Managing EDCA parameters with low latency and reliable traffic

Abstract

Management of EDCA parameters with low-latency reliable traffic. The network implements a low-latency reliable service approach to ensure that LLRS traffic is prioritized over non-LLRS traffic. LLRS-capable and non-LLRS-capable stations coexist and share the same wireless medium. Non-LLRS-capable stations complete ongoing legacy contention-free transmit TXOPs regardless of the station's need to transmit LLRS. LLRS transmissions thus wait a long time before starting. The AP detects LLRS activity in the network and modifies the EDCA TXOP limit parameters of a BSS to allow stations to reduce their TXOPs while LLRS activity remains. The AP can organize one BSS for LLRS-capable stations and another BSS for non-LLRS-capable stations. Refusal of association to or disassociation from such a BSS can include a code indicating to the rejected / disassociated station that a BSS more suited to its LLRS capabilities is available.

Description

[Technical field]

[0001] The present invention relates to the technical field of wireless communication networks, and more particularly to a method and device for transmitting data traffic of Low Latency and Reliable Service (LLRS) in an Extremely High Throughput (EHT) system. [Background technology]

[0002] Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.

[0003] The 802.11 family of standards, adopted by the Institute of Electrical and Electronics Engineers (IEEE®), provides numerous mechanisms for wireless communication between stations.

[0004] With the development of latency-sensitive applications such as online games, real-time video streaming, virtual reality, drone or robot remote control, the requirements and challenges of better low latency and robustness need to be taken into account, for example, 99.9% of latency-sensitive packets should be delivered to end devices within 2ms latency.

[0005] Such issues are currently being considered by the IEEE 802.11 working group as a primary objective in issuing the next major 802.11 release, known as 802.11be or EHT for "Extremely High Throughput."

[0006] Low-Latency Reliable Service (LLRS) has been defined as a target for such a primary objective: LLRS is a service provided to higher layer traffic streams that prioritizes MSDUs (Data Units) and delivers them within a given reliability / packet delivery ratio (PDR) and worst-case latency with low jitter.

[0007] For example, the 802.11be Project Request for Authorization (PAR) targets a worst-case latency of 5 ms for real-time gaming.

[0008] In terms of meeting QoS constraints, several low latency (LL) mechanisms have been considered to prioritize LLRS traffic within a Basic Service Set (BSS).

[0009] In terms of reducing the impact on the network, some LL techniques (passive techniques) can be applied by non-AP stations (passive stations) that do not participate in 10LLRS traffic. An example is given in the IEEE 802.11-20 / 1046r2 document, where a normal non-AP station must stop its transmission opportunity (TXOP) before a protected / limited TWT service period (for LLRS traffic) starts. In this way, the transmission of LLRS traffic can be performed without waiting for the end of an impending TXOP, thus ensuring low latency.

[0010] However, non-AP stations without LLRS capabilities, e.g., legacy non-AP stations conforming to the specifications of previous IEEE 802.11 standards including 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, and 802.11ax, may coexist with LLRS capable stations in the same BSS, or at least operate on the same wireless medium (e.g., 20 MHz channel). Such non-AP stations without LLRS capabilities cannot relinquish the wireless medium by stopping ongoing TXOPs. This significantly impacts the network latency performance, since non-AP stations capable of LLRS must wait for all ongoing TXOPs, sometimes longer than the required latency, before they can access the medium.

[0011] Therefore, efficient network management is required to improve the latency for reliable services in LL. Summary of the Invention

[0012] The main challenge proposed for improving latency is to ensure that non-AP stations capable of LLRS have frequent enough opportunities to access the wireless medium, given the latency requirements.

[0013] This objective may be achieved by adjusting the length of the TXOP when LLRS data traffic occurs on the wireless medium.

[0014] Thus, in this respect, the present invention provides a method of communication in a wireless network including an Access Point (AP) managing one or more Basic Service Sets (BSS), comprising: Configuring Enhanced Distributed Channel Access (EDCA) parameters for a first BSS (i.e., EDCA parameters to be applied by non-AP stations of the first BSS to access the wireless medium and transmit frames); modifying the EDCA parameters for the first BSS in response to actively detecting a low latency and reliable service (LLRS) in the one or more BSSs; The present invention provides a communication method including the steps of:

[0015] In this way, the AP can actively detect LLRS in one of the BSSs it manages and modify communication parameters of stations in one (or more) BSSs accordingly. Thus, by selecting appropriate modified communication parameters for the first BSS, the AP can force non-AP stations to limit TXOP on time, thus increasing access opportunities in the wireless medium for stations with LLRS capabilities.

[0016] Optional features of embodiments of the invention are defined in the appended claims. Some of these features are described herein below with reference to methods, but they can be transformed into apparatus features.

[0017] In some embodiments, the modified EDCA parameters include a modified TXOP restriction parameter that defines a maximum duration of a transmission opportunity (TXOP). In this way, the AP directly controls the maximum duration for which non-LLRS capable stations of the first BSS are allowed to reserve the wireless medium. Thus, the AP ensures that LLRS capable stations are allowed to newly access the medium with a minimum frequency corresponding to the aforementioned maximum duration. opportunity It can be guaranteed that

[0018] In a particular embodiment, the modified TXOP limit parameter is lower than the TXOP limit parameter of the EDCA parameters before modification, with the aim of reducing the maximum duration of access to the wireless medium by non-AP stations of a BSS.

[0019] For example, the (lower) TXOP limit parameter is Half the value of the worst-case latency budget for LLRS data traffic defined in the document "IEEE 802.11 Real Time Applications TIG Report" referenced IEEE 802.11-18 / 2009r6, e.g., the smallest non-zero value; - a TXOP limit value from Table 9-137 of the IEEE 802.11 Standard (RTM), Version 2016 or Table 8-105 of the IEEE 802.11 Standard (RTM), Version 2012 that is lower than the worst-case latency budget for LLRS data traffic defined in the document "IEEE 802.11 Real Time Applications TIG Report" referenced in IEEE 802.11-18 / 2009r6; -The ratio between the worst-case latency budget of LLRS data traffic defined in the document "IEEE 802.11 Real Time Applications TIG Report" referenced as IEEE 802.11-18 / 2009r6 and the number of non-AP stations that do not have LLRS capability (i.e., do not implement LLRS) in the first BSS (e.g., based on identity), - a value of 0, i.e. restricting the TXOP to the transmission of a single MAC Service Data Unit (MSDU) or management frame; A value equal to 1024 ms, which meets the requirements of the above-mentioned document "IEEE 802.11 Real Time Applications TIG Report" while limiting the impact on station throughput in the presence of LLRS activity; A value equal to or less than a Delay Bound value indicating the maximum amount of time to complete a successful transmission in a TSPEC information element managed by the AP and received from a non-AP station capable of LLRS; and a value equal to or lower than the ratio between a Delay Bound value indicating the maximum amount of time to complete a successful transmission in a TSPEC information element managed by the AP and received from a non-AP station capable of LLRS and an integer N incremented from 1 in case of a retransmission policy, It can be one of the following:

[0020] In some embodiments, the TXOP limit parameter has the same value for traffic data of different access categories, which facilitates management of TXOP duration when LLRS activity is active in the network.

[0021] In a variant, the lowered TXOP limit parameter has different values ​​for traffic data of different access categories, which makes it possible to maintain QoS for legacy (i.e. non-LLRS) communications.

[0022] In some embodiments, the method further includes restoring (changing back) the configured EDCA parameters for the first BSS in response to detecting the end of the LLRS activity in the one or more BSSs, which means that the AP resets the first BSS with the previously used EDCA parameters. Of course, the AP may use another new set of EDCA parameters, for example due to a change in the network. Thus, more generally, the AP sets new EDCA parameters with a higher TXOP limit parameter (compared to the changed one used when LLRS data traffic is present).

[0023] In some embodiments, detecting LLRS activity in the one or more BSSs includes detecting LLRS activity in the first BSS, which means that stations capable of performing LLRS and stations not capable of performing LLRS coexist in the same BSS, and thus EDCA parameter adaptation affects both types of non-AP stations.

[0024] In a variant, detecting LLRS activity in the one or more BSSs includes detecting LLRS activity in BSSs different from the first BSS managed by the AP. In that case, the AP advantageously lowers EDCA parameters (TXOP limit) for non-LLRS BSSs only. Since LLRS capable stations can suspend or stop ongoing TXOPs when LLRS transmissions are initiated, long TXOPs may persist in other BSSs specific to LLRS data traffic. In other words, EDCA parameters for other BSSs are left unchanged in response to detecting LLRS activity.

[0025] In some embodiments, detecting LLRS activity in the one or more BSSs comprises: - receiving LLRS capabilities for non-AP stations in the one or more BSSs, which means that an AP can consider there to be LLRS activity as soon as it knows that there is a station in the network (associated with that AP) capable of performing LLRS; - exchanging LLRS data traffic (i.e., uplink or downlink traffic) with non-AP stations in the one or more BSSs, preferably data traffic carrying a predefined Traffic Identifier or of a predefined Access Category (e.g., AC_VI or AC_VO), where the AP considers there to be LLRS activity while it is involved in an LLRS data traffic exchange; Receiving a message from a non-AP station signaling a request or need for LLRS data traffic, e.g., a TSPEC message having a particular latency below a predefined TXOP limit (e.g., a TXOP limit set in the EDCA parameters of the BSS); detecting one or more criteria from

[0026] Conversely, detecting the end of LLRS activity may correspond to disassociation of an LLRS-capable non-AP station from all APs, the end of LLRS data traffic exchange with the non-AP station, or the end of the station's need and demand in terms of LLRS.

[0027] In some embodiments, configuring the EDCA parameters for the first BSS includes broadcasting a beacon frame including the EDCA parameters. In a variation, configuring the EDCA parameters for the first BSS includes transmitting a probe response frame including the EDCA parameters to non-AP stations that have made a probe request.

[0028] In some embodiments, modifying the EDCA parameters for the first BSS includes broadcasting a beacon frame including the modified EDCA parameters, such that the AP broadcasts new EDCA values ​​to all of the non-AP stations in the first BSS for subsequent application of the modified parameters.

[0029] In some embodiments, the EDCA parameters for the first BSS include legacy EDCA parameters and multi-user EDCA parameters that temporarily replace the legacy EDCA parameters for non-AP stations of the first BSS when the non-AP stations are scheduled in a multi-user transmission by the AP. Thus, the present invention affects the length of a TXOP regardless of station state.

[0030] The above objectives may also be achieved by directing non-AP stations to an appropriate BSS, which may or may not be dedicated to LLRS traffic.

[0031] In this context, the method may further comprise transmitting, in the AP, to a non-AP station an association-related management frame for rejecting the association of the non-AP station with the first BSS or disassociating the non-AP station from the first BSS, the association-related management frame including a code indicating that another BSS managed by the AP is available, thanks to which the AP may redirect the non-AP station, for example to a BSS corresponding to its capabilities.

[0032] A better management of transmissions by stations may be achieved. Indeed, modified EDCA parameters (reduced TXOP limits) may be used to reduce the transmission time of stations that are not capable of LLRS (grouped in the same BSS). Furthermore, conventional EDCA parameters (and therefore TXOP limits) may be used to offer longer legacy contention-free TXOPs to stations capable of LLRS (grouped in the same BSS), as long as they are allowed to interrupt them (through the LL active approach) and make LLRS transmissions.

[0033] The specification of such codes may be implemented alone, without regard to modifying the EDCA parameters as described above. To that end, the present invention provides a method of communication in a wireless network, comprising: The present invention may also relate to a method, comprising: transmitting an association-related management frame to a non-AP station, the association-related management frame including a code indicating that another BSS managed by the AP is available, the association-related management frame rejecting association of the non-AP station with a first basic service set (BSS) managed by the AP or disassociating the non-AP station from the first BSS, the association-related management frame including a code indicating that another BSS managed by the AP is available.

[0034] Conversely, the communication method in a wireless network is as follows: This may include receiving an association-related management frame from an AP that rejects association of the non-AP station with a first basic service set (BSS) managed by the AP or disassociates the non-AP station from the first BSS, the association-related management frame including a code indicating that another BSS managed by the AP is available.

[0035] In some embodiments, the method further comprises, in the AP: receiving a capability from the non-AP station; determining whether a capability of the non-AP station matches a capability of the first BSS with respect to a low latency and reliable service (LLRS); may further include The transmitting of the association related management frame is in response to determining a mismatch. Thus, the code alerts the station that it is not compatible with the first BSS, but there is another BSS that is more compatible. Of course, the AP may grant association with the first BSS if there is a capability match between the station and the BSS.

[0036] For example, the non-AP stations may be capable of LLRS and the first BSS may be dedicated (i.e., restricted) to non-AP stations that are not capable of LLRS, i.e., to non-LLRS data traffic. Thus, in that case, the code indicates that the first BSS is dedicated to non-AP stations that are not capable of low latency and reliable service (LLRS), and that for stations that are capable of LLRS, another BSS managed by the AP that is dedicated to non-AP stations that are capable of LLRS is available.

[0037] Conversely, the non-AP stations may not be capable of performing LLRS and the first BSS may be dedicated to non-AP stations capable of performing LLRS. In the opposite case, the code indicates that the first BSS is dedicated to non-AP stations capable of performing low latency and reliable service (LLRS), and for non-AP stations that are not capable of LLRS, another legacy BSS managed by the AP is available that is dedicated to non-AP stations that are not capable of LLRS.

[0038] In some embodiments, the method further includes initiating the other BSS in response to receiving a low latency reliable service (LLRS) capability from the non-AP station at the AP. Preferably, the other BSS in this case is an LLRS-capable BSS (i.e., dedicated to LLRS data traffic). Thus, in response to there being a first LLRS-capable station, the AP decides to run a dedicated BSS to ensure proper management of EDCA parameters (as described above) for stations that are not LLRS-capable. The LLRS-capable stations can then be moved to this newly started BSS using the transmission of the code described above.

[0039] In another embodiment, the method further includes restricting the first BSS to non-AP stations capable of LLRS or restricting the first BSS to stations that are not capable of LLRS in response to detecting LLRS activity in the network at the AP. In this configuration, the AP may decide to run an unconstrained BSS and restrict LLRS to only stations capable of LLRS (or only stations that are not capable of LLRS). In this case, stations that are not capable of LLRS (or stations that are capable of LLRS) may be redirected to another BSS using the transmission of the code described above.

[0040] In some embodiments, the method further includes, after the receiving at the non-AP station, sending an association request to the AP for association with another BSS managed by the AP. Conversely, the method further includes, after the transmitting at the AP, receiving an association request from the non-AP station for association to another BSS managed by the AP. In this method, the AP successfully redirects the non-AP station to a more suitable BSS, meaning that the capabilities of the non-AP station match the capabilities of the other BSS with respect to LLRS.

[0041] To have knowledge of the availability of various BSSs, the method may further include receiving, at the non-AP station, one or more beacon frames from the AP advertising the first BSS and the other BSSs. The beacon frames may be multi-BSS beacon frames sent by the transmitting AP advertising multiple (e.g., all) BSSs instantiated by the AP. This allows the non-AP station to efficiently discover other suitable BSSs with a view to associating therewith.

[0042] Of course, an AP may manage various BSSs and perform the steps described above with respect to various non-AP stations within its BSSs, e.g., attempting to have stations capable of performing LLRS in a dedicated BSS and stations not capable of performing LLRS in other BSSs.

[0043] The above objective can also be achieved by controlling a Direct Link (DiL) or a Peer-to-Peer (P2P) using an adapted TXOP length.

[0044] In this respect, the present invention also provides a method of communication in a wireless network, comprising: in a non-access point (non-AP) station associated with a first Basic Service Set (BSS) managed by an access point (AP), Enhanced Distributed Channel Access (EDCA) parameters for the first BSS, the EDCA parameters being a ratio of a number of transmission opportunities (TXOPs) within the first BSS. maximum receiving said EDCA parameters, including a TXOP limiting parameter defining a period during which the station belongs to a BSS and is therefore aware of the transmission parameters to be respected when communicating within said BSS; negotiating a duration of a TXOP with another non-AP station for a direct link (DiL) transmission based on the TXOP limit parameter; performing a DiL transmission with the other non-AP station; The present invention proposes a communication method including the steps of:

[0045] In that method, although the DiL transmission does not occur in the first BSS but on the same wireless medium as the first BSS, the (P2P) non-AP station forces other P2P stations to limit their TXOP duration to the current request offered by the AP. Thus, the latency affected by the P2P transmission is still controlled by the AP. In fact, the latter may adapt the EDCA parameters (including the TXOP limit) as described above depending on whether LLRS activity is sensed or detected.

[0046] In some embodiments, the other (P2P) non-AP stations are non-AP stations that are not associated with the AP in the first BSS. Thus, the present invention controls any DiL transmission involving a non-AP station associated with an AP.

[0047] In some embodiments, negotiating the TXOP duration includes receiving a TXOP duration from the other non-AP station and responding with a reduced TXOP subject to the TXOP limit parameter. In this manner, a non-AP station associated with an AP exercises control over other P2P (non-associated) stations.

[0048] Relatedly, the present invention also provides a wireless communication device including at least one microprocessor configured to perform the steps of any of the methods described above.

[0049] Another aspect of the invention relates to a non-transitory computer readable medium storing a program which, when executed by a microprocessor or computer system in a wireless device, causes the wireless device to perform any of the methods described above.

[0050] At least a portion of the methods according to the invention may be computer-implemented. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, which may be generally referred to herein as a "circuit," "module," or "system." Furthermore, the present invention may take the form of a computer program product embodied in any tangible medium of expression having computer usable program code embodied in the medium.

[0051] Since the present invention may be implemented in software, the present invention may be embodied as a computer readable medium for provision to a programmable device on any suitable carrier medium. Tangible carrier media may include storage media, such as hard disk drives, magnetic tape devices, or solid-state memory devices. Transient carrier media may include signals, such as electrical, electronic, optical, audio, magnetic, or electromagnetic signals, e.g., microwave or RF signals. [Brief description of the drawings]

[0052] Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings in which: [Figure 1] FIG. 1 illustrates a network environment in which an embodiment of the present invention may be implemented. [Diagram 2] FIG. 2 is a diagram illustrating EDCA parameter set information elements exchanged in an 802.11 network to provide EDCA parameters for a BSS. [Diagram 3] FIG. 3 illustrates an example sequence of management frames that allow a not-yet-associated station to discover and register with the AP that manages the BSS. [Figure 4] FIG. 4 illustrates several LL techniques implemented in a BSS in an example scenario in which LLRS traffic is transmitted. [Diagram 5]5 and 6 are diagrams illustrating various signaling implementations for declaring LLRS capabilities. [Figure 6] 5 and 6 are diagrams illustrating various signaling implementations for declaring LLRS capabilities. [Figure 7] FIG. 7 is a timeline diagram illustrating the impact of non-LLRS data traffic experienced by legacy stations on the latency for LLRS data traffic. [Figure 8] FIG. 8 illustrates, using a timeline, the impact of an embodiment of the present invention, particularly on latency for LLRS data traffic. [Figure 9] FIG. 9 illustrates another network environment in which embodiments of the present invention may be implemented. [Figure 10] FIG. 10 illustrates, by means of a flow chart, the high-level steps in an AP for an embodiment of the invention where EDCA parameters are adapted / modified depending on LLRS activity in the network. [Figure 11a] 11a and 11b are flow charts illustrating the high-level operation of BSS management by an AP during the association phase for a non-AP station wanting to join a normal BSS and a low-latency BSS, respectively, in accordance with an embodiment of the present invention. [Figure 11b] 11a and 11b are flow charts illustrating the high-level operation of BSS management by an AP during the association phase for a non-AP station wanting to join a normal BSS and a low-latency BSS, respectively, in accordance with an embodiment of the present invention. [Figure 12a] 12a and 12b are flow chart diagrams illustrating the high level operation of BSS management by an AP during disassociation of a non-AP station from a normal BSS and a low latency BSS, respectively, according to an embodiment of the present invention. [Figure 12b]12a and 12b are flow chart diagrams illustrating the high level operation of BSS management by an AP during disassociation of a non-AP station from a normal BSS and a low latency BSS, respectively, according to an embodiment of the present invention. [Figure 13a] FIG. 13a shows a schematic representation of a communication device according to an embodiment of the present invention. [Figure 13b] FIG. 13b shows a schematic representation of a wireless communication device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] The invention will now be described by way of non-limiting exemplary embodiments and with reference to the drawings.

[0054] The techniques described herein may be used in various broadband wireless communication systems, including communication systems based on orthogonal multiplexing techniques. Such communication systems include, for example, spatial division multiple access (SDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier frequency division multiple access (SC-FDMA) systems. SDMA systems may utilize sufficiently different directions to transmit data belonging to multiple user terminals, i.e., wireless devices or stations, in parallel. TDMA systems may allow multiple user terminals to share the same frequency channel by dividing a transmission signal into different time slots or resource units and assigning each time slot to a different user terminal. OFDMA systems utilize Orthogonal Frequency Division Multiplexing (OFDM), which is a modulation technique that divides the overall system bandwidth into multiple orthogonal subcarriers or resource units. These subcarriers may also be referred to as tones, bins, etc. With OFDM, each subcarrier may be independently modulated with data. An SC-FDMA system may utilize Interleaved FDMA (IFDMA) for transmission on subcarriers distributed across the system bandwidth, Localized FDMA (LFDMA) for transmission on blocks of adjacent subcarriers, and Enhanced FDMA (EFDMA) for transmission on multiple blocks of adjacent subcarriers.

[0055] The teachings herein may be included in (e.g., implemented in or performed by) a variety of apparatuses (e.g., stations). In some aspects, a wireless device or station implemented in accordance with the teachings herein may include an access point (so-called AP) or other (so-called non-AP station or STA).

[0056] An AP may include, be implemented as, or be known as a Node B, Radio Network Controller ("RNC"), evolved Node B (eNB), 5G next-generation base station (gNB), base station controller ("BSC"), base transceiver station ("BTS"), base station ("BS"), transceiver function ("TF"), wireless router, wireless transceiver, basic service set ("BSS"), enhanced service set ("ESS"), radio base station ("RBS"), or some other terminology.

[0057] A non-AP station may include, be implemented as, or be known as a subscriber station, a mobile station (MS), a remote station, a remote terminal, a user terminal (UT), a user agent, a user device, a user equipment (UE), a user station, or some other terminology. In some implementations, a STA may include a cellular phone, a cordless phone, a Session Initiation Protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device with wireless connectivity capabilities, or some other suitable processing device that is connected to a wireless medium. Thus, one or more aspects taught herein may be incorporated within a phone (e.g., a cellular phone or a smartphone), a computer (laptop), a tablet, a portable communication device, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device, or a satellite radio), a global positioning system (GPS) device, or other suitable device configured to communicate over a wireless or wired medium. In some aspects, a non-AP station may be a wireless node. Such wireless nodes may, for example, provide connectivity for or to a network (eg, a wide area network such as the Internet or a cellular network) via wireless or wired communication links.

[0058] An AP manages a collection of stations that together organize access to the wireless medium for communication. The stations (including the AP) form a service set, which is referred to hereinafter as a Basic Service Set (BSS) (although other terms may be used). The same physical station acting as an access point may manage two or more BSSs (and thus corresponding WLANs), each BSS identified by a specific Basic Service Set Identification (BSSID) and managed by a separate virtual AP implemented in the physical AP.

[0059] Low Latency Reliable Service (LLRS) is a service provided to higher layer traffic streams that prioritizes delivery of MSDUs (data units of this traffic stream) within a given reliability / packet delivery ratio (PDR) and worst-case latency budget with low jitter. Traffic that may be associated with LLRS may include latency-sensitive data, i.e., data from applications such as gaming, media streaming, ultra-realistic, virtual reality, etc.

[0060] The 802.11be Project Request for Authorization (PAR) gives examples of worst-case latency, e.g., 5 ms for real-time gaming.

[0061] A communication network should employ appropriate techniques, hereinafter referred to as LLRS or low latency or LL techniques, to ensure that LLRS traffic is prioritized over non-LLRS traffic in the network. Some LL techniques may be active techniques in that they should be applied by stations exchanging LLRS traffic in the network. Some LL techniques may be passive techniques in that they should be applied by passive non-AP stations, i.e., stations in a BSS that do not participate in LLRS traffic exchange. Passive techniques reduce the use of the wireless network for exchanging non-LLRS traffic, thus prioritizing LLRS traffic. Such prioritization favors the achievement of PDR and low jitter targets.

[0062] The AP of a BSS may declare the LLRS requirements for non-AP stations to join the BSS, such as the LL scheme that non-AP stations will have to apply. Dedicated information elements may be used, for example in management frames with dedicated bits to declare the active and / or passive LL schemes to be applied.

[0063] A non-AP station that wishes to join the BSS may, where appropriate, declare its LLRS capabilities, i.e., its ability to perform LL techniques (either general or AP-declared or part of them). The declaration may be made during the association procedure with the BSS in such a way that the AP may decide whether to grant or reject the requested association based on the declared capabilities. In the following, such a non-AP station is referred to as a station capable of performing LLRS.

[0064] Conversely, stations that do not have LLRS capabilities are referred to as non-LLRS-enabled stations, including legacy non-AP stations that comply with any of the previous IEEE 802.11 standards, including 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, or 802.11ax.

[0065] LLRS-capable non-AP stations and non-LLRS-capable non-AP stations coexist and share the same wireless medium. While LLRS-capable stations can stop ongoing legacy contention-free transmissions to be able to use the wireless medium for LLRS transmissions, this is not true for non-LLRS-capable stations. This can result in LLRS transmissions waiting a long time before starting due to ongoing legacy contention-free transmissions by non-LLRS-capable stations.

[0066] The present invention, particularly with respect to LLRS, seeks to obtain better control over ongoing legacy contention-free transmissions by stations not capable of such LLRS in order to improve transmission latency.

[0067] FIG. 1 illustrates an example network environment 10 for delivering LLRS traffic, according to one or more example embodiments.

[0068] Each communication station 101-107 registers with a central station or AP 110 during an association procedure in which an Access Point (AP) assigns a unique Association Identifier (AID) to the requesting non-AP station. For example, the AID (e.g., a 16-bit value that uniquely identifies the non-AP station) is used to identify the station in exchanged frames. The AP 110 and associated non-AP stations 101-107 may represent a Basic Service Set (BSS) or an Extended Service Set (ESS).

[0069] An exemplary association procedure is shown in FIG. 3 and described below.

[0070] Once associated with a BSS, the communication stations 101-107, 110 exchange data frames over a wireless transmission channel 100 of a wireless local area network (WLAN) under the control of an AP 110. The wireless transmission channel 100 is defined by an operating frequency band composed of a single channel or of multiple channels forming a composite channel.

[0071] Non-AP stations may also communicate directly, i.e., without the intermediation of an AP as a relay station for their messages, via a direct wireless link (DiL for Direct Link). An exemplary situation for direct communication includes the existence of peer-to-peer (P2P) transmissions between non-AP stations having the same primary channel. Non-AP stations 101 and 107 exchange data frames via a direct link, with one of the two P2P stations acting as the AP station for this P2P exchange.

[0072] A physical access point 110 may be configured to manage two or more WLANs or BSSs, i.e., two or more groups of stations (see, for example, the embodiment of FIG. 9). Each BSS is uniquely identified by a specific Service Set Identifier (BSSID) and is managed by each virtual AP implemented in the physical AP. Within the context of a set of BSSIDs, if a virtual AP emits a beacon frame, it is called the "transmitting" BSSID or BSS (only one per set). Other BSSIDs of that AP that belong to the set of BSSIDs are "non-transmitting" BSSIDs or BSSs. Beacon frames sent by a transmitting BSSID include a base profile, and each profile element is mandatory for non-transmitting BSSIDs and includes EDCA and / or MU-EDCA parameters as described below.

[0073] The stations 101-107, 110 compete with each other using EDCA (Enhanced Distributed Channel Access) contention to gain access to the wireless medium 100 and are granted a so-called legacy contention-free transmission opportunity (TXOP- or "contention-free burst period"), during which they then transmit (single user (SU)) data frames on the wireless medium.

[0074] Stations may also use multi-user (MU) procedures that allow a single station (typically the AP 110) to schedule MU transmissions, i.e., multiple simultaneous transmissions to or from other stations, during a TXOP granted to that single station using EDCA contention in the wireless network. One implementation of such a MU procedure is adopted in the IEEE 802.11ax amendment standard, e.g., as a multi-user uplink and downlink OFDMA (MU UL and DL OFDMA) procedure.

[0075] Access to the shared wireless medium for transmitting data frames is primarily based on CSMA / CA techniques to sense the carrier and avoid collisions by separating simultaneous transmissions in space and time. Carrier sensing in CSMA / CA is performed by both physical and virtual mechanisms. Physical carrier sensing resides in the PHY layer of any station and uses power detection and preamble detection together with a frame length delay to determine when the medium is busy. Virtual carrier sensing resides in the MAC layer and uses reservation information carried in the Duration field of the MAC header to announce the blocking of the medium. The virtual carrier sensing mechanism is called the Network Allocation Vector (NAV). The medium is determined to be idle if both the physical and virtual carrier sensing mechanisms indicate that the medium is idle.

[0076] To gain access to the medium (EDCA connection), any station, including the AP, begins counting down a backoff counter (designed to expire after a number of time slots) when the medium is sensed idle after at least a predefined period (e.g., SIFS, PIFS, DIFS, or AIFS period, depending on the type of frame). The backoff counter is chosen randomly within a so-called contention window [0, CW], where CW is the number of frames in the CW window. min and C.W. max (power of 2 minus 1). This backoff mechanism or procedure, also called the Distributed Coordination Function (DCF) contention-based channel access procedure, is based on a collision avoidance mechanism that delays transmission times by a random interval to reduce the probability of collisions on the shared channel. After the backoff time has expired (i.e., the backoff counter has reached 0), the station may transmit data or control frames if the medium is still idle. These frames reserve the wireless medium 100 for the TXOP duration indicated in the Duration field of the MAC header (more precisely in the HE-SIG-A field for HE frames).

[0077] Once a station has gained access to the medium, it maintains control of the medium by maintaining a minimum gap between frames in a sequence (short inter-frame space (SIFS)). Successive frames may indicate the remaining duration of the current TXOP in the Duration field. Other stations will not gain access to the medium during the sequence, since they will have to postpone for a fixed period longer than SIFS. In this way, a station included in a TXOP can be sure that no frames will be transmitted by other stations until the end of the TXOP.

[0078] To prevent any one station from monopolizing the medium, rules limit the types of frame exchange sequences that are allowed and the duration of those sequences.

[0079] The parameters and these rules governing EDCA contention are known as EDCA parameters and are defined per BSS by the AP. They are transmitted to non-AP stations of that BSS via beacon frames transmitted by the AP or via so-called probe response frames transmitted by the AP when a non-AP station attempts to associate with that BSS (Figure XX below).

[0080] The EDCA parameters are provided through the EDCA Parameter Set information element (IE) 210, shown in Figures 9-261 and 9-262 of the IEEE 802.11 Standard (RTM), Version 2016, and reproduced in Figure 2. The EDCA parameters include the minimum contention window (CW min (or ECW min ), the maximum contention window CW max (or ECW max ), the AIFSN value (which defines the AIFS period mentioned above), and the TXOP limit which defines the maximum allowed duration for a granted TXOP.

[0081] As shown, these parameters may be provided for each of the categories (through fields 211), AC_BE, AC_BK (212), AC_VI (213), AC_VO (214) as defined in the standard 802.11e-2005. This means that the acquired TXOP is the boundary of the period during which the station may transmit data of a particular traffic class (AC). Once the TXOP is acquired, the station may continue to transmit data, control, and management frames and receive response frames, provided that the frames do not exceed the TXOP limit (field 215) set for that AC. Note that a TXOP limit of zero means that only one MSDU or management frame can be transmitted before contending for access again.

[0082] The AP can update the ACP parameters at any time by using the QoS Info field 216. The QoS Info field 216 includes an EDCA Parameter Set Update Count subfield that is initially set to 0 and incremented whenever any of the AC parameters change. This subfield is used by a non-AP station that receives a new EDCA Parameter Set information element (IE) 210 to determine whether the set of EDCA parameters has changed and therefore update its local values ​​to use them for the next data transmission.

[0083] The following table provides default values ​​for EDCA parameters for various 802.11 standards as defined in Table 9-137 of the IEEE 802.11 Standard (RTM), Version 2016 and Table 8-105 of the IEEE 802.11 Standard (RTM), Version 2012. TIFF0007618017000001.tif102161

[0084] The 802.11ax standard introduced an additional set of EDCA parameters, namely, the MU EDCA parameters, to restore fairness between non-AP stations that participate in MU transmissions with the AP and non-participating stations. The MU EDCA parameters temporarily substitute the legacy EDCA parameters for that non-AP station in a BSS when scheduled by the AP in a multi-user transmission.

[0085] The MU EDCA parameters are also transmitted by the AP to non-AP stations in the BSS via beacon frames and / or probe response frames. The format of the MU EDCA Parameter Set information element is described in Figures 9-788o and 9-788p of the 802.11ax D6.1 standard. It is very similar to the format in Figure 2, except that the MU EDCA Timer field is replaced by the TXOP Restriction field 615. This means that when using the MU EDCA parameters, the TXOP restrictions provided in the legacy EDCA parameters should be applied.

[0086] 3 shows an example sequence of management frames that allows a not-yet-associated non-AP station to discover and register with the AP managing the BSS. It includes three phases: WLAN discovery, authentication, and association, at the end of which the non-AP station moves to an authenticated and associated state with the AP if the AP grants the association. Note that the station may be currently associated with another AP (in another BSS) and willing to join this BSS.

[0087] Before associating with an AP, a non-AP station collects information about the AP by scanning channels one by one through either passive scanning (passive discovery procedure) or active scanning (active ticketing procedure).

[0088] In passive scanning mode, a station scans each 20 MHz channel consecutively and waits to listen for beacon frames (which declare the SSID-service set identifier of the BSS) on the scanned channels, regardless of whether the station has already previously connected to a particular BSS.

[0089] A beacon frame is a management frame that advertises details of the BSS. It is transmitted periodically by an AP over the wireless medium, for example every 100 ms.

[0090] In active scan mode, the station sends out a probe request frame 310 on each wireless 20 MHz channel. The probe request frame may contain the SSID of the particular BSS or WLAN that the station is looking for, or the probe request frame may not contain a specific SSID, meaning that the station is looking for "any" BSS in the station's vicinity.

[0091] In response to receiving the probe request frame, the AP checks whether the stations have at least one common supported data rate. If there is a compatible data rate, the AP responds with a probe response frame 320, the contents of which are similar to a beacon frame and advertise the AP's other 802.11 capabilities, including the SSID (wireless network name), supported data rates, encryption type if required, and a set of (MU-)EDCA parameters that should be used for further data transmissions using EDCA.

[0092] The acknowledgement frame 330 may be transmitted by a station in response to receiving the probe response frame 320 .

[0093] According to an embodiment of the present invention, an AP may use beacon frames 380 and probe response frames 320 to advertise and update the values ​​of a set of EDCA parameters to be used by non-AP stations joining the BSS.

[0094] Upon receiving a beacon frame or a probe response frame, a non-AP station may determine whether to initiate an association procedure with a given BSS.

[0095] The second phase is 802.11 authentication after the station has selected a BSS to join. The well-known conventional authentication phase is performed and will not be described in detail. The station sends a low-level 802.11 authentication request frame 340 to the selected AP. The AP receives the authentication request frame 340 and responds with an authentication response frame 350 to the station.

[0096] Next, the station must perform an actual association with the AP from the low-level authentication steps. This is the next phase of the actual 802.11 authentication, whereby the station actually joins the BSS if the AP agrees to it. This stage finalizes the security and bit rate options and establishes the data link between the station and the AP. The purpose of this last exchange is for the station to obtain an Association Identifier (AID) that should be used to access the medium and transmit data within the BSS it is joining.

[0097] For that purpose, the station transmits an association request frame 360 ​​to the selected AP. The association request frame includes the selected encryption type, if necessary, and other compatible 802.11 capabilities. The association request frame 360 ​​is a management frame.

[0098] If the elements in the association request frame match the capabilities of the AP, the AP generates an Association ID (AID) for the station and responds with an Association Response frame 370 with a success message granting network access to the station. If there is no match, an association rejection can be issued.

[0099] More generally, the AP may grant or deny association of a non-AP station with the BSS based on the received capability declaration. For that purpose (grant or deny), a result code is provided in the association response frame 370. Example codes are listed in section 6.3.7.5.2 of the IEEE 802.11 standard (RTM), version 2016, such as SUCCESS, REFUSED_REASON_UNSPECIFIED, REFUSED_CAPABILITIES_MISMATCH, REFUSED_EXTERNAL_REASON, REFUSED_AP_OUT_OF_MEMORY, REFUSED_BASIC_RATES_MISMATCH, REJECTED_EMERGENCY_SERVICES_NOT_SUPPORTED, REFUSED_TEMPORARILY.

[0100] Once the station has successfully associated with the AP, data transfer begins in the selected BSS using the physical medium 100 .

[0101] Also, after being associated, non-AP stations and APs can unilaterally disassociate by sending a disassociation frame 390. A reason code is also provided in the disassociation frame 390. A number of example codes are listed in section 9.4.1.2 of the IEEE 802.11 Standard (RTM), version 2016. Disassociation cannot be rejected by either side.

[0102] The probe response frame 320, the authentication request frame 340 and authentication response frame 350, the association request frame 360 ​​and association response frame 370, and the disassociation request frame 390 are unicast management frames emitted in an 802.11 legacy format known as the single-user (SU) format, which is the format used for point-to-point communication (here between an AP and a station). Each of these unicast management frames is acknowledged by an ACK frame 330.

[0103] Returning to Figure 1, non-AP stations may represent a variety of devices, such as gaming clients, augmented / virtual reality headsets, smartphones, wireless displays, etc., some of which must exchange (i.e., transmit and / or receive) low latency or LLRS data traffic over time. LLRS data traffic has more constrained QoS requirements, e.g., with respect to PDR, jitter and latency, than non-LLRS traffic that coexists in WLAN 10.

[0104] As an example, the document "IEEE802.11 Real Time Applications TIG Report", referenced as IEEE802.11-18 / 2009r6, gives the following latency requirements for LLRS (real time): Real-time gaming: Less than 5ms latency Cloud Gaming: Sub-10ms Latency Real-time video: Less than 3 to 10 ms latency Robotics and industrial automation, plant control and human safety: latency below 1 to 10 ms Haptic technology: Latency shorter than 1 to 5 ms.

[0105] Some non-AP stations 102, 103, 105 are capable of LLRS and can participate to prioritize LLRS traffic over non-LLRS traffic, and can implement LL or LLRS techniques within their BSS, an active LL technique for stations that exchange LLRS traffic (called active stations) and a passive LL technique for non-AP stations that do not participate in LLRS traffic exchange at a given time (called passive stations). Non-AP stations 102, 103, 105 can be active and passive stations in the same BSS sequentially. Non-AP stations 102, 103, 105 are capable of LLRS.

[0106] The non-AP stations 103, 106, 107 do not implement LLRS functionality. The non-AP stations 103, 106, 107 are not LLRS capable. The non-AP stations 103, 106, 107 may be legacy stations conforming to a previous version of the IEEE 802.11 standard (802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, or 802.11ax) that does not include LLRS, or may be stations that do not support LLRS (e.g., if LLRS is considered optional in the next 802.11 release).

[0107] FIG. 4 illustrates several LL techniques performed in a BSS in an example scenario in which LLRS traffic is transmitted.

[0108] In this scenario, the AP schedules a reserved service period 410. The AP may announce the start and end times of that period. The reserved service period 410 may be entirely dedicated to LLRS traffic exchange, or in a variant, both LLRS and non-LLRS traffic may be allowed. In this figure, this is the reserved LLRS period.

[0109] The AP participates in the LLRS traffic exchange (transmitting 421 to non-AP stations 105 and subsequently receiving from non-AP stations 102) during the reserved service period. However, this is not required. The reserved LLRS period may alternatively be used by non-AP stations to directly exchange P2P LLRS traffic.

[0110] In one embodiment, the reserved service period is a protected TWT service period, as presented in the IEEE 802.11-20 / 1046r2 document.

[0111] Prior to the reserved service period, the non-AP station 104 gains access to the wireless medium 100 for a TXOP period and begins transmitting non-LLRS traffic 420.

[0112] Because the station 104 is aware of the scheduled reserved service period 410, it stops transmitting its non-LLRS traffic when its TXOP has not ended but LLRS traffic should be exchanged among other stations in the BSS. Such stopping behavior is a passive LL approach because it reduces the use of the wireless medium by the station 104 for the exchange of non-LLRS traffic in the network. Such a mechanism (or procedure) gives priority to LLRS traffic.

[0113] The AP 110 can then transmit LLRS traffic to the non-AP stations 105 and receive other LLRS traffic from the non-AP stations 102. The stations can apply an active LL technique to perform the LLRS traffic exchange, e.g., using specific network resources dedicated to LLRS traffic.

[0114] The current TXOP termination mentioned above is just one example of a possible LL approach.

[0115] More generally, an LLRS capable station may stop or interrupt its own current data transmission while a TXOP is not yet completed, to the benefit of LLRS data traffic transmissions from other LLRS capable stations.

[0116] The example of FIG. 4 shows that if station 104 does not apply the passive approach when the time comes, LLRS exchange within the reserved service period cannot occur (or at least interference will occur), causing degradation of QoS for LLRS traffic.

[0117] A non-AP station may declare its LLRS capability (or inability) during association as described above with reference to Figure 3. Note that a non-AP station may already declare some 802.11 capabilities in the association request frame 360, for example, using the Extended Capabilities information element (IE) defined in clause 9.4.2.27 of P802.11-REVmd / D5.0.

[0118] According to an embodiment of the present invention, a non-AP station that wants to join a BSS declares its LLRS capability to apply one or more LL techniques. A non-AP station may declare that it is capable of performing passive LLRS and / or active LLRS, or may only declare that it is capable of performing LLRS. Of course, a station that is not capable of performing LLRS provides a declaration accordingly. An example of signaling of LLRS capability in a management frame transmitted by a non-AP station is provided below with reference to Figures 5 and 6.

[0119] In a variant for providing LLRS capability in the association request frame 360, the non-AP station may decide to use the probe request frame 310. The latter is also a management frame. Thus, a similar signaling of LLRS capability may be used. In that scenario, upon receiving the probe request frame, the AP may analyze the LLRS capability of the non-AP station and decide whether to continue the association procedure with the non-AP station as described below.

[0120] In Fig. 5, a single bit 500 is added to the existing IE as a supplementary station capability. In the case of the known Extended Capabilities IE, the available bits are from the 87th bit onwards. Thus, for example, bit 87 is selected to signal whether the LL approach can be applied (LLRS executable - value set to 1) or not (value set to 0). At this stage, no distinction is made between active and passive LLRS capabilities. This may mean that the station has both passive and active LLRS capabilities. In a variant, it may mean that the station has at least one of the two capabilities.

[0121] In Figure 6, two bits 600 are added to the existing IE as supplemental station capabilities. For the existing Extended Capabilities IE, the available bits are from bit 87 onwards. Bits 88 and 89 are selected for the following, respectively: - to signal whether a non-AP station can apply a passive LL approach when LLRS traffic is to be exchanged between other stations of the BSS, reducing the use of the wireless medium by the non-AP station for exchanging non-LLRS traffic in the network (bit 88 is set to 1) or not (bit 88 is set to 0). In that way, the station declares whether it is capable of performing passive LLRS, and - To signal whether a non-AP station is capable of performing an active LLRS scheme when it has to exchange LLRS traffic with other stations in the BSS, using resources dedicated for LLRS traffic to exchange LLRS in the network (bit 89 set to 1) or not (bit 90 set to 0). In that way, the station declares whether it is capable of performing active LLRS.

[0122] Although FIG. 6 shows both bits, an embodiment may be contemplated to use only one of the two bits, for example to declare a non-AP station as a station capable of passive (or active) LLRS or as a station not capable of LLRS.

[0123] Such signaling by non-AP stations (FIGS. 5 and 6) allows the AP to know which non-AP stations are capable of LLRS and which are not, and therefore which non-AP stations to assume to transmit LLRS data traffic. As described below, if the LLRS capabilities declared by the non-AP stations do not match the LLRS requirements of the BSS (e.g., declared in the beacon 380 or probe response frame 320), the AP may reject the association.

[0124] FIG. 7 illustrates, with a timeline, the impact of non-LLRS traffic received by legacy stations (ie, stations not capable of running LLRS) on the latency for LLRS data traffic.

[0125] FIG. 7a illustrates a long duration TXOP 714 performed by a legacy station 106 that has acquired a TXOP 714 having a long duration, e.g., equal to the TXOP limit provided by the AP (FIG. 2), to transmit non-LLRS data traffic 710 over the wireless medium 100.

[0126] During this contention-free period TXOP 714, the LLRS capable station 105 may be ready to transmit LLRS data traffic 711. Unfortunately, the legacy station 106 cannot stop the TXOP 714 and return the wireless medium 100 to the LLRS capable station 105 because it does not have the LLRS methodology capability (the legacy station 106 is not LLRS capable).

[0127] LLRS data transmission is postponed until the end of the legacy contention-free period transmission opportunity: the LLRS-capable station 105 must wait until the end of the TXOP 714 to obtain a new contention-free period 713 using EDCA and transmit its LLRS data traffic, referenced 712. Thus, a large delay occurs before the LLRS-capable station 105 can transmit its LLRS data traffic 711.

[0128] The delay may exceed the worst-case latency budget required for LLRS data traffic, which is drastic to the quality of real-time applications. For example, if the worst-case latency budget for LLRS data traffic is 2 ms and the duration of the TXOP714 is 3 ms (according to Table 1) considering 802.11ac video data traffic (non-LLRS data traffic), the LLRS data traffic will be transmitted with a very late delay.

[0129] More generally, this example shows that if passive stations are not amenable to applying passive LL techniques to reduce their impact on the network and available bandwidth, LLRS data traffic will not be given priority and therefore low latency, PDR and jitter requirements will not be met.

[0130] Similar considerations may be made for active stations: an active non-AP station may decide, for example, not to enable / use an active LL technique, e.g., to not penalize its own non-LLRS data traffic (such as web browsing, email, etc.), however, this may penalize the efficiency of LLRS in the network as a whole.

[0131] Also, stations specified in previous 802.11 standards (that is, non-EHT, non-AP stations) obviously cannot apply the LL techniques, which can dramatically degrade the efficiency of LLRS, as shown in this example.

[0132] To overcome the above-mentioned drawbacks, an embodiment of the present invention provides for modifying the EDCA parameters of a BSS, in particular the TXOP limit, when LLRS activity (including interruptions) is detected in the network 10. Such modification allows reducing the TXOP limit, i.e. the duration of the TXOP obtained by legacy non-AP stations, so that LLRS-capable stations can obtain more frequent opportunities to access the medium (given the lower TXOP duration) against the will of non-LLRS-capable stations.

[0133] To that end, the AP may first configure (e.g., using a beacon frame) Enhanced Distributed Channel Access (EDCA) parameters for the first BSS, i.e., EDCA parameters to be applied by non-AP stations of the first BSS to access the wireless medium and transmit frames. The AP may then modify the EDCA parameters for the first BSS in response to detecting low latency and reliable service (LLRS) activity in one or more BSSs that it manages. The modified EDCA parameters are then reliably transmitted to the interested non-AP stations, e.g., through a beacon frame.

[0134] With the modified EDCA parameters, particularly with the reduced TXOP limit, legacy station 106 will no longer be able to reserve a TXOP as large as TXOP 714.

[0135] 8 illustrates, via a timeline, the technical effect of an embodiment of the present invention, particularly with respect to latency for LLRS data traffic, showing station behavior in a BSS after an AP broadcasts modified EDCA parameters, particularly reduced TXOP limits, in response to recognizing LLRS activity in the network.

[0136] A legacy station 106 may reserve a TXOP 814 in EDCA to transmit non-LLRS data traffic, within the constraints of the TXOP limit. Because the TXOP limit may be significantly reduced, the TXOP 814 is shorter than the TXOP 714, and the wireless medium is released sooner. Thus, an LLRS-capable station 105 may access the wireless medium 100 in EDCA substantially earlier (with lower delay) than in FIG. 7, and may then transmit its LLRS data traffic 812 during the acquired TXOP 813. A legacy station 106 that still has some non-LLRS data 820 may again access the medium in EDCA to transmit data during the acquired TXOP 824 while still complying with the TXOP limit.

[0137] It can be seen that stations capable of LLRS can transmit LLRS data traffic with short delays and thus tend to meet the worst-case latency requirements. Stations not capable of LLRS are no worse: they start at a similar timing as data transmission via TXOP 714, but are performed at two (or more) timings, split into two (or more) parts 810 and 820 between TXOP 814 and TXOP 824.

[0138] Since EDCA parameter adaptation affects the throughput of legacy stations by limiting their burst duration (TXOP duration), the adaptation is preferably temporary, e.g., only while LLRS activity is ongoing. Thus, upon detecting the end of LLRS activity in one or more BSSs, the AP may restore (re-modify) the configured EDCA parameters for the first BSS.

[0139] 1, stations 103, 106, 107 that are not LLRS capable may coexist in the same BSS with non-AP stations 102, 103, 105 that are LLRS capable, where LLRS activity is detected in the first BSS.

[0140] However, in this configuration, stations capable of running LLRS can also provide a passive LL approach for them to stop running TXOPs and give special treatment to LLRS data traffic, but are affected by the modified EDCA parameters, specifically the reduced TXOP limit.

[0141] Therefore, another embodiment is considered in which two or more APs sharing the same wireless medium 100 are managed, one of which (the first BSS) is reserved for stations that are not capable of LLRS, and another one (the second BSS) is reserved for stations that are capable of LLRS. In that way, it is only possible to change EDCA parameters for stations that are not capable of LLRS (i.e., the first BSS). In the second BSS, stations that are capable of LLRS are also allowed to reserve TXOPs for a longer period even for transmitting non-LLRS data traffic without affecting the latency of the LLRS data. This is because, as mentioned above, an ongoing TXOP can be stopped at any time to free up the wireless medium for the transmission of LLRS data traffic.

[0142] In this configuration, LLRS activity may be detected in a (second) BSS other than the first BSS managed by the AP, and EDCA parameters for the (second) BSS may be left unchanged in response to detecting the LLRS activity.

[0143] An illustration of this configuration is given in FIG. 9, where the AP 110 creates a first BSS 901, named LEGACY_BSS, to manage the legacy stations 103, 106, 107 (stations that are not capable of running LLRS), and the AP 110 creates a second BSS 902, named LL_BSS, to manage the stations 102, 104, 105 that are capable of running LLRS.

[0144] Multiple BSSs can be used by creating independent BSSs or by using the multi-BSS standard feature (802.11be). LEGACY_BSS 901 and LL_BSS 902 receive two different EDCA Parameter Set elements from the AP 110 that can be updated independently. As mentioned above, the EDCA Parameter Set element (FIG. 2) can be associated with the MU EDCA Parameter Set element.

[0145] To provide backward compatibility with legacy non-AP stations, the LEGACY_BSS 901 is the transmitting BSS while the LL_BSS is the non-transmitting BSS.

[0146] When using the standard feature of multi-BSS, a single beacon frame may be used by the AP 110 to transmit information related to the two BSSs (including EDCA parameters). When the LEGACY_BSS is the transmitting BSS, its information (EDCA parameters) is provided first. This allows the legacy stations to obtain the necessary communication parameters. After the LEGACY_BSS information, the LL_BSS information is transmitted on the same beacon frame.

[0147] When EDCA parameters (e.g., TXOP limits) for the first BSS (LEGACY_BSS 901) are changed in response to detection of LLRS activity, a new beacon frame 380 may be transmitted in which the LEGACY_BSS information is updated while the LL_BSS information may remain unchanged.

[0148] Figure 10 illustrates, by means of a flow chart, the high-level steps in an AP for an embodiment of the invention where EDCA parameters are adapted / modified depending on the LLRS activity in the network. The algorithm applies to both single BSS and multi-BSS (LEGACY_BSS and LLBSS) embodiments.

[0149] In the following, the first BSS refers to a single BSS or the LEGACY_BSS in the case of a multi-BSS.

[0150] In step 1000, the AP 110 configures EDCA parameters (including MU EDCA parameters) for the first BSS, for example, in response to creating the first BSS or when updating its own EDCA parameters.

[0151] The configuration is done in a conventional manner: it may involve broadcasting a beacon frame containing the EDCA parameters, or sending a probe response frame containing the EDCA parameters to each non-AP station that has made a probe request. The EDCA parameters are carried in the (MU-)EDCA Parameter Set IE (e.g., 210 in FIG. 2). The values ​​of the EDCA parameters may be those shown in Table 1 above.

[0152] This state (LEGACY STATE) of the first BSS corresponds to the AP 110 detecting no LLRS activity over the wireless network or in the BSSs it manages.

[0153] Thus, the non-AP stations of the first BSS access the wireless medium, for example as described above with reference to Figure 7. This configuration makes it possible to achieve high throughput data transmission.

[0154] In step 1010, the AP 110 becomes aware of LLRS activity in the network, particularly related to the wireless medium 100. For example, the AP 110 may detect LLRS in one or more BSSs that it manages: this may be LLRS activity in a first BSS or LLRS activity in other BSSs (e.g., the LL_BSS mentioned above).

[0155] Such detection may include having the AP 110 participate in an LLRS scheme such as that described in FIG. 4 or detect any LLRS schemes in the network.

[0156] It may also include the AP receiving LLRS capabilities for non-AP stations in its own BSSs (including the first BSS) that share the wireless medium 100. In that case, as soon as there are non-AP stations capable of performing LLRS, the state of the first BSS may be changed to (LL STATE) as described below. Conversely, as soon as there are no non-AP stations capable of performing LLRS in the first BSS or in the AP's BSS, the state of the first BSS may be set back to its previous state (LEGACY STATE).

[0157] Alternatively, the AP may include exchanging LLRS data traffic (uplink or downlink traffic) with non-AP stations in its own BSS (including the first BSS). The data traffic may carry a predefined Traffic Identifier to identify the data traffic as LLRS traffic or of a predefined access category (e.g., AC_VI or AC_VO). Thus, as soon as the AP 110 is involved in the LLRS data exchange, the state of the first BSS is changed. Conversely, when the LLRS data exchange with the AP is terminated, the state of the first BSS may be set back to its previous state.

[0158] Another option may include the AP receiving a message from a non-AP station signaling a request or need for LLRS data traffic. This may be, for example, a TSPEC message indicating low latency, i.e., a specific latency less than a predefined TXOP limit (e.g., a TXOP limit set in the EDCA parameters of the BSS). In this situation, as soon as the AP recognizes the station's needs in terms of LLRS data traffic, the state of the first BSS may be changed. Conversely, as soon as the station's needs are met and no LLRS needs are identified any more, the AP may switch the first BSS back to its previous state.

[0159] For example, the Delay Bound field in the TSPEC specifies the maximum amount of time, in microseconds, to complete a successful transmission, including retransmissions, if any. LLRS activity can be declared if Delay Bound < TXOP Limit without retransmissions, or if Delay Bound < (N+1)*TXOP Limit with retransmissions, where N is an integer, e.g., N=1 for exactly one retransmission.

[0160] When LLRS activity is detected in the network (e.g., the first BSS or the LL_BSS), the AP 110 may update the EDCA parameters for the first BSS, in particular the TXOP maximum The transmission opportunity (TXOP) limit parameter, which defines the duration and is reduced (compared to the TXOP limit parameter of the EDCA parameters before the change), is changed, step 1020.

[0161] This involves forming a new EDCA Parameter Set IE with the TXOP changed (in field 215 for each AC) to a predefined TXOP_LL limit value, for example as shown in the table below: The same TXOP_LL limit value may be used throughout the ACs, or different TXOP_LL limit values ​​may be used for each AC.

[0162] As mentioned above, the TXOP_LL value helps reduce the impact of non-LLRS data traffic transmitted by legacy non-AP stations or stations not capable of LLRS. TIFF0007618017000002.tif100161

[0163] Preferably, the TXOP_LL value is set lower (depending on the data type) than the worst-case latency budget required for LLRS data traffic, as mentioned in the document "IEEE 802.11 Real Time Applications TIG Report" referenced IEEE 802.11-18 / 2009r6.

[0164] For example, the TXOP_LL value is Half of such worst-case latency budget value, e.g., the lowest non-zero value, A TXOP limit value from Table 9-137 of the IEEE 802.11 Standard (RTM), version 2016, or from Table 8-105 of the IEEE 802.11 Standard (RTM), version 2012, that is lower than the worst-case latency budget for LLRS data traffic as defined in the document "IEEE 802.11 Real Time Applications TIG Report" referenced IEEE 802.11-18 / 2009r6. For example, a TXOP limit value of 1.504 ms may be used when the worst-case latency budget is 2 ms. - A ratio of a worst-case latency budget for LLRS data traffic defined in the document "IEEE 802.11 Real Time Applications TIG Report" referenced as IEEE 802.11-18 / 2009r6 to a number based on the number of non-AP stations in the first BSS that do not have LLRS capability (i.e., do not implement LLRS). This can be, for example, a ratio of the worst-case latency budget to the number of stations that are not capable of running LLRS; - a value of 0, i.e. restricting the TXOP to the transmission of a single MAC Service Data Unit (MSDU) or management frame; A value equal to -1.024 ms, which reduces to a minimum the duration of any TXOP performed by a station that is not capable of performing any LLRS. A value equal to or less than the Delay Bound value indicating the maximum amount of time to complete a successful transmission in a TSPEC information element managed by the AP and received from a non-AP station capable of LLRS; A Delay Bound value indicating the maximum amount of time to complete a successful transmission in a TSPEC information element managed by the AP and received from a non-AP station capable of performing LLRS, and a value less than or equal to the ratio of an integer N incremented from 1 in the case of a retransmission policy; can be set to

[0165] This reduces the duration of any TXOP performed by any station that is not LLRS capable to a minimum in preference to low latency data traffic transmitted by any LLRS capable non-AP station.

[0166] The modified EDCA parameters for the first BSS are broadcast in the first BSS using a beacon frame. Thus, each non-AP station in the first BSS sets its local TXOP limit value to the modified TXOP_LL(i) value. Thus, the first BSS enters a state (LL STATE) while LLRS activity occurs on the shared wireless medium. In this way, the non-AP stations in the first BSS access the wireless medium using a shorter TXOP, for example as described above with reference to FIG. 8.

[0167] This configuration makes it possible to achieve low latency transmission for LLRS data traffic even when LLRS-enabled and non-LLRS-enabled stations are associated within the same AP.

[0168] Next, in step 1030, the AP 110 determines whether LLRS activity has stopped. Exemplary circumstances for such a determination are provided above. In response to detecting the end of LLRS activity in one or more BSSs, the AP 110 loops back to step 100 and restores (i.e., changes back) previous EDCA parameters for the first BSS. Thus, the first BSS returns to LEGACY STATE if non-AP stations are able to obtain longer TXOPs.

[0169] 1 and 9, Direct Link communication (here between an associated non-AP station 107 and an unassociated station 101) may also take place over the wireless medium 110. The P2P stations (here 101 and 107) directly negotiate communication parameters, including their own TXOP duration, without considering (MU-)EDCA parameters that they may know.

[0170] This negotiation can be done using the QoS control field in the MAC header of the exchanged frames, as described in the IEEE 802.11-2007 standard: In particular, a "QoS Data(+)CF-Poll" frame can be used to request a TXOP duration ("TXOP duration requested" in the QoS control field), and a "QoS Data(+)CF-Ack" frame can be used to respond with a TXOP limit ("TXOP limit" in the QoS control field).

[0171] Additionally, to minimize the chance of collisions and as a more robust collision detection mechanism, the initiating P2P station may begin the sequence with an exchange of short control frames, using robustly modulated RTS and CTS frames that allow for contention-free burst periods during transmission opportunities (TXOPs). This sets the NAV in the surrounding stations of both the P2P initiator and the P2P responder, some of which may be hidden nodes that cannot detect the transmissions of more distant stations and therefore can only prolong frame transmissions from nearby nodes.

[0172] The RTS and CTS frames also contain a duration field that can be used to learn the remaining duration of the current TXOP.

[0173] P2P processing does not follow the rules of the BSS and therefore the EDCA parameters of the first BSS. Therefore, DiL or P2P communication has the same impact as shown in Figure 7, long TXOPs that dramatically degrade the latency of LLRS data traffic.

[0174] To improve this situation, a P2P station that also belongs to the first BSS (here, station 107 with knowledge of the EDCA parameters) may negotiate the duration of the P2P TXOP with the other P2P station (here, station 101) based on the TXOP limit parameter and based on the currently applicable TXOP limit in the EDCA parameters. For example, the duration of the P2P TXOP is made shorter than the TXOP limit parameter. Thus, if the first BSS is in LEGACY STATE, the P2P TXOP may have a larger duration. On the other hand, if the first BSS is in LL STATE (because LLRS activity has been detected), the P2P TXOP is made shorter in duration to comply with the latency requirements of LLRS.

[0175] If both P2P stations belong to respective BSSs, they may negotiate the P2P TXOP duration with the minimum TXOP limit value.

[0176] In practice, the P2P station 107 may receive a TXOP duration from the P2P station 101 and, subject to the TXOP limiting parameters, may respond with a reduced TXOP duration (e.g., if the received TXOP duration is higher than the TXOP limiting parameters applicable for the first BSS and the considered AC).

[0177] Turning now to the multi-BSS case, the AP 110 may manage in parallel a LEGACY_BSS 901 and a LL_BSS 902. As mentioned above, grouping stations that are not capable of LLRS in one BSS (LEGACY_BSS) and stations that are capable of LLRS in another BSS (LL_BSS) is advantageous in that it allows the AP 110 to affect the TXOP duration only for stations that are not capable of LLRS (by setting appropriate EDCA parameters for only the LEGACY_BSS).

[0178] It is proposed that the AP transmits to a given non-AP station an association-related management frame that denies the non-AP station's association with a target BSS managed by the AP or disassociates the non-AP station from the target BSS, the association-related management frame including a code indicating another BSS managed by the AP.

[0179] Thus, such code may alert a station that is not LLRS capable that the target BSS is not suitable for it (LL_BSS), but that another suitable BSS is available in the same AP (LEGACY_BSS). Alternatively, such code may alert a station that is LLRS capable that the target BSS is not suitable for it (LEGACY_BSS), but that another more suitable BSS is available in the same AP (LL_BSS).

[0180] Such signaling can occur during the association phase (ie, in an association response frame 870) or throughout the disassociation procedure (ie, in a disassociation request or response frame 390 from the AP).

[0181] FIG. 11a illustrates, by means of a flow chart, the high-level operations for such management at the AP during the association phase for a non-AP station wishing to join the LEGACY_BSS.

[0182] Step 1100 determines when an association request frame 360 ​​is received from a non-AP station for the LEGACY_BSS 901. Note that this BSS is reserved for stations that are not LLRS capable.

[0183] Thus, in step 1110, the AP determines whether the requesting non-AP station is capable of performing LLRS, for example, using the capability declarations shown in Figure 5. In that method, the AP determines whether the capabilities of the non-AP station match the capabilities of the considered BSS for low latency and reliable service (LLRS).

[0184] If the requesting station is not LLRS capable, the association may be granted and a response (eg, an association response frame 370 with the conventional result code SUCCESS) is sent to the station in step 1120 .

[0185] If the requesting station is capable of performing LLRS, the BSS is not suitable compared to the LL_BSS that the AP has formed or can form.

[0186] Thus, in step 1130, the AP determines whether a low latency BSS (LL_BSS) has already been started. If not, in step 1140, the AP creates the LL_BSS 902 by using a second beacon frame or by using the multi-BSS function.

[0187] If so, or after step 1140, the AP rejects the association and signals to the requesting LLRS capable station that the LL_BSS is available.

[0188] This is done by sending 1150 an association response frame 370 with a new proposed result code, e.g., REFUSED_LL_BSS_AVAILABLE, which thus complements the result codes listed in clause 6.3.7.5.2 of the IEEE 802.11 Standard (RTM), version 2016.

[0189] A requesting LLRS capable station receiving such a result code may search for another BSS of the same AP. Such information may be obtained from a beacon frame transmitted by the AP. In response to identifying another BSS (ideally an LL_BSS), the requesting station may transmit an association request frame to the AP to associate with this other BSS. The process of FIG. 11b may then be performed by the AP receiving the association request frame to accept (or not accept) the association. Thanks to the result code redirecting the requesting station, it is expected that the capabilities of the redirected non-AP station will eventually match the LLRS capabilities of the redirected other BSS.

[0190] FIG. 11b illustrates, by means of a flow chart, the high-level operations for BSS management by the AP during the association phase for a non-AP station wanting to join the LL_BSS.

[0191] Step 1160 determines when an association request frame 360 ​​is received from a non-AP station for the LL_BSS 902. Note that this BSS is reserved for stations capable of performing LLRS.

[0192] Thus, in step 1170, the AP determines whether the requesting non-AP station is capable of performing LLRS, for example using the capability declarations shown in FIG.

[0193] If the requesting station is LLRS capable, the association can be granted and a response (e.g., an association response frame 370 with the conventional result code SUCCESS) is sent to the station in step 1180. This is the case for a non-AP station capable of LLRS as described above that received result code REFUSED_LL_BSS_AVAILABLE when attempting to join the LEGACY_BSS and is directed to the LL_BSS for association.

[0194] If the requesting station is not LLRS capable, then its BSS is not suitable compared to the LEGACY_BSS that the AP has already formed.

[0195] Thus, in step 1190, the AP denies the association and signals the requesting LLRS-non-capable station that the LEGACY_BSS is available.

[0196] This is done by sending an association response frame 370 with a newly proposed result code, e.g., REFUSED_LL_BSS_RESERVED, which thus complements the result codes listed in section 6.3.7.5.2 of the IEEE 802.11 Standard (RTM), version 2016.

[0197] A requesting non-LLRS capable station receiving such a result code may search for another BSS of the same AP. Such information may be obtained from a beacon frame transmitted by the AP. In response to identifying another BSS (ideally a LEGACY_BSS), the requesting station may send an association request frame to the AP to associate with this other BSS. The process of Fig. 11a is then performed by the AP receiving the association request frame in order to accept (or not accept) the association. Thanks to the result code redirecting the requesting station, it is expected that the capabilities of the redirected non-AP station will match the LLRS capabilities of the redirected other BSS.

[0198] Thanks to the new result codes REFUSED_LL_BSS_AVAILABLE and REFUSED_LL_BSS_RESERVED indicating the reason for the association refusal, an AP that determines a mismatch between the LLRS capabilities of the association requesting non-AP station and the target BSS may redirect the requesting non-AP station to another BSS that it has formed. Upon receiving such a code, the requesting non-AP station may discover, for example through the multi-BSS feature, another BSS managed by the same AP and request association with this other BSS.

[0199] FIG. 12a illustrates, using a flowchart, the high-level operations for BSS management by the AP during the disassociation phase of a LLRS-enabled non-AP station belonging to LEGACY_BSS 901.

[0200] Disassociation occurs when a LLRS capability mismatch occurs between one (or more) non-AP stations associated with the first BSS and the first BSS. Thus, the AP must determine whether the capabilities of an already associated non-AP station are inconsistent with the capabilities of the first BSS with respect to low latency and reliable service (LLRS).

[0201] This situation may arise for a number of reasons, for example, a non-AP station that is already associated with the first BSS (i.e., during the existence of the first BSS) may change its LLRS capability declaration.

[0202] It may also occur when detecting LLRS activity (its onset or a substantial amount of it) in the network and thus deciding (based on some criteria) to form both a LEGACY_BSS and an LL_BSS. In other words, the AP may restrict the first BSS to stations that are not capable of LLRS in response to detecting LLRS activity in the network. Thus, the first BSS becomes the LEGACY_BSS and stations capable of LLRS should move to the LL_BSS.

[0203] Thus, step 1200 consists in checking whether such a situation occurs and triggering a disassociation process for non-AP stations that are not compatible with the possible LEGACY_BSS (ie, capable of LLRS).

[0204] In step 1210, the AP determines whether a low latency BSS (LL_BSS 902) has already been started. If not, in step 1220, the AP creates the LL_BSS 902 by using a second beacon frame or by using the multi-BSS function.

[0205] If yes or after step 1220, the AP disassociates that (or some) non-AP station(s) that have LLRS capabilities that do not match the LEGACY_BSS, while signaling to the station under disassociation that the LL_BSS is available.

[0206] This is done by sending a disassociation request frame 390 (step 1230) with a new proposed reason code (e.g., LL_BSS_AVAILABLE), which thus supplements the reason codes listed in section 9.4.1.2 of the IEEE 802.11 Standard (RTM), version 2016.

[0207] An LLRS capable station under disassociation and receiving such a reason code may search for another BSS of the same AP. Such information may be obtained from a beacon frame transmitted by the AP. In response to identifying another BSS (ideally an LL_BSS), the requesting station may transmit an association request frame to the AP to associate with the other BSS. The above process of FIG. 11b may then be performed by the AP to authorize the disassociated LLRS capable station to associate with the LL_BSS (step 1240).

[0208] Figure 12b illustrates, with a flow chart, the high-level operation of BSS management by the AP during the disassociation phase of non-LLRS-enabled stations belonging to LL_BSS 902. This is very similar to Figure 12b where the BSSs have swapped roles.

[0209] Disassociation occurs when a mismatch in LLRS capabilities occurs between one (or more) non-AP stations associated with the first BSS and the first BSS. Thus, the AP needs to determine whether the capabilities of an already associated non-AP station are inconsistent with the capabilities of the first BSS with respect to low latency and reliable service (LLRS).

[0210] Such a situation may arise for several reasons, for example, a non-AP station that is already associated with the first BSS (i.e., while the first BSS is present) may change its LLRS capability declaration.

[0211] It may also occur when the AP detects LLRS activity (either its initiation or its substantial amount) in the network and decides (based on some criteria) to form both a LEGACY_BSS and an LL_BSS. In other words, the AP may restrict the first BSS to non-AP stations capable of LLRS in response to detecting LLRS activity in the network. In this way, the first BSS becomes the LL_BSS and stations that are not capable of LLRS should move to the LEGACY_BSS.

[0212] Thus, step 1250 consists in checking whether such a situation occurs and triggers a disassociation process for non-AP stations that are not compatible with the possible LL_BSS (ie, are not LLRS capable).

[0213] In step 1260, the AP determines whether a legacy BSS (LEGACY_BSS 901) is already started. If not, in step 1270, the AP creates a LEGACY_BSS 902 by using a second beacon frame or by using the multi-BSS feature. Preferably, the LEGACY_BSS 902 is always created as a transmitting BSS as soon as the AP is switched on. In fact, the LEGACY_BSS may be started permanently or "on demand" if LLRS is active in the network.

[0214] If yes or after step 1270, the AP disassociates that (or some) non-AP station whose LL_BSS and LLRS capabilities do not match, while signaling to the station under disassociation that the LEGACY_BSS is available.

[0215] This is done by sending a disassociation request frame 390 (step 1280) with a newly proposed reason code, e.g., LL_BSS_RESERVED, which thus complements the reason codes listed in clause 9.4.1.2 of the IEEE 802.11 Standard (RTM), version 2016.

[0216] A non-LLRS capable station that is in the process of disassociating and receives such a reason code may search for other BSSs of the same AP. Such information may be obtained from a beacon frame transmitted by the AP. In response to identifying another BSS, ideally a LEGACY_BSS, the responding station may transmit an association request frame to the AP and associate with the other BSS. The above process of FIG. 11a may then be performed by the AP with a view to authorizing (step 1290) the disassociated non-LLRS capable station to associate with the LEGACY_BSS.

[0217] Thanks to the new reason codes LL_BSS_AVAILABLE and LL_BSS_RESERVED, an AP that determines a mismatch in LLRS capabilities between an associated non-AP station and a BSS may redirect it to another, more suitable BSS that it has created. A mismatched non-AP station receiving such a code may discover other BSSs managed by the same AP, for example through the multi-BSS feature, and request association with this more suitable BSS.

[0218] The above embodiments show that an AP may dynamically manage its one or more BSSs to improve latency for LLRS data traffic.

[0219] 13 shows a schematic diagram of a communication device 1300, which may be either a non-AP station 101-107 or an access point 110 of a wireless network 100, and which is configured to carry out at least one embodiment of the present invention. The communication device 1300 may preferably be a device such as a microcomputer, a workstation, or a lightweight portable device. The communication device 1300 preferably has a communication bus 1313 connected to: A central processing unit 1301, such as a processor, denoted as CPU; A memory 1303 for storing executable code of the method according to an embodiment of the invention or steps of said method, and registers adapted to record variables and parameters necessary for executing said method; and At least one communication interface 1302 coupled via a transmit / receive antenna 1304 to a wireless communication network, for example a communication network according to any of the IEEE 802.11 family of standards.

[0220] Preferably, a communications bus provides communication and interoperability between various elements included in or connected to communications device 1300. The representation of a bus is not limiting, in particular a central processing unit is operable to transfer instructions to any element of communications device 1300 directly or with other elements of communications device 1300.

[0221] The executable code may be stored in a memory, which may be either read-only, a hard disk, or on a removable digital medium, such as a disk. According to an optional variant, the executable code of the program may be received by means of a communications network, via the interface 1302, so as to be stored in the memory of the communications device 1300 before being executed.

[0222] In an embodiment, the device is a programmable apparatus that uses software to implement embodiments of the invention, however, alternatively, embodiments of the invention may be implemented in whole or in part in hardware (e.g., in an application specific integrated circuit (ASIC)).

[0223] 13b is a block diagram that illustrates a schematic architecture of a communication device 1300, either an AP 110 or one of the stations 101-107, adapted to at least partially carry out the present invention. As shown, the device 1300 includes a physical (PHY) layer block 1323, a MAC layer block 1322, and an application layer block 1321.

[0224] The PHY layer block 1323 (here the PHY layer of the 802.11 standard) has the task of formatting, modulating on or demodulating from a 20 MHz channel or a composite channel, and transmitting or receiving frames, such as 802.11 frames, over the wireless medium 100 used to reserve TXOPs and exchange (LLRS or non-LLRS) data.

[0225] The MAC layer block or controller 1322 preferably includes an 802.11 MAC layer 1324 for performing conventional 802.11ax MAC operations, and additional blocks 1325 for at least partially performing the present invention. The MAC layer block 1322 may optionally be implemented in software executed by the CPU 1301.

[0226] Preferably, an additional block 1325 called LLRS management module performs part of an embodiment of the present invention.

[0227] The AP manages the EDCA parameters of its own BSS depending on whether LLRS activity is detected, and also manages the association and disassociation procedures to provide the above-mentioned result or reason codes to redirect some non-AP stations to other more suitable BSSs.

[0228] A non-AP station processes such result or reason codes to declare the station's LLRS capability and to discover and associate with other BSSs.

[0229] The 802.11 MAC layer 1324 and the LLRS management module 1325 interact to perform LLRS management of a BSS and / or a DiL TXOP in accordance with an embodiment of the present invention.

[0230] At the top of the diagram, an application layer block 1321 runs applications that generate and receive data packets, such as video streams, etc. The application layer block 1321 represents all of the stack layers above the MAC layer according to the ISO standard.

[0231] Although the present invention has been described above with reference to particular embodiments, it is not limited to those embodiments, and modifications which are within the scope of the invention will be apparent to those skilled in the art.

[0232] Numerous further modifications and variations will themselves suggest themselves to those skilled in the art by reference to the above-described exemplary embodiments, which are given by way of example only and are not intended to limit the scope of the invention, which is determined solely by the appended claims. In particular, different features from different embodiments can be interchanged, where appropriate.

[0233] In the claims, the term "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

Claims

1. A communication device that performs wireless communication in accordance with the IEEE 802.11 standard, a scheduling means for scheduling protected or restricted TWT service periods for low latency data traffic; a transmitting means for transmitting an association-related management frame to a non-AP station, the association-related management frame rejecting association with a first basic service set (BSS) managed by the communication device or disassociating the non-AP station from the first BSS, based on whether the non-AP station has an ability to recognize the protected or restricted TWT service period and to stop traffic of data other than the low latency data before the start of the protected or restricted TWT service period; the association related management frame includes a code indicating that another BSS managed by the communication device is available; A communication device characterized in that a limit value of a transmission opportunity (TXOP) period in a BSS in which a non-AP station having the capability participates, among the first BSS and the other BSS, is longer than a limit value of a TXOP period in a BSS in which a non-AP station having the capability does not participate.

2. The communication device includes: receiving information from the non-AP station indicating whether it has the capability; configured to determine whether the capabilities of the non-AP station match capabilities associated with the first BSS; The communication device of claim 1 , wherein the association-related management frame is transmitted in response to a determination of a mismatch.

3. The communication device described in claim 2, wherein the non-AP station to which the association-related management frame is transmitted is a non-AP station having the capability, and the first BSS is a BSS associated with a non-AP station not having the capability.

4. The communications device of claim 2, wherein the non-AP station to which the association-related management frame is transmitted is a non-AP station that is not capable of performing low latency reliable service (LLRS), the capability is the capability to perform LLRS, and the first BSS is a BSS dedicated to non-AP stations capable of performing LLRS.

5. The communication device of claim 1 , further comprising: activating the other BSS in response to receiving information indicating the capability from the non-AP station in the communication device.

6. 2. The communication device of claim 1, further comprising: restricting association with the first BSS to non-AP stations having the capability, or restricting association with the first BSS to stations not having the capability, in response to detecting activity in the communication device of scheduling the TWT service period that is protected or restricted for low latency data traffic.

7. 2. The communication device of claim 1, further comprising, after transmitting the association-related management frame at the communication device, receiving an association request to the other BSS from the non-AP station to which the association-related management frame was transmitted for association to the other BSS.

8. The communications device of claim 7, wherein the capabilities of the non-AP station to which the association-related management frame was transmitted match the capabilities of the other BSS with respect to low latency reliable service (LLRS).

9. A wireless communication method conforming to the IEEE 802.11 standard, comprising: - a scheduling step of scheduling protected or restricted TWT service periods for low latency data traffic; and transmitting an association-related management frame to a non-AP station, the association-related management frame rejecting association with a first basic service set (BSS) managed by a communication device or disassociating the non-AP station from the first BSS, based on whether the non-AP station has an ability to recognize the protected or restricted TWT service period and to stop traffic of data other than the low-latency data before the start of the protected or restricted TWT service period; the association related management frame includes a code indicating that another BSS managed by the communication device is available; A wireless communication method, characterized in that a limit value of a transmission opportunity (TXOP) period in a BSS in which a non-AP station having the capability participates, among the first BSS and the other BSS, is longer than a limit value of a TXOP period in a BSS in which a non-AP station having the capability does not participate.

10. A program for causing a computer to execute wireless communication conforming to the IEEE 802.11 standard, The wireless communication includes: - a scheduling step of scheduling protected or restricted TWT service periods for low latency data traffic; and transmitting an association-related management frame to a non-AP station, the association-related management frame rejecting association with a first basic service set (BSS) managed by a communication device or disassociating the non-AP station from the first BSS, based on whether the non-AP station has an ability to recognize the protected or restricted TWT service period and to stop traffic of data other than the low-latency data before the start of the protected or restricted TWT service period; the association related management frame includes a code indicating that another BSS managed by the communication device is available; A program characterized in that a limit value of a transmission opportunity (TXOP) period in a BSS in which a non-AP station having the capability participates, among the first BSS and the other BSS, is longer than a limit value of a TXOP period in a BSS in which a non-AP station having the capability does not participate.

11. An access point providing a first network for wireless communication conforming to the IEEE 802.11 standard, the first network being identified by a first BSSID, and a second network for wireless communication conforming to the IEEE 802.11 standard, the second network being identified by a second BSSID, a transmission control means for controlling transmission of an association-related management frame to a second type station, the second type station being different from a first type station capable of recognizing information on a protected or limited service period announced by the access point to its surroundings, to the second type station, the association-related management frame being for rejecting association of the second type station to the first network or for canceling association of the second type station to the first network; the association-related management frame includes information indicating that the second network is available; and An access point, comprising: an access point having a transmission opportunity (TXOP) period limit value in the first network that is longer than a transmission opportunity period limit value in the second network.

12. 12. The access point according to claim 11, further comprising a determination means for determining whether a station that has requested association is the first type station or the second type station based on information indicating communication capabilities contained in an association request frame received from the station.

13. 12. The access point according to claim 11, characterized in that the second type station is a station that does not support the IEEE 802.11be standard and supports any one of the following IEEE 802.11 standards: IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac, or IEEE 802.11ax.

14. An access point that provides a first network for wireless communication conforming to the IEEE 802.11 standard, identified by a first BSSID, and a second network for wireless communication conforming to the IEEE 802.11 standard, identified by a second BSSID, to a station, a transmission control means for controlling transmission of an association-related management frame to a first type station capable of recognizing information on a protected or limited service period announced by the access point to its surroundings, the association-related management frame being for rejecting association of the first type station to the second network or for canceling association of the first type station to the second network, the association-related management frame includes information indicating that the first network is available; and An access point, comprising: an access point having a transmission opportunity (TXOP) period limit value in the first network that is longer than a transmission opportunity period limit value in the second network.

15. 15. The access point according to claim 14, further comprising a determination means for determining whether the station that has requested association is the first type station or a second type station different from the first type station, based on information indicating communication capabilities contained in an association request frame received from the station.

16. 16. The access point according to claim 15, characterized in that the second type station is a station that does not support the IEEE 802.11be standard and supports any one of the following IEEE 802.11 standards: IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac, or IEEE 802.11ax.

17. An access point providing a first network for wireless communication conforming to the IEEE 802.11 standard, the first network being identified by a first BSSID, and a second network for wireless communication conforming to the IEEE 802.11 standard, the second network being identified by a second BSSID, a transmission control means for controlling transmission of an association-related management frame to the legacy type station, the association-related management frame being for rejecting association of the legacy type station to the first network or for canceling association of the legacy type station in the first network, the association-related management frame transmitted to the legacy-type station includes information indicating that the second network is available; and An access point, comprising: an access point having a transmission opportunity (TXOP) period limit value in the first network that is longer than a transmission opportunity period limit value in the second network.

18. The access point according to claim 17, characterized in that the legacy type station is a station that does not support the IEEE 802.11be standard and supports any one of the IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac, and IEEE 802.11ax IEEE 802.11 standards.

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