Method for establishing wireless synchronous network

Abstract

The invention provides a method for establishing a clock synchronization network, which comprises the following steps of: dividing areas in advance according to spatial positions, determining the priority of the areas and the priority of nodes in the areas, dividing the priority of the areas according to the degree of closeness with a root node area, the closer the other areas are to the root node area, the higher the priority of the area is, nodes in the same node area are divided into area internal priorities to establish a distributed synchronous network, different areas can keep synchronous, and when the areas lose synchronization, local area network clock synchronization can still be kept in the areas, so that forced dependence on the root node is avoided, and the reliability of the local area network is improved. And the robustness of the system is improved.

Description

Technical Field

[0001] The invention relates to the field of wireless positioning, and in particular to a method for establishing a wireless synchronization network. Background Art

[0002] The relative position of the tag and the base station is obtained by the flight time and phase difference of the radio wave in the air. In order to increase the concurrent capacity of the tag, it is usually necessary to establish a positioning network with wireless clock synchronization. Through the clock synchronization between base stations and base stations, and the clock synchronization between base stations and tags, the tags transmit signals according to the specified time slots, which can effectively reduce the probability of collision of tag transmission signals, thereby increasing the system capacity. The existing synchronization method and process between base stations are as follows:

[0003] First, plan the clock tree. Each base station is a node in the clock tree. The base station clock tree contains a root node, multiple child nodes, and multiple leaf nodes. The clock of the root node base station is the benchmark of the entire clock tree. The child node clock of the root node is synchronized with the root node clock, and the child node clock is synchronized with its parent node clock, ultimately achieving synchronization between nodes in the entire clock tree.

[0004] The root node base station broadcasts beacon frames periodically. Before the child node synchronizes with the clock tree, it scans the beacon frame of its parent node and synchronizes its own clock through the beacon frame. After the synchronization is completed, the child node sends the beacon frame according to the set time slot.

[0005] The existing clock tree topology synchronization network has two main disadvantages:

[0006] First, the system has low robustness. When a node fails, all subordinate nodes of the node will fail, making the positioning area covered by the failed node a blind spot. If the root node fails, the entire synchronization network will be paralyzed.

[0007] Second, when a node needs to be deleted or added to the clock tree, the clock tree needs to be reconstructed, which usually consumes more resources and time.

[0008] Therefore, there is an urgent need in the art for a clock synchronization network with strong robustness. Summary of the invention

[0009] The object of the present invention is to provide a clock synchronization network capable of improving robustness.

[0010] To achieve the above object, the present invention provides the following solutions:

[0011] A method for establishing a wireless synchronization network, comprising:

[0012] Divide node areas, determine regional priorities and node priorities within areas, and build a distributed synchronization network.

[0013] Optionally, the dividing of the node regions specifically includes: dividing the nodes into different regions according to spatial positions, including: a root node region and a plurality of child node regions, each region including a plurality of nodes.

[0014] Optionally, the determination of regional priority and node priority within the region is specifically as follows: regional priority is divided according to the degree of proximity to the root node region, the region where the root node is located has the highest priority, and the closer other regions are to the root node, the higher the priority, and nodes within the same node region are further divided into regional internal priorities.

[0015] Optionally, each of the node areas forms a distributed network.

[0016] Optionally, when the node with the highest priority in each node area is synchronized with the nodes in the node area with a higher priority than this node area, the node area is synchronized with the system clock.

[0017] Optionally, when the clock of a high-priority node area with a higher priority than a node area is abnormal or the node area cannot receive the synchronization beacon frame of the high-priority node area, the node with the highest priority in the node area serves as the clock reference of the distributed network.

[0018] Optionally, the root node area includes a root node of the root node area and a child node of the root node area; the child node area includes a root node of the child node area and a child node of the child node area.

[0019] Optionally, the root node of the root node area is the node with the highest priority and serves as the clock reference of the entire clock tree network; the child nodes of the root node area are synchronized with the clock of the root node of the root node area or a child node with a higher priority in the root node area, and send beacon frames according to the preset allocated time slots; the root node of the child node area is the node with the highest priority in the child node area, and is used to receive beacon frames sent by nodes in the root node area or nodes in a child node area with a higher priority than the child node area, and the root node of the child node area maintains clock synchronization with them; the child nodes of the child node area are used to receive beacons of other child nodes in the child node area or the root node in the area, and the child nodes of the child node area maintain clock synchronization with them, and send beacon frames according to the preset allocated time slots.

[0020] Optionally, after any node is started, it first listens to the beacon frame. If it can receive the beacon frame, it will be synchronized with the clock that sends the beacon frame.

[0021] Optionally, after the root node in the root node area is started, it first listens to the beacon frame. If a beacon frame is received, it synchronizes with the base station that sends the beacon frame, and then sends the beacon frame based on its own clock. If the beacon frame still cannot be heard after T1 time, it stops listening and sends the beacon frame based on itself.

[0022] After the child node with priority M in the root node area is started, it first listens to beacon frames. If a beacon frame is received, it synchronizes with the base station that sends the beacon frame, and then sends beacon frames in synchronization with surrounding base stations. If the beacon frame is still not detected after M*T1 time, it sends beacon frames based on its own clock. In order to avoid conflicts with beacon frames of higher priority base stations, at the beginning of sending beacon frames M*T1, it sends M beacon frames and listens to beacon frames for M*t time every time. If a beacon frame is detected, it synchronizes with the base station that sends the beacon frame, and then keeps synchronization with surrounding base stations, and then sends beacon frames according to normal cycles and time slots.

[0023] After the root node with the highest priority in the sub-node area with regional priority A is started, it first listens to beacon frames. If a beacon frame is received, it will give priority to synchronizing with nodes in the node area with a higher priority than this area, and send beacon frames according to the preset allocated time slots. If the received beacon frame does not contain nodes in the high-priority area, it will synchronize with the base station that sends the beacon frame and send beacon frames based on its own clock; if the beacon frame cannot be detected after A*R*T1+M*T2 time, it will send beacon frames based on its own clock, where R represents the maximum number of nodes supported by the root node area; in order to avoid conflicts with beacon frames of higher priority base stations, within the M*T1 time when the beacon frame is just started, each M beacon frame is sent, and beacon frames of M*t time and M*T time are listened. If a beacon frame is detected, it will synchronize with the base station that sends the beacon frame, and then keep synchronization with the surrounding base stations, and send beacon frames according to normal cycles and time slots;

[0024] After the subnode with regional priority A and regional internal priority M is started, it first listens to beacon frames. If a beacon frame is received, it synchronizes with the base station that sends the beacon frame, and then keeps synchronized with the surrounding base stations and sends beacon frames. If it still cannot hear the beacon frame after A*R*T1+M*T2 time, it sends beacon frames based on its own clock. In order to avoid conflict with beacon frames of base stations with higher priority, it starts sending beacon frames at M*T time, sends M beacon frames, and listens to beacon frames for M*t time every time. If a beacon frame is heard, it synchronizes with the base station that sends the beacon frame, and then keeps synchronized with the surrounding base stations and sends beacon frames according to normal cycles and time slots.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] The clock synchronization network designed by the present invention supports both distributed network synchronization and full network clock synchronization. The two synchronization modes can be switched automatically, making the clock synchronization network more robust. In the traditional solution, when the distributed synchronization network nodes start to establish a synchronization network, conflicts may occur when sending beacon frames. The present invention is designed with regional priority and intra-regional priority. The listening time after startup is different according to the priority, which can avoid most conflicts. In the method of the present invention, the non-root node is also designed with a periodic listening function for all beacons, which can solve the conflict problem caused by sending beacons at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 A schematic diagram of a clock synchronization tree of a prior art solution.

[0029] Figure 2 A schematic diagram of a distributed clock tree provided by the present invention.

[0030] Figure 3 This is the root node startup flow chart provided by the present invention.

[0031] Figure 4 This is a root node area sub-node startup flow chart provided by the present invention.

[0032] Figure 5This is a flowchart for starting the highest priority node in the sub-node area provided by the present invention.

[0033] Figure 6 This is a sub-node area sub-node startup flow chart provided by the present invention.

[0034] Figure 7 This is a node topology diagram provided for Example 1 of the present invention.

[0035] Figure 8 This is a 100 millisecond internal time slot allocation diagram provided in Example 1 of the present invention.

[0036] Fig. 9 This is a node topology diagram provided for Example 2 of the present invention.

[0037] Fig.10 This is a 100 millisecond internal time slot diagram provided for Embodiment 2 of the present invention.

[0038] Fig.11 This is a node topology diagram provided for Example 3 of the present invention.

[0039] Fig.12 This is a 100 millisecond internal time slot diagram provided in Example 3 of the present invention.

[0040] Fig.13 A schematic diagram of beacon transmission conflict provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The object of the present invention is to provide a clock synchronization network capable of improving robustness.

[0043] To achieve the above object, the present invention provides a method for establishing a wireless synchronization network, comprising:

[0044] Divide node areas, determine regional priorities and node priorities within areas, and build a distributed synchronization network.

[0045] Further, such as Figure 2 In the distributed clock tree schematic diagram shown, the node area division is specifically: dividing the nodes into different areas according to the spatial position, including: a root node area and several child node areas, each area contains several nodes.

[0046] Furthermore, the determination of regional priority and node priority within the region is specifically as follows: regional priority is divided according to the degree of proximity to the root node region, the region where the root node is located has the highest priority, and the closer other regions are to the root node region, the higher the priority, and nodes within the same node region are further divided into regional internal priorities.

[0047] Furthermore, each of the node areas constitutes a distributed network.

[0048] Furthermore, when the node with the highest priority in each node area is synchronized with the nodes in the node area with a higher priority than this node area, the node area is synchronized with the system clock.

[0049] Furthermore, when the clock of a high-priority node area with a higher priority than a node area is abnormal or the node area cannot receive the synchronization beacon frame of the high-priority node area, the node with the highest priority in the node area serves as the clock reference of the distributed network.

[0050] Further, the root node area includes a root node of the root node area and a child node of the root node area; the child node area includes a root node of the child node area and a child node of the child node area.

[0051] Furthermore, the root node of the root node area is the node with the highest priority and serves as the clock reference of the entire clock tree network; the child nodes of the root node area are synchronized with the clock of the root node of the root node area or a child node with a higher priority in the root node area, and send beacon frames according to the preset allocated time slots; the root node of the child node area is the node with the highest priority in the child node area and is used to receive beacon frames sent by nodes in the root node area or nodes in a child node area with a higher priority than the child node area, and the root node of the child node area maintains clock synchronization with them; the child nodes of the child node area are used to receive beacons of other child nodes in the child node area or the root node in the area, and the child nodes of the child node area maintain clock synchronization with them, and send beacon frames according to the preset allocated time slots.

[0052] Furthermore, after any node is started, it first listens to the beacon frame. If it can receive the beacon frame, it will be synchronized with the clock that sends the beacon frame.

[0053] Furthermore, the present invention provides a root node startup process for a root node area, such as Figure 3As shown in the figure, after the root node in the root node area is started, it first listens to the beacon frame. If it receives the beacon frame, it synchronizes with the base station that sends the beacon frame, and then sends the beacon frame based on its own clock. If it still cannot hear the beacon frame after T1 time, it will stop listening and send the beacon frame based on itself.

[0054] like Figure 4 As shown, the present invention provides a process for starting a sub-node in a root node area: after a sub-node with a priority of M in the root node area is started, it first listens to beacon frames. If a beacon frame is received, it synchronizes with the base station that sends the beacon frame, and then sends beacon frames in synchronization with surrounding base stations; if the beacon frame still cannot be detected after M*T1 time, the beacon frame is sent based on its own clock. In order to avoid conflicts with beacon frames of higher priority base stations, at the M*T1 moment when the beacon frame is just started to be sent, every time M beacon frames are sent, the beacon frame is listened to for M*t time. If a beacon frame is detected, it synchronizes with the base station that sends the beacon frame, and then keeps synchronization with surrounding base stations, and then sends beacon frames according to normal cycles and time slots;

[0055] like Figure 5 As shown, the present invention provides a process for starting the highest priority node in the sub-node area: after the root node with the highest priority in the sub-node area with the area priority of A is started, it first listens to the beacon frame. If a beacon frame is received, it is preferred to keep synchronization with the nodes in the node area with a higher priority than this area, and send the beacon frame according to the preset allocated time slot. If the received beacon frame does not contain the node in the high-priority area, it is synchronized with the base station that sends the beacon frame, and then sends the beacon frame based on its own clock; if the beacon frame cannot be detected after A*R*T1+M*T2 time, it sends the beacon frame based on its own clock, where R represents the maximum number of nodes supported by the root node area; in order to avoid conflict with the beacon frame of a higher priority base station, within the M*T1 time when the beacon frame is just started, each M beacon frame is sent, and the beacon frame of M*t time and M*T time is listened; if the beacon frame is detected, it is synchronized with the base station that sends the beacon frame, and then it keeps synchronization with the surrounding base stations and sends the beacon frame according to the normal cycle and time slot;

[0056] like Figure 6As shown, the present invention provides a sub-node startup process within a sub-node area: after a sub-node with an area priority of A and an internal priority of M in the area is started, it first listens to beacon frames. If a beacon frame is received, it synchronizes with the base station that sends the beacon frame, and then keeps synchronization with surrounding base stations and sends beacon frames; if the beacon frame cannot be heard after A*R*T1+M*T2 time, the beacon frame is sent based on its own clock; in order to avoid conflicts with beacon frames of base stations with higher priority, at the M*T moment when the beacon frame is just started to be sent, every time M beacon frames are sent, the beacon frame is listened for M*t time. If a beacon frame is heard, it synchronizes with the base station that sends the beacon frame, and then keeps synchronization with surrounding base stations and sends beacon frames according to normal cycles and time slots.

[0057] The following will describe methods for establishing wireless synchronization networks with different topological structures in conjunction with the accompanying drawings.

[0058] Embodiment 1:

[0059] This embodiment provides a topology structure with four areas.

[0060] like Figure 7 As shown, the synchronization network is divided into four areas. Including the root node area, 1# sub-node area, 2# sub-node area and 3# sub-node area, where the root node area has 1 root node and 6 sub-nodes, 1# sub-node area has 4 nodes, 2# sub-node area has 4 nodes and 3# sub-node area has 5 nodes. Through reasonable deployment and installation, nodes in the same area can be powered on and started at the same time. In addition, it is necessary to ensure that the sub-nodes in the area can communicate wirelessly with at least one high-priority node, ensure that the highest priority node in the sub-node area can receive beacon frames from higher priority areas, and ensure that nodes with the same beacon frame sending time slots do not interfere with each other.

[0061] The entire network has 20 nodes. The priority and beacon time slot division details are as follows:

[0062] The value selection rules of regional priority and intra-regional priority are the same, that is, the smaller the priority value, the higher the priority.

[0063] Normally, the process of establishing a wireless synchronization network is as follows:

[0064] 1) First, manually start all nodes in the root node area.

[0065] 2) After the root node 0# starts, it first listens to the beacon frame for 1 second, and then determines the relative time 0 based on its own clock. Based on time 0, it sends a beacon frame every 100ms. It takes about 0.7 milliseconds to send a beacon frame. The time slot allocation rules are as follows: Figure 8 As shown in the figure, the 100ms time resource is divided into two parts. The first 20 milliseconds are used for clock synchronization beacon frame transmission, and the last 80ms are used for terminal communication. There are 10 time slots in the design, and each base station is allocated a time slot. The 10 time slots can be recycled. It is necessary to ensure that base stations in the same time slot cannot communicate wirelessly.

[0066] 3) After the other nodes in the root node area are started, they determine the duration of beacon listening to be M seconds according to their own priority M. Under normal circumstances, within the duration of M seconds, other nodes can listen to beacon frames and complete synchronization, and then maintain synchronization with the high-priority base station and periodically send beacon frames. Under abnormal circumstances, if no beacon frame is heard within M seconds, it means that all high-priority nodes in the area have failed, and the child node sends beacon frames every 100 milliseconds based on its own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to send M beacon frames and perform M long-term listening. Each listening time is 100ms. If a beacon frame is heard, it will be synchronized with it. If no beacon frame is heard after M seconds, the frequency of long-term listening will be reduced. During the listening period, if a beacon frame with a higher priority is received, it will be synchronized with it and the clock reference will be changed.

[0067] 4) After all nodes in the root node area are started, manually start the nodes in the 1# child node area.

[0068] 5) The regional priority of the 1# subnode area is 1. After the 7# node with the highest priority in the area is started, it first listens to the beacon frame for 11 (1*10+1*1) seconds. During this period, if it hears a beacon frame with a regional priority of 0, it will immediately synchronize with it and then send beacon frames periodically. If the 11 seconds are up and no beacon frame is heard, it indicates that there is no high-priority regional node that can provide a clock reference for this area. In this case, it will send beacon frames based on its own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to perform a long-term listening for each beacon frame sent. The listening time is 100ms. If a beacon frame is heard, it will synchronize with it. If no beacon frame is heard after another 1 second, the frequency of long-term listening will be reduced. During the listening period, if a beacon frame with a higher priority is received, it will synchronize with it and change the clock reference.

[0069] 6) The regional priority of the 1# subnode area is 1. After other subnodes in the area are started, they first listen to beacon frames for 10+M (1*10+M*1) seconds. During this period, if a beacon frame with a regional priority of 1 is heard, it will immediately synchronize with it and then send beacon frames periodically. If no beacon frame is heard after 10+M seconds, it indicates that no high-priority node has failed. Then, beacon frames are sent based on their own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to send M beacon frames and perform M long-term listening. Each listening lasts 100ms. If a beacon frame is heard, it will synchronize with it. If no beacon frame is heard after M seconds, the frequency of long-term listening will be reduced. During the listening period, if a beacon frame with a higher priority is received, it will synchronize with it and change the clock reference.

[0070] 7) After all nodes in the 1# node area are started, manually start the nodes in the 2# child node area.

[0071] 8) The regional priority of the 2# subnode area is 1. After the 7# node with the highest priority in the area is started, the process is the same as step 5).

[0072] 9) The regional priority of the 2# subnode area is 1. After other subnodes in the area are started, the process is the same as step 6).

[0073] 10) After all nodes in the 2# subnode area are started, manually start all nodes in the 3# subnode area.

[0074] 11) The regional priority of the 3# subnode area is 2. After the 15# node with the highest priority in the area is started, it first listens to the beacon frame for 21 (2*10+1*1) seconds. During this period, if it hears a beacon frame with a regional priority of 0, it will immediately synchronize with it and then send beacon frames periodically. If the 21 seconds are up and no beacon frame is heard, it indicates that there is no high-priority regional node that can provide a clock reference for this area. In this case, it will send beacon frames based on its own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to perform a long-term listening for each beacon frame sent. The listening time is 100ms. If a beacon frame is heard, it will synchronize with it. If no beacon frame is heard after another 1 second, the frequency of long-term listening will be reduced. During the listening period, if a beacon frame with a higher priority is received, it will synchronize with it and change the clock reference.

[0075] 12) The regional priority of the 3# subnode area is 2. After other subnodes in the area are started, they first listen to beacon frames for 20+M (2*10+M*1) seconds. During this period, if a beacon frame with a regional priority of 2 is heard, it will immediately synchronize with it and then send beacon frames periodically. If no beacon frame is heard after 21 seconds, it indicates that no high-priority node has failed. Then, beacon frames are sent based on their own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to send M beacon frames and perform M long-term listening. Each listening lasts 100ms. If a high-priority beacon frame is heard, it will synchronize with it. If no beacon frame is heard after another 20+M seconds, the frequency of long-term listening will be reduced. During the listening period, if a beacon frame with a higher priority is received, it will synchronize with it and change the clock reference.

[0076] 13) At this point, the entire synchronization network has been successfully established.

[0077] 14) The above steps are the normal startup process. The startup process also takes into account the abnormal restart situation. When any node in the clock tree restarts, it will first listen to the beacon frame and then access the network, which will not affect the network.

[0078]

[0079] Table 1: Node list of embodiment 1

[0080] Embodiment 2:

[0081] This embodiment provides a method for starting a network with two areas and no root node area.

[0082] like Fig. 9 As shown, the synchronization network is divided into two areas. Including 1# subnode area, 2# subnode area, and no root node area. There are 4 nodes in 1# subnode area and 5 nodes in 2# subnode area. Through reasonable deployment and installation, nodes in the same area can be powered on and started at the same time. In addition, it is necessary to ensure that the subnodes in the area can communicate wirelessly with at least one high-priority node, ensure that the highest priority node in the subnode area can receive beacon frames in higher priority areas, and ensure that nodes with the same beacon frame sending time slots do not interfere with each other.

[0083] The entire network has 9 nodes. The priority and beacon time slot division details are shown in Table 2:

[0084] The value selection rules of regional priority and intra-regional priority are the same, that is, the smaller the priority value, the higher the priority.

[0085]

[0086] Table 2 Internal topology diagram of embodiment 2

[0087] Normally, the process of establishing a wireless synchronization network is as follows:

[0088] 1) First, manually start all nodes in the 1# subnode area.

[0089] 2) The regional priority of the 1# subnode area is 1. After the 0# node with the highest priority in the area is started, it first listens to the beacon frame for 11 (1*10+1*1) seconds. Since no node with a high regional priority is started, the beacon frame cannot be heard within 11 seconds. Then the beacon frame is sent based on its own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to perform a long-term listening for each beacon frame sent. The listening time is 100ms. If a beacon frame is heard, it is synchronized with it. If no beacon frame is heard after another 1 second, the frequency of long-term listening is reduced. During the listening period, if a beacon frame with a higher priority is received, it is synchronized with it and the clock reference is changed.

[0090] The time slot allocation rules are as follows: Fig.10 As shown in the figure, the 100ms time resource is divided into two parts. The first 20 milliseconds are used for clock synchronization beacon frame transmission, and the last 80ms are used for terminal communication. There are 10 time slots in the design, and each base station is allocated a time slot. The 10 time slots can be recycled. It is necessary to ensure that base stations in the same time slot cannot communicate wirelessly.

[0091] 3) The regional priority of the 1# subnode area is 1. After other subnodes in the area are started, they first listen to beacon frames for 10+M (1*10+M*1) seconds. During this period, if a beacon frame with a regional priority of 1 is heard, it will immediately synchronize with it and then send beacon frames periodically. If no beacon frame is heard after 11+M seconds, it indicates that no high-priority node has failed. Then, beacon frames are sent based on their own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to send M beacon frames and perform M long-term listening. Each listening lasts 100ms. If a high-priority beacon frame is heard, it will synchronize with it. If no beacon frame is heard after another 10+M seconds, the frequency of long-term listening will be reduced. During the listening period, if a beacon frame with a higher priority is received, it will synchronize with it and change the clock reference.

[0092] 4) After all nodes in the 1# subnode area are started, manually start the nodes in the 2# subnode area.

[0093] 5) The regional priority of the 2# subnode area is 2. After the 4# node with the highest priority in the area is started, it first listens to the beacon frame for 21 (2*10+1*1) seconds. During this period, if it hears a beacon frame with a regional priority of 0, it will immediately synchronize with it and then send beacon frames periodically. If the 21 seconds are up and the beacon frame is still not heard, it indicates that there is no high-priority regional node that can provide a clock reference for this area. In this case, it will send beacon frames based on its own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to perform a long-term listening for each beacon frame sent. The listening time is 100ms. If a beacon frame is heard, it will synchronize with it. If M seconds have passed and no beacon frame has been heard, the frequency of long-term listening will be reduced. During the listening period, if a beacon frame is received, it will synchronize with it and change the clock reference.

[0094] 6) The regional priority of the 2# subnode area is 2. After other subnodes in the area are started, they first listen to beacon frames for 20+M (2*10+M*1) seconds. During this period, if a beacon frame with a regional priority of 2 is heard, it will immediately synchronize with it and then send beacon frames periodically. If no beacon frame is heard after 21+M seconds, it indicates that no high-priority node has failed. Then, beacon frames are sent based on their own clock. In order to avoid misjudgment, when sending beacon frames at the same time as other nodes, it is necessary to send M beacon frames and perform M long-term listening. Each listening lasts 100ms. If a beacon frame is heard, it will synchronize with it. If no beacon frame is heard after M seconds, the frequency of long-term listening will be reduced. During the listening period, if a beacon frame with a higher priority is received, it will synchronize with it and change the clock reference.

[0095] 7) At this point, the entire synchronization network has been successfully established.

[0096] The above steps are the normal startup process. The startup process also takes into account the abnormal restart situation. When any node in the clock tree restarts, it will first listen to the beacon frame and then access the network, which will not affect the network.

[0097] Embodiment 3:

[0098] This implementation provides a topology structure with two sub-node areas, and specifically describes a solution when two nodes conflict in sending beacon frames.

[0099] like Fig.11As shown, the synchronization network is divided into two areas. Including 1# subnode area, 2# subnode area, and no root node area. There are 3 nodes in 1# subnode area and 4 nodes in 2# subnode area. Through reasonable deployment and installation, nodes in the same area can be powered on and started at the same time. In addition, it is necessary to ensure that the subnodes in the area can communicate wirelessly with at least one high-priority node, ensure that the highest priority node in the subnode area can receive beacon frames from higher priority areas, and ensure that nodes with the same beacon frame sending time slots do not interfere with each other.

[0100] The entire network has 9 nodes. The priority and beacon time slot division details are shown in Table 3:

[0101] The value selection rules of regional priority and intra-regional priority are the same, that is, the smaller the priority value, the higher the priority.

[0102]

[0103] Table 3 Node list of embodiment 3

[0104] like Fig.12 As shown, under normal circumstances, the process of establishing a wireless synchronization network is as follows:

[0105] 1) Manually start all nodes in the 2# subnode area at time 0.

[0106] 2) The regional priority of the 2# subnode area is 1. After the 3# node with the highest priority in the area is started, it first listens to the beacon frame for 21 (2*10+1*1) seconds. Since no node with a high regional priority is started, the beacon frame cannot be heard within 21 seconds. Then the beacon frame is sent based on its own clock. The time slot allocation rule is shown in the figure below: 100ms time resources are divided into two parts, the first 20 milliseconds are used for clock synchronization beacon frame transmission, and the last 80ms are used for terminal communication. There are 10 time slots in the design, and each base station is allocated a time slot. The 10 time slots can be recycled. It is necessary to ensure that base stations with the same time slot cannot communicate wirelessly.

[0107] 3) The regional priority of the 2# subnode area is 1. After other subnodes in the area are started, they first listen to the beacon frame for 20+M(1*10+M*1) seconds. After 21 seconds, they can hear the beacon frame with regional priority 1, and then synchronize with it immediately, and then send beacon frames periodically.

[0108] 4) At the 10th second, all nodes in the 1# child node area are manually started.

[0109] 5) The regional priority of the 1# subnode area is 1. After the 0# node with the highest priority in the area is started, it first listens to beacon frames from 10 seconds to 21 seconds. Since no node with a higher regional priority sends beacon frames, it still cannot listen to beacon frames until 21 seconds, and then sends beacon frames based on its own clock. At this time, the 3# node in the 2# subnode area has also started to send beacon frames based on itself. In this way, the two are not synchronized, and both send beacon frames based on themselves.

[0110] 6) The priority of node 0# in the area of ​​subnode 1# is 3, so the subnode sends beacon 3 times and listens for beacon for 300 milliseconds; the priority of node 3# in the area of ​​subnode 2# is 1, so the subnode sends beacon once and listens for beacon for 100 milliseconds. As shown in the following figure: between 21.1 seconds and 21.2 seconds, node 2# sends beacon frame, and after receiving the beacon frame, node 3# can synchronize with it immediately, and then keep synchronized with node 2#.

[0111] 7) At this point, the entire synchronization network has been successfully established.

[0112] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0113] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for establishing a wireless synchronization network, characterized in that: include: Divide node areas, determine regional priorities and node priorities within areas, and build a distributed synchronization network.

2. The method for establishing a wireless synchronization network according to claim 1, characterized in that: The node area division is specifically: dividing the node into different areas according to the spatial position, including: a root node area and a plurality of child node areas, each area including a plurality of nodes.

3. The method for establishing a wireless synchronization network according to claim 2, characterized in that: The determination of regional priority and node priority within the region is specifically as follows: regional priority is divided according to the degree of proximity to the root node region, the region where the root node is located has the highest priority, and the closer other regions are to the root node, the higher the priority, and nodes within the same node region are further divided into regional internal priorities.

4. The method for establishing a wireless synchronization network according to claim 1, characterized in that: Each of the node areas constitutes a distributed network.

5. The method for establishing a wireless synchronization network according to claim 1, characterized in that: When the node with the highest priority in each node area keeps synchronization with the nodes in the node area with a higher priority than this node area, the node area keeps synchronization with the system clock.

6. The method for establishing a wireless synchronization network according to claim 1, characterized in that: When the clock of a high-priority node area with a higher priority than a node area is abnormal or the node area cannot receive the synchronization beacon frame of the high-priority node area, the node with the highest priority in the node area serves as the clock reference of the distributed network.

7. The method for establishing a wireless synchronization network according to claim 2, characterized in that: The root node area includes a root node of the root node area and a child node of the root node area; the child node area includes a root node of the child node area and a child node of the child node area.

8. The method for establishing a wireless synchronization network according to claim 7, characterized in that: The root node of the root node area is the node with the highest priority and serves as the clock reference of the entire clock tree network; the child nodes of the root node area are synchronized with the clock of the root node of the root node area or the child nodes with higher priority in the root node area, and send beacon frames according to the preset allocated time slots; The root node of the sub-node area is the node with the highest priority in the sub-node area, and is used to receive beacon frames sent by the node of the root node area or the node of the sub-node area with a higher priority than the sub-node area, and the root node of the sub-node area maintains clock synchronization with the node; the sub-nodes of the sub-node area are used to receive beacons of other sub-nodes in the sub-node area or the root node in the area, and the sub-nodes of the sub-node area maintain clock synchronization with the root node and send beacon frames according to the preset allocated time slots.

9. The method for establishing a wireless synchronization network according to claim 7, characterized in that: After any node starts, it first listens to the beacon frame. If it can receive the beacon frame, it will be synchronized with the clock that sends the beacon frame.

10. The method for establishing a wireless synchronization network according to claim 9, characterized in that: After the root node in the root node area is started, it first listens to the beacon frame. If it receives a beacon frame, it synchronizes with the base station that sends the beacon frame, and then sends the beacon frame based on its own clock. If it still cannot hear the beacon frame after T1 time, it will stop listening and send the beacon frame based on itself. After the child node with priority M in the root node area is started, it first listens to beacon frames. If a beacon frame is received, it synchronizes with the base station that sends the beacon frame, and then sends beacon frames in synchronization with surrounding base stations. If the beacon frame is still not detected after M*T1 time, it sends beacon frames based on its own clock. In order to avoid conflicts with beacon frames of higher priority base stations, at the beginning of sending beacon frames M*T1, it sends M beacon frames and listens to beacon frames for M*t time every time. If a beacon frame is detected, it synchronizes with the base station that sends the beacon frame, and then keeps synchronization with surrounding base stations, and then sends beacon frames according to normal cycles and time slots. After the root node with the highest priority in the sub-node area with regional priority A is started, it first listens to beacon frames. If a beacon frame is received, it will give priority to synchronizing with nodes in the node area with a higher priority than this area, and send beacon frames according to the preset allocated time slots. If the received beacon frame does not contain nodes in the high-priority area, it will synchronize with the base station that sends the beacon frame and send beacon frames based on its own clock; if the beacon frame cannot be detected after A*R*T1+M*T2 time, it will send beacon frames based on its own clock, where R represents the maximum number of nodes supported by the root node area; in order to avoid conflicts with beacon frames of higher priority base stations, within the M*T1 time when the beacon frame is just started, each M beacon frame is sent, and beacon frames of M*t time and M*T time are listened. If a beacon frame is detected, it will synchronize with the base station that sends the beacon frame, and then keep synchronization with the surrounding base stations, and send beacon frames according to normal cycles and time slots; After the subnode with regional priority A and regional internal priority M is started, it first listens to beacon frames. If a beacon frame is received, it synchronizes with the base station that sends the beacon frame, and then keeps synchronized with the surrounding base stations and sends beacon frames. If it still cannot hear the beacon frame after A*R*T1+M*T2 time, it sends beacon frames based on its own clock. In order to avoid conflict with beacon frames of base stations with higher priority, it starts sending beacon frames at M*T time, sends M beacon frames, and listens to beacon frames for M*t time every time. If a beacon frame is heard, it synchronizes with the base station that sends the beacon frame, and then keeps synchronized with the surrounding base stations and sends beacon frames according to normal cycles and time slots.

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