CN100525212C - Method and system for network clock synchronous - Google Patents
Method and system for network clock synchronous Download PDFInfo
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- CN100525212C CN100525212C CNB2007101357478A CN200710135747A CN100525212C CN 100525212 C CN100525212 C CN 100525212C CN B2007101357478 A CNB2007101357478 A CN B2007101357478A CN 200710135747 A CN200710135747 A CN 200710135747A CN 100525212 C CN100525212 C CN 100525212C
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Abstract
This invention discloses a method and a system for synchronizing network clocks, which sets synchronous source nodes with mutual redundance in a wireless sensor network to design them a working clock node and a backup clock source node and selects a regional master clock node in network node to form a synchronous queue, the network node asks for clock synchronization to the nodes in the synchronous queue, the backup clock source node computes the mean queue synchronous clock based on the difference between the local clock and the synchronous clock of the working clock node and sends it to the regional master clock node in the queue so as to realize clock rectification to the regional master clock.
Description
Technical field
The present invention relates to wireless communication field, the synchronous method and system of particularly a kind of network clocking.
Background technology
Development along with wireless technology, microelectric technique, sensor technology, wireless sensor network is subjected to academia and industrial quarters attention more and more widely because of its great application prospect, the high precision clock of each node is the prerequisite that wireless sensor network is used in the industry spot that high real-time requires synchronously in the wireless sensor network, also is the basis of realizing communication scheduling between each node.In present wireless sensor network, be provided with a work clock source node, and the network node of some is set to regional master clock node, described regional master clock node forms isochronous queue, and is synchronous to the request of work clock source node; Other node in the network is an ordinary node, and described ordinary node is to regional master clock node request clock synchronization, thereby realization and work clock source node is synchronous.
At the high real-time requirement of industry spot application to wireless sensor network, that generally adopt at present is time synchronization protocol (Timing-sync Protocol for Sensor Networks, TPSN) or reference-broadcast clock synchronization protocol (reference broadcast synchronization algorithm, RBS) clock synchronization of each node on the realization wireless sensor network, its basic operation principle is that the regional master clock node in the wireless sensor network all is synchronized on the work clock source node, carry out synchronous coordination, thereby realize the clock synchronization of all nodes of wireless sensor network.
But, if the work clock source node in the wireless sensor network breaks down, the clock of zone master clock joint can be subjected to the influence of work clock source node, can not be synchronous with described work clock source node, the clock of zone master clock node will cause confusion, and then influence the clock of ordinary node, finally cause system crash.
Simultaneously, in large-scale industry spot is used, the formation multilayered structure of wireless sensor network also impacts the network clocking precise synchronization of system, each internodal synchronization accuracy descends rapidly along with the increase of formation, has therefore limited the application of wireless sensor network at high real-time large-scale industry scene to a great extent.
Summary of the invention
Embodiment of the invention problem to be solved provides the synchronous method and system of a kind of network clocking, to solve the system crash that causes owing to the wireless sensor network clock source failure, reaches the problem that wireless sensor network can't be applied to the large-scale industry scene.
For addressing the above problem, the invention provides the synchronous method of a kind of network clocking, described method comprises step:
The redundancy clock source node be set, and realize the clock synchronization between the described redundancy clock source node, and to set at least one described redundancy clock source node be the work clock source node that other redundancy clock source node is set at the standby clock source node in network; If described work clock source node is in abnormal operating state, described work clock source node is initiated redundant the switching, and described standby clock source node is set at the work clock source node;
In the network ordinary node, select regional master clock node, be specially: the network ordinary node receives the formation generation message that the redundancy clock source node generates, produce a random number, greater than regional master clock threshold value, then setting this ordinary node is regional master clock node as if described random number;
Make head of the queue with described work clock source node, the standby clock source node is made tail of the queue, and described regional master clock node forms isochronous queue for the member;
Described regional master clock node its last node request clock synchronization in described isochronous queue, ordinary node communicates with top-quality node request clock synchronization in described isochronous queue;
Described standby clock source node calculates the accumulative total synchronism deviation of clock synchronization, and according to the described number that adds up node in synchronism deviation and the formation, obtains the average clock synchronism deviation of formation;
Described standby clock source node sends the average clock synchronism deviation of described formation to described regional master clock node, realizes the clock correction.
Wherein, judge that the concrete steps that described work clock source node is in abnormal operating state comprise:
Described work clock source node residual amount of energy is lower than default energy residual value, perhaps,
Described work clock source node energy consumption is greater than default energy consumption values, perhaps,
Described work clock source node fault level is higher than described standby clock source node.
In the synchronous method of network clocking provided by the invention, realize that the clock synchronization between the described redundancy clock source node is specially:
Described redundancy clock source node is installed the GPS receiving instrument respectively and is communicated, thereby realizes clock synchronization; Perhaps,
Use the radio communication of non-interfering frequency between the described redundancy clock source node, thereby realize clock synchronization; Perhaps,
Described redundancy clock source node connects by cable network, thereby realizes clock synchronization.
In the synchronous method of network clocking provided by the invention, the concrete steps of setting work clock source node and standby clock source node are:
Described redundancy clock source node enters init state;
Described redundancy clock source node is created the formation that comprises equipment of itself queue number and preset state and is generated message, and sends described formation and generate the node of message to the network;
Described redundancy clock source node enters operating state and is set at the work clock source node according to preset state, perhaps, enters stand-by state and is set at the standby clock source node.
In the synchronous method of network clocking provided by the invention, in the network ordinary node, select regional master clock node also to comprise step:
The described regional master clock node that is set generates a last node device queue number and a preset state in the message according to the described formation that receives, setting the equipment of itself queue number is that a last node device queue number adds one, oneself state is identical with a last node preset state, the formation of creating self generates message, and with its transmission.
In the synchronous method of network clocking provided by the invention, if receiving formation once more, described regional master clock node or described ordinary node generate message, do not carry out any processing.
In the synchronous method of network clocking provided by the invention, the equipment of itself queue number of described redundancy clock source node is 0, and preset state is operating state or stand-by state.
In the synchronous method of network clocking provided by the invention, the concrete steps of described regional master clock node or ordinary node request clock synchronization are:
Described regional master clock node or ordinary node send the first synchronous pulse data bag that comprises delivery time T1 at moment T1 to selecteed isochronous queue node;
Described selecteed isochronous queue node receives described synchronous pulse data bag at moment T2, and replys the second synchronous pulse data bag that comprises moment T1, T2, T3 at moment T3 to described regional master clock node or ordinary node;
Described regional master clock node or ordinary node receive the described second synchronous pulse data bag at moment T4;
Described regional master clock node or ordinary node according to described moment T1, T2, T3, T4 calculates with described selecteed formation in the time clock correction Δ t of node, according to formula
t′＝t+Δt，
The clock synchronization of realization and described selecteed isochronous queue node,
Wherein, the clock value after described regional master clock node of t ' expression or the ordinary node request synchronously, t are represented the clock value that described regional master clock node or ordinary node request are preceding synchronously.
In the synchronous method of network clocking provided by the invention, described standby clock source node synchronous accumulative total synchronism deviation computing time is specially:
Described standby clock source node according to the difference of the standard time clock that clock synchronization obtained of described work clock source node and the local master clock that himself in described isochronous queue, obtains, obtain the accumulative total synchronism deviation of clock synchronization.
In the synchronous method of network clocking provided by the invention, described standby clock source node obtains the average clock synchronism deviation of formation and is specially according to the number of node in described accumulative total synchronism deviation and the isochronous queue:
Wherein, u represents the average synchronism deviation of formation, and Δ U represents the accumulative total synchronism deviation, and N represents the number of Area Node in the described formation.
In the synchronous method of network clocking provided by the invention, described standby clock source node sends the average clock synchronism deviation of described formation to described regional master clock node, realizes that the clock correction is specially:
t1′＝t1-u*n
Wherein, the clock value after the described regional master clock node correction of t1 ' expression, t1 represents the clock value before the described regional master clock node correction, and u represents the average synchronism deviation of formation, and n represents the equipment of itself queue number of described regional master clock node.
Correspondingly, the present invention also provides a kind of network clocking synchronous system, and described system comprises:
Lock unit is used to realize the clock synchronization between the redundancy clock source node;
The operating state setup unit is used for described redundancy clock source node is set at work clock source node and standby clock source node respectively;
Redundant switch unit is used for when described work clock source node is in abnormal operating state described standby clock source node being set at the work clock source node;
Zone master clock selected cell is used for selecting regional master clock node at the network ordinary node;
Formation forms the unit, and being used to form with described work clock source node is head of the queue, and the standby clock source node is a tail of the queue, and with the described regional master clock node isochronous queue that is the member;
The clock synchronization request unit is used for the node request clock synchronization of network node to isochronous queue; The clock jitter computing unit is used for the accumulative total synchronism deviation that the standby clock source node calculates clock synchronization, and according to the described number that adds up node in synchronism deviation and the formation, calculates the average clock synchronism deviation of formation;
Clock correction unit is used for according to the average clock synchronism deviation of described formation, realizes clock compensation at described regional master clock node;
Wherein, regional master clock selected cell comprises:
Message receives subelement, is used to receive the formation generation message that the redundancy clock source node generates;
Zone master clock node is judged subelement, is used for random number and predefined regional master clock threshold value that network node produces are compared, and greater than described threshold value, then selecting described node is regional master clock node as if described random number;
The clock synchronization request unit comprises:
The first local master clock chooser unit is used for described regional master clock node and selects the clock of its last node of formation as local master clock;
The communication quality judgment sub-unit is used for judging the communication quality of described ordinary node and isochronous queue node;
The second local master clock chooser unit, that be used for selecting obtaining and the local master clock of the clock best isochronous queue node of described ordinary node communication quality as described ordinary node according to described communication quality judgment sub-unit.
In the synchronous system of network clocking provided by the invention, described redundant switch unit comprises:
The operating state judgment sub-unit is used to judge whether the operating state of described work clock source node is normal.
In the synchronous system of network clocking provided by the invention, described lock unit comprises:
The GPS subelement is used to realize that the GPS between described redundancy clock source node communicates by letter;
The radio communication subelement is used to realize the radio communication between described redundancy clock source node;
Network connexon unit is used to realize that the network between described redundancy clock source node connects communication.
In the synchronous system of network clocking provided by the invention, described operating state setup unit comprises:
The state exchange subelement is used for according to preset state, and described redundancy clock source node is converted to operating state or stand-by state by init state;
First message is created subelement, is used for creating formation generation message according to the equipment of itself queue number and the preset state of described redundancy clock source node;
First message sends subelement, is used for described formation is generated the node that message is sent to network.
In the synchronous system of network clocking provided by the invention, described regional master clock selected cell also comprises:
Subelement is set, is used for generating a last node device queue number of message and device queue that preset state is set described regional master clock node number and state according to the described formation that receives;
Second message is created subelement, is used for creating formation according to the device queue of described regional master clock node number and state and generates message;
Second message sends subelement, is used to send the formation generation message of described regional master clock node.
In the synchronous system of network clocking provided by the invention, described clock synchronization request unit also comprises:
The pulse data bag sends subelement, is used for network node and sends the first or second pulse data bag;
The pulse data bag receives subelement, is used for network node and receives the first or second pulse data bag;
The timing subelement is used to write down the local master clock node of moment T1, the first local master clock chooser unit or the second local master clock chooser unit that described regional master clock node or ordinary node send the described first pulse data bag selecting and receives the moment T2 of the first pulse data bag, described local master clock node and send the moment T4 that the moment T3 of the second pulse data bag and described regional master clock node or ordinary node receive the second pulse data bag;
The clock synchronization computation subunit is used for according to described moment T1, T2, T3 and T4, calculates the time difference Δ t of described regional master clock node or ordinary node and local master clock node, according to formula
t′＝t+Δt，
The clock synchronization of realization and described local master clock node,
Wherein, the clock value after described regional master clock node of t ' expression or the ordinary node request synchronously, t are represented the clock value that described regional master clock node or ordinary node request are preceding synchronously.
In the synchronous system of network clocking provided by the invention, described clock jitter computing unit comprises:
Accumulative total clock jitter computation subunit, be used for the difference of standby clock source node, obtain the accumulative total synchronism deviation Δ U of time synchronized according to the lock unit local master clock that obtains with the lock in time work clock source node with according to the time synchronized request unit that obtain;
The average clock synchronism deviation of formation computation subunit is used for the number according to described accumulative total synchronism deviation and formation node, calculates the average clock synchronism deviation of formation u,
Wherein, u represents the average synchronism deviation of formation, and Δ U represents the accumulative total synchronism deviation, and N represents the number of Area Node in the described isochronous queue.
In the synchronous system of network clocking provided by the invention, clock correction unit comprises:
The average synchronism deviation of formation sends subelement, is used for the average synchronism deviation of described formation is sent to the regional master clock node of described formation;
Clock correction calculations subelement is used for realizing the correction to described regional master clock node according to the described average clock synchronism deviation that receives,
t1′＝t1-u*n
Wherein, the clock value after the described regional master clock node correction of t1 ' expression, t1 represents the clock value before the described regional master clock node correction, and u represents the average synchronism deviation of formation, and n represents the equipment of itself queue number of described regional master clock node.
Compared with prior art, method and system provided by the invention are provided with redundant each other clock source node in wireless sensor network, wherein setting at least one redundancy clock source node is the work clock source node, other is set at the standby clock source node, realizes between them that high accuracy clock is synchronous.In wireless sensor network, if the work clock source breaks down, described when redundant clock source node state exchange, have the clock source node of operate as normal in the wireless sensor network always, to guarantee the synchronous of network clocking, avoid wireless sensor network to collapse because of clock source failure; Simultaneously, wireless sensor network is in the large-scale industry applications, the average clock synchronism deviation of isochronous queue in the standby clock source node computing network, and send it to regional master clock node in the described isochronous queue, clock to regional master clock node is rectified a deviation, and then realizes the clock synchronization of wireless sensor network.
Description of drawings
Fig. 1 is the synchronous method flow diagram of embodiment of the invention network clocking;
Fig. 2 is that embodiment of the invention redundancy clock source state switches schematic diagram;
Fig. 3 is an embodiment of the invention network node distribution schematic diagram;
Fig. 4 is a formation structural representation in the embodiment of the invention network;
Fig. 5 is the synchronous system construction drawing of embodiment of the invention network clocking;
Fig. 6 is an embodiment of the invention zone master clock selected cell structure chart.
Embodiment
Below in conjunction with drawings and Examples the present invention is done detailed explanation.
The embodiment of the invention provides a kind of network clocking synchronous method, sees also Fig. 1, specifically comprises step:
Step S101: the redundancy clock source node is set in network, and realizes the clock synchronization between the described redundancy clock source node, and set at least one work clock source node, other redundancy clock source node is set at the standby clock source node;
Step S102: select regional master clock node in the network ordinary node, and make head of the queue with described work clock source node, the standby clock source node is made tail of the queue, and described regional master clock node forms isochronous queue for the member;
Step S103: described regional master clock node its last node request clock synchronization in described isochronous queue, ordinary node communicates with top-quality node request clock synchronization in described formation.
In the method that the embodiment of the invention provided, have a plurality of redundancy clock source nodes in the wireless sensor network, wherein at least one is set at the work clock source node, other is set at the standby clock source node, realize between the described redundancy clock source node that high precision clock is synchronous, according to concrete network size difference, can use different communication modes to realize that the high precision clock between described redundancy clock source node is synchronous:
If the network area radius greater than 10 kms, is then installed the GPS receiving instrument respectively at described redundancy clock source node and communicated, thereby realize the nanosecond clock synchronization of described redundancy clock source node;
If the network area radius is in 10 kms, then the high precision clock that the radio communication of the non-interfering frequency of use realizes between described redundancy clock source node is synchronous, for example wireless sensor network uses the 2.4G frequency range, and then described redundancy clock source node can use the frequency range of 5G to carry out synchronizing process.Owing to there is not extra packet exchange task, therefore can carry out frequent time synchronized task between two clock source nodes;
If the network area radius less than 1 km, then uses cable network to connect described redundancy clock source node,, realize that hundred nanosecond are with interior clock synchronization accuracy between the described redundancy clock source node as high accuracy clock protocols such as use IEEE1588.
Described redundancy clock source node has three kinds of states: " initialization ", " operating state " reach " stand-by state ", described redundancy clock source node enters " initialization " state after powering on, transmit queue enters " operating state " or " stand-by state " according to preset state after generating the node of message to the network.
Be in the redundancy clock source node of " initialization " state, generate message, realize the division of isochronous queue structure, thereby generate isochronous queue by transmit queue.Formation generates the device queue number that message has been stated node self, and wherein, the device queue of described redundancy clock source node number is 0.Described redundancy clock source node changes " operating state " or " stand-by state " over to according to preset state.
If the work clock source node is in abnormal operating state, then described work clock source node is initiated redundant the switching, and notice standby clock source node initiation state switches, and the schematic diagram that state switches as shown in Figure 2, state is switched to " operating state ", become new operation source node.
Wherein, judgment task clock source node is in the concrete steps of abnormal operating state and is:
Work clock source node dump energy is lower than predefined minimum energy lower limit, and remaining energy can not be kept its normal work, perhaps
The energy value that the work clock source node consumes is excessive, greater than predefined energy consumption values, perhaps
The fault level of work clock source node is higher than the fault level of standby clock source node.
Ordinary node in the network receives formation and generates message, produces a random number, if this random number is greater than predefined regional master clock threshold value, then this node is set at regional master clock node, otherwise is ordinary node, the schematic diagram that node distributes in the network sees also shown in Figure 3.
Wherein, the regional master clock joint in the network is a head of the queue with the work clock source node, and the standby clock source node is a tail of the queue, forms isochronous queue, specifically sees also shown in Figure 4.
The device queue of zone master clock node self number is set at the device queue that comprised in the formation generation message that a node sends and number adds one, it is identical that the state of self and the formation that receives generate the preset state that is comprised in the message, and be local master clock with the clock setting that transmit queue generates a last node of message, to its request clock synchronization.The formation that zone master clock node sends self generates message other node to the network, and generates message for the formation that repeats to receive and no longer handle.
Ordinary node select in the isochronous queue one with the best node of himself communication quality, and ask clock synchronization to it.This selecteed node may be regional master clock node, also may be work clock source node or standby clock source node, and with the clock of this selecteed node as local master clock.
Described regional master clock node or ordinary node adopt the TPSN mode to its local master clock request clock synchronization, are example with regional master clock node, and concrete implementation procedure is as follows:
Zone master clock node is to its local master clock node request clock synchronization, and this zone master clock node sends the first lock-out pulse bag at this locality moment T1 to described local master clock node, includes T1 constantly in the first lock-out pulse bag.Described local master clock node receives the lock-out pulse bag at this locality moment T2, and its local T3 constantly send comprise T1, T2 and T3 value constantly the second lock-out pulse bag to described regional master clock node, described regional master clock node receives described second sync packet at this locality moment T4.
Described regional master clock node is according to described T1, T2, and the value of T3 and T4 calculates the time clock correction Δ t with local master clock node, according to formula
t′＝t+Δt，
Realization is synchronous with local master clock node, and wherein, the clock value after the described regional master clock node of the t ' expression request synchronously, t are represented the clock value that the request of described regional master clock node is preceding synchronously.
Ordinary node is identical to the method and the said method of its local master clock request clock synchronization, just local master clock node is changed to by a last node in the isochronous queue and communicates with top-quality node in the isochronous queue, and detailed process repeats no more.
In the synchronous method of described network clocking, use the raising that the standby clock source node is realized clock accuracy.The standby clock source is as " feedback sources " in work clock source, and the node of device queue maximum in the formation as local master clock node, is synchronized with this this locality master clock with local clock.Simultaneously, the standby clock source node is safeguarded and the complete synchronous local standard clock of work clock source node, deducts local clock with described local standard clock, obtains accumulative total synchronism deviation Δ U.
The standby clock source node passes through formula according to the number of regional master clock node in described accumulative total synchronism deviation Δ U and the formation
Calculate the average synchronism deviation of formation, wherein, u represents the average synchronism deviation of formation, and Δ U represents the accumulative total synchronism deviation, and N represents the number of Area Node in the described formation.
The standby clock source node is finished the aforementioned calculation step, and the average synchronism deviation of described formation is sent to regional master clock node in the isochronous queue, realizes the clock correction of regional master clock node, and concrete implementation is as follows:
t1′＝t1-u*n
Wherein, the clock value after the regional master clock node correction of t1 ' expression, t1 represents the clock value before the regional master clock node correction, and u represents the average synchronism deviation of formation, and n represents the equipment of itself queue number of regional master clock node.
Use the method that the embodiment of the invention provided, clock high level of synchronization, redundant clock source node each other are set in wireless sensor network, the system crash that can make wireless sensor network avoid the fault because of the work clock source to cause, and wireless sensor network is applied in the large-scale industry occasion.
Correspondingly, the embodiment of the invention also provides a kind of network clocking synchronous system, sees also Fig. 5, and described system comprises:
Operating state setup unit 502 is used for described redundancy clock source node is set at work clock source node and standby clock source node respectively;
Zone master clock selected cell 503 is used for selecting regional master clock node at the network ordinary node;
Clock synchronization request unit 505 is used for the node request clock synchronization of network node to synchronization node.
The system that the network clocking that the embodiment of the invention provided is synchronous, also comprise: clock jitter computing unit 506, be used for the accumulative total synchronism deviation that the standby clock source node calculates clock synchronization, and, calculate the average clock synchronism deviation of formation according to the described number that adds up node in synchronism deviation and the formation;
Use the system that the embodiment of the invention provided, realize that the synchronizing process of wireless sensor network clock is specially:
Operating state setup unit 502 is set at work clock source node and standby clock source node respectively with the redundancy clock source node, described work clock source node and standby clock source node are in " initialization " state after powering on, comprising the equipment of itself queue number by 5022 establishments of first message establishment subelement is 0, the formation of self preset state generates message, and send subelement 5023 by first message and described formation is generated message be sent to other node in the network, and enter " operating state " or " stand-by state " by state conversion unit 5021 according to preset state.
The network ordinary node carries out the selection of regional master clock node by regional master clock selected cell 503, the network ordinary node receives subelement 5031 by message and receives formation generation message, at first generate a random number, judge that by regional master clock node identifying unit 5032 whether this random number is greater than predefined regional master clock threshold value, if this random number is greater than described regional master clock threshold value, then this node is set at regional master clock node, otherwise is ordinary node by subelement 5033 is set; Zone master clock node is created subelement 5034 by second message and self device queue number is set at the device queue that institute receives in the formation generation message of receiving number is added one, and it is the setting state of self is identical with the preset state that receives, and according to above-mentioned self device queue number and oneself state, the formation of creating self generates message, and sends subelement 5035 with this formation generation message transmission by second message.
The formation that zone master clock node counterweight multiple connection is received generates message and does not handle.After zone master clock selected cell 503 is finished the step of above-mentioned selection zone master clock node, it is head of the queue with the work clock source node that formation forms unit 504, the standby clock source node is a tail of the queue, according to the distance of regional master clock source node and work clock source node distance, generates isochronous queue.
The structure of clock synchronization request unit 505 sees also Fig. 6, and be used for regional master clock node and ordinary node and select local master clock node, and to its request clock synchronization.Zone master clock node is by the first local master clock selected cell 5051, and to send the node that its received formation generates message, promptly its a last node is local master clock node in the isochronous queue; Ordinary node is selected and the best node of its communication quality in isochronous queue by communication quality judgment sub-unit 5052, and should be set at local master clock node by top-quality node by the second local master clock chooser unit 5053.
Described regional master clock node and ordinary node are to separately local master clock node request clock synchronization.The described request clock synchronization adopts the TPSN mode, is example with regional master clock node, and concrete implementation procedure is as follows:
Zone master clock node is to its local master clock node request clock synchronization, this zone master clock node sends subelement 5054 at this locality moment T1 by the pulse data bag and sends the first lock-out pulse bag to described local master clock node, comprises T1 constantly in the first lock-out pulse bag.Described local master clock node receives subelement 5055 at this locality moment T2 by the pulse data bag and receives the lock-out pulse bag, and its local T3 constantly send comprise T1, T2 and T3 value constantly the second lock-out pulse bag to described regional master clock node, described regional master clock node receives described second sync packet at this locality moment T4.Wherein, the timing of T1, T2, T3 and T4 is finished by timing subelement 5056 constantly.
Described regional master clock node is according to described T1, T2, and the value of T3 and T4 by clock synchronization computation subunit 5057, calculates the time clock correction Δ t with local master clock node, according to formula
t′＝t+Δt，
Realization is synchronous with this master clock node, and wherein, the clock value after the described regional master clock node of the t ' expression request synchronously, t are represented the clock value that the request of described regional master clock node is preceding synchronously.
Ordinary node is identical to the method and the said method of its local master clock request clock synchronization, just local master clock node is changed to by a last node in the isochronous queue and communicates with top-quality node in the isochronous queue, and detailed process repeats no more.
In the synchronous system of described network clocking, use the raising that the standby clock source node is realized clock accuracy.The standby clock source is as " feedback sources " in work clock source, and the node of device queue maximum in the formation as local master clock node, is synchronized with this this locality master clock with local clock.Described standby clock source node uses clock jitter computing unit 506, obtains accumulative total synchronism deviation and the average synchronism deviation of formation.Concrete process is as follows:
In the synchronous system of described network clocking, use the raising that the standby clock source node is realized clock accuracy.The standby clock source is as " feedback sources " in work clock source, and the node of device queue maximum in the formation as local master clock node, is synchronized with this this locality master clock with local clock.Simultaneously, the standby clock source node is safeguarded and the complete synchronous local standard clock of work clock source node by lock unit 501, and, deduct local clock with described local standard clock by accumulative total clock jitter computation subunit 5061, obtain accumulative total synchronism deviation Δ U.
The standby clock source node by the average synchronism deviation computation subunit 5062 of formation, uses formula according to the number of regional master clock node in described accumulative total synchronism deviation Δ U and the formation
Calculate the average synchronism deviation of formation, wherein, u represents the average synchronism deviation of formation, and Δ U represents the accumulative total synchronism deviation, and N represents the number of regional master clock node in the described isochronous queue.
After the standby clock source node obtains the average synchronism deviation of described formation, use clock correction unit 507 to realize the clock of the regional master clock node in the formation is rectified a deviation, detailed process is:
The standby clock source node sends subelement 5071 by the average synchronism deviation of formation the average synchronism deviation of described formation is sent to regional master clock node in the formation, and uses formula by clock correction calculations subelement 5072:
t1′＝t1-u*n
Realize the correction of regional master clock nodal clock,
Wherein, the clock value after the regional master clock node correction of t1 ' expression, t1 represents the clock value before the regional master clock node correction, and u represents the average synchronism deviation of formation, and n represents the equipment of itself queue number of regional master clock node.
The standby clock source node is realized with the high precision clock of work clock node synchronous by the redundancy clock source node in said process, difference according to network size, can use GPS subelement 5011, radio communication subelement 5012, network connexon unit 5013 to realize the function of described clock synchronization respectively, be specially:
If the network area radius greater than 10 kms, then communicates by GPS subelement 5011, thereby realize the nanosecond clock synchronization of described redundancy clock source node;
If the network area radius is in 10 kms, then synchronous by the high precision clock of radio communication subelement 5012 realizations, for example wireless sensor network uses the 2.4G frequency range, and then described redundancy clock source node can use the frequency range of 5G to carry out synchronizing process.Owing to there is not extra packet exchange task, therefore can carry out frequent time synchronized task between two clock source nodes;
If the network area radius less than 1 km, then connects described redundancy clock source node by network connexon unit 5013,, realize that hundred nanosecond are with interior clock synchronization accuracy between the described redundancy clock source node as high accuracy clock protocols such as use IEEE1588.
When the work clock source node is in abnormal operating state, realize that by redundant switch unit 508 state exchange with former standby operation source node is " operating state ", set it and be new work clock source node; The state exchange of former work clock source node is " stand-by state ".The work clock source node is specially by the judgement of operating state judgment sub-unit 5081 realization operating states:
Work clock source node dump energy is lower than predefined minimum energy lower limit, and remaining energy can not be kept its normal work, perhaps
The energy value that the work clock source node consumes is excessive, greater than predefined energy consumption values, perhaps
The fault level of work clock source node is higher than the fault level of standby clock source node.
When above-mentioned situation occurring, the redundant subelement 508 that switches will be carried out handoff procedure, and the state of finishing the work between clock source node and standby clock source node switches.
Use the system that the embodiment of the invention provided, clock high level of synchronization, redundant clock source node each other are set in wireless sensor network, the system crash that can make wireless sensor network avoid the fault because of the work clock source to cause, and wireless sensor network is applied in the large-scale industry occasion.
The above only is a preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (19)
1, the synchronous method of a kind of network clocking is characterized in that, described method comprises step:
The redundancy clock source node be set, and realize the clock synchronization between the described redundancy clock source node, and to set at least one described redundancy clock source node be the work clock source node that other redundancy clock source node is set at the standby clock source node in network; If described work clock source node is in abnormal operating state, described work clock source node is initiated redundant the switching, and described standby clock source node is set at the work clock source node;
In the network ordinary node, select regional master clock node, be specially: the network ordinary node receives the formation generation message that the redundancy clock source node generates, produce a random number, greater than regional master clock threshold value, then setting this ordinary node is regional master clock node as if described random number;
Make head of the queue with described work clock source node, the standby clock source node is made tail of the queue, and described regional master clock node forms isochronous queue for the member;
Described regional master clock node its last node request clock synchronization in described isochronous queue, ordinary node communicates with top-quality node request clock synchronization in described isochronous queue;
Described standby clock source node calculates the accumulative total synchronism deviation of clock synchronization, and according to the described number that adds up node in synchronism deviation and the formation, obtains the average clock synchronism deviation of formation;
Described standby clock source node sends the average clock synchronism deviation of described formation to described regional master clock node, realizes the clock correction.
2, the synchronous method of network clocking according to claim 1 is characterized in that, judges that the concrete steps that described work clock source node is in abnormal operating state comprise:
Described work clock source node dump energy is lower than default energy surplus value, perhaps,
Described work clock source node energy consumption is greater than default energy consumption values, perhaps,
Described work clock source node fault level is higher than described standby clock source node.
3, the synchronous method of network clocking according to claim 1 is characterized in that, realizes that the clock synchronization between the described redundancy clock source node is specially:
Described redundancy clock source node is installed the GPS receiving instrument respectively and is communicated, thereby realizes clock synchronization; Perhaps,
Use the radio communication of non-interfering frequency between the described redundancy clock source node, thus the clock synchronization that realizes; Perhaps,
Described redundancy clock source node connects by cable network, thereby realizes clock synchronization.
4, the synchronous method of network clocking according to claim 1 is characterized in that, the concrete steps of setting work clock source node and standby clock source node are:
Described redundancy clock source node enters init state;
Described redundancy clock source node is created the formation that comprises equipment of itself queue number and preset state and is generated message, and sends described formation and generate the node of message to the network;
Described redundancy clock source node enters operating state and is set at the work clock source node according to preset state, perhaps, enters stand-by state and is set at the standby clock source node.
5, the synchronous method of network clocking according to claim 4 is characterized in that, selects regional master clock node also to comprise step in the network ordinary node:
The described regional master clock node that is set generates a last node device queue number and a preset state in the message according to the described formation that receives, setting the equipment of itself queue number is that a last node device queue number adds one, oneself state is identical with a last node preset state, the formation of creating self generates message, and with its transmission.
6, the synchronous method of network clocking according to claim 5 is characterized in that, generates message if described regional master clock node or described ordinary node receive formation once more, does not carry out any processing.
According to the synchronous method of each described network clocking of claim 4-6, it is characterized in that 7, the equipment of itself queue number of described redundancy clock source node is 0, preset state is operating state or stand-by state.
8, the synchronous method of network clocking according to claim 1 is characterized in that, the concrete steps of described regional master clock node or ordinary node request clock synchronization are:
Described regional master clock node or ordinary node send the first synchronous pulse data bag that comprises delivery time T1 at its local T1 constantly to selecteed isochronous queue node;
Described selecteed isochronous queue node receives described synchronous pulse data bag at its local T2 constantly, and comprises the second synchronous pulse data bag of T1, T2, T3 constantly at its local T3 constantly to described regional master clock node or ordinary node answer;
Described regional master clock node or ordinary node receive the described second synchronous pulse data bag at its local T4 constantly;
Described regional master clock node or ordinary node according to described moment T1, T2, T3, T4 calculates with described selecteed formation in the time clock correction Δ t of node, according to formula
t′＝t+Δt，
The clock synchronization of realization and described selecteed isochronous queue node,
Wherein, the clock value after described regional master clock node of t ' expression or the ordinary node request synchronously, t are represented the clock value that described regional master clock node or ordinary node request are preceding synchronously.
9, the synchronous method of network clocking according to claim 1 is characterized in that, described standby clock source node synchronous accumulative total synchronism deviation computing time is specially:
Described standby clock source node according to the difference of the standard time clock that clock synchronization obtained of described work clock source node and the local master clock that himself in described isochronous queue, obtains, obtain the accumulative total synchronism deviation of clock synchronization.
10, the synchronous method of network clocking according to claim 1 is characterized in that, described standby clock source node obtains the average clock synchronism deviation of formation and is specially according to the number of node in described accumulative total synchronism deviation and the isochronous queue:
Wherein, u represents the average synchronism deviation of formation, and Δ U represents the accumulative total synchronism deviation, and N represents the number of Area Node in the described formation.
11, the synchronous method of network clocking according to claim 10 is characterized in that, described standby clock source node sends the average clock synchronism deviation of described formation to described regional master clock node, realizes that the clock correction is specially:
t1′＝t1-u*n
Wherein, the clock value after the described regional master clock node correction of t1 ' expression, t1 represents the clock value before the described regional master clock node correction, and u represents the average synchronism deviation of formation, and n represents the equipment of itself queue number of described regional master clock node.
12, the synchronous system of a kind of network clocking is characterized in that, described system comprises:
Lock unit is used to realize the clock synchronization between the redundancy clock source node;
The operating state setup unit is used for described redundancy clock source node is set at work clock source node and standby clock source node respectively;
Redundant switch unit is used for when described work clock source node is in abnormal operating state described standby clock source node being set at the work clock source node;
Zone master clock selected cell is used for selecting regional master clock node at the network ordinary node;
Formation forms the unit, and being used to form with described work clock source node is head of the queue, and the standby clock source node is a tail of the queue, and with the described regional master clock node isochronous queue that is the member;
The clock synchronization request unit is used for the node request clock synchronization of network node to isochronous queue;
The clock jitter computing unit is used for the accumulative total synchronism deviation that the standby clock source node calculates clock synchronization, and according to the described number that adds up node in synchronism deviation and the formation, calculates the average clock synchronism deviation of formation;
Clock correction unit is used for according to the average clock synchronism deviation of described formation, realizes clock compensation at described regional master clock node;
Wherein, regional master clock selected cell comprises:
Message receives subelement, is used to receive the formation generation message that the redundancy clock source node generates;
Zone master clock node is judged subelement, is used for random number and predefined regional master clock threshold value that network node produces are compared, and greater than described threshold value, then selecting described node is regional master clock node as if described random number;
The clock synchronization request unit comprises:
The first local master clock chooser unit is used for described regional master clock node and selects the clock of its last node of formation as local master clock;
The communication quality judgment sub-unit is used for judging the communication quality of described ordinary node and isochronous queue node;
The second local master clock chooser unit, that be used for selecting obtaining and the local master clock of the clock best isochronous queue node of described ordinary node communication quality as described ordinary node according to described communication quality judgment sub-unit.
13, the synchronous system of network clocking according to claim 12 is characterized in that, described redundant switch unit comprises:
The operating state judgment sub-unit is used to judge whether the operating state of described work clock source node is normal.
14, the synchronous system of network clocking according to claim 12 is characterized in that, described lock unit comprises:
The GPS subelement is used to realize that the GPS between described redundancy clock source node communicates by letter;
The radio communication subelement is used to realize the radio communication between described redundancy clock source node;
Network connexon unit is used to realize that the network between described redundancy clock source node connects communication.
15, the synchronous system of network clocking according to claim 12 is characterized in that, described operating state setup unit comprises:
The state exchange subelement is used for according to preset state, and described redundancy clock source node is converted to operating state or stand-by state by init state;
First message is created subelement, is used for creating formation generation message according to the equipment of itself queue number and the preset state of described redundancy clock source node;
First message sends subelement, is used for described formation is generated the node that message is sent to network.
16, the synchronous system of network clocking according to claim 15 is characterized in that, described regional master clock selected cell also comprises:
Subelement is set, is used for generating a last node device queue number of message and device queue that preset state is set described regional master clock node number and state according to the described formation that receives;
Second message is created subelement, is used for creating formation according to the device queue of described regional master clock node number and state and generates message;
Second message sends subelement, is used to send the formation generation message of described regional master clock node.
17, the synchronous system of network clocking according to claim 12 is characterized in that, described clock synchronization request unit also comprises:
The pulse data bag sends subelement, is used for network node and sends the first or second pulse data bag;
The pulse data bag receives subelement, is used for network node and receives the first or second pulse data bag;
The timing subelement is used to write down the local master clock node of moment T1, the first local master clock chooser unit or the second local master clock chooser unit that described regional master clock node or ordinary node send the described first pulse data bag selecting and receives the moment T2 of the first pulse data bag, described local master clock node and send the moment T4 that the moment T3 of the second pulse data bag and described regional master clock node or ordinary node receive the second pulse data bag;
The clock synchronization computation subunit is used for according to described moment T1, T2, T3 and T4, calculates the time difference Δ t of described regional master clock node or ordinary node and local master clock node, according to formula
t′＝t+Δt，
The clock synchronization of realization and described local master clock node,
Wherein, the clock value after described regional master clock node of t ' expression or the ordinary node request synchronously, t are represented the clock value that described regional master clock node or ordinary node request are preceding synchronously.
18, the synchronous system of network clocking according to claim 12 is characterized in that, described clock jitter computing unit comprises:
Accumulative total clock jitter computation subunit, be used for the difference of standby clock source node, obtain the accumulative total synchronism deviation Δ U of time synchronized according to the lock unit local master clock that obtains with the lock in time work clock source node with according to the time synchronized request unit that obtain;
The average clock synchronism deviation of formation computation subunit is used for the number according to described accumulative total synchronism deviation and formation node, calculates the average clock synchronism deviation of formation u,
Wherein, u represents the average synchronism deviation of formation, and Δ U represents the accumulative total synchronism deviation, and N represents the number of Area Node in the described isochronous queue.
19, the synchronous system of network clocking according to claim 18 is characterized in that, clock correction unit comprises:
The average synchronism deviation of formation sends subelement, is used for the average synchronism deviation of described formation is sent to the regional master clock node of described formation;
Clock correction calculations subelement is used for realizing the correction to described regional master clock node according to the described average clock synchronism deviation that receives,
t1′＝t1-u*n
Wherein, the clock value after the described regional master clock node correction of t1 ' expression, t1 represents the clock value before the described regional master clock node correction, and u represents the average synchronism deviation of formation, and n represents the equipment of itself queue number of described regional master clock node.
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| CN102487318A (en) * | 2010-12-06 | 2012-06-06 | 中国移动通信集团公司 | Method, equipment and system for transmitting time synchronization information on ground |
| CN102317885B (en) * | 2011-07-26 | 2014-05-07 | 华为技术有限公司 | Computer system and method of configuring clock thereof |
| CN103402250B (en) * | 2013-07-26 | 2014-11-26 | 深圳职业技术学院 | Clock synchronization method and device for large-scale wireless sensor network |
| CN103401630B (en) * | 2013-07-30 | 2016-08-10 | 西南大学 | Redundancy timing system in a kind of industrial control network and method |
| CN105024798A (en) * | 2014-04-28 | 2015-11-04 | 中兴通讯股份有限公司 | Method and device for time synchronization |
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