Communication device, communication method, and computer-readable medium

Abstract

The present invention provides a communication device, a communication method, and a computer-readable medium. In an 802.11ax network with an access point, a trigger frame supplies scheduled resource units and random resource units to a node for uplink data communication to the access point. To more efficiently utilize the network, the access point can design a trigger frame to force the node to send certain classes of data. Resource units can be defined in the trigger frame to be dedicated to small packets or certain access class data. Adjusting the duration of the resource units helps limit the type of data that can be transmitted by these resource units. In addition, when different traffic types coexist, using different bandwidths for resource units in the same trigger frame can help reduce padding in the resource units.

Description

[0001] (This application is a divisional application of application No. 201680040890.6, filed on July 8, 2016, entitled “Trigger Frame for Packet-Based Policy in 802.11 Networks.”) Technical Field

[0002] The present invention relates generally to wireless communication networks and, more particularly, to random allocation of OFDMA subchannels (or resource units) for uplink communications, such as those forming a communication composite channel. One application of the method relates to wireless data communications over a wireless communication network using carrier sense multiple access with collision avoidance (CSMA / CA), where the network is accessible to multiple node devices. Background Art

[0003] The IEEE 802.11 MAC standard defines how wireless local area networks (WLANs) must operate at the physical and medium access control (MAC) layers. Typically, the 802.11 MAC (medium 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 with Collision Avoidance" (CSMA / CA) technique.

[0004] The 802.11 medium access protocol standard or operating mode primarily relates to managing communication nodes that wait for the wireless medium to become idle in order to attempt to access the wireless medium.

[0005] The network operating mode defined by the IEEE 802.11ac standard provides very high throughput (VHT) by moving from the 2.4 GHz band, which is considered to be extremely susceptible to interference, to the 5 GHz band, etc., thereby enabling the use of wider 80 MHz frequency-contiguous channels, where two of these frequency-contiguous channels can be optionally combined to obtain a 160 MHz channel as the operating frequency band of the wireless network.

[0006] The 802.11ac standard also adjusts control frames such as Request-To-Send (RTS) and Clear-To-Send (CTS) frames to allow composite channels with different predefined bandwidths of 20 MHz, 40 MHz, or 80 MHz, where a composite channel is composed of one or more contiguous channels within the operating band. A 160 MHz composite channel can be a combination of two 80 MHz composite channels within the 160 MHz operating band. The control frame specifies the channel width (bandwidth) of the target composite channel.

[0007] Therefore, a composite channel contains a primary channel, on which a given node performs EDCA backoff to access the medium, and at least one secondary channel, for example, of 20 MHz. A communication node uses the primary channel to sense if the channel is idle, and can use the secondary channel to extend the primary channel to form a composite channel.

[0008] Channel clearing is detected using CCA (Clear Channel Assessment), more specifically CCA-ED (CCA-Energy Detect). CCA-ED is the ability of any node to detect non-802.11 energy in the channel and back off from data transmission. The ED threshold against which the energy detected on the channel is compared is defined, for example, as 20 dB above the minimum sensitivity of the node's PHY layer. If the in-band signal energy exceeds this threshold, CCA remains active until the intermediate energy level falls below the threshold again.

[0009] In view of the tree-like decomposition of the operating band into basic 20 MHz channels, some auxiliary channels are named as third-level channels or fourth-level channels.

[0010] In 802.11ac, all composite channels over which transmissions are possible include the primary channel. This is because nodes perform full Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) and Network Allocation Vector (NAV) tracking only on the primary channel. Other channels are designated as secondary channels, where nodes only have CCA (Clear Channel Assessment) capability, i.e., the ability to detect whether the secondary channel is idle or busy.

[0011] A problem with the use of composite channels as defined in 802.11n or 802.11ac (or 802.11ax) is that 802.11n and 802.11ac compatible nodes (i.e., HT nodes (an acronym for High Throughput nodes)) and other legacy nodes (i.e., non-HT nodes that are only compatible with, for example, 802.11a / b / g) must coexist in the same wireless network and therefore must share a 20 MHz channel.

[0012] To address this issue, the 802.11n and 802.11ac standards provide the ability to replicate control frames (e.g., RTS / CTS frames or CTS-to-Self frames or ACK frames used to confirm correct or erroneous reception of transmitted data) in the 802.11a legacy format (referred to as "non-HT"), thereby establishing protection for the requested TXOP across the entire composite channel.

[0013] This prevents any legacy 802.11a node from initiating a new transmission before the end of the current composite channel TXOP granted to the 802.11n / ac node.

[0014] As originally proposed in 802.11n, a duplication of the legacy 802.11a or "non-HT" transmission is provided to enable two identical 20 MHz non-HT control frames to be sent simultaneously on both the primary and secondary channels forming the composite channel used.

[0015] For 802.11ac, this method has been extended to allow replication on channels forming an 80 MHz or 160 MHz composite channel. For the remainder of this document, "replicated non-HT frame" or "replicated non-HT control frame" or "replicated control frame" means a node device replicating the legacy or "non-HT" transmission of a given control frame on a 20 MHz secondary channel of the (40 MHz, 80 MHz, or 160 MHz) operating band.

[0016] In practice, to request a new TXOP on a composite channel (equal to or greater than 40 MHz), an 802.11n / ac node performs an EDCA backoff procedure on the 20 MHz primary channel. In parallel, the 802.11n / ac node performs a channel sensing mechanism, such as Clear Channel Assessment (CCA) signal detection, on the secondary channel to detect a secondary channel that is idle (channel status / condition is "idle") during the PIFS interval before the start of a new TXOP (i.e., before the backoff counter expires).

[0017] Recently, the Institute of Electrical and Electronics Engineers (IEEE) officially approved the 802.11ax task force as the successor to 802.11ac. The main goals of the 802.11ax task force include attempting to increase the data speed of wireless communication devices used in dense deployment scenarios.

[0018] The recent development of the 802.11ax standard aims to optimize the use of composite channels across multiple nodes in wireless networks with access points (APs). In practice, typical content, such as high-definition audiovisual real-time interactive content, has significant data volumes. Furthermore, it is well known that the performance of the CSMA / CA used in the IEEE 802.11 standard degrades rapidly as the number of nodes and traffic volume increases (i.e., in dense WLAN scenarios).

[0019] As network density increases, the number of large collisions and associated retransmissions increases dramatically.

[0020] A problematic situation relates to so-called "small packets," i.e., MAC packets that inherently suffer from a significant overhead (with respect to the amount of payload data) due, for example, to the MAC header, latency for accessing the wireless medium, etc. The greater the number of small packets, the greater the loss of network bandwidth due to the corresponding overhead, and thus the greater the number of collisions and retransmissions associated with small packets.

[0021] Furthermore, the problematic situation becomes increasingly worse because, even if the overhead due to the MAC header is fixed, the latency increases with the number of nodes (the medium for access is shared between a larger number of nodes) and the number of collisions.

[0022] Therefore, established traffic (or scheduled traffic managed by the AP) may be harmed by small packets transmitted over the network.

[0023] However, in a basic service set (BSS) consisting of an AP and its registered nodes, scheduled traffic is not primary traffic.

[0024] To coordinate nodes together, a new Hybrid Coordination Function (HCF) was introduced, which includes two channel access methods: HCF Controlled Channel Access (HCCA) and Enhanced Distributed Channel Access (EDCA). Both EDCA and HCCA define traffic classes (TCs) to adjust QoS (Quality of Service) support by differentiating and negotiating node service parameters. For example, email can be assigned to a low-priority class, while Voice over Wireless LAN (VoWLAN) can be assigned to a high-priority class.

[0025] Four access categories are defined:

[0026] AC_BK is the lowest priority of background data.

[0027] AC_BE is the next priority for best-effort data.

[0028] AC_VI is the priority for video applications, and

[0029] AC_VO is the priority level of the voice application.

[0030] Each access category essentially has two traffic classes as defined in IEEE Standard 802.11. In the following document, traffic class and access category are used interchangeably to designate the same concept.

[0031] These QoS services are inherently unfair, exacerbating collisions and retransmissions in dense environments like those addressed by 802.11ax, leading to inefficiencies in the wireless medium.

[0032] In this context, multi-user transmission has been considered to allow multiple simultaneous transmissions to different users in the downlink and uplink directions. In the uplink, multi-user transmission can be used to reduce the probability of collisions by allowing multiple nodes to transmit simultaneously and to increase network capacity by making the overhead (header, latency, etc.) common to the MAC packets.

[0033] In order to actually carry out such multi-user transmission, it is proposed to divide the authorized 20 MHz channel into subchannels (basic subchannels, also called resource units (RUs)), where multiple users share these subchannels in the frequency domain, for example based on Orthogonal Frequency Division Multiple Access (OFDMA) technology.

[0034] OFDMA is a multi-user variant of OFDM that has emerged as a key new technology to improve the efficiency of wireless networks based on advanced infrastructure. OFDMA combines OFDM at the physical layer with frequency division multiple access (FDMA) at the MAC layer, enabling multiple subcarriers or tones to be assigned to different nodes to improve concurrency. Adjacent subcarriers often experience the same channel conditions and are therefore grouped into subchannels: an OFDMA subchannel, or RU, is therefore a collection of subcarriers or tones.

[0035] As currently envisioned, the granularity of such OFDMA subchannels is finer than the original 20 MHz channel band. Typically, a 2 MHz or 5 MHz subchannel may be considered as the minimum width, so within a single 20 MHz channel, for example, 9 subchannels or resource units are defined.

[0036] To support multi-user uplink (i.e., uplink transmission to an 802.11ax access point (AP) during an authorized TxOP), the 802.11ax AP must provide signaling information for legacy nodes (non-802.11ax nodes) to set their NAVs and for 802.11ax nodes to determine resource unit (RU) allocations and to be used as a reference time for data transmission synchronization.

[0037] It has been proposed that the AP sends a trigger frame (TF) to the 802.11ax node to trigger uplink communication.

[0038] IEEE 802.11-15 / 0365 proposes that an AP send a "trigger" frame (TF) to request the transmission of uplink (UL) multi-user (OFDMA) PPDUs from multiple nodes. In response, the nodes transmit UL MU (OFDMA) PPDUs as an immediate response to the trigger frame. All transmitters can transmit data simultaneously, but using disjoint sets of RUs (i.e., frequencies in OFDMA schemes), resulting in less interference-prone transmissions.

[0039] OFDMA, which is used to provide multi-user transmission in 802.11ax, requires precise inter-user symbol synchronization to maintain orthogonality between different OFDMA subchannels or RUs.

[0040] In addition, each node transmitting a PPDU on an RU must synchronize the end of its PPDU transmission. Otherwise, if a node ends its transmission prematurely, the unused RU can be acquired by an OBSS (Overlapping Base Station Subsystem) node, which can then initiate a new transmission.

[0041] This may cause interference to the following Block Acknowledgements (BAs) sent to the nodes via the AP.

[0042] This may also interfere with the AP when it is receiving other PPDUs in progress.

[0043] In order to synchronize the end of PPDU transmission of each node, the node must send data on its RU until the end of the TXOP duration indicated in the trigger frame. In fact, if the node ends the transmission of payload data before the end of the TXOP, these nodes start sending filler data (as defined in document IEEE802.11-15 / 617).

[0044] The bandwidth or width of the target composite channel is also signaled in the TF frame, meaning a value of 20 MHz, 40 MHz, 80 MHz, or 160 MHz is added. The TF frame is sent on the 20 MHz primary channel and replicated (repeated) on each of the other 20 MHz channels to form the target composite channel. As described above with respect to the replication of control frames, it is expected that each nearby legacy node (non-HT or 802.11ac node) receiving the TF on the primary channel will then set its NAV to the TXOP duration value specified in the TF frame. This prevents these legacy nodes from accessing channels in the target composite channel during the TXOP.

[0045] Resource units (RUs) can be reserved for specific nodes. In this case, the AP indicates the node that has reserved the RU in the TF. This RU is called a scheduled RU. The indicated node does not need to compete when accessing the scheduled RU reserved for that node.

[0046] In order to better improve the efficiency of the system in terms of unmanaged traffic for the AP (e.g., uplink management frames from associated nodes, non-associated nodes intended to reach the AP, or simply unmanaged data traffic), document IEEE802.11-15 / 0604 proposes a new trigger frame (TF-R) on top of the previous UL MU process, thereby enabling random access to OFDMA TXOPs. In other words, a resource unit RU can be randomly accessed by more than one node. Such a RU is called a random RU and is indicated as such in the TF. A random RU can be used as the basis for contention between nodes that intend to access the communication medium to send data.

[0047] The random resource selection process has not yet been defined. All that is known is that the trigger frame may define only scheduled RUs, or only random RUs within the target composite channel.

[0048] Regardless of the random resource selection process used, multi-user transmission based on a triggered frame mechanism should improve network capacity by making the overhead common to all nodes. In fact, the latency overhead is reduced overall.

[0049] However, it is believed that the triggered frame mechanism still has overhead issues (mainly moving from waiting time to filling time).

[0050] Specifically, the triggered frame mechanism provides only a generic RU, in which padding must be applied to ensure reaching the end of the TXOP and avoiding interference with legacy nodes. This padding increases overall overhead costs. This additional overhead cost is exacerbated for so-called small packets, which use a small fraction of the allocated RUs.

[0051] Therefore, especially for small packets, the gain in latency reduction may not be enough to compensate for the loss due to padding. As a result, the total overhead may not be reduced, contrary to the intended goal when the triggered frame mechanism was introduced.

[0052] In addition to the case of small packets, different types of data traffic typically coexist in different RUs, where these RUs have different requirements in terms of the amount of data to be transmitted, latency, TxOP duration, etc. This heterogeneity of the different PPDUs transmitted by a node may result in a large amount of padding data in some RUs, thereby significantly reducing the efficiency of channel usage.

[0053] It may be noted that the use of different modulations (modulation and coding schemes) to handle the distance (node to AP) and signal-to-noise ratio variations (changing channel conditions) through different paths (i.e., through different RUs involving different nodes) may also exacerbate the filling problem.

[0054] Therefore, there is a need to improve this situation and reduce the impact of padding on network usage efficiency.

[0055] In addition, the use of the network can be improved by taking advantage of different types of data services that exist in various RUs at the same time. Summary of the Invention

[0056] A broad object of the present invention is to provide a method and apparatus for wireless communication in a wireless network comprising an access point and a plurality of nodes that share a physical medium of the wireless network.

[0057] The present invention has been designed to overcome one or more of the above-mentioned limitations.

[0058] In this context, the present invention seeks to provide a wireless communication method that improves the use of the network and, in turn, improves the mechanisms against collisions in the communication channel.

[0059] The present invention is applicable to any wireless network in which an access point provides a registered node with a plurality of sub-channels (or resource units) forming a communication channel. The communication channel is a basic channel on which a node listens to determine whether the basic channel is idle or busy.

[0060] The present invention is particularly suitable for data transmission to an AP of an IEEE 802.11ax network (and future versions).

[0061] The first main embodiment of the present invention provides a wireless communication method in a wireless network from the perspective of an access point, wherein the wireless network includes an access point and multiple nodes, and the wireless communication method includes a step of sending a trigger frame to the node at the access point, wherein the trigger frame reserves at least one communication channel of the wireless network for a transmission opportunity and defines multiple resource units, i.e., multiple RUs, for forming the communication channel.

[0062] The trigger frame includes an indicator for limiting data to be sent on at least one resource unit among the plurality of resource units to data having a restricted data type.

[0063] The same first main embodiment of the present invention provides a wireless communication method in a wireless network from the perspective of a node, the wireless network comprising an access point and a plurality of nodes, the wireless communication method comprising the following steps at one of the plurality of nodes:

[0064] receiving a trigger frame from the access point, wherein the trigger frame reserves at least one communication channel of the wireless network for a transmission opportunity and defines a plurality of resource units (RUs) for forming the communication channel;

[0065] determining, from the trigger frame, an indicator defining a restricted data type permitted for at least one resource unit of the plurality of resource units;

[0066] determining, from the local transmission memory, data having a type corresponding to the determined restricted data type; and

[0067] The determined data is transmitted to the access point over the resource unit.

[0068] Because the indicator specifies the restricted data type, the access point can drive or control the node in its process of selecting data to transmit on the RU. As a result, the AP can efficiently adjust the RU to suit the data type, thereby optimizing the use of the RU.

[0069] Relatedly, the present invention provides a communication device for use as an access point in a wireless network, the wireless network also comprising a plurality of nodes, the communication device for use as an access point comprising at least one microprocessor configured to perform steps for sending a trigger frame to the nodes, the trigger frame reserving at least one communication channel of the wireless network for a transmission opportunity and defining a plurality of resource units for forming the communication channel.

[0070] The trigger frame includes an indicator for limiting data to be sent on at least one resource unit among the plurality of resource units to data having a restricted data type.

[0071] From the perspective of a node, the present invention further provides a communication device in a wireless network, the wireless network comprising an access point and a plurality of nodes, the communication device being one of the plurality of nodes and comprising at least one microprocessor configured to perform the following steps:

[0072] receiving a trigger frame from the access point, wherein the trigger frame reserves at least one communication channel of the wireless network for a transmission opportunity and defines a plurality of resource units for forming the communication channel;

[0073] determining, from the trigger frame, an indicator defining a restricted data type permitted for at least one resource unit of the plurality of resource units;

[0074] determining, from the local transmission memory, data having a type corresponding to the determined restricted data type; and

[0075] The determined data is transmitted to the access point over the resource unit.

[0076] Optional features of the embodiments of the present invention are defined in the appended claims. Some of these features are described below with reference to methods, and these features can be converted into system features specific to any node device according to embodiments of the present invention.

[0077] In an embodiment, the restricted data type defines small MAC packets relative to the MAC packets transmitted via the wireless network. Consequently, the AP can force nodes to send so-called small packets. Consequently, nodes will less often spend time acquiring a TXOP for sending small packets. This significantly helps reduce the overall overhead costs incurred by small packets. Consequently, network utilization is improved.

[0078] In a specific embodiment, the small MAC packet is a MAC packet having a packet size smaller than a predetermined maximum packet size (i.e., a threshold). For example, the predefined maximum packet size is equal to a so-called RTS threshold parameter set for the wireless network according to the 802.11 standard. The RTS threshold parameter is a manageable parameter of the 802.11 network that is used to determine when (i.e., starting from which size of MAC packet) the RTS / CTS handshake should precede a data packet.

[0079] As a result, small packets that would normally be processed without RTS / CTS handshaking (ie, small packets that should avoid the overhead due to RTS / CTS) are processed in bursts using TF.

[0080] In a variant example, the small MAC packet is a MAC packet having an overhead due to the MAC header in the packet that is greater than a predetermined maximum overhead (i.e., a threshold), such as 20% or 30%. In practice, these packets, which already have large internal overhead, should preferably be processed together in a burst to avoid having too much additional overhead for each packet.

[0081] There are some types of packets that essentially have one or the other of the above definitions. For example, a control packet is essentially a small packet.

[0082] In a specific embodiment, the predetermined maximum packet size or the predetermined maximum overhead is specified in the trigger frame.

[0083] In an embodiment from the perspective of an access point, the wireless communication method may further include adjusting the predetermined maximum packet size or the predetermined maximum overhead from one trigger frame to another based on network statistics related to one or more previous transmission opportunities.

[0084] These two provisions enable the AP to efficiently drive the management of small packets as network conditions evolve.

[0085] In an embodiment from the perspective of a node, the local transmit memory of the node includes a plurality of ordered transmit queues, each ordered transmit queue being associated with a dynamic priority value (i.e., the priority value evolves over time. In the 802.11 scheme, the priority value corresponds to the value of a contention backoff counter associated with each transmit queue); and

[0086] Determining data having a type corresponding to the determined restricted data type includes selecting at least one packet from a set of one or more packets, the set comprising one of:

[0087] The first packet from the transmit queue with the highest priority value,

[0088] The first small packet from each transmission queue,

[0089] All packets from all transmit queues,

[0090] All packets in the transmit queue are stored only for small packets.

[0091] Therefore, node-related policies can be adapted.

[0092] In an embodiment, the at least one resource unit has a minimum bandwidth permitted by the 802.11 standard. Currently, a 20 MHz channel can be divided into a maximum of nine identical resource units, i.e., the minimum bandwidth is 2.03 MHz. This provision optimizes the use of RUs for small packets. Consequently, this provision also increases the number of nodes that can send small packets on the RUs of the authorized composite channel.

[0093] In an embodiment, the restricted data types define data traffic types. As a result, the AP can force nodes to send certain types of data in response to specific TFs. When this happens as described below, the AP will then adapt the RUs based on the allowed traffic types to optimize the use of network bandwidth.

[0094] In a specific embodiment, the restricted data service type is one of four access categories defined in the 802.11 standard, namely AC_BK for background data, AC_BE for best effort data, AC_VI for video applications, and AC_VO for voice applications.

[0095] In a specific embodiment from the perspective of the AP, the wireless communication method further includes: determining the restricted data service type from a plurality of predefined service types (such as the above four access categories) based on the following:

[0096] network statistics relating to an amount of data received in one or more previous transmission opportunities for each of the plurality of predefined traffic types, or

[0097] A total queue size for each of the plurality of predefined traffic types, wherein the total queue size for a predefined traffic type is the sum of the sizes of the transmit queues associated with the predefined traffic type in the node. The AP can obtain such information from each node because the 802.11 standard MAC header of the PPDU transmitted by the node includes a "Queue Size" field, which the node uses to indicate the amount of buffered traffic for a given traffic type. Therefore, the AP can calculate global statistics related to the total queue size for each traffic type and construct an associated trigger frame with a dedicated RU traffic type.

[0098] In a specific embodiment from the perspective of the node, determining from the local transmit memory that data of a type corresponding to the determined restricted data type includes selecting, from the transmit queue storing the data, only data of the determined restricted data type. This is particularly applicable when the restricted data type is one of the four access categories defined above. In this case, processing at the node is very simple because the processing only requires accessing a single transmit queue based on the restricted data type associated with the RU being used.

[0099] In a specific embodiment from the perspective of a node, the local transmission memory of the node includes a plurality of transmission queues, each transmission queue is associated with a dynamic priority value and a traffic type, and the wireless communication method further includes the following steps:

[0100] The transmit queues are considered sequentially in order of highest to lowest priority value until data is sent on a resource unit, and

[0101] For each transmission queue considered in turn, it is determined whether a resource unit in the communication channel has a restricted traffic type, and in the event of an affirmative determination, data from the transmission queue currently considered is transmitted on the determined resource unit.

[0102] This configuration maintains the priority order as defined in the 802.11 standard, thereby preserving fairness among nodes.

[0103] In an embodiment, the wireless communication method further comprises: determining a frequency of transmitting a trigger frame with a restricted type indicator based on network statistics related to one or more previous transmission opportunities. This helps improve network usage because the AP dynamically adjusts the number of opportunities for a node to transmit specific data (small packets or with a traffic type) to suit network conditions.

[0104] In other embodiments, the wireless communication method further comprises determining the number of resource units forming the communication channel based on network statistics related to one or more previous transmission opportunities. This helps improve network utilization because the number of nodes that can transmit data during the next TXOP is dynamically adjusted to suit network conditions.

[0105] In a specific embodiment, the network statistics include one or more of the following:

[0106] the number of nodes registered with the access point in the wireless network,

[0107] the number of collisions or collision rate (the number of collided RUs in the plurality of RUs) that occurred during the one or more previous transmission opportunities,

[0108] the distribution of packet sizes received by the access point, in particular the distribution of packet sizes relative to the maximum packet size (i.e., defining small packets),

[0109] The amount of data transmitted by the node,

[0110] an amount of data transmitted by the node for each traffic type from a plurality of predefined traffic types, and

[0111] The ratio of medium busyness, for example, the ratio of medium busy time in a given period (e.g., one second).

[0112] In some embodiments, the trigger frame includes a single indicator defining the same restricted data type for all resource units of the at least one communication channel (ie, for the entire composite channel), thereby minimizing the overhead caused by the indicator.

[0113] In a variant, the trigger frame includes an indicator for each resource unit, thereby defining a different restricted data type for each resource unit. This allows more nodes to transmit data during the current TXOP because nodes with different types of data can now transmit via each RU within the same communication channel.

[0114] The second main embodiment of the present invention provides a wireless communication method in a wireless network from the perspective of an access point, wherein the wireless network includes an access point and multiple nodes, and the wireless communication method includes a step for sending a trigger frame to the node at the access point, wherein the trigger frame reserves at least one communication channel of the wireless network for a transmission opportunity and defines multiple resource units, i.e., multiple RUs, for forming the communication channel, wherein at least one resource unit has a predefined resource unit bandwidth.

[0115] The wireless communication method further includes the following step at the access point, which is used to determine the duration of the transmission opportunity based on the predefined resource unit bandwidth and the predetermined maximum packet size, so that the at least one resource unit can only include MAC packets with a packet size smaller than the predetermined maximum packet size.

[0116] This configuration enables the access point to force the nodes to transmit their so-called small packets (ie packets with a packet size smaller than a predetermined maximum packet size). This is achieved by adjusting the size of the TXOP in an appropriate manner given the predefined width of the resource units.

[0117] One advantage of using this method to force the transmission of small packets is that it is fully compliant with the 802.11ax standard. In fact, no additional information is provided, and the node still performs the same process to select data that matches the RU offering.

[0118] Relatedly, the present invention provides a communication device used as an access point in a wireless network, the wireless network also including multiple nodes, the communication device used as an access point including at least one microprocessor configured to perform steps for sending a trigger frame to the nodes, the trigger frame reserving at least one communication channel of the wireless network for a transmission opportunity and defining multiple resource units for forming the communication channel, wherein at least one resource unit has a predefined resource unit bandwidth.

[0119] In which, the microprocessor is also configured to perform the following steps, which are used to determine the duration of the transmission opportunity based on the predefined resource unit bandwidth and the predetermined maximum packet size, so that the at least one resource unit can only include MAC packets with a packet size smaller than the predetermined maximum packet size.

[0120] Optional features of the embodiments of the present invention are defined in the appended claims. Some of these features are described below with reference to methods, and these features can be converted into system features specific to any node device according to embodiments of the present invention.

[0121] In an embodiment, the predefined maximum packet size is equal to a so-called RTS threshold parameter set according to the 802.11 standard for the wireless network.

[0122] In an embodiment, the predefined resource unit width is the minimum bandwidth permitted by the 802.11 standard.

[0123] As described above with reference to the first main embodiment, the frequency for sending such trigger frames or the number of resource units in the communication channel may also be determined dynamically.

[0124] A third main embodiment of the present invention provides a wireless communication method in a wireless network from the perspective of a node, wherein the wireless network includes an access point and multiple nodes. The wireless communication method includes the following steps at the access point:

[0125] sending a trigger frame to the node, the trigger frame reserving at least one communication channel of the wireless network for a transmission opportunity and defining a plurality of resource units (RUs) for forming the communication channel, the plurality of resource units having the same time length,

[0126] The resource units in the communication channel have different bandwidths.

[0127] The same third main embodiment of the present invention provides a wireless communication method in a wireless network from the perspective of a node, the wireless network comprising an access point and a plurality of nodes, the wireless communication method comprising the following steps at one of the plurality of nodes:

[0128] receiving a trigger frame from the access point, the trigger frame reserving at least one communication channel of the wireless network for a transmission opportunity and defining a plurality of resource units (RUs) for forming the communication channel, wherein the plurality of resource units have the same time length; and

[0129] transmitting data to the access point on one of the plurality of resource units,

[0130] The resource units in the communication channel have different bandwidths.

[0131] The use of network bandwidth is optimized by enabling resource units to have different bandwidths (i.e., different transmission capacities).

[0132] As a result, nodes can efficiently select resource units that match their needs, minimizing fill-up.

[0133] Relatedly, the present invention provides a communication device used as an access point in a wireless network, the wireless network also including multiple nodes, the communication device used as an access point including at least one microprocessor configured to perform steps for sending a trigger frame to the nodes, the trigger frame reserving at least one communication channel of the wireless network for a transmission opportunity and defining multiple resource units for forming the communication channel, the multiple resource units having the same time length.

[0134] The resource units in the communication channel have different bandwidths.

[0135] From the perspective of a node, the present invention further provides a communication device in a wireless network, the wireless network comprising an access point and a plurality of nodes, the communication device being one of the plurality of nodes and comprising at least one microprocessor configured to perform the following steps:

[0136] receiving a trigger frame from the access point, the trigger frame reserving at least one communication channel of the wireless network for a transmission opportunity and defining a plurality of resource units used to form the communication channel, wherein the plurality of resource units have the same time length; and

[0137] transmitting data to the access point on one of the plurality of resource units,

[0138] The resource units in the communication channel have different bandwidths.

[0139] Optional features of the embodiments of the present invention are defined in the appended claims. Some of these features are described below with reference to methods, and these features can be converted into system features specific to any node device according to embodiments of the present invention.

[0140] In an embodiment, each of the resource units is associated with a data traffic type selected from four access categories defined by the 802.11 standard, namely AC_BK for background data, AC_BE for best effort data, AC_VI for video applications, and AC_VO for voice applications.

[0141] In a specific embodiment, resource units associated with the AC_BK and AC_BE traffic types have a first bandwidth, resource units associated with AC_VO have a bandwidth equal to twice the first bandwidth, and resource units associated with AC_VI have a bandwidth equal to four times the first bandwidth. This provision optimizes bandwidth usage because the RU size is adjusted to suit the size of the content carried by these RUs. As a result, the size of the resource units dedicated to small content is adjusted accordingly, avoiding overfilling.

[0142] In a more specific embodiment, the first bandwidth is equal to the minimum bandwidth permitted by the 802.11 standard. Currently, a 20 MHz channel is divided into a maximum of 9 identical resource units, i.e., the minimum bandwidth is 2.03 MHz. This is to provide access points with optimal granularity when designing resource units.

[0143] In a specific embodiment, the same duration of the resource units is less than or equal to one-quarter of the TXOP limit parameter set for the wireless network according to the 802.11 standard. This provision is advantageously combined with the aforementioned adjustment of the relative size (width) of the resource units based on their associated AC_BK, AC_BE, AC_VI, or AC_VO traffic types. In practice, utilizing RU width can significantly reduce the duration of the TXOP and, therefore, reduce the need to fill underutilized RUs.

[0144] In an embodiment related to a node, each resource unit is associated with a data service type, and the wireless communication method further comprises performing the following steps at the node:

[0145] Data having the same traffic type as the traffic type associated with a resource unit is transmitted on the resource unit.

[0146] This helps the access point drive how the nodes use the resource units. The access point can define the traffic type of each resource unit in the trigger frame.

[0147] In an embodiment, the node includes a plurality of transmission queues storing data to be transmitted, each transmission queue being associated with a dynamic priority value; and the wireless communication method further includes the following steps:

[0148] determining whether one of the plurality of resource units matches the amount of data to be sent in the transmission queue having the highest priority value, and

[0149] In case of a positive determination, the data of the transmission queue having the highest priority value is transmitted on the matching resource unit.

[0150] Of course, other transmit queues may be considered in turn in order of priority to transmit their contents in appropriate (ie, appropriately sized) RUs.

[0151] In an embodiment, the wireless communication method further comprises: adapting a modulation scheme used to modulate data on the resource unit, wherein the adaptation maximizes the duration of transmitting data within the transmission opportunity. This also helps to reduce padding in the RU while strengthening the data to avoid errors on the communication channel.

[0152] In an embodiment related to an access point, each resource unit is associated with a data service type, and the wireless communication method further comprises the following steps:

[0153] The bandwidth of the resource unit is determined based on statistical data related to data associated with each traffic type received in one or more previous transmission opportunities.

[0154] This is to enable the access point to dynamically adjust the RU design to suit the node requirements, that is, to make dynamic adjustments as network conditions evolve.

[0155] In a specific embodiment, the bandwidth of the resource unit is further adjusted based on the number of nodes registered with the access point. This provision also helps to adjust the number of RUs based on the number of nodes, because the bandwidth of the RU can be adjusted so that one or more RUs can be added or removed from the communication channel.

[0156] In a specific embodiment, the bandwidth of the resource unit associated with the traffic type is further adjusted based on the modulation scheme used by the node to send data with the associated traffic type in one or more previous transmission opportunities. This regulation helps to reduce padding in the RU at the end of the transmission of useful data and enhances the robustness of the transmitted data to avoid transmission errors.

[0157] In an embodiment, the wireless communication method further comprises: determining the number of resource units forming the communication channel based on network statistics related to one or more previous transmission opportunities.

[0158] The same statistics as defined above can be used. In particular, the type of data traffic (video, audio, background, best effort), the number of each data traffic type, the number of nodes, the modulation scheme (MCS) used by each node, the modulation scheme (MCS) used on each RU, the identification of stable traffic (video streaming, VoIP, ...) or random traffic (web browsing, control frames, ...) can be used.

[0159] Another aspect of the invention relates to a non-transitory computer-readable medium storing a program that, when executed by a microprocessor or a computer system in a device of a wireless network, causes the device to perform any of the methods defined above.

[0160] The non-transitory computer-readable medium may have similar features and advantages as those set forth above and below in connection with the method and the node apparatus.

[0161] Another aspect of the present invention relates to a method of wireless communication in a wireless network comprising substantially as herein described with reference to the accompanying drawings Figure 8 、 9 , 10a, 10b, 11, 12 and 13 and as shown in any of the access points and multiple nodes.

[0162] At least a portion of the method according to the present invention can be implemented by a computer. Thus, the present invention can take the form of an all-hardware embodiment, an all-software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects that may generally be referred to herein as a "circuit," "module," or "system." Furthermore, the present invention can take the form of a computer program product embodied in any tangible medium of expression having computer-usable program code embodied therein.

[0163] Since the present invention can be implemented in software, the present invention 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 electric signals, electronic signals, optical signals, acoustic signals, magnetic signals, or electromagnetic signals (e.g., microwave or RF signals). BRIEF DESCRIPTION OF THE DRAWINGS

[0164] Further advantages of the present invention will become apparent to those skilled in the art upon examination of the drawings and detailed description.Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings.

[0165] Figure 1 shows a typical wireless communication system in which embodiments of the present invention may be implemented;

[0166] Figure 2 is a timeline schematically illustrating a conventional communication mechanism according to the IEEE 802.11 standard;

[0167] Figure 3 802.11ac channel allocations supporting channel bandwidths of 20 MHz, 40 MHz, 80 MHz, or 160 MHz as known in the prior art are shown;

[0168] Figure 4 An example of an 802.11ax uplink OFDMA transmission mechanism is shown, where the AP sends a trigger frame on an 80 MHz channel known in the prior art to reserve a transmission opportunity for an OFDMA subchannel (resource unit);

[0169] Figure 5 shows a typical communication line according to a typical random assignment;

[0170] Figure 5a An example showing the use of 8 RUs forming a composite channel;

[0171] Figure 6 shows a schematic representation of a communication device or station according to an embodiment of the present invention;

[0172] Figure 7 shows a schematic representation of a wireless communication device according to an embodiment of the present invention;

[0173] Figure 8 A flowchart is used to illustrate the general steps of the first embodiment of the present invention from the perspective of an access point;

[0174] Figure 9 A flowchart is used to illustrate the general steps of the first embodiment of the present invention from the perspective of nodes;

[0175] Figure 10a and 10b A flowchart is used to illustrate the general steps of the second embodiment of the present invention from the perspective of an access point;

[0176] Figure 11 A flowchart is used to illustrate the general steps of the second embodiment of the present invention from the perspective of nodes;

[0177] Figure 12 A flowchart is used to illustrate the general steps of the third embodiment of the present invention from the perspective of an access point;

[0178] Figure 13 A flowchart is used to illustrate the general steps of the third embodiment of the present invention from the perspective of nodes;

[0179] Figure 14 An example of designing an RU of a composite channel according to the third embodiment is shown; and

[0180] Figure 15 Typical formats for signaling RU attributes according to the first, second and third embodiments of the present invention are presented. DETAILED DESCRIPTION

[0181] The invention will now be described using specific non-limiting exemplary embodiments and with reference to the accompanying drawings.

[0182] Figure 1 A communication system is shown in which a plurality of communication nodes (or stations) 101-107 exchange data frames via a wireless transmission channel 100 of a wireless local area network (WLAN) under the management of a central station or access point (AP) 110. The wireless transmission channel 100 is defined by an operating frequency band, wherein the operating frequency band is composed of a single channel or a plurality of channels forming a composite channel.

[0183] Accessing the shared wireless medium to send data frames is based on CSMA / CA technology to sense the carrier and avoid collisions by separating concurrent transmissions in space and time.

[0184] Carrier sensing in CSMA / CA is performed by both physical and virtual mechanisms. Virtual carrier sensing is achieved by transmitting a control frame before transmitting a data frame to reserve the medium.

[0185] Next, before transmitting a data frame, the source node first attempts to sense a medium that has been idle for at least a DIFS (DCF InterFrame Spacing) period through a physical mechanism.

[0186] However, if the shared wireless medium is detected to be busy during the DIFS period, the source node continues to wait until the wireless medium becomes idle. To do this, the source node starts a countdown backoff counter that is designed to expire after a number of time slots randomly selected between [0, CW], where CW (an integer) is called the Contention Window. This backoff mechanism or process is the basis of a collision avoidance mechanism that postpones transmissions by random intervals, thereby reducing the probability of collisions on the shared channel. After the backoff period, if the medium is idle, the source node can send data or control frames.

[0187] One problem with wireless data communications is that the source node cannot listen while transmitting, thereby preventing the source node from detecting data corruption caused by channel fading or interference or collision phenomena. The source node remains unaware of the corruption of the transmitted data frame and continues to transmit frames unnecessarily, thereby wasting access time.

[0188] Thus, the collision avoidance mechanism of CSMA / CA provides a positive acknowledgement (ACK) of a data frame sent by a receiving node if a frame is successfully received, to inform the source node that the sent data frame is not damaged.

[0189] The ACK is transmitted at the end of reception of a data frame, immediately after a period of time known as the Short Interframe Space (SIFS).

[0190] If the source node does not receive an ACK within the specified ACK timeout, or detects that a different frame was transmitted on the channel, the source node can infer that the data frame was lost. In this case, the source node typically reschedules the frame transmission according to the backoff process described above. However, if only the ACK is corrupted and the data frame is received correctly by the receiving node, this can be considered a waste of bandwidth.

[0191] To improve the collision avoidance efficiency of CSMA / CA, a four-way handshake mechanism may optionally be implemented. One implementation is known as the RTS / CTS exchange defined in the 802.11 standard.

[0192] The RTS / CTS exchange consists in exchanging control frames before transmitting data frames to reserve the wireless medium, thereby protecting the data transmission from any further collisions, during a transmission opportunity called TXOP in the 802.11 standard as described below.

[0193] Figure 2 The behavior of three groups of nodes during conventional communication on a 20 MHz channel via an 802.11 medium is shown: a sending or source node 20, a receiving or addressed or destination node 21, and other nodes 22 not involved in the current communication.

[0194] When the backoff process 270 is started before sending data, as described above, the station (e.g., source node 20) initializes its backoff time counter to a random value. As long as the wireless medium is sensed as idle, the backoff time counter is decremented by 1 for each time slot interval 260 (as shown in the figure, the countdown starts at T0,23).

[0195] Channel sensing is performed, for example, using clear channel assessment (CCA) signal detection.

[0196] CCA is a WLAN carrier sensing mechanism defined in the IEEE 802.11-2007 standard as part of the Physical Medium Dependence (PMD) and Physical Layer Convergence Protocol (PLCP) layers. CCA includes two functions:

[0197] Carrier Sense (CCA-CS) is the ability of a receiving node to detect and decode an 802.11 frame preamble. Based on the PLCP header field, the duration for which the medium will be occupied can be inferred. If such an 802.11 frame preamble is detected, the CCA flag remains busy until the data transmission is completed.

[0198] Energy Detection (CCA-ED) is the ability of a receiving node to detect non-802.11 energy in a specific 20MHz channel and back off data transmission. In practice, the energy level on the 20MHz channel is sensed and compared to an ED threshold used to distinguish between channel states with and without 802.11 energy channels. The ED threshold is defined, for example, as 20dB higher than the minimum sensitivity of the node's PHY layer. If the in-band channel energy exceeds this threshold, CCA remains active until the medium energy falls below the threshold again.

[0199] The time unit in the 802.11 standard is a slot interval called the "aSlotTime" parameter. This parameter is specified by the PHY (physical) layer (for example, in the case of the 802.11n standard, aSlotTime is equal to 9 μs). All dedicated space durations (for example, backoff) add multiples of this time unit to the SIFS value.

[0200] In the event that a transmission is detected on the wireless medium channel, the backoff time counter is "frozen" or paused (for other nodes 22 whose backoff time counters are decremented, the countdown stops at T1, 24).

[0201] The backoff timer countdown resumes or restarts after the DIFS period when the wireless medium is sensed to be idle again. Once the transmission opportunity TXOP granted to source node 20 ends and the DIFS period 28 has elapsed, the same is true for other nodes at T2, 25. Therefore, the DIFS 28 (DCF Interframe Space) defines the minimum time a source node must wait before attempting to transmit data. In practice, DIFS = SIFS + 2*aSlotTime.

[0202] When the backoff time counter reaches zero (26) at T1, the timer expires, the corresponding node 20 requests access to the medium to be granted a TXOP, and the backoff time counter is reinitialized 29 with a new random backoff value.

[0203] In the example of the figure implementing the RTS / CTS scheme, at T1, the source node 20 that wants to transmit the data frame 230 sends a special short frame or message serving as a medium access request instead of the data frame itself to reserve the wireless medium immediately after the channel is sensed to be idle for DIFS or immediately after the backoff period as described above.

[0204] The medium access request is known as a Request to Send (RTS) message or frame. The RTS frame generally includes the addresses of the source and receiving nodes ("destination 21") and the duration for which the wireless medium is to be reserved for transmission of control frames (RTS / CTS) and data frames 230.

[0205] When an RTS frame is received and the wireless medium is sensed as idle, the receiving node 21 responds with a medium access response known as a Clear to Send (CTS) frame after a SIFS period 27 (e.g., in the case of the 802.11n standard, SIFS is equal to 16 μs). The CTS frame also includes the addresses of the source and receiving nodes and indicates the remaining time required to transmit the data frame, calculated from the time the CTS frame was sent.

[0206] The CTS frame is considered by the source node 20 as an acknowledgement of the source node's request to reserve the shared wireless medium for a given duration.

[0207] Therefore, the source node 20 expects to receive a CTS frame 220 from the receiving node 21 before sending data 230 using a frame that is unique and unicast (one source address and one visited or destination address).

[0208] Therefore, the source node 20 can send the data frame 230 after the new SIFS period 27 if the CTS frame 220 is correctly received.

[0209] To provide QoS support, 802.11 defines various priority levels for data that a source node 20 wants to transmit. These levels are primarily defined based on the nature of the data.

[0210] In 802.11e, four access categories (ACs) are defined:

[0211] AC_BK has the lowest priority for background data.

[0212] AC_BE has the next priority for best-effort data,

[0213] AC_VI has a higher priority than video applications, and

[0214] AC_VO has the highest priority for voice applications.

[0215] Each access category has one or more traffic classes as defined in IEEE Standard 802.11e-2005.

[0216] In practice, the source node 20 has a transmission buffer queue for each access category and therefore implements a backoff counter for each access category. The backoff counter with the lowest value from the four AC backoff counters is considered the backoff counter for the node because it is the first backoff counter to reach zero.

[0217] The receiving node 21 sends an ACK frame 240 after a new SIFS period 27 after having correctly received the transmitted data frame.

[0218] If the source node 20 does not receive the ACK 240 within a specified ACK timeout (typically within a TXOP), or if the source node 20 detects that a different frame was transmitted on the wireless medium, the source node again uses the backoff procedure to reschedule the frame transmission.

[0219] Since the RTS / CTS four-way handshake mechanism 210 / 220 is optional in the 802.11 standard, the source node 20 may immediately send the data frame 230 when its backoff time counter reaches zero (ie, at T1).

[0220] The requested duration of the transmission defined in the RTS and CTS frames defines the length of the authorized transmission opportunity TXOP and can be used by any listening node in the wireless network ( Figure 2 "Other nodes 22" in the read).

[0221] To do this, each node maintains in memory a data structure known as a network allocation vector or NAV that stores the duration for which the medium is known to remain busy. Upon listening to a control frame (RTS 210 or CTS 220) not addressed to itself, the listening node 22 updates its NAV (NAV 255 associated with an RTS and NAV 250 associated with a CTS) with the requested transmission duration specified in the control frame. The listening node 22 thus maintains in memory the duration for which the wireless medium is known to remain busy.

[0222] By pausing 31 the association timer of the other node 22 and then resuming 32 the timer upon expiry of the NAV, access to the wireless medium by the other node 22 is thereby deferred.

[0223] This prevents the listening node 22 from transmitting any data or control frames during this period.

[0224] The receiving node 21 may not correctly receive the RTS frame 210 due to message / frame collision or fading. Even if the receiving node 21 receives the RTS frame 210, the receiving node 21 cannot always respond with the CTS 220 because, for example, the NAV of the receiving node 21 is set (i.e., another node has already reserved the medium). In any case, the source node 20 enters a new backoff process.

[0225] The RTS / CTS four-way handshake mechanism is very efficient in terms of system performance, especially for large frames, because the RTS / CTS four-way handshake mechanism reduces the length of messages involved in contention processing.

[0226] Specifically, assuming perfect channel sensing by each communication node, a collision can only occur if two (or more) frames are transmitted in the same time slot after 28 DIFS (DCF Interframe Space), or if the communication node's own backoff counter reaches zero at approximately the same time, T1. If two source nodes use the RTS / CTS mechanism, such a collision can only occur with RTS frames. Fortunately, since it can be quickly determined that a CTS response has not been received, such a collision can be detected in advance.

[0227] As described above, the original IEEE 802.11 MAC always sends an acknowledgement (ACK) frame 240 after each data frame 230 is received.

[0228] However, such collisions limit the optimal functionality of wireless networks. As mentioned above, simultaneous transmission attempts from multiple wireless nodes can lead to collisions. The 802.11 backoff procedure was first introduced for DCF mode as a fundamental solution for collision avoidance. In the emerging IEEE 802.11n / ac / ax standards, the backoff procedure is still used as a fundamental method for supporting distributed access between mobile stations or nodes.

[0229] To meet the growing demand for faster wireless networks to support bandwidth-intensive applications, 802.11ac targets greater bandwidth transmission via multi-channel operation. Figure 3 802.11ac channel allocations are shown supporting composite channel bandwidths of 20 MHz, 40 MHz, 80 MHz, or 160 MHz.

[0230] IEEE 802.11ac introduces a restricted number of predefined subsets of 20 MHz channels to form a unique predefined composite channel configuration that can be reserved by any 802.11ac node on the wireless network for transmitting data.

[0231] The predefined subsets are shown in the figure and correspond to 20 MHz, 40 MHz, 80 MHz and 160 MHz channel bandwidths, compared to only 20 MHz and 40 MHz supported by 802.11n. In practice, the 20 MHz composite channels 300-1 to 300-8 are concatenated to form a wider communication composite channel.

[0232] In the 802.11ac standard, channels in each predefined 40 MHz, 80 MHz, or 160 MHz subset are continuous within the operating band, ie, holes (missing channels) are not allowed in the composite channels ordered in the operating band.

[0233] A 160 MHz channel bandwidth is composed of two 80 MHz channels, which may or may not be frequency-contiguous. An 80 MHz channel and a 40 MHz channel are composed of two frequency-adjacent or contiguous 40 MHz channels and 20 MHz channels, respectively.

[0234] Nodes are granted TxOPs on the "primary channel" (300-3) via the Enhanced Distributed Channel Access (EDCA) mechanism. 802.11ac designates one channel as "primary" for each composite channel with bandwidth, meaning it is used to compete for access to the composite channel. The 20 MHz primary channel is shared by all nodes (STAs) belonging to the same basic set, meaning they are managed by or registered with the same local access point (AP).

[0235] However, in order to ensure that other legacy nodes (ie legacy nodes not belonging to the same set) do not use the secondary channel, it is proposed to replicate the control frames (eg RTS frames / CTS frames) used to reserve such a composite channel on each 20 MHz channel in the composite channel.

[0236] As previously discussed, the IEEE 802.11ac standard enables the bonding of up to four or even eight 20 MHz channels. Due to the limited number of channels (19 in the 5 GHz band in Europe), channel saturation becomes a problem. In fact, in densely populated areas, even with 20 MHz or 40 MHz of bandwidth available for each wireless LAN cell, the 5 GHz band will certainly become saturated.

[0237] The development of the 802.11ax standard seeks to enhance the efficiency and use of wireless channels in dense environments.

[0238] From this perspective, the multi-user transmission feature can be considered, allowing multiple simultaneous transmissions to multiple users in both the downlink and uplink directions. In the uplink, multi-user transmission can be used to reduce the probability of collisions by allowing multiple nodes to transmit simultaneously.

[0239] To implement such multi-user transmission, it has been proposed to divide the licensed 20 MHz channels (300-1 to 300-4) into subchannels 410 (basic subchannels, also known as subcarriers or resource units (RUs)), where multiple users share these subchannels 410 in the frequency domain, for example, based on orthogonal frequency division multiple access (OFDMA) technology. Each RU can be defined by multiple tones, and a 20 MHz channel contains a plurality of 242 available tones.

[0240] refer to Figure 4 Such a multi-user transmission is shown.

[0241] The multi-user feature of OFDMA enables the AP to assign different RUs to different nodes to reduce contention. This can help reduce contention and collisions within the 802.11 network.

[0242] In contrast to downlink OFDMA, where the AP can directly send multiple data to multiple stations (supported by specific indications within the PLCP header), a triggering mechanism has been adopted for the AP to trigger uplink communications from various nodes.

[0243] To support uplink multi-user transmission (during preemptive TxOP), the 802.11ax AP must provide signaling information to both legacy stations (non-802.11ax nodes) to set their NAVs and to the 802.11ax nodes to determine resource unit allocations.

[0244] In the following description, the term “legacy” refers to non-802.11ax nodes, which means prior art 802.11 nodes that do not support OFDMA communications.

[0245] like Figure 4 As shown in the example of FIG4 , the AP sends a trigger frame (TF) 430 to the target 802.11ax node. The bandwidth or width of the target composite channel is signaled in the TF frame, which means that a value of 20 MHz, 40 MHz, 80 MHz, or 160 MHz is added. The TF frame is sent on the 20 MHz primary channel and replicated (repeated) on each of the other 20 MHz channels to form the target composite channel. As described above with respect to the replication of control frames, it is expected that each nearby legacy node (non-HT or 802.11ac node) that receives the TF on the primary channel will then sequentially set its NAV to the value specified in the TF frame. This prevents these legacy nodes from accessing channels in the target composite channel during the TXOP.

[0246] The trigger frame TF may specify at least one resource unit (RU) 410 or a "random RU" that may be randomly accessed by more than one node. In other words, the random RU in the TF, designated or allocated by the AP, may serve as a basis for contention between nodes interested in accessing the communication medium to transmit data. Figure 5 A typical example of such random allocation is shown.

[0247] In addition to or instead of random RUs, the trigger frame TF may also specify scheduled resource units. Scheduled RUs may be reserved for certain nodes, in which case no contention is required for access to such RUs.

[0248] In this context, the TF includes information specifying the type of RU (scheduled or random). For example, a label can be used to indicate whether all RUs defined in the TF are scheduled (label = 1) or random (label = 0). In this case, random RUs and scheduled RUs are mixed within the TF, and a bitmap (or any other equivalent information) can be used to define the type of each RU (the bitmap can follow the known order of RUs in the entire communication channel).

[0249] The multi-user feature of OFDMA enables the AP to assign different RUs to different nodes to reduce contention. This can help reduce contention and collisions within the 802.11 network.

[0250] exist Figure 4 In the example of FIG, each 20 MHz channel is subdivided in the frequency domain into four subchannels or RUs 410 of typically 5 MHz in size. These subchannels (or resource units) are also called "subcarriers" or "traffic channels."

[0251] Of course, the number of RUs that divide 20 MHz may be different from 4. For example, 2 to 9 RUs may be provided (so that each RU has a size of 10 MHz to approximately 2.2 MHz).

[0252] As shown, all RUs 410 have the same time length 230 (corresponding to the length of the TXOP).

[0253] Figure 5 A typical communication line is shown according to a typical random allocation process 500 that can be used by a node to access a random RU indicated in a TF. The random allocation process is based on the reuse of a node's backoff counter value to assign an RU to a node of the network to send data.

[0254] The AP sends a trigger frame (TF) that defines a RU as having random access. In the example shown in the figure, eight RUs with the same bandwidth are defined for a 40 MHz composite channel, and TF 430 is replicated across two 20 MHz channels to form the composite channel. In other words, the network is configured to process four OFDMA resource units for each 20 MHz channel.

[0255] Each node STA1 ˜STAn is a transmission node to the receiving AP, and as a result, each node has at least one active backoff value (corresponding to the AC backoff counter with the lowest value).

[0256] The random allocation process for a node among a plurality of nodes with active backoff 510 includes the following steps: a first step for determining the subchannels or RUs of the communication medium available for contention from a trigger frame; a second step for verifying whether the value of the local active backoff of the node under consideration is not greater than the number of RUs detected as available; and then, a step for sending data on a number of RUs equal to the backoff value.

[0257] In other words, random RUs may be indexed in TF, and each node uses the RU with an index equal to the node's backoff value.

[0258] As shown, some resource units may not be used, for example, RUs with indices 2 (410-2), 5, 7, and 8. This is due to randomization, and in this example due to the fact that no node has a backoff value equal to 2, 5, 7, or 8 when sending TF.

[0259] Figure 5a An example of the use of 8 RUs forming a composite channel is shown (of course, the number of OFDMA RUs may vary). These 8 RUs have the same design, ie, the same time length (corresponding to the TXOP duration) and the same frequency bandwidth.

[0260] The AP sends a TF having a duration 550 of, for example, 3 ms and a number of random RUs and / or scheduled RUs.

[0261] Upon receiving a TF, the node accesses the scheduled RU, or competes for access to a random RU (e.g., as referenced Figure 5 As described), the data of the node is then transmitted in the visited RU during a time corresponding to the TXOP duration 900.

[0262] In this example, the data traffic sent by the nodes is heterogeneous, ie, video, voice, web applications, control frames, etc. are mixed in the same uplink (UL) multi-user (MU) OFDMA transmission.

[0263] As shown in the figure, the resulting PPDU is a PPDU that is very different from other PPDUs in terms of duration.

[0264] This is because the amount of data to be transferred varies greatly from one data type to another.

[0265] This is also because, even for the same type of data traffic or the same amount of data to be transmitted, the modulation used by the node (which is linked to the distance between the transmitting node and the access point) significantly modifies the transmission duration. Depending on the modulation used (MCS0-9 in IEEE 802.11ac), the number of bits carried by each OFDM symbol changes, and for a given amount of data, the transmission duration also changes, knowing that the symbol duration is fixed.

[0266] For example, node STA1 may transmit web browsing traffic (AC_BE: access category best effort), node STA2 may transmit control frames, and node STA4 may transmit a large aggregation of video data frames (AC_VI: access category video).

[0267] As shown in the figure, the PPDU sent by STA4 (553) uses the entire TXOP duration of the UL MU OFDMA, while the PPDU sent by STA1 (551) requires padding (552) to maintain the signal on RU#1 for the entire TXOP duration. In fact, if the data transmission lasts less than the TXOP duration 550, the node must pad (send padding data) until the UL MU transmission ends.

[0268] Figure 5a This example illustrates the disadvantages of UL MU transmission in some scenarios.

[0269] So called "small packets" like those sent by STA7 have a lot of overhead due to the large amount of padding required to have a signal until the end of TXOP 230. There is a need to alleviate this situation and improve the efficiency of the triggered frame mechanism when transmitting small packets.

[0270] In addition, due to the heterogeneity of different PPDUs transmitted by nodes, a large amount of padding data is sent on the RU. The trigger frame mechanism needs to be adjusted to adapt to the heterogeneity of data between RUs.

[0271] All of these requirements attempt to improve network usage by reducing padding in particular.

[0272] Embodiments of the present invention find particular application in enhancements to the 802.11ac standard, and more specifically in the context of 802.11ax, where dense wireless environments are more certain to exist beyond previous limitations.

[0273] Embodiments of the present invention provide improved wireless communications with more efficient bandwidth usage while limiting the risk of collisions. In particular, an attempt is made to reduce the amount of filler data.

[0274] Typical wireless networks are IEEE 802.11ac networks (and later versions). However, the present invention is applicable to any wireless network comprising an access point AP 110 and a plurality of nodes 101-107 transmitting data to the AP via multi-user transmission. The present invention is particularly suitable for data transmission in IEEE 802.11ax networks (and future versions) that require better bandwidth utilization.

[0275] The above reference Figures 1 to 5 To illustrate the typical management of multi-user transmission in such a network.

[0276] A first main embodiment of the invention provides that, in addition to reserving at least one communication channel of the wireless network for a transmission opportunity and defining a plurality of resource units forming the communication channel, the trigger frame further comprises an indicator for limiting the data to be sent on the at least one resource unit to data having a restricted data type.

[0277] As a result, the node can determine from the trigger frame an indicator defining a restricted data type permitted for at least one resource unit; determine from the local transmission memory data having a type corresponding to the determined restricted data type; and transmit the determined data to the access point on the resource unit.

[0278] By using such an indicator, the AP can force the node to send specific data that is particularly suitable for the designed RU.

[0279] Two main approaches are proposed for the first embodiment.

[0280] In one aspect, the restricted data type defines a small MAC packet relative to the MAC packet transmitted via the wireless network. Figure 8 and 9 The method described in more detail is to enable the AP to control the transmission of so-called small packets by sending appropriate trigger frames. Thus, depending on the amount of small packets in the ongoing communication (the AP is able to classify the data transmitted via the ongoing communication), the AP can decide to clear the node's transmission buffer with small packets, thereby reducing the node's overall contention time and the overall overhead caused by the small packets.

[0281] On the other hand, the restricted data type defines the data service type. For the restricted data service type, the main embodiment refers to one of the four access categories defined in the 802.11 standard (i.e., AC_BK for background data, AC_BE for best effort data, AC_VI for video applications, and AC_VO for voice applications). Figure 10a 、 10b11 describe this method in more detail. As a result, the AP can force nodes to use RUs for specific traffic data, as the AP may assume that the RUs forming the composite channel are specifically designed for this type of data. Furthermore, efficient use of RUs results in less padding being sent, improving network bandwidth utilization.

[0282] Other main embodiments of the present invention provide that, in a trigger frame that reserves at least one communication channel of a wireless network for a transmission opportunity and defines a plurality of resource units forming the communication channel (these plurality of resource units have the same time length), the resource units within the communication channel are defined to have different bandwidths.

[0283] The RUs provided in the composite channel are therefore more suitable for heterogeneous data services. By selecting the RUs to use in an appropriate manner (an example of the selection process is described below), the node generally reduces the amount of padding sent. This improves the use of network bandwidth.

[0284] For example, the node may determine whether one of the resource units matches the amount of data to be sent in the node's priority AC transmission queue, and in the event of a positive determination, transmit the data in the priority AC transmission queue on the matching resource unit.

[0285] The following references Figures 12-14 To illustrate the methods of these other main embodiments.

[0286] The main method of the first main embodiment and the methods of the other main embodiments may be combined partially or completely to increase the benefits in reducing the overall fill.

[0287] Figure 6 The communication device 600 of the wireless network 100 is schematically shown, 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, a workstation, or a lightweight portable device. The communication device 600 includes a communication bus 613 to which the following items are preferably connected:

[0288] A central processing unit 611 , such as a microprocessor, denoted as a CPU;

[0289] A read-only memory 607, denoted as ROM, for storing computer programs used to implement the present invention;

[0290] A random access memory 612 represented as a RAM for storing executable code of the method according to an embodiment of the present invention, and registers suitable for recording variables and parameters required to implement the method according to an embodiment of the present invention; and

[0291] At least one communication interface 602 connected to a wireless communication network 100, for example, an 802.11ac wireless communication network, through which digital data packets or digital data frames or control frames are transmitted. Under the control of a software application running in the CPU 611, frames are written from a transmit FIFO in the RAM 612 to the transmitting network interface, or frames are read from a receiving network interface and written to a receive FIFO in the RAM 612.

[0292] Optionally, the communication device 600 may further include the following components:

[0293] A data storage component 604, such as a hard disk, for storing a computer program for implementing the method according to one or more embodiments of the present invention;

[0294] a disk drive 605 for a disk 606, which is suitable for reading data from the disk 606 or writing data to the disk;

[0295] • Screen 609 for displaying decoded data and / or serving as a graphical interface for the user via a keyboard 610 or any other indication means.

[0296] The communication apparatus 600 may optionally be 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 apparatus 600 .

[0297] Preferably, a communication bus provides communication and interoperability between the various components included in or connected to the communication device 600. The representation of a bus is not limiting, and in particular, the central processing unit is operable to communicate instructions to any other component of the communication device 600, either directly or through a component of the communication device 600.

[0298] The disk 606 can optionally be replaced by any information medium such as a compact disk (CD-ROM) (rewritable or not), a ZIP disk, a USB key or a memory card, and is generally replaced by an information storage component, which can be read by a microcomputer or a microprocessor, is integrated or not integrated into the device, is possibly removable and is suitable for storing one or more programs, the execution of which implements the method according to the invention to be implemented.

[0299] The executable code may optionally be stored in a read-only memory 607, on a hard disk 604 or on a removable digital medium such as a disk 606 as previously described. According to an optional variant, the executable code of the program may be received via the interface 602 over the communication network 603 to be stored in one of the storage means of the communication device 600, such as the hard disk 604, before being executed.

[0300] The central processing unit 611 is optionally adapted to control and direct the execution of instructions or portions of the software code of the program according to the present invention, wherein these instructions are stored in one of the above-mentioned storage components. Upon power-on, the program stored in the non-volatile memory (e.g., stored on the hard disk 604 or stored in the read-only memory 607) is transferred to the random access memory 612, which contains the executable code of the program, and registers for storing variables and parameters required to implement the present invention.

[0301] In a preferred embodiment, the device is a programmable device that implements the invention using software. Alternatively, however, the invention may be implemented in hardware (for example in the form of an application specific integrated circuit or ASIC).

[0302] Figure 7 1 is a block diagram schematically illustrating the basic structure of a communication device or node 600 (AP 110 or one of nodes 101-107 suitable for at least partially implementing the present invention). As shown in the figure, node 600 includes a physical (PHY) layer block 703, a MAC layer block 702, and an application layer block 701.

[0303] The PHY layer block 703 (here the 802.11 standardized PHY layer) has the following tasks: formatting, modulating or demodulating any 20 MHz channel or composite channel, and thus sending or receiving frames such as 802.11 frames via the wireless medium used, for example, the medium access trigger frame TF 430 used to reserve a transmission time slot, MAC data and management frames based on a 20 MHz width for interaction with traditional 802.11 stations, and OFDMA type MAC data frames with a width smaller than the traditional 20 MHz (typically 2 MHz or 5 MHz) to / from the wireless medium.

[0304] The PHY layer block 703 includes a CCA capability that listens to the idle or busy status of the 20 MHz channel and reports the results according to the 802.11 standard to the MAC 702. When a signal with significant received signal strength is detected, an indication of channel usage is generated.

[0305] The MAC layer block or controller 702 preferably includes a MAC 802.11 layer 704 that implements legacy 802.11ax MAC operations, as well as additional blocks for at least partially implementing the present invention. The MAC layer block 702 can optionally be implemented in software, where the software is loaded into the RAM 612 and executed by the CPU 611.

[0306] Preferably, an additional block called MU management module implements a portion dedicated to implementing all or part of the embodiments of the present invention in relation to the node 600 .

[0307] For example, in implementing the first method of the first main embodiment of the present invention (hereinafter referred to as Figure 8 and 9 To describe the example), the MU management module 705 includes a small packet (SP) management module 7050, wherein the small packet (SP) management module 7050 includes an AP implementation Figure 8 The "TF processor" sub-block 7051 used in the algorithm, and / or each node implements Figure 9 The "RU Selector" sub-block 7052 used by the algorithm.

[0308] In implementing the second method of the first main embodiment of the present invention (hereinafter referred to as Figure 10a 、 10b 11 to describe its illustrative example), the MU management module 705 includes an access category (AC- or service type) management module 7053, wherein the access category management module 7053 also includes an AP implementation Figure 10a and 10b The "TF Processor" sub-block used in one of the algorithms, and / or each node implementation Figure 11 The "RU Selector" sub-block used by the algorithm.

[0309] In implementing other main embodiments of the present invention (refer to Figures 12-14 To describe the example), the MU management module 705 includes a bandwidth management module 7054, wherein the bandwidth management module 7054 also includes an AP implementation Figure 12 The "TF Processor" sub-block used by the algorithm, and / or each node implementation Figure 14 The "RU Selector" sub-block used by the algorithm.

[0310] Figure 7 Typical nodes in include the following reference Figures 8 to 15 Features of all embodiments of the invention described.

[0311] At the top of the figure, an application layer block 701 runs an application, wherein the application generates and receives data packets, for example, data packets of a video stream. The application layer block 701 represents all stack layers above the MAC layer according to ISO standardization.

[0312] Figure 8 and 9 Two flow charts are used to illustrate the general steps of an embodiment of the present invention for limiting data to be sent on at least one resource unit to data of restricted data type, particularly small MAC packets relative to MAC packets transmitted via a wireless network. Figure 8 is a flowchart from the perspective of the access point, and Figure 9 The following flowcharts are from the node's perspective. They all apply to multi-user OFDMA uplink in 802.11ax wireless medium.

[0313] Packets can be defined in various ways.

[0314] First, a small MAC packet may be a MAC packet having a packet size smaller than a predetermined maximum small packet size (i.e., a threshold value). For example, the predefined maximum packet size is equal to the so-called RTS threshold parameter set for wireless networks according to the 802.11 standard. Typically, a value equal to 256 bits may be selected. The threshold size may be pre-set in the AP by an administrator or through factory default settings.

[0315] In a variant, these small packets can be defined with respect to their overhead cost. For example, a small MAC packet can be a MAC packet with an overhead due to the MAC header in the packet that is greater than a predetermined maximum overhead (i.e., a threshold). Typical ratio values are 20% or 30%.

[0316] In a third embodiment, the threshold (predetermined maximum packet size or predetermined maximum overhead) may be dynamically determined using a learning mechanism as described below with reference to step 804 .

[0317] Figure 8 A typical process of an AP generating a trigger frame dedicated to a set of small packets (SPs) (hereinafter also referred to as an SP trigger frame or SPTF) is shown.

[0318] This SP trigger frame is constructed to force the node to send packets only in specific RUs (preferably, all RUs defined by the SP TF or all random RUs). To achieve this purpose, the SP TF includes an indicator that specifies this restriction on packets.

[0319] Various implementations are conceivable.

[0320] For example, the limit indicator specified in the SP TF may be a predetermined maximum packet size or maximum overhead that provides an upper limit when evaluating whether a packet is a small packet. Figure 15 This is provided by a dedicated field 1522 in the signaling shown.

[0321] In a variant, such an upper limit may be predefined and known to all APs and nodes in the network. In this case, it is only necessary to indicate that for all RUs or for some RUs, the TF is an SP TF.

[0322] In an embodiment, the restriction indicator defines a trigger frame type, i.e., an SP TF. The restriction indicator indicates that all RUs defined by the SP TF are limited to small packets. In other words, the trigger frame includes a single indicator for defining the same restricted data type for all resource units of at least one communication channel.

[0323] In other embodiments, the restrictions can be defined at the RU level. This means that the indicator defines the RU service type: restricted to small packets, or not restricted. This means that the trigger frame includes an indicator for each resource unit, thereby defining various restricted data types for each resource unit. For example, as shown in the following reference Figure 15 As described above, a dedicated RU SP or service type field may be used in the RU description to restrict the use of a specific RU in the transmission of a packet.

[0324] In a variation of the use of a specific restriction indicator in the SP TF, an embodiment may provide for automatically making the duration of the TXOP very short to implicitly allow only small packets to be transmitted. To implement this structure, the AP will determine the duration of the transmission opportunity based on a predefined resource unit bandwidth and a predetermined maximum packet size, so that at least one resource unit can only include MAC packets with a packet size smaller than the predetermined maximum packet size. Preferably, the predefined maximum packet size is equal to the so-called RTS threshold parameter set for wireless networks according to the 802.11 standard, and the predefined resource unit width is the minimum bandwidth permitted by the 802.11 standard (2.2 MHz in the case of a 20 MHz channel divided into 9 RUs).

[0325] As described below, a schedule for SP TF transmissions is determined to optimize the reduction of packet overhead. This includes determining the frequency of transmission of trigger frames with a restricted type indicator based on network statistics related to one or more previous transmission opportunities. This corresponds to the first steps 800-803 of the process now described.

[0326] Processing begins at step 799, where the AP determines whether a new event has occurred. If a new event has occurred, step 799 determines whether the new event corresponds to the receipt of a packet at the MAC layer, the expiration of an SP TF timer as described below, or any other event.

[0327] In case of receiving a packet at the MAC level, the next step 800 is executed, during which the AP (in a more general way, any node in the network can initiate a TXOP by sending a TF, in this case Figure 8 The collection of some statistics related to the wireless network during one or more previous TXOPs may be accomplished via such a node.

[0328] Typical statistics include the number of nodes in the network, the number or ratio of collisions (colliding RUs), the number or ratio of used RUs, the number or ratio of unused RUs, the distribution of packet sizes received by the AP, etc.

[0329] The statistics may be updated each time the AP receives and decodes a new MAC packet.

[0330] Next, at step 801, the AP determines the maximum waiting time between two consecutive SP trigger frame transmissions.

[0331] This determination is based on updated statistics and can be made using a pre-calculated abacus of the optimal waiting time between two consecutive SP TFs. More precisely, the abacus can plot the optimal waiting time based on the number of nodes in the network and / or based on the collision rate (the number of colliding RUs out of the total number of RUs during the last N TXOPs).

[0332] Note that different Abacus can be used for different AP configurations: for example, one Abacus for APs used as hotspots, one Abacus for APs used as home set-top boxes, one Abacus for APs used as enterprise APs, etc. This is to better match network conditions.

[0333] In a variant, the time interval between two consecutive SP TFs may be determined using a learning mechanism. For example, the AP has received packets from some nodes during previous TXOPs.

[0334] The scheduling interval may be changed using the ratio of used RUs and the number of received packets determined during step 800. For example, if a given threshold of RUs is used (typically 80%), the AP may decrease the interval between two SP TFs by dividing the current interval by the ratio (typically 2). Conversely, a low RU usage (less than 50%) may drive an increase in the interval between two SP TFs by multiplying the current interval by the ratio (typically 2).

[0335] Although two mechanisms (the use of an abacus and a learning mechanism) are suggested above, any other mechanism may be used to adapt the scheduling of SP TF transmissions.

[0336] After step 801 of determining the maximum wait time, step 802 involves having the AP schedule the next time the next SPTF should be transmitted. Thus, the AP adapts the delay until the next SPTF must be transmitted based on the previous SPTF transmission time and the maximum wait time determined at step 801.

[0337] Therefore, steps 801 and 802 define the SP TF timer before sending a new SP TF.

[0338] Once the next transmission time is known, step 803 involves having the AP determine when the delay / timer has expired. If the delay has just expired, the SP TF must be transmitted and step 804 is executed. Otherwise, the SP TF timer value is modified or adjusted according to the delay determined at step 802 (if no timer is running, for example, during the startup phase, a new timer is started with the waiting value), and the system returns to the waiting step 799 to wait for a new packet to be received.

[0339] In case the SP TF timer has expired as detected via test 803 or test 799, step 804 is executed.

[0340] At step 804, the AP determines the characteristics of the SP TF: for example, the number of RUs, and which of these RUs are scheduled RUs and which RUs are random RUs; the number of RUs allocated to the packet, and which of these RUs are from all RUs; the TXOP duration; and the maximum size or maximum overhead of the packet defined for the current SP TF.

[0341] For example, the AP may adjust the predetermined maximum packet size or the predetermined maximum overhead from one trigger frame to another based on network statistics related to one or more previous transmission opportunities. This information (maximum size or maximum overhead) may be specified within the AP so that nodes know the upper limit of the packet.

[0342] Additionally, the AP may determine the number of resource units forming the communication channel based on network statistics related to one or more previous transmission opportunities. Again, this is to optimize the use of network bandwidth taking into account the needs of the nodes.

[0343] In a first embodiment, the number of resource units, the predetermined maximum packet size or maximum overhead, and the TXOP duration are fixed and known to all nodes. Step 804 simply retrieves these values. For example, the maximum packet size is typically set to 256 bytes; the number of RUs dedicated to packets is equal to the total number of possible RUs in the composite channel (typically, 9 RUs for each 20 MHz channel); and given the number of RUs, the TXOP duration is set to fit the predefined maximum packet size.

[0344] In a more complex second embodiment, step 804 uses a predefined abacus to obtain the values of these TF features.

[0345] For example, the number of RUs dedicated to small packets can be set according to a predefined algorithm (usually associating the number of SP RUs with the number of nodes in the cell according to the AP type (hotspot, home, enterprise, etc.)).

[0346] The same mechanism can be used to determine the maximum packet size.

[0347] Again, given the number of abacus-based RUs, the TXOP duration can be set to fit the abacus-based maximum packet size.

[0348] During evaluation testing of access points embodying the present invention, the abacus can be determined using simulation models or actual measurements.

[0349] In a third embodiment, a learning mechanism is used during step 804 to determine the TF features.

[0350] For example, the number of RUs dedicated to small packets can be determined based on the ratio of used RUs dedicated to small packets during the last TXOP. The ratios of used RUs, conflicted RUs, and / or unused RUs are collected at step 800. Based on these ratios, a typical algorithm can be performed at step 804 to determine the number of small packet RUs: if the ratio of used RUs is greater than 80%, the maximum number of SP RUs is doubled; if the ratio is less than 50%, the maximum number of SP RUs is divided by 2; otherwise, the number of SP RUs remains unchanged.

[0351] Note that the number of RUs per 20 MHz channel should not exceed the maximum number of RUs (usually 9 RUs per 20 MHz channel). When starting a wireless network cell, such a value (9 RUs per channel) can be used by the AP as a default value.

[0352] Of course, combinations of these embodiments are conceivable within the scope of this first embodiment: for example, a fixed maximum packet size and a dynamically determined number of SP RUs.

[0353] After step 804, step 805 creates and sends an SP trigger frame having the characteristics determined at step 804. This SP TF transmission causes one or more nodes in the network to transmit their pending packets in random RUs during the SP TXOP. Step 805 also starts a new SP TF timer starting with the current wait interval value.

[0354] Figure 9 The typical processing of a node handling a trigger frame, in particular a TF dedicated to a collection of small packets (SPs), is shown.

[0355] At step 900, a node waits until a MAC packet addressed to the node is received.

[0356] Upon receiving such a MAC packet, the process proceeds to step 811 , where the node determines whether the received packet is an SP trigger frame.

[0357] To do this, the node reads the appropriate restriction indicator in the TF at step 901 (e.g., RU traffic type field 1521 - see Figure 15 ) to check whether at least one RU defined by TF is dedicated to the small packet.

[0358] If at least one RU defined by the TF is not dedicated to small packets, the received MAC packet is processed according to conventional mechanisms and the processing loop returns to step 900. In particular, in the case where the AP sends a trigger frame with no indication of a small packet set, but with a very short TXOP to force the node to send only small packets, the node performs conventional processing, which means that the node will look for appropriate (small packet) data in its transmission buffer queue.

[0359] If the received packet is an SP TF, step 902 is executed, during which the node determines whether the node has some small packets to transmit.

[0360] To do this, the node first determines a maximum packet size or overhead ratio. Depending on how the SPTF feature is defined as described above with reference to step 804, this maximum packet size or overhead ratio may be known in advance (fixed parameters) or (e.g., via field 1522 of each RU - see Figure 15 )Transmit the maximum packet size or overhead ratio in SP TF.

[0361] As is conventionally known, an 802.11 node typically has multiple in-order transmit queues (or Wi-Fi Multimedia (WMM) waiting queues). These queues are typically associated with a service class or access category as described above. Each WMM waiting queue is associated with a dynamic priority value, typically an AC backoff counter.

[0362] During a step 902, the node builds a list of packets to send (SP list).

[0363] In a first embodiment, given a maximum packet size or overhead, only the first packet (in transmission order in the queue) from the WMM transmit queue with the highest priority value (i.e., with the smallest backoff counter) is considered. Thus, a single packet is added to the list and is thus transmitted via the node during the current SP TXOP.

[0364] In a second embodiment, the first packet from each WMM transmit queue is considered, given a maximum packet size or overhead. Thus, (in the case of 4 802.11 WMM queues) a maximum of 4 packets are added to the list and thus transmitted during the current SP TXOP.

[0365] In a third embodiment, all packets from all WMM transmit queues are considered given a maximum packet size or overhead.

[0366] In a fourth embodiment, in addition to the four existing 802.11WMM queues, a node may also maintain a fifth transmit queue in which the node queues only small packets as they are generated for transmission (given a maximum small packet size or overhead). In this embodiment, all packets in the fifth transmit queue are considered to store only small packets.

[0367] Once the SP list has been constructed, step 903 determines whether the SP list is empty (ie, are there one or more packets to be sent?).

[0368] If the SP list is not empty, step 904 is executed. Otherwise, the process loops back to step 900.

[0369] At step 904, the node selects one or more RUs to send all or part of the packets in the SP list.

[0370] In the first embodiment, using Figure 5 The random allocation process 500 in selects only one RU, eg, a random RU, among the SP RUs.

[0371] In a second embodiment, if the SP list contains multiple packets, multiple RUs (eg, random RUs) may be selected, such as selecting one RU for each packet in the SP list. However, multiple packets for each RU may also be envisioned.

[0372] For illustrative purposes only, for the first and second embodiments described at step 902, one RU for each packet may be selected. In this configuration, the TXOP duration is preferably short so that the SP RU is designed to more or less fit within the maximum packet size. This reduces the amount of padding.

[0373] Still for illustration purposes, for the third and fourth embodiments described at step 902, multiple RUs may be selected, wherein the multiple RUs allow all packets in the SP list to be transmitted (in one or more RUs as needed).

[0374] If multiple RUs are to be selected, a random assignment process is applied, such as iteratively applying the above reference Figure 5 The process 500 is described to select all required RUs.

[0375] After step 904 , the node transmits the packet in the SP list in the selected RU at step 905 .

[0376] In the first embodiment and the second embodiment described above in step 902, each packet of the SP list may be sent on a different RU.

[0377] In the third and fourth embodiments described above in step 902, packets are aggregated (or concatenated) to fill the selected RU, for example, based on the TXOP duration. When the packets are aggregated, the TXOP duration can have a conventional length because multiple packets are sent within a single RU. Therefore, the aggregation helps reduce the amount of padding.

[0378] After step 905 , the process loops back to step 900 .

[0379] Now go to Figure 10a 、 10b 1 and 11, which use two flow charts to illustrate the general steps of an embodiment of the present invention for limiting the data to be transmitted on at least one resource unit to data of a restricted data type (particularly data of a specific service type). The service type of data generally refers to the four access categories defined in the 802.11 standard, namely, AC_BK for background data, AC_BE for best-effort data, AC_VI for video applications, and AC_VO for voice applications. Figure 10a and 10b is an optional flowchart from the perspective of the access point, and Figure 11 The following flowcharts are from the node's perspective. They all apply to multi-user OFDMA uplink in 802.11ax wireless medium.

[0380] Figure 10aThe typical process of AP generating a trigger frame (hereinafter also referred to as TT trigger frame or TT TF) that causes some traffic type (TT) to be transmitted via a node is shown. In this typical process, the sending of the TT trigger frame is driven by the number of reserved RUs (test 1003 below).

[0381] During AP initialization, the number of RUs to be allocated during OFDMA transmission is predetermined at step 1000. This number can be fixed or dynamically updated. Figures 12-14 As described in the embodiments, various bandwidths can be envisioned for RUs within the same composite channel.

[0382] Once the number of RUs is known, step 1001 involves having the node collect some statistics about the wireless network during one or more previous TXOPs. As described below, these statistics will be used to define a traffic policy, where each RU to be retained is associated with a traffic type through the traffic policy.

[0383] AP can track multiple events and statistics, such as:

[0384] - Collision rate (of collided RUs). This rate corresponds to the percentage of bandwidth loss due to collisions between nodes in an 802.11 network cell.

[0385] In the case of many collisions, many nodes compete for access to the wireless medium at the same time. As a result, bandwidth sharing driven by the AP can make wireless access smoother. Therefore, for example, when the collision rate is greater than a predetermined threshold, one or more TT trigger frames can be sent;

[0386] Statistics related to traffic types (e.g., the four 802.11 access categories). An example of a statistic is the portion of each traffic type in the total amount of data sent by the node. This statistic corresponds to network statistics related to the amount of data received in one or more previous transmission opportunities for each predefined traffic type.

[0387] Note that this statistical data enables the AP to assign RU traffic types to each RU in the TT trigger frame based on the portion of each traffic type in the overall traffic. Therefore, as network traffic evolves (due to evolving service requirements such as latency of each data traffic), the trigger frame configuration can be generated and adapted in the future.

[0388] - A queue size associated with each traffic type, representing the sum of all corresponding traffic waiting to be sent via all nodes.

[0389] As known from the 802.11 standard, the MAC header of a transmitted packet includes a "queue size" field that indicates the amount of buffered traffic of a given traffic type waiting in the transmitting node. Based on this information, the AP can calculate global statistics related to the total queue size for each predefined traffic type, where the total queue size for a predefined traffic type is the sum of the sizes of the transmit queues associated with that predefined traffic type in the node. The AP can then construct an associated TT trigger frame that defines the RU with the dedicated traffic type.

[0390] Following step 1001, step 1002 uses the statistical data to dedicate one or more RUs to each specific RU traffic type.

[0391] In case all RUs of the trigger frame are reserved for the dedicated traffic type (test 1003) (in the variant where a predetermined number of RUs are reserved for the dedicated traffic type), a trigger frame is constructed and broadcast to all nodes (1004 and 1005).

[0392] Figure 10b When trigger frames are sent periodically Figure 10a A variant of . Figure 10b In this embodiment, the sending of TT trigger frames is no longer driven by the number of reserved RUs (test 1003 below), but is driven by the service policy and mainly by the service delay.

[0393] Based on statistical data (including the delay associated with each of the four 802.11 standard access categories (voice, video, best effort, background) with different latency requirements (step 1011), the AP can determine the time interval before sending the next TT trigger frame at step 1012, which also depends on which traffic types will be associated with the RU of the TT trigger frame. Because the most critical access category is the video access category, the time interval for such a TT trigger frame including video access RUs will be shorter than the time interval for TT trigger frames including only RUs of other access categories.

[0394] In the second sub-process, the AP waits for the end of the determined time interval (test 1013) and then prepares a TT trigger frame (step 1004) before sending the TT trigger frame (step 1005).

[0395] Figure 11 Shows the node processing the trigger frame (especially according to Figure 10a or 10b via a typical processing of a TT trigger frame sent by an AP).

[0396] Upon receiving a TT trigger frame (ie, a trigger frame defining one or more RUs associated with a restricted traffic type) (test 1100), the node checks whether the TT trigger frame is a TT trigger frame indicating a single restricted traffic type (test 1101).

[0397] If only one restricted traffic type is defined in the TT trigger frame, the node selects the corresponding access category WMM queue (step 1120).

[0398] Next, the node checks (step 1121) whether there is at least one packet ready to be transmitted in the selected AC WMM queue. In this way, the node selects data in the transmission queue that stores data having only the determined restricted data type.

[0399] If there are one or more packets in the selected AS WMM queue, the node, for example, by using Figure 5 The process 500 for selecting a random RU associated with a restricted traffic type in FIG. 5 is used to select (step 1122) one (or more) RUs with a restricted traffic type.

[0400] Next, the node transmits the MPDU frame with the packet in the selected AS WMM queue in the selected RU (step 1123), and waits for a corresponding confirmation from the AP indicating a successful transmission (step 1124).

[0401] If two or more restricted service types (mixed service types) are defined in the TT trigger frame, the node considers the transmission queues in sequence in order from the highest to the lowest priority value until data is sent on the resource unit; and for each transmission queue considered in sequence, the node determines whether the resource unit in the communication channel has a restricted service type, and in the case of a positive judgment, transmits the data from the transmission queue currently considered on the determined resource unit.

[0402] As shown, the node first selects the access category with the (next) highest priority, ie, the access category with the current smallest backoff value (step 1110).

[0403] Next, the node parses the list of RUs defined in the received TT trigger frame to select the RU having the same traffic type as the (next) highest priority (step 1111).

[0404] If a single RU with the (next) highest priority traffic type is detected, that RU is selected (step 1122).

[0405] In the case of multiple RUs with appropriate service types, the following can be used: Figure 5A specific RU is selected using a random assignment process similar to process 500 in step 1122.

[0406] Once the RU is selected, the above steps 1123 and 1124 are executed to perform data transmission.

[0407] If the RU defined in the TT TF does not have a dedicated traffic type that matches the (next) highest priority traffic type, then a determination may be made as to whether unprocessed access categories remain (step 1112 ), in which case processing loops back to step 1110 .

[0408] Since the RUs are restricted to specific traffic types, the AP can efficiently adapt the TXOP to suit various types of traffic.

[0409] Now go to Figure 12 and 13 , which use two flow charts to illustrate the general steps of an embodiment of the present invention in which a trigger frame defines resource units with different bandwidths (ie, different numbers of tones) within a communication channel.

[0410] Figure 12 is a flowchart from the perspective of the access point, and Figure 13 The following flowcharts are from the node's perspective. They all apply to multi-user OFDMA uplink in 802.11ax wireless medium.

[0411] Figure 12 A typical process of an AP generating a trigger frame defining resource units with different RU widths within a communication channel is shown.

[0412] The process begins at step 1200, where the AP collects statistics about the traffic in the network cell (BSS), such as statistics about each traffic type (e.g., the four 802.11 access categories - video, voice, background, best effort). An example of statistics is the portion of each traffic type in the overall amount of data sent by a node. Other statistics may include the number of registered nodes, the modulation scheme (MCS) used by each node, the modulation scheme (MCS) used on each RU, the identification of steady traffic (video streaming, VoIP, ...) or random traffic (web browsing, control frames, ...), the average duration of transmissions (in the absence of padding, i.e., by excluding the padding duration, the duration of transmissions outside of or within a multi-user OFDMA uplink transmission).

[0413] Next, at step 1210, the AP determines the number of concurrent (ie, simultaneous) nodes and / or traffic types.

[0414] The AP uses the number of concurrent nodes / traffic to define the number of RUs to be allocated in the MU UL TXOP. For example, the greater the number of simultaneous nodes / traffic, the greater the number of RUs.

[0415] For illustration purposes, the number of RUs may be set equal to N previous TXOPs (possibly to implement Figure 12 and 13 The number of active nodes (i.e., transmitting data) in the TXOP of this embodiment is determined. This method is used, for example, when each node can only send data of a single service type. This method can also be applied when a node is forced to send data of only one service type.

[0416] In any case, a service type is associated with each RU.

[0417] Thus, step 1202 involves reserving the RU in the TF for a particular node or service.

[0418] Note that the RU allocation in step 1202 should preferably take into account the number of concurrent data services within each node, because a corresponding number of RUs should be provided for a specific node (if possible). For example, a node can transmit two separate data services via an AP: video streaming can coexist with VoIP communication in a smartphone.

[0419] As a result, the number of RUs can be set equal to the number of RUs in N previous TXOPs (possibly to achieve Figure 12 and 13 The number of pairs (service type, transmitting node) detected during the TXOP of this embodiment.

[0420] Therefore, step 1202 defines the optimal number of RUs that should be provided to meet the network requirements, where each RU is dedicated to each service type. Note that this optimal number of RUs does not necessarily correlate with the actual number of RUs available at that stage of processing (which means that the optimal number can be greater than the number of possible RUs in the composite channel).

[0421] Next, steps 1203 and 1204 are performed in relation to each other and may be looped to avoid inconsistencies with the duration of the TXOP or the number of RUs and the corresponding bandwidth defined first, as well as inconsistencies with other situations related to the first defined information.

[0422] At step 1203, the AP calculates the duration of the next MU UL transmission, ie, the next TXOP triggered by the trigger frame to be sent.

[0423] To this end, the AP determines (based on statistics related to, for example, the previous N TXOPs or based on the service type associated with the RU determined at step 1202) which types of data services are currently being transmitted in the network, and more particularly determines the redistribution of the data services, for example according to the four 802.11AC protocols, to adjust the TXOP duration accordingly.

[0424] More generally, the duration may be determined based on the average duration of the N (integer) previous transmissions to minimize padding on average.

[0425] In a variant, the duration can also be determined to prioritize some services. For example, if a lot of best-effort services were transmitted in the RU during one or more previous TXOPs, a short TXOP duration can be selected, for example, by selecting a time that allows the transmission of a typical amount of data for the best-effort access category (based on the statistics obtained in 1200). On the other hand, if multiple video streams are ongoing, a larger TXOP duration can be selected, preferably close to the TXOP limit defined for the video access category.

[0426] In the absence of any statistical data, the TXOP duration can be set to 1 / 4 of the TXOP limit duration of the video access category (AC_VI). Therefore, one RU with a width of 106 tones is allocated to video-AC_VI (or services with a large amount of data to be transmitted), one RU with a width of 52 tones is allocated to VoIP-AC_VO (or services with a medium amount of data to be transmitted), and three RUs with 26 tones each are allocated to the best effort service, background access categories (AC_BE, AC_BK) and control packets in the 20MHz channel, that is, one RU is allocated to each service category on the 20MHz band.

[0427] Once the TXOP duration is determined, the AP defines the RU characteristics for the next TXOP at step 1204 .

[0428] Such characteristics include the number of RUs.In addition, in case the TXOP duration is set, the other main RU characteristic to be determined is the bandwidth (number of tones) of each RU forming the TF.

[0429] Based on the TXOP duration and the amount of data to be transmitted for each service type (a list of optimal RU allocations and associated data amounts), the AP determines the bandwidth of each RU (for each service type) in the form of tones (the amount of data to be transmitted is a function of the TXOP duration and RU_width_in_tones).

[0430] The AP then determines how to allocate the available tones on the composite channel to each RU to define the TF. The AP takes into account the RU_width_in_tones for each traffic type.

[0431] For example, four RU_width_in_tones (26 tones, 52 tones, 106 tones, and 242 tones) may be defined for a 20 MHz channel.

[0432] For a 20 MHz channel in the OFDMA MU uplink, the maximum number of RUs defined with respect to RU_width_in_tones can be defined as follows: 9 RUs each with 26 tones; or 4 RUs each with 52 tones + 1 RU with 26 tones; or 2 RUs each with 106 tones + 1 RU with 26 tones; or 1 RU with 242 tones. These are typical RU configurations from a wide set of possible RU configurations. The only limitation on mixing different RU_width_in_tones is the maximum number of tones in the channel (e.g., for 20 MHz, the maximum number is 242 tones).

[0433] Returning to the previous RU configuration example, the AP may allocate, for example, 3 RUs with 26 tones + 1 RU with 52 tones + 1 RU with 106 tones in a 20 MHz channel.

[0434] If the number of required RUs, defined as the optimal number of RUs at step 1202, is greater than the capacity of the composite channel given the RU_width_in_tones for each traffic type, prioritization is performed. Prioritization can be performed based on traffic class to prioritize stable flows, small packets, or to minimize padding as much as possible by excluding RUs for which the actual transmission duration of useful data (obtained by taking into account the modification of the duration applied by the number of allocated tones) is significantly different from the TXOP duration defined in the previous step. These RUs are those for which too little data is scheduled for transmission.

[0435] After the RU characteristics are allocated and defined, the TXOP duration can be refined (if necessary) to adjust the transmission duration to take advantage of the available RU time slots.

[0436] The RU bandwidth is preferably determined based on the traffic type, where the traffic type is specific as determined based on the statistical data at step 1202. That is, the bandwidth of the resource unit is determined based on the statistical data related to the data related to each traffic type received in one or more previous transmission opportunities. Figure 10a 、 10bThe mechanism described in Figure 11 explicitly assigns RUs to specific service types in TF.

[0437] However, this specific traffic type may not be signaled in the TF. This is because by designing RUs with appropriate sizes, the node will select data that is well-suited to the RU's available bandwidth, implicitly specifying the intended content (traffic type). For example, for large content such as video, a RU with a large bandwidth is implicitly specified.

[0438] An example of RU bandwidth is as follows: the AP allocates more than 4 times the tones allocated to the video RU_traffic_type as the tones allocated to the background RU_traffic_type, and allocates more than 2 times the tones allocated to the voice RU_traffic_type as the tones allocated to the background RU_traffic_type to maintain the differentiation provided by the TXOP limit parameters of the 802.11n standard. In other words, the resource units associated with the AC_BK and AC_BE traffic types have a first bandwidth (e.g., the minimum bandwidth permitted by the 802.11 standard, i.e., 2.03 MHz when a 20 MHz channel is divided into 9 RUs), the resource units associated with AC_VO have a bandwidth equal to twice the first bandwidth, and the resource units associated with AC_VI have a bandwidth equal to 4 times the first bandwidth.

[0439] Due to the 1 / 4 ratio of the bandwidth between the AC_BK RU and the AC_VO RU, the TXOP duration is preferably set to be less than or equal to one quarter of the TXOP limit parameter set for the wireless network according to the 802.11 standard.

[0440] For illustrative purposes, the 802.11n standard defines the following TXOP limits: a TXOP limit of 3.008 ms for the video access category (AC_VI), a TXOP limit of 1.504 ms for the voice access category (AC_VO), and a TXOP limit of 0 ms (i.e., 1 MPDU) for the background and best-effort access categories (AC_BK and AC_BE, respectively). When implementing this embodiment, AC_BK and AC_BE can be defined as having the lowest number of tones (i.e., 26 tones), AC_VO as having twice as many tones (i.e., 52 tones), and AC_VI as having four times as many tones (i.e., 106 tones). For this configuration, the duration of the MU UL transmission, which defines the TXOP duration, is set to 752 μs (3.008 ms / 4).

[0441] Additionally, the bandwidth (number of tones) of the RU may also depend on the modulation scheme (MCS) used by the node to reach the AP (which may also affect the transmission duration) (the MCS may be defined by each node, but again for each RU in each node). In other words, the bandwidth of the resource units associated with a traffic type is adjusted based on the modulation scheme used by the node to send data with the associated traffic type in one or more previous transmission opportunities.

[0442] On the other hand, the AP can also set the MCS to minimize padding and maximize BER.

[0443] Once all RU characteristics are known, a TF can be generated and sent over the network at step 1205. Figure 15 Further explain the signaling of some RU features in TF.

[0444] Note that for random RUs, the TF should signal at least the TXOP duration, the number of random RUs, and the bandwidth of each random RU (RU_width_in_tones). If the RU is explicitly dedicated to a specific traffic type, the RU_traffic_type field is used to signal that specific traffic type in the TF. If the number of tones is fixed for each traffic type, RU_traffic_type can be replaced by RU_width_in_tones.

[0445] After the TF is sent, the AP waits for the end of the TXOP at step 1206 and sends an acknowledgment (1207) if appropriate to acknowledge receipt of all or part of the MPDUs transmitted from multiple users within the OFDMA TXOP.

[0446] Preferably, the ACK frame is transmitted in non-HT duplication format in each 20 MHz channel covered by the reservation of the initial TF.

[0447] Next, at step 1208, the AP updates its statistics based on the current transmission.

[0448] Figure 13 Shows the node processing the trigger frame (especially according to Figure 12 Typical processing of trigger frames sent by AP.

[0449] At step 1300, the node detects a trigger frame that reserves a composite channel. The TF is then decoded to analyze its content. The TF defines multiple RUs.

[0450] At step 1301, the node selects one (or more) of the RUs using the RU characteristics specified in the TF. The selection may also be based on the type of traffic that must be transmitted.

[0451] The node selects any scheduled RU corresponding to its node_AID and determines the possible traffic type (if any) associated with the scheduled RU. This is to send appropriate data in the RU.

[0452] For random RUs, the node selects one (or more) of the following random RUs:

[0453] The random RU(s) have a signaled traffic type corresponding to the traffic type that the node has to transmit (e.g. from a priority AC queue). This is to drive the node to transmit data on a resource unit with the same traffic type as that associated with the resource unit.

[0454] Alternatively, the random RU(s) have a bandwidth, expressed in tones, that matches the maximum amount of data that the node must transmit (e.g., from a priority AC queue) given the TXOP duration. This means that the node determines whether one of the resource units matches the amount of data to be sent in the transmission queue with the highest priority value, and only in the event of a positive determination does the node transmit the data from the transmission queue with the highest priority value on the matching resource unit.

[0455] The node may also use other information from the TF, such as MCS, to adjust its transmission parameters.

[0456] Next, at optional step 1302, the node may adapt or adjust the modulation scheme used to modulate the data on the resource unit (possibly multiple resource units), the adaptation maximizing the duration of the data transmission within the transmission opportunity. This step of reducing the MCS attempts to minimize padding relative to the TXOP duration of the next MU UL transmission. However, the same amount of data is transmitted, but with a better BER.

[0457] Next, at step 1303 , the node transmits data on each RU of the one or more RUs selected at step 1201 .

[0458] At step 1304, the node waits for confirmation from the AP.

[0459] Upon receiving confirmation of successful transmission, the node clears the buffered data from the AC transmission queue at step 1305, thereby ending the process.

[0460] and Figure 5a Compared with the situation in Figure 14 Show Figure 12 and 13The embodiments in FIG. 4 provide benefits in terms of padding reduction. These benefits rely on selecting different RU configurations based on data traffic and / or node characteristics.

[0461] As shown in the figure, the AP sends Figure 5a Compared to the TF of a RU with different bandwidth (expressed in number of tones) and shorter TXOP duration 550'. In other words, the AP modifies both dimensions of the RU (TXOP duration and bandwidth expressed in tones) to optimize padding.

[0462] In the example in the figure, the PPDU of node STA4 is Figure 5a and Figure 14 The same amount of data is included between them. However, due to Figure 5a The RU used in the Figure 14 The RU used in

[15] consists of 80 tones, so the TXOP duration is significantly reduced (i.e., divided by about 3 in this example).

[0463] On the other hand, due to the reduction of TXOP duration (made possible due to the bandwidth of each RU), the MU UL duration is increased by 50%. Figure 5a Many of the padded nodes in STA1 (eg, STA1, STA2, STA6) now send significantly reduced amounts of padding.

[0464] Note that nodes that have not been allocated RUs (STA3, STA7, and STA8 cannot transmit in this MU UL OFDMA transmission) will transmit in the next MU UL transmission or via legacy access to the wireless medium (EDCA).

[0465] Figure 12 and 13 The embodiments in can be applicable to both random RUs and scheduled RUs.

[0466] Before using scheduled RUs, random RUs may be used when creating a network cell driven by an AP.

[0467] Initially, the initial number of random RUs can be defined using predefined statistics that define the proportions of different traffic types in a cell and the typical number of nodes in the cell based on AP characteristics (office, home, stadium, etc.). The TXOP duration and RU bandwidth can be defined by maintaining the scaling factors of the 802.11 standard, for example, 26 tones for AC_BK and AC_BE, 52 tones for AC_VO, and 106 tones for AC_VI, while setting the MU UL transmission duration to 750 μs.

[0468] The initial random-based phase may be a temporary step used as a learning phase to learn the types of traffic sent by each node, the modulation used by each node, and / or the modulation on each RU, etc., before using the scheduling-based mode. In other words, the initial random-based phase is a phase in which the nodes collect or gather statistical data as described above with reference to step 1200.

[0469] During this learning phase, the random RU can be dynamically adjusted or improved based on dynamically collected statistical data. This is to gradually modify the RU to reflect the actual traffic ratio and the number of active registered nodes.

[0470] As a result of this learning phase, the width of each RU and its allocation to dedicated nodes can be precisely defined according to the current network usage. Preferably, the selection of the RU width is based on the traffic type, but also on the modulation scheme, since the modulation scheme can significantly modify the transmission duration required for a fixed amount of data (e.g., modulation MCS 0 provides a bit rate of 6.5 Mbps, while modulation MCS 1 provides a bit rate of 13 Mbps).

[0471] Next, the scheduled RU mode is used where the AP explicitly allocates the designed RUs to specific nodes based on node requirements (e.g., node requirements transmitted during a previous TXOP; or the AP can use service specifications supplied by some nodes to define their requirements (e.g., TSPEC in HCCA)).

[0472] Figure 15 The format of the "RU Information Element" (1510) is presented, wherein the "RU Information Element" (1510) can be used to signal the packet attributes of the TF and / or the service type attributes of the TF and / or the RU bandwidth attributes.

[0473] The AP uses the "RU Information Element" (1510) to embed additional information within the trigger frame related to the OFDMA TXOP. The format of the "RU Information Element" (1510) preferably follows the "Vendor Specific Information Element" format as defined in the IEEE 802.11-2007 standard.

[0474] The "RU Information Element" (1510) is a container for one or more RU attributes (1520), each of which has a dedicated attribute ID for identification. The header of the RU IE can be standardized (and therefore easily recognized by nodes) through the element ID, OUI, and OUI type values.

[0475] The RU attribute 1520 is defined to have a common general format including a 1-byte RU attribute ID field, a 2-byte length field, and a variable-length attribute specific information field.

[0476] The use of information elements within the MAC frame payload is given for illustration only, any other format is supportable.

[0477] The choice of embedding additional information in the MAC payload is advantageous for maintaining legacy compliance with the medium access mechanism, since any modification within the PHY header of the 802.11 frame will prohibit any successful decoding of the MAC header by legacy devices.

[0478] As shown in the figure, the dedicated RU attributes follow the following format:

[0479] - Attribute ID is a dedicated value used to identify "RU Information". A value not used in the standard (e.g., in the range 19 to 221) may be selected. This 1-byte value is a tag that activates "RU Information".

[0480] - A 2-byte length field defining the length of the attribute body.

[0481] The attribute body varies depending on the embodiment under consideration. The attribute body 15a refers to Figure 8 and 9 In the packet embodiment; attribute body 15b refers to Figure 10a 、 10b and the business type embodiment in 11; and attribute body 15c refers to Figure 12 and 13 Example of varying RU width.

[0482] To efficiently signal the packet mode ( Figure 8 and 9 ), the attribute body 15a of a given RU (or the entire TF) may include:

[0483] The SP Type field 1521 is used to indicate whether the RU (or all RUs) is limited to small packets (or whether the IF is an SP TF). This field, when set to SP Type (Small Packet Type), indicates to the receiving node that the RU (or all RUs) can only be used to send small packets, such as packets smaller than the maximum packet size.

[0484] Maximum packet size field 1522, which is used by the AP to explicitly define the maximum size of a packet.

[0485] In order to efficiently signal the service type mode ( Figure 10a 、 10b and 11), the attribute body 15b may include:

[0486] The TF_type field 1523 is used to indicate whether the trigger frame specifies the mixed mode in step 1101 (i.e., specifies a list of RUs with the same service type or a list of RUs with different mixed service types);

[0487] RU_nb field 1524, used to define the number of resource units comprising the composite channel. This number also gives the number of entries in the next field;

[0488] RU_list field 1525, which lists the characteristics of each RU in the current OFDMA TXOP. Each entry in list 1525 may include the following fields:

[0489] The RU_index field is used to specify the index of the current RU in the RU list;

[0490] RU_type field, used to specify the random mode or scheduled mode of the RU (only in the case of mixed mode);

[0491] The RU_traffic_type field is used to specify the service type supported by the RU; and

[0492] The optional Node_AID field is used to define the identifier of the node in the case of a scheduled RU. This identifier can be the node's MAC address, or an association identifier (AID), or a partial AID.

[0493] In order to efficiently signal the RU bandwidth ( Figure 12 and 13 ), the attribute body 15c of a given RU may include:

[0494] RU_nb field 1524, used to define the number of resource units comprising the composite channel. This number also gives the number of entries in the next field;

[0495] RU_list field 1525, which lists the characteristics of each RU in the current OFDMA TXOP. Each entry in list 1525 may include the following fields:

[0496] The RU_index field is used to specify the index of the current RU in the RU list;

[0497] The RU_width_in_tones field specifies the number of tones for this RU.

[0498] RU_type field, used to specify the random mode or scheduled mode of the RU (only in the case of mixed mode);

[0499] The RU_traffic_type field is used to specify the service type supported by the RU;

[0500] The optional MCS field specifies the modulation scheme to be used by the RU; and

[0501] The optional Node_AID field is used to define the identifier of the node in the case of a scheduled RU. This identifier can be the node's MAC address, or an association identifier (AID), or a partial AID.

[0502] All or part of the various attributes described above may be combined to, for example, define an SP triggered frame, where the SP triggered frame is also a TT triggered frame with a bandwidth-variable RU.

[0503] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to these specific embodiments, and modifications within the scope of the invention will be apparent to those skilled in the art.

[0504] While referring to the foregoing illustrative embodiments, which are given by way of example only and are not intended to limit the scope of the invention, which is determined solely by the appended claims, many further modifications and variations will be suggested to those skilled in the art. In particular, different features from different embodiments may be interchanged where appropriate.

[0505] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

Claims

1. A communication device comprising: a receiving unit configured to receive a trigger frame from another communication device, the trigger frame including information for dividing a plurality of resource units of one or more communication channels in the frequency domain; as well as a sending unit configured to send data to the other communication device in response to the trigger frame received by the receiving unit, The trigger frame includes information indicating an access category specified in the IEEE 802.11 series of standards for each resource unit in the plurality of resource units.

2. The communication device according to claim 1, wherein The data sent by the sending unit includes multiple MAC protocol data units.

3. The communication device according to claim 1 or 2, wherein: The information indicating the access category is information indicating any one of AC_BK for background data, AC_BE for best effort data, AC_VI for video applications, and AC_VO for voice applications.

4. The communication device according to claim 1 or 2, wherein: The trigger frame is a trigger frame that complies with the IEEE 802.11ax standard.

5. The communication device according to claim 1 or 2, wherein: Each resource unit among the multiple resource units is a resource unit that complies with the IEEE 802.11ax standard.

6. The communication device according to claim 1 or 2, wherein: The bandwidth of each resource unit in the plurality of resource units is the minimum bandwidth defined in the IEEE 802.11ax standard.

7. The communication device according to claim 1 or 2, wherein: Each resource unit of the plurality of resource units includes a plurality of subcarriers constituting orthogonal frequency division multiplexing.

8. The communication device according to claim 1 or 2, wherein: The sending unit sends the data to the other communication device using communication compliant with Orthogonal Frequency Division Multiple Access.

9. The communication device according to claim 1 or 2, wherein: The trigger frame further includes information on a time ensured for the communication device.

10. A communication method in a communication device, comprising the following steps: receiving a trigger frame from another communication device, the trigger frame including information for partitioning a plurality of resource units of one or more communication channels in the frequency domain; as well as sending data to the other communication device in response to the received trigger frame, The trigger frame includes information indicating an access category specified in the IEEE 802.11 series of standards for each resource unit in the plurality of resource units. The communication method according to claim 10 , wherein: The transmitted data includes a plurality of MAC protocol data units.

12. The communication method according to claim 10 or 11, wherein: The information indicating the access category is information indicating any one of AC_BK for background data, AC_BE for best effort data, AC_VI for video applications, and AC_VO for voice applications.

13. The communication method according to claim 10 or 11, wherein: The trigger frame is a trigger frame that complies with the IEEE 802.11ax standard.

14. The communication method according to claim 10 or 11, wherein: Each resource unit among the multiple resource units is a resource unit that complies with the IEEE 802.11ax standard.

15. The communication method according to claim 10 or 11, wherein: The bandwidth of each resource unit in the plurality of resource units is the minimum bandwidth defined in the IEEE 802.11ax standard.

16. The communication method according to claim 10 or 11, wherein: Each resource unit of the plurality of resource units includes a plurality of subcarriers constituting orthogonal frequency division multiplexing.

17. The communication method according to claim 10 or 11, wherein: The data is transmitted to the other communication device using communications compliant with Orthogonal Frequency Division Multiple Access.

18. The communication method according to claim 10 or 11, wherein: The trigger frame further includes information on a time ensured for the communication device.

19. A non-transitory computer-readable medium storing a program which, when executed by a microprocessor or a computer system in a communication device, causes the communication device to perform the communication method according to claim 10.

20. A communication device comprising: a receiving unit configured to receive a trigger frame from an access point, wherein the trigger frame notifies two or more communication devices including the communication device to divide at least one wireless communication channel into a plurality of resource units in the frequency domain, wherein the plurality of resource units can be used by one or more other communication devices, and wherein the trigger frame includes two or more association identifier fields (AID fields) for specifying two or more other communication devices to be transmitted, and each AID field is associated with an indicator field, and each value stored in each indicator field represents an access category defined in the Institute of Electrical and Electronics Engineers 802.11 standard (IEEE 802.11 standard); and A transmitting unit is configured to transmit data to the access point on one or more resource units assigned to the communication device in the trigger frame if a specific AID corresponding to the communication device is stored in any AID field of the trigger frame.

21. The communication device according to claim 20, wherein: The data sent by the sending unit includes multiple MAC protocol data units.

22. The communication device according to claim 20 or 21, wherein: The access category represented by using the indicator field is one of: AC_BK for background data, AC_BE for best effort data, AC_VI for video applications, and AC_VO for voice applications.

23. The communication device according to claim 20 or 21, wherein: The trigger frame is a trigger frame that complies with the IEEE802.11 standard.

24. The communication device according to claim 20 or 21, wherein: Each resource unit among the plurality of resource units is a resource unit that complies with the IEEE802.11ax standard.

25. The communication device according to claim 20 or 21, wherein: The bandwidth of each resource unit in the plurality of resource units is the minimum bandwidth defined in the IEEE 802.11ax standard.

26. The communication device according to claim 20 or 21, wherein: Each resource unit of the plurality of resource units includes a plurality of subcarriers constituting orthogonal frequency division multiplexing.

27. The communication device according to claim 20 or 21, wherein: The sending unit sends the data to the access point using communication compliant with Orthogonal Frequency Division Multiple Access.

28. The communication device according to claim 20 or 21, wherein: The trigger frame further includes information on a time ensured for the communication device.

29. The communication device according to claim 20 or 21, further comprising: a determining unit configured to determine data having an access category from a local transmission memory by using an indicator field associated with an AID field storing the specific AID in the trigger frame, and The determined data is transmitted during the transmission.

30. The communication device according to claim 20 or 21, wherein: Each AID field is associated with a field storing an index for specifying a resource unit to be used by a corresponding other communication device among the two or more other communication devices specified by the value of the respective AID field.

31. A computer program product comprising a program which, when executed by a microprocessor or a computer system in a communication device, causes the communication device to perform the communication method according to claim 10.

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