Data transmission method and apparatus, device, and system

Abstract

The present application relates to the technical field of optical communications, and provides a data transmission method and apparatus, a device, and a system. The method comprises: a master device determining a destination AP of a station that will experience roaming, wherein the destination AP is any one of a plurality of slave devices; the master device or the destination AP caching a downlink packet of the station; the master device or the destination AP acquiring a sequence number of a downlink packet sent to the station by a source AP of the station; and once roaming handover is completed, sending the cached downlink packet according to the sequence number. This helps 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. 202411645252.X, 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 STA before the roaming handover, it will be unable to send packets to the STA after the handover is completed because the source AP has lost connection with the STA. In this case, the source AP will discard these 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. 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 (Access Point) at a site where roaming will occur, wherein the destination AP is any one of the multiple slave devices; buffering downlink packets of the site; obtaining the sequence number of a downlink packet sent from a source AP to the site; and, upon receiving a service activation completion message from the destination AP, sending the buffered downlink packet to the destination AP according to the sequence number.

[0008] In this application, before a site roams from a source AP to a destination AP, the master device pre-caches downlink packets for that site. Upon receiving a service activation completion message from the destination AP, i.e., after the site's roaming handover is complete, the master device sends the cached downlink packets to the destination AP based on the sequence number of the downlink packets sent by the source AP to the site. This ensures that the downlink packets sent to the site are continuous before and after the roaming handover, thereby reducing downlink packet loss during roaming and improving the user's network experience.

[0009] Optionally, obtaining the sequence number of the downlink message sent by the source AP to the site includes: receiving a service shutdown completion message sent by the source AP, the service shutdown completion message carrying the sequence number. This service shutdown completion message indicates that the source AP has shut down the service at the site. By carrying the sequence number of the downlink message 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.

[0010] Optionally, the method further includes: receiving message indication information sent by the source AP, the message indication information being used to instruct the source AP to send a failed message to the site; and after receiving a service activation completion message sent by the destination AP, sending the message indicated by the message indication information to the destination AP. By carrying message indication information in the service closure completion message, the master device can know that the source AP failed to send a failed message to the site, thereby sending the message indicated by the message indication information to the destination AP, improving the reliability of data transmission.

[0011] Optionally, the message indication information can indicate the message in either of the following two ways. First, the message indication information includes the sequence number of the retransmitted message. Second, the message indication information includes the sequence number of the starting message and a bitmap, where the bits in the bitmap are used to indicate whether a message following the starting message has been successfully transmitted. In this second method, the transmission status of multiple downlink messages can be indicated with fewer bits, which helps save network overhead.

[0012] Optionally, the service activation completion message is a WLAN management and control interface (WMCI) message.

[0013] 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 a first 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 first 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.

[0014] In this implementation, the service activation completion message is jointly identified by the message type identifier field and the first indication field, roaming status field, and completion status field 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 handover indication refers 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 first indication field, roaming status field, and completion status field in the message content. 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 retrieval of the information carried within the roaming handover messages. Furthermore, the MAC address field in the message content field carries the site's MAC address, which uniquely identifies the corresponding site.

[0015] 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.

[0016] Optionally, the service shutdown completion message is a WMCI message.

[0017] 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. The message content field includes a first indicator field, a media access control MAC address field, a second indicator field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The first indicator field is used to indicate that the type of the roaming handover message is a roaming handover completion status report. The second indicator field is used to carry the sequence number. The roaming status field is used to indicate that the service is shut down. The completion status field is used to indicate success.

[0018] In this implementation, the service closure completion message is jointly identified by the message type identifier field and the first indication field, roaming status field, and completion status field 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 handover indication refers to, and the completion status field indicates the actual completion status. Therefore, the service closure completion message can be jointly identified by the message type identifier field and the first indication field, roaming status field, and completion status field in the message content. 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 retrieval of the information carried within the roaming handover messages. Furthermore, the MAC address field in the message content field carries the site's MAC address, which uniquely identifies the corresponding site.

[0019] 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 a service startup completion message, 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.

[0020] Optionally, the method further includes: sending a roaming start indication message to the source AP and the destination AP, the roaming start indication message being used to indicate the start of roaming handover for the site. This roaming start indication message can notify the source AP and the destination AP to initiate the roaming handover process.

[0021] Optionally, the roaming start indication message is a WMCI message.

[0022] Optionally, the method further includes: sending a service shutdown instruction message to the source AP, the service shutdown instruction message being used to instruct the shutdown of the site's services; and sending a service activation instruction message to the destination AP, the service activation instruction message being used to instruct the activation of the site's services. Through the service shutdown instruction message and the service activation instruction message, roaming of a site from the source AP to the destination AP can be achieved.

[0023] Optionally, both the service shutdown instruction message and the service startup instruction message are WMCI messages.

[0024] 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: the master device determining the destination AP of a site where roaming will occur, the destination AP being the master device; buffering downlink packets of the site; obtaining the sequence number of a downlink packet sent to the site by a source AP, the source AP being any one of the multiple slave devices; and after completing service activation at the site, sending the buffered downlink packet to the destination AP according to the sequence number.

[0025] 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 is sent to the destination AP according to the sequence number after the service activation of the site is completed. Other details can be found in the aforementioned first aspect.

[0026] Thirdly, 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 a destination AP (Access Point) at a site where roaming will occur, wherein the destination AP is any one of the multiple slave devices; sending a downlink packet of the site to the destination AP; obtaining the sequence number of a downlink packet sent from a source AP to the site; and sending the sequence number to the destination AP.

[0027] Before a site roams from the source AP to the destination AP, its downlink packets are pre-sent to the destination AP, allowing the destination AP to back up and cache these packets. Furthermore, by obtaining the sequence number of the downlink packets sent from the source AP to the site and sending that sequence number to the destination AP, the destination AP can send the cached downlink packets after the roaming handover is complete. This ensures that downlink packets are sent continuously to the site before and after the roaming handover, reducing downlink packet loss during roaming and improving the user's network experience.

[0028] In one possible implementation, the source AP is one of multiple slave devices. Obtaining the sequence number of the downlink packets sent by the source AP to the site includes receiving a service shutdown completion message sent by the source AP, the service shutdown completion message carrying the sequence number. By carrying the sequence number of the downlink packets sent by the source AP to the site in the service shutdown completion message, messages during roaming handover can be reused, reducing the number of interactive messages and saving network overhead.

[0029] In another possible implementation, the source AP is the master device, and the source AP can obtain the sequence number of the downlink message sent to the station from the information it records.

[0030] Optionally, the service closure 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. The message content field includes a first indicator field, a media access control MAC address field, a second indicator field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The first indicator field is used to indicate that the type of roaming handover message is a roaming handover completion status report. The second indicator field is used to carry the sequence number. The roaming status field is used to indicate that the service is closed, and the completion status field is used to indicate success.

[0031] Compared to the service closure completion message in the first aspect, the service closure completion message in the third aspect also includes a second indication field for carrying the sequence number.

[0032] Optionally, sending the sequence number to the destination AP includes: sending a service activation indication message to the destination AP, the service activation indication message being used to indicate the activation of services at the site, and the service activation indication message carrying the sequence number. By carrying the sequence number of the downlink packets sent by the source AP to the site in the service deactivation indication message, messages during the roaming handover process can be reused, reducing the number of interactive messages and saving network overhead.

[0033] Optionally, 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. The message content field includes a first indication field, a MAC address field, a roaming status field, and a second indication field. The MAC address field carries the MAC address of the site. The first indication field indicates that the type of the roaming handover message is a roaming handover indication. The roaming status field indicates that the service is activated. The second indication field carries the sequence number. The service activation indication message is jointly identified by the message type identifier field and the first indication field and roaming status field in the message content field. Furthermore, the MAC address field in the message content field carries the MAC address of the site, which uniquely identifies the corresponding site.

[0034] Optionally, the method further includes: receiving message indication information sent by the source AP, the message indication information being used to instruct the source AP to send a failed message to the station; and sending the message indication information to the destination AP. After receiving the message indication information, the destination AP can retrieve the corresponding message from the cached downlink messages according to the message indication information and send it to the station, thereby improving the reliability of data transmission. The relevant content of the message indication information can be found in the first aspect described above, and will not be repeated here.

[0035] Optionally, the method further includes sending a roaming start indication message to the source AP and the destination AP, the roaming start indication message being used to indicate the start of roaming handover of the site.

[0036] Optionally, the method further includes: sending a service shutdown instruction message to the source AP, the service shutdown instruction message being used to instruct the shutdown of services at the site.

[0037] Fourthly, a data transmission method is provided, which is applied to a destination AP, where the destination AP is any one of a plurality of slave devices connected to a master device via optical fiber. The method includes: receiving and buffering downlink packets from a site sent by a master device, wherein the master device is connected to the plurality of slave devices via optical fiber; receiving a sequence number sent by the master device, wherein the sequence number is the sequence number of a downlink packet sent by a source AP to the site; and sending the buffered downlink packet to the site according to the sequence number.

[0038] Before a site roams from the source AP to the destination AP, the destination AP pre-caches downlink packets for that site. Furthermore, after the roaming handover is complete, the destination AP can send the cached downlink packets back to the site based on the sequence numbers of the downlink packets sent to the site by the source AP. Before and after the roaming handover, the downlink packets sent to the site are continuous, thereby reducing downlink packet loss during roaming and improving the user's network experience.

[0039] Optionally, receiving the sequence number sent by the master device includes: receiving a service activation indication message sent by the master device, the service activation indication message being used to indicate the activation of services at the site, the service activation indication message carrying the sequence number. The service activation indication message can be found in the third aspect.

[0040] Optionally, sending the cached downlink message to the site according to the sequence number includes: after the service activation of the site is completed, sending the cached downlink message to the site according to the sequence number.

[0041] Optionally, the method further includes: receiving message indication information sent by the master device, the message indication information being used to instruct the source AP of the site to send a failed message to the site; and sending the message indicated by the message indication information to the site. For details regarding the message indication information, please refer to the first aspect.

[0042] Optionally, the method further includes: sending a service activation completion message to the master device, the service activation completion message indicating that the service activation of the site has been completed.

[0043] Optionally, the method further includes: receiving a roaming start indication message sent by the master device, the roaming start indication message being used to indicate the start of roaming handover of the site.

[0044] Fifthly, a data transmission method is provided. This method is applied to a master device, which is 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; sending a downlink packet of the site to the destination AP; obtaining the sequence number of a downlink packet sent to the site by a source AP, wherein the source AP is any one of the multiple slave devices; and, after completing service activation at the site, sending the buffered downlink packet to the destination AP according to the sequence number.

[0045] The difference between this fifth aspect and the third 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 is sent to the destination AP according to the sequence number after the service activation of the site is completed. Other details can be found in the aforementioned third aspect.

[0046] Sixthly, a data transmission apparatus is provided. This data transmission apparatus has the function of implementing the method described in the first 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 above-described function.

[0047] In a seventh aspect, a data transmission apparatus is provided. This data transmission apparatus has the function of implementing the method described in the second aspect above. 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.

[0048] Eighthly, 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 described function.

[0049] Ninthly, a data transmission apparatus is provided. This data transmission apparatus has the function of implementing the method described in the fourth 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 described function.

[0050] In a tenth aspect, a data transmission apparatus is provided. This data transmission apparatus has the function of implementing the method described in the fifth aspect above. 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 described function.

[0051] Eleventhly, 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 one of the data transmission methods provided in any one of the first to fifth aspects.

[0052] 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.

[0053] Optionally, the communication interface includes a transceiver.

[0054] 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 in any of the first to fifth aspects.

[0055] Optionally, the memory may be integrated with the processor, or the memory may be separated from the processor.

[0056] 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.

[0057] In a twelfth aspect, a communication system is provided, comprising a master device and a plurality of slave devices, wherein the master device and the plurality of slave devices are connected via optical fiber. The master device is used to implement any of the data transmission methods provided in the first, second, or fifth aspects described above.

[0058] In a thirteenth aspect, a communication system is provided, 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 the methods provided in the third aspect and its optional embodiments. A destination access point (AP) among the plurality of slave devices is used to implement the methods provided in the fourth aspect and its optional embodiments.

[0059] In a fourteenth 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 any of the first to fifth aspects.

[0060] In a fifteenth aspect, 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 one of the data transmission methods provided in any of the first to fifth aspects.

[0061] In a sixteenth 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 such that the chip performs any of the data transmission methods provided in any of the first to fifth aspects described above. Attached Figure Description

[0062] Figure 1 is a schematic diagram of the system architecture for fiber to the home or fiber to the office.

[0063] Figure 2 is a schematic diagram of the FTTR system architecture;

[0064] Figure 3 is a schematic diagram of the management channel between the master and slave devices in an FTTR network;

[0065] Figure 4 is a schematic diagram of a site roaming in an FTTR network;

[0066] Figure 5 is a schematic diagram of a data transmission method provided in an embodiment of this application;

[0067] Figure 6 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0068] Figure 7 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0069] Figure 8 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0070] Figure 9 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0071] Figure 10 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0072] Figure 11 is a schematic diagram of another data transmission method provided in an embodiment of this application;

[0073] Figure 12 is a schematic diagram of a data transmission device provided in an embodiment of this application;

[0074] Figure 13 is a schematic diagram of another data transmission device provided in an embodiment of this application;

[0075] Figure 14 is a schematic diagram of another data transmission device provided in an embodiment of this application;

[0076] Figure 15 is a schematic diagram of another data transmission device provided in an embodiment of this application;

[0077] Figure 16 is a schematic diagram of another data transmission device provided in an embodiment of this application;

[0078] Figure 17 is a schematic diagram of the structure of an optical communication device provided in another exemplary embodiment of this application. Detailed Implementation

[0079] 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.

[0080] 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).

[0081] 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).

[0082] 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).

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] Table 1 WMCI Message Encapsulation Format

[0089] The following is an explanation of each field in Table 1.

[0090] 1) Message Type ID

[0091] 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.

[0092] In the embodiments of this application, the types of messages include, but are not limited to, roaming switching messages, etc., as described below.

[0093] 2) SeqNo

[0094] 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.

[0095] 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.

[0096] 3) Length and processing requirements

[0097] The message length and processing is a 2-byte field consisting of three fields: message priority, operation type, and message content length.

[0098] 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.

[0099] C: Used to indicate the operation type of the current message.

[0100] 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.

[0101] 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.

[0102] LL LLLL LLLL: This field indicates the length of the message content. The value range is 0 to 1023.

[0103] 4) Message content

[0104] 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.

[0105] The message mask consists of a 16-bit mask, as shown in Table 2.

[0106] Table 2 Message Masks

[0107] Each message type can carry up to 16 parameters.

[0108] 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.

[0109] 5) Message verification

[0110] 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.

[0111] The message transmission mechanism between the master and slave devices is explained below.

[0112] Both the master and slave devices can actively send WMCI messages or respond to messages sent by the other.

[0113] Downlink messages are parameter request messages and configuration messages; uplink messages are parameter reporting messages, scheduling requests, and status alarm messages.

[0114] 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.

[0115] The format of the parameter request message is shown in Table 3 below.

[0116] Table 3

[0117] 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.

[0118] The format of the configuration message is shown in Table 4 below.

[0119] Table 4

[0120] 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.

[0121] The format of the parameter reporting message is shown in Table 5 below.

[0122] Table 5

[0123] 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.

[0124] The format of the status alarm messages mentioned above is shown in Table 6 below.

[0125] Table 6

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] Figure 5 is a schematic diagram of data transmission according to an embodiment of this application. This method is applied to a communication system comprising multiple access points (APs), each AP including 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.

[0134] As shown in Figure 5, the method includes:

[0135] In step 501, the master device determines the destination AP of the site where roaming will occur.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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 slave device's service load information. 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.

[0140] 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.

[0141] In step 502, the master device caches the downlink packets of the site.

[0142] In this process, after receiving a roaming trigger event or a roaming decision indicating the destination AP, the master device caches the downlink packets for that site and continues to send the cached downlink packets for that site to the source AP. The downlink packets cached by the master device are essentially a backup of the downlink packets sent to the source AP.

[0143] The downlink messages from this station are those received and buffered by the master device that need to be sent to this station, and the destination address in these messages is the address of this station. These downlink messages are sent by the OLT to the master device. Optionally, the messages can also be called data packets or data frames.

[0144] In step 503, the master device obtains the sequence number of the downlink message sent by the source access point to the site.

[0145] During the process of the source access point sending downlink packets to the station, if the station's signal quality is poor, the source access point will be unable to send downlink packets to the station. The source access point can send the sequence numbers of the downlink packets that have already been sent to the station to the master device.

[0146] Optionally, the sequence number of the downlink message can be the sequence number of the last message sent by the source access point to the site.

[0147] In practice, the sequence number of a message can be carried by the IP identifier (ID) field in the IP header, or by a private tunnel encapsulation.

[0148] In step 504, the destination AP sends a service activation completion message to the master device.

[0149] The master device receives the message indicating that the service has been successfully started.

[0150] This service activation completion message indicates that the destination AP has activated the service for the site. In other words, a data path has been established between the destination AP and the site, the site has roamed to the destination AP, and the destination AP can now provide services to the site.

[0151] In step 505, the master device sends the cached downlink message to the destination AP according to the sequence number.

[0152] The master device can retrieve the target downlink packet to be sent to the destination AP from the cached downlink packets based on this sequence number, and then send the target downlink packet to the destination AP. Specifically, the master device can send the next packet starting with this sequence number, as well as subsequent packets, to the destination AP.

[0153] For example, if the sequence number of the downlink message sent by the source access point to the site is 100, the master device will send the message with sequence number 101 and subsequent messages to the destination AP.

[0154] In step 506, the destination AP sends a downlink message to the station.

[0155] In this embodiment, before a site roams from a source AP to a destination AP, the master device pre-caches the downlink packets for that site. After receiving the service activation completion message from the destination AP, i.e., after the site's roaming handover is complete, the master device sends the cached downlink packets to the destination AP based on the sequence number of the downlink packets sent from the source access point to the site. This ensures that the downlink packets sent to the site are continuous before and after the roaming handover, thereby reducing downlink packet loss during roaming and improving the user's network experience.

[0156] Figure 6 is a schematic diagram of data transmission according to an embodiment of this application. This method is applied to a communication system comprising 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 fiber. For example, the communication system shown in Figure 2 or Figure 4. In this embodiment, the source AP and the destination AP are any two slave devices from the multiple slave devices. In this case, the source AP can also be referred to as the source slave device, and the destination AP can also be referred to as the destination slave device.

[0157] As shown in Figure 6, the method includes:

[0158] In step 601, the master device determines the destination AP of the site where roaming will occur.

[0159] See step 501 for related details, which will not be described in detail here.

[0160] In step 602, the master device caches the downlink packets of the station.

[0161] See step 502 for related details, which will not be described in detail here.

[0162] In step 603, the master device sends roaming start indication messages to the source AP and the destination AP.

[0163] 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.

[0164] Optionally, the roaming start indication message is a WMCI message, which can adopt the message format in Table 1 above.

[0165] In one 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).

[0166] For example, the roaming handover message content fields include a first indication field, a MAC address field, and a roaming status field. The first indication field indicates that the type of the roaming handover message is a roaming handover indication message. The MAC address field carries the MAC address of the site. The roaming status field indicates which stage of the roaming handover process the roaming handover indication is in; here, the roaming status field indicates 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 first indication field and roaming status field in the message content field.

[0167] In the embodiments of this application, the roaming status includes, but is not limited to, roaming decision information collection, roaming start, roaming preprocessing, instructing service to be turned off, and instructing service to be turned on.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] Optionally, the preprocessing of the target AP includes the following two possible scenarios:

[0172] (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.

[0173] (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.

[0174] In step 604, the master device sends a service shutdown instruction message to the source AP.

[0175] The service shutdown instruction message is used to instruct the source AP to shut down the services at the site.

[0176] Accordingly, the source AP receives the service shutdown instruction message and shuts down the service at the site based on the message. After successfully shutting down the service, the source AP proceeds to step 606.

[0177] For example, the service shutdown instruction message is a WMCI message, which can adopt the message format in Table 1.

[0178] 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 site's MAC address or AID.

[0179] For example, the message content fields of the aforementioned roaming handover message include a first indication field, a MAC address field, and a roaming status field. The MAC address field carries the MAC address of the site. The first indication field indicates that the type of roaming handover message is a roaming handover indication. 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, indicating service closure, and indicating service activation. Here, the roaming status field is used to indicate service closure. This embodiment determines that the message is a service closure completion message based on the message type identifier field and the first indication field and roaming status field in the message content field.

[0180] 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.

[0181] In step 605, the source AP sends a service shutdown completion message to the master device.

[0182] The "Service Closure Completed" message indicates that the services for the site have been shut down.

[0183] For example, the service shutdown completion message carries parameters to be synchronized. Here, the parameters to be synchronized include packet number (PN), data packet sequence number (SN) context, key update information, STA sleep state, message sequence number and other context information.

[0184] Accordingly, the master device receives a message indicating that the service has been closed.

[0185] Optionally, the service closure completion message is a WMCI message, which can adopt the message format in Table 1.

[0186] 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.

[0187] For example, the message content fields of the service shutdown completion message (the roaming handover message in the previous paragraph) include a first indication field, a MAC address field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The first 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. The second indication field is used to carry the aforementioned sequence number.

[0188] In other words, based on the message type identifier field and the first 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, facilitating FTTR equipment identification and obtaining the information carried in the roaming handover messages, thus improving identification efficiency.

[0189] 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.

[0190] In step 606, the master device sends a service activation instruction message to the destination AP.

[0191] The service activation instruction message is used to instruct the activation of services for the site.

[0192] 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 according to the service activation instruction message. After the destination AP completes service activation, it executes step 608.

[0193] For example, the service activation instruction message is a WMCI message, which can adopt the message format in Table 1.

[0194] 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.

[0195] For example, the message content fields of the service activation indication message (the aforementioned roaming handover message) include a first indication field, a MAC address field, and a roaming status field. The MAC address field carries the MAC address of the site, the first 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 has been 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 first indication field and roaming status field in the message content field.

[0196] 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.

[0197] In step 607, the destination AP sends a service activation completion message to the master device.

[0198] The "Service Activation Complete" message indicates that the services for the site have been activated.

[0199] Accordingly, the master device receives the service activation completion message sent by the destination AP, and the roaming handover ends.

[0200] Optionally, the service activation completion message is a WMCI message, which can adopt the message format in Table 1.

[0201] In one possible implementation, 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 a roaming handover message, and the message content field carries the MAC address of the site.

[0202] For example, the message content fields of the service activation completion message (the roaming handover message in the previous paragraph) include a first indication field, a MAC address field, a roaming status field, and a completion status field. Among them, the MAC address field carries the MAC address of the site, the first indication field is used to indicate that the specific type of the roaming handover message is roaming handover completion status reporting, the roaming status field is used to indicate that the service has been activated, and the completion status field is used to indicate that the (service activation) was successful.

[0203] 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 first 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.

[0204] 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.

[0205] In step 608, the master device sends the roaming end notification message to the source AP.

[0206] Accordingly, the source AP receives the roaming end notification message.

[0207] 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.

[0208] 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.

[0209] 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.

[0210] In step 609, the source AP sends a message indication message to the master device.

[0211] Accordingly, the master device receives the message instruction information.

[0212] The message indication information is used to indicate retransmission messages, which are messages that the source AP failed to send to the station. In implementation, the station determines whether there are any lost messages based on the sequence number carried in the received messages; based on the determination result, it sends an acknowledgment message to the source AP. The source AP can then use this acknowledgment message to identify the failed message, i.e., to determine the retransmission message, and thus generate the message indication information.

[0213] Optionally, the acknowledgment message can be associated with one or more messages to indicate whether there are any messages that failed to be sent among the associated messages.

[0214] For example, the number of retransmission messages indicated by the message indication information may be one or more, depending on the actual message reception situation of the site.

[0215] Optionally, the message indication information can indicate the retransmission of the message in the following two ways.

[0216] The first type includes the sequence number of the retransmitted message in the message indication information.

[0217] The second type of message indication information includes the sequence number of the starting message and a bitmap. The bitmap consists of multiple bits, each bit indicating whether the message following the sequence number of the starting message is a retransmission message.

[0218] For example, the starting message sequence number is 1000. The bitmap consists of 32 consecutive bits, each corresponding to a downlink message with sequence numbers 1000-1031, indicating whether the transmission status of the corresponding message was successful or failed. Specifically, the first bit indicates the transmission status of the message with sequence number 1000, the second bit indicates the transmission status of the message with sequence number 1001, and so on.

[0219] When a bit is at its first value, it indicates that the corresponding message was successfully sent and is not a retransmission message; when the bit is at its second value, it indicates that the corresponding message was sent but failed and is a retransmission message. Optionally, the first value can be 0 and the second value can be 1; or the first value can be 1 and the second value can be 0.

[0220] Compared to the first method, this second method can effectively save the number of bits used to indicate retransmission messages, thereby saving network overhead.

[0221] For example, the message indication information can be carried in a roaming message and sent to the master device.

[0222] Optionally, the roaming message sending message may also include a message type identifier field and a message content field.

[0223] For example, the roaming message can be a WMCI message. The message format of the roaming message can be as shown in Table 1.

[0224] In one possible implementation, the Message Type Identifier (ID) field is used to indicate the roaming message transmission. The Message Content field is used to carry the station identifier and message indication information. 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.

[0225] The message content field also includes a first field and a second field. The first field carries the sequence number of the starting message, and the second field carries the bitmap.

[0226] In some examples, the message content field includes one first field and one second field. In other examples, the message content field includes multiple first fields and multiple second fields, with each first field corresponding to one second field.

[0227] As an example, the format of the message content sent by this roaming message can be shown in Table 7 below.

[0228] Table 7. Format of the message content field for roaming message sending.

[0229] In Table 7, the starting serial number is the first field mentioned above; the bitmap is the second field mentioned above.

[0230] As shown in Table 7, the message content fields include multiple first fields and multiple second fields. Each first field corresponds to one second field, and each first field is followed by its corresponding second field. In scenarios with high data transmission rates, the master device pre-stores a large number of downlink packets, and the message indication information can indicate the transmission status of these downlink packets individually. In this case, multiple first and second fields can be set in the message indication information to indicate the transmission status of more downlink packets.

[0231] In Table 7, the message content field also includes a last sequence number field, which is used to carry the sequence number of the message sent by the aforementioned source access point to the site.

[0232] In some embodiments, since the sequence number is carried in the service closure completion message, the roaming message sending message may not include the last sequence number field. In still other embodiments, the service closure completion message may not carry the sequence number, but the last sequence number field may be included in the roaming message sending message.

[0233] It should be noted that step 609 is an optional step. If all messages sent by the source AP to the site are successfully sent, then step 609 does not need to be executed. Accordingly, the steps of sending retransmission messages in step 610 and subsequent step 611 do not need to be executed.

[0234] In step 610, the master device sends the cached downlink message to the destination AP according to the sequence number and message indication information.

[0235] Accordingly, the destination AP receives downlink and retransmission messages from that station.

[0236] The master device sends a cached downlink packet to the destination AP according to the sequence number, including: obtaining the downlink packet (target packet) corresponding to the subsequent sequence number of the sequence number in the downlink packets cached by the master device, and sending the obtained downlink packet (target packet) to the destination AP.

[0237] In some examples, the master device may send retransmission messages to the destination AP first, and then send the buffered downlink messages.

[0238] In step 611, the destination AP sends the received downlink message to the station.

[0239] After receiving the downlink message from the destination AP, the site can continue its previous services.

[0240] In this embodiment, after the cached downlink packets are sent, the master device can send the downlink packets of the destination AP that it received after receiving the service shutdown completion message to the destination AP.

[0241] In this embodiment, the master device prioritizes sending downlink packets received and buffered 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.

[0242] 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 caching 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.

[0243] It should be noted that in the embodiment shown in Figure 6, the source AP sends the message indication information 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 can send the message indication information to the master device during the roaming handover process. For example, the source AP can include the message indication information in the service termination completion message. In this case, steps 608 and 609 can be omitted from the source AP. This allows the source AP to send the message indication information to the master device as quickly as possible, so that the master device can immediately send the retransmission message to the site after the roaming handover is completed.

[0244] Figure 7 is a schematic diagram of another data transmission method provided by an embodiment of this application. The difference from 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 the cached downlink packets to the destination AP after receiving the service activation completion message from the destination AP; instead, it sends the cached downlink packets of the site to the site after completing the service activation of the site.

[0245] 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:

[0246] In step 701, the master device determines the destination AP of the site where roaming will occur.

[0247] See step 501 for related details, which will not be described in detail here.

[0248] In step 702, the master device caches the downlink packets of the site.

[0249] See step 502 for related details, which will not be described in detail here.

[0250] In step 703, the master device sends a roaming start indication message to the source AP.

[0251] See step 603 for related details, which will not be described in detail here.

[0252] In step 704, the master device sends a service shutdown instruction message to the source AP.

[0253] See step 604 for related details, which will not be described in detail here.

[0254] In step 705, the source AP sends a service shutdown completion message to the master device.

[0255] See step 605 for related details, which will not be described in detail here.

[0256] In step 706, the master device sends a roaming end notification message to the source AP.

[0257] See step 608 for related details, which will not be described in detail here.

[0258] In step 707, the source AP sends a message indication message to the master device.

[0259] See step 609 for related details, which will not be described in detail here.

[0260] In step 708, the master device sends the cached downlink message to the station according to the sequence number and message indication information.

[0261] See step 610 for related details, which will not be described in detail here.

[0262] 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 8 and the embodiment shown in Figure 6 is that, in the embodiment shown in Figure 8, the master device and the source AP are the same device, for example, the master device in Figure 2 or Figure 4. Therefore, the embodiment shown in Figure 8 may omit the interaction steps between the master device and the source AP.

[0263] In this embodiment, the site is currently connected to the master device (source AP). Due to site movement or other reasons, a roaming handover process will be initiated.

[0264] As shown in Figure 8, the data transmission method provided in this embodiment includes:

[0265] In step 801, the master device determines the destination AP of the site where roaming will occur.

[0266] See step 501 for related details, which will not be described in detail here.

[0267] In step 802, the master device caches the downlink packets of the station.

[0268] See step 502 for related details, which will not be described in detail here.

[0269] In step 803, the master device sends a roaming start indication message to the destination AP.

[0270] See step 603 for related details, which will not be described in detail here.

[0271] In step 804, the master device sends a service activation instruction message to the destination AP.

[0272] See step 606 for related details, which will not be described in detail here.

[0273] In step 805, the destination AP sends a service activation completion message to the master device.

[0274] See step 607 for related details, which will not be described in detail here.

[0275] In step 806, the master device sends the cached downlink message to the destination AP according to the sequence number.

[0276] In this embodiment, the master device and the source AP are the same device. Therefore, the master device can obtain the sequence number of the downlink message sent to the station from its own recorded information, without needing to obtain the sequence number from other devices.

[0277] See step 610 for related details, which will not be described in detail here.

[0278] Optionally, if there is a failed message sent by the source AP to the site, i.e. a retransmission message, the method further includes: determining the retransmission message and sending the retransmission message to the destination AP after step 805.

[0279] 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 packets to be retransmitted.

[0280] In step 807, the destination AP sends the received downlink message to the station.

[0281] See step 611 for related details, which will not be described in detail here.

[0282] Figure 9 is a schematic diagram of another data transmission method provided in an embodiment of this application. This method is applied to a communication system comprising 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 fiber. For example, the communication system shown in Figure 2 or Figure 4. In this embodiment, the source AP and the destination AP are any two slave devices from the multiple slave devices.

[0283] The difference between the embodiments shown in Figures 5 to 8 is that, in the embodiments shown in Figures 5 to 8, the master device pre-caches the station's packets, while in the embodiment shown in Figure 9, the destination AP pre-caches the station's downlink packets.

[0284] As shown in Figure 9, the method includes:

[0285] In step 901, the master device determines the destination AP.

[0286] See step 501 for related details, which will not be described in detail here.

[0287] In step 902, downlink messages for the site are sent to the source AP and the destination AP.

[0288] In other words, the master device sends the same downlink packets to both the source AP and the destination AP simultaneously. Correspondingly, the destination AP and the source AP receive the downlink packets sent by the master device. Before performing a roaming handover at that site, the source AP sends the received downlink packets to that site.

[0289] In step 903, the destination AP caches the downlink packets of the site.

[0290] After the destination AP receives downlink packets from the site, it will cache those packets. However, since roaming handover has not yet been performed, the site is connected to the source AP but not to the destination AP, and the destination AP will not send data to the site.

[0291] In step 904, the master device obtains the sequence number of the downlink message sent by the source AP to the site, and sends the sequence number to the destination AP.

[0292] The master device can obtain the sequence number of the downlink message sent to the site from the source AP.

[0293] In step 905, the destination AP sends the cached downlink message to the station according to the sequence number.

[0294] In this embodiment, before the site roams from the source AP to the destination AP, the destination AP pre-caches the downlink packets of the site. The master device obtains the sequence number of the downlink packets sent by the source AP to the site and informs the destination AP. In this way, after the site roaming handover, the destination AP can quickly send packets to the site according to the sequence number, thereby improving the continuity of downlink packets sent to the site, reducing downlink packet loss during roaming, and improving the user's network experience.

[0295] Figure 10 is a schematic diagram of another data transmission method provided in an embodiment of this application. In this embodiment, the master device is the master device in Figure 2 or Figure 4, and the source AP and destination AP are any two slave devices in Figure 2 or Figure 4.

[0296] As shown in Figure 10, the method includes:

[0297] In step 1001, the master device determines the destination AP of the site where roaming will occur.

[0298] For related details, please refer to step 501, which will not be repeated here.

[0299] In step 1002, the master device sends a roaming start indication message to both the source AP and the destination AP.

[0300] Accordingly, the source AP and the destination AP receive the roaming start indication message.

[0301] See step 502 for related details, which will not be repeated here.

[0302] In step 1003, the master device sends the downlink message of the site to the destination AP and the source AP.

[0303] For related details, please refer to step 902, which will not be repeated here.

[0304] In step 1004, the destination AP caches the downlink packets received from the site.

[0305] See step 903 for related details, which will not be described in detail here.

[0306] In step 1005, the master device sends a service shutdown instruction message to the source AP.

[0307] See step 604 for related details, which will not be described in detail here.

[0308] In step 1006, the source AP sends a service shutdown completion message to the master device.

[0309] See step 605 for related details, which will not be described in detail here.

[0310] In step 1007, the master device sends a service activation instruction message to the destination AP.

[0311] Step 1007 is basically the same as step 606, except that the service activation instruction message in step 1007 also carries the aforementioned sequence number, while the service activation instruction message in step 606 may not carry the sequence number.

[0312] In step 1008, the destination AP sends the cached downlink message to the station according to the sequence number.

[0313] See step 611 for related details, which will not be described in detail here.

[0314] In step 1009, the destination AP sends a service activation completion message to the master device.

[0315] See step 607 for related details, which will not be described in detail here.

[0316] It should be noted that the execution order between steps 1008 and 1009 is not restricted in the embodiments of this application. Step 1009 can be executed first and then step 1008, or step 1008 can be executed first and then step 1009, or steps 1008 and 1009 can be executed simultaneously.

[0317] In step 1010, the master device sends a roaming end notification message to the source AP.

[0318] See step 608 for related details, which will not be described in detail here.

[0319] In step 1011, the source AP sends message indication information to the master device.

[0320] See step 609 for related details, which will not be described in detail here.

[0321] In step 1012, the master device sends a message indication message to the destination AP.

[0322] Accordingly, the destination AP receives the message instruction information.

[0323] Optionally, this message indication information is carried in the roaming message transmission message. See step 609 for details regarding the roaming message transmission message.

[0324] In step 1013, the destination AP sends the cached downlink message to the station according to the message instruction information.

[0325] See step 611 for related details, which will not be described in detail here.

[0326] Figure 11 is a schematic diagram of another data transmission method provided by an embodiment of this application. Compared with the embodiment shown in Figure 10, the difference is that in the embodiment shown in Figure 10, the master device and the source AP are the same AP, such as the master device in Figure 2 or Figure 4. Therefore, the embodiment shown in Figure 11 may not perform the interaction steps between the master device and the source AP.

[0327] 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:

[0328] In step 1101, the master device determines the destination AP of the site where roaming will occur.

[0329] For related details, please refer to step 501, which will not be repeated here.

[0330] In step 1102, the master device sends a roaming start indication message to the destination AP.

[0331] Accordingly, the destination AP receives the roaming start indication message.

[0332] See step 502 for related details, which will not be repeated here.

[0333] In step 1103, the master device sends the downlink message of the destination AP to the destination AP.

[0334] Since the master device and the source AP are the same device, the master device will send downlink packets to the site at the same time.

[0335] For related details, please refer to step 902, which will not be repeated here.

[0336] In step 1104, the destination AP caches the downlink packets received from the site.

[0337] For related details, please refer to step 903, which will not be repeated here.

[0338] In step 1105, the master device sends a service activation instruction message to the destination AP.

[0339] For related details, please refer to step 603, which will not be repeated here.

[0340] In step 1106, the destination AP sends a service activation completion message to the master device.

[0341] For related details, please refer to step 604, which will not be repeated here.

[0342] In step 1107, the master device sends the cached downlink message to the destination AP according to the sequence number.

[0343] See step 607 for related details, which will not be described in detail here.

[0344] In this embodiment, since the master device and the source AP are the same device, the master device can determine whether there is a retransmission message. If there is a retransmission message, the master device also sends the cached retransmission message to the destination AP.

[0345] In step 1108, the destination AP sends the received downlink message from the station to the station.

[0346] For related details, please refer to step 611, which will not be repeated here.

[0347] The message content fields of the roaming switching messages in the aforementioned embodiments are illustrated below with reference to Tables 8 to 11.

[0348] Table 8. Roaming Switching Instructions and Reporting Messages

[0349] The roaming handover instructions and reporting messages in Table 8 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.

[0350] 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.

[0351] Additionally, the payload field in roaming handover instructions and reporting messages can carry the following: <1> - <3> Any message in the [process].

[0352] <1> Roaming decision feedback information

[0353] Table 9. Roaming Decision Feedback Information

[0354] The roaming decision feedback information, once transmitted to the main device, can be used by the main device to make roaming decisions.

[0355] <2> Contextual information of roaming preprocessing

[0356] Table 10. Contextual Information for Roaming Preprocessing

[0357] 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).

[0358] <3> Roaming feedback context information

[0359] Table 11. Roaming Feedback Context Information

[0360] 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.

[0361] In addition, in the method embodiment shown in Figure 5-11, 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.

[0362] Figure 12 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 12, the data transmission device 1200 includes: a determining module 1201, a buffering module 1202, an acquiring module 1203, and a transceiver module 1204.

[0363] The determination module 1201 is used to determine the destination AP of the site where roaming will occur. The destination AP is any one of a plurality of slave devices connected to the master device via optical fiber. The caching module 1202 is used to cache the downlink packets of the site. The acquisition module 1203 is used to acquire the sequence number of the downlink packets sent by the source AP to the site. The transceiver module 1204 is used to send the cached downlink packets to the destination AP according to the sequence number after receiving the service activation completion message sent by the destination AP.

[0364] Optionally, the transceiver module 1204 is further configured to receive a service shutdown completion message sent by the source AP, the service shutdown completion message carrying the sequence number; the acquisition module 1203 is configured to acquire the sequence number from the service shutdown completion message.

[0365] Optionally, the transceiver module 1204 is further configured to receive message indication information sent by the source AP, the message indication information being used to instruct the source AP to send a failed message to the site; and after receiving a service activation completion message sent by the destination AP, to send the message indicated by the message indication information to the destination AP.

[0366] Optionally, the transceiver module 1204 is configured to receive a service shutdown completion message sent by the source AP, the service shutdown completion message carrying the message indication information; or, after receiving a service activation completion message sent by the destination AP, it receives a roaming message transmission message sent by the source AP, the roaming message transmission message carrying the message indication information.

[0367] Optionally, the transceiver module 1204 is further configured to send a roaming start indication message to the source AP and the destination AP, the roaming start indication message being used to indicate the start of roaming handover of the site.

[0368] Optionally, the transceiver module 1204 is further configured to send a service shutdown indication message to the source AP, the service shutdown indication message being used to indicate that the service of the site is shut down; and to send a service startup indication message to the destination AP, the service startup indication message being used to indicate that the service of the site is started.

[0369] Figure 13 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 13, the data transmission device 1300 includes: a determining module 1301, a buffering module 1302, an acquiring module 1303, and a sending module 1304.

[0370] The determination module 1301 is used to determine the destination AP of the site where roaming will occur, wherein the destination AP is the master device. The caching module 1302 is used to cache the downlink packets of the site. The acquisition module 1303 is used to acquire the sequence number of the downlink packets sent to the site by the source AP, wherein the source AP is any one of a plurality of slave devices connected to the master device via optical fiber. The sending module 1304 is used to send the cached downlink packets to the destination AP according to the sequence number after the service activation of the site is completed.

[0371] Figure 14 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 14, the data transmission device 1400 includes: a determining module 1401, a first transmitting module 1402, an acquiring module 1403, and a second transmitting module 1404.

[0372] The determining module 1401 is used to determine the destination AP of the site where roaming will occur, wherein the destination AP is any one of a plurality of slave devices connected to the master device via optical fiber. The first sending module 1402 is used to send the downlink packets of the site to the destination AP. The obtaining module 1403 is used to obtain the sequence number of the downlink packets sent by the source AP of the site to the site. The second sending module 1404 is used to send the sequence number to the destination AP.

[0373] Optionally, the data transmission device 1400 further includes a receiving module 1405. The receiving module 1405 is used to receive a service shutdown completion message sent by the source AP, the service shutdown completion message carrying the sequence number. The obtaining module 1403 is used to obtain the sequence number from the service shutdown completion message.

[0374] Optionally, the second sending module 1404 is used to send a service activation indication message to the destination AP. The service activation indication message is used to indicate the activation of the service at the site, and the service activation indication message carries the sequence number.

[0375] Optionally, the receiving module 1405 is used to receive message indication information sent by the source AP, the message indication information being used to instruct the source AP to send a failed message to the site; and to send the message indication information to the destination AP.

[0376] Optionally, the receiving module 1405 is configured to receive a service shutdown completion message sent by the source AP, the service shutdown completion message carrying the message indication information; or, after receiving a service activation completion message sent by the destination AP, it receives a roaming message transmission message sent by the source AP, the roaming message transmission message carrying the message indication information.

[0377] Optionally, the second sending module 1404 is further configured to send a roaming start indication message to the source AP and the destination AP, the roaming start indication message being used to indicate the start of roaming handover of the site.

[0378] Optionally, the second sending module 1404 is further configured to send a service shutdown indication message to the source AP, the service shutdown indication message being used to indicate the shutdown of the service at the site.

[0379] Figure 15 is a schematic diagram of a data transmission device provided in an embodiment of this application. This device can be configured as part or all of the aforementioned target AP in a software, hardware, or a combination of software and hardware manner. As shown in Figure 15, the data transmission device 1500 includes: a first receiving module 1501, a buffer module 1502, a second receiving module 1503, and a transmitting module 1504.

[0380] The first receiving module 1501 is used to receive downlink packets from a site sent by a master device, wherein the master device is connected to multiple slave devices via optical fiber. The buffering module 1502 is used to buffer the downlink packets received by the receiving module. The second receiving module 1503 is used to receive a sequence number sent by the master device, wherein the sequence number is the sequence number of the downlink packet sent by the source AP to the site. The sending module 1504 is used to send the buffered downlink packet to the site according to the sequence number.

[0381] Optionally, the second receiving module 1503 is used to receive a service activation instruction message sent by the master device. The service activation instruction message is used to indicate the activation of the service of the site, and the service activation instruction message carries the sequence number.

[0382] Optionally, the sending module 1504 is used to send the cached downlink message to the site according to the sequence number after the service activation of the site is completed.

[0383] Optionally, the second receiving module 1503 is further configured to receive message indication information sent by the master device, the message indication information being used to instruct the source AP of the site to send a failed message to the site; the sending module 1504 is further configured to send the message indicated by the message indication information to the site.

[0384] Optionally, the sending module 1504 is further configured to send a service activation completion message to the master device, the service activation completion message being used to indicate that the service activation of the site has been completed.

[0385] Optionally, the second receiving module 1503 is further configured to receive a roaming start indication message sent by the master device, the roaming start indication message being used to indicate the start of roaming handover of the site.

[0386] Figure 16 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 16, the data transmission device 1600 includes: a determining module 1601, a first transmitting module 1602, an acquiring module 1603, and a second transmitting module 1604.

[0387] The determining module 1601 is used to determine the destination AP of the site where roaming will occur, wherein the destination AP is the master device. The first sending module 1602 is used to send the downlink packets of the site to the destination AP. The obtaining module 1603 is used to obtain the sequence number of the downlink packets sent to the site by the source AP, wherein the source AP is any one of a plurality of slave devices connected to the master device via optical fiber. The second sending module 1604 is used to send the buffered downlink packets to the destination AP according to the sequence number after the service activation of the site is completed.

[0388] Optionally, the data transmission device 1600 further includes a receiving module 1605, which is used to receive a service shutdown completion message sent by the source AP, the service shutdown completion message carrying the sequence number. An obtaining module 1603 is used to obtain the sequence number from the service shutdown completion message.

[0389] 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.

[0390] 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.

[0391] This application also provides an optical communication device. Figure 17 is a schematic diagram of the structure of an optical communication device provided in an embodiment of this application. As shown in Figure 17, the optical communication device 1700 includes a processor 1704 and a communication interface 1708. The processor 1704 and the communication interface 1708 are connected, for example, through a bus 1702. It should be understood that this application does not limit the number of processors in the optical communication device 1700.

[0392] Bus 1702 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 17, but this does not imply that there is only one bus or one type of bus. Bus 1702 can include pathways for transmitting information between various components of the optical communication device 1700 (e.g., processor 1704, communication interface 1708).

[0393] Processor 1704 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).

[0394] The communication interface 1708 uses transceiver modules (e.g., optical modules) such as, but not limited to, transceivers to enable communication between the optical communication device 1700 and other devices or communication networks.

[0395] Optionally, the optical communication device also includes a memory 1706, and the processor 1704, memory 1706, and communication interface 1708 communicate via a bus 1702. It should be understood that this application does not limit the number of memories in the optical communication device 1700.

[0396] The memory 1706 may include volatile memory, such as random access memory (RAM). The processor 1704 may also include non-volatile memory, such as read-only memory (ROM), flash memory, hard disk drive (HDD), or solid state drive (SSD).

[0397] The memory 1706 stores executable program code, and the processor 1704 executes this executable program code to implement the functions of the aforementioned modules, thereby realizing the aforementioned data transmission method. That is, the memory 1706 stores instructions for executing the data transmission method.

[0398] 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.

[0399] 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.

[0400] 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.

[0401] 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.

[0402] 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 of the site where roaming will occur, wherein the destination access point is any one of a plurality of slave devices; Cache the downlink packets of the site; Obtain the sequence number of the downlink packet sent from the source access point of the site to the site; After receiving the service activation completion message from the destination access point, the cached downlink message is sent to the destination access point according to the sequence number.

2. The method according to claim 1, characterized in that, The sequence number of the downlink message sent from the source access point of the obtained site to the site includes: Receive a service shutdown completion message sent by the source access point, the service shutdown completion message carrying the sequence number.

3. The method according to claim 2, characterized in that, The service closure 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 first indication field, a media access control MAC address field, a second indication field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The first indication field is used to indicate that the type of roaming handover message is roaming handover completion status reporting. The second indication field is used to carry the sequence number. The roaming status field is used to indicate that the service is closed. 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 method further includes: Receive message indication information sent by the source access point, the message indication information being used to instruct the source access point to send a failed message to the site; After receiving the service activation completion message sent by the destination access point, send the message indicated by the message indication information to the destination access point.

5. The method according to claim 4, characterized in that, The message indication information includes the sequence number of the message that failed to be sent; Alternatively, the message indication information may include the sequence number of the starting message and a bitmap, wherein the bits in the bitmap are used to indicate whether a message following the starting message has been successfully sent.

6. The method according to claim 4 or 5, characterized in that, The receipt of the message indication information sent by the source access point includes: Receive a service shutdown completion message sent by the source access point, the service shutdown completion message carrying the message indication information; or, After receiving the service activation completion message sent by the destination access point, the system receives the roaming message sending message sent by the source access point, the roaming message sending message carrying the message indication information.

7. The method according to any one of claims 1 to 6, 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 first 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 first 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.

8. The method according to any one of claims 1 to 7, characterized in that, The method further includes: A roaming start indication message is sent to the source access point and the destination access point. The roaming start indication message is used to indicate the start of roaming handover for the site.

9. The method according to any one of claims 1 to 8, characterized in that, The method further includes: Send a service shutdown instruction message to the source access point, the service shutdown instruction message being used to instruct the shutdown of the service of the site; Send a service activation instruction message to the destination access point, the service activation instruction message being used to instruct the activation of services at the site.

10. 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; Obtain the sequence number of the downlink message sent from the source access point of the site to the site, wherein the source access point is any one of the plurality of slave devices; After the service activation of the site is completed, the cached downlink message is sent to the destination access point according to the sequence number.

11. 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 any one of the plurality of slave devices; Send the downlink message of the site to the destination access point; Obtain the sequence number of the downlink packet sent from the source access point of the site to the site; Send the sequence number to the destination access point.

12. The method according to claim 11, characterized in that, The sequence number of the downlink message sent from the source access point of the obtained site to the site includes: Receive a service shutdown completion message sent by the source access point, the service shutdown completion message carrying the sequence number.

13. The method according to claim 12, characterized in that, The service closure 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 first indication field, a media access control MAC address field, a second indication field, a roaming status field, and a completion status field. The MAC address field carries the MAC address of the site. The first indication field is used to indicate that the type of roaming handover message is roaming handover completion status reporting. The second indication field is used to carry the sequence number. The roaming status field is used to indicate that the service is closed. The completion status field is used to indicate success.

14. The method according to any one of claims 11 to 13, characterized in that, Sending the sequence number to the destination access point includes: A service activation instruction message is sent to the destination access point. The service activation instruction message is used to indicate that the service of the site is activated. The service activation instruction message carries the sequence number.

15. The method according to claim 14, characterized in that, The service activation instruction 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 first indication field, a media access control MAC address field, a roaming status field, and a second indication field. The MAC address field carries the MAC address of the site. The first indication field is used to indicate that the type of roaming switching message is a roaming switching indication. The roaming status field is used to indicate that the service is enabled. The second indication field is used to carry the sequence number.

16. The method according to any one of claims 11 to 15, characterized in that, The method further includes: Receive message indication information sent by the source access point, the message indication information being used to instruct the source access point to send a failed message to the site; Send the message indication information to the destination access point.

17. The method according to claim 16, characterized in that, The message indication information includes the sequence number of the retransmitted message; Alternatively, the message indication information may include the sequence number of the starting message and a bitmap, wherein the bits in the bitmap are used to indicate whether a message following the starting message is a retransmission message.

18. The method according to claim 16 or 17, characterized in that, The receipt of the message indication information sent by the source access point includes: Receive a service shutdown completion message sent by the source access point, the service shutdown completion message carrying the message indication information; or, After receiving the service activation completion message sent by the destination access point, the system receives the roaming message sending message sent by the source access point, the roaming message sending message carrying the message indication information.

19. The method according to any one of claims 11 to 18, characterized in that, A roaming start indication message is sent to the source access point and the destination access point. The roaming start indication message is used to indicate the start of roaming handover for the site.

20. The method according to any one of claims 11 to 19, characterized in that, The method further includes: A service shutdown instruction message is sent to the source access point, the service shutdown instruction message being used to instruct the shutdown of the service of the site.

21. A data transmission method, characterized in that, Applied to a destination access point, the method includes: The system receives and buffers downlink packets from stations sent by a master device, which is connected to multiple slave devices via optical fiber, and the destination access point is any one of the multiple slave devices. Receive the sequence number sent by the master device, where the sequence number is the sequence number of the downlink message sent by the source access point of the site to the site; The cached downlink message is sent to the station according to the sequence number.

22. The method according to claim 21, characterized in that, The sequence number received from the master device includes: The system receives a service activation instruction message sent by the master device. The service activation instruction message is used to indicate the activation of services at the site and carries the sequence number.

23. The method according to claim 22, characterized in that, The service activation instruction 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 first indication field, a media access control MAC address field, a roaming status field, and a second indication field. The MAC address field carries the MAC address of the site. The first indication field is used to indicate that the type of roaming switching message is a roaming switching indication. The roaming status field is used to indicate that the service is enabled. The second indication field is used to carry the sequence number.

24. The method according to any one of claims 21 to 23, characterized in that, The step of sending the cached downlink message to the station according to the sequence number includes: After the service activation of the site is completed, the cached downlink message is sent to the site according to the sequence number.

25. The method according to any one of claims 21 to 24, characterized in that, The method further includes: Receive message indication information sent by the master device, the message indication information being used to instruct the source access point of the site to send a failed message to the site; Send the message indicated by the message indication information to the station.

26. The method according to claim 25, characterized in that, The message indication information includes the sequence number of the retransmitted message; Alternatively, the message indication information may include the sequence number of the starting message and a bitmap, wherein the bits in the bitmap are used to indicate whether a message following the starting message is a retransmission message.

27. The method according to any one of claims 21 to 26, characterized in that, The method further includes: Send a service activation completion message to the master device. The service activation completion message is used to indicate that the service activation of the site has been completed.

28. The method according to any one of claims 21 to 27, characterized in that, The method further includes: The system receives a roaming start indication message sent by the master device, which is used to indicate the start of roaming handover for the site.

29. 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; Send the downlink message of the site to the destination access point; Obtain the sequence number of the downlink message sent from the source access point of the site to the site, wherein the source access point is any one of the plurality of slave devices; After the service activation of the site is completed, the cached downlink message is sent to the destination access point according to the sequence number.

30. A data transmission device, characterized in that, The device includes: The determination module is used to determine the destination access point of the site where roaming will occur, wherein the destination access point is any one of a plurality of slave devices connected to the master device via optical fiber; A caching module is used to cache downlink packets of the site; The acquisition module is used to acquire the sequence number of the downlink message sent from the source access point of the site to the site; The transceiver module is used to send the cached downlink message to the destination access point according to the sequence number after receiving the service activation completion message sent by the destination access point.

31. A data transmission device, characterized in that, The device includes: The determination module is used to determine the destination access point of the site where roaming will occur, wherein the destination access point is the master device; A caching module is used to cache downlink packets of the site; The acquisition module is used to acquire the sequence number of the downlink message sent by the source access point of the site to the site, wherein the source access point is any one of a plurality of slave devices connected to the master device via optical fiber; The sending module is used to send the cached downlink message to the destination access point according to the sequence number after the service activation of the site is completed.

32. A data transmission device, characterized in that, The device includes: The determination module is used to determine the destination access point of the site where roaming will occur, wherein the destination access point is any one of a plurality of slave devices connected to the master device via optical fiber; The first sending module is used to send the downlink message of the site to the destination access point; The acquisition module is used to acquire the sequence number of the downlink packet sent from the source access point of the site to the site; The second sending module is used to send the sequence number to the destination access point.

33. A data transmission device, characterized in that, The device includes: The first receiving module is used to receive downlink messages from the site sent by the master device, wherein the master device is connected to multiple slave devices via optical fiber; A caching module is used to cache the downlink messages received by the receiving module; The second receiving module is used to receive the sequence number sent by the master device, wherein the sequence number is the sequence number of the downlink message sent by the source access point of the site to the site; The sending module is used to send the cached downlink message to the station according to the sequence number.

34. A data transmission device, characterized in that, The device includes: The determination module 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 first sending module is used to send the downlink message of the site to the destination access point; The acquisition module is used to acquire the sequence number of the downlink message sent by the source access point of the site to the site, wherein the source access point is any one of a plurality of slave devices connected to the master device via optical fiber; The second sending module is used to send the cached downlink message to the destination access point according to the sequence number after the service activation of the site is completed.

35. 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 execute the data transmission method as described in any one of claims 1 to 9, or execute the data transmission method as described in claim 10, or execute the data transmission method as described in any one of claims 11 to 20, or execute the data transmission method as described in any one of claims 21 to 28, or execute the data transmission method as described in claim 29.

36. 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, can implement the data transmission method as described in any one of claims 1 to 9, or the data transmission method as described in claim 10, or the data transmission method as described in any one of claims 11 to 20, or the data transmission method as described in any one of claims 21 to 28, or the data transmission method as described in claim 29.

37. A communication system, characterized in that, The communication system includes a master device and multiple slave devices, the master device and the multiple slave devices are connected by optical fiber, and the master device is used to execute the data transmission method as described in any one of claims 1 to 9, or to implement the data transmission method as described in claim 10, or to execute the data transmission method as described in claim 29.

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 execute the data transmission method as described in any one of claims 11 to 20, and the destination access point among the plurality of slave devices being used to execute the data transmission method as described in any one of claims 21 to 28.

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