Transmission tower terminal synchronization method and system based on cooperative broadcast

Abstract

The invention belongs to the technical field of communication, and discloses a transmission tower terminal synchronization method and system based on cooperative broadcast, and the method comprises the steps: taking a plurality of first tower terminals as synchronization source nodes, and broadcasting a synchronization announcement in a preset period; the second tower terminal receives at least one synchronous announcement; the second tower terminal obtains a timestamp, hop count information, received signal strength, synchronization source clock precision and terminal load information according to the synchronization announcement, and calculates synchronization quality information of the synchronization announcement; the second tower terminal determines a target announcement in the synchronous announcements according to the synchronous quality information; the second tower terminal adjusts a local clock according to the synchronization source clock precision of the target announcement; and the second tower terminal updates the target announcement to obtain and broadcast a new synchronous announcement. According to the invention, decentralized cooperation of the transmission tower terminal can be realized, the child nodes only interact with the optimal synchronization source, and network flooding and delay are reduced.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a transmission tower terminal synchronization method and system based on collaborative broadcasting. Background Art

[0002] Currently, data transmission on transmission towers in areas without a public network primarily utilizes broadband ad hoc networking technology, enabling real-time monitoring of transmission tower equipment within the power grid. However, conventional synchronization of the link layer of wireless communication components within broadband ad hoc network equipment typically relies on a central node or clock source for time synchronization. Nodes must regularly communicate with the central node to obtain accurate time information and adjust their clocks accordingly. This approach can introduce significant synchronization delays and communication overhead when the number of nodes is large or the network topology is complex, making it unsuitable for grid systems with a large number of nodes. Summary of the Invention

[0003] The present application provides a transmission tower terminal synchronization method and system based on collaborative broadcasting, which can realize decentralized collaboration of transmission tower terminals. Sub-nodes only interact with the optimal synchronization source, reducing network flooding and delay.

[0004] In a first aspect, an embodiment of the present application provides a transmission tower terminal synchronization method based on collaborative broadcasting, comprising:

[0005] Using multiple first tower terminals as synchronization source nodes to broadcast synchronization announcements at a preset period;

[0006] The second tower terminal receives at least one synchronization announcement;

[0007] The second tower terminal obtains the timestamp, hop count information, received signal strength, synchronization source clock accuracy, and terminal load information based on the synchronization announcement, and calculates the synchronization quality information of the synchronization announcement;

[0008] The second tower terminal determines the target announcement in the synchronization announcement based on the synchronization quality information;

[0009] The second tower terminal adjusts the local clock according to the synchronization source clock accuracy announced by the target;

[0010] The second tower terminal updates the target announcement, obtains a new synchronization announcement and broadcasts it.

[0011] Furthermore, the synchronization announcement includes a timestamp, a synchronization source identifier, hop count information, terminal load information, synchronization source clock accuracy, and a cycle sequence number; the synchronization source clock accuracy includes the synchronization source clock and the synchronization source clock delay.

[0012] Furthermore, the method further comprises:

[0013] The second tower terminal classifies each synchronization announcement according to the synchronization source identifier to obtain an announcement queue;

[0014] The synchronization announcement with the largest cycle number in each announcement queue is selected to calculate the synchronization quality information.

[0015] Furthermore, the method further comprises:

[0016] Before classification, the second tower terminal removes synchronization announcements with hop count information greater than a preset hop count threshold.

[0017] Furthermore, the method further comprises:

[0018] The first tower terminal obtains terminal load information and historical maximum synchronization error;

[0019] The preset period is determined based on the terminal load information and the historical maximum synchronization error.

[0020] Furthermore, the second tower terminal obtains the timestamp, hop count information, received signal strength, synchronization source clock accuracy, and terminal load information based on the synchronization announcement, and calculates synchronization quality information of the synchronization announcement, including:

[0021] Perform signal sampling and averaging based on the received synchronization announcement to obtain the received signal strength;

[0022] Mapping the received signal strength according to a preset strength range to obtain a link quality indicator;

[0023] Calculate transmission delay based on timestamp and synchronization source clock accuracy;

[0024] The hop count information, link quality index, transmission delay, synchronization source clock accuracy and terminal load information are normalized and weighted to obtain the synchronization quality information of the synchronization announcement.

[0025] Furthermore, the above calculation of transmission delay based on timestamp and synchronization source clock accuracy includes:

[0026] Get the reception time of the synchronization announcement;

[0027] Subtract the timestamp from the reception time to get the transmission time difference;

[0028] Subtract the synchronization source clock delay from the transmission time difference to obtain the transmission delay.

[0029] Furthermore, the method further comprises:

[0030] The second tower terminal obtains each synchronization announcement corresponding to the same synchronization source identifier;

[0031] Calculate the quality parameters of each synchronization announcement; quality parameters include hop count information, link quality indicators, transmission delay, synchronization source clock accuracy and terminal load information;

[0032] Calculate the corresponding parameter weight according to the change rate of each quality parameter;

[0033] The quality parameters are weighted and calculated according to the parameter weights to obtain synchronization quality information.

[0034] Furthermore, the second tower terminal determines a target announcement in the synchronization announcement based on the synchronization quality information, including:

[0035] The synchronization bulletin with the highest synchronization quality information is selected as the target bulletin.

[0036] Furthermore, the second tower terminal adjusts the local clock according to the synchronization source clock accuracy announced by the target, including:

[0037] Subtract the local clock of the second tower terminal from the synchronization source clock to obtain the clock deviation;

[0038] Determine whether the clock deviation is less than or equal to a preset clock threshold;

[0039] If so, add the local clock and the clock bias;

[0040] If not, the local clock is gradually adjusted according to the PID algorithm.

[0041] Furthermore, the second tower terminal updates the target announcement, obtains a new synchronization announcement, and broadcasts it, including:

[0042] Add 1 to the hop count information in the target announcement;

[0043] Update the terminal load information in the target announcement according to the current resource utilization rate;

[0044] Update the timestamp in the target announcement according to the current moment, obtain a new synchronization announcement and broadcast it.

[0045] Furthermore, the method further comprises:

[0046] After adding 1 to the hop count information of the target announcement, the second tower terminal determines whether the hop count information is greater than a preset hop count threshold; if so, no new synchronization announcement is generated.

[0047] In a second aspect, an embodiment of the present application provides a transmission tower terminal synchronization system based on cooperative broadcasting, comprising a plurality of first tower terminals and a plurality of second tower terminals; each first tower terminal serves as a synchronization source node;

[0048] The first tower terminal is used to broadcast synchronous announcements at a preset period;

[0049] The second tower terminal is used to receive at least one synchronization announcement; obtain a timestamp, hop count information, received signal strength, synchronization source clock accuracy and terminal load information according to the synchronization announcement, and calculate synchronization quality information of the synchronization announcement;

[0050] Furthermore, a target announcement is determined in the synchronization announcement according to the synchronization quality information; a local clock is adjusted according to the synchronization source clock accuracy of the target announcement; the target announcement is updated, a new synchronization announcement is obtained, and the new synchronization announcement is broadcast.

[0051] Furthermore, the synchronization announcement includes a timestamp, synchronization source identification, hop count information, terminal load information, synchronization source clock accuracy, and cycle sequence number; the synchronization source clock accuracy includes the synchronization source clock and synchronization source clock delay;

[0052] The second tower terminal is further configured to classify each synchronization announcement according to the synchronization source identifier to obtain an announcement queue; and select the synchronization announcement with the largest cycle number in each announcement queue to calculate synchronization quality information.

[0053] Furthermore, the second tower terminal is further configured to remove synchronization announcements with hop count information greater than a preset hop count threshold before classification.

[0054] Furthermore, the first tower terminal is further configured to obtain terminal load information and a historical maximum synchronization error; and determine a preset period according to the terminal load information and the historical maximum synchronization error.

[0055] Furthermore, the second tower terminal is specifically used to sample and average the signal according to the received synchronization announcement to obtain the received signal strength; map the received signal strength according to the preset strength range to obtain the link quality index; calculate the transmission delay based on the timestamp and the synchronization source clock accuracy; normalize the hop number information, link quality index, transmission delay, synchronization source clock accuracy and terminal load information, and perform weighted calculation to obtain the synchronization quality information.

[0056] Furthermore, the second tower terminal is specifically used to obtain the reception time of the synchronization announcement; subtract the timestamp from the reception time to obtain the transmission time difference; and subtract the synchronization source clock delay from the transmission time difference to obtain the transmission delay.

[0057] Furthermore, the second tower terminal is also used to obtain various synchronization announcements corresponding to the same synchronization source identifier; calculate the quality parameters of each synchronization announcement; the quality parameters include hop count information, link quality indicators, transmission delay, synchronization source clock accuracy and terminal load information; calculate the corresponding parameter weight according to the change rate of each quality parameter; and perform weighted calculation on the quality parameters according to the parameter weight to obtain synchronization quality information.

[0058] Furthermore, the second tower terminal is specifically used to subtract the local clock of the second tower terminal from the synchronization source clock to obtain the clock deviation; determine whether the clock deviation is less than or equal to the preset clock threshold; if so, add the local clock to the clock deviation; if not, gradually adjust the local clock according to the PID algorithm.

[0059] In summary, compared with the prior art, the technical solutions provided by the embodiments of the present application have at least the following beneficial effects:

[0060] An embodiment of the present application provides a transmission tower terminal synchronization method based on collaborative broadcasting. First, a certain number of first tower terminals are selected as synchronization source nodes to broadcast synchronization announcements. After the second tower terminals that receive the synchronization announcements perform clock synchronization according to the synchronization announcements, they further update the announcements for broadcasting, thereby realizing a synchronization announcement mechanism of collaborative broadcasting. The above method realizes decentralized collaboration of transmission tower terminals, and at the same time limits the synchronization range with hop count information. If the second tower terminal of a non-synchronization source node receives multiple synchronization announcements at the same time or in a short time, it will make an announcement decision based on the timestamp, hop count information, received signal strength, synchronization source clock accuracy and terminal load information, and select the optimal synchronization announcement as the target announcement for clock synchronization, so that the child node only interacts with the optimal synchronization source, reducing network flooding and delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 A flowchart of a transmission tower terminal synchronization method based on collaborative broadcasting is provided in accordance with an embodiment of the present application.

[0062] Figure 2 A flowchart of the steps for calculating synchronization quality information provided in one embodiment of the present application.

[0063] Figure 3 A flowchart of the parameter weight calculation steps provided for one embodiment of the present application.

[0064] Figure 4 A flowchart of the local clock adjustment steps provided for one embodiment of the present application. DETAILED DESCRIPTION

[0065] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0066] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0067] See Figure 1The embodiment of the present application provides a transmission tower terminal synchronization method based on cooperative broadcasting, comprising:

[0068] Step S11: multiple first tower terminals are used as synchronization source nodes to broadcast synchronization announcements at a preset period.

[0069] The synchronization announcement includes a timestamp, synchronization source identifier, hop count information, terminal load information, synchronization source clock accuracy, and cycle sequence number; the synchronization source clock accuracy includes the synchronization source clock and synchronization source clock delay.

[0070] The timestamp is the moment when the first tower terminal broadcasts the synchronization announcement.

[0071] The hop count information is the tower nodes that the synchronization announcement passes through, and the hop count information in the synchronization source node is initialized to 0 or 1.

[0072] The terminal load information is the resource occupancy rate of the first tower terminal, which is a percentage.

[0073] The synchronization source identifier is used to distinguish different first tower terminals, and the cycle number is used to indicate the cycle in which the synchronization announcement is sent by the first tower terminal, and is indirectly used to determine the timing of the synchronization announcement and the latest announcement parameters.

[0074] The synchronization source clock is the clock signal of the first tower terminal.

[0075] The synchronization source clock delay is the clock stability of the first tower terminal, for example, ±10ppm.

[0076] Step S12: The second tower terminal receives at least one synchronization announcement.

[0077] Here, the second tower terminal may be allowed to reserve a receiving window (time period), that is, all synchronization announcements received within the window period will enter the announcement decision phase of step S13 to achieve optimal synchronization.

[0078] Step S13: The second tower terminal obtains the timestamp, hop count information, received signal strength, synchronization source clock accuracy, and terminal load information according to the synchronization announcement, and calculates the synchronization quality information of the synchronization announcement.

[0079] Step S14: The second tower terminal determines a target announcement in the synchronization announcement according to the synchronization quality information.

[0080] Specifically, the second tower terminal selects the synchronization announcement with the highest synchronization quality information as the target announcement.

[0081] It can be assumed that in the uninhabited areas where transmission towers are located, the terrain varies greatly. Not only are the horizontal and vertical distances between towers uneven, but there may also be hills and other obstacles that block signal transmission. This causes wireless signals to be interfered with by the terrain. Even if two transmission links have the same number of nodes, their transmission delays may vary significantly.

[0082] Therefore, this application requires each second tower terminal to judge the quality of the synchronization source based on the received synchronization announcement, select the best synchronization source within the synchronization range to perform clock synchronization operations, and reduce the delay of subsequent communications and network flooding.

[0083] Step S15: The second tower terminal adjusts the local clock according to the synchronization source clock accuracy announced by the target.

[0084] Step S16: The second tower terminal updates the target announcement, obtains a new synchronization announcement, and broadcasts it.

[0085] Specifically, the second tower terminal updates the target announcement, obtains a new synchronization announcement, and broadcasts it, including:

[0086] Step S161: add 1 to the hop count information in the target announcement.

[0087] Step S162: Update the terminal load information in the target announcement according to the current resource occupancy rate.

[0088] Step S163: Update the timestamp in the target announcement according to the current time, obtain a new synchronization announcement and broadcast it.

[0089] It can be considered that the hop count information of the new synchronization announcement is increased by 1 compared with the target announcement, the terminal load information is the resource occupancy rate of the second tower terminal, and the timestamp is the time of the second tower terminal broadcast, which can be specifically the current time plus the radio frequency delay.

[0090] By executing the above steps, collaborative broadcasting of multiple tower nodes is realized, forming a distributed synchronization tree. This not only avoids single-point bottlenecks, but also allows the second tower terminal to quickly resynchronize by receiving synchronization announcements from other synchronization source nodes or other second tower terminals in the event of failure of a synchronization source, without the need for full network reconstruction.

[0091] The above embodiment provides a transmission tower terminal synchronization method based on collaborative broadcasting. First, a certain number of first tower terminals are selected as synchronization source nodes to broadcast synchronization announcements. After the second tower terminals that receive the synchronization announcements perform clock synchronization according to the synchronization announcements, they further update the announcements and broadcast them, thereby realizing a synchronization announcement mechanism of collaborative broadcasting. The above method realizes decentralized collaboration of transmission tower terminals, and at the same time limits the synchronization range by hop count information. If the second tower terminal, which is not a synchronization source node, receives multiple synchronization announcements at the same time or in a short time, it will make an announcement decision based on the timestamp, hop count information, received signal strength, synchronization source clock accuracy and terminal load information, and select the optimal synchronization announcement as the target announcement for clock synchronization, so that the child node only interacts with the optimal synchronization source, reducing network flooding and delay.

[0092] In some embodiments, the method further comprises:

[0093] Step S21: The second tower terminal classifies each synchronization announcement according to the synchronization source identifier to obtain an announcement queue.

[0094] Step S22: Select the synchronization announcement with the largest cycle number in each announcement queue to calculate the synchronization quality information.

[0095] Specifically, if the receiving window of the second tower terminal is set longer and the preset broadcast period of the first tower terminal is shorter, the second tower terminal may receive synchronization announcements broadcast by the same synchronization source node for two or even more consecutive periods. At this time, the second tower terminal makes an announcement decision based on the latest synchronization announcement, that is, the one with the largest period number.

[0096] The above embodiment uses the synchronization source identifier and cycle sequence number of the synchronization announcement as a reference to accurately screen out the synchronization announcements belonging to the same first tower terminal and the latest synchronization announcement therein. While ensuring the reliability of the announcement decision, it avoids making decisions on useless and redundant synchronization announcements, and reduces the delay and power consumption required for synchronization.

[0097] In some embodiments, the method further comprises:

[0098] Before classification, the second tower terminal removes synchronization announcements with hop count information greater than a preset hop count threshold.

[0099] Specifically, the unlimited forwarding of synchronization announcements may lead to a broadcast storm, causing each non-synchronized source node to receive too many synchronization announcements, resulting in increased power consumption of each node and the entire tower communication system.

[0100] Therefore, the above embodiment sets the synchronization range through hop count information, that is, limits the synchronization announcement broadcast range, avoids broadcast storms through a broadcast suppression strategy, and reduces the power consumption of the tower network.

[0101] In some embodiments, the method further comprises:

[0102] Step S01: A first tower terminal obtains terminal load information and a historical maximum synchronization error.

[0103] The terminal load information is the resource occupancy rate of the terminal on the first tower at this time, which is expressed as a percentage, or may be the channel contention intensity, such as the number of CSMA / CA conflicts.

[0104] The historical maximum synchronization error is the historical maximum value of the clock error of the second tower terminal after synchronization, which performs clock synchronization using the synchronization announcement broadcast by the first tower terminal as the target announcement.

[0105] Step S02: determining a preset period according to the terminal load information and the historical maximum synchronization error.

[0106] Specifically, the preset period T new It can be determined by the following formula:

[0107]

[0108] Among them, T base is the preset basic period, for example 10 seconds; ɑ is the load sensitivity coefficient, the default value is 0.5.

[0109] L max The upper limit threshold of the terminal load is usually 90%. net This is the terminal load information.

[0110] β is the error sensitivity coefficient, which generally defaults to 0.1 / ms; E is the maximum historical synchronization error.

[0111] In the preset period determination rule defined in the above embodiment, L net The larger the value, the longer the cycle, thereby reducing the broadcast frequency when the load is high and avoiding congestion; the larger the value of E, the smaller the cycle, that is, shortening the cycle when the error increases and improving synchronization accuracy.

[0112] See Figure 2 In some embodiments, the second tower terminal obtains a timestamp, hop count information, received signal strength, synchronization source clock accuracy, and terminal load information based on the synchronization announcement, and calculates synchronization quality information of the synchronization announcement, including:

[0113] Step S131: sampling and averaging the signals according to the received synchronization announcement to obtain the received signal strength.

[0114] Step S132: Map the received signal strength according to a preset strength range to obtain a link quality indicator.

[0115] Specifically, first take the average of multiple samples of the received signal:

[0116]

[0117] Among them, RSSI i is the signal strength of the i-th sampling, N is the number of sampling times, which can be 10 times.

[0118] This application takes the average of multiple samples of the received signal because this application is applied to the transmission tower terminal. In order to reduce the path loss of electric energy, the transmission network in the uninhabited area generally transmits electric energy at ultra-high voltage or even ultra-high voltage. Therefore, it can be assumed that there are high-voltage lines around the transmission tower terminal, and strong electromagnetic noise will be generated around the high-voltage lines, affecting the stability of wireless communication. Therefore, when calculating the received signal strength, this application takes the average of multiple samples to eliminate instantaneous interference.

[0119] Then the received signal strength RSSI is converted into the link quality indicator R norm :

[0120]

[0121] Among them, RSSI max and RSSI min The signal strength range is within a preset reasonable range, such as -120dBm to -40dBm.

[0122] Step S133: Calculate the transmission delay based on the timestamp and the synchronization source clock accuracy.

[0123] Specifically, the above calculation of transmission delay based on timestamp and synchronization source clock accuracy includes:

[0124] Step S1331, obtain the reception time of the synchronization announcement.

[0125] Step S1332: Subtract the timestamp from the receiving time to obtain the transmission time difference.

[0126] Step S1333 : Subtract the synchronization source clock delay from the transmission time difference to obtain the transmission delay.

[0127] Specifically, first calculate the transmission time difference Total Diff :

[0128] Total Diff =T recv -T s

[0129] Among them, T recv is the receiving time (specifically a moment), T s This is the timestamp in the synchronization announcement.

[0130] Then, because the transmission time difference includes the transmission delay d and the clock delay, the transmission delay d is calculated as:

[0131] d=Total Diff -Δ

[0132] Where Δ is the synchronization source clock delay recorded in the synchronization announcement.

[0133] Step S134 , normalizing the hop count information, link quality indicator, transmission delay, synchronization source clock accuracy, and terminal load information, and performing weighted calculation to obtain synchronization quality information of the synchronization announcement.

[0134] Specifically, the synchronization quality information Q can be calculated using the following formula:

[0135]

[0136] Among them, h norm is the hop count information in the synchronization announcement, and w1 to w5 are the parameter weights of the corresponding parameters.

[0137] The above embodiment takes into account the influence of electromagnetic interference from the surrounding high-voltage lines on the second tower terminal, as well as weather factors, its own faults, and possible geographical factors between the first tower terminal and the like. The quality of the synchronization source is calculated based on the weighted calculation of the above multiple parameters to select the optimal synchronization source for synchronization, thereby reducing network delay. If a synchronization source node fails or malfunctions, the second tower terminal can quickly resynchronize through other synchronization announcements received without the need for full network reconstruction.

[0138] See Figure 3 In some embodiments, the method further comprises:

[0139] Step S31: The second tower terminal obtains synchronization announcements corresponding to the same synchronization source identifier.

[0140] “Synchronization announcements corresponding to the same synchronization source identifier” refer to synchronization announcements continuously sent by a first tower terminal at a preset period. The synchronization announcements here are arranged according to the period sequence numbers therein, reflecting the time sequence of changes in quality parameters.

[0141] Step S32, calculating the quality parameters of each synchronization announcement; the quality parameters include hop count information, link quality index, transmission delay, synchronization source clock accuracy and terminal load information.

[0142] The specific calculation process of the quality parameters is consistent with the above embodiment and will not be described in detail here.

[0143] Step S33: Calculate the corresponding parameter weight according to the change rate of each quality parameter.

[0144] Specifically, the link quality indicator R norm For example, the rate of change can be calculated using the following function:

[0145]

[0146] The rate of change of each quality parameter is negatively correlated with the corresponding parameter weight:

[0147]

[0148] That is, the higher the rate of change, the lower the weight, which suppresses the influence of unstable parameters.

[0149] Furthermore, in addition to considering the rate of change, if the quality parameter exceeds the corresponding threshold, its parameter weight can be directly increased by a preset step size. For example, if the terminal load information is greater than the terminal load upper limit threshold, the corresponding parameter weight is increased by 0.2.

[0150] Step S34: Perform weighted calculation on the quality parameters according to the parameter weights to obtain synchronization quality information.

[0151] The above embodiment provides a dynamic parameter weight adjustment strategy based on real-time network status, which improves the adaptability and robustness of synchronization quality information calculation for synchronization source nodes.

[0152] See Figure 4 In some embodiments, the second tower terminal adjusts the local clock according to the synchronization source clock accuracy announced by the target, which may specifically include the following steps:

[0153] Step S151: Subtract the local clock of the second tower terminal from the synchronization source clock to obtain the clock deviation.

[0154] Step S152: determine whether the clock deviation is less than or equal to a preset clock threshold.

[0155] Step S153: If yes, add the local clock and the clock deviation.

[0156] Step S154: If not, gradually adjust the local clock according to the PID algorithm.

[0157] Specifically, if the clock deviation is small, the local clock and the clock deviation can be directly set to be added. If the clock deviation is large, that is, the degree of synchronization adjustment required is large, in order to avoid clock jumps, the PID algorithm is used to gradually adjust the local clock frequency and compensate for the drift rate until the local clock frequency is synchronized with the synchronization source clock frequency.

[0158] In some embodiments, the method further comprises:

[0159] After adding 1 to the hop count information of the target announcement, the second tower terminal determines whether the hop count information is greater than a preset hop count threshold; if so, no new synchronization announcement is generated.

[0160] Specifically, consistent with the reason for filtering synchronization announcements based on hop count information in the above embodiment, if the second tower terminal finds that forwarding the synchronization announcement again will cause its forwarding times to exceed the synchronization range, it will stop forwarding, that is, the synchronization announcement corresponding to the synchronization source node will be terminated at the current second tower terminal, avoiding network flooding.

[0161] Another embodiment of the present application provides a transmission tower terminal synchronization system based on collaborative broadcasting, including multiple first tower terminals and multiple second tower terminals; each first tower terminal serves as a synchronization source node.

[0162] The first tower terminal is used to broadcast synchronization announcements at a preset period.

[0163] The synchronization announcement includes a timestamp, synchronization source identifier, hop count information, terminal load information, synchronization source clock accuracy, and cycle sequence number; the synchronization source clock accuracy includes the synchronization source clock and synchronization source clock delay.

[0164] The timestamp is the moment when the first tower terminal broadcasts the synchronization announcement.

[0165] The hop count information is the tower nodes that the synchronization announcement passes through, and the hop count information in the synchronization source node is initialized to 0 or 1.

[0166] The terminal load information is the resource occupancy rate of the first tower terminal, which is a percentage.

[0167] The synchronization source identifier is used to distinguish different first tower terminals, and the cycle number is used to indicate the cycle in which the synchronization announcement is sent by the first tower terminal, and is indirectly used to determine the timing of the synchronization announcement and the latest announcement parameters.

[0168] The synchronization source clock is the clock signal of the first tower terminal.

[0169] The synchronization source clock delay is the clock stability of the first tower terminal, for example, ±10ppm.

[0170] The second tower terminal is used to receive at least one synchronization announcement; obtain the timestamp, hop count information, received signal strength, synchronization source clock accuracy and terminal load information according to the synchronization announcement, calculate the synchronization quality information of the synchronization announcement; and determine the target announcement in the synchronization announcement according to the synchronization quality information; adjust the local clock according to the synchronization source clock accuracy of the target announcement; update the target announcement, obtain a new synchronization announcement and broadcast it.

[0171] Here, the second tower terminal may be allowed to reserve a receiving window (time period), that is, all synchronization announcements received within the window period will enter the subsequent announcement decision phase to achieve optimal synchronization.

[0172] Specifically, the second tower terminal selects the synchronization announcement with the highest synchronization quality information as the target announcement.

[0173] It can be assumed that in the uninhabited areas where transmission towers are located, the terrain varies greatly. Not only are the horizontal and vertical distances between towers uneven, but there may also be hills and other obstacles that block signal transmission. This causes wireless signals to be interfered with by the terrain. Even if two transmission links have the same number of nodes, their transmission delays may vary significantly.

[0174] Therefore, this application requires each second tower terminal to judge the quality of the synchronization source based on the received synchronization announcement, select the best synchronization source within the synchronization range to perform clock synchronization operations, and reduce the delay of subsequent communications and network flooding.

[0175] The second tower terminal is specifically used to increase the hop count information in the target announcement by 1; update the terminal load information in the target announcement according to the current resource occupancy rate; update the timestamp in the target announcement according to the current moment, obtain a new synchronization announcement and broadcast it.

[0176] It can be considered that the hop count information of the new synchronization announcement is increased by 1 compared with the target announcement, the terminal load information is the resource occupancy rate of the second tower terminal, and the timestamp is the time of the second tower terminal broadcast, which can be specifically the current time plus the radio frequency delay.

[0177] The above system construction realizes the collaborative broadcast of multiple tower nodes and forms a distributed synchronization tree. It not only avoids the single point bottleneck, but also can package in the event of failure of a synchronization source. The second tower terminal can quickly resynchronize by receiving synchronization announcements from other synchronization source nodes or other second tower terminals without the need for full network reconstruction.

[0178] The above embodiment provides a transmission tower terminal synchronization system based on collaborative broadcasting, which first selects a certain number of first tower terminals as synchronization source nodes to broadcast synchronization announcements. After the second tower terminals that receive the synchronization announcements perform clock synchronization according to the synchronization announcements, they further update the announcements and broadcast them, thereby realizing the synchronization announcement mechanism of collaborative broadcasting; the above system realizes the decentralized collaboration of transmission tower terminals, and at the same time limits the synchronization range with hop count information. If the second tower terminal, which is not a synchronization source node, receives multiple synchronization announcements at the same time or in a short time, it will make an announcement decision based on the timestamp, hop count information, received signal strength, synchronization source clock accuracy and terminal load information, and select the optimal synchronization announcement as the target announcement for clock synchronization, so that the child node only interacts with the optimal synchronization source, reducing network flooding and delay.

[0179] In some embodiments, the second tower terminal is further configured to classify each synchronization announcement according to the synchronization source identifier to obtain an announcement queue; and select the synchronization announcement with the largest cycle number in each announcement queue to calculate the synchronization quality information.

[0180] Specifically, if the receiving window of the second tower terminal is set longer and the preset broadcast period of the first tower terminal is shorter, the second tower terminal may receive synchronization announcements broadcast by the same synchronization source node for two or even more consecutive periods. At this time, the second tower terminal makes an announcement decision based on the latest synchronization announcement, that is, the one with the largest period number.

[0181] The above embodiment uses the synchronization source identifier and cycle sequence number of the synchronization announcement as a reference to accurately screen out the synchronization announcements belonging to the same first tower terminal and the latest synchronization announcement therein. While ensuring the reliability of the announcement decision, it avoids making decisions on useless and redundant synchronization announcements, and reduces the delay and power consumption required for synchronization.

[0182] Furthermore, the second tower terminal is further configured to remove synchronization announcements with hop count information greater than a preset hop count threshold before classification.

[0183] Specifically, the unlimited forwarding of synchronization announcements may lead to a broadcast storm, causing each non-synchronized source node to receive too many synchronization announcements, resulting in increased power consumption of each node and the entire tower communication system.

[0184] Therefore, the above embodiment sets the synchronization range through hop count information, that is, limits the synchronization announcement broadcast range, avoids broadcast storms through a broadcast suppression strategy, and reduces the power consumption of the tower network.

[0185] Furthermore, the first tower terminal is further configured to obtain terminal load information and a historical maximum synchronization error; and determine a preset period according to the terminal load information and the historical maximum synchronization error.

[0186] The terminal load information is the resource occupancy rate of the terminal on the first tower at this time, which is expressed as a percentage, or may be the channel contention intensity, such as the number of CSMA / CA conflicts.

[0187] The historical maximum synchronization error is the historical maximum value of the clock error of the second tower terminal after synchronization, which performs clock synchronization using the synchronization announcement broadcast by the first tower terminal as the target announcement.

[0188] Specifically, the preset period T new It can be determined by the following formula:

[0189]

[0190] Among them, Tbase is the preset basic period, such as 10 seconds; a is the load sensitivity coefficient, the default value is 0.5.

[0191] L max The upper limit threshold of the terminal load is usually 90%. net This is the terminal load information.

[0192] β is the error sensitivity coefficient, which generally defaults to 0.1 / ms; E is the maximum historical synchronization error.

[0193] In the preset period determination rule defined in the above embodiment, L net The larger the value, the longer the cycle, thereby reducing the broadcast frequency when the load is high and avoiding congestion; the larger the value of E, the smaller the cycle, that is, shortening the cycle when the error increases and improving synchronization accuracy.

[0194] Furthermore, the second tower terminal is specifically used to sample and average the signal according to the received synchronization announcement to obtain the received signal strength; map the received signal strength according to the preset strength range to obtain the link quality index; calculate the transmission delay based on the timestamp and the synchronization source clock accuracy; normalize the hop number information, link quality index, transmission delay, synchronization source clock accuracy and terminal load information, and perform weighted calculation to obtain the synchronization quality information.

[0195] Specifically, first take the average of multiple samples of the received signal:

[0196]

[0197] Among them, RSSI i is the signal strength of the i-th sampling, N is the number of sampling times, which can be 10 times.

[0198] This application takes the average of multiple samples of the received signal because this application is applied to the transmission tower terminal. In order to reduce the path loss of electric energy, the transmission network in the uninhabited area generally transmits electric energy at ultra-high voltage or even ultra-high voltage. Therefore, it can be assumed that there are high-voltage lines around the transmission tower terminal, and strong electromagnetic noise will be generated around the high-voltage lines, affecting the stability of wireless communication. Therefore, when calculating the received signal strength, this application takes the average of multiple samples to eliminate instantaneous interference.

[0199] Then the received signal strength RSSI is converted into the link quality indicator R norm :

[0200]

[0201] Among them, RSSI max and RSSI min The signal strength range is within a preset reasonable range, such as -120dBm to -40dBm.

[0202] Furthermore, the second tower terminal is specifically used to obtain the reception time of the synchronization announcement; subtract the timestamp from the reception time to obtain the transmission time difference; and subtract the synchronization source clock delay from the transmission time difference to obtain the transmission delay.

[0203] Specifically, first calculate the transmission time difference Total Diff :

[0204] Total Diff =T recv -T s

[0205] Among them, T recv is the receiving time (specifically a moment), T s This is the timestamp in the synchronization announcement.

[0206] Then, because the transmission time difference includes the transmission delay d and the clock delay, the transmission delay d is calculated as:

[0207] d=Total Diff -Δ

[0208] Where Δ is the synchronization source clock delay recorded in the synchronization announcement.

[0209] The synchronization quality information Q can be calculated using the following formula:

[0210]

[0211] Among them, h norm is the hop count information in the synchronization announcement, and w1 to w5 are the parameter weights of the corresponding parameters.

[0212] The above embodiment takes into account the influence of electromagnetic interference from the surrounding high-voltage lines on the second tower terminal, as well as weather factors, its own faults, and possible geographical factors between the first tower terminal and the like. The quality of the synchronization source is calculated based on the weighted calculation of the above multiple parameters to select the optimal synchronization source for synchronization, thereby reducing network delay. If a synchronization source node fails or malfunctions, the second tower terminal can quickly resynchronize through other synchronization announcements received without the need for full network reconstruction.

[0213] Furthermore, the second tower terminal is also used to obtain various synchronization announcements corresponding to the same synchronization source identifier; calculate the quality parameters of each synchronization announcement; the quality parameters include hop count information, link quality indicators, transmission delay, synchronization source clock accuracy and terminal load information; calculate the corresponding parameter weight according to the change rate of each quality parameter; and perform weighted calculation on the quality parameters according to the parameter weight to obtain synchronization quality information.

[0214] “Synchronization announcements corresponding to the same synchronization source identifier” refer to synchronization announcements continuously sent by a first tower terminal at a preset period. The synchronization announcements here are arranged according to the period sequence numbers therein, reflecting the time sequence of changes in quality parameters.

[0215] The specific calculation process of the quality parameter is consistent with the above embodiment and will not be described in detail here.

[0216] The link quality index R norm For example, the rate of change can be calculated using the following function:

[0217]

[0218] The rate of change of each quality parameter is negatively correlated with the corresponding parameter weight:

[0219]

[0220] That is, the higher the rate of change, the lower the weight, which suppresses the influence of unstable parameters.

[0221] Furthermore, in addition to considering the rate of change, if the quality parameter exceeds the corresponding threshold, its parameter weight can be directly increased by a preset step size. For example, if the terminal load information is greater than the terminal load upper limit threshold, the corresponding parameter weight is increased by 0.2.

[0222] The above embodiment provides a dynamic parameter weight adjustment strategy based on real-time network status, which improves the adaptability and robustness of synchronization quality information calculation for synchronization source nodes.

[0223] Furthermore, the second tower terminal is specifically used to subtract the local clock of the second tower terminal from the synchronization source clock to obtain the clock deviation; determine whether the clock deviation is less than or equal to the preset clock threshold; if so, add the local clock to the clock deviation; if not, gradually adjust the local clock according to the PID algorithm.

[0224] Specifically, if the clock deviation is small, the local clock and the clock deviation can be directly set to be added. If the clock deviation is large, that is, the degree of synchronization adjustment required is large, in order to avoid clock jumps, the PID algorithm is used to gradually adjust the local clock frequency and compensate for the drift rate until the local clock frequency is synchronized with the synchronization source clock frequency.

[0225] The specific limitations of the collaborative broadcast-based transmission tower terminal synchronization system provided in this embodiment can be found in the embodiment of the collaborative broadcast-based transmission tower terminal synchronization method described above and will not be repeated here. Each module in the collaborative broadcast-based transmission tower terminal synchronization device described above can be implemented in whole or in part through software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor in a computer device in hardware form, or can be stored in a computer device memory in software form, so that the processor can call and execute the corresponding operations of each of these modules.

[0226] The various embodiments described in this application may be independent solutions or combined according to internal logic, and all of these solutions fall within the scope of protection of this application. It is understood that in the various method embodiments described above, the methods and operations implemented by the first tower terminal may also be implemented by components (such as chips or circuits) applicable to the first tower terminal, and the methods and operations implemented by the second tower terminal may also be implemented by components (such as chips or circuits) applicable to the second tower terminal.

[0227] To implement the various functions of the methods provided in the embodiments of the present application, the first tower terminal and the second tower terminal may include hardware structures and / or software modules, and implement the aforementioned functions in the form of hardware structures, software modules, or a combination of hardware structures and software modules. Whether a particular function is implemented in the form of hardware structures, software modules, or a combination of hardware structures and software modules depends on the specific application and design constraints of the technical solution.

[0228] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0229] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A transmission tower terminal synchronization method based on cooperative broadcasting, characterized in that: include: Using multiple first tower terminals as synchronization source nodes to broadcast synchronization announcements at a preset period; The second tower terminal receives at least one of the synchronization announcements; The second tower terminal obtains the timestamp, hop count information, received signal strength, synchronization source clock accuracy and terminal load information according to the synchronization announcement, and calculates the synchronization quality information of the synchronization announcement; The second tower terminal determines a target announcement in the synchronization announcement according to the synchronization quality information; The second tower terminal adjusts the local clock according to the synchronization source clock accuracy announced by the target; The second tower terminal updates the target announcement, obtains a new synchronization announcement, and broadcasts it.

2. The transmission tower terminal synchronization method based on cooperative broadcasting according to claim 1, characterized in that: The synchronization announcement includes a timestamp, a synchronization source identifier, hop count information, terminal load information, synchronization source clock accuracy, and a cycle sequence number; The synchronization source clock accuracy includes the synchronization source clock and the synchronization source clock delay.

3. The transmission tower terminal synchronization method based on cooperative broadcasting according to claim 2, characterized in that: Also includes: The second tower terminal classifies each synchronization announcement according to the synchronization source identifier to obtain an announcement queue; The synchronization quality information is calculated by selecting the synchronization announcement with the largest cycle number in each of the announcement queues.

4. The transmission tower terminal synchronization method based on cooperative broadcasting according to claim 3, characterized in that: Also includes: Before classification, the second tower terminal removes the synchronization announcements whose hop count information is greater than a preset hop count threshold.

5. The transmission tower terminal synchronization method based on cooperative broadcasting according to claim 2, characterized in that: The second tower terminal obtains a timestamp, hop count information, received signal strength, synchronization source clock accuracy, and terminal load information according to the synchronization announcement, and calculates synchronization quality information of the synchronization announcement, including: Performing signal sampling and averaging according to the received synchronization announcement to obtain the received signal strength; Mapping the received signal strength according to a preset strength range to obtain a link quality indicator; Calculating a transmission delay based on the timestamp and the synchronization source clock accuracy; The hop count information, the link quality indicator, the transmission delay, the synchronization source clock accuracy and the terminal load information are normalized and then weighted calculated to obtain the synchronization quality information of the synchronization announcement.

6. The transmission tower terminal synchronization method based on cooperative broadcasting according to claim 5, characterized in that: The calculating the transmission delay based on the timestamp and the synchronization source clock accuracy includes: Obtaining the reception time of the synchronization announcement; Subtract the timestamp from the reception time to obtain a transmission time difference; The transmission delay is obtained by subtracting the synchronization source clock delay from the transmission time difference.

7. The transmission tower terminal synchronization method based on cooperative broadcasting according to claim 5, characterized in that: Also includes: The second tower terminal obtains the synchronization announcements corresponding to the same synchronization source identifier; Calculating quality parameters of each of the synchronization announcements; The quality parameters include the hop count information, the link quality indicator, the transmission delay, the synchronization source clock accuracy and the terminal load information; Calculating corresponding parameter weights according to the change rates of the respective quality parameters; The quality parameter is weightedly calculated according to the parameter weight to obtain the synchronization quality information.

8. The transmission tower terminal synchronization method based on cooperative broadcasting according to claim 2, characterized in that: The second tower terminal adjusts the local clock according to the synchronization source clock accuracy announced by the target, including: Subtract the local clock of the second tower terminal from the synchronization source clock to obtain a clock deviation; Determining whether the clock deviation is less than or equal to a preset clock threshold; If yes, add the local clock to the clock deviation; If not, the local clock is gradually adjusted according to the PID algorithm.

9. The transmission tower terminal synchronization method based on cooperative broadcasting according to claim 2, characterized in that: The second tower terminal updates the target announcement, obtains a new synchronization announcement, and broadcasts it, including: Increment the hop count information in the target announcement by 1; updating the terminal load information in the target announcement according to the current resource occupancy rate; The timestamp in the target announcement is updated according to the current time, and a new synchronization announcement is obtained and broadcast.

10. A transmission tower terminal synchronization system based on cooperative broadcasting, characterized in that: It includes a plurality of first pole tower terminals and a plurality of second pole tower terminals; each of the first pole tower terminals serves as a synchronization source node; The first tower terminal is used to broadcast synchronization announcements at a preset period; The second tower terminal is used to receive at least one of the synchronization announcements; obtain a timestamp, hop count information, received signal strength, synchronization source clock accuracy, and terminal load information according to the synchronization announcement, and calculate synchronization quality information of the synchronization announcement; and, determining a target announcement in the synchronization announcement according to the synchronization quality information; and adjusting a local clock according to the synchronization source clock accuracy of the target announcement; The target announcement is updated, a new synchronization announcement is obtained and broadcasted.

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