Canon Kabushiki Kaisha

Canon Research Centre France

Stéphane Baron

Pascal Viger

Patrice Nezou

Julien Sevin

Romain Guignard

Hervé Le Floch

Pascal Rousseau

François Thoumy

Brice Le Houerou

Eric Nguyen

Mickaël Lorgeoux

An 802.11ax access point, AP, manage a granted transmission opportunity to schedule multi user uplink and downlink transmissions with non-AP stations. Resource units may also be allocated to non-AP stations for direct link, DiL, transmissions. To efficiently arbitrate between scheduling new MU UL transmissions or DiL transmissions, the AP must know the needs of the non-AP stations. The buffer status report, BSR, either solicited or unsolicited, provides an ACI Bitmap subfield and a Delta TID subfield to signal a number of TIDs for which buffered uplink traffic is declared. The BSR is amended so that these two subfields further signal, in addition to the buffered UL traffic, when there is buffered DiL traffic. Other subfields may provide more information on the amount of buffered DiL traffic.

Buffer status report signaling both buffered uplink traffic and buffered direct link traffic

The present invention provides according to one of its aspects a method of communication in a wireless network comprising an access point and a plurality of stations, the method comprising, at one of the stations:

Multi-user random access in a wireless network

In a 802.11 be multi-AP collaboration, collaborated devices obtaining shared resources announced by a collaborator AP re-announce the shared resource for the stations out of the transmission range of the collaborator AP. Given the short time available, the re-announcing frame binary repeats most of the initial announcement by the collaborator AP, in particular substantially the whole MAC payload thereof. In order to facilitate the identification of the re-announcing, the latter comprises an empty TA field or no TA field in its header. This additionally allows any AP to act as the coordinator AP.

Methods and apparatuses for optimized multi-AP coordination

A physical AP manages a plurality of BSSs through VAPs. The AP sends a trigger frame to reserve a TXOP including resource units the nodes access to transmit data during the reserved TXOP. To improve channel utilization, the trigger frame identifies a plurality of groups, nodes of which are allowed to access the resources units to transmit data during the reserved TXOP. Thus, the AP receives, during the reserved TXOP, data from one node of a first group identified in the trigger frame and data from one node (separate from the first one) of a second and separate group identified in the trigger frame. A single access by the AP to the medium is thus required, reducing the channel occupation due to control frames. In some embodiments, the number of trigger frames can be drastically reduce, while offering resource units to several BSSs.

Access to random resource units by a plurality of BSSs

Aspects of the present disclosure generally relate to enhanced multi-user (MU) uplink (UL) protocols in wireless networks that allow non-UL transmissions to be performed simultaneously with triggered MU UL transmissions. A station may send a trigger frame triggering MU transmissions with an appropriate signaling to allow non-UL transmissions, i.e. transmission to another station, in a resource unit of the MU transmission. Examples of non-UL transmissions include Direct Link transmissions as well as downlink (DL) transmissions. The present disclosure regards how the MAC/PHY interface at an AP and at non-AP stations can be modified to efficiently handle the DiL and DL transmissions. On one hand, a non-AP station recipient of DiL or DL transmissions can use an 802.11ax TRIGVECTOR to efficiently configure its PHY. On the other hand, the AP can configure its PHY to filter out the DiL/DL RUs.

MAC/PHY interface of wireless stations compliant to direct link and downlink transmissions in trigger-based multi-user transmissions

A flexible NFRP procedure is proposed where the AP can adjust the granularity of the possible answers to a given question. The NFRP trigger frame includes a tone set configuration indication representative of a number of tone groups per RU tone set. The number of possible FEEDBACK_STATUS values consequently also varies, making it possible for the AP to poll the stations for more detailed feedback reports. A station determines which FEEDBACK_STATUS values are available, calculates its FEEDBACK_STATUS value and retrieves the corresponding subset of tone groups on which energy must be sent. Due to the multiples existing tone set configurations, the station also determines the tones forming the subset to be activated, based on the tone set configuration indication. The station can then properly send its feedback report response by activating (emitting energy on) the appropriate tunes and therefore the appropriate tone groups.

Variable configurations of NFRP RU tone sets in wireless networks

Association procedure in 802.11 networks is bandwidth consuming because the management frames are sent in the low bitrate Single User mode. Multi-user operations are not available for unassociated stations because they are not assigned association identifiers. The present invention proposes to provide temporary AIDs to unassociated stations sending a frame to the AP, wherein the temporary AIDs are conveyed by a multi-station block acknowledgment. In an efficient scenario for station association, unassociated stations randomly access tone sets of a short feedback procedure. Based on the feedback responses, the AP subsequently provides MU UL RUs for the unassociated station to send a first management frame. Subsequently, the temporary AID may be used to schedule further MU UL RUs and to provide response in MU DL transmissions.

Temporary aids for unassociated stations in communication networks

The invention relates to wireless network comprising an access point and non-AP stations. The station has traffic queues and associated a backoff counters which are decremented over time upon continuously sensing the medium as free during more than respective AIFS durations. To compensate additional opportunities provided by OFDMA RUs, a queue switches to an MU mode upon transmitting its data in an RU provided by the AP. To restore dynamicity of the backoff counters, frozen in the MU mode in the known techniques, embodiments provide the following at each expiry of one of the queue backoff counters: the current mode of the expiring traffic queue is determined; in case of legacy mode, the station accesses the channel to transmit data from the queue; whereas in case of MU mode, a new backoff value is drawn to reset the expiring backoff counter, without having data from the queue being transmitted.

QoS management for multi-user EDCA transmission mode in 802.11ax networks

802.11ax nodes benefit from additional medium accesses through multi-user uplink provided by an AP, compared to legacy node. To restore fairness in medium access, the invention proposes to update node's EDCA parameters, in particular EDCA backoffs, using penalty values each time the node successfully transmits data to the AP over OFDMA resource units. This is to reduce the probability for the node to access anew a communication channel through conventional EDCA contention. The penalty value is preferably provided by the AP which has an overview of the system and may be adjusted based on information local to the node, for instance the amount of data transmitted or its current contention window. For instance, the penalty value is added to the current value of the EDCA backoff counters upon successful OFDMA transmission by the node.

Restored fairness in an 802.11 network implementing resource units

To avoid blocking node AC queues in the degraded MU EDCA mode due to regular OFDMA transmission of data from another AC queue in resource units provided by an AP, the present invention proposes to use a dedicated HEMUEDCATimer for each AC queue, in order for them to be able to exit the degraded MU EDCA mode independently of the other AC queues. In this respect, upon successfully transmitting data stored in two or more traffic queues, in each of one or more accessed resource units provided by the AP within one or more transmission opportunities, the node sets each traffic queue transmitting in the accessed resource unit in the degraded MU EDCA mode for a predetermined degrading duration counted down by a respective timer associated with the transmitting traffic queue. Next, upon expiry of any timer, the node switches back the associated traffic queue to the conventional EDCA mode.

Enhanced management of ACs in multi-user EDCA transmission mode in wireless networks

In 802.11ax networks with access points, a trigger frame offers scheduled and random resource units to nodes for data uplink communication to the access points. To make more effective the usage of the network, the access point may design the trigger frame to force the nodes to send some categories of data. Resource units may be defined in trigger frames to be dedicated to small packets or to some access category data. Adjusting the time length of the resource units helps restricting the type of data that can be conveyed by the resource units. Also, using various frequency widths for resource units in the same trigger frame helps reducing padding in the resource units when various traffic types coexist.

Trigger frames adapted to packet-based policies in an 802.11 network

The present invention relates to a wireless communication method in a wireless network comprising an access point and stations. The method comprises, at a station: receiving a trigger frame from the access point, the trigger frame reserving a transmission opportunity on at least one communication channel of the wireless network, the transmission opportunity including a random resource unit that the stations may access using a contention scheme; receiving parameters of the contention scheme in management frames from the access point, the parameters comprising a contention window range; contending access to the random resource unit of the transmission opportunity reserved by the received trigger frame, using a contention window value; and updating the contention window value based on the success or failure of the access to the random resource unit. The updated contention window value remains within the contention window range obtained from the most recently received contention scheme parameters.

Access management to multi-user uplink random resource units by a plurality of BSSs

The invention provides a random access mechanism for short feedback procedure. An AP provides a random-access NFRP trigger frame defining a random access for the stations to a plurality of RU tone sets. A non-AP station randomly selects a responding RU tone set from the plurality of RU tone sets and send a NDP feedback report response on the selected responding RU tone set. A dedicated backoff counter may be used for the purposes of contention to the random RU tone sets. A subsequent UL MU transmission can then be scheduled by the AP for the NDP responding stations. No unused RU is expected, improving the random-access network efficiency. Also, the number of non-AP stations that can be targeted by the random-access NFRP trigger frame can be easily increased.

Random access for short feedback procedures in wireless networks

In an 802.11ax network with an access point, a trigger frame offers scheduled and random resource units to nodes for data uplink communication to the access point. To avoid the overall energy level seen by legacy nodes for a communication channel to drop below a detection threshold, the invention provides two tools. First, the scheduled and random resource units may be interleaved over communication channels. Second, unused resource units may be detected, and a node or the access point may send a padding signal on them to increase the overall energy level. The latter may be evaluated during a monitoring period before deciding to emit the signal. As the overall energy level seen by legacy nodes is increased, the risk that such legacy nodes do not detect activity on a 20 MHz channel having only a subpart of its RUs used is reduced. And risks of collisions are consequently reduced.

Emission of a signal in unused resource units to increase energy detection of an 802.11 channel

Aspects of the present disclosure generally relate to a wireless communication method in a wireless network comprising a plurality of access points (APs) sharing a communication channel, each AP is configured to manage stations of a basic service set (BSS), the method comprising at a coordinator AP: signaling to another AP, referred to as coordinated AP, that the coordinator AP has gained access to the communication channel; and sending to the coordinated AP a resource allocation allocating a chunk of the communication channel for stations managed by the coordinated AP.

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Le Rheu, France

Stéphane Baron