Communication device, access point, and communication method

Abstract

The present invention provides a communication apparatus, an access point and a communication method. To avoid blocking a node AC queue in a degraded MU EDCA mode due to periodic OFDMA transmission of data from another AC queue in a resource unit provided by the AP, the present invention proposes using a dedicated HEMU EDCA Timer for each AC queue so that the AC queue can exit the degraded MU EDCA mode independently of other AC queues. In this regard, upon successful transmission of data stored by two or more traffic queues in each of one or more accessed resource units provided by the AP within one or more transmission opportunities, the node sets each traffic queue that transmitted in the accessed resource unit into the degraded MU EDCA mode and for a predetermined duration of degradation that is derived from a respective timer associated with the transmitting traffic queue counting down. Then, upon expiration of any timer, the node switches the associated traffic queue back to the legacy EDCA mode.

Description

[0001] (This application is a divisional application of the application filed on October 16, 2017, with application number 201780065054.8 and invention title "Enhanced Management of AC in Multi-User EDCA Transmission Mode in Wireless Network".) Technical Field

[0002] This invention generally relates to communication networks, and more specifically to communication networks that transmit data by contention for channel access to nodes and by providing secondary access to these nodes to sub-channels (or resource units) segmented by the transmission opportunities (TXOPs) granted to access points.

[0003] This invention can be applied in wireless communication networks, particularly in 802.11ax networks, thereby providing nodes with access to 802.11ax composite channels and / or OFDMA resource elements that form, for example, 802.11ax composite channels for granting access points, and enabling uplink communication. Background Technology

[0004] The IEEE 802.11 MAC standard defines how wireless local area networks (WLANs) must operate at both the physical and media access control (MAC) layers. Typically, the 802.11 MAC (Media Access Control) operating mode implements the well-known Distributed Coordination Function (DCF), which relies on a contention-based mechanism based on the so-called Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) technique.

[0005] The 802.11 Media Access Protocol standard or operating mode primarily involves the management of communication nodes that are waiting for the wireless medium to become idle in order to attempt to access it.

[0006] The network operating mode defined by the IEEE 802.11ac standard provides very high throughput (VHT) by moving from the 2.4 GHz band, which is considered to be highly susceptible to interference, to the 5 GHz band. This enables the use of a wider frequency contiguous channel of 80 MHz, in which two channels of these frequency contiguous channels can be optionally combined to obtain a 160 MHz channel as the operating frequency band of the wireless network.

[0007] The 802.11ac standard also modifies control frames such as Request to Send (RTS) and Allow to Send (CTS) frames to allow composite channels with different predefined bandwidths of 20MHz, 40MHz, or 80MHz, where these composite channels consist of one or more consecutive communication channels within the operating frequency band. A 160MHz composite channel can be a combination of two 80MHz composite channels within the 160MHz operating frequency band. The control frame specifies the channel width (bandwidth) of the target composite channel.

[0008] Therefore, a composite channel includes a primary channel for a given node to perform an EDCA backoff procedure to access the medium, and at least one secondary channel, each for example, 20 MHz.

[0009] EDCA (Enhanced Distributed Channel Access) defines service categories and four corresponding access categories that allow high-priority services to be processed differently from low-priority services.

[0010] The implementation of EDCA in a node can be achieved using multiple service queues (known as "access categories") for serving data services with different priorities, where each service queue is associated with a corresponding queue backoff value. The queue backoff value is calculated based on individual queue contention parameters (e.g., EDCA parameters) and is used to compete for access to the communication channel in order to transmit the data stored in the service queue.

[0011] Traditional EDCA parameters include CW for each service queue. min CW max And AIFSN, of which CW min and CW max It represents the lower and upper boundaries of the selection range of the EDCA contention window CW for a given traffic queue. AIFSN represents the number of arbitration inter-frame gaps and defines the number of time slots (typically 9 μs) that a node must listen for as idle media before decrementing the queue backoff value associated with the traffic queue under consideration, excluding the DIFS interval (which defines the sum of AIFS time periods).

[0012] EDCA parameters can be defined in beacon frames sent by specific nodes in the network to broadcast network information.

[0013] The contention window (CW) and queue backoff value are EDCA variables.

[0014] The traditional EDCA backoff process involves a node selecting a queue backoff value for the service queue from each contention window (CW), and then decrementing that queue backoff value when the medium is idle after the AIFS period. Once the backoff value reaches zero, the node is allowed to access the medium.

[0015] Therefore, EDCA queue backoff values ​​or counters serve two purposes. First, they drive nodes to access the medium efficiently by reducing the risk of collisions. Second, they manage Quality of Service (QoS) by reflecting the aging of data contained in the service queue (the older the data, the lower the backoff value) and thus providing different priorities to the service queue through different values ​​of EDCA parameters (especially the AIFSN parameter that delays the start of the decrease in EDCA queue backoff values).

[0016] Because of the EDCA backoff process, nodes can access the communication network using a contention-based access mechanism based on queue contention parameters (usually based on a calculated queue backoff counter or value).

[0017] Communication nodes use the primary channel to listen for channel availability and can use secondary channels to extend the primary channel to form a composite channel. The primary channel can also be used alone.

[0018] Given the tree-like decomposition of the operating frequency band into the basic 20MHz channel, some auxiliary channels are named third-level channels or fourth-level channels.

[0019] In 802.11ac, all transmissions, and therefore possible composite channels, include a primary channel. This is because nodes perform full Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) and Network Allocation Vector (NAV) tracking only on the primary channel. Other channels are assigned as secondary channels, where nodes only have the capability of CCA (Free Channel Assessment), i.e., detecting the free or busy status / condition of the secondary channel.

[0020] The problem with using composite channels as defined in 802.11n or 802.11ac (or 802.11ax) is that nodes compatible with composite channel use (i.e., 802.11n and 802.11ac compatible nodes or "HT nodes" (representing high-throughput nodes)) must coexist in the same wireless network with traditional nodes that cannot use composite channels but rely solely on traditional 20MHz channels (i.e., non-HT nodes that are only compatible with, for example, 802.11a / b / g) and therefore must share the same 20MHz channels.

[0021] To address this issue, the 802.11n, 802.11ac, and 802.11ax standards provide the possibility of replicating control frames (e.g., RTS / CTS frames, CTS-to-Self frames, or ACK frames used to confirm the correct or incorrect reception of transmitted data) on each 20MHz channel in the legacy 802.11a format (referred to as "non-HT"), thereby establishing protection for the requested TXOP across the entire composite channel.

[0022] This applies to any legacy 802.11a node that uses any 20MHz channel included in the composite channel to learn about ongoing communication on the 20MHz channel. As a result, it prevents legacy nodes from initiating new transmissions before the current composite channel TXOP granted to the 802.11n / ac / ax node ends.

[0023] As originally proposed by 802.11n, it provides a copy of the traditional 802.11a or "non-HT" transmission, so that two identical 20MHz non-HT control frames can be transmitted simultaneously on both the primary and secondary channels that constitute the composite channel used.

[0024] This method has been extended for 802.11ac to allow replication on channels constituting an 80MHz or 160MHz composite channel. In the remainder of this document, “replicated non-HT frame” or “replicated non-HT control frame” or “replicated control frame” means that the node device replicates a given control frame’s conventional or “non-HT” transmission on a secondary 20MHz channel within its (40MHz, 80MHz, or 160MHz) operating band.

[0025] In practice, to request a new TXOP on a composite channel (equal to or greater than 40MHz), as described above, the 802.11n / ac node performs an EDCA backoff process on the 20MHz primary channel. In parallel, the 802.11n / ac node performs channel listening mechanisms such as Clear Channel Assessment (CCA) signal detection on the secondary channel to detect secondary channels that are idle (channel state / condition is "idle") during the PIFS interval before the start of a new TXOP (i.e., before any queue backoff counter expires).

[0026] Recently, the Institute of Electrical and Electronics Engineers (IEEE) officially approved the 802.11ax task group as the successor to 802.11ac. The main goal of the 802.11ax task group involves attempting to improve the data speed of wireless communication devices used in densely deployed scenarios.

[0027] Recent developments in the 802.11ax standard attempt to optimize the use of composite channels through multiple nodes in wireless networks with access points (APs). In practice, typical content involves significant data volumes, such as those related to real-time interactive high-definition audiovisual content. Furthermore, it is well known that the performance of the CSMA / CA protocol used in the IEEE 802.11 standard degrades rapidly with increasing node numbers and traffic volume (i.e., in dense WLAN scenarios).

[0028] In this context, multi-user (MU) transmission is considered to allow multiple simultaneous transmissions relative to different users in both the downlink (DL) and uplink / downlink (UL) directions relative to the AP, as well as during the transmission opportunity granted to the AP. In the uplink, MU transmission can be used to reduce the probability of collisions by allowing multiple non-AP stations or nodes to transmit simultaneously.

[0029] To enable such multi-user transmission in practice, a proposed approach is to divide the licensed communication channel into sub-channels (also known as resource units (RUs)). Multiple users (non-AP stations / nodes) share these sub-channels in the frequency domain, for example, based on Orthogonal Frequency Division Multiple Access (OFDMA) technology. Each RU can be defined by multiple tones, with an 80MHz channel containing up to 996 available tones.

[0030] OFDMA is a multi-user variant of OFDM that emerged as a new key technology to improve the efficiency of advanced architecture-based wireless networks. OFDMA combines OFDM at the physical layer with Frequency Division Multiple Access (FDMA) at the MAC layer, allowing different subcarriers to be assigned to different stations / nodes to improve concurrency. Adjacent subcarriers often experience the same channel conditions and are therefore grouped into subchannels: OFDMA subchannels or RUs are thus collections of subcarriers.

[0031] As currently envisioned, the granularity of this OFDMA subchannel is finer than the original 20MHz channel bandwidth. Typically, a 2MHz or 5MHz subchannel can be considered as the minimum width, thus defining, for example, nine subchannels or resource units within a single 20MHz channel.

[0032] OFDMA's multi-user feature allows an AP to assign or provide different RUs to different non-AP stations / nodes to increase contention. This can help reduce contention and collisions within an 802.11 network.

[0033] In contrast to the downlink OFDMA where the AP can send multiple data directly to multiple stations (supported by specific indications within the PLCP header), the AP employs a triggering mechanism to trigger multi-user uplink (MU UL) OFDMA communication from each node.

[0034] In order to support multi-user uplinks (i.e., uplink transmissions to 802.11ax access points (APs) during preemptive TXOPs), 802.11ax APs must provide signaling information for legacy nodes (non-802.11ax nodes) to set their NAVs and for 802.11ax nodes to determine the allocation of resource units (RUs) provided by the AP.

[0035] The 802.11ax standard defines trigger frames (TFs) that are sent by an AP to an 802.11ax node to trigger multi-user uplink communication.

[0036] The IEEE 802.11-15 / 0365 standard proposes that an Access Point (AP) sends a "trigger" frame (TF) to request the transmission of uplink (UL) multi-user (OFDMA) PPDUs from multiple nodes. The TF defines the resource units provided by the AP to these nodes. In response, the nodes send UL MU (OFDMA) PPDUs as an immediate response to the trigger frame. All transmitters can transmit data simultaneously, but use a set of disjoint RUs (i.e., frequencies in the OFDMA scheme) to achieve less interference-prone transmission.

[0037] The bandwidth or width of the target composite channel is notified in the TF frame, which means adding a value of 20MHz, 40MHz, 80MHz, or 160MHz. Where appropriate, the TF frame is transmitted via the 20MHz master channel and copied (repeated) on each of the other 20MHz channels, thus forming the target composite channel. As described above regarding the copying of the control frame, it can be expected that the nearby traditional nodes (non-HT or 802.11ac nodes) receiving the TF on the master channel will then set their NAV to the value specified in the TF. This prevents these traditional nodes from accessing channels in the target composite channel during TXOP.

[0038] Resource Units (RUs) can be reserved for specific nodes. In this case, the Access Point (AP) indicates the node that has reserved the RU in the Transfer Function (TF). This RU is called a scheduled RU. The indicated node does not need to contend for access to the scheduled RU reserved for that node.

[0039] The type of data that a node is allowed to send in a scheduled RU can be specified by the AP in the TF. For example, the TF includes a 2-bit "Preferred AC" field, where the AP indicates one of the four EDCA service queues. Alternatively, the AP can allow the scheduled RU to be open to any type of data. To activate or deactivate "Preferred AC", the TF includes another 1-bit field, namely "AC Preferred Level".

[0040] To improve system efficiency regarding unmanaged traffic to the AP (e.g., uplink management frames from associated nodes, non-associated nodes intending to reach the AP, or simply unmanaged data traffic), the AP can propose resource elements (RUs) to 802.11ax nodes through contention-based access. In other words, a resource element (RU) can be randomly accessed by more than one node (from a group of nodes registered to the AP). This RU is called a random RU and is thus indicated in the TF (Transmission Function). The random RU can serve as the basis for contention between nodes intending to access the communication medium to send data.

[0041] A typical random resource selection process is defined in the document IEEE 802.11-15 / 1105. According to this process, each 802.11ax node uses a RU contention parameter, including a RU backoff value, to maintain a dedicated backoff engine, referred to as OFDMA or RU (short for Resource Unit) backoff engine, to compete for access to one of the random RUs. Once its OFDMA or RU backoff value reaches 0 (the OFDMA or RU backoff value is reduced, for example, at each new TF-R frame by the number of random RUs as defined herein), the node becomes eligible for RU access and thus randomly selects one RU from all the random RUs defined in the received trigger frame. The node then uses the selected RU to transmit data from at least one traffic queue in the traffic queue.

[0042] As can be easily seen from the above, multi-user uplink media access schemes (or OFDMA or RU access schemes) allow for a reduction in the number of collisions resulting from simultaneous media access attempts, while also reducing the overhead associated with media access (because the cost of media access is shared among several nodes). Therefore, OFDMA or RU access schemes appear to be more efficient than traditional EDCA contention-based media access schemes (in high-density 802.11 cell environments) (in terms of media usage).

[0043] Although OFDMA or RU access schemes may seem more efficient, EDCA access schemes must also survive and therefore coexist with OFDMA or RU access schemes.

[0044] This is primarily due to the presence of legacy 802.11 nodes, which must still have access to the media without being aware of OFDMA or RU access schemes. Furthermore, global fairness regarding media access must be ensured.

[0045] 802.11ax nodes should also have the opportunity to access the media through traditional EDCA contention-based media access, for example, to send data to another node (i.e., for a different service than the uplink service to the AP), which is even more necessary.

[0046] Therefore, the EDCA and OFDMA / RU access schemes, the two media access schemes, must coexist.

[0047] This coexistence has drawbacks.

[0048] For example, 802.11ax nodes and traditional nodes using the EDCA access scheme have the same media access probability. However, 802.11ax nodes using the MU uplink, OFDMA, or RU access schemes have additional media access opportunities.

[0049] This results in media access not being entirely fair between 802.11ax nodes and legacy nodes.

[0050] To restore some degree of fairness among nodes, a solution is proposed as follows: when data is successfully transmitted via the accessed resource unit (i.e., via UL OFDMA transmission), the current value of at least one queue contention parameter is modified to a penalty or degradation value to reduce the probability of a node contention for access to the communication channel via (EDCA). For example, the penalty or degradation value is more restrictive than the original (or conventional) value.

[0051] For example, the document IEEE 802.11-16 / 1180, titled "Proposed text changes for MU EDCA parameters," proposes that when successfully transmitting data in a resource unit (RU) reserved by an AP (MU UL OFDMA), the node is set in MU EDCA mode for a predetermined duration obtained by counting down using a timer (hereinafter referred to as HEMUEDCATimer, an abbreviation for High Efficiency Multi-User EDCA Timer)). The EDCA parameters are set to values ​​different from the traditional values ​​used in conventional EDCA modes, referred to as MU EDCA parameter values ​​or MU values. The MU parameter values ​​are set to more restrictive values ​​than the traditional values: more restrictive EDCA parameter values ​​mean that the probability of a node accessing the communication channel via the EDCA access scheme using the MU value is reduced compared to accessing using the traditional value.

[0052] In other words, when a node uses a scheduled RU assigned to the node by the AP to transmit some data from one or more traffic queues, the node should immediately modify the EDCA parameter associated with the transmission traffic queue (hereinafter referred to as "degraded", "penalized", or "blocked" traffic queue). This EDCA parameter has some special, more restrictive ("MU" or "degraded") values ​​that can be provided by the AP in the dedicated information element of the beacon frame. The EDCA parameter also includes the value that the node wants to use for its HEMUEDCATimer.

[0053] Therefore, it can be noted that the AP can send nodes more restrictive values ​​to modify the current values ​​of their EDCA parameters to MU values ​​when the nodes successfully transmit data via the accessed resource unit. This is also to reduce the probability of nodes accessing the communication channel via the EDCA access scheme.

[0054] Additionally, the AP can determine more restrictive values ​​based on the history of data received from the node (e.g., via the RU).

[0055] The disclosed method suggests increasing the AIFSN value only for each transport queue, while maintaining CW. min and CW max Unchanged. With the corresponding AIFS period lengthened, especially in high-density environments where the medium has not been idle for extended periods, this prevents (or at least substantially delays) the decrementing of queue backoff values ​​or counters in the MU EDCA mode when the medium is detected as idle. Using the EDCA access scheme, new accesses to the medium are statistically significantly reduced, or even eliminated altogether.

[0056] When switching to MU EDCA mode, the node begins its HEMUEDCATimer countdown. HEMUEDCATimer is reinitialized each time the node successfully (MUUL OFDMA) transmits data in a newly reserved RU. It is recommended that HEMUEDCATimer be initialized to a high value (e.g., tens of milliseconds) to accommodate several new opportunities for MU UL transmissions.

[0057] When HEMUEDCATimer expires, the service queue under MU EDCA mode switches back to traditional EDCA mode with traditional EDCA parameters, thereby causing the queue to exit MU EDCA mode.

[0058] Therefore, this dual-mode (traditional EDCA mode and MU EDCA mode) mechanism promotes the use of the MU UL mechanism by reducing the probability of accessing the medium through the EDCA mechanism via the MU UL transmission node.

[0059] The HEMUEDCATimer mechanism, which reinitializes HEMUEDCATimer whenever a node successfully transmits new data in a reserved RU that has been visited, means that the node remains in the MUEDCA state as long as the AP provides (scheduled or random) RUs to it.

[0060] This method has the main drawbacks as explained now.

[0061] If a node transmits data from two or more service queues within one or more resource units provided by the AP (e.g., if a dedicated service queue becomes empty, the node selects other data to send from a service queue with higher priority), then the two or more service queues become MUs and a more restrictive EDCA mode. Since, for example, the AIFSNs of these service queues are very restrictive, access to the medium via the EDCA access scheme is primarily prevented.

[0062] The following situation may occur: AP periodically provides the node (in this situation) with resource units indicating the preferred service queue for selecting data.

[0063] As long as the polling for the preferred service queue continues, the node clears the corresponding service queue when accessing the provided resource unit, while keeping all two or more service queues in MU EDCA mode. This means that other service queues remain locked in MU and the more restrictive EDCA mode and cannot be cleared via access media.

[0064] As a result, the QoS in the network is severely degraded. Summary of the Invention

[0065] The present invention seeks to overcome the above-mentioned limitations. In particular, the present invention seeks to overcome the loss of QoS processing caused by the introduction of MU UL OFDMA transmission.

[0066] The inventors have noted that locking other traffic queues in MU contention modes, such as the MU EDCA mode described above, is caused by the following: whenever data from the same preferred traffic queue is transmitted (periodically) in a resource unit, HEMUEDCATimer is reinitialized. Therefore, the unicity of HEMUEDCATimer managing all traffic queues simultaneously in MU contention mode is substantially detrimental to QoS.

[0067] Therefore, the present invention aims to restore some QoS by disrupting the uniqueness of HEMUEDCATimer.

[0068] In this context, the present invention provides a communication method in a communication network comprising multiple nodes, at least one node comprising multiple service queues for serving data services according to different priorities, each service queue being associated with a corresponding queue backoff value, the corresponding queue backoff value being calculated based on corresponding queue contention parameters having conventional values ​​in a conventional contention mode, and used to compete for access to a communication channel to transmit data stored in that service queue.

[0069] The communication method includes:

[0070] At the node

[0071] Within one or more transmission opportunities granted to another node on the communication channel, data stored in two or more service queues is transmitted in one or more accessed resource units provided by the other node.

[0072] When transmitting data in each accessed resource unit, each transmission service queue (i.e., transmission in the accessed unit) is set to a MU contention mode different from the conventional contention mode and the corresponding timer associated with the transmission service queue is continuously counted down for a predetermined duration, wherein the corresponding queue contention parameter of the MU contention mode is set to a MU value different from the conventional value; and when any timer expires, the associated (degraded) service queue is switched back to the conventional contention mode, in which the corresponding queue contention parameter is set back to the conventional value.

[0073] Therefore, this invention proposes to use a dedicated HEMUEDCATimer for each AC queue so that each AC queue can exit MU contention mode independently of other AC queues.

[0074] Timers can be implemented using both hardware and software.

[0075] Therefore, fairness between the two competition modes was restored for 802.11ax nodes.

[0076] A MU value that differs from the traditional value of the business queue means that the MU value of at least one competing parameter is different from the traditional value, regardless of whether the MU value of other competing parameters is equal to or different from the traditional value.

[0077] Accordingly, the present invention also relates to a communication device in a communication network, the communication network comprising multiple nodes, the communication device comprising:

[0078] Multiple service queues are used to serve data services according to different priorities. Each service queue is associated with a corresponding queue backoff value, which is calculated based on the corresponding queue contention parameters with traditional values ​​in the traditional contention mode, and is used to compete for access to the communication channel to transmit the data stored in that service queue.

[0079] Multiple timers, each associated with one of the service queues; and

[0080] At least one microprocessor is configured to perform the following steps:

[0081] Within one or more transmission opportunities granted to another node on the communication channel, data stored in two or more service queues is transmitted in one or more accessed resource units provided by the other node.

[0082] When transmitting data in each accessed resource unit, each transmission service queue is set to a MU contention mode different from the conventional contention mode and continuously counted down by an associated timer for a predetermined duration, wherein the corresponding queue contention parameter of the MU contention mode is set to a MU value different from the conventional value; and

[0083] When any timer expires, the associated (degraded) business queue is switched back to the traditional competition mode, in which the corresponding queue competition parameters are set back to the traditional values.

[0084] This device node has the same advantages as the method defined above.

[0085] Optional features of the invention are defined in the appended claims. Some of these features are described below with reference to other methods, while these features can be converted into system features specific to any device node according to the invention.

[0086] In this embodiment, the predetermined (preferred degraded) durations for initializing the timers associated with the two corresponding service queues are different from each other. This configuration improves QoS management.

[0087] In other embodiments, the predetermined duration for initializing the timer associated with the corresponding service queue is calculated based on a common initialization value received from the other node and adjustment parameters specific to that corresponding service queue. Thus, the combination of the common initialization value and the AC queue adjustment parameters makes it easy to adjust the duration for which each AC queue should remain in MU contention mode. Therefore, this configuration also improves QoS management.

[0088] In a variation, the predetermined duration used to initialize the timer associated with the corresponding service queue is set to a corresponding initialization value received directly from the other node. In other words, other nodes, such as APs, directly drive the AC queues to remain in MU contention mode for a specific duration.

[0089] This enables efficient QoS management, especially because other nodes, such as APs, can have a holistic view of the network (e.g., collision-related statistics and node counts). This makes adjusting priority AC queues easier, resulting in a more efficient network.

[0090] In some embodiments, the timer associated with the corresponding service queue is reinitialized to a predetermined duration whenever data from the associated service queue is transmitted in an accessed resource unit provided by the other node within any subsequent transmission opportunity granted to the other node on the communication channel.

[0091] This means that the timer used by the AC queue will only expire if no data from the AC queue is transmitted in any resource unit provided by another node within the initially initialized predetermined duration of the timer. Otherwise, the timer will be reinitialized.

[0092] As a result, a service queue can exit MU contention mode by restoring the corresponding queue contention parameters to their traditional values ​​only if no OFDMA transmission of data from the considered AC queue occurs within the specified duration.

[0093] In an embodiment, the method further includes: at the node, using queue contention parameters in the MU contention mode to compete for access to the communication channel. This means that the MU contention mode follows the same contention scheme as conventional contention modes (e.g., conventional EDCA), but with MU (preferably degraded (i.e., more restrictive)) contention parameters to penalize the AC queues polled by the AP for transmission in the RU.

[0094] In an embodiment, the method further includes: at the node, periodically receiving beacon frames from the access point, each beacon frame broadcasting network information related to the communication network to the plurality of nodes.

[0095] Wherein, at least one received beacon frame includes the conventional value of the queue contention parameter of the plurality of service queues and the MU value, as well as at least one initialization value for initializing the timer to the predetermined duration associated with the service queue.

[0096] In this embodiment, one or more of the transmission service queues are only set to the MU contention mode when data is successfully transmitted in the corresponding accessed resource unit. This configuration ensures fairness. In fact, in the concept of contention mode switching, the MU mode should only be implemented (here via RU) to compensate for the existence of other transmission opportunities, meaning that data has been successfully transmitted.

[0097] In some embodiments, the MU value includes the degraded arbitration inter-frame gap number, or degraded AIFSN, compared to the conventional value. This configuration is easy to implement to directly reduce the chances of a particular service queue accessing the medium via EDCA (reducing this chance to a desired level).

[0098] Specifically, each queue backoff value can initially be selected from the corresponding contention window, and as time passes, the queue backoff value is reduced by the node so that access to the communication channel is achieved when it reaches zero.

[0099] The MU value of the queue contention parameter may include the same lower bound CW as the conventional value. minand / or upper boundary CW max The lower boundary CW min and the upper boundary CW max These two define the range of choices for selecting the size of the competing window.

[0100] This configuration simplifies entering and exiting MU contention mode (MU EDCA mode) because it keeps the contention window unchanged. However, variations can be considered where there are different boundaries between the conventional value and the MU value.

[0101] In some embodiments, the method further includes: at the node, when accessing resource units provided by the other node within a subsequent transmission opportunity granted to the other node,

[0102] Based on the associated current queue backoff value, data is selected from the service queues of both the MU contention mode and the traditional contention mode.

[0103] The selected data is transmitted within the accessed resource unit within the new transmission opportunity.

[0104] Therefore, fair management of QoS is maintained in implementing this invention.

[0105] Based on specific characteristics, data selection includes choosing data from the business queues associated with the lowest current queue backoff value. This maintains a behavior similar to EDCA for the AC queue.

[0106] In an alternative embodiment, the method further includes: at the node, when accessing resource units provided by the other node within a subsequent transmission opportunity granted to the other node,

[0107] Select data from the preferred service queue indicated by the other node, and

[0108] The selected data is transmitted within the accessed resource unit within the new transmission opportunity.

[0109] Based on specific characteristics, the preferred service queue indication is included in a trigger frame received from another node, which reserves the transmission opportunity granted to the other node on the communication channel and defines a resource unit (RU), thereby forming a communication channel that includes the accessed resource unit.

[0110] This method allows another node (typically an AP) to drive QoS management.

[0111] In some embodiments of the invention, the accessed resource unit through which the data is transmitted is a random resource unit, wherein access to the resource unit is performed by competition using a separate RU contention parameter (separate from the queue contention parameter described above).

[0112] In other embodiments, the accessed resource unit through which the data is transmitted is a scheduled resource unit, wherein the scheduled resource is assigned to the node by another node.

[0113] Of course, some nodes can access the scheduled RU, while other nodes can access the random RU at the same time, which allows for a variety of nodes in MU contention mode at the same time (for use by one or more AC queues).

[0114] In some embodiments, the other node is an access point to which the node is registered in the communication network. This provision advantageously utilizes the central location of the access point.

[0115] From the perspective of the access point, this invention proposes a communication method in a communication network, the communication network including an access point and multiple nodes. Each node includes multiple service queues for serving data services according to different priorities. Each service queue is associated with a corresponding queue backoff value, which is calculated based on corresponding queue contention parameters with traditional values ​​in a conventional contention mode, and is used to compete for access to the communication channel to transmit the data stored in the service queue.

[0116] The communication method includes:

[0117] At the access point,

[0118] Access the communication channel to send a trigger frame, the trigger frame reserving transmission opportunities on the communication channel and defining a resource unit (RU) used by the node to transmit data to the access point for forming the communication channel; and

[0119] The node is sent a set of traditional values ​​for the queue contention parameters and a set of MU values ​​for the queue contention parameters that are different from the set of traditional values, as well as a set of initialization values ​​for the node timer associated with the service queue, to configure the node when two or more service queues of each node switch between MU contention mode and traditional contention mode, in which the corresponding queue contention parameter is set to the MU value, the MU contention mode being initialized based on the associated initialization value and maintained for a predetermined duration obtained by counting down from the associated timer, wherein the corresponding queue contention parameter in the MU contention mode is set to the corresponding MU value.

[0120] Accordingly, an access point in a communication network further includes multiple nodes, each node comprising multiple service queues for serving data services according to different priorities. Each service queue is associated with a corresponding queue backoff value, which is calculated based on corresponding queue contention parameters having conventional values ​​in a conventional contention mode, and is used to compete for access to the communication channel to transmit the data stored in that service queue.

[0121] The access point includes at least one microprocessor, which is configured to perform the following steps:

[0122] Access the communication channel to send a trigger frame, the trigger frame reserving transmission opportunities on the communication channel and defining a resource unit (RU) used by the node to transmit data to the access point for forming the communication channel; and

[0123] The node is sent a set of conventional values ​​for the queue contention parameters and a set of MU values ​​for the queue contention parameters that are different from the set of conventional values, as well as a set of initialization values ​​for the node timer associated with the service queue, to configure the node when two or more service queues of each node switch between conventional contention mode and MU contention mode, in which the corresponding queue contention parameters are set to conventional values, and the MU contention mode is to be maintained for a predetermined duration based on the associated initialization values ​​and counted down by the associated timer, wherein the corresponding queue contention parameters in the MU contention mode are set to the corresponding MU values.

[0124] Therefore, access points can efficiently control fairness in the network. In fact, by using MU values ​​and timer values, access points can drive nodes to adjust their EDCA access schemes in a MU contention mode that differs from the conventional traditional mode.

[0125] Preferably, the traditional value, the MU value, and the timer value can be evaluated based on the history of past transmissions from the node (especially in the RUs (random or scheduled RUs) provided by the access point).

[0126] Optional features of the invention are defined in the appended claims. Some of these features are described below with reference to other methods, while these features can be converted into system features specific to any device node according to the invention.

[0127] In some embodiments, a set of conventional values, a set of MU values, and a set of initialization values ​​are transmitted within one or more beacon frames that are periodically transmitted by the access point to broadcast network information related to the communication network to multiple nodes.

[0128] In other embodiments, a set of conventional values ​​and a set of MU values ​​differ due to different arbitration inter-frame gap numbers, i.e., AIFSNs.

[0129] Specifically, initially, the queue backoff value of each node can be selected from the corresponding contention window. As time passes, the queue backoff value is reduced by passing through the node so that the communication channel can be accessed when it reaches zero.

[0130] The set of conventional values ​​and the set of MU values ​​include the same lower boundary CW. min and / or upper boundary CW max The lower boundary CW min and the upper boundary CW max Together, these two define the range of choices for the size of the competition window associated with the business queue.

[0131] Another aspect of the invention relates to a non-transitory computer-readable medium that stores a program, which, when executed by a microprocessor or computer system in the device, causes the device to perform any of the methods defined above.

[0132] Non-transitory computer-readable media may have features and advantages similar to those stated above and below in relation to the methods and apparatus.

[0133] Another aspect of the invention relates to something generally as shown herein with reference to the accompanying drawings. Figure 5b ,or Figure 11 ,or Figure 11 and 12 ,or Figure 11 , 12 and 14b, or Figure 11 , 12 The methods described in 14c and shown in these figures.

[0134] At least a portion of the method according to the invention can be implemented by a computer. Therefore, the invention can take the form of a fully hardware embodiment, a fully software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects generally referred to herein as a “circuit,” “module,” or “system.” Furthermore, the invention can take the form of a computer program product, wherein the computer program product can take the form of a computer program product embodied in any tangible medium embodying computer-usable program code.

[0135] Because this invention can be implemented in software, it can be embodied as computer-readable code 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 storage devices. Transient carrier media may include signals such as electrical signals, electronic signals, optical signals, acoustic signals, magnetic signals, or electromagnetic signals (e.g., microwave or RF signals). Attached Figure Description

[0136] Other advantages of the present invention will become apparent to those skilled in the art upon examination of the accompanying drawings and detailed description. Embodiments of the invention will now be described by way of example only with reference to the following drawings.

[0137] Figure 1 This diagram illustrates a typical wireless communication system that can implement embodiments of the present invention;

[0138] Figure 2a , 2b The IEEE 802.11e EDCA is shown, which involves access categories;

[0139] Figure 2c This shows an example of the values ​​for the downgraded EDCA parameter set;

[0140] Figure 3a This demonstrates the 802.11ac mechanism for the backoff counter countdown;

[0141] Figure 3b An example showing the mapping between the eight priorities of a business class and the four EDCA ACs;

[0142] Figure 4a This demonstrates 802.11ac channel allocations supporting channel bandwidths of 20MHz, 40MHz, 80MHz, or 160MHz known in the prior art;

[0143] Figure 4b An example of an 802.11ax uplink OFDMA transmission scheme is shown, in which the AP issues a trigger frame to reserve a transmission opportunity for an OFDMA subchannel (resource element) on an 80MHz channel known in the art.

[0144] Figure 5a This shows the state of the transport queues switching in MU EDCA mode as known in the prior art;

[0145] Figure 5b This illustrates the state of the transmission service queue switched in MU EDCA mode according to an embodiment of the present invention;

[0146] Figure 6 A schematic representation of a communication device or station according to an embodiment of the present invention is shown;

[0147] Figure 7 A schematic representation of a wireless communication device according to an embodiment of the present invention is shown;

[0148] Figure 8 A typical transport block of a communication node according to an embodiment of the present invention is shown;

[0149] Figure 9 The flowchart illustrates the main steps performed by the MAC layer of a node when new data to be transmitted is received, as described in an embodiment of the present invention.

[0150] Figure 10 The flowchart illustrates the steps for accessing media based on the EDCA media access scheme in two scenarios, using non-degraded EDCA parameters or using degraded EDCA parameters, according to embodiments of the present invention.

[0151] Figure 11 The flowchart illustrates the steps of accessing a resource unit based on an RU or OFDMA access scheme when a trigger frame defining an RU is received, according to an embodiment of the present invention.

[0152] Figure 12 A flowchart is used to illustrate node management for switching back to non-degradation mode according to an embodiment of the present invention;

[0153] Figure 13 This shows the structure of a trigger frame as defined in the 802.11ax standard;

[0154] Figure 14a This illustrates the structure of the standardized information elements used to describe the parameters of EDCA in a beacon frame; and

[0155] Figure 14b and 14c An exemplary structure of a dedicated information element for transmitting downgraded EDCA parameter values, and a HEMUEDCATimer value, are shown according to an embodiment of the present invention. Detailed Implementation

[0156] The invention will now be described using specific, non-limiting exemplary embodiments and with reference to the accompanying drawings.

[0157] Figure 1 A communication system is illustrated, in which multiple communication nodes (or stations) 101–107 exchange data frames via a wireless transmission channel 100 of a wireless local area network (WLAN) under the management of a central station or an access point (AP) 110 to which nodes have registered. The wireless transmission channel 100 is defined by an operating frequency band, which consists of a single channel or multiple channels forming a composite channel.

[0158] Accessing the shared wireless medium to send data frames is based on CSMA / CA technology, which listens for carriers and avoids collisions by separating concurrent transmissions in space and time.

[0159] Carrier sensing in CSMA / CA is performed using both physical and virtual mechanisms. Virtual carrier sensing is achieved by transmitting control frames before transmitting data frames to reserve the medium.

[0160] Next, before transmitting data frames, the source node or transmission node of the AP first attempts to listen to the medium that has been idle for at least one DIFS (representing DCF inter-frame gap) period through physical mechanisms.

[0161] However, if the shared wireless medium is detected to be busy during the DIFS period, the source node continues to wait until the wireless medium becomes idle.

[0162] To access the medium, node startup is designed to use a countdown backoff counter that expires after several time slots randomly selected within a so-called contention window [0, CW], where CW is an integer. This backoff mechanism or process (also known as a channel access scheme) forms the basis of a collision avoidance mechanism that delays transmission time by random intervals, thereby reducing the probability of collisions on a shared channel. After the backoff period (i.e., when the backoff counter reaches zero), the source node can transmit data or control frames while the medium is idle.

[0163] One problem with wireless data communication is that the source node cannot listen while transmitting, thus preventing it from detecting data corruption caused by channel fading, interference, or collisions. The source node remains unaware of the corruption in the transmitted data frames and continues to transmit frames unnecessarily, wasting access time.

[0164] Therefore, the CSMA / CA collision avoidance mechanism provides a positive acknowledgment (ACK) of the data frame sent by the receiving node when the frame is successfully received, so as to notify the source node that the data frame sent has not been corrupted.

[0165] ACK is transmitted at the end of the reception of a data frame, immediately following a period of time known as the short inter-frame gap (SIFS).

[0166] If the source node does not receive an ACK within the specified ACK timeout, or detects that a different frame has been transmitted on the channel, the source node may infer that the data frame has been lost. In this case, the source node typically reschedules the frame transmission according to the backoff process described above.

[0167] To improve the collision avoidance efficiency of CSMA / CA, a four-way handshake mechanism can be optionally implemented. An implementation is known as RTS / CTS switching as defined in the 802.11 standard.

[0168] RTS / CTS switching involves exchanging control frames during a transmission opportunity known as TXOP in the 802.11 standard before transmitting data frames to preserve the radio medium, thereby protecting data transmission from any further collisions. The four-way CTS / RTS handshake mechanism is well-known and will not be elaborated upon here. For more details, please refer to the standard.

[0169] The RTS / CTS four-way handshake mechanism is highly efficient in terms of system performance, especially for large frames, because it reduces the length of messages involved in contention handling.

[0170] In detail, assuming perfect channel sensing by all communication nodes, a collision can only occur if two (or more) frames are transmitted in the same time slot after the DIFS (Divider-First Frame Facility), or if the backoff counters of two (or more) source nodes reach zero at almost the same time. If the two source nodes use the RTS / CTS mechanism, such a collision can only occur with RTS frames. Fortunately, this collision is detected early by the source nodes before a CTS response is received.

[0171] Quality of Service (QoS) management has been introduced at the node level in such wireless networks through the well-known EDCA mechanism defined in the IEEE 802.11e standard.

[0172] In fact, in the original DCF standard, communication nodes only included one transmission queue / buffer. However, since subsequent data frames could not be transmitted until the transmission / retransmission of the previous frame was complete, the delay in transmitting / retransmitting the previous frame prevented the communication from having QoS.

[0173] Figure 2a and 2b The IEEE 802.11e EDCA mechanism involving access categories is shown to improve Quality of Service (QoS).

[0174] The 802.11e standard relies on a coordination function (known as the Hybrid Coordination Function (HCF)) with two operating modes: Enhanced Distributed Channel Access (EDCA) and HCF Control Channel Access (HCCA).

[0175] EDCA enhances or extends the functionality of the original access DCF method: EDCA is designed to support priority services similar to DiffServ (Differentiated Services), which is a protocol for classifying and controlling network services to prioritize specific types of services.

[0176] EDCA is an important channel access scheme or mechanism in WLANs due to its distributed and easily deployable characteristics. This scheme uses contention parameters to compete for access to at least one communication channel in the communication network, allowing nodes to transmit locally stored data on the accessed channel.

[0177] The aforementioned deficiency of unsatisfactory QoS due to frame retransmission delays has been addressed by utilizing multiple transmission queues / buffers.

[0178] QoS support in EDCA is achieved by introducing four Access Classes (ACs) and thereby four corresponding transport / service queues or buffers (210). Typically, the four ACs are arranged in descending order of priority as follows: Voice (or "AC_VO"), Video (or "AC_VI"), Best-effort (or "AC_BE"), and Backstage (or "AC_BG").

[0179] Of course, another number of business queues can also be considered.

[0180] Each AC has its own service queue / buffer for storing the corresponding data frames to be transmitted over the network. Data frames (i.e., MSDUs) coming from the upper layers of the protocol stack are mapped to one of the four AC queues / buffers and are thus input into the mapped AC buffer.

[0181] Each AC also has its own set of queue contention parameters, which are associated with priority values, thus defining services with higher or lower priorities in the MSDU. Therefore, there are multiple service queues used to serve data services according to different priorities. Queue contention parameters typically include the Control Warrant (CW) for each service queue. min CW max The AIFSN and TXOP_Limit parameters. CW min and CW max This defines the lower and upper boundaries of the selection range for the EDCA contention window (CW) for a given traffic queue. AIFSN represents the Arbitration Inter-Frame Spacing Number and defines the number of time slots (typically 9 μs) that a node must listen for as idle media before decrementing the queue backoff value / counter associated with the considered traffic queue, excluding the DIFS interval (which defines the sum of AIFS time periods). TXOP_Limit defines the maximum size of TXOPs a node can request.

[0182] This means that each AC (and its corresponding buffer) acts as an independent DCF contention entity, including its own queue backoff engine 211. Thus, each queue backoff engine 211 is associated with a traffic queue to use queue contention parameters and set (selected from the CW) a queue backoff value / counter to compete for access to at least one communication channel in order to transmit data stored in the traffic queue on the accessed communication channel.

[0183] The contention window (CW) and queue backoff value / counter are referred to as EDCA variables.

[0184] This causes ACs within the same communication node to compete with each other in order to access the wireless medium and obtain transmission opportunities using, for example, the conventional EDCA access scheme described above.

[0185] By setting different queue backoff parameters between ACs (such as different CWs) min CW max AIFS and different transmission opportunity duration limits (TXOP_Limit, etc.) are used to differentiate services between ACs. This helps in adjusting QoS.

[0186] The following is for reference Figure 3a This illustrates the use of the AIFSN parameter and queue backoff value to access the medium in the EDCA mechanism.

[0187] Figure 2b CW is shown min CW max And the default values ​​for the AIFSN parameter.

[0188] In this table, the typical corresponding values ​​for aCWmin and aCWmax are defined as 15 and 1023, respectively, in the aforementioned standard. Other values ​​can be set by nodes in the network (typically access points) and shared among nodes. This information can be broadcast in beacon frames.

[0189] To determine the delay AIFS[i] between detecting that the medium is idle and the start of the queue backoff value decrement for service queue "i", the node multiplies the value indicated in the AIFSN parameter of service queue "i" (i.e., AIFSN[i]) by the slot duration (typically 9 microseconds) and adds that value to the DIFS duration.

[0190] like Figure 3aAs shown, this causes each service queue to wait for an AIFS[i] period (which includes the DIFS period for delaying access to the medium) before decrementing its associated queue backoff value / counter. The diagram illustrates two AIFS[i] corresponding to two different ACs. It can be seen that a priority service queue begins decrementing its backoff value earlier than other less priority service queues. This process repeats after each new medium access at any node in the network.

[0191] In addition to using a lower average CW, this decreasing delay mechanism makes high-priority traffic in EDCA more likely to be transmitted than low-priority traffic: on average, nodes with high-priority traffic wait less before sending packets than nodes with low-priority traffic.

[0192] Therefore, EDCA queue backoff values ​​or counters serve two purposes. First, they drive nodes to access the medium efficiently by reducing the risk of collisions. Second, they provide quality of service (QoS) management by reflecting the aging of data contained in the service queue (the older the data, the lower the backoff value) and thus providing different priorities to the service queue via different values ​​of EDCA parameters (especially the AIFSN parameter that delays the start of the decrease in EDCA queue backoff values).

[0193] refer to Figure 2a Buffers AC3 and AC2 are typically reserved for real-time applications (e.g., voice AC_VO or video AC_VI transmissions). These buffers have the highest priority and the second-lowest priority, respectively.

[0194] Buffers AC1 and AC0 are reserved for best-effort (AC_BE) and back-end (AC_BG) services, respectively. Buffers AC1 and AC0 have the second-lowest priority and the lowest priority, respectively.

[0195] According to the mapping rules, each data unit (MSDU) arriving at the MAC layer from the upper layer (e.g., the link layer) with priority is mapped to the AC. Figure 3b An example of mapping between eight priority service classes (user priorities according to IEEE 802.1d or UP 0–7) and four ACs is shown. Data frames are then stored in buffers corresponding to the mapped ACs.

[0196] At the end of the backoff process for the service queue (or AC), the MAC controller of the transmission node (hereinafter referred to as...) Figure 7 (See attached figure 704) The data frames from this service queue are transmitted to the physical layer for transmission over the wireless communication network.

[0197] Because ACs operate concurrently when accessing the wireless medium, it is possible for two ACs on the same communication node to simultaneously terminate their backoff. In this case, the MAC controller's virtual conflict handler (212) operates between the conflicting ACs (such as...). Figure 3b (As shown) The AC with the highest priority is selected, and data frames are abandoned from the AC with the lower priority.

[0198] Then, the virtual conflict handler commands the AC with lower priority to start the backoff operation again using an increased CW value.

[0199] The QoS obtained by using these ACs can be notified in the MAC data frame (e.g., in the QoS control field included in the header of the IEEE 802.11e MAC frame).

[0200] To meet the growing demand for faster wireless networks to support bandwidth-intensive applications, 802.11ac aims to deliver greater bandwidth via multi-channel operation. Figure 4a This shows the 802.11ac channel allocation that supports composite channel bandwidths of 20MHz, 40MHz, 80MHz, or 160MHz.

[0201] IEEE 802.11ac introduced support for a limited number of predefined subsets of 20MHz channels to form a dedicated predefined composite channel configuration that can be reserved for data transmission by any 802.11ac node on a wireless network.

[0202] The predefined subsets are shown in the figure, and correspond to channel bandwidths of 20MHz, 40MHz, 80MHz, and 160MHz, compared to the 20MHz and 40MHz supported only by 802.11n. In practice, the 20MHz channels 300-1 to 300-8 are cascaded to form a wider communication composite channel.

[0203] In the 802.11ac standard, channels in each predefined 40MHz, 80MHz, or 160MHz subset are continuous within the operating frequency band. That is, holes (missing channels) are not allowed in the ordered composite channels within the operating frequency band.

[0204] The 160MHz channel bandwidth includes two 80MHz channels, which may or may not be frequency-contiguous. The 80MHz and 40MHz channels each comprise two frequency-adjacent or consecutive 40MHz channels and a 20MHz channel, respectively. However, the invention may include embodiments with any composition of channel bandwidth (i.e., including only consecutive channels within the operating frequency band, or including non-consecutive channels within the operating frequency band).

[0205] On the "primary channel" (400-3), TXOPs are granted to nodes via the Enhanced Distributed Channel Access (EDCA) mechanism. In practice, for each composite channel with bandwidth, 802.11ac designates one channel as "primary," meaning that this channel is used to compete for access to the composite channel. The 20MHz primary channel is shared by all nodes (STAs) belonging to the same basic set, i.e., managed by or registered to the same local access point (AP).

[0206] However, in order to ensure that other traditional nodes (i.e., traditional nodes that do not belong to the same set) do not use the secondary channel, it is proposed to replicate the control frame (e.g., RTS frame / CTS frame) that preserves the composite channel on each 20MHz channel in the composite channel.

[0207] As previously addressed, the IEEE 802.11ac standard allows for the bonding of up to four or even eight 20MHz channels. Due to the limited number of channels (19 in the 5GHz band in Europe), channel saturation becomes a problem. In fact, in densely populated areas, even with 20MHz or 40MHz bandwidth allocated to each wireless LAN cell, the 5GHz band will undoubtedly tend towards saturation.

[0208] The development of the 802.11ax standard aims to enhance the efficiency and usability of wireless channels in dense environments.

[0209] From this perspective, multi-user (MU) transmission characteristics can be considered, allowing multiple simultaneous transmissions from a master node (typically an access point, AP) relative to different users in both the downlink (DL) and uplink (UL) directions. In the uplink, multi-user transmission can be used to reduce the probability of collisions by allowing multiple nodes to transmit to the AP simultaneously.

[0210] To enable this multi-user transmission in practice, it has been proposed to divide the allocated 20MHz channel (400-1 to 400-4) into sub-channels 410 (basic sub-channels, also known as subcarriers or resource units (RUs)), in which multiple users share these sub-channels 410 in the frequency domain, for example, based on orthogonal frequency division multiple access (OFDMA) technology.

[0211] refer to Figure 4b This situation is shown.

[0212] OFDMA's multi-user feature allows nodes (typically access points, or APs) to assign different RUs to different nodes, increasing contention. This can help reduce contention and collisions within 802.11 networks.

[0213] In contrast to MU downlink OFDMA (where the AP can directly send multiple data to multiple nodes (supported by specific indications within the PLCP header)), a triggering mechanism has been adopted for the AP to trigger MU uplink communication from each node.

[0214] To support MU uplink transmission (during AP-preempted TXOP), the 802.11ax AP must provide two legacy nodes (non-802.11ax nodes) to set their NAV and the 802.11ax nodes to determine the signaling information used for resource unit allocation.

[0215] In the following description, the term "traditional" refers to a non-802.11ax node, which means an 802.11 node that does not support prior technology for OFDMA communication.

[0216] like Figure 4b As shown in the example, the AP sends a trigger frame (TF) 430 to the target 802.11ax node. The TF frame informs the bandwidth or width of the target composite channel, meaning a value of 20MHz, 40MHz, 80MHz, or 160MHz. The TF frame is transmitted on the primary 20MHz channel and copied (repeated) on each of the other 20MHz channels, thus forming the target composite channel. As described above regarding the copying of control frames, it can be expected that the nearby legacy nodes (non-HT or 802.11ac nodes) that receive the TF frame (or its copy) on the primary channel will then set their NAV to the value specified in the TF frame. This prevents these legacy nodes from accessing the channels in the target composite channel during the TXOP.

[0217] Based on the AP's decision, the trigger frame TF can define multiple resource units (RUs) 410 or "random RUs" that can be randomly accessed by nodes in the network. In other words, the random RUs in the TF, specified or assigned by the AP, can serve as the basis for competition between nodes that intend to access the communication medium to send data. A collision occurs when two or more nodes attempt to transmit simultaneously on the same RU.

[0218] In that case, the trigger frame is called the Trigger Frame for Random Access (TF-R). The TF-R can be transmitted by the AP to allow multiple nodes to perform MU UL (Multi-User Uplink) random access to obtain the RU used by these nodes for UL transmission.

[0219] In addition to or as a substitute for random RUs, trigger frames (TFs) can also specify scheduled resource units. Scheduled RUs can be reserved by the AP for certain nodes, in which case no contention for access to these RUs is required for those nodes. These RUs and their corresponding scheduled nodes are indicated in the trigger frame. For example, node identifiers (such as the association ID (AID) assigned to each node upon registration) can be added to the TF frame in a manner associated with each scheduled RU to explicitly indicate which nodes are permitted to use each scheduled RU.

[0220] A random RU can be identified using an AID equal to 0.

[0221] OFDMA's multi-user feature allows the AP to assign different RUs to different nodes, increasing contention. This can help reduce contention and collisions within 802.11 networks.

[0222] exist Figure 4b In the example, each 20MHz channel (400-1, 400-2, 400-3 or 400-4) is subdivided into four sub-channels or RU 410 (typically 5MHz in size) in the frequency domain.

[0223] Of course, the number of RUs used to divide the 20MHz channel can be different from four. For example, 2 to 9 RUs can be set (and each one is 10MHz to about 2MHz in size).

[0224] Once a node uses an RU to transmit data to the AP, the AP responds with an ACK (not shown in the diagram) used to acknowledge the data on each RU, thus allowing each node to know when its data transmission was successful (ACK received) or unsuccessful (no ACK after timeout).

[0225] The IEEE 802.11-15 / 1105 standard provides a typical random allocation process that can be used by nodes to access random RUs indicated in a TF. This random allocation process (referred to as the RU contention scheme) is managed by a dedicated RU access module, separate from the channel access module described above, and is configured to manage access to at least one resource unit offered by another node (typically an AP) within a transmission opportunity granted to that other node on the communication channel, for the transmission of locally stored data on the accessed resource unit. Preferably, the RU access module includes an RU backoff engine, separate from the queue backoff engine, which uses RU contention parameters (including calculated RU backoff values) to compete for access to the random RU.

[0226] In other words, the RU contention scheme is based on a new backoff counter (called OFDMA or RU backoff counter / value (or OBO)) within the 802.11ax node to allow dedicated contention when accessing a random RU to send data.

[0227] Each node STA1 to STAn is a transmission node for receiving AP. As a result, each node has an active RU backoff engine separate from the queue backoff engine, which is used to calculate the RU backoff value (OBO) to be used for accessing at least one random resource unit for dividing the transmission opportunities granted on the communication channel, in order to transmit data stored in any traffic pair queue AC.

[0228] The random allocation process described in this document, targeting nodes with an active RU backoff value (OBO) among multiple nodes, includes the following steps: A first step, used to determine a random subchannel or RU competing for available communication medium based on a trigger frame; a second step, used to verify that the active RU backoff value (OBO) of the considered node is not greater than the number of randomly detected available RUs; then, if the verification is successful, a third step, used to randomly select a random RU from the detected available RUs to transmit data. If the second step is not verified, a fourth step (instead of the third step) is performed to decrement the RU backoff value (OBO) according to the number of detected available RUs.

[0229] As shown in the figure, some resource units may not be used (410u) because nodes with RU backoff value OBO less than the number of available random RUs do not randomly select one of these random RUs, while some other nodes are in conflict (as in example 410c) (because two of these nodes have randomly selected the same RU).

[0230] The MU uplink (UL) media access scheme, which includes both scheduled RUs and random RUs, has proven to be highly efficient compared to traditional EDCA access schemes. This is because both the number of collisions generated by simultaneous media access attempts and the overhead incurred due to media access are reduced.

[0231] However, the EDCA access scheme and the MU UL OFDMA / RU access scheme must coexist, especially allowing traditional 802.11 nodes to access the medium and even allowing 802.11ax nodes to initiate communication with nodes other than the AP.

[0232] While the standalone EDCA access scheme provides fair access to the medium across all nodes, its association with the MUUL OFDMA / RU access scheme introduces a shift in fairness. This is because 802.11ax nodes have additional opportunities to send data using the resource units provided in the transmission opportunities granted to another node (particularly the AP), compared to traditional nodes.

[0233] Solutions have been proposed to restore some fairness among nodes.

[0234] For example, in co-pending UK application 1612151.9 filed on July 13, 2016, when data is successfully transmitted via the accessed resource element (i.e., via UL OFDMA), the current value of at least one EDCA parameter is modified to a different value (MU EDCA parameter). This is to reduce the probability that a node will compete for access to the communication channel via (conventional EDCA).

[0235] Within this framework, a method is proposed to immediately reduce the probability of a node's EDCA-based transmissions (i.e., using the EDCA media access scheme) when the node successfully transmits its data using the MU UL mechanism. This reduction is achieved by modifying well-known EDCA parameters.

[0236] The proposed mechanism, as described in the paper titled "Proposed text changes for MU EDCA parameters," sets each transport queue to MU EDCA mode in response to successful data transmission within an accessed MU UL OFDMA resource unit. This setting is performed for a predetermined duration known as HEMUEDCA. MU EDCA mode is a mode that sets each EDCA parameter to a MU value corresponding to the conventional values ​​used in different conventional EDCA modes.

[0237] To switch from the traditional EDCA contention access mode to the MU EDCA mode, a node can modify its EDCA parameters (AIFSN, CW) for all service queues that have successfully transmitted some data in the accessed resource unit. min and / or CW max Switching back to traditional EDCA mode can occur when HEMUEDCATimer expires. Note: This timer is reset to its initial value whenever a node transmits new data (from any AC) again during a newly accessed resource unit provided by the AP. It is recommended that HEMUEDCATimer's initial value be high (e.g., tens of milliseconds) to accommodate several new opportunities for MU UL transmissions.

[0238] The MU value of the EDCA parameter can be transmitted by the AP in a dedicated information element (usually sent within a beacon frame that broadcasts network information to the node).

[0239] The disclosed method suggests increasing the AIFSN value only for each transport queue, while maintaining CW. min and CW max Unchanged. With the increase of the corresponding AIFS time period, it prevents (or at least substantially delays) the decrementing of queue backoff values ​​or counters by service queues in the MU EDCA mode when the media is detected as idle. During the aforementioned predetermined duration, new accesses to the media using the EDCA access scheme are statistically significantly reduced, or even no longer possible.

[0240] The AIFSN value in MU mode can be quite restrictive. Therefore, in high-density environments where the medium is busy most of the time (and thus idle for very short periods), nodes in MU EDCA mode must wait for a correspondingly restrictive AIFS period, thus preventing the backoff value of the AC queue in MU EDCA mode from frequently decreasing. As a result, nodes cannot frequently engage in EDCA contention for access to the medium.

[0241] Note that the specific configurations in the publications tend to completely prevent transport queues from making EDCA access to the medium when in MU EDCA mode (except when the network is not used at all). The AP specifies this particular operating mode by indicating a specific value (usually 0) for the AIFSN parameter in the set of MU EDCA parameters. This specific value means for a node that it should use a very high value for its AIFSN, which is equal to the HEMUEDCATimer transmitted by the AP (hint: the value of HEMUEDCATimer should be high, i.e., about tens of milliseconds, compared to the worst AIFS[i] of less than 0.1 milliseconds in the traditional EDCA mode).

[0242] Unfortunately, as long as a node periodically visits the OFDMA RU to transmit data, the node's traffic queues in MU EDCA mode remain in the same MU mode. This is particularly true for traffic queues in MU mode that haven't even transmitted any data in the visited OFDMA RU during potentially lengthy periods of periodic OFDMA access. This contradicts the QoS principles described in the 802.11e standard.

[0243] Now for reference Figure 5a Explain the situation, in which Figure 5a Examples of applications using the MU EDCA parameters as described in the aforementioned publications are illustrated.

[0244] In the scenario depicted in the diagram, AP 501 polls node 502 by sending a standardized trigger frame 1300, requesting that node to transmit some QoS data from the AC_VI access category. This can be done by providing the node with one or more scheduled RUs. This category can be... Figure 13 The “Preferred AC” field 1330 is shown as indicated.

[0245] After the SIFS time, node 502 initiates a MU UL OFDMA transmission 510 by picking up some QoS data from the requested traffic queue AC_VI (511). In this exemplary scenario, there is not enough QoS data ready to be sent in the requested traffic queue AC_VI. In this context, node 502 is allowed to retrieve additional QoS data from a higher-priority traffic queue (e.g., the AC_VO access category in this example) (512). This data retrieval rule allows for maximizing bandwidth usage as specified in the 802.11 standard.

[0246] Therefore, node 502 uses the scheduled RU to transmit AC_VI data 511 and AC_VO data 512 to the AP. The corresponding two transmission queues AC_VI and AC_VO are thus switched to MU EDCA mode (represented by the white graphic within the black box), where node 502 now uses the MU EDCA parameters for each of these transmission queues. Specifically, higher values ​​for the AIFSN parameter can be used, and CW can optionally be used. min and CW min Higher values ​​for the parameter.

[0247] In parallel, when node 502 is allowed to switch back to traditional EDCA mode with traditional EDCA parameters, HEMUEDCATimer 590 starts a countdown. The "switch back" can occur after a predetermined duration has expired (i.e., when HEMUEDCATimer reaches 0).

[0248] However, whenever node 502 transmits data in an accessed resource unit provided by the AP during any subsequent transmission opportunity granted to the AP on the communication channel, the HEMUEDCATimer is reinitialized to its initial value (predetermined duration). In other words, the timer is reinitialized whenever node 502 is polled by the AP again.

[0249] This is Figure 5a The example occurs when AP 501 sends a new trigger frame 1300-2 with a new RU to node 502, before HEMUEDCATimer 590 has expired. The AP then polls node 502 again to send QoS data from the AC_VI access category.

[0250] Node 502 retransmits QoS data 520 from the AC_VI access category, and HEMUEDCATimer 590 is reinitialized to its initial value, i.e., the predetermined duration. The same occurs when AP 501 polls node 502 again to send new QoS data from the AC_VI access category by sending a new trigger frame 1300-3.

[0251] In this scenario, node 502 is periodically polled by the AP for OFDMA transmission of QoS data from AC_VI. Finally, as long as the AC_VI class provides sufficient data, the AC_VO class will not participate in new OFDMA transmissions and will remain blocked in MU EDCA mode.

[0252] Additionally, the MU mode AIFSN value of the service queue AC_VO (which is typically a more restrictive value, i.e., a high value) prevents (or severely delays) the associated backoff value used for EDCA contention on the medium by reducing the associated backoff value of the service queue AC_VO.

[0253] This results in the AC_VO class, which inherently has the highest QoS priority, remaining locked in MU EDCA mode without new EDCA opportunities to send data. Consequently, the QoS requirements of 802.11ax remain severely degraded.

[0254] Within this framework, the present invention proposes to restore QoS fairness by breaking the singularity of HEMUEDCATimer used by service queues in MU mode when periodic node polling is conducted through the AP.

[0255] Specifically, when data stored in two or more service queues is transmitted (preferably successfully) in one or more accessed resource units provided by another node within one or more transmission opportunities granted to that other node on the communication channel, node 502 can set each transmission service queue (i.e., transmission in the accessed resource unit) to a MU EDCA mode different from the conventional EDCA mode and continuously count down to a predetermined duration for each timer associated with the transmission service queue. Then, when any timer expires, node 502 can switch the associated service queue back to the conventional EDCA mode where each EDCA parameter is set back to its conventional value.

[0256] Therefore, this invention provides nodes with multiple timers associated with each of the service queues. When a specific HEMUEDCATimer is dedicated to each AC queue, that AC queue can exit MU EDCA mode independently of other AC queues. This restores QoS at the AC queue level.

[0257] Now for reference Figure 5b This illustrates a result of one implementation of the invention, wherein Figure 5b Through with Figure 5a The same sequence illustrates how QoS is recovered through processing via a separate HEMUEDCATimer.

[0258] Following the first TF 1300, both transport queues AC_VI and AC_VO are in MU EDCA mode. When the respective transport queues are allowed to switch back to traditional EDCA mode with traditional EDCA parameters, their respective HEMUEDCATimers (591 for AC_VI and 592 for AC_VO) are simultaneously started to begin a countdown.

[0259] According to the present invention, the evolution of these individual timers is independent of each other.

[0260] As described below, the two timers associated with AC_VI and AC_VO can be initialized with different predetermined durations. This is to improve QoS management.

[0261] Therefore, when the next TF 1300-2 is received in the accessed OFDMA RU as required by the AP and AC_VI data is transmitted, HEMUEDCATimer 591 associated with AC_VI is reinitialized with its corresponding initial predetermined duration, while HEMUEDCATimer 592 associated with AC_VO continues to elapse (because no VO data is transmitted in the accessed RU after TF 1300-2).

[0262] As a result, HEMUEDCATimer 592 associated with AC_VO expires before HEMUEDCATimer 591 associated with AC_VI, thus relaxing the MU EDCA constraints for the service queue AC_VO. In effect, the service queue AC_VO switches back to the traditional EDCA mode using traditional EDCA parameters. Consequently, the backoff value of the AC_VO service queue can decrease normally, allowing the AC_VO queue to efficiently compete for the medium.

[0263] Figure 6 A communication device 600 of a wireless network 100 is schematically illustrated, wherein the communication device 600 is configured to implement at least one embodiment of the present invention. The communication device 600 may preferably be a device such as a microcomputer, workstation, or lightweight portable device. The communication device 600 includes a communication bus 613 preferably connected to the following components:

[0264] • Such as a microprocessor, etc., is represented as a central processing unit 611 of a CPU;

[0265] • Read-only memory 607, denoted as ROM, is used to store the computer program used to implement the present invention;

[0266] • A random access memory 612, represented as RAM, for storing executable code of the method according to embodiments of the present invention and registers, wherein the registers are configured to record variables and parameters required to implement the method according to embodiments of the present invention; and

[0267] At least one communication interface 602 is connected to a wireless communication network 100, such as a wireless communication network according to the 802.11ax protocol, through which digital data packets, frames, or control frames are transmitted. Under the control of a software application running in the CPU 611, frames are written from the FIFO transmit memory in RAM 612 to the transmit network interface, or frames are read from the receive network interface and written to the FIFO receive memory in RAM 612.

[0268] Optionally, the communication device 600 may also include the following components:

[0269] • A data storage component 604, such as a hard disk, is used to store a computer program used to implement a method according to one or more embodiments of the present invention;

[0270] • Disk drive 605 used by disk 606, which is configured to read data from disk 606 or write data to said disk;

[0271] • Screen 609 is used to display decoded data and / or serves as a graphical interface with the user via keyboard 610 or any other indicating component.

[0272] The communication device 600 can be optionally connected to various peripheral devices such as a digital camera 608, wherein each peripheral device is connected to an input / output card (not shown) to supply data to the communication device 600.

[0273] Preferably, the communication bus provides communication and interoperability between the components included in or connected to the communication device 600. The representation of the bus is not limiting; in particular, the central processing unit is operable to communicate instructions directly or via another component of the communication device 600 to any component of the communication device 600.

[0274] Disk 606 may optionally be replaced by any information medium such as a compact disc (CD-ROM) (rewritable or non-rewritable), a ZIP disk, a USB key, or a memory card, and is generally replaced by an information storage component, wherein the information storage component may be read by a microcomputer or microprocessor, integrated or not integrated into the device, may be removable, and configured to store one or more programs, wherein execution of the one or more programs enables the implementation of the method according to the invention.

[0275] As previously described, the executable code may optionally be stored in read-only memory 607, on hard disk 604, or on a removable digital medium such as disk 606. According to an alternative variation, the executable code of the program may be received via interface 602 through communication network 603 to be stored in one of the storage components of communication device 600, such as hard disk 604, before being executed.

[0276] The central processing unit 611 is preferably configured to control and direct the execution of instructions or software code of a program according to the invention, wherein these instructions are stored in one of the aforementioned storage components. Upon power-up, the program stored in non-volatile memory (e.g., on hard disk 604 or in read-only memory 607) is transferred to random access memory 612 containing the executable code of the program and registers for storing variables and parameters required to implement the invention.

[0277] In a preferred embodiment, the device is a programmable device that implements the invention using software. However, alternatively, the invention may be implemented in hardware (e.g., using an application-specific integrated circuit or ASIC).

[0278] Figure 7 This is a block diagram schematically illustrating the architecture of a communication device or node 600 (particularly one of nodes 100-107) configured to at least partially implement the present invention. As shown, node 600 includes a physical (PHY) layer block 703, a MAC layer block 702, and an application layer block 701.

[0279] The PHY layer block 703 (here, the 802.11 standardized PHY layer) has the following tasks: formatting frames, modulating or demodulating frames on or from any 20MHz channel or composite channel, and thus transmitting or receiving frames via the radio medium 100 used. These frames may be 802.11 frames, such as the medium access trigger frame TF 430 used to define resource units in an granted transmission opportunity, MAC data and management frames based on a 20MHz width for interaction with a conventional 802.11 station, and OFDMA type MAC data frames with a width smaller than 20MHz (typically 2MHz or 5MHz) relative to the radio medium.

[0280] The MAC layer block or controller 702 preferably includes a MAC 802.11 layer 704 that implements conventional 802.11ax MAC operations and an additional block 705 for at least partially performing the present invention. The MAC layer block 702 may optionally be implemented in software, wherein the software is loaded into RAM 512 and executed by CPU 511.

[0281] Preferably, the additional block (referred to as MU EDCA mode management module 705) implements the part of the present invention related to node 600, namely managing the switching between the two conventional modes and MU EDCA mode, and processing the timers used to control the service queues in MU EDCA mode.

[0282] From the AP's perspective, the MU EDCA mode management module 705 can be provided to send nodes a set of traditional values ​​for EDCA parameters, a set of MU values ​​for EDCA parameters different from the set of traditional values, and a set of initialization values ​​for HEMUEDCATimer, thereby driving these nodes into MU EDCA mode to remain in this mode at least for the corresponding duration. Therefore, when one of the nodes' service queues switches between a traditional EDCA mode and a MU EDCA mode to be maintained for a predetermined duration, these values ​​drive the node to configure itself, wherein in the traditional EDCA mode, each EDCA parameter is set to traditional values, and in the MU EDCA mode, each EDCA parameter is set to MU values, and the predetermined duration is initialized based on associated initialization values ​​and obtained by counting down from an associated counter.

[0283] The MAC 802.11 layer 704 and the MU EDCA mode management module 705 interact with each other to provide management of the channel access module for the processing queue backoff engine and the RU access module for the processing RU backoff engine as described below.

[0284] In the upper part of this diagram, application layer block 701 runs applications that generate and receive data packets (e.g., data packets for a video stream). Application layer block 701 represents all stacked layers above the MAC layer, which is standardized according to ISO.

[0285] Various typical embodiments are now used to illustrate embodiments of the invention. Although the presented example uses trigger frame 430 sent by the AP (see...) Figure 4b This mechanism can be used for multi-user uplink transmission, but an equivalent mechanism can be used in centralized or self-organizing environments (i.e., without an AP). This means that the operations described below with reference to an AP can be performed by any node in a self-organizing environment.

[0286] These embodiments are primarily illustrated by considering OFDMA resource units within the context of IEEE 802.11ax. However, the application of this invention is not limited to the IEEE 802.11ax context.

[0287] Furthermore, this invention does not necessarily rely on the use of a MU access scheme as described in 802.11ax. Any other RU access scheme that defines an alternative media access scheme that allows nodes to access the same medium simultaneously can also be used.

[0288] A set of MU values ​​may be more restrictive than a set of traditional values, which results in service queues in MU EDCA mode accessing the medium less frequently using the EDCA contention access scheme.

[0289] However, in some embodiments, the set of MU values ​​can be more flexible.

[0290] For clarity, the following explanation focuses on a more restrictive set of MU values. In this context, the MU EDCA pattern is referred to as the "degraded" pattern, while the traditional EDCA pattern is referred to as the "non-degraded" pattern.

[0291] Figure 8 A typical transport block of a communication node 600 according to an embodiment of the present invention is shown.

[0292] As described above, the node includes a channel access module and possibly an RU access module, both of which are implemented in MAC layer block 702. The channel access module includes:

[0293] Multiple service queues 210 are used to serve data services according to different priorities;

[0294] Multiple queue backoff engines 211, each associated with a specific service queue, are used to calculate the queue backoff values ​​to be used for contention to access at least one communication channel in order to transmit data stored in each service queue, using EDCA parameters, specifically for calculating the queue backoff values ​​to be used for access to at least one communication channel. This is the EDCA access scheme.

[0295] According to an embodiment of the invention, each queue backoff engine 211 has its own HEMUEDCATimer 2110. This means that the node includes multiple timers associated with each of the business queues.

[0296] Furthermore, by updating the EDCA parameters according to the teachings of the present invention, an EDCA mode switch 213 is set in the node for handling the switching between the degraded MU EDCA mode and the traditional EDCA mode. The EDCA mode switch operates in response to each OFDMA transmission in the RU.

[0297] The RU access module includes a separate RU backoff engine 800, used to calculate the RU backoff value to be used for accessing OFDMA random resource units (RLUs) defined in the received TF (e.g., sent by the AP) using RU contention parameters, specifically for transmitting data stored in arbitrary traffic queues within an OFDMA RU. The RU backoff engine 800 is associated with a transmission module called an OFDMA multiplexer 801. For example, when the RU backoff value OBO reaches zero, as described below, the OFDMA multiplexer 801 is responsible for selecting the data to be transmitted from AC queue 210.

[0298] The conventional AC queue backoff register 211 drives the media access request along the EDCA protocol (channel contention access scheme), while in parallel, the RU backoff engine 800 drives the media access request to the OFDMA multi-user protocol (RU contention access scheme).

[0299] When these two competing access schemes coexist, the source node implements a media access mechanism with conflict avoidance based on the calculation of backoff values:

[0300] - Queue backoff counter value, which corresponds to the number of time slots (excluding the DIFS period) a node waits before accessing the medium after the communication medium has been detected as idle. This is EDCA regardless of whether the node is in a degraded or non-degraded state;

[0301] - The RU backoff counter value (OBO) corresponds to the number of idle random RUs detected by a node before accessing the medium, after the TXOP has been granted to an AP or any other node on a composite channel consisting of RUs. This is OFDMA. A variation of counting down the OBO based on the number of idle random RUs can be based on a time-dependent countdown.

[0302] Figure 9 The flowchart illustrates the main steps performed by the MAC layer 702 of node 600 when new data to be transmitted is received. Figure 9 This illustrates a conventional FIFO feed in an 802.11 context.

[0303] Initially, no service queue 210 stores the data to be transmitted. As a result, no queue backoff value 211 is calculated. The corresponding queue backoff engine or the corresponding AC (Access Class) is considered inactive. When data is stored in the service queue, the queue backoff value is calculated immediately (according to the corresponding queue backoff parameters), and the associated queue backoff engine or AC is considered active.

[0304] When a node has data ready to be transmitted over the medium, the data is stored in one of the AC queues 210, and the associated backoff 211 should be updated.

[0305] In step 901, new data is received from an application running on the device (e.g., from application layer 701), from another network interface, or from any other data source. This new data is ready to be sent by the node.

[0306] In step 902, the node determines which AC queue 210 the data should be stored in. This operation is typically performed by (according to...) Figure 3b The matching shown is performed by checking the TID (Business Identifier) ​​value attached to the data.

[0307] Next, step 903 stores the data in the determined AC queue. This means that the data is stored in an AC queue with the same data type as the data.

[0308] In step 904, the conventional 802.11 AC backoff calculation is performed using the queue backoff engine associated with the determined AC queue.

[0309] If the determined AC queue is empty immediately before the storage in step 903 (i.e., the AC was originally inactive), then a new queue backoff value for the corresponding backoff counter needs to be calculated.

[0310] Therefore, the node calculates the queue backoff value as equal to a random value selected within the range [0, CW], where CW is the current value of the CW for the considered access class (as defined in the 802.11 standard). It should be reiterated that the queue backoff value is added to the AIFSN (which may be degraded in MU EDCA mode) to implement relative priority for different access classes. CW is selected from the range [CW]. min CW max The congestion window value selected in the image, where the two boundaries are CW. min and CW max (Potential downgrade) depends on the access category being considered.

[0311] As a result, AC became active.

[0312] The above parameters CW, CW min CW max AIFSN and backoff values ​​form the EDCA parameters and variables associated with each AC. These values ​​are used to set the relative priority of media accessing different categories of data.

[0313] EDCA parameters typically have fixed values ​​(e.g., CW). min CW maxAnd AIFSN), while EDCA variables (CW and backoff value) evolve with time and media availability. As is readily apparent from the above, this invention provides the evolution of EDCA parameters by switching between degraded and non-degraded parameter values.

[0314] Additionally, if necessary, step 904 may include calculating the RU backoff value OBO. The RU backoff engine 800 is inactive if (for example, because there was no data in the service queue prior to the previous step 903) and if new data to be addressed to the AP has been received, the RU backoff value OBO needs to be calculated.

[0315] RU backoff value OBO can be used in a similar manner to EDCA backoff value, i.e., using dedicated RU contention parameters (such as a dedicated contention window [0, CWO] and a selection range [CWO]). min CWO max ] etc. to calculate.

[0316] Note that some embodiments may provide a distinction between data that can be sent via the resource unit (i.e., compatible with MU UL OFDMA transmission) and data that cannot be sent via the resource unit. Such a decision can be made during step 902, and corresponding flags can be added to the stored data.

[0317] In this case, the RU backoff value OBO is calculated only when the newly stored data is marked as compatible with MU UL OFDMA transmission.

[0318] After step 904, Figure 9 The processing is now complete.

[0319] Once the data is stored in the AC queue, the node can refer to the following... Figure 10 The EDCA access scheme shown (in traditional EDCA mode or downgraded MU EDCA mode), or as referenced below Figure 11 The diagram shows that the medium is accessed directly via the resource units provided by the AP through one or more trigger frames.

[0320] Figure 10 A flowchart is used to illustrate the steps for accessing media based on the (traditional or downgraded MU) EDCA media access scheme.

[0321] Steps 1000–1020 describe the conventional waiting mechanism introduced in the EDCA mechanism to reduce collisions on the shared radio medium. In step 1000, node 600 listens to the medium to wait for it to become available (i.e., the detected energy is below a given threshold on the main channel).

[0322] During the AIFS[i] time interval (which includes the DIFS time interval and the AIFSN[i] time interval - see Figure 3a When the medium becomes idle, step 1010 is executed, in which node 600 decrements the backoff counter 211 of all active (non-zero) AC[] queues by 1. In other words, the node decrements the queue backoff value for each basic time unit in which the communication channel is detected as idle.

[0323] Next, in step 1020, node 600 determines whether at least one of the AC backoff counters has reached 0.

[0324] If no AC queue backoff reaches zero, node 600 waits for another backoff slot (typically 9 μs) and thus loops back to step 1000 to listen to the medium again during the next backoff slot. This allows the AC backoff counters to be decremented at each new backoff slot as soon as the medium is listened to as idle, once the respective AIFS[i] of the AC backoff counters has expired.

[0325] If at least one AC queue backoff reaches 0, then step 1030 is executed, in which node 600 (more precisely, virtual conflict handler 212) selects the active AC queue with a zero queue backoff counter and the highest priority.

[0326] In step 1040, an appropriate amount of data is selected from the chosen AC for transmission to match the bandwidth of the TXOP.

[0327] Next, in step 1050, if, for example, an RTS / CTS exchange has been successfully performed to grant a TXOP, node 600 initiates an EDCA transmission. Thus, node 600 transmits the selected data on the medium during the granted TXOP.

[0328] Next, at step 1060, node 600 determines whether the EDCA transmission has ended. If it has ended, step 1070 is executed.

[0329] At step 1070, node 600 updates the contention window CW of the selected traffic queue based on the transmission status (positive or negative ACK, or no ACK received). Typically, in the event of a transmission failure, node 600 doubles the value of CW until CW reaches the maximum value CW of the data-dependent AC type. max (Degraded or non-degraded) until then. On the other hand, if the EDCA transmission is successful, the contention window CW is set to the minimum CW of the AC type, which also depends on the data. min (Downgraded or not downgraded).

[0330] Next, if the selected service queue is not empty after the EDCA data transmission, then similar to step 904, a new associated queue backoff counter is randomly selected from [0,CW].

[0331] That's how it ended. Figure 10 The processing.

[0332] Figure 11 A flowchart illustrates the steps for accessing a resource unit based on either the RU or OFDMA access scheme upon receiving a trigger frame defining the RU. For example, this shows node 502 in... Figure 5b The behavior in the middle.

[0333] In step 1110, the node determines whether it has received a trigger frame from an access point in the communication network. This trigger frame reserves the transmission opportunity granted to the access point on the communication channel and defines the resource unit RU that forms the communication channel. If a trigger frame is received, the node analyzes the content of the received trigger frame.

[0334] In step 1120, the node determines whether it can transmit data on one of the RUs defined in the received trigger frame. This determination may involve one or both of two conditions, particularly regarding the type of RU.

[0335] By analyzing the contents of the received TF, the node determines whether the defined RU is a scheduled resource unit assigned to the node by the access point. This can be done by looking up its own AID in the received TF, which is associated with the specific scheduled RU to be used for MU UL OFDMA transmission.

[0336] Furthermore, by analyzing the content of the received TF, the node determines whether one or more random RUs are defined in the TF, i.e., RUs accessed through contention using dedicated RU contention parameters (including the OBO value 800 mentioned above). In this case, the node also determines (e.g., if OBO 800 is less than the number of random RUs in the TF) whether its current OBO value 800 allows the selection of a random RU.

[0337] If a scheduled RU is assigned to the node, or the node is allowed (after contention) access to a random RU, the node determines the size of the random / scheduled RU to use and performs step 1130. Otherwise, the node decrements the RU backoff value OBO 800 based on the number of random resource units defined in the received trigger frame, and the process ends when the node cannot access any RU defined by the received TF.

[0338] In step 1130, the node selects at least one of the service queues 210 from which the data to be sent is selected, and adds the data of the selected queue to the transmission buffer until the amount of data reaches the size of the selected resource unit to be used.

[0339] It can involve various criteria used to select the current business queue.

[0340] For example, this can be done as follows:

[0341] The service queue 210 with the lowest associated queue backoff value is selected. Therefore, the selection of the service queue depends on the value of EDCA backoff 211, thereby ensuring that the node adheres to the EDCA principle and implements the correct QoS for the data of that node;

[0342] Randomly select a non-empty business queue from the business queues;

[0343] Select the business queue that stores the largest amount of data (i.e., the one with the highest load);

[0344] Select the non-empty service queue with the highest associated service priority (considering...). Figure 3b (As shown in the AC category);

[0345] Select a non-empty service queue associated with the data type specified below, where the data type matches the data type associated with the resource unit to which the selected data is to be transmitted. This specified data type can be used by the AP, for example, when the AC preference level field is set to 1. Figure 13 The preferred AC field 1340 is the service queue indicated in the trigger frame. This is in Figure 5b The selection criteria used in the example.

[0346] Following step 1130, step 1140 provides the node with a list of transmit / transmit queues to set or update by inserting the data selected in step 1130 from the current service queue. This list maintains the insertion order of the transmit / transmit queues, thereby making it easy, for example, to identify the primary transmit / transmit queue (the first queue selected in step 1030) and subsequent transmit / transmit queues.

[0347] Additionally, during step 1140, the node may store an information item indicating the amount of data thus selected from the current traffic queue for transmission in the RU. For example, the node then updates the list of transmit queues by also inserting the amount of data selected from the current traffic queue.

[0348] The list of transmit / transmission queues can be implemented using the following table, which includes the ranking of the transmission queue (which can be simplified to "primary" or "secondary" queues) and the amount of data put into the transmission buffer for each service queue.

[0349] In step 1150, the node determines whether the amount of data stored in the transmission buffer is sufficient to fill the selected resource unit.

[0350] If not, there is still space available in the resource unit for additional data. Therefore, the process loops back to step 1130, during which the same selection criteria can be used to select another service queue. In this way, the transmission buffer is gradually filled to reach the selected resource unit size.

[0351] Therefore, it can be noted that multiple transmission service queues of the same node can be involved during MU UL OFDMA transmission, thus allowing multiple queues to enter MU EDCA mode.

[0352] In a variation that avoids mixing data from two or more service queues (i.e., selecting data for the chosen RU from a single service queue), padding data can be added to fully populate the chosen RU. This is to ensure that the RU has energy detectable by conventional nodes throughout its duration.

[0353] In another variation of implementing a specific data aggregation rule, if the first selected business queue does not have enough data to completely fill the accessed resource unit, data from a higher priority business queue can be selected.

[0354] Once the transmission buffer is full for the selected RU, step 1160 initiates the transmission of the data stored in the transmission buffer to the AP's MU UL OFDMA. The OFDMA transmission is based on the OFDMA subchannels and modulation defined in the received trigger frame and, in particular, in the RU definition.

[0355] Next, once the transmission has been made, and preferably upon successful transmission (i.e., receipt of acknowledgment from the AP), step 1170 determines a new value for one or more EDCA parameters to be applied to one or more service queues, so that the value or these values ​​are modified to a penalty value.

[0356] Therefore, adding the transmission queues in the list to MU EDCA mode in step 1140 means that the EDCA or "queue contention" parameter set of these transmission queues should be modified, specifically, the EDCA or "queue contention" parameter set should be modified to the degradation parameter values ​​to be determined. One or more transmission queues may already be in MU EDCA mode. However, the degradation parameter values ​​also need to be determined (these degradation parameter values ​​can be modified by beacon frames that have recently received new degradation values).

[0357] During step 1170, the degradation parameter values ​​are determined.

[0358] In this embodiment, the degraded value of the EDCA parameter, compared to the non-degraded value of the EDCA parameter used by a service queue not set in MU EDCA mode, includes the degraded Arbitration Interframe Gap Number (AIFSN). In other words, the AIFSN of the transmission queue is set to the degraded value. Figure 2c This shows the set of degraded EDCA parameters with degraded AIFSN values.

[0359] In some embodiments, AIFSN is the only parameter modified when switching to MU EDCA mode. This means that the downgraded value of the EDCA parameter includes the same lower bound CW as the non-downgraded value used in the traditional EDCA mode. min and / or upper boundary CW max CW min and CW max These two factors define the range of choices for selecting the size of the competition window.

[0360] The degradation value used in this step is preferably selected from the dedicated information elements that are the last received beacon frames typically formed as part of the beacon frames transmitted by the AP. Therefore, for a node that periodically receives beacon frames from the access point (each beacon frame broadcasts network information related to the communication network to multiple nodes), the received beacon frames typically include, in addition to non-degraded (or conventional EDCA) values, degraded values ​​of the EDCA parameters of multiple traffic queues switched to MU EDCA mode.

[0361] If no such degradation value is received from the AP, the default value as described in the standard can be used.

[0362] Step 1170 further includes: determining a predetermined degradation duration HEMUEDCATimer[AC] value for each transport traffic queue (AC). This duration defines the period during which a node must remain in MUEDCA mode for its associated degradation traffic queue. This information can also be obtained from the AP (e.g., from the following...). Figure 14b It can be obtained (or the specific dedicated information element for receiving beacon frames shown in 14c).

[0363] After step 1170, step 1180 actually replaces the current value of the EDCA parameter associated with the transport service queue with the degradation value determined in step 1170.

[0364] In parameter CW min and / or CW max With new values, the current CW for one or more business queues may be outdated. In this case, the CW can be changed from the newly defined range. min CW max Select a new CW in ] .

[0365] Next, in step 1190, timers 2110 associated with each transport queue 210 are initialized with the corresponding predetermined degradation duration HEMUEDCATimer[AC] as determined in step 1170. Timers 2110 then start and gradually elapse over time.

[0366] Note that if the timer has elapsed during step 1180 (meaning the associated service queue is already in MUEDCA mode), the timer is reinitialized (i.e., reset) to the HEMUEDCATimer[AC] value to keep the node in MUEDCA mode for the next HEMUEDCATimer[AC] time period. This is Figure 5b The example shows the case of timer 591.

[0367] Figure 12 The flowchart above illustrates the queue-level node management used to switch back to the non-degraded legacy mode in the example above. This management is based on HEMUEDCATimer[AC], which is dedicated to the business queue AC of interest. In fact, as long as the timer HEMUEDCATimer[AC] has not expired, the business queue AC can remain in MU EDCA mode.

[0368] Therefore, in step 1210, it is checked whether HEMUEDCATimer[AC] has expired / reached its value of 0.

[0369] If the condition is met, in step 1220, the service queue AC is switched back to EDCA mode. This may include resetting the EDCA parameters to non-degraded values ​​(e.g., the AP uses the following...). Figure 14a The beacon frame provides the value to the node.

[0370] Note that since the timer is reinitialized in each new step 1190, the expiration of HEMUEDCATimer[AC] only occurs if no data from the traffic queue AC is transmitted from the slave node in any OFDMA resource unit provided by the AP within the subsequent TXOP granted to the AP during the predetermined degradation duration.

[0371] The process then ends in step 1230.

[0372] For each service queue in the degraded MU EDCA mode (i.e., the timer is running), perform parallel and independent operations. Figure 12 The processing is as follows. This is because, according to the teachings of the present invention, timer 2110 is separate.

[0373] Figure 13The structure of a trigger frame is shown as defined in the 802.11ax draft standard.

[0374] Trigger frame 1300 includes a dedicated field 1310 called the User Information field. This field contains a “Trigger Dependency Public Information” field 1320, which in turn contains an “AC Preferred Level” field 1330 and a “Preferred AC” field 1340.

[0375] The preferred AC field 1340 is a 2-bit field that indicates the AC queue (value 0 to 3), from which data should be sent by the node on the RU assigned to the node in the trigger frame.

[0376] AC Preferred Level field 1330 is a bit that indicates whether the value of Preferred AC field 1340 is meaningful. If field 1340 is set to 1, the node should consider Preferred AC field 1340 when selecting data in step 1130. If field 1330 is set to 0, the node is allowed to send data from any AC queue regardless of the value of Preferred AC field 1340.

[0377] Other fields for triggering frames are defined in the 802.11ax standard.

[0378] The AP can also be responsible for broadcasting EDCA parameters for both EDCA mode and MU EDCA mode, as well as one or more initialization values ​​to be used to initialize or reset timer 2110 associated with traffic queue 210. The AP preferably uses well-known beacon frames specifically designed for configuring all nodes in an 802.11 cell for broadcasting. Note that if the AP is unable to broadcast EDCA parameters, the nodes are configured to fall back to the default values ​​defined in the 802.11ax standard.

[0379] Figure 14a The structure of the standardized information element 1410, which describes the parameters of EDCA in the beacon frame, is shown.

[0380] Fields 1411, 1412, 1413, and 1414 describe parameters associated with each service queue 210. For each service queue, subfield 1415 includes EDCA parameters: AIFSN as the delay before starting to decrease the associated backoff value, and minimum CW as... min and the largest CW max The values ​​of the contention window are ECWmin and ECWmax, and finally, the TXOP limit is the maximum data transfer time for an 802.11 device.

[0381] All other fields of the information element are fields described in the 802.11 standard.

[0382] Figure 14bAn exemplary structure of a dedicated information element 1420 for transmitting degraded EDCA parameter values ​​according to the present invention is shown, along with the common initialization value of the timer HEMUEDCATimer[AC] for all service queues. The dedicated information element 1420 may be included in beacon frames transmitted by the AP.

[0383] The dedicated information element 1420 specifies the downgraded EDCA parameters (1421, 1422, 1423, 1424) to be used for each AC queue, including nodes in MU EDCA mode. The dedicated information element 1420 also includes a subfield 1425 for specifying the common initialization value of HEMUEDCATimer.

[0384] Each subfield 1421, 1422, 1423, and 1424 includes the downgraded AIFSN value, as well as the downgraded ECWmin value and downgraded ECWmax value for the corresponding business queue (these two values ​​can be the same as the traditional EDCA values).

[0385] In this embodiment, the predetermined degradation duration for initializing the timer HEMUEDCATimer[AC] associated with each service queue AC is calculated based on the common initialization value 1425 received from the AP and the adjustment parameters specific to each respective service queue.

[0386] By using different adjustment parameters, different predetermined degradation durations can be obtained for initializing the timers associated with the two corresponding business queues.

[0387] In one embodiment, a common initialization value, such as that provided by the AP, can be multiplied by a constant value (adjustment parameter) based on the priority of each service queue (AC). For example, the constant value can be equal to 1 for AC_VO and AC_VI access categories, and equal to 3 for AC_BE and AC_BG access categories.

[0388] Figure 14c Another exemplary structure of a dedicated information element 1430 for transmitting degraded EDCA parameter values ​​according to the present invention is shown, along with an initialization value for each timer HEMUEDCATimer[AC] implemented by the node. The dedicated information element 1430 may be included in a beacon frame transmitted by the AP.

[0389] The dedicated information element 1430 specifies a set of degradation parameters (1431, 1432, 1433, 1434) to be used for each AC queue, including nodes in MU EDCA mode. The dedicated information element 1430 also includes a subfield 1425 for specifying the common initialization value of HEMUEDCATimer.

[0390] Each subfield 1431, 1432, 1433, and 1434 includes the downgraded AIFSN value of the corresponding service queue, as well as the downgraded ECWmin and downgraded ECWmax values ​​(these two values ​​can be the same as the traditional EDCA values), and finally the initialization value of HEMUEDCATimer to be used for the service queue of interest.

[0391] This means that the AP is responsible for calculating and then sending specific initialization values ​​for each service queue. In this embodiment, the predetermined degradation duration used to initialize the timer HEMUEDCATimer[AC] associated with each service queue is set to the corresponding initialization value received directly from the AP.

[0392] To improve QoS management, the initial values ​​calculated by the AP are preferably based on the priority of each AC.

[0393] Although the invention has been described above with reference to specific embodiments, the invention is not limited to these specific embodiments, and modifications that exist within the scope of the invention will be understood by those skilled in the art.

[0394] For example, although the above explanation describes broadcasting EDCA parameters and downgraded MUEDCA parameters in the dedicated information element of the same beacon frame, a variation could be considered that the beacon frame sending EDCA parameters alternates with another beacon frame broadcasting downgraded MUEDCA parameters.

[0395] Many other modifications and variations are shown to those skilled in the art, by reference to the foregoing exemplary embodiments which are given by way of example only and are not intended to limit the scope of the invention, that these modifications and variations are determined solely by the appended claims. In particular, different features from different embodiments may be interchanged where appropriate.

[0396] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude multiple elements. The mere fact that different features are stated in mutually different dependent claims does not indicate that combinations of these features cannot be used advantageously.

Claims

1. A communication device, comprising: A transmitter is used to transmit data in EDCA TXOP using contention parameters, where EDCA is Enhanced Distributed Channel Access and TXOP is Transmission Opportunity. A receiver is configured to receive beacon frames from an access point. The beacon frames include multiple values ​​for a multi-user EDCA timer (MUEDCATimer), a first parameter, and a second parameter different from the first parameter. The multiple values ​​correspond to multiple access categories (ACs) defined in the IEEE 802.11 series of standards. A controller, configured to control the transmitter, in the event that data of a predetermined AC included in the plurality of ACs has been successfully transmitted via resource elements defined by the IEEE 802.11 series of standards and provided by the access point, such that the first parameter for multi-user EDCA (MU EDCA) is used as the contention parameter for the predetermined AC for a predetermined duration based on a value corresponding to the predetermined AC among the plurality of values ​​included in the received beacon frame, and the contention parameter for the predetermined AC is set back to the second parameter when the predetermined duration expires.

2. The communication device according to claim 1 further includes a plurality of timers, each corresponding to a different AC of the plurality of ACs.

3. The communication device according to claim 1 or 2, wherein, The resource unit is allocated by the trigger frame transmitted from the access point.

4. The communication device according to claim 1 or 2, wherein, The competition parameters include at least CWmin, which indicates the lower boundary of the competition window (CW), and CWmax, which indicates the upper boundary of the CW.

5. The communication device according to claim 1 or 2, wherein, The received beacon frame includes at least a first value corresponding to a first AC and a second value corresponding to a second AC, and the duration based on the first value is different from the duration based on the second value.

6. The communication apparatus according to claim 1 or 2 further includes a communication unit for communicating with request-to-send frames, i.e., RTS frames or allow-to-send frames, i.e., CTS frames.

7. The communication device according to claim 1 or 2, wherein, The transmitter transmits data in different ACs.

8. An access point, comprising: A transmitter is used to transmit a beacon frame to a communication device. The beacon frame includes multiple values ​​for a multi-user EDCA timer (MUEDCATimer), a first parameter, and a second parameter different from the first parameter. The multiple values ​​correspond to multiple access categories (ACs) defined by the IEEE 802.11 series of standards. as well as A receiver is configured to receive data from the communication device, wherein, in the case that data of a predetermined AC included in the plurality of ACs has been successfully transmitted via a resource element defined by the IEEE 802.11 series of standards and provided by the access point, the communication device uses a first parameter for multi-user EDCA (i.e., MU EDCA) as a contention parameter for the predetermined AC for a predetermined duration based on a value corresponding to the predetermined AC among the plurality of values, and sets the contention parameter for the predetermined AC back to the second parameter when the predetermined duration expires.

9. The access point according to claim 8, wherein, The resource unit is allocated by the trigger frame transmitted from the access point.

10. The access point according to claim 8 or 9, wherein, The competition parameters include at least CWmin, which indicates the lower boundary of the competition window (CW), and CWmax, which indicates the upper boundary of the CW.

11. The access point according to claim 8 or 9, wherein, The plurality of values ​​includes at least a first value corresponding to a first AC and a second value corresponding to a second AC, and the duration based on the first value is different from the duration based on the second value.

12. The access point according to claim 8 or 9 further includes a communication unit for communicating with request-to-send frames, i.e., RTS frames, or allow-to-send frames, i.e., CTS frames.

13. The access point according to claim 8 or 9, wherein, The receiver receives data at different ACs.

14. An access point for transmitting beacon frames in a wireless communication network comprising multiple nodes. Each node includes multiple service queues for serving data services according to different priorities. Each service queue is associated with a corresponding queue backoff engine, which calculates a queue backoff value based on contention parameters. This queue backoff value is used to compete for access to the communication channel to transmit data stored in each of the multiple service queues in EDCATXOP. EDCA stands for Enhanced Distributed Channel Access, and TXOP stands for Transmission Opportunity. Each of the plurality of service queues is also associated with a timer for counting down a predetermined duration during which the contention parameter remains set to the MU-EDCA parameter until it is set back to an EDCA parameter that is different from the multi-user EDCA parameter (MU-EDCA parameter) used for the corresponding service queue. The beacon frame includes: The information element includes the competition parameter, and for each service queue, it includes a timer value for the predetermined duration to be used by the plurality of nodes to set the corresponding timer.

15. A method for a communication device, comprising: Data is transmitted in EDCA TXOP using contention parameters, where EDCA is Enhanced Distributed Channel Access and TXOP is Transmission Opportunity. A beacon frame is received from the access point. The beacon frame includes multiple values ​​for the multi-user EDCA timer (MUEDCATimer), a first parameter, and a second parameter different from the first parameter. The multiple values ​​correspond to multiple access categories (ACs) defined in the IEEE 802.11 series of standards. In the event that data of a predetermined AC included in the plurality of ACs has been successfully transmitted via resource units defined by the IEEE 802.11 series of standards and provided by the access point, the transmission is controlled such that the first parameter for multi-user EDCA (MUEDCA) is used as the contention parameter for the predetermined AC for a predetermined duration based on a value corresponding to the predetermined AC among the plurality of values ​​included in the received beacon frame, and the contention parameter for the predetermined AC is set back to the second parameter when the predetermined duration expires.

16. A method for an access point, comprising: A beacon frame is transmitted to the communication device. The beacon frame includes multiple values ​​for a multi-user EDCA timer (MUEDCATimer), a first parameter, and a second parameter different from the first parameter. The multiple values ​​correspond to multiple access categories (ACs) defined by the IEEE 802.11 series of standards. as well as When receiving data from the communication device, wherein, in the case that data of a predetermined AC included in the plurality of ACs has been successfully transmitted via a resource unit defined by the IEEE 802.11 series of standards and provided by the access point, the communication device uses a first parameter for multi-user EDCA (i.e., MU EDCA) as a contention parameter for the predetermined AC for a predetermined duration based on a value corresponding to the predetermined AC among the plurality of values, and sets the contention parameter for the predetermined AC back to the second parameter when the predetermined duration expires.

17. A non-transitory computer-readable medium storing a program that, when executed by a microprocessor or computer system in the device, causes the device to perform the method of claim 15 or 16.

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