WO2022114328A1

WO2022114328A1 - Time synchronization-based contention-free lora wireless communication method and device

Info

Publication number: WO2022114328A1
Application number: PCT/KR2020/017291
Authority: WO
Inventors: 지영민
Original assignee: 한국전자기술연구원
Priority date: 2020-11-30
Filing date: 2020-11-30
Publication date: 2022-06-02
Also published as: KR102278731B1

Abstract

Provided is a contention-free LoRa wireless communication method for battery-based end-device low power maximization through guaranteed transmission slot allocation of an end-device to which a synchronization technology is applied. A time synchronization-based contention-free LoRa wireless communication method according to an embodiment of the present invention comprises: a step in which one or more end-devices are registered in a gateway; a step in which the gateway sequentially allocates a guaranteed transmission slot to each of the registered end-devices; and a step in which each of the end-devices receives a beacon according to the allocated guaranteed transmission slot, and transmits IoT sensing data. Accordingly, a larger number of end-devices can be managed under a gateway than in the prior art, as the number of end-devices increases, a time taken for transmission increases, but a battery lifetime can be increased upon an increase in a sleep interval, and since all intervals except for an end-device registration period operate in a contention-free manner without contention, energy consumption of a device is considerably reduced and a maximum battery lifetime can thus be secured.

Description

Time synchronization-based contention-free LoRa wireless communication method and apparatus

The present invention relates to a LoRa (low power, wide area) wireless communication method, and more particularly, to a non-competition LoRa wireless communication method for maximizing battery-based end-device low power through allocation of an end-device transmission guarantee slot to which a synchronization technology is applied. will be.

A class A device of LoRa wireless communication is configured to secure a transmission time through contention in a slotted Aloha scheme as illustrated in FIG. 1 .

Specifically, Class A of LoRa wireless communication will operate as illustrated in FIG. 2 .

When an end-device occupies a channel in the Slotted Aloha method, the corresponding slot becomes available to the end-device. When the channel is occupied, the end-device transmits gateway data to the UL, and the gateway transmits data to the end-device. If there is, it is configured to transmit data to DL1 to DL2.

At this time, if the number of end-devices at the end is small, the transmission may not consume a lot of energy because there is not intense competition. There is a problem with this.

On the other hand, long-distance low-power wireless communication technology is not multi-hop-based, but mostly in the form of a star topology, and in the case of a gateway, it is configured in a form in which low power is not required for data reception and is always powered.

That is, if only the time synchronization and transmission time of the terminal end-device can be clearly adjusted, the battery life time of the corresponding device can be maximized.

Therefore, it is required to find a way to maximize the battery life time by applying the low-power long-distance battery technology of the IoT sensing device to acquire information of a larger number of devices through one gateway.

The present invention has been devised to solve the above problems, and an object of the present invention is a low-power long-distance battery technology of an IoT sensing device that can allocate a transmission guarantee slot of an end-device to which a time synchronization technology using a gateway and a GPS signal is applied. To provide a time synchronization-based contention-free LoRa wireless communication method and apparatus that can obtain information on a larger number of devices through a single gateway and maximize battery life time by applying .

According to an embodiment of the present invention for achieving the above object, a time synchronization-based contention-free LoRa wireless communication method includes: registering one or more end-devices to a gateway; sequentially allocating, by the gateway, a transmission guarantee slot to each of the registered end-devices; and receiving, by each end-device, a beacon according to the assigned transmission guarantee slot and transmitting IoT sensing data.

And, in the registration step, when the gateway is in the sleep period within the cycle period, a new end-device may be registered.

In addition, in the allocation step, when a new end-device is registered with the gateway, transmission guarantee slots are sequentially allocated to the registered end-devices, and in this case, the transmission step, when the gateway is an active section within the cycle period, guaranteeing its own transmission The end-device at which the slot time has arrived may receive a beacon from the gateway and transmit IoT sensing data to the gateway.

And, when the number of registered end-devices increases, the gateway may decrease the sleep period within the cycle period and increase the active period at the same time.

Also, the gateway may extend the cycle period by a multiple of two to secure the sleep period when the sleep period within the cycle period is reduced to less than or equal to a critical point.

And in the allocating step, the number of end-devices registered in the gateway gradually increases, and when the cycle period is gradually extended by a multiple of 2, when the length of the extended cycle period is greater than or equal to a threshold, the cycle period is stopped from expanding, It is possible to stop allocating a transmission guarantee slot for a newly registered end-device, and to secure a transmission time through contention in the slotted Aloha method.

In addition, in the allocation step, when a specific end-device among the registered end-devices relinquishes the occupation of the allocated transmission guaranteed slot, the end-device that has given up the occupation of the transmission guaranteed slot becomes active thereafter, and when data is transmitted , it is possible to secure the transmission time through contention in the slotted Aloha method.

And in the allocation step, when the length of the extended cycle period is equal to or greater than a threshold, if a specific end-device gives up the occupation of the allocated transmission guarantee slot, the end-device that secures the transmission time through contention transmits IoT sensing data. By checking the frequency, the end-device having the highest frequency may be allocated to the transmission guarantee slot.

In addition, in the transmission step, the end-device calculates its allocated transmission guarantee slot time by using an internal clock, and waits for receiving a beacon signal based on the calculation result, wherein the end-device has an internal clock error When synchronization signal loss occurs due to this, after time synchronization is performed through a GPS signal, it is possible to calculate its own transmission guaranteed slot time again.

On the other hand, according to another embodiment of the present invention, a time synchronization-based non-contention LoRa wireless communication device, an end-device for collecting IoT sensing data; and a gateway that registers one or more end-devices and sequentially allocates a transmission guarantee slot to each of the registered end-devices, wherein each end-device transmits a beacon at its assigned transmission guarantee slot time. Receive and transmit IoT sensing data.

In addition, according to another embodiment of the present invention, a time synchronization-based contention-free LoRa wireless communication method includes: sequentially allocating a transmission guarantee slot to each end-device registered by a gateway; and receiving, by each end-device, a beacon according to the allocated transmission guarantee slot and transmitting IoT sensing data.

And according to another embodiment of the present invention, a time synchronization-based non-contention LoRa wireless communication device, an end-device for collecting IoT sensing data; and a gateway that sequentially allocates a transmission guarantee slot to each of the registered end-devices, wherein each end-device receives a beacon at its assigned transmission guarantee slot time, and can transmit IoT sensing data. have.

As described above, according to the embodiments of the present invention, a larger number of end-devices can be managed under the gateway than before, and as the number of end-devices increases, the time taken for transmission increases, but in the sleep interval Battery life can be increased due to the increase, and since all sections except for the end-device registration cycle operate in a non-competition-free manner, the energy consumption of the device is remarkably reduced, thereby maximizing the battery life.

1 is a diagram provided for the description of LoRa wireless communication in the Slotted Aloha scheme;

Fig. 2 is a view provided for explaining the operation of class A of the LoRa radio communication shown in Fig. 1 above;

3 is a flowchart provided in the description of a contention-free LoRa wireless communication method according to an embodiment of the present invention;

4 is a view provided for the description of a contention-free LoRa wireless communication method according to an embodiment of the present invention;

5 is a diagram provided for the explanation of a process of extending a cycle when the number of registered end-devices exceeds the available slots;

6 is a diagram provided in the description of a contention-free LoRa wireless communication device according to an embodiment of the present invention;

7 is a diagram provided to explain the operation of an end-device according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

3 is a flowchart provided for explaining a contention-free LoRa wireless communication method according to an embodiment of the present invention, FIG. 4 is a diagram provided for explaining a contention-free LoRa wireless communication method according to an embodiment of the present invention, FIG. 5 is a diagram provided to explain a process of extending a cycle when the number of registered end-devices exceeds the available slots.

The contention-free LoRa wireless communication method according to this embodiment applies the low-power long-distance battery technology of the IoT sensing device that can allocate the transmission guarantee slot of the end-device 100 to which the time synchronization technology using the gateway 200 and the GPS signal is applied. , is provided to obtain information on a larger number of devices through one gateway 200 and maximize battery life time.

To this end, in the present contention-free LoRa wireless communication method, the gateway 200 allocates a specific number of transmission guarantee slots to determine an initial cycle and performs an operation.

Specifically, when one or more end-devices 100 are registered in the gateway 200 (S310), the gateway 200 sequentially allocates a transmission guarantee slot to each of the registered end-devices 100 (S320) , determine the initial cycle, and perform the operation.

In this case, since the end-device 100 initially connected to the gateway 200 does not exist, all sections operate as a sleep (=inactive) section.

And each registered end-device 100 may receive a beacon (signal) in its own order according to the assigned transmission guarantee slot (S330), and transmit IoT sensing data (S340).

Specifically, if the gateway 200 is an active period within the cycle period, the end-device 100 at which its transmission guarantee slot time has arrived receives a beacon from the gateway 200, and IoT sensing to the gateway 200 data will be transmitted.

That is, the gateway 200 registers the new end-device 100 during the sleep period within the cycle period, and when the new end-device 100 is registered, sequentially allocates transmission guarantee slots to allow the node to cycle through the cycle. Allows to receive beacons and transmit data in their own order of cycles (a specific order).

Accordingly, in the gateway 200, the number of end-devices 100 to be registered gradually increases, and the transmission guarantee slots allocated within the cycle period increase, so that the active period within the cycle period is extended according to the number of registered devices. .

In this case, when the number of registered end-devices 100 increases, the gateway 200 may decrease the sleep period within the cycle period and increase the active period at the same time.

Also, when the sleep period within the cycle period is reduced below a preset threshold, the gateway 200 may extend the cycle period by a multiple of two as illustrated in FIG. 5 to secure the sleep period. Here, the multiple expansion of 2 means that the cycle section length is extended to 2 times, 4 times, 8 times, 16 times, etc. the length of the initial cycle section.

Specifically, when the number of slots in the sleep period equal to or greater than the preset threshold is reduced, the gateway 200 may secure the sleep period by extending the cycle period by a multiple of 2. Accordingly, when the number of connected end-devices 100 increases, the transmission period is also gradually intermittently transmitted.

And among the registered end-devices, a specific end-device 100 may give up the occupation of the allocated transmission guarantee slot, and if the occupation of its own transmission guarantee slot is given up, the end-device 100 giving up the occupation of the transmission guarantee slot After becoming active, when data is to be transmitted, a transmission guarantee slot may be allocated or the transmission time may be secured through contention in the Slotted Aloha method.

That is, when a specific end-device 100 does not want frequent transmission, it gives up its assigned transmission guarantee slot occupation, continues to operate in a sleep state to reduce energy consumption, and is allocated a transmission guarantee slot again or is in an active state In the Slotted Aloha method, the transmission time can be secured through contention.

In addition, at this time, if the length of the extended cycle period is equal to or greater than the threshold, if the specific end-device 100 gives up the occupation of the allocated transmission guarantee slot, the gateway 200 determines the transmission time through contention in the Slotted Aloha method. By checking the frequency of IoT sensing data transmitted by the secured end-devices 100 , the end-device 100 having the highest frequency may be allocated to the transmission guarantee slot.

Through this, the end-device 100 does not transmit IoT sensing data even when the allocated transmission guarantee slot time arrives, and energy consumption can be reduced for the life of the battery (life time).

On the other hand, the gateway 200, when the number of end-devices 100 to be registered gradually increases, and the cycle period is gradually extended to a multiple of 2, when the length of the extended cycle period is equal to or greater than a threshold, the cycle period is extended , stops allocating a transmission guarantee slot to the newly registered end-device 100, and secures a transmission time through contention in the slotted Aloha method.

Specifically, the gateway 200 extends the cycle period by a multiple of 2 when the sleep period within the cycle period is reduced below a preset threshold point, but when it becomes 16 times the initial cycle period, stops the extension of the cycle period, and newly Slotted to stop allocating a transmission guarantee slot for the end-device 100 to be registered, receive a beacon signal transmitted by the gateway 200, compete within a sleep period to receive a transmission guarantee slot, and proceed with the device registration procedure It is possible to secure the transmission time in the Aloha method.

6 is a diagram provided to explain a contention-free LoRa wireless communication device according to an embodiment of the present invention.

Referring to FIG. 6 , the end-device 100 may include a sensor 110 , a first communication unit, a first processor 130 , and a GPS module 140 .

The sensor 110 is the IoT sensor 110 , and the first communication unit may receive a beacon from the gateway 200 and transmit IoT sensing data received from the sensor 110 to the gateway 200 .

To this end, the first communication unit may be composed of a receiving end 121 (RX) receiving a beacon from the gateway 200 and a transmitting end 122 (TX) transmitting IoT sensing data.

The first processor 130 is provided to process general matters of the end-device 100 .

Specifically, the first processor 130 may receive beacons in its own order according to the allocated transmission guarantee slot and transmit IoT sensing data.

In addition, if frequent transmission is not desired, the first processor 130 gives up its assigned transmission guarantee slot occupation, continues to operate in a sleep state to reduce energy consumption, and receives a transmission guarantee slot again or an active state In the Slotted Aloha method, the transmission time can be secured through contention.

On the other hand, the end-device 100, synchronization of its own transmission guarantee slot time for receiving a beacon signal is the biggest issue, and the first processor 130 according to the present embodiment utilizes an internal clock to transmit its own transmission. It calculates the guaranteed slot time, finds its own transmission guaranteed slot, and waits for beacon (signal) reception.

However, when the loss of the synchronization signal caused by the error of the internal clock occurs, the first processor 130 calculates its own transmission guarantee slot time again after performing time synchronization by enabling the GPS module 140 . And, it is possible to wait for the beacon (signal) reception by finding the transmission guaranteed slot time through the calculated result.

The GPS module 140 may provide a GPS signal to the first processor 130 .

The gateway 200 may include a second communication unit 210 and a second processor 220 .

The second communication unit 210 may be connected to the first communication unit.

The second processor 220 may register the end-device 100 through the second communication unit 210 or may sequentially allocate a transmission guarantee slot to each of the registered end-devices 100 .

Also, the second processor 220 may transmit a beacon to the specific end-device 100 according to the allocated transmission guarantee slot and receive IoT sensing data.

In addition, as described above, when the number of slots in the sleep period equal to or greater than the preset threshold is reduced, the second processor 220 may secure the sleep period by extending the cycle period by a multiple of 2.

7 is a diagram provided to explain the operation of the end-device 100 according to an embodiment of the present invention.

Referring to FIG. 7 , the end-device 100 is in an inactive sleep state (S710), and when its own transmission guarantee slot time arrives, it becomes an active state (S720) and waits for a beacon (signal) reception is done (S730).

If the end-device 100 does not receive a beacon from the gateway 200 (S740-No), it switches the GPS module 140 to an operating state (S750), and performs time synchronization (S755), and then the next It may be in the sleep state until the transmission guarantee slot time (S760).

And when the end-device 100 receives a beacon from the gateway 200 (S740-Yes), it updates its own transmission guarantee slot time (S770), and transmits IoT sensing data to the gateway 200 ( S780). When the transmission of IoT sensing data is completed, thereafter, it returns to the sleep state again (S790).

Through this, when the time synchronization does not match, the end-device 100 may change the GPS module 140 to an operating state to perform time synchronization, and when the time synchronization matches, the GPS module 140 By limiting the operation of the battery, it is possible to extend the life of the battery.

On the other hand, it goes without saying that the technical idea of the present invention can be applied to a computer-readable recording medium containing a computer program for performing the functions of the apparatus and method according to the present embodiment. In addition, the technical ideas according to various embodiments of the present invention may be implemented in the form of computer-readable codes recorded on a computer-readable recording medium. The computer-readable recording medium may be any data storage system readable by the computer and capable of storing data. For example, the computer-readable recording medium may be a ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical disk, hard disk drive, or the like. In addition, the computer-readable code or program stored in the computer-readable recording medium may be transmitted through a network connected between computers.

In addition, although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention as claimed in the claims In addition, various modifications are possible by those of ordinary skill in the art, and these modifications should not be individually understood from the technical spirit or perspective of the present invention.

Claims

registering one or more end-devices with the gateway;

sequentially allocating, by the gateway, a transmission guarantee slot to each of the registered end-devices; and

A time synchronization-based contention-free LoRa wireless communication method comprising: each end-device receiving a beacon according to an assigned transmission guarantee slot and transmitting IoT sensing data.
The method according to claim 1,

The registration steps are:

Time synchronization-based contention-free LoRa wireless communication method, characterized in that when the gateway is in the sleep period within the cycle period, a new end-device is registered.
3. The method according to claim 2,

The allocation step is

When a new end-device is registered in the gateway, transmission guarantee slots are sequentially allocated to the registered end-devices,

The transmission step is

If the gateway is an active period within the cycle period, the end-device, whose transmission guaranteed slot time has arrived, receives a beacon from the gateway, and transmits IoT sensing data to the gateway. .
3. The method according to claim 2,

gateway,

When the number of registered end-devices increases, the sleep period within the cycle period is reduced and the active period is increased at the same time.
5. The method according to claim 4,

gateway,

When the sleep period within the cycle period is reduced to less than or equal to a critical point, the time synchronization-based contention-free LoRa wireless communication method, characterized in that the cycle period is extended by a multiple of two in order to secure the sleep period.
6. The method of claim 5,

The allocation step is

When the number of end-devices registered in the gateway increases gradually, and the cycle period is gradually extended by a multiple of 2, when the length of the extended cycle period is greater than or equal to a threshold, the extension of the cycle period is stopped, and the newly registered end - Time synchronization-based contention-free LoRa wireless communication method, characterized in that the transmission guarantee slot assignment to the device is stopped, and the transmission time is secured through contention in the slotted Aloha method.
7. The method of claim 6,

The allocation step is

If a specific end-device among the registered end-devices relinquishes the occupation of the allocated transmission guaranteed slot, the end-device that has given up the occupation of the transmission guaranteed slot becomes active after that. Time synchronization-based contention-free LoRa wireless communication method, characterized in that to secure the transmission time through.
8. The method of claim 7,

The allocation step is

If the length of the extended cycle period is greater than or equal to the threshold, if a specific end-device gives up the occupation of the allocated transmission guarantee slot, the frequency of IoT sensing data transmitted by the end-device that secures the transmission time through contention is checked, A time synchronization-based contention-free LoRa wireless communication method, characterized in that the highest frequency end-device is allocated to a transmission guarantee slot.
The method according to claim 1,

The transmission step is

The end-device uses the internal clock to calculate its assigned transmission guaranteed slot time, and waits to receive a beacon signal based on the calculation result;

The end-device is

When synchronization signal loss occurs due to an internal clock error, time synchronization is performed through a GPS signal, and then its own transmission guarantee slot time is calculated again.
end-devices that collect IoT sensing data; and

A gateway that registers one or more end-devices and sequentially allocates a transmission guarantee slot to each of the registered end-devices;

Each end-device is

A time synchronization-based contention-free LoRa wireless communication device, characterized in that it receives a beacon in its assigned transmission guaranteed slot time, and transmits IoT sensing data.
sequentially allocating, by the gateway, a transmission guarantee slot to each of the registered end-devices; and

A time synchronization-based contention-free LoRa wireless communication method comprising: each end-device receiving a beacon according to an assigned transmission guarantee slot and transmitting IoT sensing data.
end-devices that collect IoT sensing data; and

Including; a gateway for sequentially allocating a transmission guarantee slot to each registered end-device;

Each end-device is

A time synchronization-based contention-free LoRa wireless communication device, characterized in that it receives a beacon in its assigned transmission guaranteed slot time, and transmits IoT sensing data.