Seamless roaming process of wireless networks

Abstract

A station (STA) in a wireless network is attached to a seamless roaming domain to enable seamless roaming between one or more access points (APs) attached to the seamless roaming domain without (re)association. The seamless roaming domain architecture provides multiple AP MLDs that interact with each other for mobility management and includes a logical / control entity that can interact with one or more AP MLDs to enable non-AP MLDs to roam from one AP MLD to another.

Description

Technical Field

[0001] This disclosure generally relates to wireless communication systems, and more specifically, for example, but not limited to, to seamless roaming processes in wireless networks. Background Technology

[0002] Since the late 1990s, Wireless Local Area Network (WLAN) technology has continuously evolved, with data transmission rates steadily increasing, and has experienced sustained growth across various markets, including homes, businesses, and hotspots. WLAN enables devices to access the Internet in the 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz frequency bands. WLAN is based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The IEEE 802.11 series of standards aims to improve the speed and reliability of wireless networks and expand their operational range.

[0003] The demand for WLAN devices is increasing to support a wide range of latency-sensitive or real-time applications, such as augmented reality (AR), robotics, artificial intelligence (AI), cloud computing, and autonomous vehicles. To achieve the extremely low latency and extremely high throughput required for these applications, multi-link operation (MLO) has been recommended in WLANs. A WLAN is formed by WLAN devices within a limited area, such as a home, school, apartment, or office building. Each WLAN device can have one or more stations (STAs), such as access point (AP) STAs and non-access point (non-AP) STAs.

[0004] Multi-Link Optimization (MLO) enables non-AP multi-link devices (MLDs) to establish multiple links with AP MLDs. Each of these multiple links can independently enable channel access and frame exchange between the non-AP MLD and the AP MLD, thereby reducing latency and increasing throughput.

[0005] The descriptions in the background section should not be assumed to be prior art simply because they are presented therein. The background section may describe various aspects or embodiments of this disclosure. Summary of the Invention

[0006] One aspect of this disclosure provides a station (STA) in a wireless network, comprising: a memory; and a processor coupled to the memory. The processor is configured to send a first frame to a first access point (AP) attached to a seamless roaming domain to associate with the seamless roaming domain, wherein the seamless roaming domain communicates with one or more APs attached to the seamless roaming domain, the one or more APs including the first AP and a second AP. The processor is configured to roam to a second AP attached to the seamless roaming domain, wherein the seamless roaming domain performs a context transfer from the first AP to the second AP.

[0007] In some examples, context transfer transmits information related to at least one of the following: sequence number (SN) / packet number (PN) information, block acknowledgment protocol information, quality of service (QoS) settings, target wake-up time (TWT) settings, emergency prepared communication service (EPCS) settings, or traffic identifier (TID) to link mapping information.

[0008] In some examples, the seamless roaming domain has an identifier.

[0009] In some examples, seamless roaming domains perform data transfers from the first AP to the second AP.

[0010] In some examples, the processor is further configured to send a second frame that includes a reconfiguration message that adds a link between the STA and a second AP or removes a link between the STA and the first AP.

[0011] In some examples, the processor is further configured to receive a second frame from one or more APs attached to the seamless roaming domain, the second frame announcing the seamless roaming domain.

[0012] In some examples, the second frame includes i) the Media Access Control (MAC) identifier of the Seamless Roaming Domain, ii) one or more MAC addresses of other APs that are part of the Seamless Roaming Domain, or iii) the capabilities of other APs that are part of the Seamless Roaming Domain.

[0013] In some examples, the processor is also configured to send a second frame via a second AP to disassociate from the seamless roaming domain.

[0014] One aspect of this disclosure provides a first access point (AP) in a wireless network, the first access point including: a memory; and a processor coupled to the memory. The processor is configured to receive a first frame from a slave station (STA) to be associated with a seamless roaming domain to which the first AP belongs, wherein the seamless roaming domain communicates with one or more APs attached to the seamless roaming domain, the one or more APs including the first AP and a second AP. The processor is configured to determine that the STA has roamed to a second AP attached to the seamless roaming domain and to perform a context transfer to the second AP.

[0015] In some examples, context transfer transmits information related to at least one of the following: sequence number (SN) / packet number (PN) information, block acknowledgment protocol information, quality of service (QoS) settings, target wake-up time (TWT) settings, emergency prepared communication service (EPCS) settings, or traffic identifier (TID) to link mapping information.

[0016] In some examples, the seamless roaming domain has an identifier.

[0017] In some examples, seamless roaming domains perform data transfers from the first AP to the second AP.

[0018] In some examples, the processor is further configured to send a second frame including a reconfiguration message that adds a link between the STA and a second AP or deletes a link between the STA and the first AP.

[0019] In some examples, the processor is also configured to send a second frame to the STA, the second frame announcing the seamless roaming domain.

[0020] In some examples, the second frame includes i) the Media Access Control (MAC) identifier of the Seamless Roaming Domain, ii) one or more MAC addresses of other APs that are part of the Seamless Roaming Domain, or iii) the capabilities of other APs that are part of the Seamless Roaming Domain.

[0021] One aspect of this disclosure provides a method implemented by a computer for communication by a station (STA) in a wireless network. The method includes sending a first frame to a first access point (AP) attached to a seamless roaming domain to associate with the seamless roaming domain, wherein the seamless roaming domain communicates with one or more APs attached to the seamless roaming domain, the one or more APs including the first AP and a second AP. The method includes roaming to a second AP attached to the seamless roaming domain, wherein the seamless roaming domain performs a context transfer from the first AP to the second AP.

[0022] In some examples, context transfer transmits information related to at least one of the following: sequence number (SN) / packet number (PN) information, block acknowledgment protocol information, quality of service (QoS) settings, target wake-up time (TWT) settings, emergency prepared communication service (EPCS) settings, or traffic identifier (TID) to link mapping information.

[0023] In some examples, the seamless roaming domain has an identifier.

[0024] In some examples, seamless roaming domains perform data transfers from the first AP to the second AP.

[0025] In some examples, the method further includes sending a second frame that includes a reconfiguration message that adds a link between the STA and a second AP or deletes a link between the STA and a first AP.

[0026] One aspect of this disclosure provides a computer-implemented method for communicating with a first access point (AP) in a wireless network. The method includes receiving a first frame from a slave station (STA) associated with a seamless roaming domain to which the first AP belongs, wherein the seamless roaming domain communicates with one or more APs attached to the seamless roaming domain, the one or more APs including the first AP and a second AP. The method may include determining that the STA has roamed to a second AP attached to the seamless roaming domain and performing a context transfer to the second AP.

[0027] In some examples, context transfer transmits information related to at least one of the following: sequence number (SN) / packet number (PN) information, block acknowledgment protocol information, quality of service (QoS) settings, target wake-up time (TWT) settings, emergency prepared communication service (EPCS) settings, or traffic identifier (TID) to link mapping information.

[0028] In some examples, the seamless roaming domain has an identifier.

[0029] In some examples, seamless roaming domains perform data transfers from the first AP to the second AP.

[0030] In some examples, the method further includes receiving a second frame that includes a reconfiguration message that adds a link between the STA and a second AP or deletes a link between the STA and a first AP.

[0031] In some examples, the method further includes sending a second frame to the STA, the second frame announcing the seamless roaming domain.

[0032] In some examples, the second frame includes i) the Media Access Control (MAC) identifier of the Seamless Roaming Domain, ii) one or more MAC addresses of other APs that are part of the Seamless Roaming Domain, or iii) the capabilities of other APs that are part of the Seamless Roaming Domain. Attached Figure Description

[0033] Figure 1 An example of a wireless network according to an embodiment is shown.

[0034] Figure 2a An example of an AP according to an embodiment is shown.

[0035] Figure 2b An example of a STA according to an embodiment is shown.

[0036] Figure 3 An example of multi-link communication operation according to an embodiment is shown.

[0037] Figure 4The various stages of the mobility handover process according to an embodiment are shown.

[0038] Figure 5 A roaming architecture including a parallel stack is shown according to an embodiment.

[0039] Figure 6 A flowchart illustrating an example process for associating with a seamless roaming domain according to an embodiment is shown.

[0040] In one or more embodiments, not all components shown in each figure may be required, and one or more embodiments may include additional components not shown in the figures. Changes may be made to the arrangement and type of components without departing from the scope of this disclosure. Within the scope of this disclosure, additional components, different components, or fewer components may be used. Detailed Implementation

[0041] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various embodiments and not as representing the only embodiments in which the subject matter of this disclosure can be practiced. Rather, this detailed description includes specific details intended to provide a thorough understanding of the subject matter of the invention. Those skilled in the art will recognize that the described embodiments can be modified in a variety of different ways without departing from the scope of this disclosure. Accordingly, the drawings and description are to be considered illustrative in nature and not restrictive. Similar reference numerals refer to similar elements.

[0042] The following description relates to specific embodiments used to describe the innovative aspects of this disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in a variety of different ways. The examples in this disclosure are based on WLAN communications according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, including the IEEE 802.11be standard and any future revisions to the IEEE 802.11 standard. However, the described embodiments can be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals according to the IEEE 802.11 standard, Bluetooth standard, Global System for Mobile Communications (GSM), GSM / General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Relay Radio (TETRA), Wideband Code Division Multiple Access (W-CDMA), Optimized Data Evolution (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, High-Speed ​​Packet Access (HSPA), High-Speed ​​Downlink Packet Access (HSDPA), High-Speed ​​Uplink Packet Access (HSUPA), Evolved High-Speed ​​Packet Access (HSPA+), Long Term Evolution (LTE), 5G NR (New Radio), Analog Mobile Phone Systems (AMPS), or other known signals used for communication in wireless networks, cellular networks, or Internet of Things (IoT) networks, such as systems using 3G, 4G, 5G, 6G, or further implementations thereof.

[0043] Depending on the network type, other well-known terms may be used instead of "access point" or "AP," such as "router" or "gateway." For convenience, the term "AP" is used in this disclosure to refer to a network infrastructure component that provides wireless access to remote terminals. In a WLAN, since the AP also contends for the wireless channel, the AP may also be referred to as a STA. Additionally, depending on the network type, other well-known terms may be used instead of "station" or "STA," such as "mobile station," "subscriber station," "remote terminal," "user equipment," "wireless terminal," or "user equipment." For convenience, the terms "station" and "STA" as used in this disclosure refer to a remote wireless device that wirelessly accesses an AP or contends for a wireless channel in a WLAN, whether the STA is a mobile device (e.g., a mobile phone or smartphone) or is generally considered a fixed device (e.g., a desktop computer, AP, media player, fixed sensor, television, etc.).

[0044] Multilink Operation (MLO) is a key feature currently being developed by standards bodies in IEEE 802.11be for next-generation Ultra High Throughput (EHT) Wi-Fi systems. Wi-Fi devices that support MLO are called Multilink Devices (MLDs). Through MLO, a non-AP MLD can discover, authenticate, associate with, and establish multiple links to an AP MLD. Channel access and frame switching can occur on each link between the AP MLD and the non-AP MLD.

[0045] Figure 1 An example of a wireless network 100 according to an embodiment is shown. Figure 1 The illustrated embodiment of the wireless network 100 is for illustrative purposes only. Other embodiments of the wireless network 100 may be used without departing from the scope of this disclosure.

[0046] like Figure 1 As shown, wireless network 100 may include multiple wireless communication devices. Each wireless communication device may include one or more stations (STAs). An STA can be a logical entity, i.e., a separately addressable instance of the Media Access Control (MAC) layer and Physical (PHY) layer interfaces to the wireless medium. STAs can be categorized as Access Point (AP) STAs and Non-Access Point (Non-AP) STAs. An AP STA can be an entity that provides access to distributed system services to associated STAs via the wireless medium. A Non-AP STA can be a STA not included within an AP-STA. For the purpose of simplification, an AP STA may be referred to as an AP, and a Non-AP STA may be referred to as a STA. Figure 1 In the examples, AP 101 and AP 103 are wireless communication devices, each of which may include one or more AP STAs. In these embodiments, AP 101 and 103 may be AP multilink devices (MLDs). Similarly, STAs 111-114 are wireless communication devices, each of which may include one or more non-AP STAs. In these embodiments, STAs 111-114 may be non-AP MLDs.

[0047] APs 101 and 103 can also communicate with at least one network 130, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network. AP 101 provides wireless access to network 130 for multiple stations (STAs) 111-114, covering an area 120 of AP 101. APs 101 and 103 can communicate with each other using Wi-Fi or other WLAN communication technologies, and also communicate with each STA.

[0048] Depending on the network type, other well-known terms may be used instead of "access point" or "AP," such as "router" or "gateway." For convenience, the term "AP" is used in this disclosure to refer to a network infrastructure component that provides wireless access to remote terminals. In a WLAN, since the AP also contends for the wireless channel, the AP may also be referred to as a STA. Additionally, depending on the network type, other well-known terms may be used instead of "station" or "STA," such as "mobile station," "subscriber station," "remote terminal," "user equipment," "wireless terminal," or "user equipment." For convenience, the terms "station" and "STA" as used in this disclosure refer to a remote wireless device that wirelessly accesses an AP or contends for a wireless channel in a WLAN, whether the STA is a mobile device (e.g., a mobile phone or smartphone) or is generally considered a fixed device (e.g., a desktop computer, AP, media player, fixed sensor, television, etc.).

[0049] exist Figure 1 In the diagram, dashed lines indicate the approximate extent of the coverage areas 120 and 125 of APs 101 and 103, which are illustrated as generally circular for illustrative and explanatory purposes. It should be clearly understood that the coverage areas associated with APs, such as coverage areas 120 and 125, may have other shapes, including irregular shapes, depending on the configuration of the APs.

[0050] As described in more detail below, one or more APs may include circuitry and / or programming for managing MU-MIMO and OFDMA channel probes in a WLAN. Although Figure 1 The image shows an example of a wireless network 100, but more details can be found on the image. Figure 1 Various modifications can be made. For example, wireless network 100 can include any number of APs and any number of STAs in any suitable arrangement. Furthermore, AP 101 can communicate directly with any number of STAs and provide those STAs with wireless broadband access to network 130. Similarly, each AP 101 and 103 can communicate directly with network 130 and provide STAs with direct wireless broadband access to network 130. Additionally, AP 101 and / or 103 can provide access to other or additional external networks, such as external telephone networks or other types of data networks.

[0051] Figure 2a An example of AP 101 according to an embodiment is shown. Figure 2a The embodiment of AP 101 shown is for illustrative purposes only, and Figure 1 The AP103 in the example can have the same or similar configuration. However, wireless access points (APs) have various configurations, and Figure 2a This disclosure is not intended to limit the scope of any particular AP implementation.

[0052] like Figure 2a As shown, AP 101 may include multiple antennas 204a-204n, multiple radio frequency (RF) transceivers 209a-210n, transmit (TX) processing circuitry 214, and receive (RX) processing circuitry 219. AP 101 may also include a controller / processor 224, a memory 229, and a backhaul or network interface 234. RF transceivers 209a-209n may receive input RF signals from antennas 204a-204n, such as signals transmitted by STAs in network 100. RF transceivers 209a-210n downconvert the input RF signals to generate intermediate frequency (IF) or baseband signals. The IF or baseband signals are sent to RX processing circuitry 219, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. RX processing circuitry 219 sends the processed baseband signals to controller / processor 224 for further processing.

[0053] The TX processing circuit 214 receives analog or digital data (such as voice data, network data, email, or interactive video game data) from the controller / processor 224. The TX processing circuit 214 encodes, multiplexes, and / or digitizes the output baseband data to generate a processed baseband or IF signal. RF transceivers 209a-209n receive the processed baseband or IF signal from the TX processing circuit 214 and up-convert the baseband or IF signal into an RF signal transmitted via antennas 204a-204n.

[0054] The controller / processor 224 may include one or more processors or other processing devices that control the overall operation of AP 101. For example, the controller / processor 224 may control the RF transceivers 209a-209n, the RX processing circuitry 219, and the TX processing circuitry 214 to receive uplink signals and transmit downlink signals, based on known principles. The controller / processor 224 may also support additional functions, such as more advanced wireless communication functions. For example, the controller / processor 224 may support beamforming or directional routing operations, where the output signals from multiple antennas 204a-204n are weighted differently to effectively direct the output signals in a desired direction. The controller / processor 224 may also support OFDMA operations, where the output signals are assigned to different subsets of subcarriers for different receivers (e.g., different STAs 111-114). In AP 101, the controller / processor 224 may support a variety of other functions, including combinations of DL MU-MIMO and OFDMA in the same transmission opportunity. In some examples, the controller / processor 224 may include at least one microprocessor or microcontroller. The controller / processor 224 is also capable of executing programs and other processes, such as an operating system, residing in the memory 229. The controller / processor 224 can move data into or out of the memory 229 as needed by the executing process.

[0055] Controller / processor 224 is also coupled to backhaul or network interface 234. Backhaul or network interface 234 communicates with other devices or systems via a backhaul connection or over a network. Interface 234 can support communication via any suitable wired or wireless connection(s). For example, interface 234 can allow AP 101 to communicate with a larger network (e.g., the Internet) via a wired or wireless LAN or via a wired or wireless connection. Interface 234 may include any suitable structure supporting communication via wired or wireless connections, such as an Ethernet or RF transceiver. Memory 229 is coupled to controller / processor 224. A portion of memory 229 may include RAM, and another portion of memory 229 may include flash memory or other ROM.

[0056] As described in more detail below, AP 101 may include circuitry and / or programming for managing the channel detection process in a WLAN. Although Figure 2a An example of AP 101 is shown, but it is possible to compare it with other versions. Figure 2a Various modifications can be made. For example, AP 101 can include any number of... Figure 2aEach component shown. As a specific example, the AP may include multiple interfaces 234, and the controller / processor 224 may support routing functionality to route data between different network addresses. As another specific example, although illustrated as including a single instance of TX processing circuitry 214 and a single instance of RX processing circuitry 219, AP 101 may include multiple instances of each type of circuitry (e.g., one per RF transceiver). Alternatively, only one antenna and RF transceiver channel may be included, as in a traditional access point (AP). Furthermore, Figure 2a The various components can be combined, further subdivided, or omitted, and additional components can be added as needed.

[0057] like Figure 2a As shown, in some embodiments, AP 101 may be an AP MLD comprising multiple APs 202a-202n. Each AP 202a-202n is attached to AP MLD 101 and includes multiple antennas 204a-204n, multiple radio frequency (RF) transceivers 209a-209n, transmit (TX) processing circuitry 214, and receive (RX) processing circuitry 219. Each AP 202a-202n may independently communicate with the controller / processor 224 and other components of AP MLD 101. Figure 2a The diagram shows that each AP 202a-202n has multiple independent antennas, but each AP 202a-202n can share multiple antennas 204a-204n without requiring separate multiple antennas. Each AP 202a-202n can represent the physical (PHY) layer and the lower media access control (MAC) layer.

[0058] Figure 2b An example of STA 111 according to an embodiment is shown. Figure 2b The embodiment of STA 111 shown is for illustrative purposes only, and Figure 1 STAs 111-114 can have the same or similar configurations. However, STAs have various configurations, and Figure 2b This disclosure is not intended to limit the scope to any particular implementation of STA.

[0059] like Figure 2b As shown, STA 111 may include antenna(s) 205, RF transceiver 210, TX processing circuitry 315, microphone 220, and RX processing circuitry 225. STA 111 may also include speaker 230, controller / processor 240, input / output (I / O) interface (IF) 245, touchscreen 250, display 255, and memory 260. Memory 260 may include operating system (OS) 261 and one or more applications 262.

[0060] RF transceiver 210 receives an input RF signal transmitted by an AP in network 100 from antenna 205. RF transceiver 210 down-converts the input RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is sent to RX processing circuitry 225, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. RX processing circuitry 225 sends the processed baseband signal to speaker 230 (e.g., for voice data) or to controller / processor 240 for further processing (e.g., for web browsing data).

[0061] TX processing circuit 215 receives analog or digital voice data from microphone 220 or other output baseband data (such as network data, email, or interactive video game data) from controller / processor 240. TX processing circuit 215 encodes, multiplexes, and / or digitizes the output baseband data to generate a processed baseband or IF signal. RF transceiver 210 receives the processed baseband or IF signal from TX processing circuit 215 and up-converts the baseband or IF signal into an RF signal transmitted through antenna 205.

[0062] The controller / processor 240 may include one or more processors and execute a basic OS 261 program stored in memory 260 to control the overall operation of STA 111. In one such operation, the controller / processor 240 may control the RF transceiver 210, RX processing circuitry 225, and TX processing circuitry 215 to receive downlink signals and transmit uplink signals according to known principles. The controller / processor 240 may also include processing circuitry configured to provide management of channel detection processes in the WLAN. In some examples, the controller / processor 240 may include at least one microprocessor or microcontroller.

[0063] The controller / processor 240 is also capable of executing other processes and programs residing in memory 260, such as operations for managing the channel sounding process in the WLAN. The controller / processor 240 can move data into or out of memory 260 as needed by the executing processes. In some examples, the controller / processor 240 is configured to execute multiple applications 262, such as applications for channel sounding, including feedback calculations based on received null packet announcements (NDPA) and null packets (NDP), and sending beamforming feedback reports in response to trigger frames (TF). The controller / processor 240 can operate multiple applications 262 based on OS 261 programs or in response to signals received from the AP. The controller / processor 240 is also coupled to an I / O interface 245, which provides the STA 111 with the ability to connect to other devices, such as laptops and handheld computers. The I / O interface 245 is the communication path between these accessories and the main controller / processor 240.

[0064] The controller / processor 240 is also coupled to input 250 (e.g., a touchscreen) and display 255. The operator of STA 111 can use input 250 to input data into STA 111. Display 255 may be a liquid crystal display, a light-emitting diode display, or other display capable of displaying, for example, text and / or at least limited graphics from a website. Memory 260 is coupled to the controller / processor 240. A portion of memory 260 may include random access memory (RAM), and another portion of memory 260 may include flash memory or other read-only memory (ROM).

[0065] although Figure 2b An example of STA 111 is shown, but more can be found on STA 111. Figure 2b Make various changes. For example, Figure 2b The various components can be combined, further subdivided, or omitted, and additional components can be added as needed. In a specific example, STA 111 may include any number of antennas 205 for MIMO communication with AP 101. In another example, STA 111 may not include voice communication, or the controller / processor 240 may be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). Furthermore, although Figure 2b The STA 111 is shown configured as a mobile phone or smartphone, but the STA can be configured to operate as other types of mobile or fixed devices.

[0066] like Figure 2bAs shown, in some embodiments, STA 111 may be a non-AP MLD comprising multiple STAs 203a-203n. Each STA 203a-203n is attached to the non-AP MLD 111 and includes antenna(s) 205, RF transceiver 210, TX processing circuitry 215, and RX processing circuitry 225. Each STA 203a-203n may independently communicate with the controller / processor 240 and other components of the non-AP MLD 111. Figure 2b Each STA 203a-203n has an independent antenna, but each STA 203a-203n can share antenna 205 without requiring separate antennas. Each STA 203a-203n can represent the physical (PHY) layer and the lower media access control (MAC) layer.

[0067] Figure 3 An example of multi-link communication operation according to an embodiment is shown. Multi-link communication operation can be applied to the IEEE 802.11be standard and any future revisions to the IEEE 802.11 standard. Figure 3 In the middle, AP MLD 310 can be Figure 1 Wireless communication devices 101 and 103, rather than AP MLD 220, can be Figure 1 One of the wireless communication devices 111-114.

[0068] like Figure 3 As shown, AP MLD 310 may include multiple affiliated APs, such as AP 1, AP 2, and AP 3. Each affiliated AP may include a PHY interface to the wireless medium (Link 1, Link 2, or Link 3). AP MLD 310 may include a single MAC Service Access Point (SAP) 318 through which the affiliated APs of AP MLD 310 communicate with higher layers (Layer 3 or network layer). Each affiliated AP of AP MLD 310 may have a different MAC address (lower-layer MAC address) than any other affiliated AP of AP MLD 310. AP MLD 310 may have an MLD MAC address (upper-layer MAC address), while the affiliated APs share a single MAC SAP 318 for Layer 3. Therefore, the affiliated APs share a single IP address, and Layer 3 identifies AP MLD 310 by assigning this single IP address.

[0069] A non-AP MLD 320 may include multiple affiliated APs, such as STA 1, STA 2, and STA 3. Each affiliated STA may include a PHY interface to the wireless medium (Link 1, Link 2, or Link 3). A non-AP MLD 320 may include a single MAC SAP 328 through which affiliated STAs communicate with higher layers (Layer 3 or network layer). Each affiliated STA of a non-AP MLD 320 may have a different MAC address (lower-layer MAC address) than any other affiliated STA of the non-AP MLD 320. The non-AP MLD 320 may have an MLD MAC address (upper-layer MAC address), while the affiliated STAs share a single MAC SAP 328 for Layer 3. Therefore, the affiliated STAs share a single IP address, and Layer 3 identifies the non-AP MLD 320 by assigning this single IP address.

[0070] AP MLD 310 and non-AP MLD 320 can establish multiple links between their associated APs and STAs. In this example, AP 1 and STA 1 can establish link 1 operating in the 2.4 GHz band. Similarly, AP 2 and STA 2 can establish link 2 operating in the 5 GHz band, and AP 3 and STA 3 can establish link 3 operating in the 6 GHz band. Each link independently enables channel access and frame switching between the AP MLD 310 and non-AP MLDs, thereby improving data throughput and reducing latency. When associating with an AP MLD on a set of links (setup links), each non-AP device is assigned a unique association identifier (AID).

[0071] The following documents are hereby incorporated in their entirety into this disclosure, as if fully described herein: i) IEEE 802.11-2020, “Wireless LAN Media Access Control (MAC) and Physical Layer (PHY) Specification”, ii) IEEE 802.11ax-2021, “Wireless LAN Media Access Control (MAC) and Physical Layer (PHY) Specification”, and ii) IEEE P802.11be / D4.0, “Wireless LAN Media Access Control (MAC) and Physical Layer (PHY) Specification”.

[0072] When a user moves around the environment while holding the STA device, the signal strength between the STA and its connected AP may change. If the user's movement causes a significant drop in signal strength, handover may be necessary. During handover, the STA may switch from its currently associated AP to a new AP.

[0073] Figure 4The various stages of the mobility handover process according to an embodiment are shown. Figure 4 As shown, in a traditional device without any mobility support, the handover process may involve several steps, including detection phase 401, search phase 403, 802.11 authentication phase 405, 802.11 association phase 407, 802.1X authentication phase 409, and 802.11 resource reservation phase 411.

[0074] In detection phase 401, the STA can determine that a handover is necessary. The process for detecting a handover requirement may vary depending on the vendor. For example, a particular vendor's implementation may choose to trigger a handover when the signal strength of the currently associated AP drops below a certain threshold.

[0075] Following detection phase 401, search phase 403 can proceed. In search phase 403, the STA can search for new APs to associate with. In search phase 403, the STA can scan different channels to identify surrounding APs. This can be done passively, for example, by listening to beacons on specific channels, or actively, for example, by using a probe request and response process.

[0076] After the scanning process is complete, the next step is to perform 802.11 authentication (based on Open Systems / Shared Key) 405. Once the STA is successfully authenticated, the next step is to perform 802.11 association 807. The 802.1X authentication phase 409, introduced in the IEEE 802.1i revision, can include EAP authentication between the STA and the AAA server with the assistance of the AP. Finally, during the 802.11 resource reservation phase 411, the STA can configure various resources on the new AP. For example, the STA can perform QoS reservation, BA settings, and other operations for the newly associated AP.

[0077] Typically, during handover, the connection may be interrupted because the establishment process involves a disconnect-then-reconnect mechanism. This can impact the user experience, particularly for multimedia services, as the high latency during handover can cause session interruptions.

[0078] To reduce handover latency, several procedures have been introduced in various standards. These procedures aim to eliminate or reduce latency at each step of the handover process. In 2008, the IEEE 802.11r standard introduced Fast Transition Roaming, a technique that eliminates the need for authentication steps during handover. In 2011, IEEE 802.11k introduced Assisted Roaming, which shortens the search phase by allowing the STA to request the AP to send channel information for candidate neighbor APs. Also in 2011, IEEE 802.11v introduced Network Assisted Roaming to assist the search phase. In IEEE 802.11be, the Fast BSS Transition procedure was extended to cover MLO operations. This procedure helps reduce latency due to 802.11 resource reservations. However, the STA may still need to perform an association and authentication phase, which can take, for example, 10 ms.

[0079] In some examples, a roaming architecture can be used where multiple AP MLDs can interact with each other for mobility management. This architecture may include a logical control entity that can interact with one or more AP MLDs to enable non-AP MLDs to roam from one AP MLD to another. The logical control entity may be referred to herein as a parallel stack, a seamless mobility domain entity, etc.

[0080] Figure 5 A roaming architecture including a parallel stack is illustrated according to an embodiment. Specifically, Figure 5 The diagram shows AP MLD1, which includes AP1 and AP2, and AP MLD2, which includes AP3 and AP4. Parallel stacks (e.g., logical control entities, seamless roaming domain entities) can support the operations that may be required when roaming from one AP MLD to another.

[0081] In some examples, a logical control entity can perform one or more operations, including association processing, security parameter processing, operation parameter setting, deassociation processing, context transfer processing, roaming processing and / or authentication processing, as well as a variety of other operations.

[0082] In some examples, a logical control entity may have its own identifier. In some examples, a logical control entity may use its own Media Access Control (MAC) address as its identifier. In some examples, the process of roaming from one AP MLD to another may include a context transfer with or without data transfer (e.g., data forwarding, data path transfer, etc.). In some examples, a context transfer can be implemented by transferring the context from one AP MLD to another AP MLD. In some embodiments, a context transfer can be implemented by transferring a logical control entity from one AP MLD to another AP MLD. In some examples, a non-AP MLD can perform authentication and association with the logical control entity by communicating with the AP MLD that the logical control entity interacts with. Once a link is established, a non-AP MLD can roam from one AP MLD to another. In some examples, roaming may include performing a multi-link (ML) reconfiguration process that can add or remove links as a non-AP MLD roams between AP MLDs.

[0083] In some examples, an AP MLD interacting with a logical control entity can announce the presence of the logical control entity in its advertising messages. These advertising messages may include, but are not limited to, information exchanged via management frames, such as beacon, probe responses, and other frames. These advertising messages enable non-AP MLDs to discover the presence of the logical control entity. This can be useful information for non-AP MLDs. For example, if a non-AP MLD tends to associate with an AP MLD that supports seamless roaming, the advertisement can enable the non-AP MLD to discover and utilize such support by initiating or participating in the necessary roaming process while roaming. In some examples, the advertising information may include at least one or more of the information items shown in Table 1.

[0084] [Table 1]

[0085]

[0086] The above information items can be transmitted together or separately. These information items can be transmitted as part of any existing frame / element / field / subfield in the standard, or as part of a newly defined frame / element / field / subfield.

[0087] In some examples, a non-AP MLD can perform association and authentication with a logical control entity. Therefore, when a non-AP MLD roams from one AP MLD to another, it may not need to (re)associate. When a non-AP MLD performs association and / or authentication, it can send a message that may include at least one or more of the information items indicated in Table 2.

[0088] [Table 2]

[0089]

[0090] The above information items can be transmitted together or separately. These information items can be transmitted as part of any existing frame / element / field / subfield in the standard, or as part of a newly defined frame / element / field / subfield.

[0091] In some examples, once a non-AP MLD is connected to a logical control entity, the non-AP MLD can be assigned an identifier, such as an association identifier (AID). This AID can remain unchanged during the association of the non-AP MLD, or it can be modified when the non-AP MLD roams from one AP MLD to another.

[0092] The deassociation process according to this disclosure will be described herein. In some examples, during deassociation, the deassociation message may include one or more of the information items shown in Table 3.

[0093] [Table 3]

[0094]

[0095] The above information items can be transmitted together or separately. These information items can be transmitted as part of any existing frame / element / field / subfield in the standard, or as part of a newly defined frame / element / field / subfield.

[0096] The roaming process according to this disclosure will be described herein. In some examples, a reconfiguration process may be performed during roaming. As part of the reconfiguration process, one or more links may be added to or removed from the settings of a non-AP MLD. In some examples, reconfiguration may be performed by either a non-AP MLD or an AP MLD by sending a reconfiguration message. The reconfiguration message may include at least one or more of the information items indicated in Table 4.

[0097] [Table 4]

[0098]

[0099] The above information items can be transmitted together or separately. These information items can be transmitted as part of any existing frame / element / field / subfield in the standard, or as part of a newly defined frame / element / field / subfield.

[0100] Upon receiving the reconfiguration message, the receiver can process the message and either initiate the roaming process directly or send a response message back to the non-AP MLD. The response message may include at least one or more of the information items described in Table 5.

[0101] [Table 5]

[0102]

[0103] The above information items can be transmitted together or separately. These information items can be transmitted as part of any existing frame / element / field / subfield in the standard, or as part of a newly defined frame / element / field / subfield.

[0104] In some examples, a context transfer procedure can be performed to allow a non-AP MLD to roam from one AP MLD to another. In some embodiments, for roaming, a context transfer can be performed simultaneously with a data transfer procedure. In some examples, roaming may also utilize a modified ML reconfiguration procedure, which can add a link from another AP MLD.

[0105] The context transfer process according to this disclosure will be described herein. In some examples, when a non-AP MLD is transferred from one AP MLD to another, one or more of the contexts of the current AP MLD can be transferred to the target AP MLD. These contexts may include, but are not limited to, the items described in Table 6.

[0106] [Table 6]

[0107]

[0108] The above information items can be transmitted together or separately. These information items can be transmitted as part of any existing frame / element / field / subfield in the standard, or as part of a newly defined frame / element / field / subfield.

[0109] Context transfer according to this disclosure will be described herein. In some examples, the context transfer can be completed entirely in one go. Therefore, all parameters can be transferred from one AP MLD to another. In some embodiments, the context transfer can be performed in multiple parts. Specifically, after roaming is initiated, a portion of the context transfer can be performed to set the target AP MLD with the required parameters. For example, this portion of the context transfer may involve the BA protocol, EPCS settings, etc. The remaining portion of the context transfer can be transferred at a later time. For example, the remaining portion may be related to SN / PN information, etc.

[0110] The data processing procedures according to this disclosure will be described herein. In some examples, during roaming, the data path can switch from the current AP MLD to the target AP MLD. In some examples, the data path can switch after a context transfer has been completed. In some embodiments, during roaming, one or more frames from a non-AP MLD can still be buffered at the original AP MLD. These frames can be processed using one or more of the following techniques. In some examples, continuous transmission can be performed, where the current AP MLD can continue to transmit buffered frames to a non-AP MLD until the buffer is empty. In some embodiments, operations can be performed to transfer data frames to a new or target AP MLD, where the current AP MLD can forward frames to the target AP MLD. In some examples, a buffer clearing without transmission can be performed, where the current AP MLD can discard frames without transmitting buffered frames to a non-AP MLD or forwarding frames to the target AP MLD. In some examples, a mixed mode can be performed, where the current AP MLD can forward some frames to the target AP MLD and discard some frames. For example, the current AP MLD can forward frames of latency-sensitive traffic and discard frames of latency-tolerant traffic. In some examples, for uplink frame transmission, a non-AP MLD can transmit uplink frames to the target AP MLD after roaming occurs, and all subsequent frames can be transmitted to the target AP MLD.

[0111] The security processing described herein will be used. In some examples, security-related parameters can be generated using parameters of the logical control entity instead of those of the AP MLD, including, for example, the MAC address of the logical control entity. In some examples, there are no link-dependent security parameters, and therefore they can remain unchanged when a non-AP MLD roams from one AP MLD to another. In some examples, link-dependent security parameters can be provided to the non-AP MLD after a new link is added.

[0112] Link management according to this disclosure will be described herein. In some examples, to avoid confusion between the link IDs indicated in signaling to the logical control entity, the link ID may be combined with one or more other parameters to distinguish these links. One or more other parameters may include, for example, the AP MLD MAC address, BSSID, etc. In some examples, the AP MLD may be assigned AP MLD IDs by the logical control entity, and these IDs may be used for differentiation.

[0113] The capability advertising according to this disclosure will be described herein. In some examples, an AP MLD capable of providing support for seamless roaming can advertise this capability in one or more frames it transmits, including, for example, management frames, such as beacon, probe response, etc. This allows non-AP MLDs to discover the capability and connect to the desired AP MLD. Advertising can be performed by including information items that describe the capability, including, for example, a bit or flag that can take a predetermined value for indication.

[0114] In some examples, a non-AP MLD can advertise its ability to support seamless roaming procedures in one or more frames it sends, including, for example, management frames such as probe requests, (re)association requests, etc. This allows the AP MLD to be aware of the non-AP MLD's capabilities and initiate the necessary procedures during roaming. Although the procedures described in this disclosure are described in the context of MLO operation, such procedures are equally applicable to single-link operation.

[0115] Figure 6 A flowchart illustrating an example process performed by the STA in association with a Seamless Roaming Domain (SRD) according to an embodiment is shown. Although one or more operations are described or shown in a particular order, in other embodiments, these operations may be rearranged in a different order, which may include performing multiple operations within at least partially overlapping time periods. Figure 6 The flowchart shown illustrates the process in STA, for example... Figure 3 The operations performed in the STA shown.

[0116] In operation 601 of process 600, the STA sends a first frame to the AP attached to the seamless roaming domain. The first frame indicates its intention to associate with the seamless roaming domain. In some examples, the first frame may include one or more information items listed in Table 2 above.

[0117] In Operation 603, the STA roams to a second AP attached to the seamless roaming domain. In some examples, a reconfiguration process can be performed during roaming. As part of the reconfiguration process, one or more links can be added to or removed from the setup of a non-AP MLD. In some examples, reconfiguration can be performed by either a non-AP MLD or an AP MLD by sending a reconfiguration message. The reconfiguration message may include at least one or more of the information items indicated in Table 4.

[0118] In some examples, a context transfer procedure may be performed to allow a non-AP MLD to roam from one AP MLD to another. In some embodiments, for roaming, a context transfer may be performed concurrently with a data transfer procedure. In some examples, roaming may also utilize a modified ML reconfiguration procedure, which can add a link from another AP MLD. In some examples, when a non-AP MLD moves from one AP MLD to another, one or more of the contexts of the current AP MLD may be transferred to the target AP MLD. These contexts may include, but are not limited to, the items described in Table 6.

[0119] In operation 605, the STA sends one or more frames to the second AP.

[0120] Embodiments of this disclosure provide seamless roaming, where a non-AP MLD can switch from one AP MLD to another without interrupting the connection, thereby providing an improved user experience, particularly in multimedia services that may be adversely affected by session interruptions due to high latency in existing handover processes.

[0121] Unless otherwise specified, a reference to a singular element does not mean "one and only one" but rather "one or more". For example, a module can refer to one or more modules. Without further restrictions, an element modified by "a (a, an)," "the," or "the" does not preclude the possibility of the existence of other identical elements.

[0122] Titles and subtitles (if any) are used for illustrative purposes only and do not limit the invention. The word “exemplary” is used herein to mean as an example or illustration. Within the scope of the use of terms “comprising,” “having,” or similar terms, the term is intended to be inclusive in a manner similar to that interpreted as “comprising” as a transitional term in the claims. Relational terms such as first, second, etc., may be used to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between these entities or actions.

[0123] Phrases such as “one aspect,” “the aspect,” “another aspect,” “some aspects,” “one or more aspects,” “one implementation,” “the implementation,” “another implementation,” “some implementations,” “one or more implementations,” “an embodiment,” “the embodiment,” “another embodiment,” “some examples,” “one or more embodiments,” “one configuration,” “the configuration,” “another configuration,” “some configurations,” “one or more configurations,” “the subject matter,” “this disclosure,” “this disclosure,” and “other variations” are used for illustrative purposes only and do not imply that the disclosure associated with such phrase(s) is necessary for the subject matter, nor does it imply that such disclosure applies to all configurations of the subject matter. The disclosure associated with such phrase(s) may apply to all configurations, or one or more configurations. The disclosure associated with such phrase(s) may provide one or more examples. Phrases such as “one aspect” or “some aspects” may refer to one or more aspects, and vice versa, and this also applies to other foregoing phrases.

[0124] When the phrase "at least one" appears after a list of items, separated by "and" or "or," the phrase "at least one" modifies the entire list, not each member of the list. The phrase "at least one" does not require the selection of at least one item; rather, it allows its meaning to include at least one of the following: any one item, and / or at least one combination of any items, and / or at least one of each item. For example, the phrase "at least one of A, B, and C" or "at least one of A, B, or C" refers to only A, only B, or only C; any combination of A, B, and C; and / or at least one of each of A, B, and C.

[0125] It should be understood that the specific order or hierarchy of the disclosed steps, operations, or processes is an illustration of exemplary methods. Unless otherwise expressly stated, it should be understood that the specific order or hierarchy of steps, operations, or processes may be performed in a different order. Certain steps, operations, or processes may be performed simultaneously or as part of one or more other steps, operations, or processes. The appended method claims (if any) present elements of various steps, operations, or processes in a sample order, but this does not imply limitation to the specific order or hierarchy presented. These may be performed sequentially, linearly, in parallel, or in different orders. It should be understood that the described instructions, operations, and systems can generally be integrated into a single software / hardware product or packaged into multiple software / hardware products.

[0126] This disclosure is provided to enable any person skilled in the art to practice the various aspects described herein. In some cases, known structures and components are shown in block diagram form to avoid obscuring the concepts of the subject matter. This disclosure provides various examples of the subject matter, but the subject matter is not limited to these examples. Various modifications to these aspects will be apparent to those skilled in the art, and the principles described herein can be applied to other aspects.

[0127] All structural and functional equivalents of the elements of all aspects described herein, whether currently known or to be known in the future to a person skilled in the art, are expressly incorporated herein by reference and are intended to be covered within the scope of the claims. Furthermore, nothing disclosed herein is intended for general public use, whether or not such disclosure is expressly stated in the claims. Unless expressly cited using the phrase “component for…” or, in the case of a method claim, using the phrase “step for…”, no element of the claim shall be construed in accordance with 35 U.SC §112, paragraph 6.

[0128] The title, background art, description of the drawings, abstract, and figures are hereby incorporated in this disclosure and are provided as illustrative examples rather than limiting descriptions. This document is filed on the premise that these elements are not intended to limit the scope or meaning of the claims. Furthermore, as will be apparent from the detailed description, the description provides illustrative examples, and various features are combined in various embodiments for the purpose of simplifying this disclosure. This method of disclosure should not be construed as indicating that the claimed subject matter requires more features than expressly recited in each claim. Rather, as reflected in the following claims, the inventive subject matter resides in a portion of the features of a disclosed configuration or operation, rather than all of them. The following claims are hereby incorporated in this detailed description, wherein each claim may stand alone as a separate claim.

[0129] The following claims are not limited to the aspects described herein, but should be given the full scope consistent with the language of the claims, and include all legal equivalents. Nevertheless, these claims are not intended to cover subject matter that does not meet the requirements of applicable patent law, nor should they be interpreted in this manner.

Claims

1. A station STA (111) in a wireless network, comprising: Memory (260); and A processor (240) coupled to the memory (260) is configured to: A first frame is sent to a first AP attached to the seamless roaming domain to associate with the seamless roaming domain, wherein the seamless roaming domain communicates with one or more APs attached to the seamless roaming domain, including the first AP and the second AP; as well as Roaming to a second AP attached to the seamless roaming domain, wherein the seamless roaming domain performs a context transfer from the first AP to the second AP.

2. The STA of claim 1, wherein the context transfer transmission is associated with at least one of the following: sequence number (SN) / packet number (PN) information, block acknowledgment protocol information, quality of service (QoS) setting information, target wake-up time (TWT) setting information, emergency prepared communication service (EPCS) setting information, or traffic identifier (TID) to link mapping information.

3. The STA according to claim 1 or claim 2, wherein the seamless roaming domain has an identifier.

4. The STA according to any of the preceding claims, wherein the seamless roaming domain performs data transfer from the first AP to the second AP.

5. The STA according to any of the preceding claims, wherein the processor (240) is further configured to: A second frame is sent, which includes a reconfiguration message that adds a link between the STA (111) and the second AP or deletes a link between the STA (111) and the first AP.

6. The STA according to any of the preceding claims, wherein the processor (240) is further configured to: A second frame is received from one or more APs attached to the seamless roaming domain, the second frame announcing the seamless roaming domain.

7. The STA according to any of the preceding claims, wherein the second frame includes i) a Media Access Control (MAC) identifier of the Seamless Roaming Domain, ii) one or more MAC addresses of other APs that are part of the Seamless Roaming Domain, or iii) the capabilities of other APs that are part of the Seamless Roaming Domain.

8. The STA according to any of the preceding claims, wherein the processor (240) is further configured to: The second frame is sent via the second AP to deassociate from the seamless roaming domain.

9. A first access point (AP) (101) in a wireless network, the AP comprising: Memory (229); and A processor (224) coupled to the memory, the processor (224) being configured to: The STA receives a first frame to be associated with a seamless roaming domain to which the first AP (101) is attached, wherein the seamless roaming domain communicates with one or more APs attached to the seamless roaming domain, including the first AP (101) and the second AP; as well as It is determined that the STA has roamed to the second AP attached to the seamless roaming domain, and a context transfer to the second AP is performed.

10. The AP of claim 9, wherein the context transfer transmission is associated with at least one of the following: sequence number (SN) / packet number (PN) information, block acknowledgment protocol information, quality of service (QoS) setting information, target wake-up time (TWT) setting information, emergency prepared communication service (EPCS) setting information, or traffic identifier (TID) to link mapping information.

11. The AP according to claim 9 or claim 10, wherein the seamless roaming domain has an identifier.

12. The AP according to any one of claims 9 to 11, wherein the seamless roaming domain performs data transfer from the first AP to the second AP.

13. The AP according to any one of claims 9 to 12, wherein the processor (224) is further configured to: Receive a second frame including a reconfiguration message, which adds a link between the STA and the second AP or deletes a link between the STA and the first AP (101).

14. The AP according to any one of claims 9 to 13, wherein the processor (224) is further configured to: A second frame is sent to the STA, which announces the seamless roaming domain.

15. The AP according to any one of claims 9 to 14, wherein the second frame includes i) a Media Access Control (MAC) identifier of the Seamless Roaming Domain, ii) one or more MAC addresses of other APs belonging to the Seamless Roaming Domain, or iii) the capabilities of other APs belonging to the Seamless Roaming Domain.

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