KR101952748B1 - Apparatus and method for timing synchronization of time division multiple access network node - Google Patents

Abstract

The present invention relates to an apparatus and method for performing time synchronization in a TDMA network node, including a communication unit for performing communication connection with a plurality of other nodes constituting a network, a real time clock (RTC) And a preset message for round trip time (RTT) measurement to a preset master node among the plurality of other nodes based on time information obtained from the RTC, And a controller for performing network time synchronization based on the correction value calculated based on the message.

Description

[0001] APPARATUS AND METHOD FOR TIMING SYNCHRONIZATION OF TIME DIVISION [0002] MULTIPLE ACCESS NETWORK NODE [

The present invention relates to an apparatus and method for performing time synchronization in a TDMA network node.

In the case of the Korean tactical data link system, the TDMA (Time Division Multiplex Access) protocol may be applied to the network access method. The TDMA network is advantageous in that multiple information senders and multiple information receivers can be time-divisionally transmitted and received through the same medium. On the other hand, it is important that the tactical data link system, which is mainly used for command control and surveillance and reconnaissance, share and collect a large number of collected information in real time among the nodes constituting the network, and the TDMA network is an appropriate access method.

However, the communication method of the TDMA network requires a precondition that the time reference is shared among all the nodes constituting the TDMA network and is promised. The communication method of the TDMA network divides a predetermined time into a plurality of time slots and each node is synchronized with each time slot so that communication can be performed. Therefore, when the transmission and reception time criteria do not coincide with each other in the TDMA communication scheme, communication between the nodes is difficult to be performed, and normal information transmission / reception between the nodes is impossible. Also, in a situation where the size of data shared in real time is variable, a TDMA (Dynamic Time Division Multiple Access) connection scheme in which the size of a time slot is dynamic is also required. In this case, acquisition of a time reference in the TDMA network, Time synchronization of the TDMA network is further identified as an important factor.

On the other hand, for time synchronization of such a TDAM network, two methods are usually used. The first method is to use an external navigation device, that is, a GPS device. [Figure 1] shows an example in which nodes of a TDMA network perform time synchronization using an external navigation device.

[Figure 1]

Referring to FIG. 1, each TDMA network subscriber communication terminal, i.e., TDMA network node, can receive time information from an external navigation apparatus. In this case, since each TDMA network node can acquire the same time information, there is no need to perform synchronization separately. In this case, it takes time for each node to receive a navigation signal from a GPS device such as a GPS satellite. When a navigation signal is received from the GPS device, synchronization is performed according to time information included in the received signal, Synchronization is performed. Hereinafter, a method of performing time synchronization using an external navigation device will be referred to as an external navigation device-based time synchronization method.

As described above, the time synchronization method based on the external navigation device does not need to perform synchronization separately, and since the time synchronization is usually performed after the time from the GPS device until the navigation signal is received, that is, the time required for GPS locking, Synchronization time is short. However, when the time synchronization is performed according to the signal received from the external navigation device, or when the navigation signal is not received due to jamming, or if the forgery or disturbance of the navigation signal occurs, time synchronization is performed Communication can not be made. That is, there is a problem that it is vulnerable to jamming, forgery, or disturbance of a navigation signal.

On the other hand, the second method is a method in which nodes of the TDMA network synchronize time based on the time of a preset master node. [Figure 2] shows an example in which the nodes of the TDMA network perform time synchronization based on the time of the master node.

[Figure 2]

Referring to FIG. 2, each TDMA network subscription communication terminal, i.e., TDMA network nodes, can receive a specific message (e.g., an initial entry message) transmitted from a preset master node every predetermined period. The specific message includes the time information of the master node, so that other nodes receiving the message can obtain the time information of the master node. The other nodes perform synchronization according to the time information of the master node, and the time synchronization of the respective nodes is performed. Hereinafter, a method of performing time synchronization using the time information of the master node as a reference time will be referred to as a master-based time synchronization method.

The master-based time synchronization method is advantageous in that it is resistant to jamming, deception, or forgery of the GPS signal because it does not need to acquire time information from an external navigation device. However, in the case of the master-based time synchronization method, time synchronization may be performed when the specific message transmitted from the master node is received. However, since the master node transmits the specific message according to the predetermined period due to the characteristics of the TDMA network communication method, the longer the transmission period of the specific message, the longer time it takes to perform the time synchronization in the TDMA network. For example, as shown in FIG. 2, if the transmission period of the specific message is 12 seconds, it may take 12 seconds or longer to obtain the time synchronization in the worst case.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and other problems, and it is an object of the present invention to provide a time synchronization method, Time synchronization of a TDMA network node in a time-synchronized manner.

According to an aspect of the present invention, there is provided a time synchronization apparatus for a TDMA network node, comprising: a communication unit for establishing communication connection with a plurality of other nodes constituting a network; a RTC (RTT) measurement message to a preset master node among the plurality of other nodes based on time information obtained from the RTC, And a controller for performing network time synchronization based on the calculated correction value based on the response message to the message.

In one embodiment, the navigation system further includes a navigation signal receiver for receiving the navigation signal from the external navigation device, wherein the controller synchronizes the RTC according to the time information included in the navigation signal.

In one embodiment, the navigation system further includes a detection unit for detecting jamming, forgery, or deception of the navigation signal, wherein, if it is determined that the navigation signal is jammed, falsified, or deceptively generated as a result of detection by the detection unit, Performs time synchronization based on time information obtained from the RTC, and performs time synchronization based on time information included in the navigation signal when it is determined that the navigation signal is not jammed, falsified, or deceived .

In one embodiment, the detection unit detects that the navigation signal is jammed when the navigation signal is not received within a predetermined reception period.

In one embodiment, the detection unit may be configured to detect at least one of a digital signature information included in the navigation signal, a value of a satellite orbit data or a specific parameter, a signal strength of the navigation signal, Or a doppler, based on at least one of the first signal and the second signal.

According to an aspect of the present invention, there is provided a time synchronization method for a TDMA network node, the method including: a first step of detecting whether there is an abnormality in reception of a navigation signal transmitted from an external navigation apparatus; A second step of acquiring time information from an RTC (Real Time Clock) when it is determined that there is an error in reception of a signal; and a second step of acquiring time information (RTT) to a predetermined master node based on time information obtained from the RTC, A third step of transmitting a predetermined message for round trip time measurement, a fourth step of receiving a response message to the transmitted message, and a fourth step of, based on the correction value calculated based on the received response message, And a fifth step of performing network time synchronization.

In one embodiment, the first step further includes a sixth step of performing network time synchronization based on time information of a navigation signal received from the external navigation apparatus when there is no abnormality in reception of the navigation signal .

In one embodiment, the first step further includes a seventh step of synchronizing the RTC according to the time information of the navigation signal received from the external navigation apparatus when there is no abnormality in the reception of the navigation signal .

In one embodiment, the first step is a step of determining that there is an abnormality in the reception of the navigation signal when the navigation signal is not received during the predetermined reception period of the navigation signal.

In one embodiment, the first step may include a step of determining whether the digital signature information included in the navigation signal, the value of the satellite orbit data or a specific parameter, the signal strength of the navigation signal, And a step of detecting whether the navigation signal received from the external navigation apparatus is falsified or deceptive based on at least one of a carrier wave or a doppler and determining that there is an abnormality in reception of the navigation signal according to the detection result .

Effects of the time synchronization apparatus and method of a TDMA network node according to the present invention will be described as follows.

According to at least one of the embodiments of the present invention, coarse synchronization between nodes can be performed based on time information obtained from a RTC (Real Time Clock). As a result, since the time synchronization can be performed without the time information transmitted from the master node, the time required for time synchronization can be reduced.

According to at least one of the embodiments of the present invention, the time synchronization is performed based on the time information obtained from the RTC (Real Time Clock), so that the time synchronization can be performed without using the navigation signal received from the external navigation device It is possible to acquire time synchronization of the TDAM network even when GPS jamming, falsification or disturbance occurs.

1 is a block diagram illustrating a configuration of an apparatus for performing time synchronization in a TDMA network node according to an embodiment of the present invention.
2 is a conceptual diagram illustrating an example in which time synchronization is performed in a TDMA network according to an embodiment of the present invention.
3 is a conceptual diagram illustrating time synchronization in a TDMA network according to an embodiment of the present invention, with reference to time axis.
4 is a flowchart illustrating an operation of a time synchronization apparatus of a TDMA network node according to an embodiment of the present invention.

It is noted that the technical terms used herein are used only to describe specific embodiments and are not intended to limit the invention. Also, the singular forms "as used herein include plural referents unless the context clearly dictates otherwise. In this specification, "comprises" Or "include." Should not be construed to encompass the various components or steps described in the specification, and some of the components or portions may not be included, or may include additional components or steps And the like.

Further, in the description of the technology disclosed in this specification, a detailed description of related arts will be omitted if it is determined that the gist of the technology disclosed in this specification may be obscured.

Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating a configuration of an apparatus 100 for performing time synchronization in a TDMA network node according to an embodiment of the present invention.

1, a time synchronization apparatus 100 of a TDMA network node according to an embodiment of the present invention includes a control unit 110, a communication unit 130 connected to the control unit 110, a real time clock (RTC) (140), and a memory (150). The navigation signal receiving unit 120 and the detecting unit 160 may be further included. The components shown in FIG. 1 are not essential for implementing the TDMA network synchronizing apparatus 100 according to the embodiment of the present invention, so that the TDMA network synchronizing apparatus 100 described in this specification can be applied to the components listed above More, or fewer components.

First, the communication unit 130 can perform communication between other nodes constituting the TDMA network. The communication unit 130 may be connected to the other nodes in a TDMA connection manner based on time synchronization obtained under the control of the controller 110 and may exchange various information with the other nodes.

In response to a request from the control unit 110, the RTC 140 may input time information measured in real time from the synchronized time based on a predetermined reference to the control unit 110. [ Meanwhile, the RTC 140 may be initialized on the basis of a predetermined time, according to a request from the controller 110, and may be initialized based on a time point set as a reference.

The memory 150 stores data supporting various functions of the synchronization apparatus 100 of the TDMA network node. The memory 150 may store a plurality of application programs or applications that are driven by the synchronization device 100, data for operation of the synchronization device 100, and commands.

In addition to the operations related to the application program, the control unit 110 typically controls the overall operation of the synchronization apparatus 100. [ The controller 180 processes signals, data, information, and the like input or output through the above-described components, or drives an application program stored in the memory 150 to provide various information or functions for acquiring time synchronization in the TDAM network Can be processed.

In addition, the controller 110 may control at least some of the components illustrated in FIG. 1 in order to drive an application program stored in the memory 150. FIG. Further, the controller 110 may operate at least two or more of the components connected to the controller 110 in combination with each other for driving the application program.

On the other hand, when the predetermined condition is satisfied, the controller 110 can request the time information measured by the RTC 140. When the measured time information from the RTC 140 is provided, the reference time information can be generated based on the measured time information and the reference time point of the reference time at which the RTC 140 was most recently synchronized.

Then, the control unit 110 may perform coarse synchronization, which is a primary time synchronization process of the TDMA network, based on the reference time information. The master slot corresponding to the master node among the nodes constituting the TDMA network can be detected according to the performance of the coarse synchronization. Then, using the master slot, a message (e.g., a Round Trip Time (RTT) message) for fine synchronization, which is a second time synchronization process of the TDMA network, can be transmitted to the master node.

Then, the communication unit 130 can receive a response message (e.g., an RTT response message) transmitted in response to the message from the master node. When the response message is received, the controller 110 calculates a time error value with the master node based on the time from when the message is transmitted until when the response message is received and the time information included in the response message Can be calculated. The control unit 110 may perform time synchronization based on the calculated time error value. Here, the time information included in the response message may be information on a time until the master node receives the message for fine synchronization and transmits a response message thereto.

FIG. 2 is a conceptual diagram illustrating an example in which time synchronization is performed in a TDMA network according to an embodiment of the present invention.

Referring to FIG. 2, a message is transmitted between a node set as a master node and a node set as a slave node. Each slave node may transmit a message for the fine synchronization to the master node at a time corresponding to the master node timeslot allocated to each slave node. Each slave node may receive a response message transmitted from the master node at a time corresponding to the master node timeslot allocated to each slave node.

2, the navigation signal receiving unit 120 may receive a navigation signal transmitted from an external navigation device such as a GPS satellite. The control unit 110 may initialize the RTC 140 based on a navigation signal received through the navigation signal receiving unit 120. In this case, the time information of the navigation signal corresponding to the time point at which the RTC 140 is initialized may be stored in the memory 150.

For example, the RTC 140 continuously counts the elapsed time since the initialization time under the control of the controller 110, and transmits the counted time to the controller 110 at the request of the controller 110, As shown in FIG. Then, the controller 110 may calculate the current time based on the counted time value from the RTC 140 and the time information of the initialized time. Accordingly, even if the GPS signal is not received from the GPS satellite, the controller 110 can acquire the time information synchronized with the time of the GPS satellite based on the time information at the initialized time point and the time value provided from the RTC 140 Can be calculated.

On the other hand, the detection unit 160 can detect whether there is an abnormality in the navigation signal received by the navigation signal receiving unit 120. For example, when the navigation signal is not received during the reception period of the preset navigation signal, the detection unit 160 may detect that there is jamming of the navigation signal. Also, even if the navigation signal is received within a predetermined reception period, the detection unit 160 may detect an error included in the navigation signal by various predetermined methods to determine whether the navigation signal is falsified, It is possible to detect whether a disturbance has occurred or not.

For example, the detection unit 160 may compare the digital signature information included in the navigation signal with the stored digital signature information. Or, the orbit information of the GPS satellite included in the navigation signal or the value of the specific parameter may be compared with the previously stored satellite orbit information or the value of the specific parameter. Then, it is possible to detect the abnormality of the navigation signal based on the comparison result.

Alternatively, the detection unit 160 may compare the signal strength of the received navigation signal according to a predetermined criterion. For example, if the signal strength of the received navigation signal is greater than or equal to a preset fixed reference value, or if the predetermined reference level is greater than a relative reference value determined based on the strength of the previously received navigation signals, It can be determined that the navigation signal is deceptive or falsified. Alternatively, the detection unit 160 may detect whether the navigation signal is deceptive or counterfeit based on a pseudo distance estimated from the navigation signal or a carrier wave or Doppler component included in the navigation signal, . Then, the determination result can be input to the control unit 110.

The control unit 110 may determine whether to perform time synchronization of the TDMA network using the time information provided from the RTC 140 according to the determination result of the detection unit 160. [ For example, when there is no abnormality in the received navigation signal, the controller 110 may perform time synchronization using the received navigation signal. However, if there is an error in the received navigation signal even though the navigation signal is not received due to jamming or the navigation signal is received, time synchronization is performed using the time information provided from the RTC 140 without using the navigation signal .

FIG. 3 is a conceptual diagram illustrating time synchronization in a TDMA network according to an embodiment of the present invention, with reference to time axis.

Referring to FIG. 3, FIG. 3 shows an example in which a normal navigation signal is initially received and a navigation signal is not received due to jamming. When the normal navigation signal is initially received, the control unit 110 may acquire the reference time information based on the received navigation signal and perform time synchronization based on the acquired reference time information. In this case, the control unit 110 may synchronize the RTC 140 according to the time information included in the navigation signal, for example, store the time information and initialize the RTC 140.

However, as shown in FIG. 3, if jamming occurs, the controller 110 can detect that the navigation signal has not been received within the reception period of the predetermined navigation signal through the detection unit 160. Then, the control unit 110 generates reference time information based on the time information provided from the RTC 140, and performs time synchronization based on the generated reference time information. Accordingly, the present invention can perform the time synchronization of the TDMA network without using the navigation signal when the navigation signal is not received due to jamming or the navigation signal has an error due to disturbance or falsification.

4 is a flowchart illustrating an operation of the time synchronization apparatus 100 of the TDMA network node according to the present invention.

4, the controller 110 of the time synchronization apparatus 100 of the TDMA network node according to the embodiment of the present invention may obtain the time information from the RTC 140 and determine the time information as the reference time (S200) . If the information of the RTC 140 is time information counted from a specific time point, the controller 110 determines whether the time information provided from the RTC 140 and the time when the RTC 140 is most recently initialized Time information can be calculated. The time at which the RTC 140 was most recently initialized may be a time point corresponding to the time information of the most recently received navigation signal.

If the reference time is determined in step S200, the controller 110 may select a time slot corresponding to the master slot based on the reference time. Then, a synchronization message (e.g., RTT message) for time synchronization may be transmitted to the predetermined master node through the selected time slot (S202). In this case, since the first time synchronization, i.e., the coarse time synchronization, is performed according to the time acquired through the RTC 140 in step S200, a channel with the master node can be formed through the master slot. Accordingly, when a synchronization message is transmitted through the master slot, the synchronization message can be transmitted to the master node.

On the other hand, the master node can transmit a response message to the synchronization message when receiving the synchronization message. For example, the master node may transmit the response message through a time slot corresponding to a time slot in which the synchronization message is received. Here, the response message may include information on a time taken for the master node to receive the synchronization message and transmit the response message.

Meanwhile, the controller 110 may receive the response message through the channel formed with the master node. Then, the control unit 110 subtracts the time included in the response message from the time required for receiving the response message from the time when the synchronization message is transmitted, The time required for the response message to be transmitted through the network can be calculated. Then, a correction value for time synchronization may be calculated for the currently determined reference time based on the calculated times (S204). The correction value may be reflected in the reference time to perform time synchronization (S206).

Meanwhile, the controller 110 may perform the processes of FIG. 4 according to the detection result of the detector 160. FIG. That is, if the navigation signal is not received from the external navigation apparatus within a predetermined time determined according to a preset time, for example, a predetermined reception period as a result of the detection by the detection unit 160, Time synchronization of the TDMA network can be performed without a navigation signal.

Alternatively, the control unit 110 can detect whether there is an error in the received navigation signal, even if the navigation signal is received, by using a predetermined means, for example, a digital signature or a specific parameter value. If it is determined that there is an error, the time synchronization of the TDMA network can be performed based on the time information obtained from the RTC 140 instead of the time information included in the currently received navigation signal through the processes described in FIG.

On the other hand, when a navigation signal for which an error is not detected is normally received within a predetermined period of time set in accordance with a reception period, the control unit 110 may change the time information included in the received navigation signal to a reference time Needless to say, it can also be used. In this case, the controller 110 may synchronize the RTC 140 according to the time information included in the navigation signal.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Particularly, in the embodiment of the present invention, an example has been described in which it is determined that the navigation signal is jammed or deceptive or falsified when a navigation signal is not received within a predetermined time or an error is detected by a predetermined error detection means. However, it is needless to say that there may be other methods for detecting jamming, deception, or forgery of the navigation signal in addition to the above-described method.

Accordingly, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the essential characteristics of the invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: synchronization device 110:
120: navigation signal receiving unit 130: communication unit
140: RTC 150: Memory
160:

Claims (10)

A communication unit for performing a communication connection with a plurality of other nodes constituting a wireless TDMA network;
A navigation signal receiver for receiving a navigation signal from an external navigation device;
An RTC (Real Time Clock) for providing real-time measured time information; And
Calculating a reference time information based on time information obtained from the RTC, and setting a preset time for round trip time (RTT) measurement to a predetermined master node among the plurality of other nodes based on the calculated reference time information And performing a wireless TDMA network time synchronization based on the calculated correction value based on a response message to the transmitted message,
The RTC includes:
Counting the elapsed time from a point corresponding to the time information of the latest received navigation signal, providing the counted time to the control unit,
Wherein,
Wherein the reference time information is calculated based on the counted time and the time information of the most recently received navigation signal. delete The method according to claim 1,
Further comprising a detector for detecting jamming, forgery, or deception of the navigation signal,
Wherein,
As a result of detection by the detecting section,
When the navigation signal is judged to be jamming, falsification or deception, time synchronization is performed based on time information obtained from the RTC,
Wherein the time synchronization unit performs time synchronization based on time information included in the navigation signal when the navigation signal is judged to be jamming, falsification, or deception. 4. The apparatus according to claim 3,
And detects that the navigation signal is jammed when the navigation signal is not received within a predetermined reception period. 4. The apparatus according to claim 3,
The signal strength of the navigation signal and the pseudorange detected from at least one of the carrier signal and the doppler detected from the navigation signal based on the digital signature information included in the navigation signal, the value of the satellite orbit data or a specific parameter, And detects whether or not the navigation signal is falsified or deceived. A first step of detecting whether there is an abnormality in reception of a navigation signal transmitted from an external navigation apparatus;
A second step of obtaining time information from a real time clock (RTC) when it is determined that there is an error in reception of the detection result of the navigation signal;
Calculating a reference time information based on the time information obtained from the RTC, and transmitting a predetermined message for round trip time (RTT) measurement to a predetermined master node based on the calculated reference time information, step;
A fourth step of receiving a response message to the transmitted message; And
And a fifth step of performing network time synchronization based on the correction value calculated based on the received response message,
The second step comprises:
Further comprising a second step of counting a time elapsed since a time corresponding to the time information of the most recently received navigation signal,
The reference-
Wherein the calculated time is calculated based on the counted time and the time information of the most recently received navigation signal. 7. The method of claim 6,
And a sixth step of performing network time synchronization based on the time information of the navigation signal received from the external navigation apparatus when there is no abnormality in the reception of the navigation signal. Way. 8. The method according to claim 7,
Further comprising a seventh step of synchronizing the RTC according to time information of a navigation signal received from the external navigation apparatus when there is no abnormality in the reception of the navigation signal. 7. The method of claim 6,
Wherein when the navigation signal is not received during the reception period of the predetermined navigation signal, it is determined that there is an error in reception of the navigation signal. 7. The method of claim 6,
The signal strength of the navigation signal and the pseudorange detected from at least one of the carrier signal and the doppler detected from the navigation signal based on the digital signature information included in the navigation signal, the value of the satellite orbit data or a specific parameter, Detecting whether the navigation signal received from the external navigation apparatus is falsified or deceptive, and determining that there is an error in reception of the navigation signal according to the detection result.

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