Buffer management for roaming stations

Abstract

A method for managing roaming / transfer handover is provided, wherein a first access point (AP) receives a first frame from a slave station (STA) indicating a transfer from a first AP to a second AP; and then sends a second frame to the STA, the second frame indicating parameters related to the transmission of data buffered at the STA prior to the transfer from the first AP to the second AP. The first frame may include a buffer status report (BSR) indicating one or more service identifiers (TIDs) associated with services buffered at the STA for the first AP. The indication of the transfer from the first AP to the second AP may be a request to roam (transfer) from the first AP to the second AP, and the parameters related to the transmission to the first AP include a first TID from one or more TIDs. Furthermore, the method may include: the first AP receiving a third frame from the STA, the third frame including a data frame associated with the first TID and a second BSR; and the first AP sending a fourth frame to the STA based on a queue size having a zero value for the first TID, the fourth frame indicating the transfer from the first AP to the second AP.

Description

Technical Field

[0001] This invention relates to wireless networks, and more particularly to those conforming to IEEE standards. TM Wireless networks conforming to the 802.11 standard. Background Technology

[0002] Wireless networks are typically required to accommodate the mobility of devices connected to them. This mobility can cause a device to move away from a node (such as an access point or base station) that has a link (in other words, is served by it) and is closer to a second access point / base station. From a link bandwidth and reliability standpoint, it may be more desirable to connect to a second access point, i.e., to perform roaming handover.

[0003] Furthermore, it is desirable to perform the handover in a manner that does not interrupt ongoing communications. Typically, the equipment (sometimes referred to as a "station" (STA) or "user equipment" (UE)) prepares for the handover by announcing its intention and then performing negotiation. The handover is then performed. Roaming can also be referred to as a "transition". Summary of the Invention

[0004] This invention is defined by the appended independent claims, in which methods and apparatus are provided.

[0005] It might be expected that a STA preparing to roam will send all of its uplink data (exhausting its uplink data) to the AP it is currently connected to before sending a roaming request to another AP. This has the advantage that data that may be part of an ongoing switch is protected to some extent from potential disruptions caused by the handover.

[0006] To this end, a method and an apparatus arranged to perform the method are provided, the method comprising: receiving a first frame of data buffered at a first access point (AP) slave station (STA), the first frame indicating a transition from the first AP to a second AP; and sending a second frame from the first AP to the STA, the second frame indicating parameters relating to the transmission of the data buffered at the STA to the first AP prior to the transition from the first AP to the second AP.

[0007] This enables the AP to provide instructions / information to the STA. Various possibilities and combinations exist, such as (but not limited to) indications of whether to send, the amount to send, and the type of data involved in the transmission.

[0008] These methods have the advantage of avoiding the problems discovered by the inventors of the process, where an STA attempting to roam / switch may require a relatively long time to exhaust its uplink data. For example, an STA may be unable to access a channel due to heavy channel contention and / or may have a large amount of buffered uplink data. This, in turn, may delay the STA's roaming request and the transition from one AP to another. Simultaneously, the link between the STA and the first AP may deteriorate or even be lost. Buffered data may subsequently be lost due to the delayed transition. Attached Figure Description

[0009] This document describes examples of several embodiments of various embodiments of the present disclosure with reference to the accompanying drawings.

[0010] Figure 1 An example wireless communication network in which embodiments of the present disclosure can be implemented is shown.

[0011] Figure 2 This is a block diagram showing an example implementation of a station (STA) and an access point (AP).

[0012] Figure 3 An example multi-AP network is shown.

[0013] Figure 4 Enhanced Distributed Channel Access (EDCA) and Coordinated Orthogonal Frequency Division Multiple Access (COFDMA) are shown.

[0014] Figure 5 An example network including a set of coordinated APs is shown.

[0015] Figure 6 An example multi-AP operation procedure is shown.

[0016] Figure 7 An example of a multi-AP probe phase is shown.

[0017] Figure 8 An example of a multi-AP downlink data transmission phase is shown.

[0018] Figure 9 This illustrates an example of a multi-AP uplink data transmission phase.

[0019] Figure 10 An example of a STA roaming from the first AP to the second AP is shown.

[0020] Figure 11 An example of using the Fast Session Transport Protocol via the DS method is shown.

[0021] Figure 12 An example of the process for transferring sessions via roaming is shown.

[0022] Figure 13 An example of a roaming process according to an embodiment is shown.

[0023] Figure 14 Another example of the roaming process according to an embodiment is shown.

[0024] Figure 15 Another example of the roaming process according to an embodiment is shown.

[0025] Figure 16 Another example of the roaming process according to an embodiment is shown.

[0026] Figure 17 An example process according to an embodiment is shown.

[0027] Figure 18 An example process according to an embodiment is shown. Detailed Implementation

[0028] In this disclosure, various embodiments are presented as examples of how the disclosed technology and / or how the disclosed technology can be practiced in environments and scenarios. It will be apparent to those skilled in the art that various changes in form and detail can be made therein without departing from the scope. After reading the specification, those skilled in the art will understand how alternative embodiments can be implemented. This embodiment is not limited to any of the exemplary embodiments described. Embodiments of the invention are described below in conjunction with the accompanying drawings. Limitations, features, and / or elements from the disclosed example embodiments can be combined to create other embodiments within the scope of this disclosure. The drawings highlighting any features and advantages are presented for illustrative purposes only. The disclosed architecture is flexible and configurable enough that it can be utilized in ways other than those shown. For example, actions listed in any flowchart can be reordered or optionally used only in some embodiments.

[0029] The embodiments can be configured to operate as needed. The disclosed mechanisms can be executed when certain criteria are met, for example, in a station, access point, radio environment, network, or a combination thereof. Example criteria may be based at least in part on, for example, wireless device or network node configuration, traffic load, initial system settings, packet size, service characteristics, or a combination thereof. Various example embodiments can be applied when one or more criteria are met. Therefore, example embodiments that selectively implement the disclosed protocols can be implemented.

[0030] In this disclosure, the terms “a”, “an”, and similar phrases will be interpreted as “at least one” and “one or more”. Similarly, any term ending with the suffix “(or more)” will be interpreted as “at least one” and “one or more”. In this disclosure, the term “may” will be interpreted as “for example”. In other words, the term “may” indicates that the phrase following the term “may” is an example of one of a number of suitable possibilities that may or may not be employed by one or more embodiments in various embodiments. As used herein, the terms “comprising” and “consisting of” enumerate one or more components of the described element. The term “comprising” may be used interchangeably with “including” and does not exclude the inclusion of unenumerated components in the described element. In contrast, “consisting of” provides a complete enumeration of one or more components of the element being described. As used herein, the term “based on” can be interpreted as “at least partially based on” rather than, for example, “based on only”. As used herein, the term “and / or” indicates any possible combination of the enumerated elements. For example, "A, B and / or C" can mean A; B; C; A and B; A and C; B and C; or A, B and C.

[0031] If A and B are sets and every element of A is an element of B, then A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, possible subsets of B = {STA1, STA2} are: {STA1}, {STA2}, and {STA1, STA2}. The phrase “based on” (or equivalently “at least based on”) indicates that the phrase following the term “based on” is an example of one of a plurality of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase “in response to” (or equivalently “at least in response to”) indicates that the phrase following the phrase “in response to…” is an example of one of a plurality of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase “depends on” (or equivalently “at least depends on”) indicates that the phrase following the phrase “depends on” is an example of one of a plurality of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase “adopt / use” (or equivalently “adopt / use at least”) indicates that the phrase following the phrase “adopt / use” is an example of one of a plurality of suitable possibilities that may or may not be used in one or more of the various embodiments.

[0032] The term "configuration" can refer to the ability of a device to be in an operational or non-operational state. Configuration can refer to specific settings within the device that affect its operational characteristics regardless of whether the device is in an operational or non-operational state. In other words, hardware, software, firmware, registers, memory values, etc., can be "configured" within the device, regardless of whether the device is in an operational or non-operational state, to provide specific characteristics to the device. Terms such as "control messages induced in the device" can mean that the control messages have parameters that can be used to configure specific characteristics, or can be used to perform certain actions within the device, regardless of whether the device is in an operational or non-operational state.

[0033] In this disclosure, a parameter (also referred to as a field or information element: IE) may include one or more information objects, and an information object may include one or more other objects. For example, if parameter (IE)N includes parameter (IE)M, and parameter (IE)M includes parameter (IE)K, and parameter (IE)K includes parameter (information element)J, then, for example, N includes K, and N includes J. In the example embodiment, when one or more messages / frames include multiple parameters, this means that a parameter among the multiple parameters is in at least one message / frame of the one or more messages / frames, but not necessarily in every message / frame of the one or more messages / frames.

[0034] Many of the features presented are described as optional using the word "may" or parentheses. For brevity and readability, this disclosure does not explicitly describe the various permutations and each permutation that can be obtained by selecting from the set of optional features. This disclosure will be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features can be embodied in seven ways: having only one of the three possible features, any two of the three possible features, or all three of the three possible features.

[0035] Many of the elements described in the disclosed embodiments can be implemented as modules. A module is defined herein as an element that performs a defined function and has an interface to the definition of other elements. Modules described in this disclosure can be implemented in hardware, software combined with hardware, firmware, artifacts (e.g., hardware with biological elements), or combinations thereof, and may be behaviorally equivalent. For example, a module can be implemented as a software routine written in a computer language configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, Matlab, etc.) or a modeling / simulation program (such as Simulink, Stateflow, GNU Octave, or LabVIEW MathScript). It is possible to implement modules using physical hardware that incorporates discrete or programmable analog, digital, and / or quantum hardware. Examples of programmable hardware include: computers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and complex programmable logic devices (CPLDs). Computers, microcontrollers, and microprocessors are programmed using languages ​​such as assembly, C, C++, etc. FPGAs, ASICs, and CPLDs are typically programmed using hardware description languages ​​(HDLs), such as VHDL or Verilog, which configure connections between smaller, internal hardware modules on a programmable device. The techniques mentioned are often used in combination to achieve the desired functional modules.

[0036] Figure 1 An example wireless communication network in which embodiments of the present disclosure can be implemented is shown.

[0037] like Figure 1 As shown, an example wireless communication network may include an IEEE 802.11 (WLAN) infrastructure network 102. WLAN infrastructure network 102 may include one or more Basic Service Sets (BSS) 110 and 120 and a Distribution System (DS) 130.

[0038] BSS 110-1 and 110-2 each comprise a set of access points (APs or AP STAs) and at least one station (STAs or non-AP STAs). For example, BSS 110-1 includes AP 104-1 and STA 106-1, and BSS 110-2 includes AP 104-2 and STAs 106-2 and 106-3. The APs and at least one STA in the BSS perform an association process to communicate with each other.

[0039] The DS 130 can be configured to connect BSS 110-1 and BSS 110-2. In this way, the DS 130 can enable Extended Service Set (ESS) 150. Within the ESS 150, APs 104-1 and 104-2 are connected via the DS 130 and can have the same Service Set Identifier (SSID).

[0040] The WLAN infrastructure network 102 can be coupled to one or more external networks. For example, such as Figure 1 As shown, WLAN infrastructure network 102 can be connected to another network 108 (e.g., 802.X) via portal 140. Portal 140 can be used as a bridge to connect DS 130 of WLAN infrastructure network 102 to another network 108.

[0041] Figure 1 The example wireless communication network shown may further include one or more self-organizing networks or independent BSSs (IBSSs). A self-organizing network or IBSS is a network of multiple STAs included within each other's communication range. The multiple STAs are configured such that they can communicate with each other using direct peer-to-peer communication (i.e., not via an AP).

[0042] For example, in Figure 1 In this configuration, STAs 106-4, 106-5, and 106-6 can be configured to form a first IBSS 112-1. Similarly, STAs 106-7 and 106-8 can be configured to form a second IBSS 112-2. Since an IBSS does not include an AP, it does not include a centralized management entity. Instead, STAs within the IBSS are managed in a distributed manner. STAs forming an IBSS can be fixed or mobile.

[0043] A STA, serving as a predefined functional medium, may include a Media Access Control (MAC) layer conforming to the IEEE 802.11 standard. A physical layer interface for the radio medium can be used between APs and non-AP stations (STAs). STA may also be referred to using various other terms, including mobile terminal, radio device, radio transceiver unit (WTRU), user equipment (UE), mobile station (MS), mobile subscriber unit, or user. For example, the term "user" may be used to refer to a STA participating in uplink multi-user multiple-input multiple-output (MU MIMO) and / or uplink orthogonal frequency division multiple access (OFDMA) transmissions.

[0044] A Physical Layer (PHY) Protocol Data Unit (PPDU) can be a composite structure including a PHY preamble and payload in the form of a PLCP Service Data Unit (PSDU). For example, a PSDU may include a PHY Convergence Protocol (PLCP) preamble and header and / or one or more MAC Protocol Data Units (MPDUs). The receiving device can use the information provided in the PHY preamble to decode subsequent data in the PSDU. In an example where the PPDU is transmitted on a bonded channel (a channel formed by channel bonding), the preamble field can be copied and transmitted in each of the multiple component channels. The PHY preamble may include a traditional portion (or "traditional preamble") and a non-traditional portion (or "non-traditional preamble"). The traditional preamble can be used for packet detection, automatic gain control, and channel estimation, among other uses. The traditional preamble is also typically used to maintain compatibility with legacy equipment. The format of the non-traditional portion of the preamble, the encoding of the non-traditional portion, and the information provided in the non-traditional portion are based on the specific IEEE 802.11 protocol to be used to transmit the payload.

[0045] A frequency band can include one or more sub-bands or frequency channels. For example, PPDUs conforming to IEEE 802.11n, 802.11ac, 802.11ax, and / or 802.11be standard revisions can be transmitted on 2.4 GHz, 5 GHz, and / or 6 GHz frequency bands, each of which can be divided into multiple 20 MHz channels. PPDUs can be transmitted on physical channels with a minimum bandwidth of 20 MHz. Larger channels can be formed through channel bonding. For example, PPDUs can be transmitted on physical channels with bandwidths of 40 MHz, 80 MHz, 160 MHz, or 520 MHz by bonding multiple 20 MHz channels together.

[0046] Figure 2 This is a block diagram illustrating example implementations of the STA 210 and AP 260. (As shown...) Figure 2 As shown, STA 210 may include at least one processor 220, memory 230, and at least one transceiver 240. AP 260 may include at least one processor 270, memory 280, and at least one transceiver 290. Processors 220 / 270 may be operatively connected to memory 230 / 280 and / or transceiver 240 / 290.

[0047] Processors 220 / 270 can implement the functions of the PHY layer, MAC layer, and / or logical link control (LLC) layer of the corresponding device (STA 210 or AP 260). Processors 220 / 270 may include one or more processors and / or one or more controllers. For example, one or more processors and / or one or more controllers may include, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), logic circuits, or a chipset.

[0048] Memory 230 / 280 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage units. Memory 230 / 280 may include one or more non-transitory computer-readable media. Memory 230 / 280 may store computer program instructions or code that can be executed by processor 220 / 270 to perform one or more operations / embodiments discussed in this application. Memory 230 / 280 may be implemented (or placed) within or outside of processor 220 / 270. Memory 230 / 280 may be operatively connected to processor 220 / 270 via various means known in the art.

[0049] Transceiver 240 / 290 can be configured to transmit / receive radio signals. In one embodiment, transceiver 240 / 290 can implement the PHY layer of a corresponding device (STA 210 or AP 260). In one embodiment, STA 210 and / or AP 260 can be multi-link devices (MLDs), which are devices capable of operating on multiple links defined by the IEEE 802.11 standard. Thus, STA 210 and / or AP 260 can each implement multiple PHY layers. Multiple PHY layers can be implemented using one or more of transceivers 240 / 290.

[0050] Figure 3 An example multi-AP network 300 is shown. The example multi-AP network 300 can be a multi-AP network according to the Wi-Fi Alliance standard specification for multi-AP networks. For example... Figure 3 As shown, the multi-AP network 300 may include a multi-AP controller 302 and multiple multi-AP groups (or multi-AP sets) 304, 306 and 308.

[0051] The multi-AP controller 302 can be a logical entity that implements the logic for controlling the APs in the multi-AP network 300. The multi-AP controller 302 can receive capability information and measurements from the APs and can trigger AP control commands and operations on the APs. The multi-AP controller 302 can also provide network entry functionality for adding and configuring APs into the multi-AP network 300.

[0052] Multiple AP groups 304, 306, and 308 can each include multiple APs. APs in a multiple AP group are within each other's communication range and can coordinate their transmissions and / or transmissions from their associated STAs. Coordinated transmissions can involve all or a subset of the APs in the multiple AP group. A multiple AP group can also be referred to as an AP candidate set because APs in the multiple AP group are considered candidates for coordinated transmissions initiated by the APs. APs in a multiple AP group do not need to have the same primary channel. As used herein, the primary channel of an AP refers to the AP's monitoring and management frames and / or the default channel used to send beacon frames. For the STA associated with the AP, the primary channel refers to the AP's primary channel, which is advertised via AP beacon frames.

[0053] In one approach, a multi-AP group can be established by a coordinating AP during the multi-AP establishment phase prior to any multi-AP coordination. APs in the multi-AP group other than the coordinating AP can be referred to as coordinated APs. The coordinating AP can establish one or more multi-AP groups. Coordinated APs can also be members of multiple multi-AP groups. The coordinating AP in one multi-AP group can be a coordinated AP in another multi-AP group, and vice versa. In another approach, a multi-AP group can be manually established by a network administrator by configuring APs as part of the multi-AP group. In yet another approach, a multi-AP group can be established in a distributed manner using APs without a central controller. In this case, the AP can advertise its multi-AP capabilities in beacons or other management frames (e.g., common action frames). Other APs receiving frames with multi-AP capability information can perform multi-AP setup with the AP that advertised the multi-AP capabilities.

[0054] In one approach, one AP in a multi-AP group can be designated as the master AP. The designation of the master AP can be done by the AP controller 302 or by the APs in the multi-AP group. The master AP of the multi-AP group can be fixed or can change among the APs in the group over time. APs that are not the master AP in the multi-AP group are referred to as slave APs.

[0055] In one approach, APs in a multi-AP group can perform coordinated transmissions together. One aspect of coordination may include coordination for performing coordinated transmissions within the multi-AP group. As used herein, coordinated transmission (also known as multi-AP transmission) is a transmission event in which multiple APs (in a multi-AP group or multi-AP network) transmit in a coordinated manner over a period of time. Coordinated transmission can involve simultaneous transmissions by multiple APs in a multi-AP group. The time period for simultaneous AP transmissions can be a continuous period of time. Multi-AP transmissions may use different transmission techniques, such as Coordinated OFDMA (COFDMA), Coordinated Spatial Reuse (CSR), Joint Transmit / Receive (JT / JR), Coordinated Beamforming (CBF), and CTDMA, or a combination of two or more of the above techniques.

[0056] Multi-AP transmission can be implemented by an AP controller and / or by a master AP in a multi-AP group. In one approach, the AP controller and / or the master AP can control time and / or frequency sharing within a transmission opportunity (TXOP). For example, when one of the APs in the multi-AP group (e.g., the master AP) acquires a TXOP, the AP controller and / or the master AP can control how the time / frequency resources of the TXOP will be shared with other APs in the multi-AP group. In one implementation, the AP that acquires the TXOP in the multi-AP group becomes the master AP of the multi-AP group. The master AP can then share a portion (which can be the entire TXOP) of its acquired TXOP with one or more other APs in the multi-AP group.

[0057] Different multi-AP transmission schemes can be applied to different use cases regarding privacy protection, including whether the transmitted data can be shared with other BSSs in the multi-AP group. For example, some multi-AP transmission schemes (such as CSR, CDTMA, Coordinated Frequency Division Multiple Access (CFDMA), COFDMA, and CBF) enable the master AP to coordinate slave APs by sharing control information among APs, without needing to share user data among APs. Control information may include the AP's BSS information, link quality information of the channel between each AP and its associated STA, and information related to resources to be used for multiplexing in power, time, frequency, or special domains for multi-AP transmission. The control information exchanged between the master and slave APs can be used for interference avoidance or zeroing to avoid or zero co-channel interference introduced into adjacent BSSs in a multi-AP network. Interference avoidance or zeroing requires that data transmission between APs and STAs is limited to the same BSS. In other words, each AP sends or receives data frames from its associated STA, while each STA receives or sends data frames from its associated AP.

[0058] In contrast, other multi-AP transmission schemes allow the master AP to coordinate slave APs by sharing control information and user data among APs in a multi-AP group. Control information may include BSS information associated with the AP and link quality information of the channel between each AP and its associated STA. By exchanging user data on the backhaul, the master and slave APs can jointly perform data transmission to achieve spatial diversity, for example, using distributed MIMO, such as joint transmission (JT) for downlink transmission and joint reception (JR) for uplink transmission. Data transmission between APs and STAs can include transmissions within the same BSS and / or transmissions across different BSSs. In other words, an AP can send data frames to or receive data frames from its associated STA and STAs associated with other APs participating in the multi-AP transmission. Similarly, a STA can send or receive data frames from multiple APs.

[0059] Depending on the signal reception level at the STAs or APs within a multi-AP group, different multi-AP transmission schemes can be suitable for different use cases. For example, CBF and JT / JR require that each STA involved in a multi-AP transmission is located within a common area of ​​signal coverage of the APs involved in the multi-AP transmission. Typically, CBF may be suitable when the receiving STA suffers potential interference from other APs in the multi-AP group. By using channel-related information exchanged between APs (such as Channel State Information (CSI), Channel Quality Indication (CQI), or Compressed Beamforming (BF) feedback), APs can precode the signal to be transmitted to form a beam that increases power towards the target STA while reducing the power of STAs associated with neighboring APs that are interfering with the signal. The JT / JR use case may require sufficient received signal power at the receiving STA for JT and sufficient received signal power at the receiving AP for JR. In contrast, CSR can perform multi-AP transmission in an interference-coordinated manner. It may be necessary for the received signal power at the STA associated with the AP transmitting data to be much higher than the received interference power.

[0060] Different multi-AP transmission schemes may require different levels of synchronization and can operate with or without backhaul between the master and slave APs in a multi-AP group. For example, CSR may require PPDU-level synchronization, while CBF may require symbol-level synchronization. On the other hand, JT / JR may require tight time / frequency / stage-level synchronization as well as backhaul for data sharing between APs in a multi-AP group.

[0061] Regarding coordination between master and slave APs in a multi-AP group, different multi-AP transmission schemes can have varying levels of complexity. For example, JT / JR may require very high complexity due to the sharing of CSI and user data among APs. CBF may require medium complexity due to CSI sharing. CFDMA, COFDMA, and CTDMA may require medium or relatively low complexity due to the sharing of CSI and time / frequency resources among APs. CSR may require low complexity because the amount of information associated with spatial reuse and the traffic that needs to be exchanged between APs is likely to be low.

[0062] Multi-AP groups can operate statically, including static multi-AP transmission schemes. However, multi-AP networks can also be dynamic for various reasons. For example, STAs can join or leave the network, switch to power-saving mode, or APs or STAs can change their locations. Such changes may alter the criteria used to select the multi-AP transmission scheme and may result in the loss of certain requirements (e.g., synchronization, backhaul, coordination, etc.). This leads to poor transmission quality in the multi-AP network.

[0063] In COFDMA, a primary AP can share a portion of its TXOP with multiple APs by assigning appropriate frequency resources (e.g., channels / subchannels) from the available frequency resources to each of the multiple APs. Compared to Enhanced Distributed Channel Access (EDCA), in Figure 4 COFDMA is shown as multi-AP channel access. For example... Figure 4 As shown, in EDCA, channel access for multiple APs (e.g., AP1, AP2) can occur within consecutive time periods (e.g., TXOPs). During a given channel access period, a single AP can use the entire channel (e.g., 80MHz). In contrast, in COFDMA, access for multiple APs (multi-AP channel access) can occur on orthogonal frequency resources within the same time period (e.g., the same TXOP or the same portion of a TXOP). For example, as... Figure 4 As shown, the 80 MHz channel can be divided into four non-overlapping 20 MHz channels, each of which is allocated to a corresponding AP among multiple APs. Multiple APs can transmit simultaneously in a coordinated manner to achieve multi-AP transmission. In multi-AP transmission, each AP can send PPDUs to one or more STAs.

[0064] Figure 5 Example network 500, including a set of coordinated APs, is shown. Figure 5As shown, the coordinated AP set may include two APs—AP 502-1 and AP 502-2. The coordinated AP set may be a subset of an established multi-AP group. At least one STA may be associated with each of APs 502-1 and 502-2. For example, STA 504-1 may be associated with AP 502-1, and STA 504-2 may be associated with AP 502-2.

[0065] AP 502-1 and 502-2 can belong to the category mentioned above. Figure 1 The same ESS described in [the original text]. In this case, AP502-1 and 502-2 can be connected by DS to support ESS features. Additionally, as part of a coordinated AP set, APs 502-1 and 502-2 can be connected via backhaul. Backhaul is used to quickly share information between APs to support coordinated transmissions. The shared information can be channel state information or data to be sent to the associated STA. Backhaul can be wired or wireless. Wired backhaul is preferred for high-capacity information transmission without burdening the AP's main radio unit. However, wired backhaul may require higher deployment costs and may impose greater constraints on AP placement. Wireless backhaul is preferred for its lower deployment costs and flexibility regarding AP placement. However, because wireless backhaul relies on the AP's main radio unit to transmit information, the AP cannot send or receive any data while wireless backhaul is in use.

[0066] Typically, one of APs 502-1 and 502-2 can act as the primary AP and the other as the secondary AP. The primary AP is the AP that owns the TXOP. The primary AP shares frequency resources with the secondary AP during the TXOP. When there are more than two APs in the coordinated set, the primary AP may share its TXOP with only a subset of the coordinated APs. The role of the primary AP can change over time. For example, the primary AP role can be assigned to a specific AP for a duration. Similarly, the secondary AP role can be dynamically selected by the primary AP or can be pre-assigned for a duration.

[0067] Depending on the capabilities of the APs in the coordinated AP set, an AP may perform only a certain type of coordinated transmission. For example, in Figure 5 In this configuration, if AP 502-1 supports JT and CSR, while AP 502-2 supports CSR and CBF, then both APs can execute CSR alone as the coordinated transmission scheme. If the benefits of coordinated transmission do not outweigh some of its disadvantages, such as reduced flexibility and increased computational power, the APs may prefer to execute a single AP transmission for the duration of the operation.

[0068] CSR can be generated by Figure 5The APs 501-1 and 502-2 shown support one type of multi-AP coordination. Spatial reuse using CSR can be more stable than non-AP coordinated spatial reuse schemes such as OBSS PD-based SR and PSR-based SR. For example, in example network 500, APs 502-1 and 502-2 can perform joint probe operations to measure path loss (PL) on paths in example network 500. For example, the joint probe operation can result in the measurement of PL 508 for the path between AP 502-1 and AP 502-2, path loss 510 for the path between AP 502-1 and STA 504-2, and path loss 512 for the path between AP 502-2 and STA 504-1. The measured path loss information can then be shared between APs 502-1 and 502-2 (e.g., using backhaul) to allow simultaneous transmissions from APs 502-1 and 502-2 to their respective associated STAs 504-1 and 504-2. Specifically, one of APs 502-1 and 502-2 acquires a TXOP to become the master AP. The master AP can then send CSR advertisement frames to the other APs. In one embodiment, the master AP can perform a polling operation before sending the CSR advertisement frames to poll the slave APs about packet availability for transmission. If at least one slave AP responds indicating packet availability, the master AP can continue sending CSR advertisement frames. In the CSR advertisement, the master AP can limit the transmit power of the slave APs to protect its own transmission to its target STA. Slave APs can similarly protect their own transmission to their target STA by selecting a modulation scheme that provides a sufficiently high signal-to-noise ratio (SIR) margin to support interference caused by transmissions from the master AP to its target STA.

[0069] Figure 6 Example 600 illustrates a multi-AP operation procedure. In Example 600, a multi-AP operation procedure is illustrated with respect to a multi-AP network including APs 602 and 604, and STAs 606 and 608. In one example, APs 602 and 604 can form a multi-AP group. AP 602 can be the master AP, and AP 604 can be a slave AP in the multi-AP group. For example, AP 602 can obtain a TXOP that makes it the master AP in the multi-AP group. Alternatively, AP 602 can be designated as the master AP by the multi-AP controller.

[0070] like Figure 6 As shown, the multi-AP operation process may include a series of time phases, each of which may include multiple frame exchanges within the multi-AP network. Specifically, the multi-AP operation process may include a multi-AP selection phase 610, a multi-AP data sharing phase 612, a multi-AP detection phase 614, and a multi-AP data transmission phase 616.

[0071] Multi-AP networks can perform multi-AP operations based on specific multi-AP transmission schemes. The master AP can select a multi-AP transmission scheme based on the capabilities of the slave APs in the multi-AP group. Before multi-AP operation, slave APs can notify the master AP of their capability information, including their ability to support one or more multi-AP transmission schemes. Slave APs can also notify the master AP of their BSS information and the link quality information of the STAs associated with them. The master AP can receive information related to all available slave APs. This information can include capability information, BSS information, and link quality information. Based on the information provided by the available slave APs, the master AP can determine the slave APs to be assigned for multi-AP transmission and the specific multi-AP transmission scheme to be used during the multi-AP transmission phase.

[0072] The multi-AP selection phase 610 may include procedures for the master AP to request, select, or specify slave APs in a multi-AP group. For example... Figure 6 As shown, the multi-AP selection phase may include the transmission of frame 618 from AP 602 and frame 620 from AP 604. AP 602 may send frame 618 to request information about the buffer status of AP 604. In response, AP 604 may send frame 620 to inform AP 602 of its buffer status and / or whether it intends to join the multi-AP operation. For example, the multi-AP selection phase 610 may also be used to exchange information related to multi-AP operation, including the BSS information of the APs and the link quality information between each AP and its associated STAs. The BSS information of the APs may include the BSS ID of the AP's BSS, the identifiers and / or capabilities of the STAs belonging to the BSS, information about the STAs' detection capabilities, information about the AP's MIMO capabilities, etc. The link quality information may include Received Signal Strength Indicator (RSSI), Signal-to-Noise Ratio (SNR), Signal-to-Interference-plus-Noise Ratio (SINR), Channel State Information (CSI), and Channel Quality Indicator (CQI).

[0073] Multi-AP data sharing phase 612 may include a process for sharing data frames to be sent by the APs to the master AP and associated STAs among selected slave APs via direct connections between the APs. For some multi-AP data transmission schemes, phase 612 may be optional. For example, JT / JR may require phase 612 because data frames can be exchanged between APs before or after multi-AP data transmission phase 616.

[0074] The multi-AP data sharing phase 612 can be performed using wired backhaul, in-channel wireless backhaul, or out-of-channel wireless backhaul. In some cases, the multi-AP data sharing phase 612 can be performed, for example, using the same wireless channel used to send data to / receive data from the STA via in-channel backhaul. For example, as... Figure 6 As shown, in stage 612, AP 602 may send frame 622, which can be received by AP 604. Frame 622 may include an MPDU that AP 602 wishes to send to the associated STA using multi-AP operation. Similarly, AP 604 may send frame 624, which can be received by AP 602. Frame 624 may include an MPDU that AP 604 wishes to send to the associated STA using multi-AP operation.

[0075] Multi-AP probing phase 614 may include procedures for multi-AP channel probing, including channel estimation and feedback of channel estimates among the master AP, candidate slave APs, and associated STAs. For some multi-AP transmission schemes, such as COFDMA, CDTMA, and CSR, phase 614 may be optional. For example, phase 614 may be performed by the master AP to assist in resource unit allocation when coordinating COFDMA transmissions.

[0076] Multi-AP data transmission phase 616 may include exchanging data frames between the master AP, slave APs, and their associated STAs based on a multi-AP transmission scheme determined by the master AP. Depending on the multi-AP transmission scheme to be used, phase 616 may include optional synchronization between the APs in the multi-AP group before exchanging data frames between the APs in the multi-AP group and the STAs within the multi-AP group.

[0077] The order of stages 610, 612, 614, and 616 can be compared with... Figure 6 The order shown differs. For example, in COFDMA, stage 616 may occur immediately after stage 610, while in JT / JR, stage 612 may occur after stage 610. Furthermore, as mentioned above, some stages may be optional and may or may not be present. For example, stage 614 may not be necessary for COFDMA, but it may be required for JT / JR.

[0078] Figure 7 Example 700 of a multi-AP detection phase is shown. Multi-AP detection phase 700 can be an example of multi-AP detection phase 614. For example... Figure 7 As shown, Example 700 may include a master AP 702 and a slave AP 704 in a multi-AP group. Example 700 may also include a STA 706 associated with AP 702 and a STA 708 associated with AP 704.

[0079] like Figure 7 As shown, the multi-AP detection phase 700 may include frame switching to allow AP 702 (the master AP) to acquire channel state information (CSI) of the channels in the multi-AP group. In one implementation, phase 700 may include a first sub-phase 710 and a second sub-phase 712.

[0080] During the first sub-phase 710, the AP can initiate channel probes, and the STA can estimate channel state information (CSI). For example, AP 702 can send frame 714 to AP 704 (from the AP) to trigger a multi-AP probe. Frame 714 may include a multi-AP trigger frame. Subsequently, APs 702 and 704 can send advertisement frames 716-1 and 716-2 to their respective associated STAs 706 and 708 to announce the transmission of the probe frames. Frames 716-1 and 716-2 may include multi-AP empty data packet announcement (NDPA) frames. Frames 716-1 and 716-2 may be sent simultaneously. Next, APs 702 and 704 can send frames 718-1 and 718-2 to STAs 706 and 708, respectively. Frames 718-1 and 718-2 may include multi-AP empty data packet (NDP) frames. STAs 706 and 708 receive frames 718-1 and 718-2 respectively, and perform channel estimation for the channels from AP 702 to STA 706 and from AP 704 to STA 708 respectively.

[0081] During the second sub-phase 712, the AP can initiate a process for the STAs to feed back channel estimates to the AP. For example, AP 702 can send frame 720 to trigger STAs 706 and 708 to send their channel estimates to APs 702 and 704, respectively. Frame 720 may include a multi-AP trigger frame. In response, STAs 706 and 708 can send frames 722 and 724, respectively, to APs 702 and 704, including feedback on the channel estimates. Frames 722 and 724 may include NDP feedback frames. The feedback on the channel estimates may include NDP feedback, CSI-related information, beamforming report (BFR), or channel quality indication (CQI) report.

[0082] Figure 8 An example 800 of a multi-AP downlink data transmission phase is shown. The multi-AP downlink data transmission phase 800 can be an example of the multi-AP data transmission phase 616. For example... Figure 8 As shown, Example 800 may include a master AP 802 and a slave AP 804 in a multi-AP group. Example 800 may also include a STA 806 associated with AP 802 and a STA 808 associated with AP 804.

[0083] like Figure 8As shown, the multi-AP downlink data transmission phase 800 may include frame switching, enabling the master AP 802 to coordinate with the slave AP 804 to execute specific multi-AP transmission schemes with their associated STAs 806 and 808, respectively. The multi-AP transmission scheme may include COFDMA, CTDMA, CSR, CBF, JT / JR, or a combination of two or more of the above schemes.

[0084] like Figure 8 As shown, the master AP 802 can initiate phase 800 by sending frame 810 to AP 804. Frame 810 may include information related to AP 804 (e.g., an identifier of AP 804), synchronization information, information related to the specific multi-AP transmission scheme to be used, and / or information related to resource elements (RUs) used by AP 804 to acknowledge frame 810. Frame 810 may include a control frame. For example, frame 810 may include a multi-AP trigger frame.

[0085] AP 804 can receive frame 810 and can use synchronization information to synchronize with the master AP 802. Subsequently, APs 802 and 804 can perform data transmissions to their associated STAs 806 and 808, respectively. Specifically, AP 802 can send data frame 812 to its associated STA 806, and AP 804 can send data frame 814 to its associated STA 808. Depending on the multi-AP transmission scheme used, APs 802 and 804 can send frames 812 and 814 to STAs in different BSSs, respectively. For example, when the multi-AP transmission scheme is JT / JR, AP 802 can also send frame 812 to STA 808 associated with AP 804, and AP 804 can also send frame 814 to STA 808 associated with AP 804. The resources used for sending and receiving frames 812 and 814 can depend on the specific multi-AP transmission scheme employed.

[0086] STAs 806 and 808 can acknowledge frames 812 and 814, respectively. For example, STA 806 can send frame 816 to AP 802, and STA 808 can send frame 818 to AP 804. Frames 816 and 818 may include block acknowledgment (BA) frames. When required by the multi-AP transmission scheme used, STAs 804 and 814 can also send frames 816 and 818 to APs in different BSSs. For example, when the multi-AP transmission scheme is JT / JR, STA 806 can also send frame 816 to AP 804, and STA 808 can also send frame 818 to AP 802. The resources used for sending and receiving frames 816 and 818 may depend on the specific multi-AP transmission scheme employed.

[0087] Figure 9 Example 900 of a multi-AP uplink data transmission phase is shown. Multi-AP uplink data transmission phase 900 can be an example of multi-AP data transmission phase 616. For example... Figure 9 As shown, Example 900 may include a master AP 902 and a slave AP 904 in a multi-AP group. Example 900 may also include STAs 906 and 908 associated with AP 902 and STA 910 associated with AP 904.

[0088] like Figure 9 As shown, the multi-AP uplink data transmission phase 900 may include frame switching, enabling the master AP 902 to coordinate with the slave AP 904 to execute specific multi-AP transmission schemes with STAs 906, 908, and 910 / 910 respectively. The multi-AP transmission scheme may include COFDMA, CTDMA, CSR, CBF, JT / JR, or a combination of two or more of the above schemes.

[0089] like Figure 9 As shown, the master AP 902 can initiate phase 900 by sending frame 912 to AP 904. Frame 912 may include information related to AP 904 (e.g., the identifier of AP 904), synchronization information, information related to the specific multi-AP transmission scheme to be used, and / or information related to the RU used by AP 904 to acknowledge frame 912. Frame 912 may include a control frame. For example, frame 912 may include a multi-AP trigger frame.

[0090] AP 904 can receive frame 912 and use synchronization information to synchronize with the master AP 902. Subsequently, APs 902 and 904 can use trigger frames to request uplink data transmission from their associated STAs 906, 908, and 910. Specifically, AP 902 can send trigger frame 914 to its associated STAs 906 and 908, and AP 904 can send trigger frame 916 to its associated STA 910. Depending on the multi-AP transmission scheme used, APs 902 and 904 can also send frames 914 and 916 to STAs in different BSSs, respectively. For example, when the multi-AP transmission scheme is JT / JR, AP 902 can also send frame 914 to STA 910 associated with AP 904, and AP 904 can also send frame 916 to STAs 906 and 908 associated with AP 902. The resources used to send and receive frames 914 and 916 can depend on the specific multi-AP transmission scheme employed.

[0091] STAs 906 and 908 can respond to frame 914, and STA 910 can respond to frame 916. For example, STAs 906 and 908 can send frames 918 and 920 to AP 902, respectively, while STA 910 can send frame 922 to AP 904. Frames 918, 920, and / or 922 can be sent simultaneously. Frames 918, 920, and 922 can include data frames or empty data frames. When required by the multi-AP transmission scheme, STAs 906, 908, and 910 can also send frames 918, 920, and 922 to APs in different BSSs, respectively. For example, when the multi-AP transmission scheme is JT / JR, STAs 906 and 908 can also send the corresponding frames 918 and 920 to AP 904, and STA 910 can also send frame 922 to AP 902. The resources used to send and receive frames 918, 920, and 922 may depend on the specific multi-AP transmission scheme employed. AP 902 can acknowledge frames 918 and 920 by sending a multi-STA BA frame 924 to STAs 906 and 908. AP 904 can acknowledge frame 922 by sending a BA frame 926 to STA 910.

[0092] Figure 10 Example 1000 shows STA 1006 transitioning / roaming from AP 1002 to AP 1004. Before transitioning / roaming from AP 1002 to AP 1004, STA 1006 can be associated with AP 1002. When STA 1006 moves from the communication range of AP 1002 to the communication range of AP 1004, STA 1006's communication session is transferred from AP 1002 to AP 1004. The IEEE 802.11 standard defines the Basic Service Set (BSS) transition process (see below). Figure 11 (As described in the text), it can be used to transfer the communication session of STA1006 from AP 1002 to AP 1004.

[0093] Figure 10 An example of a 1000 BSS conversion according to the IEEE 802.11 standard is shown. Figure 10 As shown, Example 1000 may include AP 1002, AP 1004, and STA 1006. STA 1006 may be associated with AP 1002 at the beginning of Example 1000 and may have already established a security session 1008 with AP 1002.

[0094] STA 1006 initiates the transition process by sending an authentication request frame 1010 to AP 1004. IEEE 802.10 authentication operates at the link level between IEEE 802.10 STAs. The IEEE 802.10 standard attempts to control LAN access via an authentication service. IEEE 802.10 authentication is a station service. All STAs can use this service to establish their identity with the APs they communicate with. If a mutually acceptable authentication level has not yet been established between the STA and the AP, no association is established.

[0095] If AP 1004 accepts authentication request frame 1010, then AP 1004 may send authentication response frame 1012 to STA 1006. Upon receiving authentication response frame 1012, STA 1006 may send association request frame 1014 to AP 1004 to request the initiation of a secure session with AP 1004. If AP 1004 accepts STA 1006's association request, then AP 1004 sends association response frame 1016 to indicate that a secure session has been established.

[0096] Figure 10 A drawback of the BSS transition process shown is the time required for exchanging the authentication request frame 1010 and the authentication response frame 1012. To mitigate this problem, the IEEE 802.10 standard introduced the Fast BSS Transition (FT) protocol. The FT protocol seeks to reduce the length of time the STA and distribution system (DS) lose connection during BSS transitions. The FT protocol is part of the reassociation service and applies only to STA transitions between APs within the same mobile domain within the same Extended Service Set (ESS). The FT protocol requires the exchange of information during the initial association (or subsequent reassociation) between the STA (represented as the FT Originator (FTO)) and the AP. The initial exchange is called the FT Initial Mobile Domain Association. Subsequent reassociation with APs within the same mobile domain can utilize the FT protocol.

[0097] The IEEE 802.11 standard defines two FT protocols: the FT protocol and the FT resource request protocol. The FT protocol is executed when the FTO makes a transition to the target AP and does not require a resource request before the transition. The FT resource request protocol is executed when the FTO requires a resource request before the transition. For an FTO to move from its current AP to a target AP using the FT protocol, message exchange is performed using one of two methods: via radio or via DS. Using the radio method, the FTO communicates directly with the target AP using IEEE 802.10 authentication utilizing the FT authentication algorithm. Using the DS method, the FTO communicates with the target AP via the current AP.

[0098] Communication between the FTO and the target AP is carried in the FT action frames between the FTO and the current AP. Communication between the current AP and the target AP is via encapsulation. The current AP translates between the two encapsulations. The AP advertises both the capabilities and policies used to support the FT protocol and methods.

[0099] Figure 11 An example of the 1100 using the FT protocol via the DS method is shown. Figure 11 As shown, Example 1100 may include AP 1102, AP 1104, and STA 1106. STA 1106 may be associated with AP 1102 at the beginning of Example 1100 and may have already established a secure session 1108 with AP 1102. AP 1102 and AP 1104 can communicate via DS. STA 1106 is an FTO. AP 1104 is the target AP.

[0100] Fast BSS transition via DS can begin with STA 1106 (FTO) sending an FT request 1110 to AP 1104 (the target AP) via AP 1102. FT request 1110 may include the address of STA 1106 (e.g., MAC address) and the address of AP 1104 (e.g., BSSID). AP 1104 can respond to FT request 1110 by sending an FT response 1112 to STA 1106 via AP 1102. FT response 1112 may include the address of STA 1106, the address of AP 1104, and its status. If STA 1106 does not receive a response to FT request 1110, it can retransmit the request following the restrictions given for authentication frames.

[0101] If the status indication in FT response 1112 is successful (SUCCESS), STA 1106 can send a reassociation request frame 1114 to AP 1104. AP 1104 can respond to STA 1106 with a reassociation response 1116.

[0102] Although the FT protocol eliminates the need for an authentication step, its drawback is that the FTO and the target AP still need to perform the reassociation step.

[0103] Figure 12 Example 1200 shows a procedure for session transfer via roaming. Figure 12 As shown, Example 1200 may include STA 1202, AP 1204, AP 1206, and controller 1208. Controller 1208 enables communication between AP 1204 and AP 1206. Controller 1208 can handle authentication and association; therefore, for session transfer, the authentication and association steps may not need to be repeated.

[0104] At the beginning of Example 1200, STA 1202 may be associated with AP 1204 and may have already established a secure session with AP 1204. To initiate a session transfer from AP 1204 to AP 1206, STA 1202 may send one or more uplink data frames 1210 to AP 1204, including all buffered uplink data. Subsequently, STA 1202 may send a Roaming Advertisement Indicator (RAI) (or Roaming Request) frame 1212 to AP 1204. The RAI frame 1212 may include the address of AP 1206.

[0105] Upon receiving frame 1212, AP 1204 can communicate with controller 1208 to determine whether session transfer has been approved. If controller 1208 approves the session transfer, AP 1204 transmits frame 1214 to STA 1202. Frame 1212 may be referred to as a Roaming Declaration Response (RAR) frame or a Roaming Response frame.

[0106] If controller 1208 approves the session transfer, it transfers the context associated with STA 1202 from AP 1204 to AP 1206. The context associated with STA 1202 may include the sequence number of each service identifier for STA 1202. Controller 1208 may also change the data path of incoming data from AP 1204 to AP 1206. After sending frame 1214, AP 1204 may send one or more downlink data frames 1216 to STA 1202 (containing all buffered downlink data of STA 1202). After AP 1204 has sent all data in its buffer for STA 1202, AP 1206 may send a link deletion frame 1222 to STA 1202 indicating that the link between STA 1202 and AP 1204 has been deleted and STA 1202 can no longer communicate with AP 1204.

[0107] STA 1202 can begin communicating with AP 1206 after receiving frame 1214. Specifically, AP 1206 can transfer packets received from the upper layer to STA 1202 via one or more downlink data frames 1218. Conversely, STA 1202 can send one or more uplink data frames 1220 to AP 1206.

[0108] As mentioned above, Figure 12The process requires STA 1202 to send all of its uplink data to AP 1204 (exhausting its uplink data) before sending a roaming request to AP 1204. This has the advantage that data that may be part of an ongoing switch is protected to some extent from potential disruptions caused by the handover. However, the inventors have recognized that a potential problem in this process is that STA 1202 may take a relatively long time to exhaust its uplink data (e.g., STA 1202 may be unable to access the channel due to heavy channel contention, and / or STA 1202 may have a large amount of buffered uplink data). This may delay STA 1202 sending the roaming request and the transition of STA 1202 from AP 1204 to AP 1206. Simultaneously, the link between STA 1202 and AP 1204 may deteriorate, and STA 1202 may even lose its connection to AP 1204. Due to the delayed transition (roaming) from AP 1204 to AP 1206, buffered data at STA 1202 may be lost.

[0109] As further described below, embodiments of this disclosure address the aforementioned problems of the prior art. In one aspect, the STA may send a first frame to a first AP indicative of / requesting a transition (roaming) from the first AP to a second AP. The STA may receive from the first AP a second frame indicative of parameters relating to the transmission of data buffered at the STA to the first AP prior to the transition (roaming) from the first AP to the second AP. In one embodiment, the parameters may indicate whether the STA wants to send the amount of data buffered at the STA to the first AP prior to the transition (roaming) from the first AP to the second AP. In one example, the parameters may indicate that the STA does not want to send any data buffered at the STA to the first AP prior to the transition (roaming) from the first AP to the second AP. In another embodiment, the parameters may indicate the amount of data buffered at the STA to be sent to the first AP prior to the transition (roaming) from the first AP to the second AP. In yet another embodiment, alternatively or additionally, the parameters may indicate a first service identifier (TID) (or first access class) of the first data in the data buffered at the STA to be sent to the first AP prior to the transition (roaming) from the first AP to the second AP. In another embodiment, alternatively or additionally, the parameter may indicate the first duration of the transmission of a portion of the data buffered at the STA to the first AP before the data is transferred (roamed) from the first AP to the second AP.

[0110] The parameters can be based on signal strength. In one embodiment, signal strength may include the received signal strength of a frame transmitted by a first AP and received by a STA. In another embodiment, signal strength may include the received signal strength of a frame transmitted by a second AP and received by a STA. In yet another embodiment, signal strength may include the received signal strength of a frame transmitted by a STA and received by a first AP. In yet another embodiment, signal strength may include the received signal strength of a frame transmitted by a STA and received by a second AP.

[0111] The STA can send the first data from its buffer to the AP based on parameters before the transition from the first AP to the second AP. This allows the AP to control the amount and type of data sent by the STA before the transition. This can reduce the amount of data sent to the first AP before the transition and speed up the transition process.

[0112] Figure 13 Example 1300 of a roaming process according to an embodiment is shown. Example 1300 is provided for illustrative purposes only and does not limit the embodiments of this disclosure. Figure 13 As shown, Example 1300 may include STA 1302, AP 1304 and 1306, and device 1308. In one embodiment, each of AP 1304, AP 1306, and STA 1302 may be a multi-link device (MLD), which is a device capable of operating on multiple links as defined by the IEEE 802.11 standard.

[0113] Device 1308 can be a controller. Device 1308 can be connected to each of APs 1304 and 1306 (e.g., via wired / wireless backhaul). Therefore, device 1308 can enable communication between APs 1304 and 1306. For example, device 1308 can enable context transfer between APs 1304 and 1306 when a STA associated with one of APs 1304 and 1306 roams / transfers to the other. Therefore, when a STA roams / transfers between APs 1304 and 1306, it may not be necessary to perform STA association and authentication again.

[0114] At the beginning of Example 1300, STA 1302 may be associated with AP 1304 and may have already established a secure session with AP 1304. In one embodiment, STA 1302 may have an established link with AP 1304. In one example, STA 1302 may determine to initiate a session transfer from AP 1304. When STA 1302 initiates a session transfer, STA 1302 may have buffered data for transmission to AP 1304. To initiate a session transfer from AP 1304 to another AP, STA 1302 may send frame 1310 to AP 1304. Frame 1310 may indicate a transition (roaming) from AP 1304 to AP 1306. Frame 1310 may include a roaming request.

[0115] Frame 1310 may include a link reconfiguration notification frame, a roaming announcement notification frame, a roaming announcement request frame, a roaming request frame, a roaming notification frame, or a probe request frame.

[0116] Upon receiving frame 1310, AP 1304 may send frame 1312 to STA 1302. Frame 1312 may include a roaming response. Frame 1312 may indicate parameters related to the transmission from STA 1302 to AP 1304 of data buffered at STA 1302 for AP 1304 prior to the transition (roaming) from AP 1304 to AP 1306.

[0117] In one embodiment, the parameter may indicate whether STA 1302 should send the amount of data buffered at STA 1302 to AP 1304 before transitioning (roaming) from AP 1304 to AP 1306. For example, the parameter may indicate that STA 1302 should not send any data buffered at STA 1302 to AP 1304 before transitioning (roaming) from AP 1304 to AP 1306. In another example, the parameter may indicate that STA 1302 should send all of the data buffered at STA to AP 1304 before transitioning (roaming) from AP 1304 to AP 1306. In yet another embodiment, the parameter may indicate the amount of data buffered at STA 1304 to AP 1304 before transitioning (roaming) from AP 1304 to AP 1306. For example, the amount may be indicated as the number of bits, bytes, or octets. In one example, the amount may be equal to zero.

[0118] In another embodiment, alternatively or additionally, the parameter may indicate a first service identifier (TID) (or first access class) of the first data in the data buffered at STA 1302 to be sent to AP 1304 before transitioning (roaming) from AP 1304 to AP 1306. In one embodiment, frame 1310 may indicate one or more TIDs (or one or more ACs) associated with the data buffered at STA 1302. In one implementation, frame 1310 may include a buffer status report (BSR) indicating one or more TIDs. The one or more TIDs (or one or more ACs) may include a first TID (or a first AC).

[0119] In another embodiment, alternatively or additionally, the parameter may indicate a first duration of transmission of a portion of the data buffered at STA 1302 to AP 1304 prior to transition (roaming) from AP 1304 to AP 1306. In one embodiment, the first duration includes the duration of a transmission opportunity (TXOP) initiated by frame 1312. In one embodiment, frame 1310 indicates a second duration. The first duration may be based on the second duration. In one embodiment, the first duration is less than or equal to the second duration. In one embodiment, the second duration includes the duration of the TXOP initiated by frame 1310.

[0120] In one embodiment, the parameter may be based on signal strength. In one embodiment, signal strength may include the received signal strength of a frame transmitted by AP 1304 and received by STA 1302. Examples of such frames may include a beacon frame transmitted by AP 1304 or an acknowledgment frame transmitted by AP 1304 to STA 1302. In one embodiment, when the received signal strength is below a threshold, the parameter may indicate a small amount (e.g., zero) of buffered data transmitted from STA 1302 to AP 1304 before the transition from AP 1304 to AP 1306, one or more TIDs associated with low latency services, or a short duration of transmission to AP 1304 before the transition from AP 1304 to AP 1306.

[0121] In another embodiment, signal strength may include the received signal strength of a frame transmitted by AP 1306 and received by STA 1302. An example of such a frame may be a beacon frame transmitted by AP 1306. In one embodiment, when the received signal strength is greater than or equal to a threshold, the parameter may indicate a small amount (e.g., zero) of buffered data transmitted from STA 1302 to AP 1304 before the transition from AP 1304 to AP 1306, one or more TIDs associated with low latency services, or a short duration of transmission to AP 1304 before the transition from AP 1304 to AP 1306.

[0122] In another embodiment, signal strength may include the received signal strength of a frame transmitted by STA 1302 and received by AP 1304. Examples of such frames may include data frames transmitted by STA 1302 to AP 1304. In one embodiment, when the received signal strength is below a threshold, the parameter may indicate a small amount (e.g., zero) of buffered data transmitted from STA 1302 to AP 1304 before the transition from AP 1304 to AP 1306, one or more TIDs associated with low latency services, or a short duration of transmission to AP 1304 before the transition from AP 1304 to AP 1306.

[0123] In another embodiment, signal strength may include the received signal strength of a frame transmitted by STA 1302 and received by AP 1306. Examples of such frames may include data frames transmitted by STA 1302 to AP 1304 and received by AP 1306. In one embodiment, when the received signal strength is greater than or equal to a threshold, the parameter may indicate a small amount (e.g., zero) of buffered data transmitted from STA 1302 to AP 1304 before the transition from AP 1304 to AP 1306, one or more TIDs associated with low latency services, or a short duration of transmission to AP 1304 before the transition from AP 1304 to AP 1306.

[0124] return Figure 13Upon receiving frame 1312, STA 1302 may send frame 1314 to AP 1304. In one embodiment, STA 1302 may send frame 1314 based on parameters indicated in frame 1312. For example, frame 1314 may be a data frame including an amount of buffered data based on the parameters indicated in frame 1312. In another instance, alternatively or additionally, frame 1314 may be a data frame including a TID (or AC) based on the parameters indicated in frame 1312. In yet another example, alternatively or additionally, STA 1302 may send frame 1314 for a duration indicated by the parameters indicated in frame 1312.

[0125] After receiving frame 1314, AP 1304 can communicate with device 1308 for switching / roaming. Device 1308 transfers the context associated with STA 1302 from AP 1304 to AP 1306. The context associated with STA 1302 may include the sequence number of each service identifier of STA 1302. Device 1308 can also change the data path of data entering from the upper layer from AP 1304 to AP 1306. AP 1304 can send one or more downlink data frames 1316 to STA 1302 (including all its buffered downlink data for STA 1302). After AP 1304 has sent all the data in its buffer for STA 1302, AP 1306 can send a link deletion frame 1318 to STA 1302 indicating that the link between STA 1302 and AP 1304 has been deleted and STA 1302 can no longer communicate with AP 1304.

[0126] Figure 14 Example 1400 of a roaming process according to an embodiment is shown. Example 1400 is provided for illustrative purposes only and does not limit the embodiments of this disclosure. Figure 14 As shown, Example 1400 may include STA 1402, AP 1404 and 1406, and device 1408. In one embodiment, each of AP 1404, AP 1406, and STA 1402 may be a multi-link device (MLD), which is a device capable of operating on multiple links as defined by the IEEE 802.11 standard.

[0127] Device 1408 can be a controller. Device 1408 can be connected to each of APs 1404 and 1406 (e.g., via wired / wireless backhaul). Therefore, device 1408 can enable communication between APs 1404 and 1406. For example, device 1408 can enable context transfer between APs 1404 and 1406 when a STA associated with one of APs 1404 and 1406 roams / transfers to the other. Therefore, when a STA roams / transfers between APs 1404 and 1406, it may not be necessary to perform STA association and authentication again.

[0128] At the beginning of Example 1400, STA 1402 may be associated with AP 1404 and may have already established a secure session with AP 1404. In one embodiment, STA 1402 may have an established link with AP 1404. In one example, STA 1402 may determine to initiate a session transfer from AP 1404. When STA 1402 initiates a session transfer, STA 1402 may have buffered data for transmission to AP 1404. To initiate a session transfer from AP 1404 to another AP, STA 1402 may send frame 1410 to AP 1404. Frame 1410 may indicate a transition (roaming) from AP 1404 to AP 1406. Frame 1410 may include a roaming request.

[0129] Frame 1410 may include a link reconfiguration notification frame, a roaming announcement notification frame, a roaming announcement request frame, a roaming request frame, a roaming notification frame, or a probe request frame.

[0130] Upon receiving frame 1410, AP 1404 may send frame 1412 to STA 1402. Frame 1412 may include a roaming response. Frame 1412 may indicate parameters relating to the transmission from STA 1402 to AP 1404 of data buffered at STA 1402 for AP 1404 prior to the transition (roaming) from AP 1404 to AP 1406. In Example 1400, the parameters indicate the amount (X) of data buffered at STA 1402 to be sent to AP 1404 prior to the transition (roaming) from AP 1404 to AP 1406. The amount (X) may be indicated as the number of bits, bytes, octets, etc.

[0131] Upon receiving frame 1412, STA 1402 may send frame 1414 to AP 1404 based on the parameters indicated in frame 1412. Frame 1414 may be a data frame including an amount (X) of buffered data based on the parameters indicated in frame 1412. In another example, STA 1402 may send multiple frames to AP 1404 including data with a total size equal to the amount (X) indicated by the parameters indicated in frame 1412.

[0132] In one embodiment, based on received frame 1414, AP 1404 may send frame 1416 to STA 1402 instructing STA 1402 to roam / switch from AP 1404 to AP 1406. Based on received frame 1416, STA 1402 may begin sending uplink data to AP 1406.

[0133] In another embodiment, upon receiving frame 1414, AP 1404 may further communicate with device 1408 to initiate a context transfer to AP 1406. Device 1408 transfers the context associated with STA 1402 from AP 1404 to AP 1406. The context associated with STA 1402 may include the sequence number of each service identifier of STA 1402. Device 1408 may also change the data path of data entering from the upper layer from AP 1404 to AP 1406. AP 1404 may send one or more downlink data frames to STA 1402. Figure 14 (Not shown in the image) (e.g., including all downlink data buffered for STA 1402). In one embodiment, after AP 1404 sends all data in its buffer to STA 1402, AP 1404 sends frame 1416 to STA 1402. In another embodiment, after AP 1404 has sent all data in its buffer for STA 1402, AP 1406 may send a link deletion frame 1418 to STA 1402 indicating that the link between STA 1402 and AP 1404 has been deleted and STA 1402 can no longer communicate with AP 1404.

[0134] Figure 15 Example 1500 of a roaming process according to an embodiment is shown. Example 1500 is provided for illustrative purposes only and does not limit the embodiments of this disclosure. Figure 15As shown, Example 1500 may include STA 1502, AP 1504 and 1506, and device 1508. In one embodiment, each of AP 1504, AP 1506, and STA 1502 may be a multi-link device (MLD), which is a device capable of operating on multiple links as defined by the IEEE 802.11 standard.

[0135] Device 1508 can be a controller. Device 1508 can be connected to each of APs 1504 and 1506 (e.g., via wired / wireless backhaul). Therefore, device 1508 can enable communication between APs 1504 and 1506. For example, device 1508 can enable context transfer between APs 1504 and 1506 when a STA associated with one of APs 1504 and 1506 roams / transfers to the other. Therefore, when a STA roams / transfers between APs 1504 and 1506, it may not be necessary to perform STA association and authentication again.

[0136] At the beginning of Example 1500, STA 1502 may be associated with AP 1504 and may have already established a secure session with AP 1504. In one embodiment, STA 1502 may have an established link with AP 1504. In one example, STA 1502 may determine to initiate a session transfer from AP 1504. When STA 1502 initiates a session transfer, STA 1502 may have buffered data for transmission to AP 1504. To initiate a session transfer from AP 1504 to another AP, STA 1502 may send frame 1510 to AP 1504. Frame 1510 may indicate a transition (roaming) from AP 1504 to AP 1506. Frame 1510 may include a roaming request. Frame 1510 may include a link reconfiguration notification frame, a roaming announcement notification frame, a roaming announcement request frame, a roaming request frame, a roaming notification frame, or a probe request frame. In one embodiment, frame 1510 may include a buffer status report (BSR) indicating one or more TIDs (or one or more ACs) of data buffered at STA 1502 for AP 1504.

[0137] Upon receiving frame 1510, AP 1504 may send frame 1512 to STA 1502. Frame 1512 may include a roaming response. Frame 1512 may indicate parameters relating to the transmission from STA 1502 to AP 1504 of data buffered at STA 1502 for AP 1504 prior to the transition (roaming) from AP 1504 to AP 1506. In Example 1500, the parameters indicate a first TID (TID 1) (or a first access class of one or more ACs) among one or more service identifiers (TIDs) of the first data to be sent to AP 1504 prior to the transition (roaming) from AP 1504 to AP 1506 in the data buffered at STA 1502. For example, the first TID (TID 1) may correspond to a low latency service, and the first data may correspond to low latency data in the data buffered at STA 1502 for AP 1504.

[0138] Upon receiving frame 1512, STA 1502 can send frame 1514 to AP 1504 based on the parameters indicated in frame 1512. Frame 1514 can be a data frame including a TID (or AC) based on the parameters indicated in frame 1512. Specifically, as... Figure 15 As shown, frame 1514 may be a data frame associated with the first TID (TID 1).

[0139] In one embodiment, frame 1514 may further include a BSR indicating one or more TIDs (or one or more ACs) buffered at STA 1502 for data used by AP 1504. In one embodiment, based on the BSR indicating a queue size with a value of zero for the first TID (TID 1), AP 1504 may send frame 1516 to STA 1502 instructing STA 1502 to roam / transition from AP 1504 to AP 1506. Based on receiving frame 1516, STA 1502 may begin sending uplink data to AP 1506.

[0140] In one embodiment, upon receiving frame 1514, AP 1504 may communicate with device 1508 to initiate a context transfer to AP 1506. Device 1508 transfers the context associated with STA 1502 from AP 1504 to AP 1506. The context associated with STA 1502 may include the sequence number of each service identifier of STA 1502. Device 1508 may also change the data path of data entering from the upper layer from AP 1504 to AP 1506. In one embodiment, AP 1504 may send one or more downlink data frames to STA 1502. Figure 15(Not shown) (including all its buffered downlink data for STA 1502). In one embodiment, after AP 1504 sends all the data in its buffer to STA 1502, AP 1504 sends frame 1516 to STA 1502. In another embodiment, after AP 1504 has sent all the data in its buffer for STA 1502, AP 1506 may send a link deletion frame 1518 to STA 1502 indicating that the link between STA 1502 and AP 1504 has been deleted and that STA 1502 can no longer communicate with AP 1504.

[0141] Figure 16 Example 1600 of a roaming process according to an embodiment is shown. Example 1600 is provided for illustrative purposes only and does not limit the embodiments of this disclosure. Figure 16 As shown, Example 1600 may include STA 1602, AP 1604 and 1606, and device 1608. In one embodiment, each of AP 1604, AP 1606, and STA 1602 may be a multilink device (MLD), which is a device capable of operating on multiple links as defined by the IEEE 802.11 standard.

[0142] Device 1608 can be a controller. Device 1608 can be connected to each of APs 1604 and 1606 (e.g., via wired / wireless backhaul). Therefore, device 1608 can enable communication between APs 1604 and 1606. For example, device 1608 can enable context transfer between APs 1604 and 1606 when a STA associated with one of APs 1604 and 1606 roams / transfers to the other. Therefore, when a STA roams / transfers between APs 1604 and 1606, it may not be necessary to perform STA association and authentication again.

[0143] At the beginning of Example 1600, STA 1602 may be associated with AP 1604 and may have already established a secure session with AP 1604. In one embodiment, STA 1602 may have an established link with AP 1604. In one example, STA 1602 may determine to initiate a session transfer from AP 1604. When STA 1602 initiates a session transfer, STA 1602 may have buffered data for transmission to AP 1604. To initiate a session transfer from AP 1604 to another AP, STA 1602 may send frame 1610 to AP 1604. Frame 1610 may indicate a transition (roaming) from AP 1604 to AP 1606. Frame 1610 may include a roaming request. Frame 1610 may include a link reconfiguration notification frame, a roaming announcement notification frame, a roaming announcement request frame, a roaming request frame, a roaming notification frame, or a probe request frame. In one embodiment, frame 1610 may include a parameter instructing STA 1602 to send buffered data for AP 1604 for AP 1604 for a first duration (equal to x). In one embodiment, the first duration includes the duration of the TXOP initiated by frame 1610. In one embodiment, the first duration may correspond to a duration requested / preferred / recommended by STA 1602.

[0144] Upon receiving frame 1610, AP 1604 may send frame 1612 to STA 1602. Frame 1612 may include a roaming response. Frame 1612 may indicate parameters relating to the transmission of data buffered at STA 1602 for AP 1604 from STA 1602 to AP 1604 prior to a transition (roaming) from AP 1604 to AP 1606. In Example 1600, the parameters indicate a second duration (equal to y) of the transmission of a portion of data buffered at STA 1602 for AP 1604 from STA 1602 to AP 1604 prior to a transition (roaming) from AP 1604 to AP 1606. The second duration may include the duration of a transmission opportunity (TXOP) initiated by frame 1612. The second duration may be based on a first duration. The second duration may be less than or equal to the first duration.

[0145] Upon receiving frame 1612, STA 1602 may send one or more frames to AP 1604 during a second duration indicated by parameters. For example, STA 1602 may send frames 1614 and 1616, which include data for AP 1604, during the second duration indicated by parameters. AP 1604 can then send corresponding BA frames to STA 1602. Figure 16 (Not shown in the image) in response to frames 1614 and 1616.

[0146] In one embodiment, after the second duration ends, AP 1604 may send frame 1618 to STA 1602 instructing STA 1602 to roam / switch from AP 1604 to AP 1606. Based on the received frame 1618, STA 1602 may begin sending uplink data to AP 1606.

[0147] In one embodiment, after receiving frames 1614 and 1616 and / or after the end of the second duration, AP 1604 may communicate with device 1608 to initiate a context transfer to AP 1606. Device 1608 transfers the context associated with STA 1602 from AP 1604 to AP 1606. The context associated with STA 1602 may include the sequence number of each service identifier of STA 1602. Device 1608 may also change the data path of data entering from the upper layer from AP 1604 to AP 1606. In one embodiment, AP 1604 may send one or more downlink data frames to STA 1602 ( Figure 16 (Not shown) (including all its buffered downlink data for STA 1602). In one embodiment, after AP 1604 sends all the data in its buffer to STA 1602, AP 1604 sends frame 1618 to STA 1602. In another embodiment, after AP 1604 has sent all the data in its buffer for STA 1602, AP 1606 may send a link deletion frame 1620 to STA 1602 indicating that the link between STA 1602 and AP 1604 has been deleted and that STA 1602 can no longer communicate with AP 1604.

[0148] Figure 17 An example process 1700 according to an embodiment is illustrated. The example process 1700 is provided for illustrative purposes only and is not intended to limit the embodiments. Process 1700 may be performed by a first AP (such as AP 1304, AP 1404, AP 1504, or AP 1604). Figure 17 As shown, process 1700 may include steps 1702 and 1704.

[0149] Step 1702 includes the first AP receiving a first frame from the STA indicating a transition (roaming) from the first AP to the second AP. The first frame may include a roaming request. The STA may be associated with the first AP.

[0150] Step 1704 includes: the first AP sending a second frame to the STA indicating parameters related to the transmission of data buffered at the STA to the first AP prior to the transition (roaming) from the first AP to the second AP. In one embodiment, the second frame may include a roaming response.

[0151] In one embodiment, the parameter can indicate whether the STA should send the amount of data buffered at the STA to the first AP before switching (roaming) from the first AP to the second AP.

[0152] In another embodiment, the parameters may instruct the STA not to send any data buffered at the STA to the first AP before switching (roaming) from the first AP to the second AP.

[0153] In another embodiment, the parameters instruct the STA to send all the data buffered at the STA to the first AP before switching (roaming) from the first AP to the second AP.

[0154] In another embodiment, the parameter may indicate the amount of data buffered at the STA to be sent to the first AP before transitioning (roaming) from the first AP to the second AP. In one embodiment, the amount may indicate bits, bytes, or octets. In another embodiment, the amount may be zero. In one embodiment, process 1700 may further include: the first AP receiving one or more third frames from the STA, the one or more third frames including first data for the first AP having a total size equal to the amount indicated by the parameter.

[0155] In one embodiment, process 1700 may further include: based on the reception of first data, the first AP sends a fourth frame to the STA, the fourth frame instructing the STA to roam / switch from the first AP to the second AP.

[0156] In one embodiment, the parameter may indicate the first service identifier (TID) (or first access class (AC)) of the first data in the data buffered at the STA to be sent to the first AP before transitioning (roaming) from the first AP to the second AP.

[0157] In one embodiment, the first frame may indicate one or more TIDs (one or more ACs) associated with data buffered at the STA. In one embodiment, the first frame may include a Buffer Status Report (BSR) indicating one or more TIDs. The one or more TIDs (one or more ACs) may include a first TID (or a first AC).

[0158] In one embodiment, process 1700 may further include: receiving a third frame from a STA by a first AP, the third frame including: a data frame associated with a first TID; and a second BSR.

[0159] In one embodiment, process 1700 may include: sending a fourth frame from the first AP to the STA based on a second BSR indicating a queue size with a zero value for the first TID, the fourth frame indicating that the STA roams / transfers from the first AP to the second AP.

[0160] In another embodiment, the parameter may indicate a first duration of transmission of a portion of the data buffered at the STA to the first AP before transitioning (roaming) from the first AP to the second AP. In one embodiment, the first duration may include the duration of a transmission opportunity (TXOP) initiated by the second frame.

[0161] In one embodiment, the first frame may indicate a second duration. The first duration may be based on the second duration. In one embodiment, the first duration may be less than or equal to the second duration. In one embodiment, the second duration may include the duration of a transmission opportunity (TXOP) initiated by the first frame.

[0162] In one embodiment, process 1700 may include: receiving one or more third frames from a STA by a first AP, the third frames including data for the first AP during a first duration indicated by parameters.

[0163] In one embodiment, process 1700 may further include: after the first duration ends, the first AP sends a fourth frame to the STA, the fourth frame instructing the STA to roam / switch from the first AP to the second AP.

[0164] In one embodiment, the parameter may be based on signal strength. In one embodiment, signal strength may include the received signal strength of a frame transmitted by a first AP and received by a STA. In another embodiment, signal strength may include the received signal strength of a frame transmitted by a second AP and received by a STA. In yet another embodiment, signal strength may include the received signal strength of a frame transmitted by a STA and received by a second AP.

[0165] Figure 18 An example process 1800 according to an embodiment is illustrated. The example process 1800 is provided for illustrative purposes only and is not intended to limit the embodiments. Process 1800 may be performed by an STA (such as STA 1302, STA 1402, STA 1502, or STA 1602). Figure 18 As shown, process 1800 may include steps 1802 and 1804.

[0166] Step 1802 includes the STA sending a first frame to the first AP indicating a transition (roaming) from the first AP to the second AP. The STA may be associated with the first AP.

[0167] Step 1804 includes: the STA receiving a second frame from the first AP indicating parameters related to the transmission of data buffered at the STA from the first AP to the first AP before switching (roaming) from the first AP to the second AP.

[0168] In one embodiment, the parameter can indicate whether the STA should send the amount of data buffered at the STA to the first AP before switching (roaming) from the first AP to the second AP.

[0169] In another embodiment, the parameters may instruct the STA not to send any data buffered at the STA to the first AP before switching (roaming) from the first AP to the second AP.

[0170] In another embodiment, the parameters instruct the STA to send all the data buffered at the STA to the first AP before switching (roaming) from the first AP to the second AP.

[0171] In another embodiment, the parameter may indicate the amount of data buffered at the STA to be sent to the first AP before transitioning (roaming) from the first AP to the second AP. In one embodiment, the amount may indicate bits, bytes, or octets. In another embodiment, the amount may be zero. In one embodiment, process 1800 may further include: the STA sending one or more third frames to the first AP, the third frames including first data for the first AP having a total size equal to the amount indicated by the parameter.

[0172] In one embodiment, process 1800 may further include: the STA receiving a fourth frame from the first AP, the fourth frame indicating that the STA roams / transfers from the first AP to the second AP.

[0173] In one embodiment, the parameter may indicate the first service identifier (TID) (or first access class (AC)) of the first data in the data buffered at the STA to be sent to the first AP before transitioning (roaming) from the first AP to the second AP.

[0174] In one embodiment, the first frame may indicate one or more TIDs (one or more ACs) associated with data buffered at the STA. In one embodiment, the first frame may include a Buffer Status Report (BSR) indicating one or more TIDs (one or more ACs). The one or more TIDs (or one or more ACs) may include a first TID (first AC).

[0175] In one embodiment, process 1800 may further include: the STA sending a third frame to the first AP, the third frame including: a data frame associated with the first TID, and a second BSR.

[0176] In one embodiment, process 1800 may include: receiving a fourth frame from a first AP based on a second BSR indicating a queue size with a zero value for a first TID, the fourth frame indicating that the STA is roaming / switching from the first AP to a second AP.

[0177] In another embodiment, the parameter may indicate a first duration of transmission of a portion of the data buffered at the STA to the first AP before transitioning (roaming) from the first AP to the second AP. In one embodiment, the first duration may include the duration of a transmission opportunity (TXOP) initiated by the second frame.

[0178] In one embodiment, the first frame may indicate a second duration. The first duration may be based on the second duration. In one embodiment, the first duration may be less than or equal to the second duration. In one embodiment, the second duration may include the duration of a transmission opportunity (TXOP) initiated by the first frame.

[0179] In one embodiment, process 1800 may further include: the STA sending one or more third frames to the first AP, the one or more third frames including services for the first AP during a first duration indicated by parameters.

[0180] In one embodiment, process 1800 may include: after the first duration ends, the STA receives a fourth frame from the first AP, the fourth frame indicating that the STA roams / transfers from the first AP to the second AP.

[0181] In one embodiment, the parameter may be based on signal strength. In one embodiment, signal strength may include the received signal strength of a frame transmitted by a first AP and received by a STA. In another embodiment, signal strength may include the received signal strength of a frame transmitted by a second AP and received by a STA. In yet another embodiment, signal strength may include the received signal strength of a frame transmitted by a STA and received by a second AP.

Claims

1. A method comprising: A first frame is received by a slave station (STA) from a first access point (AP), the first frame indicating a transition from the first AP to a second AP; as well as The first AP sends a second frame to the STA, the second frame indicating parameters related to the transmission of data buffered at the STA to the first AP before switching from the first AP to the second AP.

2. The method according to claim 1, in, The first frame includes a buffer status report (BSR), which indicates one or more service identifiers (TIDs) associated with services buffered at the STA for the first AP. The instruction to switch from the first AP to the second AP refers to a request to roam (switch) from the first AP to the second AP. and The parameters relating to transmission to the first AP include the first TID among the one or more TIDs. The method includes: The first AP receives a third frame from the STA, the third frame including: The data frame associated with the first TID; and Second BSR; and Based on the second BSR indicating a queue size with a zero value for the first TID, the first AP sends a fourth frame to the STA, the fourth frame indicating that the STA is switching from the first AP to the second AP.

3. A method comprising: The station (STA) sends a first frame to the first access point (AP), the first frame indicating the transition from the first AP to the second AP; as well as The STA receives a second frame from the first AP, the second frame indicating parameters related to the transmission of data buffered at the STA from the STA to the first AP before the transition from the first AP to the second AP.

4. The method according to claim 3, in, The first frame includes a buffer status report (BSR), which indicates one or more service identifiers (TIDs) associated with services buffered at the STA for the first AP. The instruction to switch from the first AP to the second AP refers to a request to roam (switch) from the first AP to the second AP. and The parameters relating to transmission to the first AP include the first TID among the one or more TIDs. The method includes: The STA sends a second frame to the first AP, the second frame including: The data frame associated with the first TID; and Second BSR; and Based on the second BSR indicating a queue size with a zero value for the first TID, the STA receives a fourth frame from the first AP, the fourth frame indicating that the STA is roaming / switching from the first AP to the second AP.

5. The method according to any of the preceding claims, wherein, The parameter indicates whether the STA should send the amount of data buffered at the STA to the first AP before switching from the first AP to the second AP.

6. The method according to claim 5, wherein, The parameter instructs the STA not to send any data buffered at the STA to the first AP before switching from the first AP to the second AP.

7. The method according to claim 5, wherein, The parameter instructs the STA to send all of the data buffered at the STA to the first AP before switching from the first AP to the second AP.

8. The method according to any of the preceding claims, wherein, The parameter indicates the amount of data buffered at the STA to be sent to the first AP before switching from the first AP to the second AP.

9. The method according to claim 8, wherein, The quantity indicates the number of bits, bytes, or octets.

10. The method according to any one of claims 8 or 9, wherein, The quantity is equal to zero.

11. The method according to any one of claims 8 or 9, further comprising: The STA sends one or more third frames to the first AP, the third frames including first data for the first AP having a total size equal to the amount indicated by the parameter.

12. The method of claim 11, further comprising: The STA receives a fourth frame from the first AP, the fourth frame indicating that the STA is roaming / switching from the first AP to the second AP.

13. The method according to any of the preceding claims, wherein, The parameter indicates the first service identifier (TID) (or first access class (AC)) of the first data in the data buffered at the STA that is to be sent to the first AP before switching from the first AP to the second AP.

14. The method according to claim 13, wherein, The first frame indicates one or more TIDs (one or more ACs) associated with the data buffered at the STA.

15. The method according to claim 14, wherein, The first frame includes a buffer status report (BSR) indicating one or more TIDs.

16. The method according to any one of claims 14 or 15, wherein, The one or more TIDs (one or more ACs) include the first TID (or the first AC).

17. The method according to any one of claims 13-16, further comprising: The STA sends a third frame to the first AP, the third frame including: The data frame associated with the first TID; and Second BSR.

18. The method of claim 17, further comprising: Based on the second BSR indicating a queue size with a zero value for the first TID, the STA receives a fourth frame from the first AP, the fourth frame indicating that the STA is roaming / switching from the first AP to the second AP.

19. The method according to any of the preceding claims, wherein, The parameter indicates the first duration of the transmission of a portion of the data buffered at the STA to the first AP before the transition from the first AP to the second AP.

20. The method according to claim 19, wherein, The first duration includes the duration of the transmission opportunity (TXOP) initiated by the second frame.

21. The method according to any one of claims 19 or 20, wherein, The first frame indicates the second duration.

22. The method according to claim 21, wherein, The first duration is based on the second duration.

23. The method according to claim 22, wherein, The first duration is less than or equal to the second duration.

24. The method according to any one of claims 20-22, wherein, The second duration includes the duration of the transmission opportunity (TXOP) initiated by the first frame.

25. The method according to any one of claims 19-24, further comprising: The STA sends one or more third frames to the first AP, the third frames including services for the first AP during the first duration indicated by the parameter.

26. The method of claim 25, further comprising: After the first duration ends, the STA receives a fourth frame from the first AP, the fourth frame indicating that the STA is roaming / switching from the first AP to the second AP.

27. The method according to any of the preceding claims, wherein, The parameters are based on signal strength.

28. The method according to claim 27, wherein, The signal strength includes the received signal strength of frames transmitted by the first AP and received by the STA.

29. The method according to claim 27, wherein, The signal strength includes the received signal strength of frames transmitted by the second AP and received by the STA.

30. The method according to claim 27, wherein, The signal strength includes the received signal strength of frames transmitted by the STA and received by the first AP.

31. The method according to claim 27, wherein, The signal strength includes the received signal strength of frames transmitted by the STA and received by the second AP.

32. The method according to any of the preceding claims, wherein, The first frame includes a roaming request.

33. The method according to any of the preceding claims, wherein, The second frame includes the roaming response.

34. An apparatus arranged to operate in an access point (AP) and including a processor and a transceiver, wherein, The processor is arranged as follows: The transceiver slave station (STA) receives a first frame, which indicates a transition from the first AP to the second AP. as well as A second frame is sent to the STA via the transceiver. The second frame indicates parameters related to the transmission of data buffered at the STA to the first AP before switching from the first AP to the second AP.

35. The apparatus according to claim 34, in, The first frame includes a buffer status report (BSR), which indicates one or more service identifiers (TIDs) associated with services buffered at the STA for the first AP. The instruction to switch from the first AP to the second AP refers to a request to roam (switch) from the first AP to the second AP. and The parameters relating to transmission to the first AP include the first TID among the one or more TIDs. The processor is arranged as follows: The third frame is received from the STA via the transceiver, the third frame including: The data frame associated with the first TID; and Second BSR; and Based on the second BSR indicating a queue size with a zero value for the first TID, a fourth frame is sent to the STA via the transceiver, the fourth frame indicating that the STA is roaming / switching from the first AP to the second AP.

36. An apparatus arranged to operate in a station (STA) and including a processor and a transceiver, said apparatus being arranged as follows: The transceiver sends a first frame to a first access point (AP), the first frame indicating a transition from the first AP to a second AP; and A second frame is received from the first AP via the transceiver. The second frame indicates parameters related to the transmission of data buffered at the STA from the STA to the first AP before the data is switched from the first AP to the second AP.

37. The apparatus according to claim 36, in, The first frame includes a buffer status report (BSR), which indicates one or more service identifiers (TIDs) associated with services buffered at the STA for the first AP. The instruction to switch from the first AP to the second AP refers to a request to roam (switch) from the first AP to the second AP. and The parameters relating to transmission to the first AP include the first TID among the one or more TIDs. The processor is arranged as follows: The second frame is sent to the first AP via the transceiver, and the second frame includes: The data frame associated with the first TID; and Second BSR; and Based on the second BSR indicating a queue size with a zero value for the first TID, a fourth frame is received from the first AP via the transceiver, the fourth frame indicating that the STA is roaming / switching from the first AP to the second AP.

38. A computer program product that can be stored on a computer-readable medium and, when run on a computer, is configured to perform the method according to any one of claims 1-33.

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