Data transmission method and apparatus, device, and system

Abstract

Provided are a data transmission method and apparatus, a device, and a system, relating to the technical field of optical communications. The method comprises: a master device determines a destination access point (AP) for a station that is about to roam, and the master device is connected to a plurality of slave devices by means of optical fibers; the master device buffers downlink packets of the station and stops sending the downlink packets of the station to a source AP; and upon receiving a service activation completion message sent by the destination AP, the master device sends the buffered downlink packets to the destination AP, wherein the source AP and the destination AP are any two slave devices. The present invention helps to prevent downlink packet loss caused by roaming handover.

Description

Data transmission methods, apparatus, equipment and systems

[0001] This application claims priority to Chinese Patent Application No. 202411642465.7, filed on November 15, 2024, entitled "Data Transmission Method, Apparatus, Device and System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical communication technology, and in particular to a data transmission method, apparatus, device and system. Background Technology

[0003] In wireless access scenarios, the coverage of a single access point (AP) is limited. In larger areas or areas with high network quality requirements, multiple APs are typically deployed to provide a unified wireless network access service. For example, in a home or office, a fiber-to-the-room (FTTR) network is deployed, where multiple FTTR devices provide a unified wireless network access service.

[0004] When multiple access points (APs) exist, a roaming handover may occur when a station (STA) moves. This means the STA disconnects from the source AP and establishes a connection with the destination AP. Before the roaming handover, the source AP sends downlink packets to the station, and after the handover is completed, the destination AP sends downlink packets to the station.

[0005] If the source AP has not sent all the downlink packets received from the station to the station before the roaming handover, the source AP will discard the unsent packets, resulting in the loss of downlink data for the STA. Summary of the Invention

[0006] This application provides a data transmission method, apparatus, device, and system that can reduce the possibility of data loss when a site roams between multiple access points (APs). The technical solution adopted is as follows:

[0007] Firstly, a data transmission method is provided, applied to a master device connected to multiple slave devices via optical fiber. The method includes: determining a destination AP for a site where roaming will occur; buffering downlink packets for the site and ceasing the transmission of downlink packets for the site to a source AP; and, upon receiving a service activation completion message from the destination AP, transmitting the buffered downlink packets for the site to the destination AP. The source AP and the destination AP are any two of the multiple slave devices.

[0008] In this application, after identifying the destination AP of a site where roaming is about to occur, the master device, while ceasing to send downlink packets destined for that site to the source AP, buffers the downlink packets intended for that site, effectively intercepting them. During this period, the source AP can continue to send downlink packets already received from that site to the site. Upon receiving a service activation completion message from the destination AP, indicating that the destination AP has established a connection with the site, the master device sends the buffered downlink packets to the destination AP, which then forwards them to the site. Because the master device prematurely stops sending downlink packets to the source AP, the likelihood of the source AP having already sent all received downlink packets to that site increases. After the source AP has sent all its downlink packets, the master device can then send the buffered downlink packets, ensuring continuous transmission of downlink packets to that site. This helps avoid downlink packet loss due to roaming handover and improves the user's network experience.

[0009] Optionally, the method further includes: the master device receiving a retransmission message sent by the source AP, the retransmission message being a message indicating that the source AP failed to send the message to the site; then, after receiving a service activation completion message sent by the destination AP, the master device sends the retransmission message to the destination AP, and the destination AP sends the retransmission message to the site.

[0010] After determining the destination AP of a site, the master device intercepts downlink packets destined for that site. Since downlink packets destined for that site that were already sent to the source AP before the destination AP was determined are no longer present in the master device, for packets that the source AP failed to send to the site (i.e., retransmission packets), the source AP must first send them to the master device, which then forwards them to the site through the destination AP, thereby improving the reliability of data transmission.

[0011] In one possible implementation, the service activation completion message includes a message type identifier field (hereinafter referred to as the message type field) and a message content field. The message type identifier field is used to indicate a roaming handover message (hereinafter referred to as a roaming message). The message content field includes an indication field, a medium access control (MAC) address field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The indication field is used to indicate that the type of the roaming handover message is a roaming handover completion status report. The roaming status field is used to indicate that the service has been activated, and the completion status field is used to indicate success.

[0012] In this implementation, the service activation completion message is jointly identified by the message type identifier field and the indication, roaming status, and completion status fields in the message content field. Roaming handover completion status reporting is one type of roaming handover message. The roaming status field indicates which stage of the roaming handover process the indication pertains to, and the completion status field indicates the actual completion status. Therefore, the service activation completion message can be jointly identified by the message type identifier field and the indication, roaming status, and completion status fields in the message content. During roaming handover, multiple roaming handover messages may exist. Further classification of these messages using certain fields in the message content field ensures a unified format for all roaming handover messages, facilitating FTTR equipment identification and retrieval of the information carried within the messages, thus improving identification efficiency. Furthermore, the MAC address field in the message content field carries the site's MAC address, which uniquely identifies the corresponding site.

[0013] In another possible implementation, the service activation completion message includes a message type identifier field and a message content field. The message type identifier field indicates that the service activation is complete, and the message content field carries the MAC address of the site. In this implementation, various roaming handover messages can be directly distinguished using the message type identifier field.

[0014] Optionally, the service activation completion message is a WLAN management and control interface (WMCI) message.

[0015] Optionally, the method further includes: the master device sending a roaming start indication message to the source AP, the roaming start indication message being used to indicate the start of roaming handover at the site. Based on the roaming start indication message, the source AP can determine the site where roaming is about to occur.

[0016] Optionally, the roaming start indication message can also be used to instruct the source AP to prioritize sending packets from the site. This can shorten the waiting time before initiating roaming handover and speed up the roaming handover process.

[0017] Optionally, the roaming start indication message includes a message type identifier field and a message content field. The message type identifier field indicates a roaming handover message. The message content field includes an indication field, a MAC address field, and a roaming status field. The indication field indicates that the roaming handover message is a roaming handover indication. The MAC address field carries the MAC address of the station. The roaming status field indicates the start of roaming. Here, a roaming handover indication is one type of roaming handover message, and the roaming status field indicates which stage of the roaming handover process it represents. It is evident that the roaming start indication message can be jointly identified by the message type identifier field, the indication field, and the roaming status field. During roaming handover, there may be multiple roaming handover messages. Further classification of roaming handover messages using certain fields in the message content field ensures a unified format for all roaming handover messages, facilitating FTTR equipment identification and obtaining the information carried in the roaming handover messages. Furthermore, the MAC address field in the message content field carries the MAC address of the station, which uniquely identifies the corresponding station.

[0018] Optionally, the roaming start indication message is a WMCI message.

[0019] Optionally, the method further includes: the master device receiving a transmission completion notification message sent by the source AP, the transmission completion notification message indicating that the source AP has sent the received downlink packets of the site to the site. After receiving the transmission completion notification message, the master device then begins the site roaming handover process, ensuring that the site roaming handover process occurs only after the source AP has completed sending all downlink packets for that site.

[0020] Optionally, the sending completion notification message carries the identifier of the site so that the master device can determine the site from which roaming handover can be initiated based on the site identifier.

[0021] Optionally, the sending completion notification message is a WMCI message.

[0022] Optionally, the method further includes: receiving a service shutdown completion message sent by the source access point, the service shutdown completion message containing context information. By carrying the context information of the downlink packets sent by the source AP to the site in the service shutdown completion message, messages during the roaming handover process can be reused, reducing the number of interactive messages and saving network overhead.

[0023] Optionally, the context information includes at least one of the following: unicast packet number (PN) and packet sequence number (SN) context.

[0024] Optionally, the service termination completion message includes a message type identifier field and a media access control MAC address field, wherein the message type identifier field is used to indicate a roaming handover message. In this embodiment, various roaming handover messages can be directly distinguished through the message type identifier field.

[0025] Optionally, the service closure completion message includes a roaming status field. This roaming status field has multiple values: a value of 0 indicates roaming decision information collection, a value of 1 indicates roaming has begun, a value of 2 indicates roaming preprocessing, a value of 3 indicates service closure, and a value of 4 indicates service activation. The roaming status field defines specific values, each corresponding to a specific roaming stage, enabling the master device and access point to accurately perceive the current roaming status and take appropriate actions based on it.

[0026] Optionally, the service shutdown completion message is a Wireless Management and Control Interface (WMCI) message.

[0027] Optionally, the method further includes: the destination access point sending the downlink message to the station according to the unicast packet number. During roaming, the unicast packet number serves as an identifier for the data packet, helping the destination AP accurately identify the sending start point and order of the message. This prevents the duplicate transmission of messages successfully sent by the source AP and avoids omitting unsent messages cached by the master device, thus preventing data packet out-of-order delivery, loss, or duplication.

[0028] Furthermore, the unicast packet number, as part of the context information, enables the destination AP to quickly synchronize its communication status with the site. This means that the destination AP can send downlink packets directly from the correct location based on the unicast packet number without needing to renegotiate or request retransmission, thereby reducing downlink packet loss and handover delays during roaming and improving the user's network experience.

[0029] Optionally, the method further includes: determining the destination port corresponding to the destination access point based on the mapping relationship between the media access control MAC address of the site and the access point port.

[0030] Optionally, the method further includes: redirecting the cached downlink packets; sending the cached downlink packets of the site to the destination access point includes: sending the redirected downlink packets to the destination access point.

[0031] Optionally, redirecting the cached downlink packets includes modifying the destination port corresponding to the downlink packet to the destination port corresponding to the destination access point. By modifying the destination port corresponding to the downlink packet, the master device can redirect packets originally sent to the source access point to the destination access point, avoiding the waste caused by the transmission of packets on the old path, and ensuring that the station receives the cached data immediately after connecting to the destination access point, thereby reducing handover latency and packet loss rate.

[0032] Optionally, the method further includes: updating the MAC forwarding table of the master device upon receiving a service shutdown completion message sent by the source access point.

[0033] Optionally, updating the MAC forwarding table of the master device includes updating the port corresponding to the MAC address of the site in the forwarding table of the master device to the port corresponding to the destination access point. By updating the MAC forwarding table, the master device can immediately forward subsequent downlink packets through the new path, avoiding service interruption or packet delay due to outdated forwarding tables and reducing roaming handover time. Updating the MAC forwarding table has a similar effect to redirection; updating the MAC forwarding table applies to packet data other than cached downlink packets, while redirection applies to cached downlink packets.

[0034] Optionally, the method further includes: the master device sending a roaming end notification message to the source AP, the roaming end notification message indicating that the site has roamed from the source AP to the destination AP, i.e., the roaming handover has been completed. The master device sends the roaming end notification message to the source AP, so that the source AP sends a retransmission message to the master device based on the roaming end notification message.

[0035] Optionally, the roaming end notification message carries the identifier of the station. This allows the master device to determine the station from which roaming handover has been completed based on the identifier, and subsequently send downlink packets to that station via the destination AP.

[0036] Optionally, the roaming end notification message is a WMCI message.

[0037] Secondly, a data transmission method is provided, which is applied to a master device connected to multiple slave devices via optical fiber. The method includes: determining the destination AP of a site where roaming will occur, wherein the destination AP is the master device; buffering downlink packets of the site and stopping the transmission of downlink packets of the site to a source AP, wherein the source AP is one of the multiple slave devices; and, after completing service activation at the site, sending the buffered downlink packets of the site to the site.

[0038] The difference between this second aspect and the first aspect is that the master device and the destination AP are the same device. Therefore, it is not necessary to send a cached downlink packet to the destination AP after receiving the service activation completion message from the destination AP. Instead, the cached downlink packet of the site is sent to the site after the service activation of the site is completed. Other details can be found in the aforementioned first aspect.

[0039] Thirdly, a data transmission method is provided, applied to a master device, wherein the master device is connected to multiple slave devices via optical fiber. The method includes: determining the destination AP of a site where roaming will occur; caching downlink packets of the site and stopping sending downlink packets of the site to the site; and sending the cached downlink packets of the site to the destination AP after receiving a service activation completion message sent by the destination AP; wherein the destination AP is any one of the multiple slave devices.

[0040] The difference between this third aspect and the first aspect is that the master device and the source AP are the same device; therefore, there is no need to perform the message exchange steps between the source AP and the master device. Other details can be found in the first aspect mentioned above.

[0041] Fourthly, a data transmission device is provided. This data transmission device has the function of implementing the method described in the first aspect. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-described function.

[0042] Fifthly, a data transmission apparatus is provided. This data transmission apparatus has the function of implementing the method described in the second aspect. The function can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the aforementioned function.

[0043] Sixthly, a data transmission apparatus is provided. This data transmission apparatus has the function of implementing the method described in the third aspect. The function can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the aforementioned function.

[0044] In a seventh aspect, an optical communication device is provided, the optical communication device being used to perform any of the data transmission methods provided in the first, second, or third aspect.

[0045] Eighthly, a communication device is provided, including a processor and a communication interface, the communication interface being connected to the processor, wherein the processor is used to implement any of the data transmission methods provided in the first, second, or third aspects above.

[0046] Optionally, the processor may be one or more, and the processor may be a multi-core processor, and the memory may be one or more.

[0047] Optionally, the communication interface includes a transceiver.

[0048] Optionally, the communication device further includes a memory storing program code; the processor is configured to read and execute the program code stored in the memory to implement any of the data transmission methods provided by the first, second, or third aspects mentioned above.

[0049] Optionally, the memory may be integrated with the processor, or the memory may be separated from the processor.

[0050] In the specific implementation process, the memory can be a non-transitory memory, such as read-only memory (ROM), which can be integrated with the processor on the same chip or set on different chips. This application does not limit the type of memory or the way the memory and processor are set.

[0051] A ninth aspect provides a communication system comprising a master device and a plurality of slave devices, the master device being connected to the plurality of slave devices via optical fiber. The master device is used to implement any of the data transmission methods provided in the first, second, or third aspect described above.

[0052] In a tenth aspect, a computer-readable storage medium is provided, wherein a software program is stored therein, and the software program, when read and executed by one or more processors, can implement any of the data transmission methods provided in the first, second, or third aspects described above.

[0053] Eleventhly, a computer program (product) is provided, the computer program (product) comprising: computer program code, wherein when the computer program code is run by a computer device, the computer device executes any of the data transmission methods provided in the first, second, or third aspects described above.

[0054] In a twelfth aspect, a chip is provided, the chip including a processor and a communication interface connected to the processor. The processor is configured to execute instructions to cause the chip to perform any of the data transmission methods provided in the first, second, or third aspects described above. Attached Figure Description

[0055] Figure 1 is a schematic diagram of the system architecture for fiber to the home or fiber to the office.

[0056] Figure 2 is a schematic diagram of the FTTR system architecture;

[0057] Figure 3 is a schematic diagram of the management channel between the master and slave devices in an FTTR network;

[0058] Figure 4 is a schematic diagram of a site roaming in an FTTR network;

[0059] Figure 5 is a schematic diagram of a data transmission method provided in an embodiment of this application;

[0060] Figure 6 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0061] Figure 7 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0062] Figure 8 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0063] Figure 9 is a schematic diagram of a data transmission device provided in an embodiment of this application;

[0064] Figure 10 is a schematic diagram of another data transmission device provided in an embodiment of this application;

[0065] Figure 11 is a schematic diagram of a data transmission device provided in an embodiment of this application;

[0066] Figure 12 is a schematic diagram of the structure of an optical communication device provided in an embodiment of this application. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0068] Figure 1 is a schematic diagram of the system architecture for Fiber to the Home / Office (FTTH / O). As shown in Figure 1, the OLT connects to upstream network-side equipment (such as switches and routers) and connects to downstream optical network units (ONUs) via an optical distribution network (ODN). The ODN includes passive optical splitters for optical power distribution, a backbone fiber connecting the passive optical splitter and the OLT, and branch fibers connecting the passive optical splitter and the ONUs. When transmitting downlink signals, the downlink signal sent by the OLT is transmitted to each ONU through the splitter, and the ONU selectively receives the downlink data belonging to itself from the downlink signal. When transmitting uplink signals, the uplink signals sent by multiple ONUs are combined into a single optical signal by the splitter and transmitted to the OLT. The ONU is also called an optical network terminal (ONT).

[0069] Building upon FTTH / O, to address signal coverage issues (such as wireless local area network (WLAN) signals) in home or office networks, fiber optic cables can be extended further into the room. Optical terminal equipment providing WLAN signals is installed inside the room, thus reducing the distance between the user terminal and the wireless access point (AP) and improving signal quality. This technology is called Fiber to the Room (FTTR).

[0070] Figure 2 is a schematic diagram of the FTTR system architecture. As shown in Figure 2, the OLT in FTTH / O is deployed in the central computer room, and the ONU is deployed in homes or offices. The master device in the FTTR network acts as both an ONU in the FTTH network and an upstream device for the FTTR slave devices, managing the slave devices. The slave devices in the FTTR network can be deployed in various rooms of a home or office. The slave devices have the functions of an ONU and can also function as an AP to provide WLAN signals to STAs. Both the master and slave devices can connect to user terminals through the user network interface (UNI).

[0071] In an FTTR network, multiple slave devices can be deployed, each connected to the master device via an optical splitter. The master device can centrally manage and configure all slave devices. The master device can also be called a "master gateway," "master optical modem," or "master FTTR unit (or master fiber unit, MFU)," etc., while slave devices can be called "slave gateways," "slave optical modems," or "slave FTTR units (or sub-fiber units, SFU)," etc.

[0072] Optionally, the STA can be any type of terminal device, including but not limited to mobile phones, laptops, tablets, or wearable devices. Wearable devices include, but are not limited to, smartwatches, smart bracelets, virtual reality (VR) glasses, or VR headsets.

[0073] In Figure 2, the master device is connected to two slave devices, namely slave device 1 and slave device 2. However, this embodiment does not limit the number of slave devices connected to the master device; for example, there can be more than two or only one slave device.

[0074] Figure 3 is a schematic diagram of the management channel between the master and slave devices in an FTTR network. As shown in Figure 3, the master device manages the slave devices through the WLAN management and control channel (WMCC). The WMCC is a low-latency channel in the FTTR network that enables WLAN control and other functions between the master and slave devices, and is used to carry WLAN management and control interface (WMCI) messages.

[0075] WMCI messages are encapsulated in FTTR encapsulation method (FEM) frames and are used to manage and control the WLAN functions of slave devices. FTTR transceivers can identify the destination (destination device) of the WMCI message using the port ID in the FEM frame. The WMCI message structure is shown in Table 1 below.

[0076] Table 1 WMCI Message Encapsulation Format

[0077] The following is an explanation of each field in Table 1.

[0078] 1) Message Type ID

[0079] The Message Type ID is an 8-bit field used to indicate the type of message and define the semantics of the message content. When the master device receives an uplink message with an unsupported message type ID, it can ignore the message, including the SeqNo field. When the slave device receives a message with a reserved or unsupported message type ID, it can ignore the message.

[0080] In this embodiment of the application, the message type can be a roaming switching message.

[0081] 2) SeqNo

[0082] SeqNo is an 8-bit field containing a sequence number counter to ensure WMCC robustness. In the downlink direction, the SeqNo field is filled with the corresponding master device sequence number counter value. The master device maintains a separate sequence number counter for each slave device unicast and broadcast WMCI message stream. Each sequence number counter rolls from 255 to 1. A value of 0 is not used in the downlink direction.

[0083] In the uplink direction, when an uplink WMCI message is a response to a downlink message, the value of the SeqNo field is equal to the value of the SeqNo field in the downlink message. If the WMCI message is initiated by the slave device, then SeqNo = 0.

[0084] 3) Length and processing requirements

[0085] The message length and processing is a 2-byte field consisting of three fields: message priority, operation type, and message content length.

[0086] X (the most significant bit of the third byte): Indicates the priority of processing this message. When X=1, it indicates that the message has a high priority; when X=0, it indicates that the message has a low priority.

[0087] C: Used to indicate the operation type of the current message.

[0088] In the downlink direction, when C=1, the message indicates that the operation type is a parameter request type, requesting the slave device to send the output indicated by the Message type ID field; when C=0, the message indicates that the message is a parameter configuration type message, and the parameter type configured in the message is indicated by the Message type ID field.

[0089] In the uplink direction, when C=1, the operation type of the message is a scheduling request, requesting the master device to send the scheduling configuration indicated by the Message type ID field; when C=0, the message is a parameter reporting message or an alarm message, and the parameter or alarm type (response) reported by the message is indicated by the Message type ID field.

[0090] LL LLLL LLLL: This field indicates the length of the message content. The value range is 0 to 1023.

[0091] 4) Message content

[0092] The format of the message content field is related to the specific message. The message content includes two parts: the message mask and the parameter content.

[0093] The message mask consists of a 16-bit mask, as shown in Table 2.

[0094] Table 2 Message Masks

[0095] Each message type can carry up to 16 parameters.

[0096] The message content is filled in according to the order indicated by the parameter mask. For downlink GET or Request messages, the parameter mask represents the parameters that the master device wants to obtain.

[0097] 5) Message verification

[0098] The CRC field is used to check whether the message has been corrupted during transmission. The value of this field is generated by the CRC algorithm.

[0099] The message transmission mechanism between the master and slave devices is explained below.

[0100] Both the master and slave devices can actively send WMCI messages or respond to messages sent by the other.

[0101] Downlink messages are parameter request messages and configuration messages; uplink messages are parameter reporting messages, scheduling requests, and status alarm messages.

[0102] To maintain and ensure the normal operation of the WMCI channel, the master and slave devices periodically exchange messages. If the master or slave device does not receive a message from the other party within a certain period of time, the master or slave device can actively send a request message to request feedback from the other party. If feedback is received within a specific period of time, the WMCI channel can be considered to be working normally; otherwise, the WMCI channel can be judged to be faulty, and the slave device can reactivate the WMCI channel or exit the WMCI scheduling mode.

[0103] The format of the parameter request message is shown in Table 3 below.

[0104] Table 3

[0105] The Message type ID field identifies the type of the parameter request message, and the parameter mask field identifies the specific parameters to be obtained. The 7-N fields are invalid; upon receiving this message, the receiving side can provide the corresponding parameters as instructed.

[0106] The format of the configuration message is shown in Table 4 below.

[0107] Table 4

[0108] The Message type ID field identifies the type of the configuration message, the parameter mask field identifies the specific parameters to be configured, and the 7-N fields are filled in sequentially according to the valid parameter order.

[0109] The format of the parameter reporting message is shown in Table 5 below.

[0110] Table 5

[0111] The Message type ID field identifies the type of the reported message, the parameter mask field identifies the specific parameters to be reported, and the 7-N fields are filled in sequentially according to the valid parameter order.

[0112] The format of the status alarm messages mentioned above is shown in Table 6 below.

[0113] Table 6

[0114] The Message type ID field identifies the type of status alarm message, the parameter mask field identifies the specific parameters being reported, and the 7-N fields are filled in sequentially according to the valid parameter order.

[0115] In this embodiment, both the master device and the slave device can function as an access point (AP) to provide WLAN signals to the STA. The STA can roam between any two access points among the master device and multiple slave devices.

[0116] When a terminal moves within an FTTR network, the channel quality with its currently associated slave device deteriorates, necessitating roaming to a slave device with better channel quality to ensure service continuity. However, during roaming, the terminal needs to re-establish a connection on the new slave device, leading to service interruptions. To ensure timely and continuous roaming, a cooperative roaming control scheme using WMCI is employed. Roaming between slave devices involves service shutdown and startup delays.

[0117] The WMCI-based collaborative roaming solution mainly includes four aspects of processing: roaming configuration information synchronization, network information synchronization, terminal online processing, and terminal roaming processing.

[0118] Figure 4 illustrates STA roaming among multiple slave devices. As shown in Figure 4, before the STA joins, the master and slave devices are configured with the same Basic Service Set Identifier (BSSID) across the entire network. When the STA comes online for the first time, all master and slave devices sharing the same BSSID in the network receive the STA's initialization information and respond with corresponding response messages. In this case, online decision-making is required to determine the device the STA connects to. After the STA comes online, the master device can transmit the STA's key information to other devices, just as if connecting its own STA. The master and slave devices can synchronize user information, enabling fast roaming decisions and seamless roaming. After roaming decisions and context synchronization are completed, the STA switches from the source device to the target device.

[0119] In wireless LANs, seamless roaming provides users with a continuous and uninterrupted wireless network connection, ensuring stable and reliable network connectivity in homes, offices, and public places. From a user experience perspective, seamless roaming avoids network interruptions. Imagine a user enjoying a smooth online video or participating in an important online meeting, only to suddenly lose their internet connection as they move from one room or area to another—the user experience would be significantly diminished. Seamless roaming technology intelligently senses user movement and changes in signal strength, automatically switching to the optimal access point to avoid such interruptions and allow users to enjoy a consistently stable network connection.

[0120] In scenarios where a site roams between multiple access points (APs), downlink packet loss may occur. Therefore, this application provides a data transmission method to reduce site data loss due to roaming handover.

[0121] Figure 5 is a schematic diagram of data transmission according to an embodiment of this application. This method is applied to a communication system including multiple access points (APs), where each AP includes a master device and multiple slave devices. The master device and the multiple slave devices are connected via optical fibers. For example, the communication system shown in Figure 2 or Figure 4. As shown in Figure 5, the method includes:

[0122] In step 501, the master device determines the destination AP of the site where roaming will occur.

[0123] In some examples, the destination AP (or destination FTTR device) is any one of multiple slave devices; in this case, the destination AP can also be referred to as the destination slave device.

[0124] This step 501 can be referred to as roaming decision. For example, the master device can determine the destination AP based on the Received Signal Strength Indication (RSSI) of the site.

[0125] In some examples, the destination AP can be determined as follows: When the source AP detects that the RSSI of a site is below a first threshold, it reports a roaming trigger event to the master device. Upon receiving this roaming trigger event, the master device initiates the roaming decision process. The master device sends RSSI and load information requests to all connected slave devices, requesting all slave devices to report the site's RSSI information and their service load information. The slave devices respond with the relevant information (the site's RSSI information and their service load information) according to the master device's request. Based on the information from all slave devices, the master device completes its decision and selects an AP as the destination AP.

[0126] Optionally, the master device determines the destination AP based on the RSSI of the site sent by each AP. For example, the AP with the highest RSSI can be selected as the destination AP, or any AP with an RSSI difference greater than a second threshold can be selected as the destination AP. This application embodiment does not limit the specific rules for determining the destination AP. Furthermore, the master device can also select the destination AP by combining the site's RSSI information and the service load information of the slave devices. For example, the master device can select the AP with the lowest service load from among multiple APs whose RSSI is greater than a third threshold as the destination AP.

[0127] Before step 501, the master device can send downlink packets for the site to the source AP, and the source AP forwards the downlink packets to the site. Here, the source AP is another slave device besides the destination AP. Specifically, the source AP is the AP currently connected to the site, and it sends downlink data to the site before roaming handover. In this embodiment, the direction from the AP to the site is downlink, and the direction from the site to the AP is uplink.

[0128] In step 502, the master device caches the downlink packets of the site and stops sending downlink packets of the site to the source AP.

[0129] In this process, after receiving a roaming trigger event or determining the destination AP through roaming decisions, the master device caches downlink packets for that site and stops sending these cached downlink packets to the source AP. That is, the master device caches the received packets that need to be sent to that site, and the destination address in these packets is the address of that site. These downlink packets are sent to the master device by the OLT. Optionally, the packets can also be called data packets or data frames.

[0130] Optionally, Hostapd processing can be completed before buffering downlink packets. Hostapd processing refers to using the Hostapd software to convert the wireless network card into an access point (AP) or "soft AP" mode to handle wireless network connections and authentication. When the source AP is turned off, Hostapd can complete some cleanup tasks, such as deassociation negotiation with terminal devices and releasing wireless channel resources. These operations are likely to be time-consuming, and downlink packet buffering should only begin after they are completely processed. Otherwise, unprocessed connection remnants and newly buffered packets can overload the buffer, affecting roaming stability.

[0131] In step 503, the destination AP sends a service activation completion message to the master device.

[0132] This service activation completion message indicates that the destination AP has activated the service at that site. Correspondingly, the master device receives the service activation completion message sent by the destination AP.

[0133] In step 504, after receiving the service activation completion message sent by the destination AP, the master device sends the cached downlink packets of that site to the destination AP.

[0134] In step 505, the destination AP sends the received downlink message to the station.

[0135] In this embodiment, after identifying the destination AP of a site where roaming is about to occur, the master device, while ceasing to send downlink packets for that site to the source AP, caches the downlink packets intended for that site, effectively intercepting them. During this period, the source AP can continue to send the downlink packets it has already received from that site to the site. When the master device receives a service activation completion message from the destination AP, indicating that the destination AP has established a connection with the site, the destination AP will forward the cached downlink packets to the site after the master device sends them to the destination AP. Because the master device prematurely stops sending downlink packets for that site to the source AP, the likelihood of the source AP sending all the received downlink packets for that site increases. After the source AP has sent all the downlink packets for that site, the master device can then send the stored downlink packets, ensuring continuous transmission of downlink packets for that site. This helps avoid downlink packet loss due to roaming handover and improves the user's network experience.

[0136] Figure 6 is a schematic diagram of another data transmission method provided in an embodiment of this application. In the embodiment shown in Figure 6, the master device can be the master device in Figure 2 or Figure 4, and the source AP and destination AP can be any two slave devices in Figure 2 or Figure 4.

[0137] As shown in Figure 6, the method includes:

[0138] In step 601, the master device determines the destination AP of the site where roaming will occur.

[0139] For related details, please refer to step 501, which will not be repeated here.

[0140] In step 602, the master device caches the downlink packets of the site and stops sending downlink packets of the site to the source AP.

[0141] See step 502 for related details, which will not be repeated here.

[0142] In step 603, the master device sends roaming start indication messages to the source AP and the destination AP.

[0143] The roaming start indication message is used to instruct the source AP and the destination AP to begin roaming handover at this site. This application embodiment does not limit the name of the roaming start indication message; it can be modified to other names as needed.

[0144] Optionally, the roaming start indication message is a WMCI message, which can adopt the message format in Table 1 above.

[0145] In another possible implementation, the roaming start indication message may include a message type identifier field and a message content field. The message type identifier field identifies the message type as a roaming handover message. The message content field may carry a site identifier, which is used to uniquely identify a site. Optionally, the site identifier may be the site's MAC address or association ID (AID).

[0146] For example, the message content fields of the aforementioned roaming handover message include an indication field, a MAC address field, and a roaming status field. The indication field indicates that the type of the roaming handover message is a roaming handover indication, the MAC address field carries the MAC address of the site, and the roaming status field indicates which stage of the roaming handover process the roaming handover indication is in. In this embodiment, the roaming status includes, but is not limited to, roaming decision information collection, roaming start, roaming preprocessing, indication of service shutdown, and indication of service startup.

[0147] Here, the roaming status field is used to indicate the start of roaming. That is, in this embodiment, the message is determined to be a roaming start indication message based on the message type identifier field and the indication field and roaming status field in the message content field.

[0148] During roaming handover, there may be multiple roaming handover messages. By further classifying the roaming handover messages through some fields in the message content, the format of each roaming handover message is standardized, which makes it easier for FTTR devices to identify and obtain the information carried in the roaming handover messages, thereby improving identification efficiency.

[0149] In another possible implementation, the roaming start indication message includes a message type identifier field and a message content field. The message type identifier field indicates that the roaming start indication message is in effect, and the message content field carries the MAC address of the station. In this implementation, various roaming handover messages can be directly distinguished using the message type identifier field.

[0150] In one possible implementation, the roaming start indication message, in addition to instructing the source AP to initiate roaming handover at the site, also instructs the source AP to prioritize sending downlink packets already received from that site. For example, prioritizing sending means that if the source AP has also received downlink packets from other sites but has not received a roaming start indication message instructing the source AP to initiate roaming handover at those other sites, the source AP prioritizes sending downlink packets from those sites before sending downlink packets from other sites.

[0151] In this embodiment, the source AP performs roaming handover for that site after sending all the downlink packets it has received from the site. By prioritizing the transmission of the downlink packets already received from the site, the roaming handover process can be accelerated.

[0152] In another possible implementation, the roaming start indication message is used to instruct the source AP to begin roaming handover for that site. In this case, after receiving the roaming start indication message, the source AP sends the corresponding packets for each site in the normal sending order.

[0153] Optionally, the method provided in this embodiment further includes: the source AP and the destination AP sending roaming start confirmation messages to the master device. After receiving the roaming start confirmation messages from the source AP and the destination AP, the master device initiates the roaming preprocessing procedure. The master device sends a roaming preprocessing instruction message to the destination AP, and the destination AP receives the roaming preprocessing instruction message and initiates roaming preparation work. The roaming preprocessing instruction message may carry parameters required for roaming preprocessing. After completing roaming preprocessing, the destination AP sends a roaming preprocessing completion message back to the master device.

[0154] Optionally, the preprocessing of the target AP includes the following two possible scenarios:

[0155] (1) If the destination AP has already established an association with the user, the parameters passed in the roaming preprocessing instruction message are aggregation parameters. The destination AP can establish an aggregation with the site through the aggregation parameters passed by the master device.

[0156] (2) If the destination AP has not yet established an association with the user, the parameters transmitted in the roaming preprocessing instruction message are association and aggregation information. The destination AP can establish an association and aggregation relationship with the terminal through the association and aggregation information transmitted by the master device.

[0157] In step 604, after the source AP has finished sending the downlink packets received from the site, it transmits a sending completion notification message to the master device.

[0158] This transmission completion notification message indicates that all downlink packets from the stations in the source AP have been transmitted. Accordingly, the master device receives this transmission completion notification message.

[0159] For example, the source AP sets up a cache area for each site it serves to store the downlink packets for that site. When all downlink packets in the cache area corresponding to that site have been sent, it means that all downlink packets for that site in the source AP have been sent.

[0160] Optionally, the delivery completion notification message may include a message type and a site identifier. The message type indicates that the message is a delivery completion notification message. The site identifier is used to uniquely identify the site. Optionally, the site identifier can be the site's MAC address or AID.

[0161] For example, the format of the sending completion notification message can be the format in Table 1 above.

[0162] In one possible implementation, the message type ID field is used to indicate a completion notification message. The message content field is used to carry the site identifier. For example, the message content field includes an STA MAC field, which carries the MAC address of the STA. Optionally, the STA MAC field can be 6 bytes long.

[0163] In another possible implementation, the message type ID field is used to indicate a roaming handover message. The roaming handover message is identified as a delivery completion notification message by a combination of fields in the message content field.

[0164] In one possible implementation, the sending completion notification message may be the aforementioned roaming start confirmation message, or it may be another message other than the aforementioned roaming start confirmation message.

[0165] In step 605, the master device sends a service shutdown instruction message to the source AP.

[0166] The service shutdown instruction message is used to instruct the source AP to shut down the services at the site.

[0167] Accordingly, the source AP receives the service shutdown instruction message and shuts down the service at the site according to the message. After the source AP successfully shuts down the service, it proceeds to step 606.

[0168] For example, the service shutdown instruction message is a WMCI message, which can adopt the message format in Table 1.

[0169] In one possible implementation, the service shutdown completion message includes a message type identifier field and a message content field. The message type identifier field is used to indicate a roaming handover message, and the message content field carries the MAC address of the site.

[0170] For example, the message content fields of the service shutdown completion message (the roaming handover message in the previous paragraph) include an indication field, a MAC address field, and a roaming status field. The MAC address field carries the MAC address of the site, the indication field indicates that the roaming handover message type is a roaming handover indication, and the roaming status field indicates that the service has been shut down. In this embodiment, the message is determined to be a service shutdown completion message based on the message type identifier field and the indication field and roaming status field in the message content field.

[0171] In another possible implementation, the service shutdown indication message includes a message type identifier field and a message content field. The message type identifier field is used to indicate the service shutdown indication message, and the message content field carries the MAC address of the site.

[0172] In step 606, the source AP sends a service shutdown completion message to the master device.

[0173] The "Service Closure Completed" message indicates that the services for the site have been shut down.

[0174] For example, the service shutdown completion message carries parameters to be synchronized. These parameters include the unicast packet number (PN), the serial number (SN) context, key update information, STA sleep state, and message sequence number, among other contextual information. By including parameters such as the unicast packet number and serial number context of the downlink messages sent by the source AP to the site in the service shutdown completion message, messages from the roaming handover process can be reused, reducing the number of interactive messages and saving network overhead.

[0175] Accordingly, the master device receives a message indicating that the service has been closed.

[0176] Optionally, the service closure completion message is a WMCI message, which can adopt the message format in Table 1.

[0177] In one possible implementation, the service shutdown completion message includes a message type identifier field and a message content field. The message type identifier field is used to indicate a roaming handover message, and the message content field carries the MAC address of the site.

[0178] For example, the message content fields of the service shutdown completion message (the roaming handover message in the previous paragraph) include an indication field, a media access control MAC address field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The indication field is used to indicate that the type of roaming handover message is roaming handover completion status reporting. The roaming status field is used to indicate that the service is shut down. The completion status field is used to indicate that the (service shutdown) was successful.

[0179] In other words, based on the message type identifier field and the indication field, roaming status field, and completion status field in the message content field, the message can be identified as a service closure completion message. During the roaming handover process, there may be multiple roaming handover messages. By further classifying the roaming handover messages using certain fields in the message content field, the format of each roaming handover message becomes uniform, making it easier for FTTR devices to identify and obtain the information carried in the roaming handover messages, thus improving identification efficiency.

[0180] In another possible implementation, the service shutdown completion message includes a roaming status field. This field has multiple possible values: 0 indicates roaming decision information collection, 1 indicates roaming has begun, 2 indicates roaming preprocessing, 3 indicates service shutdown, and 4 indicates service startup. The roaming status field defines specific values, each corresponding to a specific roaming stage, enabling the master device and access point to accurately perceive the current roaming status and take appropriate actions accordingly.

[0181] In another possible implementation, the service shutdown completion message includes a message type identifier field and a message content field. The message type identifier field indicates that the service shutdown is complete, and the message content field carries the site's MAC address. In this implementation, various roaming handover messages can be directly distinguished using the message type identifier field.

[0182] In another possible implementation, the destination AP sends downlink packets to the site based on the unicast packet number. During roaming, the unicast packet number serves as an identifier for the data packets, helping the destination AP accurately identify the start point and order of packet transmission. This prevents the retransmission of packets successfully sent by the source AP and avoids omitting unsent packets buffered by the master device, thus preventing out-of-order, lost, or duplicate data packets. Furthermore, as part of the context information, the unicast packet number allows the destination AP to quickly synchronize its communication status with the site. This means the destination AP can directly start sending downlink packets from the correct position based on the unicast packet number without renegotiating or requesting retransmissions, thereby reducing downlink packet loss and handover latency during roaming and improving the user's network experience.

[0183] In another possible implementation, the master device determines the destination port corresponding to the destination access point based on the mapping relationship between the site's Media Access Control MAC address and the access point port.

[0184] Optionally, the master device redirects the cached downlink packets; sending the cached downlink packets of the site to the destination access point includes sending the redirected downlink packets to the destination access point.

[0185] Optionally, redirecting cached downlink packets includes changing the destination port of the downlink packet to the destination port of the destination access point. By changing the destination port of the downlink packet, the master device can redirect packets originally destined for the source access point to the destination access point, avoiding the waste caused by the transmission of packets on the old path, and ensuring that the site receives the cached data immediately after connecting to the destination access point, thereby reducing handover latency and packet loss rate.

[0186] Optionally, the method provided in this embodiment further includes: updating the MAC forwarding table of the master device when a service shutdown completion message is received from the source access point.

[0187] Optionally, updating the MAC forwarding table of the master device includes updating the port corresponding to the MAC address of the site in the master device's forwarding table to the port corresponding to the destination access point. By updating the MAC forwarding table, the master device can immediately forward subsequent downlink packets through the new path, avoiding service interruptions or packet delays caused by outdated forwarding tables and reducing roaming handover time. Updating the MAC forwarding table has a similar effect to redirection; updating the MAC forwarding table applies to packet data other than cached downlink packets, while redirection applies to cached downlink packets.

[0188] In step 607, the master device sends a service activation instruction message to the destination AP.

[0189] The service activation instruction message is used to instruct the activation of services for the site.

[0190] Optionally, the service activation instruction message carries parameters to be configured, such as the aforementioned parameters to be synchronized. Accordingly, the destination AP receives the service activation instruction message, synchronizes the configuration parameters, and activates the service at that site. After the destination AP completes service activation according to the service activation instruction message, it executes step 608.

[0191] For example, the service activation instruction message is a WMCI message, which can adopt the message format in Table 1.

[0192] In one possible implementation, the service activation indication message includes a message type identifier field and a message content field. The message type identifier field is used to indicate a roaming handover message, and the message content field carries the MAC address of the site.

[0193] For example, the message content fields of the service activation indication message (the roaming handover message in the previous paragraph) include an indication field, a MAC address field, and a roaming status field. The MAC address field carries the MAC address of the site, the indication field indicates that the type of the roaming handover message is a roaming handover indication, and the roaming status field indicates that the service is activated. In this embodiment, the roaming handover message is determined to be a service activation indication message based on the message type identifier field and the indication field and roaming status field in the message content field.

[0194] In another possible implementation, the service activation indication message includes a message type identifier field and a message content field. The message type identifier field is used to indicate the service activation indication message, and the message content field carries the MAC address of the site.

[0195] In step 608, the destination AP sends a service activation completion message to the master device.

[0196] The "Service Activation Complete" message indicates that the services for the site have been activated.

[0197] Accordingly, the master device receives the service activation completion message sent by the destination AP, and the roaming handover ends.

[0198] Optionally, the service activation completion message is a WMCI message, which can adopt the message format in Table 1.

[0199] For example, the message content fields of a service activation completion message may include an indication field, a MAC address field, a roaming status field, and a completion status field. The MAC address field carries the site's MAC address, the indication field indicates that the roaming handover message type is a roaming handover completion status report, the roaming status field indicates that the service has been activated, and the completion status field indicates success.

[0200] In other words, this embodiment can determine that the message is a service activation completion message based on the message type identifier field and the indication field, roaming status field, and completion status field in the message content field. During the roaming handover process, there may be multiple roaming handover messages. By further classifying the roaming handover messages through some fields in the message content field, the format of each roaming handover message is unified, which facilitates the FTTR device to identify and obtain the information carried in the roaming handover message.

[0201] In another possible implementation, the service activation completion message includes a message type identifier field and a message content field. The message type identifier field indicates that the service activation is complete, and the message content field carries the site's MAC address. In this implementation, various roaming handover messages can be directly distinguished using the message type identifier field.

[0202] In this embodiment, the sending completion notification message and the service shutdown completion message are two different messages. In other embodiments, before shutting down the service of a site, the source AP can first send all downlink packets of that site, and then shut down the service of that site according to the service shutdown instruction message. In this way, step 604 can be omitted, and the service shutdown completion message in step 606 can be reused as a sending completion notification message, which serves to notify the master node that all downlink packets of that site have been sent.

[0203] In step 609, the master device sends the roaming end notification message to the source AP.

[0204] Accordingly, the source AP receives the roaming end notification message.

[0205] The roaming end notification message indicates that the site has roamed from the source AP to the destination AP, meaning that the roaming handover for the site has been completed.

[0206] Optionally, the roaming end notification message may include a message type and a site identifier. The message type indicates that the message is a roaming end notification message. The site identifier is used to uniquely identify the site. Optionally, the site identifier can be the site's MAC address.

[0207] For example, the roaming end notification message can be formatted as shown in Table 1 above. The message type ID field carries the message type. The message content field carries the station identifier. For example, the message content field includes a STA MAC field, which carries the MAC address of the STA. Optionally, the STA MAC field can be 6 bytes long.

[0208] In step 610, the source AP sends a retransmission message to the master device.

[0209] Optionally, this embodiment also includes a message retransmission scenario. The master device can receive retransmission messages sent by the source AP. The retransmission message is a message indicating that the source AP failed to send the message to the site.

[0210] It should be noted that step 610 is an optional step. If all messages sent by the source AP to the site are successfully sent, then step 610 does not need to be executed. Correspondingly, the step of the master device sending retransmission messages to the destination AP in step 611 does not need to be executed.

[0211] In step 611, the master device sends a retransmission message and a cached downlink message of the destination AP to the destination AP.

[0212] Accordingly, the destination AP receives retransmission messages and downlink messages from that station.

[0213] In some examples, the master device may send retransmission messages to the destination AP first, and then send the buffered downlink messages.

[0214] In step 612, the destination AP sends the received retransmission message and the downlink message of the station to the station.

[0215] After the retransmission message and the buffered downlink message are sent, the master device sends the downlink message received from that site to the destination AP after receiving the service shutdown completion message.

[0216] In this embodiment, the master device prioritizes sending downlink packets received and stored by the master device before the roaming handover to the destination AP, and then sends other downlink packets received by the master device from the site after the roaming handover. In this way, the site can receive downlink packets in the order they are arranged as much as possible.

[0217] In some examples, embodiments of this application apply to downlink packets for all services at the site. In other examples, embodiments of this application apply to downlink packets for a subset of services at the site, such as storing downlink packets for high-priority services or downlink packets for specific service types (e.g., packet loss-sensitive services). When embodiments of this application are applied to downlink packets for a subset of services, the destination AP only needs to store the downlink packets for that subset of services, which can reduce storage overhead.

[0218] In this embodiment, after identifying the destination AP of the site where roaming is about to occur, the master device stops sending downlink packets for that site to the source AP and instead caches the downlink packets for that site in the master device, effectively intercepting them. Furthermore, the source AP only begins roaming handover after sending all received downlink packets for that site to the site. Thus, the downlink packets cached by the master device include subsequent packets of the downlink packets sent by the source AP to the site. After the roaming handover is complete, the cached downlink packets are sent to the destination AP, ensuring that subsequent packets of the downlink packets sent by the source AP to the site are delivered to the site via the destination AP. The downlink packets sent to the site before and after the roaming handover process are continuous, which helps avoid downlink packet loss due to roaming handover and improves the user's network experience.

[0219] Furthermore, in this embodiment, after determining that a site is about to roam, the master device intercepts rather than backs up the downlink packets for that site. Therefore, the master device does not have the downlink packets for that site that have already been sent to the source AP. For packets that the source AP fails to send to the site (i.e., retransmission packets), the source AP can first send them to the master device, and then the master device can send them to the site through the destination AP, thereby improving the reliability of data transmission.

[0220] In the embodiment shown in Figure 6, the source AP sends a retransmission message to the master device only after the destination AP sends a roaming end notification message to the source AP through the master device. In other embodiments, the source AP may send the retransmission message to the master device after completing its actions during the roaming handover process, or after determining the retransmission message. In this case, the source AP may execute step 610 after step 604, 605, or 606, and omit step 609. In this way, the source AP can send the retransmission message to the master device as soon as possible, so that the master device can immediately send the retransmission message to the site after the roaming handover is completed.

[0221] In the embodiment shown in Figure 6 above, the master device first caches the downlink packets of the site, and then initiates the roaming preprocessing process (the master device sends a roaming preprocessing indication message to the destination AP). Optionally, the master device can also initiate the roaming preprocessing process after receiving the roaming start confirmation message. After receiving the roaming preprocessing completion message from the destination AP, the master device starts caching the downlink packets of the STA and stops sending the downlink packets of the STA to the source AP. The master device can send the cached downlink packets to the destination access point after receiving the service activation completion message from the destination AP. In this embodiment, the master device delays caching the downlink packets of the STA, which can save the cache space of the master device.

[0222] Figure 7 is a schematic diagram of another data transmission method provided by an embodiment of this application. The difference compared to the embodiment shown in Figure 6 is that in the embodiment shown in Figure 7, the master device and the destination AP are the same device, for example, the master device in Figure 2 or Figure 4. In this embodiment, the master device does not need to send a cached downlink packet to the destination AP after receiving the service activation completion message sent by the destination AP, but instead sends the cached downlink packet of the site to the site after completing the service activation of the site.

[0223] In this embodiment, the site is currently connected to the source AP. Due to site relocation or other reasons, a roaming handover process will be initiated. As shown in Figure 7, the data transmission method provided in this embodiment includes:

[0224] In step 701, the master device determines the destination AP of the site where roaming will occur.

[0225] For related details, please refer to step 501, which will not be repeated here.

[0226] In step 702, the master device caches the downlink packets of the site and stops sending downlink packets of the site to the source AP.

[0227] See step 502 for related details, which will not be repeated here.

[0228] In step 703, the master device sends a roaming start indication message to the source AP.

[0229] For related details, please refer to step 603, which will not be repeated here.

[0230] In step 704, after the source AP has finished sending the downlink packets received from the site, it sends a transmission completion notification message to the master device.

[0231] For related details, please refer to step 604, which will not be repeated here.

[0232] In step 705, the master device sends a service shutdown instruction message to the source AP.

[0233] For related details, please refer to step 605, which will not be repeated here.

[0234] In step 706, the source AP sends a service shutdown completion message to the master device.

[0235] For related details, please refer to step 606, which will not be repeated here.

[0236] In step 707, after the service activation of the site is completed, a roaming end notification message is sent to the source AP.

[0237] For related details, please refer to step 609, which will not be repeated here.

[0238] In step 708, the source AP sends a retransmission message to the master device.

[0239] For related details, please refer to step 610, which will not be repeated here.

[0240] In step 709, the master device sends the received retransmission message and the cached downlink message of the station to the station.

[0241] After the retransmission message and the buffered downlink message are sent, the master device sends the downlink message received from the site after the site's service is enabled to the site. It should be noted that step 708 is an optional step. If all messages sent from the source AP to the site are successfully sent, step 708 does not need to be executed. Correspondingly, the step of the master device sending the retransmission message to the destination AP in step 709 does not need to be executed.

[0242] Figure 8 is a schematic diagram of another data transmission method provided by an embodiment of this application. The difference between the embodiment shown in Figure 6 and the embodiment shown in Figure 8 is that the master device and the source AP are the same device, such as the master device in Figure 2 or Figure 4. The embodiment shown in Figure 8 may omit the interaction steps between the master device and the source AP.

[0243] In this embodiment, the site is currently connected to the master device (source AP). Due to site relocation or other reasons, a roaming handover process will be initiated. The data transmission method provided in this embodiment includes:

[0244] In step 801, the master device determines the destination AP of the site where roaming will occur.

[0245] See step 501 for related details, which are omitted here.

[0246] In step 802, the master device caches the downlink packets of the station and stops sending downlink packets to the station.

[0247] See step 502 for related details, which are omitted here. Since the master device and the source AP are the same device, the master device directly sends downlink packets to the site before roaming begins. Therefore, in this step, the master device stops sending downlink packets to the site.

[0248] In step 803, the master device sends a roaming start indication message to the destination AP.

[0249] See step 603 for related details, which are omitted here.

[0250] In step 804, the master device sends a service activation instruction message to the destination AP.

[0251] See step 607 for related details, which are omitted here.

[0252] In step 805, the destination AP sends a service activation completion message to the master device.

[0253] See step 608 for related details, which are omitted here.

[0254] In step 806, the master device sends a retransmission message and the downlink message of the site cached by the master device to the destination AP.

[0255] In this embodiment, the station determines whether there are any lost packets based on the sequence number carried in the received packets; and sends an acknowledgment message to the source AP based on the determination result. Since the master device and the source AP are the same device, the master device can determine the packets that failed to be sent based on the acknowledgment message, that is, determine the retransmission packets, without needing to obtain retransmission packets from other devices.

[0256] In step 806, the master device can first send a retransmission message to the destination AP, and then send the downlink message of the station stored by the master device.

[0257] In step 807, the destination AP sends the received retransmission message and the downlink message of the station to the station.

[0258] See step 612 for related details, which are omitted here.

[0259] The message content fields of the roaming switching messages in the aforementioned embodiments are illustrated below with reference to Tables 7 to 10.

[0260] Table 7. Roaming Switching Instructions and Reported Messages

[0261] The roaming handover instructions and reporting messages in Table 7 can be carried in the message content field of the WMCI messages in Table 1 above. Each roaming handover instruction and reporting message has different parameters, indicated by the parameter mask field in the message content field.

[0262] In the table above, the fields in the roaming handover indication and reporting messages are not mandatory; you can select the fields as needed. For example, the roaming handover indication message can include the fields in numbers 2-5 and 7-8; the roaming handover completion status reporting message can include the fields in numbers 2-8; the roaming handover exception handling message can include the fields in numbers 2-5 and 7-8; and the roaming handover exception handling status reporting message can include the fields in number 2-6.

[0263] Additionally, the payload field in roaming handover instructions and reporting messages can carry the following: <1> - <3> Any message in the [process].

[0264] <1> Roaming decision feedback information

[0265] Table 8. Roaming Decision Feedback Information

[0266] The roaming decision feedback information, once transmitted to the main device, can be used by the main device to make roaming decisions.

[0267] <2> Contextual information of roaming preprocessing

[0268] Table 9. Context Information for Roaming Preprocessing

[0269] The roaming preprocessing context information, after being sent to the destination AP, can be used by the destination AP for roaming preprocessing (see the above method embodiment for specific processing).

[0270] <3> Roaming feedback context information

[0271] Table 10: Roaming Feedback Context Information

[0272] After the roaming feedback context information is sent to the master device, the master device can synchronize it with the source AP, and the source AP can send downlink packets to the site based on this context information.

[0273] In addition, in the method embodiment shown in Figures 5-8, the messages transmitted between the master device, the source AP, and the destination AP can adopt the WMCI format described in Table 1, or further adopt the parameter request message and parameter reporting message formats in Table 3 or Table 5.

[0274] Figure 9 is a schematic diagram of a data transmission device provided in an embodiment of this application. This device can be formed as part or all of the aforementioned main device in a software, hardware, or a combination of software and hardware manner. As shown in Figure 9, the data transmission device 900 includes: a determination module 901, a buffer module 902, and a transceiver module 903.

[0275] The determining module 901 is used to determine the destination access point of the site where roaming will occur. The caching module 902 is used to cache the downlink packets of the site. The transceiver module 903 is used to stop sending the downlink packets of the site cached by the caching module to the source access point; and after receiving the service activation completion message sent by the destination access point, to send the cached downlink packets of the site to the destination access point. The source access point and the destination access point are any two of the plurality of slave devices.

[0276] Optionally, the transceiver module 903 is further configured to receive a retransmission message sent by the source access point, the retransmission message being a message indicating that the source access point failed to send the message to the site; and after receiving the service activation completion message, to send the retransmission message to the destination access point.

[0277] Optionally, the transceiver module 903 is further configured to send a roaming start indication message to the source access point, the roaming start indication message being used to indicate the start of roaming handover of the site.

[0278] Optionally, the transceiver module 903 is further configured to receive a transmission completion notification message sent by the source access point, the transmission completion notification message being used to indicate that the source access point has sent the received downlink message from the site to the site.

[0279] Optionally, the transceiver module 903 is further configured to send a roaming end notification message to the source access point, the roaming end notification message being used to indicate that the site has roamed from the source access point to the destination access point.

[0280] Figure 10 is a schematic diagram of a data transmission device provided in an embodiment of this application. This device can be formed as part or all of the aforementioned main device in the form of software, hardware, or a combination of both. As shown in Figure 10, the data transmission device 1000 includes: a determination module 1001, a buffer module 1002, and a transceiver module 1003.

[0281] The determination module 1001 is used to determine the destination access point of the site where roaming will occur, wherein the destination access point is the master device. The caching module 1002 is used to cache the downlink packets of the site and stop sending the cached downlink packets of the site to the source access point, wherein the source access point is any one of a plurality of slave devices connected to the master device via optical fiber. The transceiver module 1003 is used to stop sending the downlink packets of the site to the source access point, wherein the source access point is any one of a plurality of slave devices connected to the master device via optical fiber; and after the service activation of the site is completed, to send the cached downlink packets of the site to the site.

[0282] Optionally, the transceiver module 1003 is further configured to receive a retransmission message sent by the source access point, the retransmission message being a message indicating that the source access point failed to send the message to the site; and to send the retransmission message to the site after the service activation of the site is completed.

[0283] Optionally, the transceiver module 1003 is further configured to send a roaming start indication message to the source access point, the roaming start indication message being used to indicate the start of roaming handover of the site.

[0284] Figure 11 is a schematic diagram of a data transmission device provided in an embodiment of this application. This device can be formed as part or all of the aforementioned main device in a software, hardware, or a combination of both. As shown in Figure 11, the data transmission device 1110 includes: a determination module 1101, a buffer module 1102, and a transceiver module 1103.

[0285] The determining module 1101 is used to determine the destination access point of the site where roaming will occur. The destination access point is any one of a plurality of slave devices connected to the master device via optical fiber. The caching module 1102 caches the downlink packets of the site. The transceiver module 1103 is used to stop sending the downlink packets of the site cached by the caching module 1102 to the site; and after receiving a service activation completion message sent by the destination access point, to send the cached downlink packets of the site to the destination access point.

[0286] It should be noted that the data transmission device provided in the above embodiments is only illustrated by the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the data transmission device and data transmission method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process can be found in the method embodiments, which will not be repeated here.

[0287] The descriptions of the processes corresponding to the above-mentioned figures each have their own emphasis. For parts of a process that are not described in detail, please refer to the relevant descriptions of other processes.

[0288] This application also provides an optical communication device. Figure 12 is a schematic diagram of the structure of an optical communication device provided in an embodiment of this application. As shown in Figure 12, the optical communication device 1200 includes a processor 1204 and a communication interface 1208. The processor 1204 and the communication interface 1208 are connected, for example, through a bus 1202. It should be understood that this application does not limit the number of processors in the optical communication device 1200.

[0289] Bus 1202 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, only one line is used in Figure 12, but this does not imply that there is only one bus or one type of bus. Bus 1202 can include pathways for transmitting information between various components of the optical communication device 1200 (e.g., processor 1204, communication interface 1208).

[0290] The processor 1204 may include any one or more processors such as a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor (MP), or a digital signal processor (DSP).

[0291] The communication interface 1208 uses transceiver modules (e.g., optical modules) such as, but not limited to, transceivers to enable communication between the optical communication device 1200 and other devices or communication networks.

[0292] Optionally, the optical communication device also includes a memory 1206, and the processor 1204, memory 1206, and communication interface 1208 communicate via a bus 1202. It should be understood that this application does not limit the number of memories in the optical communication device 1200.

[0293] The memory 1206 may include volatile memory, such as random access memory (RAM). The processor 1204 may also include non-volatile memory, such as read-only memory (ROM), flash memory, hard disk drive (HDD), or solid state drive (SSD).

[0294] The memory 1206 stores executable program code, and the processor 1204 executes the executable program code to implement the functions of the aforementioned modules, thereby realizing the aforementioned data transmission method. That is, the memory 1206 stores instructions for executing the data transmission method.

[0295] This application also provides a computer program product containing instructions. The computer program product may be a software or program product containing instructions, capable of running on a computer device or stored on any usable medium. When the computer program product is run on at least one computer device, it causes the at least one computer device to perform the aforementioned data transmission method.

[0296] This application also provides a computer-readable storage medium. The computer-readable storage medium can be any available medium that a computer device can store, or a data storage device such as a data center containing one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive). The computer-readable storage medium includes instructions that instruct a computer device to perform the aforementioned data transmission method.

[0297] This application also provides a communication system including a master device and multiple slave devices connected via optical fiber. The master device and at least one slave device are used to implement the aforementioned data transmission method. The steps performed by the master device and the at least one slave device are determined by their roles in the method, including source AP, destination AP, and devices other than source AP and destination AP.

[0298] This application also provides a chip. The chip includes a processor and a communication interface, the communication interface being connected to the processor; the processor is used to execute instructions to cause the chip to perform the aforementioned data transmission method.

[0299] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The “multiple” mentioned in the embodiments of this application refers to two or more. A and / or B indicate three possibilities: A; B; and A and B.

[0300] The above description is merely an exemplary embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A data transmission method, characterized in that, Applied to a master device, wherein the master device is connected to multiple slave devices via optical fibers, the method includes: Determine the destination access point for the site where roaming will occur; Cache the downlink packets of the site and stop sending the downlink packets of the site to the source access point; After receiving the service activation completion message sent by the destination access point, send the cached downlink packets of the site to the destination access point; The source access point and the destination access point are any two of the plurality of slave devices.

2. The method according to claim 1, characterized in that, The method further includes: Receive a retransmission message sent by the source access point, wherein the retransmission message is a message indicating that the source access point failed to send the message to the station; After receiving the service activation completion message, the retransmission message is sent to the destination access point.

3. The method according to claim 1 or 2, characterized in that, The service activation completion message includes a message type identifier field and a message content field. The message type identifier field is used to indicate roaming switching messages; The message content fields include an indication field, a media access control MAC address field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The indication field is used to indicate that the type of roaming handover message is roaming handover completion status reporting. The roaming status field is used to indicate that the service has been started. The completion status field is used to indicate success.

4. The method according to any one of claims 1 to 3, characterized in that, The service activation completion message is a Wireless Management and Control Interface (WMCI) message.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: A roaming start indication message is sent to the source access point, the roaming start indication message being used to indicate the start of roaming handover for the site.

6. The method according to claim 5, characterized in that, The roaming start indication message is also used to instruct the source access point to prioritize sending messages from the site.

7. The method according to claim 5 or 6, characterized in that, The roaming start indication message includes a message type identifier field and a message content field, wherein the message type identifier field is used to indicate a roaming switch message; The message content fields include an indication field, a media access control MAC address field, and a roaming status field. The indication field indicates that the type of roaming handover message is a roaming handover indication. The MAC address field carries the MAC address of the site. The roaming status field indicates that roaming has started.

8. The method according to any one of claims 5 to 7, characterized in that, The roaming start indication message is a Wireless Management and Control Interface (WMCI) message.

9. The method according to any one of claims 1 to 8, characterized in that, The method further includes: The system receives a transmission completion notification message from the source access point, which indicates that the source access point has sent the received downlink message from the site to the site.

10. The method according to claim 7, characterized in that, The notification message indicating completion of delivery carries the identifier of the site.

11. The method according to claim 7 or 8, characterized in that, The transmission completion notification message is a Wireless Management and Control Interface (WMCI) message.

12. The method according to any one of claims 1 to 11, characterized in that, The method further includes: Receive a service shutdown completion message sent by the source access point, the service shutdown completion message containing context information.

13. The method according to claim 12, characterized in that, The context information includes at least one of the following: unicast packet number and data packet sequence number context.

14. The method according to claim 12 or 13, characterized in that, The service shutdown completion message includes a message type identifier field and a media access control MAC address field. The message type identifier field is used to indicate a roaming handover message.

15. The method according to any one of claims 12 to 14, characterized in that, The service closure completion message includes a roaming status field, which has multiple values: a value of 0 indicates roaming decision information collection, a value of 1 indicates roaming start, a value of 2 indicates roaming preprocessing, a value of 3 indicates service closure, and a value of 4 indicates service activation.

16. The method according to any one of claims 12 to 15, characterized in that, The service shutdown completion message is a Wireless Management and Control Interface (WMCI) message.

17. The method according to any one of claims 14 to 16, characterized in that, The MAC address field carries the MAC address of the site.

18. The method according to claim 13, characterized in that, The method further includes: A service activation instruction message is sent to the target access point, and the service activation instruction message carries the context information.

19. The method according to any one of claims 13 to 16, characterized in that, The method further includes: the destination access point sending the downlink message to the site according to the unicast packet number.

20. The method according to claim 1, characterized in that, The method further includes: Based on the mapping relationship between the media access control MAC address of the site and the access point port, the destination port corresponding to the destination access point is determined.

21. The method according to claim 20, characterized in that, The method further includes: Redirect the cached downlink packets; The sending of the cached downlink message of the site to the destination access point includes: Send a redirected downlink message to the destination access point.

22. The method according to claim 21, characterized in that, The redirection of the cached downlink packets includes: Modify the destination port corresponding to the downlink message to the destination port corresponding to the destination access point.

23. The method according to claim 12, characterized in that, The method further includes updating the MAC forwarding table of the master device upon receiving a service shutdown completion message sent by the source access point.

24. The method according to claim 23, characterized in that, The updated MAC forwarding table of the master device includes: Update the port corresponding to the MAC address of the site in the forwarding table of the master device to the port corresponding to the destination access point.

25. The method according to any one of claims 1 to 24, characterized in that, The method further includes: A roaming end notification message is sent to the source access point, the roaming end notification message indicating that the site has roamed from the source access point to the destination access point.

26. The method according to claim 25, characterized in that, The roaming end notification message carries the identifier of the site.

27. A data transmission method, characterized in that, Applied to a master device, wherein the master device is connected to multiple slave devices via optical fibers, the method includes: Determine the destination access point of the site where roaming will occur, wherein the destination access point is the main device; Cache the downlink packets of the site and stop sending the downlink packets of the site to the source access point, where the source access point is one of the plurality of slave devices; After the service activation of the site is completed, the cached downlink messages of the site are sent to the site.

28. The method according to claim 27, characterized in that, The method further includes: Receive a retransmission message sent by the source access point, wherein the retransmission message is a message indicating that the source access point failed to send the message to the station; After the service activation of the site is completed, the retransmission message is sent to the site.

29. The method according to claim 27 or 28, characterized in that, The service activation completion message includes a message type identifier field and a message content field. The message type identifier field is used to indicate roaming switching messages; The message content fields include a media access control MAC address field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The roaming status field is used to indicate that the roaming handover is complete. The roaming status field is used to indicate that the service has been started. The completion status field is used to indicate success.

30. The method according to any one of claims 27 to 29, characterized in that, The service activation completion message is a Wireless Management and Control Interface (WMCI) message.

31. The method according to any one of claims 27 to 30, characterized in that, The method further includes: A roaming start indication message is sent to the source access point, the roaming start indication message being used to indicate the start of roaming handover for the site.

32. The method according to claim 31, characterized in that, The roaming start indication message is also used to instruct the source access point to prioritize sending messages from the site.

33. The method according to claim 31 or 32, characterized in that, The roaming start indication message includes a message type identifier field and a message content field, wherein the message type identifier field is used to indicate a roaming switch message; The message content field includes a media access control MAC address field and a roaming status field, which are used to indicate roaming switching. The MAC address field carries the MAC address of the site, and the roaming status field is used to indicate the start of roaming.

34. The method according to any one of claims 31 to 33, characterized in that, The roaming start indication message is a Wireless Management and Control Interface (WMCI) message.

35. An optical communication device, characterized in that, The optical communication device is used to perform the method as described in any one of claims 1-33.

36. An optical communication device, characterized in that, The optical communication device includes a processor and a communication interface, wherein the processor and the communication interface are connected. The processor is configured to perform the data transmission method as described in any one of claims 1 to 26, or to perform the data transmission method as described in any one of claims 27 to 34.

37. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a software program that, when read and executed by one or more processors, implements the data transmission method as described in any one of claims 1 to 26, or implements the data transmission method as described in any one of claims 27 to 34.

38. A communication system, characterized in that, The communication system includes a master device and a plurality of slave devices, the master device and the plurality of slave devices being connected via optical fiber, the master device being used to perform the data transmission method as described in any one of claims 1 to 26; or, to perform the method as described in any one of claims 27 to 34.

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