Patent ID: 12225519

DETAILED DESCRIPTION

Reference will now be made in detail to several embodiments. While the subject matter will be described in conjunction with the alternative embodiments, it will be understood that they are not intended to limit the claimed subject matter to these embodiments. On the contrary, the claimed subject matter is intended to cover alternative, modifications, and equivalents, which may be included within the spirit and scope of the claimed subject matter as defined by the appended claims.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. However, it will be recognized by one skilled in the art that embodiments may be practiced without these specific details or with equivalents thereof. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects and features of the subject matter.

Portions of the detailed description that follow are presented and discussed in terms of a method. Although steps and sequencing thereof are disclosed in a figure herein (e.g.,FIGS.6-8) describing the operations of this method, such steps and sequencing are exemplary. Embodiments are well suited to performing various other steps or variations of the steps recited in the flowchart of the figure herein, and in a sequence other than that depicted and described herein.

Some portions of the detailed description are presented in terms of procedures, steps, logic blocks, processing, and other symbolic representations of operations on data bits that can be performed on computer memory. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A procedure, computer-executed step, logic block, process, etc., is here, and generally, conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout, discussions utilizing terms such as “accessing,” “configuring,” “setting,” “storing,” “transmitting,” “retransmitting,” “authenticating,” “identifying,” “requesting,” “reporting,” “determining,” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.

Some embodiments may be described in the general context of computer-executable instructions, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments.

Group Addressed Frame Wireless Transmission for Constrained Multi-Link Operation

The term station (STA) refers generally to an electronic device capable of sending and receiving data over Wi-Fi that is not operating as an access point (AP).

Multi-link operations can provide higher network throughput and improved network flexibility compared to traditional techniques for wireless communication. Constrained MLDs are devices that cannot send and receive data over multiple links simultaneously without experiencing IDC interference. Embodiments of the present invention provide a method of wireless frame transmission that prevents constrained MLDs from transmitting and receiving frames on multiple links simultaneously using an advantageous and novel, reliable group addressed frame transmission schedule for constrained MLDs. Group addressed frames are frames that are transmitted to several devices (e.g., broadcast) listening on a wireless link. It is important to transmit group addressed frames for reception by MLDs in a manner that avoids scheduling group addressed frames when the reception of said frames would overlap with a transmission by the receiving constrained MLD.

According to one embodiment, an AP MLD schedules the transmission of group addressed frames during times when all constrained MLDs are not transmitting. However, because the non-AP MLDs (STAs) do not know when the group addressed frames will be transmitted by the AP MLD, the STAs of the non-AP MLDs may attempt to access the wireless channel without any restriction. Therefore, scheduling the transmission of group addressed frames only when all constrained MLDs are not transmitting can be difficult unless the traffic load of the wireless network is relatively low.

FIG.1depicts an exemplary transmission of an MLD using multiple links. The MLD is a non-AP MLD including STA1 and STA2 communicating over respective wireless links. In the example ofFIG.1, STA1 receives an individually addressed frame105. In response, STA1 transmits a block ack (BA)110acknowledging the reception of frame105. While STA1 is transmitting BA110, STA2 simultaneously receives a delivery traffic indication map (DTIM) beacon frame115. Group-addressed frame120is received by STA1 after the DTIM beacon frame115while the transmission of BA110is ongoing. STA1 and ST2 of the non-AP MLD are in communication with the AP MLD over a non-simultaneous transmit and receive (NSTR) link pair. For example, the NSTR link pair can include a 5 GHz wireless link and a 6 GHz wireless link or a 2.4 GHz wireless link and a 5 GHz wireless link, where simultaneous transmission and reception over the links can cause IDC interference.

For example, the simultaneous transmission and reception over STA2 and STA1, respectively, causes IDC interference which can negatively impact the reliability and performance of the wireless transmissions. It is appreciated that, according to embodiments of the present invention, in order to reliably deliver a group addressed frame to a constrained non-AP MLD, the AP MLD does not schedule a frame exchange sequence to a constrained non-AP MLD that overlaps with a group addressed frame transmitted on another link or links.

FIG.2depicts an exemplary transmission between MLD devices according to embodiments of the present invention. The frames are scheduled for transmission according to a process that prevents a constrained non-AP MLD from transmitting frames that would cause IDC interference without knowledge of the link(s) on which the constrained non-AP MLD is listening for group addressed frames. As depicted inFIG.2, AP MLD includes AP1, AP2, and AP3. At times205,210,215,220,225, and230, the AP MLD advantageously does not schedule any frame exchange sequences to the non-AP MLD to prevent simultaneous transmission and reception during by the non-AP MLD during these times.

According to some embodiments, the non-AP MLD indicates to the AP MLD which link(s) are being used to listen for group addressed frame. Thereafter, the AP MLD does not schedule any frame exchange sequences to non-AP MLDs that overlap with the group addressed frame on the link or links indicated by the non-AP MLD (“configured link(s)”). Note inFIG.2that the AP MLD can transmit downlink data (D) (e.g., an individually addressed frame) at times that are not reserved for group address frame transmission as long as the transmission does not solicit an immediate response that would overlap with the group address frame transmission.

In the exemplary wireless transmission300ofFIG.3, according to embodiments of the present invention, the AP MLD does not schedule any frame exchange sequences to the non-AP MLD that overlap with the group addressed frame on the configured link(s). When the non-AP MLD intends to receive the group addressed frame on the configured link(s), other STAs of the constrained non-AP MLD do not access any channels during the group addressed frame transmission time. The non-AP MLD indicates to the AP MLD the link(s) on which it is listening for the group addressed frame (“link configuration”). Thereafter, the AP MLD does not schedule any frame exchange sequences on another link or links to the non-AP MLD which overlap with the group addressed frame on the configured link(s). InFIG.3, the DTIM beacon frame305and Group addressed MDPU310are transmitted to a non-AP MLD over a configured link(s) (indicated by the non-AP MLD), and therefore non-APs MLD1 and MLD2 do not access any channels (or any channel not supporting simultaneous Rx and Tx) on another link or links during the group addressed frame transmission.

FIG.4depicts an exemplary wireless transmission400that prevents IDC interference by constrained MLDs according to embodiments of the present invention. In general, the AP MLD does not wirelessly transmit a frame that solicits an immediate response to a STA of a non-AP MLD on a link that belongs to a non-simultaneous transmit and receive (NSTR) link pair(s) for that non-AP MLD when the immediate response is expected to overlap in time with group addressed MPDUs scheduled on another link or links of the NSTR link pairs, and the non-AP MLD is expected to be receiving the group addressed MPDUs.

In the example ofFIG.4, the AP MLD receives A-MPDU (e.g., an individually addressed frame) from non-AP MLD1 over Link 2 followed by A-MPDU from non-AP MLD2 over Link 2. Responsive to the A-MPDUs received over Link 2, the AP MLD transmits BAs415and420. The AP MLD transmits individually addressed A-MPDUs425and430over Link 1 the non-AP MLDs. The AP MLD schedules group addressed frames only when all constrained MLDs are not transmitting. Accordingly, the AP MLD does not transmit group addressed frames during time periods425and410while non-AP MLD1 is transmitting A-MPDU410and while receiving BA415to prevent IDC interference.

According to some embodiments of the present invention, an AP MLD provides scheduling information for transmitting group addressed frames to constrained non-AP MLDs. The constrained non-AP MLDs that intend to receive group addressed frames do not access the channel (on all links not supporting simultaneous Rx and Tx) during the time scheduled for transmitting group addressed frames as indicated by the scheduling information. Scheduling information for transmitting group addressed frames can be broadcasted to the constrained non-AP MLDs using a target wake time (TWT) element, for example. The TWT element can be included in a beacon frame sent by an AP MLD.

According to some embodiments, a TWT scheduling AP advertises a broadcast TWT with a Broadcast TWT ID field set to 0. The TWT scheduling AP can schedule delivery of group addressed downlink (DL) buffer units (BUs) during the broadcast TWT service periods (SPs) within the beacon interval that follows the DTIM Beacon frame when the TWT parameter set indicates non-trigger enabled unannounced TWT SP and has a Broadcast TWT Recommendation subfield equal to 0. In this case, constrained non-AP MLDs do not access the channel (on all links not supporting simultaneous Rx and Tx) during the broadcast TWT SPs if it intends to receive the group addressed frames.

FIG.5depicts an exemplary wireless transmission500(using MLDs) that prevents IDC interference using a TWT element to broadcast scheduling information for group addressed frames according to embodiments of the present invention. In the example ofFIG.5, the AP MLD does not transmit a group addressed frame on Link 1 when another MLD is transmitting A-MPDU505to the AP MLD (time period520). The AP MLD can transmit individually addressed A-MPDU510to a non-AP MLD. Subsequently, during a broadcast TWT SP indicated by a broadcast TWT with a Broadcast TWT ID field set to 0, the AP MLD transmits group addressed MPDU515. During this time, non-AP MLD1 and non-AP MLD2 cannot access the channel, and IDC interference caused by simultaneous transmission and reception by constrained MLDs is prevented or substantially reduced.

When the transmission of multicast data is overloaded, a constrained non-AP MLD may not join to the corresponding multicast group and is prevented from accessing the channel on links not supporting the simultaneous Rx and Tx during the scheduled time of the group addressed frame, which can degrade the performance of multi-link operations (MLO). According to some embodiments, for each link (e.g., Link 1 and Link 2 depicted above), the AP MLD assigns one Association ID (AID) indicating whether the broadcast data (excluding the multicast data) is buffered on the corresponding link. If the bit position of that AID is set to 1 (e.g., in a virtual bitmap in the Traffic indication map (TIM) information element), the non-AP MLD does not access the channel (on all links not supporting the simultaneous Rx and Tx) during the scheduled time of the group addressed frame. According to other embodiments, a non-AP MLD that does not join the multicast group does not have any restriction on channel access.

According to some embodiments, for each multicast group, the AP MLD can provide buffer status using a Fixed Mobile Substitution (FMS) Descriptor information element. In this case, if the non-AP MLD does not join to the multicast group on which the AP MLD has buffered the frame, the non-AP MLD has no restriction on channel access.

FIG.6depicts an exemplary sequence of computer-implemented steps of a process600for wirelessly transmitting a group addressed frame to a constrained MLD to substantially prevent IDC interference according to embodiments of the present invention.

At step605, an AP MLD determines that a first non-AP MLD is transmitting on a first wireless link of a NSTR link pair.

At step610, responsive to the determination of step605, an individually addressed frame is transmitted by the AP MLD to a second non-AP MLD over a second wireless link of the NSTR link pair.

At step615, a group addressed frame is wirelessly transmitted over the second wireless link after the first non-AP MLD is done transmitting on the first wireless link. The first non-AP MLD and second non-AP MLD are advantageously prevented from transmitting on the NSTR link pair during transmission of the group addressed frame, for example, as indicated by a broadcast TWT with a Broadcast TWT ID field set to 0.

FIG.7depicts an exemplary sequence of computer-implemented steps of a process700for wirelessly transmitting a group addressed frame to a constrained MLD to substantially prevent IDC interference based on link configuration information according to embodiments of the present invention.

At step705, an indication is accessed or received from a non-AP MLD that indicates that the non-AP MLD is listening for group addressed frames on a wireless link.

At step710, responsive to the determination at step705, a group addressed frame for transmission over the wireless network is scheduled at the AP MLD based on the indication to prevent a frame exchange sequence from being scheduled that overlaps with the group addressed frame being transmitted on the NSTR link.

At step715, the group addressed frame is wirelessly transmitted over the wireless link as scheduled by the AP MLD.

FIG.8depicts an exemplary sequence of computer-implemented steps of a process800for wirelessly transmitting a group addressed frame to a constrained MLD to substantially prevent IDC interference based on link configuration information according to embodiments of the present invention.

At step805, scheduling information is transmitted to a non-AP MLD indicating a schedule for transmitting a group addressed frame over a wireless link. The scheduling information can be broadcast in a TWT information element, for example.

At step810, responsive to the schedule of step805, a group addressed frame is scheduled for wireless transmission over the wireless network at the AP MLD in accordance with the scheduling information. The non-AP MLD refrains from transmitting on the NSTR link pair when the group addressed frame is scheduled to be transmitted on the NSTR link pair.

FIG.9depicts an exemplary wireless device900upon which embodiments of the present invention can be implemented. The wireless device900can be a mobile electronic device, a wireless AP, a wireless STA, or any suitable computer system, for example. The wireless device900includes a processor905for running software applications and optionally an operating system. Memory910can include read-only memory and/or random access memory, for example, to store applications and data for use by the processor905, as well as frames915(e.g., data frames) that are received or transmitted by transceivers920,925, and930. The wireless device900can include fewer or more transceivers according to some embodiments. The transceivers920,925,930communicate with other electronic devices over a wireless network (e.g., WLAN) and typically operates according to IEEE standards (e.g., IEEE 802.11ax, IEEE 802.11ay, IEEE 802.11be, etc.).

According to embodiment of the present invention, the processor can execute memory-resident instructions to schedule group addressed frames for avoiding IDC interference by preventing transmission of frames by non-AP MLDs when a group addressed frame is scheduled for wireless transmission. In accordance with embodiments of the present invention, the processor can generate and transmit scheduling information used by the non-AP MLDs for scheduling frame transmissions that do not overlap with planned group addressed frame transmissions. The processor can also receive or access link configuration information from non-AP MLDs for scheduling group addressed frame transmissions that do not overlap with data transmissions on the same NSTR link pair.

Embodiments of the present invention are thus described. While the present invention has been described in particular embodiments, it should be appreciated that the present invention should not be construed as limited by such embodiments, but rather construed according to the following claims.