Communication device, base station, communication method, and computer readable medium

Abstract

This invention relates to a communication device, base station, communication method, and computer-readable medium, and also to a wireless network including an access point and non-AP sites. The site has traffic queues and associated backoff counters that decrement over time as the medium is continuously listened to as idle for a period exceeding the corresponding AIFS duration. To compensate for additional opportunities provided by OFDMA RUs, the queue switches to MU mode when data from the queue is transmitted in an RU provided by an AP. To restore the dynamism of the backoff counters frozen in MU mode in known art, embodiments provide the following upon the expiration of one of the queue backoff counters: determining the current mode of the expired traffic queue; in the case of conventional mode, the site accesses the channel to transmit data from the queue; while in the case of MU mode, if no data is transmitted from the queue, a new backoff value is extracted to reset the expired backoff counter.

Description

[0001] (This application is a divisional application of the application filed on October 27, 2017, with application number 201780066921X and invention title "QoS Management for Multi-User EDCA Transmission Mode in 802.11ax Network".) Technical Field

[0002] This invention generally relates to communication networks, and more specifically to wireless communication methods and apparatus in wireless networks comprising access points (APs) and multiple non-AP sites. The invention relates to communication networks that provide channel access to non-AP sites through contention such as EDCA, and that provide secondary access to these non-AP sites to sub-channels (or resource units) segmented by the transmission opportunity (TXOP) granted to the access point, thereby transmitting data.

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

[0004] The IEEE 802.11 MAC standard family (a / b / g / n / ac, etc.) 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) technology.

[0005] The original DCF access method has been improved into the well-known Enhanced Distributed Channel Access (EDCA) method to prioritize data traffic when accessing the network's communication channels.

[0006] EDCA defines service categories and four corresponding access categories that allow high-priority services to be processed differently from low-priority services.

[0007] The implementation of EDCA at a site can be achieved using multiple service queues (known as "access categories") for serving data traffic with different priorities, each service queue being associated with a corresponding queue backoff counter. The queue backoff counter is initialized using a backoff value randomly drawn from the respective 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.

[0008] Traditional EDCA parameters include CW for each service queue. min CW max And AIFSN, of which CW min and CW max This refers to the lower and upper boundaries of the selection range of the EDCA contention window CW for a given traffic queue. AIFSN represents the Arbitration Inter-Frame Gap Number and defines the number of time slots (typically 9 μs) that a station must listen to when the medium is idle 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). This means that, with EDCA, a station decrements the queue backoff counter over time as long as the communication channel is continuously listened to when idle for a period exceeding the corresponding Arbitration Inter-Frame Gap duration.

[0009] Traditional EDCA parameters can be defined in beacon frames sent by APs in the network to broadcast network information.

[0010] The contention window (CW) and queue backoff value are EDCA variables.

[0011] The traditional EDCA backoff process involves the site randomly selecting a backoff value for the business queue backoff counter from each competing window CW, and then decrementing this backoff value when the media is idle after the AIFS period. Once the backoff value reaches zero, the site is allowed to access the media.

[0012] Therefore, EDCA queue backoff counters serve two purposes for sites. First, these counters drive efficient media access by reducing collision risk. Second, these counters manage Quality of Service (QoS) by reflecting the aging of data contained in the service queue (older data has a lower 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 decrement of the EDCA queue backoff counter).

[0013] The site uses the EDCA backoff process to access the communication network through backoff-based contention.

[0014] 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.

[0015] In particular, recent developments in the 802.11ax standard attempt to optimize the use of communication channels through multiple sites in a wireless network with access points (APs). In practice, typical content involves significant amounts of data, such as real-time interactive high-definition audiovisual content; and this content should be transmitted with the required Quality of Service (QoS).

[0016] Furthermore, it is well known that the performance of the CSMA / CA protocol used in the IEEE 802.11 standard deteriorates rapidly as the number of sites and traffic increases (i.e., in dense WLAN scenarios).

[0017] 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 sites to transmit simultaneously.

[0018] To enable such multi-user transmission in practice, it is proposed to divide the granted communication channel into sub-channels (also known as resource units (RUs)), where multiple users (non-AP sites) 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.

[0019] 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 sites 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.

[0020] OFDMA's multi-user feature allows an AP to assign different RUs to different non-AP sites to increase contention. This can help reduce contention and collisions within an 802.11 network.

[0021] In OFDMA, different subsets of subcarriers within the channel bandwidth can be used simultaneously by different frame transmissions. In the downlink direction, the AP is allowed to transmit parallel transmissions to different receiving non-AP sites. These transmissions are called multi-user downlink transmissions (MU DL). Additionally, the AP can provide uplink transmission scheduling to non-AP sites; this transmission scheme is called multi-user uplink (MU UL).

[0022] To support multi-user uplinks (i.e., uplink transmissions to an 802.11ax access point (AP) during TXOP granting), 802.11ax APs must provide signaling information for legacy sites (non-802.11ax sites) to set their NAVs and for 802.11ax client sites to determine the allocation of Resource Units (RUs) provided by the AP.

[0023] The 802.11ax standard defines a new control frame (i.e., trigger frame (TF)) sent by the AP to the site to trigger multi-user uplink communication.

[0024] The IEEE 802.11-15 / 0365 standard proposes that an Access Point (AP) sends a "trigger frame" (TF) to request the transmission of a Multi-User Uplink (MU UL) OFDMA PPDU from multiple sites. The TF defines the resource units provided by the AP to these non-AP sites. In response, the sites send MU UL (OFDMA) PPDUs as an immediate response to the trigger frame. All transmitters can transmit data simultaneously, but using a set of disjoint RUs (i.e., frequencies in the OFDMA scheme) results in less interference-prone transmission.

[0025] An Access Point (AP) can reserve a Resource Unit (RU) for a specific site. In this case, the AP indicates the site that has reserved the RU in the Transfer Function (TF). This RU is called a scheduled RU. The indicated site does not need to compete for access to this RU.

[0026] On the other hand, an AP can propose one or more resource units to an 802.11ax site through contention-based access. These RUs are called random RUs and help improve network efficiency regarding unmanaged traffic to the AP.

[0027] When an AP preempts multiple communication channels (typically 20MHz wide), all control frames, including the trigger frame, are copied on each preempted channel. This is so that legacy sites operating on any of these channels can set their NAV.

[0028] The 802.11ax standard considers several types of trigger frames to trigger various information items to a site. For example, a trigger frame can be used to retrieve uplink data traffic stored in a site's traffic queue. In another example, a trigger frame can be used to request a Buffer Status Report (BSR) from a site to determine which 802.11ax sites are holding uplink packets awaiting transmission and the associated size of these uplink packets (the amount of data in the site's traffic queue).

[0029] 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 caused by simultaneous media access attempts, while also reducing the overhead associated with media access (because the cost of media access is shared among several sites). 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).

[0030] 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.

[0031] This is primarily due to the existence of legacy 802.11 sites, which must still have access to the media without being aware of OFDMA or RU access schemes. Furthermore, overall fairness in access to the media must be ensured.

[0032] 802.11ax sites should also have the opportunity to access the media via traditional EDCA contention-based media access, such as sending data directly to another site (i.e., peer-to-peer [P2P] service, which is different from uplink service to the AP), which is even more necessary.

[0033] Therefore, the EDCA and OFDMA / RU access schemes, the two media access schemes, must coexist.

[0034] This coexistence has drawbacks.

[0035] For example, 802.11ax sites and legacy sites using the EDCA access scheme have the same media access probability. However, 802.11ax sites using the MU uplink or OFDMA or RU access scheme have additional media access opportunities.

[0036] This results in media access not being entirely fair between 802.11ax sites and legacy sites.

[0037] To restore some degree of fairness among stations, a solution is proposed as follows: when data is successfully transmitted via the accessed resource unit (i.e., via MU UL OFDMA transmission), the current value of at least one EDCA parameter is modified to a penalty or degradation value to reduce the probability of a station competing for access to the communication channel again via EDCA. For example, the penalty or degradation value used for the EDCA parameter should be more restrictive than the original (or conventional) value.

[0038] For example, it is proposed that when data is successfully transmitted (MU ULOFDMA) in a resource unit (RU) reserved by the AP for an 802.11ax site, the 802.11ax site switches to MU EDCA mode and continuously uses a timer (hereinafter referred to as HEMUEDCATimer, representing a high-efficiency multi-user EDCA timer) to count down for a predetermined duration. In this MU EDCA mode, the set of EDCA parameters for the site has been modified (specifically, penalized) to reduce the probability that the site will access the communication channel again through the EDCA access scheme.

[0039] The penalty or degradation value for the set of MU EDCA parameters is provided by the AP in a dedicated information element (usually in a beacon or associated frame).

[0040] The method disclosed in this paper suggests increasing the AIFSN value only for each traffic queue transmitted in the accessed RU, while maintaining CW. min and CW max Unchanged. With the increase of the corresponding AIFS time period, it essentially delays the decrementing of the queue backoff counter in the MU EDCA mode when the service queue detects the medium as idle. This is particularly noticeable in high-density environments where the medium has not remained idle for extended periods.

[0041] When switching to MU EDCA mode, the site begins its HEMUEDCATimer countdown. Regardless of the service queue from which the transmitted data originates, HEMUEDCATimer is reinitialized each time the site successfully transmits data in a newly reserved RU (MU UL OFDMA). 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.

[0042] The HEMUEDCATimer mechanism means that as long as the AP provides the reserved RU to the site, the site remains in the MUEDCA state.

[0043] 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.

[0044] Therefore, this dual working mode (traditional EDCA mode and MU EDCA mode) mechanism promotes the use of the MU UL mechanism by reducing the probability that sites in MU EDCA mode will use the traditional EDCA mechanism to access the media.

[0045] Additionally, this paper proposes providing a specific value for the AIFSN parameter in the set of degradation / penalty parameters provided by the AP. This specific value indicates to the site that a very high value should be used for the AIFSN of the service queue of interest.

[0046] As described in the literature, the very high value of AIFSN is equal to the HEMUEDCATimer value, which is also provided by AP. Typically, the HEMUEDCATimer timer value is around tens of milliseconds, compared to less than 0.1 milliseconds for the worst AIFS[i] in the traditional EDCA model.

[0047] The suggestion is to use a specific value for the AIFSN parameter, where "0" is used. Since this value is generally not allowed for AIFSN (because AIFSN must be at least equal to DIFS), this value is directly detected by the site as part of the code used to set AIFSN using HEMUEDCATimer.

[0048] The result of this scheme is that service queues in the MU EDCA mode are granted transmission opportunities less frequently through EDCA contention. Therefore, it is clear that using the code value (currently "0") aims to make EDCA access to these service queues less frequent. On the other hand, this simplifies processing at the AP, eliminating the need to calculate the associated penalty AIFSN value.

[0049] However, by preventing the backoff counters from evolving when the site uses the penalty MU EDCA parameter, this mechanism makes the queue backoff counters no longer reflect which traffic queue should have the highest transmission priority in the traditional EDCA sense (e.g., the earliest data stored internally). For example, if a site receives a trigger frame with a scheduled RU dedicated to that site, a site with frozen backoff counters can no longer use those backoff counters to process the site's QoS and send data with the highest priority (not only regarding the site's access class, but also regarding the corresponding age of the data in the AC[] queue).

[0050] Therefore, the QoS in the network is severely degraded, and it is necessary to reintroduce appropriate QoS operations for service prioritization, which will be adapted to the media access penalty scheme envisioned in the 802.11ax standard. Summary of the Invention

[0051] This invention seeks to overcome the aforementioned concerns. In particular, this invention seeks to overcome the loss of QoS processing caused by the introduction of MU UL OFDMA transmission.

[0052] With the introduction of 802.11e, data priority is handled along with the four access class traffic queues via the EDCA backoff mechanism. Since the EDCA backoff counter does not evolve when transmitting data on the MU UL OFDMA resource unit, the introduction of MU UL OFDMA communication disrupts the ability of the EDCA backoff counter to reflect the relative priorities of the four AC traffic queues.

[0053] Therefore, the present invention aims to restore some EDCA-like behavior to the queue backoff counter for the purpose of restoring the relevant reflection of the relative priority of the AC queue.

[0054] In this context, the present invention provides a communication device, comprising:

[0055] A receiving component for receiving signals transmitted from a base station constructing a wireless network conforming to the IEEE 802.11 series of standards, the signals including information related to AIFSN values; and

[0056] A control unit is used to control the acquisition of access category data for Enhanced Distributed Channel Access (EDCA) to the wireless network without transmitting the data in the case that the AIFSN value included in the signal received by the receiving unit is zero.

[0057] Conversely, a communication method is also proposed, in which the station performs the following:

[0058] Receive signals transmitted from a base station constructing a wireless network conforming to the IEEE 802.11 series of standards, the signals including information related to AIFSN values; and

[0059] Control is performed such that, when the AIFSN value included in the signal received by the receiving component is zero, data on the access category of Enhanced Distributed Channel Access (EDCA) access to the wireless network is obtained without transmission via the wireless network.

[0060] Other embodiments of the present invention provide a communication method in a communication network, the communication network including multiple stations, at least one station including multiple service queues for serving data services according to different priorities, each service queue being associated with a corresponding queue backoff counter to compete for access to a communication channel in order to transmit data stored in that service queue.

[0061] The communication method includes:

[0062] At the station,

[0063] The queue backoff counter is decremented as time passes, provided that the communication channel is (typically continuously) detected as idle (free or available) for a period exceeding the corresponding Arbitration Inter-Frame Spacing (AIFS) duration. This means that each service queue detects the medium as idle during the corresponding AIFS period before decrementing its backoff counter at each new consecutive time slot when the network is still detected as idle.

[0064] When data stored in any traffic queue is transmitted (preferably successfully) by the access point within the transmission opportunity granted to the access point on the communication channel in the accessed resource unit provided by the access point, the traffic queue is switched from conventional contention mode to MU contention mode; and

[0065] When one of the queue backoff counters expires (i.e., expires, for example, reaches zero), a determination is made based on the current (i.e., at the time of expiration) mode of the associated service queue to either access the communication channel to transmit data stored in the associated service queue, or to extract a new backoff value to reset the expired queue backoff counter if no data from the associated service queue is transmitted in the communication channel.

[0066] These embodiments can restore the decrementing of the backoff counter while still maintaining the penalty scheme envisioned in the 802.11ax standard. Therefore, the aging of data in the traffic queue can be restored, thereby restoring QoS.

[0067] Once the backoff counter expires, this is achieved through the proposed control of media access. In contrast to existing preventative measures to avoid backoff counter expiration, the proposed solution is a reactive countermeasure to the backoff counter reaching zero. Thus, the dynamic behavior of the backoff counter can be re-realized.

[0068] The results of these embodiments include the fact that the backoff counter can again reflect the aging of data in the AC, and also the fact that the restrictive AIFSN value is no longer needed.

[0069] Accordingly, these embodiments also provide a communication station in a communication network, the communication network including a plurality of stations, the communication station including:

[0070] Multiple service queues are used to serve data services according to different priorities. Each service queue is associated with a corresponding queue backoff counter to compete for access to the communication channel in order to transmit the data stored in that service queue; and

[0071] At least one microprocessor is configured to perform the following steps:

[0072] The queue backoff counter is decremented over time as long as the communication channel is detected as idle for a period exceeding the corresponding arbitration inter-frame gap duration.

[0073] When transmitting data stored in any traffic queue within an access resource unit provided by the access point during a transmission opportunity granted to the access point on the communication channel, the traffic queue is switched from conventional contention mode to MU contention mode; and

[0074] When one of the queue backoff counters expires, a decision is made based on the current mode of the associated service queue to determine whether to access the communication channel to transmit data stored in the associated service queue, or to extract a new backoff value to reset the expired queue backoff counter if no data from the associated service queue is transmitted in the communication channel.

[0075] This site has the same advantages as the methods defined above.

[0076] Optional features of the invention are defined in the appended claims. Some of these features are described below with reference to other methods, and these features can be adapted to system features specific to any communication site according to the invention.

[0077] In this embodiment, if the current mode is a traditional contention mode, the site accesses the communication channel to transmit data stored in the associated service queue.

[0078] If the current mode is MU contention mode, then a new backoff value is extracted to reset the due queue backoff counter if no data from the associated service queue is transmitted in the communication channel.

[0079] This ensures that the penalty scheme envisioned in the 802.11ax standard is maintained: the EDCA scheme continues to function even after the associated backoff counter for dynamics has expired, while media access to the service queue is not permitted in MU EDCA. This is the control provided by this invention.

[0080] In some embodiments, the determination of whether to access the communication channel or extract a new backoff value is further based on the data currently stored in the associated service queue. Specifically, for the purpose of maintaining QoS fairness for data unrelated to MU UL transmissions, this method allows the penalty scheme to be adjusted for certain types of data.

[0081] Depending on specific characteristics, if the current mode is a traditional competition mode, or if the data stored in the associated service queue includes data that needs to be addressed to another site different from the access point (i.e., the data is P2P data), then the site accesses the communication channel to transmit the data stored in the associated service queue.

[0082] If the current mode is MU contention mode and the data stored in the associated service queue does not include data to be addressed to another site different from the access point, then a new backoff value is extracted to reset the expiration queue backoff counter if no data from the associated service queue is transmitted in the communication channel.

[0083] In this configuration, QoS fairness is maintained for P2P services because they do not involve MU UL transmissions to the AP. In other words, even if the site is in MU EDCA mode for the same AC, this invention allows EDCA access to the medium for P2P data.

[0084] In this context, it can be specified that, in the case of access to a communication channel, only data stored in the associated traffic queue in the MU contention mode and addressed to another site different from the access point will be transmitted in the accessed communication channel. This means that only P2P data is allowed in traditional EDCA access, while the site (or the corresponding AC) is in MU EDCA mode.

[0085] In some embodiments, the MU contention mode uses the same arbitration inter-frame gap duration as the conventional contention mode. Due to the reactive approach of the present invention, control over media access in the penalty scheme no longer relies on contention parameters, but primarily on additional testing of the current mode when any backoff counter expires. As a result, modification of the AIFSN is no longer required, and therefore the AP no longer needs to transmit the modified AIFSN value. Consequently, processing at the site and AP is reduced, and bandwidth usage for transmitting the EDCA parameters for penalty transmission is also reduced.

[0086] In a particular embodiment, the backoff counters of each queue are reset using the associated backoff value extracted from the corresponding contention window, and

[0087] MU competition mode uses the same lower bound CW as traditional competition mode. min and / or the same upper boundary CW max The lower boundary CW min and upper boundary CW max These two factors define the range of choices for selecting the size of the competition window.

[0088] This configuration simplifies entering and exiting MU contention modes (e.g., MU EDCA mode) because the contention window remains unchanged. However, variations can be considered where there are different boundaries between conventional contention modes and MU contention modes.

[0089] In some embodiments, the method further includes: at the site, when a MU mode timer (referred to in the standard as HEMUEDCATimer) initialized when a traffic queue switches to MU contention mode expires, switching the traffic queue back to traditional contention mode. Depending on specific characteristics, the MU mode timer is shared by all traffic queues and is reinitialized to a predetermined duration whenever data from any traffic queue is transmitted in an accessed resource unit provided by the access point during any subsequent transmission opportunity on the communication channel. This means that if no data from the site is transmitted in any RU provided by the AP during a subsequent transmission opportunity, all traffic queues in MU contention mode exit MU contention mode upon the expiration of the predetermined duration.

[0090] In some embodiments, the data transmitted in the resource unit provided by the access point within the transmission opportunity granted to the access point is retrieved from at least one service queue selected based on the current (i.e., when accessing the medium) backoff value of the associated queue backoff counter.

[0091] Therefore, fair management of QoS is maintained in implementing this invention.

[0092] Based on specific characteristics, the business queue selects the business queue with the lowest current backoff value. This maintains the EDCA-like behavior of the AC queue.

[0093] In an alternative embodiment, the data transmitted in the resource unit provided by the access point within the transmission opportunity granted to the access point is retrieved from the preferred service queue indicated by the access point.

[0094] Based on specific characteristics, the preferred service queue indication is included in the trigger frame received from the access point, which reserves the transmission opportunity granted to the access point on the communication channel and defines the resource unit (RU) that forms the communication channel including the accessed resource unit.

[0095] This method enables the AP to drive QoS management.

[0096] In other embodiments, a reset flag is associated with each service queue, wherein the reset flag is enabled whenever a new backoff value is drawn to reset the associated queue backoff counter when no data is transmitted from the service queue, and the reset flag is disabled whenever data is transmitted from the service queue.

[0097] The data transmitted in the resource unit provided by the access point within the transmission opportunity granted to the access point is retrieved from at least one service queue selected based on the enabled or disabled state of a reset flag associated with the service queue.

[0098] Preferably, the data transmitted in the resource unit provided by the access point within the transmission opportunity granted to the access point is retrieved from the service queue with an enabled reset flag.

[0099] These configuration reset flags store QoS information related to the service queues. In practice, due to the extraction of new backoff values, the priority of a service queue may be lost compared to other service queues (because in this case, no data is transmitted in MU EDCA mode during the re-extraction of the new backoff value). Therefore, reset flags are used to indicate which service queues have priority data that should be urgently transmitted when accessing the RU.

[0100] In some embodiments, the method further includes: at the site, calculating a new backoff value for at least one service queue being transmitted in the accessed resource unit to reset the associated queue backoff counter.

[0101] This method restores fairer QoS management because it applies the same behavior as traditional EDCA (a new backoff value for the traffic queue each time a transmission occurs).

[0102] In a particular embodiment, a new backoff value is calculated only for the transport queue from which the data transmitted at the beginning of the accessed resource unit originates. Typically, it is assumed that the first transport queue transmits the majority of the data in the accessed resource unit. Other transport queues send only a small amount of data to fill the available bandwidth in the accessed resource unit (assuming a TXOP). In this respect, extracting a new backoff value for these “secondary” queues is highly likely to corrupt the remaining data in these queues, thus requiring a longer wait time compared to direct OFDMA access. As a result, the proposed implementation maintains fairness regarding these secondary queues by preserving the same future transmission probability for each queue.

[0103] In a variation, a new queue backoff value is calculated for each transport queue. Since the application behaves exactly like traditional EDCA, fair QoS management is achieved.

[0104] In some embodiments, a backoff value for resetting the queue backoff counter is calculated based on a set of contention parameters associated with the respective service queue, and

[0105] The method further includes, at the site, resetting the set of contention parameters associated with (preferably, each) service queues that remain in MU contention mode for at least the parameter lifetime duration to a default set. For example, the parameter lifetime duration may correspond to at least twice the predetermined duration used to initialize the MU mode timer (HEMUEDCATimer).

[0106] This helps improve network efficiency. In fact, because the traffic queue of interest remains in MU contention mode for an extended period, its contention parameters (typically EDCA parameters) no longer reflect the actual network conditions. Therefore, resetting these contention parameters erases any old network constraints that might have been embedded within them. Without any knowledge of the network conditions, it's as if the traffic queue is a new one in the network.

[0107] In other embodiments, the method further includes, at the site, after data stored in the associated service queue has been transmitted in the accessed communication channel, extracting a new backoff value to reset the due date queue backoff counter. Thus, the traditional EDCA scheme is maintained when the site or service queue is in a traditional EDCA contention mode.

[0108] In other embodiments, the method includes: at a station, receiving a trigger frame from an access point, the trigger frame reserving a transmission opportunity on a communication channel granted to the access point, and defining at least one resource element (RU) (preferably multiple) forming a communication channel including the accessed resource element. This follows standard requirements for declaring RUs.

[0109] In other embodiments, the transmission queue switches to MU contention mode only when data is successfully transmitted within the accessed resource unit. This structure ensures fairness. In practice, in a contention mode switching system, only a penalty MU contention mode should be implemented to compensate for the existence of other transmission opportunities (here via RU), meaning that data has been successfully transmitted.

[0110] In other embodiments, the accessed resource unit through which the data is transmitted is a random resource unit, wherein the random resource unit is accessed by competition using a separate set of RU contention parameters from the contention parameter set used to extract backoff values ​​to reset the queue backoff counter.

[0111] 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 site by the access point.

[0112] Of course, some stations can access the scheduled RU, while other stations can access the random RU at the same time, which makes it possible to have various stations in MU contention mode (for one or more AC queues) at the same time.

[0113] 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.

[0114] Non-transitory computer-readable media may have features and advantages similar to those stated above and below in relation to the methods and apparatus.

[0115] 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.

[0116] 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

[0117] 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.

[0118] Figure 1 This diagram illustrates a typical wireless communication system that can implement embodiments of the present invention;

[0119] Figure 2a The IEEE 802.11e EDCA is shown, which involves access categories;

[0120] Figure 2b An example showing the mapping between the eight priorities of a business class and the four EDCA ACs;

[0121] Figure 2c This illustrates the 802.11e mechanism for the backoff counter countdown;

[0122] Figure 2d This shows the structure of the MAC data frame header;

[0123] Figure 3 This demonstrates 802.11ac channel allocations supporting composite channel bandwidths of 20MHz, 40MHz, 80MHz, or 160MHz as known in the prior art;

[0124] Figure 4An example of an 802.11ax uplink OFDMA transmission scheme is shown using a timeline, in which the AP issues a trigger frame to reserve a transmission opportunity for an OFDMA resource unit on an 80MHz channel known in the art.

[0125] Figure 5a An exemplary scenario of conventional transmission of a trigger frame using the EDCA mechanism is shown, in which penalty schemes known in the prior art can be applied;

[0126] Figure 5b This illustrates an exemplary evolution of backoff counters and associated data selection known in the prior art;

[0127] Figure 5c This illustrates the evolution of the backoff counter and associated data selection according to embodiments of the present invention;

[0128] Figure 6 A schematic representation of a communication device or station according to an embodiment of the present invention is shown;

[0129] Figure 7 A block diagram illustrating the architecture of a wireless communication device according to an embodiment of the present invention is shown schematically.

[0130] Figure 8 An exemplary transport block of a communication station according to an embodiment of the present invention is shown;

[0131] Figure 9 The flowchart illustrates the main steps performed by the MAC layer of a station when new data to be transmitted is received, as described in an embodiment of the present invention.

[0132] Figure 10 A flowchart is used to illustrate the steps of accessing media using an EDCA-based media access scheme according to an embodiment of the present invention.

[0133] 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.

[0134] Figure 12 A flowchart is used to illustrate site management according to an embodiment of the present invention for switching back (or back) from MU competition mode to conventional competition mode;

[0135] Figure 13 This shows the structure of a trigger frame as defined in the 802.11ax standard;

[0136] Figure 14a This illustrates the structure of the standardized information elements used to describe the parameters of EDCA in a beacon frame; and

[0137] Figure 14b 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

[0138] The invention will now be described using specific, non-limiting exemplary embodiments and with reference to the accompanying drawings.

[0139] Figure 1 A communication system is illustrated, in which multiple communication stations (or nodes) 101–107 exchange data frames via a wireless transmission channel 100 of a wireless local area network (WLAN), under the management of an access point (AP) 110, which is also considered a network station. 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.

[0140] In the following text, the term "site" refers to any type of site. The term "access point site" or simply "access point" (AP) refers to a site that acts as an access point 110. The term "non-access point site" or simply "non-AP site" or client site (STA) refers to other sites 101-107.

[0141] Accessing the shared wireless medium to send data frames is primarily based on CSMA / CA technology, which listens for carriers and avoids collisions by separating concurrent transmissions in space and time.

[0142] 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.

[0143] Next, before transmitting data frames, the source or transmission station 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.

[0144] However, if the shared wireless medium is detected to be busy during the DIFS period, the source site continues to wait until the wireless medium becomes idle.

[0145] Figure 1 The wireless communication system includes a physical access point 110, which is configured to manage a WLAN BSS (Basic Service Set), i.e., a group of non-AP sites previously registered to the AP. This type of BSS managed by the AP is referred to as an infrastructure-type BSS. In the following text, the term BSS will be used as an equivalent of infrastructure-type BSS.

[0146] Once a BSS is established, access points can bridge services within the BSS or from other networks (e.g., wired networks) to the BSS (or vice versa). Therefore, BSS sites should only communicate with the AP responsible for relaying these data frames when the data frames are directed to another site within the BSS.

[0147] To access the medium, any site, including the AP, begins a countdown of a backoff counter that is designed to expire after multiple 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 time expires (i.e., the backoff counter reaches zero), the source site can transmit data or control frames while the medium is idle.

[0148] Quality of Service (QoS) management has been introduced at the site level in wireless networks through the well-known EDCA mechanism defined in the IEEE 802.11e standard.

[0149] In fact, in the original DCF standard, communication stations 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.

[0150] Figure 2a The IEEE 802.11e EDCA mechanism involving access categories is shown, thereby improving Quality of Service (QoS) for more efficient use of the wireless medium.

[0151] 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).

[0152] 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.

[0153] EDCA (Electronic Data Access Control) is an important channel access scheme or mechanism in WLANs due to its distributed and easily deployable characteristics. This scheme uses EDCA contention parameters to compete for access to at least one communication channel in the communication network, allowing stations to transmit locally stored data on the accessed channel.

[0154] The aforementioned deficiency of unsatisfactory QoS due to frame retransmission delays has been addressed by utilizing multiple transmission queues / buffers.

[0155] 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").

[0156] Of course, another number of business queues can also be considered.

[0157] 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.

[0158] 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 refers to the lower and upper boundaries of the selection range for the EDCA contention window CW for a given traffic queue. AIFSN represents the number of arbitration inter-frame gaps and defines the sum of the AIFS time intervals (excluding the SIFS interval – see [link]). Figure 2b The number of time slots (typically 9 μs) that a site must listen for as idle before decrementing the queue backoff counter associated with the considered traffic queue. TXOP_Limit defines the maximum size of TXOPs a site can request.

[0159] 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 initialize a corresponding queue backoff counter using queue contention parameters and (from the CW) extracting backoff values, thereby competing for access to at least one communication channel for transmitting data stored in each traffic queue on the accessed communication channel.

[0160] The competition window (CW) and the backoff value are referred to as EDCA variables.

[0161] This causes ACs within the same communication site to compete with each other for access to the wireless medium and to obtain transmission opportunities using, for example, the conventional EDCA access scheme described above.

[0162] 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.

[0163] Using different AIFSN values ​​(to delay the decrement of the backoff counter) in addition to using a lower average CW makes high-priority traffic in EDCA more likely to be transmitted than low-priority traffic: on average, sites with high-priority traffic wait less before sending packets than sites with low-priority traffic.

[0164] refer to Figure 2a The four AC buffers (210) shown, with buffers AC3 and AC2 typically reserved for real-time applications (e.g., voice AC_VO or video transmission AC_VI). These buffers have the highest priority and the second-to-last highest priority, respectively.

[0165] 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.

[0166] 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 2b An example is shown of the mapping between eight priority service classes (user priorities or UP, ranging from 0 to 7 according to IEEE 802.1d) and four ACs. The data frames are then stored in buffers corresponding to the mapped ACs.

[0167] For example in Figure 2c The effects of different AIFSNs are shown in the figure.

[0168] Each site must wait a fixed amount of time to ensure the medium is idle before attempting a transmission. With DCF, DIFS is constant for all types of traffic. However, with 802.11e, the fixed amount of time a site must wait depends on the access class and is called Arbitrated Inter-Frame Gap (AIFS).

[0169] Using AIFS, each service queue "i" waiting to transmit must wait until the medium is declared available via Idle Channel Assessment (CCA) and Network Allocation Vector (NAV) (these two are not discussed here for brevity). Once the medium is available, each service queue "i" must wait (including the SIFS time period for which access to the medium is postponed) for the corresponding AIFS[i] time period before its associated queue backoff counter is decremented.

[0170] Therefore, each of the four service queues has a defined inter-frame gap value corresponding to the priority assigned to that queue. For example, the AC_VO queue has the highest priority and therefore has the lowest inter-frame gap timer. All AIFS timers (250) assigned by IEEE 802.11e are defined as one short inter-frame gap (SIFS) value plus a variable number of slot times (AIFSN) defined by the physical layer coding method in use (CCK, DSSS, OFDM). The value of the EDCA parameter AIFS number (AIFSN) is configurable by the administrator, with the default value defined as follows:

[0171] AC_VO 1SIFS+2*timeslot(AIFSN=2)

[0172] AC_VI 1SIFS+2*timeslot(AIFSN=2)

[0173] AC_BE 1SIFS+3*timeslot(AIFSN=3)

[0174] AC_BG 1SIFS+7*timeslot(AIFSN=7)

[0175] The AIFSN value can be provided by the AP in a so-called EDCA parameter set information element (e.g., in a beacon frame sent by the AP). The AIFSN field in this information element is four bits long, with a minimum value of 2 as defined in the standard and a maximum value of 15 based on the field length limit.

[0176] In this way, the arbitration inter-frame gap allows for the statistical advantage of frames in higher-priority service queues, because these frames do not need to wait too long relative to other queues before decrementing their random backoff counters.

[0177] This diagram illustrates two AIFS[i] corresponding to two different traffic queues. It can be seen that, due to this priority difference, a higher-priority traffic queue begins to decrease its backoff value earlier than a lower-priority traffic queue. This process repeats after each new medium access is made using any station in the network (i.e., when the medium is relistened to be idle).

[0178] To initiate data transmission, service queues within a site first randomly select a backoff value for their backoff counters. As explained above, the backoff value must be within the contention window defined for that service queue. Similar to the AIFS parameters, the differences in contention windows between various service queues are used to prioritize services within those queues by allowing higher-priority queues to wait for shorter time intervals before being permitted to transmit over-the-air.

[0179] Once the appropriate AIFS[i] time period expires, each service queue can begin to decrement its queue backoff counter (251) by 1 for each time slot that has passed.

[0180] Next, when the EDCA backoff process for the service queue (or AC) ends (at least one backoff counter reaches zero), the MAC controller of the transmission station (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.

[0181] Because traffic queues operate concurrently when accessing the wireless medium, it is possible for two traffic queues at the same communication site to simultaneously terminate their backoff. In this situation, the virtual collision handler (212) of the MAC controller operates between conflicting ACs (such as...). Figure 2b (As shown) The AC with the highest priority is selected, and data frames are abandoned from the AC with the lower priority.

[0182] Then, the virtual conflict handler commands the AC with lower priority to start the backoff operation again using an increased CW value.

[0183] Figure 2d The diagram illustrates the structure of the QoS control field 200 included in the header of a MAC data frame and an IEEE 802.11e MAC frame. Among other fields, the MAC data frame also includes a frame control header 201 and a frame body 202. As shown in the figure, the QoS control field 200 consists of two bytes, which include the following information items:

[0184] Bits B0 to B3 are used to store the Service Identifier (TID) 204, which identifies the service flow. The service identifier uses the transmission priority value (user priority UP, a value between 0 and 9) corresponding to the data transmitted by the data frame. Figure 2b The value of ) or the value of the Service Flow Identifier (TSID) used for other data flows (a value between 8 and 15);

[0185] - Bit B4 is used by non-AP sites to distinguish the meaning of bits B8 to B15, and will be described in detail below;

[0186] Bits B5 and B6 define the ACK policy subfield, which specifies the acknowledgment strategy associated with the data frame. This subfield determines how the receiving station must acknowledge the data frame: normal ACK, no ACK, or block ACK.

[0187] Bit B7 is reserved, meaning it is not used in the current 802.11 standard; and

[0188] - If bit B4 is set to 1, bits B8-B15 represent the "Queue Size" subfield 203, indicating the buffered traffic volume for a given TID at the non-AP site that sent the frame. The queue size is the total size of all packets buffered for the specified TID, rounded up to the nearest multiple of 256 octets and expressed in 256 octets. The access point receiving the frame can use this information to determine the duration of the next TXOP that the access point will grant to the site. A queue size of 0 indicates that there is no buffered traffic for that TID. A queue size of 255 indicates that the size of TID 204 is unspecified or unknown.

[0189] - As an alternative to "Queue Size", if bit B4 is set to 0, bits B8-B15 represent the "Requested TXOP Duration" subfield. This instructs the sending station to determine the duration, in 32 μs, required for the next TXOP for the specified TID. Of course, "Requested TXOP Duration" provides an equivalent request to "Queue Size," as both take into account all packets buffered for the specified TID.

[0190] For the latest version of the standard as described now, the 802.11e MAC frame format has been maintained, and more specifically, the QoS control field 200 has been retained.

[0191] 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 3 This shows the 802.11ac channel allocation that supports composite channel bandwidths of 20MHz, 40MHz, 80MHz, or 160MHz.

[0192] IEEE 802.11ac introduced support for a limited number of predefined subsets of 20MHz channels to form dedicated predefined composite channel configurations reserved for data transmission at any 802.11ac site on a wireless network.

[0193] 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.

[0194] 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.

[0195] 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).

[0196] On the "primary channel" (300-3), TXOPs are granted to sites 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 client sites (STAs) belonging to the same basic set, i.e., managed by or registered to the same local access point (AP).

[0197] However, in order to ensure that other legacy sites (i.e., legacy sites not belonging to the same set) do not use the secondary channel, it is proposed to replicate the control frames (e.g., RTS frames / CTS frames) that preserve the composite channel on each 20MHz channel in the composite channel.

[0198] 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.

[0199] The development of the 802.11ax standard aims to enhance the efficiency and usability of wireless channels in dense environments.

[0200] From this perspective, multi-user (MU) transmission characteristics can be considered, allowing for multiple simultaneous transmissions relative to different users at the access point 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 non-AP sites to transmit to the AP simultaneously.

[0201] To practically implement such multi-user transmission, it has been proposed to divide the allocated 20MHz channel (400-1 to 400-4) into at least one sub-channel, but preferably multiple sub-channels 410 (basic sub-channels) (also referred to as subcarriers or resource units (RUs) or “traffic channels”), in which multiple users share these sub-channels 410 in the frequency domain, for example based on orthogonal frequency division multiple access (OFDMA) technology.

[0202] refer to Figure 4 This situation is shown.

[0203] In this example, each 20MHz channel (400-1, 400-2, 400-3, or 400-4) is subdivided in the frequency domain into four OFDMA subchannels or RUs 410, each with a size of 5MHz. 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 thus each with a size of 10MHz to approximately 2MHz). The RU width can also be greater than 20MHz when the RUs are included within a wider composite channel (e.g., 80MHz).

[0204] In contrast to MU downlink OFDMA (where the AP can directly send multiple data to multiple sites (supported by specific indications within the PLCP header)), a triggering mechanism has been adopted for APs to trigger MU uplink communication from each non-AP site.

[0205] To support MU uplink transmission (during AP-preempted TXOP), the 802.11ax AP must provide signaling information for two legacy sites (i.e., non-802.11ax sites) to set their NAV and for the 802.11ax client sites to determine the resource unit allocation.

[0206] In the following description, the term "conventional" refers to a non-802.11ax site, which means an 802.11 site that does not support prior technology for OFDMA communication.

[0207] like Figure 4As shown in the example, the AP sends a trigger frame (TF) 430 to a target 802.11ax site. 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. Due to the copying of the control frame, it can be expected that nearby legacy sites receiving 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 sites from accessing the channels in the target composite channel during the TXOP.

[0208] Based on the AP's decision, the trigger frame TF can define multiple Resource Units (RUs) 410. The multi-user feature of OFDMA allows the AP to assign different RUs to different client sites to increase contention. This can help reduce contention and collisions within an 802.11 network.

[0209] As already discussed, an RU with a width greater than 20MHz can be defined: as an example, an AP can provide an RU with 996 frequencies to cover an 80MHz communication channel, thus being equivalent in capacity to single-user 80MHz communication. Therefore, it can be noted that such 80MHz communication, in the sense that it is triggered by a trigger frame issued by the AP, maintains MU UL communication within the RU.

[0210] Trigger frame 430 can specify "scheduled" RUs, which can be reserved by the AP for certain sites, in which case no contention for access to these RUs is required for these sites. These RUs and their corresponding scheduled sites are indicated in the trigger frame. For example, site identifiers (such as the association ID (AID) assigned to each site upon registration) are added in a manner associated with each scheduled RU to explicitly indicate the sites allowed to use each scheduled RU. This transmission mode is concurrent with the conventional EDCA mechanism, and uplink data to be sent to the AP is retrieved from EDCA queue 210.

[0211] In addition to or as a substitute for the "scheduled" RU, the trigger frame TF can also specify a "random" RU. A random RU can be randomly accessed by stations on the BSS. In other words, the random RU specified or assigned by the AP in the TF can serve as the basis for contention between stations intending to access the communication medium to send data. A collision occurs when two or more stations attempt to transmit simultaneously on the same RU. A random RU can be identified using an AID equal to 0.

[0212] Based on the additional backoff counters (OFDMA backoff counter, or OBO counter, or RU counter) used by 802.11ax non-AP sites for RU contention, a random allocation process can be considered for the 802.11ax standard, i.e., to allow these 802.11ax non-AP sites to compete among themselves for access to and transmission of data on a random RU. The RU backoff counter differs from the EDCA backoff counter. However, it is assumed that the data transmitted in the accessed OFDMA RU 410 is provided from the same EDCA traffic queue 210.

[0213] The RU random allocation process, for multiple 802.11ax sites with positive RU backoff values ​​(initially drawn within the RU contention window), includes the following steps: A first step, for determining the sub-channel or RU (so-called "random RU") contending for available communication medium based on a received trigger frame; a second step, for verifying that the RU backoff value local to the considered site is not greater than the number of randomly detected available RUs; then, if the verification is successful, a third step, for randomly selecting an RU from the detected available RUs and then transmitting data. If the second step is not verified, a fourth step (instead of the third step) is performed to decrement the RU backoff counter according to the number of randomly detected available RUs.

[0214] It can be noted that OFDMA transmission on random RUs is not guaranteed for each received TF. This is because, at least at each reception of the trigger frame, the RU backoff counter decrements by the number of proposed random RUs, thus making the data transmission to subsequent trigger frames different (depending on the current value of the RU backoff count and the number of random RUs provided by each further received TF).

[0215] return Figure 4 From the various possible accesses to the RUs, we can see that some RUs will not be used (410u) because stations with a RU backoff value OBO less than the number of available random RUs do not randomly select one of these random RUs, while some other RUs will conflict (as in example 410c) (because at least two of these stations have randomly selected the same random RU). This shows that since the random RUs to be accessed are determined randomly, conflicts may occur on some RUs, while other RUs can remain idle.

[0216] Once a site uses scheduled and / or random RUs to transmit data to the AP, the AP responds using multi-user acknowledgments (not shown in the figure) to acknowledge the data on each RU.

[0217] Especially in the dense environments envisioned by the 802.11ax standard, 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 caused by media access are reduced.

[0218] However, the EDCA access scheme and the MU UL OFDMA / RU access scheme must coexist, especially allowing traditional 802.11 sites to access the media and even allowing 802.11ax sites to initiate communication with other non-AP sites.

[0219] While the standalone EDCA access scheme provides fair access to the medium across all sites, its association with the MUUL OFDMA / RU access scheme introduces a shift in fairness. This is because 802.11ax sites have additional opportunities to transmit data using the resource units provided within the transmission opportunities granted to the AP, compared to traditional sites.

[0220] Solutions have been proposed to restore some fairness between sites.

[0221] For example, in co-pending UK application 1612151.9 filed on 13 July 2016, when data is successfully transmitted via the accessed resource unit (i.e., via UL OFDMA transmission), the current value of at least one EDCA parameter is modified to a different value (MU EDCA parameter). This is to reduce the probability of a site competing for access to the communication channel via (conventional EDCA).

[0222] Within this framework, a method is proposed to immediately reduce the probability of a site's EDCA-based transmissions (i.e., using the EDCA Media Access scheme) when the site successfully transmits its data using the MU UL mechanism. This reduction is achieved by modifying the well-known EDCA parameter set (which is derived from AIFSN, CW...) min and CW max (Constitute) to carry out.

[0223] The proposed mechanism sets each transport queue to MU EDCA mode (or "MU mode") in response to successful data transmission in the accessed MU UL OFDMA resource unit. This setting is performed for a predetermined duration known as HEMUEDCA. MU EDCA mode is a mode that modifies each EDCA parameter set to a different MU parameter set than the conventional EDCA parameter sets used in different conventional EDCA modes.

[0224] To switch from the traditional EDCA contention access mode to the MU EDCA mode, a site can modify its EDCA parameter set (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 site transmits new data (from any AC) again during a new access 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.

[0225] Modified values ​​of the EDCA parameter set (i.e., the MU parameter set of the four service queues) can be transmitted by the access point in a dedicated information element (typically sent within a beacon frame that broadcasts network information to the site).

[0226] This document provides the following specific configuration: For transport queues in MU EDCA mode, EDCA access to the medium is preferred to be less frequent. 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 that the site should use a very high value for its AIFSN in MU EDCA mode, which should be 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] in traditional EDCA mode, which is less than 0.1 milliseconds).

[0227] Unfortunately, by drastically modifying the EDCA parameters, and especially the AIFSN value, known mechanisms for controlling fairness drift reduce the chance of queue backoff counters evolving (decreasing) for each service queue in MU EDCA mode. This reduces the efficiency of using these queue backoff counters in determining the relative priority of queues. In effect, the queue backoff value no longer reflects which service queue should have the highest transmission priority in the sense of EDCA (e.g., the earliest data stored internally).

[0228] Then, the site will no longer be able to comply with the QoS principles described in the 802.11e standard.

[0229] Now for reference Figure 5a Explain the situation, in which Figure 5aAn exemplary scenario of an 802.11ax network implementing the MU EDCA mode as described in the aforementioned literature is illustrated. In this scenario, the AP sends a completely random first trigger frame (meaning the AP only defines random RUs), followed by a completely scheduled second trigger frame (the AP only defines scheduled RUs), so that the AP polls stations with uplink data.

[0230] Since the receiver (access point) competes on behalf of non-AP sites in uplink OFDMA, the access point should know which non-AP sites have uplink packets and what the size of their buffer 210 is. In fact, polling non-AP sites without uplink packets for uplink OFDMA transmission wastes allocated resource units for MUUL OFDMA transmission, resulting in degraded use of the radio medium.

[0231] This standard proposes that buffer status reports from 802.11ax sites can be used to support efficient MU UL operation of access points. To this end, upon receiving a trigger frame 430-BSR containing a request indication for a buffer status report, the 802.11ax site responds with a frame that includes a queue size subfield 203 in the QoS control field 200. The buffer status report indication can be, for example, a "trigger type" provided within the trigger frame, and a specific value indicates this buffer status request. The trigger frame 430-BSR is considered a trigger frame for the site's response to the buffer status report (BSR).

[0232] Preferably, the trigger frame 430-BSR is broadcast by the AP to all sites of the BSS, and most or even all resource units are of random type to allow all sites to have a random opportunity to provide queue size reports. Additionally, to reach the maximum number of sites, the trigger frame 430-+BSR provides the maximum number of resource units, that is, requesting the widest communication channel with the narrowest resource unit size.

[0233] To minimize the duration of TXOP 490 for obtaining a buffer status report, frames transmitted within resource unit 410-BSR should be constrained and of uniform size to avoid inefficient padding. For example, a QoS_Null frame appears suitable for providing this constraint. This particular QoS data frame contains a QoS control field with queue size information but no data payload.

[0234] The current version of IEEE 802.11ax expands the use of queue size information 203 in the new QoS control field (i.e. HE control) (and possibly in the replacement of the QoS control field in 802.11ax frames) to notify the site of approximately and preferably all traffic queues 210 (instead of only one as proposed in the 802.11e standard).

[0235] Once an access point receives a buffer report of a set of sites from its BSS, it can then exclusively poll those sites via a scheduled resource unit allocation. This allocation is transmitted using a trigger frame 430-D for data transfer. The sites with the allocated resource units then transmit the data in a longer TXOP_TF. data During period 491, buffered data is transmitted within the allocated resource units 410-D at these stations. Since MU UL / DL OFDMA transmissions on all resource units of the composite channel must be time-aligned, a station may provide padding payload 411-D if no more data can be transmitted within the assigned resource unit. This may occur, for example, if there is no more buffered data for transmission, or if the transmitting station does not want to split any remaining data frames.

[0236] The access point can manage resource unit sizes based on reported site demand. The access point can schedule resource units during the TXOP period to any site that sent the report.

[0237] Once a site uses resource unit 410-D to transmit data to the access point, the access point responds with a multi-user acknowledgment 440 to acknowledge the data on each resource unit. This ACK ends the granted TXOP period.

[0238] Because the AP polls a given traffic queue and there is subsequent OFDMA transmission of data from that queue, subsequent OFDMA transmissions can switch to MU EDCA mode with AIFSN set to HEMUEDCATimer. Only other traffic queues (without active transmissions) can still use the EDCA scheme to access the communication channel.

[0239] When the AIFSN value provided by the AP (e.g., in the EDCA parameter set information of the beacon frame) is zero, data for the access category that enables EDCA access to the wireless network is not transmitted over the wireless network. This prevents service queues at the site in MUEDCA mode from accessing the medium.

[0240] In the example shown in the diagram, the AP polls station STA4 for the transmission of data from traffic queue AC_VI (time slot 410-D4). Due to the switch to MU EDCA mode, traffic queue AC_VI can no longer request EDCA access as long as HEMUEDCATimer has not expired. However, station STA4 can still request EDCA access to other traffic queues (until these traffic queues are provided in the next MU UL transmission if they occur). This is why traffic queue AC_VO in traditional EDCA mode can use EDCA access to actually access the communication channel and then clear itself via single-user transmission 495-SU (which is TXOP 492).

[0241] Figure 5b The above-mentioned penalty mechanism will be further elaborated.

[0242] In this diagram, the four values ​​530 represent the queue backoff counters BC[AC] (and their backoff values) associated with the four business queues 210. Graphical codes are used to distinguish the different states that the queue backoff counters can be in. These graphical codes are provided directly as a legend in the diagram.

[0243] In the first phase shown (each phase corresponds to the time period from when the network becomes available until the TXOP is granted), when BC[VI] reaches zero (the counter in the dashed box), station 502 accesses the medium via EDCA, while the optimal queue backoff value of AP 501 only reaches 4. The black portions 540 before the queue backoff value is decremented correspond to AIFS[AC] (the different sizes of these black portions 540 are not shown).

[0244] Then, during the granting of TXOP 550, video data is sent from AC[2] (i.e., the service queue of AC_VI). A new queue backoff value is extracted for AC_VI (white graphic in black box).

[0245] In the second phase, AP 501 first accesses the network after its AIFS 540 and its backoff value 710 countdown, and then sends trigger frame 1300. TF 1300 provides at least one scheduled RU for site 502.

[0246] TF 1300 does not indicate any preferred AC in the corresponding field. Figure 13 The preferred AC level field 1330 shown is set to 0). Therefore, station 502 needs to determine which AC queue has the highest priority for selecting the corresponding data used for MU UL OFDMA transmission.

[0247] Therefore, station 502 selects the AC queue with the lowest current backoff counter value. In this example, the first AC queue is selected because its associated queue backoff value (compared to 4, 6, and 12 for the other AC queues) is equal to 1.

[0248] Therefore, data from AC_VO can be transmitted (560) in the accessed resource unit.

[0249] Following a successful MU UL OFDMA transmission of data 560, the corresponding service queue enters MU EDCA mode, where a set of MU values ​​modifies the EDCA parameter set of the transmission service queue (here, AC_VO). The service queue in MU EDCA mode is shown in the diagram with a thick box.

[0250] During this second phase, the queue backoff counter 531 associated with the transport traffic queue AC_VO is frozen, meaning that the queue backoff counter 531 is not updated and retains its previous value (here, "1").

[0251] Therefore, the third phase begins as follows: Station 502 enters the delayed transmission state by waiting for the AIFS[i] timer (565) to end before decrementing the queue backoff value BC[i]530.

[0252] For traffic queues in MU EDCA mode with more restrictive EDCA parameters (such as very high AIFSN), the modified value of AIFS 565 makes the decrease of the corresponding queue backoff value BC[AC] less frequent. Therefore, when AP 501 sends a new trigger frame 1300-2 when performing EDCA-based access to the medium, the site 502 of the newly scheduled RU determines which traffic queue has the lowest current queue backoff value.

[0253] Again, this is a BC with a backoff value of 1[3]. This means that station 502 will again transmit (570) data from AC_VO in the visited RU.

[0254] Soon after, if several traffic queues, especially if all traffic queues enter MU EDCA mode, it will prevent the associated queue backoff value. Therefore, the same traffic queue used by MU UL OFDMA transmission will always take priority. Backoff-based QoS requirements will no longer be met.

[0255] The lack of dynamism in backoff counters caused by freezing in the case of MU UL OFDMA transmissions should be restored so that these backoff counters still efficiently reflect the relative priority of AC queues. Advantageously, this restoration should maintain the penalty scheme to reduce the probability of EDCA-based transmissions for AC queues in MU EDCA mode, and should also preserve the evolution principle of the backoff counters.

[0256] Within this framework, the present invention proposes to introduce reactive countermeasures when the backoff counter expires, while in particular maintaining the decrement of the queue backoff counter by not penalizing the AC queue's AIFSN.

[0257] It should be reiterated that as long as the communication channel is listened to as idle by the site for a period exceeding the corresponding arbitration inter-frame gap duration, the queue backoff counter decreases over time; when any data stored in a service queue is transmitted in the access resource unit provided by the access point within the transmission opportunity granted to the access point on the communication channel, the service queue switches from conventional contention mode to MU contention mode.

[0258] In order to efficiently restore the dynamics of the backoff counter while maintaining the penalty scheme, this invention proposes that when one of the queue backoff counters expires, the station determines, based on the current mode of the associated service queue, whether to access the communication channel to transmit the data stored in the associated service queue, or to extract a new backoff value to reset the expired queue backoff counter if no data from the associated service queue is transmitted in the communication channel.

[0259] In practice, if the current mode is the traditional contention mode, the station accesses the communication channel to transmit data stored in the associated traffic queue. This is the traditional EDCA scheme. Otherwise, if the current mode is the MU contention mode, a new backoff value is extracted to reset the expired queue backoff counter if no data from the associated traffic queue is transmitted in the communication channel.

[0260] A slight variation could be conceivable, such as making the decision regarding whether to access the communication channel or extract a new backoff value based on the data currently stored in the associated service queue. For example, in MU EDCA mode, if no data intended for non-AP sites is stored in the associated AC queue, a penalty of not transmitting data would be applied even if the backoff counter expires.

[0261] The recovery decrement of the backoff counter in the non-transmitting AC queue in MU mode ensures the recovery of the aging characteristics of the EDCA backoff counter, thereby guaranteeing QoS recovery. Therefore, EDCA backoff provides dual functionality and allows the application of relative QoS priorities among the AC queues at a site.

[0262] Additionally, the reactive strategy of resetting the expiration backoff counter without transmitting data in MU mode ensures that penalties are still applied to AC queues in this MU mode to reduce EDCA access.

[0263] Therefore, the present invention works in the opposite manner to known techniques, which are essentially preventative measures to avoid the backoff counter from reaching zero in order to ensure reduced EDCA access.

[0264] As will become further apparent, the method of the present invention is more readily implemented in standard environments, and particularly in the transmission state machine of an 802.11 device.

[0265] Now for reference Figure 5c To illustrate one implementation result of the present invention, wherein Figure 5c Utilization and Figure 5b The same sequence illustrates how QoS is recovered through relative EDCA-based priority between ACs.

[0266] The first phase remains unchanged.

[0267] During the second phase, site 502 receives TF 1300 from AP 501. The AC queue selection algorithm in the site determines that the service queue AC_VO has the highest priority due to the lowest queue backoff value (e.g., Figure 5b (as in the example). Data from AC_VO (AC[3]) was transferred via MU UL OFDMA.

[0268] After the successful transmission of data in the accessed RU 560, AC_VO enters MU EDCA mode (backoff value in the thick box), and embodiments of the present invention propose to select a new backoff value 531 (white number in the black box, which has the value "15") for the transmission traffic queue AC_VO from the current and unchanged associated contention window.

[0269] Furthermore, AIFS[AC_VO] remains unchanged when entering MU EDCA mode. This means that the penalty caused by MU mode is not applied through a downgrade of the EDCA parameter.

[0270] Next, in the third phase, the backoff counters are decremented taking into account their respective AIFS. Here, even when AC_VO is in MU mode, the backoff counter 531 of AC_VO is decremented by 1 for each time slot when the medium is detected as idle. This is due to the unmodified (or very slightly penalized in some embodiments) value of AIFS[AC_VO].

[0271] Again, station 502 receives TF 1300-2 from AP 501. The AC queue selection algorithm in this station determines that the service queue AC_VI has the highest priority due to the lowest queue backoff value (because BC[VO] now has a value of 14). Therefore, data from AC_VO undergoes MU UL OFDMA transmission in the accessed RU.

[0272] It can be noted that, with Figure 5b In contrast, due to the new backoff value 532 extracted to reset the AC_VO backoff counter, another service queue is requested for MU UL OFDMA transmissions in the third phase. Therefore, for OFDMA transmission service queues, the relative priorities between service queues are restored.

[0273] After the successful transmission of data in the accessed RU (570), AC_VI also enters MU EDCA mode (backoff value in the thick box; while AC_VO is already in MU EDCA mode), and a new backoff value (white number in the black box, with the value "9") is extracted from the contention window for the transmission traffic queue AC_VI.

[0274] Next, in the fourth phase, the medium is detected as idle, and the backoff counters are decremented taking into account their respective AIFS. Here, even if both AC queues are in MU mode, the backoff counter 531 of AC_VO changes from 14 to 7, while the backoff counter 532 of AC_VI changes from 9 to 2.

[0275] At the same time, the backoff counter of AC_BE expires, resulting in the transmission of data from AC_BE (580). For the expired backoff counter 533, a new backoff value "15" is extracted.

[0276] Next, in the fourth phase, the medium is monitored as idle, and the backoff counters are decremented taking into account their respective AIFS. Here, during the first two slots after the SIFS period, the backoff counter 531 of AC_VO changes from 7 to 5, while the backoff counter 532 of AC_VI expires.

[0277] When the service queue AC_VO is currently in MU mode, without transmitting data from the associated service queue in the communication channel, a new backoff value ("8" in this example) is extracted to reset the expiring queue backoff counter 532. As a result, the decrementing of the backoff counter continues (in fact, the decrementing never stops), especially the backoff counters of the APs expiring in sequence. Therefore, station 502 receives the new TF1300-3 from AP 501 and can execute the AC queue selection algorithm in the station.

[0278] For example, the site determines that the service queue AC_VO has the highest priority due to the lowest queue backoff value (because BC[VI] has also been reset). Therefore, data from AC_VO is transferred via MU UL OFDMA in the accessed RU 590.

[0279] However, in an embodiment, the reset of any AC queue in MU mode can be stored, and this information can be used to select the data to be transmitted. For example, a reset flag (not shown in the figure) can be associated with each service queue, wherein the reset flag is enabled (i.e., set to TRUE) whenever a new backoff value is drawn to reset the associated queue's backoff counter without transmitting data from the service queue (i.e., when the AC queue is in MU mode). This is, for example, the case of service queue AC_VI during phase 5 (which is reset with a new backoff value "8").

[0280] In this case, when the station receives TF 1300-3, it determines that the service queue AC_VI has a reset flag set to true. Therefore, data from AC_VI (such as AC[2] in the example of the figure) undergoes MU UL OFDMA transmission in the accessed RU. This means that data transmitted in the resource unit provided by the access point within the transmission opportunity granted to the access point is retrieved from at least one service queue selected based on the enabled or disabled status of the reset flag associated with the service queue. In particular, data transmitted in the resource unit 590 provided by the access point within the transmission opportunity granted to the access point is retrieved from the service queue with the enabled reset flag.

[0281] On the other hand, the reset flag is disabled (i.e., set to FALSE) whenever data from the service queue is transmitted. In this example, the reset flag of AC_VI is reset after a successful transmission of 590.

[0282] According to the embodiment shown in the figure, a new backoff value (the white number in the black box, which has the value "11") is extracted for the backoff counter 531 associated with the transmission traffic queue AC_VI.

[0283] This exemplary scenario clearly demonstrates the full functional behavior of EDCA backoff, thus restoring QoS, and in particular, restoring the dynamic relative EDCA-based priority between service queues.

[0284] Figure 6A communication device 600 for a wireless network 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:

[0285] • A central processing unit 611, such as a microprocessor, is represented as a CPU.

[0286] • Read-only memory 607, denoted as ROM, is used to store the computer program used to implement the present invention;

[0287] • 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

[0288] At least one communication interface 602 is connected to a communication network 603 through which digital data packets, frames, or control frames are transmitted, such as a wireless communication network according to the 802.11ax protocol. 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.

[0289] Optionally, the communication device 600 may also include the following components:

[0290] • 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;

[0291] • Disk drive 605 used by disk 606, which is configured to read data from disk 606 or write data to said disk;

[0292] • 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.

[0293] 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.

[0294] 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.

[0295] Disk 606 may optionally be replaced by any information medium such as a compact disc (CD-ROM) (rewritable or non-rewritable), a ZIP disc, 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 embodiments of the invention.

[0296] 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.

[0297] 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.

[0298] 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).

[0299] Figure 7 This is a block diagram schematically illustrating the architecture of a communication device or node 600 (particularly one of stations 101-107) configured to at least partially implement the present invention. As shown, station 600 includes a physical (PHY) layer block 703, a MAC layer block 702, and an application layer block 701.

[0300] The PHY layer block 703 (e.g., an 802.11 standardized PHY layer) has the following tasks: formatting, modulating or demodulating on or from any 20MHz channel or composite channel, and thus transmitting or receiving frames via the wireless transmission channel 100 used, such frames being 802.11 frames (e.g., single-user frames) such as: control frames (RTS / CTS / ACK / trigger frames), MAC data and management frames based on a 20MHz width for interaction with a conventional 802.11 station or with 802.11ax in a conventional mode (such as for trigger frames), and OFDMA type MAC data frames with a width preferably smaller than 20MHz (typically 2MHz or 5MHz) relative to the wireless medium.

[0301] 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 embodiments of the present invention. The MAC layer block 702 may optionally be implemented in software, wherein the software is loaded into RAM 612 and executed by CPU 611.

[0302] Preferably, the additional block (referred to as EDCA media access module 705) implements the part of the invention relating to site 600, namely, remembering that once a successful transmission in a resource unit is provided to a given AC, a "MU mode" is established for that AC, thereby continuing the decrementing of each backoff counter of the AC, regardless of the contention mode of the associated traffic queue (in particular, whether or not it is in MU mode), optionally remembering when the backoff counter in MU mode is reset, and also preventing EDCA media access once the backoff of an AC in MU mode drops to zero.

[0303] The MAC 802.11 layer 704 and the EDCA media access module 705 interact with each other to provide management of dual modes (single-user EDCA and multi-user UL OFDMA) as described below.

[0304] 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.

[0305] 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 4 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 site in a self-organizing environment.

[0306] 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.

[0307] 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 stations to access the same medium simultaneously can also be used.

[0308] Figure 8 A typical transport block of a communication station 600 according to an embodiment of the present invention is shown.

[0309] As described above, the site 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:

[0310] Multiple service queues 210 are used to serve data services according to different priorities;

[0311] Multiple queue backoff engines 211, each associated with a specific service queue, are used to calculate the queue backoff value to be used for access to at least one communication channel by competing for an associated backoff counter using a set of EDCA parameters, specifically to transmit the data stored in each service queue. This is the EDCA access scheme.

[0312] The RU access module includes a separate RU backoff engine 800, which is used to calculate the RU backoff value to be used for accessing OFDMA random resource units defined in the received TF (e.g., sent by the AP) using RU contention parameters, specifically RU backoff counters, to transmit 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 reaches zero, the OFDMA multiplexer 801 is responsible for selecting the data to be transmitted from AC queue 210.

[0313] The conventional AC queue backoff register 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).

[0314] When these two competing access schemes coexist, the site implements a media access mechanism with conflict avoidance based on the calculation of backoff values:

[0315] - Queue backoff counter value, which corresponds to the number of time slots (excluding the AIFS period) a station waits before accessing the medium after the communication medium has been detected as idle. This is EDCA regardless of whether the station is in a degraded or non-degraded state;

[0316] - RU backoff counter value, which corresponds to the number of idle random RUs detected by the station before accessing the medium, after the TXOP has been granted to the AP or any other station on the composite channel composed of RUs. This is OFDMA. A variation of using the countdown of the RU backoff counter based on the number of idle random RUs can be based on a time-dependent countdown.

[0317] Figure 9 The flowchart illustrates the main steps performed by the MAC layer 702 of station 600 when new data to be transmitted (an MSDU packet from an upper layer (e.g., application layer 701)) is received. Figure 9 This illustrates a conventional FIFO feed in an 802.11 context.

[0318] Initially, no service queue 210 stores the data to be transmitted. As a result, no queue backoff value is calculated. The corresponding queue backoff engine or the corresponding AC (Access Class) is assumed to be inactive. When data is stored in the service queue, the queue backoff value is calculated immediately (based on the corresponding queue backoff parameters), and the associated queue backoff engine or AC is assumed to be active.

[0319] When a site has data ready to be transmitted over a medium, the data is stored in one of the AC queues 210, and the associated backoff should be updated.

[0320] Details are available now.

[0321] In step 901, new data is received from an application running locally on the device (e.g., from application layer 601), from another network interface, or from any other data source. This new data is ready to be sent by the site.

[0322] In step 902, the station determines which of the AC queues 210 the data should be stored in. This operation is typically performed by (according to...) Figure 2b The matching shown is performed by checking the TID (Business Identifier) ​​value attached to the data.

[0323] 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.

[0324] In step 904, the conventional 802.11 AC backoff calculation is performed using the queue backoff engine associated with the determined AC queue.

[0325] 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.

[0326] Therefore, the site 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 and updated, for example, according to some embodiments of the invention described below in step 1080). It should be reiterated that the queue backoff value is added to AIFS 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 It depends on the access category being considered.

[0327] As a result, AC became active.

[0328] The above parameters CW, CW min CW max AIFSN and backoff values ​​form the EDCA contention parameters and variables associated with each AC. These values ​​are used to set the relative priority of media accessing different categories of data.

[0329] EDCA parameters typically have fixed values ​​(e.g., CW). min CW max And AIFSN), while EDCA variables (CW and backoff value) evolve with time and media availability. As is readily apparent from the above, due to this invention, it is no longer necessary to downgrade the EDCA parameters when applying the penalty MU mode. Of course, these EDCA parameters can still be modified, but this is not necessary.

[0330] Alternatively, a random access procedure for UL RU OFDMA can be supported by the site (as described above); in that case, step 904 may include calculating a RU backoff value if necessary. The RU backoff value needs to be calculated if (for example, because there was no data in the service queue prior to the previous step 903, therefore) the RU backoff engine 800 is inactive and if new data to be addressed to the AP has been received.

[0331] RU backoff values ​​can be used in a similar manner to EDCA backoff values, 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.

[0332] 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.

[0333] In this case, the RU backoff value is calculated only if the newly stored data is marked as compatible with MU UL OFDMA transfer (scheduled or random).

[0334] After step 904, Figure 9 The processing is now complete.

[0335] Once the data is stored in the AC queue, the site can refer to the following: Figure 10 The EDCA access scheme shown below, 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.

[0336] Figure 10 A flowchart illustrates the steps of accessing media based on the conventional EDCA media access scheme, which aims to handle both conventional contention mode and MU contention mode according to an embodiment of the present invention. Specifically, in this example, the reactive countermeasures of the present invention are implemented by the non-AP site 600 in step 999.

[0337] For clarity, it was also drawn Figure 9 The steps are as follows. This is because data storage in the AC[] queue is a prerequisite for any provisional EDCA media access.

[0338] Steps 1000–1020 describe the conventional waiting mechanism introduced in the EDCA mechanism to reduce collisions on the shared radio medium, based on backoff countdown. In step 1000, station 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).

[0339] The medium is in the AIFS[i] time period (at least the DIFS time period, see [link]). Figure 2d If the communication channel becomes idle within a time slot, step 1010 is executed, in which station 600 begins to decrement the backoff counter of all active (non-zero) AC[] queues by 1. In other words, the station decrements the queue backoff value for each basic time unit in which the communication channel is detected as idle.

[0340] Next, in step 1020, station 600 determines whether at least one of the AC backoff counters has reached 0.

[0341] If no AC queue backoff reaches zero, station 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.

[0342] If at least one AC queue backoff reaches 0 (in Figure 5c If the scenario occurs three times, the traditional step 1030 for starting the EDCA transmission phase will not be reached automatically.

[0343] According to the present invention, the site shall determine, based on the current mode of the service queue associated with the expiration queue backoff counter, whether to access the communication channel to transmit data stored in the associated service queue (through the conventional EDCA process starting from step 1030), or to extract a new backoff value to reset the expiration queue backoff counter without transmitting data from the associated service queue in the communication channel (this is an improvement of the present invention, thereby restoring the dynamism of the backoff counter in MU mode).

[0344] In the proposed embodiment, the determination step is implemented by step 1099, which modifies the normal behavior of the EDCA state machine to apply EDCA media access penalties to non-AP sites 600 in MU mode.

[0345] Therefore, the new test 1099 determines whether the service queue associated with the due date queue backoff counter is in penalty MU mode. The service queue may have been marked with a "MU mode" set to 1 (further described below by step 1140), thus making it easy for site 600 to know that the service queue is in penalty mode for EDCA media access.

[0346] A key advantage of this method is that it still allows the reuse of the standard backoff decrement mechanism's hardware / state machine, particularly the fundamental mechanism that ultimately enables the initiation of a media access request when the backoff counter reaches zero. With this invention, the request is simply accustomed to the usage mode (MU mode on or off). The new test 1099 can be easily implemented in hardware.

[0347] In the affirmative judgment of test 1099 (current mode is MU mode), the site will postpone any EDCA media attempts. As a result, without needing to access the transmitted data via EDCA, a new backoff value is extracted by looping back to step 904 to reset the due backoff counter. Therefore, this step reintroduces EDCA backoff management regardless of "MU mode".

[0348] In the event of a reset, a reset flag associated with the relevant business queue can be enabled (as explained above). Figure 5c (As described in the scenario), to remember that the service queue had the highest QoS before the reset. This flag will be used in step 1030 to select the highest priority data for OFDMA transmissions.

[0349] Note that when test 1099 causes the backoff value to be re-extracted without EDCA transmission, it is not necessary to modify the EDCA parameter / variable CW. min CW max And the current CW. This is because, since EDCA transmission is not allowed, there is no knowledge of the EDCA media conditions (basically, these values ​​evolve based on the correct behavior of EDCA transmission). Therefore, any updates to these values ​​are meaningless and useless.

[0350] Optionally, these EDCA parameters / variables can only be updated if the corresponding traffic queues in "MU mode" have spent a significant amount of time (e.g., at least several times the HEMUEDCATimer value of 1425). This is because these previously established frozen values ​​no longer reflect actual network conditions. Therefore, EDCA mode can begin with standardized initial values ​​as if this were the initial (first) transmission utilizing EDCA. In other words, a site can reset the set of contention parameters associated with (preferably, each) traffic queues that remain in MU contention mode for at least the parameter lifetime duration to the default parameter set. For example, the parameter lifetime duration can correspond to at least twice (or more) the predetermined duration used to initialize the MU mode timer (i.e., the value of HEMUEDCATimer).

[0351] On the other hand, in the case of a negative judgment in step 1099 (the current mode is in the traditional EDCA mode), step 1030 is executed, in which station 600 (more precisely, virtual conflict handler 212) selects the active AC queue with a zero queue backoff counter and the highest priority. This is Figure 5c The situation in the first and fourth phases.

[0352] In step 1040, an appropriate amount of data is selected from the chosen AC for transmission.

[0353] Next, in step 1050, if, for example, an RTS / CTS exchange is successfully performed to grant an EDCA TXOP, station 600 initiates an EDCA transmission. Thus, station 600 transmits the selected data on the medium during the granted EDCA TXOP.

[0354] Next, at step 1060, station 600 determines whether the EDCA transmission has ended. If it has ended, step 1070 is executed.

[0355] At step 1070, station 600 updates the EDCA 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, station 600 doubles the value of CW until CW reaches the maximum value CW of the data-dependent AC type. max That's it. 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 .

[0356] Furthermore, it should be reiterated that, due to this invention, CW min and CW max The same applies in both conventional contention mode and MU contention mode, meaning that neither will degrade during step 1170 described below. However, this invention does not prohibit these values ​​from degrading (step 1170) when switching to MU mode, for example, based on the "MU EDCA parameter set" element 1420 received in a management frame (typically a beacon frame) issued by the AP. In this case, if the traffic queue under consideration is in MU mode, the degraded CW is referenced. min and CW max Proceed to step 1070.

[0357] Note that if the transmitted data comes from a service queue where the reset flag is enabled, then disable that flag. In effect, the new backoff value to be extracted will reflect its new relative priority.

[0358] Next, if the selected service queue is not empty after the EDCA data transmission, the process loops back to step 904 and randomly selects a new associated queue backoff counter from [0, CW]. This means that after the data stored in the associated service queue has been transmitted in the accessed communication channel, the station extracts a new backoff value to reset the due queue backoff counter.

[0359] That's how it ended. Figure 10 The processing.

[0360] In a slight variation of the proposed test 1099 described above, the test 1099 used to determine whether to access the communication channel or extract a new backoff value can also be based on the data currently stored in the service queue associated with the due service queue. This is to adjust the penalty scheme for certain types of data, especially to maintain QoS fairness for data unrelated to MU UL transmissions (that have triggered the penalty scheme).

[0361] Focuses on peer-to-peer (P2P or site-to-site) data transmission between non-AP sites.

[0362] The Direct Link Setup (DLS) published in the 802.11e standard allows for direct site-to-site frame transfers within a basic service set.

[0363] Subsequently, the 802.11z standard released Tunnel Direct Link Setup (TDLS), which allows devices to perform more efficient direct site-to-site frame transmission without support from access points. The Wi-Fi Alliance added a certification program for TDLS in 2012, describing the feature as a technology that enables one site to directly link to another when connected to a legacy infrastructure network.

[0364] More generally, transmissions to independent BSS (IBSS) sites (that is, the destination is not registered with any BSS) can be considered P2P communication.

[0365] Both DLS and TLDS require sites to be associated with the same access point. As a result, communication within a P2P group can be considered to occur concurrently with communication on the infrastructure network (including communication at access point 110). In other words, the transmission queue 210 of sites involved in both P2P communication and the BSS network provides data from both service modes.

[0366] As a result, although the penalty scheme envisioned by the 802.11ax standard penalizes uplink traffic to the AP, it also blocks any traditional EDCA access used for P2P communication.

[0367] To address this situation, the above test 1099 can be slightly modified as suggested above.

[0368] Specifically, according to the modified test 1099, if the current mode is the traditional competition mode or if the data included in the associated service queue includes data to be addressed to another site different from the access point (i.e., the data is P2P data), then the process proceeds to step 1030, through which the site accesses the communication channel to transmit the data stored in the associated service queue.

[0369] Conversely, if the current mode is MU contention mode and the data stored in the associated service queue does not include data to be addressed to another site different from the access point (i.e., the data is P2P data), the process loops back to step 904, which means that without transmitting data from the associated service queue in the communication channel, a new backoff value is extracted to reset the expiration queue backoff counter.

[0370] In other words, test 1099 should be modified as follows:

[0371] - If (MU mode is active) and (the AC queue that has expired does not maintain P2P service), then the test result is positive (yes);

[0372] Otherwise, the test result is false and proceed to step 930.

[0373] If the test result of test 1099 is false due to the presence of P2P data while the AC queue is in MU mode, thus allowing access to the communication channel for data transmission, it seems appropriate to prioritize the transmission of this P2P data, contrary to the data intended for the AP that can be sent in the next accessed RU. This means that during step 1040 of data selection, the P2P standard is implemented: in the case of access to the communication channel, only data stored in the associated service queue in MU contention mode and addressed to another site different from the access point is transmitted in the accessed communication channel.

[0374] Various methods for distinguishing between P2P data and UL data intended for use by the AP can be implemented by the site. For example, the distinction between these two types of data can be made using the destination address (receiver address or related information). Figure 2d The "Address 1" field of the MAC data frame is used to: set the destination address to identify UL data to the AP; any other destination address identifies P2P data. Optionally, upcoming MAC frames to be transmitted in the direct path to a (T)DLS peer site or IBSS site are assigned an UPLINK_FLAG parameter set to 0. A UPLINK_FLAG parameter set to 1 indicates data only in the uplink direction to the AP.

[0375] Due to this variation of the invention, P2P services can still be launched by the site.

[0376] Figure 11 A flowchart illustrates the steps involved in accessing a resource unit (random RU or scheduled RU) based on an RU access scheme upon receiving a trigger frame 430 for defining a RU. For example, this shows station 502 at... Figure 5b The behavior in stage 2, 3, or 5.

[0377] In step 1110, the station determines whether it has received a trigger frame 430 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 station analyzes the content of the received trigger frame.

[0378] In step 1120, the station 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, specifically regarding the type of RU.

[0379] By analyzing the content of the received TF, the station determines whether the defined RU is a scheduled resource unit assigned to the station by the access point. This can be done by looking up its own AID in the received TF, which will be associated with the specific scheduled RU to be used for transmission.

[0380] Furthermore, by analyzing the content of the received TF, the site determines whether one or more random RUs are defined in the TF, i.e., RUs that are being accessed through contention using dedicated RU contention parameters (including the aforementioned RU backoff value 800). In this case, the site also determines (especially if the RU backoff value 800 is less than the number of random RUs available in the current TF) whether its current RU backoff value allows the selection of a random RU.

[0381] If a scheduled RU is assigned to the station, or the station is allowed access to a random RU, the station determines the size of the random / scheduled RU to use and performs step 1130. Otherwise, the station decrements the RU backoff value 800 based on the number of random resource units defined in the received trigger frame, and the process ends when the station cannot access any RU (scheduled or random) defined by the received TF.

[0382] In step 1130, the station 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.

[0383] Due to the recovery of the EDCA backoff counter countdown according to the present invention, and thus due to the dynamic nature of each backoff value, the backoff value can be used as a means for application priority selection. For example, this can be done by selecting the service queue 210 (or more queues) with the lowest associated queue backoff value. Thus, the selection of the service queue depends on the EDCA backoff value (this method ensures that the site complies with the EDCA principle, and thus ensures the correct QoS for the data at that site).

[0384] In a variation, the AP can indicate the preferred AC within the trigger frame parameters. Thus, the station can instead select a non-empty traffic queue associated with a data type that 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 13The preferred AC field 1340 is the service queue indicated in the trigger frame.

[0385] In this variation, data transmitted within resource units provided by the access point during the transmission opportunities granted to the access point is retrieved from the preferred traffic queue indicated by the access point. Furthermore, the preferred traffic queue indication is included in a trigger frame received from the access point, which reserves the transmission opportunities granted to the access point on the communication channel and defines resource units (RUs), thereby forming a communication channel including the accessed resource units.

[0386] In another variation of the reset flag based on the above description (in the description) Figure 5c In scenarios where the site is retesting (or looping back to step 904 from test 1099), the site may preferentially select data from the simultaneously reset traffic queue (i.e., in the absence of any traffic from the traffic queue since the last OFDMA transmission). This is to prioritize data that have the highest priority at a given time due to the backoff value before their relative priority is slightly degraded by the backoff counter reset.

[0387] If data is selected from a service queue that is enabled by a reset flag, the same reset flag should be disabled so that the relative priority of that service queue is given only by the associated backoff value.

[0388] Also note that in the case of P2P business, step 1130 may be limited to the selection of UL data (i.e., data intended for use by AP).

[0389] Next, in step 1140, the station can store the fact that the selected service queue is a transmission service queue. For example, the first service queue selected (i.e., selected when step 1130 first occurs) can be remembered as the primary service queue, and the other selected service queues can be remembered as secondary service queues.

[0390] In step 1150, the station determines whether the amount of data stored in the transmission buffer is sufficient to fill the selected resource unit.

[0391] If not, there is still space in the resource unit for additional data to serve another AC queue. The second AC queue (referred to as the secondary AC) can be determined using the same criteria defined above for the remaining service queues. Therefore, the process loops back to step 1130, during which another service queue is selected. In this way, the transmission buffer is progressively filled to reach the selected resource unit size.

[0392] Therefore, it can be noted that multiple transmission service queues at the same site can be involved during MU UL OFDMA transmission, thus causing multiple queues to enter MU EDCA mode.

[0393] 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 selected RU. This is to ensure that the RU has energy detectable by a conventional site throughout its duration.

[0394] According to 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.

[0395] Once the transmission buffer is full for the selected RU, step 1160 initiates a MU UL OFDMA transmission of the data stored in the transmission buffer to the AP. The MU UL OFDMA transmission is based on the OFDMA subchannels and modulation defined in the received trigger frame, and specifically in the RU definition.

[0396] Next, once a transmission has been made, and preferably upon successful transmission (i.e., receiving an acknowledgment from the AP), the transmission queue identified in step 1140 enters MU mode. One or more transmission queues may already be in MU mode.

[0397] The MU mode timer can be initialized using HEMUEDCATimer, which gradually expires over time. Note that if the MU mode timer has expired by the end of a new transmission 1160 (meaning the site is already in MU EDCA mode), the MU mode timer is reinitialized to HEMUEDCATimer to keep the site in MU EDCA mode for the next HEMUEDCATimer time period.

[0398] Therefore, step 1170 can be performed to determine one or more new values ​​of one or more EDCA parameters to be applied to one or more business queues, so that the new values ​​or these new values ​​can be modified into penalty values ​​as appropriate.

[0399] As described above, since the penalty scheme is now fully implemented through the new step 1099 of the EDCA state machine in the embodiment, step 1170 is now optional (compared to prior art documents).

[0400] Not modifying the EDCA parameters means that: MU contention mode uses the same arbitration inter-frame gap duration as traditional contention mode, and in addition, MU contention mode uses the same lower boundary CW as traditional contention mode. min and / or the same upper boundary CW max CW min and CWmax These two factors define the range of choices for selecting the size of the competition window.

[0401] Using the same value advantageously reduces the bandwidth used by the AP to transmit parameters in the beacon frame. In practice, the "MU EDCA parameter set" element 1420 can be significantly reduced to only inform the HEMUEDCATimer value. In other words, fields 1421–1424 can be removed from 1420.

[0402] Additionally, it can be noted that as the EDCA backoff value now evolves again over time, with periodic polling of several business queues, the single MU mode timer used to exit MU mode is sufficient to efficiently drive the site.

[0403] Next, optional step 1180 is implemented, thereby restoring the QoS features supported by the backoff counter, which allows the backoff value to be recalculated more frequently.

[0404] In this optional step, a new EDCA backoff value can be extracted for each transmission service queue, even if its current backoff value has not dropped to zero. This is to maintain the relative priority between service queues (the re-extracted value is likely to become the upper limit of the pending queues on other service queues, so for subsequent transmissions, other queues are given priority).

[0405] For example, a site calculates or extracts a new backoff value for at least one traffic queue being transmitted within an accessed resource unit to reset the associated queue backoff counter. This is in Figure 5c The situation where the retreat counters 531 and 532 are at the end of the second and third phases of the scenario.

[0406] In the first embodiment, the new queue backoff value is calculated only for the transport service queues that transmit data at the beginning of the accessed resource unit. Preferably, only the primary service queues identified in step 1140 involve resetting with the new queue backoff value.

[0407] In the second embodiment, a new queue backoff value is calculated for each transmission service queue identified in step 1140.

[0408] It can be noted that even if some backoff values ​​are re-extracted (and thus the corresponding backoff counters are reset), these values ​​will still decrease again and thus provide a new opportunity to reach zero, in which case Test1099 will be performed again to work according to the current competition mode.

[0409] Although the above embodiments of the invention provide penalty schemes for both scheduled access and random access on a UL MU resource unit, it is conceivable that the penalty scheme be applied only in response to a successful transmission in a scheduled RU. This is motivated in the sense that the penalty MU EDCA parameter (1150) will be applied regarding AP behavior (if the AP actually decides to grant (schedule) UL access for a given site). For a randomly accessed RU, the AP has not specified any particular site (i.e., there is no explicit confirmation that a site is being prioritized, etc.), therefore the penalty is not considered to be applied to the EDCA access mode.

[0410] Figure 12 The flowchart illustrates the site management used in the example above to switch back to traditional EDCA mode. This management is based on the HEMUEDCATimer described above. In practice, the site remains in MUEDCA mode as long as the MU mode timer has not expired.

[0411] Therefore, in step 1210, it is checked whether HEMUEDCATimer has expired / reached its expiration date, i.e., reached a value of 0.

[0412] If the condition is met, in step 1220, the site switches back to EDCA mode, for example, by setting the “MU mode” flag to 0 for all service queues.

[0413] In this embodiment, all degraded service queues share the same predetermined degrade duration HEMUEDCATimer, causing all degraded service queues to exit the degraded MU EDCA mode simultaneously. This exit can mean reverting to traditional EDCA parameters if the MU mode includes degraded EDCA parameters.

[0414] Note that the MU mode timer is reinitialized due to the successful transmission of each new MU UL OFDMA for the site. Therefore, the MU mode timer expires only if no data is transmitted from the site in any RU provided by the AP within the subsequent TXOP granted to the AP during the predetermined degradation duration HEMUEDCATimer.

[0415] The process then ends in step 1230.

[0416] Figure 13 The structure of a trigger frame is shown as defined in the 802.11ax draft standard.

[0417] 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.

[0418] The preferred AC field 1330 is a 2-bit field that indicates the AC queue (value 0 to 3), from which data should be sent by the station on the RU assigned to the station in the trigger frame.

[0419] 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 station should consider Preferred AC field 1340 when selecting data in step 1130. If field 1330 is set to 0, the station is allowed to send data from any AC queue regardless of the value of Preferred AC field 1340.

[0420] Other fields for triggering frames are defined in the 802.11ax standard.

[0421] The AP can also be responsible for broadcasting EDCA parameters for both EDCA mode and MU mode (where the MU mode has degraded parameter values). The AP preferably uses well-known beacon frames specifically designed for configuring all sites in an 802.11 cell for broadcasting. Note that if the AP is unable to broadcast EDCA parameters, the site is configured to fall back to the default values ​​defined in the 802.11ax standard.

[0422] Figure 14a The structure of the standardized information element 1410 used to describe the conventional EDCA parameters in the beacon frame is shown.

[0423] 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.

[0424] All other fields of the information element are fields described in the 802.11 standard.

[0425] This standardized information element 1410 is used by the site to configure itself in the traditional EDCA model.

[0426] Figure 14bAn exemplary structure of a dedicated information element 1420 for transmitting parameter values ​​in MU mode according to the present invention is shown, wherein the dedicated information element 1420 includes possible degraded EDCA parameters (if present) and HEMUEDCATimer values ​​(always present). The dedicated information element 1420 may be included in a beacon frame transmitted by the AP.

[0427] The dedicated information element 1420 specifies the downgraded EDCA parameters (1421, 1422, 1423, 1424) to be used for each AC queue, including sites in MU mode. The dedicated information element 1420 also includes a subfield 1425 that specifies the value of HEMUEDCATimer.

[0428] Each subfield 1421, 1422, 1423, and 1424 includes the downgraded AIFSN value for the corresponding service queue (if present), as well as the downgraded ECWmin and downgraded ECWmax values ​​(which can be the same as the traditional EDCA values). A value of 0 in the AIFSN field indicates that AIFS is equal to the HEMUEDCATimer value set in the MU EDCA timer subfield 1425.

[0429] Of course, if the MU mode uses the traditional EDCA parameters, fields 1421, 1422, 1423, and 1424 can be omitted, thereby reducing bandwidth usage.

[0430] The MU EDCA timer subfield 1425 indicates the HEMUEDCA timer value in units of 8 TU (a time unit equal to a measurement of 1024 μs).

[0431] In this example, within a beacon frame that is periodically transmitted by an access point to broadcast network information related to the communication network to multiple sites, a set of non-degraded and degraded values ​​(if present), as well as the HEMUEDCATimer value, are transmitted. In a variation, these values ​​may be included in a probe response frame or a (re)association response frame.

[0432] 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.

[0433] 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.

[0434] 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 for communicating with a base station constructing a wireless network conforming to the IEEE 802.11 series of standards, the communication device comprising: The first transmission component is used to transmit access category data via a resource unit assigned by the base station for Orthogonal Frequency Division Multiple Access (OFDMA) communication. as well as Control unit, used for control, such that: Once the first transmission component has successfully transmitted the data for the access category, transmission of the data for the access category to be addressed to the base station in the Multi-User Enhanced Distributed Channel Access (MUEDCA) mode is initiated and continues for a predetermined duration. The communication device is capable of transmitting data in the traditional EDCA mode that is to be addressed to other sites different from the base station.

2. The communication device of claim 1, wherein, The transmission of data to be addressed to other sites of a different type than the base station is a peer-to-peer service different from the uplink service to the base station.

3. The communication device of claim 1, wherein, The peer group for transmitting data for access categories to be addressed to other sites different from the base station maintains parallel operation with the wireless network constructed by the base station.

4. The communication device of claim 1, wherein, The transmission of data for the access category is carried out without the support of the base station.

5. The communication device of claim 1, wherein, The communication equipment and the other sites are associated with the same base station.

6. The communication device of claim 1, wherein, The predetermined duration is specified by HEMUEDCATimer.

7. The communication device of claim 1, wherein, Upon receiving confirmation from the base station, the data of the access category is considered to have been successfully transmitted by the first transmission component.

8. The communication device according to claim 1, wherein, The control unit is configured to enable the transmission of data of the access category to be addressed to the base station in the conventional EDCA mode when the predetermined duration expires.

9. The communication device of claim 1, further comprising a second transmission component, the second transmission component being configured to transmit the access category data in the conventional EDCA mode using a contention window defined by a lower boundary value and an upper boundary value.

10. The communication device according to claim 1, wherein, The control unit is configured such that even when the transmission of data of an access category to be addressed to the base station is enabled in the MU EDCA mode, the transmission of data of an access category different from the access category is not controlled to occur in the MU EDCA mode.

11. The communication device according to claim 1, wherein, The access category is either voice (AC_VO), video (AC_VI), best-effort (AC_BE), or background (AC_BG).

12. The communication device according to claim 1, further comprising: A receiving component is configured to receive trigger frames conforming to the IEEE 802.11 series standards, including information about the resource unit. Upon receiving the trigger frame, the first transmission component transmits the access category data.

13. The communication device according to claim 1, wherein, The traditional EDCA mode is the EDCA mode that conforms to the IEEE 802.11 standard prior to IEEE 802.11ax.

14. A communication method, comprising: At the site where communication takes place with base stations that construct wireless networks conforming to the IEEE 802.11 series of standards, Access category data is transmitted via resource units assigned by the base station for Orthogonal Frequency Division Multiple Access (OFDMA) communication; as well as To control so that: Once the data for the access category has been successfully transmitted, transmission of the data for the access category to be addressed to the base station in the Multi-User Enhanced Distributed Channel Access (MU EDCA) mode is enabled and continues for a predetermined duration. The site is able to transmit data in the traditional EDCA mode that is to be addressed to other sites that are different from the base station.

15. The communication method according to claim 14, wherein, The transmission of data to be addressed to other sites of a different type than the base station is a peer-to-peer service different from the uplink service to the base station.

16. The communication method according to claim 14, wherein, The peer group for transmitting data for access categories to be addressed to other sites different from the base station maintains parallel operation with the wireless network constructed by the base station.

17. The communication method according to claim 14, wherein, The transmission of data for the access category is carried out without the support of the base station.

18. The communication method according to claim 14, wherein, The site and the other sites are associated with the same base station.

19. The communication method according to claim 14, wherein, The predetermined duration is specified by HEMUEDCATimer.

20. The communication method according to claim 14, wherein, Upon receiving confirmation from the base station, the data for the access category is considered to have been successfully transmitted.

21. The communication method according to claim 14, wherein, When the predetermined duration expires, the transmission of data of the access category to be addressed to the base station in the conventional EDCA mode is enabled.

22. The communication method according to claim 14, further comprising: A contention window defined by a lower boundary value and an upper boundary value is used to transmit the access category data in the conventional EDCA mode.

23. The communication method according to claim 14, wherein, Even when the transmission of data of the access category to be addressed to the base station is enabled in the MU EDCA mode, the transmission of data of access categories different from the access category is not controlled to be performed in the MU EDCA mode.

24. The communication method according to claim 14, wherein, The access category is either voice (AC_VO), video (AC_VI), best-effort (AC_BE), or background (AC_BG).

25. The communication method according to claim 14, further comprising: Receive a trigger frame conforming to the IEEE 802.11 series standards, including information about the resource unit. Upon receiving the trigger frame, data on the access category is transmitted.

26. The communication method according to claim 14, wherein, The traditional EDCA mode is the EDCA mode that conforms to the IEEE 802.11 standard prior to IEEE 802.11ax.

27. A non-transitory computer-readable medium storing a program that, when executed by a microprocessor or computer system in a device, causes the device to perform the communication method according to claim 14.

28. A base station for constructing a wireless network conforming to the IEEE 802.11 series of standards, the base station comprising: The first receiving unit is used to receive access category data from the first site via a resource unit assigned by the base station for Orthogonal Frequency Division Multiple Access (OFDMA) communication. as well as Control unit, used for control, such that: Once the first station has successfully transmitted the data for the access category, transmission of the data for the access category to be addressed by the first station to the base station in the Multi-User Enhanced Distributed Channel Access (MU EDCA) mode is initiated and continues for a predetermined duration. The first station is able to transmit data in the traditional EDCA mode that is to be addressed to a second station of a different type than the base station.

29. The base station according to claim 28, wherein, The transmission of data to be addressed to a second site of a different type than the base station is a peer-to-peer service different from the uplink service to the base station.

30. The base station according to claim 28, wherein, The peer group for transmitting data for access categories to be addressed to a second site different from the base station maintains parallel operation with the wireless network constructed by the base station.

31. The base station according to claim 28, wherein, The first site and the second site are associated with the same base station.

32. The base station according to claim 28, wherein, The predetermined duration is specified by HEMUEDCATimer.

33. The base station according to claim 28, wherein, The control unit is configured to enable the transmission of data of the access category to be addressed to the base station in the conventional EDCA mode when the predetermined duration expires.

34. The base station according to claim 28, further comprising: The second receiving component is used to receive data of the access category in the conventional EDCA mode using a contention window defined by a lower boundary value and an upper boundary value.

35. The base station according to claim 28, wherein, The control unit is configured such that even when the transmission of data of an access category to be addressed to the base station is enabled in the MU EDCA mode, the transmission of data of an access category different from the access category is not controlled to occur in the MU EDCA mode.

36. The base station according to claim 28, wherein, The access category is either voice (AC_VO), video (AC_VI), best-effort (AC_BE), or background (AC_BG).

37. The base station according to claim 28, further comprising: A transmission component for transmitting trigger frames conforming to the IEEE 802.11 series standards, including information about the resource unit. During the transmission of the trigger frame, the first receiving component receives the access category data.

38. The base station according to claim 28, wherein, The traditional EDCA mode is the EDCA mode that conforms to the IEEE 802.11 standard prior to IEEE 802.11ax.

39. A communication method, comprising: At base stations used to build wireless networks compliant with the IEEE 802.11 series of standards, Access category data is received from the first site via resource units assigned by the base station for Orthogonal Frequency Division Multiple Access (OFDMA) communication; as well as To control so that: Once the first station has successfully received the data for the access category, transmission of the data for the access category to be addressed to the base station in the Multi-User Enhanced Distributed Channel Access (MU EDCA) mode is initiated and continues for a predetermined duration. The first station is able to transmit data in the traditional EDCA mode that is to be addressed to other stations that are different from the base station.

40. The communication method according to claim 39, wherein, The transmission of data to be addressed to other sites of a different type than the base station is a peer-to-peer service different from the uplink service to the base station.

41. The communication method according to claim 39, wherein, The peer group for transmitting data for access categories to be addressed to other sites different from the base station maintains parallel operation with the wireless network constructed by the base station.

42. The communication method according to claim 39, wherein, The first site and the other sites are associated with the same base station.

43. The communication method according to claim 39, wherein, The predetermined duration is specified by HEMUEDCATimer.

44. The communication method according to claim 39, wherein, When the predetermined duration expires, the transmission of data of the access category to be addressed to the base station in the conventional EDCA mode is enabled.

45. The communication method according to claim 39, further comprising: A competition window defined by a lower boundary value and an upper boundary value is used to receive data of the access category in the conventional EDCA mode.

46. ​​The communication method according to claim 39, wherein, Even when the transmission of data of the access category to be addressed to the base station is enabled in the MU EDCA mode, the transmission of data of access categories different from the access category is not controlled to be performed in the MU EDCA mode.

47. The communication method according to claim 39, wherein, The access category is either voice (AC_VO), video (AC_VI), best-effort (AC_BE), or background (AC_BG).

48. The communication method according to claim 39, further comprising: Transmit a trigger frame conforming to the IEEE 802.11 series standards, including information about the resource unit. Specifically, when transmitting the trigger frame, data of the access category is received.

49. The communication method according to claim 39, wherein, The traditional EDCA mode is the EDCA mode that conforms to the IEEE 802.11 standard prior to IEEE 802.11ax.

50. A non-transitory computer-readable medium storing a program that, when executed by a microprocessor or computer system in a device, causes the device to perform the communication method according to claim 39.

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