KR102339244B1 - Satellite IoT terminal and effective and robust unidirectional data transmission methods therby - Google Patents

Abstract

The present invention is a unidirectional data transmission method of a satellite IoT terminal using redundant transmission and split transmission by identifying a plurality of uplink radio frequencies transmitted from a terminal to a satellite in transmitting data, and furthermore, transmitting one data to a plurality of frequencies A satellite IoT terminal that maximizes unidirectional data transmission performance by increasing the reception probability of the receiving side (satellite central station) by transmitting redundantly to the and a unidirectional data transmission method using the same.

Description

Satellite IoT terminal and unidirectional data transmission method using the same

The present invention relates to a satellite IoT terminal and a unidirectional data transmission method using the same, and more particularly, to a satellite using redundant transmission and split transmission by identifying a plurality of uplink radio frequencies transmitted from a terminal to a satellite in data transmission. It relates to an IoT terminal and a unidirectional data transmission method using the same.

Furthermore, the present invention increases the reception probability of the receiving side (satellite center station) by repeatedly transmitting one data at a plurality of frequencies, or by increasing the data recovery rate of the receiving side by dividing and transmitting data to which the channel coding technique is applied into a plurality of frequencies. , to a satellite IoT terminal maximizing unidirectional data transmission performance and a unidirectional data transmission method using the same.

A representative example of applying the unidirectional satellite communication technology of the satellite is satellite broadcasting.

The data transmitted from the central station allows all satellite terminals to receive data divided into a certain size through the forward link via the satellite. identify

Patent Documents 1 and 2 are examples of such communication technology.

Patent Document 1 discloses, in a digital broadcasting system for broadcasting region-specific additional information, a transmitter for allocating region-specific additional information broadcasting having a region identification code to at least one channel among a plurality of broadcasting channels and transmitting the region-specific additional information; Including a repeater that receives the broadcast, checks the area identification code, and when it is determined as the area identification code, a repeater that transmits the additional information broadcast for the area to the radio shadow area, and a receiver that receives the area-specific additional information broadcast from the repeater It is a system composed of

Patent Document 2 discloses an input step in which a command is input and converted into a signal suitable for satellite communication; an identification code generation step of generating an identification code for each region to be received in one or more signals converted in the input step; a satellite transmission step of transmitting one or more signals inputted in the input step and converted to a satellite side; A receiving step of receiving a signal coming down through the satellite in the satellite transmitting step; and an output step in which the signal received in the receiving step is converted so as to be able to transmit only the signal for the region where it is received by the identification code and output; It is a one-way satellite communication method comprising a,

Patent Document 3 discloses a hybrid positioning method performed in a positioning terminal operated by at least one processor, comprising the steps of setting a downlink channel as a broadcast channel, determining whether the current location is a shadow area of a broadcast channel, determining a shadow area When it does, changing the downlink channel from the broadcast channel to the communication channel, receiving the position correction information through the broadcasting channel or the communication channel, and converting the position correction information received from the Global Navigation Satellite System (GNSS) satellite to the position correction information It is a hybrid positioning method comprising the step of generating the final position information by correcting based on the.

As such, various communication technologies are being developed. In this prior art, as shown in FIG. 1, all terminals receive the same data as the broadcast from the central station to the terminal, and they need to extract the data they need.

Beacon-based communication technology is being used in LoRaWAN, a terrestrial IoT technology.

It calculates its own transmission slot from the beacon signal, receives data from the satellite at the slot time, and when data is found, transmits its own data during the subsequent transmission occupancy time.

A different frequency can be selected according to conditions during transmission, and a random selection technique is used.

In this prior art, when the terrestrial IoT terminal wants to use a beacon-based communication function after going through a subscription procedure, a switching procedure must be performed. In the beacon period, as shown in FIG. In this case, data can be transmitted through the uplink frequency. Two-way communication must be possible during the subscription procedure, conversion procedure, and data transmission/reception.

Channel coding is a technique for increasing communication performance, and it is possible to increase data recovery capability on the receiving side by using error correction capability. It is a forward error control method that improves performance in a limited channel environment by inserting structured redundant information into data to overcome errors such as noise and interference in the radio section.

This conventional technique, which is widely used in all communication fields, has disadvantages of increasing channel bandwidth, decreasing data rate, and increasing complexity, but is a technique commonly applied due to high recovery performance.

Republic of Korea Patent Publication No. 10-2005-0038143 Republic of Korea Patent Publication No. 10-2010-0134436 Republic of Korea Patent Publication No. 10-2019-0024638

The present invention was developed to solve the problems of the prior art, and an object of the present invention is to provide an efficient transmission method of a satellite IoT terminal that unidirectionally transmits data based on a beacon signal transmitted from a satellite to a terminal.

That is, an object of the present invention is to provide a satellite IoT terminal using redundant transmission and split transmission by identifying a plurality of uplink radio frequencies transmitted from a terminal to a satellite in data transmission, and a unidirectional data transmission method using the same.

Furthermore, the present invention increases the reception probability of the receiving side (satellite center station) by repeatedly transmitting one data at a plurality of frequencies, or by increasing the data recovery rate of the receiving side by dividing and transmitting data to which the channel coding technique is applied into a plurality of frequencies. An object of the present invention is to provide a satellite IoT terminal that maximizes unidirectional data transmission performance and a unidirectional data transmission method using the same.

A satellite IoT terminal according to the present invention for solving the above object is a unidirectional data transmission system for transmitting data in one direction, comprising: a sensor data unit for collecting data such as temperature and location to be transmitted through a satellite channel; a channel coding unit for transmitting information transmitted from a transmitting end through coding using a forward error correction code in order to correct an error experienced in a channel with the data obtained from the sensor data unit at a receiving end; a data division unit for dividing and transmitting channel-coded data for each frequency into several packets in order to reduce loss due to data collision on a wireless channel; a data copy unit which duplicates and transmits the same data in order to reduce loss due to data collision on a wireless channel; a beacon signal receiving unit for receiving a beacon signal transmitted from a satellite and receiving a beacon message of a beacon device included in the beacon signal; a transmission information extraction unit for extracting a specific transmission time and transmission occupancy period by using the beacon message information; a frequency management unit for managing a specific uplink transmission frequency using beacon message information at a specific transmission time and transmission occupation period derived from the transmission information extraction unit; and a transmission unit for receiving information from the transmission information extraction unit and the frequency management unit and transmitting data to be transmitted to the satellite.

The beacon signal receiving unit calculates the transmission time by a random method with reference to the beacon signal, and also selects an uplink radio frequency in a random manner.

The data transmission method using the satellite IoT terminal configured as described above randomly selects uplink radio frequencies to be transmitted from a plurality of uplink radio frequencies based on a beacon signal transmitted from a satellite, and uses a randomly calculated transmission time for each frequency. , a method of increasing the data reception rate of the receiving side by repeatedly transmitting data at the transmission time of selected uplink radio frequencies It is characterized in that the method of increasing the data recovery rate of the receiving side by transmitting the divided data separately is performed in parallel.

The satellite IoT terminal and the one-way data transmission method using the same according to the present invention independently calculate the transmission time and transmission occupancy time of data with reference to beacon signal information, and increase the reception rate of the receiving side by redundantly transmitting data at a plurality of frequencies. There is an effect of greatly improving the reception efficiency of the receiving side through the parallel method and the method of increasing the error recovery possibility at the receiving side by dividing the data to which the channel coding is applied into a plurality of frequencies and transmitting the same.

1 is a conceptual diagram of a conventional satellite broadcasting;
2 is a conceptual diagram of a beacon-based communication of a typical LoRaWAN;
3 is a conceptual diagram of a beacon-based unidirectional communication through a low-orbit satellite according to the present invention;
4 is a conceptual diagram of transmission by upstream frequency selection according to the present invention;
5 is a conceptual diagram of redundant transmission according to the present invention;
6 is a conceptual diagram of divided transmission according to the present invention;
7 is a configuration diagram of a satellite IoT terminal according to the present invention

Since the present invention can be practiced by adding various changes, specific embodiments are illustrated in the drawings and will be described with reference to the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing each figure, like reference numerals have been used for like elements. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The present invention enables efficient transmission of a satellite IoT terminal that unidirectionally transmits data based on a beacon signal transmitted from the satellite to the terminal.

As shown in FIG. 7, the satellite IoT terminal according to the present invention comprises: a sensor data unit 11 for collecting data such as temperature and location to be transmitted through a satellite channel; a channel coding unit 12 for transmitting information transmitted from a transmitting end through coding using a forward error correction code in order to correct an error experienced in a channel with the data obtained from the sensor data unit; a data division unit 13 for dividing and transmitting channel-coded data for each frequency into several packets in order to reduce loss due to data collision on a wireless channel; a data copy unit 14 for repeatedly transmitting the same data in order to reduce loss due to data collision on a wireless channel; a beacon signal receiving unit 15 for receiving a beacon signal transmitted from a satellite and receiving a beacon message of a beacon device included in the beacon signal; a transmission information extraction unit 16 for extracting a specific transmission time and transmission occupation period by using the beacon message information; a frequency management unit 17 for managing a specific uplink transmission frequency using beacon message information at a specific transmission time and transmission occupation period derived from the transmission information extraction unit; and a transmitter 18 that receives the information of the transmission information extraction unit and the frequency management unit and transmits data to be transmitted to the satellite.

The data transmission method by the satellite IoT terminal randomly selects uplink radio frequencies to be transmitted from a plurality of uplink radio frequencies based on a beacon signal transmitted from a satellite, and selects data using a transmission time randomly calculated for each frequency. A method of increasing the data reception rate of the receiving side by performing redundant transmission at the transmission time of the uplink radio frequencies, and dividing the channel-coded data obtained by performing channel coding of data into a plurality of data to divide the divided data at the transmission time of the selected uplink radio frequencies A method of increasing the data recovery rate of the receiving side by transmitting each is used in parallel.

As shown in FIG. 3, the satellite IoT terminal of the present invention transmits data to a central station based on a beacon transmitted from a low-earth orbit (LEO).

At this time, the data of the satellite IoT terminal collected by the sensor data unit 11 may be transmitted through relays of several LEO satellites, the LEO satellites are synchronized with each other, and a separate downlink frequency that can be received by the satellite IoT terminals is transmitted. Send beacons through

The beacon signal of the satellite received by the beacon signal receiver 15 includes a satellite identifier, a position (latitude/longitude/altitude) of a satellite, satellite time information, uplink radio frequency information, a beacon period, and a transmission occupancy time.

The terminal may simultaneously access a plurality of satellites, and may identify a communication target satellite and estimate a data transmission path using the satellite identifier.

One of the important services of a satellite IoT terminal is to be able to provide its own location information, and location information such as latitude, longitude, and altitude of the satellite is required to identify the direction and distance from the satellite, which is the sensor data unit (11) is collected by.

A satellite IoT terminal must be able to use a plurality of radio frequencies for data transmission. To this end, as shown in FIG. 4, upstream frequencies to the satellites to be accessed must be identified. This uplink radio frequency is made by the frequency management unit 17, and may be predetermined or dynamically provided by a satellite.

Data transmission in such multiple frequencies uses a random frequency hopping technique in a satellite IoT terminal.

The transmission information extraction unit 16 of the satellite IoT terminal derives the data transmission time by itself based on the beacon period and the transmission occupancy time of the beacon signal. This transmission time is derived by a random function of all satellite terminals, and is guaranteed to be unique for each terminal.

A specific uplink transmission frequency is managed by the frequency management unit 17 using beacon message information at a specific transmission time and transmission occupation period derived from the transmission information extraction unit.

The transmission time T(tx) derived for data transmission is T(tx) = T(on) by the transmission index (I) obtained by the random function, the beacon start time T(on), and the transmission occupancy time T(dwell) It is determined by + (I-1) * T(dwell). The period T (period) of the beacon is implemented as a function of the number of Earth orbits of the LEO satellite and the available communication time. The LEO satellite orbits the earth 10 to 16 times, and can communicate with a terminal in a specific location for 20 to 30 minutes at a time.

The satellite IoT terminal may transmit data for T(dwell) at T(tx) within the period of Ton ~ [T(on) + T(period)]. In order to avoid between transmission data of several satellite IoT terminals, a T (guard) time is maintained before and after the transmission occupancy time. That is, the actual transmission available time of the satellite IoT terminal is T(dwell) - 2*T(guard).

The satellite IoT terminal of the present invention transmits data redundantly through a plurality of channels selected by frequency hopping through the data copying unit 14 as shown in FIG. can increase

The receiving side manages the state of the received data and discards the duplicate received data.

The satellite IoT terminal channel-codes data with a code rate K/N (K is the original data size, N is the channel-coded data size) by the channel coding unit 12 in consideration of the failure of the uplink radio frequency section, and the After dividing the result into P pieces of data, the data division unit 13 transmits the divided data to a plurality of channels selected by frequency hopping, respectively, as shown in FIG. 6 to increase the reception data recovery rate of the central station. .

For example, if K=1 and N=2, data to which channel coding is applied is made twice as large as the original data. The data to which the channel coding is applied is divided into P data, and the divided data is transmitted one by one to the P radio frequencies. to restore the original data.

11: Sensor data part
12: channel coding unit
13: data partition
14: data copy unit
15: beacon signal receiver
16: transmission information extraction unit
17: frequency management unit
18: transmitter

Claims (3)

A unidirectional data transmission terminal for transmitting data in one direction, comprising: a sensor data unit 11 for collecting data such as temperature and position to be transmitted through a satellite channel; a channel coding unit 12 for transmitting information transmitted from a transmitting end through coding using a forward error correction code in order to correct an error experienced in the channel with the data obtained from the sensor data unit; a data division unit 13 for dividing and transmitting channel-coded data for each frequency into several packets in order to reduce loss due to data collision on a wireless channel; a data copying unit 14 for repeatedly transmitting the same data in order to reduce loss due to data collision on a wireless channel; a beacon signal receiving unit 15 for receiving a beacon signal transmitted from a satellite and receiving a beacon message of a beacon device included in the beacon signal; a transmission information extraction unit 16 for extracting a specific transmission time and transmission occupation period by using the beacon message information; a frequency management unit 17 for managing a specific uplink transmission frequency using beacon message information at a specific transmission time and transmission occupation period derived from the transmission information extraction unit; and a transmitter 18 that receives the information of the transmission information extraction unit and the frequency management unit and transmits data to be transmitted to the satellite,
In the satellite IoT terminal, the beacon signal receiving unit 15 calculates the transmission time by a random method with reference to the beacon signal and selects the uplink radio frequency in a random manner,
The transmission time extracted by the transmission information extraction unit 16 is T(tx) = T(on) by the transmission index (I) obtained by a random function, the beacon start time T(on), and the transmission occupancy time T(dwell) ) + (I-1) * T(dwell), and the period T(period) of the beacon is implemented as a function of the number of Earth orbits of the LEO satellite and the available communication time, and the LEO satellite travels the earth 10 to 16 times. A satellite IoT terminal characterized in that it rotates and communicates with a terminal in a specific location for 20 to 30 minutes at a time. delete The data transmission method by the satellite IoT terminal of claim 1,
Based on the beacon signal transmitted from the satellite, uplink radio frequencies to be transmitted from a plurality of uplink radio frequencies are randomly selected, and data is repeatedly transmitted at the transmission time of the selected uplink radio frequencies by using the randomly calculated transmission time for each frequency. A method of increasing the data reception rate of the receiving side by performing channel coding of the data, dividing the obtained channel coding data into a plurality of data, and transmitting the divided data at the transmission time of the selected uplink radio frequencies. A unidirectional data transmission method of a satellite IoT terminal, characterized in that the method is increased in parallel.

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