frame exchange in scenario 1 according to an embodiment of the present invention. [Figure 3B] 11 is a schematic flowchart of another frame exchange in scenario 1 according to an embodiment of the present invention. [Figure 3C] 11 is a schematic flowchart of frame exchange in scenario 2 according to an embodiment of the present invention. [Figure 3D] 13 is a schematic flowchart of frame exchange in scenario 3 according to an embodiment of the present invention. [Figure 3E]13 is a schematic flowchart of frame exchange in scenario 4 according to an embodiment of the present invention. [Figure 3F] 11 is a schematic flowchart of frame exchange in scenario 5 according to an embodiment of the present invention. [Figure 3G-1] FIG. 1 is a schematic diagram of multiple transmission schemes operating together. [Figure 3G-2] FIG. 1 is a schematic diagram of multiple transmission schemes operating together. [Figure 4] 11 is a schematic flowchart of frame exchange in an access method according to Example 4 of the present invention. [Diagram 5] FIG. 2 is a schematic diagram of some situations in which a timer needs to be used; [Figure 5A] FIG. 4 is a schematic operational diagram of a first timer according to an embodiment of the present invention. [Figure 5B] FIG. 4 is a schematic operational diagram of a second timer according to an embodiment of the present invention. [Figure 5C] FIG. 11 is a schematic operational diagram of a third timer according to an embodiment of the present invention. [Figure 5D] FIG. 11 is a schematic operational diagram of a fourth timer according to an embodiment of the present invention. [Figure 6A] FIG. 1 is a first schematic diagram of transmitting a multi-user transmission trigger frame according to an embodiment of the present invention; [Figure 6B] FIG. 2 is a second schematic diagram of transmitting a multi-user transmission trigger frame according to an embodiment of the present invention; [Figure 6C] FIG. 3 is a third schematic diagram of transmitting a multi-user transmission trigger frame according to an embodiment of the present invention; [Figure 6D] FIG. 4 is a fourth schematic diagram of transmitting a multi-user transmission trigger frame according to an embodiment of the present invention. [Figure 7] 4 is a schematic flowchart of a frame exchange of a transmission mode conversion method according to an embodiment; [Figure 8] 1 illustrates an access device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Although the description is provided with reference to these embodiments, it will be understood that these embodiments are not used to limit the present invention to these embodiments. Instead, the present invention is intended to cover substitutes, modifications, and equivalents that may be included within the scope of the present invention as defined in the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are described in order to provide a thorough understanding of the present invention. However, it will be understood that in practical applications, these specific details of the present invention may not be included. Well-known methods, processes, components, and circuits have not been described in detail in other instances to avoid unnecessarily obscuring various aspects of the present invention.

[0039] In the IEEE802.11ax system, a station (STA) mainly performs uplink access using one of the following methods.

[0040] Method 1: A contention access method based on Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) Method 2: Contention-based access method based on Orthogonal Frequency Division Multiple Access (OFDMA) Scheme 3: OFDMA-based scheduling access scheme In the above-mentioned method 1, the STAs may simultaneously perform access by carrier sensing when the channel is idle. In the above-mentioned method 2, after receiving a trigger frame for random access (TFR) sent by the AP, the STAs may randomly select a resource block to perform access. In the above-mentioned method 3, after receiving a trigger frame sent by the AP, the STAs may perform data transmission on the corresponding channel according to the instruction of the trigger frame. To enable the AP to send the trigger frame to the STA, the STA needs to send a buffer size report (BSR) to the AP, and the BSR may be sent by the above-mentioned method 1, method 2, or other methods.

[0041] The OFDMA-based scheduling access scheme may also be realized by using other access schemes. For example, the STA may transmit a radio frame to the AP in scheme 1 or scheme 2, and the radio frame carries indication information used to indicate that the AP may transmit a trigger frame to trigger the STA to transmit uplink data (and may further trigger other STAs to transmit uplink data).

[0042] If each STA is allowed to perform data transmission in all three above mentioned schemes, when there are many STAs, many users may participate in CSMA / CA contention or OFDMA contention, the probability of collision between users increases significantly, and the channel utilization rate decreases. The embodiment of the present invention provides a channel access scheme management mechanism to reduce the congestion of the system and improve the channel utilization rate.

[0043] Example 1: Multi-user transmission framework When multiple users perform random access, the AP needs to provide a trigger frame to ensure that the signals of multiple users arrive at the AP in an aligned manner. The basic process is as follows:

[0044] Step 1: An AP sends a trigger frame, which is used to trigger a station to perform OFDMA-based random access.

[0045] Step 2: The station determines whether to transmit a random access packet according to the transmission conditions. If the station determines to transmit the random access packet, the station transmits the random access packet at a designated time after receiving the trigger frame.

[0046] The transmission conditions may be one or more of the following:

[0047] (1) A station generates a random backoff number within the contention window range of a packet to be transmitted, and the station updates the random backoff number according to the number of random access resources included in the trigger frame, and determines to transmit the random access packet when the backoff is completed. Updating the random backoff number includes that the new random backoff number = the original random backoff value - the number of random access resources. When the random backoff value reaches 0, the backoff is completed.

[0048] (2) The station generates a random backoff number within the contention window range of the packet to be transmitted, and the station updates the random backoff number according to the access condition included in the trigger frame and the number of resources for random access corresponding to the access condition and included in the trigger frame, and decides to transmit the random access packet when the backoff is completed. The updating includes that the new random backoff number=the original random backoff value-the number of resources for random access. When the random backoff value reaches 0, the backoff is completed.

[0049] The transmission conditions may include requirements for the type of random access packet of the station (association request, buffer size report, idle / available channel report, channel status report or channel quality / signal to interference and noise ratio report) and / or requirements for the service type of the random access packet.

[0050] The transmission conditions may further include whether the station needs to determine whether the channel is busy or idle when performing access: the station accesses the channel only when the channel is idle, or the station updates the random backoff value only when the channel is idle.

[0051] It should be noted that in embodiments of the present invention, packets and frames may be used interchangeably unless otherwise specified.

[0052] Step 3: After receiving the random access packets of one or more stations, the AP sends an acknowledgement frame, which includes acknowledgement indication information that the AP has successfully received the random access packets.

[0053] Step 4: The station receives the acknowledgement frame, and learns according to the acknowledgement indication information whether the random access packet sent by the station is successfully received by the AP.

[0054] In the implementation, the AP can also be a general station in the network.

[0055] Figure 1 is a schematic flow chart of frame exchange of STA random access. In this process, if the number of stations that meet the transmission condition is greater than 1, the stations may transmit random access packets in parallel (such as packets transmitted by STA1, STA2 or STA3 in Figure 1). Figure 2 is a schematic diagram of the basic structure of an uplink random access packet. When an access method based on OFDMA is used, the specific format of the random access packet transmitted by a station is shown in Figure 2. The field (L-STF (Legacy Short Training Field), L-LTF (Legacy Long Training Field), L-SIG (Legacy Signal Field), RL-SIG (Repeat Legacy Signal Field), HE-SIG-A (High Efficiency Signal Field) or HE-SIG-B (High Efficiency Signal Field B), etc., before the High Efficiency-Short Training Field (HE-STF)) is used by the receiving end to detect a packet start event, synchronization or channel estimation, and to indicate the packet format. If the packet format is a High Efficiency (HE) packet format, the number of symbols of the High Efficiency Long Training Field (HE-LTF) is further indicated. The station transmits an HE-STF signal and an HE-LTF signal on the subchannel to provide a channel estimation reference. Optionally, the station may transmit a load signal after the HE-LTF signal.

[0056] The receiving end receives and analyzes the pre-HE-STF signal, which indicates the symbol number and packet length of the HE-LTF, and the time of data loading or the symbol number of data loading may be obtained according to the packet length. The receiving end receives the HE-STF signal, whereby the receiving end adjusts and synchronizes an Automatic Gain Control (AGC). Then, the receiving end receives the HE-LTF signal, and the receiving end may perform channel estimation based on the HE-LTF signal. If the packet length information indicates that a data load exists, the receiving end continues to receive the data load. The HE-LTF signal may be a row or column in a P-matrix or a row or column of other orthogonal matrices, and may be selected from a set including low correlation sequences.

[0057] Based on the received HE-LTF signal, the receiving end may determine whether the HE-LTF sequence is used on the subchannel and / or determine the corresponding received signal strength. Specifically, the receiving end may perform channel estimation based on the received HE-LTF signal to obtain a channel coefficient h, which may be multiple (e.g., when there is a single receiving antenna) or vector (e.g., when there are multiple receiving antennas). The received signal power value may be obtained by performing a modulo operation on h to calculate a square value or performing other mathematical operations. The received signal power value depends on the channel gain and the transmission signal power of the transmitter. According to the received signal power value, it may be determined whether the HE-LTF sequence is used on the subchannel. When the power value is higher than a specified threshold, the receiving end may determine that the HE-LTF sequence is used on the subchannel. The physical layer of the receiving end may add a receiving vector (rxvector) message in a receiving start indication (RXstart indication), thereby reporting the receiving result of the HE-LTF to the MAC layer. Specifically, the reception result may include detection results on subcarriers / subchannels / spatial flows / LTF sequences. Optionally, the detection result may be whether the HE-LTF sequence is used or the corresponding received signal strength.

[0058] Furthermore, the receiving end may set the threshold based on the noise power strength or noise and interference strength present before the uplink packet is received. Alternatively, some subchannels and / or HE-LTF sequences may be reserved when the subchannels and HE-LTF sequences are assigned. The receiving end may set the threshold by measuring the noise power strength or noise and interference strength on these reserved resources. The success rate, false positive rate or dropout rate of determining whether the HE-LTF sequence is used may be controlled by adjusting the threshold.

[0059] [Example 2] This embodiment provides an access method, transmitting a first frame to an AP, the first frame carrying uplink transmission requirement information; transmitting uplink multi-user transmission data to the AP when a second frame carrying uplink transmission instruction information is received from the AP within the agreed period, and the uplink transmission instruction information includes a resource instruction and a transmission scheme instruction, and a plurality of uplink users transmit data to be transmitted on the uplink transmission resource indicated by the resource instruction according to a transmission scheme (including a modulation and coding scheme or a transmission duration) indicated by the transmission scheme instruction; or accessing the channel by the station in a contention access scheme based on CSMA / CA when the second frame is not received within the agreed period; Includes.

[0060] The first frame may be transmitted in a contention access manner based on CSMA / CA or by using an OFDMA access method. The uplink transmission requirement information includes packet arrival time, packet size information, or traffic rate information. In addition, the uplink transmission requirement information may further include flow rate, bandwidth requirement information, or BSR. After receiving the AP's acknowledgement frame or response frame corresponding to the first frame, the station may suppress the access manner of CSMA contention access, including increasing the contention window parameter of CSMA contention access, or stopping updating the back-off value of CSMA contention access, and prohibiting CSMA contention access. This realization may reduce the probability of the station's contention transmission attempt, thereby increasing the probability that the access point succeeds in contention for transmission. The access point may instruct multiple users to perform simultaneous transmission after the contention is successful, thereby improving channel access efficiency.

[0061] The AP provides the uplink transmission resource to the station by using the second frame. Specifically, the second frame may be a trigger frame. Furthermore, the agreed period may be a duration having a specific time length. The agreed period may be counted. The AP may add an indication of the target transmission time and / or timeout duration of the second frame in the acknowledgement frame or response frame to the first frame or the beacon frame. The station obtains the agreed period according to the target transmission time and the timeout duration. The agreed period = target transmission time + timeout duration. The timeout duration may be further agreed in the protocol. The station may further use the time at which the AP's acknowledgement frame or response frame to the first frame is received plus the timeout duration as the agreed period.

[0062] [Example 3] The access method provided in the second embodiment may use multiple different scenarios. Therefore, this embodiment provides a process for realizing access through the interaction between AP and STA according to different scenarios (or different data transmission types or different service transmission types). Details are as follows:

[0063] Scenario 1: Periodic, constant rate data transmission For example, this scenario is applicable to a voice service with disabled mute suppression: voice service packets arrive periodically and the coding rate of the voice service determines the packet size.

[0064] As shown in Fig. 3A, after receiving the first frame transmitted by the STA and carrying uplink transmission requirement information, the AP transmits a first trigger frame carrying information about uplink transmission resources to the STA at a preset first time point, and the STA performs uplink multi-user data transmission according to the instruction of the first trigger frame. The AP transmits a second trigger frame carrying information about uplink transmission resources to the STA at a preset second time point, and the STA performs uplink multi-user data transmission according to the instruction of the second trigger frame. The first trigger frame and the second trigger frame are equivalent to the second frame in the second embodiment, and there may be multiple second frames.

[0065] The period in this scenario may be an absolute agreed-upon period or a non-absolute agreed-upon period. When this embodiment of the present invention is applied to a system in which carrier sensing needs to be performed, if the AP detects that the channel is busy, the AP will delay transmission and directly perform transmission after the channel is idle, or perform transmission after the backoff is completed. Therefore, the transmission time of the trigger frame may be later than the agreed-upon period, and the agreed-upon period is called a non-absolute agreed-upon period, and in other cases is called an absolute agreed-upon period.

[0066] To handle the timeout, the STA may start a periodic and constant rate data transmission timer at the agreed upon period of the trigger frame (e.g., the first and second time points in FIG. 3A). If the STA receives a trigger frame in a preset condition (including before the periodic and constant rate data transmission timer times out), the STA may cancel the timer. If the trigger frame is not received in the preset condition, the STA may access the channel by using other methods.

[0067] For example, scenario 1 is also applicable to a voice service with variable rate, which arrives periodically and uses variable rate coding, resulting in variable packet size. After the transmission of the first packet is completed, if there is subsequent data to be transmitted, the STA may request the AP to allocate more resources.

[0068] Specifically, after receiving the first trigger frame, the STA performs uplink multi-user data transmission according to the instruction in the first trigger frame (it should be noted that in this embodiment of the present invention, there may be one or more STAs performing uplink multi-user data transmission), and the first trigger frame indicates parameters such as frequency band or transmission time of the STA's uplink multi-user data transmission. If the number of resources allocated by the AP is less than that requested by the STA, the STA may add a bandwidth indication (or a non-zero indication of the remaining buffer size, i.e., the buffer has data to be transmitted) in the uplink multi-user data transmission. If the bandwidth indication bit is 1, this represents that the STA needs more uplink resources, and the AP may provide an uplink multi-user data transmission resource indication to the STA in the following trigger frame. As shown in FIG. 3B, after the first trigger frame is transmitted and before the second trigger frame is transmitted, the AP may continue to transmit a trigger frame to the STA, and the trigger frame indicates resources for further uplink multi-user data transmission. In this manner, if the number of resources previously allocated by the AP is less than that requested by the STA, the STA may continue to perform uplink multi-user data transmission on the uplink multi-user data transmission resources indicated by the trigger frame.

[0069] Scenario 2: Aperiodic and equal-sized data transmissions After receiving the first frame transmitted by the STA and carrying uplink transmission requirement information, the AP transmits a null data trigger frame to the STA, and the null data trigger frame includes an agreed-upon period. The agreed-upon period may be a time relative to the AP's beacon frame or a periodic time, or a combination of both. The AP receives the STA's response to the null data trigger frame 1. According to the response, the AP transmits a trigger frame to provide the STA with uplink multi-user data transmission resources.

[0070] As shown in Figure 3C, the AP transmits a null data trigger frame 1. After receiving the null data trigger frame 1, the STA may perform uplink transmission and include an agreed-upon sequence (e.g., an LTF sequence or an LTF sequence on a specific subchannel) in the uplink transmission frame. The sequence may be included in the null data trigger frame 1 and specified by the AP, or may be specified by the AP when the STA and the AP associate.

[0071] The AP receives a sequence on a specific subchannel. If the sequence is a sequence agreed upon with the STA, the AP sends a first trigger frame to the STA, where the first trigger frame carries information about uplink multi-user data transmission resources allocated to the STA by the AP according to packet size information or traffic rate information. After receiving the first trigger frame, the STA performs uplink multi-user data transmission according to the uplink multi-user data transmission resources indicated by the first trigger frame.

[0072] When the beacon frame indicates an agreed-upon period of the null data trigger frame, or when the AP and the STA negotiate the agreed-upon period of the null data trigger frame, the STA may initiate the null data trigger frame at the agreed-upon period of the null data trigger frame (e.g., the first time point in FIG. 3C). If the STA receives a null data trigger frame under a preset condition (including before the periodic and constant rate data transmission timer times out), the STA may cancel the timer.

[0073] The station may start an uplink data transmission timer. If a first trigger frame (or a second frame carrying information about uplink transmission resources) is received in a preset condition (including before the uplink data scheduling transmission timer times out) and contains uplink data transmission resource allocation information for the STA, the STA may cancel the timer. If a trigger frame is not received in a preset condition, the STA may access the channel by using other methods.

[0074] Scenario 3: Periodic and variable rate data transmission As shown in FIG. 3D, after receiving the first frame transmitted by the STA and carrying uplink transmission requirement information, the AP may contend for the channel and transmit trigger frame 1 after the contention backoff is completed. After receiving trigger frame 1, the STA may include buffer status report information or bandwidth request information in the uplink multi-user data transmission. After the AP receives the request of the STA, the AP transmits trigger frame 2, which indicates the uplink multi-user data transmission resource allocated to the station by the AP according to the user request. After receiving trigger frame 2, the STA performs uplink multi-user data transmission according to the uplink multi-user data transmission resource indicated by the trigger frame.

[0075] Scenario 4: Aperiodic and variable-sized data transmissions As shown in Figure 3E, after receiving the first frame transmitted by the STA and carrying uplink transmission requirement information, the AP may contend for the channel and transmit trigger frame 1 after the contention backoff is completed, where trigger frame 1 indicates the spatial flow number or LTF symbol number or sequence length for uplink transmission. After receiving trigger frame 1, the STA may include the agreed-upon sequence (e.g., LTF sequence or LTF sequence on a specific subchannel) in uplink transmission frame 1.

[0076] The AP receives a sequence on the subchannel, and if the sequence is an agreed sequence with the STA, the AP transmits trigger frame 2. The trigger frame 2 may include the received sequence number or subchannel number, or a number determined jointly by the sequence number and the subchannel number, and the AP instructs the STA corresponding to the number to transmit buffer status report information or bandwidth request information. Alternatively, the trigger frame 2 carries a station identifier, and the AP instructs the STA having the station identifier to transmit buffer status report information or bandwidth request information.

[0077] After receiving the trigger frame 2, the STA sends an uplink transmission frame 2 carrying a bandwidth request according to the instruction of the trigger frame 2, where the uplink transmission frame 2 includes buffer status report information or bandwidth request information. After receiving the uplink transmission frame 2, the AP sends a trigger frame 3 according to the uplink transmission frame 2 to allocate uplink resources to the STA. After receiving the trigger frame 3, the STA performs uplink multi-user data transmission according to the uplink multi-user data transmission resource indicated by the trigger frame 3.

[0078] Scenario 5: Aperiodic and low-latency data transmission As shown in Figure 3F, the STA may report the existence of aperiodic and low-latency data transmission to the AP. The AP transmits a trigger frame for random access, and the trigger frame indicates an uplink multi-user data transmission resource allocation. At least one uplink resource (e.g., an OFDMA subchannel) is used for random access. After receiving the trigger frame, the station selects an uplink resource to perform uplink random access, or selects not to perform uplink random access.

[0079] Figures 3G-1 and 3G-2 are schematic diagrams of multiple transmission methods working together. As shown in Figures 3G-1 and 3G-2, multiple transmission methods applicable to different scenarios may work together. When different types of data need to be transmitted, according to the scenario that the data is applicable to, the corresponding transmission method may be selected, or multiple transmission methods may be selected simultaneously to perform transmission.

[0080] [Example 4] This embodiment provides an access method, receiving a first frame from an AP, the first frame carrying information about uplink transmission resources; sending a second frame carrying uplink transmission requirement information to the AP, and disabling a contention access scheme based on CSMA / CA or pausing a CSMA / CA contention access back-off timer corresponding to the uplink transmission requirement information queue; transmitting uplink multi-user transmission data to the AP if a third frame carrying information about uplink transmission resources is received from the AP within the agreed period, the uplink multi-user transmission data being transmitted on the uplink transmission resources; or enabling, by the station, a contention access scheme based on CSMA / CA or restarting a CSMA / CA contention access back-off timer corresponding to the uplink transmission requirement information queue if the third frame is not received within the agreed period. Includes.

[0081] The information about the uplink transmission resources in the third frame may further include identifiers of one or more stations using the uplink transmission resources. Further, the back-off timer may be a back-off counter.

[0082] The uplink transmission requirement information includes whether the STA has data to be transmitted, which may be indicated by using one bit. Multiple STAs may simultaneously transmit a second frame carrying the uplink transmission requirement information (the training portions of the second frames may be the same or overlap, and the load portions of the second frames may not overlap). Furthermore, disabling or enabling the CSMA / CA-based contention access scheme may be disabling or enabling the CSMA / CA-based contention access function by the STA. The third frame may be a trigger frame.

[0083] FIG. 4 is a schematic flowchart of frame exchange of an access method according to a fourth embodiment of the present invention. As shown in FIG. 4, the AP transmits a first frame (e.g., a data frame or a trigger frame is used to carry the indication information) to the STA, which carries information about uplink transmission resources (may be considered as indication information like the indication information in FIG. 4). The indication information indicates the uplink transmission resources that can be assigned to the STA to perform uplink multi-user transmission (i.e., the access point uses the first frame to inform the station that there are available uplink transmission resources, and the access point uses the first frame to instruct any user to respond to the first frame without needing backoff). The STA that needs to perform uplink multi-user data transmission may transmit uplink transmission requirement information according to the indication information. The AP may further instruct the parameters for the STA to perform uplink multi-user data transmission according to the indication information (e.g., instruct the uplink transmission resources, the usage scheme or subchannel, the spatial flow allocation, or the modulation and coding scheme used by the STA). The STA generates a second frame (e.g., a frame carrying 26-tone RU information) carrying uplink transmission requirement information according to the parameters. Since all STAs use the same parameters, the generated second frames are the same. Thus, although multiple users use the same resource to transmit frames, the signals of multiple users do not interfere with each other, and the AP may receive one or more second frames (may be multiple overlapping second frames). After receiving the second frame, the AP may transmit a third frame (e.g., a trigger frame for random access). If the AP does not occupy the TXOP or the third frame exchange cannot be completed in the remaining TXOP time, the AP may contend for the channel and transmit the third frame after the contention backoff is completed. If the AP occupies the TXOP, the AP may transmit the trigger frame.After receiving the trigger frame, the STA performs uplink multi-user data transmission according to the trigger frame.

[0084] Table 1 lists three technical solutions for triggering data transmission. In technical solution 1, a specific user is designated to perform transmission on a specific resource (the station does not need to perform contention backoff). In technical solution 2, any user is designated to perform random transmission within a specific resource range. In the technical solution provided in this embodiment, any user is designated to perform transmission on a specific resource. It should be noted that after receiving the second frame, the AP is allowed to trigger multi-user data transmission. For example, the AP may trigger multi-user data transmission by using technical solution 1 or 2 in Table 1. [Table 1] [Example 5] When initially accessing an AP, a STA may determine a channel access method according to the instruction of the AP, or may negotiate the channel access method with the AP, or the channel access method may be predetermined in the protocol.

[0085] Specifically, when initially accessing a channel, the STA learns a channel access method for accessing the AP by receiving a beacon frame. If the AP does not provide an instruction, a default channel access method (e.g., the default channel access method is a contention access method based on CSMA / CA) is used. The STA sends an association request frame to the AP. The association request frame carries information about the STA's channel access method support capability / policy or station version, which information represents the STA's default support capability. Alternatively, the AP obtains the STA's default support capability according to the format of the association request frame (e.g., frame version / modulation and coding scheme). After receiving the association request frame, the AP sends an association response frame to the STA. The association response frame carries a channel access policy (e.g., carries information indicating the channel access method used by the STA to access the channel). The STA accesses the channel according to the channel access policy.

[0086] For example, when a STA performs initial access, the AP may specify an access scheme for the STA according to information about the currently connected STA (e.g., the access scheme or the number of connected STAs). When there are many connected STAs, an OFDMA-based scheduling access scheme may be used.

[0087] [Example 6] This embodiment provides a timer design and timeout process in the access process, for example, timing process for an agreed period in each embodiment of the present invention, as detailed below.

[0088] Figure 5 is a schematic diagram of some situations in which the timer needs to be used. As shown in Figure 5, in the case of overlapping basic service set (OBSS), when an AP is within the coverage area of ​​an OBSS, the AP will back off when it detects that the channel is busy, and will delay the trigger frame transmission within an agreed period. After the channel becomes idle, the AP will contend for the channel and transmit the trigger frame after acquiring the channel through contention.

[0089] When the STA is within the coverage area of ​​the OBSS, if the AP does not detect that the channel is busy, it completes the backoff and the AP transmits a trigger frame. Because the STA is affected by transmission interference or noise or other environmental factors in the OBSS, the STA continues to wait if it fails to receive the AP's trigger frame. However, since the AP is transmitting the trigger frame and the STA may not receive the AP's trigger frame, the STA needs to perform EDCA contention aggressively.

[0090] When both the AP and the STA are within the coverage area of ​​the OBSS, if the AP detects that the channel is busy, it will pause the backoff count and will not resume the backoff count until the channel is idle. After the backoff is completed, the AP will transmit a trigger frame. Since the STA can monitor the transmission of the OBSS, the STA may infer that the AP will delay the transmission of the trigger frame due to the OBSS. The STA may wait for a longer time, i.e., the STA may take into account the transmission delay caused by the ODSS while waiting.

[0091] Specifically, the STA may set a timer (or backoff counter) to the agreed upon trigger frame arrival time, or may set the timer (or backoff counter) after receiving an uplink packet or after the STA's queue changes from empty to non-empty.

[0092] Fig. 5A is a schematic operation diagram of a first timer according to an embodiment of the present invention. As shown in Fig. 5A, when a STA has uplink data to be transmitted or when a queue of the STA changes from empty to non-empty, the STA or queue starts counting down. The duration of the countdown may be specified by the AP or may be agreed upon in the protocol.

[0093] FIG. 5B is a schematic operation diagram of a second timer according to an embodiment of the present invention. As shown in FIG. 5B, after a STA receives an uplink packet or after a queue of the STA changes from empty to non-empty, the STA or queue sets a back-off value. The back-off value may be specified by the AP or agreed upon in the protocol. When the channel is idle, the back-off value is gradually decreased. Specifically, the back-off value may be gradually decreased by 1 after each unit time has elapsed. When the channel is busy, the gradually decreasing of the back-off value is paused.

[0094] FIG. 5C is a schematic operation diagram of a third timer according to an embodiment of the present invention. As shown in FIG. 5C, after a STA receives an uplink packet or after a queue of the STA changes from empty to non-empty, the STA or queue sets a back-off value. The back-off value may be specified by the AP or may be agreed upon in the protocol. When the channel is idle, the back-off value is gradually decreased. Specifically, the back-off value may be gradually decreased by 1 after each unit time has elapsed. When the channel is busy, the gradually decreasing of the back-off value is suspended. Furthermore, when receiving a trigger frame for uplink random access transmitted by the AP, the STA updates the back-off value, for example, increases the back-off value. Receiving the trigger frame represents that the AP has the intention to trigger multiple users to perform uplink transmission. The AP acquires the channel by contention to transmit the trigger frame for uplink random access. In order to improve the probability that the AP acquires the channel by contention, the STA actively decreases the strength with which the STA contends for the channel. Specifically, the STA may add a constant based on the current backoff value, where the constant is either pre-set in the protocol or specified by the AP in a message frame (e.g., an association response frame or a beacon frame). Alternatively, the current backoff value may be multiplied by a constant, where the constant is either pre-set in the protocol or specified by the AP in a message frame.

[0095] Fig. 5D is a schematic operation diagram of a fourth timer according to an embodiment of the present invention. As shown in Fig. 5D, when a STA performs uplink transmission, for example, transmits a buffer size report or a bandwidth request, and receives an AP's acknowledgement frame for successful transmission, the STA may update the back-off value. Since the STA transmits the amount of data that needs to be transmitted or the required bandwidth information to the AP, the AP allocates resources to the STA. Therefore, the STA may reduce the strength of the STA's contention for the channel by updating the back-off value, thereby increasing the AP scheduling opportunity.

[0096] [Example 7] After a STA acquires the channel, the STA may relinquish control to the AP, which instructs one or more STAs to perform uplink multi-user data transmission.

[0097] FIG. 6A is a first schematic diagram of transmitting a multi-user transmission trigger frame according to an embodiment of the present invention. As shown in FIG. 6A, a STA accesses a channel in an EDCA manner and transmits a single-user physical layer protocol data unit (SU-PPDU). After an AP receives an uplink SU-PPDU transmitted by a STA, the AP responds with an acknowledgement frame or a block acknowledgement frame. In this frame, the AP may indicate that the AP transmits a multi-user transmission trigger frame by using a control channel. For example, the AP may indicate that the AP transmits a multi-user transmission trigger frame by using a control channel by using one bit in this frame. After the STA receives the frame, if it is indicated in the frame that the AP transmits a multi-user transmission trigger frame by using a control channel, the STA may transmit an acknowledgement frame (the acknowledgement frame is used to confirm that the AP can transmit a frame for triggering uplink multi-user data transmission by using a control channel). If not, the STA continues to transmit a SU-PPDU.

[0098] After receiving the acknowledgement frame of the STA, the AP transmits a multi-user transmission trigger frame. The AP may include information about the uplink transmission resources of the STA or the STA and other STAs in the trigger frame. After the acknowledgement frame of the STA is received, the trigger frame may be transmitted after a SIFS time.

[0099] Optionally, after receiving the STA's acknowledgement frame, the AP may transmit a multi-user transmission trigger frame after an interval of duration 1 (an agreed period longer than SIFS). During that time, the AP detects whether the channel is busy or idle. If the channel is idle, the AP transmits the multi-user transmission trigger frame. If the channel is busy, the AP transmits a short packet with a transmission time shorter than a threshold, which may be an acknowledgement frame or other short frame, and the STA may continue to use the channel after receiving the short packet. Alternatively, if the channel is busy, the AP may not transmit a data packet. When the STA does not detect that the channel is busy or that there is a packet to be transmitted during duration 2 (e.g., a time longer than duration 1), the STA may continue to transmit a data packet.

[0100] Figure 6B is a second schematic diagram of sending a multi-user transmission trigger frame according to an embodiment of the present invention. As shown in Figure 6B, after receiving an uplink SU-PPDU, the AP sends an acknowledgement frame or a block acknowledgement frame, and sends a multi-user transmission trigger frame after a SIFS time. Compared with the method shown in Figure 6A, after sending an acknowledgement frame or a block acknowledgement frame, the AP can directly trigger the STA to perform uplink multi-user data transmission without needing to wait for receiving an acknowledgement frame responded by the STA.

[0101] Optionally, Figure 6C is a third schematic diagram of sending a multi-user transmission trigger frame according to an embodiment of the present invention. As shown in Figure 6C, after receiving an uplink SU-PPDU, an AP sends an acknowledgement frame or a block acknowledgement frame, and the acknowledgement frame carries uplink transmission trigger information. In this case, the AP does not need to indicate that the AP sends a multi-user transmission trigger frame by using a control channel by using one bit in the frame. After one or more STAs receive the information, the STAs send uplink multi-user transmission data according to the uplink transmission trigger information.

[0102] Fig. 6D is a fourth schematic diagram of sending a multi-user transmission trigger frame according to an embodiment of the present invention. As shown in Fig. 6D, a STA sends an RTS packet, and an AP responds with a CTS packet. The AP may use the CTS packet to indicate whether the multi-user transmission trigger frame needs to be sent by using a control channel.

[0103] When the AP needs to send a multi-user transmission trigger frame by using a control channel, for STAs that support this interaction process (e.g., STAs that support a protocol version, or STAs that have notified the AP that the STA supports the interaction process, or STAs that support channel control handover), the AP may put the MAC address of the AP in the receiving address (RA) field of the CTS. Otherwise, the AP may put the MAC address of the RTS sender in the RA of the CTS. After the STA receives the CTS, if the RA address carried in the CTS is the address of the AP, the STA sends a short packet (e.g., a delivery acknowledgement frame), and the AP sends a multi-user transmission trigger frame after receiving the short packet. The AP may include uplink transmission resource indication information of the STA or the STA and other STAs in the multi-user transmission trigger frame. After receiving the multi-user transmission trigger frame, the STA performs data transmission according to the uplink transmission resource indication information.

[0104] [Example 8] This embodiment of the present invention proposes an access method (e.g., the above three uplink access methods) for the STA, and the access method may be designated by the AP. After the AP designates the access method to the STA, the STA can only perform access and data transmission in the access method designated by the AP. The AP may designate the access method by sending a radio frame to the STA. The radio frame may carry indication information used to indicate the access method of the STA. The radio frame may be a beacon frame or an association response frame.

[0105] Specifically, this embodiment proposes an access method, receiving a wireless frame sent by an AP, where the wireless frame indicates an access scheme for performing channel access, and the wireless frame is an association response frame, a beacon frame, or a response frame of the AP to the received data frame; transmitting uplink multi-user transmission data to the AP if a second frame (e.g., a trigger frame) carrying information about uplink transmission resources is received from the AP within the agreed-upon period, the uplink multi-user transmission data being transmitted on the uplink transmission resources; or accessing the channel by the station in a contention access manner based on CSMA / CA if the second frame is not received within the agreed-upon period. Includes.

[0106] If the wireless frame is a beacon frame, the specific process of this embodiment is as follows.

[0107] Step 1: An AP generates a beacon frame, and the beacon frame carries indication information used to indicate the access method of the STA.

[0108] Step 2: The AP transmits a beacon frame.

[0109] The instruction information in step 1 may be public information shared by all STAs, or may be private information dedicated to one or more STAs and indicating the transmission scheme for each STA separately. For the latter, the beacon frame may further include the identifier (e.g., association identifier AID) of one or more STAs.

[0110] The indication information sent to each STA may be a field. The value of the field may indicate one or more transmission schemes that may be used by the STA. Furthermore, the indication information may be a bitmap. Each bit may indicate whether a transmission scheme is allowed to be used or not.

[0111] If the wireless frame is an association response frame, the specific process of this embodiment is as follows:

[0112] Step 1: The STA sends an association request frame to the AP.

[0113] Step 2: The AP sends an association response frame to the STA, where the association response frame includes indication information used to indicate the access method of the STA.

[0114] In addition, the association request frame and the association response frame in step 1 and step 2 can also be a re-association request frame and a re-association response frame. The process is the same, and the details are not described again here.

[0115] [Example 9] According to the access method used by the STA, there are three data transmission states for the STA.

[0116] Contention condition: A STA can only perform data transmission in a contention-based manner, for example, Scheme 1 and / or Scheme 2 of the three access schemes mentioned above.

[0117] Scheduling state: The STA can only perform data transmission in a scheduling-based scheme, e.g. scheme 3.

[0118] Hybrid state: A STA can perform data transmission in both the contention-based scheme and the scheduling-based scheme, for example, in any one of schemes 1, 2, or 3.

[0119] AP assigns access method to STA, which is to actually assign data transmission state to STA. However, data transmission state of STA may need to change with time. For example, when there are several STAs in the system, hybrid state of STA is more conducive to STA's data transmission. When there are many STAs, contention state or scheduling state of STA is helpful to improve overall system performance. Therefore, this embodiment proposes a method for switching data transmission state of STA.

[0120] When the STA is in a data transmission state and successfully transmits a data frame to the AP, the AP transmits a response frame to the STA, and the response frame carries indication information used to indicate the data transmission manner of the STA (or enable the STA to enter a data transmission state). The specific process is as follows:

[0121] Step 1: A STA transmits a wireless frame to an AP. The wireless frame may be a data frame.

[0122] Step 2: The AP sends a response frame to the STA, where the response frame carries indication information used to indicate the data transmission manner of the STA.

[0123] When a STA is in a contention state and successfully transmits a data frame to the AP, and the AP finds that there are many STAs in the system at this time, the STAs in excessive contention state will significantly affect the overall system performance, so the AP will send indication information to the STA in a response frame, so that the STA enters a scheduling state, thereby reducing the contention degree within the system and improving the overall channel resource utilization rate.

[0124] Alternatively, the AP may enable the STA to enter the hybrid state from the contention state by using indication information: the STA should monitor the channel to receive a trigger frame, or preferably, choose to send a buffer status report (BSR) instead of directly sending a data frame.

[0125] Similarly, the AP may further enable the STA to enter the contention state from the hybrid state by using the indication information, in which the STA can transmit data only in the scheme 1 and / or the scheme 2, which affects the selection of the contention access policy by the AP.

[0126] It should be noted that step 1 in the above process may be omitted, i.e., the AP directly sends a radio frame to the STA, and the radio frame carries indication information used to indicate the data transmission method of the STA.

[0127] In addition, when the indication information is not received, the STA may determine the transmission mode according to a certain rule. For example, the STA uses the OFDMA-based scheduling access method by default. Optionally, when the STA uses the OFDMA-based scheduling access method, a timer may be set. After the timer times out, the STA may use the CSMA / CA-based contention access method or the OFDMA-based contention access method.

[0128] [Example 10] The contention access method based on OFDMA is that the AP transmits a trigger frame for random access (TFR) and designates one or more subchannels in the TFR for random access. After receiving the TFR, when the condition is met (or when the condition for responding to the TFR is met), the STA may randomly select a subchannel for random access to perform transmission. Because the STA randomly selects a subchannel, the probability of collision is relatively large. Analysis shows that the best channel utilization of this method is about 37%. When a large number of STAs participate in contention together, the channel utilization may be lower. Therefore, this embodiment provides the following three data transmission methods:

[0129] Method 1: After the STA receives a TFR, when the conditions are met, The STA transmits an unfragmented data frame (e.g., an unfragmented MAC layer Protocol Data Unit (MPDU)) within the time specified by the TFR, or When a STA transmits an aggregated MPDU including multiple MPDUs within a time period specified by the TFR, the multiple MPDUs include at most one fragmented data frame, for example, only the last MPDU includes a fragmented data frame.

[0130] Method 2: After receiving a TFR, a STA is not allowed to transmit a data frame unless the data frame carries a buffer status report BSR.

[0131] Method 3: After receiving a TFR, the STA is not allowed to transmit a data frame.

[0132] [Example 11] For the OFDMA-based scheduling access scheme, after receiving the trigger frame sent by the AP, the STA may perform data transmission on the corresponding channel according to the instruction of the trigger frame. Before the AP sends the trigger frame to the STA, the STA needs to send a buffer status report BSR to the AP. The BSR may be sent in the CSMA / CA-based contention access scheme (scheme 1) or the OFDMA-based contention access scheme (scheme 2). In view of the problem of whether the STA is allowed to send a BSR (or other control frame / management frame) in the two contention access schemes, this embodiment proposes several possible solutions as follows.

[0133] Solution 1: A STA may simultaneously perform transmission in Scheme 1 and Scheme 2. That is, a STA may simultaneously enable two backoff processes, one of which is used for CSMA / CA-based contention access and the other of which is used for OFDMA-based contention access.

[0134] Solution 2: The STA performs transmission in either scheme 1 or scheme 2, and the STA decides to select scheme 1 or scheme 2.

[0135] Solution 3: The AP specifies that the STA transmits in Scheme 1 and / or Scheme 2. That is, the AP transmits a wireless frame to the STA, and the wireless frame carries indication information, which is used to specify that the STA transmits in Scheme 1 or Scheme 2, or both. The wireless frame may be a beacon frame, an association response frame, or a reassociation response frame. For example, the AP includes indication information indicating the transmission scheme of the STA in a beacon frame, and the STA reads the beacon frame to obtain the transmission scheme, and transmits an association request frame in the transmission scheme to the AP.

[0136] [Example 12] This embodiment proposes a transmission mode switching method. After acquiring a TXOP by acquiring a channel through contention in a manner based on CSMA / CA, the STA may transmit a wireless frame to the AP and give up the TXOP to the AP. The AP may start uplink multi-user transmission by using the TXOP, and needs to schedule the STA in uplink multi-user transmission. The specific process is as follows:

[0137] Step 1: The STA accesses a channel through a contention access method based on CSMA / CA, and transmits a wireless frame to the AP after the contention is successful, and the wireless frame carries indication information, which is used to indicate that the AP may instruct the STA to perform uplink multi-user data transmission after receiving the wireless frame, and the AP needs to schedule the STA in uplink multi-user transmission.

[0138] Step 2: After receiving the radio frame, the AP sends a trigger frame after a preset time, and the trigger frame carries scheduling information to trigger the STA to send a data frame (and other STAs may also be triggered).

[0139] Step 3: The STA transmits a wireless frame according to the trigger information of the AP.

[0140] Step 4: The AP transmits a multi-user block ACK (MBA) frame.

[0141] Furthermore, the STA may add indication information in the radio frame in step 3, thereby indicating whether the AP can continue to transmit other frames after transmitting the MBA in step 4. The other frames may be a trigger frame or a downlink data frame. If the indication information indicates that the AP can further continue to transmit other frames, the AP transmits a radio frame after a preset time after transmitting the MBA in step 4. The preset time may be a SIFS, and the radio frame may be a trigger frame or a downlink data frame. If the indication information indicates that the AP cannot further continue to transmit other frames, the AP cannot transmit a radio frame after transmitting the MBA in step 4. The STA may transmit a radio frame after a preset time, and the preset time may be a SIFS.

[0142] [Example 13] This embodiment provides a transmission mode switching method. After acquiring a TXOP by acquiring a channel through contention in a contention access method based on CSMA / CA, the STA may transmit a wireless frame to the AP, and the AP is allowed to schedule other STAs that share the TXOP with the STA. The specific sharing method may be an OFDMA method or a multi-user MIMO method. As the owner of the TXOP, the STA has the right to control whether the current TXOP is for multi-user transmission or single-user transmission, and to control the transmission time of the single-user transmission or multi-user transmission.

[0143] As shown in FIG. 7, this embodiment provides a transmission mode switching method, which includes the following steps:

[0144] Step 1: STA1 transmits a first frame to the AP in a TXOP initiated by STA1, where the first frame carries first indication information, and the first indication information is used to indicate that the AP may trigger an uplink multi-user data transmission.

[0145] Step 2: After receiving the first frame of STA1, the AP sends a trigger frame after a preset time.

[0146] The trigger frame should carry scheduling information for triggering the STA to transmit a data frame (i.e., ensure that the STA is triggered, but other STAs may also be triggered). The scheduling information is used to assign a space-time stream to each uplink user when an uplink multi-user MIMO (UL MU-MIMO) transmission scheme is used, to assign a frequency domain sub-band to each uplink user when an uplink orthogonal frequency division multiple access (UL OFDMA) transmission scheme is used, and to assign a frequency domain sub-band to each uplink user and each user's space-time stream within the frequency domain sub-band when both UL OFDMA and UL MU-MIMO transmission schemes are used.

[0147] The AP responds to the first frame (e.g., sends an ACK frame or a Block ACK (BA) frame) before sending the trigger frame or simultaneously when sending the trigger frame. Specifically, after the AP receives the first frame of STA1, the response frame responded by the AP may carry second instruction information, and the second instruction information is used to indicate whether the AP follows the instruction of STA1. That is, the AP may further use the second instruction information to refuse to use UL MU transmission, and may respond to the first frame in a conventional manner.

[0148] Step 3: STA1 transmits a second frame according to the information carried in the trigger frame sent by the AP. The second frame is transmitted in a UL MU format. According to the instruction of the trigger frame sent by the AP, the UL MU format may be the frame format of a user in UL OFDMA (i.e., the second frame is located in a frequency domain subchannel allocated by the AP), or may be the format of a user in UL MU-MIMO (i.e., the second frame is located in a spatial flow / space-time stream allocated by the AP).

[0149] According to the instruction of the trigger frame, in addition to STA1, other STAs (eg, STA2) and STA1 both use the UL MU mode to transmit data to the AP.

[0150] Step 4: The AP sends a response frame, which responds to the data frames (or UL MU data frames) sent by multiple users simultaneously. The response frame may be a multi-user block ACK (MBA) frame or a DL MU (Downlink Multi-User) mode carried ACK / BA frame.

[0151] In addition, the STA may also add the first indication information in the second frame in step 3 to indicate whether the AP can continue to trigger UL MU transmission in subsequent transmissions. Furthermore, when transmitting the response frame, the AP may choose to use the DL MU transmission scheme to transmit data of more than one user to each user. Therefore, if STA1 is allowed to continue UL MU transmission in step 3, the AP may respond to the multi-user data frame in step 3 by using an independent trigger frame, or may respond with information or downlink multi-user data frame by using a DL MU to carry the trigger frame in the DL MU in step 4.

[0152] In this embodiment, if the first indication information in the frame transmitted by STA1 indicates that the AP cannot trigger the UL MU transmission (unauthorized multi-user transmission shown by frames 1-3 in FIG. 7), the AP cannot trigger the UL MU in subsequently transmitted frames.

[0153] In this embodiment, in the transmission of STA1, the owner of the TXOP determines the transmission length of the TXOP. Therefore, when the transmission of STA1 ends and the unauthorized AP continues to use the TXOP, STA1 may send a Contention Free-End (CF-End) frame to end the TXOP. When the AP triggers more than one STA to transmit data by using the UL MU, the data length of STA1 should be used as the reference for the transmission time, i.e., the transmission of other STAs cannot exceed the transmission length of STA1.

[0154] The preset time in this embodiment may be SIFS, or may be other fixed time such as SSIFS or PIFS. The first indication information in this embodiment is located in the HE control field, and the second indication information is also located in the HE control field, and information bits of the first indication information may even be reused.

[0155] Furthermore, in this process, if STA2 indicates that data transmission is not completed (e.g., the more data bit is set to 1) in the frame transmitted by STA2 in the UL MU format, the AP may indicate that some data transmission is not completed in the subsequent trigger frame (the specific form may be to reuse the more data bit, or to use other dedicated information bits). As the owner of the TXOP, STA1 may take the information into consideration to decide whether to continue to grant UL MU transmission. When the AP triggers UL MU transmission, STA1 may indicate information about the minimum resource allocated to STA1 in the granted UL MU while indicating UL MU transmission permission, which prevents the AP from allocating some resources to STA1, the owner of the TXOP. For example, if the AP triggers UL OFDMA transmission later, STA1 may indicate that the minimum bandwidth allocated to STA1 by the AP cannot be less than 20 MHz.

[0156] [Example 14] This embodiment of the present invention may be applied to multi-user uplink contention scenarios.

[0157] When a station has a data packet to be transmitted, or when the station transmits a buffer size report and receives an acknowledgement frame responded to by the AP, there are three cases: 1. If the trigger frame is received within the agreed period, the OFDMA access scheme (which may be the OFDMA contention access scheme or the OFDMA scheduling access scheme) is used to transmit data, or if the trigger frame is not received within the agreed period, the contention access scheme based on CSMA / CA is used to transmit data. 2. The contention access scheme based on CSMA / CA with a relatively large CW is used to transmit data within the agreed period, and the contention access scheme based on CSMA / CA with a relatively small CW is used to transmit data after the agreed period. 3. When the agreed period ends, the size of the CW is reduced.

[0158] From the target transmission time of the trigger frame indicated by the beacon frame or negotiated by the station and the AP, there are three cases: 1. If the trigger frame is received within the agreed period, the OFDMA access method (which may be the OFDMA contention access method or the OFDMA scheduling access method) is used to transmit data, or if the trigger frame is not received within the agreed period, the contention access method based on CSMA / CA is used to transmit data. 2. The contention access method based on CSMA / CA with a relatively large CW is used to transmit data within the agreed period, and the contention access method based on CSMA / CA with a relatively small CW is used to transmit data after the agreed period. 3. When the agreed period ends, the size of the CW is reduced.

[0159] For the aforementioned agreed period, the station may set a timer to count the agreed period. Before the timer times out, the channel access method 1 (e.g., OFDMA access method (if a trigger frame is received) or a contention access method based on CSMA / CA with a relatively large CW) is used. After the timer times out, the channel access method 2 (e.g., OFDMA access method (if a trigger frame is received) or a contention access method based on CSMA / CA with a relatively small CW) is used. After the trigger frame from the AP is received, the timer is canceled. Before the timer times out, one way is for the station to delay contention or reduce the strength with which the station contends for the channel. Furthermore, when the channel is acquired by contention, the station may cede control to the AP, and the AP transmits a multi-user transmission trigger frame. The trigger frame may carry information about uplink transmission resources.

[0160] The station uses an access scheme that suppresses CSMA contention access during event 1. The station uses a scheme that promotes CSMA contention access during event 2. The access scheme that suppresses CSMA contention access includes increasing a contention window parameter for CSMA contention access, or stopping updates of a back-off value for CSMA contention access, or disabling CSMA contention access. The access scheme that promotes CSMA contention access includes decreasing a contention window parameter for CSMA contention access, or restarting / starting updates of a back-off value for CSMA contention access, or enabling CSMA contention access.

[0161] Event 1 may be that the station has a data packet to be transmitted, or that the station transmits a buffer size report and receives an acknowledgement frame in response by the AP, etc. Event 2 may be that a timer times out and a trigger frame transmitted by the AP is not received, etc. The AP provides an event indication, which is used to instruct (explicitly or implicitly) the station to use a channel access scheme. For example, the event indication may be information about uplink transmission resources carried in the trigger frame transmitted by the AP.

[0162] [Example 15] FIG. 8 illustrates an access device according to an embodiment of the present invention. As shown in FIG. 8, this embodiment provides an access device, A transmitting module 801 configured to transmit a first frame carrying uplink transmission requirement information to an access point; a processing module 802 configured to transmit uplink multi-user transmission data to the access point if a second frame carrying information about uplink transmission resources is received from the access point within the agreed period, and the uplink multi-user transmission data is transmitted on the uplink transmission resources or to access the channel by the station in a contention access manner based on carrier sense CSMA / CA if the second frame is not received within the agreed period; Includes.

[0163] Optionally, the access device further includes a timing module 803 configured to count an agreed period by using a timer, the initial value of the timer being specified by the access point or agreed within the protocol.

[0164] Optionally, the access device further includes a receiving module 804 configured to receive a radio frame transmitted by the access point, where the radio frame indicates a transmission time of the second frame, and the radio frame is an association response frame, a beacon frame, or a response frame of the access point to the received data frame.

[0165] Some technical features in the above-mentioned apparatus embodiments, such as access methods, timers, or other further explanations (such as trigger frames), are similar to or correspond to some technical features in the above-mentioned method embodiments, and repeated explanations will not be given here.

[0166] Further, corresponding to the aforementioned method, an embodiment of the present invention further provides an access device. The device includes a memory and a processor, the memory is configured to store instructions required by the processor for execution, and the processor is configured to execute the method in the aforementioned embodiment. Moreover, the device may further include a transmitter and a receiver configured to transmit and receive data, respectively.

[0167] In accordance with the embodiments of the present invention, as described herein, the present invention has been described in specific embodiments, but the present invention should not be construed as being limited to these embodiments, but rather as being set forth in the claims.

Claims

1. receiving, by a station, a first frame carrying information for indicating an access scheme of the station, the access scheme being a contention access scheme based on carrier sense multiple access with collision avoidance or orthogonal frequency division multiple access, or the access scheme being an orthogonal frequency division multiple access based on a scheduling access scheme, the access scheme being specified by an access point (AP), the first frame including a field, a first value of the field indicating the access scheme; transmitting uplink multi-user transmission data to the AP by the station when the access scheme is an orthogonal frequency division multiple access based on the scheduled access scheme and a second frame carrying information about uplink transmission resources is received from the AP within an agreed period, and the uplink multi-user transmission data is transmitted on the uplink transmission resources; or accessing a channel by the station using a contention access scheme based on CSMA / CA when the access scheme is an orthogonal frequency division multiple access based on the scheduled access scheme and the second frame is not received within the agreed period. A communication method including:

2. The communication method of claim 1 , wherein the first frame is a beacon frame or an association response frame.

3. The first frame is an association response frame, and the method includes: The communication method of claim 2 , further comprising the step of transmitting, by the station, an association request frame to the AP.

4. a receiver configured to receive a first frame carrying information for indicating an access scheme of a station, the access scheme being a contention access scheme based on carrier sense multiple access with collision avoidance or orthogonal frequency division multiple access, or the access scheme being an orthogonal frequency division multiple access based on a scheduling access scheme, the access scheme being specified by an access point (AP), the first frame including a field, a first value of the field indicating the access scheme; and a transmitter configured together with the receiver to transmit uplink multi-user transmission data to the AP if the access scheme is an orthogonal frequency division multiple access based on the scheduled access scheme and a second frame carrying information about uplink transmission resources is received by the receiver from the AP within an agreed period, and the uplink multi-user transmission data is transmitted on the uplink transmission resources, or to access a channel by a contention access scheme based on CSMA / CA if the access scheme is an orthogonal frequency division multiple access based on the scheduled access scheme and the second frame is not received within the agreed period; Stations including.

5. The station of claim 4 , wherein the first frame is a beacon frame or an association response frame.

6. The station of claim 4 , wherein the first frame is an association response frame, and the transmitter is further configured to transmit an association request frame.

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