Information transmission system, information transmission method, terminal program, and base station program

Abstract

To provide an information transmission system capable of efficient information transmission, an information transmission method, a terminal program, and a base station program.SOLUTION: An information transmission system includes a terminal and a base station. The terminal transmits a packet signal representing packet information in a predetermined time slot using a predetermined frequency band. The base station receives packet information. The terminal generates predetermined transmission data. The terminal calculates packet information, time information representing a time slot, and frequency information representing a frequency band on the basis of predetermined data. The base station calculates the time information on the basis of the time slot in which the packet information has been received. The base station calculates the frequency information on the basis of the frequency band used for receiving the packet information. The base station stores the packet information, the time information, and the frequency information in association with each other. The base station decodes the transmission data on the basis of the packet information, the time information, and the frequency information.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an information transmission system, an information transmission method, a terminal program, and a base station program, and can be suitably used, for example, in an information transmission system, an information transmission method, a terminal program, and a base station program for transmitting information from multiple terminals to a single base station. [Background technology]

[0002] There is a demand for a large number of IoT (Internet of Things) terminals to transmit relatively small amounts of data from each to a single base station. For example, by aggregating sensor data detected by sensor devices on each terminal to a base station or gateway, the aggregating base station can obtain significant statistical data even if the amount of data from each sensor is relatively small.

[0003] Such IoT terminals need to consume little power and be capable of long-distance transmission. For this reason, standards such as LoRaWAN (Long Range Wide Area Network) have been developed as LPWA (Low Power Wide Area) wireless communication standards. LoRaWAN uses a simple MAC (Medium Access Control) layer access protocol and is known to be capable of long-distance transmission with low power consumption.

[0004] On the other hand, when multiple terminals in LoRaWAN send their respective packets to a gateway, the following problems can arise:

[0005] When multiple terminals transmit packets independently, packet collisions may occur, in which two or more packets are transmitted simultaneously, resulting in a decrease in the Packet Delivery Rate (PDR).

[0006] There is a restriction on the transmission time due to the duty cycle (DC), i.e., it is difficult or impossible to increase the number of transmission packets beyond a certain threshold in order to expand the transmission capacity.

[0007] In general, the time interval from when each terminal transmits a packet of information to when it transmits the next packet of information is relatively long.

[0008] In relation to the above, non-patent document 1 (LoRa Alliance, Inc., "LoRaWAN(TM) 1.0.3 Specification", 2018, Internet<URL:https: / / lora-alliance.org / sites / default / files / 2018-07 / lorawan1.0.3.pdf> ) discloses the LoRaWAN specification version 1.0.3. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] LoRa Alliance, Inc., “LoRaWAN(TM) 1.0.3 Specification”, 2018, Internet<URL:https: / / lora-alliance.org / sites / default / files / 2018-07 / lorawan1.0.3.pdf> Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides an information transmission system, an information transmission method, a terminal program, and a base station program capable of performing efficient information transmission. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0011] The means for solving the problems will be explained below using the numbers used in the (Mode for carrying out the invention). These numbers are added to clarify the correspondence between the description in the (Claims) and the (Mode for carrying out the invention). However, these numbers should not be used to interpret the technical scope of the invention described in the (Claims).

[0012] According to one embodiment, an information transmission system (1) includes a terminal (2) and a base station (3). The terminal (2) transmits a packet signal representing packet information in a predetermined time slot using a predetermined frequency band. The base station (3) receives the packet signal. The terminal (2) generates predetermined transmission data. The terminal (2) calculates the packet information, time information representing the time slot, and frequency information representing the frequency band based on the predetermined data. The base station (3) calculates the time information based on the time slot in which the packet signal was received. The base station (3) calculates the frequency information based on the frequency band used to receive the packet signal. The base station (3) stores the packet information represented by the packet signal, the time information, and the frequency information in association with each other. The base station (3) decodes the transmission data based on the packet information, the time information, and the frequency information.

[0013] According to one embodiment, the information transmission method includes generating transmission data and calculating packet information, time information, and frequency information based on the transmission data. The information transmission method further includes transmitting a packet signal representing the packet information in a time slot represented by the time information, using a frequency band represented by the frequency information. The information transmission method further includes receiving the packet signal. The information transmission method further includes calculating the time information based on the time slot in which the packet signal is received. The information transmission method further includes calculating the frequency information based on the frequency band used for receiving the packet signal. The information transmission method further includes storing the packet information represented by the packet signal, the time information, and the frequency information in association with each other. The information transmission method further includes decoding the transmission data based on the packet information, the time information, and the frequency information.

[0014] According to one embodiment, the terminal program (221) is a program for implementing functions of the terminal (2) by having the arithmetic unit (21) of the terminal (2) execute the program. The functions include generating transmission data and calculating packet information, time information, and frequency information based on the transmission data. The functions further include transmitting a packet signal representing the packet signal in a time slot represented by the time information, using a frequency band represented by the frequency information.

[0015] According to one embodiment, the base station program (321) is a program for implementing the functions of the base station (3) by having the arithmetic device (31) of the base station (3) execute the program. The functions include receiving a packet signal and calculating time information based on a time slot in which the packet signal is received. The functions further include calculating frequency information based on a frequency band used to receive the packet signal. The functions further include storing packet information represented by a packet signal, time information, and frequency information in association with each other. The functions further include decoding transmission data based on the packet information, time information, and frequency information. Effect of the Invention

[0016] According to one embodiment, efficient information transmission can be achieved. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing an example of a configuration of an information transmission system according to an embodiment. [Diagram 2] FIG. 2 is a block circuit diagram showing an example of a configuration of a terminal according to an embodiment. [Diagram 3] FIG. 3 is a block circuit diagram showing an example of a configuration of a base station according to an embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of a configuration of an information transmission method according to an embodiment. [Diagram 5] FIG. 5 is a graph for explaining chirp spread spectrum modulation. [Figure 6] FIG. 6 is a graph for explaining packet information and symbols according to one embodiment. [Figure 7] FIG. 7 is a diagram for explaining the transmission method of LoRaWAN. [Figure 8] FIG. 8 is a diagram for explaining an information transmission method according to an embodiment. [Figure 9] FIG. 9 is a table showing an example of parameters of a simulation for comparing LoRaWAN with an information transmission method according to an embodiment. [Figure 10] FIG. 10 is a table showing an example of a simulation result for the LoRaWAN transmission method. [Figure 11] FIG. 11 is a table showing an example of a simulation result of the information transmission method according to the embodiment. [Figure 12] FIG. 12 is a graph comparing the simulation results. [Figure 13] FIG. 13 is a graph comparing the simulation results. [Figure 14]FIG. 14 is a graph comparing the simulation results. [Figure 15] FIG. 15 is a graph comparing the simulation results. [Figure 16] FIG. 16 is a block circuit diagram showing an example of a configuration of a gateway according to an embodiment. [Figure 17] FIG. 17 is a block circuit diagram showing an example of a configuration of a server according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An information transmission system, an information transmission method, a terminal program, and a base station program according to the present invention will be described below with reference to the accompanying drawings.

[0019] (First embodiment) 1, an information transmission system 1 according to an embodiment includes a plurality of terminals 2A, 2B, 2C, and 2D, and a base station 3. When the terminals 2A, 2B, 2C, and 2D are not distinguished from one another, they are collectively referred to as terminal 2.

[0020] Each terminal 2 transmits information independently of the other terminals 2. In other words, each terminal 2 is not synchronized with the other terminals when transmitting information. The base station 3 receives the information transmitted from the terminals 2.

[0021] 2, the terminal 2 according to one embodiment includes a bus 20, a computing device 21, a storage device 22, a communication device 23, and a sensor device 24. The computing device 21, the storage device 22, the communication device 23, and the sensor device 24 are connected via the bus 20 so as to be able to communicate with each other.

[0022] The arithmetic device 21 includes an information division unit 211, a transmission parameter determination unit 212, a CSS (Chirp Spread Spectrum) modulation unit 213, a packet generation unit 214, and a transmission unit 215. The storage device 22 stores terminal ID information representing a terminal ID for identifying the terminal 2, and a terminal program 221 to be executed by the arithmetic device 21. The terminal IDs of the multiple terminals 2 are different from each other. The terminal program 221 may be read from an external recording medium 220 and stored in the storage device 22. The recording medium 220 may be a non-transitory and tangible medium.

[0023] The arithmetic device 21 realizes the functions of the information division unit 211, the transmission parameter determination unit 212, the CSS modulation unit 213, the packet generation unit 214, and the transmission unit 215 by reading and executing the terminal program 221 from the storage device 22. In other words, although the information division unit 211, the transmission parameter determination unit 212, the CSS modulation unit 213, the packet generation unit 214, and the transmission unit 215 are shown as components of the arithmetic device 21 for the sake of convenience in Fig. 2, they are functional units that realize predetermined functions through cooperation between the arithmetic device 21 and the terminal program 221. Details of these functions will be described later.

[0024] The communication device 23 performs wireless communication with the base station 3. The communication device 23 transmits packet information to be received by the base station 3, and also receives signals such as a time adjustment signal transmitted from the base station 3. The terminal program 221 stored in the storage device 22 may be received by the communication device 23 from the base station 3 or another external device.

[0025] The sensor device 24 measures a desired parameter representative of an ambient condition and outputs measurement data representative of the results of this measurement. As an example, the sensor device 24 may be an air temperature sensor for measuring the ambient air temperature, a humidity sensor for measuring the ambient humidity, a carbon dioxide concentration sensor for measuring the ambient carbon dioxide concentration, etc.

[0026] 3, the base station 3 according to one embodiment includes a bus 30, a calculation device 31, a storage device 32, and a communication device 33. The calculation device 31, the storage device 32, and the communication device 33 are connected via the bus 30 so as to be able to communicate with each other.

[0027] The arithmetic device 31 includes a CSS demodulation unit 311, a transmission information detection unit 312, a reception timing detection unit 313, a transmission index detection unit 314, and an information combination unit 315. The storage device 32 stores a base station program 321 to be executed by the arithmetic device 31. The base station program 321 may be read from an external recording medium 320 and stored in the storage device 32. The recording medium 320 may be a non-transitory and tangible medium.

[0028] The arithmetic device 31 reads out the base station program 321 from the storage device 32 and executes it to realize the functions of the CSS demodulation unit 311, the transmission information detection unit 312, the reception timing detection unit 313, the transmission index detection unit 314, and the information combination unit 315. In other words, although the CSS demodulation unit 311, the transmission information detection unit 312, the reception timing detection unit 313, the transmission index detection unit 314, and the information combination unit 315 are each shown as components of the arithmetic device 31 for the sake of convenience in Fig. 3, they are functional units that realize predetermined functions in cooperation with the arithmetic device 31 and the base station program 321. Details of these functions will be described later.

[0029] The communication device 33 performs wireless communication with the terminal 2. The communication device 33 receives packet information transmitted from the terminal 2, and transmits signals such as a time adjustment signal to the terminal 2. The base station program 321 stored in the storage device 32 may be received by the communication device 33 from another external device.

[0030] An example of a configuration of an information transmission method according to an embodiment will be described with reference to the flowchart of FIG.

[0031] In step S01, time adjustment is performed between the base station 3 and each terminal 2. As an example, the calculation device 21 of the terminal 2 generates a time adjustment signal and transmits the time adjustment signal to the base station 3 using the communication device 23. The calculation device 31 of the base station 3 receives the time adjustment signal of each terminal 2 using the communication device 33 and adjusts the time with each terminal 2. There is no need to adjust the time between multiple terminals 2. Note that the frequency of time adjustment may be every predetermined number of information transmissions, depending on the accuracy of the clock functions of the terminal 2 and the base station 3.

[0032] In step S02, the arithmetic device 21 of the terminal 2 generates transmission data. The transmission data includes measurement data representing the result of measurement by the sensor device 24 and terminal ID information representing the terminal ID of the terminal 2. In other words, the arithmetic device 21 of the terminal 2 generates the transmission data based on the measurement data and the terminal ID. As an example, the transmission data may be generated by combining the measurement data and the terminal ID information according to a predetermined format. The measurement by the sensor device 24 and the generation of the measurement data may be performed in step S02, or may be performed before step S02 and the measurement data may be stored in the storage device 22.

[0033] In step S03, the arithmetic unit 21 of the terminal 2 calculates packet information, time information, and frequency information. Note that the time information and frequency information form index information, as will be described later.

[0034] First, the information division unit 211 divides the transmission data into a first portion and a second portion. As an example, the information division unit 211 extracts the first portion from a predetermined first memory address to a predetermined first length from the transmission data, and stores it in the storage device 22 as index information combining time information and frequency information. The information division unit 211 stores the second portion of the transmission data excluding the first portion in the storage device 22.

[0035] Next, the transmission parameter determination unit 212 determines the transmission timing, which is the time slot at which the terminal 2 transmits the packet information, based on the time information included in the index information. The transmission parameter determination unit 212 also determines the frequency channel, which is the frequency band used to transmit the packet information, based on the frequency information included in the index information. The correspondence between the time information and the transmission timing, and the correspondence between the frequency information and the frequency channel will be described later.

[0036] Next, the packet generator 214 generates packet information by, for example, adding header information to the second portion of the transmission data.

[0037] Next, the CSS modulation unit 213 CSS-modulates the packet information to generate a packet signal. CSS modulation will be described later.

[0038] In step S04, the transmitting unit 215 transmits a packet signal representing packet information to the base station 3 using the communication device 23. In detail, the transmitting unit 215 controls the communication device 23 to transmit the packet signal generated in step S03 to the base station 3 during the time slot corresponding to the transmission timing determined in step S03 and using the frequency band corresponding to the frequency channel determined in step S03. Here, each terminal 2 transmits a packet signal to the base station 3 independently of the other terminals 2.

[0039] In step S05, the processor 31 of the base station 3 receives the packet signal via the communication device 33, and in step S06, the memory device 32 of the base station 3 stores the packet information, time information, and frequency information.

[0040] Here, the CSS demodulation unit 311 CSS demodulates the received packet signal, and stores packet information obtained by the CSS demodulation in the storage device 32. The reception timing detection unit 313 detects the time and frequency channel at which the packet signal was received, and stores time information indicating this time and frequency information indicating this frequency channel in the storage device 32. Here, the packet information, time information, and frequency information are stored in the storage device 32 in association with each other.

[0041] In step S07, the processor 31 of the base station 3 decodes the transmission data based on the packet information, the time information, and the frequency information.

[0042] Here, the transmission index detection unit 314 calculates data corresponding to a combination of a time slot and a frequency channel based on a combination of time information and frequency information to restore the first part of the transmission data. The transmission index detection unit 314 can obtain index information in this manner. The transmission information detection unit 312 combines the restored index information with packet information to decode the transmission data, and calculates measurement data and a terminal ID based on the decoded transmission data.

[0043] The information combination unit 315 associates the measurement data with the terminal ID and stores them in the storage device 32 .

[0044] When step S07 is completed, the flowchart in Fig. 4 ends. Thereafter, by processing the measurement data collected from the multiple terminals 2 for each frame period, it is possible to analyze the distribution of the desired parameter measured in the area where the terminals 2 are distributed. In addition, by processing the measurement data collected from the multiple terminals 2 across multiple periods, it is also possible to analyze the time change of the desired parameter measured in the area where the terminals 2 are distributed.

[0045] CSS modulation and CSS demodulation will be explained with reference to Figure 5. In CSS modulation, a certain number of bits of binary data are converted into one chirp signal symbol. In CSS demodulation, the inverse conversion of CSS modulation is performed. Hereinafter, the number of bits of information that can be represented by one chirp signal symbol is referred to as the spreading factor S.

[0046] In the example of Figure 5, the spreading factor S is 2, and 2 S =2 2 There are four types of chirp signal symbols: Symbol A chirp signal having a waveform from time T00 to time T10 is referred to as a chirp signal symbol. In the example of Fig. 5, a chirp signal symbol having a waveform from time T10 to time T20 corresponds to two-bit data "01", a chirp signal symbol having a waveform from time T20 to time T30 corresponds to two-bit data "11", and a chirp signal symbol having a waveform from time T30 to time T40 corresponds to two-bit data "10".

[0047] On the time axis, the symbol length T Symbol is 2 S The length of each chip period is the chip length T Chip In other words, T Symbol =2 S ×T Chip In one embodiment, the frequency of one chirp signal symbol increases during each chip period, while a momentary decrease in frequency may occur at the time separating two consecutive chip periods. In other words, one chip signal symbol in CSS modulation is 2 S It consists of two chips, and the same waveform is reproduced twice. S By cyclically shifting the signal in units of chip periods, S bits of information can be represented.

[0048] In the example of Figure 5, the chip length T Chip is the symbol length T Symbol 2 S =2 2 = 4 equal lengths. In the example of FIG. 5, the chirp signal symbol corresponding to the 2-bit data "00" has a waveform in which the frequency increases from frequency F0 to frequency F4 in the period from time T00 to time T10. Similarly, the chirp signal symbol corresponding to the 2-bit data "01" has a waveform in which the frequency increases from frequency F3 to frequency F4 in the period from time T10 to time T11, and from frequency F0 to frequency F3 in the period from time T11 to time T20. The chirp signal symbol corresponding to the 2-bit data "11" has a waveform in which the frequency increases from frequency F2 to frequency F4 in the period from time T20 to time T22, and from frequency F0 to frequency F2 in the period from time T22 to time T30. The chirp signal symbol corresponding to the 2-bit data "10" has a waveform in which the frequency increases from frequency F1 to frequency F4 during the period from time T30 to time T33, and from frequency F0 to frequency F1 during the period from time T33 to time T40.

[0049] The range in which the frequency of the chirp signal symbol changes is referred to as the bandwidth W. In the example of FIG. 5, the bandwidth W ranges from frequency F0 to frequency F4. In one embodiment, the chip length T Chip is the inverse of the bandwidth W. That is, T Chip =1 / W holds true.

[0050] An example of the configuration of packet information according to an embodiment will be described with reference to Fig. 6. In Fig. 6, the horizontal axis represents time and the vertical axis represents frequency. As shown in Fig. 6, in one embodiment, one packet information P includes N chirp signal symbols S1, S2, ..., S N-1 , S N Here, N is the number of chirp signal symbols per packet information, which can be calculated using the following formula:

number

number

[0051] Therefore, the packet length T Packet is calculated using the following formula:

number

[0052] The time slots and frequency bands will be described with reference to Fig. 7 and Fig. 8. Fig. 7 shows an example of the time slots and frequency bands for transmitting packet information P1 and P2 in a LoRaWAN transmission method. Fig. 8 shows an example of the time slots and frequency bands for transmitting packet information P1 and P2 in an information transmission method according to one embodiment.

[0053] In both Fig. 7 and Fig. 8, the horizontal axis represents time, and the vertical axis represents frequency. In both Fig. 7 and Fig. 8, the first packet information P1 is transmitted using a frequency band from frequency F12 to frequency F13 during a time frame from time T100 to time T200. Similarly, in both Fig. 7 and Fig. 8, the second packet information P2 is transmitted using a frequency band from frequency F10 to frequency F11 during a time frame from time T200 to time T300.

[0054] Due to the constraints of DC, in both the LoRaWAN transmission method of FIG. 7 and the information transmission method according to the embodiment of FIG. 8, the terminal 2 transmits the signal in one frame period T Frame Only one packet of information can be sent during

[0055] Here, the packet length T Packet is the frame period T Frame In detail, as shown in FIG. Packet is one frame period T Frame The time slot period T Slot As described below. Therefore, in one embodiment, the base station 3 detects during which of a plurality of time slots included in one time frame the terminal 2 transmitted packet information, and this makes it possible to transmit additional information not included in the packet information from the terminal 2 to the base station 3. In the example of Fig. 8, by dividing one frame into four time slots, it is possible to add and transmit 2-bit data "00", "01", "11" or "10" to the packet information.

[0056] Similarly, it should be noted that the bandwidth W used by one packet information is sufficiently narrower than the frequency band from frequency F10 to frequency F14 available for transmitting the packet information. In detail, as shown in FIG. 8, the bandwidth W is equal to or less than the bandwidth of the frequency channel obtained by dividing the frequency band from frequency F10 to frequency F14 into four equal parts. Therefore, in one embodiment, the base station 3 detects which of the multiple frequency channels included in the available frequency band used by the terminal 2 to transmit the packet information, and thus it becomes possible to transmit additional information not included in the packet information from the terminal 2 to the base station 3. In the example of FIG. 8, by dividing the available frequency band into four frequency channels, it is possible to add 2-bit data "00", "01", "11" or "10" to the packet information and transmit it. The additional information transmitted by using the time slot and the frequency channel is referred to as index information.

[0057] In this way, in one embodiment, the amount of packet data that can be transmitted by one packet of information is B pl In addition, the amount of index data B is the amount of index information represented by the time slot and frequency channel. pi can be transmitted from the terminal 2 to the base station 3. Here, the amount of index data B pi is calculated by the following formula:

number

number

number

[0058] Therefore, in one embodiment, the total amount of data that can be transmitted when transmitting one packet of information from the terminal 2 to the base station 3 is B prop is calculated by the following formula:

number

[0059] Taking the above into consideration, an additional explanation will be given regarding the flowchart in FIG.

[0060] In step S03, the number of bits of the time information as the first part of the transmission data is equal to M, and the transmission parameter determination unit 212 determines the time slot corresponding to the content of the time information as the transmission timing. Similarly, the number of bits of the frequency information as the second part of the transmission data is equal to K, and the transmission parameter determination unit 212 determines the frequency band corresponding to the content of the frequency information as the frequency channel.

[0061] In step S07, contrary to step S03, the reception timing detector 313 uses data corresponding to the time slot, which is the reception timing, as the first part of the transmission data, and uses data corresponding to the frequency channel as the second part of the transmission data.

[0062] The inventors verified the superiority of the information transmission method according to this embodiment over the LoRaWAN transmission method by computer simulation. The specifications of this simulation are as shown in the table of FIG. 9. A base station 3 is placed at the center of a square area with each side being 1 km (kilometer), and 100 terminals 2 are placed at random locations within this area. The frame period T Frame Each terminal 2 generates and transmits packet information every 10 seconds. For each transmitted packet information, if both the SNR (Signal-Noise Ratio) and SIR (Signal-Interference Ratio) at the base station 3 exceed their respective thresholds, it is determined that the reception is successful. Such a simulation was performed 100 times for each of the cases where the spreading factor S is 7, 8, 9, and 10.

[0063] The results of the above simulations are shown in the table of Fig. 10 for LoRaWAN, and in the table of Fig. 11 for the information transmission method according to this embodiment. Here, the packet delivery rate is the ratio of the average value of the transmission data amount obtained by 100 simulations to the theoretically ideal data amount in information transmission. It was confirmed that the packet delivery rate of the information transmission method according to this embodiment was higher than the packet delivery rate of the transmission method by LoRaWAN in each of the cases where the spreading factor S was 7, 8, 9, and 10.

[0064] Figures 12, 13, 14, and 15 are graphs comparing the above simulation results between the information transmission method according to this embodiment and the transmission method by LoRaWAN. In common to Figures 12, 13, 14, and 15, the horizontal axis represents the amount of transmission data per packet in bits, the vertical axis represents the CDF (Cumulative Distribution Function), the dashed graphs show the simulation results of the transmission method by LoRaWAN, and the solid graphs show the simulation results of the information transmission method according to this embodiment.

[0065] As shown in FIG. 12, when the spreading factor S=7, if the CDF is the same, the number of bits of a packet transmitted by the information transmission method of this embodiment increases by about 14 bits compared to the LoRaWAN transmission method, which corresponds to an increase rate of about 1.2%.

[0066] As shown in FIG. 13, when the spreading factor S=8, if the CDF is the same, the number of bits of a packet transmitted by the information transmission method of this embodiment increases by approximately 14 bits compared to the LoRaWAN transmission method, which corresponds to an increase rate of approximately 2.0%.

[0067] As shown in FIG. 14, when the spreading factor S=9, if the CDF is the same, the number of bits of a packet transmitted by the information transmission method of this embodiment increases by approximately 14 bits compared to the LoRaWAN transmission method, which corresponds to an increase rate of approximately 4.9%.

[0068] As shown in FIG. 15, when the spreading factor S=10, if the CDF is the same, the number of bits of a transmission packet using the information transmission method of this embodiment increases by about 15 bits compared to the LoRaWAN transmission method, which corresponds to an increase rate of about 32.6%.

[0069] In this way, the information transmission method according to this embodiment has higher transmission efficiency than the LoRaWAN transmission method. The main reason is that index information is transmitted simultaneously in addition to packet information. In other words, the amount of information that can be transmitted at one time under the same conditions can be increased by the amount of index information.

[0070] Alternatively, by transmitting a part of the information that would normally be transmitted as packet information as index information, the packet information is reduced accordingly, and the packet length T Packet This reduces the probability of packets being transmitted from different terminals 2 colliding with each other, leading to a further improvement in transmission efficiency.

[0071] (Second embodiment) As a modification of the base station 3 according to the first embodiment, this embodiment describes a configuration example in which the base station 3 is separated into a gateway 3A and a server 3B. The terminal 2 according to this embodiment is the same as that in the first embodiment.

[0072] 16, the gateway 3A includes a bus 30A, a calculation device 31A, a storage device 32A, and a communication device 33A. The calculation device 31A, the storage device 32A, and the communication device 33A are communicatively connected via the bus 30A.

[0073] The arithmetic device 31A includes a CSS demodulation unit 311, a reception timing detection unit 313, and a reception information addition unit 316. The storage device 32A stores a gateway program 321A to be executed by the arithmetic device 31A. The gateway program 321A may be read from an external recording medium 320A and stored in the storage device 32A. The recording medium 320A may be a non-transitory and tangible medium.

[0074] The calculation device 31A reads out the gateway program 321A from the storage device 32A and executes it to realize the functions of the CSS demodulation unit 311, the reception timing detection unit 313, and the reception information addition unit 316. In other words, although the CSS demodulation unit 311, the reception timing detection unit 313, and the reception information addition unit 316 are each shown as components of the calculation device 31A for the sake of convenience in Fig. 16, they are functional units that realize predetermined functions in cooperation with the calculation device 31A and the gateway program 321A.

[0075] The communication device 33A performs wireless communication with the terminal 2. The communication device 33A receives packet information transmitted from the terminal 2, and transmits signals such as a time adjustment signal to the terminal 2. Note that the gateway program 321A stored in the storage device 32A may be received by the communication device 33A from the server 3B or another external device.

[0076] The CSS demodulation unit 311 and the reception timing detection unit 313 function in the same manner as the CSS demodulation unit 311 and the reception timing detection unit 313 shown in Fig. 3. That is, in step S06 of the flowchart in Fig. 4, the CSS demodulation unit 311 CSS demodulates the received transmission signal, and stores packet information obtained by the CSS demodulation in the storage device 32A. In addition, in step S06, the reception timing detection unit 313 detects the time and frequency channel at which the packet information was received, and stores time information indicating this time and frequency information indicating this frequency channel in the storage device 32A.

[0077] The reception information adding unit 316 adds time information and frequency information to the packet information and stores it in the storage device 32A. The communication device 33A stores the packet information, to which the time information and frequency information are added, collected in the storage device 32A, in a frame period T Frame The request signal may be transmitted to the server 3B every time the request is received, or may be transmitted in response to a request signal transmitted from the server 3B.

[0078] 17, the server 3B includes a bus 30B, a calculation device 31B, a storage device 32B, and a communication device 33B. The calculation device 31B, the storage device 32B, and the communication device 33B are communicatively connected via the bus 30B.

[0079] The arithmetic device 31B includes an information division unit 317, a transmission index detection unit 314, and an information combination unit 315. The storage device 32B stores a server program 321B to be executed by the arithmetic device 31B. The server program 321B may be read from an external recording medium 320B and stored in the storage device 32B. The recording medium 320B may be a non-transitory and tangible medium.

[0080] The arithmetic device 31B reads out and executes the server program 321B from the storage device 32B to thereby realize the functions of the information division unit 317, the transmission index detection unit 314, and the information combination unit 315. In other words, although the information division unit 317, the transmission index detection unit 314, and the information combination unit 315 are shown as components of the arithmetic device 31B for the sake of convenience in Fig. 17, they are functional units that realize predetermined functions in cooperation with the arithmetic device 31B and the server program 321B.

[0081] The communication device 33B performs wireless communication with the gateway 3A. The communication device 33B receives packet information to which time information and frequency information are added, which is automatically transmitted from the gateway 3A, and stores the packet information in the storage device 32B. Alternatively, the communication device 33B may transmit a request signal to the gateway 3A for each frame period, and receive packet information to which time information and frequency information are added, which is transmitted from the gateway 3A in response to the request signal and is stored in the storage device 32A of the gateway 3A, and store the packet information in the storage device 32B. The server program 321B stored in the storage device 32B may be received by the communication device 33B from another external device.

[0082] In step S07 of the flowchart in FIG. 4, the information division unit 317 divides the packet information to which the time information and frequency information are added into time information, frequency information, and packet information, and stores the divided information in the storage device 32B. The transmission index detection unit 314 calculates data corresponding to a time slot based on the time information to restore a first portion of the transmission data, and calculates data corresponding to a frequency channel based on the frequency information to restore a second portion of the transmission data. In this manner, the transmission index detection unit 314 can obtain index information. The information combination unit 315 further combines the restored index information with the packet information to decode the transmission data, calculates measurement data based on the combined transmission data and the terminal ID, and stores the measurement data in association with the terminal ID in the storage device 32B.

[0083] Other configurations and operations of this embodiment are similar to those of the first embodiment.

[0084] As described above, in this embodiment as well, efficient information transmission can be performed, similarly to the first embodiment.

[0085] Although the invention made by the inventors has been specifically described above based on the embodiment, it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways without departing from the gist of the invention. Furthermore, the respective features described in the above embodiment can be freely combined within the scope of technical compatibility. [Explanation of symbols]

[0086] 1. Information Transmission System 2, 2A~2D terminals 20 Bus 21 Arithmetic unit 211 Information division section 212 Transmission parameter determination unit 213 CSS Modulation Section 214 Packet Generation Unit 215 Transmitter 22 Storage device 220 Recording media 221 Terminal Program 23 Communication Equipment 24 Sensor device 3 base station 3A Gateway 3B Server 30, 30A, 30B Bus 31, 31A, 31B Arithmetic unit 311 CSS demodulator 312 Transmission information detection unit 313 Reception timing detection unit 314 Transmission index detection unit 315 Information connection part 316 Reception information addition unit 317 Information division section 32, 32A, 32B storage device 320, 320A, 320B Recording medium 321 Base Station Program 321A Gateway Program 321B Server Program 33, 33A, 33B Communication equipment F0~F4 frequency F10~F14 Frequency P, P1, P2 packet information S1, S2, S N-1 , S N Chirp Signal Symbols T00~T03, T10~T13, T20~23, T30~T33, T40 Time T100~T103, T200~T203, T300 time W Bandwidth

Claims

1. a terminal that transmits a packet signal representing packet information in a predetermined time slot using a predetermined frequency band; a base station for receiving the packet signal; Equipped with The terminal includes: A computing device for generating predetermined transmission data; an information division unit that divides the transmission data into a first portion as a combination of time information and frequency information and a remaining second portion; a transmission parameter determination unit that determines the time slot based on the time information and determines the frequency band based on the frequency information; a packet generator that generates the packet information based on the second portion; Equipped with The base station, Calculating the time information based on the time slot in which the packet signal was received; Calculating the frequency information based on the frequency band used for the reception of the packet signal; storing the packet information represented by the packet signal, the time information, and the frequency information in association with each other; Decoding the transmission data based on the packet information, the time information, and the frequency information; The transmission parameter determination unit determines the time slot and the frequency band independently of the second portion and the packet information; The packet generation unit generates the packet information independently of the first portion, the time information, the time slot, the frequency information, and the frequency band. Information transmission system.

2. 2. The information transmission system according to claim 1, A plurality of the terminals, Each of the plurality of terminals A storage device for storing different terminal IDs; the arithmetic unit that generates the transmission data including the terminal ID; Equipped Information transmission system.

3. 3. The information transmission system according to claim 2, The computing device includes: the information division unit dividing the transmission data into the first portion as a combination of the time information and the frequency information, and the remaining second portion; the transmission parameter determination unit determining the time slot based on the time information and determining the frequency band based on the frequency information; the packet generator generating the packet information based on the second portion; a CSS (chirp spread spectrum) modulation unit that generates a packet signal by CSS modulating the packet information; Equipped Information transmission system.

4. 4. The information transmission system according to claim 3, Each of the terminals comprises: A first communication device that transmits the packet information independently of other terminals. Further equipped with The base station, a second communication device that receives the plurality of pieces of packet information transmitted from the plurality of terminals; Equipped Information transmission system.

5. 5. The information transmission system according to claim 4, The first communication device of each of the terminals transmits a time alignment signal; the second communication device receives the time alignment signal from each of the terminals; The base station synchronizes the time with each of the terminals based on the time synchronization signal. Information transmission system.

6. In the information transmission system according to any one of claims 3 to 5, Each of the terminals comprises: Sensor device for outputting measurement data representing the results of measuring a given parameter Further equipped with The computing device includes: The transmission data is generated based on the measurement data and the terminal ID. Information transmission system.

7. In the information transmission system according to any one of claims 3 to 6, The base station, a CSS demodulation unit that CSS demodulates the packet signal to generate the packet information; a reception timing detection unit that detects the time information indicating the time slot in which the packet signal is received and the frequency information indicating the frequency band in which the packet signal is received; a transmission index detection unit that detects index information added to the packet information based on the combination of the time information and the frequency information; an information combination unit that combines the packet information and the index information to decode the transmission data; Equipped Information transmission system.

8. In the information transmission system according to any one of claims 3 to 6, The base station, a gateway that receives the packet information, calculates the packet information, the time information, and the frequency information, and stores the packet information, the time information, and the frequency information in association with each other; a server connected to the gateway and configured to decode the transmission data based on the packet information, the time information, and the frequency information; Equipped Information transmission system.

9. generating transmission data; Dividing the transmission data into a first portion as a combination of time information and frequency information and a remaining second portion; determining a time slot based on the time information; determining a frequency band based on the frequency information; generating packet information based on the second portion; transmitting a packet signal representing the packet information using the frequency band during the time slot; receiving the packet signal; calculating the time information based on the time slot in which the reception of the packet signal occurred; calculating the frequency information based on the frequency band used for the reception of the packet signal; storing the packet information represented by the packet signal, the time information, and the frequency information in association with each other; decoding the transmission data based on the packet information, the time information, and the frequency information; Including, Determining the time slots includes: determining the time slot independently of the second portion and the packet information; Including, Determining the frequency bands includes: determining the frequency band independent of the second portion and the packet information; Including, generating the packet information generating the packet information independent of the first portion, the time information, the time slot, the frequency information, and the frequency band; Includes Method of information transmission.

10. A program for implementing a function of a terminal by causing a computing device of the terminal to execute the program, The function is generating transmission data; Dividing the transmission data into a first portion as a combination of time information and frequency information and a remaining second portion; determining a time slot based on the time information; determining a frequency band based on the frequency information; generating packet information based on the second portion; transmitting a packet signal representing the packet information using the frequency band during the time slot; Including, Determining the time slots includes: determining the time slot independently of the second portion and the packet information; Including, Determining the frequency bands includes: determining the frequency band independent of the second portion and the packet information; Including, generating the packet information generating the packet information independent of the first portion, the time information, the time slot, the frequency information, and the frequency band; Includes Terminal program.

11. A program for causing a computing device of a base station to execute the program to realize a function of the base station, The function is receiving a packet signal; calculating time information based on a time slot in which the reception of the packet signal occurred; calculating frequency information based on a frequency band used for the reception of the packet signal; storing packet information represented by the packet signal, the time information, and the frequency information in association with each other; decoding transmission data based on the packet information, the time information, and the frequency information; Including, Decoding the transmitted data includes: decoding a first portion of the transmission data based on the time information and the frequency information; Decoding a second portion of the transmission data other than the first portion based on the packet information. Including, Calculating the time information Calculating the time information independently of the second portion and the packet information. Including, Calculating the frequency information Calculating the time information independently of the second portion and the packet information. Including, Decrypting the second portion comprises: Decoding the second portion independently of the first portion, the time information, the time slot, the frequency information, and the frequency band. Including, Base station program.

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