CN115988630B - Wireless network time synchronization method based on pulse coupling oscillator model - Google Patents

Abstract

The invention belongs to the technical field of wireless sensor network communication, and particularly relates to a wireless network time synchronization method based on a pulse coupled oscillator model, which comprises the steps of starting a time synchronization mechanism in a preset time period by designing the pulse coupled oscillator model with an idle state, a monitoring state and an excitation state and corresponding switching rules, enabling the pulse coupled oscillators to alternately and circularly switch among the idle state, the monitoring state and the excitation state, and enabling follower pulse coupled oscillators with different orders to sequentially achieve time synchronization with a leader pulse coupled oscillator according to corresponding node division rules; the method and the device remarkably reduce the requirement of time synchronization based on the pulse coupled oscillator on the wireless sensor network, and greatly expand the application range of the time synchronization method based on the pulse coupled oscillator in the wireless sensor network.

Description

A wireless network time synchronization method based on pulse coupled oscillator model

Technical Field

The invention belongs to the technical field of wireless sensor network communication, and in particular relates to a wireless network time synchronization method based on a pulse coupled oscillator model, which can be widely applied to the time synchronization process of a wireless sensor network.

Background Art

Wireless sensor networks are wireless networks composed of a large number of sensor nodes. They integrate detection sensing, wireless communication, distributed information processing and other technologies, and are widely used in many fields such as environmental monitoring and logistics and transportation. The capabilities of a single node in a wireless sensor network are limited, and the powerful functions of a wireless sensor network are achieved through the cooperation between nodes. In a wireless sensor network, each node has its own time, and the time synchronization of the entire network nodes is the prerequisite for the cooperation between wireless sensor nodes.

The traditional time synchronization method is data packet-based time synchronization, that is, sensor nodes achieve synchronization by exchanging synchronization data packets containing their own time information. For example, CN101977433A discloses an average time synchronization method for wireless sensor networks, which abstracts the topological structure of the wireless sensor network into a graph model G, and uses the time value of the network node at the initial moment as the node initial value; the edge controlled by the switching signal transmits data packets at the same time for communication, and the nodes i and j connected by the edge send and receive three data packets to implement the average time operation of the node and complete the update of their respective local time; the execution is repeated until the maximum difference between the network nodes gradually approaches an error within an allowable range, the network achieves average time synchronization, the network nodes continue to work, and the time synchronization state is stably maintained. CN101588628A discloses a wireless sensor network time synchronization method. First, the wireless sensor network is constructed into a tree-type network topology, and the time value of the root node is used as the reference time, and the root node is synchronized with the base station of the network through a pair-wise algorithm; then the root node broadcasts a synchronization data packet containing the root node time information along each subtree, and the parent node of each subtree is synchronized with its child node through a pair-wise algorithm, and finally each layer of each subtree is synchronized; until each node in the tree-type network has a unified time signal.

However, data packet-based time synchronization has many limitations, including: 1) The transmission, encoding, and decoding processes of synchronization data packets will inevitably produce time delays, resulting in reduced synchronization accuracy; 2) The synchronization data packets contain information such as the time and identity of the sensor nodes, which can easily cause information leakage; 3) In the time synchronization process of large-scale wireless sensor networks, the transmission of a large number of data packets will cause high energy loss and occupy a large amount of bandwidth, which makes the data packet-based time synchronization method difficult to apply in large-scale wireless sensor networks.

In view of the above limitations, exploring time synchronization methods with high precision, high security and low energy consumption has become an important research direction for wireless sensor networks. Inspired by various biological synchronization phenomena in nature, such as the synchronized flashing of fireflies, the rhythmic contraction of myocardial cells, and the synchronized discharge of neuronal cells, time synchronization based on pulse-coupled oscillators has emerged. A pulse-coupled oscillator is an oscillator that periodically sends pulse signals. Each sensor node can be designed as a pulse-coupled oscillator. Under the time synchronization mechanism based on pulse-coupled oscillators, the time synchronization of the entire network can be achieved by exchanging pulse signals that do not carry any additional information between nodes. Time synchronization based on pulse-coupled oscillators has the following advantages: 1) Pulse signals do not carry any additional information, so the time delay generated when sending, transmitting, receiving, and processing pulse signals is small and the synchronization accuracy is high; 2) Pulse signals do not carry additional information such as time and identity. Time synchronization based on pulse-coupled oscillators effectively protects the time and identity of sensor nodes from being leaked; 3) In the time synchronization process of large-scale wireless sensor networks, time synchronization achieved by exchanging pulse signals consumes less energy and does not occupy a large amount of bandwidth. Due to the constraints of limited energy of wireless sensor nodes and limited bandwidth of communication channels between nodes, the above advantages make time synchronization based on pulse coupled oscillators naturally suitable for wireless sensor networks. Therefore, the research on time synchronization based on pulse coupled oscillators has important theoretical significance and application prospects.

Although time synchronization based on pulse-coupled oscillators has received extensive attention from scholars at home and abroad, there are still many problems that have not been properly resolved. Since the pulse signals exchanged between nodes do not carry any additional information, the external information that each pulse-coupled oscillator can obtain is extremely scarce, which makes it difficult to achieve time synchronization for the entire network. In order to ensure that wireless sensor networks can achieve time synchronization, the existing time synchronization mechanism based on pulse-coupled oscillators usually requires the wireless sensor network to meet one or more of the following constraints:

1) The network topology must be a special structure such as fully connected, spanning tree, chain, ring, etc.

2) The coupling strength between network nodes must be selected between [0.5, 1]. In addition, when the coupling strength between network nodes is less than 1, the existing time synchronization mechanism based on pulse coupled oscillators can only achieve asymptotic time synchronization, that is, when time tends to infinity, time synchronization can finally be achieved.

3) The initial phase of all pulse-coupled oscillators in the network is within half an oscillation period.

The above stringent constraints severely limit the widespread application of existing pulse-coupled oscillator-based time synchronization in wireless sensor networks.

Summary of the invention

In view of the problems existing in the prior art, the present invention proposes a novel pulse coupled oscillator model and its time synchronization mechanism, which significantly reduces the requirements of pulse coupled oscillator time synchronization on wireless sensor networks in the following three aspects, and greatly expands the application scope of the pulse coupled oscillator time synchronization method in wireless sensor networks:

1) In terms of network topology, the topology of the wireless sensor network only needs to be a general connected structure rather than a special structure such as full connection, spanning tree, chain, ring, etc.;

2) In terms of the coupling strength between network nodes, the coupling strength between nodes can be arbitrarily selected between (0, 1] instead of being limited to [0.5, 1]. In addition, when the coupling strength between nodes is less than 1, the network can achieve time synchronization within a limited time.

3) In terms of the initial phase distribution of the pulse coupled oscillator, the initial phase of the pulse coupled oscillator in the network can be distributed arbitrarily.

The complete technical solution of the present invention includes:

A wireless network time synchronization method based on a pulse coupled oscillator model, wherein the wireless network comprises a plurality of pulse coupled oscillators, all of which are directly or indirectly connected;

、一个与内部时间相关的相位变量

，以及空闲状态、监听状态和激发状态三种状态；每个脉冲耦合振荡器的相位变量以恒定速度从0向临界值运动，相位变量运行到临界值时，脉冲耦合振荡器将相位变量重置为0，并根据所处状态决定是否发送脉冲信号；每个脉冲耦合振荡器收到一个外部脉冲信号时，根据所处状态决定是否进行相位跳变；The pulse coupled oscillator model is as follows: Each pulse coupled oscillator has an internal time

, a phase variable related to the internal time

, as well as three states: idle state, monitoring state and exciting state; the phase variable of each pulse-coupled oscillator moves from 0 to the critical value at a constant speed. When the phase variable reaches the critical value, the pulse-coupled oscillator resets the phase variable to 0 and decides whether to send a pulse signal according to the state; when each pulse-coupled oscillator receives an external pulse signal, it decides whether to perform a phase jump according to the state;

The wireless network time synchronization method is as follows: all pulse coupled oscillators start the time synchronization mechanism within a preset time period. After the pulse coupled oscillators start the time synchronization mechanism, they first enter the idle state and switch between the idle state, the listening state, and the exciting state in turn.

The wireless network defines the pulse coupled oscillator that sends out the pulse signal first after starting the time synchronization mechanism as the initial leader; and divides the remaining pulse coupled oscillators into multiple-order followers from the first-order follower to the M-order follower according to their connection relationship with the initial leader;

In the process of switching between the idle state, the monitoring state and the exciting state of all pulse-coupled oscillators in the wireless network, the followers from the first order to the M order successively achieve time synchronization with the initial leader.

Furthermore, in the pulse coupled oscillator model, the operation rules of each pulse coupled oscillator in the idle state, the monitoring state, and the exciting state are:

When the pulse coupled oscillator is in an idle state, the pulse coupled oscillator does not send out a pulse signal; when the pulse coupled oscillator receives an external pulse signal in the idle state, the pulse coupled oscillator does not perform a phase jump; after the idle state ends, the pulse coupled oscillator enters a listening state;

When the pulse coupled oscillator is in the monitoring state, the pulse coupled oscillator only monitors whether there is a pulse signal input without sending a pulse signal; when the pulse coupled oscillator receives a pulse signal in the monitoring state, the pulse coupled oscillator performs a phase jump according to the phase jump function and the coupling strength, and at the same time ends the monitoring state and enters the exciting state;

When the pulse coupled oscillator is in an excited state, after receiving a pulse signal, the pulse coupled oscillator performs a phase jump according to the phase jump function and the coupling strength; when the pulse coupled oscillator is in an excited state and the phase variable reaches a critical value, the pulse coupled oscillator sends a pulse signal and resets the phase variable to 0, and at the same time ends the excited state and enters the idle state.

Furthermore, when the pulse coupled oscillator receives an external pulse signal in the monitoring state or the exciting state, the pulse coupled oscillator performs a phase jump according to the following method:

为脉冲耦合振荡器在t时刻收到脉冲信号时的相位，

为相位跳变函数，

为耦合强度，

为相位跳变后脉冲耦合振荡器的相位。In the formula,

is the phase of the pulse coupled oscillator when it receives the pulse signal at time t,

is the phase jump function,

is the coupling strength,

is the phase of the pulse coupled oscillator after the phase jump.

为：Furthermore, the phase jump function

for:

。

.

Furthermore, the remaining pulse coupled oscillators are divided into multiple-order followers from 1st-order followers to M-order followers according to their connection relationship with the initial leader, specifically:

A pulse coupled oscillator directly connected to an initial leader and not belonging to the initial leader is defined as a first-order follower; a pulse coupled oscillator directly connected to a first-order follower and not belonging to the initial leader and the first-order follower is defined as a second-order follower, and the pulse coupled oscillators in the wireless network are divided into a total of M-order followers according to the above division rules, where M≤N-1;

The initial leader first achieves time synchronization within a finite time; then, followers from order 1 to order M successively achieve time synchronization with the initial leader within a finite time.

Furthermore, after the time synchronization mechanism is started, the pulse coupled oscillator switches between the idle state, the monitoring state, and the excitation state in turn in a cyclic process as follows:

时刻进入第

轮空闲状态；在内部时间为

时刻结束第

轮空闲状态空闲状态，进入第

轮监听状态；

为脉冲耦合振荡器内部时间，

为无线网络中脉冲耦合振荡器数量，

为脉冲耦合振荡器的自然振荡周期，

为大于等于1的自然数；Entering the listening state from the idle state: The i-th pulse coupled oscillator i is internally

Enter the moment

The wheel is in idle state; the internal time is

The end of time

Idle state, enter the idle state

Wheel monitoring status;

is the internal time of the pulse coupled oscillator,

is the number of pulse coupled oscillators in the wireless network,

is the natural oscillation period of the pulse coupled oscillator,

is a natural number greater than or equal to 1;

时刻进入第

轮监听状态；若第i个脉冲耦合振荡器i在第

轮监听状态中一直未收到脉冲信号，则第i个脉冲耦合振荡器i在内部时间为

时刻结束监听状态并进入第

轮激发状态；若第i个脉冲耦合振荡器i在第

轮监听状态中收到一个脉冲信号，则第i个脉冲耦合振荡器i在收到脉冲信号的同时结束监听状态，将内部时间设定为

并进入激发状态；From the monitoring state to the exciting state: the i-th pulse coupled oscillator i has an internal time of

Enter the moment

Round monitoring state; if the i-th pulse coupled oscillator i in the

If no pulse signal is received in the round monitoring state, the i-th pulse coupled oscillator i will be

End the monitoring state and enter the

round excitation state; if the i-th pulse coupled oscillator i is in the

When a pulse signal is received in the round monitoring state, the i-th pulse coupled oscillator i ends the monitoring state at the same time as receiving the pulse signal, and sets the internal time to

and enters the excited state;

时刻进入第

轮激发状态；当第i个脉冲耦合振荡器i在第

轮激发状态发出一个脉冲信号后，第i个脉冲耦合振荡器i设定此时内部时间为

并同时结束激发状态，进入第

轮空闲状态。From the excited state to the idle state: the i-th pulse coupled oscillator i has an internal time of

Enter the moment

round excitation state; when the i-th pulse coupled oscillator i is in the

After the wheel excitation state sends a pulse signal, the i-th pulse coupled oscillator i sets the internal time at this time to

At the same time, the excitation state ends and the

Wheel idle state.

Furthermore, if multiple pulse coupled oscillators send out pulse signals earliest at the same time, the multiple pulse coupled oscillators that send out pulse signals earliest at the same time are collectively defined as initial leaders.

Furthermore, the wireless network is a wireless sensor network.

Furthermore, the wireless sensor network is a general connected network structure.

Furthermore, in the general interconnected network structure, any pulse coupled oscillator has a direct or indirect path to reach another pulse coupled oscillator.

The advantages of the present invention over the prior art are: a new pulse-coupled oscillator model is disclosed: three states are introduced into the pulse-transmitting and receiving pulse mechanism of the pulse-coupled oscillator, and a new type of non-negative phase jump function is designed. Based on the above new pulse-coupled oscillator model, a new time synchronization mechanism is proposed. The above new pulse-coupled oscillator model and time synchronization mechanism greatly expand the application scope of time synchronization based on pulse-coupled oscillators in wireless sensor networks in the following three aspects:

1) In terms of network topology, the topology of wireless sensor networks can achieve time synchronization with only a general connectivity structure;

之间任意选取。此外，当节点间的耦合强度小于1时，网络可在有限时间内达成时间同步，有效提升了网络达成时间同步的速度；2) In terms of the coupling strength between network nodes, the coupling strength between network nodes can be

In addition, when the coupling strength between nodes is less than 1, the network can achieve time synchronization within a limited time, which effectively improves the speed at which the network achieves time synchronization;

3) In terms of the initial phase distribution of the pulse coupled oscillator, even if the initial phase of the pulse coupled oscillator in the network is arbitrarily distributed, the time synchronization of the wireless sensor network can still be achieved with certainty.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram showing the phase variation of a pulse coupled oscillator running on a unit circle.

FIG. 2 is a schematic diagram of a non-negative phase jump function of the present invention.

FIG3 is a schematic diagram of a pulse coupled oscillator state switching.

FIG. 4 is a schematic diagram showing the structure of a general connected network.

FIG. 5 is a schematic diagram of dividing nodes of the network shown in FIG. 4 according to network node division rules.

DETAILED DESCRIPTION

The present invention is described in detail below in conjunction with the embodiments and drawings, but it should be understood that the embodiments and drawings are only used to exemplify the present invention and do not constitute any limitation on the protection scope of the present invention. All reasonable changes and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

、一个与内部时间

相关的相位变量

以外，都具有三种状态：空闲状态、监听状态、激发状态。First, the present invention constructs a new type of pulse coupled oscillator model. In this model, each pulse coupled oscillator has an internal time

, one with internal time

Related phase variables

In addition, there are three states: idle state, listening state, and excited state.

。相位变量

在单位圆上以ω=1rad/s的恒定速度从0向临界值2π rad做圆周运动，该单位圆上，0点与2π rad点重合，该单位圆表示预先设定的时长。相位变量

在单位圆上以ω=1rad/s的恒定速度运行一周所需的时间为脉冲耦合振荡器的自然振荡周期

。当相位变量

运行到临界值2π rad时，脉冲耦合振荡器将相位变量

重置为0 rad，并根据此时脉冲耦合振荡器所处状态决定是否发出脉冲信号。As shown in Figure 1, each pulse coupled oscillator has a phase variable

. Phase variable

It moves in a circle from 0 to the critical value 2π rad at a constant speed of ω=1rad/s on the unit circle. On the unit circle, the 0 point coincides with the 2π rad point. The unit circle represents the preset duration. Phase variable

The time required for a pulse coupled oscillator to run one circle at a constant speed of ω = 1 rad/s is the natural oscillation period of the pulse coupled oscillator.

When the phase variable

When the pulse coupled oscillator reaches the critical value of 2π rad, the phase variable

Reset to 0 rad, and decide whether to send a pulse signal based on the state of the pulse coupled oscillator at this time.

When the pulse coupled oscillator receives a pulse signal, the pulse coupled oscillator will decide whether to perform a phase jump according to the state of the pulse coupled oscillator at that time.

The operating rules of the pulse coupled oscillator in three states are as follows:

1) When the pulse coupled oscillator is in the idle state, the pulse coupled oscillator does not send out a pulse signal; when the pulse coupled oscillator receives an external pulse signal in the idle state, the pulse coupled oscillator does not perform a phase jump. After the idle state ends, the pulse coupled oscillator enters the listening state.

2) When the pulse coupled oscillator is in the monitoring state, the pulse coupled oscillator only monitors whether there is a pulse signal input without sending a pulse signal. When the pulse coupled oscillator receives a pulse signal in the monitoring state, the pulse coupled oscillator performs a phase jump according to the phase jump function and the coupling strength. At the same time, the pulse coupled oscillator ends the monitoring state and enters the excitation state.

3) When the pulse coupled oscillator is in the excited state, if the pulse coupled oscillator receives a pulse signal, the pulse coupled oscillator performs a phase jump according to the phase jump function and the coupling strength. When the pulse coupled oscillator is in the excited state and the phase variable runs to the critical value 2π rad, the pulse coupled oscillator sends a pulse signal to reset the phase variable to 0, and at the same time ends the excited state and enters the idle state.

When the pulse coupled oscillator receives a pulse signal in the monitoring state or the excitation state, the pulse coupled oscillator will perform a phase jump according to the following formula:

为脉冲耦合振荡器在t时刻收到脉冲信号时的相位，

为相位跳变函数，

为耦合强度，

为相位跳变后脉冲耦合振荡器的相位。

is the phase of the pulse coupled oscillator when it receives the pulse signal at time t,

is the phase jump function,

is the coupling strength,

is the phase of the pulse coupled oscillator after the phase jump.

：即当脉冲耦合振荡器的相位

等于2π rad时，相位跳变函数

的值为0；当脉冲耦合振荡器的相位

在[0,2π)之间时，相位跳变函数值为正数。在此类相位跳变函数下，脉冲耦合振荡器仅能产生非负的相位跳变。在本发明中，选用如图2所示的非负相位跳变函数

：The present invention also designs a type of non-negative phase jump function

：When the phase of the pulse coupled oscillator

When it is equal to 2π rad, the phase jump function

The value is 0; when the phase of the pulse coupled oscillator

When the phase jump function is between [0,2π), the value of the phase jump function is positive. Under this type of phase jump function, the pulse coupled oscillator can only produce non-negative phase jumps. In the present invention, the non-negative phase jump function shown in FIG2 is selected.

:

The present invention considers a general connected network structure. In a general connected network structure, any node has a direct or indirect path to another node. In the present invention, each node represents a pulse coupled oscillator. Based on the above definition of a general connected network structure, it can be seen that fully connected, spanning tree, chain, ring and other structures are all special cases of a general connected network structure.

Definition of time synchronization: When the phase of all pulse-coupled oscillators in the network remains the same as the internal time, the entire network achieves time synchronization.

Based on the above pulse coupled oscillator model, the present invention proposes a time synchronization mechanism, which mainly includes the following four steps:

Step 1: Start the time synchronization mechanism

Since the time synchronization of the sensor network has not been achieved, each pulse-coupled oscillator in the network cannot guarantee to start the time synchronization mechanism at the same time. Therefore, in the present invention, each pulse-coupled oscillator in the network is allowed to start the time synchronization mechanism within a time period of (N -1 )T , where T is the natural oscillation period of the pulse-coupled oscillator, and N is the number of pulse-coupled oscillators, that is, the number of nodes in the network. Consider a wireless sensor network composed of N pulse-coupled oscillators. The initial phase of the pulse-coupled oscillator i ( i=1, 2, …,N ) can be arbitrarily distributed. After the pulse-coupled oscillator starts the time synchronization mechanism, it immediately enters the idle state and sets its internal time to 0.

Step 2: Set the pulse coupled oscillator state switching rules

After the pulse coupled oscillator starts the time synchronization mechanism, it first enters the idle state, and then switches in sequence among the idle state, the monitoring state, and the exciting state according to the following state switching rules.

时刻进入第

轮空闲状态，

=1, 2, 3, …。在内部时间为

=

+NT时刻结束第

轮空闲状态空闲状态，进入第

轮监听状态；a) From idle state to listening state: the pulse coupled oscillator i is internally

Enter the moment

Wheel idle state,

=1, 2, 3, … . The internal time is

=

+ NT time ends

Idle state, enter the idle state

Wheel monitoring status;

在内部时间为

时刻进入第

轮监听状态。若脉冲耦合振荡器

在第

轮监听状态中一直未收到脉冲信号，则脉冲耦合振荡器

在内部时间为

=

+NT时刻结束监听状态，进入第

轮激发状态；若脉冲耦合振荡器

在第

轮监听状态中收到一个脉冲信号，则脉冲耦合振荡器

在收到脉冲信号的同时结束监听状态，将内部时间设定为

=

+NT并进入激发状态。b) From the monitoring state to the exciting state: pulse coupled oscillator

The internal time is

Enter the moment

If the pulse coupled oscillator

In the

If no pulse signal is received in the round monitoring state, the pulse coupled oscillator

The internal time is

=

+ End the monitoring state at NT time and enter the

Wheel excitation state; if the pulse coupled oscillator

In the

When a pulse signal is received in the round monitoring state, the pulse coupled oscillator

When the pulse signal is received, the monitoring state ends and the internal time is set to

=

+ NT and enter the excited state.

在内部时间为

时刻进入第

轮激发状态。当脉冲耦合振荡器

在第

轮激发状态发出一个脉冲信号后，脉冲耦合振荡器

将此时内部时间设定为

=

并同时结束激发状态，进入第

+1轮空闲状态；c) From the excited state to the idle state: pulse coupled oscillator

The internal time is

Enter the moment

When the pulse coupled oscillator

In the

After the wheel excitation state sends a pulse signal, the pulse coupled oscillator

Set the internal time to

=

At the same time, the excitation state ends and the

+1 round of idle state;

在各个状态间切换的示意图。Figure 3 shows the pulse coupled oscillator

Schematic diagram of switching between various states.

Step 3: Set network node division rules

After the sensor network starts the time synchronization mechanism, the pulse-coupled oscillator that sends out the pulse signal earliest is called the initial leader. If multiple pulse-coupled oscillators send out pulse signals earliest at the same time, they are collectively called the initial leader. The pulse-coupled oscillator that is directly connected to the initial leader and does not belong to the initial leader is called the first-order follower; the pulse-coupled oscillator that is directly connected to the first-order follower and does not belong to the initial leader and the first-order follower is called the second-order follower; and so on, at most M -order followers are defined, M ≤ N -1.

Subsequently, if an m- th order follower ( m =1, 2, …, M) achieves time synchronization with the initial leader, the m- th order follower is upgraded to an m- th order leader. The initial leader and the m- th order leader are collectively referred to as leaders, and the remaining order followers are collectively referred to as followers.

Taking the general connected network shown in FIG4 as an example, the number of nodes in the network is N = 10. Assuming that node 1 and node 7 are the initial leaders, according to the network node division rule, M = 3-order followers can be defined. FIG5 shows a schematic diagram of node division of the general connected network shown in FIG4. Node 1 and node 7 are the initial leaders.

The feasibility of the time synchronization process of the present invention is analyzed as follows:

Firstly, the characteristics of the network under the novel pulse coupled oscillator model and time synchronization mechanism are analyzed.

。由于本发明允许网络中的脉冲耦合振荡器在一个长度为(N-1)T的时间段内启动时间同步机制，于是在

时刻，可能出现以下两种情况：Let pulse coupled oscillator l be any initial leader. After pulse coupled oscillator l starts the time synchronization mechanism, it enters the first round of idle state and sets the internal time to 0. According to the state switching rule,

Since the present invention allows the pulse coupled oscillator in the network to start the time synchronization mechanism within a time period of (N-1)T,

At this moment, the following two situations may occur:

1) All pulse coupled oscillators have started the time synchronization mechanism;

2) Some pulse-coupled oscillators have not yet started the time synchronization mechanism, while some pulse-coupled oscillators have already started the time synchronization mechanism;

时刻由第一轮空闲状态进入第一轮监听状态。由于网络中全部脉冲耦合振荡器在长度为(N-1)T的时间段内启动时间同步机制，因此在

时刻，全部脉冲耦合振荡器都已经启动时间同步机制。After NT time, the pulse coupled oscillator l

At this moment, the first round of idle state enters the first round of listening state. Since all pulse-coupled oscillators in the network start the time synchronization mechanism within a time period of (N-1)T,

At this moment, all pulse-coupled oscillators have started the time synchronization mechanism.

时刻由第一轮监听状态进入第一轮激发状态。由于全部脉冲耦合振荡器在

时刻已经启动时间同步机制，并且空闲状态时长固定为NT，可知全部脉冲耦合振荡器在

时刻已经结束空闲状态，处于监听状态或激发状态。It is known that the initial leader sends out a pulse signal at the same time after starting the time synchronization mechanism. According to the state switching rule, the initial leader does not receive a pulse signal during its first round of listening state. Therefore, the first round of listening state of the pulse-coupled oscillator l lasts for NT time.

At this moment, the first round of monitoring state enters the first round of excitation state.

The time synchronization mechanism has been started at this moment, and the idle state duration is fixed at NT. It can be seen that all pulse-coupled oscillators are

The idle state has ended and the device is in the listening state or the excited state.

时刻达成时间同步。Since the pulse coupled oscillator 1 and other initial leaders send out pulse signals at the same time, according to the pulse coupled oscillator model and state switching rules in the present invention, it can be known that the initial leaders reset the phase from 2π rad to 0 at the same time, set the internal time to 2NT, end the first round of excitation state and enter the second round of idle state. At this time, all initial leaders have the same phase 0 and the same internal time 2NT.

Achieve time synchronization at all times.

时刻都处于监听状态或激发状态，且在脉冲耦合振荡器l发出脉冲信号前未发出脉冲信号，因此网络中跟随者在

时刻均处于第一轮监听状态或第一轮激发状态。Since all followers in the network are

It is always in the listening state or the exciting state, and does not send out a pulse signal before the pulse coupled oscillator l sends out a pulse signal, so the follower in the network is

It is always in the first round of monitoring state or the first round of excitation state.

时刻，脉冲耦合振荡器j ₁ 处于监听状态或激发状态。若脉冲耦合振荡器j ₁ 处于监听状态，则它进行相位跳变并同时进入激发状态；若脉冲耦合振荡器j ₁ 处于激发状态，则它仅进行相位跳变。根据相位跳变函数与耦合强度，脉冲耦合振荡器j ₁ 跳变后的相位为：Let the pulse coupled oscillator j ₁ be an arbitrary 1st order follower.

At the moment, the pulse coupled oscillator j ₁ is in the listening state or the exciting state. If the pulse coupled oscillator j ₁ is in the listening state, it performs a phase jump and enters the exciting state at the same time; if the pulse coupled oscillator j ₁ is in the exciting state, it only performs a phase jump. According to the phase jump function and the coupling strength, the phase of the pulse coupled oscillator j ₁ after the jump is:

。若

，则脉冲耦合振荡器j ₁ 在

时刻将相位由2π rad重置为0，将内部时间设定为

，结束第一轮激发状态并进入第二轮空闲状态。此时脉冲耦合振荡器j ₁ 与全部初始领导者具有相同的相位0与相同的内部时间2NT，脉冲耦合振荡器j ₁ 与领导者在

时刻达成时间同步，脉冲耦合振荡器j ₁ 升级成为1阶领导者。According to the above formula, we can know

.like

, then the pulse coupled oscillator j ₁ is

At this moment, the phase is reset from 2π rad to 0, and the internal time is set to

, ending the first round of excitation state and entering the second round of idle state. At this time, the pulse-coupled oscillator j ₁ has the same phase 0 and the same internal time _2NT as all the initial leaders.

Time synchronization is achieved at all times, and the pulse-coupled oscillator j ₁ is upgraded to become the first-order leader.

，脉冲耦合振荡器j ₁ 在

时刻后必处于激发状态。其相位变量以ω=1rad/s的速度从

向2π rad运行。在此期间，若脉冲耦合振荡器j ₁ 收到外部脉冲信号，则脉冲耦合振荡器j ₁ 会再次进行非负相位调整。因此，经过至多

时间，脉冲耦合振荡器j ₁ 的相位将运行到2π rad。由于脉冲耦合振荡器j ₁ 为任意1阶跟随者，可知，在

时间内，全部1阶跟随者必然发出脉冲信号并且进入第二轮空闲状态。like

, pulse coupled oscillator j ₁ in

After the moment, it must be in the excited state. Its phase variable changes from

Runs towards 2π rad. During this period, if the pulse coupled oscillator j ₁ receives an external pulse signal, the pulse coupled oscillator j ₁ will perform non-negative phase adjustment again. Therefore, after at most

At this time, the phase of the pulse coupled oscillator j ₁ will reach 2π rad. Since the pulse coupled oscillator j ₁ is an arbitrary first-order follower, it can be seen that at

Within this time, all first-order followers must send out pulse signals and enter the second round of idle state.

时间内收到由1阶跟随者发出的脉冲信号，若脉冲耦合振荡器j ₂ 在收到1阶跟随者发出的脉冲信号时处于监听状态，则它进行相位跳变并同时进入激发状态；若脉冲耦合振荡器j ₂ 处于激发状态，则它仅进行相位跳变；若脉冲耦合振荡器j ₂ 处于空闲状态，则说明脉冲耦合振荡器j ₂ 已在收到1阶跟随者发出的脉冲信号前发出脉冲信号并进入第二轮空闲状态。通过对脉冲耦合振荡器j ₂ 的相位跳变与演化过程分析可知，在

时间内，全部2阶跟随者必然发出脉冲信号并且进入第二轮空闲状态。Let the pulse coupled oscillator j ₂ be an arbitrary order follower, we know that the pulse coupled oscillator j ₂ must be

The pulse signal sent by the first-order follower is received within the time. If the pulse-coupled oscillator j ₂ is in the listening state when it receives the pulse signal sent by the first-order follower, it performs a phase jump and enters the excited state at the same time; if the pulse-coupled oscillator j ₂ is in the excited state, it only performs a phase jump; if the pulse-coupled oscillator j ₂ is in the idle state, it means that the pulse-coupled oscillator j ₂ has sent a pulse signal before receiving the pulse signal sent by the first-order follower and entered the second round of idle state. Through the analysis of the phase jump and evolution process of the pulse-coupled oscillator j ₂ , it can be seen that in

Within this time, all second-order followers must send out pulse signals and enter the second round of idle state.

时间内进入第二轮空闲状态。由于空闲状态的时长为NT，领导者在

时刻依然处于空闲状态，因此跟随者发出的脉冲信号不能影响领导者的相位运行。Summarizing the above analysis process, we can know that: since the sensor network has at most M≤N-1 followers, all followers will be in

The leader enters the second round of idle state within NT.

It is still in idle state at all times, so the pulse signal sent by the follower cannot affect the phase operation of the leader.

时刻最先进入第二轮空闲状态。由于空闲状态的时长为NT，领导者在

时刻最先进入监听状态。在领导者处于监听状态期间，由于网络中的脉冲耦合振荡器都处于空闲或监听状态，全部脉冲耦合振荡器均不发出脉冲信号。因此，领导者脉冲耦合振荡器的第二轮监听状态持续NT时长，在

时刻首先进入第二轮激发状态。由于空闲状态时长为NT，可知全部跟随者在

时刻已经结束第二轮空闲状态，处于监听状态。Leaders in

The leader enters the second round of idle state first at time. Since the idle state lasts for NT, the leader

When the leader is in the listening state, all pulse-coupled oscillators in the network are in the idle or listening state, and no pulse-coupled oscillators send out pulse signals. Therefore, the second round of listening state of the leader pulse-coupled oscillator lasts for NT time.

At this moment, the second round of excitation state is entered first. Since the idle state duration is NT, it can be known that all followers are

The second round of idle state has ended and the system is in the listening state.

时刻由2π rad重置为0，因此在2NT时长的自由运行后，脉冲耦合振荡器l的相位在

时刻也将运行到2π rad并重置为0。由于此时脉冲耦合振荡器已处于第二轮激发状态，因此脉冲耦合振荡器l发出一个脉冲信号。考虑到领导者脉冲耦合振荡器已达成时间同步，可知在

时刻，全部领导者脉冲耦合振荡器都已进入第二轮激发状态，将相位由2π rad重置为0，发出脉冲信号，将内部时间重置为

，并进入第三轮空闲状态。Since the leader's phase is

The moment is reset to 0 by 2π rad, so after a free run of 2NT, the phase of the pulse-coupled oscillator l is

At this moment, the pulse-coupled oscillator will also run to 2π rad and reset to 0. Since the pulse-coupled oscillator is already in the second round of excitation, the pulse-coupled oscillator l sends a pulse signal. Considering that the leader pulse-coupled oscillator has achieved time synchronization, it can be known that at

At this moment, all leader pulse-coupled oscillators have entered the second round of excitation, reset the phase from 2π rad to 0, send out a pulse signal, and reset the internal time to

, and enter the third round of idle state.

Based on the above analysis, it can be seen that the leader pulse-coupled oscillator first enters the second round of excitation state, and sends out a pulse signal while entering the excitation state, entering the third round of idle state. Repeating the above analysis process, it can be seen that under the new pulse-coupled oscillator model and time synchronization mechanism, this network has the following properties:

i. In each round of state cycle, the leader always sends out a pulse signal first and enters the next round of idle state;

ii. When the leader sends a pulse signal, the follower is in the listening state or the exciting state;

iii. Once the leader achieves time synchronization, it will always maintain time synchronization.

Next, the synchronization process between the leader and the follower is described mathematically. The present invention will prove that the wireless sensor network will achieve time synchronization within a limited time.

时刻最先发出脉冲信号，将相位由2πrad重置为0，将内部时间设定为2NT，结束第一轮激发状态并进入第二轮空闲状态。此时全部初始领导者具有相同的相位0与相同的内部时间2NT，初始领导者在

时刻达成时间同步。Based on the previous analysis process, we know that the initial leader

The first pulse signal is sent at the moment, the phase is reset from 2πrad to 0, the internal time is set to 2NT, the first round of excitation state ends and the second round of idle state begins. At this time, all initial leaders have the same phase 0 and the same internal time 2NT. The initial leader

Achieve time synchronization at all times.

时刻，任意1阶跟随者脉冲耦合振荡器j ₁ 处于监听状态或激发状态。若脉冲耦合振荡器j ₁ 处于监听状态，则它进行相位调整并同时进入激发状态；若脉冲耦合振荡器j ₁ 处于激发状态，则它仅进行相位跳变。根据相位跳变函数与耦合强度，脉冲耦合振荡器j ₁ 跳变后的相位为：exist

At the moment, any 1-order follower pulse-coupled oscillator j ₁ is in the listening state or the exciting state. If the pulse-coupled oscillator j ₁ is in the listening state, it performs phase adjustment and enters the exciting state at the same time; if the pulse-coupled oscillator j ₁ is in the exciting state, it only performs phase jump. According to the phase jump function and the coupling strength, the phase of the pulse-coupled oscillator j ₁ after the jump is:

。若

，则脉冲耦合振荡器j ₁ 在

时刻将相位由2πrad重置为0，将内部时间设定为

，结束第一轮激发状态并进入第二轮空闲状态。此时脉冲耦合振荡器j ₁ 与全部初始领导者具有相同的相位0与相同的内部时间2NT，脉冲耦合振荡器j ₁ 与初始领导者在

时刻达成时间同步，脉冲耦合振荡器j ₁ 升级成为1阶领导者。According to the above formula, we can know

.like

, then the pulse coupled oscillator j ₁ is

At this moment, the phase is reset from 2πrad to 0, and the internal time is set to

, ending the first round of excitation state and entering the second round of idle state. At this time, the pulse-coupled oscillator j ₁ has the same phase 0 and the same internal time _2NT as all the initial leaders.

Time synchronization is achieved at all times, and the pulse-coupled oscillator j ₁ is upgraded to become the first-order leader.

，则脉冲耦合振荡器j ₁ 在

时刻后必处于激发状态。其相位变量以ω=1rad/s的速度从

向2π rad运行。在此期间，若脉冲耦合振荡器j ₁ 收到外部脉冲信号，则脉冲耦合振荡器j ₁ 会再次进行非负相位调整，缩小与领导者之间的相位差。因此，经过至多（1-ε）T时间，脉冲耦合振荡器j ₁ 的相位将运行到2π rad。由于脉冲耦合振荡器j ₁ 为任意1阶跟随者，可知，在

]时间内，全部1阶跟随者必然发出脉冲信号并且进入第二轮空闲状态。由于领导者在

时刻进入第二轮空闲状态，在

期间，领导者的相位变量以ω=1rad/s的恒定速度在圆周上从0向2πrad运行而不受脉冲信号的影响。因此，在

时刻，领导者与1阶跟随者的相位全部位于[0,（1-ε）2π]之间。此时，领导者与1阶跟随者的相位差的上界为（1-ε）2π rad。like

, then the pulse coupled oscillator j ₁ is

After the moment, it must be in the excited state. Its phase variable changes from

Runs to 2π rad. During this period, if the pulse coupled oscillator j ₁ receives an external pulse signal, the pulse coupled oscillator j ₁ will perform non-negative phase adjustment again to reduce the phase difference with the leader. Therefore, after at most (1- ε ) T time, the phase of the pulse coupled oscillator j ₁ will run to 2π rad. Since the pulse coupled oscillator j ₁ is an arbitrary 1st order follower, it can be seen that in

] time, all first-order followers must send out pulse signals and enter the second round of idle state.

Enter the second round of idle state at any time.

During this period, the phase variable of the leader runs from 0 to 2πrad on the circumference at a constant speed of ω=1rad/s without being affected by the pulse signal.

At this moment, the phases of the leader and the first-order followers are all between [0, (1-ε) 2π]. At this time, the upper bound of the phase difference between the leader and the first-order followers is (1-ε) 2π rad.

时刻后都处于第二轮空闲状态，领导者与1阶跟随者之间的相位差的上界在下一次领导者发出脉冲信号前保持不变。Since the leader and the first-order follower are

After time, they are in the second round of idle state, and the upper bound of the phase difference between the leader and the first-order follower remains unchanged before the next leader sends a pulse signal.

时刻第二次发出脉冲信号，此时，脉冲耦合振荡器j ₁ 处于监听状态或激发状态，其相位变量满足下式：In the second round of state switching, the initial leader

The second pulse signal is sent out at time , at this time, _the pulse coupled oscillator j1 is in the listening state or the exciting state, and its phase variable satisfies the following formula:

If the pulse coupled oscillator j ₁ is in the listening state, it performs phase adjustment and enters the exciting state at the same time; if the pulse coupled oscillator j ₁ is in the exciting state, it only performs phase jump. According to the phase jump function and the coupling strength, the phase of the pulse coupled oscillator j ₁ after the jump is:

。若

，则脉冲耦合振荡器j ₁ 与初始领导者在

时刻达成时间同步，脉冲耦合振荡器j ₁ 升级成为1阶领导者。According to the above formula, we can know

.like

, then the pulse coupled oscillator j ₁ and the initial leader are

Time synchronization is achieved at all times, and the pulse-coupled oscillator j ₁ is upgraded to become the first-order leader.

，则初始领导者与1阶跟随者的相位差的上界在

时刻为（1-2ε）2π rad。like

, then the upper bound of the phase difference between the initial leader and the first-order follower is

The time is (1-2ε)2π rad.

个脉冲信号后，全部1阶跟随者将升级成为1阶领导者，与领导者达成时间同步，其中

为向上取整函数。因此，最晚在

时刻，全部1阶跟随者将升级成为1阶领导者，与领导者达成时间同步。Based on the above analysis, it can be concluded that the initial leader sends at most

After a pulse signal, all 1st-order followers will be upgraded to 1st-order leaders and achieve time synchronization with the leader.

is a round-up function. Therefore, at the latest

At this moment, all level 1 followers will be upgraded to level 1 leaders and achieve time synchronization with the leader.

Since ε∈(0,1], we know that k is a bounded positive integer. Therefore, within a finite time, all first-order followers achieve time synchronization with the leader.

时刻，全部1阶领导者与初级领导者达成时间同步并同s时发出脉冲信号。此时，2阶跟随者收到脉冲信号并处于监听状态或激发状态。若任意2阶跟随者脉冲耦合振荡器j ₂ 处于监听状态，则它进行相位调整并同时进入激发状态；若脉冲耦合振荡器j ₂ 处于激发状态，则它仅进行相位跳变。根据相位跳变函数与耦合强度，脉冲耦合振荡器j ₂ 跳变后的相位为：exist

At time s, all 1st-order leaders achieve time synchronization with the primary leader and send out pulse signals at the same time. At this time, the 2nd-order followers receive the pulse signal and are in the listening state or the exciting state. If any 2nd-order follower pulse-coupled _oscillator j2 is in the listening state, it performs phase adjustment and enters the exciting state at the same time; if the pulse-coupled _oscillator j2 is in the exciting state, it only performs phase jump. According to the phase jump function and the coupling strength, the phase of the pulse-coupled oscillator j2 after the _jump is:

。若

，则脉冲耦合振荡器j ₂ 与领导者在

时刻达成时间同步，脉冲耦合振荡器j ₂ 升级成为2阶领导者。According to the above formula, we can know

.like

, then _the pulse coupled oscillator j2 and the leader are

Time synchronization is achieved at all times, and the pulse-coupled oscillator j ₂ is upgraded to become a 2nd-order leader.

，则领导者与2阶跟随者的相位差的上界在

时刻为（1-ε）2π rad。like

, then the upper bound of the phase difference between the leader and the second-order follower is

The time is (1-ε)2π rad.

开始，领导者发出至多

个脉冲信号后，全部2阶跟随者都将升级成为2阶领导者，与领导者达成时间同步。因此，在

时刻，全部2阶跟随者升级成为2阶领导者，与初级领导者达成时间同步。Summarizing the above analysis, we can conclude that:

Initially, the leader sends out at most

After a pulse signal, all second-order followers will be upgraded to second-order leaders and achieve time synchronization with the leader.

At this moment, all Level 2 followers are upgraded to Level 2 leaders and achieve time synchronization with the primary leader.

时刻，全部跟随者升级成为领导者，与初级领导者达成时间同步。由于k为一个有界正整数，(N-1)k同样为一个有界正整数。因此，可得知，在有限时间内网络中全部脉冲耦合振荡器将达成时间同步。Since there are at most M≤N-1 followers in the network, we know that at the latest

At this moment, all followers are upgraded to become leaders and achieve time synchronization with the primary leader. Since k is a bounded positive integer, (N -1 )k is also a bounded positive integer. Therefore, it can be known that within a finite time, all pulse-coupled oscillators in the network will achieve time synchronization.

The above applications are only some implementation methods of the present application. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present application, and these all belong to the protection scope of the present application.

Claims (9)

1. A wireless network time synchronization method based on a pulse coupled oscillator model, characterized in that the wireless network includes a plurality of pulse coupled oscillators, all of which are directly or indirectly connected; The pulse coupled oscillator model is as follows: Each pulse coupled oscillator has an internal time

, a phase variable related to the internal time

, as well as three states: idle state, monitoring state and exciting state; the phase variable of each pulse-coupled oscillator moves from 0 to the critical value at a constant speed. When the phase variable reaches the critical value, the pulse-coupled oscillator resets the phase variable to 0 and decides whether to send a pulse signal according to the state; when each pulse-coupled oscillator receives an external pulse signal, it decides whether to perform a phase jump according to the state; The wireless network time synchronization method is as follows: all pulse coupled oscillators start the time synchronization mechanism within a preset time period. After the pulse coupled oscillators start the time synchronization mechanism, they first enter the idle state and switch between the idle state, the listening state, and the exciting state in turn. The wireless network defines the pulse coupled oscillator that sends out the pulse signal first after starting the time synchronization mechanism as the initial leader; and divides the remaining pulse coupled oscillators into multiple-order followers from the first-order follower to the M-order follower according to their connection relationship with the initial leader; In the process of switching between the idle state, the monitoring state, and the exciting state of all pulse-coupled oscillators in the wireless network, the first-order followers to the M-order followers successively achieve time synchronization with the initial leader; In the pulse coupled oscillator model, the operating rules of each pulse coupled oscillator in the idle state, the monitoring state, and the exciting state are: When the pulse coupled oscillator is in an idle state, the pulse coupled oscillator does not send out a pulse signal; when the pulse coupled oscillator receives an external pulse signal in the idle state, the pulse coupled oscillator does not perform a phase jump; after the idle state ends, the pulse coupled oscillator enters a listening state; When the pulse coupled oscillator is in the monitoring state, the pulse coupled oscillator only monitors whether there is a pulse signal input without sending a pulse signal; when the pulse coupled oscillator receives a pulse signal in the monitoring state, the pulse coupled oscillator performs a phase jump according to the phase jump function and the coupling strength, and at the same time ends the monitoring state and enters the exciting state; When the pulse coupled oscillator is in an excited state, after receiving a pulse signal, the pulse coupled oscillator performs a phase jump according to the phase jump function and the coupling strength; when the pulse coupled oscillator is in an excited state and the phase variable reaches a critical value, the pulse coupled oscillator sends a pulse signal and resets the phase variable to 0, and at the same time ends the excited state and enters the idle state. 2. A wireless network time synchronization method based on a pulse coupled oscillator model according to claim 1, characterized in that when the pulse coupled oscillator receives an external pulse signal in a listening state or an exciting state, the pulse coupled oscillator performs a phase jump according to the following method:

In the formula,

is the phase of the pulse coupled oscillator when it receives the pulse signal at time t,

is the phase jump function,

is the coupling strength,

is the phase of the pulse coupled oscillator after the phase jump. 3. A wireless network time synchronization method based on a pulse coupled oscillator model according to claim 2, characterized in that the phase jump function

for:

. 4. A wireless network time synchronization method based on a pulse coupled oscillator model according to claim 3, characterized in that the remaining pulse coupled oscillators are divided into multiple orders of followers from 1st order followers to Mth order followers according to their connection relationship with the initial leader, specifically: A pulse coupled oscillator directly connected to an initial leader and not belonging to the initial leader is defined as a first-order follower; a pulse coupled oscillator directly connected to a first-order follower and not belonging to the initial leader and the first-order follower is defined as a second-order follower, and the pulse coupled oscillators in the wireless network are divided into a total of M-order followers in turn, where M≤N-1; The initial leader first achieves time synchronization within a finite time; then, followers from order 1 to order M successively achieve time synchronization with the initial leader within a finite time. 5. A wireless network time synchronization method based on a pulse coupled oscillator model according to claim 4, characterized in that after the time synchronization mechanism is started, the pulse coupled oscillator switches between the idle state, the listening state, and the excited state in turn in a cyclic process as follows: Entering the listening state from the idle state: The i-th pulse coupled oscillator i is internally

Enter the moment

The wheel is in idle state; the internal time is

The end of time

Idle state, enter the idle state

Wheel monitoring status;

is the internal time of the pulse coupled oscillator,

is the number of pulse coupled oscillators in the wireless network,

is the natural oscillation period of the pulse coupled oscillator,

is a natural number greater than or equal to 1; From the monitoring state to the exciting state: the i-th pulse coupled oscillator i has an internal time of

Enter the moment

Round monitoring state; if the i-th pulse coupled oscillator i in the

If no pulse signal is received in the round monitoring state, the i-th pulse coupled oscillator i will be

End the monitoring state and enter the

round excitation state; if the i-th pulse coupled oscillator i in the

When a pulse signal is received in the round monitoring state, the i-th pulse coupled oscillator i ends the monitoring state at the same time as receiving the pulse signal, and sets the internal time to

and enters the excited state; From the excited state to the idle state: the i-th pulse coupled oscillator i has an internal time of

Enter the moment

round excitation state; when the i-th pulse coupled oscillator i is in the

After the wheel excitation state sends a pulse signal, the i-th pulse coupled oscillator i sets the internal time at this time to

At the same time, the excitation state ends and the

Wheel idle state. 6. According to the wireless network time synchronization method based on the pulse coupled oscillator model described in claim 1, it is characterized in that if multiple pulse coupled oscillators send out pulse signals at the same time, the multiple pulse coupled oscillators that send out pulse signals at the same time are collectively defined as the initial leaders. 7 . The wireless network time synchronization method based on a pulse coupled oscillator model according to claim 6 , wherein the wireless network is a wireless sensor network. 8 . The wireless network time synchronization method based on a pulse coupled oscillator model according to claim 7 , wherein the wireless sensor network is a general connected network structure. 9. A wireless network time synchronization method based on a pulse coupled oscillator model according to claim 8, characterized in that in the generally connected network structure, any pulse coupled oscillator has a direct or indirect path to reach another pulse coupled oscillator.

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