KR20210100053A - Method for time compensation in low power wide-area terminal and terminal performing same - Google Patents

Abstract

The present invention provides a method for compensating time effectively so that the time of a terminal can become correct in a low power wide-area (LPWA) network system which cannot transmit or receive the data of the terminal in real time. The method for compensating the time information of an LPWA network terminal connected to an LPWA network server according to an embodiment of the present invention can comprise the steps of: transmitting a first time information request message to the LPWA network server at a first point of time; receiving a first reception confirmation message of the first time information request message sent by the LPWA network server, at a second point of time; transmitting a second time information request message to the LPWA network server at a third point of time; receiving a time information message having a reference time recorded therein, which has been generated in response to the first time information request message, together with a second reception confirmation message of the second time information request message sent by the LPWA network server, at a fourth point of time; and compensating the time information of the LPWA network terminal using the reference time, the first point of time, the second point of time and the fourth point of time.

Description

A method of time correction in a terminal connected to the LPWA network and a terminal performing the method {METHOD FOR TIME COMPENSATION IN LOW POWER WIDE-AREA TERMINAL AND TERMINAL PERFORMING SAME}

The present invention relates to a method for accurately correcting the time of a terminal connected to an LPWA network system, and to a terminal performing the method.

The Internet of Things (IoT) refers to intelligent technologies and services that connect various things through networks such as the Internet so that information between people and things and between things and things can communicate with each other. The Internet of Things (IoT) is a more advanced technology than the existing wired/wireless communication, and can be used in various fields such as unmanned meters, unmanned vending machines, intelligent transportation services, and real-time monitoring medical services. According to the research results and analysis on IoT devices, the number of IoT-connected devices is expected to increase to about 30 billion by 2025, and research on IoT utilization is currently being actively conducted.

Conventionally, Wi-Fi, Bluetooth, and the like have been used as communication methods for building such an IoT system. However, these methods have a disadvantage that communication is possible only in a relatively short distance, so it is not suitable for an IoT system that needs to cover a wide range. The communication method for the Internet of Things needs to be designed to cover a wide range as described above, but to consume less power for IoT devices that often require charging restrictions and continuous power supply. Accordingly, a demand for so-called low-power long-distance communication (Low Power Wide-Area, LPWA) has emerged. LPWA is a generic term for IoT network technology specialized for small data transmission, which allows low-speed transmission of 1 kbps or less and has wide area coverage and low power consumption.

LoRa (Long Range) network is one of these LPWA type networks. In general, high-speed real-time data transmission/reception is not required for IoT systems. Power consumption is reduced by adopting a downlink asymmetric transmission scheme. The LoRa network is an IoT-only network that can accommodate low-performance devices with small batteries for the implementation of the Small Things Internet, and can provide coverage of 293bps to 5.4kbps and -143dbm sensitivity. In addition, the LoRa network terminal may receive the received data transmitted from the base station only after a predetermined time has elapsed after transmitting the transmitted data to the base station due to the above-described data transmission/reception limitation.

Meanwhile, in the case of using the Internet of Things for unmanned metering or transportation services, time synchronization between IoT terminals is very important. To this end, time information needs to be transmitted from the reference time providing device that maintains an accurate time to the IoT terminal. However, since the LoRa network terminal having the above-described transmission characteristics cannot receive the time information in real time even if the time information is requested from the reference time providing device, it is difficult to derive the time correction technique of the terminal considering the characteristics of the LoRa network system. situation is necessary.

Korean Patent Application Laid-Open No. 10-2011-0059421 (published on 02.06.2011)

The problem to be solved by the present invention relates to a method for effectively correcting the time of a terminal to be an accurate time in an LPWA network system in which real-time data transmission and reception of a terminal is impossible, and a terminal to which the method is applied.

However, the problems to be solved of the present invention are not limited to those mentioned above, and other problems to be solved that are not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description. will be.

In the method for correcting time information of an LPWA network terminal connected to a Low Power Wide-Area (LPWA) network server according to an embodiment of the present invention, at a first time point, a first time information request message is sent to the LPWA network server. transmitting; receiving a first acknowledgment message for the first time information request message sent by the LPWA network server at a second time point; transmitting a second time information request message to the LPWA network server at a third time point after the second time point; At the fourth time point, time information at which a reference time is recorded, generated in response to the first time information request message, together with a second acknowledgment message for the second time information request message sent by the LPWA network server receiving a message; and correcting time information of the LPWA network terminal by using the reference time, the first time, the second time, and the fourth time, wherein the reference time recorded in the time information message is the It is determined based on a time point at which the LPWA network server transmits the first acknowledgment message, and data may not be transmitted/received from the first time point to the second time point.

The correcting may include setting the time of the fourth time point to a correction time determined based on the reference time, a difference between the fourth time point and the second time point, and a difference between the second time point and the first time point. It may include the step of setting

The first time information request message is transmitted from the LPWA network server to a reference time providing device having standard time information at a time when the LPWA network server sends an acknowledgment message for the first time information request message; The time information message is generated by the reference time providing device receiving the first time information request message and transmitted to the LPWA network server. In the time information message, the reference time providing device requests the first time information A time indicating a time point at which a message is received from the LPWA network server based on the standard time information may be recorded as the reference time.

A terminal connected to an LPWA network server through an LPWA network according to another embodiment of the present invention includes: a communication unit configured to transmit data to the LPWA network server and receive data from the LPWA network server; A first time information request message is transmitted to the LPWA network server through the communication unit at a first time point, and a first acknowledgment message for the first time information request message sent by the LPWA network server is transmitted at a second time point. Received through a communication unit, and transmits the second time information request message to the LPWA network server through the communication unit at a third time point after the second time point, and the second time information request message sent by the LPWA network server a control unit configured to receive a time information message in response to the first time information request message, in which a reference time is recorded, through the communication unit at a fourth time, together with a second acknowledgment message for ; and a correction unit for correcting the time information of the terminal by using the reference time, the first time, the second time, and the fourth time, wherein the reference time recorded in the time information message is the LPWA It is determined based on a time point at which the network server transmits the first acknowledgment message, and data may not be transmitted/received from the first time point to the second time point.

According to an embodiment of the present invention, the LPWA network terminal receives the reference time information from the LPWA network server, and uses the time interval between a plurality of messages exchange performed between the LPWA network terminal and the LPWA network server as a kind of offset. Correction time information may be calculated by correcting the reference time information. Accordingly, it is possible to simply and accurately correct the time of the LPWA network terminal by using only the characteristics of the LPWA network system itself without adding an additional device to the terminal.

1 is a diagram illustrating a configuration of a LoRa network system according to an embodiment of the present invention.
2 is a diagram illustrating data transmission in a LoRa network system according to an embodiment of the present invention.
3 is a diagram illustrating a configuration of a terminal performing a time correction method in a LoRa network terminal according to an embodiment of the present invention.
4 is a diagram illustrating a sequence of a time correction method performed through a LoRa network terminal according to an embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

In describing the embodiments of the present invention, if it is determined that a detailed description of a well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

1 is a diagram illustrating a configuration of a LoRa network system according to an embodiment of the present invention. The LoRa network system 10 of FIG. 1 is a network system to which the LoRa network method as described above is applied. The LoRa network terminal 100 , the LoRa network server 200 , the LoRa network base station 300 and the LoRa application server 410 . may include. However, since the components of the LoRa network system 10 of FIG. 1 and the connection relationship between the components are only an embodiment of the present invention, the technical idea of the present invention is not limitedly interpreted by FIG. 1 .

Hereinafter, the LoRa network system 10 and each component will be briefly described with reference to FIG. 1 . The LoRa network terminal 100 may be various IoT devices such as an automatic meter and a traffic information collection device. The LoRa network server 200 may manage the LoRa network system 10 , and specifically, registration, authentication, and ID assignment for the LoRa network terminal 100 , and interworking between the LoRa network terminal 100 and the application server 410 . , it is possible to perform various management functions such as selection of a base station for the LoRa network terminal 100 and policy setting for a LoRa network operator. The LoRa network terminal 100 and the LoRa network server 200 may exchange data with each other through the LoRa network base station 300 .

Meanwhile, the LoRa network server 200 may be additionally connected to the reference time providing apparatus 400 that provides reference time information based on the standard time of the region to which the LoRa network system 10 belongs to the LoRa network server 200 . The reference time providing device is, for example, a device having accurate time information according to Universal Time Coordinated (UTC), and the LoRa application server 410 or the LoRa network system 10 included in the LoRa network system 10 . ) may be an external time information providing server 420 that provides reference time information from the outside.

The LoRa application server 410 may be included in the LoRa network system 10 as described above, and receives data from the LoRa network server 200 , encryption/decryption of data packets, and a specific application for the LoRa network terminal 100 . It is possible to perform functions such as provision of a service and management/control related to the corresponding application service. This LoRa application server 410 may be managed by the service manager 500, and may maintain an accurate time through NTP (Network Time Protocol). In contrast, the external time information server 420 may exist outside the LoRa network system 10, and may be any device capable of maintaining an accurate time through a Global Positioning System (GPS) device or the like.

2 is a diagram illustrating data transmission in a LoRa network system according to an embodiment of the present invention. The asymmetric transmission method as described above is applied to the LoRa network terminal 100 under the LoRa network system 10, so that data reception can be performed only after a predetermined time has elapsed after data transmission. Therefore, even if data is transmitted to the LoRa network server 200 through the LoRa network base station 300 , a response cannot be immediately received.

More specifically, it is assumed that the LoRa network terminal 100 transmits the transmission data packet 101 to the LoRa network base station 300 , but such transmission ends at a first time point t ₁ . Then, the LoRa network terminal 100 enters a sleep mode for a first predetermined waiting time (T _{1 ) from the first time point (t 1} ), which is the time when the transmission is terminated. During the sleep mode, the LoRa network terminal 100 cannot transmit/receive data.

When the second instance of time (t _2), the sleep mode is terminated, LoRa network terminal 100 is picked the turn of the data reception mode capable of receiving data over a network LoRa base station 300. More precisely, the LoRa network terminal 100 transmits data from the LoRa network base station 300 to the LoRa network terminal 100 for a predetermined first reception time (eg, 20 ms) from _{the second time point t 2 (} 102) can detect that, and, if the data 102 if it received, and the first reception time from the second point in time (t ₂₎ has passed the absence and ends the data reception mode. Meanwhile, although not shown in FIG. 2 , after the second predetermined waiting time T _{2 has elapsed from the first time point t 1} , the LoRa network terminal 100 again enters the data reception mode, and the LoRa network It may be detected whether there is data transmitted from the base station 300 to the LoRa network terminal 100 . As in the case of the first reception time, the LoRa network terminal 100 receives the data transmitted from the LoRa network base station 300 if there is, and if there is no second reception time (eg, 20 ms), the data reception mode is terminated. do. The first and second waiting times (T ₁ , T ₂ ) can be set arbitrarily, but in the general LoRa network system 10 , the first and second waiting times ( T ₁ , T ₂ ) are set to 1 second and 2 seconds, respectively. can According to this, even if the LoRa network terminal 100 transmits a message requesting to transmit specific data to the LoRa network server 200 to the LoRa network server 200 via the LoRa network base station 300, at most 1 second later , in some cases, it will be possible to receive a response to the request after 2 seconds.

In the above LoRa network environment described with reference to FIG. 2 , for example, the LoRa network terminal 100 transmits data 101 including a request message for requesting specific information to the LoRa network server 200 _{at a first time point t 1 .} ) can be transmitted. Then, the LoRa network server 200 may transmit the data 102 including the acknowledgment message indicating that the request has been received to the LoRa network terminal 100 _{at the second time point t 2 .} If it takes time to process the request, the LoRa network server 200 may not be able to transmit the specific information requested by the LoRa network terminal 100 at the second time point t _{2 .} In this case, the LoRa network terminal 100 transmits the data 103 including the request message to the LoRa network server 200 again at a third time point t _{3 , which is an arbitrary time point after the second time point t 2 .} The LoRa network server 200 that has processed the request may transmit the data 104 including the specific information requested by the LoRa network terminal 100 to the LoRa network terminal 100 _{at the fourth time point t 4 .} there is. At this time, the time interval between the first time point (t ₁ ) and the second time point (t ₂ ) and the time interval between the third time point (t ₃ ) and the fourth time point (t ₄ ) are the first waiting time (T _{1 )} ) or the second waiting time T ₂ .

3 is a diagram illustrating a configuration of a terminal performing a time correction method in a LoRa network terminal according to an embodiment of the present invention. The LoRa network terminal 100 of FIG. 3 may include a communication unit 110 , a control unit 120 , and a correction unit 130 . However, since the components of the LoRa network terminal 100 of FIG. 3 and the functions of each component are only one embodiment of the present invention, the technical idea of the present invention is not limitedly interpreted by FIG. 3 . Hereinafter, the operation of each component included in the LoRa network terminal 100 will be briefly described with reference to FIG. 3 , and more detailed information will be described with reference to FIG. 4 .

The communication unit 110 may transmit data to the LoRa network server 200 and receive data from the LoRa network server 200 based on the control of the control unit 120 . As described above, such data transmission and reception may be performed via the LoRa network base station 300 . The communication unit 110 may be implemented through a wired or wireless communication module.

The control unit 120 may control the communication unit 110 to transmit and receive data. When viewed from the perspective of an embodiment of the present invention, data transmitted from the LoRa network terminal 100 to the LoRa network server 200 through the action of the control unit 120 includes reference time information for knowing accurate time information. There may be a time information request message requesting provision. Contrary to this, data received from the LoRa network server 200 to the LoRa network terminal 100 includes an acknowledgment (Acknowledge or Ack) for the time information request message, a time information message including reference time information, and the like. can

The correction unit 130 accurately determines the time information of the LoRa network terminal 100 based on the time when the control unit 120 transmits or receives data through the communication unit 130 and the reference time information recorded in the time information message. can be corrected. The correction unit 130 may be implemented by an arithmetic device including a microprocessor together with the control unit 120 described above.

In addition, the LoRa network terminal 100 may further include a storage unit (not shown) capable of storing data for the components. The storage unit may be specifically implemented as a computer-readable recording medium, and examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, and optical recording media such as CD-ROMs and DVDs ( hardware devices specially configured to store and execute program instructions, such as optical media, magneto-optical media such as a floptical disk, and flash memory.

4 is a diagram illustrating a sequence of a time correction method performed through a LoRa network terminal according to an embodiment of the present invention. Each step of the interworking method according to an embodiment of the present invention will be described with reference to FIG. 4 . For reference, hereinafter, the term "time point" refers to a point on the absolute time axis, and the term "time" is numerical data (eg, 15:47 minutes) for expressing a time point, which is expressed in units of hours, minutes, seconds, etc. 38 seconds).

First, the LoRa network terminal 100 may transmit a first time information request message for requesting accurate reference time information through the LoRa network base station 300 _{at a first time point t 1 ( S101 ).} Then, the LoRa network base station 300 may transmit the first time information request message to the LoRa network server 200 (S102). Upon receiving the first time information request message, the LoRa network server 200 sends an acknowledgment message for the first time information request message for notifying the LoRa network terminal 100 that the first time information request message has been received to the LoRa network. It can be transmitted through the base station 300 (S103). Then, the LoRa network terminal 100 may receive the acknowledgment message through the LoRa network base station 300 at a second time point t ₂ (S104). As described above, the _{interval between the first time point t 1} and the second time point t _{2 may be the length T 1} of the sleep mode described in FIG. 2 in a general situation, for example, it may be set to 1 second. there is.

Meanwhile, when receiving the first time information request message, the LoRa network server 200 may transmit the first time information request message to the reference time providing apparatus 400 ( S105 ). Then, the reference time providing device 400 transmits the time information message in which the first time information request message is received, that is, the reference time (T _ref ) based on the standard time information, is recorded to the LoRa network server 200 at the correct time. It can be (S106). However, due to the above-described limitation in data transmission/reception of the LoRa network system 10, the LoRa network server 200 cannot send the time information message together with the acknowledgment message for the first time information request message, and accordingly The LoRa network terminal 100 also cannot receive the time information message at the second time point. Accordingly, in order to receive the time information message, the time correction method according to an embodiment of the present invention may further go through the following steps.

At a third time point t ₃ after the second time point t ₂ , the LoRa network terminal 100 may transmit a second time information request message for receiving the time information message through the LoRa network base station 300 . There is (S107). Then, the LoRa network base station 300 may transmit the second time information request message to the LoRa network server 200 (S108). At this time, the LoRa network server 200 receiving the second time information request message receives a acknowledgment message for the second time information request message for notifying the LoRa network terminal 100 that the second time information request message has been received. can be transmitted through the LoRa network base station 300, and at the same time, the time information message can be transmitted together (S109). Then, the LoRa network terminal 100 may receive the acknowledgment message and the time information message through the LoRa network base station 300 at a fourth time point t ₄ (S110). As described above, the interval between the third time point (t ₃ ) and the fourth time point (t ₄ ) is also the same as the interval between the first time point (t ₁ ) and the second time point (t ₂ ) in a general situation in FIG. 2 . The length of the sleep mode may be the first waiting time (T ₁ ) or the second waiting time (T ₂ ), and this interval may be, for example, 1 second or 2 seconds, as described above.

Finally, the LoRa network terminal 100 is the reference time (T _ref ) recorded in the time information message, the interval between the second time point (t ₂ ) and the fourth time point (t ₄ ) and the first time point (t ₁ ) and Time information of the LoRa network terminal 100 may be corrected based on the interval between the second time points t _{2 ( S111 ).}

As described above, the LoRa network terminal 100 needs to send the time information request message twice. However, here, the LoRa network terminal 100 receives the time information message at the fourth time point ( t ₄ ) and the reference time providing device 400 for generating the time information message is between the time point when the first time information request message is delivered. Since there is a time difference between , the reference time T _ref recorded in the time information message cannot be directly set to the time of the fourth time t _{4 .} Accordingly, the LoRa network terminal 100 may set the time of the fourth time point t _{4 as the correction time T corr} of the LoRa network terminal 100 through Equation 1 below.

[Equation 1]

T _corr = T _ref + (t ₄ -t ₂ ) + (t ₂ -t ₁ )/2

The principle of Equation 1 will be described as follows. 4, the reference time (T _ref ) is a time point between the first time point (t ₁ ) and the second time point (t ₂ ) (the first time information request message is sent to the reference time providing device 400 ) As the transmitted time point, it may be a time based on the standard time of a " _{fifth time point (t 5 )").} However, since the time _{corrected as the reference time (T ref} ) is not the fifth time (t ₅ ) but the fourth time (t ₄ ), the time interval between the fourth time (t ₄ ) and the fifth time (t _{5 ) (} t ₄ -t ₅ ) needs to be added to the reference time T _ref to be set as the correction time T _{corr .}

Wherein Referring to Figure _4, t 4 -t ₅ is the value of the fourth time (t ₄₎ and the second point in time (t ₂₎ the time interval between (t ₄ -t ₂₎ and a second point in time (t ₂₎ and It can be seen that it can be obtained by adding the time interval t ₂ -t ₅ between the fifth time points t _{5 .} Here, in transmitting the first time information request message and the second time information request message, when both the acknowledgment messages are received after the first waiting time (T ₁ ), the third time point (t ₃ ) and the first time point ( the time interval (t ₃ -t ₁₎ between t ₁₎ is also equal to the value of t ₄ -t _2. Also, since the fifth time point t ₅ may exist between the first time point t ₁ and the second time point t ₂ as described above, _{the value of t 2} -t ₅ is, on average, the first time point. _{It may be (t 2} -t ₁ )/2, which is half the time interval between (t ₁ ) and the second time point (t _{2 ).} According to this principle, Equation 1 can be derived.

The practical application of the time correction method according to Equation 1 as described above will be exemplarily described as follows. For example, the time of the fourth time point (t ₄ ) was 15:47:38 according to the time information of the LoRa network terminal 100 before the correction, but the correction time (T _corr ) calculated by Equation 1 is 15 o'clock If it was 52 minutes 58 seconds, the LoRa network terminal 100 may newly set the time _{of the fourth time point t 4 to 15:52:58 seconds.} That is, this is a story that the time information before correction is about 5 minutes and 20 seconds earlier than the accurate time information based on standard time, and the clock of the LoRa network terminal 100 is delayed by 5 minutes and 20 seconds by the time correction.

According to an embodiment of the present invention as described above, it is possible to simply and accurately correct the time of the LoRa network terminal by using only the characteristics of the LoRa network itself without adding an additional device to the terminal.

Combinations of each block in the block diagram attached to the present invention and each step in the flowchart may be performed by computer program instructions. These computer program instructions may be embodied in an encoding processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions executed by the encoding processor of the computer or other programmable data processing equipment may correspond to each block of the block diagram or Each step of the flowchart creates a means for performing the functions described. These computer program instructions may also be stored in a computer-usable or computer-readable memory that may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable memory. The instructions stored in the block diagram may also produce an item of manufacture containing instruction means for performing the functions described in each block in the block diagram or in each step in the flowchart. The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It is also possible that instructions for performing the processing equipment provide steps for carrying out the functions described in each block of the block diagram and each step of the flowchart.

Further, each block or each step may represent a module, segment, or portion of code that includes one or more executable instructions for executing the specified logical function(s). It should also be noted that in some alternative embodiments it is also possible for the functions recited in blocks or steps to occur out of order. For example, it is possible that two blocks or steps shown one after another may in fact be performed substantially simultaneously, or that the blocks or steps may sometimes be performed in the reverse order according to the corresponding function.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and variations will be possible without departing from the essential quality of the present invention by those skilled in the art to which the present invention pertains. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

According to an embodiment of the present invention, it is possible to simply and accurately correct the time of the LPWA network terminal by using only the characteristics of the LPWA network system itself without adding an additional device to the terminal.

10: LoRa network system
100: LoRa network terminal
200: LoRa network server
300: LoRa network base station
400: reference time providing device
410: application server
420: external time information providing server
500: service manager

Claims (8)

A method for correcting time information of an LPWA network terminal connected to an LPWA (Low Power Wide-Area) network server, the method comprising:
at a first time point, sending a first time information request message to the LPWA network server;
receiving a first acknowledgment message for the first time information request message sent by the LPWA network server at a second time point;
transmitting a second time information request message to the LPWA network server at a third time point after the second time point;
At the fourth time point, time information at which a reference time is recorded, generated in response to the first time information request message, together with a second acknowledgment message for the second time information request message sent by the LPWA network server receiving a message; and
Comprising the step of correcting the time information of the LPWA network terminal by using the reference time, the first time, the second time, and the fourth time,
The reference time recorded in the time information message is,
It is determined based on the time when the LPWA network server transmits the first acknowledgment message,
After the first time point until the second time point, data is not transmitted and received
How to correct time. The method of claim 1,
The correcting may include setting the time of the fourth time point to a correction time determined based on the reference time, a difference between the fourth time point and the second time point, and a difference between the second time point and the first time point. comprising the steps of setting
How to correct time. The method of claim 1,
The first time information request message is transmitted from the LPWA network server to a reference time providing device having standard time information at a time when the LPWA network server sends an acknowledgment message for the first time information request message,
The time information message is generated by the reference time providing device receiving the first time information request message and transmitted to the LPWA network server,
In the time information message, a time indicating a point in time when the reference time providing device receives the first time information request message from the LPWA network server based on the standard time information is recorded as the reference time
How to correct time. A terminal connected to an LPWA network server through an LPWA network,
a communication unit for performing data transmission to the LPWA network server and data reception from the LPWA network server;
A first time information request message is transmitted to the LPWA network server through the communication unit at a first time point, and a first acknowledgment message for the first time information request message sent by the LPWA network server is transmitted at a second time point. Received through a communication unit, and transmits the second time information request message to the LPWA network server through the communication unit at a third time point after the second time point, and the second time information request message sent by the LPWA network server a control unit configured to receive a time information message in response to the first time information request message, in which a reference time is recorded, through the communication unit at a fourth time, together with a second acknowledgment message for ; and
and a correction unit for correcting the time information of the terminal by using the reference time, the first time, the second time, and the fourth time,
The reference time recorded in the time information message is,
It is determined based on the time when the LPWA network server transmits the first acknowledgment message,
After the first time point until the second time point, data is not transmitted and received
LPWA network terminal. 5. The method of claim 4,
The correction unit,
setting the time of the fourth time as a corrected time determined based on the reference time, the difference between the fourth time and the second time, and the difference between the second time and the first time
LPWA network terminal. 5. The method of claim 4,
The first time information request message is transmitted from the LPWA network server to a reference time providing device having standard time information at a time when the LPWA network server sends an acknowledgment message for the first time information request message,
The time information message is generated by the reference time providing device receiving the first time information request message and transmitted to the LPWA network server,
In the time information message, a time indicating a point in time when the reference time providing device receives the first time information request message from the LPWA network server based on the standard time information is recorded as the reference time
LPWA network terminal. As a computer program stored in a computer-readable recording medium,
The computer program is
A method comprising instructions for causing a processor to perform the method according to any one of claims 1 to 3
computer program. As a computer-readable recording medium storing a computer program,
The computer program is
A method comprising instructions for causing a processor to perform the method according to any one of claims 1 to 3
computer readable recording medium.

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