KR20150135881A - Time Synchronization Method and System Using MULTI-HOP in Wireless Networks - Google Patents

Abstract

The present invention relates to a wireless communications technology and, more specifically, to a method for maintaining smooth wireless communications. When communications between a master station and a slave station is not smooth due to an environment restriction or the like, under a multiple wireless communications environment, the other slave station plays a role of the master station and the slave station at the same time.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a time synchronization method and system using a multi-hop method in a wireless communication environment,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication technology, and more particularly, to a wireless communication technology in which, when communication between a master station and a slave station is not smooth due to restriction of environment etc. in a multi- And a method for maintaining smooth wireless communication while simultaneously acting as a master station and a slave station.

Particularly, in the present invention, when the communication between the master station and the slave station is disconnected, the disconnected slave station and the slave station closest to the slave station serve as a master station, And a method of receiving information of a disconnected slave station and transmitting the information to a master station.

The time synchronization technique of the radio wave is a synchronization method based on a long wave or a long distance propagation, a time synchronization method using a terrestrial wave such as a dedicated short wave broadcast, a bidirectional time synchronization method using a communication satellite, a GPS (Global Positioning System) , GLONASS (Global Navigation Satellite System), and so on.

The time synchronization method using such a navigation satellite signal is generally used for mobile communication network synchronization, power grid synchronization, etc. with its convenience and high accuracy. However, the time synchronization method using the GPS (Global Positioning System) signal has weak reception power of 130dBm at the pico watt level and the system of the signal is disclosed. Therefore, unintentional radio interference or intentional deception And / or is very vulnerable to interference.

In addition, due to various environment constraints, if one or more end stations can not communicate with the main station, the time synchronization with the main station will not be achieved and the disadvantage that precise position detection is impossible due to the non-synchronized time .

1. Korean Patent Publication No. 10-2011-0022874 2. Korean Patent Publication No. 10-2010-0007765 3. Korean Patent No. 10-094912

1. Baek, Gyu-gyu, "Time Synchronization of Wireless Sensor Networks by Tree-based Indirect Broadcasting," Journal of the Institute of Information Science and Technology, Vol. 39, No. 6, pp 490-498, December 2012.

The present invention has been proposed in order to solve the problem according to the above background art, and provides a method and system for synchronizing time using a multi-hop method in a wireless communication environment which is resistant to unintentional radio interference or intentional deception and / or interference It has its purpose.

In addition, the present invention ensures line-of-sight for both the main and subnetworks, and provides a multi-hop method in a wireless communication environment for synchronizing the time even when the last line of sight to synchronize with the main station is not secured The present invention provides a method and system for synchronizing time using a time synchronization function.

The present invention provides a time synchronization method using a multi-hop method in a wireless communication environment that is resistant to unintentional radio interference or intentional deception and / or interference in order to achieve the above-described problems.

The time synchronization method includes:

Broadcasting a reference PRN (Pseudo Random Noise) time synchronization signal;

Generating a unique PRN time synchronizing signal for each of a plurality of terminal stations using the broadcasting reference PRN synchronizing signal and transmitting the unique PRN time synchronizing signal to the main station;

Receiving, by the master station, the unique PRN time synchronization signal, measuring a return delay and transmitting the measured delay to the plurality of end stations via a separate data exchange channel; And

Calculating a time error using a measure of the return delay received from the main station and controlling the self time to reflect the calculated time error, wherein the end time of one of the plurality of end stations And if the base station does not receive the reference PRN time synchronizing signal of the main station, receives the PRN time synchronizing signal from the other one of the adjacent stations.

At this time, the plurality of end stations may have a multi-channel receiving function so as to receive both the reference PRN time synchronizing signal of the main station and the PRN time synchronizing signal of the other station.

In addition, the synchronization signal synchronized with the other terminal may be transmitted to the master station.

Further, the plurality of end stations may communicate with each other using a multi-hop scheme.

The plurality of endpoints may also be characterized by synchronizing the transmitted code phase to the received code phase.

The control may be performed such that the frequency of the local oscillator is controlled so that the code phase of the reference PRN time synchronizing signal measured at the end point is equal to 0.5 times the return delay measured at the main station.

In addition, the measurement value can be characterized by comparing the code phase and the carrier Doppler with a digitally controlled oscillator (DCO) and a carrier NCO (Numerically Controlled Oscillator) for generating its own PRN time synchronizing signal.

Also, the local oscillator may be a Rubidium oscillator.

On the other hand, another example of the present invention includes a master station broadcasting a reference PRN (Pseudo Random Noise) time synchronization signal; And a plurality of final stations each generating a unique PRN time synchronization signal using the broadcasted reference PRN time synchronization signal and transmitting the generated synchronization signal to the main station, the present invention provides a multi-hop time synchronization system in a wireless communication environment .

According to the present invention, a master station, four (or n) slave stations are required for precise position detection of unknown signals, and information Estimates and / or tracks the position of the vehicle.

If one or more end stations can not communicate with the main station due to various environment constraints, the end station will not synchronize with the main station, and accurate position detection will not be possible due to the non-synchronized time. At this time, the last station which can not communicate using the multi-hop method can synchronize its time with the main station by communicating with its own final station (capable of communicating with the main station) so that a precise position detector for the unknown signal becomes possible.

In the case of location detection using data of devices that have not been synchronized in time, location accuracy is not precise and the accuracy of location detection is also significantly reduced when data of unsynchronized devices are not used. In order to secure this, synchronization is performed for all devices that do not synchronize with the main station by using the multi-hop method, and the effect of correcting the location detection of the unknown signal occurs.

1 is a conceptual diagram of a multi-hop scheme.
FIG. 2A and FIG. 2B are flowcharts illustrating transmission and reception of a PRN (Pseudo Random Noise) time synchronization signal and processing of time data according to an embodiment of the present invention.
FIGS. 3A, 3B, and 3C are diagrams illustrating a time synchronization process in which a time line or a radio wave arrival distance between a main station and a final station is not secured and direct time synchronization is not possible according to another embodiment of the present invention, Fig.
FIG. 4 is a conceptual diagram of a time synchronization system 400 showing multi-hop time synchronization according to an embodiment of the present invention.
5 to 8 are timing diagrams showing the time synchronization process according to the conceptual diagram shown in FIG.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

Hereinafter, a multi-hop time synchronization method and system in a wireless communication environment according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a multi-hop scheme. Referring to FIG. 1, a master station 110 and a first and second slave stations 121 and 122 are provided for precise position detection of the unknown signal. In particular, a communication obstacle 120 is placed between the main station 110 and the second terminating 122 and the Master PRN signal can not be broadcast directly from the main station 110 to the second terminating end 122. [

The principle of multi-hop based visual / frequency synchronization under the condition that LOS (Line of Sight) is not guaranteed is as follows.

The second endpoint 122 proceeds with synchronization with the second endpoint at the first endpoint 121 synchronized to the primary station 110 if it can not directly receive the Master PRN (Pseudo Random Noise) signal from the primary station 110. [

(Time Offset, Locking Status) in the first end station 121 and the main station 110 to the second end station 122 in the return PRN (Pseudo Random Noise).

The second endpoint 122 receives the signal of the first endpoint 121 and measures the Time Offset measurement data with the second endpoint 122 and then retransmits the measurement data.

Therefore, the end stations 121 and 122 have a multi-channel receiver function to receive the Master PRN (Pseudo Random Noise) of the main station 110 as well as other slave PRNs (Pseudo Random Noise).

Of course, the time offset measurement data of the second endpoint 122 measured by the first endpoint 121 is transmitted to the second endpoint 122 using a separate data channel.

FIG. 2A and FIG. 2B are flowcharts illustrating transmission and reception of a PRN (Pseudo Random Noise) time synchronization signal and processing of time data according to an embodiment of the present invention. The basic method is to generate the PRN time synchronization signal of the last station based on the PRN time synchronization signal transmitted from the master station and return it to the master station. The master station receives the round trip delay (reply delay) And sends it back to the end with a separate data exchange channel. The terminal calculates the time error from the return delay measurement received from the main station and controls its own time by reflecting the error.

First, referring to FIG. 2A, initial stabilization of a rubidium oscillator is performed when the main power and / or the final power is turned on (steps S210 and S211). Since the error is large when the oscillator is large from the beginning, the oscillation falls within a predetermined range after a predetermined time, which is called initial stabilization.

After the initial stabilization, it is determined whether the current main station or the last station operates (step S213).

As a result of the determination, if it is an operation of the main station, a Master PRN (Pseudo Random Noise) is set and a slave PRN receiving channel to be traced is allocated (step S215).

In addition, the master PRN code and the carrier are generated based on the own time / frequency reference and transmitted to the final station through the assigned channel (step S217).

The slave PRN code phase received from the last station and the carrier Doppler are compared with a Digitally Controlled Oscillator (DCO) and a Carrier NCO (Numerically Controlled Oscillator) for PRN generation (Step S218).

Each measured value of the time error is reflected in the slave transmission time data (step S219). In this case, the master PRN code and carrier wave generation / transmission are performed on the basis of the time / frequency again using the reflected time data (step S217).

Otherwise, if the final operation is performed in step S213, the process according to FIG. 2B is performed. Referring to FIG. 2B, when the final operation is performed, the corresponding slave PRN is set and the master PRN receiving channel to be traced is allocated (step S223).

In addition, the master PRN code and the carrier signal are received from the master station through the allocated channel, and the carrier phase and the code phase are tracked using the master PRN code and the carrier phase (step S224).

Generates the corresponding slave PRN code and carrier wave in the same manner as the tracked master code phase and carrier Doppler, and transmits it to the main station in step S218 (step S225).

Thereafter, measurement information of the own time error is confirmed in the master transmission time data, and the synchronized signal is generated by correcting the measurement transmission delay and the Doppler (step S226). Furthermore, the frequency of the measurement TIC slew and the local oscillator are controlled so that the code phase of the main signal measured at the end is equal to 0.5 times (half of the RTD) measured at the main station do.

Also, the frequency of the local oscillator is controlled so that the carrier NCO value of the master tracking loop is equal to 0.5 times the Doppler measured by the master station.

Thereafter, its own time / frequency synchronization error and synchronization state are applied as its own PRN code data (step S227). After application, step S225 proceeds.

FIGS. 3A, 3B, and 3C are diagrams illustrating a time synchronization process in which a time line or a radio wave arrival distance between a main station and a final station is not secured and direct time synchronization is not possible according to another embodiment of the present invention, Fig.

First, referring to FIG. 3A, an initial stabilization of a rubidium oscillator is performed when the main power and / or the final power is turned on (steps S310 and S311).

After the initial stabilization, it is determined whether the current main station 110 or the last stations 121 and 122 are operating (step S313).

As a result of the determination, if the master station 110 is operating, the master PRN is set and a slave PRN receiving channel to be traced is allocated (step S315).

In addition, it generates a Master PRN code and a carrier wave based on its own time / frequency reference, and transmits it to the first terminal 121 through the allocated channel (step S317).

The slave PRN code phase received from the first terminal 121 and the carrier Doppler are compared with a Digitally Controlled Oscillator (DCO) or a Carrier NCO (Numerically Controlled Oscillator) for PRN generation (Step S318).

Each measured value of the time error is reflected in the slave transmission time data (step S319). In this case, the master PRN code and carrier wave generation / transmission are performed on the basis of the time / frequency again using the reflected time data (step S217). Also, the peripheral last signal measurement value is reflected in the slave transmission time data.

Also, the reflected time data is transmitted to the first terminal 121, wherein the time data includes each measurement of the time error reported by each endpoint.

Otherwise, if the operations of the final stages 121 and 122 are completed in step S313, the process according to FIG. 3B and FIG. Referring to FIG. 3B, when the first end station 121 is operated, the corresponding slave PRN is set and a master PRN reception channel to be tracked is allocated (step S321).

In addition, a master signal (i.e., a Master PRN code and a carrier signal) is received from the master station 110 through the allocated channel, and the carrier phase and the code phase are tracked using the master signal (Step S322). In particular, it receives peripheral end signals to obtain measurements of carrier phase and code phase.

The master PRN code and the carrier signal to the second terminal (step S323).

The slave PRN code and the carrier wave are generated in the same manner as the code phase and the carrier Doppler of the tracked master station 110 (step S324).

The carrier phase and code phase measurements are obtained via the peripheral slave 'signal received from the second terminal 122 (step S325).

The slave PRN code and the carrier signal of the first terminal station 121 and the slave 'PRN code and the carrier signal of the second terminal station 122 to the main station 110 (step S326).

Thereafter, the measurement information of the own time error is confirmed in the master transmission time data, and the synchronized signal is generated by compensating the measurement transmission delay and the Doppler (step S327). Further, in step S327, the measured value information of the slave 'signal from the second terminal 122 is confirmed, reflected on the time data, and transmitted to the main station 110.

In particular, when the main signal is not received, the terminal acquires the last measurement value received from the time data and regards the end signal as the main signal and performs the synchronization procedure.

Then, its own time / frequency synchronization error and synchronization state are applied as its own PRN code data (step S329). When the PRN code data is applied, the flow advances to step S324.

Referring to FIG. 3C, when the second end station 122 is operated, the corresponding slave 'PRN is set and the master PRN reception channel to be traced is allocated (step S331).

In addition, a slave signal (i.e., a slave PRN code and a carrier signal) is received from the first terminal 121 through the allocated channel, and the carrier phase and the code phase are tracked using the slave signal (step S332).

Generates the corresponding slave 'PRN code and carrier wave in the same manner as the code phase and carrier Doppler of the tracked master station 110 (step S333).

Thereafter, the measurement information of the own time error is confirmed in the slave transmission time data, and the synchronized signal is generated by compensating the measurement transmission delay and the Doppler (step S335).

Then, its own time / frequency synchronization error and synchronization state are applied as its own PRN code data (step S337). When the PRN code data is applied, the process proceeds to step S333.

FIG. 4 is a conceptual diagram of a time synchronization system 400 showing multi-hop time synchronization according to an embodiment of the present invention. Referring to FIG. 4, the time synchronization system 400 includes a main station 410, and first to third stations 421 to 423.

Of course, in FIG. 4, the three first to third end stations 421, 422, and 423 are shown for the sake of convenience of understanding. However, the present invention is not limited thereto and may be composed of three or more end stations. Also in FIG. 4, a communication obstacle 430 is located between the main station 410 and the third terminating station 423, similar to FIG. Therefore, direct communication between the main station 410 and the third terminating station 423 is not achieved.

The master station 410 is a Master PRN-code transceiver that broadcasts a reference PRN time synchronizing signal of the master station to each of the stations 411 to 412, tracks the last PRN time synchronizing signal, Round-trip-delay (RTD), and Doppler.

In addition, time synchronization between the master station and the final station is performed, and a multi-channel function is performed.

The end stations 411 to 413 are slave PRN-code transceivers that track the reference PRN time synchronizing signal of the main station and generate the last PRN time synchronizing signal as a time / phase difference.

Also, the time / frequency synchronization error is extracted from the corresponding measurement signal received from the main station and synchronized. In addition, the terminal performs a multi-channel function.

When the base station PRN time synchronizing signal of the main station 410 is not received, the signal of the adjacent main station is tracked. Also, PRN time synchronization signal generation and synchronization are performed by using the last terminal signal and the time / phase difference.

Therefore, PRN (Pseudo Random Noise) code is used to transmit time, and measurement related information is exchanged through a separate data channel. In this way, precise time synchronization is implemented. It is implemented as a number of slave stations that synchronize with the time of the main station. In addition, if the line of sight is to be secured for the mainland and the end, and if there is no end of line to be synchronized with the mainland, if the mainland and the line of sight are secured and the line of sight is secured, To synchronize the time.

In this case, the last station that can not communicate using the multi-hop method can synchronize its time with the main station by communicating with its own final station (capable of communicating with the main station) to enable precise position detection on the unknown signal do.

Generally, when the position detection is performed using the data of the devices that are not synchronized with time, the accuracy of the position detection is not precise and the accuracy of the position detection is remarkably decreased even when the data of the unsynchronized equipment is not used.

In order to secure this, synchronization is performed for all devices that do not synchronize with the main station by using the multi-hop method, and the effect of correcting the position detection of the unknown signal occurs.

FIGS. 5 to 8 are timing diagrams illustrating respective time synchronization processes according to the conceptual diagram shown in FIG.

In particular, 2 * Td1, 2 * Td2, 2 * (Td1 + Td1 ') shown in FIG. 5 represents the return delay of each of the last stations 421, 422, 423 measured in the home station. Each final Doppler measurement is also measured by carrier tracking.

The concept of 2 * Td1 is shown in Fig. 6 is a timing diagram between main station 410 and first end 411.

The concept of 2 * Td2 is shown in Fig. Figure 7 is a timing diagram between main station 410 and second end 412.

2 * (Td1 + Td1 ') is shown in Fig. 8 is a timing diagram between main station 410 and third terminating station 413. In particular, FIG. 8 illustrates that the first end station 411 plays a role of relaying the signal of the second end station 413.

400: Time synchronization system
410: master station
411: First closing
412: The second end
413: Third closing date
430: communication obstacle

Claims (5)

Broadcasting a reference PRN (Pseudo Random Noise) time synchronization signal;
Generating a unique PRN time synchronizing signal for each of a plurality of terminal stations using the broadcasting reference PRN synchronizing signal and transmitting the unique PRN time synchronizing signal to the main station;
Receiving, by the master station, the unique PRN time synchronization signal, measuring a return delay and transmitting the measured delay to the plurality of end stations via a separate data exchange channel; And
Calculating a time error using the measurements of the return delay received from the main station and controlling the self time to reflect the calculated time error,
And the PRN time synchronizing signal from the other one of the adjacent stations is received and synchronized when the terminal end of one of the plurality of end stations fails to receive the reference PRN time synchronizing signal of the master station. Time Synchronization Method Using.
The method according to claim 1,
Wherein the plurality of end stations have a multi-channel reception function so as to receive both the reference PRN time synchronizing signal of the main station and the other PRN time synchronizing signal of the other station, wherein the one end station is synchronized with the other station And transmitting a signal to the main station in a wireless communication environment.
The method according to claim 1,
Wherein the plurality of end stations synchronize the transmitted code phase to the received code phase and wherein the control is performed such that the code phase of the reference PRN time synchronous signal measured at the end station is equal to 0.5 times the return delay measured at the home station Wherein the frequency of the time synchronization is controlled by using the multi-hop time synchronization method in a wireless communication environment.
The method of claim 3,
The measurement is performed by comparing a code phase and a carrier Doppler with a Digitally Controlled Oscillator (DCO) and a Carrier NCO (Numerically Controlled Oscillator) for generating a unique PRN time synchronizing signal, and the local oscillator is a Rubidium oscillator A time synchronization method using a multi-hop method in a wireless communication environment.
A base station broadcasting a reference PRN (Pseudo Random Noise) time synchronization signal; And
And generating a unique PRN time synchronization signal using the broadcasted reference PRN time synchronization signal and transmitting the unique PRN time synchronization signal to the main station,
Wherein the main station receives the unique PRN time synchronization signal and measures a return delay and transmits the measured delay time to the plurality of end stations using a separate data exchange channel and the plurality of end stations use a measurement value of a return delay received from the main station, And controls its own time by reflecting the calculated time error,
And the PRN time synchronizing signal from the other one of the adjacent stations is received and synchronized when the terminal end of one of the plurality of end stations fails to receive the reference PRN time synchronizing signal of the master station. Time Synchronization System Using.

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