Integrated circuit for access point (AP)

Abstract

There is provided an integrated circuit for an access point (AP), the integrated circuit including at least one input to input an electrical signal, and a controller circuit to control: packaging Joint Transport (JT) data, and generating a frame including the packaged JT data and a JT identification uniquely identifying the JT data; and transmitting the frame to one or more other APs jointly transmitting the JT data to the communication device, and transmitting a JT trigger frame comprising the JT identification to the one or more other APs, characterized in that the encapsulated JT data and the JT identification in the JT packet ID field are included in the frame.

Description

[0001] This application is a divisional application of an invention patent application with an application date of March 11, 2020, application number 202080028188.4, and invention name “Communication device and communication method for multi-AP joint transmission”. Technical Field

[0002] The present disclosure relates generally to communication apparatus and methods for electronic devices and systems, and more particularly, to joint transmission in a multi-AP network. Background Art

[0003] Wireless networks that communicate via multi-AP joint transmissions enable electronic devices to communicate in a network with joint transmissions sent to multiple electronic devices. Such networks are superior to other wireless networks in which wireless communication is limited to a single transmission to one electronic device. Summary of the invention

[0004] One non-limiting and exemplary embodiment facilitates providing joint transmission communications in a multi-AP network. For example, the communications include joint transmissions from two or more access points (APs) to one or more wireless stations (STAs).

[0005] In one general aspect, the technology disclosed herein features an access point (AP). The access point includes: a circuit that generates a frame including joint transmission (JT) data and a JT identifier that uniquely identifies the JT data; and a transmitter that sends the frame to one or more other APs that jointly send the JT data to a communication device.

[0006] In a general aspect, the technology disclosed herein includes an integrated circuit for an access point AP, the integrated circuit including: at least one input, an input electrical signal, and a controller circuit that controls: encapsulating jointly transmitted JT data, and generating a frame including the encapsulated JT data and a JT identifier that uniquely identifies the JT data; and sending the frame to one or more other APs that jointly send the JT data to a communication device, and sending a JT trigger frame including the JT identifier to the one or more other APs, characterized in that the encapsulated JT data and the JT identifier in the JT group ID field are included in the frame.

[0007] It should be noted that the general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof.

[0008] Other beneficial effects and advantages of the disclosed embodiments will become apparent through the specification and the accompanying drawings. Beneficial effects and / or advantages can be obtained individually through the various embodiments and features of the specification and the accompanying drawings, and these embodiments and features do not need to be provided in their entirety in order to obtain one or more such beneficial effects and / or advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, in which like reference numerals refer to the same or functionally similar elements in the separate views and which are incorporated into and form a part of the specification together with the following detailed description, serve to illustrate various embodiments and to explain various principles and advantages according to embodiments of the present invention.

[0010] Figure 1 is a wireless network with a multi-AP system according to an example embodiment.

[0011] Figure 2A is a multi-AP system shown as an enterprise network according to an example embodiment.

[0012] Figure 2B is a multi-AP system shown as a home or office network according to an example embodiment.

[0013] Figure 2C is a multi-AP system shown in a master-slave configuration according to an example embodiment.

[0014] Figure 3 is a MAC protocol data unit (MPDU) according to an example embodiment.

[0015] Figure 4 is a message sequence in joint transmission in a multi-AP system according to an example embodiment.

[0016] Figure 5A and Figure 5B is a data frame for encapsulating JT data according to an example embodiment.

[0017] Figure 6 Shown are a data frame, a first table showing protocol names and payload types, and a second table showing AP coordination packet types according to an example embodiment.

[0018] Figure 7 A joint transmission between a master AP, a slave AP, and a target STA is shown according to an example embodiment.

[0019] Figure 8 is a JT trigger frame according to an example embodiment.

[0020] Fig. 9 is a message sequence for a joint transmission session between a master AP and a slave AP in a multi-AP system according to an exemplary embodiment.

[0021] Fig.10 AP coordination action frames exchanged over the air to negotiate or tear down a joint transmission session are shown according to an example embodiment.

[0022] Fig.11 A frame is shown in which an Ethernet frame encapsulates JT data and an AP coordination action frame according to an example embodiment.

[0023] Fig.12 A trigger frame for joint transmission to a target STA according to an example embodiment is shown.

[0024] Fig.13 A communication exchange is shown in which the master AP does not participate in the joint transmission according to an example embodiment.

[0025] Fig.14 An action frame used by an AP to collect information from another AP during an information inquiry phase is shown according to an example embodiment.

[0026] Fig.15 A frame for data sharing from a master AP to a slave AP according to an example embodiment is shown.

[0027] Fig.16 A JT data frame is shown as an aggregate MAC protocol data unit (A-MPDU) according to an example embodiment.

[0028] Fig.17 A frame is shown as an Aggregate MAC Protocol Data Unit (A-MPDU) for data sharing to a slave AP according to an example embodiment.

[0029] Fig.18 A joint transmission trigger frame according to an example embodiment is shown.

[0030] Fig.19 is an example of a distributed MU-MIMO joint transmission to two STAs, both associated with a primary AP, according to an example embodiment.

[0031] Fig. 20 is an example of an electronic device according to an example embodiment.

[0032] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. DETAILED DESCRIPTION

[0033] Electronic devices can be configured to send and receive joint transmission (JT) data in a multi-AP network. These electronic devices have many advantages over conventional electronic devices that are limited to a single transmission to a single electronic device. However, there are many technical problems in performing joint transmission in a multi-AP network.

[0034] The existing 802.11 BSS (Basic Service Set) operates as an independent unit. The AP of each BSS provides wireless communication services only to the wireless stations (STAs) associated with the corresponding AP. The data rate that the AP can provide for the wireless link to the associated STA depends on the MCS (Modulation and Coding Scheme) used for the link, which in turn depends on the SINR (Signal to Interference plus Noise Ratio) of each STA. A higher MCS can usually be achieved at a higher SINR, while only a low MCS may be achieved at a low level of SINR. In an independent BSS, while the signal ratio can be controlled by the AP by adjusting the transmit power, the interference experienced by the STA is more difficult to control. This problem is particularly true for STAs that exist at the edge of the network and are within the wireless range of multiple BSSs, also known as OBSS (Overlapping BSS) areas. The useful signal in one BSS is essentially interference to the STA of another BSS.

[0035] Multi-AP coordination (e.g., coordination between APs of neighboring BSSs) can be used as an effective way to improve the SINR of member STAs. Such a scheme is possible due to the proliferation of APs, such as dense AP deployment in managed networks (e.g., enterprise networks, stadium settings, etc.) or home networks (e.g., home mesh networks with multiple APs).

[0036] Various multi-AP coordination schemes can be divided into two general groups. The first group includes schemes that attempt to reduce interference to the OBSS through transmit power control, coordinated beamforming, coordinated null forming, coordinated scheduling, etc. The second group includes schemes that attempt to increase the signal level at the STA through synchronous transmission to the same STA by multiple APs. The schemes of the second group can be called multi-AP joint processing or multi-AP joint transmission, or distributed MU-MIMO.

[0037] Joint transmission can not only improve the signal level, but also reduce interference by converting interfering signals into desired signals. Example embodiments therefore solve technical problems associated with STAs in overlapping BSSs or multi-AP systems by reducing interference to STAs and improving SINR to STAs. These problems include how to distribute and synchronize joint transmission data (joint MU-MIMO data) between slave APs and other issues discussed herein.

[0038] Example embodiments include apparatus and methods for sending and receiving joint transmissions in a multi-AP network. Such apparatus and methods include electronic devices such as APs and STAs having a transmitter and / or a receiver. An exemplary embodiment is an AP, comprising: a circuit that generates a frame, the frame body of the frame including joint transmission (JT) data and a JT identifier that uniquely identifies the JT data; and a transmitter that sends the frame to one or more APs, which jointly send the JT data to a communication device.

[0039] Another example embodiment is an access point (AP) including: a receiver that receives a frame including joint transmission (JT) data and a JT identification that uniquely identifies the JT data from the AP; and a local memory that stores the JT data and the JT identification.

[0040] Another example embodiment is a communication method in which one or more access points (APs) jointly transmit to a communication device. The method includes transmitting a frame from a first AP to one or more second APs, wherein a frame body of the frame includes joint transmission (JT) data and a JT identifier that uniquely identifies the JT data; and jointly transmitting the JT data from the one or more second APs to the communication device.

[0041] Figure 1 1 is a wireless network with a multi-AP system 100 according to an example embodiment. For example, the system 100 includes three BSSs (shown as BSS1, BSS2, and BSS3). Each BSS has at least one AP (shown as AP1, AP2, and AP2). Multiple STAs (shown as STA1-STA5) are distributed throughout the system. STA1 exists in a single BSS (BSS1); STA2 exists in three overlapping BSSs (BSS1–BSS3); STA3 exists in two overlapping BSSs (BSS1 and BSS3); STA4 exists in two overlapping BSSs (BSS2 and BSS3); and STA5 exists in a single BSS (BSS2).

[0042] exist Figure 1 , although STA2 is associated with AP3, the three APs (AP1, AP2, and AP3) can coordinate their transmissions to simultaneously transmit to STA2. This simultaneous transmission increases the SINR level of STA2 and facilitates the use of a higher MCS which translates into higher throughput for STA2.

[0043] Although multi-AP coordination schemes typically utilize some kind of time synchronization between participating APs, joint transmissions utilize the highest level of synchronization, especially distributed MU-MIMO. Therefore, one or more exemplary embodiments implement joint transmissions where one AP (referred to as the master AP) provides the synchronization signal and the other participating APs (referred to as slave APs) are within range of the master AP. Figure 1 , AP3 may be the master AP, while AP1 and AP2 are slave APs. The master AP may also be referred to as an alternative name such as a coordinated AP, or a joint transmission (JT) AP or a multi-AP controller, and the slave AP may also be referred to as a multi-AP device or a coordinated AP, etc.

[0044] In an example embodiment and as discussed in more detail below, the joint transmission includes all participating APs sending the same signal to the STA. This includes MAC layer specific fields that are equivalent to all participating APs.

[0045] Figure 2A It is a multi-AP system 200 shown as an enterprise network according to an example embodiment. For example, the system includes multiple APs (shown as AP1-AP8) broadcasting with overlapping transmissions. Each AP operates its own channel (Ch), such as AP1 at Ch 36, AP2 at Ch 52, AP3 at Ch 149, AP4 at Ch 44, AP5 at Ch 56, AP6 at Ch 161, AP7 at Ch 48, and AP8 at Ch 60.

[0046] In enterprise networks, AP locations and frequency allocations are carefully planned during deployment to maximize capacity. Figure 2A As shown, adjacent APs use non-overlapping channels to minimize inter-BSS interference. APs can use high-gain directional antennas with narrow beamwidths. Adjacent APs may not be within each other's wireless range. Multiple APs or all APs can use the same service set identifier (SSID). In addition, the APs are connected using Ethernet and can be configured and / or controlled by a central AP controller. Most edge STAs will be within the coverage of at least two APs. AP-to-AP communication can use, for example, Ethernet or out-of-band mesh wireless direct links. Even if adjacent APs are assigned non-overlapping primary channels, inter-BSS interference is inevitable in the OBSS area when wideband channels are used. Since most enterprise networks are centrally managed and coordination between APs is easier, enterprise networks are prime candidates for joint transmission systems.

[0047] Figure 2B2 is a multi-AP system 230 shown as a home or office network according to an exemplary embodiment. For example, the system includes multiple APs (shown as AP1-AP3) broadcasting with overlapping transmissions. Each AP operates its own channel, such as AP1 at Ch 36, AP2 at Ch 149, and AP3 at Ch 52.

[0048] A multi-AP system (such as Wi-Fi EasyMesh) is an example configuration that provides Wi-Fi coverage throughout an area, such as a house or office. AP bit positions and frequency allocations are planned to maximize coverage. For example, one AP can act as a multi-AP controller, while the remaining APs act as multi-AP agents. The AP can be expected to be within the wireless coverage of at least one other AP. The backhaul BSS is set for AP to AP signaling. The backhaul BSS can use a different SSID from the fronthaul SSID. Most edge STAs will be within the coverage of at least two APs. In addition, AP to AP communication can use a wireless direct link or a mixture of wireless and wired links. This multi-AP home or small office network is also a good candidate for a joint transmission system.

[0049] Figure 2C 260 is a multi-AP system 260 shown in a master-slave configuration according to an exemplary embodiment. For example, the system includes a master AP 270, two slave APs 280 and 282, and a STA 284. AP-to-AP communication occurs on link 290, while communication between AP and STA occurs on link 292.

[0050] For joint transmission, the AP has transmission data (upper layer data) to be sent jointly to the STAs before the actual joint transmission. However, in one or more example embodiments, in order to achieve SINR gain for joint transmission, having the transmission data may not be enough. The actual data symbols sent over the air need to be synchronized between participating APs, such as multiple APs or all APs. This means that the PHY layer and MAC layer processing of the transmission data are the same between the participating APs. Example embodiments include systems, devices, and methods for distributing and synchronizing data for multi-AP joint transmission.

[0051] In one or more example embodiments, joint transmission is performed in two phases: distribution of JT data to slave APs and joint transmission to target STAs.

[0052] In the first phase (distribution of joint transmission data from AP to AP), the AP to AP link (such as Figure 2CPrior to the actual joint transmission on the link 290 in the master AP, the data to be sent jointly is distributed to the participating slave APs. The distribution can occur over a wireless backhaul link between the APs, or it can also occur over a wired backhaul link between the APs, such as Ethernet. When wireless backhaul is used, for the purpose of communicating between the APs, the slave APs may have associated with the master AP on a separate BSS established by the master AP before initiating the joint transmission. The wireless channel used for the backhaul link between the APs may be different from the fronthaul link between the AP and the target STA.

[0053] In the second phase (joint transmission to the target STA), the actual joint transmission of two or more participating APs to the target STA occurs over a link such as Figure 2C The joint transmission may be preceded by a synchronization signal from the master AP via link 290, which may be referred to as a slave trigger frame or a joint transmission (JT) trigger frame. In some scenarios, the master AP may also participate in the joint transmission, while in some scenarios, the master AP may not participate in the joint transmission and only the slave AP may participate. Different AP sets may be involved in the joint transmission of different target STAs.

[0054] Figure 3 is a MAC protocol data unit (MPDU) 300 to be jointly transmitted according to an example embodiment. The MPDU includes a MAC header and a frame body. The MAC header includes frame control, duration, address 1 (receiver address), address 2 (transmitter address), address 3 (BSSID), sequence control, QoS control, and HT control. The frame body includes data payload, MIC, and FCS. If the data frame carries an A-MSDU, the address 3 field carries the BSSID, otherwise the address 3 field carries the source address (SA), that is, the MAC address of the device that is the source of the data payload.

[0055] To achieve the SINR gain of the joint transmission, the actual data symbols sent over the air are synchronized between the participating APs. In addition, the PHY layer and MAC layer processing of the transmission are the same between the participating APs. Typically, for normal transmission (e.g., non-joint transmission), the upper layer (e.g., IP layer) passes the data payload to be transmitted (e.g., IP packet) to the MAC layer, which performs MAC layer processing such as pre-pending the MAC header, adding the FCS, MAC padding if necessary (etc. to create the MPDU (MAC Protocol Data Unit) 300. If protection is enabled, the data payload may further undergo an encryption process, which results in the CCMP header field and the MIC field being added to the MAC frame body. The MPDU is then passed down to the PHY layer for PHY layer processing, such as pre-pending the PHY preamble, applying PHY coding, adding PHY padding, etc. to create the PPDU (PHY Protocol Data Unit), and finally sending the PPDU into the air.

[0056] For joint transmission, the participating APs need to know the MAC and PHY parameters to be applied to the data payload. In addition, at the MAC layer, several fields are generated locally. While some fields like frame control, address 2 (TA), address 3 (BSSID), QoS control, HT control may be overwritten by the MAC layer of the slave AP to match the fields generated by the master AP, some fields like sequence control, CCMP header are different for each MPDU and are usually generated locally at each AP; therefore, these fields are more difficult to synchronize between APs. In addition, more than one MPDU can also be aggregated at the MAC layer to form an A-MPDU (aggregate MPDU), or one MPDU can constitute an S-MPDU (single MPDU). In order to synchronize the data to be sent jointly between the MAC layers of all participating APs, the master AP can generate and distribute the actual MAC layer A-MPDU or S-MPDU to all participating slave APs. The sequence control field in the MPDU is also generated by the master AP, and the same digital space is used for the sequence number subfield of the sequence control field to be used for both direct transmission from the master AP to the target STA (i.e., single AP transmission) and for joint transmission. If encryption is enabled, the master AP also encrypts the data payload and appends the MIC field. In this case, joint transmission (JT) data refers to MAC layer data to be sent jointly.

[0057] In some cases, the master AP may not be involved in the actual joint transmission phase (e.g., only slave APs may participate in the joint transmission). This may happen when the master AP is implemented as a central controller and is far away from the target STA. In this case, the target STA will associate with one of the slave APs instead of the master AP.

[0058] In this case where the target STA is associated with a slave AP, during the data distribution phase, the master AP sets the MAC header fields of the MPDU 300 so that the MPDU appears to be generated by the slave AP associated with the target STA, for example, the Address 2 (TA) field and the Address 3 (BSSID) are set to the MAC address of the slave AP. The master AP also queries the slave AP for the next sequence control to be used, and optionally the CCMP packet number (PN) and encryption key ID for transmission to the target STA and setting the fields of the MPDU 300, respectively. In this case, the sequence control field in the MPDU is generated by the slave AP, and the same digital space is used for the sequence number subfield of the sequence control field to be used for both direct transmission from the slave AP to the target STA (i.e., single AP transmission) and joint transmission.

[0059] Figure 4 is a message sequence 400 in a joint transmission in a multi-AP system according to an example embodiment.

[0060] In distributed wireless networks, such as 802.11 WLANs, access to the wireless channel is controlled by CSMA / CA, and it is difficult to predict the exact transmission time. Also, transmission failures and retransmissions make it difficult to maintain the order of transmissions. Therefore, for joint transmission, it may be advantageous to separate the data distribution phase and the joint transmission phase.

[0061] like Figure 4 As shown, joint transmission occurs in two phases: distribution of joint transmission data to slave APs and joint transmission to one or more target STAs. In the first phase, one or more joint transmission data are distributed to slave APs (e.g., on wireless backhaul). Each joint transmission data is assigned a unique ID. In the second phase, the master AP initiates the joint transmission by sending a JT trigger frame. The frame carries a unique ID that identifies the joint transmission data to be sent jointly by all participating APs.

[0062] Figure 4 An example message sequence involved in a joint transmission is shown in which a data distribution phase 410 is separated from a joint transmission phase 420. During the data distribution phase 410, the master AP distributes one or more joint transmission (JT) data to the slave APs. In this case, the JT data may be an actual S-MPDU or A-MPDU to be sent jointly and encapsulated in another data frame addressed to the slave AP. In order to reduce the overhead of distributing the JT data, the encapsulated data frame may be sent to the slave AP as a multicast transmission rather than a unicast transmission. The master AP may also use a multi-user (MU) PPDU format to distribute different JT data to different slave APs simultaneously.

[0063] In order to uniquely identify each JT data, the master AP also assigns a unique ID to each JT data, which can be called a JT packet ID. After receiving the encapsulated JT data, each slave AP decapsulates the JT data and saves it in a local memory indexed by the JT packet ID. In order to ensure that the slave AP saves the JT data instead of forwarding it to the target STA immediately, the data frame encapsulating the JT data can be addressed to the slave AP by setting the RA to the MAC address of the slave AP. If a four-address MAC header is used for the data frame to the slave AP, both the RA (address 1) and the DA (address 3) can be set to the MAC address of the slave AP. Due to the strict time synchronization requirements for joint transmission and faster retrieval, the JT data frame can be saved in a separate memory (for example, different from the local EDCA queue).

[0064] In the joint transmission phase 420, the master AP initiates the joint transmission by sending a JT trigger frame to the slave APs. The JT trigger frame provides time synchronization to the slave APs. In addition, the JT trigger frame also carries the JT group ID of the JT data to be jointly transmitted. After receiving the JT trigger frame, each slave AP retrieves the JT data from the local memory corresponding to the JT group ID and sends a JT PPDU constructed by the JT data.

[0065] Figure 5A and Figure 5B is a data frame for encapsulating JT data according to an example embodiment.

[0066] Figure 5A A data frame 500 sent by a master AP is shown, which encapsulates JT data, in this case, an S-MPDU, within the frame body of the data frame 500. The S-MPDU consists of an MPDU delimiter, an actual MPDU, and padding (if necessary). A unique ID (JT packet ID) is assigned to each joint transmission data. In this case, the JT packet ID uniquely identifies the S-MPDU.

[0067] Figure 5B A data frame 550 sent by a master AP is shown, which encapsulates JT data, which in this case is an A-MPDU, within the frame body of the data frame 550. An A-MPDU consists of two or more A-MPDU subframes, and EOF (end of frame) padding if necessary. Each A-MPDU subframe shares the same format as an S-MPDU. In this case, the JT packet ID uniquely identifies the A-MPDU.

[0068] If encryption is enabled, each MPDU in the JT data is also encrypted by the master AP before being encapsulated into the data frame 500 or 550.

[0069] Each slave AP, after receiving the encapsulated JT data, decapsulates the JT data and saves it in a local memory indexed by the JT packet ID. Due to the strict time synchronization requirements of the joint transmission, the JT data frame can be stored in a separate memory (e.g., different from the local EDCA queue) for faster retrieval.

[0070] The slave AP does not immediately forward received JT data to the target STA. To ensure this, if a four-address MAC header is used for a data frame to a slave AP, both RA (address 1) and DA (address 3) are set to the MAC address of the slave AP.

[0071] Figure 6 Shown is a data frame 600, a first table 610 showing encoding of a payload type field, and a second table 620 showing encoding of an AP coordination packet type field, according to an example embodiment.

[0072] Data frame 600 encapsulates JT data during the data distribution phase (e.g., in Figure 4 410 in ). In this example, the frame body of data frame 600 carries an Ethernet type 89-0d frame with the payload type field set to 5 "AP coordination" to distinguish it from other encapsulation types. Ethernet type 89-0d is an Ethernet type originally assigned for encapsulation of IEEE 802.11 frames within Ethernet frames. When the payload type is set to "AP coordination", the payload of the Ethernet type 89-0d frame can carry JT data in the packet content field when the AP coordination packet type field is set to 0, 1, or 2, as indicated in table 620. The destination MAC address carries the MAC address of the target STA (e.g., the target of the joint transmission). The JT packet ID is a unique ID assigned to the JT data, and the packet length field indicates the size of the JT data carried in the packet content field. When 802.11 data frames are used exclusively to encapsulate JT data, the sequence number subfield 630 in the sequence control field 632 of the host 802.11 data frame can serve as an implicit JT packet ID, and the JT packet ID field can be omitted in the Ethernet type 89-0d frame body.

[0073] To ensure that the slave AP saves the JT data instead of forwarding it immediately to the target STA, the data frame 600 encapsulating the JT data is addressed to the slave AP by setting the RA field of the MAC header to the MAC address of the slave AP. If a four-address MAC header is used, both RA (address 1) and DA (address 3) are set to the MAC address of the slave AP.

[0074] Figure 7 A joint transmission 700 between a master AP, a slave AP, and a target STA is shown according to an example embodiment.

[0075] During the joint transmission phase (e.g. Figure 4 420 in ), the master AP initiates a joint transmission by sending a JT trigger frame 710 to the slave APs. In addition to PHY and MAC parameters for synchronization, the JT trigger frame also carries the JT packet ID of the JT data to be jointly transmitted. The MAC layer of each slave AP, upon receiving the JT trigger frame that identifies the slave AP as a participating AP in the joint transmission, retrieves the JT data from the local memory corresponding to the JT packet ID and passes it down to the PHY layer, which builds a JT PPDU from the JT data before sending it SIFS (Short Inter-Frame Space) after the end of the JT trigger frame. The master AP also builds a JT PPDU from the JT data corresponding to the JT packet ID after the end of the JT trigger frame and sends the JT PPDU SIFS (Short Inter-Frame Space). Since the channel status at different APs may be different, each slave AP may need to consider the channel conditions and send the JT PPDU only when the channel is considered to be idle during the SIFS after the end of the JT trigger frame, except that the NAV (Network Allocation Vector) setting due to the transmission of the master AP or the target STA can be ignored. For the target STA, after receiving the JT data, it may not even know that multiple APs are involved in the transmission. As far as the target STA is concerned, this is just another transmission to it from the primary AP or the AP whose MAC address appears in the TA Address (Address 2) field of the frame. If the reception is successful, the target STA proceeds to send an acknowledgment frame (ACK or Block Ack) to the AP whose MAC address appears in the TA Address (Address 2) field.

[0076] Figure 8 800 is a JT trigger frame according to an example embodiment. Each user information field carries information from a set of APs and target STAs.

[0077] The MAC address field of the slave AP identifies the slave AP that participates in the joint transmission for a particular set of STAs. This can be omitted if only a single slave AP is involved in the joint transmission, and the slave AP is identified by the RA field in the MAC header. The AID 12 field within each user information field can be set to a special value (e.g., 2047) to distinguish the JT trigger frame from other trigger frames used to request uplink OFDMA transmissions.

[0078] The JT Packet ID field identifies the (stored) MPDU to be carried in the JT PPDU. In the case of an S-MPDU, this may also be the value of the Sequence Control field of the S-MPDU. If the same data is to be sent jointly (transmit diversity), the field value for different slave APs may be the same. Alternatively, when different data is to be sent jointly (D-MIMO), the field value may be different for different slave APs.

[0079] In addition, the joint transmission PHY layer information specifies additional PHY parameters used to encode the JT PPDU. The target STA information carries relevant information for joint transmission from the AP to one or more target STAs. The joint transmission information identifies the stored data to be sent and the spatial streams for the target STA.

[0080] In addition, the Spatial Stream Assignment field indicates the spatial streams assigned to each target STA and is present only in the case of MIMO joint transmission. The Start Spatial Stream field indicates the first spatial stream assigned to the STA, and the Spatial Stream Number field indicates the total number of consecutive spatial streams assigned to the STA, including the first spatial stream.

[0081] Fig. 9 9 is a message sequence 900 for a joint transmission session between a master AP and a slave AP in a multi-AP system according to an example embodiment.

[0082] If the joint transmission is expected to be sent for more than one or two frames, the example embodiment establishes a joint transmission session between the master AP and the participating slave APs before the actual joint transmission. During the joint transmission session negotiation process, the master AP and the slave AP exchange information about the target STA involved in the joint transmission. The master AP and the slave AP also specify the joint transmission parameters expected to be used throughout the session, such as the channel to be used, the PPDU format (HT, VHT or HE, etc.), the precoding scheme for MU-MIMO, etc. Each joint transmission session is identified by a unique session ID. The master AP initiates the establishment of a joint transmission session by sending an AP coordination session request frame to the slave AP. If the slave AP accepts the request, it sends an AP coordination session response frame with the status code field set to accepted back to the master AP. The master AP repeats this process for each slave AP participating in the joint transmission. To terminate the session, the master AP sends an AP coordination session teardown frame to the slave AP.

[0083] Fig.10 The AP coordination action frames exchanged between APs to negotiate or tear down a joint transmission session according to an example embodiment are shown. The figure shows an AP coordination session request 1000, an AP coordination session response 1002, an AP coordination session teardown 1004, a table 1010 with AP coordination session action field values, and a table 1020 with AP coordination type field values.

[0084] A new action frame category is defined for multi-AP coordination and is indicated in the category field. Five new action frames are defined for the purpose of AP-to-AP communication related to multi-AP coordination, three of which are used for session establishment / teardown (indicated by the value of the "AP coordination session action" field, as listed in Table 1010). Sessions can be established for various types of multi-AP coordination schemes and indicated by the value of the "AP coordination type" field in the AP coordination session request frame, as listed in Table 1020. For example, for a joint transmission session, it is set to 2. The "target STA information" field in the AP coordination session request frame 1000 lists the MAC addresses of one or more target STAs that are expected to participate in the joint transmission.

[0085] The "Type Specific Parameters" field in the AP coordination session request frame 1000 carries additional session parameters specific to the AP coordination type. For example, for a joint transmission, this field may specify channel information for the joint transmission. The channel information may be present when the master AP and the slave AP operate on different fronthaul channels. The "Type Specific Parameters" field may also indicate the start time when the joint transmission is expected to begin. In dense networks, it is common for neighboring APs to operate on different channels to mitigate inter-BSS interference. If the channel specified in the channel information is different from the operating channel of the slave AP, and if the slave AP accepts the AP coordination session request, the slave AP is expected to switch the channel to the specific joint transmission channel before the indicated joint transmission start time.

[0086] As another example, for joint transmission, if encryption is enabled for joint transmission and encryption needs to be performed locally at each AP, the "Type Specific Parameters" field may also include a security key (eg, PTK) used for encryption.

[0087] As yet another example, for a joint transmission, the "Type Specific Parameters" field may also include the amount of buffer space requested by the master AP to be allocated by the slave AP to hold the JT data frames.

[0088] Fig.11 Frame 1100 is shown in which an Ethernet frame encapsulates JT data as well as an AP coordination action frame according to an example embodiment.

[0089] The master AP encapsulates the joint transport data frame (the entire S-MPDU or A-MPDU carrying the joint transport data payload) in an 802.3 (Ethernet) frame and sends it to the slave AP on the Ethernet link. If encryption is to be used, then (multiple) encrypted frames are encapsulated.

[0090] When Ethernet frames are used to exchange AP coordination information between APs, EtherType 89-0d frames can also be used to encapsulate AP coordination action frames, such as to establish or tear down an AP coordination session. In this case, the Payload field is set to "AP Coordination" and the EtherType 89-0d frame payload carries the AP Coordination Action frame. In this case, the "AP Coordination Packet Type" field is set to AP Coordination Action Frame (set to 3, such as Figure 6 ), and the packet content field carries the AP coordination action frame while other fields in the payload are omitted.

[0091] The destination address in the MAC header ensures that the slave AP does not immediately forward the received JT data frame to the target STA. For example, the subfield is set to the MAC address of the slave AP instead of the MAC address of the target STA.

[0092] In a wired or hybrid backhaul scenario, transmissions to different slave APs may not be synchronized in time and may occur at the same time or at different times. The JT packet ID is used to synchronize the joint transmission content.

[0093] Fig.12 A trigger frame 1200 for a joint transmission to a target STA is shown according to an example embodiment.

[0094] The joint transmission trigger frame 1200 includes an AP coordination session ID 1210. The session ID is included in the JT trigger frame to indicate which joint transmission session is being triggered. Based on the session ID, the slave AP receiving the JT trigger frame retrieves the common parameters negotiated during the session establishment. Unless the master AP explicitly overrides any parameters, such pre-negotiated parameters are omitted in the JT trigger frame. The overhead of joint transmission control signaling on the wireless medium is reduced.

[0095] In addition, if all slave APs corresponding to the session ID are involved in the joint transmission, the slave AP MAC address field can be skipped. If the target STA is obvious from the session ID, the destination MAC address field can also be skipped.

[0096] Fig.13 A communication exchange 1300 is shown in which a master AP does not participate in a joint transmission, according to an example embodiment.

[0097] As mentioned before, in some cases, the master AP may not participate in the actual joint transmission phase, and only the slave AP may participate in the joint transmission. This may happen when the master AP is implemented as a central controller and is far away from the target STA, or the master AP may not even be an actual AP but may be a multi-AP controller device in the core network. In this case, the target STA is associated with one of the slave APs instead of the master AP. Communication between the slave AP and the master AP, including the JT trigger frame, may occur on a wired backhaul (such as Ethernet). When there is no wireless link between the master AP and the slave AP, even the JT trigger frame is encapsulated in an Ethernet frame. Due to the strict time synchronization requirements of the joint transmission, and due to the fact that the JT trigger frame is used for time synchronization between slave APs, the JT trigger frame can only be transmitted using a wired backhaul when it can be guaranteed that all participating slave APs receive the JT trigger frame at the same time. In this case, the payload field is set to "AP Coordination" and the Ethernet type 89-0d frame payload carries the JT trigger frame. In this case, the "AP Coordination Packet Type" field is set to the JT trigger frame (set to 4, such as Figure 6 ), and the packet content field carries the JT trigger frame while omitting other fields in the payload. This deployment eliminates the restriction that the slave AP must be within the wireless range of the master AP and enables larger-scale joint transmissions, where the master AP at a centralized location can remotely manage joint transmissions of multiple physical locations. However, if it cannot be guaranteed that all participating slave APs receive the JT trigger frame at the same time, the JT trigger frame will be transmitted on the wireless medium.

[0098] In the case where the target STA is not associated with the master AP, the master AP may not know the value to be used for the sequence control field, or the CCMP packet number (PN) generated locally by the slave AP. For example, if the target STA is associated with slave AP1, before the data distribution phase 1320, the master AP initiates the information query phase 1310 and queries the slave AP1 for the next sequence control to be used, and optionally the CCMP packet number (PN) and the encryption key ID for transmission to the target STA. If the entire MPDU is distributed to the slave AP, the master AP uses the query information to set the various fields of the encapsulated JT data, or if the MPDU for joint transmission is generated locally by the slave AP, the information is distributed to the slave AP.

[0099] At some point in time before the data distribution phase 1320, the master AP also arranges for the upper layer data to be routed through itself instead of through slave AP1. This can be done by temporarily updating the routing table of the network router device that forwards the data payload to the AP so that the master AP is recorded as the serving AP for the target STA.

[0100] During the data distribution phase 1320, the master AP sets the MAC header fields of the encapsulated JT data so that the data appears to be generated by slave AP1 associated with the target STA, for example, the Address 2 (TA) field of the MPDU of the joint transmission is set to the MAC address of slave AP1. In addition, the sequence number subfield in the sequence control field of the MPDU (of the JT data) is used as an implicit JT identifier, so an explicit JT packet ID is not assigned to the JT data. During the joint transmission phase 1330, the master AP still initiates the joint transmission by sending a JT trigger frame, however only the slave AP participates in the actual joint transmission. To the target STA, the transmission appears to be initiated by slave AP1.

[0101] Fig.14 An action frame 1400 used by an AP to collect information from another AP during an information inquiry phase is shown according to an example embodiment.

[0102] The AP coordination information request frame includes a request information bitmap indicating information about slave AP parameters for the target STA requested by the master AP. The slave AP reports the requested information to the master AP using an AP coordination information response frame, including information indicated by the report information bitmap.

[0103] Although the master AP can initiate the request, the slave AP may also initiate the request. The AP coordination information request frame 1410 includes a request information bitmap, which indicates information about the receiving AP parameters for the target STA requested by the sending AP. The receiving AP uses the AP coordination information response frame 1420 to report the requested information to the requesting AP, and the included information fields are indicated by the report information bitmap. If a bit in the report information bitmap is set to 1, the corresponding field is included in the AP coordination information response frame 1420, otherwise it does not exist.

[0104] Fig.15 A frame 1500 for data sharing from a master AP to a slave AP is shown according to an example embodiment.

[0105] Instead of encapsulating the entire MAC layer frame (MPDU or A-MPDU), the master AP encapsulates only the upper layer data payload, also known as the MSDU (MAC Service Data Unit), and other relevant fields of the MAC header within the payload field of the Ethernet type 89-0d frame body. If multiple data payloads are included, the sequence control field and the CCMP header (if included) carry the starting sequence number (SN) and the packet number (PN), respectively. Based on this, each slave AP generates the MPDUs or A-MPDUs to be sent jointly. If necessary, encryption of the data is performed by each slave AP.

[0106] The MAC header is created by the slave AP for the locally generated MPDU using a copy of the Frame Control, Duration / ID, QoS Control, and HT Control fields. Optionally, some or all of these fields may also be distributed during the JT session setup if they remain the same throughout the JT session.

[0107] The CCMP Header field 1510 is present if the "Protect Frame" bit in the Frame Control field 1520 is set. The CCMP Header field 1510 carries the Packet Number (PN) that will be used to encrypt the first MPDU of subsequent MPDUs using sequentially increasing PNs.

[0108] The sequence control field 1520 carries the sequence number (SN) for the locally created A-MPDU. This is used as the starting SN for the first MPDU and is sequentially incremented for subsequent MPDUs in the A-MPDU.

[0109] The packet content field 1530 carries only the payload of the higher layer (also called MSDU). Each slave AP appends a locally generated MAC header to the payload of the higher layer to generate an MPDU for joint transmission.

[0110] Fig.16 A JT data frame 1600 is shown as an aggregated MAC protocol data unit (A-MPDU) according to an example embodiment.

[0111] Each slave AP generates a joint transmission data frame 1600 locally and stores it in a memory. For example, each slave AP generates an MPDU or A-MPDU to be jointly transmitted based on information 1602 received from the master AP. Fig.16 The arrows in mean that the fields are simply copied to the locally generated MPDU, except for some fields that need to be added. The first MPDU generated uses the sequence control field received from the master AP directly, while each subsequent MPDU increments the sequence number subfield within the sequence control field 1620 by one. The MPDU or A-MPDU can be generated and saved in memory immediately after receiving the encapsulated data from the master AP. If encryption is required (indicated by the "Protect Frame" bit in the frame control field 1610), each slave AP also encrypts the data payload, and generates a MIC and appends it to the payload. The first encrypted MPDU uses the CCMP header field received from the master AP directly, while each subsequent MPDU increments the PN subfield in the CCMP header field by one. The encrypted MPDUs are saved in memory, which is indexed by the JT packet ID 1630.

[0112] Alternatively, if the slave AP has a fast enough processor, the received MAC parameters and payload are kept in memory during the data distribution phase, and MPDU generation (and encryption, if required) may be done only after receiving the JT trigger frame.

[0113] exist Fig.16 In the locally created JT data frame 1600, the address 2 (TA) field 1622 in the MPDU is also copied by the corresponding address 2 (TA) field 1630 in the information 1602 received from the master AP. Depending on the AP associated with the target STA, the address 2 (TA) field 1630 is set to the MAC address of the master AP or to one of the MAC addresses of the slave AP. The remaining fields of each A-MPDU subframe (MPDU delimiter, padding, FCS, etc.) and EOF padding are locally generated. In addition, in the CCMP encrypted frame, if the "protected frame" bit in the frame control field 1610 is set, CCMP encryption is performed by the slave AP.

[0114] One benefit of frame 1600 is the reduction of overhead in data transfer via backhaul.

[0115] Fig.17 Frame 1700 is shown as an Aggregate MAC Protocol Data Unit (A-MPDU) for data sharing to a slave AP according to an example embodiment.

[0116] The master AP uses 802.11 data frame 1700 with a 4-address MAC header format to distribute JT data to the slave AP (without using Ethernet type 89-0d encapsulation). This distribution scheme can be used when the slave AP is associated with the master AP, such as in a Wi-Fi Easy Mesh deployment.

[0117] After receiving the joint transmission data from the master AP, the slave AP generates an MPDU to be jointly transmitted. The sequence number within the sequence control field 1734 in the MAC header of the generated MPDU 1730 is used as an implicit JT identifier.

[0118] Consider an example of a deployment in which the target STA is associated with a master AP and the master AP also participates in the actual joint transmission. The master AP sends an A-MPDU 1700 to the slave AP to distribute JT data. Each data frame within the MPDU of the A-MPDU uses a four-address MAC header format, and the frame body of the MPDU 1710 carries the actual data payload 1720 to be sent jointly (encrypted if necessary and including the CCMP header field and the MIC field). In this case, the JT data refers to the data payload 1720 (encrypted if necessary and including the CCMP header field and the MIC field). Since the final destination of the data payload 1720 is not the slave AP, both the "to DS" and "from DS" bits in the frame control field 1712 are set to 1 to distinguish transmissions from the AP to the STA or from the STA to the AP. The HE control field 1714 is also enhanced for EHT use, and a new control ID is defined for AP coordination. The control field can be used to carry control signals for various multi-AP coordination schemes, and the AP coordination type 1716 indicates the coordination scheme and can be set to Fig.10 One of the values ​​in Table 1020, for example, is set to 2 for joint transmission in which case the subsequent fields of the HE Control field are used to carry the JT Sequence Control 1718. The JT Sequence Control field 1718 carries the Sequence Control field 1734 of the actual MPDU to be jointly transmitted.

[0119] After receiving the A-MPDU 1710 carrying the HE control field 1714 for AP coordination from the master AP, the addressed slave AP (i.e., indicated by address 1 (RA)) generates an MPDU or A-MPDU to be jointly transmitted based on the information received from the master AP, instead of forwarding the A-MPDU to the target STA (indicated by address 3 (DA)). The generated MPDU 1730 is an 802.11 data frame using a three-address MAC header format.

[0120] exist Fig.17, the arrows indicate that the fields are copied from the received MPDU to the generated MPDU, except that in the generated MPDU, the "To DS" bit in the Frame Control field 1732 is set to 0 and the "From DS" bit is set to 1. The Sequence Control field 1734 of the generated MPDU is copied from the JT Sequence Control 1718 received from the master AP. The Duration field, Address 2 (TA) field, and QoS Control field are copied without any modification, while the Address 3 (DA) field is copied to the Address 1 (RA) field and the Address 4 (SA) field is copied to the Address 3 (SA) field in the generated MPDU. The HE Control field carrying the JT Sequence Control field is omitted from the generated MPDU. The frame body of the generated MPDU is copied directly from the MPDU 1710 as received from the master AP (i.e., without any further processing). However, the FCS field 1738 is generated locally by the slave AP. If the data payload 1720 is encrypted, an important aspect to note here is that CCMP encryption is performed for consumption by the target STA, so the MAC header parameters used for encryption are based on the MAC header fields included in the actual MPDU 1730 sent jointly, rather than based on the MAC header fields of the MPDU 1710. Specifically, during the CCMP encapsulation process, the master AP uses the frame control field 1732, address 1 (RA) field 1740, address 2 (TA) field 1742, address 3 (SA) field 1744, sequence control field 1746, and QoS control field 1748 as generated by the slave AP to construct the additional authentication data (AAD) for CCMP encryption. The address 4 field is not included in the AAD. The CCMP header fields, the encrypted data payload 1720, and the generated MIC are included in the frame body of the MPDU 1710 and are copied directly from the AP to the frame body of the MPDU 1730 without further processing. This significantly reduces the processing overhead associated with encryption for the slave AP.

[0121] The MPDU or A-MPDU may be generated by the slave AP and saved in memory when data is received from the master AP. The MPDU is saved in memory indexed by the sequence number subfield of the sequence control field 1734. Alternatively, if the slave AP has a fast enough processor, the received MPDU / A-MPDU is saved in memory without any modification during the data distribution phase, and the MPDU generation (for joint transmission) may be completed only after the JT trigger frame is received.

[0122] Fig.18 A joint transmission trigger frame 1800 is shown according to an example embodiment.

[0123] The JT trigger frame includes a list of sequence numbers of the MPDUs to be sent jointly. If necessary, an A-MPDU is constructed from the saved MPDUs from the AP.

[0124] The sequence number subfield in the sequence control field of the MPDU (JT data), e.g. Fig.16 1620 or Fig.17 1732 in the JT trigger frame 1800 is used as an implicit JT identifier. This allows the primary AP to more flexibly select the content of the JT data during the actual joint transmission (by indicating a specific sequence number in the sequence number information field 1810 in the JT trigger frame 1800).

[0125] For example, such flexibility may be performed during a joint retransmission where only failed MPDUs are retransmitted. The sequence number information field 1810 identifies the MPDUs to be transmitted jointly. The bits set to 1 in the sequence number bitmap subfield indicate the sequence number of the MPDU to be included, where the first bit (n=1) in the bitmap corresponds to the starting sequence number (SSN) subfield and the nth bit corresponds to (SSN+n–1).

[0126] Fig.19 is an example of a distributed MU-MIMO joint transmission 1900 to two STAs both associated with a primary AP according to an example embodiment.

[0127] Numbers 1910 and 1912 show data distribution to slave APs. JT data is distributed to slave APs with destinations STA1 and STA2, respectively. For example, JT data 1910 and 1912 may be Fig.17 A-MPDU 1700 in. After receiving JT data 1910 and 1920, the slave AP can generate an MPDU 1730 for joint transmission by copying the necessary fields from the received JT data. The slave AP can also aggregate the locally generated MPDUs into a single A-MPDU and save the A-MPDU in a designated local buffer. Number 1914 shows a joint transmission trigger frame for initiating a joint transmission to a target STA. The JT trigger frame 1914 initiates a MU joint transmission using two spatial streams. Number 1920 shows a joint transmission to STA1: S.N1–5 to STA1 using spatial stream 1. Number 1922 shows a joint transmission to STA2: S.N11–15 to STA2 using spatial stream 2. 1920 and 1922 occur simultaneously but use different spatial streams.

[0128] Fig. 20 is an example of an electronic device 2000 according to an example embodiment.

[0129] The electronic device 2000 includes a power source 2010, a memory 2020, a central processing unit (CPU) 2030, an auxiliary storage 2040, and a wireless I / F 2050 (including a transmitter and / or a receiver). The wireless I / F 2050 includes a MAC 2052 and a PHY 2060 that communicate with an antenna 2070. The MAC 2052 also includes a JT identification generator 2054, a JT data buffer 2056, and a JT data encapsulation / decapsulation 2058.

[0130] Consider an example embodiment in which the electronic device 2000 is an AP such as a master AP or a slave AP (note that the JT identification generator 2054 is only present in a master AP).

[0131] The electronic device 2000 includes a circuit that operates to generate a frame including JT data and a JT identifier that uniquely identifies the JT data. For example, the JT identifier generator block 2054 is responsible for generating a JT identifier corresponding to the JT data distributed to the slave AP. The JT data encapsulation / decapsulation block 2058 is used by the master AP to encapsulate the JT data in an 802.11 data frame or an 802.3 Ethernet frame during the data distribution phase. The slave AP uses this block to decapsulate the JT data received from the master AP. The JT data buffer 2056 stores the JT data for joint transmission. In the master AP, this may not be a separate buffer, but a shared buffer that stores all outgoing data frames. In the slave AP, this may be a separate buffer that is exclusively used to store data frames to be used for joint transmission. The electronic device 2000 also includes circuits, such as a wireless transmitter and / or antenna 2070, which enables the AP to send data frames to one or more communication devices, such as one or more STAs in a wireless network.

[0132] The present disclosure can be implemented by software, hardware, or software in collaboration with hardware. Each functional block used in the description of each of the above embodiments can be partially or fully implemented by an LSI such as an integrated circuit, and each process described in each embodiment can be partially or fully controlled by the same LSI or a combination of LSIs. The LSI can be formed as a chip alone, or a chip can be formed to include some or all of the functional blocks. The LSI may include data inputs and outputs coupled thereto. According to the difference in integration, the LSI may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI. However, the technology for implementing an integrated circuit is not limited to LSI, and can be implemented by using a dedicated circuit, a general-purpose processor, or a dedicated processor. In addition, an FPGA (field programmable gate array) that can be programmed after manufacturing the LSI or a reconfigurable processor in which the connection and setting of the circuit unit inside the LSI can be reconfigured can be used. The present disclosure can be implemented as digital processing or analog processing. If future integrated circuit technology replaces LSI due to the advancement of semiconductor technology or other derivative technologies, future integrated circuit technology can be used to integrate functional blocks. Biotechnology can also be applied.

[0133] The present disclosure may be implemented by any kind of device, apparatus or system having a communication function, which is referred to as a communication device.

[0134] The communication device may include a transceiver and a processing / control circuit. The transceiver may include and / or function as a receiver and a transmitter. The transceiver as a transmitter and a receiver may include an RF (radio frequency) module, which includes an amplifier, an RF modulator / demodulator, etc., and one or more antennas.

[0135] Some non-limiting examples of such communication devices include phones (e.g., cellular (mobile) phones, smart phones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital cameras / camcorders), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, digital book readers, telehealth / telemedicine (remote health and medicine) devices, and vehicles that provide communication capabilities (e.g., cars, airplanes, ships), and various combinations thereof.

[0136] The communication devices are not limited to portable or mobile, and may also include any type of device, equipment, or system that is non-portable or fixed, such as smart home devices (e.g., home appliances, lighting devices, smart meters, control panels), vending machines, and any other "things" in an "Internet of Things (IoT)" network.

[0137] Communications may include exchanging data through, for example, cellular systems, wireless LAN systems, satellite systems, etc., and various combinations thereof.

[0138] The communication device may include a device such as a controller or a sensor that is coupled to a communication device that performs the communication functions described in the present disclosure. For example, the communication device may include a controller or a sensor that generates a control signal or a data signal that is used by the communication device that performs the communication functions of the communication device.

[0139] The communication device may also include infrastructure such as base stations, access points, and any other device, equipment, or system that communicates with or controls devices such as the non-limiting examples above.

[0140] It should be understood that, although some features of the various embodiments have been described with reference to an apparatus, the corresponding features also apply to the method of the various embodiments, and vice versa.

[0141] Those skilled in the art will appreciate that, without departing from the spirit or scope of the present disclosure as broadly described, various changes and / or modifications may be made to the present disclosure as shown in the specific embodiments. Therefore, the present embodiments should be considered in all aspects as illustrative and not restrictive.

[0142] Other example embodiments include, but are not limited to, the following examples.

[0143] An example embodiment is an access point (AP) comprising: circuitry that generates a frame, a frame body of the frame including joint transmission (JT) data and a JT identifier that uniquely identifies the JT data; and a transmitter that sends the frame to one or more APs that jointly send the JT data to a communication device.

[0144] With the access point, the circuit generates a JT trigger frame including a JT identifier of the JT data, and the transmitter sends the JT trigger frame to one or more APs.

[0145] As with the access point, the JT trigger frame includes the MAC address of the communication device.

[0146] With this access point, JT data is carried as the payload of the EtherType 89-0d frame body.

[0147] With the access point, the frame is one of an IEEE 802.11 data frame and an Ethernet frame.

[0148] As with the access point, JT data is one or more MAC protocol data units (MPDUs) addressed to the communication device.

[0149] With the access point, the JT identity is one of a uniquely assigned JT packet ID, a value of a sequence number subfield within a sequence control field of an encapsulating IEEE 802.11 data frame, and a value of a sequence number subfield within a sequence control field of an MPDU in the JT data.

[0150] With the access point, the JT data has the higher layer payload and common fields required by the receiving AP to locally construct one or more MAC protocol data units (MPDUs) that are jointly sent to the communication device.

[0151] With the access point, JT data is carried as a payload of an IEEE 802.11 data frame using a four-address MAC header format; the MAC header of the IEEE 802.11 data frame includes a control field indicating a sequence control field of the IEEE 802.11 data frame to be jointly transmitted; and the JT identifier includes a value of a sequence number subfield within the sequence control field.

[0152] With the access point, the access point negotiates an AP coordination session with one or more APs, the AP coordination session specifies the AP coordination scheme as joint transmission, and the AP coordination session is identified by a session ID.

[0153] With the access point, after a fixed duration from the end of the JT trigger frame, the access point sends a PHY protocol data unit (PPDU) constructed from the JT data.

[0154] Another example embodiment is an access point (AP) including: a receiver that receives a frame including joint transmission (JT) data and a JT identification that uniquely identifies the JT data from the AP; and a local memory that stores the JT data and the JT identification.

[0155] With the access point, the receiver is also operative to receive a JT trigger frame with a JT identifier carrying JT data from the AP; the access point retrieves the JT data with a matching JT identifier from the memory and sends a physical layer protocol data unit (PPDU) constructed from the JT data after a fixed duration from the end of the JT trigger frame.

[0156] Another example embodiment is a communication method in which one or more access points (APs) jointly transmit to a communication device. The method includes: transmitting a frame from a first AP to one or more second APs, wherein a frame body of the frame includes joint transmission (JT) data and a JT identifier that uniquely identifies the JT data; and jointly transmitting the JT data from the one or more second APs to the communication device.

[0157] The method also includes synchronizing PHY and MAC parameters at the two or more transmitting APs so that transmission signals received by the communication device from the two or more transmitting APs are exactly the same.

Claims

1. An integrated circuit for an access point AP, the integrated circuit comprising: at least one input that inputs an electrical signal, and A controller circuit that controls: Encapsulating joint transmission JT data, and generating a frame including the encapsulated JT data and a JT identifier uniquely identifying the JT data; as well as sending the frame to one or more other APs that jointly send the JT data to the communication device, and sending a JT trigger frame including the JT identifier to the one or more other APs, It is characterized in that The encapsulated JT data and the JT identification in the JT Packet ID field are included in the frame.

2. The integrated circuit according to claim 1, wherein: The JT trigger frame includes the MAC address of the communication device.

3. The integrated circuit according to claim 1, wherein: The JT data is carried as the payload of the EtherType 89-0d frame body.

4. The integrated circuit according to claim 1, wherein: The frame is one of an IEEE 802.11 data frame and an Ethernet frame.

5. The integrated circuit according to claim 1, wherein: The JT data is one or more MAC protocol data units MPDUs addressed to the communication device.

6. The integrated circuit of claim 1, wherein: The JT identity is one of a uniquely assigned JT packet ID, a value of a sequence number subfield within a sequence control field of an encapsulating IEEE 802.11 data frame, and a value of a sequence number subfield within a sequence control field of an MPDU in the JT data.

7. The integrated circuit according to claim 1, wherein: The JT data has a high-layer payload and common fields required for a receiving AP to locally construct one or more MAC protocol data units MPDUs to be jointly sent to the communication device.

8. The integrated circuit of claim 1, wherein: The JT data is carried as a payload of an IEEE 802.11 data frame using a four-address MAC header format; the MAC header of the IEEE 802.11 data frame includes a control field indicating a sequence control field of the IEEE 802.11 data frames to be jointly transmitted; and the JT identifier includes a value of a sequence number subfield within the sequence control field.

9. The integrated circuit of claim 1, wherein: The control circuit controls negotiation of an AP coordination session with the one or more other APs, the AP coordination session specifies the AP coordination scheme as joint transmission, and the AP coordination session is identified by a session ID.

10. The integrated circuit of claim 1, wherein: The control circuit controls the transmission of a PHY protocol data unit PPDU constructed from the JT data after a fixed duration from an end of a JT trigger frame.

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