Wireless signal transmission method and apparatus for notifying depletion of duty cycle transmission

Abstract

To provide a signaling method and device of wireless communication that meet duty cycle constraints.SOLUTION: In a wireless communication system, a signaling method includes: determining whether a transmission budget derived based on a duty cycle constraint and an accumulated transmission time within an observation window is about to be depleted; in response to determining that the transmission budget is about to be depleted, transmitting a first data frame carrying a power management bit to a peer device to mark the transmission budget as depleted; and updating the transmission budget over time, transmitting a second data frame carrying the power management bit to the peer device, and resuming communication with the peer device in accordance with the updated transmission budget.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to Australian Provisional Patent Application No. 2023901522, filed on May 17, 2023, the contents of which are incorporated herein by cross reference.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to wireless communication devices that comply with duty cycle constraints. [Background technology]

[0003] A wireless communication system, e.g., a wireless local area network (WLAN), typically includes multiple wireless communication devices, including at least an access point (AP) that communicates with one or more stations (STAs). The AP of the wireless communication system may be coupled to another network, such as the Internet, and may allow the STA to communicate bidirectionally or may allow the STA to communicate with other devices in the network through the AP. The available frequency band may be shared with a huge number of wireless communication devices in the WLAN, and in certain regulatory domains, there are some frequency band regulatory constraints on the airtime used by transmitting devices using the medium of both APs and STAs in a basic service set (BSS), which are called duty cycle constraints. Wireless communication devices operating in regulatory domains such as Europe and Japan must limit their transmission airtime so that in any observation window, the transmission ratio is equal to or less than a predetermined duty cycle. An observation window with a length equal to the observation period is used to measure the accumulated transmission time, but since the start of the observation window is not defined, the proportion of airtime used by each AP or STA to transmit packets must be less than the duty cycle constraint in an observation window starting from any time. The observation period is relatively long compared to the packet transmission time, for example, the observation period in some regulatory domains is set to one hour. How operators in such restricted channels achieve this duty cycle requirement varies from vendor to vendor.

[0004] A wireless communication device that meets the duty cycle constraint is configured to wait a certain amount of time after each successful transmission. For example, with a 10% duty cycle constraint, a wireless communication device that has recently used a wireless channel for 1 millisecond (ms) must wait another 9 ms before this wireless channel becomes available again. The purpose of introducing the duty cycle constraint is to ensure fair access to the wireless medium for all connected devices competing for the frequency band. Duty cycle constraints must be considered in the design of real-time Internet of Things (IoT) systems, where a large number of connected devices need to transmit data wirelessly over long distances in real time. Summary of the Invention

[0005] The following summary presents technical features relevant to one or more aspects disclosed herein and is not intended to be an extensive overview relevant to all aspects contemplated, nor is the following summary intended to identify key elements or critical elements relevant to all aspects contemplated or to delineate the scope relevant to any aspect. As such, the following summary is intended only to present certain concepts relevant to one or more embodiments related to the signaling methods disclosed herein in a simplified form prior to the detailed description presented below. [Means for solving the problem]

[0006] A signaling method is disclosed for notifying one or more peer devices wirelessly connected to a wireless communication network of depletion of a transmission budget. An embodiment of the signaling method includes determining whether a transmission budget is about to be depleted, transmitting a first data frame carrying a power management bit to the peer device, and marking the transmission budget as depleted if the transmission budget is about to be depleted, and transmitting a second data frame carrying a power management bit to the peer device to update the transmission budget over time and resume communication with the peer device according to the updated transmission budget. The transmission budget is derived based on a duty cycle constraint and an accumulated transmission time within an observation window. One embodiment of a peer device is an access point (AP) of a wireless local area network (WLAN).

[0007] In some embodiments, the first data frame carrying a power management bit is used to notify a peer device to enter a power management mode and the second data frame carrying a power management bit is used to notify a peer device to exit a power management mode. For example, the first data frame carrying a power management bit is a quality of service null (QOS) [asleep] frame and the second data frame carrying a power management bit is a quality of service null [awake] frame. In some embodiments, the signaling method further includes: entering a power management mode if the transmission budget is marked as exhausted.

[0008] In some embodiments, the transmission budget is about to be depleted when the transmission budget falls below a threshold, the threshold being set according to an airtime for transmitting one or more frames, for example, the threshold being set to be longer than an airtime for transmitting a first data frame carrying a power management bit.

[0009] According to an embodiment of the present invention, the signaling method further includes determining whether there is buffered data traffic in the peer device, and transmitting a second data frame carrying a power management bit only if there is buffered data traffic in the peer device. The signaling method further includes receiving one or more beacon frames from the peer device, and determining whether there is buffered data traffic in the peer device according to the one or more beacon frames.

[0010] In one embodiment, the unique signaling method further includes: calculating a time when the transmission budget is updated to resume communication with the peer device; inserting information corresponding to the time in a third frame; and transmitting the third frame to the peer device. In this embodiment, the third frame may be a vendor-specific action frame or a type of management frame. The time is calculated from the perspective of a time synchronization function (TSF). The transmission budget is reserved for the transmission of the first data frame and the third frame by setting a threshold value that is longer than the communication time for transmitting both the first data frame and the third frame, and the transmission budget is about to be depleted when the transmission budget falls below the threshold value.

[0011] One embodiment of the signaling method further includes receiving a beacon frame from the peer device, parsing a vendor peer exhaustion information element (IE) in the beacon frame, determining a resume time from the vendor peer exhaustion IE, and entering a power management mode until the resume time.

[0012] Another embodiment of the signaling method includes determining whether a transmission budget is about to be exhausted, and if the transmission budget is about to be exhausted, inserting a restricted access window parameter set (RPS) information element (IE) into a beacon frame to reserve a time slice between a current target beacon transmission time (TBTT) and a next TBTT, and transmitting a beacon frame on a wireless channel to inform one or more peer devices that transmission on the wireless channel between the current TBTT and the next TBTT is prohibited. The transmission budget is derived based on a duty cycle constraint and a cumulative transmission time within an observation window. An embodiment of a peer device is a STA associated with an AP.

[0013] In some embodiments, the signaling method includes dropping non-beacon frames in response to the transmission budget being exhausted. In some embodiments, the RPS IE in the beacon frame includes an unused Association ID (AID) that is not assigned to any peer device in a wireless communication network, and the peer device receiving the beacon frame is prohibited from accessing a wireless channel between a current TBTT and a next TBTT.

[0014] In some embodiments, it is determined whether the transmission budget is about to run out by comparing the transmission budget to a threshold, the threshold being set to be longer than the airtime required for the transmission of one or more beacon frames. Optionally, if the transmission budget is still below the threshold at the next TBTT, an RPS IE is inserted into the next beacon frame to reserve another time slice. The next beacon frame is transmitted on a wireless channel to inform peer devices according to the RPS IE that transmission on the wireless channel is still prohibited. One embodiment of the proprietary signaling includes calculating a time point when the transmission budget exceeds the threshold and inserting information corresponding to the time point into a vendor IE added to the beacon frame.

[0015] In one embodiment, a vendor action frame is received from a first peer device notifying depletion of a peer transmission budget, and in response to the vendor action frame, data traffic of the first peer device is buffered and communication with the first peer device is suspended, and a time point is derived from the vendor action frame after which the buffered data traffic is transmitted to the first peer device.

[0016] In another aspect of the present invention, a wireless communication device wirelessly connected to a wireless communication network is disclosed, the wireless communication device including a receiver, a transmitter, a processor, and one or more memory banks, the processor being communicatively coupled to the receiver and the transmitter, the memory bank being communicatively coupled to the processor and storing processor readable code that, when executed by the processor in cooperation with the receiver and the transmitter, is configured to perform the steps of: determining whether a transmission budget is about to be depleted, the transmission budget being derived based on a duty cycle constraint and an accumulated transmission time within an observation window; and in response to determining that the transmission budget is about to be depleted, transmitting a first data frame carrying a power management bit to a peer device and marking the transmission budget as being depleted; updating the transmission budget over time, transmitting a second data frame carrying a power management bit to the peer device, and resuming communication with the peer device in accordance with the updated transmission budget.

[0017] Other objects and advantages associated with the embodiments disclosed herein will become apparent to one of ordinary skill in the art based on the accompanying drawings and detailed description. [Brief description of the drawings]

[0018] Exemplary aspects of the present application are described in detail below with reference to the following drawings: [Figure 1]11 is a flowchart illustrating an operation of a STA waking up from a power management mode and adaptively receiving buffered traffic from an AP based on its transmission budget. [Figure 2A] 1 illustrates an example of signaling behavior when a STA has exhausted its duty cycle transmission budget. [Figure 2B] 1 illustrates an example of signaling behavior when an AP has exhausted its duty cycle transmission budget. [Figure 3A] 1 illustrates an exemplary standard signaling method for a STA to notify an AP that its transmission budget is about to run out, according to one embodiment of the present invention. [Figure 3B] 1 illustrates an exemplary proprietary signaling method for a STA to notify an AP that its transmission budget is about to run out, according to one embodiment of the present invention. [Figure 3C] 4 illustrates an exemplary signaling method for a STA to notify an AP that its transmission budget is about to run out, according to another embodiment of the present invention. [Figure 3D] 4 illustrates an exemplary standard signaling method for an AP to notify one or more STAs that its transmission budget is about to run out, according to another embodiment of the present invention. [Figure 3E] 1 illustrates an exemplary unique signaling method for an AP to notify one or more STAs that its transmission budget is about to run out, according to one embodiment of the present invention. [Figure 3F] 4 illustrates an exemplary signaling method for an AP to notify one or more STAs that its transmission budget is about to run out, according to another embodiment of the present invention. [Figure 4] 1 is a flow chart illustrating a STA notifying an associated AP about a depletion of a transmission budget according to one embodiment of the present invention. [Diagram 5] 1 is a flow chart illustrating an AP notifying associated APs about a transmission budget depletion according to one embodiment of the present invention. [Figure 6]1 is a flow chart illustrating a STA receiving signaling from an associated AP indicating that its transmission budget has been depleted, according to one embodiment of the present invention. [Figure 7] 4 is a flow chart illustrating an AP receiving signaling from a STA indicating that its transmission budget has been depleted, according to one embodiment of the present invention. [Figure 8A] FIG. 1 is a schematic block diagram for implementing an embodiment of the present invention. [Figure 8B] 2 is a schematic block diagram of a receiver data flow architecture in a wireless communication device for implementing an embodiment of the present invention; [Figure 8C] 1 is a schematic block diagram of a transmitter data flow architecture in a wireless communication device for implementing an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Specific aspects and examples of the present disclosure are given below. Some of these examples can be applied independently, and some of them can be applied in combination, as will be apparent to one skilled in the art. In the following description, for the purpose of explanation, specific details are set forth to allow a thorough understanding of the aspects of the present application. However, it will be apparent that various embodiments can be practiced without these specific details. The figures and descriptions are not intended to be limiting. The following description of the examples is intended to provide a person skilled in the art with possible explanations for implementing the exemplary aspects. Changes can be made in the function and arrangement of elements without departing from the spirit and scope of the invention, as defined in the claims.

[0020] A wireless communication device is configured to operate in a duty cycle mode to comply with the duty cycle constraints of a regulatory domain. The wireless communication device may operate in one duty cycle mode at all times, or may be configured to operate in any of multiple duty cycle modes. A duty cycle burst mode has been developed along with a conventional duty cycle spread mode, and instead of delaying each successive packet transmission in a duty cycle spread mode, a wireless communication device operating in a duty cycle burst mode can transmit a burst of packets in a single hit. This is very important when using a video doorbell or a battery-powered camera. For example, a device with a 10% duty cycle limit can send up to 6 minutes of burst traffic in a 1-hour window before transmission is blocked. If the 1-hour window slides forward sufficiently, for example after the wireless communication device is stationary for 54 minutes after a 6-minute burst transmission, the wireless communication device can transmit again. For a wireless communication device operating in a duty cycle burst mode, a transmission budget is recorded and periodically updated according to the elapsed time and the airtime used for transmission to reflect the remaining transmission airtime within the observation window. Also, if the transmission budget is exceeded under the duty cycle constraint, the transmission is blocked. Figure 1 shows an exemplary operation of a STA waking up from a power management mode (e.g., power saving mode or sleep mode) and adaptively receiving buffered traffic from an AP based on its transmission budget. In step S102 of Figure 1, the STA wakes up from a power management mode and receives a delivery traffic indication message (DTIM) beacon frame from an AP. In step S104, the STA first determines whether there is data traffic buffered in the AP according to the received DTIM beacon frame, and if there is data traffic buffered in the STA, checks the transmission budget in step S106.If the received DTIM beacon frame indicates that there is no buffered data traffic in the AP, the STA goes back to sleep in step S116. If the transmission budget is exhausted, the STA further determines whether the observation window has advanced so that there is available transmission time in step S108. If the STA determines that the observation window has advanced to allow transmission, the observation window and the transmission budget are adjusted accordingly in step S110, otherwise the STA goes back to sleep in step S116 and accumulates more transmission budget. In step S112, since the transmission budget has been adjusted to allow transmission, the STA notifies the AP that the AP is awake and ready to receive data traffic. In step S114, the STA receives the buffered data traffic from the AP and goes back to sleep in step S116 after transmitting the traffic.

[0021] According to an embodiment of the present invention, the transmission budget of a wireless communication device in a duty cycle spread mode or a burst mode can be tracked. The transmission budget is depleted when a cumulative counter that tracks the total communication time used within an observation window reaches the maximum transmission time allowed within the observation window. For example, the maximum transmission time is calculated by multiplying the total period size by the duty cycle ratio, the total period size being the period during which the duty cycle requirement applies, e.g., one hour. Before transmitting a frame, the wireless communication device checks whether there is sufficient transmission budget, and the transmission budget is updated to take into account the communication time spent transmitting the frame. The transmission budget is also updated when the observation window advances in time.

[0022] During the period when the STA's transmission budget is exhausted, the STA cannot send frames to the AP, and more importantly, the STA cannot respond with an acknowledgement (ACK) frame when it receives a data frame from the AP. The ACK frame is a control frame that creates a delivery confirmation that is expected after the transmission of the data frame to confirm the reception of the data frame. When the STA stops responding to the data frame received from the AP, the AP will retransmit the same data frame several times, which will increase the communication time. If the AP does not know whether the STA is not responding because the STA has left the BSS or because the duty cycle transmission budget has been exhausted, it may decide to initiate a disconnection. After a while, when the STA acquires more transmission budget, the AP may have already sent a disconnection frame. The STA needs to re-associate with the BSS by exchanging additional frames with the AP. An example of a signaling operation when a STA has exhausted its duty cycle transmission budget is shown below. Before the STA runs out of transmission budget, the STA transmits frame A to the AP and receives an ACK frame from the AP, after which the STA receives frame B from the AP and responds with an ACK frame. By the time the STA receives frame C from the AP, it cannot respond with an ACK frame because its transmission budget has been exhausted. Similarly, the AP sends frames D, E, and F to the STA, but does not receive an ACK frame from the STA. The AP may then transmit frame G to disconnect the STA, assuming that the STA has already left the BSS.

[0023] Similarly, if an AP has exhausted its duty cycle transmission budget, it cannot respond with an ACK frame after receiving a frame from an associated STA. If the STA does not receive an ACK frame from the AP, it will try to retransmit the frame to the AP, but each time it fails to transmit the frame, the STA's rate control algorithm will lower the modulation coding scheme (MCS) rate. This will increase the transmission time of each frame, causing the STA to exhaust its transmission budget sooner. The STA will waste additional power retransmitting the frame to the AP. Figure 2B shows an example of signaling behavior when an AP has exhausted its duty cycle transmission budget. In a typical design, the AP reserves transmission airtime for beacon frames when managing the transmission budget, so that beacon frames are always transmitted. The AP in Figure 2B cannot respond to frame A coded with MCS=7 transmitted from an associated STA because the AP can transmit beacon A due to the exhaustion of the transmission budget for non-beacon frames. The STA then drops the MCS rate to 4 and retransmits the same content in frame B. Because the AP does not yet have the transmission budget to respond to frame B, the STA drops its MCS rate to 2 and attempts to retransmit in frame C. In this example, the STA has not received an ACK frame from the AP after transmitting frames A, B, and C, and its transmission budget may be exhausted.

[0024] To better manage the power and airtime spent on retransmissions due to unannounced exhaustion of the duty cycle transmission budget by either the AP or the STA, several new signaling methods have been proposed to inform peers in a WLAN BSS that the duty cycle transmission budget is about to be exhausted. These signaling methods apply to APs and STAs operating in a duty cycle mode where the transmission time is governed by a duty cycle constraint. Some embodiments of the signaling methods use standard signaling, but proprietary signaling can also be used to achieve the desired operation.

[0025] STA Standard Signaling An embodiment of a STA operating in a duty cycle mode can control downlink transmissions from an AP using a power management bit communicated in a data frame. In this embodiment, airtime for this particular data frame carrying a power management bit is reserved within an observation window in which a duty cycle restriction applies, i.e., the STA can transmit a data frame carrying a power management bit even if its transmission budget is about to be depleted. In the following embodiments, the transmission budget is about to be depleted may refer to the transmission budget of a duty cycle falling below a predetermined or adaptive threshold, ratio, or percentage. For example, the predetermined or adaptive threshold corresponds to the airtime for transmitting one or more data, management, or control frames utilizing a lowest modulation coding scheme (MCS). The STA's threshold may be different from the AP's threshold, and the threshold may be different for various applications and use cases. In some embodiments of a signaling method for a STA to inform an associated AP that its duty cycle transmission budget is about to be depleted, the STA informs the AP through a power management bit communicated in a data frame. When a STA is about to exhaust its transmission budget, e.g., when the transmission budget reaches a threshold where normal frames cannot be transmitted, the STA immediately transmits a data frame with a subtype field equal to QoS Null to block the AP from transmitting downlink frames. The QoS Null data frame is used to transmit control information without transmitting normal data. For example, the STA utilizes the QoS Null data frame to indicate to the AP that it is entering a power saving mode or waking up. FIG. 3A illustrates an exemplary standard signaling method for a STA to inform an AP that its transmission budget is about to exhaust, according to one embodiment of the present invention. The STA transmits frame A to the AP and receives an ACK frame from the AP. The STA then receives frame B from the AP and responds with an ACK frame.At this point, the STA will try to exhaust the transmission budget for its duty cycle, so it will send a quality of service null [asleep] frame to the AP to inform it that the STA will not respond for a while. The AP receives this quality of service null [asleep] frame and responds with an ACK frame. The AP then treats the STA as having entered a power management mode, so instead of sending data traffic to the STA immediately, it buffers the STA's data traffic. As a result, after receiving this quality of service null [asleep] frame, the AP will not try to send more frames to the exhausted STA and will not waste its transmission budget. In this example, the STA will gain more transmission budget and can transmit again at time TSF=45, and the STA will send another QoS Null data frame, QoS Null [awake], to the AP after TSF=45 and resume communication with the AP. The time synchronization function (TSF) is maintained and shared by all APs and STAs in the same BSS. The AP that receives this quality of service null [awake] frame will know that the STA is ready to receive frames. The AP then responds with an ACK frame for receiving the quality of service null [awake] frame. In this example, the AP transmits frame C to the STA after receiving the quality of service null [awake] frame from the STA. The STA responds with an ACK frame after receiving frame C. In some embodiments, the STA may enter a power management mode after receiving an ACK frame for the quality of service null [asleep] frame and wake up when it has more transmission budget. After the STA wakes up from the power management mode, the STA may transmit a quality of service null [awake] frame to the AP. In one embodiment, the STA transmits a quality of service null [awake] frame only if it receives one or more beacons indicating that there is buffered traffic for the STA. In this embodiment, the STA does not need to inform the AP about the restoration of the transmission budget if the AP indicates that there is no traffic for the STA.

[0026] STA-specific signaling In some embodiments of the present invention, a proprietary signaling method is used by the STA to inform the AP that the STA's transmission budget is about to run out. The proprietary signaling method of some embodiments allows the STA to further inform the AP about when the STA will be able to transmit again. For example, when the STA is about to run out of transmission budget for its duty cycle, a management frame, more specifically a vendor-specific action frame, is dispatched to the AP. The STA can transmit this vendor-specific action frame even when the transmission budget is about to run out because airtime is reserved for transmitting this vendor-specific action frame. The vendor-specific action frame may carry information related to when the STA will have a transmission budget again. The AP may decode this vendor-specific action frame to know that the STA's transmission budget has run out and know when the STA can transmit again based on the shared BSS TSF. The AP can use this knowledge to decide whether to disconnect a STA that has been inactive on the BSS for some time. FIG. 3B illustrates an exemplary proprietary signaling method for a STA to inform an AP that the transmission budget is about to run out, according to one embodiment of the present invention. In this example, the STA transmits frame A to the AP and receives an ACK frame from the AP, after which the STA receives frame B from the AP and transmits an ACK frame to the AP. When the STA is about to exhaust its transmission budget due to duty cycle limitations, it transmits a vendor action frame specifying that the transmission budget is exhausted until TSF=45. The AP receives this vendor action frame from the STA and responds with an ACK frame. Because the vendor action frame informs the AP that the STA cannot transmit until TSF=45, the AP can use this information to prevent the disconnection logic before TSF=45. In this example, the AP stops communication with the STA until TSF=45 according to the vendor action frame, and resumes transmitting frames to the STA after TSF=45.This unique signaling method prevents the AP from disconnecting from a depleted STA due to lack of knowledge of the peer's duty cycle transmission budget. In one embodiment, a STA can be configured to be more power efficient by entering power management mode when its transmission budget is depleted. For example, the STA calculates the time when it can enter power management mode, notifies the AP in a vendor action frame, enters power management mode after receiving an ACK frame for the vendor action frame, and wakes up according to the calculated time.

[0027] STA Standard and Proprietary Signaling In some embodiments of a signaling method for notifying an AP, a STA sends both a data frame carrying a power management bit and a vendor specific action frame to the AP when the transmission budget is about to be depleted. In these embodiments, airtime is reserved in the transmission budget for transmitting both the data frame carrying the power management bit and the vendor action frame, so that these two frames can be transmitted to the AP when the STA's transmission budget is about to be depleted. FIG. 3C illustrates an exemplary signaling method for a STA to notify an AP that its transmission budget is about to be depleted, according to another embodiment of the present invention. The STA periodically transmits and receives frames before its transmission budget is about to be depleted, and immediately after determining that the transmission budget is about to be depleted, the STA transmits a quality of service null [asleep] frame to the AP to block the AP from transmitting frames. The STA further transmits a vendor action frame to the AP indicating that the transmission budget is depleted until TSF=45. The AP buffers data traffic for the STA after TSF=45 or until it receives a quality of service null [awake] frame from the STA. In one embodiment, the STA transmits this quality of service null [awake] frame only if it receives a beacon frame from the AP indicating that data traffic is buffered for the STA.

[0028] AP Standard Signaling In various embodiments of a signaling method for notifying associated STAs that an AP is about to exhaust its duty cycle transmission budget, airtime for beacon transmission is reserved within an observation window where the duty cycle restriction applies, so that from the user's perspective, the AP can still transmit beacon frames after the transmission budget is exhausted. According to some embodiments of the present invention, by combining a Restricted Access Window (RAW) Parameter Set (RPS) Information Element (IE) with the beacon transmission, the AP reserves the entire time slice between two beacon frames, preventing other stations on the network from transmitting to the AP. This signaling method is not proprietary and should interoperate with all vendors. Figure 3D illustrates an exemplary standard signaling method for an AP to notify one or more STAs that its transmission budget is about to exhaust, according to another embodiment of the present invention. In this embodiment, the AP's transmission budget is about to exhaust means that the AP has exhausted its transmission budget for non-beacon frames. Used as the shared BSS Time Synchronization Function (TSF) time scale. The AP sends out Beacon A with TSF equal to TSF=15 to reserve the medium between TSF=15 and TSF=30 using the RPS IE in Beacon A. The RAW capability indicated in Beacon A blocks uplink transmissions from all STAs between TSF=15 and TSF=30. The STAs receiving Beacon A do not transmit any frames during the period from TSF=15 to TSF=30 according to the RPS IE to respect the RAW capability. In this example, since the AP has a transmission budget after TSF becomes 35, it sends Beacon B before TSF becomes 30 to reserve the medium between TSF=30 and TSF=35 using the RPS IE in Beacon B. This RAW capability again prevents all associated stations from transmitting frames during this period.The STA can send uplink data to the AP after TSF=35 because it has the transmission budget to respond to the AP's successfully received frames. For example, the STA sends frame A with MCS of 7, receives an ACK frame from the AP, and then sends frames B and C and receives an ACK frame, respectively. By implementing the standard signaling method, the STA does not attempt to send frames to the AP with a depleted transmission budget, so there is no data loss due to the depleted AP not responding to the successfully received frames. Furthermore, the STA's rate control algorithm does not collapse. Without this signaling method, a STA transmitting to an AP with a depleted transmission budget may interpret the lack of an ACK response as a bad link and continuously reduce its transmission rate, and if the STA attempts to retransmit, it may exhaust the transmission budget of its duty cycle.

[0029] AP-specific signaling In one embodiment of the present invention, it is unique in the form of a vendor IE in the beacon frame. This vendor IE in the beacon frame informs the STAs that the AP cannot transmit non-beacon frames and when the AP will have a transmit budget again, using the shared BSS TSF as a time scale. Devices that decode this vendor IE can decide to enter power management mode until the specified timestamp and become more power efficient. For example, the AP in FIG. 3E signals a vendor IE in Beacon A to inform associated STAs that all STAs cannot retransmit until TSF=35, and the STAs receive and analyze this vendor IE in Beacon A, enter power management mode, and wake up at TSF=35. The STAs know that the AP cannot respond before TSF=35. The unique signaling method allows the STAs to enter power management mode as soon as they know that the AP does not have a transmit budget to send traffic to the STAs. The STAs are informed that the AP has more transmit budget, so they can be more power efficient and sleep until then.

[0030] AP standard and proprietary signaling In another signaling method for an AP to inform a STA that the transmission budget of non-beacon frames is exhausted, the beacon frame includes an RPS IE and a vendor IE. FIG. 3F illustrates an exemplary signaling method for an AP to inform one or more STAs that the transmission budget is about to be exhausted according to another embodiment of the present invention. In this example, the AP exhausts the transmission budget of non-beacon frames from TSF=10 to TSF=35. The AP sends out a beacon A including an RPS IE reserving the medium between TSF=15 and TSF=30, and then sends out a beacon B with an RPS IE reserving the medium between TSF=30 and TSF=35. The STA does not transmit during these RAW periods defined in beacon A and beacon B. Beacon A and beacon B may include a vendor IE indicating that the AP can respond after TSF=35. The STAs capable of decoding the vendor IE can enter a power management mode after receiving and analyzing beacon A. In one embodiment, those STAs that enter power management mode may skip receiving Beacon B and exit power management mode at TSF=35. STAs that cannot decode the vendor IE may also get the stop transmission message between TSF=15 and TSF=30 and between TSF=30 and TSF=35 after receiving and analyzing Beacon A and Beacon B.

[0031] FIG. 4A is a flow chart showing a STA notifying an associated AP about the depletion of the transmission budget according to an embodiment of the present invention. In this embodiment, the STA transmits both a quality of service null frame and a vendor action frame to the AP when the transmission budget is about to be depleted, but in other embodiments, the STA may transmit only one of the quality of service null frame or the vendor action frame to notify its peer device that the transmission budget is about to be depleted. In step S402, the transmission budget of the STA is checked, and if the transmission budget is currently marked as being depleted, the STA proceeds to step S404. In step S404, the STA determines whether enough time has passed such that the STA has a transmission budget again according to the duty cycle constraint, and if the STA has acquired more transmission budget, in step S406, the STA unpauses the traffic queue. The transmission budget may be calculated according to the accumulated communication time used by the STA for transmission within the observation window. For example, if the STA adheres to a 10% duty cycle constraint in any 60-minute observation window, the transmission budget is 6 minutes if the STA has not transmitted a frame in the past 60 minutes. If the STA has used 5 minutes of accumulated airtime for transmission in the past 60 minutes, the transmission budget is 1 minute. The STA enters the power management mode in step S412 if the STA has not yet acquired sufficient transmission budget, e.g., if the transmission budget calculated according to the accumulated airtime in the latest observation window over time is still below a safety threshold. In step S408, the STA determines whether there is data traffic buffered at the AP, e.g., based on one or more DTIM beacon frames received from the AP. In step S410, the STA transmits a quality of service null [awake] frame to inform the AP that it is ready to receive and respond if there is data traffic buffered for the STA. Otherwise, the STA enters the power management mode in step S412 if there is data traffic.After sending the quality of service null [awake] frame in step S410, the STA receives buffered traffic from the AP in step S422. In this embodiment, the STA sends the quality of service null [awake] frame to inform the AP that it can receive and respond to frames only if the AP has buffered data traffic. In another embodiment, the STA sends the quality of service null [awake] frame to inform the AP when it has acquired more transmission budget, regardless of whether the AP has buffered data traffic.

[0032] In step S414 of FIG. 4, the STA determines whether the transmission budget is about to run out if the transmission budget is not yet marked as exhausted in step S402. One example of determining whether the transmission budget is about to run out includes comparing the transmission budget to a predefined threshold, which in this embodiment is set to be longer than the airtime required to transmit both the quality of service null [asleep] frame and the vendor action frame. In another embodiment, when only the quality of service null [asleep] frame or the vendor action frame is used to notify the AP, the predefined threshold may be set to be longer than the airtime required to transmit the quality of service null [asleep] frame or the vendor action frame, respectively. The STA may proceed to step S412 or may remain awake if the transmission budget is not about to run out. The STA transmits a quality of service null [asleep] frame in S416 to notify the AP if the STA's transmission budget is about to run out. After transmitting the quality of service null [asleep] frame, the STA calculates a time from the perspective of the TSF at which the STA has a transmission budget for transmitting a frame again in step S418. The STA then inserts this TSF information into a vendor action frame to send to the AP in step S418. In other embodiments, the STA may first calculate a time and send the vendor action frame before sending the quality of service null [asleep] frame. In step S420, the STA marks the transmission budget as exhausted and pauses the traffic queues, and then enters the power management mode in step S412. In this embodiment, the transmission budget is marked as exhausted if the transmission budget falls below a predetermined threshold and the STA transmits both a quality of service null [asleep] frame and a vendor action frame. The predetermined threshold may be the same or different from the safety threshold used to check whether it is sufficient to unpause the traffic queues, depending on the application use or design.

[0033] FIG. 5 is a flow chart showing an AP notifying associated APs about the depletion of the transmission budget according to an embodiment of the present invention. In this embodiment, the AP notifies STAs using both standard and proprietary signaling methods when it exhausts the transmission budget of non-beacon frames. In some embodiments, the AP employs only the standard signaling method. In some other embodiments, the AP employs only the proprietary signaling method because the AP is configured to allow all associated STAs to calculate the resume time from the vendor IE carried in the beacon frame. Here, the resume time is the time when the AP has the transmission budget for transmitting non-beacon frames. In step S502 of FIG. 5, the AP waits for a frame to transmit, and if there is a frame to transmit, the AP determines whether the transmission budget of non-beacon frames is exhausted in step S504. For example, the transmission budget of non-beacon frames is exhausted when the transmission budget is lower than the threshold reserved for beacon transmission. If the transmission budget is sufficient for non-beacon frames, the AP transmits the frame in step S514. Otherwise, in step S504, if the transmission budget of non-beacon frames is exhausted, the AP determines whether the frame is a beacon frame in step S506. In this embodiment, if the frame is not a beacon frame, the AP drops the frame in step S508. If the AP is transmitting a beacon frame, the AP inserts an RPS IE with an unused Association ID (AID) to reserve a time slice between this Target Beacon Transmission Time (TBTT) and the next TBTT in step S510. In this embodiment, in step S512, the AP further calculates the resume time in terms of the TSF for which the AP will have a transmission budget of non-beacon frames, and inserts this information into the vendor IE added to the beacon frame to be transmitted.STAs that can decode this vendor IE have information when the AP has a transmission budget, while STAs that cannot decode this vendor IE only wait to receive the next beacon frame at the next TBTT. In some other embodiments, the AP skips this step S512 of calculating the STF and inserting the resume time information into the vendor IE, so that all STAs need to listen to the next beacon frame after receiving this received beacon. The order of these two steps S510 and S512 can be switched, or these two steps can be performed simultaneously. The AP may transmit a frame in step S514 and return to step S502 to wait to transmit another frame.

[0034] FIG. 6 is a flow chart showing a STA receiving a notification from an associated AP indicating that its transmission budget is exhausted according to an embodiment of the present invention. In this embodiment, the STA can decode a vendor peer exhaustion IE in a beacon frame indicating when the AP has a transmission budget again. The STA receives a beacon frame in step S602, determines whether the beacon frame includes an RPS IE in step S604, and if the beacon frame includes an RPS IE, analyzes the RPS IE in step S606. By analyzing the RPS IE, if the AID in the RPS IE does not match the AID of the STA, it indicates that the medium is reserved for a certain period of time, and the STA is prohibited from transmitting frames in this RAW defined by the RPS. The STA further determines whether the received beacon frame includes a vendor peer exhaustion IE in step S608. If the beacon frame does not include a vendor peer exhaustion IE in step S608, the STA waits to receive the next beacon frame in step S614. In one embodiment, the STA enters the power management mode before receiving the next beacon frame. In step S610, the STA may decode the vendor peer exhaustion IE and determine the TSF for which the AP has a transmission budget, and in step S612, the STA may enter the power management mode until the determined TSF. In this embodiment, the STA may skip receiving one or more subsequent beacon frames if these beacon frames are transmitted before the determined TSF. In another embodiment, in which the STA cannot decode the vendor peer exhaustion IE, after analyzing that the AID does not match the AID, the STA stops transmitting the entire scheduled RAW and waits to receive the next beacon frame. The STA may enter the power management mode between two beacon frames.

[0035] FIG. 7 is a flow chart showing an AP receiving a notification from an associated STA indicating that its transmission budget is exhausted according to an embodiment of the present invention. In this embodiment, the AP can decode the vendor peer exhaustion notification indicating when the STA has a transmission budget again. For example, the vendor peer exhaustion notification is conveyed through a vendor action frame, and the vendor peer exhaustion notification also includes information of the resume time from the perspective of the TSF. The AP receives a frame from the STA in step S702, and determines whether the received frame is a quality of service null [asleep] frame in step S704. After receiving the quality of service null [asleep] frame from the STA, the AP buffers the data traffic of the STA in step S706, assuming that the STA is in a power management mode. The AP determines whether the received frame is a quality of service null [awake] frame in step S708, and transmits the buffered data traffic to the STA upon receiving the quality of service null [awake] frame from the STA in step S710. The AP checks in step S712 whether the frame received from the STA is a frame containing a vendor peer depletion notification, and if so, the AP stores information about whether the STA is expected to obtain more transmission budget according to the vendor peer depletion notification in step S714. Figure 7 shows how the AP reacts when receiving these three types of frames related to the transmission budget depletion notification, and the description of the processing and reaction of other types of frames received by the AP is omitted for brevity. In another embodiment, an AP that does not support proprietary signaling only responds to a data frame carrying a power management bit and suspends or resumes communication with the STA.

[0036] FIG. 8A illustrates a high-level block diagram of a wireless communication device 800 that can be used to implement an embodiment of the present invention. The embodiment of the wireless communication device 800 manages the Media Access Control (MAC) layer and the Physical (PHY) layer in compliance with the IEEE 802.11 standard with duty cycle constraints. The wireless communication device 800 may be a station (STA) or an access point (AP) of a wireless network. For example, the wireless communication device 800 may be implemented in a mobile device, a personal computer, a laptop computer, an Internet of Things (IoT) device, a wearable device, an augmented reality device, a video server, a camera, or a communication device on a vehicle. The wireless communication device 800 includes a Radio Frequency (RF) transmit module 802, an RF receive module 804, an antenna unit 806, one or more memory banks 808, an input / output interface 810, and a communication bus 812. The RF transmit module 802 and the RF receive module 804, also known as modems (modulator demodulators), transmit frames by modulating one or more carrier signals into coded digital information and receive frames by demodulating the signals to recreate the original digital information. Furthermore, the wireless communication device 800 includes a MAC processor 814, a PHY processor 816, and a host processor 818. These processors may be any type of integrated circuit (IC), including a GPU (General Processing Unit), an ASIC (Application Specific Integrated Circuit), or a RISC-V (Reduced Instruction Set Computer-Five) based IC, etc. The memory 808 stores software for the processors of the wireless communication device 800. Each processor executes software to implement the functions of its respective communication / application layer. In particular, the PHY processor 816 includes a transmit signal processing unit and a receive signal processing unit and manages the interface with the wireless medium (WM).The PHY processor 816 operates on Physical Protocol Data Units (PPDUs) by exchanging digital samples with the radio module, which includes the RF transmitter 802, a digital-to-analog converter (DAC), an RF receiver 804, and an analog-to-digital converter (DAC). The MAC processor 814 executes MAC-level instructions and manages the interface between the application software and the WM via the PHY processor 816. The MAC processor 814 is responsible for coordinating access to the WM so that APs and STAs within range can communicate effectively. The MAC processor 814 adds header and tail bytes to data units provided by the upper level and sends them to the PHY layer for transmission. The reverse is true when receiving data from the PHY layer. If a radio frame is received in error, the MAC processor 814 manages the retransmission of the radio frame. The host processor 818 is responsible for interfacing with the MAC layer and performing the high-level functions of the wireless communication device 800.

[0037] The peripheral bus 820 connects to a number of peripherals that support the core functions of the wireless communication device 800, including timers, interrupts, radio / filter / system registers, counters, Universal Asynchronous Receiver / Transmitter (UART) and General Purpose Input Output (GPIO). The PHY processor 816, the MAC processor 814, the host processor 818, the peripheral bus 820, the memory 808 and the input / output interface 810 communicate with each other via the system bus 812. The memory 808 may also store an operating system and applications. In some embodiments, the memory 808 may store record information regarding captured frames and packets. The input / output interface unit 810 allows for the exchange of information with a user. The antenna unit 806 may include a single antenna or multiple antennas.

[0038] FIG. 8B is a schematic block diagram of a receiver data flow architecture used to receive wireless signals transmitted to the wireless communication device 800. Wireless signals are received via the WM and converted to electrical signals by a receive antenna 852. The received signals are conditioned using a series of analog RF receive (Rx) filters 854 before being converted to digital signals using an ADC 856. The digital signals output from the ADC 856 are conditioned again using a digital filter bank 258, which may include one or more digital RF filters and / or Farrow filters, before the samples in the digital signals are collected in an asynchronous receive first-in-first-out (FIFO) data structure 860. The samples in the asynchronous receive FIFO data structure 860 can be accessed by a packet detection module and a sub-band module, both of which may be included in a lower level PHY portion 862. In some embodiments, the lower level PHY portion 862 is included in the PHY processor 816 shown in FIG. 8A along with the upper level PHY portion 264. The packet detection module included in the lower level PHY portion 862 has hardware and / or implemented algorithms that can be used to analyze an initial section of a PHY protocol data unit (PPDU) in the time domain. Based on the analysis, the packet detection module recognizes the received 802.11 frame and synchronizes the frequency and timing of the wireless communication device to the packet being received. The sub-band module has hardware and / or implemented algorithms that can be used to detect which sub-channel within the assigned frequency band is being used to transmit the packet being received. Once a packet is detected and the associated sub-channel is established, the sample is conveyed to the upper level PHY portion 864. Some embodiments of the upper level PHY portion 864 process and decode the orthogonal frequency division multiplexing (OFDM) symbols to reconstruct the complete PPDU. The reconstructed PPDU is then processed by the MAC module 866 to extract the data payload and provided to the host module 868 for consumption of the associated information.

[0039] FIG. 8C shows a simplified schematic block diagram of a transmitter data flow architecture 880 used to transmit wireless signals over the WM. Data originates from a host module 882 and is packaged into a MAC level protocol data unit (MPDU) to be routed over the wireless network by a MAC management module 884. A PHY module 886 interfaces with the WM and compiles a PHY level protocol data unit (PPDU) by adding a PHY preamble and tail to the MPDU. Typically, a modulation coding scheme (MCS) for transmitting packets over the medium is established using a rate control algorithm by the MAC module 884 or the PHY module 886. The selected modulation scheme defines the modulation technique and coding rate used for data transmission over the WM. Based on the selected modulation scheme, e.g., Quadrature Amplitude Modulation (QAM) 64, the PPDU is modulated to be transmitted over the WM. An encoder module 888 generates signals corresponding to points of QAM constellation symbols (groups of bits in the PPDU) that can be encoded using polar coordinates (r-θ) or Cartesian coordinates (QI). The modulation is performed by linking the encoder module 888 to a Digital Phase Lock Loop (DPLL) 890. The modulated signal is filtered by an analog filter 892 and transmitted using a transmit antenna 894.

[0040] Although the present invention has been illustrated and described herein with reference to specific embodiments, it is not intended that the invention be limited to the details shown. Rather, various changes in details may be made within the scope of the claims and equivalents without departing from the invention. It should be understood that the above description is illustrative of the invention and is not to be construed as limiting the invention. Those skilled in the art may make various modifications, applications, and / or combinations of the embodiments without departing from the scope of the invention as defined by the claims. Well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail to avoid obscuring aspects.

[0041] The processes and methods according to the above examples can be stored on a computer-readable medium or implemented using computer-executable instructions. Such instructions may include, for example, instructions and data that cause or otherwise configure a general purpose computer, a special purpose computer, or a processing device to perform a certain function or group of functions. Some of the computer resources used may be accessible over a network. The computer-executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, firmware, source code, etc. Apparatuses implementing the processes and methods according to these disclosures may include hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof, and may take any of a variety of form factors. When implemented in software, firmware, middleware, or microcode, the program code or code segments to perform the necessary tasks may be stored on a computer-readable or machine-readable medium. The computer-readable medium may include, for example, memory or data storage media, such as Random-Access Memory (RAM), such as Synchronous Dynamic Random-Access Memory (SDRAM), Read-Only Memory (ROM), Non-Volatile Random-Access Memory (NVRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), FLASH memory, magnetic data storage media, or optical data storage media. Additionally or alternatively, the technology may be realized at least in part by a computer-readable communications medium, such as a propagated signal or wave, that carries or communicates program code in the form of instructions or data structures and that can be accessed, read, and / or executed by a computer.The program code may be executed by a processor, which may include one or more processors including one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Such a processor may be configured to perform any of the steps described in this disclosure. A general purpose processor may be a microprocessor, or alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may be implemented as a combination of computing devices.

[0042] As mentioned above, various example components, blocks, modules, engines, circuits, and steps have been described in terms of their functionality to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends on the application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in different ways for each application, and such implementation decisions should not be interpreted as a departure from the scope of the present application.

Claims

1. 1. A signaling method for notifying a peer device of a wireless connection to a wireless communication network, the signaling method comprising: determining whether a transmission budget is about to be depleted, the transmission budget being derived based on a duty cycle constraint and an accumulated transmission time within an observation window; in response to determining that the transmission budget is about to be depleted, transmitting a first data frame to a peer device, the first data frame carrying a power management bit to mark the transmission budget as depleted; updating the transmission budget over time, transmitting a second data frame carrying a power management bit to the peer device, and resuming communication with the peer device in accordance with the updated transmission budget.

2. the first data frame carrying a power management bit is used to inform a peer device of entering a power management mode; 2. The signaling method of claim 1, wherein the second data frame carrying a power management bit is used to inform a peer device to exit a power management mode.

3. 3. The signaling method of claim 2, wherein the first data frame carrying a power management bit is a quality of service null (QOS) [asleep] frame and the second data frame carrying a power management bit is a quality of service null [awake] frame.

4. 2. The signaling method of claim 1, wherein the transmission budget is about to run out when the transmission budget falls below a threshold, the threshold being set according to a communication time for transmitting one or more frames.

5. 2. The signaling method of claim 1, wherein the threshold is set to be longer than a communication time for transmitting a first data frame carrying a power management bit.

6. determining whether there is buffered data traffic in the peer device; 2. The method of claim 1, further comprising: transmitting the second data frame carrying a power management bit only if there is buffered data traffic in the peer device.

7. receiving one or more beacon frames from the peer device; 7. The signaling method of claim 6, further comprising: determining whether there is buffered data traffic in the peer device according to the one or more beacon frames.

8. 2. The signaling method of claim 1, further comprising: entering a power management mode if the transmission budget is marked as depleted.

9. calculating when the transmission budget will be updated to resume communication with the peer device; inserting information corresponding to the time point into a third frame; 2. The method of claim 1, further comprising: transmitting the third frame to the peer device.

10. the third frame is a vendor-specific action frame; 10. The signaling method according to claim 9, characterized in that the time point is calculated in terms of a Time Synchronisation Function (TSF).

11. if the transmission budget is below a threshold, the transmission budget is about to be depleted; 10. The signaling method of claim 9, wherein the threshold is set to be longer than a communication time for transmitting a first data frame and a third frame carrying a power management bit.

12. receiving a beacon frame from the peer device; Parsing a vendor peer exhaustion information element (IE) in the beacon frame; determining a resume time from the vendor peer exhaustion IE; 2. The signaling method of claim 1, further comprising: entering a power management mode until the resume time.

13. 1. A signaling method for notifying one or more peer devices wirelessly connected to a wireless communication network, the signaling method comprising: determining whether a transmission budget is about to be depleted, the transmission budget being derived based on a duty cycle constraint and an accumulated transmission time within an observation window; in response to the transmission budget being exhausted, inserting a restricted access window parameter set (RPS) information element (IE) into a beacon frame to reserve a time slice between a current target beacon transmission time (TBTT) and a next TBTT; and transmitting a beacon frame on the wireless channel to notify that one or more peer devices are prohibited from transmitting on the wireless channel between the current TBTT and the next TBTT.

14. 14. The signaling method of claim 13, further comprising dropping non-beacon frames in response to the transmission budget becoming depleted.

15. The RPS IE in the beacon frame includes an unused Association ID (AID) that is not assigned to any peer device in a wireless communication network; 14. The signaling method of claim 13, wherein the peer device receiving the beacon frame is prohibited from accessing the radio channel between a current TBTT and a next TBTT.

16. when the transmission budget falls below a threshold, the transmission budget is about to be depleted; 14. The signaling method according to claim 13, characterized in that the threshold is set to be longer than a communication time for transmitting one or more beacon frames.

17. 17. The signaling method of claim 16, further comprising: determining whether the transmission budget is still below a threshold at a next TBTT; and in response to the transmission budget being still below a threshold at the next TBTT, inserting an RPS IE into a next beacon frame, reserving another time slice, and transmitting the next beacon frame to one or more peer devices.

18. calculating when the transmission budget exceeds the threshold; The signaling method according to claim 16, further comprising: inserting information corresponding to the time point into a vendor information element (IE) added to the beacon frame.

19. receiving and parsing a vendor action frame from a first peer device indicating exhaustion of a peer transmission budget; in response to receiving the vendor action frame, buffering data traffic of the first peer device and suspending communications with the first peer device; 14. The signaling method of claim 13, further comprising: transmitting the buffered data traffic to the first peer device after a time derived from the vendor action frame.

20. A wireless communication device wirelessly connected to a wireless communication network, the wireless communication device including a receiver, a transmitter, a processor, and one or more memory banks; the processor is communicatively coupled to the receiver and the transmitter; The memory bank is communicatively coupled to the processor and stores processor readable code that, when executed by the processor in conjunction with the receiver and the transmitter, determining whether a transmission budget is about to be depleted, the transmission budget being derived based on a duty cycle constraint and an accumulated transmission time within an observation window; in response to determining that the transmission budget is about to be depleted, transmitting a first data frame to a peer device, the first data frame carrying a power management bit to mark the transmission budget as depleted; updating the transmission budget over time, transmitting a second data frame carrying a power management bit to the peer device, and resuming communication with the peer device in accordance with the updated transmission budget.

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