CN109691191B

CN109691191B - Clock synchronization method and equipment

Info

Publication number: CN109691191B
Application number: CN201780056194.9A
Authority: CN
Inventors: 杜振国; 丁志明; 方平; 杨云松
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2016-09-14
Filing date: 2017-07-25
Publication date: 2020-11-17
Anticipated expiration: 2037-07-25
Also published as: WO2018049924A1; CN109691191A

Abstract

The embodiment of the invention discloses a clock synchronization method and equipment, relates to the technical field of communication, and can solve the problem that a synchronization frame cannot be normally transmitted due to the fact that the information carried in the synchronization frame sent to an STA by an AP is large and the duration of a WUR awakening window is limited. The specific scheme is as follows: the AP sends at least one WUR frame to the STA at intervals of first time, each WUR frame in the at least one WUR frame comprises frame type information, the frame type information is used for indicating that the WUR frame is a synchronous frame, the first time is less than critical time and is more than interval time of a WUR awakening window, and the critical time is time required for the STA and the AP to generate clock drift so that the WUR awakening window is completely staggered with the WUR awakening window of the STA predicted by the AP; the AP sets the TSF clock sequence of the AP to a first predefined value when transmitting at least one WUR frame. The method and the device are used in the process of clock synchronization of the AP and the STA.

Description

Clock synchronization method and equipment

The present application claims priority of chinese patent application with application number CN201610826663.8, entitled "a method and apparatus for clock synchronization" filed on 14/9/2016 and chinese patent application with application number cn201710221945.x, entitled "a method and apparatus for clock synchronization" filed on 6/4/2017, which are all incorporated herein by reference.

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method and an apparatus for clock synchronization.

Background

A Station (STA) may perform data communication with an Access Point (AP) through a Wireless FIdelity (WiFi) network. In the above communication process, the communication module of the STA receives data sent by the AP, and if the communication module in the STA is in an active state for a long time, that is, the communication module is in an active state regardless of whether data communication is performed, there is a problem that power consumption of the STA is large.

In order to reduce the Power consumption of the STA, a communication module in the STA is in a sleep mode, and a Low Power (LP) Wake-up Radio (WUR) may be added to the STA. Before sending data to a communication module of the STA, the AP can send a wakeup frame in a WUR format to a LP-WUR in the STA; after receiving the wakeup frame, the LP-WUR may send a wakeup signal to the communication module in the STA, activate the communication module in the sleep mode, and enable the communication module to receive data from the AP. However, if the LP-WUR in the STA is active for a long time, there is still a problem that the STA consumes much power. The communication module may be a WiFi module or other communication modules, such as a Long Term Evolution (LTE) communication module.

To further reduce power consumption of the STA, periodic awake windows may be set for the LP-WURs, controlling the LP-WURs to be in an active state during each awake window and to be in a sleep state at times other than during the awake window. Thus, if the AP sends a wakeup frame to the LP-WUR at a time corresponding to the STA's LP-WUR wakeup window, the LP-WUR can receive the wakeup frame. However, due to the jitter of the device crystal, the clocks of both the STA and the AP may drift; thus, after a certain time, the clocks of the STA and the AP may not be consistent, which may cause the AP to deviate the expected LP-WUR wake-up window of the STA from the time of the determined LP-WUR wake-up window of the STA, or even completely stagger the two wake-up windows. If the two awake windows are completely staggered, the LP-WUR will not receive the awake frame sent by the AP.

In order to avoid the problem that the LP-WUR cannot receive the wakeup frame sent by the AP due to clock drift of the STA and the AP, the AP can periodically send a WUR format Synchronization frame carrying part or all bits of a Timing Synchronization Function (TSF) clock sequence of the AP to the STA, the TSF clock sequence of the AP is used for indicating a current clock of the AP, and the STA can update the TSF clock sequence of the STA according to the received TSF clock sequence to realize clock Synchronization of the AP and the STA.

However, there are problems in that: the TSF clock sequence is long (generally 64bits), and the overhead of carrying the TSF clock sequence in periodic transmission is large.

Disclosure of Invention

Embodiments of the present invention provide a clock synchronization method and device, so as to solve the problem that in the process of implementing clock synchronization between an AP and a WUR in an STA, since a TSF clock sequence of the AP carried in a synchronization frame sent to the STA by the AP is long, overhead of periodically transmitting the synchronization frame carrying the TSF clock sequence is large.

In a first aspect, an embodiment of the present invention provides a clock synchronization method, where the clock synchronization method includes: the method comprises the steps that an AP sends at least one WUR frame to the STA once in a WUR awakening window of the STA predicted by the AP every other first preset time, wherein each WUR frame in the at least one WUR frame comprises frame type information, and the frame type information is used for indicating that the WUR frame is a synchronization frame; the AP sets a WUR clock sequence of the AP to a first predefined value when transmitting the at least one synch frame.

In the scheme, the moment when the AP sends at least one synchronization frame is located in the WUR awakening window of the STA predicted by the AP, so that the AP can be ensured to send at least one synchronization frame in the WUR awakening window of the STA predicted by the AP every time. Moreover, since the WUR frame sent by the AP to the STA carries only frame type information indicating that the WUR frame is a sync frame, and does not need to carry specific sync time information (e.g., all (64bits) or a part of bits of a time sequence of TSF), the frame type information is generally one or two bits in the WUR frame, which does not bring large overhead even if the sync frame is periodically transmitted, and is sufficient to ensure normal transmission of the sync frame even if the duration of the WUR wake-up window is limited.

In one possible implementation, the first predetermined time is less than a time (hereinafter referred to as a critical time) required for the STA and the AP to completely stagger the WUR wake-up window of the STA from the WUR wake-up window of the STA expected by the AP due to clock drift. Since the first predetermined time is less than the critical time, if the AP sends at least one sync frame to the STA every first predetermined time, it can be guaranteed that the wake-up window of the at least one sync frame sent by the AP is not completely staggered from the WUR wake-up window of the STA, and thus it can be guaranteed that the STA can receive the at least one sync frame in its WUR wake-up window.

In a possible implementation manner, the WUR Frame may include a WUR preamble, a Medium Access Control (MAC) header, a Frame entity (Frame Body), a Frame Check Sequence (FCS), and other parts. The above frame type information may be included in different portions of the WUR frame. Frame type information may be included in the WUR preamble as each WUR frame; alternatively, the MAC header of each WUR frame may contain frame type information. The frame type information may be contained in a frame control field in the MAC header, or the frame type information may be contained in a reception address field in the MAC header.

In a possible implementation manner, the method for the AP to send at least one synchronization frame to the STA may include: the AP sends a synchronization frame to the STA in a WUR wake-up window of the STA predicted by the AP every second preset time. Wherein the AP may transmit at least one sync frame to the STA in a WUR wake-up window of the STA expected by each AP, and each of the at least one sync frame is transmitted at a second predetermined time interval by interval; thus, the STA can sequentially receive at least one synchronization frame during a WUR wakeup window.

In a possible implementation manner, the method that the AP sets the WUR clock sequence of the AP to the first predefined value when transmitting at least one WUR frame may include: the AP sets a WUR clock sequence of the AP to a first predefined value when transmitting a first of the at least one synch frame to the STA. In this implementation, the AP only executes once "setting the WUR clock sequence of the AP to the first predefined value" in a WUR wakeup window, which can reduce the occupation of a Central Processing Unit (CPU) of the AP by the AP that frequently performs clock synchronization.

In one possible implementation, each synchronization frame in the at least one WUR frame is sent by the AP to the STA every second predetermined time in a WUR wake-up window of the STA expected by the AP; each synchronization frame in at least one synchronization frame also contains the sequence number of the synchronization frame, and the sequence number of the synchronization frame is used for indicating the sequence of the synchronization frame in at least one synchronization frame according to the sending sequence of each synchronization frame in at least one synchronization frame.

In one possible implementation, the "AP sets the WUR clock sequence of the AP to a first predefined value when transmitting the at least one synch frame" may include: the AP sets a WUR clock sequence of the AP to a first predefined value at a start time or an end time of transmitting a first of the at least one synch frame to the STA.

In one possible implementation, the AP may obtain the interval time of the WUR awake window of the STA and the duration of the WUR awake window of the STA from the STA before transmitting the synchronization frame to the STA. Specifically, before the AP sends at least one WUR frame to the STA once in the WUR awake window of the STA expected by the AP every first predetermined time, the method of the embodiment of the present invention may further include: the AP receives first time information sent by the STA, wherein the first time information comprises the interval time of a WUR awakening window of the STA and the duration of the WUR awakening window of the STA; the AP can determine a first preset time according to the duration of the WUR awakening window of the STA, and then determine the WUR awakening window of the STA predicted by the AP according to the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA. After the AP determines the first preset time, the AP can send at least one WUR frame to the STA every first preset time so as to realize the clock synchronization of the AP and the STA.

In a possible implementation manner, the AP may notify all STAs in a Basic Service Set (BSS) of an interval time of a first WUR wake-up window and a duration of the first WUR wake-up window in a broadcast manner, so that all STAs in the BSS receive a synchronization frame or a wake-up frame in the first WUR wake-up window. Specifically, before the AP sends at least one WUR frame to the STA once in the WUR awake window of the STA expected by the AP every first predetermined time, the method of the embodiment of the present invention may further include: the AP broadcasts second time information to the STA, wherein the second time information comprises the interval time of a first WUR awakening window and the duration of the first WUR awakening window; the first WUR awake window is a WUR awake window of the STA expected by the AP. It is conceivable that, when the AP and the STAs perform clock synchronization respectively, the AP needs to store the interval time of the WUR awake window of each STA of the STAs and the duration of the WUR awake window of each STA of the STAs, and occupies the memory space of the AP; the AP also needs to send a synchronization frame to the corresponding STA in the WUR wake-up window of each STA among the multiple STAs, and too many synchronization frames sent by the AP occupy port resources of the AP, which affects normal transmission of other services of the AP. In this scheme, the AP may broadcast a first WUR awake window (broadcasting the interval time of the first WUR awake window and the duration of the first WUR awake window) to the STAs, and broadcast a synchronization frame to all STAs in a BSS in the first WUR awake window. Therefore, the AP only needs to save the interval time of the first WUR awakening window and the duration of the first WUR awakening window, the occupation of the AP memory can be reduced, and the port resource of the AP can be released by adopting a broadcasting mode.

In one possible implementation, the AP and the STA belong to the same BSS; the method for the AP to send at least one synchronization frame to the STA once in a WUR wakeup window of the STA predicted by the AP every first preset time can comprise the following steps: the AP broadcasts at least one synchronous frame once to the STA in a wake-up window of the STA predicted by the AP every first preset time, and each synchronous frame in the at least one synchronous frame also comprises an identification of the BSS. It is conceivable that, since each synchronization frame in the at least one synchronization frame further includes an identifier of a BSS, after receiving any one of the at least one synchronization frame, the STA may compare the identifier of the BSS included in the synchronization frame with the identifier of the BSS to which the STA belongs to determine whether the STA needs to perform clock synchronization. For example, the BSS Identifier may be an Identifier (ID) of the BSS, or the BSS Identifier may be a Color value (Color) previously allocated to the BSS. In the embodiment of the present invention, different colors may be allocated to different BSSs in advance, so as to uniquely identify corresponding BSSs.

In a possible implementation manner, before the AP sends at least one synchronization frame to the STA once in a WUR awake window of the STA expected by the AP every first predetermined time, the method of the embodiment of the present invention may further include: the AP transmits the length of each of the at least one synchronization frame and the second predetermined time to the STA. It is conceivable that due to the unreliability of binary On-Off Keying (OOK) modulation, the STA may not receive each of the at least one synchronization frame sent by the AP, for example, the STA may not receive the first synchronization frame of the at least one synchronization frame sent by the AP. In the above implementation, the AP does not perform "setting the WUR clock sequence of the AP to the first predefined value" each time a sync frame is transmitted to the STA, but performs "setting the WUR clock sequence of the AP to the first predefined value" only when the first sync frame of the at least one sync frame is transmitted to the STA; however, if the STA does not receive the first sync frame of the at least one sync frame transmitted by the AP, the STA cannot set the WUR clock sequence of the STA in time. However, since the sequence number of the synchronization frame may be included in each synchronization frame transmitted from the AP to the STA, even if the STA cannot receive the first synchronization frame, the difference between the time when the AP transmits the arrival synchronization frame and the time when the AP transmits the first synchronization frame may be calculated based on the length of the synchronization frame, the second predetermined time, and the sequence number of the received synchronization frame (simply referred to as the arrival synchronization frame), and then the WUR clock sequence of the STA may be set based on the difference and the first synchronization frame, thereby achieving clock synchronization between the STA and the AP.

In a possible implementation manner, the first predefined value may be preconfigured, and in this embodiment of the present invention, the same first predefined value may be preconfigured for the STA and the AP. Alternatively, the AP may interact with the STA to determine the first predefined value. For example, the AP may send the STA a first predefined value before performing "the AP sends the STA at least one synchronization frame every first predetermined time in a WUR wake-up window of said STA expected by the AP". The embodiment of the present invention does not limit the method for determining the first predefined value.

In a second aspect, an embodiment of the present invention provides a clock synchronization method, where the clock synchronization method includes: the method comprises the steps that an STA receives at least one WUR frame sent by an AP in a WUR awakening window of the STA, wherein each WUR frame in the at least one WUR frame comprises frame type information, the frame type information is used for indicating that the WUR frame is a synchronization frame, and the at least one WUR frame is sent in the WUR awakening window of the STA expected by the AP every first preset time; the STA sets a WUR clock sequence of the STA according to the received synchronization frame and a first predefined value.

In the scheme, the moment when the AP sends at least one synchronization frame is located in the WUR awakening window of the STA predicted by the AP, so that the AP can be ensured to send at least one synchronization frame in the WUR awakening window of the STA predicted by the AP every time. In addition, since the STA receives the WUR frame sent by the AP and only carries the frame type information indicating that the WUR frame is a synchronization frame, the frame type information is generally one or two bits in the WUR frame, even if the synchronization frame is periodically transmitted, a large overhead is not brought, and even if the duration of the WUR wake-up window is limited, the normal transmission of the synchronization frame can be sufficiently ensured.

In one possible implementation, the first predetermined time is less than a time (i.e., a critical time) required for the STA and the AP to clock drift such that the WUR wake-up window of the STA is completely staggered from the WUR wake-up window of the STA expected by the AP. Since the first predetermined time is less than the critical time, if the AP sends at least one sync frame to the STA every first time, it can be guaranteed that the wake-up window of the at least one sync frame sent by the AP is not completely staggered from the WUR wake-up window of the STA, and thus it can be guaranteed that the STA can receive the at least one sync frame in its WUR wake-up window.

In a possible implementation manner, the specific content of the frame type information and the sending manner of each synchronization frame in the at least one synchronization frame may refer to the detailed description in the implementation manner corresponding to the first aspect, and are not described herein again.

In one possible implementation, the STA setting a WUR clock sequence of the STA according to the received synchronization frame and a first predefined value includes: if the STA receives a synchronization frame with the sequence number k in a WUR awakening window of the STA, the STA sets a WUR clock sequence of the STA according to the sequence number k, the length of each synchronization frame in at least one synchronization frame, second preset time and a first predefined value; wherein k is more than 0 and less than or equal to n, and n is the number of synchronous frames in at least one synchronous frame. Setting the TSF clock sequence of the AP to a first predefined value since the AP only transmits a first synchronization frame of the at least one synchronization frame to the STA; therefore, the STA may also perform "set the WUR clock sequence of the STA" only once according to the received synchronization frame and the first predefined value.

In a possible implementation manner, the synchronization frame between the AP and the STA is transmitted after OOK modulation, and unreliability of OOK modulation may cause that the STA may not necessarily receive all the synchronization frames sent by the AP; and, since the AP sets the WUR clock sequence of the AP to a first predefined value only when transmitting a first of the at least one sync frame to the STA; therefore, even if the STA cannot receive the first synchronization frame transmitted by the AP in the WUR awake window, the STA can synchronize the clocks of the AP and the STA according to the synchronization frame with the sequence number k received in the WUR awake window of the STA. Specifically, the method for the STA to set the WUR clock sequence of the STA according to the received synchronization frame and the first predefined value may include: if the STA receives a synchronization frame with the sequence number of k in the WUR wake-up window of the STA, the WUR clock sequence of the STA is set to C + kXL + (k-1). times.T₀Or, the WUR clock sequence of the STA is set to C + (k-1). times.L + (k-1). times.T₀. Where k is {1, 2, 3.... times, n }, C is used to represent a first predefined value, L is used to represent a time-domain length of each synchronization frame, and T is used to represent a time-domain length of each synchronization frame₀For indicating the second predetermined time.

Wherein when the AP sets the WUR clock sequence of the AP to a first predefined value C at a start time of transmitting a first sync frame of the at least one sync frame to the STA, since k × L + (k-1) xT₀Can be used to indicate the time difference between the AP transmitting the sync frame with sequence number k and the AP transmitting the sync frame with sequence number 1, and since the AP only transmits the first sync frame (i.e., sync frame with sequence number 1) to the STA at the start of the WUR wake-up window, the WUR clock sequence of the AP is set to a first predefined value C; thus, from the moment the AP sets the AP's WUR clock sequence to the first predefined value C (i.e., the AP sends at least one peer to the STA)The start time of the first sync frame in the step frames) through k × L + (k-1) × T₀The WUR clock sequence of the AP may then be C + kXL + (k-1). times.T₀. At this time, the STA sets its WUR clock sequence to C + kXL + (k-1). times.T₀Then clock synchronization of AP and STA can be achieved.

When the AP sets the WUR clock sequence of the AP to a first predefined value C at the end time of transmitting the first of the at least one sync frame to the STA, since (k-1). times.L + (k-1). times.T₀For indicating a time difference between the AP transmitting the sync frame with sequence number k and the AP transmitting the sync frame with sequence number 1, and setting the WUR clock sequence of the AP to a first predefined value C since the AP transmits the first sync frame (i.e., the sync frame with sequence number 1) to the STA only at the end time of the WUR wake-up window; therefore, starting from the time when the AP sets the WUR clock sequence of the AP to the first predefined value C (i.e., the end time when the AP transmits the first sync frame of the at least one sync frame to the STA), the (k-1). times.L + (k-1). times.T is passed₀The WUR clock sequence of the AP may be C + (k-1). times.L + (k-1). times.T₀. At this time, the STA sets its WUR clock sequence to C + (k-1). times.L + (k-1). times.T₀Then clock synchronization of AP and STA can be achieved.

In one possible implementation manner, it is assumed that the synchronization frame with sequence number k is the first synchronization frame received by the STA in the WUR wake-up window, that is, the STA does not receive other synchronization frames sent by the AP in the WUR wake-up window of the STA receiving the synchronization frame with sequence number k before receiving the synchronization frame with sequence number k. When receiving the synchronization frame with the sequence number k, the STA can receive the WUR awakening window of the STA of the synchronization frame with the sequence number k, so that the clock synchronization of the AP and the STA is realized; therefore, if the STA receives a synchronization frame with sequence number k + m in its WUR wake-up window, the STA may discard the synchronization frame with sequence number k + m, m {1, 2.

In this implementation, the STA does not need to perform clock synchronization each time a synchronization frame is received, and only once the STA receives the first synchronization frame in the WUR wakeup window, "set the WUR clock sequence in the STA", and discard the subsequent received synchronization frame, so that the occupation of the CPU of the STA by the STA that frequently performs clock synchronization can be reduced.

In a possible implementation manner, before the STA receives at least one WUR frame sent by the AP in a WUR wake-up window of the STA, the method of the embodiment of the present invention may further include: the STA sends first time information to the AP, wherein the first time information comprises the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA, so that the AP acquires the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA from the STA. The duration of the WUR awakening window of the STA is used for determining the first preset time, and the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA are used for determining the WUR awakening window of the STA predicted by the AP.

In one possible implementation, the STA may receive the interval time of the first WUR awake window and the duration of the first WUR awake window broadcast by the AP. Specifically, before the STA receives at least one WUR frame sent by the AP in a WUR awake window of the STA, the method of the embodiment of the present invention may further include: the STA receives second time information broadcasted by the AP, wherein the second time information comprises the interval time of a first WUR awakening window and the duration of the first WUR awakening window, and the first WUR awakening window is the WUR awakening window of the STA predicted by the AP; the STA sets a WUR awakening window of the STA according to the interval time of the first WUR awakening window and the duration of the first WUR awakening window; wherein the duration of the first WUR awake window is used to determine the first predetermined time. In this implementation, all STAs in a BSS may clock-synchronize with the AP in the same first WUR wake-up window.

In a possible implementation manner, if a STA does not receive a synchronization frame sent by an AP in the WUR awake windows of N consecutive STAs, the STA may adjust the duration of the WUR awake window of the STA according to a preset window extension rule until the STA receives the synchronization frame sent by the AP.

In a possible implementation manner, when the STA does not receive the synchronization frame sent by the AP in the WUR awake windows of N consecutive STAs, the STA extends the duration of the WUR awake window of the STA according to the preset window extension rule until the STA receives the synchronization frame sent by the AP, the method of the embodiment of the present invention may further include: and the STA restores the duration of the WUR awakening window of the STA to the duration of the WUR awakening window of the STA before adjustment.

In one possible implementation, the AP and the STA belong to the same basic service set BSS; the method for receiving, by the STA, at least one synchronization frame transmitted by the AP in a WUR wakeup window of the STA may include: the STA receives at least one synchronization frame broadcasted by the AP in a WUR awakening window of the STA, and each WUR frame in the at least one WUR frame further comprises an identifier of the BSS; it is conceivable that, since each synchronization frame in the at least one synchronization frame further includes an identifier of a BSS, after receiving any one of the at least one synchronization frame, the STA may compare the identifier of the BSS included in the synchronization frame with the identifier of the BSS to which the STA belongs to determine whether the STA needs to perform clock synchronization. For example, the identification of the BSS may be an identification ID of the BSS, or the identification of the BSS may be a Color value Color allocated to the BSS in advance. In the embodiment of the present invention, different colors may be allocated to different BSSs in advance, so as to uniquely identify corresponding BSSs.

In one possible implementation, the STA sets a WUR clock sequence of the STA according to the received synchronization frame and a first predefined value. Specifically, the method of the embodiment of the present invention may further include: and if the BSS indicated by the identification of the BSS is the same as the BSS to which the STA belongs, the STA sets a WUR clock sequence of the STA. It is conceivable that the clock synchronization is performed only when the WUR in the STA receives the WUR synchronization frame transmitted by the AP of the BSS to which it belongs.

In a possible implementation manner, the length and the second time of each synchronization frame are pre-configured in the STA; or, before the STA sets the WUR clock sequence of the STA after receiving the synchronization frame and the first predefined value, the method of the embodiment of the present invention may further include: the STA receives the length of each synchronization frame transmitted by the AP and a second predetermined time.

In a third aspect, an embodiment of the present invention provides an AP, where the AP may include: a sending unit and a setting unit. And the sending unit is used for sending at least one WUR frame to the STA once in a WUR awakening window of the STA predicted by the AP every first preset time, wherein each WUR frame in the at least one WUR frame comprises frame type information, and the frame type information is used for indicating that the WUR frame is a synchronization frame. A setting unit for setting the WUR clock sequence of the AP to a first predefined value when the transmitting unit transmits the at least one sync frame.

In one possible implementation, the first predetermined time is less than the time required for the STA and the AP to drift clocks such that the WUR wake-up window of the STA completely staggers from the WUR wake-up window of the STA expected by the AP.

In one possible implementation, the WUR preamble of each WUR frame contains frame type information; alternatively, the MAC header of each WUR frame contains frame type information, where the frame control field in the MAC header contains frame type information, or the receive address field in the MAC header contains frame type information.

In a possible implementation manner, the sending unit is specifically configured to: in a WUR awakening window of the STA predicted by the AP, sending a synchronization frame to the STA at intervals of second preset time; each synchronization frame in at least one synchronization frame also contains a sequence number of the synchronization frame, and the sequence number of the synchronization frame is used for indicating the sequence of the synchronization frame in at least one synchronization frame according to the sending sequence of each synchronization frame in at least one synchronization frame.

In a possible implementation manner, the setting unit is specifically configured to: the WUR clock sequence of the AP is set to a first predefined value at a start time or an end time when the transmitting unit transmits a first one of the at least one sync frame to the STA.

In one possible implementation, the AP may further include: and a receiving unit. And the receiving unit is used for receiving first time information sent by the STA before the sending unit sends at least one WUR frame to the STA in a WUR awakening window of the STA predicted by the AP every first preset time, wherein the first time information comprises the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA.

In one possible implementation, the AP may further include: a determination unit. And the determining unit is used for determining a first preset time according to the duration of the WUR awakening window of the STA received by the receiving unit, and determining the WUR awakening window of the STA predicted by the AP according to the interval time of the WUR awakening window of the STA received by the receiving unit and the duration of the WUR awakening window of the STA.

In a possible implementation manner, the sending unit is further configured to broadcast second time information to the STA before sending at least one WUR frame to the STA in a WUR wake-up window of the STA expected by the AP every first predetermined time, where the second time information includes an interval time of the first WUR wake-up window and a duration of the first WUR wake-up window; the first WUR awake window is the WUR awake window of the STA that the AP expects.

In one possible implementation, the AP and the STA belong to the same BSS. A sending unit, specifically configured to: the sending unit sends at least one synchronization frame to the STA once in an AP-expected wake-up window of the STA every first preset time, wherein each synchronization frame in the at least one synchronization frame also comprises an identification of the BSS.

In a possible implementation manner, the transmitting unit is further configured to transmit, to the STA, the length of each of the at least one synchronization frame and the second predetermined time before transmitting, to the STA, the at least one synchronization frame every first predetermined time in a WUR wake-up window of the STA expected by the AP.

In one possible implementation, the first predefined value is preconfigured. Or, the transmitting unit is further configured to transmit the first predefined value to the STA before transmitting at least one WUR frame to the STA in a WUR wake-up window of the STA expected by the AP every first predetermined time.

It should be noted that each functional unit of the third aspect and various possible implementations of the third aspect of the embodiment of the present invention is a logical partition performed on the AP in order to perform the clock synchronization method described in the first aspect and the various optional implementations of the first aspect. For detailed description and beneficial effect analysis of each functional unit of the third aspect and various possible implementations thereof, reference may be made to corresponding description and technical effects in the first aspect and various possible implementations thereof, which are not described herein again.

In a fourth aspect, an AP is provided, including: a processor, a memory, a bus, and a transceiver. The memory is for storing computer executable instructions, the processor is connected to the memory via the bus, and when the AP is running, the processor executes the computer executable instructions stored by the memory to cause the AP to perform the method for clock synchronization as in the first aspect and the various alternatives of the first aspect.

In a fifth aspect, there is provided a non-volatile storage medium having one or more program codes stored therein, which when executed by a processor of the AP in the fourth aspect, the AP performs the method for clock synchronization as in the first aspect and the various alternatives of the first aspect.

The processor in the fourth aspect may be an integration of functional units such as a setting unit and a determining unit in the third aspect and various possible implementations thereof, and the transceiver in the fourth aspect may be an integration of a transmitting unit and a receiving unit in the third aspect and various possible implementations thereof, so as to implement information interaction between the AP and other communication devices (e.g., STAs). The AP in the fourth aspect and the specific technical effect of the AP executing the program stored in the computer-readable storage medium of the fifth aspect and the related analysis process thereof may refer to the description of the related technical effect in the first aspect of the embodiment of the present invention or any implementation manner of the first aspect, and are not described herein again.

In a sixth aspect, an embodiment of the present invention provides an STA, where the STA may include: a receiving unit and a first setting unit. The receiving unit is used for receiving at least one WUR frame sent by the AP in a WUR wake-up window of the STA, wherein each WUR frame in the at least one WUR frame comprises frame type information, the frame type information is used for indicating that the WUR frame is a synchronization frame, and the at least one WUR frame is sent in the WUR wake-up window of the STA predicted by the AP every first preset time. And the first setting unit is used for setting the WUR clock sequence of the STA according to the synchronization frame received by the receiving unit and the first predefined value.

In a possible implementation manner, each synchronization frame in the at least one synchronization frame received by the receiving unit is sent by the AP to the STA every second predetermined time in a WUR wake-up window of the STA expected by the AP; each synchronization frame also contains the sequence number of the synchronization frame, and the sequence number of the synchronization frame is used for indicating the sequence of the synchronization frame in at least one synchronization frame according to the sending sequence of each synchronization frame in at least one synchronization frame.

In a possible implementation manner, the first setting unit is further configured to set a WUR clock sequence of the STA according to the sequence number k, a length of each of the at least one synchronization frame, a second predetermined time, and a first predefined value if the receiving unit receives the synchronization frame with the sequence number k in a WUR wake-up window of the STA; wherein k is more than 0 and less than or equal to n, and n is the number of synchronous frames in at least one synchronous frame.

In a possible implementation manner, the first setting unit is specifically configured to: if the receiving unit receives a synchronization frame with the sequence number k in the WUR wake-up window of the STA, the WUR clock sequence of the STA is set to C + kXL + (k-1) xT₀(ii) a Alternatively, the WUR clock sequence of the STA is set to C + (k-1). times.L + (k-1). times.T₀(ii) a Where k is {1, 2, 3.... times, n }, C is used to represent a first predefined value, L is used to represent the length of each synchronization frame, and T is used to represent the length of each synchronization frame₀For indicating the second predetermined time.

In one possible implementation, the synchronization frame with sequence number k is the first synchronization frame that the STA receives in the WUR wake-up window of the STA. The STA may further include: a first control unit. A first control unit, configured to discard the synchronization frame with the sequence number k + m if the receiving unit receives the synchronization frame with the sequence number k + m in a WUR wake-up window of the STA, where m is {1, 2.

In one possible implementation, the STA may further include: and a sending unit. The transmitting unit is used for transmitting first time information to the AP before the receiving unit receives at least one WUR frame transmitted by the AP in a WUR awakening window of the STA, wherein the first time information comprises the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA; the duration of the WUR awakening window of the STA is used for determining the first preset time, and the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA are used for determining the WUR awakening window of the STA predicted by the AP.

In a possible implementation manner, the receiving unit is further configured to receive second time information broadcasted by the AP before the WUR wake-up window of the STA receives at least one WUR frame sent by the AP, where the second time information includes an interval time of a first WUR wake-up window and a duration of the first WUR wake-up window, and the first WUR wake-up window is a WUR wake-up window of the STA expected by the AP. The STA may further include: a second setting unit. The second setting unit is used for setting the WUR awakening window of the STA according to the interval time of the first WUR awakening window broadcasted by the AP and the duration of the first WUR awakening window received by the receiving unit; wherein the duration of the first WUR awake window is used to determine the first predetermined time.

In one possible implementation, the STA may further include: a second control unit. And the second control unit is used for adjusting the duration of the WUR awakening window of the STA according to a preset window extension rule until the receiving unit receives the synchronization frame sent by the AP if the receiving unit does not receive the synchronization frame sent by the AP in the WUR awakening windows of the N continuous STAs.

In a possible implementation manner, the second control unit is further configured to, if the receiving unit does not receive the synchronization frame sent by the AP in the WUR wake-up windows of the consecutive N STAs, extend the duration of the WUR wake-up window of the STA according to a preset window extension rule until the receiving unit receives the synchronization frame sent by the AP, and restore the duration of the WUR wake-up window of the STA to the duration of the WUR wake-up window of the STA before adjustment.

In one possible implementation, the AP and the STA belong to the same basic service set BSS; a receiving unit, specifically configured to: and receiving at least one synchronization frame broadcasted by the AP in a WUR wake-up window of the STA, wherein each synchronization frame also comprises the identification of the BSS.

The first setting unit is specifically configured to: and if the BSS indicated by the identification of the BSS contained in each of the at least one synchronous frame received by the receiving unit is the same as the BSS to which the STA belongs, setting a WUR clock sequence of the STA.

In one possible implementation, the length of each synchronization frame and the second predetermined time are pre-configured in the STA; or, the receiving unit is further configured to receive the length of each synchronization frame and a second predetermined time sent by the AP before the setting unit sets the WUR clock sequence of the STA according to the received synchronization frame and the first predefined value.

It should be noted that each functional unit of the sixth aspect and various possible implementations of the sixth aspect of the embodiment of the present invention is a logical division performed on the STA to execute the clock synchronization method described in the second aspect and various optional implementations of the second aspect. For a detailed description and a beneficial effect analysis of each functional unit of the sixth aspect and various possible implementations thereof, reference may be made to the corresponding description and technical effects in the second aspect and various possible implementations thereof, which are not described herein again.

In a seventh aspect, there is provided a STA comprising: a processor, a memory, a bus, and a transceiver. The memory is configured to store computer executable instructions, the processor is coupled to the memory via the bus, and the processor is configured to execute the computer executable instructions stored by the memory when the STA is operating, so as to cause the STA to perform the method for clock synchronization as in the second aspect and the various alternatives of the second aspect.

In an eighth aspect, there is provided a non-volatile storage medium having one or more program codes stored therein, which when executed by a processor of the AP in the seventh aspect, the STA performs the method for clock synchronization as in the second aspect and the various alternatives of the second aspect.

The processor in the seventh aspect may be an integration of functional units such as the first setting unit, the second setting unit, the first control unit, and the second control unit in the sixth aspect and various possible implementations thereof, and the transceiver in the seventh aspect may be an integration of the transmitting unit and the receiving unit in the sixth aspect and various possible implementations thereof, so as to implement information interaction between the STA and another communication device (e.g., an AP). The specific technical effect of the STA in the seventh aspect and the specific technical effect of the STA executing the program stored in the computer-readable storage medium according to the eighth aspect and the related analysis process thereof may refer to the description of the related technical effect in the second aspect or any implementation manner of the second aspect of the embodiment of the present invention, and are not described herein again.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic network architecture diagram of a WiFi network according to an embodiment of the present invention;

fig. 2 is a diagram illustrating an example of a WUR wake-up window according to an embodiment of the present invention;

fig. 3 is a schematic diagram illustrating an example of mutually staggered WUR wake windows according to an embodiment of the present invention;

FIG. 4 is a flowchart of a method for clock synchronization according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a WUR frame structure according to an embodiment of the present invention;

fig. 6 is a schematic diagram illustrating an example that an AP transmits a synchronization frame in a WUR wake-up window of the STA expected by the AP according to the embodiment of the present invention;

FIG. 7 is a flow chart of another method for clock synchronization according to an embodiment of the present invention;

FIG. 8 is a flow chart of another method for clock synchronization according to an embodiment of the present invention;

FIG. 9 is a flow chart of another method for clock synchronization according to an embodiment of the present invention;

FIG. 10 is a flow chart of another method for clock synchronization according to an embodiment of the present invention;

FIG. 11 is a flow chart of another method for clock synchronization according to an embodiment of the present invention;

FIG. 12 is a flow chart of another method for clock synchronization according to an embodiment of the present invention;

fig. 13 is a schematic diagram illustrating an example that a STA adjusts a duration of a WUR wake-up window of the STA according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram of an AP according to an embodiment of the present invention;

fig. 15 is a schematic structural diagram of another AP according to an embodiment of the present invention;

fig. 16 is a schematic structural diagram of another AP according to an embodiment of the present invention;

fig. 17 is a schematic structural diagram of an STA according to an embodiment of the present invention;

fig. 18 is a schematic structural diagram of another STA according to an embodiment of the present invention;

fig. 19 is a schematic structural diagram of another STA according to an embodiment of the present invention.

Detailed Description

In the description of the present invention, the meaning of "at least one" means one or more than one unless otherwise specified. For example, at least one synchronization frame refers to one synchronization frame or more than one synchronization frame.

Furthermore, the terms "comprising" and "having" and any variations thereof as referred to in the description of the invention are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements but may alternatively include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, interfaces, techniques, etc., in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

Technical solutions in the embodiments of the present invention will be described in detail below with reference to the drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all the embodiments.

The clock synchronization method and the clock synchronization equipment provided by the embodiment of the invention can be applied to the clock synchronization process, and particularly, the clock synchronization of the AP and the STA is realized in the process that the STA carries out data communication with the AP through the WiFi network.

Referring to fig. 1, a schematic diagram of a network architecture of a WiFi network to which a clock synchronization method according to an embodiment of the present invention is applied is shown. As shown in fig. 1, the WiFi network includes: an AP 10 and at least one STA 20. Among them, the STA 20 includes a communication module and a LP-WUR (WUR for short). After receiving the wakeup frame in the WUR format sent by the AP, the WUR in the STA sends a wakeup signal to the communication module in the STA, and activates the communication module in the sleep mode, so that the communication module receives WiFi data from the AP.

In order to reduce STA power consumption, the WUR in the STA is only active during the periodic WUR wake-up window as shown in fig. 2, and the AP also needs to send a wake-up frame in WUR format to the WUR in the STA at a time corresponding to the WUR wake-up window. For example, as shown in fig. 2, a WUR wake-up window of 2ms duration may be set every 100 milliseconds (ms) for WURs in a STA that are active during the WUR wake-up window of 2ms duration. Here, every 100ms means that the interval between the start times of two adjacent WUR wake-up windows is 100ms, that is, the period of the WUR wake-up window is 100 ms. Due to the jitter of the crystal oscillator of the device, clocks of the STA and the AP can drift; as shown in fig. 3, after a certain time, the expected LP-WUR wake-up window of the STA by the AP is completely staggered from the determined LP-WUR wake-up window of the STA, and the WUR cannot receive the wake-up frame sent by the AP.

The embodiment of the invention provides a clock synchronization method and a clock synchronization device, which can realize the clock synchronization of an AP and an STA, and avoid the problem that a WUR in the STA cannot receive a wake-up frame sent by the AP due to the jitter of a crystal oscillator of equipment; in addition, the problem that in the process of synchronizing the WUR clocks in the AP and the STA, the overhead of periodically transmitting the synchronization frame carrying the larger information is larger because the synchronization frame sent to the STA by the AP is larger in information is solved.

For example, the STA in the embodiment of the present invention may be an electronic terminal installed with a WiFi module, and the electronic terminal may perform data interaction with the AP through a WiFi network. For example, the electronic terminal may be a mobile phone, a PC, a handheld device, a pad, or the like. The AP in the embodiment of the present invention is not limited to a conventional access point, and the AP in the embodiment of the present invention may be any communication device having an access point function, and the AP may perform data interaction with the STA through a WiFi network. For example, the AP may be a WiFi router, and the STA may be a user terminal such as a mobile phone and a computer; when the user terminal such as a mobile phone or a computer is set to be in a WiFi hotspot mode to provide a WiFi network for other terminals, the user terminal such as the mobile phone or the computer is the AP in the embodiment of the present invention, and other terminals connected with the WiFi network provided by the AP are STAs. Alternatively, the AP in the embodiment of the present invention may be a user terminal such as a mobile phone or a computer, and the STA may be a wearable device connected to the user terminal such as the mobile phone or the computer.

A clock synchronization method and apparatus provided in the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

An embodiment of the present invention provides a clock synchronization method, as shown in fig. 4, the clock synchronization method includes:

s401, the AP sends at least one WUR frame to the STA once in a WUR awakening window of the STA predicted by the AP every first preset time, wherein each WUR frame in the at least one WUR frame comprises frame type information, and the frame type information is used for indicating that the WUR frame is a synchronization frame.

Wherein the moment when the AP transmits at least one synchronization frame is located in a WUR wakeup window of the STA predicted by the AP. Specifically, the first predetermined time may be an integer multiple of an interval time of a WUR wakeup window of the STA. For example, the interval time of the WUR wake-up window of the STA may be 100ms, the duration of the WUR wake-up window of the STA may be 2ms, and the AP may transmit at least one sync frame every gx 100ms, where g is a positive integer, such as 1, 2, 3. Since, as long as the AP first transmits at least one sync frame to the STA in the WUR awake window of the STA expected by the AP every first predetermined time, the time of transmitting at least one sync frame to the STA is in the WUR awake window of the STA, the AP will also transmit at least one sync frame in the WUR awake window of the STA expected by the AP every first predetermined time thereafter. And, the first predetermined time cannot be too large, so as not to cause too long interval time between two consecutive transmissions of at least one WUR frame, which results in completely staggering the WUR wake-up window of the STA and the WUR wake-up window of the STA expected by the AP. Specifically, the first predetermined time is less than a time (hereinafter, referred to as a critical time) required for the STA and the AP to generate clock drift so that the WUR wake-up window of the STA completely deviates from the WUR wake-up window of the STA expected by the AP.

For example, the critical time may be a time T from the time when the AP and the STA are completely synchronized (i.e., T1) to the time when the WUR wake-up window of the STA is just completely staggered from the WUR wake-up window of the STA expected by the AP (i.e., T2), as shown in fig. 3. The AP may determine the critical time according to the duration of the WUR wake-up window of the STA (Ton shown in fig. 3).

The method for the AP to determine the critical time according to the duration of the WUR wake-up window of the STA (Ton shown in fig. 3) may include: AP adoption

And calculating to obtain the critical time T. Wherein λ is a clock drift rate, which is used to represent the length of time that the device drifts out per million time units, and λ is measured in parts per million(English: Percent Per Million: ppm for short), the clock drift rate of the device is usually + -lambda. For example, when T_onWhen λ is 500 at 2ms, it can be calculated

That is, if the AP does not transmit a sync frame to the STA within 2000ms (i.e., 2s), the WUR wake-up window of the STA will be completely staggered from the WUR wake-up window of the STA that the AP expects.

It is conceivable that even if clocks of the AP and the STA drift due to device crystal oscillation jitter, as long as the AP and the STA perform clock synchronization at least once within the critical time, that is, the AP transmits at least one synchronization frame to the STA within the critical time, so that the STA sets the WUR clock sequence of the STA according to the at least one synchronization frame, the WUR clock sequence of the STA is the same as the WUR clock sequence of the AP, and the WUR wake-up window of the STA is still not completely staggered from the WUR wake-up window of the STA expected by the AP. Therefore, if the AP sends at least one sync frame to the STA every first predetermined time (the first predetermined time is less than the critical time), it can be guaranteed that the wake-up window of the AP sending the at least one sync frame is not completely staggered from the WUR wake-up window of the STA, and thus, it can be guaranteed that the STA can receive the at least one sync frame in the WUR wake-up window of the STA.

Illustratively, the above frame type information may be included in a WUR preamble of a WUR frame or a MAC header of a WUR frame. In an embodiment of the present invention, the WUR preamble and MAC header of the WUR frame are included in the Payload (english) portion of the WUR frame as shown in fig. 5. As shown in fig. 5, a WUR frame in an embodiment of the present invention may include: a Preamble portion and a payload portion. Wherein the preamble part may include: legacy Short Training Field (L-STF for Short), Legacy Long Training Field (L-LTF for Short), and Legacy Signal Field (L-SIG for Short). The load part may include: WUR preamble, MAC header, frame entity, and FCS. Of course, the payload portion of the WUR frame may not include a frame entity. Among them, the MAC header, the frame entity, and the FCS in the payload portion of the WUR frame as shown in fig. 5 may be collectively referred to as a MAC portion in the payload portion, i.e., the payload portion of the WUR frame may include a WUR preamble and a MAC portion.

In a first application scenario, the frame type information in embodiments of the present invention may be included in the WUR preamble in the payload portion of the WUR frame as shown in fig. 5. Wherein the WUR preamble in the payload portion of the WUR frame may include a synchronization sequence field and a signaling field, and the frame type information may include the synchronization sequence field or the signaling field in the WUR preamble. Of course, the WUR preamble may include other information besides the synchronization sequence field or the signaling field, for example, the WUR preamble may include a frame start identification field.

Optionally, in this embodiment of the present invention, the predefined sequence (e.g., the first predefined sequence) carried in the synchronization sequence field may be used to represent the frame type information.

For example, if a first predefined sequence is carried in a sync sequence field in the WUR preamble of a WUR frame, the WUR frame is a sync frame. For example, the first predefined sequence may be 00000000111111110000000011111111. And if the synchronization sequence field in the WUR preamble of the WUR frame carries a second predefined sequence, the WUR frame is represented as a wake-up frame. For example, the second predefined sequence may be 11111111000000001111111100000000.

Conceivably, after receiving a WUR frame sent by the AP, the STA may detect a synchronization sequence field of a WUR preamble of the WUR frame, and if the synchronization sequence field in the WUR preamble of the WUR frame carries a first predefined sequence, may determine that the WUR frame is a synchronization frame; if the synchronization sequence field in the WUR preamble of the WUR frame carries a second predefined sequence, the WUR frame may be determined to be a wake-up frame.

It should be noted that, in the embodiment of the present invention, only one example of the first predefined sequence and the second predefined sequence is given by way of example, and values of the first predefined sequence and the second predefined sequence include, but are not limited to, values in the above example.

Optionally, in this embodiment of the present invention, one or more bits carried by a signaling field in the WUR preamble in the payload portion of the WUR frame may be used to represent the frame type information.

For example, taking a bit carried in the signaling field to represent the frame type information as an example, when the bit takes a first value (e.g., 0), the WUR frame is represented as a sync frame. When the bit takes on a second value (e.g., 1), the WUR frame is indicated as a wakeup frame.

It is conceivable that the WUR frame in the first application scenario may be a Null-Data Packet (NDP) without a MAC portion, that is, the payload portion of the WUR frame only contains a WUR preamble and does not contain a MAC portion (including a MAC header, a frame entity, and an FCS).

In a second application scenario, the frame type information in the embodiment of the present invention may be included in a MAC header in the payload portion of the WUR frame as shown in fig. 5.

Specifically, the frame type information may be contained in a frame control field in the MAC header as shown in fig. 5, or the frame type information may be contained in a reception address field in the MAC header as shown in fig. 5.

For example, when the frame type information may be included in the frame control field in the MAC header as shown in fig. 5, if the frame type sequence in the frame control field of the WUR frame is a third value (e.g., 000), it indicates that the WUR frame is a sync frame; if the frame type sequence in the frame control field of the WUR frame is a fourth value (e.g., 001), it indicates that the WUR frame is a wake-up frame.

When the frame type information is included in the reception address field in the MAC header as shown in fig. 5, the current WUR frame can be represented as a sync frame with a predefined address. For example, if the address sequence in the reception address field of the WUR frame is all 1, this indicates that the WUR frame is a sync frame; if the address sequence in the reception address field of the WUR frame is not all 1, this indicates that the WUR frame is a wakeup frame.

It should be noted that, the frame type information given above by way of example only may be included in the WUR preamble or the MAC header in the payload portion of the WUR frame, and indicates that the WUR frame is a synchronization frame, and other indication manners are not described again in this embodiment of the present invention.

It is contemplated that the frame type information in embodiments of the present invention may be included not only in the WUR preamble or MAC header in the WUR frame payload portion, but also in the frame entity in the WUR frame payload portion. The specific manner in which the frame entity in the WUR frame payload portion contains frame type information will not be described in detail in embodiments of the present invention.

It should be noted that "in the WUR wake-up window of the STA expected by the AP" may not be necessary. The time interval (i.e. the first predetermined time) for the AP to transmit the two adjacent sync frames should take into account the interval time of the WUR awake window of the STA (i.e. the first predetermined time is determined according to the interval time of the adjacent WUR awake window of the STA), for example, the time interval for the AP to transmit the two adjacent sync frames is an integer multiple of the interval time of the WUR awake window of the STA, but the time for transmitting the first sync frame is not necessarily exactly located in the WUR awake window of the STA, but the first sync frame is transmitted at any time. From the STA perspective, after the AP configures an awake window for its WUR interface, or after the AP instructs the WUR of the STA to start working according to a predefined awake window, it starts to attempt to receive a synchronization frame in the awake window, and if the synchronization frame from the AP is not received within a certain time, it should actively find the synchronization frame by other methods. For example, when the STA does not receive the sync frame from the AP within a certain time, the WUR does not enter the sleep state any more, but continues to monitor the channel until the STA receives the sync frame from the AP again, and after the STA regains synchronization, the WUR of the STA does not enter the awake window operating mode again. Therefore, the time interval (i.e., the first predetermined time) between the two consecutive sync frames transmitted by the AP is related to the period of the wake-up window, but each sync frame may be transmitted periodically according to a predetermined rule without considering whether the current time is in the WUR wake-up window of the STA. In other words, the AP always sends the synchronization frame periodically, regardless of whether the STA's awake window has drifted, and once the STA loses synchronization with the AP, the STA should actively seek the synchronization frame in order to regain synchronization. Once synchronized, the STA is naturally able to receive subsequent synchronization frames since the first predetermined time is related to the time between the STA's adjacent WUR wake-up windows. In fact, this is consistent with the way in which the AP sends Beacon (Beacon) frames in the current 802.11 standard, i.e., the AP always sends Beacon frames at a fixed Target Beacon Transmission Time (TBTT), regardless of whether the STA is active at this Time, and synchronization is achieved by the STA actively listening to Beacon frames. In the following description, the example of "in the WUR wake-up window of the STA expected by the AP" is described, but it should be understood that it is also possible that the AP sends the synchronization frame without considering the WUR wake-up window, and the description thereof is omitted.

It should be noted that, since the AP needs to contend for the channel when transmitting the synchronization frame, the AP may not always successfully contend for the channel at the time when the synchronization frame should be transmitted, so that the actual interval between the adjacent synchronization frames is not always exactly the first predetermined time. Therefore, the above-mentioned "every first predetermined Time" means that the Target Transmission times (Target Transmission times) for transmitting the two adjacent sync frames are separated by the first predetermined Time, which is similar to that in the current 802.11 standard, although the AP indicates the Beacon Interval (Beacon Interval), the Time Interval at which the AP actually transmits the adjacent Beacon frame is not absolutely equal to the Beacon Interval.

S402, when the AP sends at least one synchronous frame, the WUR clock sequence of the AP is set to a first predefined value.

Wherein the AP may set the sequence of WUR clocks of the AP to a first predefined value at a start time or an end time of transmitting each of the at least one synch frame. The first predefined value may be preconfigured, and the preconfigured first predefined value in the AP is the same as the preconfigured first predefined value in the STA. Alternatively, the AP may interact with a communication module in the STA to determine the first predefined value, e.g., the AP may transmit the first predefined value to the communication module in the STA before performing S401.

It is conceivable that the WUR clock sequence of the AP may be used to indicate the current clock of the AP, the WUR clock sequence of the STA may be used to indicate the current clock of the STA, and both the WUR clock sequence of the STA and the WUR clock sequence of the AP may change with time, but due to different drift rates of the device crystal, clock drift may occur between the AP and the STA, that is, the WUR clock sequence of the STA and the WUR clock sequence of the AP may not be absolutely synchronized, so that clocks of the STA and the AP may not be consistent.

It is emphasized that since the AP may need to communicate not only with the WUR in the STA, but also with other devices or modules, for example, the AP may also communicate with a communication module in the STA; therefore, the AP can maintain one WUR clock not only for the WUR in the STA but also for the communication module in the STA. The specific time of the WUR clock maintained by the AP can be represented by the sequence of WUR clocks of the AP. Of course, the AP may also maintain only one clock for the WUR and the communication module in the STA, which is not limited in this embodiment of the present invention. Correspondingly, the STA may also maintain one clock for the WUR in the STA and the communication module in the STA, respectively, or maintain only one clock for the WUR in the STA and the communication module, which is not limited in this embodiment of the present invention.

It should be noted that, the clock sequences in the embodiments of the present invention, such as the WUR clock sequence of the AP, the WUR clock sequence of the STA, the clock sequence of the communication module of the AP, and the clock sequence of the communication module of the STA, may all be TSF clock sequences.

Illustratively, the WUR clock sequence for the STA and the WUR clock sequence for the AP are typically 64 bits. In the process of clock drift of the AP and the STA, the high bits of the WUR clock sequences of the AP and the STA generally have no difference in a short time, and the low bits of the WUR clock sequences of the STA and the low bits of the WUR clock sequences of the AP have a larger difference; therefore, in an embodiment of the present invention, a method for an AP to set a WUR clock sequence of the AP to a first predefined value may include: the AP sets the low X bits of the AP's WUR clock sequence to a first predefined value, which is a sequence of all 0's of X bits.

Illustratively, X is greater than or equal to Y, where the low Y bits of the WUR clock sequence of the STA or AP change within a duration corresponding to the critical time.

The embodiment of the invention can adopt a formula:

and calculating the number Y of the possible change bits of the WUR clock sequence of the STA or the AP in the time duration corresponding to the critical time. For example, when T_on＝2When ms is equal to 12, that is, in the critical time, the low 12 bits of the WUR clock sequence of the STA or the AP may be different, and the other bits above 12 bits may not be changed, and at this time, the value of X may be X ≧ 12.

Of course, the AP may also set its WUR clock sequence entirely to the first predefined value, e.g., the AP may be a 64-bit all-0 sequence.

It is conceivable that the first predefined value in the embodiment of the present invention may also be other sequences, and is not limited to the all-0 sequence, for example, the first predefined value may also be an all-1 sequence of 64bits or an all-1 sequence of X bits.

It is emphasized that even though the AP does not carry 64bits of the WUR clock sequence of the AP in the synchronization frame transmitted to the STA in the prior art, but only carries the low X bits of the WUR clock sequence of the AP, the low X bits of the WUR clock sequence carried by the AP are very expensive for the synchronization frame.

S403, the STA receives at least one WUR frame sent by the AP in a WUR wake-up window of the STA.

Wherein each WUR frame in the at least one WUR frame includes frame type information, and the frame type information is used for indicating that the WUR frame is a synchronization frame.

S404, the STA sets a WUR clock sequence of the STA according to the received synchronous frame and the first predefined value.

According to the clock synchronization method provided by the embodiment of the invention, because the first preset time is less than the time (namely critical time) required for completely staggering the WUR awakening window of the STA and the WUR awakening window of the STA predicted by the AP due to clock drift of the STA and the AP, if the AP sends at least one synchronization frame to the STA once in the WUR awakening window of the STA predicted by the AP every first preset time, the WUR awakening window of the STA predicted by the AP and the WUR awakening window of the STA can be ensured to be not completely staggered, and thus, the STA can be ensured to receive the at least one synchronization frame in the WUR awakening window of the STA certainly. In addition, because the WUR frame sent by the AP to the STA only carries frame type information indicating that the WUR frame is a synchronization frame, compared with 64bits of a WUR clock sequence or low X bits of the WUR clock sequence which need to be carried in the WUR frame in the prior art, the frame type information is generally one or two bits in the WUR frame, and even if the synchronization frame is periodically transmitted, a large overhead is not brought. By the scheme, the clock synchronization of the AP and the STA can be realized, and the overhead of transmitting the synchronization frame can be reduced.

It is conceivable that WUR frames sent by the AP to the STA are generally modulated by OOK, and the unreliable OOK modulation may result in a high transmission error rate of the WUR frames, so that the STA may not successfully receive the WUR frames sent by the AP. Based on this, the at least one WUR frame in the embodiment of the present invention may be a plurality of WUR frames, that is, the AP may continuously transmit a plurality of sync frames (i.e., WUR frames) in the WUR wake-up window of the STA expected by the AP every first predetermined time. As shown in fig. 6, the AP may transmit a synchronization frame to the STA every second predetermined time in a WUR awake window of the STA expected by the AP.

Specifically, the method for the AP to send at least one synchronization frame (i.e., WUR frame) to the STA in S401 may include: the AP sends a synchronization frame to the STA in a WUR wake-up window of the STA predicted by the AP every second preset time. Specifically, as shown in fig. 7, S401 shown in fig. 4 may be replaced with S401 a:

s401a, AP sends a synchronization frame to STA in WUR wake-up window of STA predicted by AP every second preset time.

Wherein the AP may transmit at least one sync frame to the STA in a WUR wake-up window of the STA expected by each AP, and each of the at least one sync frame is transmitted at a second predetermined time interval by interval; therefore, the clock synchronization of the AP and the STA can be realized by the STA receiving any one synchronization frame sent by the AP in the WUR awakening window of the STA, so that the reliability of the transmission of the synchronization frame is improved.

Preferably, the AP may perform "setting the WUR clock sequence of the AP to the first predefined value" only once when transmitting the at least one sync frame. Specifically, as shown in fig. 7, S402 shown in fig. 4 may be replaced with S402 a:

s402a, the AP sets the WUR clock sequence of the AP to a first predefined value at a start time or an end time of transmitting a first of the at least one synchronization frame to the STA.

Wherein the AP may interact with a communication module in the STA, and determine whether the AP sets the WUR clock sequence of the AP to a first predefined value at a "start time of transmitting a first one of the at least one sync frame to the STA" or sets the WUR clock sequence of the AP to the first predefined value at an "end time of transmitting the first one of the at least one sync frame to the STA"; alternatively, the AP and the STA may set the WUR clock sequence according to a time (the start time or the end time) specified by the standard.

Because the synchronization frame between the AP and the STA is generally transmitted after OOK modulation, the unreliability of OOK modulation may cause that the STA may not necessarily receive all the synchronization frames sent by the AP; in order to ensure that the STA can determine that the received synchronization frame is the second synchronization frame that the AP transmits in the WUR awake window of the STA expected by the AP, so as to determine how to set the WUR clock sequence of the STA, each synchronization frame in at least one synchronization frame that the AP transmits to the STA may further include a sequence number of the synchronization frame, where the sequence number of the synchronization frame is used to indicate the sequence of the synchronization frame in the at least one synchronization frame according to the transmission sequence of each synchronization frame in the at least one synchronization frame.

For example, when the AP continuously transmits n sync frames in the WUR wake-up window of the STA expected by the AP, each of the n sync frames may further carry a sequence number k of the sync frame in the n sync frames. Wherein, the synchronization frame with sequence number 1 (i.e. k equals 1) is the first synchronization frame that the AP transmits in the WUR wake-up window of the STA expected by the AP as shown in fig. 6; the synchronization frame with sequence number n (i.e., k ═ n) is the nth synchronization frame transmitted by the AP in the WUR wake-up window of the STA expected by the AP as shown in fig. 6. Wherein n is the number of the synchronous frames in at least one synchronous frame.

Of course, the synchronization frame with sequence number 0 (i.e., k is 0) may be used as the 1 st synchronization frame that the AP transmits in the WUR wake-up window of the STA expected by the AP. Correspondingly, the synchronization frame with the sequence number n-1 (i.e., k ═ n-1) is used as the nth synchronization frame transmitted by the AP in the WUR wake-up window of the STA expected by the AP.

It is conceivable that the WUR clock sequence of the AP is set to a first predefined value since the AP is only transmitting the start time or the end time of the first of the at least one sync frame to the STA; therefore, the STA may also perform "set the WUR clock sequence of the STA" only once according to the received synchronization frame and the first predefined value. Wherein the STA may set its WUR clock sequence immediately after its WUR wakeup window receives the first synchronization frame.

It should be noted that due to a reception error or the like, the first sync frame received by the STA in the WUR awake window of the STA may not be the sync frame with sequence number 1, but may be the sync frame with sequence number x (1 < x ≦ n). Since the AP sets the WUR clock sequence of the AP to a first predefined value only when transmitting a first sync frame (i.e., sync frame with sequence number 1) of at least one sync frame, and a time when the AP transmits the sync frame with sequence number 1 and a time when the sync frame with sequence number k are separated by k-1 second predetermined times, which is an interval time between frames between two adjacent sync frames; therefore, if the STA sets the WUR clock sequence of the STA upon receiving the synchronization frame with sequence number x and the first predefined value, it cannot be guaranteed that the WUR clock sequence of the AP and the WUR clock sequence of the STA are identical. Based on this situation, as shown in fig. 7, S404 shown in fig. 4 may be replaced with S404 a:

s404a, if the STA receives the synchronization frame with sequence number k in the WUR wake-up window of the STA, the STA sets the WUR clock sequence of the STA according to the sequence number k, the length of each of the at least one synchronization frame, the second predetermined time, and the first predefined value.

Wherein k is more than 0 and less than or equal to n, and n is the number of synchronous frames in at least one synchronous frame.

It is conceivable that since the AP sets the WUR clock sequence of the AP to a first predefined value only when transmitting a sync frame with sequence number 1 among at least one sync frame, and the time when the AP transmits the sync frame with sequence number 1 and the time when the sync frame with sequence number k are separated by k-1 second predetermined times, a certain time (i.e., the time domain length of the sync frame) is required to transmit each sync frame; therefore, after receiving the synchronization frame with sequence number k, the STA can set the WUR clock sequence of the STA toC+k×L+(k-1)×T₀Or C + (k-1). times.L + (k-1). times.T₀K ═ 1, 2, 3. Specifically, as shown in fig. 8, after S404a shown in fig. 7, the method according to the embodiment of the present invention may further include S801:

s801, if the STA receives a synchronization frame with the sequence number of k in the WUR wake-up window of the STA, the WUR clock sequence of the STA is set to C + kXL + (k-1) xT₀Or, the STA sets the WUR clock sequence of the STA to C + (k-1). times.L + (k-1). times.T₀。

Where k is {1, 2, 3.... times, n }, C is used to represent a first predefined value, L is used to represent a time-domain length of each synchronization frame, and T is used to represent a time-domain length of each synchronization frame₀For indicating the second predetermined time.

Illustratively, the time domain length and the second predetermined time of each synchronization frame are pre-configured in the STA; alternatively, the AP may transmit the time domain length of the synchronization frame and the second predetermined time to the STA before transmitting the at least one synchronization frame to the STA. In the embodiment of the present invention, the time domain length of each of the at least one synchronization frame is the same. The STA can receive the time domain length L and the second preset time T of the synchronous frame sent by the AP through the communication module of the STA₀。

It will be appreciated that in one implementation, the AP may set the WUR clock sequence of the AP to a first predefined value C at the beginning of the transmission of the first of the at least one synch frame to the STA. In other words, the AP and the STA may each calculate the start point with the start time of the first synchronization frame as the time of clock synchronization.

In this implementation, since k × L + (k-1) × T₀Can be used to indicate the time difference between the STA receiving the sync frame with sequence number k and the AP transmitting the sync frame with sequence number 1, and since the AP only transmits the first sync frame (i.e., sync frame with sequence number 1) to the STA at the start of the WUR wake-up window, the WUR clock sequence of the AP is set to a first predefined value C; thus, if both the AP and the STA are clocked in increments of a clock, starting from the moment the AP sets the WUR clock sequence of the AP to the first predefined value C (i.e., the starting moment of the AP sending the first of the at least one sync frame to the STA),passing through kXL + (k-1). times.T₀During this time period, the WUR clock sequence of the AP may then be C + kXL + (k-1). times.T₀The STA can set the WUR clock sequence of the STA to C + kXL + (k-1) xT immediately after receiving the synchronization frame with the sequence number of k₀。

In another implementation, the AP may set the WUR clock sequence of the AP to a first predefined value C at the end of the transmission of the first of the at least one synch frame to the STA. In other words, the AP and the STA may each calculate the start point with the end time of the first synchronization frame as the time of clock synchronization.

In this implementation, since (k-1). times.L + (k-1). times.T₀Indicating the time difference between the STA receiving the sync frame with sequence number k and the AP transmitting the sync frame with sequence number 1, and setting the WUR clock sequence of the AP to a first predefined value C since the AP transmits the first sync frame (i.e., the sync frame with sequence number 1) to the STA only at the end of the WUR awake window; thus, if both the AP and the STA are clocked in increments of clocks, starting from the time "AP sets the WUR clock sequence of the AP to the first predefined value C" (i.e., the end time of the first of the at least one sync frame sent by the AP to the STA), through (k-1). times.L + (k-1). times.T₀The WUR clock sequence of the AP may be C + (k-1). times.L + (k-1). times.T₀The STA can set the WUR clock sequence of the STA to C + (k-1) xL + (k-1) xT immediately after receiving the synchronization frame with the sequence number of k₀。

Optionally, if the AP and the STA are both clocked by the clock decrementing manner, if the AP sets the WUR clock sequence of the AP to the first predefined value C at the start time of the first sync frame of the at least one sync frame transmitted to the STA, the STA may set the WUR clock sequence of the STA to C- [ k × L + (k-1) × T ] immediately after receiving the sync frame with sequence number k₀](ii) a If the AP sets the WUR clock sequence of the AP to a first predefined value C at the end of the transmission of the first of the at least one synch frame to the STA, the STA may set the WUR clock sequence of the STA to C- [ (k-1) xL + (k-1) xT immediately after receiving the synch frame with sequence number k₀]

Further, after the first sync frame (i.e., the sync frame with sequence number k) received by the STA in the WUR wake-up window, the STA may also receive a sync frame with sequence number k + m, where m is {1, 2. After the STA receives the first synchronization frame in the WUR awakening window of the STA, the WUR clock sequence of the STA is set, namely the clock synchronization of the STA and the AP is realized; therefore, after receiving the synchronization frame with the sequence number k + m, the STA does not need to set the WUR clock sequence of the STA. Specifically, as shown in fig. 9, after S801 shown in fig. 8, the method according to the embodiment of the present invention may further include S901:

s901, if the STA receives the synchronization frame with sequence number k + m, the STA discards the synchronization frame with sequence number k + m, where m is {1, 2.

In the scheme, the STA sets the WUR clock sequence only when the STA receives the first synchronization frame (i.e. the synchronization frame with the sequence number k) in the WUR wake-up window of the STA, instead of performing the "setting the WUR clock sequence of the STA" once every time the STA receives a synchronization frame, so that redundant occupation and energy consumption of the CPU of the STA due to frequent setting of the WUR clock sequence by the STA can be avoided.

Optionally, in an application scenario of the embodiment of the present invention, the STA may actively report the interval time of the WUR wake-up window of the STA and the duration of the WUR wake-up window of the STA to the AP, so that the AP may send the synchronization frame in the WUR wake-up window of the STA.

Specifically, as shown in fig. 10, before S401 shown in fig. 4, the method of the embodiment of the present invention may further include S1001 to S1003:

s1001, the STA sends first time information to the AP, wherein the first time information comprises interval time of a WUR awakening window of the STA and duration of the WUR awakening window of the STA.

Wherein, the STA may transmit the first time information to the AP through a communication module in the STA. It is conceivable that the STA may transmit the first time information to the AP through the communication module in the STA while the communication module in the STA is in the active state. Wherein, the STA may transmit the first time information to the AP through a communication module of the STA.

S1002, the AP receives the first time information sent by the STA.

S1003, the AP determines first preset time according to the duration of the WUR awakening window of the STA, and determines the WUR awakening window of the STA predicted by the AP according to the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA.

Wherein the first predetermined time is less than the critical time, and the moment when the AP transmits at least one synchronization frame is located in a WUR wakeup window of the STA predicted by the AP. It should be noted that, for the method for determining the first predetermined time by the AP according to the duration of the WUR wake-up window of the STA, reference may be made to the detailed description of S401 in the embodiment of the present invention, which is not described herein again; the method for determining the expected WUR wake-up window of the STA by the AP according to the interval time of the WUR wake-up window of the STA and the duration of the WUR wake-up window of the STA by the AP may refer to specific description of determining the expected WUR wake-up window of the STA by the AP in the prior art, and details are not repeated here in the embodiments of the present invention.

It is conceivable that, when the AP and the STAs perform clock synchronization respectively, the AP needs to store the interval time of the WUR wake-up window of each STA of the STAs and the duration of the WUR wake-up window of the STA, and occupies the memory space of the AP; the AP also needs to send a synchronization frame to the corresponding STA in the WUR wake-up window of each STA among the multiple STAs, and too many synchronization frames sent by the AP occupy port resources of the AP, which affects normal transmission of other services of the AP.

As described previously, the AP may only need to determine the first predetermined time (e.g., the first predetermined time is an integer multiple of the interval time of the WUR awake window of the STA) according to the WUR awake window information of the STA, regardless of whether the transmission time of the sync frame is located in the WUR awake window of the STA. In this case, it is not necessary to determine the WUR awake window of the STA expected by the AP according to the interval time of the WUR awake window of the STA and the duration of the WUR awake window of the STA.

In order to reduce the interval time of the WUR wake-up window of the STA and the duration of the WUR wake-up window of the STA to occupy the memory space of the AP and avoid the excessive occupation of the AP port resources by the synchronization frame, in another application scenario of the embodiment of the present invention, the AP may allocate the same interval time of the WUR wake-up window and the duration of the WUR wake-up window to a plurality of STAs, so that the WUR wake-up windows of the plurality of STAs for receiving the synchronization frame are in the same period, even if the plurality of STAs receive the synchronization frame sent by the AP in the same period. That is, the STAs may share a WUR awake window (referred to as a common awake window). Therefore, the AP only needs to maintain one "interval time of a common wake-up window and duration of the common wake-up window" for the plurality of STAs, and does not need to maintain one "interval time of a WUR wake-up window and duration of a WUR wake-up window" for each STA in the plurality of STAs, so that the overhead of AP storage is reduced. Therefore, the AP can send the synchronization frame to the plurality of STAs in the public wake-up window in a broadcasting mode without sending the synchronization frame for one time aiming at each STA in the plurality of STAs, so that the occupation of the synchronization frame on AP port resources can be reduced, and the transmission efficiency of AP services is improved.

Further, the plurality of STAs may include STAs which support the WUR in the middle of the BSS to which the AP belongs, and may also include all STAs which support the WUR in the BSS to which the AP belongs.

It is conceivable that, in the embodiment of the present invention, all STAs supporting WUR in a BSS to which an AP belongs may be divided into at least two STA groups, where each STA group in the at least two STA groups includes at least one STA supporting WUR; and, the STAs in any one of the at least two STA groups share a common awake window, and the common awake windows of the STAs in different STA groups are different.

Preferably, all STAs supporting WUR in the BSS to which the AP belongs may share a common wake-up window, and the AP only needs to maintain a "interval time of the common wake-up window and a duration of the common wake-up window" for all STAs supporting WUR in the BSS to which the AP belongs, so that storage occupation of the WUR wake-up windows of the multiple STAs on the AP is reduced.

The AP may send, to the STAs, notification messages carrying the "interval time of the common awake window and the duration of the common awake window" in a unicast manner, respectively. Specifically, the AP may send an Association Response (english: Association Response) frame to the STA, so that the AP sends a notification message carrying the "interval time of the public awake window and the duration of the public awake window" to the STA; alternatively, after the AP associates with the STA, the AP may notify the STA of the "interval time of the common awake window and the duration of the common awake window" in a special unicast management frame manner.

Preferably, the AP may further send the "interval time of the common awake window and the duration of the common awake window" to the STAs in a broadcast manner.

Of course, the AP may also notify the STAs of the interval time of a common awake window and the duration of the common awake window by means of a broadcast notification message, where the AP may carry the information (the interval time of a common awake window and the duration of the common awake window) in a Beacon (english: Beacon) frame, or the AP may notify the information by means of a special broadcast management frame.

Specifically, as shown in fig. 11, before S401 shown in fig. 4, the method of the embodiment of the present invention may further include S1101-S1103:

s1101, broadcasting second time information to the STA by the AP, wherein the second time information comprises the interval time of the first WUR awakening window and the duration of the first WUR awakening window.

S1102, the STA receives the second time information broadcasted by the AP.

Wherein, the STA may receive the second time information broadcast by the AP through a communication module in the STA.

S1103, if the BSS indicated by the identification of the BSS is the same as the BSS to which the STA belongs, the STA sets the WUR awakening window of the STA according to the interval time of the first WUR awakening window and the duration of the first WUR awakening window.

Illustratively, the identification of the BSS in the embodiment of the present invention may be a complete 64-bit BSS ID, or the identification of the BSS may also be a Color previously allocated to the BSS. In the embodiment of the present invention, different colors may be allocated to different BSSs in advance, so as to uniquely identify corresponding BSSs.

Accordingly, as shown in fig. 12, S401 shown in fig. 11 may be replaced with S401b, S403 shown in fig. 11 may be replaced with S403b, and S404 shown in fig. 11 may be replaced with S404 b:

s401b, the AP broadcasts at least one synchronization frame once to the STA in the awake window of the STA expected by the AP every first predetermined time, wherein each synchronization frame in the at least one synchronization frame further includes an identifier of the BSS.

S403b, the STA receives at least one synchronization frame broadcasted by the AP in the WUR awake window of the STA, where each synchronization frame in the at least one synchronization frame further includes an identifier of the BSS.

S404b, if the BSS indicated by the BSS identifier is the same as the BSS to which the STA belongs, the STA sets the WUR clock sequence of the STA.

In the scheme, each synchronization frame in at least one synchronization frame further includes an identifier of a BSS, so that after receiving any one of the at least one synchronization frame, an STA can compare the identifier of the BSS included in the synchronization frame with the identifier of the BSS to which the STA belongs to determine whether the STA needs to perform clock synchronization, that is, perform clock synchronization only when the WUR receives a WUR synchronization frame sent by an AP of the BSS to which the WUR belongs.

Further, the method of the embodiment of the present invention may further include: if the STA does not receive the synchronization frame sent by the AP in the WUR awakening windows of the N continuous STAs, the STA adjusts the duration of the WUR awakening window of the STA according to a preset window extension rule until the STA receives the synchronization frame sent by the AP. For example, if the STA does not receive the synchronization frame in the WUR awake windows of three consecutive STAs, the STA may extend the duration of the WUR awake window of the STA by 3 times as long as it was in the WUR awake window of the fourth STA.

Preferably, the STA may also enter the awake state in advance while extending the duration of the WUR awake window of the STA. For example, as shown in fig. 13, if the STA does not receive the synchronization frame in the WUR awake windows of three consecutive STAs, the STA may also wake up in advance of the duration of the WUR awake window of one STA and extend the duration of the WUR awake window of the STA by 3 times as long as the duration of the WUR awake window of the fourth STA.

It will be appreciated that some network delays, rather than the clocks of the AP and the STA being out of synchronization, may cause the STA to not receive the synchronization frame sent by the AP during the WUR wakeup window of the STA. In this case, if the STA does not receive the synchronization frame transmitted by the AP within the WUR awake window of consecutive N STAs, the STA may adjust the duration of the WUR awake window of the STA according to the preset window extension rule until the STA receives the synchronization frame transmitted by the AP.

Further, in order to enable the WUR wake-up window of the STA to be in the same time period as the WUR wake-up window of the STA stored in the AP and enable the STA to save more power, after the STA receives the synchronization frame sent by the AP, the STA may restore the duration of the WUR wake-up window of the STA to the duration of the WUR wake-up window of the STA before the adjustment.

According to the clock synchronization method provided by the embodiment of the invention, as the time when the AP sends the at least one synchronization frame is positioned in the WUR awakening window of the STA predicted by the AP, the STA can be ensured to receive the at least one synchronization frame in the WUR awakening window of the STA. Because the first preset time is less than the critical time, and the critical time is the time required for the clock drift of the STA and the AP to make the WUR awakening window of the STA completely staggered with the WUR awakening window of the STA predicted by the AP, if the AP sends at least one synchronous frame to the STA every first preset time, the AP can be ensured to send the awakening window of the at least one synchronous frame to be incompletely staggered with the WUR awakening window of the STA, and thus, the STA can be ensured to receive the at least one synchronous frame in the WUR awakening window of the STA certainly. Moreover, since the WUR frame sent by the AP to the STA carries only frame type information indicating that the WUR frame is a sync frame, the frame type information is generally one or two bits in the WUR frame, or the frame type information can also be represented by a sequence carried in a WUR sync sequence field in the WUR preamble, which does not bring a large overhead even if the sync frame is periodically transmitted, and is sufficient to ensure normal transmission of the sync frame even if the duration of the WUR wake-up window of the STA is limited.

Furthermore, both the AP and the STA can perform clock synchronization only once in a WUR wakeup window, that is, only set the WUR clock sequence once, instead of setting the WUR clock sequence every time a synchronization frame is sent or received, so that the occupation of the CPU of the AP and the STA which frequently performs clock synchronization can be reduced, and further the power consumption can be reduced.

The above describes the scheme provided by the embodiment of the present invention mainly from the point of interaction between the AP and the STA. It is understood that the AP and the STA include hardware structures and/or software modules for performing the respective functions in order to implement the above functions. Those skilled in the art will readily appreciate that the present invention can be implemented in hardware or a combination of hardware and computer software for the exemplary AP and STA and algorithm steps described in connection with the embodiments disclosed herein. Whether a function is performed as hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The embodiments of the present invention may perform the division of the functional modules or functional units on the AP and the STA according to the above method examples, for example, each functional module or functional unit may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated module may be implemented in a form of hardware, or may be implemented in a form of a software functional module or a functional unit. The division of the modules or units in the embodiments of the present invention is schematic, and is only a logic function division, and there may be another division manner in actual implementation.

Fig. 14 shows a schematic diagram of a possible structure of the AP involved in the above embodiments. The AP 1400 may include: a transmission unit 1401, and a setting unit 1402. Wherein, the transmitting unit 1401 is configured to transmit at least one WUR frame to the STA. E.g., a transmitting unit 1401 to support S401, S401a, S1101, and S401b in the above embodiments, and/or other processes for the techniques described herein. A setting unit 1402 for setting a WUR clock sequence of the AP to a first predefined value. For example, setup unit 1402 may be configured to support S402 and S402a in the above-described embodiments, and/or other processes for the techniques described herein.

Further, as shown in fig. 15, the AP 1400 may further include: a receiving unit 1403 and a determining unit 1404. Wherein, the receiving unit 1403 is configured to receive the first time information sent by the STA. For example, receiving unit 1403 is used to support S1002 in the above embodiments, and/or other processes for the techniques described herein. A determining unit 1404, configured to determine a WUR wake-up window of the STA expected by the AP according to the first time information received by the receiving unit 1403. For example, determination unit 1404, for use in S1003 in the above-described embodiments, and/or for use in other processes for the techniques described herein.

Certainly, the AP 1400 provided in the embodiment of the present invention includes, but is not limited to, the above-mentioned functional units, for example, the AP 1400 may further include a storage unit for storing the duration and interval time of the WUR wake-up window of the STA expected by the AP.

In the case of an Integrated unit, the setting unit 1402, the determining unit 1404, and the like may be Integrated into a processing unit, which may be a Processor or a controller, such as a CPU, a general-purpose Processor, a Digital Signal Processor (DSP), an Application-Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or other Programmable logic devices, transistor logic devices, hardware components, or any combination thereof. Which may implement or execute the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. A processing unit may also be a combination that performs computing functions, e.g., a combination of one or more microprocessors, a DSP and a microprocessor, etc. The transmitting unit 1401 and the receiving unit 1403 may be implemented integrally in one communication unit, which may be a communication interface, a transceiver circuit or a transceiver, etc. The storage unit may be a memory.

When the processing unit is a processor, the storage unit is a memory, and the communication unit is a transceiver, the AP 1400 according to the embodiment of the present invention may be the AP 1600 shown in fig. 16.

Referring to fig. 16, AP 1600 includes: a processor 1601, a memory 1602, a transceiver 1603, and a bus 1604. The processor 1601, the memory 1602 and the transceiver 1603 (which may be a WiFi module specifically, and is used for transmitting a WUR frame, and may also be used for other communications between the AP 1600 and the STA) are connected to each other via a bus 1604. The bus 1604 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus 1604 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown in FIG. 16, but this is not intended to represent only one bus or type of bus.

Embodiments of the present invention also provide a non-volatile storage medium having one or more program codes stored therein, wherein when the processor 1601 of the AP 1600 executes the program codes, the AP 1600 executes the relevant method steps shown in any one of fig. 4 and 7-12.

The detailed description of each module or unit in the AP 1600 and the technical effects brought by each module or unit after executing the related method steps in any one of fig. 4 and fig. 7 to fig. 12 provided by the embodiment of the present invention may refer to the related description in the embodiment of the method of the present invention, and are not repeated here.

Fig. 17 shows a schematic diagram of a possible structure of the STA involved in the above embodiments. The STA1700 may include: a receiving unit 1701 and a first setting unit 1702. The receiving unit 1701 is configured to receive a synchronization frame transmitted by an AP in a WUR wake-up window of an STA. E.g., a receiving unit 1701, to support S403, S1102, and S403b in the above-described embodiments, and/or other processes for the techniques described herein. A first setting unit 1702 for setting the WUR clock sequence of the STA according to the synchronization frame received by the receiving unit 1701 and a first predefined value. For example, the first setup unit 1702 is used to support S404, S404a, S801, and S404b in the above embodiments, and/or other processes for the techniques described herein.

Further, as shown in fig. 18, the STA1700 may further include: a first control unit 1703, a sending unit 1704, a second setting unit 1705, and a second control unit 1706. A first control unit 1703, configured to, when the sync frame with sequence number k received by the receiving unit 1701 is the first sync frame received by the receiving unit 1701 in the WUR wake-up window of the STA, if the receiving unit 1701 receives a sync frame with sequence number k + m in the WUR wake-up window of the STA, discard the sync frame with sequence number k + m, {1, 2, ·. E.g., the first control unit 1703, to support S901 in the above embodiments, and/or other processes for the techniques described herein. A transmitting unit 1704, configured to transmit the first time information to the AP. For example, sending unit 1704, may be configured to support S1001 in the embodiments described above, and/or other processes for the techniques described herein. A second setting unit 1705, configured to set a WUR awake window of the STA according to the interval time of the first WUR awake window and the duration of the first WUR awake window, which are received by the receiving unit 1701 from the AP. For example, the second setup unit 1705, is used to support S1103 in the above embodiments, and/or other processes for the techniques described herein. The second control unit 1706 is configured to, if the receiving unit 1701 does not receive the synchronization frame sent by the AP in the WUR wake-up windows of consecutive N STAs, adjust the duration of the WUR wake-up window of the STA according to a preset window extension rule until the receiving unit 1701 receives the synchronization frame sent by the AP. The second control unit 1706 is further configured to, if the receiving unit 1701 does not receive the synchronization frame sent by the AP in the WUR wake-up windows of the consecutive N STAs, extend the duration of the WUR wake-up window of the STA according to a preset window extension rule until the receiving unit 1701 receives the synchronization frame sent by the AP, and restore the duration of the WUR wake-up window of the STA to the duration of the WUR wake-up window of the STA before adjustment.

Of course, the STA1700 provided in the embodiment of the present invention includes, but is not limited to, the above-mentioned functional units, for example, the STA1700 may further include a storage unit for storing the duration and interval time of the WUR wakeup window of the STA.

In the case of using integrated units, the functional units such as the first control unit 1703, the first setting unit 1702, the second setting unit 1705, and the second control unit 1706 may be integrated into one processing unit, and the processing unit may be a processor or a controller, for example, a CPU, a general processor, a DSP, an ASIC, an FPGA, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. Which may implement or execute the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. A processing unit may also be a combination of computing functions, e.g., comprising one or more microprocessors, a DSP and a microprocessor, or the like. The receiving unit 1701 and the transmitting unit 1704 may be implemented integrally in one communication unit, which may be a communication interface, a transceiver circuit, a transceiver, or the like. The storage unit may be a memory.

When the processing unit is a processor, the storage unit is a memory, and the communication unit is a transceiver, the STA1700 according to the embodiment of the present invention may be the STA 1900 shown in fig. 19.

Referring to fig. 19, the STA 1900 includes: a processor 1901, a memory 1902, a transceiver 1903 (which may be specifically a WUR module, and may also be referred to as a WUR interface, for receiving WUR frames sent by an AP), and a bus 1904. The processor 1901, the memory 1902, and the transceiver 1903 are interconnected via a bus 1904. The bus 1904 may be a PCI bus, an EISA bus, or the like. The bus 1904 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown in FIG. 19, but it is not intended that there be only one bus or one type of bus.

An embodiment of the present invention further provides a non-volatile storage medium, where one or more program codes are stored in the non-volatile storage medium, and when the processor 1901 of the STA 1900 executes the program codes, the STA 1900 executes relevant method steps in any one of fig. 4 and fig. 7 to fig. 12.

The detailed description of each module in the STA 1900 and the technical effects brought by each module after the module executes the related method steps in any one of fig. 4, fig. 7 to fig. 12 provided in the embodiment of the present invention may refer to the related description in the embodiment of the method of the present invention, and are not repeated herein.

Through the above description of the embodiments, it is clear to those skilled in the art that, for convenience and simplicity of description, the foregoing division of the functional modules is merely used as an example, and in practical applications, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the device may be divided into different functional modules to complete all or part of the above described functions. For the specific working processes of the system, the apparatus and the unit described above, reference may be made to the corresponding processes in the foregoing method embodiments, and details are not described here again.

The relevant parts among the method embodiments of the invention can be mutually referred; the apparatus provided in the respective apparatus embodiments is adapted to perform the method provided in the respective method embodiments, so that the respective apparatus embodiments may be understood with reference to the relevant parts in the relevant method embodiments. All relevant parts between the embodiments of the invention can be mutually referred. The device structure diagrams given in the device embodiments of the invention only show a simplified design of the corresponding devices. In practical applications, the apparatus may comprise any number of transmitters, receivers, transceivers, processors, memories, etc. to implement the functions or operations performed by the apparatus in the embodiments of the apparatus of the present invention, and all apparatuses that can implement the present invention are within the scope of the present application. The names of the message/frame/indication information, the module or the unit, etc. provided in the embodiments of the present invention are only examples, and other names may be used as long as the roles of the message/frame/indication information, the module or the unit, etc. are the same.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, a network device, or the like) or a processor (processor) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A method of clock synchronization, comprising:

the method comprises the steps that an Access Point (AP) sends at least one WUR frame to a Station (STA) every other first preset time, wherein each WUR frame in the at least one WUR frame comprises frame type information, and the frame type information is used for indicating that the WUR frame is a synchronization frame;

the AP sets a WUR clock sequence of the AP to a first predefined value when transmitting the at least one synch frame;

wherein the first predetermined time is less than the time required for the STA and the AP to generate clock drift so that the WUR awakening window of the STA is completely staggered from the WUR awakening window of the STA predicted by the AP.

2. The method of claim 1 wherein the WUR preamble of each WUR frame contains the frame type information;

alternatively, the first and second electrodes may be,

the MAC header of each WUR frame includes the frame type information, where a frame control field in the MAC header includes the frame type information, or a receiving address field in the MAC header includes the frame type information.

3. The method of any of claims 1-2, wherein the method for the AP to transmit the at least one synchronization frame to the STA every first predetermined time comprises:

the AP sends a synchronization frame to the STA at intervals of second preset time in a WUR awakening window of the STA predicted by the AP;

each of the at least one synchronization frame further includes a sequence number of the synchronization frame, where the sequence number of the synchronization frame is used to indicate the sequence of the synchronization frame in the at least one synchronization frame according to the sending sequence of each synchronization frame in the at least one synchronization frame.

4. The method of any of claims 1-2, wherein the method for the AP to transmit the at least one synchronization frame to the STA every first predetermined time comprises:

the AP sends at least one synchronous frame to the STA every other first preset time, wherein the time interval between two adjacent synchronous frames in the at least one synchronous frame is second preset time;

5. The method of claim 4, wherein the AP setting a WUR clock sequence of the AP to a first predefined value when transmitting at least one synch frame comprises: the AP sets a WUR clock sequence of the AP to the first predefined value at a start time or an end time of transmitting a first of the at least one synch frame to the STA.

6. The method of claim 3, wherein the AP setting a sequence of WUR clocks of the AP to a first predefined value while transmitting at least one synch frame comprises: the AP sets a WUR clock sequence of the AP to the first predefined value at a start time or an end time of transmitting a first of the at least one synch frame to the STA.

7. A method of clock synchronization having all the features of the method of any one of claims 1 to 6, and further comprising, before the access point AP sends at least one WUR frame to a station STA every first predetermined time, the method comprising:

the AP receives first time information sent by the STA, wherein the first time information comprises the interval time of a WUR awakening window of the STA and the duration of the WUR awakening window of the STA;

and the AP determines the first preset time according to the duration of the WUR awakening window of the STA, and/or determines the WUR awakening window of the STA predicted by the AP according to the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA.

8. A method of clock synchronization having all the features of the method of any one of claims 1 to 6, and further comprising, before the access point AP sends at least one WUR frame to a station STA every first predetermined time, the method comprising:

and the AP broadcasts second time information to the STA, wherein the second time information comprises the interval time of a first WUR awakening window and the duration of the first WUR awakening window.

9. The method of claim 8 wherein the first WUR awake window is a WUR awake window of the STA expected by the AP.

10. A method of clock synchronization characterized in that it has all the features of the method of any of claims 8 to 9 and in that said AP and said STA belong to the same basic service set, BSS;

the method for the AP to send the at least one synchronization frame to the STA every the first preset time comprises the following steps: and the AP broadcasts the at least one synchronous frame to the STA once in a wake-up window of the STA predicted by the AP every other first preset time, wherein each synchronous frame in the at least one synchronous frame also comprises the identification of the BSS.

11. A method of clock synchronization having all the features of the method of any one of claims 3 to 6, and further comprising, before the AP transmits the at least one synchronization frame to the STA every first predetermined time: the AP transmits the length of each of the at least one synchronization frame and the second predetermined time to the STA.

12. A method of clock synchronization, characterized in that it has all the features of the method of any one of claims 1 to 11, and in that said first predefined value is pre-configured;

alternatively, the first and second electrodes may be,

before the access point AP transmits at least one WUR frame to the station STA every first predetermined time, the method further comprises:

the AP sends the first predefined value to the STA.

13. A method of clock synchronization, comprising:

a station STA receives at least one WUR frame sent by an access point AP in a wake-up radio frequency WUR wake-up window of the STA, wherein each WUR frame in the at least one WUR frame comprises frame type information, the frame type information is used for indicating that the WUR frame is a synchronous frame, and the at least one WUR frame is sent by the AP every first preset time;

the STA sets a WUR clock sequence of the STA according to the received synchronous frame and a first predefined value;

14. The method of claim 13 wherein the WUR preamble of each WUR frame contains the frame type information;

alternatively, the first and second electrodes may be,

15. The method of any of claims 13-14 wherein each synchronization frame in the at least one WUR frame is sent by the AP to the STA every second predetermined time during a WUR wake-up window of the STA expected by the AP;

each synchronization frame also contains the sequence number of the synchronization frame, and the sequence number of the synchronization frame is used for indicating the sequence of the synchronization frame in the at least one synchronization frame according to the sending sequence of each synchronization frame in the at least one synchronization frame.

16. The method of any of claims 13-14 wherein each synchronization frame in the at least one WUR frame is transmitted by the AP to the STA every second predetermined time;

17. A method of clock synchronization characterized in that it has all the features of the method of any one of claims 15 to 16 and in that said STA sets its WUR clock sequence according to the received synchronization frame and said first predefined value, comprising:

if the STA receives a synchronization frame with the sequence number k in a WUR awakening window of the STA, the STA sets a WUR clock sequence of the STA according to the sequence number k, the length of each synchronization frame in the at least one synchronization frame, the second preset time and the first predefined value; wherein k is more than 0 and less than or equal to n, and n is the number of the synchronous frames in the at least one synchronous frame.

18. The method of claim 17, wherein the STA setting the WUR clock sequence of the STA according to the sequence number k, the length of each of the at least one synchronization frame, the second predetermined time, and the first predefined value comprises:

the STA sets the WUR clock sequence of the STA to C + kXL + (k-1) xT₀；

Alternatively, the first and second electrodes may be,

the STA sets a WUR clock sequence of the STA to C + (k-1) xL + (k-1) xT₀；

Where k is {1, 2, 3, … …, n }, C is used to represent the first predefined value, L is used to represent a time domain length of the each synchronization frame, and T is used to represent a time domain length of the each synchronization frame₀For indicating the second predetermined time.

19. The method of claim 18 wherein the sync frame with sequence number k is the first sync frame received by the STA during the STA's WUR wake-up window;

the method further comprises the following steps:

if the STA receives a synchronization frame with sequence number k + m in the WUR awake window of the STA, the STA discards the synchronization frame with sequence number k + m, where m is {1, 2, … …, n-1 }.

20. A method of clock synchronization characterized in that it has all the features of any one of the methods of claims 13 to 19 and that before the station STA receives at least one WUR frame sent by the access point AP in its wake-up rf WUR wake-up window, it further comprises:

the STA sends first time information to the AP, wherein the first time information comprises the interval time of a WUR awakening window of the STA and the duration of the WUR awakening window of the STA;

wherein, the duration of the WUR wakeup window of the STA is used for determining the first preset time, and/or the interval time of the WUR wakeup window of the STA and the duration of the WUR wakeup window of the STA are used for determining the WUR wakeup window of the STA predicted by the AP.

21. A method of clock synchronization characterized in that it has all the features of any one of the methods of claims 13 to 19 and that before the station STA receives at least one WUR frame sent by the access point AP in its wake-up rf WUR wake-up window, it further comprises:

the STA receives second time information broadcasted by the AP, wherein the second time information comprises the interval time of a first WUR awakening window and the duration of the first WUR awakening window;

the STA sets a WUR awakening window of the STA according to the interval time of the first WUR awakening window and the duration of the first WUR awakening window;

wherein a duration of the first WUR awake window is used to determine the first predetermined time.

22. The method of claim 21 wherein the first WUR awake window is a WUR awake window of the STA expected by the AP.

23. A method of clock synchronization, characterized in that it has all the features of the method of any one of claims 13 to 22, and in that it further comprises:

if the STA does not receive the synchronization frame sent by the AP in the WUR awakening windows of N continuous STAs, the STA adjusts the duration of the WUR awakening window of the STA according to a preset window extension rule until the STA receives the synchronization frame sent by the AP.

24. The method of claim 23 wherein, if the STA does not receive the synchronization frame from the AP in the WUR awake window of N consecutive STAs, the STA extends the duration of the WUR awake window of the STA according to the preset window extension rule until the STA receives the synchronization frame from the AP, the method further comprising: and the STA restores the time length of the WUR awakening window of the STA into the time length of the WUR awakening window of the STA before adjustment.

25. A method of clock synchronization characterized in that it has all the features of the method of claim 21 and in that said AP and said STA belong to the same basic service set, BSS;

the method for the STA to receive at least one synchronization frame sent by the AP in a WUR wake-up window of the STA comprises the following steps:

the STA receives the at least one synchronization frame broadcasted by the AP in a WUR wakeup window of the STA, wherein each synchronization frame in the at least one synchronization frame also comprises an identification of a BSS;

the STA sets a WUR clock sequence of the STA according to the received synchronization frame and the first predefined value, and the WUR clock sequence comprises the following steps:

and if the BSS indicated by the identification of the BSS is the same as the BSS to which the STA belongs, the STA sets a WUR clock sequence of the STA.

26. A method of clock synchronization characterized in that it has all the features of the method of claim 18 and in that the length of each synchronization frame and the second predetermined time are preconfigured in the STA;

alternatively, the first and second electrodes may be,

before the STA sets a WUR clock sequence of the STA according to the received synchronization frame and a first predefined value, the method further comprises:

and the STA receives the length of each synchronous frame and the second preset time sent by the AP.

27. A method of clock synchronization characterized in that it has all the features of the method of claim 19 and in that the length of each synchronization frame and the second predetermined time are preconfigured in the STA;

alternatively, the first and second electrodes may be,

28. An access point, AP, comprising:

the transmitting unit is used for transmitting at least one WUR frame to the station STA once every first preset time, wherein each WUR frame in the at least one WUR frame comprises frame type information, and the frame type information is used for indicating that the WUR frame is a synchronization frame;

a setting unit, configured to set a WUR clock sequence of the AP to a first predefined value when the transmitting unit transmits the at least one sync frame;

29. The AP of claim 28, wherein the WUR preamble of each WUR frame includes the frame type information;

alternatively, the first and second electrodes may be,

30. The AP according to any of claims 28-29, wherein the sending unit is specifically configured to:

sending a synchronization frame to the STA every second preset time in a WUR wake-up window of the STA predicted by the AP;

31. The AP according to any of claims 28-29, wherein the sending unit is specifically configured to:

transmitting a synchronization frame to the STA every second predetermined time;

32. The AP of claim 30, wherein the setting unit is specifically configured to:

setting the WUR clock sequence of the AP to the first predefined value at a start time or an end time when the transmitting unit transmits a first one of the at least one sync frame to the STA.

33. The AP of claim 31, wherein the setting unit is specifically configured to:

34. An AP having all the features of the AP of any one of claims 28 to 33, and further comprising:

a receiving unit, configured to receive first time information sent by the STA before the transmitting unit transmits the at least one WUR frame to the STA every other first predetermined time, where the first time information includes an interval time of a WUR awake window of the STA and a duration of the WUR awake window of the STA;

and the determining unit is used for determining the first preset time according to the duration of the WUR awakening window of the STA received by the receiving unit, and/or determining the WUR awakening window of the STA predicted by the AP according to the interval time of the WUR awakening window of the STA received by the receiving unit and the duration of the WUR awakening window of the STA.

35. An AP having all the features of any one of claims 28 to 33, wherein the transmitting unit is further configured to broadcast second time information to a station STA before transmitting at least one WUR frame to the STA every first predetermined time, and the second time information includes an interval time of a first WUR wake-up window and a duration of the first WUR wake-up window.

36. The AP of claim 35 wherein the first WUR awake window is a WUR awake window expected by the AP for the STA.

37. The AP of claim 35, wherein the AP and the STA belong to a same basic service set, BSS;

the sending unit is specifically configured to:

and transmitting the at least one synchronization frame to the STA once every other first preset time, wherein each synchronization frame in the at least one synchronization frame also comprises the identification of the BSS.

38. An AP having all the features of the AP of any one of claims 31 to 33, wherein the transmitting unit is further configured to transmit the length of each of the at least one synchronization frame and the second predetermined time to the STA before transmitting the at least one synchronization frame to the STA at every first predetermined time.

39. An AP, characterized in that the AP has all the features of the AP of any one of claims 28 to 38, and in that the first predefined value is preconfigured;

alternatively, the first and second electrodes may be,

the sending unit is further configured to send the first predefined value to a station STA before sending at least one WUR frame to the STA every first predetermined time.

40. A Station (STA), comprising:

the receiving unit is used for receiving at least one WUR frame sent by an Access Point (AP) in a wake-up radio frequency (WUR) wake-up window of the STA, wherein each WUR frame in the at least one WUR frame comprises frame type information, the frame type information is used for indicating that the WUR frame is a synchronous frame, and the at least one WUR frame is sent by the AP every first preset time;

a first setting unit, configured to set a WUR clock sequence of the STA according to the synchronization frame received by the receiving unit and a first predefined value;

41. The STA of claim 40 wherein the WUR preamble of each WUR frame contains the frame type information;

alternatively, the first and second electrodes may be,

42. The STA according to any one of claims 40-41, wherein each of the at least one synchronization frame received by the receiving unit is sent by the AP to the STA every second predetermined time;

43. The STA of claim 42, wherein the first setting unit is further configured to set the WUR clock sequence of the STA according to the sequence number k, the length of each of the at least one synchronization frame, the second predetermined time, and the first predefined value if the receiving unit receives a synchronization frame with sequence number k in the WUR awake window of the STA; wherein k is more than 0 and less than or equal to n, and n is the number of the synchronous frames in the at least one synchronous frame.

44. The STA of claim 43, wherein the first setting unit is specifically configured to:

setting a WUR clock sequence of the STA to C + kXL + (k-1) xT₀；

Alternatively, the first and second electrodes may be,

the STA sets a WUR clock sequence of the STA to C + (k-1) xL + (k-1) xT₀；

Where k is {1, 2, 3, … …, n }, C is used to represent the first predefined value, L is used to represent the length of each of the synchronization frames, and T is used to represent the length of each of the synchronization frames₀For indicating the second predetermined time.

45. The STA of claim 44 wherein the sync frame with sequence number k is the first sync frame received by the STA in the WUR awake window of the STA;

the STA further comprises:

a first control unit, configured to discard the synchronization frame with sequence number k + m if the receiving unit receives the synchronization frame with sequence number k + m in the WUR wake-up window of the STA, where m is {1, 2, … …, n-1 }.

46. An STA having all the features of the STA of any one of claims 40 to 45 and further comprising:

a sending unit, configured to send first time information to the AP before the receiving unit receives the at least one WUR frame sent by the AP in a WUR awake window of the STA, where the first time information includes an interval time of the WUR awake window of the STA and a duration of the WUR awake window of the STA;

wherein, the duration of the WUR awakening window of the STA is used for determining the first preset time, and/or the interval time of the WUR awakening window of the STA and the duration of the WUR awakening window of the STA are used for determining the WUR awakening window of the STA expected by the AP.

47. An STA, wherein the STA has all the features of the STA of any one of claims 40 to 45, and the receiving unit is further configured to receive second time information broadcasted by the AP before a WUR wake-up window of the STA receives the at least one WUR frame sent by the AP, where the second time information includes an interval time of a first WUR wake-up window and a duration of the first WUR wake-up window;

the STA further comprises:

the second setting unit is used for setting the WUR awakening window of the STA according to the interval time of the first WUR awakening window received by the receiving unit and the duration of the first WUR awakening window;

48. The STA of claim 47 wherein the first WUR awake window is a WUR awake window of the STA expected by the AP.

49. A STA, characterized in that the STA has all the features of the STA of any one of claims 40 to 48, and further comprising:

and the second control unit is used for adjusting the duration of the WUR awakening window of the STA according to a preset window extension rule until the receiving unit receives the synchronization frame sent by the AP if the receiving unit does not receive the synchronization frame sent by the AP in the continuous N WUR awakening windows of the STA.

50. The STA of claim 49, wherein the second control unit is further configured to, if the receiving unit does not receive the synchronization frame sent by the AP in N consecutive WUR awake windows of the STA, extend the duration of the WUR awake window of the STA according to a preset window extension rule until the receiving unit receives the synchronization frame sent by the AP, restore the duration of the WUR awake window of the STA to the duration of the WUR awake window of the STA before adjustment.

51. A STA, characterized in that the STA has all the features of the STA of claim 47, and the AP and the STA belong to the same basic service set, BSS;

the receiving unit is specifically configured to:

receiving the at least one synchronization frame broadcasted by the AP in a WUR wakeup window of the STA, wherein each synchronization frame in the at least one synchronization frame further comprises an identification of the BSS;

the first setting unit is specifically configured to:

and if the BSS indicated by the identification of the BSS contained in each of the at least one synchronization frame received by the receiving unit is the same as the BSS to which the STA belongs, setting a WUR clock sequence of the STA.

52. An STA characterized in that it has all the features of the STA of claim 44 or 45 and that the length of each synchronization frame and the second predetermined time are pre-configured in the STA;

alternatively, the first and second electrodes may be,

the receiving unit is further configured to receive the length of each synchronization frame and the second predetermined time sent by the AP before the first setting unit sets the WUR clock sequence of the STA according to the synchronization frame and the first predefined value received by the receiving unit.

53. An access point, AP, comprising: a processor, a memory, a bus, and a transceiver;

the memory is used for storing computer-executable instructions, the processor is connected with the memory through the bus, and when the AP runs, the processor executes the computer-executable instructions stored by the memory so as to enable the AP to execute the clock synchronization method according to any one of claims 1-12.

54. A Station (STA), the STA comprising: a processor, a memory, a bus, and a transceiver;

the memory is configured to store computer-executable instructions, the processor is coupled to the memory via the bus, and when the STA is running, the processor executes the computer-executable instructions stored in the memory to cause the STA to perform the method of clock synchronization according to any one of claims 13 to 27.

55. The STA of claim 54 wherein the transceiver is a WUR module.

56. A storage medium, characterized in that the storage medium stores a computer program which, when executed by a computer, is capable of implementing the method of any one of claims 1-12.

57. A storage medium, characterized in that the storage medium stores a computer program which, when executed by a computer, is capable of implementing the method of any one of claims 13-27.