Power off alarm method and related device

Abstract

The embodiment of the present application discloses a power-off alarm method and related devices, which is used in the field of communication technology, and includes a step of a terminal device composing a dying gasp packet after being powered on, where the dying gasp packet is used to indicate that the terminal device is in a power-off state; and a step of the terminal device sending the dying gasp packet to a wireless access point after detecting a power-off signal. In the embodiment of the present application, upon detecting a power-off signal, the terminal device reports the power-off state of the terminal device to the wireless access point by using the dying gasp packet. The access point device can know the power-off failure of the terminal device in time and indicate to the gateway to maintain the terminal device. In this way, the maintenance cost of the terminal device can be greatly reduced and the maintenance efficiency can be improved.

Description

[Technical field]

[0001] TECHNICAL FIELD Embodiments of the present application relate to the field of communication technologies, and in particular to a power-off alarm method and related device. [Background technology]

[0002] With the rapid development of wireless communication technology, Wi-Fi, as a short-range wireless technology, is widely applied to various communication scenarios. In a Wi-Fi system, terminal devices share air interface resources provided by a Wi-Fi access network. When performing communication simultaneously, multiple Wi-Fi terminal devices need to compete for air interface resources to establish a connection to a Wi-Fi access point device.

[0003] When the air interface is busy, the Wi-Fi terminal device may not be able to obtain air interface resources due to contention, so communication is interrupted. When the Wi-Fi terminal device is powered off or the battery is depleted, the connection between the Wi-Fi terminal device and the Wi-Fi access point device is also broken. However, the core network connected to the Wi-Fi access point device cannot recognize the reason for the interruption of the communication of the Wi-Fi terminal device, and therefore cannot specifically analyze the failure of the Wi-Fi terminal device. In some scenarios, the core network needs to know the power-off of the Wi-Fi terminal device. For example, a Wi-Fi camera deployed in a mountainous area or a reservoir is powered by a battery or solar energy. If the core network can recognize the failure occurring in the camera due to power-off, battery depletion, etc., the maintenance cost can be greatly reduced. Therefore, how to know the power-off failure of the Wi-Fi terminal device has become a problem that needs to be urgently solved. Summary of the Invention

[0004] An embodiment of the present application provides a power-off alarm method and related device for reporting power-off alarm information of a terminal device so that a terminal device can be known to be powered off based on the power-off alarm information, thereby reducing the maintenance cost of the terminal device.

[0005] A first aspect of an embodiment of the present application provides a power-off alarm method, including:

[0006] A Wi-Fi terminal device and an access point device perform data transmission through a wireless network. When in a power-off state due to battery depletion, power interruption, etc., the terminal device may transmit the state to the access point device. In this way, the access point device may transmit the power-off state of the terminal device to a network management device to facilitate subsequent maintenance of the terminal device. Thus, after being powered on, the terminal device pre-configures a dying gasp packet, which is used to indicate that the terminal device is in a power-off state. After detecting the power-off signal, the terminal device transmits the dying gasp packet to the wireless access point.

[0007] In the above embodiment, after receiving the power-off signal, the terminal device sends a dying gasp packet to the access point device to provide feedback that the terminal device is in a power-off state. In this way, the access point device can send the status to the network management device so that the network management device knows the reason for the failure of the terminal device and then maintains the terminal device, which greatly reduces the maintenance cost of the terminal device. In addition, when powered on, the terminal device pre-configures a dying gasp packet and immediately transmits the dying gasp packet after detecting the power-off signal. In this way, the time for assembling a dying gasp packet before the terminal device is powered off is reduced, the packet transmission success rate is increased, and the ability of the access point device to know the power-off state of the terminal device is improved.

[0008] Based on the first aspect, the present application further provides a first implementation of the first aspect.

[0009] The terminal device may feed back the power-off state of the terminal device to the wireless access point in two forms: a management frame and a data frame. That is, the terminal device may assemble a dying gasp packet in the form of a management frame and a dying gasp packet in the form of a data frame, and then transmit both dying gasp packets to the wireless access point by using a management frame queue and a data frame queue.

[0010] It can be understood that the management frame has a high transmission power and the data frame has a high transmission rate. By feeding back the power-off state of the terminal device in the form of two frames, the transmission success rate of the dying gasp packet can be further improved.

[0011] Based on the first implementation form of the first aspect, the present application further provides a second implementation form of the first aspect.

[0012] The dying gasp packet may be in the form of a management frame packet and a data frame packet, and the terminal device may reflect the power-off state of the terminal device by using a reserved field in the management frame packet. When assembling a dying gasp packet in the form of a management frame, the terminal device first determines the value of a preset reserved field and determines the management frame packet as a dying gasp packet. After detecting the power-off signal, the terminal device first clears a management frame queue of the terminal device, adds the dying gasp packet to the cleared management frame queue, and transmits the dying gasp packet to the wireless access point by using the management frame queue.

[0013] When using a dying gasp packet in the form of a management frame, the terminal device needs to transmit the packet by using a management frame queue. When the terminal device is in a power-off state, the terminal device needs to reflect the power-off state to the wireless access point first. Therefore, by clearing the management frame queue, the waiting time for transmitting the dying gasp packet can be reduced, which further increases the success rate of transmitting the dying gasp packet.

[0014] Based on the first and second implementation forms of the first aspect, the present application further provides a third implementation form of the first aspect.

[0015] The terminal device may further reflect the power-off state of the terminal device in the form of a data frame packet. When assembling the dying gasp packet in the form of a data frame packet, the terminal device adds the data frame packet to a data frame queue, and transmits the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet is added.

[0016] Generally, since a data frame packet has a high transmission rate, the time it takes for a wireless access point to receive a dying gasp packet from a terminal device can be reduced, and the wireless access point can more quickly know that the terminal device has been powered off.

[0017] Based on the third implementation form of the first aspect, the present application further provides a fourth implementation form of the first aspect.

[0018] When reflecting the power-off state by using a data frame, the terminal device not only needs to assemble a data frame packet, but also needs to determine a data frame queue for transmitting the data frame packet. Therefore, before detecting a power-off signal, the terminal device needs to pre-determine a target data frame queue. Specifically, the target data frame queue can be determined based on the priorities corresponding to multiple data frame queues. For example, the data frame queue with the highest transmission level can be determined as the target data frame queue. After detecting the power-off signal, the terminal device adds the pre-constructed data frame packet to the target data frame queue, and transmits a dying gasp packet to the wireless access point by using the target data frame queue to which the data frame packet is added.

[0019] The target data frame queue is determined based on the priority, and the terminal device may select a data frame queue with a high transmission level to transmit the dying gasp packet. In this way, the waiting time for transmitting the dying gasp packet can be reduced, which further increases the success rate of transmitting the dying gasp packet.

[0020] Based on the first aspect, the present application further provides a fifth implementation of the first aspect.

[0021] It can be understood that the terminal device may designate a dedicated queue for dying gasp packets, and the dedicated queue may be used only for transmitting dying gasp packets. The terminal device transmits dying gasp packets to a wireless access point by using the dedicated queue without waiting, which further increases the success rate of transmitting dying gasp packets.

[0022] Based on the first to fifth implementation forms of the first aspect, the present application further provides a sixth implementation form of the first aspect.

[0023] The power-off signal is a power-off alarm signal of the terminal device, i.e., alarm information sent when the electrical energy of the terminal device is about to run out. Therefore, the terminal device can control the generation of the power-off signal by detecting the input voltage of the terminal device. When the input voltage corresponding to the terminal device is below a preset threshold, the terminal device generates the power-off signal.

[0024] Based on the first to sixth implementation forms of the first aspect, the present application further provides a seventh implementation form of the first aspect.

[0025] A transmission channel exists between the terminal device and the wireless access point device, and communication is implemented through the transmission channel. Therefore, when the terminal device is in a power-off state and sends a dying gasp packet to the wireless access point, the terminal device first increases a clear channel evaluation threshold corresponding to the transmission channel, and sends the dying gasp packet through the transmission channel.

[0026] The clear channel assessment value is used to reflect the busyness of a transmission channel. The terminal device determines whether to perform communication over a channel based on the clear channel assessment threshold. If the terminal device determines that the current clear channel assessment value of a channel is greater than the clear channel assessment threshold, the terminal device performs communication without using the channel. Thus, if the terminal device increases the clear channel assessment threshold, the amount of the transmission channel over which communication can be performed may increase, thereby increasing the success rate of transmission of dying gasp packets.

[0027] A second aspect of an embodiment of the present application provides a power-off alarm method, including:

[0028] A wireless access point receives a dying gasp packet transmitted by a terminal device. After receiving the dying gasp packet, the wireless access point may determine that the terminal device is in a power-off state.

[0029] When receiving the dying gasp packet sent by the terminal device, the wireless access point can know that the terminal device is in a power-off state. In this way, the access point device can send the status to the network management device so that the network management device knows the reason for the failure of the terminal device and maintains the terminal device, which greatly reduces the maintenance cost of the terminal device.

[0030] A third aspect of an embodiment of the present application provides a terminal device including: a processing unit configured to pre-configure a dying gasp packet after the terminal device is powered on, where the dying gasp packet is used to indicate that the terminal device is in a powered off state; a detection unit configured to detect a power off signal; and a transmission unit configured to transmit the dying gasp packet to a wireless access point after the power off signal is detected.

[0031] Based on the third aspect, the present application further provides a first implementation of the third aspect.

[0032] The sending unit is specifically configured to send both dying gasp packets to the wireless access point by using a management frame queue and a data frame queue.

[0033] Based on the first implementation form of the third aspect, the present application further provides a second implementation form of the third aspect.

[0034] The dying gasp packet includes a management frame packet.

[0035] The processing unit is specifically configured to determine a value of a preset field in the management frame packet, and determine the management frame packet as the dying gasp packet.

[0036] The processing unit is further configured to clear management frame packets to be transmitted in the management frame queue after the detection unit detects the power-off signal, and add the management frame packets to the cleared management frame queue.

[0037] The sending unit is specifically configured to send the dying gasp packet to the wireless access point by using the management frame queue to which the management frame packet has been added.

[0038] Based on the first and second implementation forms of the third aspect, the present application further provides a third implementation form of the third aspect.

[0039] The dying gasp packet includes a data frame packet.

[0040] The sending unit is specifically configured to add the data frame packet to the data frame queue, and transmit the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet has been added.

[0041] Based on the third implementation form of the third aspect, the present application further provides a fourth implementation form of the third aspect.

[0042] The terminal device further includes a determining unit.

[0043] The determining unit is configured to determine priorities corresponding to a plurality of data frame queues before the detecting unit detects the power-off signal, and determine a target data frame queue based on the priorities.

[0044] The transmitting unit is specifically configured to add the data frame packet to the target data frame queue and transmit the dying gasp packet to the wireless access point by using the target data frame queue to which the data frame packet has been added.

[0045] Based on the third aspect, the present application further provides a fifth implementation of the third aspect.

[0046] The terminal device pre-configures a dedicated queue.

[0047] The sending unit is specifically configured to send the dying gasp packets to the wireless access point by using the dedicated queue.

[0048] Based on the third to fifth implementation forms of the third aspect, the present application further provides a sixth implementation form of the third aspect.

[0049] The power-off signal is generated when an input voltage corresponding to the terminal device is below a preset threshold.

[0050] Based on the third to sixth implementation forms of the third aspect, the present application further provides a seventh implementation form of the third aspect.

[0051] A transmission channel exists between the terminal device and the wireless access point.

[0052] The transmitting unit is further configured to increase a clear channel assessment threshold corresponding to the transmission channel, and transmit the dying gasp packet via the transmission channel.

[0053] A fourth aspect of an embodiment of the present application provides an access point device including: a receiving unit configured to receive a dying gasp packet transmitted by a terminal device; and a determining unit configured to determine a power-off state of the terminal device based on the dying gasp packet.

[0054] A fifth aspect of the present application provides a terminal device including at least one processor and a memory. Computer executable instructions operable on the processor are stored in the memory. When the computer executable instructions are executed by the processor, the terminal device performs a method according to any one of the first aspect or possible implementations of the first aspect.

[0055] A sixth aspect of the present application provides an access point device including at least one processor and a memory, the memory storing computer executable instructions operable on the processor, the access point device performing the method of the second aspect when the computer executable instructions are executed by the processor.

[0056] A seventh aspect of the present application provides a power-off alarm system, including a terminal device and an access point device. The terminal device executes the method in any one of the first aspect or possible implementation forms of the first aspect. The access point device executes the method in the second aspect.

[0057] An eighth aspect of an embodiment of the present application provides a computer storage medium comprising a program, which when run on a computer enables the computer to perform the method of any one of the first aspect or possible implementations of the first aspect.

[0058] A ninth aspect of the present application provides a chip or chip system. The chip or chip system includes at least one processor and a communication interface. The communication interface and the at least one processor are interconnected via a line. The at least one processor is configured to run a computer program or instructions to perform the power-off alarm method described in any one of the first aspect or possible implementations of the first aspect.

[0059] The communication interface in a chip may be an input / output interface, a pin, or a circuit.

[0060] In a possible implementation, the chip or chip system described above in this application further includes at least one memory in which instructions are stored. The memory may be a storage unit internal to the chip, such as a register or cache, or may be a storage unit of the chip (e.g., a read-only memory or a random access memory).

[0061] A tenth aspect of the present application provides a computer program product, the computer program product including computer software instructions, the computer software instructions being loadable by a processor to implement the steps of the power-off alarm method in any one of the first aspect or possible implementations of the first aspect.

[0062] From the above technical solutions, it can be seen that the embodiments of the present application have the following advantages:

[0063] In the present embodiment, after being powered on, the terminal device pre-constructs a dying gasp packet, and after detecting a power-off signal, the terminal device transmits a dying gasp packet to the access point device to provide feedback that the terminal device is in a power-off state. The access point device can know the power-off failure of the terminal device by using the mechanism of the dying gasp packet, and facilitate the subsequent maintenance of the terminal device, thereby greatly reducing the maintenance cost of the terminal device. In addition, when being powered on, the terminal device pre-constructs a dying gasp packet, and immediately transmits the dying gasp packet after detecting a power-off signal. Therefore, the time for assembling a dying gasp packet before the terminal device is completely powered off can be reduced, and the packet transmission success rate can be increased, thereby improving the ability of the wireless access point to know the power-off state of the terminal device. [Brief description of the drawings]

[0064] [Figure 1] 4 is a schematic flowchart of a power-off alarm method according to an embodiment of the present application;

[0065] [Diagram 2] FIG. 2 is a schematic diagram of the structure of a terminal device according to an embodiment of the present application;

[0066] [Diagram 3] FIG. 2 is a schematic diagram of the structure of an access point device according to an embodiment of the present application;

[0067] [Figure 4] FIG. 2 is a schematic diagram of the structure of another terminal device according to an embodiment of the present application;

[0068] [Diagram 5] FIG. 2 is a schematic diagram of the structure of another access point device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] An embodiment of the present application provides a power-off alarm method and related device for reporting power-off alarm information of a terminal device so that a terminal device can be known to be powered off based on the power-off alarm information, thereby reducing the maintenance cost of the terminal device.

[0070] The technical solutions in the present application are clearly described below with reference to the accompanying drawings in the present application. It is apparent that the described embodiments are only a part, but not all, of the embodiments in the present application.

[0071] In the present specification, claims, and accompanying drawings, terms such as "first," "second," "third," and "fourth," when present, are intended to distinguish between similar objects, but do not necessarily indicate a particular order or sequence. It should be understood that data used in such a manner are interchangeable in appropriate circumstances, such that the embodiments described herein can be implemented in orders other than those illustrated or described herein. In addition, terms such as "comprises," "having," and other variations thereof are intended to cover non-exclusive inclusions, e.g., a process, method, system, product, or device comprising a series of steps or units is not necessarily limited to the steps or units expressly recited, but may include other steps or units that are not expressly recited or are intrinsic to such process, method, product, or device.

[0072] As a short-range wireless network transmission technology, Wi-Fi can convert wired network signals into wireless signals for transmission. A Wi-Fi system can include an access point device and a terminal device. One end of the access point device is connected to a wired network, and the other end is connected to the terminal device through a wireless channel. The access point device is configured to perform conversion between wired signals and wireless signals. The access point device can convert wired signals in the wired network to wireless signals and then forward the wireless signals to the terminal device, and can also receive the wireless signals of the terminal device, convert the wireless signals to wired signals, and forward the wired signals to the wired network.

[0073] In a Wi-Fi system, all terminal devices share air interface resources. When an access point device communicates with a terminal device, the terminal device needs to compete for air interface resources. Therefore, the reason for the terminal device being disconnected may be a communication failure caused when the air interface resource is not obtained through contention, or a communication failure with the access point device caused by a failure of the terminal device, such as the power-off or battery depletion of the terminal device. Currently, the Wi-Fi system is applicable to personal home devices in most cases, and the access point device does not need to know the reason why the terminal device is disconnected. However, in some new application scenarios of the Wi-Fi system, the access point device needs to know the reason why the terminal device is disconnected. For example, a Wi-Fi camera deployed in a mountain area or a reservoir is powered by a battery or solar energy, and the communication with the access point device is easily interrupted due to a failure such as the power-off or battery depletion. When deploying experts to perform on-site monitoring and maintenance, it is necessary to consume sufficient manpower and material resources. If the terminal device can report the power-off state of the terminal device by itself, the maintenance cost can be greatly reduced. In addition, how a terminal device can successfully report a power-off state due to interference or in a remote environment also becomes a problem that needs to be urgently solved.

[0074] Based on the above-mentioned problems, the embodiments of the present application provide a power-off alarm method and related devices to report the power-off state of a terminal device by using a dying gasp mechanism, so that the access point device can know the power-off failure of the terminal device in a timely manner, and then report the power-off to the gateway and perform maintenance for the power-off failure, thereby reducing maintenance costs.

[0075] The dying gasp mechanism is a method for performing monitoring and alarm generation for the power supply of a terminal device. The principle of the dying gasp mechanism is as follows: when a terminal monitors the status of the power supply and finds that the device is powered off or the battery is depleted, it will transmit the final status information of the terminal device by using the energy stored by the energy storage component of the terminal device, such as a large-capacity capacitor or a backup battery. Therefore, the terminal device can report the power-off status of the terminal device to the access point device by using the dying gasp mechanism, so that the access point device knows the reason why the terminal device is disconnected.

[0076] A Wi-Fi terminal device and an access point device perform data transmission through a wireless network. When in a power-off state due to battery depletion, power interruption, etc., the terminal device may send a dying gasp packet to the access point device. In this way, the access point device may send the power-off state of the terminal device to a network management device based on the dying gasp packet to facilitate subsequent maintenance of the terminal device. Therefore, after being powered off, the terminal device may first pre-configure a dying gasp packet. After detecting a power-off signal, the terminal device sends a dying gasp packet to a wireless access point.

[0077] In the above embodiment, after receiving the power-off signal, the terminal device sends a dying gasp packet to the access point device to provide feedback that the terminal device is in a power-off state. In this way, the access point device can send the status to the network management device so that the network management device knows the reason for the failure of the terminal device and maintains the terminal device, which greatly reduces the maintenance cost of the terminal device.

[0078] Specifically, to transmit a dying gasp packet, a series of steps such as packet construction, inter-core communication, queue caching, aggregation waiting, and air interface scheduling need to be passed. Therefore, if the terminal device assembles and transmits a packet after detecting a power-off signal, it is highly likely that the amount of electricity in the energy storage component will be exhausted before the packet is assembled. In addition, if the dying gasp packet is transmitted in the form of a normal management packet or data packet, when the contention for the air interface is intense or the distance between the terminal device and the access point device is long, it is highly likely that the packet will be damaged and cannot be successfully transmitted to the access point device, which will ultimately cause a failure in reporting the power-off state of the terminal device.

[0079] In order to improve the success rate of sending dying gasp packets, Figure 1 is a schematic flow chart of a power-off alarm method according to an embodiment of the present application. As shown in Figure 1, the power-off alarm method includes the following steps:

[0080] 101: After being powered on, the terminal device composes a dying gasp packet and detects a power-off signal.

[0081] In order to ensure that the dying gasp packet is successfully transmitted, the dying gasp packet needs to be pre-assembled before the power-off signal is detected, so that the dying gasp packet can be transmitted immediately after the power-off signal appears, thereby avoiding the case where the energy storage component is depleted of electricity before the packet is assembled and after the terminal device is powered off.

[0082] Specifically, the terminal device may start to preassemble a dying gasp packet after being powered on, and the dying gasp packet is used to indicate that the terminal device is in a power-off state. The assembled dying gasp packet is stored. The terminal device starts to monitor the battery status, and immediately sends the dying gasp packet after detecting the power-off signal. In this way, the time for assembling a dying gasp packet before the terminal device is powered off is reduced, and the packet transmission success rate is increased.

[0083] In order to further increase the transmission success rate of the dying gasp packet, two forms of frames may further be used to carry the information of the power-off state of the terminal device. That is, the dying gasp packet includes a management frame packet and a data frame packet. The management frame packet is transmitted by using a management frame queue, and the data frame packet is transmitted by using a data frame queue. The management frame packet and the data frame packet are described individually below.

[0084] (1) Management frame packets

[0085] The management frame has high transmission power, which can overcome power loss in wireless networks. When the distance between the terminal device and the access point device is long, the transmission success rate of the management frame is high. There are various types of management frames for interaction between Wi-Fi devices. The access point device may send a management frame request to the terminal device. The terminal device responds to the request and sends a management frame answer to the access point device to complete the communication between the access point device and the terminal device.

[0086] For example, when a terminal device is disconnected from an access point device, the terminal device may send a deauthentication (deauth) management frame to the access point device. Thus, when the terminal device is in a power-off state, the power-off state of the terminal device may be conveyed by using the deauth management frame to assemble a dying gasp packet. Specifically, the power-off state of the terminal device may be indicated by using a reserved field in the deauth management frame.

[0087] For example, an identifier field may be extended in the reserved field of the deauth management frame to indicate the power-off state of the terminal device. For example, the reserved field is determined as an identifier bit of the power-off state, and when the reserved field is 1, it indicates that the terminal device is in the power-off state, and when the reserved field is 0, it indicates that the terminal device is not in the power-off state. After being powered on, the terminal device may preassemble a deauth management frame, determine the value of the reserved field reflecting the power-off state as 1, encapsulate the deauth management frame, and determine the deauth management frame as a dying gasp packet. When in the power-off state, the terminal device transmits a dying gasp packet. The access point device detects the received dying gasp packet and knows the status of the terminal device based on the value of the reserved field reflecting the power-off state.

[0088] (2) Data frame packet

[0089] The data frame has a high transmission rate, which can implement high-speed transmission in the wireless network, reduce interference from other signals in the wireless network, and increase the success rate of sending dying gasp packets. For example, the terminal device may fill the data frame in the form of a preamble+TLV format, and the wireless access point device performs analysis in the form of the preamble+TLV format to determine the content of the data frame. Specifically, the form of the data frame packet indicating that the terminal device is in a power-off state is not limited.

[0090] It can be seen that when assembling the dying gasp packet in two forms of frames, the terminal device can report the power-off state of the terminal device more effectively, which increases the possibility that the access point device knows the power-off state of the terminal device. The management frame packet can be transmitted by using a management frame queue, and the data frame is transmitted by using a data frame queue. The terminal device can further pre-configure a dedicated queue for the dying gasp packet. That is, the dedicated queue is only used to transmit the dying gasp packet instead of another packet. In this way, the dying gasp packet can be transmitted quickly and effectively, which reduces the time waiting for the transmission of the packet and increases the packet transmission success rate.

[0091] 102: The terminal device determines priorities corresponding to a plurality of data frame queues.

[0092] It can be understood that the terminal device has various types of data frame queues, and the data frame queues have different priorities. A data frame with a higher priority in a data frame queue is preferentially transmitted. For example, the terminal device includes a VI queue and a VO queue. The VI queue is used to transmit video data, and the VO queue is used to transmit audio data. The priority of the VI queue is higher than the priority of the VO queue. Therefore, compared with the data frames in the VO queue, the data frames in the VI queue are preferentially transmitted.

[0093] 103: The terminal device determines a target data frame queue based on priority.

[0094] It can be understood that in order to ensure that the dying gasp packet is transmitted promptly after power-off and to avoid the case where the packet is not transmitted because the amount of electricity in the energy storage component is depleted, the terminal device needs to select a high-priority data frame queue for transmission. For example, the data frame queue with the highest priority can be selected as the target data frame queue. When in a power-off state, in order to increase the success rate of transmitting the dying gasp packet, the terminal device transmits the data frame packet by using the target data frame queue.

[0095] It can be understood that the terminal device may immediately select a target data frame queue after being powered on, that is, step 101 may be performed simultaneously with steps 102 and 103, and there is no time sequence relationship.

[0096] 104: The terminal device detects a power-off signal.

[0097] The power-off signal may be a power-off alarm signal of the terminal device, i.e., an alarm signal sent when the terminal device is powered off or the battery is depleted. Specifically, the detection unit of the terminal device may monitor the input voltage of the terminal device. When the input voltage is detected to be below a certain value, it indicates that the terminal device is in a power-off state. In this case, the power-off signal is sent to indicate the terminal device to send a dying gasp packet to the access point device to report the power-off failure of the terminal device.

[0098] 105: The terminal device clears the management frame packets to be transmitted from the management frame queue.

[0099] Specifically, when a management frame packet is transmitted by using a management frame queue, the terminal device needs to clear another management frame packet in the management frame queue. The terminal device should transmit packets sequentially in the order of the management frame packets in the queue, and reduce the waiting time for transmitting the dying gasp packet to ensure that the terminal device transmits the dying gasp packet before the terminal device is completely powered off. Thus, the packet to be transmitted first in the queue can be cleared, so that the dying gasp packet can be directly transmitted without waiting, which further increases the transmission success rate of the dying gasp packet.

[0100] 106: The end device adds the management frame packet to the cleared management frame queue.

[0101] After clearing the management frame queue, the terminal device adds a management frame packet to the cleared management frame queue, and transmits the management frame packet via the transmission window: management frame queue.

[0102] 107: The terminal device adds the data frame packet to the target data frame queue.

[0103] The terminal device can transmit data frame packets by using a target data frame queue and transmit the data frame packets preferentially, so that the dying gasp packets are transmitted quickly and the transmission success rate of the dying gasp packets is increased.

[0104] It can be understood that the terminal device can execute step 106 and step 107 simultaneously. That is, the step of adding the management frame packet to the management frame queue and the step of adding the data frame packet to the data frame queue by the terminal device are independent of each other, and there is no time sequence. The terminal device may preferentially add the management frame packet to the management frame queue, or may preferentially add the data frame packet to the data frame queue, or may execute these two steps simultaneously. This is not specifically limited.

[0105] For example, the processing chip of the terminal device may further provide a hardware queue for transmitting a specific service packet individually. The transmission priority of the hardware queue may be higher than the transmission priority of another queue. The terminal device may designate a special service packet for the queue and pre-configure the queue for specially transmitting dying gasp packets. Specifically, the chip provides a dedicated pre-configured interface to bypass another protocol stack and cache queue. In this way, steps such as inter-core communication, queue caching, and aggregation waiting, which are required for transmitting normal packets, are omitted, thereby increasing the packet transmission efficiency of dying gasp packets.

[0106] 108: The terminal device transmits both the management frame packet and the data frame packet to the wireless access point by using the management frame queue and the data frame queue.

[0107] The terminal device may transmit both of the two forms of dying gasp packets by using a management frame queue and a data frame queue to increase the possibility that the access point device receives the dying gasp packet. For example, the management frame queue and the data frame queue may be configured to be transmitted periodically. That is, the terminal device does not pay attention to the reception status of the access point device but continues to transmit. By performing transmission multiple times, the access point device may increase the success rate of receiving the packet, so that the access point device knows the power-off state of the terminal device, and thus the success rate of reporting the dying gasp packet may increase.

[0108] It can be understood that the management frame queue and the data frame queue are cache queues of the terminal device and the "transmission window" of the packet, and there are further wireless communication channels between the terminal device and the access point device. In general, when the terminal device communicates with the access point device, it needs to detect the clear channel assessment values ​​of multiple transmission channels to obtain the busyness of each communication channel. However, if the clear channel assessment value of a communication channel is greater than the clear channel assessment threshold, it indicates that the contention interference of the air interface corresponding to the communication channel is very strong, and the terminal device will not select the communication channel for communication. However, in this embodiment, in order to increase the transmission success rate of the dying gasp packet, even if the transmission channel is busy, the dying gasp packet still needs to be transmitted through the transmission channel. Therefore, the terminal device needs to increase the clear channel assessment threshold of the transmission channel. In this way, the amount of communication channels that can be selected by the terminal device is increased, and the dying gasp packet can be transmitted through multiple transmission channels, thereby increasing the packet transmission success rate.

[0109] In this embodiment, the terminal device transmits both dying gasp packets by using a management frame queue and a data frame queue, and performs other transmissions in conjunction to increase the success rate of transmitting dying gasp packets as much as possible, so that the access point device knows the power-off state of the terminal device, which provides the necessary conditions for later maintenance of the terminal device, and reduces the maintenance costs of the terminal device.

[0110] FIG. 2 is a structural schematic diagram of a terminal device according to an embodiment of the present application. As shown in FIG. 2, the terminal device includes: a processing unit 201 configured to pre-configure a dying gasp packet after the terminal device is powered on, where the dying gasp packet is used to indicate that the terminal device is in a powered off state; a detection unit 202 configured to detect a power off signal; and a sending unit 203 configured to send the dying gasp packet to a wireless access point after the power off signal is detected.

[0111] In an optional implementation, the sending unit 203 is specifically configured to send both dying gasp packets to the wireless access point by using a management frame queue and a data frame queue.

[0112] In an optional implementation, the dying gasp packet comprises a management frame packet.

[0113] The processing unit 201 is specifically configured to determine a value of a preset field in a management frame packet, and determine the management frame packet as a dying gasp packet.

[0114] The processing unit 201 is further configured to clear the management frame packets to be transmitted in the management frame queue after the detection unit 202 detects the power-off signal, and add the management frame packets to the cleared management frame queue.

[0115] The sending unit 203 is specifically configured to send the dying gasp packet to the wireless access point by using a management frame queue to which the management frame packet is added.

[0116] In an optional implementation, the dying gasp packet comprises a data frame packet.

[0117] The sending unit 203 is specifically configured to add the data frame packet to a data frame queue, and transmit the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet has been added.

[0118] In an optional implementation, the terminal device further includes a determining unit 204.

[0119] The determining unit 204 is configured to determine priorities corresponding to the multiple data frame queues before the detecting unit 202 detects the power-off signal, and determine a target data frame queue based on the priorities.

[0120] The sending unit 203 is specifically configured to add the data frame packet to a target data frame queue, and transmit the dying gasp packet to the wireless access point by using the target data frame queue to which the data frame packet has been added.

[0121] In an optional implementation, the terminal device pre-configures the dedicated queue.

[0122] The sending unit 203 is specifically configured to send dying gasp packets to the wireless access points by using a dedicated queue.

[0123] In an optional implementation, a power off signal is generated when an input voltage corresponding to the terminal device is below a preset threshold.

[0124] In an optional implementation, a transmission channel exists between the terminal device and the wireless access point.

[0125] The sending unit 203 is further configured to increase a clear channel assessment threshold corresponding to a transmission channel, and send the dying gasp packet via the transmission channel.

[0126] FIG. 3 is a schematic diagram of the structure of an access point device according to an embodiment of the present application. As shown in FIG. 3, the access point device includes: a receiving unit 301 configured to receive a dying gasp packet transmitted by a terminal device; and a determining unit 302 configured to determine a power-off state of the terminal device based on the dying gasp packet.

[0127] 4 is a schematic diagram of the structure of a terminal device 400 according to an embodiment of the present application. The terminal device 400 includes: a processor 401, a memory 402, and a communication interface 403.

[0128] The processor 401, the memory 402, and the communication interface 403 are interconnected by using a bus. The bus may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus may be classified into an address bus, a data bus, a control bus, etc. For ease of representation, the representation in FIG. 4 uses only one thick line, but this does not mean that there is only one bus or only one type of bus.

[0129] The memory 402 may include volatile memory, such as random access memory (RAM). Alternatively, the memory may include non-volatile memory, such as flash memory, a hard disk drive (HDD), or a solid-state drive (SSD). Alternatively, the memory 402 may include a combination of the above types of memory.

[0130] The processor 401 may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and a NP. The processor 401 may further include a hardware chip. The hardware chip may be an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0131] The communication interface 403 may be a wired communication interface, a wireless communication interface, or a combination thereof. The wired communication interface may be, for example, an Ethernet interface. The Ethernet interface may be an optical interface, an electrical interface, or a combination thereof. The wireless communication interface may be a WLAN interface, a cellular network communication interface, or a combination thereof.

[0132] The processor 401 is configured to operate computer programs or instructions in the memory 402 to execute the steps performed by a terminal device in any one of the possible implementations of the embodiments shown in FIG.

[0133] 5 is a schematic diagram of the structure of an access point device 500 according to an embodiment of the present application. The access point device 500 includes a processor 501, a memory 502, and a communication interface 503.

[0134] The processor 501, the memory 502, and the communication interface 503 are interconnected by using a bus. The bus may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus may be classified into an address bus, a data bus, a control bus, etc. For ease of representation, the representation in FIG. 5 uses only one thick line, but this does not mean that there is only one bus or only one type of bus.

[0135] The memory 502 may include volatile memory, such as random access memory (RAM). Alternatively, the memory may include non-volatile memory, such as flash memory, a hard disk drive (HDD), or a solid-state drive (SSD). Alternatively, the memory 502 may include a combination of the above types of memory.

[0136] The processor 501 may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and a NP. The processor 501 may further include a hardware chip. The hardware chip may be an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0137] The communication interface 503 may be a wired communication interface, a wireless communication interface, or a combination thereof. The wired communication interface may be, for example, an Ethernet interface. The Ethernet interface may be an optical interface, an electrical interface, or a combination thereof. The wireless communication interface may be a WLAN interface, a cellular network communication interface, or a combination thereof.

[0138] The processor 501 is configured to operate computer programs or instructions in the memory 502 to execute the steps performed by the access point device in any one of the possible implementation forms of the embodiments shown in FIG.

[0139] An embodiment of the present application further provides a power-off alarm system, which includes a terminal device and an access point device, the terminal device being the terminal device described in the embodiment shown in Figure 2, and the access point device being the access point device described in the embodiment shown in Figure 3.

[0140] An embodiment of the present application further provides a chip or chip system. The chip or chip system includes at least one processor and a communication interface. The communication interface and the at least one processor are interconnected through a line. The at least one processor is configured to run a computer program or instruction to execute the power-off alarm method described in any one of the possible implementation forms of the embodiment shown in FIG. 1.

[0141] The communication interface in a chip may be an input / output interface, a pin, or a circuit.

[0142] In a possible implementation, the chip or chip system described above in this application further includes at least one memory in which instructions are stored. The memory may be a storage unit internal to the chip, such as a register or cache, or may be a storage unit of the chip (e.g., a read-only memory or a random access memory).

[0143] An embodiment of the present application further provides a computer storage medium configured to store computer software instructions for use by a terminal device, including a program designed for the terminal device.

[0144] An embodiment of the present application further provides a computer storage medium configured to store computer software instructions for use by an access point device, including a program designed for the access point device.

[0145] An embodiment of the present application further provides a computer program product, which includes computer software instructions, which can be loaded by using a processor to implement procedures in the power-off alarm method.

[0146] All or part of the above-described embodiments may be implemented by using software, hardware, firmware, or any combination thereof. If software is used to implement the embodiments, all or part of the embodiments may be implemented in the form of a computer program product.

[0147] For the purpose of simple and easy description, the detailed work processes of the above-mentioned systems, devices and units can be clearly understood by those skilled in the art by referring to the corresponding processes in the above-mentioned method embodiments, and the details will not be described again in this specification.

[0148] In some embodiments provided in the present application, it should be understood that the disclosed system, device, and method can be implemented in other ways. For example, the embodiment of the device described is merely an example. For example, the division into units is only a logical functional division, and there may be other divisions in the actual implementation form. For example, multiple units or components may be combined or integrated into another system, or some functions may be ignored or not performed. In addition, the shown or described mutual coupling or direct coupling or communication connection may be implemented through some interfaces. Indirect coupling or communication connection between devices or units may be implemented in an electrical, mechanical, or other form.

[0149] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one location or distributed across multiple network units. Some or all of the units may be selected based on the actual requirements for achieving the objectives of the solutions of the embodiments.

[0150] In addition, the functional units in the embodiments of the present application may be integrated into one processing unit, each of the units may exist physically alone, or two or more units may be integrated into one unit. The integrated unit may be implemented in the form of hardware or a software functional unit.

[0151] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on such understanding, the technical solution in the present application is essential, but the part contributing to the prior art, or all or part of the technical solution may also be implemented in the form of a software product. The computer software product is stored in a storage medium and includes some instructions for instructing a computer device (which may be a computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the embodiments of the present application. The aforementioned storage medium includes any medium that can store program code, such as a USB flash device, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc. Other possible items [Item 1] constructing a dying gasp packet by a terminal device after being powered on, where the dying gasp packet is used to indicate that the terminal device is in a powered off state; and transmitting, by the terminal device, the dying gasp packet to a wireless access point after detecting a power-off signal. A power-off alarm method comprising: [Item 2] said step of transmitting said dying gasp packet to a wireless access point by said terminal device further comprising: transmitting, by the terminal device, both dying gasp packets to the wireless access point using a management frame queue and a data frame queue. The method according to item 1. [Item 3] The dying gasp packet is a management frame packet, and the step of configuring a dying gasp packet by a terminal device comprises: determining, by the terminal device, a value of a preset field in the management frame packet, and determining the management frame packet as the dying gasp packet; the method further comprising: clearing, by the terminal device, management frame packets to be transmitted in the management frame queue after detecting the power-off signal; and adding, by the terminal device, the management frame packets to the cleared management frame queue; said step of transmitting said dying gasp packet to a wireless access point by said terminal device further comprising: transmitting the dying gasp packet to the wireless access point by the terminal device using the management frame queue to which the management frame packet has been added. The method according to item 2. [Item 4] the dying gasp packet being a data frame packet, the step of transmitting the dying gasp packet by the terminal device to a wireless access point, adding the data frame packet to the data frame queue by the terminal device, and transmitting the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet has been added. The method according to item 2 or 3. [Item 5] The method comprising: determining, by the terminal device, prior to detecting the power-off signal, prior to the power-off signal, prior to the power-off signal; determining, by the terminal device, a target data frame queue based on the priority; adding the data frame packet to the data frame queue by the terminal device, and transmitting the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet has been added, adding the data frame packet to the target data frame queue by the terminal device, and transmitting the dying gasp packet to the wireless access point by using the target data frame queue to which the data frame packet has been added. The method according to item 4. [Item 6] the step of the terminal device pre-configuring a dedicated queue and transmitting the dying gasp packet by the terminal device to a wireless access point, transmitting the dying gasp packet to the wireless access point by the terminal device using the dedicated queue. The method according to item 1. [Item 7] The method further comprises: the power-off signal being generated when an input voltage corresponding to the terminal device is below a preset threshold. 7. The method according to any one of items 1 to 6. [Item 8] A transmission channel exists between the terminal device and the wireless access point, and the method comprises: increasing, by the terminal device, a clear channel assessment threshold corresponding to the transmission channel; and transmitting, by the terminal device, the dying gasp packet over the transmission channel. 8. The method of any one of items 1 to 7, further comprising: [Item 9] receiving, by the wireless access point, a dying gasp packet transmitted by the terminal device; and determining, by the wireless access point, a power-off state of the terminal device based on the dying gasp packet; A power-off alarm method comprising: [Item 10] a processing unit configured to pre-configure a dying gasp packet after the terminal device is powered on, where the dying gasp packet is used to indicate that the terminal is in a powered off state; A detection unit configured to detect a power-off signal; and a transmitting unit configured to transmit the dying gasp packet to a wireless access point after the power off signal is detected. A terminal device comprising: [Item 11] Item 11. The terminal device according to item 10, wherein the sending unit is specifically configured to send both dying gasp packets to the wireless access point by using a management frame queue and a data frame queue. [Item 12] the dying gasp packet comprises a management frame packet, The processing unit is specifically configured to determine a value of a preset field in the management frame packet, and determine the management frame packet as the dying gasp packet; The processing unit is further configured to clear a management frame packet to be transmitted in the management frame queue after the detection unit detects the power-off signal, and add the management frame packet to the cleared management frame queue by the terminal device; The sending unit is specifically configured to send the dying gasp packet to the wireless access point by using the management frame queue to which the management frame packet is added. Item 12. A terminal device according to item 11. [Item 13] the dying gasp packet comprises a data frame packet, The sending unit is particularly configured to add the data frame packet to the data frame queue, and transmit the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet has been added. Item 13. A terminal device according to item 11 or 12. [Item 14] the terminal device further comprises a determining unit; The determining unit is configured to determine priorities corresponding to a plurality of data frame queues before the detecting unit detects the power-off signal, and determine a target data frame queue based on the priorities; The sending unit is particularly configured to add the data frame packet to the target data frame queue, and transmit the dying gasp packet to the wireless access point by using the target data frame queue to which the data frame packet has been added. Item 14. A terminal device according to item 13. [Item 15] the terminal device pre-configuring a dedicated queue; 11. The terminal device according to item 10, wherein the transmitting unit is specifically configured to transmit the dying gasp packet to the wireless access point by using the dedicated queue. [Item 16] the power-off signal is generated when an input voltage corresponding to the terminal is below a preset threshold; A terminal device according to any one of items 10 to 15. [Item 17] a transmission channel exists between the terminal and the wireless access point; The transmitting unit is further configured to increase a clear channel assessment threshold corresponding to the transmission channel and transmit the dying gasp packet via the transmission channel. A terminal device according to any one of items 10 to 16. [Item 18] a receiving unit configured to receive a dying gasp packet transmitted by a terminal device; and a determining unit configured to determine a power-off state of the terminal device based on the dying gasp packet; An access point device comprising: [Item 19] A terminal device comprising a processor and a memory, the processor coupled to the memory, the memory storing program instructions, and the program instructions stored in the memory, when executed by the processor, implementing the method according to any one of items 1 to 8. [Item 20] 10. An access point device comprising a processor and a memory, the processor coupled to the memory, the memory storing program instructions, and the program instructions stored in the memory, when executed by the processor, implementing the method described in item 9. [Item 21] A power-off alarm system comprising a terminal device and an access point device, the terminal device executing the method according to any one of items 1 to 8, and the access point device executing the method according to item 9. [Item 22] 10. A computer-readable storage medium comprising a program, the program enabling the computer to perform the method according to any one of items 1 to 9 when the program runs on a computer.

Claims

1. A power off alarm method, comprising: constructing a dying gasp packet by the terminal device after being powered on, where the dying gasp packet is used to indicate that the terminal device is in a powered off state; and transmitting the dying gasp packet to a wireless access point by the terminal device after detecting a power-off signal. A method comprising:

2. said step of transmitting said dying gasp packet by said terminal device to a wireless access point, transmitting, by the terminal device, both dying gasp packets to the wireless access point using a management frame queue and a data frame queue. The method of claim 1.

3. The dying gasp packet is a management frame packet, and the step of configuring the dying gasp packet by the terminal device includes: determining, by the terminal device, a value of a preset field in the management frame packet, and determining the management frame packet as the dying gasp packet; the method further comprising: clearing, by the terminal device, management frame packets to be transmitted in the management frame queue after detecting the power-off signal; and adding, by the terminal device, the management frame packets to the cleared management frame queue; said step of transmitting said dying gasp packet by said terminal device to a wireless access point, transmitting the dying gasp packet to the wireless access point by the terminal device using the management frame queue to which the management frame packet has been added. The method of claim 2.

4. the dying gasp packet being a data frame packet, the step of transmitting the dying gasp packet by the terminal device to a wireless access point comprising: adding the data frame packet to the data frame queue by the terminal device, and transmitting the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet has been added. The method according to claim 2 or 3.

5. The method comprising: determining, by the terminal device, prior to detecting the power-off signal, prior to the power-off signal, prior to the power-off signal; determining, by the terminal device, a target data frame queue based on the priority; the step of adding the data frame packet to the data frame queue by the terminal device and transmitting the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet has been added, adding the data frame packet to the target data frame queue by the terminal device, and transmitting the dying gasp packet to the wireless access point by using the target data frame queue to which the data frame packet has been added. The method according to claim 4.

6. The step of the terminal device pre-configuring a dedicated queue and transmitting the dying gasp packet by the terminal device to a wireless access point comprises: transmitting the dying gasp packet to the wireless access point by the terminal device using the dedicated queue. The method of claim 1.

7. The power-off signal is generated when an input voltage corresponding to the terminal device is below a preset threshold.

7. The method according to any one of claims 1 to 3 or 5 to 6.

8. A transmission channel exists between the terminal device and the wireless access point, and the method includes: increasing, by the terminal device, a clear channel assessment threshold corresponding to the transmission channel; and transmitting the dying gasp packet via the transmission channel by the terminal device.

7. The method of any one of claims 1 to 3 or 5 to 6, further comprising:

9. The method of claim 1, wherein the dying gasp packet is preassembled before the power off signal is detected.

10. A power off alarm method, comprising: receiving, by a wireless access point, a dying gasp packet transmitted by a terminal device, the dying gasp packet transmitted by the terminal device including a management frame packet and a data frame packet; and determining, by the wireless access point, a power-off state of the terminal device based on the dying gasp packet; A method comprising:

11. A terminal device, comprising: a processing unit configured to pre-configure a dying gasp packet after the terminal device is powered on, where the dying gasp packet is used to indicate that the terminal device is in a powered off state; A detection unit configured to detect a power-off signal; and a transmitting unit configured to transmit the dying gasp packet to a wireless access point after the power-off signal is detected. A terminal device comprising:

12. The terminal device according to claim 11, wherein the sending unit is specifically configured to send both dying gasp packets to the wireless access point by using a management frame queue and a data frame queue.

13. the dying gasp packet comprises a management frame packet, The processing unit is specifically configured to determine a value of a preset field in the management frame packet, and determine the management frame packet as the dying gasp packet; the processing unit is further configured to clear a management frame packet to be transmitted in the management frame queue after the detection unit detects the power-off signal, and add the management frame packet to the cleared management frame queue; The sending unit is specifically configured to send the dying gasp packet to the wireless access point by using the management frame queue to which the management frame packet is added. A terminal device according to claim 12.

14. the dying gasp packet comprises a data frame packet, The sending unit is particularly configured to add the data frame packet to the data frame queue, and transmit the dying gasp packet to the wireless access point by using the data frame queue to which the data frame packet has been added. A terminal device according to claim 12 or 13.

15. the terminal device further comprises a determining unit; The determining unit is configured to determine priorities corresponding to a plurality of data frame queues before the detecting unit detects the power-off signal, and determine a target data frame queue based on the priorities; The sending unit is particularly configured to add the data frame packet to the target data frame queue, and transmit the dying gasp packet to the wireless access point by using the target data frame queue to which the data frame packet has been added. A terminal device according to claim 14.

16. the terminal device pre-configuring a dedicated queue; The terminal device according to claim 11, wherein the sending unit is specifically configured to send the dying gasp packet to the wireless access point by using the dedicated queue.

17. The power-off signal is generated when an input voltage corresponding to the terminal device is below a preset threshold. A terminal device according to any one of claims 11 to 13 or 15 to 16.

18. a transmission channel exists between the terminal device and the wireless access point; The transmitting unit is further configured to increase a clear channel assessment threshold corresponding to the transmission channel and transmit the dying gasp packet via the transmission channel. A terminal device according to any one of claims 11 to 13 or 15 to 17.

19. A terminal device according to claim 11, wherein the dying gasp packet is preassembled before the power off signal is detected.

20. A receiving unit configured to receive a dying gasp packet transmitted by a terminal device, the dying gasp packet transmitted by the terminal device including a management frame packet and a data frame packet; and A determining unit configured to determine a power-off state of the terminal device based on the dying gasp packet. An access point device comprising:

21. A terminal device comprising a processor and a memory, the processor coupled to the memory, the memory storing program instructions, the program instructions stored in the memory being executed by the processor to implement the method of any one of claims 1 to 9.

22. 11. An access point device comprising a processor and a memory, the processor coupled to the memory, the memory storing program instructions, the program instructions stored in the memory being executed by the processor to implement the method of claim 10.

23. A power off alarm system comprising a terminal device and an access point device, said terminal device executing the method according to any one of claims 1 to 9 and said access point device executing the method according to claim 10.

24. A computer program product for causing a computer to carry out the method according to any one of claims 1 to 10.

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