Method for transmitting coordinated multipoint access point AP and related device

Abstract

To provide a method for transmitting a coordinated multipoint access point AP in order to solve the problem of a prior art for occupying comparatively many channel resources to acquire a CSI, and a related device.SOLUTION: An embodiment of the application discloses a method and a related device for multipoint access point AP coordination. A method in the embodiment of the application includes a step in which a first access point AP generates a first radio frame, the step in which the first radio frame includes instruction information to be used to instruct a transmission time of a second radio frame to be transmitted by a second access point AP, a step in which the first access point AP transmits the first radio frame to the second access point AP, and a step in which the first access point AP transmits a third radio frame to a first station STA associated with the first access point AP during a transmission period of the second radio frame.SELECTED DRAWING: Figure 2a

Description

[Technical Field]

[0001] This application claims priority to Chinese Patent Application No. 201810133190.2, entitled "METHOD FOR COORDINATED MULTI-ACCESS POINT AP TRANSMISSION AND RELATED APPARATUS," filed with the China Patent Office on February 8, 2018, which is incorporated herein by reference in its entirety.

[0002] The present application relates to the field of communications, and more particularly to a method and related apparatus for coordinated multi-access point (AP) transmission. [Background technology]

[0003] With the development of wireless networks and the gradual popularization of wireless local area network (WLAN) technology, the density of WLAN devices is becoming increasingly high. Because wireless access points (APs) are easy to deploy, the higher the AP density, the greater the inter-cell interference. How to reduce inter-cell interference through AP cooperation and improve user service quality is also an issue that needs to be considered in next-generation Wi-Fi technology.

[0004] In the prior art, inter-cell interference can be reduced by using coordinated beamforming (co-BF) technology. Based on the co-BF technology, a relatively low correlation between effective channels can be maintained. For example, FIG. 1a is a schematic diagram of a prior art co-BF technology. In this diagram, AP1 is associated with station (STA) 1, and AP2 is associated with STA2. Before AP1 transmits data with STA1 and AP2 transmits data with STA2, AP1 needs to obtain channel state information (CSI) of the downlink channel between AP1 and STA1 and perform joint beamforming based on the CSI so that when a beam is emitted to STA1, the direction of STA2 is diverted to avoid interference with STA2. In addition, the same applies to AP2. Therefore, in a scenario where co-BF is used, simultaneous transmissions of two APs can be implemented, interference between the transmissions of the two APs can be avoided, and overall throughput can be effectively increased.

[0005] However, the CSI acquisition process is relatively complex and occupies some channel resources. When there are a relatively large number of users and the channel variation is fast, the CSI feedback imposes a high overhead. Summary of the Invention

[0006] The embodiments of the present application provide a method and related apparatus for coordinated multi-access point AP transmission to solve the problem in the prior art that a relatively large number of channel resources are occupied to obtain CSI. [Means for solving the problem]

[0007] A first aspect of an embodiment of the present application provides a method for coordinated multi-access point AP transmission, the method including: a first access point AP generating a first radio frame, the first radio frame including indication information, the indication information being used by a second access point AP to indicate a transmission time of a second radio frame; the first access point AP transmitting the first radio frame to the second access point AP after generating the first radio frame; and the first access point AP transmitting a third radio frame to a first station STA associated with the first access point AP during the transmission period of the second radio frame. In this embodiment of the present application, since the first access point AP transmits the first radio frame to the second access point AP, at least one second access point AP can simultaneously transmit a second radio frame to the second station STA at the same transmission time based on the first radio frame. By transmitting control information, multiple access points APs are synchronized, thereby solving the problem of the prior art that a relatively large number of channel resources are occupied for acquiring CSI.

[0008] In one possible embodiment, the instruction information includes a transmission time and an end time of the second wireless frame, and the first access point AP instructs the second access point AP of the transmission time and the end time of the second wireless frame, so that the second access point AP can determine the transmission time of the second wireless frame according to the instruction.

[0009] In one possible embodiment, the transmission time of the third radio frame is the same as the transmission time of the second radio frame, and in this embodiment, the third radio frame and the second radio frame are transmitted at the same transmission time, thereby reducing interference between the first access point AP and the second access point AP.

[0010] In one possible embodiment, the transmission time of the third radio frame is before the transmission time of the second radio frame. In this embodiment, the transmission time of the third radio frame may be before the transmission time of the second radio frame, and for the first station STA and the second station STA, after the transmission of the radio frame with the later end time in the second radio frame and the third radio frame is completed, the first station STA may further transmit an acknowledgment frame in response to the third radio frame, and the second station STA may further transmit an acknowledgment frame in response to the second radio frame, thereby avoiding a case where one access point AP transmits while another access point AP receives, and reducing the value of interference between the first AP and the second AP.

[0011] In one possible implementation, the indication information includes identifier information of the second access point AP. In this implementation, the first radio frame may further include identifier information of the second access point AP to assist multiple second APs in determining whether to participate in cooperative transmission with the first access point AP based on the identifier information.

[0012] In one possible embodiment, the first radio frame further carries one or more of the following: transmission power information of the second access point AP, information on the maximum tolerable interference threshold of the first access point AP, identifier information of the first station STA, transmission power information of the first station STA, and transmission power information of the first access point AP. In this embodiment, the first radio frame may further carry multiple other types of instruction information to add a multi-AP joint resource management function. The transmission power of the second access point AP and the transmission power information of the first access point AP may be adjusted to effectively control the interference of the first access point AP with the second station STA and the interference of the second access point AP with the first station STA. Since the information on the maximum tolerable interference threshold of the first access point AP is indicated to the second access point AP, the second access point AP controls the transmission power of the second station STA to prevent the value of the second station STA's interference with the first access point AP from exceeding the information on the maximum tolerable interference threshold of the first access point AP. Since the identifier information of the first station STA and the transmission power information of the first station STA are instructed to the second access point AP, the second access point AP can predict the value of the interference of the first station STA with the second access point AP, and the interference of the first station STA with the second access point AP can be effectively controlled.

[0013] In one possible implementation, the transmission time of the third radio frame is the same as the transmission time of the second radio frame. In this implementation, the first access point AP configures the transmission time of the second radio frame to be the same as the transmission time of the third radio frame, so that the end time of the second radio frame can be aligned with the end time of the third radio frame, thereby reducing interference between the first access point AP and the second access point AP.

[0014] In one possible embodiment, before the step of the first access point AP transmitting the first wireless frame to the second access point AP, the method further includes the steps of the first access point AP determining the second access point AP and the first access point AP allocating resource scheduling information to the second access point AP, where the resource scheduling information is used to indicate channel resources to be used by the second access point AP to transmit the second wireless frame. In this embodiment, the first access point AP allocates, to the second access point AP, channel resources to be used by the second access point AP to transmit the second wireless frame, thereby improving the efficiency of the second access point AP transmitting the second wireless frame.

[0015] In one possible embodiment, before the step of the first access point AP transmitting the first wireless frame to the second access point AP, the method further includes a step of the first access point AP successfully acquiring a channel through contention to transmit the first wireless frame, or a step of the first access point AP receiving a request frame transmitted by the access point AP that successfully acquired a channel through contention, the request frame being used to request the first access point AP to transmit the first wireless frame using the channel. In this embodiment, the first access point AP may contend for a channel to transmit the first wireless frame or may transmit the first wireless frame using a channel acquired through contention by another AP, thereby improving the flexibility of the first access point AP to transmit the first wireless frame.

[0016] A second aspect of the present application provides a method for coordinated multi-access point AP transmission, the method including: a step of receiving, by a second access point AP, a first radio frame transmitted by a first access point AP, the first radio frame including indication information used to indicate a transmission time of the second radio frame; and a step of transmitting, by the second access point AP, a second radio frame to a second station associated with the second access point AP during a transmission period in which the first access point AP transmits a third radio frame to a first station associated with the first access point AP. In this embodiment of the present application, since the second access point AP receives the first radio frame transmitted by the first access point AP, at least one second access point AP can simultaneously transmit a second radio frame to the second station at the same transmission time based on the first radio frame. By transmitting control information, multiple access points APs are synchronized, thereby solving the problem of the prior art that a relatively large number of channel resources are occupied for acquiring CSI.

[0017] In one possible embodiment, the instruction information includes a transmission time and an end time of the second wireless frame, and in this embodiment, the first access point AP uses the first wireless frame to instruct the second access point AP of the transmission time and the end time of the second wireless frame, so that the second access point AP can determine the transmission time of the second wireless frame according to the instruction.

[0018] In one possible embodiment, the transmission time of the second radio frame is the same as the transmission time of the third radio frame, and the third radio frame is transmitted by the first access point AP to the first station STA associated with the first access point AP during the transmission period of the second radio frame, and the transmission time of the third radio frame is the same as the transmission time of the second radio frame. In this embodiment, the third radio frame and the second radio frame are instructed to be transmitted at the same transmission time, thereby reducing interference between the first access point AP and the second access point AP.

[0019] In one possible embodiment, the transmission time of the second radio frame is before the transmission time of the third radio frame. In this embodiment, the transmission time of the second radio frame may be before the transmission time of the third radio frame, and for the first station STA and the second station STA, after the transmission of the radio frame with the later end time in the second radio frame and the third radio frame is completed, the first station STA may further transmit an acknowledgment frame in response to the third radio frame, and the second station STA may further transmit an acknowledgment frame in response to the second radio frame, thereby avoiding a case where one access point AP transmits while another access point AP receives, and reducing the value of interference between the first AP and the second AP.

[0020] In one possible implementation, the indication information includes identifier information of the second access point AP. In this implementation, the first radio frame may further include identifier information of the second access point AP to assist multiple second APs in determining whether to participate in cooperative transmission with the first access point AP based on the identifier information.

[0021] In one possible embodiment, the first radio frame further carries one or more of the following: transmission power information of the second access point AP, information on the maximum tolerable interference threshold of the first access point AP, identifier information of the first station STA, transmission power information of the first station STA, and transmission power information of the first access point AP. In this embodiment, the first radio frame may further carry multiple other types of instruction information to add a multi-AP joint resource management function. The transmission power of the second access point AP and the transmission power information of the first access point AP may be adjusted to effectively control the interference of the first access point AP with the second station STA and the interference of the second access point AP with the first station STA. Since the information on the maximum tolerable interference threshold of the first access point AP is indicated to the second access point AP, the second access point AP controls the transmission power of the second station STA to prevent the value of the second station STA's interference with the first access point AP from exceeding the information on the maximum tolerable interference threshold of the first access point AP. Since the identifier information of the first station STA and the transmission power information of the first station STA are instructed to the second access point AP, the second access point AP can predict the value of the interference of the first station STA with the second access point AP, and the interference of the first station STA with the second access point AP can be effectively controlled.

[0022] In one possible implementation, the transmission time of the second radio frame is the same as the transmission time of the third radio frame. In this implementation, the first access point AP configures the transmission time of the second radio frame to be the same as the transmission time of the third radio frame, so that the end time of the second radio frame can be aligned with the end time of the third radio frame, thereby reducing interference between the first access point AP and the second access point AP.

[0023] In one possible embodiment, before the step of the second access point AP receiving the first wireless frame transmitted by the first access point AP, the method further includes the step of the second access point AP transmitting a request frame to the first access point AP if the second access point AP has successfully acquired the channel through contention, the request frame being used to request the first access point AP to transmit the first wireless frame using the channel. In this embodiment, a method for the first access point AP to access a channel is provided, so that the first access point AP can transmit the first wireless frame based on the channel acquired by the second access point AP through contention.

[0024] In one possible embodiment, the indication information further includes resource scheduling information, which is used to indicate a channel resource to be used by the second access point AP to transmit the second wireless frame. In this embodiment, the first access point AP allocates the channel resource to be used by the second access point AP to transmit the second wireless frame, thereby improving the efficiency of the second access point AP transmitting the second wireless frame.

[0025] A third aspect of an embodiment of the present application provides a method for coordinated multi-access point AP transmission, the method including: a step of a first access point AP generating a first radio frame; and a step of the first access point AP transmitting the first radio frame to a second access point AP after generating the first radio frame, wherein the first radio frame is used to trigger the second access point AP to transmit the second radio frame to a second station STA associated with the second access point AP, and the first radio frame includes first instruction information such that the second access point AP determines a transmission end time of the second radio frame according to the first instruction information. In this embodiment of the present application, a first access point (AP) transmits a first wireless frame to a second access point (AP), triggering the second access point (AP) to transmit a second wireless frame to a second station (STA), and the second access point (AP) can determine the transmission end time of the second wireless frame according to the first instruction information in the first wireless frame, so that multiple second access points (AP) can end transmission at the same time, specifically, avoiding a case where one AP transmits while another AP receives, thereby reducing interference between APs and STAs.

[0026] A fourth aspect of the embodiment of the present application provides a method for coordinated multi-access point AP transmission, the method including: a second access point (AP) receiving a first wireless frame transmitted by a first access point (AP), where the first wireless frame carries first indication information; the second access point (AP) determining a transmission end time of the second wireless frame according to the first indication information; and the second access point (AP) transmitting the second wireless frame to a second station (STA) associated with the second access point (AP). In this embodiment of the present application, the second access point (AP) receives the first wireless frame transmitted by the first access point (AP) and determines a transmission end time of the second wireless frame according to the first indication information in the first wireless frame, so that multiple second access points (AP) can finish transmission simultaneously, specifically, avoiding a case where one AP transmits while another AP receives, thereby reducing interference between APs and STAs.

[0027] In one possible implementation, the first instruction information is used to indicate a transmission end time or a transmission duration of the first radio frame, where the transmission end time of the first radio frame is the same as the transmission end time of the second radio frame. The step of the second access point AP determining the transmission end time of the second radio frame in accordance with the first instruction information includes a step of the second access point AP determining the transmission end time of the first radio frame as the transmission end time of the second radio frame, or a step of the second access point AP determining the transmission end time of the first radio frame based on the transmission duration of the first radio frame and the transmission start time of the first radio frame, where the transmission end time of the first radio frame is equal to the transmission end time of the second radio frame. In this embodiment, since the transmission end time of the second wireless frame transmitted by the second access point AP is the same as the transmission end time of the first wireless frame transmitted by the first access point AP, a case in which one access point is transmitting while another access point is receiving is avoided, and correspondingly, a case in which one station is receiving data while another station is transmitting an acknowledgment frame is also avoided, thereby avoiding interference between access points and between stations.

[0028] A fifth aspect of an embodiment of the present application provides a channel information prediction method, the method including: a step of a first station STA receiving a broadcast frame from a first access point AP, where the broadcast frame includes identifier information of a second access point AP, and the broadcast frame is used to trigger the first station STA to detect a channel between the second access point AP and the first station STA, where the first station STA is associated with the first access point AP; a step of the first station STA determining channel quality information of a target channel based on a received radio frame transmitted by a target AP, where the target channel is a channel between the target AP and the first station STA, and the target AP is included in the second access point AP; and a step of the first station STA transmitting a feedback frame to the first access point AP, where the feedback frame includes the channel quality information of the target channel. In this embodiment of the present application, when scheduling a first station STA for transmission, the first access point AP can select an appropriate MCS based on the channel quality information of the target channel fed back by the first station STA to achieve a balance between the transmission rate and the packet loss rate.

[0029] In one possible embodiment, the broadcast frame may further include sequence indication information, which is used to instruct the second access point AP to broadcast the null data packets NDP sequentially. In this embodiment, the first access point AP can instruct the second access point AP to transmit the NDP sequentially, so that the first station STA measures channel information based on the NDPs sequentially transmitted by the multiple second access points APs. This is more orderly and efficient than the method in which the first station STA measures channel information by receiving beacon frames transmitted by the multiple second access points APs after different periods.

[0030] In one possible embodiment, the wireless frame transmitted by the target AP may be NDP, and after the first station STA receives the wireless frame transmitted by the target AP and before the first station STA transmits a feedback frame to the first access point AP, the method further includes the first station STA determining the AP that is the target AP based on the order indication information. In this embodiment, after receiving the wireless frame, the first station STA needs to determine the AP that will transmit the wireless frame based on the order indication information, so that when the first station STA provides feedback to the first access point AP, the first access point AP can know the access point, and the channel between the first station STA and the access point is detected.

[0031] In one possible embodiment, before the step of the first station STA transmitting a feedback frame to the first access point AP, the method further includes the step of the first station STA receiving a trigger frame transmitted by the first access point AP, the trigger frame being used to trigger the first station STA to transmit the feedback frame, the trigger frame including resource scheduling information, the resource scheduling information being used to indicate the channel resource used by the first station STA to transmit the feedback frame, or the step of the first station STA successfully acquiring a channel through contention, the channel being used to transmit the feedback frame. In this embodiment, two methods are provided for the first station STA to transmit the feedback frame, including a method in which the feedback frame is transmitted using the channel resource allocated by the first access point AP, or a method in which the feedback frame is transmitted using the channel acquired through contention. If the feedback frame is transmitted using the channel resource allocated by the first access point AP, the first STA may not need to contend for the channel, thereby improving the efficiency of the first station STA transmitting the feedback frame.

[0032] A sixth aspect of an embodiment of the present application provides a channel information prediction method, the method including: a step of a first access point (AP) transmitting a broadcast frame to a first station (STA) associated with the first access point (AP), wherein the broadcast frame carries identifier information of a second access point (AP), and the broadcast frame is used to trigger the first station (STA) to detect a channel between the second access point (AP) and the first station (STA); and a step of the first access point (AP) receiving a feedback frame transmitted by the first station (STA), wherein the feedback frame carries channel quality information of a target channel detected by the first station (STA), the target channel is a channel between the target AP and the first station (STA), the target AP is an AP for communicating with the first station (STA), and the target AP is included in the second access point (AP). In this embodiment of the present application, the first access point AP uses a broadcast frame to trigger the first station STA to detect a channel between the second access point AP and the first station STA, and receives channel quality information of the target channel that can be detected by the second access point AP fed back by the first station STA, so that the first access point AP can predict the signal-to-interference ratio of the first station STA based on the channel quality information of the target channel, and further, when scheduling the first station STA for transmission, the first access point AP can select an appropriate MCS to achieve a balance between the transmission rate and the packet loss rate.

[0033] In one possible embodiment, after the first access point AP receives the feedback frame transmitted by the first station STA, the method further includes the first access point AP determining a signal-to-interference ratio (SIR) of the first station STA based on the channel quality information of the target AP. In this embodiment, since the first access point AP determines the SIR of the first station STA, when scheduling the first station STA for transmission, the first access point AP can select an appropriate MCS to achieve a balance between transmission data and packet loss rate.

[0034] In one possible embodiment, before the step of the first access point AP receiving the feedback frame transmitted by the first station STA, the method further includes a step of the first access point AP transmitting a trigger frame to the first station STA, the trigger frame being used to trigger the first station STA to transmit the feedback frame, the trigger frame carrying resource scheduling information, and the resource scheduling information being used to indicate channel resources used by the first station STA to transmit the feedback frame. In this embodiment, a method for the first station STA to transmit a feedback frame is provided, the method including a method in which the feedback frame is transmitted using channel resources allocated by the first access point AP, thereby improving the efficiency of the first station STA transmitting the feedback frame.

[0035] In one possible embodiment, the broadcast frame further carries sequence indication information, which is used to indicate the sequence in which the second access point AP transmits null data packets NDP, so that the first station STA performs signal quality detection on the channel between the second access point AP and the first station STA based on the received NDP. In this embodiment, the first access point AP can instruct the second access point AP to transmit NDPs sequentially, so that the first station STA measures channel information based on the NDPs sequentially transmitted by multiple second access points AP. This is more orderly and efficient than the method in which the first station STA measures channel information by receiving beacon frames transmitted by multiple second access points APs after different periods.

[0036] A seventh aspect of the present application provides an apparatus for coordinated multi-access point AP transmission. The apparatus includes: a processor configured to generate a first radio frame, the first radio frame including indication information used to indicate a transmission time of a second radio frame transmitted by a second access point AP; and a transceiver configured to transmit the first radio frame to the second access point AP, the transceiver further configured to transmit a third radio frame to a first station associated with the first access point AP during the transmission period of the second radio frame. In this embodiment of the present application, since the transceiver transmits the first radio frame to the second access point AP, at least one second access point AP can simultaneously transmit a second radio frame to a second station at the same transmission time based on the first radio frame. By transmitting control information, multiple access points APs are synchronized, thereby solving the problem of the prior art that a relatively large number of channel resources are occupied for acquiring CSI.

[0037] An eighth aspect of the present application provides an apparatus for coordinated multi-access point AP transmission. The apparatus includes a transceiver adapted to a second access point AP, configured to receive a first radio frame transmitted by a first access point AP, the first radio frame including an indication of a transmission time of the second radio frame, and further configured to transmit the second radio frame to a second station associated with the second access point AP during a transmission period in which the first access point AP transmits a third radio frame to a first station associated with the first access point AP. In this embodiment of the present application, the transceiver receives the first radio frame transmitted by the first access point AP and simultaneously transmits a second radio frame to the second station STA at the same transmission time based on the first radio frame. By transmitting control information, multiple access points AP are synchronized, thereby solving the problem of the prior art that a relatively large number of channel resources are occupied for acquiring CSI.

[0038] A ninth aspect of an embodiment of the present application provides an apparatus for coordinated multi-access point AP transmission, the apparatus being applied to a first access point AP side and including: a processor configured to generate a first radio frame; and a transceiver configured to transmit the first radio frame to a second access point AP, the first radio frame being used to trigger the second access point AP to transmit the second radio frame to a second station STA associated with the second access point AP, the first radio frame including first indication information, the first indication information being used by the second access point AP to determine a transmission end time of the second radio frame. In this embodiment of the present application, the transceiver transmits a first wireless frame to the second access point AP to trigger the second access point AP to transmit a second wireless frame to the second station STA, so that the second access point AP can determine the transmission end time of the second wireless frame according to the first instruction information in the first wireless frame, and multiple second access points AP can end transmission at the same time, specifically, avoiding the case where one AP transmits while another AP receives, thereby reducing interference between APs and STAs.

[0039] A tenth aspect of the present application provides an apparatus for coordinated multi-access point AP transmission. The apparatus is applied to a second access point AP side and includes: a transceiver configured to receive a first radio frame transmitted by a first access point AP, where the first radio frame carries first instruction information; and a determination unit configured to determine a transmission end time of the second radio frame according to the first instruction information, where the transceiver is further configured to transmit the second radio frame to a second station STA associated with the second access point AP. In this embodiment of the present application, the transceiver receives the first radio frame transmitted by the first access point AP, and the determination unit determines the transmission end time of the second radio frame according to the first instruction information in the first radio frame. Therefore, multiple second access points APs can end transmission simultaneously, specifically, avoiding a case where one AP transmits while another AP receives, thereby reducing interference between APs and STAs.

[0040] An eleventh aspect of an embodiment of the present application provides a channel information detection device, which is applied to a first station (STA) side and includes: a transceiver configured to receive a broadcast frame transmitted by a first access point (AP), the broadcast frame including identifier information of a second access point (AP), the broadcast frame being used to trigger the first station (STA) to detect a channel between the second access point (AP) and the first station (STA), the first station (STA) being associated with the first access point (AP); and a determination unit configured to determine channel quality information of a target channel based on a received wireless frame transmitted by a target AP, the target channel being a channel between the target AP and the first station (STA), the target AP being included in the second access point (AP), the transceiver further configured to transmit a feedback frame to the first access point (AP), the feedback frame including the channel quality information of the target channel. In this embodiment of the present application, when scheduling a first station STA for transmission, the first access point AP can select an appropriate MCS based on the channel quality information of the target channel fed back by the first station STA to achieve a balance between the transmission rate and the packet loss rate.

[0041] A twelfth aspect of the embodiment of the present application provides a channel information detection device, which is applied to a first access point (AP) side and includes a transceiver configured to: transmit a broadcast frame to a first station (STA) associated with the first access point (AP), the broadcast frame carrying identifier information of a second access point (AP), the broadcast frame being used to trigger the first station (STA) to detect a channel between the second access point (AP) and the first station (STA), receive a feedback frame transmitted by the first station (STA), the feedback frame carrying channel quality information of a target channel detected by the first station (STA), the target channel being a channel between the target AP and the first station (STA), and the target AP being included in the second access point (AP). In this embodiment of the present application, the transceiver uses a broadcast frame to trigger the first station STA to detect a channel between the second access point AP and the first station STA, and receives channel quality information of the target channel that can be detected by the second access point AP fed back by the first station STA, so that the first access point AP can predict the signal-to-interference ratio of the first station STA based on the channel quality information of the target channel, and further, when scheduling the first station STA for transmission, the first access point AP can select an appropriate MCS to achieve a balance between the transmission rate and the packet loss rate.

[0042] A thirteenth aspect of the present application provides a communication device. The communication device has a function of implementing the behavior of the first access point AP or the behavior of the second access point AP in the above-mentioned method design. These functions can be implemented by hardware, or by the hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the functions. The modules can be software and / or hardware.

[0043] In one possible implementation, the communication device includes a storage unit, a processing unit, and a communication unit.

[0044] The memory unit is configured to store program code and data required by the communication device, the processing unit is configured to invoke the program code to control and manage the operation of the communication device, and the communication unit is configured to assist the communication device in communicating with another device.

[0045] In one possible embodiment, the communication device has a structure including a processor, a memory, a baseband circuit, a radio frequency circuit, an antenna, and a bus. The processor, the memory, the baseband circuit, the radio frequency circuit, and the antenna are connected to each other using the bus. The memory stores corresponding operation instructions. The processor executes the operation instructions to control the radio frequency circuit, the baseband circuit, and the antenna to help the first access point AP or the second access point AP perform corresponding functions in the aforementioned method.

[0046] Another aspect of the present application provides a station, which has functions for implementing the station in the above-described method embodiments. These functions can be implemented by hardware, or by the hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the functions.

[0047] Another aspect of an embodiment of the present application provides a station including a processor, a memory, a bus, a transmitter, and a receiver. The memory is configured to store computer-executable instructions. The processor is connected to the memory using the bus. When the station is operational, the processor executes the computer-executable instructions stored in the memory, causing the station to perform a channel information prediction method according to a fifth aspect.

[0048] Another aspect of an embodiment of the present application provides an apparatus. The apparatus includes a memory. The memory is configured to store instructions. When executed by a processor, the instructions stored in the memory enable the processor to perform corresponding functions performed by a first access point (AP), a second access point (AP), or a first station (STA) in the aforementioned method, such as transmitting or processing data and / or information in the aforementioned method. The apparatus may include a chip, or may include a chip and another discrete component.

[0049] Another aspect of an embodiment of the present application provides a system, the system including a first access point AP according to the first aspect and a second access point AP according to the second aspect, or a first access point AP according to the third aspect and a second access point AP according to the fourth aspect, or a first station STA according to the fifth aspect and a first access point AP according to the sixth aspect, or a first access point AP according to the seventh aspect and a second access point AP according to the eighth aspect, or a first access point AP according to the ninth aspect and a second access point AP according to the tenth aspect, or a first access point AP according to the eleventh aspect and a second access point AP according to the twelfth aspect.

[0050] Another aspect of an embodiment of the present application provides a computer-readable storage medium storing instructions that, when executed on a computer, enable the computer to perform a method according to the aforementioned aspect.

[0051] Another aspect of an embodiment of the present application provides a computer program product comprising instructions that, when executed on a computer, enable the computer to perform a method according to the aforementioned aspect.

[0052] From the above technical solution, it can be seen that in the embodiment of the present application, a first access point (AP) transmits a first radio frame to a second access point (AP), and at least one second access point (AP) can simultaneously transmit a second radio frame to a second station (STA) at the same transmission time based on the first radio frame. By transmitting control information, multiple access points (APs) are synchronized, specifically, to avoid a case where one AP transmits while another AP receives, thereby reducing interference between APs and STAs. [Brief explanation of the drawings]

[0053] [Figure 1a] FIG. 1 is an example of a schematic diagram of a co-BF technique in the prior art. [Figure 1b] 1 is an example of an architecture diagram of a system according to an embodiment of the present application. [Figure 2a] 1 is an example of a flowchart of a method for coordinated multi-access point AP transmission according to an embodiment of the present application; [Figure 2b] FIG. 2 is an example of a schematic diagram of a frame format of a first radio frame according to an embodiment of the present application; [Figure 2c] FIG. 10 is another example of a schematic diagram of a frame format of a first radio frame according to an embodiment of the present application; [Figure 2d] 1 is an example of a schematic diagram of synchronous aligned transmission according to an embodiment of the present application; [Figure 2e] 10 is another example of a schematic diagram of synchronous aligned transmission according to an embodiment of the present application; [Figure 2f-1] FIG. 1 is an example of a schematic diagram of a transmission according to an embodiment of the present application; [Figure 2f-2] FIG. 1 is an example of a schematic diagram of a transmission according to an embodiment of the present application; [Figure 3a] 2 is an example of a flowchart of a method for coordinated multi-AP transmission according to an embodiment of the present application. [Figure 3b] 10 is another example of a schematic diagram of synchronous aligned transmission according to an embodiment of the present application; [Figure 3c]10 is another example of a schematic diagram of synchronous aligned transmission according to an embodiment of the present application; [Figure 4a] 2 is an example of a flowchart of a method for coordinated multi-AP transmission according to an embodiment of the present application. [Figure 4b] 1 is an example of a schematic diagram of downstream ordering transmission according to an embodiment of the present application; [Figure 4c] 10 is another example of a schematic diagram of downstream ordering transmission according to an embodiment of the present application; [Figure 4d] 10 is another example of a schematic diagram of downstream ordering transmission according to an embodiment of the present application; [Figure 5a] 1 is an example of a flowchart of an information prediction method according to an embodiment of the present application. [Figure 5b] FIG. 1 is an example of a schematic diagram of a transmission according to an embodiment of the present application; [Figure 5c] 1 is a diagram showing an example of the frame structure of a Trigger frame defined by the standard. [Figure 5d] 10 is a schematic diagram of an example of information included in a common information field (Common info) in a trigger frame (Trigger). FIG. [Figure 5e] FIG. 10 is a schematic diagram of information that may be included in a User Info field in a Trigger frame. [Figure 5f] 1 is an example of a schematic diagram of a frame structure of a broadcast frame according to an embodiment of the present application; [Figure 5g] FIG. 1 is an example of a schematic diagram of a frame structure of a feedback frame according to an embodiment of the present application; [Figure 5h] FIG. 10 is another example of a schematic diagram of a frame structure of a feedback frame according to an embodiment of the present application; [Figure 5i] FIG. 10 is another example of a schematic diagram of a frame structure of a feedback frame according to an embodiment of the present application; [Figure 6] 1 is an example of a schematic structural diagram of an apparatus for coordinated multi-AP transmission according to an embodiment of the present application; [Figure 7] 1 is another example of a schematic structural diagram of an apparatus for coordinated multi-AP transmission according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0054] The embodiments of the present application provide a method and related apparatus for coordinated multi-AP transmission to solve the problem in the prior art that a relatively large number of channel resources are occupied to obtain CSI.

[0055] The following clearly and fully describes the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part but not all of the embodiments of the present application.

[0056] An embodiment of the present application provides a method for cooperative multi-AP transmission. The method may be applied to a wireless local area network. Figure 1b is an example of an architecture diagram of a system according to an embodiment of the present application. The system includes at least two wireless access points, AP1 and AP2, and two stations, STA1 and STA2. STA1 is a station associated with AP1, and STA2 is a station associated with AP2. In this embodiment of the present application, a first AP1 may exchange control information with a second AP2 to implement transmission coordination when the AP transmits to an associated STA, thereby solving the problem in the prior art that a relatively large number of channel resources are occupied to obtain CSI and reducing transmission interference.

[0057] It should be understood that the number of APs and the number of STAs in a WLAN communication system are merely examples and do not constitute limitations on this embodiment of the present application. Those skilled in the art will understand that an AP in this embodiment of the present application is a device disposed in a wireless communication network and provides wireless communication functions to stations, and may be used as a hub of a WLAN. For example, an AP may be a base station, a router, a gateway, or a repeater. A base station may include various types of macro base stations, micro base stations, relay nodes, etc. Correspondingly, a STA in this embodiment of the present application may be any suitable device connected to a distributed network via a wireless link. For example, a STA may be a user terminal, a user device, an access device, a mobile station, a user equipment, or another name. User terminals may include various handheld devices, in-vehicle devices, wearable devices (such as smart watches or smart bands) with wireless communication capabilities, computing devices, or other processing devices connected to a wireless modem, as well as various forms of user equipment (UE), mobile stations (MS), terminals, terminal equipment, portable communications devices (such as cellular GPRS phones), handsets, portable computing devices, entertainment devices, gaming devices or systems, global positioning system devices, ultra wideband (UWB) devices, wireless devices, or any other suitable devices configured to communicate over a wireless medium with a network.

[0058] In the embodiment of the present application, there may be multiple methods for coordinated multi-AP transmission for various scenarios. Coordinated multi-AP transmission in the embodiment of the present application means that two or more APs coordinate with each other to schedule radio resources by exchanging control information. Methods for coordinated multi-AP transmission include the following methods: Method A: Synchronous and aligned transmission of multiple APs during downlink transmission; Method B: Implementing synchronous aligned transmission of multiple STAs during uplink transmission; and Method C: Implementing aligned transmission of multiple APs during downlink transmission.

[0059] It should be noted that synchronous transmission in the embodiments of the present application can be understood as multiple transceivers starting to transmit their respective radio frames at the same time, and the clocks of the multiple transceivers being synchronized. For example, the multiple transceivers include AP01 and AP02, and the clocks of AP01 and AP02 are synchronized. The synchronous transmission between AP01 and AP02 means that AP01 starts to transmit radio frame 01 at time A, and AP02 also starts to transmit radio frame 02 at time A.

[0060] In the embodiments of the present application, aligned transmission can be understood as multiple transceivers completing the transmission of their respective radio frames at the same time, and the clocks of the multiple transceivers being synchronized. For example, the multiple transceivers including AP03 and AP04, the clocks of AP03 and AP04 being synchronized. Aligned transmission between AP03 and AP04 means that AP03 completes the transmission of radio frame 03 at time B, and AP04 also completes the transmission of radio frame 04 at time B.

[0061] It should be understood that synchronous aligned transmission means that multiple transceivers start transmitting their respective radio frames at the same time and finish transmitting their respective radio frames at the same time. For example, the multiple transceivers include AP01 and AP02, and the clocks of AP01 and AP02 are synchronized. Synchronous transmission between AP01 and AP02 means that AP01 starts transmitting radio frame 01 at time C and finishes transmitting radio frame 01 at time D, and AP02 also starts transmitting radio frame 02 at time C and finishes transmitting radio frame 02 at time D.

[0062] The aforementioned methods are described below with reference to specific embodiments.

[0063] Referring to Figure 2a, a method embodiment in which coordinated multi-AP transmission is performed using Method A in an embodiment of the present application is described. For ease of understanding, this embodiment may be briefly described with reference to the system framework diagram shown in Figure 1b. This method may include:

[0064] AP1 transmits control information to AP2. After receiving the control information, AP2 transmits data to STA2 after a specific time, e.g., 4 ms. If AP2 includes multiple APs, the time from receiving the control information by one AP2 to transmitting data by that AP2 is the same as the time from receiving the control information by another AP2 to transmitting data by that AP2, and the transmission time of the transmitted data is also the same. Specifically, to achieve synchronous aligned transmission of multiple APs during downlink transmission, the multiple APs start transmitting data at the same time, and the transmission time of the transmitted data is also the same, so the data transmission also ends at the same time. AP1 can also be synchronized with multiple APs2.

[0065] A description is provided below based on specific steps.

[0066] 201. The first AP accesses the channel.

[0067] In this embodiment, the AP that initiates multi-AP cooperation is called the first AP, and the AP that exchanges control information with the first AP is called the second AP. Since the Wi-Fi frequency band is an unlicensed frequency band, multiple APs should access the channel through contention to transmit wireless frames. The following two cases can be used for explanation: In case 1, an AP is selected as the first AP; in case 2, any AP can be the first AP.

[0068] In one example of Case 1, the selected AP, i.e., the first AP, successfully acquires the channel through contention and transmits a first wireless frame over the channel, which may be used to initiate cooperative multi-AP transmission. In another example, the first AP loses contention for the channel, and the AP that successfully acquires the channel through contention transmits a request frame to the first AP, which is used to request the first AP to access the channel and transmits a first wireless frame over the channel.

[0069] In one example of Case 2, any AP can contend for the channel using the channel access method, and the AP that successfully contends is the first AP and will transmit the first wireless frame, thereby triggering a cooperative multi-AP transmission. It will be understood that the AP that obtains the channel through contention is used to transmit the first wireless frame as the first AP.

[0070] In this embodiment of the present application, APs may contend for the channel in multiple ways. In one example, the channel is contended for based on a channel access method using carrier sense multiple access with collision avoidance (CSMA / CA). In another example, the APs may contend for the channel based on a request to send / clear to send (RTS / CTS) channel access mechanism or a point coordination function (PCF), which is not particularly limited herein.

[0071] 202. The first AP determines the second AP.

[0072] When inter-cell interference needs to be reduced through cooperation between multiple APs, the first AP determines a second AP to participate in the cooperation. In this embodiment, there are multiple bases for the first AP to determine the second AP. In one example, the first AP obtains received signal strength indications (RSSIs) of neighboring APs and determines, as the second AP, an AP corresponding to an RSSI having a value included in a first value range. A neighboring AP may be understood as an AP that can communicate with the first AP. In another example, the first AP determines a physical distance between the first AP and each of the neighboring APs and selects a second AP from the neighboring APs, so that the physical distance between the first AP and the second AP is within a second value range. In yet another example, the first AP may determine a fit AP among the neighboring APs as the second AP. In this embodiment, a fit AP is understood as an AP that needs to be managed, operated, and controlled by a radio controller. That is, a fit AP cannot operate independently and needs to be used in cooperation with a radio controller. In yet another example, the first AP may determine the second AP based on the service requirement information. Therefore, the method by which the first AP determines the second AP is not particularly limited herein. It should be understood that the second AP may be one or more APs.

[0073] It should be noted that in practical application, this step is an optional step. Specifically, the first AP may enable all neighboring APs to participate in cooperation.

[0074] 203. The first AP generates a first radio frame.

[0075] The first AP generates a first radio frame, which is used to initiate coordinated multi-AP transmission. It should be noted that the first radio frame includes at least first indication information, which is used to indicate to the second AP the transmission time of the second radio frame, in order to achieve synchronized aligned transmission of the multiple APs during downlink transmission.

[0076] In this embodiment of the present application, the transmission time may be understood as the time from the start of transmission of a radio frame by a transceiver device to the completion of transmission of the radio frame, and it should be noted that the transmission time is related to the size of the radio frame. In practical application, the transmission time may alternatively have another name, such as a transmission delay, which is not particularly limited herein. The transmission time may be directly indicated by a duration or may be indicated by the transmission time and end time of the radio frame, which is not particularly limited herein.

[0077] In this embodiment, the first AP generates the first radio frame. After receiving the first radio frame, the second AP transmits a second radio frame to a second STA associated with the second AP after a first time to achieve synchronization of the multiple APs. The first time may be a predetermined short inter-frame space (SIFS) or may be defined by the first AP. If the first time is defined by the first AP, the first radio frame may further include indication information about the first time.

[0078] Optionally, the first radio frame may further include second indication information to indicate the second AP to participate in the cooperative transmission initiated by the first AP. The second indication information is used to indicate the identifier information of the second AP, so that after receiving the first radio frame, the second AP determines whether the second AP needs to participate in the cooperative multi-AP transmission according to the second indication information. Note that in this embodiment, there may be multiple cases for the identifier information of the second AP. In one example, the identifier information of the second AP may be the media access control (MAC) address of the second AP. In another example, the identifier information of the second AP may be a part of the MAC address of the second AP. In yet another example, the first AP may assign an address to the second AP, or the second AP may determine an address and instruct the first AP to add the address to the first wireless frame, or the identifier information of the second AP is the identifier information of a device (which may be a STA or an AP) that has a binding relationship with the second AP, so that after receiving a frame sent by the first AP to the second AP, the device forwards the frame to the second AP through an internal interface between the device and the second AP. Therefore, the identifier information of the second AP is not particularly limited here.

[0079] Optionally, the first AP may further instruct the second AP to sense the channel within a first time period after the second AP receives the first wireless frame. After the second AP receives the first wireless frame, if the second AP detects through sensing within the first time period that the channel between the second AP and the second STA is idle, the second AP may transmit the second wireless frame to the associated second STA. Otherwise, if the channel between the second AP and the second STA is occupied, the second AP does not transmit the second wireless frame. Therefore, the first wireless frame may further include third indication information, which is used to indicate whether the second AP needs to sense the channel between the second AP and the second STA before transmitting the second wireless frame to the second STA. In one example, a 1-bit channel sensing (CS) indication field may be set in the first wireless frame. For example, if the CS indication field is set to 1, this indicates that the second AP needs to sense the channel and transmit the second wireless frame to the second STA only when the channel between the second AP and the second STA is idle. If the CS indication field is set to 0, this indicates that the second AP does not need to sense the channel, and specifically, after receiving the first wireless frame, the second AP transmits the second wireless frame to the second STA after a first time regardless of whether the channel between the second AP and the second STA is idle.

[0080] Optionally, to implement joint resource management function, the first radio frame may further carry some control information to assist the second AP in performing radio resource management. An example is described below.

[0081] Since the transmission by the first AP and the transmission by the second AP are performed on the same channel, in order to reduce interference of the second AP with the first STA associated with the first AP, the first radio frame may carry fourth instruction information, where the fourth instruction information is used to indicate transmission power information of each second AP, where the transmission power information may be a maximum transmission power or a transmission power configured for the second AP by the first AP, so that the value of interference of the second AP with the first STA falls within a third value range. The third value range may be predefined.

[0082] Optionally, to enable the second AP to predict the value of interference of the first AP to the second STA before transmitting the second radio frame, the first radio frame may further carry fifth indication information, which is used to indicate the transmission power information of the first AP.

[0083] Optionally, to reduce interference of the second STA with the first AP, the first radio frame may carry sixth indication information, where the sixth indication information is used to indicate information about the first AP's maximum tolerable interference threshold, and the second AP determines power indication information for each associated second STA based on the sixth indication information. The power indication information may be used by each second STA to determine a maximum transmission power. In addition, the power indication information may also be included in the second radio frame transmitted by the second AP to the second STA. In one possible embodiment, the information about the maximum tolerable interference threshold may be a value of a spatial reuse parameter (SRP). The SRP may be used by the second AP to adjust transmission power during spatial reuse transmission. Therefore, the second AP may set transmission parameters for the associated second STA based on the value of the SRP. Correspondingly, in order to enable the second AP to predict the value of interference of the first STA to the second AP when the second AP receives the radio frame transmitted by the second STA before transmitting the second radio frame, the first radio frame may carry seventh indication information and eighth indication information, where the seventh indication information is used to indicate identifier information of the first STA and the eighth indication information is used to indicate transmission power information of the first STA.

[0084] Optionally, the first radio frame may be extended to ensure that the second AP has sufficient time to prepare data transmission after receiving the first radio frame. Therefore, after obtaining each indication information included in the first radio frame by decoding, the second AP has a specific time to prepare data after the transmission of the first radio frame is completed. In one example, a padding field is added to the first radio frame, and useless information is padded into the padding field. Therefore, the first radio frame may include a ninth indication information for indicating the length of the padding field. For ease of understanding, FIG. 2b is a schematic diagram of an example of a frame format of the first radio frame according to an embodiment of the present application. Each AP information field may include an AP ID field and an other information field following the AP ID field. In one example, the AP info field may be used as a padding field. The AP ID in the padding field may be set to a special AP ID field, such as all 1s or all 0s, to indicate the start of the padding field. Upon detecting the special AP ID field, the second AP may determine that the subsequent other information field is padded with useless information, so that the second AP can prepare data in time to receive the padding field. Figure 2c is an example of a schematic diagram of a frame format of a first radio frame according to this embodiment. In the figure, the AP info field adjacent to the frame check sequence (FCS) can be understood as a padding field. AP ID in the AP info field is a special value, and the other information field following the AP ID field in the AP info field contains useless information.

[0085] Optionally, for better radio resource management, the first AP may further perform centralized scheduling to determine transmission parameters of the second AP. Specifically, the first AP allocates and indicates resource scheduling information to the second AP. Thus, the first radio frame may further carry tenth indication information, and the tenth indication information is used to indicate the resource scheduling information, so that the second AP determines the channel resources to be used to transmit the second radio frame based on the resource scheduling information. The resource scheduling information may include, but is not limited to, one or more combinations of resource block (RU) allocation information of each second AP, identifier information of stations scheduled by the second AP (i.e., identifier information of the second STA), modulation and coding scheme (MCS) used by each station, or spatial streams used by each station.

[0086] Optionally, since there are different application scenarios in actual applications, such as uplink transmission and downlink transmission, in this embodiment of the present application, the first radio frame may include eleventh indication information, which is used to instruct uplink transmission or downlink transmission. In one example, a 1-bit uplink / downlink indication field may be set in the first radio frame. For example, if the uplink / downlink indication field is set to 0, this indicates that uplink transmission needs to be performed, specifically, that the second AP triggers the second STA to transmit a radio frame. If the uplink / downlink indication field is set to 1, this indicates that downlink transmission needs to be performed, specifically, that the second AP needs to transmit a radio frame to the second STA. It should be noted that in this embodiment, the eleventh indication information is used to instruct downlink transmission.

[0087] Optionally, considering that the present application further provides multiple cooperative transmission modes, such as synchronous transmission, aligned transmission, and synchronous aligned transmission, the first AP may instruct the second AP of a specific transmission mode before the second AP participates in the cooperative transmission. The first AP may have an instruction method including:

[0088] The first radio frame includes twelfth indication information, which is used to indicate whether synchronous transmission is required. In this embodiment, the twelfth indication information is used to indicate that synchronous transmission is required. If the twelfth indication information indicates that multiple APs do not need to perform synchronous transmission, specifically, that the second AP does not need to start transmission simultaneously, it should be noted that the second AP may independently determine the transmission start time, and the second AP may or may not perform aligned transmission.

[0089] Optionally, the first radio frame may further include thirteenth indication information, which is used to indicate whether aligned transmission is required. If the thirteenth indication information indicates that multiple APs do not need to perform aligned transmission, specifically, that the second AP does not need to end transmission simultaneously, the second AP may independently determine the transmission end time.

[0090] In some specific scenarios, when there is a relatively long distance between APs and a relatively long distance between STAs, asynchronous transmission and non-aligned transmission may be permitted. In this embodiment, to indicate to the second AP the asynchronous transmission and non-aligned transmission, the first AP may add both twelfth and thirteenth indications to the first radio frame. The twelfth indication is used to indicate that the multiple APs do not need to perform synchronous transmission, and the thirteenth indication is used to indicate that the multiple APs do not need to perform aligned transmission.

[0091] Optionally, the first radio frame includes fourteenth indication information, which is used to indicate a mode of coordinated multi-AP transmission. In one example, a 2-bit transmission indication field may be set in the first radio frame. For example, if the transmission indication field is 01, this indicates that synchronous transmission is required. If the transmission indication field is 10, this indicates that aligned transmission is required. If the transmission indication field is 00, this indicates asynchronous transmission and non-aligned transmission. If the transmission indication field is 11, this indicates synchronous aligned transmission. Therefore, this application does not limit a specific indication method.

[0092] Optionally, when the first AP decides to perform asynchronous and unaligned transmission, the first AP may instruct the acknowledgement policy (ACK policy) to be set to block ACK (BA) when the second AP transmits the second wireless frame to the second STA, so that after receiving the second wireless frame, the second STA does not immediately respond to the BA frame, but responds to the BA frame after receiving a block ACK request (BAR) frame sent by the second AP, thereby reducing interference caused by the possible case where the second STA transmits a BA frame while the second AP transmits a data frame. For example, a first AP instructs a second AP to transmit a second radio frame to a second STA, and during the transmission period of the second radio frame, the first AP transmits a third radio frame to the first STA associated with the first AP. In other words, the transmission time of the second radio frame may be different from the transmission time of the third radio frame, and the end time of the second radio frame may be different from the end time of the third radio frame, but there may be a common portion between the transmission period of the second radio frame and the transmission period of the third radio frame. In this embodiment of the present application, the transmission period may be understood as a corresponding time segment from the start of transmission of a radio frame by a transceiver to the completion of transmission of the radio frame. For example, the transceiver starts transmitting a radio frame at time A and ends transmitting the radio frame at time B, so the transmission period of the radio frame is from time A to time B. Therefore, for ease of understanding, the transmission period of the second radio frame is set to [time 1, time 2], and the transmission period of the third radio frame is set to [time 3, time 4], where time 3 may be earlier than time 1 and time 4 may not be equal to time 2. Therefore, there may be a common portion between the transmission period of the second radio frame and the transmission period of the third radio frame.In order to avoid a case where another access point receives an acknowledgment frame while one AP is transmitting a wireless frame, the first AP instructs the second AP to set an ACK policy so that the second STA does not immediately respond with an acknowledgment frame after receiving the second wireless frame, but instead sends an acknowledgment frame to the second AP after the second AP sends an acknowledgment frame request to the second STA after both the transmission of the first wireless frame and the transmission of the second wireless frame have been completed.

[0093] Therefore, the first radio frame may further carry fifteenth indication information, which is used to instruct adding an ACK policy to the second radio frame.

[0094] In conclusion, in addition to the first indication information, the first radio frame may further carry multiple indication information, as shown in Table 1.

[0095] [Table 1]

[0096] For ease of explanation, in this embodiment, information that needs to be instructed by the first AP to the second AP is referred to as "information to be instructed." The information to be instructed includes at least the first instruction information and may further include, but is not limited to, one or more combinations of the instruction information shown in Table 1. Note that all of the information to be instructed may be included in the first radio frame. For example, if the information to be instructed includes the first to fourth instruction information, the first radio frame includes the first to fourth instruction information. In one example, all information in the information to be instructed other than the first instruction information may not be included in the first radio frame. For example, if the information to be instructed includes the first to fourth instruction information, after determining the second AP to participate in the cooperative transmission, the first AP transmits a control frame to the second AP. The control frame includes the second instruction information and the third instruction information. After acquiring the channel through contention, the first AP transmits a first radio frame to the second AP to trigger multi-AP transmission. The first radio frame includes the first indication information and the fourth indication information, and therefore, the method by which the first AP transmits the information to be instructed to the second AP is not limited herein.

[0097] It should be noted that in this embodiment, the first AP accesses a channel using step 201, determines the second AP using steps 202 and 203, and generates a first wireless frame. These steps are not limited to a specific order in the two processes, and step 201 may be performed first, or steps 202 and 203 may be performed first, or these steps may be performed simultaneously. This is not particularly limited here.

[0098] 204. The second AP receives the first wireless frame transmitted by the first AP.

[0099] After accessing the channel, the first AP transmits a generated first wireless frame to the determined second AP to initiate cooperative multi-AP transmission. After receiving the first wireless frame, the second AP transmits a second wireless frame to a second STA associated with the second AP after a first time period. The transmission time of the second wireless frame is the transmission time indicated by the first instruction information. In addition, the first time period may be a time period defined by the first AP or a preset time period.

[0100] It should be noted that in practical application, in order to improve data transmission efficiency and reduce bit error rate, the transmitting end, i.e., the first AP in this embodiment, may sequentially perform operations such as encoding, modulation, frame mapping, inverse fast Fourier transform, and cyclic prefix (CP) addition on the first radio frame, and then transmit the first radio frame to the receiving end, i.e., the second AP in this application, via a channel. Correspondingly, after receiving the first radio frame transmitted by the first AP, the second AP sequentially performs CP removal, fast Fourier transform, data extraction, channel estimation, equalization, demodulation, and decoding processes on the received first radio frame. In this application, a decoding operation can be performed on the first radio frame encoded by existing technical means. Details are not described in this application.

[0101] In addition, as described in step 203, the first radio frame may include multiple types of indication information, and the second AP participates in the cooperative multi-AP transmission according to each type of indication information in the first radio frame. Details are as follows:

[0102] The second AP determines, according to the first indication information, a transmission time of a second radio frame to be sent to the second STA.

[0103] Optionally, if the first radio frame includes second indication information, the second AP determines to participate in the cooperative multi-AP transmission initiated by the first AP according to the second indication information.

[0104] Optionally, if the first wireless frame includes third instruction information, the second AP determines, according to the third instruction information, whether it needs to sense a channel between the second AP and the second STA before transmitting the second wireless frame. If the third instruction information indicates that it needs to sense the channel, the second AP determines whether to transmit the second wireless frame based on the channel status obtained by sensing, specifically, not transmit the second wireless frame if the channel is busy, and transmit the second wireless frame if not. If the third instruction information indicates that it does not need to sense the channel, after receiving the first wireless frame, the second AP directly transmits the second wireless frame to the second STA after a first time.

[0105] Optionally, if the first radio frame includes the fourth instruction information, the second AP determines the transmission power information of the second AP according to the fourth instruction information. The transmission power information may be the maximum transmission power or the transmission power configured by the first AP. Therefore, in this embodiment, when the second AP transmits the second radio frame, the transmission power used does not exceed the maximum transmission power, or the transmission power used is the transmission power configured by the first AP.

[0106] Optionally, if the first radio frame includes the fifth instruction information, the second AP obtains the transmission power information of the first AP according to the fifth instruction information, and then the second AP predicts an interference value of the first AP to the associated second STA based on the transmission power information of the first AP. In practical application, the following formula may be used for prediction: interference value of the first AP to the second STA = transmission power of the first AP - path loss value from the first AP to the second STA. It should be understood that in practical application, other methods may be used for prediction, which are not particularly limited herein.

[0107] Optionally, if the first radio frame includes the sixth instruction information, the second AP obtains information about the maximum acceptable interference threshold of the first AP according to the sixth instruction information and determines the power instruction information for each second STA based on the information about the maximum interference threshold, so that each second STA determines the maximum transmission power of the second STA according to the power instruction information. Specifically, the transmission power of each second STA is controlled so that the interference value of the second STA with the first AP is within the fourth value range. Therefore, in this embodiment, the transmission power used by the second STA when transmitting a BA in response to the second radio frame cannot exceed the maximum transmission power of the second STA. In one example, the second AP may determine the average value of the interference of each second STA with the first AP based on the information about the maximum interference threshold. For example, since the value of the information about the maximum acceptable interference threshold of the first AP is 5mw and the second AP is associated with five second STAs, the second AP may assume that the average value of the interference of each second STA to the first AP cannot be greater than 5mw / 5=1mv, and then the second AP can determine the maximum transmission power of the second STA based on the average value of the interference of each second STA to the first AP. Note that in the present application, in an optional method, the second AP may directly predict the maximum transmission power of the second STA and instruct the second STA to use the maximum transmission power. In another optional method, the second AP may provide the second STA with power instruction information, for example, the maximum value of the interference of the second STA to the first AP, so that the second STA determines the maximum transmission power of the second STA according to the power instruction information. Specifically, the second STA may directly obtain the maximum transmission power of the second STA using the power indication information transmitted by the second AP, or may further calculate the maximum transmission power of the second STA according to the power indication information.

[0108] Optionally, when the first radio frame includes seventh instruction information and eighth instruction information, the second AP determines an interference value of each first STA to the second AP based on the identifier information of the first STA in the seventh instruction information and the transmission power of the first STA in the eighth instruction information.

[0109] Optionally, if the first radio frame includes the ninth indication information, the second AP uses the ninth indication information to determine the length of a padding field for padding useless information. Specifically, the second AP may prepare data to be transmitted to the second STA within the length of the padding field. In another example, the first radio frame may further include a special AP ID field to indicate the start of the padding field. When the second AP detects the special AP ID field, the second AP may prepare data to be transmitted to the second STA within the time of the padding field.

[0110] Optionally, if the first radio frame includes the tenth indication information, the second AP uses resource scheduling information indicated by the tenth indication information to determine the channel resources used to transmit the second radio frame. The resource scheduling information may include, but is not limited to, one or more combinations of resource block (RU) allocation information of each second AP, identifier information of stations scheduled by the second AP (i.e., identifier information of the second STAs), MCSs used by each station, or spatial streams used by each station.

[0111] Optionally, if the first radio frame includes eleventh instruction information, the second AP uses the eleventh instruction information to determine whether to perform uplink transmission or downlink transmission. In this embodiment, the eleventh instruction information is used to instruct the second AP to perform downlink transmission, specifically to trigger the second AP to send a second radio frame to the second STA. The second radio frame can be a data frame or a control frame.

[0112] Optionally, if the first radio frame includes twelfth indication information, the second AP uses the twelfth indication information to determine whether synchronous transmission is required. In this embodiment, the twelfth indication information is used to indicate that synchronous transmission is required. Specifically, after receiving the first radio frame, each second AP transmits a second radio frame to the second STA after a preset time, thereby implementing synchronous transmission among multiple APs.

[0113] Optionally, when the first radio frame includes the thirteenth indication information, the second AP uses the twelfth indication information to determine whether aligned transmission is required. In this embodiment, the thirteenth indication information is used to indicate that aligned transmission is required.

[0114] Optionally, if the first radio frame includes the fourteenth instruction information, the second AP may use the fourteenth instruction information to determine a mode for cooperative multi-AP transmission. In this embodiment, the fourteenth instruction information is used to instruct the second AP to perform synchronous aligned transmission.

[0115] Optionally, if the 13th instruction information indicates that aligned transmission is not required or the 14th instruction information indicates asynchronous transmission and unaligned transmission, the first radio frame may further include 15th instruction information, and the second AP uses the 15th instruction information to add an ACK policy to the second radio frame, so that after receiving the second radio frame, the second STA does not immediately respond to the BA frame, but instead responds to the BA frame after receiving the BAR frame sent by the second AP.

[0116] Optionally, after receiving the first wireless frame transmitted by the first AP, the second AP further transmits a first acknowledgment frame to the first AP in response to the first wireless frame. Note that if there are multiple second APs, there will also be multiple corresponding first acknowledgment frames. Therefore, to achieve synchronously aligned transmission of the multiple first acknowledgment frames, the first wireless frame may further include a transmission time of the first acknowledgment frame, so that after receiving the first wireless frame, the multiple second APs transmit the first acknowledgment frames to the first AP at the same time.

[0117] 205. The second AP transmits a second wireless frame to the second STA.

[0118] In this embodiment, after receiving the first radio frame, the second AP transmits a second radio frame to the second STA after a first time.

[0119] For how the second AP transmits the second radio frame to the second STA based on the respective indication information included in the first radio frame, please refer to the description of step 204. The details will not be described again here.

[0120] 206. The first AP transmits a third wireless frame to the first STA.

[0121] After transmitting the first wireless frame to the second AP, the first AP transmits a third wireless frame to a first STA associated with the first AP during the transmission period of the second wireless frame. In addition, to align the transmission of downlink frames by multiple APs, the transmission time of the third wireless frame is equal to the transmission time of the second wireless frame. In this embodiment, to synchronize the transmission of downlink frames by multiple APs, after transmitting the first wireless frame, the first AP also transmits a third wireless frame to the first STA a first time later. In other words, to synchronize the second wireless frame and the third wireless frame, the transmission time of the third wireless frame is the same as the transmission time of the second wireless frame.

[0122] Optionally, the third radio frame may also include an ACK policy, so that after receiving the second radio frame, the first STA does not immediately respond to the third acknowledgment frame, which may be understood as a BA, but instead responds to the third acknowledgment frame after receiving the BAR frame sent by the first AP.

[0123] It should be noted that in this embodiment, this step is optional. Specifically, the first AP does not transmit the third wireless frame to the first STA, but simply triggers the second APs to transmit the second wireless frame, thereby implementing synchronous aligned transmission of the second APs.

[0124] For ease of understanding, the two cases are described separately below based on the figures.

[0125] 1. The first AP transmits a third wireless frame to the first STA.

[0126] 2d is a schematic diagram of synchronous transmission according to this embodiment. In FIG. 2d, after transmitting a first radio frame (i.e., a SYNC frame) to a second AP, the first AP transmits a third radio frame (i.e., Data1) to a first STA after Tms. Optionally, the first AP then receives a third acknowledgment frame (i.e., BA1) sent by the first STA and used to respond to the third radio frame. After receiving the SYNC frame, the second AP transmits a second radio frame (i.e., Data2) to the second STA after Tms and receives a second acknowledgment frame (i.e., BA2) sent by the second STA and used to respond to the second radio frame. It can be understood that since Data1 and Data2 have the same transmission start time and the same transmission duration, Data1 and Data2 also have the same transmission end time, thereby implementing synchronous aligned transmission of multiple APs.

[0127] 2. The first AP does not transmit the third wireless frame to the first STA.

[0128] 2e is another schematic diagram of synchronous transmission according to this embodiment. In FIG. 2e, after transmitting a first radio frame (i.e., a SYNC frame) to a second AP, the first AP does not transmit any radio frames. After receiving the SYNC frame, the second AP (1) transmits a second radio frame (i.e., Data1) to a second STA (1) after T ms and receives a second acknowledgement frame (i.e., BA1) transmitted by the second STA (1). After receiving the SYNC frame, the second AP (2) also transmits Data2 to a second STA (2) after T ms and receives BA2 transmitted by the second STA (2). It can be seen that since Data1 and Data2 have the same transmission start time and the same transmission duration, Data1 and Data2 also have the same transmission end time, thereby achieving synchronous aligned transmission among multiple APs.

[0129] 207. The second STA sends a second acknowledgment frame to the second AP.

[0130] After receiving the second radio frame transmitted by the second AP, the second STA transmits a second acknowledgment frame to the second AP in response to the second radio frame.

[0131] Optionally, if the second radio frame includes power indication information of the second STA, the second STA determines the maximum transmission power of the second STA according to the power indication information, and the transmission power used when the second STA transmits the second acknowledgment frame cannot be greater than the maximum transmission power.

[0132] Optionally, if the second wireless frame includes an ACK policy, the second STA transmits a second acknowledgment frame to the second AP only after receiving the BAR frame transmitted by the second AP.

[0133] It should be noted that in practical application, this step is optional, specifically, the second STA may not send a second acknowledgment frame after receiving the second radio frame.

[0134] 208. The first STA sends a third acknowledgment frame to the first AP.

[0135] Optionally, after receiving the third radio frame transmitted by the first AP, the first STA transmits a third acknowledgment frame to the first AP in response to the third radio frame.

[0136] Optionally, if the third wireless frame includes an ACK policy, the first STA transmits a third acknowledgment frame to the first AP only after receiving the BAR frame transmitted by the first AP.

[0137] It should be noted that in this embodiment, in addition to implementing synchronously aligned transmission of downlink radio frames, synchronously aligned transmission of uplink acknowledgement frames can also be implemented. For example, synchronously aligned transmission of the second acknowledgement frame and the third acknowledgement frame is implemented. In another example, when the first AP does not transmit the third radio frame, or when the first AP transmits the third radio frame but the first STA does not transmit the third acknowledgement frame, synchronously aligned transmission of multiple second acknowledgement frames is implemented. Details are as follows.

[0138] The first radio frame may further include a transmission time of the second acknowledgment frame. After obtaining the transmission time of the second acknowledgment frame, the second AP may use the second radio frame to indicate the transmission time of the second acknowledgment frame to the second STA. After receiving the second radio frame, the second STA transmits the second acknowledgment frame to the second AP after the second time. Note that, like the first time, the second time may also be preset or defined by the first AP. Therefore, the second time may be the same as or different from the first time. This is not particularly limited herein.

[0139] Optionally, when the first AP transmits the third wireless frame, the third wireless frame may include the transmission time of the third acknowledgment frame, so that after receiving the third wireless frame, the first STA transmits the third acknowledgment frame to the first AP after the second time. In addition, it should be noted that the transmission time of the third acknowledgment frame is equal to the transmission time of the second acknowledgment frame.

[0140] In conclusion, in this embodiment, synchronously aligned transmission of acknowledgement frames can be implemented, avoiding a case where one STA receives a data frame or control frame transmitted by the AP while another STA is transmitting an acknowledgement frame, thereby reducing interference between the STA and the AP.

[0141] It should be noted that in this embodiment of the present application, transmitting a radio frame once and receiving an acknowledgement frame in response to the radio frame can be referred to as one transmission. Additionally, in this embodiment, the first radio frame can trigger not only one synchronous alignment transmission but also multiple synchronous alignment transmissions. Figures 2f-1 and 2f-2 are schematic diagrams of an example of transmission according to this embodiment. Multiple synchronous alignment transmissions are performed using the first radio frame. The time occupied by each transmission is referred to as a time segment (TS), and the first radio frame can include instruction information for each time segment. It should be understood that the instruction information for each time segment can include a combination of the first instruction information and one or more of the second to sixteenth instruction information. In one example, the instruction information for each time segment can be different. For example, the transmission time of Data11 in time segment 1 is different from the transmission time of Data21 in time segment 2. Alternatively, the instruction information for each time segment can be the same. For example, the first radio frame may include period indication information, so that multiple APs perform synchronous aligned transmission using the same indication information for each time segment.

[0142] In this embodiment of the present application, multiple APs coordinate scheduled transmission procedures and signaling to implement coordinated multi-AP parallel synchronous downlink transmission, thereby reducing interference and increasing throughput.

[0143] Downlink synchronous transmission is described above in Figure 2a. Referring to Figure 3a, a method embodiment for multi-AP cooperation using Method B for implementing uplink synchronous aligned transmission in the present application is described. For ease of understanding, this embodiment may be briefly described with reference to the system framework diagram shown in Figure 1b. The method may include:

[0144] AP1 transmits control information to AP2. After receiving the control information, AP2 transmits trigger information to STA2 after time A. After receiving the trigger information, STA2 transmits data to AP2 after time B. Note that if AP2 includes multiple APs, there may be multiple associated STA2s. The time from each AP2 receiving the control information to transmitting the trigger information is time A, and the trigger information transmitted by AP2 also has the same transmission time. Therefore, each STA2 also receives the trigger information simultaneously. In addition, the time from each STA2 receiving the trigger information to transmitting the data is time B, and the data transmitted by STA2 also has the same transmission time. Therefore, each STA2 also finishes transmitting data simultaneously. Therefore, multiple STA2 start transmitting data simultaneously and finish transmitting data simultaneously to achieve synchronous transmission of multiple STAs during uplink transmission. Alternatively, STA1 may receive trigger information from AP1 to synchronize with multiple AP2s.

[0145] A description is provided below based on specific steps.

[0146] 301. The first AP accesses the channel.

[0147] 302. The first AP determines the second AP.

[0148] In this embodiment, step 301 and step 302 are the same as step 201 and step 202 shown in Fig. 2a, and the details will not be described again here.

[0149] 303. The first AP generates a first radio frame.

[0150] In this embodiment, to perform synchronous transmission of uplink data, the first AP generates a first radio frame. After receiving the first radio frame, the second AP transmits a second radio frame to the second STA a first time later. The second radio frame triggers the second STA to transmit a third radio frame a second time later after receiving the second radio frame. In this embodiment, the second radio frame may be a trigger frame, and the third radio frame may be a data frame transmitted by the second STA. Note that the first and second times may both be preset or defined by the first AP. If the first and second times are defined by the first AP, the first radio frame may further include information indicating the first and second times. Therefore, the second time may be the same as or different from the first time. This is not particularly limited herein.

[0151] In order to coordinate the uplink synchronously aligned transmissions of multiple APs, the first radio frame includes at least first indication information and sixteenth indication information, where the first indication information is used to indicate the transmission time of the second radio frame, and the first indication information is similar to the first indication information included in the first radio frame of FIG. 2a. Details will not be described again here. In addition, the sixteenth indication information is used to indicate the transmission time of the third radio frame transmitted by the second STA. It should be understood that the second radio frame transmitted by the second AP to the second STA may also include the transmission time of the third radio frame to indicate the transmission time of the third radio frame to the second STA.

[0152] Similar to the first radio frame generated in step 203 shown in FIG. 2a, in this embodiment, the first radio frame generated using step 303 may also include, but is not limited to, one or more combinations of the indication information shown in Table 2.

[0153] [Table 2]

[0154] The second to eighth indication information are similar to the second to eighth indication information included in the first radio frame in Fig. 2a, and will not be described in detail again here.

[0155] The 11th instruction information is used to instruct the second AP to perform uplink transmission, specifically, the second STA needs to be triggered to transmit a third radio frame to the second AP.

[0156] The twelfth to fourteenth indications are similar to the twelfth to fourteenth indications included in the first radio frame in Fig. 2a, and will not be described in detail again here.

[0157] When the first AP decides to perform asynchronous transmission and unaligned transmission, the 15th instruction information is used to indicate the ACK policy, specifically, the second AP does not immediately respond to the acknowledgment frame after receiving the third radio frame, but responds to the acknowledgment frame after receiving the BAR frame sent by the second STA.

[0158] It should be noted that in this embodiment, the first AP accesses a channel using step 301, determines the second AP using steps 302 and 303, and generates a first wireless frame. These steps are not limited to a specific order in the two processes, and step 301 may be performed first, or steps 302 and 303 may be performed first, or these steps may be performed simultaneously. This is not particularly limited here.

[0159] 304. The second AP receives the first wireless frame transmitted by the first AP.

[0160] In this embodiment, step 304 is similar to step 204 in the embodiment shown in Figure 2a, and the details will not be described again here.

[0161] 305. The second AP transmits a second wireless frame to the second STA.

[0162] In this embodiment, step 305 is similar to step 205 in the embodiment shown in Figure 2a, and the details will not be described again here.

[0163] In this embodiment, the second radio frame is used to trigger the second STA to send the third radio frame to the second AP, and the second radio frame may include the transmission time of the third radio frame. In the embodiment shown in Figure 2a, the second STA may be a data frame transmitted by the second AP to the second STA.

[0164] 306. The second STA transmits a third wireless frame to the second AP.

[0165] After receiving the second radio frame transmitted by the second AP, the second STA transmits a third radio frame to the second AP after a second time period, which may be a single interval (SIFS).

[0166] Optionally, if the second radio frame includes power indication information of the second STA, the second STA determines a maximum transmission power of the second STA according to the power indication information, and the power used when the second STA transmits the third radio frame cannot be greater than the maximum transmission power.

[0167] 307. The second AP sends a third acknowledgment frame to the second STA.

[0168] After receiving the third radio frame transmitted by the second STA, the second AP transmits a third acknowledgment frame to the second STA in response to the third radio frame.

[0169] Optionally, if the first wireless frame includes an ACK policy, the second AP sends a third acknowledgment frame to the second STA only after receiving the BAR frame sent by the second STA.

[0170] Optionally, when the first radio frame includes fifth instruction information for indicating transmission power information of the second AP, the transmission power information may be a maximum transmission power or a transmission power configured by the first AP, and when the second AP transmits the third receipt confirmation frame, the power used cannot exceed the maximum transmission power of the second AP, or the power used is the transmission power configured by the first AP.

[0171] It should be noted that this step is optional. Specifically, in practical application, after receiving the third wireless frame transmitted by the second STA, the second AP may not transmit a third acknowledgment frame to the second STA in response to the third wireless frame.

[0172] 308. The first AP transmits a fourth wireless frame to the first STA.

[0173] After transmitting the first radio frame to the second AP, the first AP transmits a fourth radio frame to a first STA associated with the first AP during the transmission period of the second radio frame. The fourth radio frame is used to trigger the first STA to transmit a fifth radio frame to the first AP a second time after receiving the fourth radio frame, and the fourth radio frame must include the transmission time of the fifth radio frame. In addition, to align the transmission of uplink frames by multiple STAs, the transmission time of the fourth radio frame is equal to the transmission time of the second radio frame, and the transmission time of the fifth radio frame is equal to the transmission time of the third radio frame.

[0174] In this embodiment, in order to synchronize the fourth radio frame with the second radio frame, the first AP transmits the fourth radio frame to the first STA during the transmission period of the second radio frame; specifically, after transmitting the first radio frame, the first AP also transmits the fourth radio frame to the first STA after a first time, so please note that the transmission time of the fourth radio frame is the same as the transmission time of the second radio frame.

[0175] Note that this step is similar to step 206 shown in Figure 2a, and the details will not be described again here.

[0176] For ease of understanding, the two cases are described separately below based on the figures.

[0177] 1. The first AP transmits a fourth radio frame to the first STA.

[0178] 3b is another schematic diagram of synchronously aligned transmission according to this embodiment. In FIG. 3b, after transmitting a first radio frame (i.e., a SYNC frame) to a second AP, the first AP transmits a fourth radio frame (i.e., a Trigger 1 frame) to a first STA after T ms and receives a fifth radio frame (i.e., a Data 1 frame) transmitted by the first STA after P ms. After receiving the SYNC frame, the second AP transmits a second radio frame (i.e., a Trigger 2 frame) to the second STA after T ms and receives a third radio frame (i.e., a Data 2 frame) transmitted by the second STA after P ms. It can be seen that since Data 1 and Data 2 have the same transmission start time and the same transmission duration, Data 1 and Data 2 also have the same transmission end time, thereby achieving synchronous transmission of uplink data.

[0179] 2. The first AP does not transmit the fourth wireless frame to the first STA.

[0180] 3c is another example of a schematic diagram of synchronous aligned transmission according to this embodiment. In FIG. 3c, after transmitting a first wireless frame (i.e., a SYNC frame) to a second AP, the first AP does not transmit any wireless frames. After receiving the SYNC frame, the second AP (1) transmits a second wireless frame (i.e., Trigger 1) to a second STA (1) after T ms and receives a third wireless frame (i.e., Data 1) transmitted by the second STA (1) after P ms. After receiving the SYNC frame, the second AP (2) also transmits a Trigger 2 to a second STA (2) after T ms and receives Data 1 transmitted by the second STA (2) after P ms. Since Data 1 and Data 2 have the same transmission start time and the same transmission duration, Data 1 and Data 2 also have the same transmission end time, thereby achieving synchronous aligned transmission of uplink data.

[0181] 309. The first STA transmits a fifth wireless frame to the first AP.

[0182] Optionally, after receiving the fourth radio frame transmitted by the first AP, the first STA transmits a fifth radio frame to the second AP after a second time.

[0183] 310. The first AP sends a fifth acknowledgment frame to the first STA.

[0184] Optionally, after receiving the fifth radio frame transmitted by the first STA, the first AP may transmit a fifth acknowledgment frame to the first STA in response to the fifth radio frame.

[0185] Optionally, the first AP may set an ACK policy so that the first AP sends a fifth acknowledgment frame to the first STA only after receiving the BAR frame sent by the first STA.

[0186] It should be noted that in this embodiment, in addition to implementing synchronously aligned transmission of uplink radio frames, synchronously aligned transmission of downlink acknowledgement frames can also be implemented, specifically, synchronously aligned transmission of the third acknowledgement frame and the fifth acknowledgement frame or synchronously aligned transmission of multiple third acknowledgement frames is implemented. Details are as follows:

[0187] The first radio frame may further include a fifteenth indication, which is used to indicate a transmission time of the third acknowledgment frame, so that after receiving the third radio frame, the second AP transmits the third acknowledgment frame to the second STA after a third time. Note that the third time may be a preset time or may be defined by the first AP. If the third time is defined by the first AP, the first radio frame may further include an indication of the third time.

[0188] Optionally, after receiving the fifth radio frame, the first AP also sends a fifth acknowledgment frame to the first STA after a third time. In addition, it should be noted that the transmission time of the fifth acknowledgment frame is equal to the transmission time of the third acknowledgment frame.

[0189] In conclusion, in this embodiment, synchronous aligned transmission of acknowledgement frames of the first AP and the second AP can be implemented, and a case where one AP receives a data frame transmitted by a STA while another AP transmits an acknowledgement frame can be avoided, thereby reducing interference between the AP and the STA.

[0190] Similar to the first radio frame in the embodiment shown in Fig. 2a, the first radio frame in this embodiment may also trigger multiple synchronous transmissions, and the triggering method is similar to that of the first radio frame in the embodiment shown in Fig. 2a, and the details will not be described again here.

[0191] In this embodiment of the present application, multiple APs coordinate scheduled transmission procedures and signaling to implement synchronous transmission of uplink data, thereby reducing interference and increasing throughput.

[0192] The above Fig. 2a and Fig. 3a have described synchronous aligned transmission. Referring to Fig. 4a, a method embodiment for multi-AP cooperation using Method C for implementing downlink aligned transmission of the present application is described. For ease of understanding, this embodiment can be briefly described with reference to the system framework diagram shown in Fig. 1b. The method includes:

[0193] AP1 sends control information to AP2. After receiving the control information, AP2 transmits data to STA2 and ends the data transmission at time C. Note that if AP2 includes multiple APs, the time at which AP2 ends data transmission to its associated STA2 is also time C. Specifically, multiple APs may simultaneously end data transmission to achieve aligned transmission of multiple APs during downlink transmission. AP1 may also be aligned with AP2.

[0194] A description is provided below based on specific steps.

[0195] 401. The first AP accesses the channel.

[0196] 402. The first AP determines the second AP.

[0197] In this embodiment, step 401 and step 402 are the same as step 201 and step 202 shown in Fig. 2a, and the details will not be described again here.

[0198] 403. A first AP generates a first radio frame.

[0199] The first AP generates a first radio frame, which is used to trigger a second AP to transmit a second radio frame to a second STA associated with the second AP to perform cooperative multi-AP scheduling. Note that, in order to align multiple APs during downlink transmission, the first radio frame includes at least first indication information, which is used by the second AP to determine the transmission end time of the second radio frame.

[0200] It should be noted that if the radio frame transmitted by the first AP is different, the first radio frame may also include different first indication information, which will be described separately below.

[0201] Scenario 1: A first AP transmits a first wireless frame to a second AP and a first STA.

[0202] For ease of understanding, FIG. 4b is an example of a schematic diagram of downlink ordered transmission based on Scenario 1 according to this embodiment. In the figure, a first AP transmits a first radio frame, i.e., Data1 in the figure, to a first STA. Data1 carries first instruction information, which can be used to indicate the transmission time or transmission end time of Data1. Therefore, the second AP obtains the first instruction information from Data1 to determine the transmission end time of Data1, and transmits a second radio frame, i.e., Data2 in the figure, to the second STA, so that the transmission end time of Data2 is the same as the transmission end time of Data1, so as to order the downlink data transmission. Optionally, after receiving Data1 transmitted by the first AP, the first STA transmits BA frame 1 to the first AP. After receiving Data2 transmitted by the second AP, the second STA transmits BA frame 2 to the first AP.

[0203] Therefore, in this scenario, since the first instruction information is used to indicate the transmission time of the first radio frame or the transmission end time of the first radio frame, the second AP determines the transmission end time of the second radio frame according to the first instruction information, and the transmission end time of the second radio frame is the same as the transmission end time of the first radio frame.

[0204] Scenario 2: A first AP transmits a first wireless frame to a second AP, which then transmits a third wireless frame to an associated first STA.

[0205] For ease of understanding, FIG. 4c is a schematic diagram of an example of downlink aligned transmission based on Scenario 2 according to this embodiment. In the figure, the first AP transmits a first radio frame, i.e., a SYNC frame in the figure, to the second AP and a third radio frame, i.e., Data1 in the figure, to the first STA. The SYNC frame carries first instruction information, which can be used to indicate the transmission time or the end time of Data1. Therefore, the second AP determines the end time of Data1 transmission according to the first instruction information and transmits a second radio frame, i.e., Data2 in the figure, to the second STA. The end time of Data2 transmission is the same as the end time of Data1 transmission, so that the downlink data transmissions are aligned. Optionally, after receiving Data1 transmitted by the first AP, the first STA transmits BA frame 1 to the first AP. After receiving Data2 transmitted by the second AP, the second STA transmits BA frame 2 to the first AP.

[0206] Therefore, in this scenario, since the first instruction information is used to indicate the transmission time of the third radio frame or the transmission end time of the third radio frame, the second AP determines the transmission end time of the second radio frame according to the first instruction information, and the transmission end time of the second radio frame is the same as the transmission end time of the third radio frame.

[0207] Scenario 3: A first AP transmits a first wireless frame to a second AP.

[0208] For ease of understanding, FIG. 4d is an example of a schematic diagram of downlink aligned transmission based on Scenario 3 according to this embodiment. In the figure, a first AP transmits a first radio frame, i.e., a SYNC frame, to multiple second APs to trigger them to transmit second radio frames, i.e., data shown in the figure. For example, the first radio frame transmits a first instruction information to the second APs, which may be used to indicate the end time of the transmission of the data transmitted by each second AP. Note that, to align the downlink data transmission, the data transmitted by the second APs have the same end time of transmission. Optionally, after receiving Data1 transmitted by the second AP(1), the second STA(1) transmits BA frame 1 to the second AP(1). After receiving Data2 transmitted by the second AP(2), the second STA(2) transmits BA frame 2 to the second AP(2).

[0209] Therefore, in this scenario, since the first instruction information is used to indicate the transmission end time of the second radio frame, multiple second APs determine the transmission end time of each second radio frame according to the first instruction information, and each second radio frame has the same transmission end time.

[0210] Similar to the first radio frame generated in step 203 shown in FIG. 2a, in this embodiment, the first radio frame generated using step 403 may also include, but is not limited to, one or more combinations of the indication information shown in Table 3.

[0211] [Table 3]

[0212] The second to eleventh indications and the fifteenth indication are similar to the second to eleventh indications and the fifteenth indications included in the first radio frame in Fig. 2a, and will not be described in detail again here.

[0213] The 12th indication information is used to indicate that the second AP does not need to perform synchronous transmission, specifically, that multiple APs may independently determine the transmission start time, provided that the same transmission end time can be guaranteed.

[0214] The thirteenth indication information is used to indicate that ordered transmission is required, specifically, that multiple APs must have the same transmission end time.

[0215] The fourteenth indication information is used to indicate that synchronous transmission is not required and that synchronization and alignment are required.

[0216] It should be noted that in this embodiment, the first AP accesses a channel using step 401, determines the second AP using steps 402 and 403, and generates a first wireless frame. These steps are not limited to a specific order in the two processes, and step 401 may be performed first, or steps 402 and 403 may be performed first, or these steps may be performed simultaneously. This is not particularly limited here.

[0217] 404. The second AP receives the first wireless frame transmitted by the first AP.

[0218] In scenario 1 described in step 403 of this embodiment, the first instruction information in the first radio frame is used to indicate the transmission time or the transmission end time of the first radio frame. When the first instruction information is used to indicate the transmission time of the first radio frame, the second AP determines the transmission end time of the first radio frame based on the transmission start time and the transmission time of the first radio frame, and determines the transmission end time of the first radio frame as the transmission end time of the second radio frame to be transmitted to the second STA. When the first instruction information is used to indicate the transmission end time of the first radio frame, the second AP directly uses the transmission end time of the first radio frame as the transmission end time of the second radio frame to be transmitted to the second STA.

[0219] It should be noted that in order to help the second AP quickly detect the indication information in the first radio frame, the indication information may be carried in a physical layer preamble in the physical layer protocol data unit in which the first radio frame is located.

[0220] In scenario 2 described in step 403 of this embodiment, the first instruction information is used to indicate the transmission time or the transmission end time of the third radio frame. The method by which the second AP determines the transmission end time of the second radio frame according to the first instruction information is similar to the method by which the second AP determines the transmission end time of the second radio frame in scenario 1. Details will not be described again here.

[0221] In scenario 3 described in step 403 of this embodiment, the first instruction information is used to indicate the transmission end time of the second wireless frame, and the second AP directly obtains the transmission end time of the second wireless frame according to the first instruction information.

[0222] Optionally, if the first radio frame further includes, but is not limited to, one or more combinations of the second to fifteenth indication information in Table 3, the method of the second AP receiving and processing the first radio frame is similar to the method of step 204 shown in Figure 2a. Details will not be described again here.

[0223] Optionally, in this embodiment, after receiving the first wireless frame transmitted by the first AP, the second AP further transmits a first acknowledgment frame to the first AP in response to the first wireless frame. In addition, if there are multiple second APs, there will also be multiple corresponding first acknowledgment frames. Therefore, to achieve aligned transmission of the multiple first acknowledgment frames, the first wireless frame may further include a transmission end time of the first acknowledgment frame, so that after receiving the first wireless frame, the multiple second APs transmit multiple first acknowledgment frames to the first AP with the same transmission end time.

[0224] 405. The second AP transmits a second wireless frame to the second STA.

[0225] In this embodiment, step 405 is similar to step 205 in Fig. 2a, and the details will not be described again here.

[0226] It should be noted that in this embodiment, the second AP determines the transmission end time of the second radio frame to be transmitted. In step 205 shown in Figure 2a, the second AP further determines the transmission start time of the second radio frame.

[0227] 406. The first AP transmits a fourth wireless frame to the first STA.

[0228] This step is an optional step, as described in scenario 1 to scenario 3 of step 403. This step will be described separately based on the three scenarios.

[0229] Scenario 1: A first AP transmits a first radio frame to a first STA, in other words, the fourth radio frame is the first radio frame.

[0230] After generating the first radio frame, the first AP transmits the first radio frame to the associated first STA, and the first radio frame also needs to be transmitted to the second AP to instruct the second AP to align its downlink transmission. The transmission end time of the first radio frame is the same as the transmission end time of the second radio frame.

[0231] Optionally, the indication information in the first radio frame may be carried in a physical layer preamble of the first radio frame.

[0232] Scenario 2: The first AP transmits the third radio frame to the first STA, in other words, the fourth radio frame is the third radio frame.

[0233] After transmitting the first wireless frame to the second AP, the first AP transmits a third wireless frame to the associated first STA, and the first indication information in the first wireless frame is used to indicate the transmission time or transmission end time of the third wireless frame, so that the transmission end time of the second wireless frame transmitted by the second AP is the same as the transmission end time of the third wireless frame.

[0234] Scenario 3: The first AP does not transmit wireless frames to the first STA.

[0235] In this scenario, the first AP does not transmit a radio frame to the first STA, but simply triggers multiple second APs to transmit second radio frames to perform aligned transmission of multiple second radio frames.

[0236] 407. The second STA sends a second acknowledgment frame to the second AP.

[0237] 408. The first STA sends a fourth acknowledgment frame to the first AP.

[0238] In this embodiment, step 407 and step 408 are the same as step 207 and step 408 shown in Fig. 2a, and the details will not be described again here.

[0239] It should be noted that in this embodiment, in addition to performing the aligned transmission of the downlink radio frames, the aligned transmission of the uplink acknowledgement frames can also be performed. For example, the aligned transmission of the second acknowledgement frame and the fourth acknowledgement frame is performed, or the aligned transmission of multiple second acknowledgement frames is performed. Details are as follows.

[0240] The first radio frame may further include a transmission end time of the second acknowledgment frame, so that after obtaining the transmission end time of the second acknowledgment frame, the second AP may use the second radio frame to indicate the transmission end time of the second acknowledgment frame to the second STA, and after receiving the second radio frame, the second STA transmits the second acknowledgment frame to the second AP. In addition, the transmission end time of the second acknowledgment frame is indicated by the first radio frame.

[0241] Optionally, after the first AP transmits a fourth radio frame to the first STA, the fourth radio frame may include a transmission end time of the fourth acknowledgment frame, which is the same as the transmission end time of the second acknowledgment frame.

[0242] In conclusion, in this embodiment, aligned transmission of acknowledgement frames can be implemented, and cases where one STA receives a data frame or control frame while another STA is transmitting an acknowledgement frame can be avoided, thereby reducing interference between STAs and interference between APs.

[0243] Similar to the first radio frame in the embodiment shown in Fig. 2a, the first radio frame in this embodiment may also trigger multiple aligned transmissions, and the triggering method is similar to that of the first radio frame in the embodiment shown in Fig. 2a, and the details will not be described again here.

[0244] In this embodiment of the present application, multiple APs coordinate scheduled transmission procedures and signaling to implement coordinated multi-AP parallel ordered downlink transmission, thereby reducing interference and increasing throughput.

[0245] It should be understood that for a given signal-to-interference ratio (SIR), if the transmitting end selects an MCS that is too high, packet loss will occur because the SIR at the receiving end cannot reach the SIR required for the high MCS. If the transmitting end selects an MCS that is too low, the probability of packet loss is very low, but the low MCS results in a relatively low data transmission rate and the channel cannot be fully utilized. Therefore, to support cooperative scheduling among multiple APs, each AP needs to know how high the SIR that the STAs associated with the AP can achieve when multiple APs transmit in parallel, so that the AP can select an appropriate MCS when scheduling STAs for transmission.

[0246] Therefore, one embodiment of the present application provides a channel information prediction method used to predict the SIR of a station during cooperative multi-AP scheduling to allocate an appropriate MCS, thereby achieving a balance between transmission rate and packet loss rate. For details, please refer to Figure 5a, which is an example of a flowchart of the information prediction method according to one embodiment of the present application. The method includes the following steps:

[0247] 501. A first AP transmits a broadcast frame.

[0248] The first AP transmits a broadcast frame to all STAs associated with the first AP. The broadcast frame is used to indicate to the STAs associated with the first AP the second AP for which signal quality detection should be performed, and the broadcast frame carries identifier information of the second AP. Note that the second AP may include at least one AP, and the second AP may include the first AP.

[0249] In this embodiment, there may be several cases for the identifier information of the second AP. In one example, the identifier information of the second AP may be the MAC address of the second AP. In another example, the identifier information of the second AP may be a part of the MAC address of the second AP, or an address assigned to the second AP by the first AP, or an address determined by the second AP and instructed to the first AP. Therefore, the first AP adds an address to the broadcast frame. Alternatively, the identifier information of the second AP may be identifier information of a device (which may be a STA or an AP) having a binding relationship with the second AP. After receiving a frame transmitted by the first AP to the second AP, the device forwards the frame to the second AP through an internal interface between the device and the second AP. Therefore, the identifier information of the second AP is not particularly limited here.

[0250] For ease of description, in this embodiment, any one or more of the STAs associated with the first AP are referred to as the first STA. Therefore, the first AP sends a broadcast frame to the first STA to trigger the first STA to detect the channel between the second AP and the first STA.

[0251] In this embodiment, the broadcast frame may be an existing management frame such as a beacon frame or a probe request frame of the 802.11 standard, or may be a frame format defined by a non-standard vendor, etc. This is not particularly limited here.

[0252] It should be noted that in this embodiment, the second AP may also receive the broadcast frame transmitted by the first AP.

[0253] 502. The first STA receives a wireless frame transmitted by the target AP.

[0254] In this embodiment, the AP that can communicate with the first STA is called the target AP. It should be understood that the target AP is a part or all of the second AP. Therefore, the first STA receives the wireless frame transmitted by the target AP to detect the channel between the first STA and the target AP.

[0255] It should be noted that in this embodiment, the radio frame received by the first STA may be autonomously transmitted by the target AP, or may be transmitted by the target AP after being triggered by the first AP, which will be described separately below.

[0256] Example 1: A wireless frame is transmitted autonomously by the target AP.

[0257] In this example, the radio frame is a beacon frame transmitted by the target AP. The beacon frame may be used to measure path loss from the target AP to the beacon frame receiver (i.e., the first STA). The beacon frame may carry a measurement report of the target AP. The measurement report may include, but is not limited to, one or more types of information: the transmission power of the target AP and the signal reception level and power of devices surrounding the target AP.

[0258] Example 2: A radio frame is transmitted by the target AP after the target AP is triggered by the first AP.

[0259] In this example, the broadcast frame of step 501 may be further used to trigger the second AP to sequentially transmit null data packets (NDP), and the broadcast frame further includes order indication information, which is used to indicate the order in which the second AP transmits the NDP frames. Note that the broadcast frame may be an enhanced-null data packet announcement (E-NDPA) frame.

[0260] Therefore, after receiving the broadcast frame transmitted by the first AP, the second AP sequentially transmits NDP frames according to the order indication information in the broadcast frame. The inter-frame interval may be SIFS. Note that the inter-frame interval may be a default interval or may be defined by the first AP. If the inter-frame interval is defined by the first AP, the broadcast frame further carries the inter-frame interval indication information. For ease of understanding, FIG. 5b is an example of a schematic diagram of transmission according to this embodiment. In the figure, AP1 broadcasts an E-NDPA frame (which can be understood as a broadcast frame). Therefore, AP1 to AP3 sequentially transmit NDP frames in the order indicated by the E-NDPA frame. For example, AP1 first transmits NDP frame 1, then AP2 transmits NDP frame 2, and finally AP3 transmits NDP frame 3. Optionally, AP1 may further send a Trigger frame used to trigger the first STA to send a Feedback frame, so that after receiving the Trigger frame, the first STA will feed back corresponding Feedback frames 1 to 3 based on the received NDP frames 1 to 3.

[0261] Optionally, the broadcast frame may further include the identifier information of the STA whose channel needs to be detected, which may be a MAC address or an IP address.

[0262] Therefore, in the two above examples, the difference is that in example 1, the first STA receives a radio frame (such as a beacon frame) autonomously transmitted by the second AP and then detects the channel based on the received signal strength of the beacon frame, while in example 2, the first STA detects the channel based on the NDP frame received by the first AP, since each second AP transmits an NDP frame in the order instructed by the first AP.

[0263] 503. The first STA determines channel quality information of the target channel based on the radio frame.

[0264] When Example 2 of step 502 is used, specifically, when the wireless frame may be an NDP frame, it should be noted that the first STA further needs to determine the target AP based on the received NDP frame. This includes the steps of the first STA obtaining the order in which the second AP will transmit the NDP frames according to the second instruction information in the broadcast frame, and determining the target AP to transmit the wireless frame based on the ranking of the received wireless frame. For example, AP1 first transmits NDP1, then AP2 transmits NDP2, then AP3 transmits NDP3, and so on. Upon receiving the second NDP, i.e., NDP2, the first STA may determine that the target AP to transmit the second NDP is AP2, in accordance with the order in which the second AP transmits the NDP frames.

[0265] Therefore, after receiving the radio frame transmitted by the target AP, the first STA determines channel quality information of the target channel (i.e., the channel between the first STA and the target AP) based on the radio frame. Specifically, the first STA may obtain the received signal strength indication (RSSI) of the target AP or the transmit power of the target AP based on the measurement report of the target AP carried in the radio frame. Therefore, the channel quality information of the target channel determined by the first STA may be the RSSI of the target AP, or the transmit power of the target AP, or the path loss between the target AP and the first STA. Therefore, in this embodiment, the channel quality information of the target channel may include multiple types of content, which is not particularly limited herein.

[0266] Optionally, if the channel quality information is the propagation loss between the target AP and the first STA, the first STA further needs to calculate the channel quality information using the transmission power and RSSI of the target AP. path loss=TX power+Gr+Gt-RSSI, where TX power represents the transmission power of the target AP, Gr represents the receiving antenna gain, Gt represents the transmitting antenna gain, RSSI represents the signal receiving strength of the target AP, and Gr and Gt are preset values. It should be noted that in practical applications, there are multiple ways to calculate path loss, and these methods will not be described in detail one by one here.

[0267] 504. The first STA receives the trigger frame sent by the first AP.

[0268] Optionally, the first STA may further receive a trigger frame transmitted by the first AP. The trigger frame is used to trigger the first STA to transmit a feedback frame, and the trigger frame may include resource configuration indication information. The resource configuration indication information is used to indicate radio channel resources used by each first STA to respond with the feedback frame. The resource configuration information may include, but is not limited to, one or more combinations of the following information: RU allocation information of the first STA, spatial and time stream (STS) information, or orthogonal codes.

[0269] It should be noted that the trigger frame generated by the first AP may be designed based on the Trigger frame defined in the 802.11ax standard, as shown in Figures 5c to 5e. Figure 5c is an example of a diagram of the frame structure of the Trigger frame defined in the 802.11ax standard. The Trigger frame includes multiple sections, such as Frame Control, Common info, and User info. Figure 5d is a schematic diagram of information included in the Common info section of the Trigger frame shown in Figure 5c. Figure 5e is a schematic diagram of information included in the User Info section of the Trigger frame shown in Figure 5c. As shown in Figure 5c, when the value of the Trigger Type subfield is different in the Common info section of the Trigger frame, the Trigger frame has different functions. Table 4 is an example of a table of correspondence between the value and type of the Trigger Type subfield.

[0270] [Table 4]

[0271] In one example, the value of the Trigger Type subfield may be set to a specific value, for example, a value from 8 to 15. When the first AP sends a Trigger frame to the first STA, this indicates that the trigger frame is used to trigger the first STA to send a feedback frame.

[0272] It should be noted that the first STA determines the channel quality information of the target channel using steps 502 and 503, and receives the trigger frame transmitted by the first AP using step 504. These steps are not limited to a specific order in the two processes, and steps 502 and 503 may be performed first, or step 504 may be performed first, or these steps may be performed simultaneously. This is not particularly limited here.

[0273] 505. The first STA sends a feedback frame to the first AP.

[0274] In response to the trigger frame transmitted by the first AP, the first AP transmits a feedback frame to the first STA. The feedback frame includes channel quality information of the target channel, where the target channel is a channel between the first STA and the target AP. It should be understood that the feedback frame includes identifier information of the target AP to indicate the detected AP to the first AP. The identifier information of the target AP may be the MAC address of the target AP.

[0275] Optionally, in this embodiment, a short ID can be used as the identifier of the target AP to reduce the length of the feedback frame. The specific operation is as follows:

[0276] The broadcast frame of step 501 further includes fourth indication information, which is used to indicate the short ID of each second AP. Figure 5f is an example of a schematic diagram of a frame structure of a broadcast frame. In the figure, each AP info field includes a corresponding MAC Address and a Feedback ID (i.e., a short ID). Therefore, correspondingly, when the first STA sends a feedback frame to the first AP, the feedback frame carries a short ID for indicating the identifier information of the target AP. Figure 5g is an example of a schematic diagram of a frame structure of a feedback frame. In the figure, each AP Feedback info field includes a corresponding Feedback ID (i.e., a short ID) and channel quality information (such as RSSI).

[0277] Optionally, the feedback frame sent by the first STA may include multiple types of channel quality information, for example, the RSSI of the target AP and the transmit power information of the target AP. Figure 5h is an example of a schematic diagram of a frame structure of a feedback frame. In the figure, each AP Feedback info field includes a corresponding Feedback ID, TX power, RSSI, etc. Alternatively, the channel quality information may further directly include the path loss between the first STA and the target AP. The path loss value is obtained by the first STA through calculation using the transmit power and RSSI of the target AP. Figure 5i is another example of a schematic diagram of a frame structure of a feedback frame. In the figure, each AP Feedback info field includes a corresponding Feedback ID, path loss, etc.

[0278] Optionally, in Example 2, the first STA may receive NDP frames from the first AP and the second AP. Therefore, the first STA may calculate an interference to signal ratio (ISR) of the second AP based on the received power of the two NDP frames, and add the SIR or ISR of the second AP to the feedback frame.

[0279] Therefore, the content included in the feedback frame transmitted by the first STA to the first AP is not particularly limited in this embodiment.

[0280] 506. The first AP predicts the SIR of the first STA based on the channel quality information of the target channel.

[0281] After receiving the feedback frame sent by the first STA, the first AP predicts the SIR of the first STA based on the channel quality information of the target channel included in the feedback frame. The calculation formula for the SIR of the first STA may be SIR = (transmission power of the first AP - path loss between the first AP and the first STA) / (transmission power of the target AP - path loss between the target AP and the first STA). Therefore, the first AP may directly or indirectly obtain the path loss between the target AP and the first STA using the channel quality information of the target channel fed back by the first STA to calculate the SIR of the first STA.

[0282] Optionally, the first AP may further calculate the ISR of the first STA, where ISR×SIR=1.

[0283] Optionally, the present application may further provide an information prediction method, including the steps of each AP continuing to sense the channel, obtaining RSSI for each STA (including STAs in the local cell and STAs in another cell) based on the sensing result, and then transmitting information about the obtained RSSI to another AP. After obtaining information about the RSSI transmitted by another AP, each AP may calculate the SIR for each STA during parallel transmission and use the SIR as input for cooperative multi-AP scheduled transmission. For ease of understanding, for example, assume there are two APs, AP1 and AP2, where AP1 is associated with STA1 and AP2 is associated with STA2. In the transmission history, AP1 detects the signals of STA1 and STA2, and similarly, AP2 also detects the signals of STA1 and STA2. After AP1 transmits the signal strengths of STA1 and STA2 to AP2, if AP2 needs to obtain the SIR for STA2 during parallel transmission, the SIR can be obtained by dividing the signal strength of STA2 sensed by AP2 by the signal strength of STA2 transmitted by AP1.

[0284] It should be noted that the information prediction method shown in Fig. 5a may be applied to the scenario of the method for multi-AP cooperation in the embodiment of the present application, and may also be independently applied to another scenario in which information prediction needs to be performed before data transmission. Therefore, the actual application scenario of the information prediction method provided in Fig. 5a of the present application is not particularly limited here.

[0285] The method for multi-AP cooperation in the embodiment of the present application has been described above, and the apparatus for coordinated multi-access point AP transmission will be described in detail below from the perspective of hardware processing.

[0286] 6 is a possible schematic structural diagram of an apparatus 600 for coordinated multi-access point AP transmission in the aforementioned embodiment. The apparatus 600 may be configured as the aforementioned first access point AP, and may include a processor 602, a computer-readable storage medium / memory 603, a transceiver 604, an input device 605, an output device 606, and a bus 601. The processor, the transceiver, the computer-readable storage medium, etc. are connected using a bus. The specific connection medium between the aforementioned components is not limited in this embodiment of the present application.

[0287] The transceiver 604 may be configured to assist the first AP in communicating with the second access point AP of the aforementioned embodiment and further assist the first AP in communicating with one or more first STAs associated with the first access point AP of the aforementioned embodiment, and may perform the transmission and reception processes in the first AP of Figures 2a to 5i and / or other processes used in the techniques described herein. For example, the transceiver 604 may be configured to transmit at least one first radio frame to the second access point AP, where the first radio frame includes indication information used to indicate a transmission time of a second radio frame transmitted by the second AP, and transmit a third radio frame to the first STA during the transmission period of the second radio frame, where the transmission time of the third radio frame is the same as the transmission time of the second radio frame. The transceiver 604 may further perform step 208 of Figure 2a, step 306 and step 310 of Figure 3a, step 408 of Figure 4a, and step 501, step 504, and step 505 of Figure 5a. Of course, the transceiver 604 may be further configured to perform other processes and methods in the techniques described in this application.

[0288] The processor 602 is configured to control and manage the operation of the first AP, to perform the processing performed by the first AP in the above-described embodiment, to perform the processing processes of the first AP in Figures 2a to 5i and / or other processes used in the techniques described herein, to manage the bus, and to execute programs or instructions stored in memory. For example, the processor 602 may perform steps 201 to 203 in Figure 2a, steps 301 to 303 in Figure 3a, steps 401 to 403 in Figure 4a, and step 506 in Figure 5a.

[0289] The computer-readable storage medium / memory 603 stores programs, instructions, or data for implementing the technical solutions of the present application. For example, the computer-readable storage medium / memory 603 may include instructions for causing the device 600 to transmit a first radio frame to one or more second APs, may further include instructions for causing the device 600 to transmit a third radio frame to the first station STA during the transmission period of the second radio frame, and may further include instructions for causing the device 600 to perform the transmitting process, receiving process, and processing process of the first AP in Figures 2a to 5i and / or another process used in the technology described in the present application.

[0290] It should be understood that Figure 6 shows a simplified design of the first AP. In practical application, the first AP may include any number of transceivers, processors, memories, etc., and all first APs that can implement the present application fall within the protection scope of the present application.

[0291] 7 is a possible schematic structural diagram of an apparatus 700 for coordinated multi-access point AP transmission in the aforementioned embodiment. The apparatus 700 may be configured as the aforementioned second AP, and includes a processor 702, a computer-readable storage medium / memory 703, a transceiver 704, an input device 705, an output device 706, and a bus 701. The processor, the transceiver, the computer-readable storage medium, etc. are connected using a bus. The specific connection medium between the aforementioned components is not limited in this embodiment of the present application.

[0292] The transceiver 704 may be configured to assist the second AP in communicating with the first AP and further assist the second AP in communicating with one or more second STAs associated with the second access point AP of the aforementioned embodiment, and may perform the communication or interaction process of the second AP in FIGS. 2a to 4d and / or another process used in the techniques described herein. For example, the transceiver 704 may be configured to receive at least one first radio frame transmitted by the first AP and further configured to transmit a second radio frame to the second STA after receiving the first radio frame. The transceiver 704 may further be configured to perform steps 204, 205, and 207 of FIG. 2a, steps 304 to 307 of FIG. 3a, and steps 404, 405, and 407 of FIG. 4a. Of course, the transceiver 704 may further be configured to perform other processes and methods in the techniques described herein.

[0293] The processor 702 is configured to control and manage the operation of the second AP, to perform the processing performed by the second AP in the above-described embodiments, to perform the processing processes of the second AP in FIGS. 2a to 4d and / or other processes used in the techniques described in this application, to be responsible for managing the bus, and to execute programs or instructions stored in memory.

[0294] The computer-readable storage medium / memory 703 stores programs, instructions, and data for implementing the technical solutions of the present application. For example, the computer-readable storage medium / memory 703 may include instructions for causing the device 700 to receive a first wireless frame transmitted by a first AP, may further include instructions for causing the device 700 to transmit a second wireless frame to a second STA after receiving the first wireless frame, and may further include instructions for causing the device 700 to perform the transmitting process, receiving process, and processing process of the second AP in Figures 2a to 4d and / or another process used in the technology described in the present application.

[0295] It should be understood that Figure 7 shows a simplified design of the second AP. In practical application, the second AP may include any number of transceivers, processors, memories, etc., and all second APs that can implement the present application fall within the protection scope of the present application.

[0296] The processor in device 600 and device 700 may be a general-purpose processor, such as a general-purpose central processing unit (CPU), network processor (NP), or microprocessor, or may be an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to control program execution of the solutions of the present application. The processor may alternatively be a digital signal processor (DSP), a field-programmable gate array (FPGA), another programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. Alternatively, the controller / processor may be a combination of processors that perform computational functions, such as a combination of one or more microprocessors or a combination of a DSP and a microprocessor. A processor typically performs logical and arithmetic operations based on program instructions stored in memory.

[0297] The computer-readable storage medium / memory 603 and the computer-readable storage medium / memory 703 may further store an operating system and other application programs. Specifically, the programs may include program code, which includes computer operating instructions. More specifically, the memory may be read-only memory (ROM), another type of static storage device capable of storing static information and instructions, random access memory (RAM), another type of dynamic storage device capable of storing information and instructions, magnetic disk memory, etc. The memory 603 may be a combination of the aforementioned storage types. In addition, the computer-readable storage medium / memory may be located on the processor, external to the processor, or distributed across multiple entities, including the processor or processing circuitry. The computer-readable storage medium / memory may be specifically embodied in a computer program product. For example, the computer program product may include a computer-readable medium in packaging materials.

[0298] Alternatively, device 600 and device 700 may be configured as a general-purpose processing system, commonly referred to as a chip, that includes one or more microprocessors that provide the processor functions and external memory that provides at least a portion of the storage medium, all of which are connected to other support circuitry via an external bus architecture. When executed by the processor, the instructions stored in the memory enable the processor to perform some or all of the steps of the method for cooperative multi-AP transmission of a first AP in the embodiments of Figures 2a to 4d and the channel information prediction method of a first AP in the embodiments of Figures 5a to 5i, e.g., steps 201 to 203 of Figure 2a, steps 301 to 303 of Figure 3a, steps 401 to 403 of Figure 4a, step 506 of Figure 5a, and / or another process used in the techniques described herein, or enable the processor to perform some or all of the steps of the method for cooperative multi-AP transmission of a second AP in the embodiments of Figures 2a to 4d and / or another process used in the techniques described herein, or enable the processor to perform some or all of the steps of the channel information prediction method of a first STA in the embodiments of Figures 5a to 5i, e.g., step 503 of Figure 5a and / or another process used in the techniques described herein.

[0299] The method or algorithm steps described in connection with the contents disclosed in this application may be implemented by hardware or by a processor executing software instructions. The software instructions may be formed by corresponding software modules. The software modules may be located in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable hard disk, a CD-ROM, or any other form of storage medium known in the art. For example, a storage medium may be coupled to the processor such that the processor can read information from or write information to the storage medium. Of course, the storage medium may be components of the processor. The processor and the storage medium may be located in an ASIC. In addition, the ASIC may also be located in a user device. Of course, the processor and the storage medium may reside as discrete components in the user device.

[0300] An embodiment of the present application further provides an apparatus, which may be a chip, and which may include a memory, the memory configured to store instructions.

[0301] For convenience of description, those skilled in the art can clearly understand that the detailed operation processes of the above-mentioned systems, devices and units can be referred to the corresponding processes in the above-mentioned method embodiments, and the details will not be described again here.

[0302] In some embodiments provided in the present application, it should be understood that the disclosed system, device, and method may be realized in other ways. For example, the described device embodiments are merely examples. For example, the unit division is merely a logical functional division, and other divisions may be used in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not implemented. In addition, the illustrated or discussed mutual couplings or direct couplings or communication connections may be realized through some interfaces. Indirect couplings or communication connections between devices or units may be realized in electronic, mechanical, or other forms.

[0303] Units described as separate components may or may not be physically separated, and components illustrated as units may or may not be physical units, located in one place, or distributed over multiple network units. Some or all of the units may be selected based on actual requirements to achieve the objectives of the solutions of each embodiment.

[0304] In addition, the functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist physically independent, or two or more units may be integrated into one unit. The integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0305] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application may essentially be realized, or the portion that contributes to the prior art, or all or part of the technical solution may be realized in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for instructing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method described in the embodiments of the present application. The aforementioned storage medium includes any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0306] In conclusion, the above embodiments are not intended to limit the present application, but are merely intended to illustrate the technical solutions of the present application. Although the present application has been described in detail in relation to the above embodiments, those skilled in the art should understand that, without departing from the spirit and scope of the technical solutions of the embodiments of the present application, they may further modify the technical solutions recorded in the above embodiments, or make equivalent substitutions for some technical features of the above embodiments. [Explanation of symbols]

[0307] 600 APPARATUS FOR COORDINATED MULTIPLE ACCESS POINT TRANSMISSION 601 Bus 602 processor 603 memory 604 Transceiver 605 Input Device 606 Output Device 700 APPARATUS FOR COORDINATED MULTIPLE ACCESS POINT TRANSMISSION 701 Bus 702 processor 703 memory 704 Transceiver 705 Input Device 706 Output Device

Claims

1. 1. A method for coordinated multi-access point (AP) transmission, comprising: a step of generating a first radio frame by a first access point AP, the first radio frame including indication information used to indicate a transmission time of a second radio frame transmitted by a second access point AP; transmitting the first wireless frame from the first access point AP to the second access point AP; transmitting a third wireless frame from the first access point AP to a first station STA associated with the first access point AP during a transmission period of the second wireless frame; A method comprising:

2. The method of claim 1 , wherein the indication information includes a transmission time and an end time of the second radio frame.

3. The method according to claim 1 or 2, wherein the transmission time of the third radio frame is the same as the transmission time of the second radio frame.

4. The method according to claim 1 or 2, wherein the transmission time of the third radio frame is before the transmission time of the second radio frame.

5. The method according to claim 1 , wherein the instruction information includes identifier information of the second access point AP.

6. The first radio frame: Transmission power information of the second access point AP, information on the maximum allowable interference threshold of the first access point AP, identifier information of the first station STA, transmission power information of the first station STA, and transmission power information of the first access point AP 6. The method of claim 1, further comprising delivering one or more of:

7. 7. The method according to claim 1, wherein the transmission time of the third radio frame is the same as the transmission time of the second radio frame.

8. 1. A method for coordinated multi-access point (AP) transmission, comprising: receiving, by a second access point AP, a first radio frame transmitted by a first access point AP, the first radio frame including indication information used to indicate a transmission time of a second radio frame; transmitting the second wireless frame from the second access point AP to a second station STA associated with the second access point AP during a transmission period in which the first access point AP transmits a third wireless frame to a first station STA associated with the first access point AP; A method comprising:

9. The method of claim 8 , wherein the indication information includes a transmission time and an end time of the second radio frame.

10. 10. The method of claim 8, wherein the transmission time of the second radio frame is the same as the transmission time of the third radio frame.

11. 10. The method of claim 8, wherein the transmission time of the second radio frame is before the transmission time of the third radio frame.

12. The method according to claim 8 , wherein the instruction information includes identifier information of the second access point AP.

13. The first radio frame: Transmission power information of the second access point AP, information on the maximum allowable interference threshold of the first access point AP, identifier information of the first station STA, transmission power information of the first station STA, and transmission power information of the first access point AP 13. The method of claim 8, further comprising delivering one or more of:

14. 14. The method according to claim 8, wherein the transmission time of the second radio frame is the same as the transmission time of the third radio frame.

15. An apparatus for coordinated multi-access point (AP) transmission, the apparatus being applied on a first access point (AP) side, the apparatus comprising: a processor configured to generate a first radio frame, the first radio frame including indication information used to indicate a transmission time of a second radio frame transmitted by a second access point (AP); a transceiver configured to transmit the first radio frame to the second access point AP, the transceiver is further configured to transmit a third radio frame to a first station STA associated with the first access point AP during a transmission period of the second radio frame; 1. An apparatus comprising:

16. The apparatus of claim 15 , wherein the indication information includes a transmission time and an end time of the second radio frame.

17. 17. The apparatus according to claim 15 or 16, wherein a transmission time of the third radio frame is the same as the transmission time of the second radio frame.

18. 17. The apparatus according to claim 15 or 16, wherein the transmission time of the third radio frame is before the transmission time of the second radio frame.

19. The apparatus according to claim 15 , wherein the instruction information includes identifier information of the second access point AP.

20. The first radio frame: Transmission power information of the second access point AP, information on the maximum allowable interference threshold of the first access point AP, identifier information of the first station STA, transmission power information of the first station STA, and transmission power information of the first access point AP 20. The apparatus of claim 15, further comprising one or more of:

21. 21. The apparatus according to claim 15, wherein a transmission time of the third radio frame is the same as the transmission time of the second radio frame.

22. An apparatus for coordinated multi-access point (AP) transmission, the apparatus being applied on a second access point (AP) side; A transceiver configured to receive a first radio frame transmitted by a first access point AP, the first radio frame including indication information used to indicate a transmission time of a second radio frame; the transceiver is further configured to transmit the second radio frame to a second station STA associated with the second access point AP during a transmission period in which the first access point AP transmits a third radio frame to a first station STA associated with the first access point AP.

1. An apparatus comprising:

23. 23. The apparatus of claim 22, wherein the indication information includes a transmission time and an end time of the second radio frame.

24. 24. The apparatus of claim 22 or 23, wherein the transmission time of the second radio frame is the same as the transmission time of the third radio frame.

25. 24. The apparatus of claim 22 or 23, wherein the transmission time of the second radio frame is before the transmission time of the third radio frame.

26. The apparatus according to claim 22 , wherein the instruction information includes identifier information of the second access point AP.

27. The first radio frame: Transmission power information of the second access point AP, information on the maximum allowable interference threshold of the first access point AP, identifier information of the first station STA, transmission power information of the first station STA, and transmission power information of the first access point AP 27. The apparatus of any one of claims 22 to 26, further delivering one or more of:

28. 28. The apparatus of claim 22, wherein the transmission time of the second radio frame is the same as the transmission time of the third radio frame.

29. 1. A method for coordinated multi-access point (AP) transmission, comprising: a first access point AP generating a first radio frame; a step of transmitting the first wireless frame from the first access point AP to a second access point AP, wherein the first wireless frame is used to trigger the second access point AP to transmit a second wireless frame to a second station STA associated with the second access point AP, and the first wireless frame includes first instruction information so that the second access point AP determines a transmission end time of the second wireless frame according to the first instruction information; A method comprising:

30. 1. A method for coordinated multi-access point (AP) transmission, comprising: receiving, by a second access point AP, a first radio frame transmitted by a first access point AP, the first radio frame carrying first indication information; the second access point AP determining a transmission end time of a second wireless frame according to the first instruction information; transmitting the second wireless frame by the second access point AP to a second station STA associated with the second access point AP; A method comprising:

31. the first indication information is used to indicate a transmission end time of the first radio frame or a transmission duration of the first radio frame, and the transmission end time of the first radio frame is the same as the transmission end time of the second radio frame; the step of determining, by the second access point AP, a transmission end time of a second wireless frame according to the first instruction information, the second access point AP determining the transmission end time of the first wireless frame as the transmission end time of the second wireless frame; or a step in which the second access point AP determines the transmission end time of the first wireless frame based on the transmission time of the first wireless frame and the transmission start time of the first wireless frame, wherein the transmission end time of the first wireless frame is equal to the transmission end time of the second wireless frame; 31. The method of claim 30, comprising:

32. A channel information prediction method, comprising: a step of receiving a broadcast frame from a first access point (AP) by a first station (STA), the broadcast frame including identifier information of a second access point (AP), the broadcast frame being used to trigger the first station (STA) to detect a channel between the second access point (AP) and the first station (STA), and the first station (STA) is associated with the first access point (AP); The first station STA determines channel quality information of a target channel based on a received radio frame transmitted by a target AP, the target channel being a channel between the target AP and the first station STA, and the target AP being included in the second access point AP; a step of transmitting a feedback frame from the first station STA to the first access point AP, the feedback frame including the channel quality information of the target channel; A channel information prediction method, comprising:

33. The broadcast frame may further include sequence indication information, and the sequence indication information is used to instruct the second access point AP to broadcast null data packets NDP in sequence.

33. The channel information prediction method of claim 32.

34. The wireless frame transmitted by the target AP is a null data packet NDP, and after the step of the first station STA receiving the wireless frame transmitted by the target AP, and before the step of the first station STA transmitting a feedback frame to the first access point AP, the method includes: The first station STA determines the target AP based on the sequence indication information.

34. The channel information prediction method of claim 33, further comprising:

35. Before the step of the first station STA transmitting a feedback frame to the first access point AP, the method further comprises: receiving, by the first station STA, a trigger frame transmitted by the first access point AP, the trigger frame being used to trigger the first station STA to transmit the feedback frame, the trigger frame including resource scheduling information, the resource scheduling information being used to indicate channel resources to be used by the first station STA to transmit the feedback frame; or the first station STA successfully acquires a channel through contention, the channel being used to transmit the feedback frame; 35. The channel information prediction method according to any one of claims 32 to 34, further comprising:

36. A channel information prediction method, comprising: a step of transmitting a broadcast frame from a first access point AP to a first station STA associated with the first access point AP, the broadcast frame carrying identifier information of a second access point AP, and the broadcast frame being used to trigger the first station STA to detect a channel between the second access point AP and the first station STA; receiving, by the first access point AP, a feedback frame transmitted by the first station STA, the feedback frame carrying channel quality information of a target channel detected by the first station STA, the target channel being a channel between a target AP and the first station STA, the target AP being an access point AP for communicating with the first station STA, and the target AP being included in the second access point AP; A channel information prediction method, comprising:

37. After the step of the first access point AP receiving a feedback frame transmitted by the first station STA, the method further comprises: the first access point AP determining a signal-to-interference ratio (SIR) of the first station STA based on the channel quality information of the target AP; 37. The channel information prediction method of claim 36, further comprising:

38. Before the step of the first access point AP receiving a feedback frame transmitted by the first station STA, the method further comprises: a step in which the first access point AP transmits a trigger frame to the first station STA, the trigger frame being used to trigger the first station STA to transmit the feedback frame, the trigger frame carrying resource scheduling information, the resource scheduling information being used to indicate a channel resource to be used by the first station STA to transmit the feedback frame; 38. The channel information prediction method of claim 36 or 37, further comprising:

39. The broadcast frame further carries order indication information, and the order indication information is used to indicate an order in which the second access point AP transmits a null data packet NDP, so that the first station STA performs signal quality detection on a channel between the second access point AP and the first station STA based on the received NDP.

39. A channel information prediction method according to any one of claims 36 to 38.

40. An apparatus for coordinated multi-access point (AP) transmission, the apparatus being applied on a first access point (AP) side; a processor configured to generate a first radio frame; a transceiver configured to transmit the first radio frame to a second access point (AP), wherein the first radio frame is used to trigger the second access point (AP) to transmit a second radio frame to a second station (STA) associated with the second access point (AP); a transceiver, wherein the first radio frame includes first indication information, and the first indication information is used by the second access point AP to determine a transmission end time of the second radio frame; 1. An apparatus comprising:

41. An apparatus for coordinated multi-access point (AP) transmission, the apparatus being applied on a second access point (AP) side; a transceiver configured to receive a first radio frame transmitted by a first access point AP, the first radio frame carrying first indication information; a determination unit configured to determine a transmission end time of the second radio frame according to the first instruction information; Including, The transceiver is further configured to transmit the second radio frame to a second station STA associated with the second access point AP. Device.

42. A channel information detection device, the channel information detection device being applied to a first station STA side; a transceiver configured to receive a broadcast frame transmitted by a first access point (AP), the broadcast frame including identifier information of a second access point (AP), the broadcast frame being used to trigger the first station (STA) to detect a channel between the second access point (AP) and the first station (STA), the first station (STA) being associated with the first access point (AP); a determining unit configured to determine channel quality information of a target channel based on a received radio frame transmitted by a target AP, the target channel being a channel between the target AP and the first station STA, and the target AP being included in the second access point AP; Including, The transceiver is further configured to transmit a feedback frame to the first access point AP, the feedback frame including the channel quality information of the target channel. Channel information detector.

43. A channel information detection device, the channel information detection device being applied to a first access point (AP), transmitting a broadcast frame to a first station STA associated with the first access point AP, the broadcast frame carrying identifier information of a second access point AP, the broadcast frame being used to trigger the first station STA to detect a channel between the second access point AP and the first station STA; a transceiver configured to receive a feedback frame transmitted by the first station STA, the feedback frame carrying channel quality information of a target channel detected by the first station STA, the target channel being a channel between a target AP and the first station STA, and the target AP being included in the second access point AP. A channel information detection device comprising:

44. a memory configured to store instructions, A memory, wherein the instructions stored in the memory, when executed by a processor, enable the processor to perform corresponding functions in the method of any one of claims 1 to 14 or claims 29 to 39.

1. An apparatus comprising:

45. 40. A computer readable storage medium comprising instructions which, when executed on a computer, enable the computer to perform the method of any one of claims 1 to 14 or claims 29 to 39.

46. 40. A computer program product comprising instructions which, when executed on a computer, enable the computer to perform a method according to any one of claims 1 to 14 or claims 29 to 39.

47. 40. Apparatus configured to perform a method according to any one of claims 1 to 14 or claims 29 to 39.

Images