Seamless roaming method, access point, terminal and seamless roaming system

Abstract

The application relates to the communication technical field, discloses a seamless roaming method, an access point, a terminal and a seamless roaming system. The method comprises the following steps: in response to determining that roaming needs to be triggered, a group owner-group client communication link is established with a terminal; and before the terminal and a target access point complete connection, the terminal is communicated through the group owner-group client communication link, and the target access point is a target for the terminal to soon perform roaming switching. The group owner-group client communication link is established between the original access point and the terminal, so that the packet loss problem of the terminal in the process of disconnecting the link with the original access point and reestablishing the link with the target access point is solved, and zero packet loss roaming is realized without additional hardware, without changing standard protocols and without relying on strict synchronization between access points.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a seamless roaming method, access point, terminal, and seamless roaming system. Background Technology

[0002] Existing seamless roaming solutions can be mainly divided into three categories: seamless roaming based on dual links, seamless roaming based on roaming process modification, and seamless roaming based on multi-AP (access point) data interaction. Their main drawbacks are as follows: 1. Seamless roaming based on dual links: This mostly relies on two sets of physical network cards, and not all terminal devices support DBDC functionality. Furthermore, Wi-Fi 7 devices disable DBDC when MLO is enabled, therefore, current seamless roaming solutions based on multi-links lack universality. 2. Seamless roaming based on modified roaming protocols: Although it is possible to achieve a "establish a new connection first, then disconnect the old connection" switching process by modifying the roaming protocol, it is still impossible to completely achieve zero packet loss. Furthermore, the modification of the standard roaming protocol also makes this solution non-compliant with standard protocol specifications. 3. Seamless roaming based on multi-AP data interaction: It relies heavily on centralized management and control of multiple APs and has extremely strict requirements on the interaction latency between APs.

[0003] In summary, existing seamless roaming solutions still suffer from data loss during roaming handover, making it difficult to achieve zero-packet-loss roaming without additional hardware, changes to standard protocols, or strict synchronization between APs. Summary of the Invention

[0004] The purpose of this invention is to provide at least one seamless roaming method, access point, terminal, and seamless roaming system, which can at least solve the technical problem that existing methods are unable to achieve zero packet loss roaming without additional hardware, without modifying standard protocols, and without relying on strict synchronization between APs.

[0005] To address the aforementioned technical problems, at least one embodiment of this application provides a seamless roaming method, comprising: In response to the determination that roaming needs to be triggered, a group owner-group client communication link is established with the terminal; Before the terminal completes the connection with the target access point, it communicates with the terminal through the group owner-group client communication link. The target access point is the target to which the terminal will switch roaming.

[0006] In some optional embodiments, communicating with the terminal via the group owner-group client communication link includes: During the existence of the main link between the terminal and the original access point, if the communication quality of the main link is detected to be substandard and the terminal fails to establish a connection with the target access point, redundant communication is performed with the terminal using both the main link and the group owner-group client communication link.

[0007] In some optional embodiments, communicating with the terminal via the group owner-group client communication link further includes: When the main link is disconnected, communication with the terminal is achieved through the group owner-group client communication link.

[0008] In some alternative embodiments, the group owner-group client communication link uses a different channel frequency band than the main link.

[0009] In some optional embodiments, it also includes: Once the new main link is established between the terminal and the target access point, the group owner-group client communication link is released.

[0010] At least one embodiment of this application provides a seamless roaming method applied to a terminal, including: In response to receiving a group owner-group client communication link establishment instruction sent by the original access point after determining that roaming needs to be triggered, a group owner-group client communication link is established with the original access point; Before the terminal completes the connection with the target access point, it communicates with the terminal through the group owner-group client communication link. The target access point is the target to which the terminal will switch roaming.

[0011] In some optional embodiments, communicating with the original access point via the group owner-group client communication link includes: During the existence of the main link between the terminal and the original access point, if the communication quality of the main link is substandard and the terminal fails to establish a connection with the target access point, redundant communication with the original access point is simultaneously performed using the main link and the group owner-group client communication link.

[0012] In some alternative embodiments, the following are also included: Data packets from the main link and the group owner-group client communication link are deduplicated and reordered.

[0013] In some optional embodiments, establishing a connection with the target access point includes: The target access point is determined based on roaming assistance information, and the established authentication context is reused during the association process with the target access point to skip the complete authentication process.

[0014] In some optional embodiments, after establishing a connection with the target access point, the method further includes: Switch the business data path to the main link established with the target access point, and release the group owner-group client communication link.

[0015] At least one embodiment of this application also provides a primary access point, including: The first module is used to establish a group owner-group client communication link with the terminal in response to the determination that roaming needs to be triggered. The first communication module is used to communicate with the terminal through the group owner-group client communication link before the terminal completes the connection with the target access point, wherein the target access point is the target to which the terminal is about to switch roaming.

[0016] At least one embodiment of this application also provides a terminal, including: The second establishment module is used to establish a group owner-group client communication link with the original access point in response to receiving a group owner-group client communication link establishment instruction sent by the original access point after determining that roaming needs to be triggered; The second communication module is used to communicate with the original access point through the group owner-group client communication link before the terminal completes the connection with the target access point, where the target access point is the target to which the terminal is about to switch roaming.

[0017] A seamless roaming system, characterized in that it includes: The original access point is used to establish a group owner-group client communication link with the terminal in response to the determination that roaming needs to be triggered; A terminal, configured to receive data forwarded by the original access point via the group owner-group client communication link; The target access point is used to establish a connection with the terminal. The group owner-group client communication link is used to continuously forward data before the terminal completes the connection with the target access point, where the target access point is the target to which the terminal is about to switch roaming.

[0018] At least one embodiment of this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the seamless roaming method described above.

[0019] At least one embodiment of this application also provides a computer program product, including a computer program that, when executed by a processor, implements the seamless roaming method described above.

[0020] The seamless roaming method, access point, terminal, and seamless roaming system provided in the embodiments of this application, by adopting a group owner-group client communication link (i.e., Wi-Fi Direct P2P mode), have their data fallback function completed locally on the original access point alone. This eliminates the need for dual physical network cards for the terminal and avoids reliance on wired networks between the original and target access points for low-latency data synchronization or contextual interaction. Therefore, it solves the problems of lack of universality due to reliance on DBDC hardware and the difficulty in deployment due to centralized management and strict interaction latency between APs in the background art. Furthermore, the establishment of the group owner-group client communication link follows the Wi-Fi Direct standard protocol and does not modify the 802.11 roaming protocol itself, thus avoiding any issues of non-compliance with standard protocol specifications. By establishing a group owner-group client communication link between the original access point and the terminal, it compensates for packet loss during the disconnection of the link with the original access point and the re-establishment of the link with the target access point. Ultimately, it achieves zero-packet-loss roaming without requiring additional hardware, modifying standard protocols, or relying on strict synchronization between APs. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative descriptions do not constitute a limitation on the embodiments.

[0022] Figure 1 This is a flowchart of a seamless roaming method provided in one embodiment of this application. Figure 1 ; Figure 2 This is a flowchart of a seamless roaming method provided in one embodiment of this application. Figure 2 ; Figure 3 This is a schematic diagram of a zero-packet-loss roaming process provided in one embodiment of this application; Figure 4 This is a schematic diagram of the original access point provided in one embodiment of this application; Figure 5 This is a schematic diagram of a terminal provided in another embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this application to help readers better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0024] This invention proposes a seamless roaming method. The implementation details of the seamless roaming method in this embodiment are described below. The following content is only for the convenience of understanding and is not necessary for implementing this solution.

[0025] Example 1: The seamless roaming method of this embodiment can be applied to original access points with communication, computing, and data storage capabilities. Its specific process can be as follows: Figure 1 As shown, it includes: Step 110: In response to the determination that roaming needs to be triggered, establish a group owner-group client communication link with the terminal; Step 120: Before the terminal completes the connection with the target access point, it communicates with the terminal through the group owner-group client communication link. The target access point is the target to which the terminal will switch roaming.

[0026] Specifically, the original access point (OAP) is the service access point currently connected to the terminal. When the OAP determines that roaming needs to be triggered, it establishes a group owner-group client communication link (GO-GC direct link) with the terminal. The "determination to trigger roaming" can be based on various factors, such as the OAP detecting a continuous deterioration in the primary link signal quality with the terminal, receiving a measurement report from the terminal, or receiving a load balancing indication initiated by the network side. When the triggering conditions are met, the OAP does not directly disconnect from the terminal, but actively uses the Wi-Fi Direct (P2P) protocol stack to establish a point-to-point direct link with the terminal. In this P2P group, the OAP acts as the group owner (GO), and the terminal acts as the group client (GC), forming the group owner-group client communication link. The establishment of this link does not rely on an additional physical network card, but is achieved by reusing the existing VAP resources on the OAP and the terminal.

[0027] Before the terminal completes its connection with the target access point, the original access point communicates with the terminal via the aforementioned group owner-group client communication link. The target access point is the access point to which the terminal will be switched during roaming. This "communication" includes at least the following: the original access point forwards downlink service data destined for the terminal via the GO-GC direct link, ensuring continuous data delivery during the transition period from the original access point to the target access point, and preventing service interruption or data loss due to primary link failure. This communication process is independent of the standard association process between the terminal and the target access point, and is executed in parallel, thus providing a fallback channel independent of the infrastructure network for roaming switching.

[0028] In some optional embodiments, communicating with the terminal via the group owner-group client communication link includes: during the existence of the main link between the terminal and the original access point, when it is detected that the communication quality of the main link is substandard and the terminal has not established a connection with the target access point, simultaneously using the main link and the group owner-group client communication link to perform redundant communication with the terminal.

[0029] Specifically, the primary link refers to the 802.11 connection link between the terminal and the original access point based on the infrastructure model. The condition that the primary link is still operational and has data carrying capacity limits the time window for initiating redundant communication to the transitional phase where the primary link is available but has experienced quality degradation, rather than a post-disconnection scenario after the primary link has completely failed. That is, the redundant communication in this embodiment is not a post-disconnection remedy, but rather a pre-disconnection prevention.

[0030] Redundant communication refers to a system where, for the same service data packet destined for a terminal, the original access point simultaneously sends the same copy to the terminal on both the main link and the GO-GC direct link (group owner-group client communication link). This serves as a backup for each other, rather than a path switching between the two, allowing the terminal to receive two copies of the data. Based on this heterogeneous redundant transmission mechanism, the probability of packet loss due to signal fluctuations on a single link is significantly reduced.

[0031] In some optional embodiments, communicating with the terminal via the group owner-group client communication link further includes: communicating with the terminal via the group owner-group client communication link after the main link is disconnected.

[0032] Specifically, when the primary link is completely disconnected due to signal degradation, excessive distance, or active deassociation, the original access point and the terminal can no longer exchange data using the standard infrastructure mode. At this point, the previously established group owner-group client communication link serves as a backup data channel, continuing to carry downlink service data from the original access point to the terminal until the terminal and the target access point complete the construction of a new primary link.

[0033] This mechanism embodies the core "backup" function of the GO-GC direct link, ensuring that downlink data can still be continuously delivered to the terminal during the "communication window" when the main link is completely interrupted, thus avoiding data loss due to link interruption. This mechanism, along with the aforementioned "redundant communication," represents single-path continuation after the main link is interrupted and dual-path parallel transmission when the main link is active, respectively covering different stages of the roaming transition period.

[0034] During the "backup" transmission process, the original access point utilizes a retransmission mechanism based on interrupted transmission completion to ensure reliable message transmission: After each data frame is transmitted on the P2P link, the underlying Wi-Fi chip reports the transmission completion status to the MAC layer. For frames that fail to transmit, the MAC layer reschedules them for transmission in its local retransmission queue until the maximum retransmission limit (defined by dot11ShortRetryLimit and dot11LongRetryLimit) is reached. This retransmission mechanism is independent of TCP retransmission, resolving packet loss caused by channel interference at the MAC layer, ensuring that all messages in the original access point's buffer are reliably delivered to the terminal. Retransmission parameters can be configured differently based on the service type (VoIP, video streaming, file transfer).

[0035] In some alternative embodiments, the group owner-group client communication link uses a different channel frequency band than the main link.

[0036] Specifically, the main link typically operates on a channel within the 2.4GHz, 5GHz, or 6GHz frequency band, while the group owner-group client communication link is configured on a channel in a different frequency band. For example, the main link might use the 5GHz band, while the group owner-group client communication link might use the 2.4GHz band. Modern Wi-Fi chips generally support dual-band / tri-band concurrency, allowing P2P direct connections to be established using available frequency band resources without additional hardware overhead.

[0037] The two links operate on different frequency bands, avoiding data conflicts, backoff waiting, and throughput reduction caused by competition for air interface resources on the same channel, thus ensuring the communication efficiency of each link. Simultaneously, different frequency bands have different propagation characteristics: 2.4GHz has strong penetration and wide coverage, while 5GHz / 6GHz offers high speeds but rapid attenuation. This differentiated frequency band configuration allows the main link and the GO-GC direct link to have complementary coverage capabilities. When the main link degrades due to distance or obstruction, the GO-GC direct link may still maintain good communication quality, effectively improving the reliability of backup transmission.

[0038] In some optional embodiments, the method further includes: releasing the group owner-group client communication link after a new main link is established between the terminal and the target access point.

[0039] Specifically, once the new primary link (i.e., the new Infra link) is established between the terminal and the target access point, it means that the terminal has successfully connected to the target access point, and the core steps of roaming handover have been completed. At this point, the fallback function of the group owner-group client communication link between the original access point and the terminal has ended, and both parties execute the link release process to reclaim relevant resources.

[0040] The establishment of the group owner-group client communication link occupies the VAP resources (GO role and GC role) of the original access point and terminal. After roaming is completed, these resources should be released in time to restore them to an idle state, so that they can be used by other P2P services (such as Wi-Fi Direct file transfer, screen casting, etc.) to avoid long-term resource occupation.

[0041] The release steps are as follows: the terminal sends a P2P deassociation frame to the original access point, terminating the session state of the P2P group; both parties release the GC / GO role VAP resources allocated to the P2P link, restoring the P2P VAP to an idle state; the terminal switches the service data transmission path to the newly established Infra mode main link with the target access point, restoring the normal terminal-AP communication mode. The roaming process is thus completed, achieving zero packet loss throughout.

[0042] In some optional embodiments, releasing the group owner-group client communication link includes: releasing the group owner-group client communication link after the original access point has completed sending all cached messages through the group owner-group client communication link.

[0043] Specifically, once the original access point has completed sending all cached messages through the group owner-group client communication link, and has confirmed that each frame has been successfully received by the terminal based on the retransmission mechanism after the transmission is interrupted, the original access point and the terminal will respectively execute the P2P link release process after the new link is ready.

[0044] Example 2: The seamless roaming method of this embodiment can be applied to terminals with communication, computing, and data storage capabilities. Its specific process can be as follows: Figure 2 As shown, it includes: Step 210: In response to receiving the group owner-group client communication link establishment instruction sent by the original access point after determining that roaming needs to be triggered, establish a group owner-group client communication link with the original access point; Step 220: Before the terminal completes the connection with the target access point, it communicates with the original access point through the group owner-group client communication link. The target access point is the target to which the terminal will switch roaming.

[0045] Specifically, in response to receiving the group owner-group client communication link establishment instruction sent by the original access point after determining that roaming needs to be triggered, the terminal establishes a group owner-group client communication link with the original access point. The establishment instruction itself implies that the original access point has made a decision based on the roaming triggering conditions. The terminal, as the receiver, executes the Wi-Fi Direct P2P group joining process according to the instruction, forming a point-to-point direct communication channel with the original access point as the GO and the terminal as the GC. The establishment of this channel is achieved by reusing the existing VAP resources on the terminal, without the need for additional hardware support.

[0046] During the roaming transition period, before the terminal has established a connection with the target access point that serves as the roaming handover target, the terminal maintains communication with the original access point through the owner-client communication link of the group, and receives downlink data forwarded by the original access point, thereby maintaining data reception capability during the deterioration or interruption of the main link, until the terminal and the target access point complete the construction of a new main link.

[0047] Steps 210 and 220 are linked together, forming a complete communication logic in which the terminal side passively responds to cooperate with the original access point to establish a P2P direct connection channel, and continuously receives data through this channel during the roaming transition period.

[0048] In some optional embodiments, communicating with the original access point via the group owner-group client communication link includes: during the existence of the main link between the terminal and the original access point, when the communication quality of the main link is substandard and the terminal has not established a connection with the target access point, simultaneously using the main link and the group owner-group client communication link to perform redundant communication with the original access point.

[0049] Specifically, when the main link between the terminal and the original access point is still in existence but the communication quality is substandard, and the terminal has not yet established a new connection with the target access point, the terminal does not passively wait for the main link to be completely interrupted before switching to the backup channel. Instead, within the time window when the main link can still carry data, the terminal simultaneously uses the main link and the established group owner-group client communication link to conduct redundant communication with the original access point. That is, the terminal simultaneously receives the same data packets sent by the original access point through two heterogeneous links. Thus, before the main link is finally interrupted due to continuous deterioration, the terminal has already obtained parallel data reception capability through the P2P direct connection channel.

[0050] The core of this embodiment is to advance the use of the GO-GC direct link from "backup after disconnection" to "redundancy before disconnection", so that the terminal can obtain dual data reception paths during the transition phase when the main link is still alive but unreliable. This avoids the time blind spot introduced by waiting for the main link to be completely disconnected before starting the backup link in the traditional solution, and provides the necessary cooperation on the terminal side to achieve zero packet loss.

[0051] In some optional embodiments, the method further includes: deduplicating and reordering data packets from the main link and the group owner-group client communication link.

[0052] Specifically, because the original access point sends the same service data packets to the terminal simultaneously through two links in redundant communication mode, the terminal will receive two identical packet copies from the two heterogeneous links within the same time period. Without deduplication, the upper-layer protocol stack will receive a large amount of duplicate data, wasting memory and CPU resources and potentially interfering with the normal operation of the TCP / IP protocol stack. Meanwhile, due to differences in physical layer characteristics, channel contention, and retransmission mechanisms between the main link (usually the 5GHz band) and the group owner-group client communication link (which can be a different band, such as 2.4GHz), the arrival order of the two identical packets at the terminal may be disordered. That is, the later-sent packet may arrive first, and the earlier-sent packet may arrive later. Without reordering, the upper-layer application will receive a disordered data stream, which will severely impact order-sensitive services such as real-time audio and video and TCP transmission. Therefore, the terminal sets up a deduplication buffer and a reordering buffer in the MAC layer or the upper-layer protocol stack. The received data packets are compared according to their sequence numbers, duplicate copies are discarded, and out-of-order data packets are buffered and sorted. Once they are complete and ordered, they are then handed over to the upper-layer protocol for processing.

[0053] This processing mechanism, together with the dual-path redundant transmission on the original access point side, forms a complete lossless data transmission closed loop, ensuring that even if the two links experience different degrees of jitter and latency differences during the roaming transition period, the terminal's upper-layer services can still obtain a complete and orderly data stream, thus achieving zero packet loss and seamless roaming.

[0054] In some optional embodiments, the method further includes: when the main link is disconnected, communicating with the original access point through the group owner-group client communication link. This communication mechanism is similar to the "fallback" mechanism in Embodiment 1, and will not be described in detail here to avoid repetition.

[0055] In some optional embodiments, establishing a connection with the target access point includes: determining the target access point based on roaming assistance information, and reusing an established authentication context during the association process with the target access point to skip the full authentication process.

[0056] Specifically, the process of the terminal connecting with the target access point is achieved through a fast roaming mechanism, which includes two steps: determining the target access point based on roaming assistance information and reusing the existing authentication context during the association process to skip the complete authentication process.

[0057] Among them, roaming assistance information is used to provide the terminal with a basis for screening candidate APs. It can be a neighbor report provided by the original access point through the 802.11k protocol, which contains basic information such as the channel number and BSSID of the surrounding APs. It can also be a BTM suggestion provided by the original access point through the 802.11v protocol, which carries a list of recommended target access points for handover. Based on the above information, the terminal can quickly lock the optimal target access point as the handover target without scanning all channels by itself.

[0058] After the target access point is determined, the terminal does not re-execute the complete 802.1X / EAP authentication and four-way handshake process when associating with the AP. Instead, it reuses the established authentication context: that is, the PMK (Paired Master Key) and its derived key levels (such as PMK-R0, PMK-R1) generated by the terminal through complete authentication when it first associates with the network are carried in the reassociation request frame. This allows the target access point to quickly find the corresponding key material based on the local cache of the PMKID or through cooperation with the original access point. This allows the terminal to skip the complete EAP process and the complete four-way handshake interaction with the authentication server and directly derive the new PTK (Paired Temporary Key) for data encryption.

[0059] Through the above mechanism, the terminal can directly reuse the existing security context during association without having to establish any connection with the target access point in advance, compressing the roaming authentication latency to the tens of milliseconds level, achieving rapid switching while ensuring security. In conjunction with the fallback transmission of the group owner-group client communication link, it jointly ensures that the terminal's data is not interrupted and services are not perceived during the roaming transition period.

[0060] In some optional embodiments, after establishing a connection with the target access point, the method further includes: switching the service data path to the main link established with the target access point, and releasing the group owner-group client communication link.

[0061] Specifically, the timing and specific release process for releasing the group owner-group client communication link are similar to those in Embodiment 1. To avoid repetition, the details will not be repeated here.

[0062] Example 3: Based on the above embodiments, this embodiment provides an application example of a seamless roaming method. A seamless roaming system is provided, comprising: The original access point is used to establish a group owner-group client communication link with the terminal in response to the determination that roaming needs to be triggered; A terminal, configured to receive data forwarded by the original access point via the group owner-group client communication link; The target access point is used to establish a connection with the terminal. The group owner-group client communication link is used to continuously forward data before the terminal completes the connection with the target access point, where the target access point is the target to which the terminal is about to switch roaming.

[0063] Modern WiFi chips typically integrate multiple Virtual Access Point (VAP) hardware resources, supporting a single physical device to virtualize multiple logically independent interfaces at the MAC layer. Terminal devices generally have at least three VAP resources, respectively implementing terminal tion mode, SoftAP mode, and WiFi P2P GO / GC mode; access point (AP) devices have even more VAP resources and can be configured into various modes as needed.

[0064] In existing technologies, WiFi Direct peer-to-peer connection technology is mainly used for data interaction between terminals and has not been applied to compensate for packet loss during roaming. This embodiment, based on research on network device chips, addresses the packet loss problem caused by communication link disconnection during roaming. It proposes to establish a group owner-group client communication link (GO-GC direct link) between the original access point and the terminal to compensate for packet loss during the disconnection of the link with the original access point and the re-establishment of the link with the target access point.

[0065] like Figure 3 The diagram shown illustrates the zero-packet-loss roaming process provided by the seamless roaming system. The specific implementation steps include the following: (1) Roaming Trigger (Initiated by AP) When a terminal device moves to the edge of the signal coverage area of ​​its current associated access point (hereinafter referred to as "original access point or original AP"), the original access point (original AP) monitors the communication quality of the main link (preferably the 5GHz band) with the terminal in real time according to the signaling process defined by the 802.11k / v / r standard protocol. Specifically, it obtains parameters such as RSSI, signal-to-noise ratio, bit error rate, and transmission delay reported by the terminal through the 802.11k Radio Resource Measurement (RRM) mechanism.

[0066] When the RSSI is detected to be below a preset threshold (or the bit error rate is higher than the threshold, or the latency exceeds the threshold), the original access point determines that roaming needs to be triggered. To avoid the ping-pong effect, the roaming trigger threshold can be appropriately increased. Subsequently, the original access point actively sends a BSS transition management request frame to the terminal through the BSS transition management (BTM) function defined in the 802.11v protocol. This frame contains a list of neighbor AP candidates (including BSSID, operating channel, signal strength, load status, etc.) to guide the terminal to roam to the target access point. At the same time, the original access point can send a neighbor report to the terminal through the 802.11k protocol, providing detailed information about the neighbor APs.

[0067] (2) P2P (GO-GC) fallback link establishment (initiated by the terminal side) After receiving the BTM request from the original access point, the terminal immediately initiates the pre-establishment process for the P2P (Wi-Fi Direct) fallback link. The terminal utilizes a set of independent VAP resources in its chip, configures the VAP in P2P Device mode, and actively initiates the establishment of a P2P connection with the original access point.

[0068] The establishment of a P2P link follows the four-stage process of the Wi-Fi Direct standard protocol: P2P device discovery (alternating listening and scanning on the 2.4GHz social channel to exchange P2P capability information), GO negotiation (a three-frame handshake of GO negotiation request / response / acknowledgment, the default GO intent value of the original access point is 15 to force it to the GO role, and the GO intent value of the terminal is 0 to force it to the GC role), P2P configuration (the WPS configuration process completes authentication and key distribution), and P2P connection establishment (standard 802.11 association and four-way handshake to derive PTK / GTK, and establish an encrypted P2P direct link).

[0069] The P2P link preferentially uses a different channel frequency band than the main link to avoid co-channel interference, and can be selected automatically based on duty cycle information. During this stage, the main link (Infra mode terminal-AP link) between the terminal and the original access point continues to maintain normal communication, and service data continues to be transmitted through the main link. The P2P link (GO-GC direct link) is in a ready state, transmitting only a small amount of link keep-alive signaling.

[0070] (3) Redundant transmission (the quality of the main link continues to deteriorate, but it has not yet been disconnected) The original access point continuously monitors the quality of the main link. When it detects that the communication quality of the main link is continuously deteriorating and the terminal has not yet established a valid association with the target access point, the original access point activates a redundant transmission mechanism: all service data packets destined for the terminal are simultaneously transmitted on both the main link and the P2P link.

[0071] The terminal receives data packets from the two links through the terminal VAP and GC VAP respectively. It performs deduplication and reordering based on the message sequence number and IP packet ID, selects valid data packets and submits them to the upper-layer protocol stack, and discards duplicate packets.

[0072] (4) Backup transmission after the main link is disconnected (including retransmission based on interruption after transmission completion) As the terminal continues to move away from the original access point, the main link (5GHz Infra link) signal further attenuates until the link is disconnected. At this point, if the terminal has not yet completed association authentication with the target access point, the MAC layer reports the main link unavailable to the upper layer via the MLME state change primitive. The terminal immediately switches all uplink service data to the P2P link for transmission.

[0073] At the same time, the original access point initiates a fallback transmission mechanism: it sends all uncompleted service messages and control messages in its own transmission buffer that are destined for the terminal to the terminal through the established P2P link (GO-GC direct link).

[0074] During fallback transmission, the original access point utilizes a retransmission mechanism based on interrupted transmission completion to ensure reliable message transmission: After each data frame is transmitted on the P2P link, the underlying Wi-Fi chip reports the transmission completion status to the MAC layer. For frames that fail to transmit, the MAC layer reschedules them for transmission in its local retransmission queue until the maximum retransmission limit (defined by dot11ShortRetryLimit and dot11LongRetryLimit) is reached. This retransmission mechanism is independent of TCP retransmission, resolving packet loss caused by channel interference at the MAC layer, ensuring that all messages in the original access point's buffer are reliably delivered to the terminal. Retransmission parameters can be configured differently based on the service type (VoIP, video streaming, file transfer).

[0075] (5) New link establishment (terminal and target access point association) While or after the P2P link performs fallback transmission (the two can be performed in parallel), the terminal continuously scans for surrounding AP signals. Based on the 802.11k neighbor report and the candidate AP list recommended by 802.11v BTM, it prioritizes searching for the target access point and initiates the Fast BSS Transition process defined by 802.11r. Through the pre-established master key hierarchy (PMK-R0 / PMK-R1 derived chain) and PMKID, the complete 802.1X / EAP authentication and four-way handshake are skipped during the re-association process. The target access point association is completed only through FT authentication frames and FT association frames, compressing the roaming authentication latency to the tens of milliseconds level. Finally, the terminal establishes a stable new master link with the target access point (preferably in the 5GHz band).

[0076] (6) P2P link release (released after all confirmation messages have been successfully sent) Once the original access point has completed sending all buffered packets via the P2P link, and the retransmission mechanism based on interrupted transmission confirms that each frame has been successfully received by the terminal, both the original access point and the terminal execute the P2P link release procedure. If the new link has not yet been established, the release can be performed only after the new link is ready.

[0077] The release steps are as follows: the terminal sends a P2P deauthentication / disassociation frame to the original access point, terminating the P2P group's session state; both parties release the GC / GO role VAP resources allocated to the P2P link, restoring the P2P VAP to an idle state; the terminal switches its service data transmission path to the newly established Infra mode main link with the target access point, restoring normal terminal-AP communication mode. The roaming process is thus completed, achieving zero packet loss throughout.

[0078] In some alternative embodiments, the Infra link based on the DBDC / dual WiFi module can also be implemented in the following ways: By utilizing the capabilities of the DBDC (Dual Band Dual Concurrent) chip or dual independent WiFi RF modules, the terminal can connect to two WiFi APs simultaneously, establishing two independent Infra physical paths for transmission and reception (primary link + backup link). When the communication quality of one link degrades or disconnects, the terminal automatically switches the service traffic to the backup link.

[0079] In some optional embodiments, the fallback link scheme of WiFi Direct can also be replaced by the NAN protocol: the WiFi Aware / NAN (Neighbor Awareness Networking) protocol can replace the WiFi DirectGO / GC protocol in this invention as the underlying direct connection technology for the fallback link. The terminal and the original access point perform device discovery and establish a direct connection link through the NAN protocol. When the main link is disconnected, data is transmitted through the direct connection channel established by NAN.

[0080] NAN's current applications are mainly focused on the device discovery and service awareness stages, but in terms of protocol capabilities, NAN has the potential to become a replacement for WiFi Direct as the underlying P2P protocol, and is an alternative equivalent technology path.

[0081] Additional information: The NAN (Neighbor Awareness Networking) standard was officially released by the Wi-Fi Alliance in 2015 and is the core technology of the Wi-Fi Aware certification program. The related communication standard specifications are based on IEEE 802.11mc. Currently, the main commercial applications of NAN include: device discovery optimization, location-aware precise message push, and low-power self-organizing networks for IoT devices.

[0082] In some optional embodiments, a fallback solution based on cellular network auxiliary links is also provided: utilizing the terminal's simultaneous WiFi and cellular network interfaces, during WiFi roaming, intelligent link aggregation / splitting technology is used to distribute and converge service data simultaneously on both WiFi and cellular network links. When the WiFi link is lost due to roaming, service data automatically continues to be transmitted through the cellular network link, achieving seamless switching.

[0083] In summary, the seamless roaming method of this embodiment has at least the following beneficial effects: (1) Current mainstream WiFi 5 / 6 / 7 commercial chips natively have multiple sets of VAP hardware virtualization resources built in, naturally supporting the configuration of multiple VAPs and multiple network roles (AP / terminal, GO / GC) on the same device, without the need to redesign the chip hardware; (2) It is fully based on the standard 802.11 WiFi protocol, WiFi Direct GO / GC protocol, and 802.11k / v / r roaming protocol. No custom private protocol is required. It can be seamlessly integrated into the existing WiFi standard system and included in the operator's FTTR roaming standard scheme.

[0084] (3) During the roaming triggering phase, a parallel redundant transmission channel is established between the Wi-Fi main link (Infra mode) and the P2P direct link (GO-GC mode). When the terminal is located at the edge of the AP coverage area and the main link signal quality degrades, the original access point will send service packets on both links simultaneously, and the terminal side will receive valid data through a deduplication mechanism. This mechanism significantly improves the reliability of signal transmission in edge areas and avoids communication interruptions caused by fluctuations in the main link.

[0085] (4) After the terminal completes the establishment of a new main link with the target access point, the original access point has not yet released the P2P direct link. This application utilizes this link and, based on the transmission completion interruption mechanism, sends and retransmits all unacknowledged buffered packets in the original access point's transmission buffer to the terminal. After the terminal confirms that all packets have been received correctly, both parties release the P2P link resources. This mechanism achieves reliable transmission of packets in the original access point's buffer, fundamentally solving the data packet loss problem during roaming and achieving the goal of zero packet loss.

[0086] Example 4: Another embodiment of this application relates to a primary access point. The implementation details of the primary access point in this embodiment are described below. The following content is for ease of understanding and is not essential for implementing this solution. A schematic diagram of the primary access point in this embodiment can be seen as follows: Figure 4 As shown, it includes a first establishment module 410 and a first communication module 420.

[0087] The first establishment module 410 is used to establish a group owner-group client communication link with the terminal in response to the determination that roaming needs to be triggered. The first communication module 420 is used to communicate with the terminal through the group owner-group client communication link before the terminal completes the connection with the target access point, wherein the target access point is the target to which the terminal is about to switch roaming.

[0088] It is worth mentioning that all modules involved in this embodiment are logical modules. In practical applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. Furthermore, to highlight the innovative aspects of this application, this embodiment does not introduce units that are not closely related to solving the technical problems proposed in this application; however, this does not mean that other units are absent in this embodiment.

[0089] In some alternative embodiments, the original access point can implement the seamless roaming method described in any of the above embodiments.

[0090] Example 5: Another embodiment of this application relates to a terminal. The implementation details of the terminal in this embodiment are described below. The following content is for ease of understanding and is not essential for implementing this solution. A schematic diagram of the terminal in this embodiment can be shown as follows: Figure 5 As shown, it includes a second establishment module 510 and a second communication module 520.

[0091] The second establishment module 510 is used to establish a group owner-group client communication link with the original access point in response to receiving a group owner-group client communication link establishment instruction sent by the original access point after determining that roaming needs to be triggered; The second communication module 520 is used to communicate with the original access point through the group owner-group client communication link before the terminal completes the connection with the target access point, wherein the target access point is the target to which the terminal is about to switch roaming.

[0092] It is worth mentioning that all modules involved in this embodiment are logical modules. In practical applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. Furthermore, to highlight the innovative aspects of this application, this embodiment does not introduce units that are not closely related to solving the technical problems proposed in this application; however, this does not mean that other units are absent in this embodiment.

[0093] In some alternative embodiments, the terminal is capable of implementing the seamless roaming method described in any of the above embodiments.

[0094] Example 6: Another embodiment of this application relates to an electronic device, including: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the seamless roaming methods in the above embodiments.

[0095] In this embodiment, the memory and processor are connected via a bus, which can include any number of interconnected buses and bridges, connecting various circuits of one or more processors and the memory together. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be further described in this embodiment. A bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0096] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0097] Example 7: Another embodiment of this application relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the method embodiments described above.

[0098] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0099] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A seamless roaming method, characterized in that, Applied to the original access point, including: In response to the determination that roaming needs to be triggered, a group owner-group client communication link is established with the terminal; Before the terminal completes the connection with the target access point, it communicates with the terminal through the group owner-group client communication link. The target access point is the target to which the terminal will switch roaming.

2. The seamless roaming method according to claim 1, characterized in that, The communication with the terminal via the group owner-group client communication link includes: During the existence of the main link between the terminal and the original access point, if the communication quality of the main link is detected to be substandard and the terminal fails to establish a connection with the target access point, redundant communication is performed with the terminal using both the main link and the group owner-group client communication link.

3. The seamless roaming method according to claim 2, characterized in that, The communication with the terminal via the group owner-group client communication link further includes: When the main link is disconnected, communication with the terminal is achieved through the group owner-group client communication link.

4. The seamless roaming method according to claim 2, characterized in that, The group owner-group client communication link uses a different channel frequency band than the main link.

5. The seamless roaming method according to any one of claims 2-4, characterized in that, Also includes: Once the new main link is established between the terminal and the target access point, the group owner-group client communication link is released.

6. A seamless roaming method, characterized in that, Applied to terminals, including: In response to receiving a group owner-group client communication link establishment instruction sent by the original access point after determining that roaming needs to be triggered, a group owner-group client communication link is established with the original access point; Before the terminal completes the connection with the target access point, it communicates with the original access point through the group owner-group client communication link. The target access point is the target to which the terminal will switch roaming.

7. The seamless roaming method according to claim 6, characterized in that, The communication with the original access point via the group owner-group client communication link includes: During the existence of the main link between the terminal and the original access point, if the communication quality of the main link is substandard and the terminal fails to establish a connection with the target access point, redundant communication with the original access point is simultaneously performed using the main link and the group owner-group client communication link.

8. The seamless roaming method according to claim 7, characterized in that, Also includes: Data packets from the main link and the group owner-group client communication link are deduplicated and reordered.

9. The seamless roaming method according to claim 6, characterized in that, Establishing a connection with the target access point includes: The target access point is determined based on roaming assistance information, and the established authentication context is reused during the association process with the target access point to skip the complete authentication process.

10. The seamless roaming method according to claim 6, characterized in that, After establishing a connection with the target access point, the process also includes: Switch the business data path to the main link established with the target access point, and release the group owner-group client communication link.

11. A primary access point, characterized in that, include: The first module is used to establish a group owner-group client communication link with the terminal in response to the determination that roaming needs to be triggered. The first communication module is used to communicate with the terminal through the group owner-group client communication link before the terminal completes the connection with the target access point, wherein the target access point is the target to which the terminal is about to switch roaming.

12. A terminal, characterized in that, include: The second establishment module is used to establish a group owner-group client communication link with the original access point in response to receiving a group owner-group client communication link establishment instruction sent by the original access point after determining that roaming needs to be triggered; The second communication module is used to communicate with the original access point through the group owner-group client communication link before the terminal completes the connection with the target access point, where the target access point is the target to which the terminal is about to switch roaming.

13. A seamless roaming system, characterized in that, include: The original access point is used to establish a group owner-group client communication link with the terminal in response to the determination that roaming needs to be triggered; A terminal, configured to receive data forwarded by the original access point via the group owner-group client communication link; The target access point is used to establish a connection with the terminal. The group owner-group client communication link is used to continuously forward data before the terminal completes the connection with the target access point, where the target access point is the target to which the terminal is about to switch roaming.

14. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the seamless roaming method according to any one of claims 1-10.

15. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the seamless roaming method as described in any one of claims 1-10.

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