Communication method and apparatus

Abstract

A communication method and apparatus, which relate to the field of communications, and can prevent, to the greatest possible extent, a station from frequently scanning a channel, thereby improving the reliability of communication. The method is applied to a communication network comprising a plurality of access points (APs) associated with the same BSSID. In other words, the method is applied to co-frequency networking in the communication network. The method may comprise: at least two APs among a plurality of APs generating a plurality of beacon frames, and the at least two APs simultaneously sending the beacon frames.

Description

Communication methods and devices

[0001] This application claims priority to Chinese patent application No. 202510301675.8, filed on March 12, 2025, entitled "Communication Method and Apparatus", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communications, and more particularly to communication methods and apparatus. Background Technology

[0003] In communication systems, multiple access points (APs) in the network can be virtualized into a single AP through co-frequency networking. This allows a station (STA) to perceive itself as always associated with an AP while moving, thus eliminating the need for roaming and achieving a "zero roaming" effect. For example, multiple APs can send beacon frames to the STA. These beacon frames from different APs can include the same basic service set identifier (BSSID). Accordingly, the station can determine that it is always associated with the same AP based on the identical BSSID in the beacon frames from different APs.

[0004] However, because the distances between different APs and individual stations vary, the signal strength of beacon frames received by a single station from different APs varies. If the statistical value of the signal strength of beacon frames from these different APs is lower than a preset threshold, it will trigger the station to roam, thereby causing the station to frequently scan channels, reassociate with other APs with different BSSIDs, and may even cause the station to drop out of service, reducing communication reliability.

[0005] Therefore, how to minimize the frequency of station channel scanning in order to improve communication reliability has become an urgent problem to be solved. Summary of the Invention

[0006] This application provides a communication method and apparatus that can minimize the need for stations to frequently scan the channel, thereby improving communication reliability.

[0007] In a first aspect, a communication method is provided, which can be executed by an Access Point (AP). Unless otherwise specified, "AP" in this application can refer to the AP itself, a component in the AP (e.g., a processor, chip, or chip system), or a logical module or software that can implement all or part of the AP. The method is applied to a communication network including multiple access points associated with the same BSSID. The method can include: at least two of the multiple APs generating beacon frames, and at least two APs simultaneously sending beacon frames.

[0008] Based on the above scheme, at least two access points among multiple access points simultaneously send beacon frames, causing collisions between the simultaneously sent beacon frames. This allows the station to successfully demodulate the beacon frame with the higher signal strength among the collided beacon frames, but fails to demodulate the beacon frame with the lower signal strength among the collided beacon frames. The station determines whether to trigger roaming based on the beacon frame with the higher signal strength among the collided beacon frames, thereby reducing the probability of triggering station roaming and station frequent channel scanning.

[0009] In this application, beacon frames that are not successfully demodulated by the station among multiple beacon frames transmitted simultaneously can be referred to as "collision-dropped" beacon frames or "cancelled" beacon frames. For collision-dropped beacon frames, the station cannot obtain the content contained in the beacon frame, such as the BSSID contained in the beacon frame, and therefore cannot identify whether the beacon frame contains the same BSSID. This means that when calculating the average signal strength of beacon frames containing the same BSSID, the signal strength of collision-dropped beacon frames will not be included in the calculation of the average signal strength.

[0010] Since the signal strength of beacon frames that are knocked down is generally low, they are considered weak beacon frames. If the weak beacon frames that are knocked down among multiple beacon frames containing the same BSSID are not included in the calculation of the average signal strength, the average signal strength of multiple beacon frames containing the same BSSID will be increased. This will reduce the probability that the site will determine the beacon frames carrying the same BSSID as weak signals based on the average signal strength, thereby reducing the probability of site roaming and frequent channel scanning.

[0011] In one possible implementation, multiple APs are located in at least one AP group; at least two APs are APs in any AP group within at least one AP group.

[0012] Based on this possible implementation, multiple APs can be divided into at least one AP group. An AP group may include one AP or at least two APs. At least one AP group must contain at least two APs, and at least two APs simultaneously transmitting beacon frames can be located within the same AP group. APs within the same AP group transmit beacon frames at overlapping times, meaning at least two APs in the same AP group transmit beacon frames simultaneously. APs in different AP groups transmit beacon frames at different times, or the transmission times of APs in different AP groups do not overlap, and APs in different AP groups will not collide when transmitting beacon frames.

[0013] In one possible implementation, when there are multiple AP groups, any two APs in any AP group are not adjacent; where two APs are not adjacent means that the location distance between the two APs is greater than a distance threshold, and / or that the path loss between the two APs is greater than a path loss threshold.

[0014] Based on this possible implementation, the AP and its neighboring APs are located in different AP groups. This prevents the AP from sending beacon frames at the same time, avoiding the phenomenon of beacon frame loss caused by the signal strength of multiple beacon frames received by the site from multiple access points at the same time being close.

[0015] In one possible implementation, at least one AP group corresponds to a first candidate grouping method; the first candidate grouping method is the candidate grouping method with the largest gain among multiple candidate grouping methods, and the gain of a candidate grouping method is used to characterize the beacon frame loss and weak beacon frame occurrence when beacon frames are sent in that candidate grouping method.

[0016] It should be understood that if a beacon frame is lost while beacon frames are being transmitted simultaneously, the STA will not be able to detect the existence of the 802.11 network at that time, triggering the station to roam. This leads to the station frequently scanning the channel, reducing communication reliability. The STA determines whether to trigger roaming based on the statistical value of the signal strength of all beacon frames associated with the same BSSID. However, if there are multiple beacon frames with weak signal strength associated with the same BSSID, the calculated statistical value of the signal strength of beacon frames associated with the same BSSID may be too low, thus triggering station roaming.

[0017] Based on the above analysis, in at least one AP group, the more beacon frame losses and weak beacon frames sent by APs, the greater the probability of triggering STA roaming. Based on this possible implementation, when multiple APs are divided into at least one AP group, each AP group within that group should send beacon frames according to the first candidate grouping method with the fewest beacon frame losses and weak beacon frames, which can better reduce the probability of triggering STA roaming.

[0018] In one possible implementation, the gain of the candidate packet method is determined based on the number of beacon frame losses and the number of weak beacon frames that occur when beacon frames are sent using that candidate packet method.

[0019] Both the number of beacon frame losses and the number of weak beacon frames can trigger a station to roam. Based on this possible implementation, the gain of the candidate packet method can be determined by the number of beacon frame losses and the number of weak beacon frames when sending beacon frames, which can better reduce the probability of station roaming and frequent channel scanning.

[0020] In one possible implementation, at least two APs simultaneously transmit beacon frames, including: at least two APs starting to transmit beacon frames after a delay time following the arrival of the target beacon transmission time (TBTT); wherein the delay time of at least two APs is greater than the delay time of the first AP and less than a first duration; the first duration is the sum of the delay time of the first AP, XIFS, and the frame length of a beacon frame; the delay time of the first AP is the shortest delay time among the multiple APs.

[0021] In this application, the moment after the TBTT and experiencing a delay is named the preparation moment.

[0022] Based on this possible implementation, each of the at least two access points can perform a preparation operation to send a beacon frame in response to the arrival of the preparation time during the time period when the first AP sends a beacon frame. This involves detecting whether the channel is busy or idle. Since at least two APs operate on the same channel, the busy / idle status of the channel detected by different APs is the same. Ignoring the detection capability / detection duration of the at least two APs, if the preparation time of the at least two APs falls within the time period when the first AP sends a beacon frame, then at the end of the time period when the first AP sends a beacon frame, these at least two APs can simultaneously detect that the channel is idle, and in the case of an idle channel, they can simultaneously send beacon frames after experiencing at least the same extended interframe space (XIFS).

[0023] In one possible implementation, before at least two APs simultaneously send beacon frames, each of the multiple APs performs clock synchronization; wherein the clock synchronization error after clock synchronization is less than a preset duration; the preset duration is determined according to the channel busy detection interval of the site.

[0024] Based on this possible implementation, at least two APs out of multiple access points (APs) can simultaneously, for example, detect channel busy / idle status when the TBTT (Block Transmission Time To Detection) arrives, and send beacon frames in response to detecting channel idleness. The moment of detecting channel busy / idle status can be called the channel detection moment, and the time interval between adjacent channel detection moments can be called the channel busy / idle detection interval. To ensure that at least two APs send beacon frames simultaneously, the clocks of at least two APs need to be strictly synchronized. For example, the clock synchronization error after synchronization of the clocks of at least two APs needs to be less than the channel busy / idle detection interval. This way, even if there is a clock synchronization error between at least two APs, it can be guaranteed that at least two APs will perform channel busy / idle detection within one channel busy / idle detection interval. Since the channel busy / idle detection interval is relatively short, at least two access points performing channel busy / idle detection within one channel busy / idle detection interval can be approximated as performing channel detection simultaneously, ensuring that at least two APs detect the same channel state, for example, both detecting channel idleness, and thus sending beacon frames in response to simultaneously detecting channel idleness. Collisions occur between the simultaneously sent beacon frames.

[0025] In one possible implementation, before at least two APs simultaneously send beacon frames, at least two of the multiple APs simultaneously send clear to send (CTS) frames; the simultaneous sending of beacon frames by at least two APs includes: each of the at least two APs sending a beacon frame after a preset time elapsed after sending the CTS frame; wherein the preset time elapsed for the at least two APs is the same.

[0026] Based on this possible implementation, each of at least two access points (APs) simultaneously sends a CTS frame to each STA they serve to inform the STAs that the channel for sending beacon frames is occupied and that STAs are not allowed to send data frames, etc., on the same channel. The access point sends the beacon frame after sending the CTS frame. In this way, the AP can pre-broadcast a CTS to notify the STAs not to send data frames that would occupy the channel, and then send the beacon frame after a preset time interval. Since each beacon frame has a certain length, and this length is greater than the clock synchronization error, even if there is a clock synchronization error between at least two access points, it can be guaranteed that the beacon frames sent by at least two access points after the preset time interval overlap, thus achieving simultaneous beacon frame transmission and preventing collisions between the beacon frames.

[0027] It should be understood that if simultaneous CTS frames cause a collision at a station, i.e., the station does not resolve all simultaneously transmitted CTS frames, then the station needs to resolve at least one of the simultaneously transmitted CTS frames to announce to the station that the channel for sending beacon frames is occupied.

[0028] In one possible implementation, the TBTT and XIFS of APs in the same AP group are identical. Based on this possible implementation, the identical TBTT and XIFS of APs in the same AP group cause the timing of beacon frame transmissions by APs in the same AP group to overlap. This allows APs in the same AP group to detect channel busy / idle when the same TBTT arrives, and in response to detecting channel idleness, they all wait for the same XIFS to transmit beacon frames, thus achieving simultaneous transmission of beacon frames.

[0029] In a second aspect, a communication device is provided for implementing the method of the first aspect. This communication device may be the access point (AP) as described in the first aspect, or a device or component included in the AP, such as a chip.

[0030] The communication device includes modules, units, or means that implement the methods described above. These modules, units, or means can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

[0031] In some possible implementations, the communication device may include a processing module and a transceiver module. The transceiver module may include a sending module and a receiving module, respectively used to implement the sending and receiving functions of the first aspect described above and any possible implementation thereof. For example, the transceiver module is used to send beacon frames. The processing module may be used to implement the processing functions of the first aspect described above and any possible implementation thereof. For example, the processing module is used to generate beacon frames.

[0032] Optionally, the transceiver module and processing module of the communication device in the second aspect may also perform the corresponding functions in the first aspect or any possible implementation of the first aspect, as detailed in the method examples, and the beneficial effects that can be achieved can also be found in the foregoing related content.

[0033] Thirdly, a communication device is provided, comprising: at least one processor configured to cause the communication device to perform the method described in any of the above aspects or possible implementations thereof by executing computer instructions stored in a memory or by logic circuitry. The communication device may be an access point (AP) in the first aspect or any possible implementation thereof, or a device or component included in the AP, such as a chip.

[0034] In some possible implementations, the communication device also includes a memory for storing configuration files of computer instructions and / or logic circuits. Optionally, the memory is integrated with the processor, or the memory is independent of the processor.

[0035] Fourthly, a communication device is provided, comprising: a processor and a communication interface; the communication interface being used for inputting and / or outputting signals; the processor being used to execute computer programs or instructions to cause the communication device to perform the method described in the first aspect. The communication device may be an access point (AP) in the first aspect or any possible implementation of the first aspect, or a device or component included in the AP, such as a chip.

[0036] In some possible implementations, the communication interface is an interface circuit used to read and write computer instructions. For example, the interface circuit is used to receive computer execution instructions (which are stored in memory and may be read directly from memory or may be transmitted through other devices) and transmit them to the processor.

[0037] In some possible implementations, the communication interface is used to communicate with modules outside the communication device.

[0038] In some possible implementations, the communication device can be a chip or a chip system. When the device is a chip system, the chip system may include chips or contain chips and other discrete components.

[0039] Fifthly, a communication device is provided, comprising: a logic circuit and an interface circuit; the interface circuit is used for inputting information and / or outputting information; the logic circuit is used to perform the method described in the first aspect, processing the input information and / or generating the output information. The communication device may be an access point (AP) in the first aspect or any possible implementation of the first aspect, or a device or component included in the AP, such as a chip.

[0040] In a sixth aspect, a computer-readable storage medium is provided, wherein a computer program or instructions are stored therein, which, when executed by a processor, cause the method described in the first aspect to be performed.

[0041] In a seventh aspect, a computer program product is provided, which, when executed by a processor, causes the method described in the first aspect to be performed.

[0042] It is understood that when the communication device provided by any of the second to seventh aspects is a chip, the above-mentioned sending action / function can be understood as output information, and the above-mentioned receiving action / function can be understood as input information.

[0043] The technical effects of any possible implementation of aspects two through seven can be found in the first aspect or any possible implementation of the first aspect, and will not be repeated here.

[0044] Eighthly, a communication system is provided, which includes the AP described in the first aspect or any possible implementation thereof. Attached Figure Description

[0045] Figure 1 is a schematic diagram of a network configuration with BSSID provided in an embodiment of this application;

[0046] Figure 2 is a schematic diagram of a site roaming trigger provided in an embodiment of this application;

[0047] Figure 3 is a timing diagram of a beacon frame transmission according to an embodiment of this application;

[0048] Figure 4 is a schematic diagram of a communication system provided in an embodiment of this application;

[0049] Figure 5 is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0050] Figure 6 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0051] Figure 7 is a timing diagram of simultaneous transmission of beacon frames provided in an embodiment of this application;

[0052] Figure 8 is a timing diagram of another simultaneous transmission of beacon frames provided in an embodiment of this application;

[0053] Figure 9 is a timing diagram illustrating another method for simultaneously transmitting beacon frames according to an embodiment of this application;

[0054] Figure 10 is a schematic diagram of multiple access points provided in an embodiment of this application;

[0055] Figure 11 is a schematic diagram of a process for determining a first candidate grouping method according to an embodiment of this application;

[0056] Figure 12 is a schematic diagram of the delay time for multiple access points to send beacon frames according to an embodiment of this application;

[0057] Figure 13 is a timing diagram of another method for simultaneously transmitting beacon frames according to an embodiment of this application;

[0058] Figure 14 is a timing diagram of another method for simultaneously transmitting beacon frames according to an embodiment of this application;

[0059] Figure 15 is a schematic diagram of an access point provided in an embodiment of this application;

[0060] Figure 16 is a schematic diagram of the structure of a communication device provided in an embodiment of this application. Detailed Implementation

[0061] Before introducing the embodiments of this application, some technical terms involved in the embodiments of this application will be explained. The following explanations are intended to make the embodiments of this application easier to understand, and should not be regarded as limiting the scope of protection claimed by the embodiments of this application.

[0062] 1. Wireless Local Area Network (WLAN)

[0063] With the rapid development of wireless LANs, the deployment of access points in enterprise-level WLAN networks is becoming increasingly dense to meet the indoor coverage needs of campus networks, corporate parks, automated production workshops, and hospitals. Enterprise-level WLAN networks commonly adopt the "thin AP" mode. In the "thin AP" mode, the devices in a WLAN network can include a wireless controller, access points, and sites. The wireless controller can be replaced by a WLAN controller, responsible for managing the access points. Optionally, the wireless controller can be an access controller (AC). The access points provide wireless access services based on the 802.11 standard to the sites. Sites are terminal devices that support the 802.11 standard, such as computers with wireless network cards or mobile phones that support WLAN.

[0064] 2. Beacon Frame

[0065] A beacon frame is a broadcast frame periodically sent by an access point. Beacon frames are primarily used by access points to periodically announce the existence of a wireless network (such as a WLAN) and various supported wireless parameters, such as Service Set Identifier (SSID), bandwidth, and authentication type. The period at which the access point sends beacon frames can be determined by the beacon interval, which refers to the time interval between beacon frame transmissions.

[0066] A beacon frame may include, but is not limited to, SSID, Basic Service Set Identifier (BSSID), and Traffic Indication Map (TIM). SSID is an identifier for a WLAN network, used to distinguish different WLAN networks. BSSID is typically the MAC address of an access point, used to uniquely identify an access point at the physical layer. TIM is an element in the beacon frame. TIM indicates which sites among the sites associated with the access point have data buffered in the access point awaiting transmission. TIM can also be a Delivery Traffic Indication Map (DTIM). DTIM indicates that data buffered in the access point is about to be transmitted. When a beacon frame includes a DTIM, sites in the WLAN network should be in a wake-up receiving state. For example, when the DTIM Count field under the TIM element is 0, the current TIM is a DTIM. The value of the DTIM Count field indicates how many beacon frames are needed for the next DTIM to appear.

[0067] According to the IEEE 802.11 protocol, access points do not need to perform a random backoff process when sending beacon frames (referred to as beacons). The beacon frame transmission procedure is as follows: When the target beacon transmission time (TBTT) arrives, the access point performs preparation operations for sending the beacon frame. After these preparation operations are completed, the beacon frame is sent. The preparation operations for sending the beacon frame include: at the TBTT, the access point checks whether the channel is busy or idle. If the channel is idle, it waits for the extended interframe space (XIFS) duration and then checks the channel again. If the channel is still idle, the preparation operation ends, and the beacon frame transmission begins. If the channel is detected to be busy, the access point must wait for the channel to become idle before performing the above process.

[0068] Therefore, it can be concluded that the access point needs at least XIFS time to travel from TBTT to the point where it can send a beacon frame.

[0069] In this context, TBTT can be protocol-defined, representing the time point at which a node (such as an access point) should send a beacon frame. Multiple TBTTs can be included, such as a first TBTT, a second TBTT, etc. For example, a node can use "zero point" as the starting TBTT, the first TBTT, or any other TBTT. When "zero point" arrives, it checks if the channel is busy or idle. If it detects that the channel is idle, after waiting for XIFS, the access point needs to send the first beacon frame. Further, using this "zero point" as a reference point / reference time point, after one beacon interval following this reference time point, the access point needs to send the second beacon frame, and so on. After one beacon interval following the transmission of the second beacon frame, the access point needs to send the third beacon frame, and so on. Here, "zero point" refers to the moment the node starts. The beacon interval refers to the period during which the access point should or needs to send beacon frames; that is, the beacon interval is the interval between adjacent TBTTs. The beacon interval of a beacon frame is carried within that beacon frame.

[0070] XIFS can be configured by the access point itself and can also be named frame interval wait time, minimum frame interval wait time, or other names without restriction. XIFS includes one of the following: Short Interframe Space (SIFS), Point Coordination Function Interframe Space (PIFS), or Distributed Coordination Function Interframe Space (DIFS). SIFS is the smallest frame interval in the 802.11 protocol, typically 16 microseconds (µs). SIFS is used for the highest priority information transmission, such as request-to-send (RTS) frames, clear-to-send (CTS) frames, and acknowledgement (ACK) frames. PIFS refers to the interframe interval in Point Coordination Function (PCF) mode, typically 25µs. The access priority of PIFS is only lower than that of SIFS. DIFS refers to the interframe interval in Distributed Coordination Function (DIFS) mode, typically 34µs.

[0071] 3. Wireless roaming (referred to as roaming)

[0072] In a WLAN network, to avoid service interruption during site movement, sites will roam. The site roaming process may include: when a site moves to the boundary area of ​​the coverage of two access points, the site associates with the new access point and disconnects from the original access point, and during this process, the site maintains an uninterrupted network connection, thus achieving uninterrupted communication service.

[0073] 4. Single frequency network (SFN)

[0074] Co-frequency networking is a networking method for WLAN networks. Co-frequency networking refers to dividing multiple access points in a WLAN network into a co-frequency group, where the access points within the same frequency group will operate on the same channel.

[0075] Co-frequency networking is a networking method to achieve "zero roaming." In co-frequency networking, multiple access points within a co-frequency group can be virtualized as a single "access point." This prevents a station from distinguishing between multiple access points within the same co-frequency group when moving within its coverage area, thus leading it to believe it is always associated with the same access point and eliminating the need for roaming, achieving the "zero roaming" effect. However, from the network side, the access points communicating with the station during its movement are multiple access points within the co-frequency network.

[0076] One approach is to use a shared BSSID scheme to virtualize multiple access points within the same frequency group as a single "access point," making it impossible for a site to distinguish between multiple access points within the same frequency network when moving within its coverage area. Specifically, this shared BSSID scheme includes: multiple access points in a WLAN network sending beacon frames with the same SSID and the same BSSID.

[0077] Whether an access point is in a co-frequency group can be preset. Furthermore, the BSSID associated with a co-frequency group is also pre-configured and unrestricted. Different co-frequency groups are associated with different BSSIDs, but all access points within a co-frequency group are associated with the same BSSID.

[0078] For example, as shown in Figure 1, the WLAN network includes an access controller (AC), access point 1 (AP1), access point 2 (AP2), access point 3 (AP3), station 1 (STA1), and station 2 (STA2). Access points 1, 2, and 3 are in the same frequency group. Station 1 is associated with access point 1, and station 2 is associated with access point 2. The BSSID in the beacon frames sent by each access point to station 1 in Figure 1 is BSSID1, and the BSSID in the beacon frames sent by each access point to station 2 in Figure 1 is also BSSID1. Therefore, even if an access point switches from AP1 to AP2, it is imperceptible to station 1 and will not trigger roaming.

[0079] As shown above, in a WLAN co-frequency network, different access points within the same frequency group can send beacon frames containing the same BSSID to a station, allowing the station to believe it is consistently associated with the same access point, achieving zero roaming. However, because the distances between different access points within the same frequency group and a single station vary, the signal strength of beacon frames received by a single station from different access points differs. The station can calculate the statistical values ​​of the signal strength of beacon frames containing the same BSSID sent by different access points. If the signal strength of the received beacon frames containing the same BSSID is lower than a preset threshold, the station is triggered to roam, leading to frequent channel scanning and reassignment to other access points with different BSSIDs. This can even cause the station to drop out of service, reducing communication reliability.

[0080] In this application, the statistical values ​​of signal strength may include, but are not limited to, the average signal strength, the variance of signal strength, and individual thresholds of signal strength. The individual thresholds of signal strength may refer to the maximum or minimum signal strength among the signal strengths. For ease of description, the following embodiments use the average signal strength as an example for the statistical value of signal strength, and this will be consistently applied throughout.

[0081] For example, Figure 2 is a schematic diagram of a WLAN co-frequency network. The devices in the WLAN co-frequency network shown in Figure 2 include an access controller, access point 1, access point 2, access point 3, access point 4, and a station. Access points 1, 2, 3, and 4 operate at the same frequency, meaning they are access points within the same frequency group. Access point 1 in Figure 2 is a timing access point; the clocks of access points 2, 3, and 4 are synchronized with the clock of access point 1. The station in Figure 2 is located below access point 1. Access point 1 sends beacon frame 1 containing BSSID 1, access point 2 sends beacon frame 2 containing BSSID 1, access point 3 sends beacon frame 3 containing BSSID 1, and access point 4 sends beacon frame 4 containing BSSID 1. The frame length of each beacon frame in Figure 2 is the same, for example, the frame length of each beacon frame is 536 microseconds (µs). In Figure 2, all beacon frames have the same transmission rate (referred to as beacon rate), such as 6 megabits per second (Mbps). The beacon intervals in all beacon frames in Figure 2 are also the same, such as 102.4 milliseconds (ms).

[0082] Specifically, the process of each access point sending beacon frames in Figure 2 can be seen in Figure 3. As shown in Figure 3, before each access point sends a beacon frame, access point 1 needs to send synchronization frames to access points 2, 3, and 4 to synchronize the clocks of access points 2, 3, and 4 with the clock of access point 1. After clock synchronization, each access point periodically sends beacon frames. The time interval T between adjacent beacon frames (or the beacon frame transmission period T) should be greater than the sum of the beacon frame length and the XIFS.

[0083] For example, assuming the beacon frame length is 536µs and the XIFS is 25µs, the transmission time interval T between adjacent beacon frames can be set to 600µs. Taking a transmission time interval T of 600µs and the statistical value of signal strength as the average signal strength as an example, as shown in Figure 3, access point 1 transmits beacon frame 1 at time t1, where t1 is the reference time and is an integer multiple of TBTT; access point 2 transmits beacon frame 2 at time t2, where t2 is a time after t1 delayed by T. In other words, the delay τ1 between t2 and t1 is equal to T, i.e., τ1 = 600µs; access point 3 transmits beacon frame 3 at time t3, where t3 is a time after t2 delayed by T. Therefore, the delay τ2 between t3 and t1 is equal to 2*T, i.e., τ2 = 1200µs; access point 4 transmits beacon frame 4 at time t4, where t4 is a time after t3 delayed by T. Therefore, the delay τ3 between t4 and t1 is equal to 3*T, i.e., τ3 = 1800µs.

[0084] In this example, the air interface overhead is at least the duration after all access points have sent beacon frames. In wireless communication systems, due to the technical characteristics of the air interface, some resources, such as time-domain resources, cannot be used for effective data transmission; this lost resource is the air interface overhead. Since a device in Figure 2 (such as any access point or station in Figure 2) can only send a data frame at time t5, at least after access point 4 has sent beacon frame 4 and XIFS has elapsed, t5 > t4 + 536µs + 25µs. Assuming t5 = t4 + 600µs, the air interface overhead is at least 2400µs.

[0085] In this example, access points 1 to 4 send beacon frames according to the timing sequence in Figure 3. Correspondingly, for the station, it can receive beacon frame 1, beacon frame 2, beacon frame 3, and beacon frame 4 according to the timing sequence in Figure 3. Furthermore, the station detects that the received signal strength indicator (RSSI) of beacon frame 1 is RSSI1, for example, -44 dBm; the RSSI of beacon frame 2 is RSSI2, for example, -56 dBm; the RSSI of beacon frame 3 is RSSI3, for example, -75 dBm; and the RSSI of beacon frame 4 is RSSI4, for example, -80 dBm. Subsequently, the station successfully demodulated beacon frames 1, 2, 3, and 4, and found that they all carried the same BSSID, BSSID1. The average value of RSSI1, RSSI2, RSSI3, and RSSI4 was calculated to be -63.75dBm. This average value is less than the preset threshold of -60dBm. The station judged the beacon frames including BSSID1 as weak signals, triggering the station to roam, which in turn triggered the station to frequently scan the channel in order to try to access other access points that could provide better signal strength for the station.

[0086] In this application, the process of a station demodulating a beacon frame may include: the station receiving a radio signal on the time-frequency resources where the AP transmits the beacon frame, the radio signal including the beacon frame modulated by the AP; when the station receives a beacon frame from the AP, it first determines whether the signal-to-interference-plus-noise ratio (SNR) of the beacon frame reaches the demodulation threshold. If the SNR of the received beacon frame is lower than the demodulation threshold, the station may not be able to correctly demodulate the beacon frame, resulting in the inability to obtain the content carried in the beacon frame.

[0087] The signal-to-noise ratio (SNR) of a beacon frame refers to the ratio of the received signal strength indication (or signal strength) of that beacon frame to the sum of the signal strengths of other signals on the channel during the transmission time of that beacon frame. The signal strength of the beacon frame itself is directly proportional to its SNR, while the SNR of the beacon frame is inversely proportional to the sum of the signal strengths of other signals. Other signals can be understood as signals transmitted on the channel simultaneously with the beacon frame, excluding the beacon frame itself. Specifically, other signals may include, but are not limited to, white noise or Gaussian white noise transmitted on the channel, and may also include other beacon frames or data frames, etc.

[0088] It should be understood that the demodulation threshold can be preset, for example, to 10dB. The level of the demodulation threshold directly affects the success rate of the site in demodulating beacon frames. If the demodulation threshold is set too high, some beacon frames with low signal-to-noise ratios may not be demodulated correctly; if the demodulation threshold is set too low, it may increase the bit error rate and affect the communication quality between the AP and the site.

[0089] As can be seen from the above, since the signal strengths of multiple beacon frames containing the same BSSID obtained by a station vary, there is a problem that the average signal strength of the calculated multiple beacon frames may be too low when there are multiple beacon frames with weak signal strength, thus triggering station roaming. Based on this, this application embodiment considers increasing the average signal strength of multiple beacon frames containing the same BSSID obtained by a station to reduce the probability of the average value being too low. For example, it considers that the station cannot resolve beacon frames with weak signal strength, so that beacon frames with weak signal strength are not included in the calculation of the average signal strength. For example, in the example above, RSSI1 and RSSI2 are greater than the preset strength threshold, indicating relatively strong signal strength, while RSSI3 and RSSI4 are less than the preset strength threshold, indicating relatively weak signal strength. RSSI3 and RSSI4 are the main factors triggering the station to frequently scan the channel. This application embodiment can design a scheme to prevent the station from demodulating beacon frames 3 and 4, thereby reducing the probability of the station roaming and frequently scanning the channel.

[0090] Based on the foregoing analysis, embodiments of this application provide a communication method. This method is applied to a communication network comprising multiple access points associated with the same BSSID, or in other words, it is applied to a co-frequency network within the communication network. In this method, at least two of the multiple access points generate beacon frames including the same BSSID, and at least two access points simultaneously transmit beacon frames including the same BSSID, thereby enabling the station to simultaneously receive at least two beacon frames including the same BSSID.

[0091] As discussed above, when a station receives multiple beacon frames simultaneously, the signal-to-noise ratio (SNR) of one of these beacon frames can be considered the ratio of its signal strength to the noise (signal strength of other beacon frames + signal strength of white noise). In other words, the other beacon frames can be viewed as interference signals, becoming noise energy that affects the demodulation of this beacon frame. If the signal strength of the beacon frame is weak, demodulation will be severely affected, resulting in a low SNR that the station cannot successfully demodulate. Conversely, if the signal strength is strong, the SNR of the beacon frame will be high. The beacon frame will not be affected and can be successfully demodulated by the station. In other words, when a station receives multiple beacon frames at the same time, some beacon frames will be successfully demodulated by the station, while others will not be demodulated. This phenomenon can be called a "collision" between beacon frames sent by at least two access points. This phenomenon causes the station to demodulate and obtain the content of the beacon frame with the larger signal strength (or high signal strength) among the beacon frames sent at the same time, but it cannot demodulate and obtain the content of the beacon frame with the smaller signal strength (or weak signal strength) among the beacon frames sent at the same time.

[0092] In this application, a beacon frame with a signal strength greater than a preset strength threshold can be called a strong beacon frame, and a beacon frame with a signal strength less than or equal to the preset strength threshold can be called a weak beacon frame.

[0093] In this application, beacon frames that are not successfully demodulated by the station among multiple beacon frames transmitted simultaneously can be referred to as "collision-dropped" beacon frames or "cancelled" beacon frames. For collision-dropped beacon frames, the station cannot obtain the content contained in the beacon frame, such as the BSSID contained in the beacon frame, and therefore cannot identify whether the beacon frame contains the same BSSID. This means that when calculating the average signal strength of beacon frames containing the same BSSID, the signal strength of collision-dropped beacon frames will not be included in the calculation of the average signal strength.

[0094] Since the signal strength of beacon frames that are knocked down is generally low, they are considered weak beacon frames. If the weak beacon frames that are knocked down among multiple beacon frames containing the same BSSID are not included in the calculation of the average signal strength, the average signal strength of multiple beacon frames containing the same BSSID will be increased. This will reduce the probability that the site will determine the beacon frames carrying the same BSSID as weak signals based on the average signal strength, thereby reducing the probability of site roaming and frequent channel scanning.

[0095] The communication method provided in this application embodiment is applicable to WLANs that support the relevant standards of the Institute of Electrical and Electronics Engineers (IEEE). These IEEE standards include: 802.11a / b / g, 802.11n, 802.11ac, 802.11ax, 802.11be, 802.11bn / Ultra High Resolution (UHR) / Wireless-Fidelity (Wi-Fi) 8, 802.11ad, 802.11ay, 802.11bf / sensing, Ultra Wideband (UWB) / 802.15, and subsequent related evolution standards, without limitation.

[0096] As exemplarily shown in Figure 4, this application provides a schematic diagram of a communication system. The communication system shown in Figure 4 includes multiple access points and stations. One access point can communicate with one or more stations, which is not limited in this application.

[0097] As shown in Figure 4, all access points in a group can be associated with the same BSSID and located in the same frequency group. All access points in the same frequency group will send beacon frames. Alternatively, multiple access points can be associated with the same BSSID and located in the same frequency group. Some access points in the same frequency group will send beacon frames, without restriction.

[0098] Taking multiple access points in Figure 4, including access point 1, access point 2, access point 3, access point 4, and access point 5, located in the same frequency group, as an example: In one example, access points 1, 2, 3, 4, and 5 in Figure 4 all transmit beacon frames. In another example, access points 1, 4, and 5 in Figure 4 transmit beacon frames.

[0099] For example, an access point can be a device that supports multiple WLAN standards, such as the 802.11be standard or future Wi-Fi standards; it can also be a device that supports 802.11a / b / g standards, 802.11n standards, 802.11 wireless controller standards, 802.11ax standards, 802.11be standards, 802.11bn standards / UHR standards / Wi-Fi 8 standards, without limitation. For instance, an access point can be a terminal device with a Wi-Fi chip, network device, communication server, router, switch, bridge, computer, etc. Access points serve as the entry point for mobile users to access a wired network, primarily deployed in homes, buildings, and campuses, with a typical coverage radius of tens to hundreds of meters. Of course, they can also be deployed outdoors. An access point acts as a bridge connecting wired and wireless networks, its main function being to connect various wireless network clients to the wireless network and then connect the wireless network to other networks, such as Ethernet.

[0100] For example, a site can be a device that supports multiple WLAN standards, such as the 802.11be standard or future Wi-Fi standards; it can also be a device that supports 802.11a / b / g standards, 802.11n standards, 802.11 wireless controller standards, 802.11ax standards, 802.11be standards, 802.11bn standards / UHR standards / Wi-Fi 8 standards, without limitation. For example, a site can be a wireless communication chip, wireless sensor, wireless communication terminal, communication server, router, switch, bridge, computer, etc. For example, a site can be a mobile phone with Wi-Fi communication function, a tablet computer with Wi-Fi communication function, a set-top box with Wi-Fi communication function, a smart TV with Wi-Fi communication function, a smart wearable device with Wi-Fi communication function, an in-vehicle communication device with Wi-Fi communication function, and a computer with Wi-Fi communication function, without limitation.

[0101] Optionally, the communication system shown in Figure 4 may further include a wireless controller. The wireless controller is a device responsible for managing the access points; for example, the wireless controller may be an AC (Access Controller). The wireless controller can manage one or more access points, and this application is not limited in this regard. The wireless controller may include a unit with data processing capabilities.

[0102] The communication system described in this application is intended to more clearly illustrate the technical solutions of this application and does not constitute a limitation on the technical solutions provided in this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in this application are also applicable to similar technical problems.

[0103] In specific implementation, the access point and station shown in Figure 4 can both adopt the composition structure shown in Figure 5, or include the components shown in Figure 5. Figure 5 is a schematic diagram of the composition of a communication device 50 provided in an embodiment of this application. The communication device 50 can be an access point or a chip or system-on-a-chip in the access point; it can also be a station or a chip or system-on-a-chip in the station.

[0104] As shown in Figure 5, the communication device 50 includes one or more processors 501. Further, the communication device 50 may also include a communication bus 502 and at least one communication interface 504 (Figure 5 is merely exemplary, illustrating the communication device 50 with a communication interface 504 and a processor 501 as an example). Optionally, the communication device 50 may also include a memory 503.

[0105] Processor 501 can be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the program according to the present application, or a processing core for processing data (e.g., computer program instructions). The processor can be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. In a specific implementation, as one embodiment, processor 501 may include one or more CPUs, such as CPU0 and CPU1 in Figure 5.

[0106] The communication bus 502 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This bus can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is used in Figure 5, but this does not mean that there is only one bus or one type of bus. The communication bus 502 is used to connect different components in the communication device 50, enabling communication and interaction between these components.

[0107] The communication interface 504 can be a transceiver module used to communicate with other devices or communication networks, such as Ethernet, radio access network (RAN), or WLAN. For example, the communication interface 504 can be a transceiver or similar device. Alternatively, the communication interface 504 can also be a transceiver circuit located within the processor 501, used to implement signal input and signal output for the processor.

[0108] Memory 503 can be a device with storage function. For example, it can be read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions; random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions; electrically erasable programmable read-only memory (EEPROM); compact disc read-only memory (CD-ROM) or other optical disc storage; optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.); magnetic disk storage media or other magnetic storage devices; or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. Memory can exist independently and be connected to the processor via communication bus 502. Memory can also be integrated with the processor.

[0109] For example, memory 503 is used to store computer execution instructions for implementing the scheme of this application, and the execution is controlled by processor 501. Processor 501 is used to execute the computer execution instructions stored in memory 503, thereby implementing the methods provided in the embodiments of this application. For example, processor 501 performs processing-related functions in the methods provided in the following embodiments of this application, and processor 501 controls communication interface 504 to perform communication with other devices or communication networks, which are not specifically limited in the embodiments of this application.

[0110] Optionally, the computer execution instructions in the embodiments of this application may also be referred to as application code, without specific limitation.

[0111] In a specific implementation, as one embodiment, the communication device 50 may further include an output device 505 and an input device 506. The output device 505 communicates with the processor 501 and can display information in various ways. For example, the output device 505 may be a liquid crystal display (LCD), a light-emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector, etc. The input device 506 communicates with the processor 501 and can receive user input in various ways. For example, the input device 506 may be a mouse, keyboard, touchscreen device, or sensing device, etc.

[0112] The composition shown in Figure 5 does not constitute a limitation on the communication device. In addition to the components shown in Figure 5, the communication device may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0113] The communication method provided in this application embodiment will be described in detail below with reference to Figure 6. Figure 6 shows an interaction diagram of a communication method provided in this application. This communication method is described using the interaction between an access point and a station as an example. For example, this communication method is applied to the communication network shown in Figure 4. The communication network may include one or more co-frequency groups, and a co-frequency group may include multiple access points. The multiple access points included in a co-frequency group are associated with the same BSSID. This application describes the process of multiple access points within a co-frequency group sending beacon frames as an example. Referring to Figure 6, this communication method includes steps S601 and S602.

[0114] S601: At least two of the multiple access points generate beacon frames.

[0115] The beacon frame may carry the BSSID and other radio parameters. Specifically, the information that the beacon frame may include is as described above, and the beacon frame generation process can refer to existing technologies, which will not be elaborated here.

[0116] In this application, multiple access points can all be located in the same frequency group, and the BSSIDs carried in the beacon frames generated by access points in the same frequency group are all the same. In this application, the fact that the BSSIDs carried in the beacon frames generated by access points are the same can be understood as the BSSIDs associated with the access points being the same.

[0117] In this application, at least two of the multiple access points generate beacon frames with the same frame length.

[0118] In this application, to ensure that at least two of the multiple access points operate according to a unified time standard, clock synchronization is required between the multiple access points before the method shown in Figure 6, to ensure that the clocks of the multiple access points are synchronized. Specifically, the clock synchronization process may include: each access point acquiring a synchronization signal, adjusting its own clock according to the synchronization signal, and adjusting its own clock to the time indicated by the synchronization signal.

[0119] In one example, the access point can receive a synchronization signal from a reference access point. That is, the synchronization signal can originate from the reference access point.

[0120] The reference access point can be a timing access point, which can be a pre-set access point or a selected access point from multiple access points. It should be understood that when the reference access point is selected from multiple access points, the acquisition of the synchronization signal by the access point can be described as the access point generating the synchronization signal, for example, generating a synchronization signal based on its own clock. In this case, the access point does not need to adjust its own clock. Instead, after generating the synchronization signal, it encapsulates the synchronization signal into a synchronization frame and sends it to all other access points. Upon receiving the synchronization frame, each access point parses it and adjusts its own clock based on the clock information carried in the synchronization frame, thereby synchronizing the clocks of all its access points with the timing access point.

[0121] In another example, the access point can receive synchronization signals from Global Positioning System (GPS) satellites. That is, the synchronization signals originate from GPS satellites.

[0122] For example, before multiple access points send beacon frames, they receive time signals from GPS satellites and use these signals to precisely calibrate their local clocks, thereby ensuring that the local clocks of multiple access points are synchronized with global standard time.

[0123] S602: At least two of the multiple access points simultaneously transmit the generated beacon frames; correspondingly, the station receives beacon frames from at least two of the multiple access points.

[0124] In this application, multiple access points are located in a co-frequency group, and the multiple access points in the co-frequency group operate on the same channel, that is, they share the same channel. The transmission of beacon frames by at least two of the multiple access points in S602 can be understood as at least two of the multiple access points transmitting beacon frames on the same channel. For any one of the multiple access points, that access point can periodically transmit beacon frames; within one transmission period, that access point can generate and transmit one beacon frame.

[0125] As mentioned above, collisions can occur between simultaneously transmitted beacon frames, knocking out the beacon frames with weaker signal strength. To achieve this collision effect, in this application, "at least two access points simultaneously transmitting beacon frames" can refer to at least two access points simultaneously transmitting beacon frames on the same channel. "At least two access points simultaneously transmitting beacon frames" can be understood as the transmission times of at least two access points overlapping. This overlap can include partial or complete overlap, without limitation. The transmission time of the beacon frames can be determined based on the beacon frame length. Optionally, the transmission time of the beacon frames (or the transmission duration of the beacon frames / the transmission duration of the beacon frames) is equal to or greater than the beacon frame length.

[0126] In this application, access points that simultaneously transmit beacon frames can be located in the same AP group. Optionally, a co-frequency group can include one or more AP groups, that is, the multiple access points in the method shown in Figure 6 can be divided into at least one AP group. An AP group can include one access point or at least two access points. There is at least one AP group in the co-frequency group that includes at least two access points, and the at least two access points that simultaneously transmit beacon frames can be located in the same AP group. The access points in different AP groups are different, and the number of access points in different AP groups can be the same or different. The timing of beacon frame transmission by access points in the same AP group overlaps, that is, there are at least two access points in the same AP group that transmit beacon frames simultaneously. The timing of beacon frame transmission by access points in different AP groups is different or the timing of beacon frame transmission by access points in different AP groups does not overlap, and the transmission of beacon frames by access points in different AP groups will not collide.

[0127] For example, a co-frequency group includes 6 access points AP1-AP6. These 6 access points can be divided into 3 AP groups: the first AP group (AP1-AP2), the second AP group (AP3-AP5), and the third AP group (AP6). AP1 and AP2 in the first AP group send beacon frames simultaneously, and AP3, AP4, and AP5 in the second AP group send beacon frames simultaneously. The timing of beacon frame transmission by AP1 and AP2 in the first AP group, the timing of beacon frame transmission by AP3, AP4, and AP5 in the second AP group, and the timing of beacon frame transmission by AP6 do not overlap. Alternatively, these 6 access points can be divided into 2 AP groups: the first AP group (AP1-AP3) and the second AP group (AP4-AP6). AP1, AP2, and AP3 in the first AP group send beacon frames simultaneously, and AP4, AP5, and AP6 in the second AP group send beacon frames simultaneously. The timing of beacon frame transmission by AP1, AP2, and AP3 in the first AP group does not overlap with the timing of beacon frame transmission by AP4, AP5, and AP6 in the second AP group.

[0128] Optionally, to ensure that the beacon frame transmission times of access points between AP groups do not overlap, for two AP groups with adjacent beacon frame transmission times, the time interval between beacon frame transmissions by access points in these two adjacent AP groups can be greater than or equal to the sum of the beacon frame length and the XIFS value. Adjacent AP groups refer to two AP groups where the APs in the two groups transmit beacon frames at adjacent times. This ensures that there is a time interval between beacon frames transmitted by access points in different AP groups, preventing overlapping transmission times and collisions.

[0129] For a detailed description of XIFS, please refer to the above text, which will not be repeated here.

[0130] For example, suppose there are 6 access points (AP1-AP6) in a co-frequency group, and these 6 access points are divided into 3 AP groups: AP group 1, AP group 2, and AP group 3. The APs in an AP group send beacon frames at the same start time. APs in AP group 1 send beacon frames at time t1, APs in AP group 2 all send beacon frames at time t2, and APs in AP group 3 all send beacon frames at time t3. The time interval between t1 and t2 is less than the time interval between t1 and t3. Therefore, AP group 1 and AP group 2 are adjacent AP groups, and AP group 2 and AP group 3 are adjacent AP groups. Assume that the beacon frames sent by multiple access points have the same frame length, such as T. frame To avoid collisions between beacon frames sent by APs in different AP groups, time t2 can be delayed by T from time t1. frame After +XIFS, time t3 is a delay of time t2 by T. frame The moment after +XIFS.

[0131] Specifically, the grouping method of multiple access points in the method shown in Figure 6 can be found in Methods 1-3 below, and will not be repeated here.

[0132] Optionally, for an AP group containing one access point, the access point in the AP group may send beacon frames using the beacon frame transmission mechanism specified in the existing 802.11 protocol. Optionally, for an AP group containing at least two access points, the access points in the AP group may send beacon frames using either of the following two possible implementations:

[0133] In the first possible implementation, at least two access points simultaneously detect whether the channel is busy or idle, and send a beacon frame in response to detecting that the channel is idle.

[0134] Specifically, each of the at least two access points can refer to the beacon frame transmission mechanism specified in the 802.11 protocol above: upon arrival of the TBTT, the access point performs a preparation operation to transmit the beacon frame, and transmits the beacon frame after the preparation operation is completed. The preparation operation for the access point to transmit the beacon frame includes: at the TBTT time, the access point checks whether the channel is busy or idle. If the channel is idle, it waits for the XIFS duration and then checks whether the channel is busy or idle again. If the channel is still idle, the preparation operation ends and the beacon frame is transmitted. If the channel is detected to be busy, the access point needs to wait for the channel to be idle before performing the above process. Access points in the same AP group share the same XIFS, that is, for access points in the same AP group, they can transmit the beacon frame at the same XIFS duration after detecting that the channel is idle.

[0135] In the first possible implementation, the TBTT (Transmission Time To Watch) of each of the at least two access points is the same, meaning that each of the at least two access points can simultaneously detect channel busy / idle status in response to the arrival of the TBTT. Since the at least two access points operate on the same channel, the busy / idle status detected by different access points on that same channel is the same. Ignoring the detection capability / detection duration of the at least two access points, these at least two access points can simultaneously detect that the channel is idle and simultaneously transmit beacon frames when the channel is idle.

[0136] The access point's channel busy / idle detection can include periodically detecting channel busy / idle status until an idle channel is detected. For example, when the first channel detection time arrives, the access point checks whether the channel is busy / idle. If the channel is idle, the detection is terminated, and the access point waits for XIFS before checking the channel busy / idle status again. If the access point detects that the channel is busy when the first channel detection time arrives, the access point continues to check whether the channel is busy / idle when the second channel detection time arrives, and so on.

[0137] Here, the channel detection time can refer to the moment when the channel is busy or idle, and the time interval between adjacent channel detection times can be called the channel busy / idle detection interval. The channel busy / idle detection interval can be specified by the protocol, or it can be described as a channel busy / idle detection time window, a minimum time unit for channel busy / idle detection, or a minimum unit for channel busy / idle detection. Optionally, the channel busy / idle detection interval is set to a time slot length of 9µs.

[0138] In the first possible implementation, in order to ensure that at least two access points send beacon frames simultaneously, the clocks of at least two access points need to be strictly synchronized. For example, the clock synchronization error after the clocks of at least two access points are synchronized needs to be less than the channel busy / idle detection interval. In this way, even if there is a clock synchronization error between at least two access points, it can be guaranteed that at least two access points will perform channel busy / idle detection within one channel busy / idle detection interval. Since the channel busy / idle detection interval is relatively short, the channel busy / idle detection performed by at least two access points within one channel busy / idle detection interval can be approximated as simultaneous channel detection, so that at least two access points detect the same channel state, such as both detecting that the channel is idle.

[0139] For example, taking the WLAN co-frequency networking shown in Figure 2 as an example, the access points in Figure 2 send beacon frames according to the timing sequence shown in Figure 7. The timing access point in Figure 7, i.e., access point 1 in Figure 7, sends a synchronization frame to the other access points in Figure 7 before each access point in Figure 7 sends a beacon frame, so that the clocks of the other access points in Figure 7 are synchronized with the clock of the timing access point in Figure 7. Assume that access points 1 and 3 in Figure 7 are located in one AP group, and access points 2 and 4 in Figure 7 are located in another AP group, and the access points in one AP group send beacon frames simultaneously. The process of access points in different AP groups in Figure 7 sending beacon frames simultaneously can include: each access point in Figure 7 performs channel detection before time t1, and the detection result is that the channel is idle. Access points 1 and 3 compete for the channel and send beacon frames simultaneously at time t1; subsequently, access points 2 and 4 send beacon frames simultaneously at time t2, which is a time after a delay from time t1. Time t2 can be a time greater than time t1 + the frame length of the beacon frame + XIFS. Assuming the beacon frame length is 536µs and the XIFS is 25µs, then time t2 can be the time corresponding to t1+600µs.

[0140] In this example, beacon frames 1 and 3, transmitted simultaneously at time t1, will collide, and beacon frames 2 and 4, transmitted simultaneously at time t2, will collide. As mentioned above, the beacon frame with the weaker signal strength among the colliding beacon frames will be dropped, and the station cannot successfully resolve the weaker signal strength beacon frame among the colliding beacon frames. Based on this principle, if the station can only successfully resolve the BSSID carried in beacon frame 1 at time t1 and the BSSID carried in beacon frame 2 at time t2, but cannot resolve the BSSID carried in beacon frames 3 and 4, then the station can only determine whether to trigger roaming based on the average signal strength of beacon frames 1 and 2. Since the signal strengths of beacon frames 1 and 2 are relatively large, their average signal strength is also relatively large. Based on the average signal strength of beacon frames 1 and 2, the station in Figure 7 will not be triggered to roam, and thus will not be triggered to frequently scan the channel.

[0141] In the first possible implementation, it can be guaranteed that the beacon frames sent by access points between AP groups do not collide or that the timing of beacon frame transmission does not overlap by either of the following two examples: In one example, the TBTT of access points between AP groups is the same, but the timing of the preparation operation for sending beacon frames by access points between different AP groups is different, so the timing of beacon frame transmission between different AP groups does not overlap.

[0142] For example, in one of the adjacent AP groups, each AP begins the preparation operation for sending a beacon frame when the TBTT arrives. The XIFS (Multiple Components of the Beacon Frame) in the preparation operation is the same for each AP, thus ensuring that each AP sends a beacon frame at the same time. In another AP group, each AP begins the preparation operation for sending a beacon frame at a time after a first delay from the TBTT, where the duration of the first delay is greater than or equal to the sum of the beacon frame length and the XIFS. The XIFS in the preparation operation is the same for each AP, thus ensuring that each AP sends a beacon frame at the same time. Thus, sending beacon frames according to the first possible implementation method ensures that the time interval between beacon frame transmissions by access points in adjacent AP groups is greater than or equal to the sum of the beacon frame length and the XIFS, the transmission times of access points between AP groups do not overlap, and the transmitted beacon frames will not collide.

[0143] In another example, the TBTT of access points in different AP groups is different. For example, the time interval of TBTT of access points in adjacent AP groups can be greater than or equal to the sum of the beacon frame length and XIFS. In this way, sending beacon frames in accordance with the first possible implementation method can ensure that the time interval of beacon frame sending by access points in adjacent AP groups is greater than or equal to the sum of the beacon frame length and XIFS, and the time of beacon frame sending by access points in different AP groups does not overlap, so the sent beacon frames will not collide.

[0144] In a second possible implementation, each of at least two access points simultaneously sends a CTS frame to each station it serves to inform the stations that the channel for sending beacon frames is occupied and that stations are not allowed to send data frames, etc., on the beacon frame channel. The access point then sends the beacon frame after sending the CTS frame.

[0145] In this application, each of the at least two access points can send a CTS frame at a time predefined by the protocol or a negotiated time, thus enabling simultaneous transmission of CTS frames. The access points do not need to check channel busy / idle status before sending the CTS frame; they simply send the CTS frame when the specified time arrives. Correspondingly, for the station, it can simultaneously receive CTS frames sent by at least two access points, parse the received CTS frames from both access points, and determine from the successfully parsed CTS frames that the channel is occupied, thus preventing the station from sending data frames on that channel.

[0146] It should be understood that the CTS frames of at least two access points sent simultaneously in this application will have a collision effect. That is, the CTS frame with weaker signal strength among the CTS frames of at least two access points has a lower signal-to-noise ratio and is knocked away and cannot be parsed by the station. The CTS frame with stronger signal strength among the CTS frames of at least two access points has a higher signal-to-noise ratio and can be successfully parsed by the station.

[0147] Specifically, each of at least two access points can send a beacon frame after a preset time interval following the transmission of a CTS frame. The preset time intervals for at least two access points are the same. Optionally, the preset time interval is greater than or equal to (the frame length of the CTS frame + XIFS). The XIFS intervals for different access points among the at least two access points are the same.

[0148] In the second possible implementation, the timing of beacon frame transmissions by at least two access points does not need to be strictly synchronized. Optionally, the clock synchronization error requirement in the second possible implementation can be lower than that in the first possible implementation; for example, the clock synchronization error between different access points among the at least two access points in the second possible implementation can be 20µs.

[0149] In this way, a CTS (Content Transmission System) can be broadcast in advance to notify users not to send data and occupy the channel. After a preset time has elapsed since the CTS is sent, a beacon frame is sent. Since each beacon frame has a certain length and the length of the beacon frame is greater than the clock synchronization error, even if there is a clock synchronization error between at least two access points, it can be guaranteed that the beacon frames sent by at least two access points after the preset time has elapsed since the CTS is sent will overlap in time, that is, the beacon frames will be sent simultaneously and collide with each other.

[0150] For example, taking the WLAN co-frequency networking shown in Figure 2 as an example, the access points in Figure 2 send beacon frames according to the timing sequence shown in Figure 8. The difference between the timing sequence shown in Figure 8 and that in Figure 7 is that, in Figure 8, each access point simultaneously sends a CTS frame at a certain moment after clock synchronization, such as time t0, while in Figure 7, each access point performs channel busy / idle detection after clock synchronization. Further, as shown in Figure 8, access points 1 and 3 simultaneously send beacon frames at time t1, and access points 2 and 4 simultaneously send beacon frames at time t2. Time t1 is greater than time t0 + the frame length of the CTS frame + XIFS, and time t2 is greater than time t1 + the frame length of the beacon frame + XIFS. Assuming the beacon frame length is 536µs and the XIFS is 25µs, then time t2 can be the time corresponding to t1 + 600µs. The beacon frame collision phenomenon achieved by the access point in Figure 2 sending beacon frames according to the timing shown in Figure 8 is the same as the beacon frame collision phenomenon achieved by the access point in Figure 2 sending beacon frames according to the timing shown in Figure 7, and will not be described again here.

[0151] In the second possible implementation, to ensure that beacon frames sent by access points between AP groups do not collide or overlap in time, in one example, the CTS frames sent by access points between AP groups are sent at different times. For example, the time interval between CTS frames of access points in adjacent AP groups can be greater than or equal to the sum of the beacon frame length and XIFS. In this way, sending beacon frames according to the second possible implementation method can ensure that the time interval between beacon frames sent by access points in adjacent AP groups is greater than or equal to the sum of the beacon frame length and XIFS, and the time of beacon frame sending by access points between AP groups does not overlap, so the sent beacon frames will not collide.

[0152] In another example, the CTS frames of access points in different AP groups are sent at the same time, but the preset duration after sending the CTS frame is different. This will cause access points in different AP groups to send beacon frames at different preset durations after sending the CTS frame, so that the time of sending beacon frames by access points in adjacent AP groups does not overlap and the sent beacon frames will not collide.

[0153] Based on the method shown in Figure 6, at least two access points among multiple access points simultaneously transmit beacon frames, causing collisions between the simultaneously transmitted beacon frames. This allows the station to successfully demodulate the beacon frame with the higher signal strength among the collided beacon frames, while failing to successfully demodulate the beacon frame with the lower signal strength among the collided beacon frames. The station determines whether to trigger roaming based on the beacon frame with the higher signal strength among the collided beacon frames, thereby reducing the probability of triggering station roaming and station frequent channel scanning.

[0154] As mentioned above, the signal-to-noise ratio (SNR) of a beacon frame is the ratio of the received signal strength indication (or signal strength) of the beacon frame to the signal strength of other signals (including noise and other beacon frames) on the channel during the transmission time of that beacon frame. Based on the interpretation of SNR, one possible scenario is that if a station simultaneously receives beacon frames from at least two access points with similar signal strengths, the SNR of each beacon frame from those access points will be small and similar. This results in the SNR of each beacon frame from those access points being lower than the station's demodulation threshold. Consequently, the station fails to demodulate each beacon frame from those access points, and at that time, the station cannot obtain the information carried by any of the beacon frames from those access points, resulting in a beacon frame loss (BCN miss) phenomenon. Therefore, the station cannot perceive the existence of the 802.11 network at that time.

[0155] In practical applications, beacon frame loss can occur not only due to the low signal-to-noise ratio of beacon frames, but also because the access point's transmission power is too low to transmit the beacon frames to the station, resulting in beacon frame loss.

[0156] There are two main reasons for beacon frame loss: 1. The station receives the beacon frame but is unable to demodulate it. 2. The station cannot receive the beacon frame at all. To address these different reasons, the occurrence of beacon frame loss can be reduced by increasing the beacon frame transmission power and / or lowering the station's demodulation threshold.

[0157] Scenario 1: Each of at least two access points increases its transmission power to send beacon frames at a higher power, thereby increasing the transmission distance of the beacon frames and ensuring that the beacon frames sent by the access points are received by the stations.

[0158] Optionally, the transmission power of an access point can refer to the magnitude of the electromagnetic wave energy generated and radiated by the access point. The transmission power used by the access point when transmitting a signal is proportional to the transmission distance of the signal transmitted by that access point. The transmission distance can refer to the farthest distance from the transmitting end to the receiving end while maintaining effective communication. The higher the transmission power of the access point, the greater the transmission distance of the signal transmitted by that access point; conversely, the lower the transmission power of the access point, the smaller the transmission distance of the signal transmitted by that access point.

[0159] Thus, when each of at least two access points transmits beacon frames at maximum transmission power, the transmission distance of each beacon frame transmitted by each access point will be greater. With a fixed distance between the access point and the station, increasing the transmission power of an access point allows the beacon frame to be transmitted over a longer distance, reaching the station and increasing the probability that the station will receive the beacon frame. This increases the probability that the station will receive beacon frames transmitted by each of the at least two access points, thereby reducing the probability that the station will not receive beacon frames and minimizing beacon frame loss due to unreceived beacon frames.

[0160] Optionally, in this application, the increased transmission power of each of the at least two access points can be the same. For example, each access point can use the same higher transmission power to transmit beacon frames.

[0161] In this application, the signal strength of the signal (such as a beacon frame) received by the station from the access point is related to parameters such as the signal's transmission power, the access point's antenna gain, the path loss (or path drop) between the access point and the station, obstacle attenuation, and the station's antenna gain. For example, the signal strength of the signal received by the station from the access point = signal transmission power + access point antenna gain - path loss - obstacle attenuation + station antenna gain. From this relationship, it can be seen that the signal strength of the signal received by the station from the access point is directly proportional to the access point's transmission power. When other parameters except the access point's transmission power remain constant, the higher the access point's transmission power, the stronger the signal; conversely, the lower the access point's transmission power, the weaker the signal.

[0162] As mentioned above, the signal-to-noise ratio (SNR) of a beacon frame is 10 * log10 (signal strength of the beacon frame / received power of the noise). For any beacon frame transmitted simultaneously by at least two access points, the signal strength of the noise is the sum of the signal strengths of the other beacon frames and the signal strength of the white noise. For beacon frames not transmitted simultaneously with other beacon frames, the signal strength of the noise is the same as the signal strength of the white noise.

[0163] Therefore, assuming the signal strength of white noise on the channel remains constant, if the transmission power of the access point increases and the access point does not transmit beacon frames simultaneously with other beacon frames, the signal-to-noise ratio of the beacon frames received by the station from the access point will increase with the increase of transmission power. When the transmission power of an access point increases, and that access point simultaneously transmits beacon frames with at least one other access point at the increased transmission power (i.e., multiple access points simultaneously transmit beacon frames with increased transmission power), the signal strength of the beacon frames received by the station from each of the multiple access points increases. When calculating the beacon frame of a certain beacon frame using the aforementioned signal-to-noise ratio (SNR) calculation formula, if the signal strength of white noise is ignored, both the numerator and denominator in the calculation formula increase, and may even increase proportionally. Thus, for each of the at least two access points simultaneously transmitting beacon frames, the difference between the SNR of the beacon frame transmitted by that access point using the same higher transmission power and the SNR of the beacon frame transmitted by that access point using the same lower transmission power is small, or even the same. This ensures that the simultaneous transmission of beacon frames with increased transmission power by at least two access points does not affect the collision effect when the beacon frames of at least two access points are transmitted simultaneously, or has a small impact on the collision effect when the beacon frames of at least two access points are transmitted simultaneously.

[0164] Scenario 2: Adjust the demodulation threshold.

[0165] The station can set a lower demodulation threshold, so that the signal-to-noise ratio (SNR) of most beacon frames received from at least two access points is greater than the demodulation threshold, while the SNR of a small portion of the beacon frames received from at least two access points is less than the demodulation threshold. This means that a small portion of the beacon frames cannot be demodulated, and the station will not encounter the problem of not being able to parse the information carried by any beacon frame at the same time, thereby reducing the occurrence of beacon frame loss.

[0166] Meanwhile, in scenario two, each of the at least two access points transmits beacon frames using the same high transmission power to ensure that most beacon frames received by the site have a high received power, i.e., most beacon frames have a high signal strength. This ensures that the signal strength of beacon frames containing the same BSSID resolved by the site is high, and site roaming will not be triggered.

[0167] Optionally, a demodulation threshold can be set based on the access point's transmission rate. At high transmission rates, the site's demodulation threshold needs to be set relatively high, while at low transmission rates, it typically doesn't need to be set very high. For example, at a transmission rate of 6 Mbps, the minimum demodulation threshold can be 0 dBm, and at a transmission rate of 54 Mbps, the minimum demodulation threshold can be 30 dBm. The access point's transmission rate can be pre-configured for the site.

[0168] The grouping method for multiple access points in the method shown in Figure 6 can include any of the following grouping methods: Method 1 to Method 3. Specifically, the grouping method can be preset or determined by the management node; there are no restrictions. The management node can be a node that manages multiple access points, such as a wireless controller or AC, or simply one of the multiple access points. Methods 1 to 3 are described below:

[0169] Method 1: Multiple access points are located in one AP group, that is, all access points in the same frequency group are located in the same AP group.

[0170] At this time, at least two access points in the AP group can send beacon frames in accordance with the first or second possible implementation in S902 above, so that at least two access points among multiple access points can send beacon frames at the same time.

[0171] In the first possible implementation of S902 above, the TBTT of each access point in the AP group is the same, the XIFS of each access point is the same, and the frame length of the beacon frames sent is the same.

[0172] In the second possible implementation described in S902 above, each access point in the AP group sends a CTS frame at the same time, and after sending a CTS frame, it waits for the same preset time before sending a beacon frame.

[0173] In this application, parameters such as TBTT, XIFS, beacon frame length, CTS frame transmission time, CTS frame length, and preset duration of the interval between the CTS frame transmission time and the beacon frame transmission time can be referred to as relevant transmission parameters of the beacon frame.

[0174] The relevant transmission parameters of the beacon frame can be negotiated and determined by multiple access points in the same AP group, or they can be determined and configured by the management node that manages multiple access points and assigned to each access point, without any restrictions.

[0175] Optionally, in Method 1, after at least two access points out of multiple access points have simultaneously sent beacon frames, the channel used for transmitting beacon frames is idle. If one of the access points has a data frame to transmit, that access point can refer to the data frame transmission mechanism described above to check if the channel is idle and send the data frame after waiting for XIFS duration. Since the air interface overhead for sending a data frame is at least the duration for all access points to send beacon frames, in Method 1, when at least two access points in the same frequency group send beacon frames at the same time, and the beacon frames of at least two access points have the same frame length, the end time for sending the beacon frames of at least two access points is also the same. This makes the air interface overhead at least the sum of the frame length of one beacon frame and one XIFS, which is less than the air interface overhead for sending data frames as shown in Figure 3 (at least the sum of multiple beacon frames and multiple XIFS), thus reducing the air interface overhead for sending data frames.

[0176] For example, taking the WLAN co-frequency network shown in Figure 2 as an example, access points 1 to 4 in Figure 2 send beacon frames according to the timing sequence shown in Figure 9. As shown in Figure 9, all access points in Figure 9 are configured through negotiation to send beacon frames at a transmission rate of 6 Mbps at time t1 after the TBTT delay τ0. The frame length T of the beacon frames sent by each access point in Figure 9 is... frame Equal, for example, the frame length T of each beacon frame. frame All are 536µs. In this example, as shown in Figure 9, one of the access points 1-4 can send a data frame at time t2, after sending the beacon frame and then waiting for XIFS. In this example, the air interface overhead for this access point to send the data frame is at least T. frame The XIFS value is used in conjunction with the data frame transmission overhead. Assuming XIFS is 25µs, the air interface overhead is at least 536µs + 25µs = 561µs. This means that the access point must wait at least 561µs after sending the beacon frame at time t1 before sending the data frame at time t2. For example, the air interface overhead can be set to 600µs, with t2 being the time corresponding to t1 + 600µs. The access point then sends the data frame at time t2. Comparing Figures 9 and 3, it is found that the air interface overhead is significantly reduced compared to the 2400µs required to send the beacon frame using the method shown in Figure 3.

[0177] Method 2: Multiple access points are located in multiple AP groups, and no two APs in any AP group are adjacent.

[0178] In this application, two APs not being adjacent means that the distance between the two APs is greater than a preset location threshold, and / or that the path loss between the two APs is greater than a path loss threshold. Two APs being adjacent means that the distance between the two APs is less than a distance threshold, and / or that the path loss between the two APs is less than a path loss threshold, etc.

[0179] In this application, the location distance between APs can refer to the Euclidean distance between APs, etc. The specific calculation of the location distance between APs can refer to existing technologies and will not be elaborated here. The distance threshold can be set as needed and is not limited. When the location distance between APs is greater than the distance threshold, it means that the APs are far apart; when the location distance between APs is less than the distance threshold, it means that the APs are close together.

[0180] In this application, path loss can be alternatively described as path distance loss. The formula for calculating path loss is: Path loss (dB) = 32.44 + 20log10(f) + 20log10(d), where f represents the signal frequency (in MHz) and d represents the propagation distance (in km). As can be seen from the formula, the higher the signal frequency of the signal transmitted between APs, the greater the path loss; the greater the propagation distance of the signal transmitted between APs, i.e., the greater the distance between the APs, the greater the path loss. The calculation of path loss between APs can refer to existing technologies and will not be elaborated further. The path loss threshold can be set as needed and is not limited. When the path loss between APs is greater than the path loss threshold, it means that the distance between APs is relatively far; when the path loss between APs is less than the path loss threshold, it means that the distance between APs is relatively short.

[0181] Optionally, when two access points (APs) are adjacent, meaning they are close to each other, their wireless signal coverage areas (or simply coverage areas) will overlap significantly. This means the two adjacent APs correspond to a large overlapping area (or shared coverage area). Generally, the shared coverage area of ​​two adjacent APs can be located in the "middle" of their physical locations. It should be understood that the "middle" of the two APs' physical locations is a relative concept, describing their relatively central position in the physical layout. When a station moves towards one of the two adjacent APs, it is likely to move into this shared coverage area and receive signals (such as beacon frames) from both APs within this shared coverage area. When a station moves within this "middle" area, the distance between the station and the two APs is not significantly different, and the signal strength of the beacon frames received simultaneously from both APs (or adjacent APs) is relatively similar, or even the same. If two adjacent APs simultaneously transmit beacon frames, the signal-to-noise ratio (SNR) of the simultaneously transmitted beacon frames detected by the station will be low, below the demodulation threshold, and therefore cannot be demodulated by the station, resulting in beacon frame loss.

[0182] Conversely, when two access points (APs) are not adjacent, meaning they are far apart, their wireless signal coverage areas are unlikely to overlap, i.e., they do not share a common coverage area. When a station moves towards one of these two non-adjacent APs, it may move away from the other. In other words, as the station moves towards one of the two non-adjacent APs, it will move to the edge of the other AP's coverage area, or even outside the coverage area. In this case, the signal strength of the beacon frames received by the station from these two non-adjacent APs will differ significantly. If the two non-adjacent APs send beacon frames simultaneously, the signal-to-noise ratio (SNR) of the simultaneously transmitted beacon frames detected by the station will be different, with one having a higher SNR than the other. The higher SNR is above the demodulation threshold and is successfully demodulated by the station, while the lower SNR is below the demodulation threshold and cannot be successfully demodulated, achieving the effect of simultaneous beacon frame collision between two non-adjacent APs.

[0183] It should be understood that the common coverage area of ​​two adjacent access points (APs) located in the "middle" region of their physical locations is affected by various factors, such as the AP's transmit power and antenna type, environmental factors, frequency and channel selection, and the AP's installation location and layout. Under ideal conditions (e.g., open space, no obstructions, identical transmit power and antenna type, appropriate channel selection), the common coverage area of ​​two APs may be closer to the "middle" region of their physical locations. In most cases, due to environmental complexity and the presence of various interference factors, the common coverage area may deviate from the "middle" region, and even signal dead zones or weak coverage areas may appear in some areas. The term "middle" in this application can also be used interchangeably to describe a middle location, a middle region, a relatively middle location, etc., without limitation. For example, suppose AP1-AP4 all transmit beacon frames with the same power, AP1-AP4 are located at the same level, AP2 is located 30m to the right of AP1, AP3 is located 30m to the right of AP2, AP4 is located 30m to the right of AP3, and the distance threshold is 35m. AP1-AP4 are divided into two AP groups.

[0184] One possible grouping is AP1 and AP4 in AP group 1, and AP2 and AP3 in AP group 2. When the STA is located between AP1 and AP2, or between AP3 and AP4, the STA receives beacon frames simultaneously transmitted by AP2 and AP3 in AP group 2. The signal strength of the beacon frames received from AP2 and AP3 will not be close. For example, when the STA is located between AP1 and AP2, the distance between the STA and AP2 is less than the distance between the STA and AP3, and the signal strength of the beacon frames received from AP2 is greater than the signal strength of the beacon frames received from AP3. Similarly, when the STA is located between AP3 and AP4, the distance between the STA and AP3 is less than the distance between the STA and AP2, and the signal strength of the beacon frames received from AP3 is greater than the signal strength of the beacon frames received from AP2. However, when the STA is located between AP2 and AP3, the distance between the STA and AP3 is similar to the distance between the STA and AP2. The signal strength of the beacon frames received by the STA from AP2 is similar to the signal strength of the beacon frames received from AP3, resulting in beacon frame loss. The STA, located between AP2 and AP3, cannot detect the existence of the 802.11 network, triggering roaming.

[0185] Another possible grouping is where no two APs in any of the two AP groups are adjacent. For example, AP1 and AP3 are in AP group 1, and AP2 and AP4 are in AP group 2. The STA is located in the middle of any two adjacent APs from AP1 to AP4. Since the signal strengths of the beacon frames received by the STA from the two APs in the same AP group are not close, beacon frame loss will not occur, and roaming will not be triggered. For example, when the STA is located between AP2 and AP3, for AP1 and AP3 in AP group 1, the distance between the STA and AP3 is less than the distance between the STA and AP1. When the AP in AP group 1 sends a beacon frame, the signal strength of the beacon frame received by the STA from AP3 is greater than the signal strength of the beacon frame received from AP1. For AP2 and AP4 in AP group 2, the distance between the STA and AP2 is less than the distance between the STA and AP4. When the AP in AP group 2 sends a beacon frame, the signal strength of the beacon frame received by the STA from AP2 is greater than the signal strength of the beacon frame received from AP4.

[0186] Based on method two, the AP and its neighboring APs are located in different AP groups. This ensures that the AP and its neighboring APs will not send beacon frames at the same time, avoiding beacon frame loss caused by similar signal strength when a site receives multiple beacon frames from at least two access points simultaneously. For a detailed description of beacon frame loss, please refer to the above text; it will not be repeated here.

[0187] In Method 2, adjacent APs can be considered as APs that interfere with or conflict with each other, and are not allowed to be assigned to the same AP group. Optionally, multiple access points can be divided into multiple AP groups based on a graph coloring strategy. The graph coloring strategy can be applied to areas considering resource allocation and conflict avoidance, such as solving the problem in this application where adjacent APs are assigned to the same AP group and simultaneously send beacon frames. The principle of the graph coloring strategy is to assign different colors (different colors represent different delay times or resources) to adjacent access points (or adjacent APs) among multiple access points, so that adjacent access points have different colors, thereby assigning APs of different colors to different AP groups and APs of the same color to the same AP group, avoiding APs of different colors from sending beacon frames simultaneously, and ensuring that APs of the same color send beacon frames simultaneously.

[0188] The following describes the process of grouping multiple access points based on the graph coloring strategy, using AC as the execution entity, through steps 1-6:

[0189] Step 1: The AC determines that multiple access points will be divided into K groups, that is, the access points will be divided into K AP groups. The AC is configured with K delay times.

[0190] Where K is an integer greater than 1.

[0191] Here, the K delay times can correspond to the K AP groups obtained from the final grouping, and one AP group corresponds to / is associated with one delay time. Optionally, the delay time can also be replaced with a color, that is, the AP group is marked / corresponded to / associated with a color.

[0192] Step 2: The AC obtains the location information and / or path loss information of each of the multiple access points, and determines the set of adjacent access points for each of the multiple access points based on the location information and / or path loss information.

[0193] The set of adjacent access points includes the access point itself and all access points adjacent to it from among multiple access points. An access point may have one or more adjacent access points; for example, in this application, the number of adjacent access points may be less than or equal to K, without limitation. Access points included in different sets of adjacent access points may partially overlap.

[0194] Optionally, for any one of multiple access points, the location distance and / or path loss between it and other access points (excluding the access point itself) can be calculated based on the location information and / or path loss information of each access point. Access points whose location distance is less than a distance threshold and / or whose path loss is less than a path loss threshold are designated as adjacent access points. Specifically, the calculation methods for location distance and path loss can refer to existing technologies and will not be elaborated upon here.

[0195] Furthermore, the AC iterates through each of the multiple access points, and for each access point it encounters, performs the following steps 3-4 to allocate a delay time to each of the adjacent access points in the set of adjacent access points for that access point:

[0196] Step 3: The AC determines whether the access point has already been assigned a delay time. If no delay time has been assigned, a delay time is selected from K delay times, such as the first delay time, and assigned to the access point. If a delay time has already been assigned, proceed to Step 4.

[0197] It should be understood that when an access point is the first access point visited, it has not been allocated a delay time, and this first access point can be any one of multiple access points. For example, this access point can be access point 1 in Figure 10. When an access point is not the first access point visited, it may have been allocated a delay time.

[0198] Step 4: The AC iterates through each of the access point's neighboring access points. For each neighboring access point encountered, the following process is performed: Determine if a delay time has already been assigned to the neighboring access point. If no delay time has been assigned, select the second delay time from the K delay times and assign it to the neighboring access point. If a delay time has already been assigned, do not assign one, and continue iterating through the next neighboring access point until all neighboring access points of the access point have been visited, i.e., until every access point in the neighboring access set of the access point has been assigned a delay time.

[0199] The second delay time differs from the first delay time. Different access points within the adjacent access point set are assigned different delay times.

[0200] Step 5: The AC continues to traverse the next access point, performing the delay time allocation process as described in Steps 3 and 4 above, until the next access point and every access point in the adjacent access set of the next access point are allocated a delay time.

[0201] In this application, the AC repeatedly executes step 5 above until each of the multiple access points has been traversed, and each of the multiple access points is assigned a delay time. Different access points in the same set of adjacent access points are assigned different delay times. Access points in different sets of adjacent access points can be assigned the same delay time, that is, access points in different sets of adjacent access points may reuse the same delay time.

[0202] Step 6: The AC will group access points with the same delay time into one AP group.

[0203] Each AP group corresponds to / is associated with a delay time allocated to the access points included in that AP.

[0204] For example, with 3 preset delay times and 4 access points (APs), each access point's neighboring access point set is as follows: AP1 - neighboring access point set 1 (AP1, AP3), AP2 - neighboring access point set 2 (AP2, AP4), AP3 - neighboring access point set 3 (AP3, AP1, AP4), and AP4 - neighboring access point set 4 (AP4, AP2, AP3). One possible design allocates the following delay times to each access point: AP1's delay time is delay time 1, AP2's delay time is delay time 1, AP3's delay time is delay time 2, and AP4's delay time is delay time 3. Another possible design allocates the following delay times to each access point: AP1's delay time is delay time 1, AP2's delay time is delay time 2, AP3's delay time is delay time 2, and AP4's delay time is delay time 3. The principle behind this design is as follows: Based on the adjacent access point set 1, AP1 and AP3 are assigned different delay times, assuming AP1 is assigned delay time 1 and AP3 is assigned delay time 2. Further based on the adjacent access point set 3, AP4 is an adjacent access point of both AP1 and AP3, and AP4 needs to be assigned a delay time different from both AP1 and AP2, so delay time 3 is assigned to AP4. Further based on the adjacent access point set 2, AP2 is an adjacent access point of AP4, and AP2 needs to be assigned one of the other times besides delay time 3, such as delay time 1 or delay time 2. Since AP2 is neither an adjacent access point of AP1 (corresponding to delay time 1) nor an adjacent access point of AP3 (corresponding to delay time 2), any delay time of either delay time 1 or delay time 2 can be assigned to AP2, thus ensuring that the delay time assigned to each of the four APs is different.

[0205] Furthermore, the AC sends the first information to each access point in each AP group, and each access point in the AP group receives the first information. The first information may carry or be used to indicate the delay time corresponding to the AP group. Any one of the multiple access points performs the preparation operation for sending the beacon frame and sends the beacon frame after the delay time following the TBTT, based on the delay time carried in the first information.

[0206] The core design of Method 2 is to ensure that any two APs in any AP group are not adjacent in the multiple AP groups in the communication network. Thus, any two access points that send beacon frames at the same time are not adjacent. No restrictions are placed on the algorithm or design for how to achieve the non-adjacent nature of any two APs in any AP group in the multiple AP groups of the communication network.

[0207] For example, the communication network includes 16 access points located in 7 AP groups. Access points in different AP groups send beacon frames at different times; for instance, the access point in the first AP group sends the beacon frame at time t1, the access point in the second AP group at time t2, ..., and the access point in the seventh AP group at time t7. The location distribution of the 16 access points is shown in Figure 10.

[0208] Taking access point 6 in Figure 10 as an example, the location of access point 6 in Figure 10 is adjacent to the locations of access points 1, 7, and 12 in Figure 10. Therefore, access point 6 in Figure 10 will not be located in the same AP group as access points 1, 7, and 12 in Figure 10.

[0209] Taking access point 7 in Figure 10 as an example, access point 7 in Figure 10 is adjacent to access points 1, 2, 8, 13, 12 and 6 in Figure 10. Therefore, access point 7 in Figure 10 will not be in the same AP group as access points 1, 2, 8, 13, 12 and 6 in Figure 10.

[0210] Taking access point 8 in Figure 10 as an example, access point 8 in Figure 10 is adjacent to access points 2, 3, 9, 14, 13 and 7 in Figure 10. Therefore, access point 7 in Figure 10 will not be in the same AP group as access points 2, 3, 9, 14, 13 and 7 in Figure 10.

[0211] Based on the design that no two APs in any AP group are adjacent, one possible grouping is as follows: the access points in the first AP group are access point 1, access point 14, and access point 5; the access points in the second AP group are access point 2 and access point 15; the access points in the third AP group are access point 3, access point 12, and access point 16; the access points in the fourth AP group are access point 4 and access point 13; the access points in the fifth AP group are access point 6 and access point 9; the access points in the sixth AP group are access point 8 and access point 11; and the access points in the seventh AP group are access point 7 and access point 10.

[0212] Method 3: Determine multiple candidate packet methods corresponding to multiple access points, select the first candidate packet method from the multiple candidate packet methods, and determine the AP group corresponding to the first candidate packet method as the AP group corresponding to the multiple access points.

[0213] The candidate grouping method can be replaced by a candidate beacon frame collision strategy or a candidate grouping strategy. Multiple candidate grouping methods are determined based on the number of access points and / or the candidate status of each access point. Specifically, the process for determining the candidate grouping method can be referred to step 2 below, and will not be repeated here.

[0214] The first candidate packet method can be the candidate packet method with the largest gain among multiple candidate packet methods. In this application, the gain of the candidate packet method can be replaced by the value function value described by the candidate packet method. The gain of the candidate packet method can be used to characterize the beacon frame loss and weak beacon frame occurrence when transmitting beacon frames using that candidate packet method.

[0215] The following describes the specific execution process of Method 3, using AC as the execution entity, through steps 1-3 (see Figure 11):

[0216] 1. The AC determines that multiple access points are divided into K groups, that is, the access points are divided into K AP groups. The AC determines the candidate state of each access point among the multiple access points based on the value of K.

[0217] Where K is an integer greater than 1.

[0218] In this application, the candidate state of an access point can be replaced by a candidate time state for the access point to send beacon frames. Optionally, the candidate state of the access point may include: not sending beacon frames, or sending beacon frames after a delay time. Sending beacon frames after a delay time means sending the beacon frame at a time after the delay time, starting from a reference time. The reference time can be an integer multiple of TBTT.

[0219] In this application, the candidate / selectable values ​​for the delay time can be one or more. For example, there can be K delay times, which can correspond to the K AP groups obtained from the final grouping. One AP group corresponds to / is associated with one delay time. One delay time corresponds to one candidate state, and multiple delay times correspond to multiple candidate states. For example, the delay time can include a first time and a second time. Delaying the beacon frame transmission at the first time is one candidate state for the access point, and delaying the beacon frame transmission at the second time is another candidate state for the access point. Alternatively, K delay times can correspond to K different candidate states.

[0220] Optionally, the number M of candidate states for an access point can be determined based on the number K of AP groups. For example, the number of candidate states for an access point is the number of AP groups plus 1, i.e., M = N + 1. Taking multiple access points divided into 2 AP groups as an example, the candidate states for each access point can include not sending a beacon frame, sending a beacon frame after a delay of 1, and sending a beacon frame after a delay of 2.

[0221] In this application, sending a beacon frame after a delay time can be understood as performing preparation operations for sending the beacon frame and sending the beacon frame after the delay time.

[0222] 2. The AC determines all candidate grouping methods corresponding to multiple access points based on the candidate status of each access point among multiple access points.

[0223] One method for determining all candidate groupings for multiple access points can be: Based on the candidate state of each access point, obtain all permutations and combinations of the candidate states of all K access points. Each access point has M possible candidate states. With the number of access points being q, the total number of permutations / combinations of the candidate states of all access points is M. q One, M q One combination method corresponds to one candidate grouping method. Access points with the same candidate state in each candidate combination method / result are located in the same AP group, so that access points in the same AP group can send beacon frames simultaneously when the candidate state time arrives, thus causing the beacon frames sent by access points in the same AP group to collide.

[0224] 3. AC determines the gain of each candidate grouping method and selects the first candidate grouping method with the largest gain among all candidate grouping methods.

[0225] Here, gain can be replaced by a value function value or a beacon frame collision gain.

[0226] In one example, for each candidate packet mode, the AC can test at each sampling point the number of times beacon frame loss occurs and the number of times weak beacon frames occur when beacon frames are sent using the packet mode in that candidate packet mode. The value function value corresponding to that sampling point is determined based on the number of times beacon frame loss occurs and the number of times weak beacon frames occur. The sum of the value function values ​​corresponding to all sampling points is taken as the value function value corresponding to that candidate packet mode.

[0227] The location and / or number of sampling points can be preset, and the sampling points can be included in the coverage area of ​​multiple access points.

[0228] Optionally, for any given sampling point, the fewer the number of beacon frame loss occurrences and weak beacon frame occurrences at that sampling point, the greater the beacon frame collision gain that can be obtained using the candidate grouping method at that sampling point, and the larger the gain / value function value. Conversely, the more the number of beacon frame loss occurrences and weak beacon frame occurrences at that sampling point, the smaller the corresponding beacon frame collision gain and the smaller the gain / value function value. Beacon frame loss can include beacon frames that cannot be received by the station, or beacon frames that are received by the station but cannot be successfully demodulated / parsed by the station. Weak beacon frames can refer to beacon frames with signal strength less than a preset strength threshold. Optionally, the preset strength threshold can be -70dBm. As mentioned above, if the signal-to-noise ratio of a beacon frame is less than the demodulation threshold, the beacon frame cannot be successfully demodulated by the station. Specific details are as described above and will not be repeated here.

[0229] Optionally, for any sampling point, the AC can obtain a value function and determine the gain of the candidate grouping method at that sampling point based on the number of times beacon frame loss occurs, the number of times weak beacon frames occur, and the value function.

[0230] The value function is used to measure the beacon frame collision gain corresponding to the candidate grouping method. The value function can be preset or pre-configured, or it can be obtained by the AC from other devices; there are no restrictions.

[0231] For example, the value function is the following formula (1), which characterizes the correlation between the value function value Q and the number of times beacon frame loss occurs and the number of times weak beacon frames occur:

[0232] Q = N miss *f1+N weak *f2 formula (1)

[0233] In formula (1), N missN represents the number of times a beacon frame is lost. weak f1 represents the number of times weak beacon frames occur; f2 and f1 are values ​​between 0 and 1. Optionally, f1 and f2 can be the same or different. Substituting the number of times beacon frame loss occurs and the number of times weak beacon frames occur into formula (1) yields the beacon frame collision gain for the candidate grouping method.

[0234] Optionally, the signal strength and signal-to-noise ratio (SNR) of each beacon frame can be obtained from a link budget simulation model. This model calculates the received signal power based on the transmitted power and path loss. The received signal power indicates the signal strength. For example, given the transmitted power P0 and path loss P of the beacon frame... L In this case, the received power P1 of the beacon frame is the difference between the transmitted power of the beacon frame and the path loss of the beacon frame, i.e., P1 = P0 - P L Furthermore, after calculating the signal strength of each beacon frame, the signal-to-noise ratio (SNR) of the beacon frame can be calculated based on the definition of SNR mentioned above.

[0235] For example, suppose there are 5 access points (APs) in a co-frequency network with the same BSSID, and the signal coverage area of ​​the 5 APs is 100 square meters (10 meters long and 10 meters wide). Each AP has 3 candidate states: {do not send beacon frames, send beacon frames after delay t1, and send beacon frames after delay t2}. Then there are 5^3 possible grouping methods for the 5 APs. Each candidate beacon strategy requires evaluating the sum of the value function values ​​Q of all sampling points within the 100 square meters. Assuming one sampling point is obtained per square meter, there are 100 sampling points within the signal coverage area of ​​the 5 APs. For each of the 5^3 candidate grouping methods, the sum of the value function values ​​Q of these 100 sampling points must be calculated. Then, the candidate grouping method with the largest sum of value function values ​​Q is selected as the first candidate grouping method from the 5^3 candidate grouping methods.

[0236] In another example, a reinforcement learning strategy can be used to determine the gain of all candidate groupings and select the first candidate grouping.

[0237] Specifically, the reinforcement learning strategy can be understood as determining the gain of all candidate grouping methods through multiple iterations. Determining all candidate grouping methods using a reinforcement learning strategy may include: setting up multiple iterations; for the i-th iteration, determining the gain of M candidate analysis methods, where the M are the top M candidate grouping methods with the largest gain from the (i-1)-th iteration. The process of determining the gain of each of the M candidate grouping methods can be referred to the example above and will not be repeated here.

[0238] Where i can be set as needed, and i is an integer greater than 1. M is an integer greater than 1, and the value of M can be set as needed. The number of sampling points in each iteration is different. Optionally, the number of sampling points can be proportional to the number of iterations.

[0239] For example, consider a network with 5 APs in the same frequency and BSSID, with a signal coverage area of ​​100 square meters (10 meters long and 10 meters wide). Each AP has 3 candidate states: {do not send beacon frames, send beacon frames after delay time t1, and send beacon frames after delay time t2}. Then, there are 5^3 possible grouping methods for the 5 APs. Assume that the reinforcement learning iterations are 3 and there are 100 sampling points within the signal coverage area of ​​the 5 APs.

[0240] For the first iteration, five sampling points are selected within a 100-square-meter area. For each of the candidate grouping methods, the sum of the value function values ​​Q of these five sampling points is calculated. Then, all candidate grouping methods are arranged from high to low according to the sum of the value function values ​​Q of each candidate grouping method, and the first half of the candidate grouping methods are retained.

[0241] For the second iteration, 50 sampling points are selected within a 100-square-meter area. For each of the 1 / 2 candidate grouping methods retained in the first iteration, the sum of the value function values ​​Q of these 50 sampling points is calculated. The 1 / 2 candidate grouping methods are further arranged from high to low according to the sum of the value function values ​​Q of each candidate grouping method. The first 1 / 2 of the 1 / 2 candidate grouping methods are retained. That is, the candidate grouping methods retained after the second iteration are 1 / 4 of all candidate grouping methods.

[0242] For the third iteration, 100 sampling points are selected from 100 square meters. For each of the 1 / 4 candidate grouping methods retained from the second iteration, the sum of the value function values ​​Q of these 100 sampling points is calculated. The 1 / 4 candidate grouping methods are further arranged from high to low according to the sum of the value function values ​​Q of each candidate grouping method. The candidate grouping method with the largest sum of value function values ​​Q among the 1 / 4 candidate grouping methods is taken as the first candidate grouping method.

[0243] Thus, by using reinforcement learning to determine the first candidate grouping method, the number of candidate grouping methods calculated in each iteration can be reduced, which can significantly reduce the amount of computation and improve computational efficiency.

[0244] Furthermore, the AC sends the first information to each of the multiple access points, and each access point receives the first information accordingly. Each access point sends a beacon frame based on its own candidate state.

[0245] The first information received by the access point carries the candidate status of the access point, and the candidate status of the access point corresponds to the first candidate grouping method.

[0246] Besides dividing multiple access points into multiple groups so that access points in the same group can simultaneously transmit beacon frames, thus achieving simultaneous transmission of beacon frames by at least two access points, this method can also achieve simultaneous transmission of beacon frames by adjusting the timing of the preparation operations performed by at least two access points. Specifically, this method may include:

[0247] At least two access points among multiple access points negotiate a delay time. After the negotiation, for each of the at least two access points, upon arrival of the TBTT (Total Time To Be Received), the access point performs a preparation operation to send a beacon frame after the delay time. After this preparation operation, the beacon frame is sent. The preparation operation for sending the beacon frame includes: the access point checks if the channel is busy or idle. If the channel is idle, it waits for the XIFS (One-Hourly Rate) duration and then checks if the channel is busy or idle again. If the channel is still idle, the preparation operation ends, and the beacon frame is sent. If the channel is detected as busy, the access point must wait for the channel to become idle before performing the above process.

[0248] In this application, the TBTT and XIFS of each of at least two access points are identical, and the frame length of the beacon frames sent by each access point is the same. The delay time is the duration from the moment corresponding to the TBTT to the moment when the access point begins to perform the exact operation of sending the beacon frame. If the moment after the TBTT (or the moment when the access point prepares to send the beacon frame) is considered as the preparation moment or the adjusted TBTT, the mutual negotiation of the delay time among at least two access points can be replaced by the description that at least two access points negotiate the preparation moment or the adjusted TBTT. The aforementioned preparation operation for sending the beacon frame after the delay time when the TBTT arrives can be replaced by the access point preparing to send the beacon frame when the preparation moment or the adjusted TBTT arrives. In this application, for ease of description, the moment after the delay time after the TBTT is named the preparation moment.

[0249] In one example, at least two of the multiple access points have the same delay time. That is, each of the at least two access points can perform preparation operations to send a beacon frame and detect channel busy / idle status in response to the simultaneous arrival of the preparation time. Since at least two access points operate on the same channel, the busy / idle status of the channel detected by different access points is the same. Ignoring the detection capability / detection time of the at least two access points, these at least two access points can simultaneously detect that the channel is idle and, if the channel is idle, simultaneously send a beacon frame after at least the same XIFS.

[0250] In another example, at least two of the multiple access points have a delay time greater than the delay time of the first access point but less than a first duration. The first duration is the sum of the delay time of the first access point, XIFS, and the frame length of a beacon frame. The delay time of the first access point is the shortest / smallest delay time among the multiple access points. In other words, a delay time can be allocated to the first access point first, and then the delay time of the at least two access points can be allocated to these access points using the delay time of the first access point as a reference time. For example, if the at least two access points include access point 1 and access point 2, and the delay time allocated to the first access point is 10µs, assuming the frame length of the beacon frame is 536µs and XIFS is 25µs, then two time values ​​can be selected from the time range (10µs, 571µs) and allocated to access point 1 and access point 2 as delay times.

[0251] Thus, each of the at least two access points can perform a preparation operation to send a beacon frame in response to the arrival of the preparation time during the time period when the first access point sends a beacon frame, and detect the channel busy / idle status. Since the at least two access points operate on the same channel, the busy / idle status of the channel detected by different access points is the same for the same channel. Ignoring the detection capability / detection duration of the at least two access points, if the preparation time of the at least two access points falls within the time period when the first access point sends a beacon frame, then at the end time when the first access point sends a beacon frame, these at least two access points can simultaneously detect that the channel is idle, and in the case of an idle channel, simultaneously send a beacon frame after at least the same XIFS.

[0252] The two examples mentioned above can be combined without restriction.

[0253] In this implementation, at least two access points are non-adjacent. Specifically, the method for determining whether at least two access points are adjacent can be referred to in Method Two above, and will not be repeated here.

[0254] For example, a communication network includes 16 access points and 1 station. The beacon frames sent by the 16 access points have the same BSSID. The locations of the 16 access points are shown in Figure 12. The station is either station 1 at location 1 or station 2 at location 2 in Figure 12. The delay time of each access point sending its beacon frame relative to the TBTT, determined through negotiation among the 16 access points, is shown in Figure 12. (Figure 12 shows the delay time of each access point sending its beacon frame relative to the TBTT.)

[0255] Specifically, the timing sequence of the preparation times for each access point in Figure 12 is shown in Figure 13. Access points 7 and 10 perform preparation operations for sending beacon frames at a time 0µs after a TBTT delay. Assuming TBTT is time t0, both access points 7 and 10 perform preparation operations for sending beacon frames at time t0. Access points 6 and 9 perform preparation operations for sending beacon frames at time t1, 20µs after a TBTT delay. Time t1 is 20µs after time t0. Access points 1, 5, 11, and 14 perform preparation operations for sending beacon frames at time t2, 40µs after a TBTT delay. Time t2 is 40µs after time t0 and 20µs after time t1. Access point 8 performs preparation operations for sending beacon frames at time t3, 80µs after a TBTT delay. Time t3 is 80µs after time t0 and 20µs after time t2. Access points 4 and 13 perform preparation operations to send beacon frames at time t4, after a TBTT delay of 100µs. Time t3 is a delay of 100µs from time t0, and also a delay of 20µs from time t4. Access points 3, 12, and 16 perform preparation operations to send beacon frames at time t5, after a TBTT delay of 120µs. Time t5 is a delay of 120µs from time t0, and also a delay of 20µs from time t4.

[0256] Next, as shown in Figure 13, after access points 7 and 10 perform preparation operations for sending beacon frames at time t0, they send beacon frames at time t0' after undergoing XIFS. At this time, the channel is occupied by beacon frames sent by access points 7 and 10 from time t0' to time t6, with time t6 being the end time of beacon frames sent by access points 7 and 10. During the period from time t0' to time t6, the preparation time (i.e., the time when preparation operations for sending beacon frames are performed) of all access points other than access points 7 and 10 arrives. Each access point other than access points 7 and 10 performs channel busy / idle detection. During the period from time t0' to time t6, it is detected that the channel is occupied and busy, until the end of time t6 when it is detected that the channel is idle. Thus, all access points other than access points 7 and 10 simultaneously send beacon frames after undergoing XIFS, as shown in Figure 14, simultaneously sending beacon frames at time t7.

[0257] This implementation method enables at least two access points to simultaneously transmit beacon frames. As mentioned above, weak beacon frames among the simultaneously transmitted beacon frames cannot be demodulated by the station. For example, still taking Figure 12 as an example, for station 1, station 1 receives beacon frames transmitted by access points 7 and 10 at time t0'. Since the distance between station 1 and access point 7 is less than the distance between station 1 and access point 10, the signal strength of the beacon frame transmitted by access point 7 at time t0' received by station 1 will be greater than the signal strength of the beacon frame transmitted by access point 10 at time t0' received by station 1. The beacon frame transmitted by access point 10 is a weak beacon frame. The signal-to-noise ratio (SNR) of the beacon frame transmitted by access point 7 received by station 1 at time t0 is likely to be higher than the demodulation threshold of station 1, and the SNR of the beacon frame transmitted by access point 10 received by station 1 at time t0' is likely to be lower than the demodulation threshold of station 1. Therefore, station 1 will only successfully parse the information carried in the beacon frame transmitted by access point 7 at time t0.

[0258] Taking Figure 12 as an example, for station 2, station 2 receives beacon frames sent by access point 7 and access point 10 at time t0'. Since the distance between station 2 and access point 7 and the distance between station 2 and access point 10 are close, the signal strength of the beacon frame sent by access point 7 at time t0 may be equal to (or close to) the signal strength of the beacon frame sent by access point 10 at time t0'. Moreover, the signal-to-noise ratio of the two beacon frames is less than the demodulation threshold of station 2, causing the beacon frame loss phenomenon, resulting in station 2 not parsing any beacon frame sent at time t0'. Since the distance between station 2 and access point 9 is less than the distance between station 2 and access point 6, the signal strength of the beacon frame sent by access point 9 at time t7 received by station 2 will be greater than the signal strength of the beacon frame sent by access point 6 at time t7 received by station 2. The signal-to-noise ratio of the beacon frame sent by access point 9 received by station 2 at time t7 is likely to be higher than the demodulation threshold of station 2, and the signal-to-noise ratio of the beacon frame sent by access point 6 received by station 2 at time t7 is likely to be lower than the demodulation threshold of station 2. Therefore, station 2 will only successfully parse the information carried in the beacon frame sent by access point 7 at time t0.

[0259] The various embodiments of this application can be implemented independently or in combination, without limitation. Unless otherwise specified or in conflict of logic, the terminology and / or descriptions between the different embodiments provided in this application are consistent and can be referenced mutually. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0260] It is understood that in the embodiments of this application, the executing entity may perform some or all of the steps in the embodiments of this application. These steps or operations are merely examples, and the embodiments of this application may also perform other operations or variations thereof. Furthermore, the various steps may be executed in different orders as presented in the embodiments of this application, and it is not necessarily necessary to execute all the operations in the embodiments of this application.

[0261] The foregoing primarily describes the solutions provided in this application from the perspective of device-to-device interaction. It is understood that each device, in order to achieve the aforementioned functions, includes corresponding hardware structures and / or software modules for executing each function. Those skilled in the art will readily recognize that, in conjunction with the algorithm steps of the examples described in the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0262] This application embodiment can divide each device into functional modules according to the above method example. For example, each function can be divided into a separate functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. The module division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0263] With each function module divided according to its corresponding function, Figure 15 shows an access point 150 (AP 150). The AP 150 can perform the actions performed by the AP in the method shown in the above embodiment. All relevant content of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module. The technical effects that can be obtained can be referred to the above method embodiment, and will not be repeated here.

[0264] The AP 150 may include a processing module 1501 and a transceiver module 1502. Exemplarily, the AP 150 may be a communication device, or a chip or other combination device or component with the aforementioned AP functions applied in a communication device. When the AP 150 is a communication device, the transceiver module 1502 may be a transceiver, which may include an antenna and radio frequency circuitry; the processing module 1501 may be a processor (or processing circuitry), such as a baseband processor, which may include one or more CPUs. When the AP 150 is a component with the aforementioned AP functions, the transceiver module 1502 may be a radio frequency unit; the processing module 1501 may be a processor (or processing circuitry), such as a baseband processor. When the AP 150 is a chip system, the transceiver module 1502 may be an input / output interface of a chip (e.g., a baseband chip); the processing module 1501 may be a processor (or processing circuitry) of the chip system, and may include one or more central processing units. It should be understood that the transceiver module 1502 in the embodiments of this application can be implemented by a transceiver or transceiver-related circuit components; the processing module 1501 can be implemented by a processor or processor-related circuit components (or, referred to as processing circuit).

[0265] For example, the transceiver module 1502 can be used to perform all the transceiver operations performed by the AP in the embodiments shown in the examples, and / or to support other processes of the technology described herein; the processing module 1501 can be used to perform all the operations performed by the AP in the embodiments shown in the examples other than the transceiver operations, and / or to support other processes of the technology described herein.

[0266] As another possible implementation, the transceiver module 1502 in Figure 15 can be replaced by a transceiver that integrates the functions of the transceiver module 1502; the processing module 1501 can be replaced by a processor that integrates the functions of the processing module 1501. Furthermore, the AP 150 shown in Figure 15 may also include a memory.

[0267] Alternatively, when the processing module 1501 is replaced by a processor and the transceiver module 1502 is replaced by a transceiver, the AP 150 involved in the embodiments of this application can also be the communication device 160 shown in FIG16.

[0268] The processor can be logic circuit 1601, and the transceiver can be interface circuit 1602. Furthermore, the communication device 160 shown in FIG16 may also include a memory 1603.

[0269] This application also provides a computer program product that, when executed by a computer, can implement the functions of any of the above method embodiments.

[0270] This application also provides a computer program that, when executed by a computer, can implement the functions of any of the above method embodiments.

[0271] This application also provides a computer-readable storage medium. All or part of the processes in the above method embodiments can be implemented by a computer program instructing related hardware. This program can be stored in the computer-readable storage medium, and when executed, it can include the processes of the above method embodiments. The computer-readable storage medium can be an internal storage unit of the terminal (including a data sending end and / or a data receiving end) of any of the foregoing embodiments, such as the terminal's hard disk or memory. The computer-readable storage medium can also be an external storage device of the terminal, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the terminal. Further, the computer-readable storage medium can include both the terminal's internal storage unit and external storage devices. The computer-readable storage medium is used to store the computer program and other programs and data required by the terminal. The computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

[0272] The terms "first" and "second," etc., used in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. "First" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature. In the description of this embodiment, unless otherwise stated, "a plurality of" means two or more.

[0273] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0274] In this application, "at least one (item)" means one or more. "More than one" means two or more. "At least two (items)" means two or three or more. "And / or" is used to describe the relationship between related objects, indicating that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple. "...when" and "if" both mean that a corresponding action will be taken under certain objective circumstances, not a time limit, nor do they require a judgment action at the time of implementation, nor do they imply any other limitations.

[0275] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner to facilitate understanding.

[0276] In this application, "sending information to...(terminal device)" can be understood as the destination of the information being the terminal device. This can include sending information directly or indirectly to the terminal device. "Receiving information from...(terminal device)" can be understood as the source of the information being the terminal device, and can include receiving information directly or indirectly from the terminal device. Information may undergo necessary processing between the source and destination, such as format changes, but the destination can understand the valid information from the source.

[0277] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0278] In the several embodiments provided in this application, the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0279] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0280] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0281] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of this application embodiment, or all or part of the technical solution, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

Claims

1. A communication method, characterized in that, The method is applied to a communication network, the communication network including multiple access points (APs) associated with the same Basic Service Set Identifier (BSSID), the method comprising: At least two of the plurality of APs generate beacon frames; The at least two APs simultaneously transmit the beacon frame.

2. The method according to claim 1, characterized in that, The multiple APs are located in at least one AP group; The at least two APs are APs from any AP group in the at least one AP group.

3. The method according to claim 2, characterized in that, In the case of multiple AP groups, no two APs in any AP group are adjacent; Wherein, two APs are not adjacent means that the location distance between the two APs is greater than a distance threshold, and / or that the path loss between the two APs is greater than a path loss threshold.

4. The method according to claim 2, characterized in that, The at least one AP group corresponds to the first candidate grouping method; The first candidate grouping method is the candidate grouping method with the largest gain among multiple candidate grouping methods. The gain of a candidate grouping method is used to characterize the beacon frame loss and weak beacon frame occurrence when beacon frames are sent in the candidate grouping method.

5. The method according to claim 4, characterized in that, The gain of the candidate grouping method is determined based on the number of beacon frame losses and the number of weak beacon frames that occur when beacon frames are sent using the candidate grouping method.

6. The method according to claim 1, characterized in that, The simultaneous transmission of beacon frames by at least two APs includes: The at least two APs begin transmitting beacon frames after a delay following the arrival of the beacon scheduled transmission time TBTT; Wherein, the delay time of the at least two APs is greater than the delay time of the first AP but less than the first duration; The first duration is the sum of the delay time of the first AP, the extended inter-frame interval (XIFS), and the frame length of a beacon frame; the delay time of the first AP is the shortest delay time among the plurality of APs.

7. The method according to any one of claims 1-6, characterized in that, Before the at least two APs simultaneously send the beacon frame, the method further includes: each of the plurality of APs performing clock synchronization; Among them, the clock synchronization error after clock synchronization is less than the preset duration; The preset duration is determined based on the station's channel busy detection interval.

8. The method according to any one of claims 1-7, characterized in that, Before the at least two APs simultaneously send the beacon frame, the method further includes: at least two of the plurality of APs simultaneously sending a CTS-enabled frame; The simultaneous transmission of beacon frames by at least two APs among the plurality of APs includes: each of the at least two APs transmitting a beacon frame after a preset time elapsed after transmitting a CTS frame; wherein the preset time elapsed for the at least two APs is the same.

9. The method according to any one of claims 2-5, characterized in that, APs in the same AP group have the same beacon scheduled transmission time (TBTT) and extended interframe interval (XIFS).

10. A communication device, characterized in that, The communication device includes a processor for running a computer program or instructions that cause the method described in any one of claims 1-9 to be executed.

11. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed on a computer, cause the method described in any one of claims 1-9 to be performed.

12. A computer program product, characterized in that, The computer program product includes computer instructions that, when some or all of the computer instructions are run, cause the method as described in any one of claims 1-9 to be performed.

Images