Controlling access to radio network

Abstract

A method of controlling access to a radio network (1), the method comprising transmitting, by an access node (AP), a frame (2) of at least one terminal device (STA, STA1, STA2), where the frame (2) causes the terminal device to suspend contention-based access to the radio network (1) by resetting a timer running in the terminal device (STA, STA1, STA2) prior to expiration of the timer, where upon expiration of the timer, the frame (2) causes the terminal device to suspend contention-based access to the radio network (1). A terminal device resumes contention-based access to a radio network.

Description

Technical Field

[0001] The present disclosure relates to the field of wireless communications, and more particularly to the field of wireless communications in industrial systems. The present disclosure also relates to wireless communications with deterministic and / or real-time capabilities. Background Art

[0002] In recent years, wireless communication has been widely adopted in the field of industrial systems. Compared with traditional wired control and monitoring systems, the wireless control and / or monitoring system described herein is cost-effective and / or easy to deploy.

[0003] In such radio networks, different types of data traffic may have diverse real-time requirements. For example, alert traffic (emergency traffic) generated by safety and / or emergency systems should be transmitted with the highest priority and / or hard real-time guarantees.

[0004] However, there may be delays that cause latency when transmitting data. For example, in CSMA / CA-based medium access, all stations within radio range compete for transmission resources. If a station's transmission undergoes multiple backoff procedures, it may result in a high probability of experiencing long delays when accessing the medium. An overview of delay-sensitive applications where timeliness is crucial and transmission protocol adaptation is considered is provided in the following paper: Y. Cheng, D. Yang, H. Zhou, and H. Wang, "Adopting IEEE 802.11 MAC for industrial delay-sensitive wireless control and monitoring applications: A survey," Computer Networks, page 27, 2019. Summary of the Invention

[0005] Hence, an object is to improve the latency of transmissions (especially when accessing the medium).A further object is to provide deterministic access to a radio network, eg in order to initiate scheduled transmissions.

[0006] This object is achieved by the subject matter of the independent claims. Advantageous embodiments are provided in the dependent claims and described in the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 The channel access mechanism according to Wi-Fi 5 (and earlier versions) is shown.

[0008] Figure 2A channel access mechanism according to Wi-Fi 6 is shown.

[0009] Figure 3 A channel access mechanism is shown that allows deterministic channel access.

[0010] Figure 4 A diagram showing an access point and two stations is shown.

[0011] Figure 5 A sequence diagram including transmission of a frame for suspending contention-based access to a radio network is shown.

[0012] Figure 6 An exemplary MU-EDCA parameter set is shown.

[0013] Figure 7 The transmission of a BSRP frame for suspending contention-based access to a radio network is shown.

[0014] Figure 8 The access delay for different access control types is shown.

[0015] Figure 9 Different frame types are shown.

[0016] Figures 10 to 20 Exemplary method steps are shown. DETAILED DESCRIPTION

[0017] Figure 1 、 Figure 2 and Figure 3 The following diagram illustrates the conceptual differences in channel access, medium access, or access mechanisms between Wi-Fi 5 (ie, IEEE 802.11ac) (and earlier versions) and Wi-Fi 6 (ie, 802.11ax).

[0018] exist Figure 1 The distributed approach used for Wi-Fi 5 and earlier versions is shown in . Channel access is based on listen-before-talk (or carrier sense multiple access with collision avoidance (CSMA / CA)). For transmission, stations (STAs) (including the AP) can individually attempt to access the medium. If a station STA finds the medium idle for a certain amount of time, it starts transmitting using the entire assigned subchannel. This mechanism is also known as the Distributed Coordination Function (DCF). DCF is extended with the Enhanced Distributed Channel Access (EDCA) mechanism, which introduces priority to Wi-Fi in the form of four access categories: voice, video, background, and best effort. The main goal is to be able to optimize average performance (e.g., latency and jitter) for multimedia services.

[0019] Wi-Fi 6 brings two major advantages. The first is the new 6 GHz band that can be used by stations with Wi-Fi 6 capabilities and later versions. However, the new 6 GHz band is not available for stations before Wi-Fi 6. This means that currently only Wi-Fi 6 STAs will use the 6 GHz band, so there is no need to deal with backward compatibility issues in this band. The second major advantage of Wi-Fi 6 compared to traditional Wi-Fi is the use of Orthogonal Frequency Division Multiple Access (OFDMA). Compared with Wi-Fi 5 and earlier Wi-Fi versions, with OFDMA, the access point AP controls the allocation of sub-channel resources (i.e., resource units (RU)) more efficiently (i.e., allocates sub-channel resources). To this end, Figure 2 As shown in , APs must contend for the medium (using EDCA, as EDCA is one of the default channel access mechanisms in modern Wi-Fi networks) before performing frequency allocation centrally. Figure 1 Compared to pre-Wi-Fi 6 (where STAs could independently initiate UL transmissions and block the entire channel), whether a downlink (DL) or uplink (UL) OFDMA transmission should occur, the first thing that happens is that the AP wins the contention with the associated STA. Figure 2 A Wi-Fi or WLAN consisting of Wi-Fi 6 STAs and STAs prior to Wi-Fi 6 is shown, that is, OFDMA transmission can be initiated by the AP and typical distributed access can be performed by the STAs.

[0020] Figure 3 An access mechanism is shown that allows deterministic medium access, channel access, or generally, access to, for example, a radio network. Here, because STAs are suspended from accessing the channel / medium, the AP can centrally perform frequency allocation. Consequently, the AP can perform deterministic (channel / medium) access to initiate scheduled transmissions. The AP can thus access the channel / medium within a predictable (e.g., maximum) time. Consequently, one or more STAs associated with the AP are (at least temporarily) not allowed to contend for the medium and / or perform contention-based access to the radio network, and in particular, are not allowed to access the medium or access channel, e.g., for transmissions to an access node (such as an access point AP).

[0021] This results in the AP (always) winning the contention and, therefore, being able to initiate transmissions, such as OFDMA uplink or downlink transmissions. Consequently, STAs are blocked from channel / medium access (i.e., in the uplink). However, these "blocked" STAs are not resource-starved, as the AP can still allocate resources for UL transmissions by one or more STAs (e.g., using OFDMA), and / or can even be more efficient than if one or more STAs were blocking the medium / channel, for example, using traditional (MU-)EDCA mechanisms. Since there are no STAs competing for the channel / medium in the radio network, the AP's channel / medium access time (and, therefore, the transmissions of one or more stations scheduled by the access point, for example) becomes predictable and / or deterministic.

[0022] It should be understood that a terminal device (such as a user equipment UE) can be used instead of a station STA. In addition, an access node (such as a base station) can be used instead of an access point. Furthermore, instead of the WiFi network 1, a radio network, such as a mobile radio network (for example, in accordance with 3GPP Release 18, Release 17, Release 16, Release 15, Release 14, Release 13, Release 12, Release 11, Release 10, Release 9, and / or Release 8) can be used. In any case, any other access node in the radio network and / or any other terminal device in the radio network can be used, and the access node and / or terminal device, for example, adopts contention-based access (such as carrier sense multiple access with collision avoidance (CSMA / CA) and / or carrier sense multiple access with collision detection (CSMA / CD)).

[0023] Figure 4 A diagram showing an access point AP and two stations STA1 , STA2 is shown.

[0024] One or more stations STA1, STA2 are initially unauthenticated and / or unassociated with the access point AP. The stations STA1, STA2 and the access point AP will exchange a series of management frames, for example, according to IEEE 802.11ac or 802.11ax, to reach an authenticated and associated state, i.e., the stations STA1, STA2 are associated with the access point AP.

[0025] For example, according to 802.11ac / ax, three possible connection states include: unauthenticated or unassociated; authenticated but not yet associated; and authenticated and associated.

[0026] The stations STA1 , STA2 may actively or passively scan a radio network 1 , such as a wireless network.

[0027] For example, stations STA1 and STA2 may send a probe request to discover Radio Network 1 within their proximity. The AP may then send a probe response, advertising its SSID (wireless network name), supported data rates, encryption type (if required), and / or other 802.11ac / ax capabilities. Stations STA1 and STA2 may then send an authentication frame to the AP. The AP receives the authentication frame and / or responds to STA1 and STA2 with a set of authentication frames. At this point, stations STA1 and STA2 are authenticated but not yet associated.

[0028] If the AP receives any frame other than an authentication or probe request from an unauthenticated station STA1, STA2, it will respond with a deauthentication frame which puts the station STA1, STA2 into an unauthenticated and / or unassociated state.

[0029] Stations STA1, STA2 can be authenticated to multiple APs, but can only be (actively) associated to a single AP (at a time). However, multi-connectivity is considered in IEEE 802.11be / Wi-Fi 7, i.e. stations can then be allowed to actively connect to multiple access points.

[0030] Stations STA1 and STA2 then send an association request to the AP. The association request may include the encryption type and / or other 802.11ac / ax-compatible capabilities. The AP may then send a success message to stations STA1 and STA2 authorizing radio network access.

[0031] Alternatively, the stations STA1 and STA2 can passively scan the access point AP. To this end, the stations STA1 and STA2 listen to the beacon frames periodically sent by the AP in each channel to obtain AP information. Such beacon frames (e.g., Figure 5 The AP (as shown) may contain information including the AP's SSID and / or supported data rates.

[0032] Therefore, the stations STA1, STA2 may be associated with the access point AP.

[0033] Access mechanisms to channels / mediums and / or radio networks (e.g., in Wi-Fi) can be based on distributed mechanisms (distributed coordination function (DCF) and / or enhanced distributed channel access (EDCA)) and / or operate in a listen-before-talk mode (such as CSMA / CA). EDCA is a mechanism optimized for high throughput and average latency, but not for determinism and / or worst-case transmission delay. Industrial applications, in particular, require deterministic and / or real-time wireless communications with guaranteed medium / channel access. These can be based on polling-based mechanisms, which are often non-compliant with IEEE 802.11ac / ax, or TDMA-based mechanisms (i.e., proprietary solutions) with high implementation complexity. For example, Wi-Fi 6 uses orthogonal frequency division multiple access (OFDMA), which represents a paradigm shift from distributed channel access to centrally controlled (i.e., scheduled) transmissions. Specifically, the AP consistently uses so-called trigger frames compliant with IEEE 802.11ax to control the initiation of OFDMA transmissions in both the uplink and downlink directions. However, because IEEE 802.11 networks are backward compatible, 802.11ax networks must support both centralized and distributed medium access mechanisms. To address this paradigm shift, the IEEE has developed a new multi-user (MU) extension to EDCA in Wi-Fi 6 / IEEE 802.11ax, known as MU-EDCA. MU-EDCA is designed to reduce the average channel / medium access time of access points when contending with associated IEEE 802.11ax STAs during channel access. MU-EDCA reduces the average channel / medium access time of APs. However, it currently cannot guarantee the worst-case medium / channel access latency required in industrial solutions.

[0034] Initially, EDCA introduced four access categories (ACs) to prioritize multimedia services (e.g., voice and video) over best-effort services. Each of the four ACs has a separate set of EDCA parameters, known as a Wireless Multimedia (WMM) parameter set.

[0035] The MU-EDCA technology introduced with IEEE 802.11ax allows an AP to adjust channel / medium access parameters for one or more stations and use a separate EDCA parameter set (referred to as a MU-EDCA parameter set). The MU-EDCA parameter set can be distributed via one or more beacon frames (similar to the WMM parameter set). As described in this disclosure, the MU-EDCA parameter set can be used as a first access configuration, and the EDCA (WMM) parameter set can be used as a second access configuration.

[0036] The MU-EDCA parameter sets are intended to degrade the medium / channel access probability for stations using EDCA, as they typically require longer arbitration interframe space (AIFS) and contention windows compared to those in the EDCA (WMM) parameter set.

[0037] The MU-EDCA parameter set shall be activated after a successful UL OFDMA transmission and shall last for the duration specified by the MU-EDCA parameters (ie, MU-EDCA Timer 4).

[0038] Therefore, using MU-EDCA, an access point (AP) can reduce the probability that a station (e.g., one that has just performed an UL transmission) will access the channel again in the near future. However, current MU-EDCA mechanisms do not guarantee the worst-case channel / medium access time required for deterministic channel / medium access (i.e., wireless communication) for the access point (AP), but rather optimize average channel / medium access performance in favor of the access point (AP).

[0039] Go to Figure 5 , shows a sequence diagram for suspending the transmission of one or more frames for contention-based access of one or more terminal devices (such as said stations) to a radio network. The terminal devices (here the stations STA1, STA2) may for example suspend the transmission of one or more frames for contention-based access of one or more terminal devices (such as said stations) to a radio network according to a combination of Figure 4 The detailed mechanism is associated with an access node (such as an access point AP).

[0040] Beacon frames are one type of management frame in radio networks based on IEEE 802.11ac / ax (referred to herein as Wi-Fi or WLAN). Beacon frames contain (all) information about the radio network. Beacon frames may be transmitted periodically to advertise the presence of access points (APs) (i.e., WLANs) and / or for synchronization. Beacon frames may be transmitted, for example, by access points (APs) within the infrastructure's basic service set (BSS).

[0041] The beacon frame can be used to distribute the MU-EDCA parameter set (similar to the WMM parameter set). Therefore, the beacon frame can contain the MU-EDCA parameter set.

[0042] When stations STA1 and STA2 receive the beacon frame, they thus receive information about the capabilities and / or configuration of the radio network. Stations STA1 and STA2 can then configure themselves according to the obtained MU-EDCA parameter set. Thus, any pre-existing MU-EDCA parameter set can be replaced.

[0043] The MU-EDCA parameter set (which can be applied to all four EDCA access categories (ACs)) may include: Figure 6 The parameters and / or parameter values ​​shown.

[0044] The MU-EDCA parameter set may include parameters AIFSN and MU-EDCA timer. Figure 6 As shown, the AIFSN is set to 0, and therefore stations STA1 and STA2 are not allowed to use EDCA (i.e., EDCA parameter set) for channel / medium access (e.g., in a specific AC). The MU-EDCA timer is set to a value (e.g., to the longest possible MU-EDCA timer) so that the access point AP can ensure that the MU-EDCA timer is reset before it expires. As described in the present invention, the timer reset can be caused by the AP's transmission of a frame.

[0045] This MU-EDCA parameter set allows disabling EDCA-based channel / medium access for the stations STA1, STA2 and allows the access point AP to win contention-based access.

[0046] Back to Figure 5 For example, after transmitting a beacon frame, the access point AP may transmit a frame that causes a station to suspend contention-based access to the radio network. This frame TF, when received by the stations STA1 and STA2, causes the stations STA1 and STA2 to reset their / their MU-EDCA timers. Thus, for example, instead of and / or in addition to resetting the MU-EDCA timers upon successful completion of an UL OFDMA transmission (e.g., as defined in IEEE 802.11ax), when the AP sends or transmits a frame (e.g., a trigger frame TF, in particular, one or more trigger frames TF of a specific type) to one or more stations STA1 and STA2, the MU-EDCA timers of the stations STA1 and STA2 should be reset.

[0047] Since the access point AP controls the transmission of these frames (which may also be referred to as pause frames) to the stations STA1, STA2, it can now control when and / or how often the stations STA1, STA2 reset their / their MU-EDCA timers. Thus, the access point AP can reset the timers before they expire so that the station or stations STA1, STA2 will always use the first access configuration (e.g., Figure 6 ), and therefore cannot use the second access configuration (i.e., the EDCA (WMM) parameter set) for transmission, for example according to EDCA.

[0048] Since all associated stations STA1, STA2 (or at least a subset thereof) can receive these frames from the AP, timers (especially MU-EDCA timers) will be reset for all associated STAs (or at least a subset thereof), not just for the STAs that immediately participated in the UL OFDMA transmission.

[0049] Therefore, the proposed mechanism (i.e., a modification to the MU-EDCA mechanism) does not allow the associated stations STA1, STA2 to contend for the channel / medium. This results in the access point AP (always) winning the contention and, therefore, being able to initiate / schedule (e.g., using OFDMA) uplink and / or downlink transmissions for the (preferably associated) stations STA1, STA2. Overall, the proposed method can be viewed as a way of preventing one or more stations STA1, STA2 from accessing the channel / medium, for example, in the uplink. However, these blocked stations STA1, STA2 will still be able to transmit because the access point AP will still allocate resources (e.g., using OFDMA) for, for example, the UL transmissions of the stations STA1, STA2 (which is even more efficient than if the stations STA1, STA2 were blocking the channel / medium using conventional EDCA mechanisms (e.g., in OFDM-based transmissions)).

[0050] Therefore, since there are currently no stations STA1, STA2 competing for the channel / medium in the radio network (or there are a reduced number of stations) (given the 6 GHz band and / or MU-EDCA parameter sets (e.g. Figure 6 (as shown) is enabled), the channel / medium access time of the access point AP and thus the transmission of one or more stations STA1, STA2 also becomes predictable / deterministic.

[0051] Thus, for example according to Multi-User EDCA (MU-EDCA) introduced with IEEE 802.11ax / Wi-Fi 6, an access AP will win the contention with respect to its associated stations STA1, STA2.

[0052] In a radio network consisting only of IEEE 802.11ax compliant stations (eg, in the 6 GHz band), MU-EDCA may be used to increase the probability of the access point AP winning medium / channel access relative to the stations STA1, STA2.

[0053] MU-EDCA parameters may not initially be available to one or more stations, i.e., they may not be stored, for example, in the station's memory. MU-EDCA parameters can be sent or transmitted by the AP in a beacon and thus stored on one or more stations and / or activated by one or more stations (e.g., upon successful UL OFDMA transmission). However, sending or transmitting the MU-EDCA parameters with one or more control frames (e.g., trigger frames (TFs)) may be more flexible. This allows for faster adaptation of the first access configuration, for example, compared to using beacon frames that are transmitted every 100 ms by default. A further aspect is the permanent activation of the first access configuration (e.g., the so-called MU-EDCA parameter (set)) based on the resetting of a timer (e.g., a MU-EDCA timer) (preferably for one or more stations STA1, STA2 associated with the access point AP). The resetting can be controlled by the transmission of one or more frames (e.g., trigger frames (TFs)) by the access point (or, more generally, access node). This frame or frame type may also be referred to as a pause frame, as it pauses contention-based access (to the radio network) by the terminal device.

[0054] Instead of or in addition to including MU-EDCA parameters in a beacon frame, MU-EDCA parameters present in a station may be used and / or activated via a flag in a frame (such as a beacon frame). Thus, a flag (e.g., in the form of one or more bits in a beacon frame) may be transmitted by the AP. For example, a flag in a capability information element (IE) of a beacon frame may be used. The flag will indicate to the associated STAs to use and / or activate the MU-EDCA parameters or MU-EDCA parameter(s), e.g., according to Figure 6 Additionally, a frame containing such an indication (eg, in the form of the mentioned flag) may cause the station's MU-EDCA timer to be reset.

[0055] In addition, a flag in a frame sent by the AP (e.g., a flag in a common information field in a frame (e.g., a BSRP frame)) may be used to cause a station to use and / or activate MU-EDCA parameters and / or reset a MU-EDCA timer. This flag may indicate to a station receiving the BSRP frame to use (modified) MU-EDCA parameters and / or reset a MU-EDCA timer.

[0056] Go to Figure 7 , shows an embodiment including transmission of a first frame (such as a BSRP frame) and / or a second frame (such as a basic trigger frame) for suspending contention-based access to the radio network. As before, two stations STA1, STA2 associated with an access point AP are shown again.

[0057] It is proposed that the MU-EDCA timer be reset when one or more STAs receive a frame from an access point (AP), such as a Buffer Status Report Poll (BSRP) frame. The BSRP frame is a frame type standardized by IEEE 802.11ax. The BSRP frame was chosen because it is a crucial component of UL OFDMA transmissions. The purpose is that the AP can use the BSRP frame to query associated STAs for their buffered traffic. STAs respond to the BSRP with a Buffer Status Report (BSR) frame, which contains information about the data packets the station wishes to send to the AP, such as the payload size of the buffered data traffic or QoS requirements. Therefore, BSRP is typically used in most UL OFDMA transmissions.

[0058] like Figure 7 As shown, the channel / medium may initially be busy, i.e., one or more stations are transmitting and / or receiving traffic (e.g., in the form of one or more (data) frames) according to the channel and / or resource units assigned to them by the access point. This busy medium is followed by a contention window, during which contention-based access and / or corresponding access attempts by stations STA1, STA2, and / or the access point AP may occur. However, due to the successful UL transmission, the MU-EDCA parameter set for stations STA1 and STA2 is activated. This MU-EDCA parameter set persists (i.e., remains active) for a duration specified by the MU-EDCA timer. As described in this disclosure, the MU-EDCA parameter set is intended to degrade the medium / channel access probability for STAs using MU-EDCA, as it typically requires a longer AIFS (N) and contention window than the parameters in the EDCA (WMM) parameter set. Therefore, stations STA1 and STA2 will not perform contention-based access in the subsequent contention window according to their MU-EDCA parameter set values.

[0059] Thereupon, the AP obtains access to the medium and transmits a BSRP frame, which preferably includes the new MU-EDCA parameter set and / or corresponding parameter values, e.g. Figure 6 One or more stations STA1, STA2 (after receiving the BSRP frame) respond to the BSRP frame with a BSR frame. As shown, a SIFS may be placed between the BSRP frame and the BSR frame. For example, after another SIFS, the access point may transmit a second type of frame (e.g., a control frame, such as in Figure 7 The second type of frame is a basic trigger frame represented as a basic TF in the MU-EDCA parameter set, which enables stations STA1 and STA2 to suspend contention-based access, for example, by resetting the MU-EDCA timer in the MU-EDCA parameter set.

[0060] Accordingly, the access point can schedule transmission opportunities for stations STA1 and STA2. That is, the access point AP can allocate transmission resources for stations STA1, STA2, or multiple stations (preferably based on at least one received buffer status report frame). As shown in the figure, transmission opportunities and transmission resources are associated with UL PPDU transmissions. Therefore, the stations can preferably transmit one or more frames in the uplink (UL) based on the transmission resources allocated by the access point (e.g., based on the buffer status reports from stations STA1 and STA2), each of which includes a physical protocol data unit (PPDU). As shown in the figure, the access point AP can then acknowledge receipt of the PPDU transmitted by the station.

[0061] Figure 8 The access delay for different access control types is shown. The access delay is given in μs. The worst-case channel access delay is shown for EDCA, MU-EDCA, and the MU-EDCA parameter set and modified mechanism CuMU-EDCA as proposed in this invention.

[0062] It can be seen that when EDCA or standard MU-EDCA is used, the access time or access delay increases with the number of stations, whereas when a modified mechanism as proposed in the present invention is employed (i.e., when the access point transmits a frame that causes the stations to suspend contention-based channel access), the access time or access delay remains constant.

[0063] With changing the configuration of MU-EDCA parameters to favor the AP and modifying the MU-EDCA mechanism as proposed in the present invention, a maximum worst-case channel access time of 55 μs for the AP can be achieved. Figure 8 Shown is a comparison of the worst-case channel access time of an AP for standards-compliant EDCA (upper curve), MU-EDCA (middle curve), and a modified version of MU-EDCA known as CuMU-EDCA; lower flat line curve.

[0064] In order to get Figure 8 The curves shown in have been simulated for an IEEE 802.11ax network with up to 30 STAs. The worst-case channel / medium access delay for the AP can be calculated as follows:

[0065] Delay = SIFS + (AIFSN + CW) * ST

[0066] Where: Delay = Channel Access Delay, SIFS = Short Interframe Space, AIFSN = Arbitration Interframe Space Number, CW = Contention Window, ST = Slot Time.

[0067] For simulation of the Wi-Fi 6 scenario, this yields a maximum of 55 μs as the worst-case channel / medium access time for the AP:

[0068] Delay = SIFS + (AIFSN + GW) * ST = 10μs+ (2+3) * 9μs = 55μs

[0069] An alternative implementation is to reset the MU-EDCA timer when one or more STAs receive a basic trigger frame sent by the AP. The basic trigger frame is mandatory for each UL OFDMA transmission because it is used to synchronize the start time of UL OFDMA data transmission (i.e., one SIFS after the basic trigger frame, STAs begin to send their UL PPDUs simultaneously on their assigned RUs). However, since the basic trigger frame is mandatory for each UL OFDMA transmission, the MU-EDCA timer may be reset more frequently than necessary.

[0070] Polling-based mechanisms for (semi-)deterministic channel access in radio networks such as Wi-Fi already exist (e.g. Point Coordination Function (PCF) or Hybrid Coordination Function (HCF) Controlled Channel Access (HCCA), or even proprietary products like iWLAN that use a modified version of PCF known as industrial PCF).

[0071] With the new OFDMA direction in Wi-Fi 6 and later versions, Wi-Fi evolves into a more AP-centric communication technology (similar to the adoption of OFDMA in cellular 5G technology). Therefore, the aspects and embodiments presented in this disclosure can be applied to mobile radio networks according to, for example, 4G, 5G, or 6G specifications.

[0072] The proposed new solution modifies existing medium or channel access mechanisms (particularly MU-EDCA) to achieve deterministic channel access (latency), particularly in OFDMA-based Wi-Fi (802.11) networks. A primary advantage is reduced, predictable, and / or deterministic medium / channel access (latency) for OFDMA-based transmissions, for example, in the uplink and / or downlink directions. Another advantage is the ease of implementing the proposed modifications to the existing MU-EDCA mechanism in Wi-Fi 6.

[0073] Figure 9Different frame types are shown. Frames of these frame types or formats can be used to suspend channel-based access by one or more terminal devices (such as the stations discussed herein). Depending on the circumstances, one or more frames (preferably transmitted and / or received by the terminal devices) can be used to suspend contention-based access. Therefore, these frames can be referred to as pause frames.

[0074] Figure 9 Figure 1 shows three frame types according to 802.11, namely management frames, control frames, and data frames. Management frames are used to manage the basic service set (BSS), control frames control access to the medium, and data frames contain payloads, for example, including information for applications and protocols (such as higher-level layers 3 to 7).

[0075] In particular, one or more management frames (ie, management frame types or formats) may be used, such as probe requests and / or probe responses, association requests and / or association responses, authentication requests and / or authentication responses, timing announcements.

[0076] Additionally, additionally, or alternatively, one or more control frames (i.e., control frame types or formats) may be used, such as one or more trigger frames. In particular, one or more basic trigger frames, one or more buffer status report poll trigger frames, one or more MU-RTS trigger frames, and one or more beamforming report poll trigger frames may be used. Other frame types or formats are provided in Section 9.3.1.22 of IEEE Standard 802.11ax-2020 and its revised version, IEEE Standard 802.11ax-2021.

[0077] Finally, additionally or alternatively, one or more data frames may be used such that they may be used to suspend channel-based access by one or more terminal devices (such as the stations discussed in this invention).

[0078] A station or terminal device generally may be operable and / or configured to suspend contention-based access upon or after receiving such a pause frame.

[0079] All 802.11ac / ax frames fall into one of three types: management, control, or data. A frame may include a header, which in turn includes a frame control field containing the frame type and subtype values. The type field indicates a management frame, control frame, or data frame. The subtype field indicates the specific type of management frame, control frame, or data frame. One type of management frame is a beacon (frame) transmitted by an access point, for example, at regular intervals. Beacon frames may contain the configuration of a radio network (such as a WLAN), including whether it supports standards such as 802.11k and 802.11r, the required cipher suites and authentication key management (AKM) methods, and whether protection mechanisms are required, as described in this disclosure.

[0080] Thus, a management frame (e.g., a beacon frame) may contain a MU-EDCA parameter set (e.g., Figure 6 as shown), and / or may cause the terminal device to suspend contention-based access to the radio network.

[0081] A control frame may be a Request to Send (RTS) frame and / or a Clear to Send (CTS) frame. A control frame may be used to control access to the medium and / or for frame acknowledgment. A control frame may contain only a header and trailer, i.e., no body. Thus, a combination of management frames and control frames may make it possible to suspend contention-based access to the radio network for one or more terminal devices. That is, management frames are initially transmitted, and control frames are subsequently transmitted in order to suspend contention-based access, i.e., to cause a terminal device to suspend contention-based access to the radio network. In any case, a combination of control frames may also be used to initially notify a terminal device of a first access configuration and / or to activate the first access configuration and / or to suspend contention-based access for a terminal device (e.g., by resetting a timer for the terminal device).

[0082] Finally, data frames can be used to convey information or trigger events. Thus, data frames can also be used to suspend contention-based access, i.e., to cause a terminal device to suspend contention-based access to the radio network (e.g., by resetting a timer on the terminal device). Not all data frames contain a payload; some are "empty data frames" containing only a header and trailer. For example, an access point can transmit one or more broadcast or multicast frames to suspend contention-based access, i.e., to cause a terminal device to suspend contention-based access to the radio network, i.e., access the medium / channel.

[0083] It should be understood that for exemplary purposes, a system with access points and stations according to IEEE 802.11ax is described, but the teachings disclosed in this invention are applicable to other radio systems or wireless systems (particularly, those employing contention-based access).

[0084] Go to Figure 10 , shows an exemplary method step S1. In step S1, the access node may transmit a frame that causes the terminal device to suspend contention-based access to the radio network. As already mentioned, such a frame may be called a pause frame. In particular, the terminal device may suspend contention-based access to an access node (e.g., an access point) of the radio network. So far, the terminal device may be associated with an access node or access point, for example as described in the present invention. The frame may be a frame specifically related to the present invention. Figure 9Any of the frames described herein. An access node may transmit frames for reception by terminal devices via beaconing, broadcasting, or multicasting. In any case, the frame may be addressed to one or more, or all, terminal devices associated with the access node. Thus, the frame may include a destination address corresponding to the address of one or more terminal devices to which the frame is addressed. This transmission allows the access node to control access to the radio network.

[0085] Therefore, a method for controlling access to a radio network 1 is proposed. The method comprises transmitting, by an access node AP, a frame 2 for at least one terminal device STA, STA1, STA2, wherein the frame 2 causes the terminal device STA, STA1, STA2 to suspend contention-based access to the radio network 1 .

[0086] The method may comprise, wherein the frame 2 causes the terminal device STA, STA1, STA2 to apply a first access configuration 3 for contention based access, according to which the terminal device STA, STA1, STA2 suspends contention based access to the radio network 1 .

[0087] The method may include wherein frame 2 causes the terminal devices STA, STA1, STA2 to suspend contention-based access for a predetermined period of time.

[0088] The method may include wherein frame 2 causes a timer of the terminal device STA, STA1, STA2 to be reset, wherein upon expiry of timer 4 the terminal device STA, STA1, STA2 resumes contention-based access to the radio network 1 .

[0089] The method may comprise, wherein upon expiry of the timer 4, the terminal device STA, STA1, STA2 resumes contention based access according to the second access configuration.

[0090] The method may comprise, wherein the frame 2 comprises one or more parameters 4, 5 for configuring the first access configuration 3, in particular for configuring the AIFSN and / or the MU-EDCA timer.

[0091] The method may include, wherein the timer 4 of the terminal device STA, STA1, STA2 is started and / or reset after a contention-based access of the terminal device STA, STA1, STA2 is successful.

[0092] The method may comprise wherein frame 2 causes each of a predetermined number of terminal devices STA, STA1, STA2 (preferably a majority of the terminal devices, and most preferably all the terminal devices STA, STA1, STA2) associated with the access node AP to suspend contention based access to the radio network 1 .

[0093] The method may comprise repeatedly, preferably periodically, transmitting a frame 2 to at least one terminal device STA, STA1, STA2 in order to suspend contention-based access of the at least one terminal device STA, STA1, STA2 to the radio network 1 .

[0094] The method may comprise using at least one control frame type 21 , preferably a trigger frame 22 , most preferably a buffer status report poll 23 , as a frame 2 for causing at least one terminal device STA, STA1 , STA2 to suspend contention-based access to the radio network 1 .

[0095] The method may include: using different types of control frames 21 as frames for causing the terminal device to suspend contention-based access to the radio network, wherein the first type of control frame 22 includes one or more parameters for configuring the first access configuration 3, and the second type of control frame 22 does not have one or more parameters for configuring the first access configuration 3.

[0096] The method may include attempting, by the access node AP, contention-based access after transmitting frame 2 .

[0097] The method may comprise receiving, by the access node AP, a buffer status report from at least one terminal device STA, STA1, STA2, the buffer status report comprising, for example, an acknowledgement.

[0098] The method may comprise allocating, by the access node AP, preferably based on the received at least one buffer status report, to at least one terminal device STA, STA1, STA2 transmission resources for transmission from the terminal device STA, STA1, STA2 to the access node AP.

[0099] Furthermore, an access node AP of a radio network 1 is proposed, preferably comprising a processor and a memory operable to perform the method steps as described.

[0100] Furthermore, a method for controlling access to a radio network 1 is proposed, wherein the method comprises: receiving a frame 2 by a terminal device STA, STA1, STA2 from an access node AP of the radio network 1, wherein the frame 2 causes the terminal device STA, STA1, STA2 to suspend contention-based access to the radio network 1.

[0101] Furthermore, a terminal device STA, STA1, STA2 of a radio network 1 is proposed, preferably comprising a processor and a memory operable to perform the method steps of the aforementioned method.

[0102] Go to Figure 11, illustrating an exemplary method step S2. In step S2, the access node may transmit a frame that causes the terminal device to apply a first access configuration for contention-based access, according to which the terminal device suspends contention-based access to the radio network. The first access configuration may include one or more parameters according to which contention-based access is performed. For example, the first access configuration may correspond to a MU-EDCA parameter set as described herein.

[0103] Go to Figure 12 , an exemplary method step S3 is shown. In step S3, the access node may transmit a frame that causes the terminal device to suspend contention-based access for a predetermined period of time.

[0104] Go to Figure 13 , shows an exemplary method step S4. In step S4, the access node may transmit a frame that causes a timer of the terminal device to be reset, wherein upon expiration of the timer, the terminal device resumes contention-based access to the radio network. The timer may be running in the terminal device.

[0105] Upon expiration of the timer, the terminal device may resume contention-based access according to the second access configuration. The second access configuration (for contention-based access) may also be stored in the terminal device. The second access configuration may correspond to an EDCA parameter set, which is also referred to as a WMM parameter set.

[0106] Go to Figure 13 , illustrating an exemplary method step S4. In step S4, the access node may transmit a frame including one or more parameters (such as a MU-EDCA parameter set) for configuring a first access configuration. The parameters included in the frame may be or may be used to configure the first access configuration, for example, parameters such as AIFSN and / or a MU-EDCA timer.

[0107] As described in the present invention, a timer for a terminal device is started and / or (re)set after a successful contention-based access by the terminal device. During the runtime of the timer, the terminal device therefore relies on a first access configuration to perform contention-based access. In particular, the first access configuration may (in particular, during the runtime of the timer) prohibit contention-based access to the radio network. Alternatively, the first access configuration may include a setting with an extended backoff period that degrades the probability of contention-based access (e.g., through a high AISFN setting). A second access configuration is adopted by the terminal device upon expiration or expiration of the timer. Typically, the second access configuration will allow contention-based access to the radio network. As described in the present invention, after a successful contention-based access and / or transmission by the terminal device, the timer is (re)started or (re)set. As a result, the terminal device uses the first access configuration to access the radio network, thereby reducing the chances of immediate medium access for the terminal device.

[0108] Go to Figure 14 , an exemplary method step S5 is shown. In step S5, the access node may transmit a frame that causes each of a predetermined number of terminal devices (preferably a majority of the terminal devices, and most preferably all the terminal devices) associated with the access node to suspend contention-based access to the radio network. As appropriate, the terminal device or devices for which a timer reset is required may be determined by the access node or another network function. The access node may then transmit a frame to be received by the terminal device, for example as a management frame and / or a control frame. Thus, by resetting the timers of at least some of the terminal devices associated with the access point (i.e., by suspending contention-based access for these terminal devices), the probability of the access point winning contention-based access is increased.

[0109] Go to Figure 15 , illustrating an exemplary method step S6. In step S6, the access node may repeatedly (preferably periodically) transmit a frame to at least one terminal device to suspend contention-based access to the radio network by the at least one terminal device. This repetition may be periodic, as in the case of beacon frames transmitted according to a beacon period or interval (e.g., every 102.4 ms).

[0110] It should be understood that it can be transmitted by the access node including the combination of Figures 10 to 15 The same frame may be a frame having the attributes described in any of the figures and / or causing the terminal device to perform the actions described in the present invention. However, in any case, it may be a frame transmitted by the access node with the attributes described in any of the figures and / or causing the terminal device to perform the actions described in the present invention. Figures 10 to 15 A separate frame describing the properties.

[0111] Go to Figure 16, an exemplary method step S7 is shown. In step S7, at least one control frame type (preferably a trigger frame, most preferably a buffer status report poll) is used as a frame for causing at least one terminal device to suspend contention-based access to the radio network, e.g. as described in the present invention.

[0112] Go to Figure 17 , illustrating an exemplary method step S8. In step S8, different types of control frames can be used as the frames, wherein a first type of control frame includes one or more parameters for configuring a first access configuration (e.g., a MU-EDCA parameter set), and a second type of control frame does not (i.e., does not include) one or more parameters for configuring the first access configuration. As mentioned above, and even more generally, the first frame can be a management frame such as a beacon frame, and the second frame can be a control frame such as a trigger frame (e.g., a basic trigger frame).

[0113] Go to Figure 18 , an exemplary method step S9 is shown. In step S9, the access node may attempt contention-based access after transmitting the frame. That is, the access node is guaranteed to succeed in accessing the medium, or at least has an increased chance, depending on the specific implementation selected as described in the present invention.

[0114] Go to Figure 19 , illustrating exemplary method steps S10 and S11. In step S10, the access node may receive a buffer status report from at least one terminal device, the buffer status report comprising, for example, an acknowledgment. This may be the case, for example, if BSRP frames are used to suspend contention-based access for the terminal device, and / or to reset a timer for the terminal device (in a first access configuration), and / or to transmit the first access configuration to the terminal device.

[0115] Subsequently, in step S11 , the access node may allocate, to at least one terminal device, transmission resources for transmission from the terminal device to the access node, preferably based on the received at least one buffer status report.

[0116] Go to Figure 20 , shows an exemplary method step S12. In step S12, the terminal device may receive a frame from an access node of the radio network, wherein the frame causes the terminal device to suspend contention-based access to the radio network. The frame may include a frame as specifically combined with the present invention. Figures 10 to 19 It should also be understood that in conjunction with any of the attributes described herein, Figures 10 to 20 The steps described may be combined so as to obtain a series of consecutive steps.

Claims

1. A method of controlling access to a radio network (1), the method comprising: A frame (2) of at least one terminal device (STA, STA1, STA2) is transmitted by an access node (AP), wherein the frame (2) causes the terminal device (STA, STA1, STA2) to suspend contention-based access to the radio network (1) by resetting a timer running in the terminal device (STA, STA1, STA2) before the timer expires, and wherein the terminal device resumes contention-based access to the radio network when the timer expires.

2. The method according to the preceding claim, wherein The frame is transmitted after the uplink transmission of the terminal device is successful.

3. A method according to any one of the preceding claims, wherein The timer (4) of the terminal device (STA, STA1, STA2) is started after uplink transmission of the terminal device (STA, STA1, STA2) is successful.

4. A method according to any one of the preceding claims, wherein During the runtime of the timer, contention-based access of the terminal device is suspended.

5. A method according to any one of the preceding claims, wherein A plurality of terminal devices (STA1, STA2) associated with the access node receive one or more frames from the access node, and wherein the timers of the associated terminal devices are reset.

6. A method according to any one of the preceding claims, wherein The frame is a broadcast frame or a multicast frame.

7. A method according to any one of the preceding claims, wherein The frame (2) causes the terminal device (STA, STA1, STA2) to apply a first access configuration (3) for contention-based access, according to which the terminal device (STA, STA1, STA2) suspends contention-based access to the radio network (1).

8. A method according to any one of the preceding claims, wherein The frame (2) causes the terminal devices (STA, STA1, STA2) to suspend contention-based access for a predetermined period of time.

9. A method according to any one of the preceding claims, wherein When the timer (4) expires, the terminal device (STA, STA1, STA2) resumes contention-based access according to the second access configuration.

10. A method according to any one of the preceding claims, wherein The frame (2) comprises one or more parameters (4, 5) for configuring a first access configuration (3), in particular for configuring an AIFSN and / or MU-EDCA timer.

11. A method according to any one of the preceding claims, wherein The timer (4) of the terminal device (STA, STA1, STA2) is started and / or reset after contention-based access of the terminal device (STA, STA1, STA2) is successful.

12. A method according to any one of the preceding claims, wherein The frame (2) causes each terminal device of a predetermined number of terminal devices (STA, STA1, STA2), preferably a majority of the terminal devices and most preferably all the terminal devices (STA, STA1, STA2) associated with the access node (AP) to suspend contention-based access to the radio network (1).

13. The method according to any of the preceding claims, comprising repeatedly, preferably periodically, transmitting the frame (2) to the at least one terminal device (STA, STA1, STA2) in order to suspend contention-based access of the at least one terminal device (STA, STA1, STA2) to the radio network (1).

14. The method according to any of the preceding claims, using at least one control frame type (21), preferably a trigger frame (22), most preferably a buffer status report poll (23), as the frame (2) for causing the at least one terminal device (STA, STA1, STA2) to suspend contention-based access to the radio network (1).

15. The method according to any of the preceding claims, using different types of control frames (21) as frames for causing the terminal device to suspend contention-based access to the radio network, wherein The first type of control frame (22) includes one or more parameters for configuring a first access configuration (3), and the second type of control frame (22) is devoid of the one or more parameters for configuring the first access configuration (3).

16. The method according to any of the preceding claims, wherein contention-based access is attempted by the access node (AP) after transmitting the frame (2).

17. The method according to any of the preceding claims, receiving by the access node (AP) a buffer status report from the at least one terminal device (STA, STA1, STA2), the buffer status report for example comprising an acknowledgement.

18. The method according to any of the preceding claims, allocating, by the access node (AP), to the at least one terminal device (STA, STA1, STA2), transmission resources for transmission from the terminal device (STA, STA1, STA2) to the access node (AP), preferably based on the received at least one buffer status report.

19. An access node (AP) of a radio network (1), preferably comprising a processor and a memory, operative to perform the steps of the method according to any one of the preceding claims.

20. A method of controlling access to a radio network (1), the method comprising: A frame (2) is received by a terminal device (STA, STA1, STA2) from an access node (AP) of the radio network (1), wherein the frame (2) causes the terminal device (STA, STA1, STA2) to suspend contention-based access to the radio network (1).

21. A terminal device (STA, STA1, STA2) of a radio network (1), preferably comprising a processor and a memory, operative to perform the steps of the method according to the preceding claim.

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