KR101742443B1 - Adaptive lbt method and system for operating long range wide area network in the rfid/usn frequency band - Google Patents

Abstract

The present invention provides an adaptive listen before talk (LBT) method and an adaptive LBT system to operate a long-range wide-area (LoRa) network using a radio-frequency identification (RFID)/ubiquitous sensor network (USN) non-licensed band. The adaptive LBT method to operate a LoRa network using an RFID/USN non-licensed band may comprise: a step of performing channel sensing on a plurality of channels corresponding to the RFID/USN non-licensed band; a step of adaptively setting a transmission time of LoRa data to be transmitted through the LoRa network based on the amount of interference of the channel detected through the channel sensing; a step of transmitting the LoRa data through the detected channel based on the adaptively set transmission time. Therefore, a standby time for the use of a LoRa service can be reduced.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adaptive LBT method and system for LoRa network operation in a license-

Embodiments of the present invention relate to techniques for operating a long range wide area network (LoRa), which is a low power long distance wireless communication, among the Internet of Things (IoT) technology for Internet of Small Things in a license-exempt space.

LoRa (Long Range Wide Area Network), a low-power long-distance wireless communication technology, is a technology used for transmitting and receiving data in smart cities and outdoor areas because of low standby power and low module price. Unlike the conventional LTE, a chip set supporting LoRa is attached to a terminal without a separate base station or relay equipment, and data is transmitted and received at a low power. Bluetooth, ZigBee, etc. are low-power wireless communication protocols, but only provide short-range data transmission service, but LoRa provides long-distance data transmission service with lower power than Bluetooth or Zigbee.

In order to use the existing LTE network instead of using the LoRa network, it is necessary to install the expensive chipset in the terminal in order to utilize the existing LTE base station. Therefore, the LoRa terminal equipped with the low- . For example, the amount of data to be exchanged through the network, such as the location of a child, an elderly person (such as a demented elderly), a patient, confirmation of arrival, parking management of a car, a motorcycle, a bicycle, In order to provide a small amount of simple functions, it is not necessary to install a costly chipset for providing an LTE service such as a smart phone to the terminal, and it only increases the price of the terminal. In other words, it is only necessary to mount an inexpensive LoRa chipset capable of performing the above simple function without needing to mount an LTE chipset on a bicycle or a car key for identifying a car of the user.

Furthermore, LoRa provides data transmission / reception using the license-exempt band, and provides data transmission / reception through the LoRa network supporting the LoRa wireless communication technology using the RFID / USN frequency band. As such, LoRa shares interference with RFID devices in the RFID / USN license-exempt band, resulting in interference.

1 is a diagram showing an RFID / USN license-exempt band.

Referring to FIG. 1, the RFID / USN license-exempt band is a 900 MHz band, and may include, for example, 917 to 923.5 MHz band.

The license-exempted band may include a total of 32 channel bands divided into a high-power channel period and a small-power channel period. At this time, frequency hopping is performed in at least six channels in a high power channel period in the case of the fixed type RFID and in a small power channel period in the case of the mobile RFID, and data communication can be performed. In this case, when the LoRa service is provided in a state in which the high power channel section or the small output channel section occupies the RFID, interference may occur in the existing system, that is, the RFID system.

Accordingly, when transmitting / receiving data through LoRa network using the RFID / USN license-exempted band (ie providing LoRa service), a LoRa network providing LoRa service using the license-exempt band without affecting the existing RFID system Communication technology is required. Korean Patent Laid-Open No. 10-2013-0107942 relates to an ultra low power wireless communication method and apparatus, and discloses a technique of assigning a communication channel with priority to use of the ISM band.

The present invention relates to a method and system for operating a LoRa network for Internet communication of goods using an RFID / USN license-exempt band without affecting an existing RFID system, that is, transmitting and receiving data (i.e., LoRa data) using the license- Technology.

In addition, the present invention relates to a technology for determining transmission time of LoRa data through a LoRa network in consideration of interference amount from an existing RFID system and transmitting / receiving data.

An adaptive LBT method for operating a LoRa network using an RFID / USN license-exempt band, the method comprising: performing channel sensing for a plurality of channels corresponding to the RFID / USN license-exempt band; The method comprising: adaptively setting a transmission time of LoRa data to be transmitted through the LoRa network based on a channel interference amount; and transmitting LoRa data through the detected channel based on the adaptively set transmission time . ≪ / RTI >

According to an aspect, the step of adaptively setting the transmission time may include adjusting a level of the transmission time down by one level if the interference amount is larger than the predetermined reference interference.

According to another aspect, the step of adaptively setting the transmission time is to perform the channel sensing again after a predetermined backoff time if the adjusted transmission time is less than the predetermined minimum time Step < / RTI >

According to another aspect, the step of adaptively setting the transmission time may include setting a level of the transmission time to a maximum level if the interference amount is smaller than the predetermined reference interference.

An adaptive LBT system for operating a LoRa network using an RFID / USN license-exempt band, the system comprising: a channel sensing unit for performing channel sensing for a plurality of channels corresponding to the RFID / USN license-exempt band; A transmission time setting unit adapted to adaptively set a transmission time of LoRa data to be transmitted through the LoRa network based on a detected interference amount of a channel, And a data transmission / reception unit for transmitting data.

In the present invention, in providing LoRa service using the RFID / USN license-exempt band, LBT (Listen Before Talk) is applied to transmit data (i.e., LoRa Data) can be transmitted and received.

In addition, the present invention adjusts the transmission time of LoRa data through the LoRa network in consideration of the amount of interference from the existing RFID system, transmits and receives data, waits unconditionally until there is no interference due to the nearby RFID system, LoRa services can be provided more efficiently than when they are provided. That is, the waiting time for using the LoRa service can be reduced.

1 is a diagram showing an RFID / USN license-exempt band.
2 is a diagram showing a LoRa network according to an embodiment of the present invention.
FIG. 3 is a flowchart illustrating an adaptive LBT method for LoRa network operation in a license-exempt band, according to an embodiment of the present invention.
4 is a block diagram illustrating an internal configuration of an adaptive LBT system according to an embodiment of the present invention.
5 is a flowchart illustrating an operation of confirming a state of a channel after setting a transmission time in an embodiment of the present invention.
Figure 6 is a flow diagram illustrating an operation for determining whether a channel state is idle or busy in one embodiment of the present invention.

The present invention relates to a technology for providing a LoRa service, which is a technology for providing a goods Internet communication service using a license-unlicensed band of RFID / USN, and more particularly to a technology for providing LoRa service by considering the interference with an existing RFID system using the license- (LBT) technique so as to enable transmission and reception of a service, that is, LoRa data.

In the present embodiments, the 'license-exempt band' is a frequency band used for RFID / USN communication, and may include the 917 MHz to 923.5 MHz band.

In the present embodiments, the 'Long Range Wide Area Network' may represent a dedicated network for providing the Internet of things and the Internet of goods using LoRa, which is one of low power long distance communication technologies. For example, it may mean a dedicated IoT network or a dedicated Internet network.

In the present embodiments, the 'LBT system' may include a base station (ie, a LoRa base station) having a channel sensing function, for example, a LoRa gateway, or the like. In addition, the LBT system may have a channel sensing function, i.e., a terminal equipped with a LoRa chipset (LoRa terminal). For example, the LoRa terminal may include various things such as a smart PC, a smart TV, a smart refrigerator, a car key, a bicycle, a smart location notification device, a smart watch, a wearable device, In the present embodiments, the case where the LoRa base station is used as the LBT system will be described as an example, but the LBT system may be the LoRa terminal.

In the present embodiments, in order to provide the LoRa service using the license-exempt band, the LBT system may have to satisfy the following regulations. In this specification, 'LoRa service' may mean a service that provides transmission / reception (or exchange) of data through a LoRa network using a license-exempt band.

1. For passive RFID, occupied frequency bandwidth should be 200kHz or less.

2. For passive RFID reader and writer in frequency hopping, use more than 6 non-overlapping channels and the continuous occupancy time per channel should be less than 0.4 second.

3. When using LBT (Listen Before Talk), if the received signal strength is less than -65dBm after receiving for more than 5msec before transmission, it should transmit radio wave, stop transmission within 4seconds and stop for more than 5msec.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram showing a LoRa network according to an embodiment of the present invention.

2, the LoRa network 200 may include a LoRa terminal 210, a LoRa base station 220, a wired network 230, and a LoRa server 240. At this time, a conventional RFID system using an unlicensed band such as an RFID reader (not shown) and an RFID tag (not shown) may be located around the LoRa terminal 210, If so, the LoRa terminal 210 can start LoRa service such as data transmission.

The LoRa terminal 210 may be one or more electronic devices equipped with a LoRa chipset that enables LoRa communication services such as data transmission and reception using a license-exempt band via a LoRa network. The LoRa terminal 210 can transmit or request data to and receive data from the LoRa server 240 through the LoRa base station.

For example, if the LoRa terminal 210 is a wearable device that provides location tracking of an eye or an old person, the LoRa terminal 210 may transmit its location information to the LoRa server 240 via the LoRa base station 220 And the LoRa server 240 may store data received from the LoRa terminal 210 by matching with the identifier of the LoRa terminal 210. [ When the position confirmation request of the child or the elderly is received from another terminal registered in association with the position confirmation of the LoRa terminal 210 (for example, a LoRa terminal held by a guardian, a parent, a teacher or the like), the LoRa server 240 transmits a LoRa The location information can be provided to the terminal such as the parent or guardian based on the registration information (for example, terminal identification information such as a parent or guardian) matched to the terminal 210.

As another example, in the case of gas meter reading, water meter reading, and electricity meter reading, a meter reading meter installed in the house may be used as the LoRa terminal 210. Data measured and quantified for a predetermined period of time in the meter reading meter may be transmitted to the LoRa server 240 through the LoRa base station 220. The LoRa server 240 transmits the identifier information of the meter reading meter and the received (E.g., user name, user address, user's mobile phone number, etc.) of the meter reading data and the user of the meter reading meter (for example, gas, water, electricity meter subscriber) If there is a data request, the LoRa server 240 can provide the meter reading data to the device registered by the user or the meter reading terminal. At this time, the meter probe provider or the user's device may be a LoRa terminal using a LoRa network, or a terminal of a smart phone, a desktop PC, a notebook or a tablet using an LTE network or a wired network.

At this time, the LoRa terminal 210 transmits data to the LoRa terminal 210 in order to perform data communication with the server 240 through the LoRa base station 220 using the license-exempt band, that is, the RFID / USN band A channel for starting the LoRa service can be allocated. At this time, it is checked whether the RFID / USN service is used around the LoRa terminal 210 before the channel is allocated, and a channel that is not used for the RFID / USN service can be allocated. That is, the LoRa base station 220 can perform channel sensing for checking presence / absence of the RFID / USN service and allocate a channel for starting the LoRa service. Here, the LoRa base station 220 is an example of the LBT system, and detailed operation will be described later with reference to FIG. 3 and FIG.

The LoRa terminal 210 wirelessly connects to the LoRa base station 220 to perform data transmission and reception and the LoRa base station 220 collects data received from the LoRa terminal 210 and transmits the data to the wired backhaul 230 to the LoRa server 240 via the Internet.

FIG. 3 is a flowchart illustrating an adaptive LBT method for LoRa network operation in a license-exempt band according to an exemplary embodiment of the present invention. FIG. 4 illustrates an internal configuration of an adaptive LBT system according to an exemplary embodiment of the present invention. Fig.

4, the adaptive LBT system 400 may include a data transmission / reception unit 410, a channel sensing unit 420, and a transmission time setting unit 430 as the LoRa base station 220 in FIG. 2 . 3 are performed by the components shown in FIG. 4, that is, the data transmission / reception unit 410, the channel sensing unit 420, and the transmission time setting unit 430 .

The data transmitting and receiving unit 410 may transmit data to the LoRa server 240 through the LoRa base station 220 or may receive data from the LoRa server 240. [ As described above, when the LoRa service such as data transmission / reception is requested, the LoRa service is performed using the RFID / USN license-exempt band, so channel sensing for providing the corresponding service may be required.

In step 310, the channel sensing unit 420 may perform channel sensing to check presence or absence of a terminal using the RFID / USN service in the vicinity in order to start the LoRa service. That is, the channel sensing unit 420 may perform channel sensing to check whether the RFID system or the like is using the RFID / USN service through a specific one of the license-exempt bands.

At this time, the channel sensing unit 420 may perform channel sensing many times as many times as the predetermined sensing number in order to secure reliability. For example, the channel sensing unit 420 may perform channel sensing at least ten times.

In step 320, the transmission time setting unit 430 may adaptively set the transmission time of the LoRa data based on the channel interference amount.

For example, if the RFID / USN service is being used through adjacent channels from a specific channel detected through channel sensing, the influence of the RFID / USN service of the adjacent channel may interfere with the specific channel. If there is an RFID system using the RFID / USN service in the vicinity of the adaptive LBT system 300, there may exist channel interference as two different systems use the license-exempt band, and the transmission time setting unit 430 The existing interference amount can be measured and the transmission time can be set based on the measured interference amount.

In step 321, the transmission time setting unit 430 may adjust the level of the transmission time Ton by comparing the measured interference amount with the predetermined reference interference.

For example, if the RFID / USN service is being used at a close distance, the measured amount of interference may be greater than the reference interference. As described above, if the reference interference is larger than the reference interference, the transmission time setting unit 430 may adjust the level of the transmission time Ton by adjusting the transmission time to a level below the transmission time. Here, the level of the transmission time Ton is divided into a plurality of levels from a minimum level to a maximum level, and a transmission time Ton corresponding to each level can be defined in advance. For example, the maximum level can be matched with a transmission time (Ton) of 0.4 seconds. The initial transmission level may be preset to a maximum level or a predetermined specific level (e.g., an intermediate level, etc.), and if the interference amount is larger than the reference interference level, The transmission time can be adjusted to be short.

For example, if the current level corresponds to a maximum level of 0.4 second, if the interference amount is larger than the reference interference, the transmission time setting unit 430 lowers the level of the transmission time by one level so that the transmission time Ton is 0.4 second To 0.3 seconds.

In step 322, if the measured interference amount is smaller than the reference interference, the transmission time setting unit 430 can set the level of the transmission time Ton to the maximum level. For example, since the channel must be occupied within 0.4 second according to the regulation of the license-unlicensed band of RFID / USN, the maximum level can be predefined as 0.4 second, and the time required to occupy the channel Is greater than or less than 0.4 seconds, the maximum level may be changed in accordance with the changed regulation.

In other words, as more RFID systems using the RFID / USN service are located near the LBT system 400, many channels are used for the RFID / USN service among a plurality of channels (for example, 16 channels) . In this way, when the interference amount is larger than the reference interference, since there are many RFID systems within a predetermined distance, i.e., a close distance, even if the detected channel is an idle state, / USN service. Accordingly, if the interference amount is larger than the reference interference, the transmission time setting unit 430 sets the transmission time (time) based on the amount of interference to provide the LoRa service by quickly using the corresponding channel for a short time of 0.3 seconds, Ton) can be adaptively set. At this time, the probability that the RFID / USN service provided through the other channel X is hopped to the detected specific channel Y is 1 / the number of hopping channels (for example, 16), so it may correspond to 6.25%.

If the interference amount is smaller than the reference interference, the transmission time can be set to 0.4 seconds so that the channel can be occupied for the LoRa service for 0.4 seconds, which is the maximum value permitted by the regulation.

In step 323, if the transmission time Ton corresponding to the level of the set transmission time is less than the predetermined minimum time, the channel sensing unit 420 can perform channel sensing again.

For example, if the transmission time for which the level is downwardly adjusted is very short, such as 0.1 second, to transmit only a small amount of LoRa data, the channel sensing unit 420 does not use the corresponding channel and, after a predetermined backoff time The channel sensing can be performed again. In other words, the operation of the channel sensing and the transmission time setting may be repeatedly performed again.

In step 330, when the transmission time Ton of the specific channel detected through the channel sensing is set, the data transmitting / receiving unit 410 may start the LoRa communication service for transmitting the LoRa data through the corresponding channel. At this time, the channel sensing unit 420 may determine the channel state of the specific channel before transmitting the LoRa data after setting the transmission time Ton of the detected specific channel. If the channel state is identified as an idle state, the data transmission / reception unit 410 can transmit LoRa data through the specific channel. Hereinafter, detailed operation for confirming the channel status after setting the transmission time will be described with reference to FIG.

5 is a flowchart illustrating an operation of confirming a state of a channel after setting a transmission time in an embodiment of the present invention.

If the transmission time of the LoRa data is adaptively set in accordance with the amount of interference, the channel sensing unit 420 determines whether the transmission time of the LoRa data is equal to or greater than the channel of the corresponding channel (i.e., You can check the status.

In step 511, if the channel state of the corresponding channel is determined as Busy state, the channel sensing unit 420 can check the channel states of all of the plurality of channels. For example, if the number of hopping channels is 16, the channel sensing unit 420 can check channel states of all 16 channels. Here, the busy state may indicate a case where the RFID / USN service is provided in the corresponding channel. That is, the RFID system can indicate the occupied state of the corresponding channel to use the RFID / USN service.

If it is determined in step 512 that all the channels are in a Busy state, the channel sensing unit 420 may perform channel sensing again after a predetermined backoff time. For example, since all sixteen channels are occupied by the RFID system as busy, that is, there is no channel currently available in the license-exempt band, and therefore, a vacant channel (i.e., a channel of an idle state) It is possible to wait for the off-time and perform channel sensing again.

If it is determined in step 513 that all the channels are not Busy, the channel sensing unit 420 may perform a channel change to a non-busy channel.

For example, after setting the transmission time for the channel 1, the channel state of the channel 1 is checked as Busy state, and the channel state of the channel 6 among the plurality of channels is not the Busy state. Idle State), the channel sensing unit 420 may perform the channel change from the channel 1 to the channel 6. Then, the channel sensing unit 420 may perform the operation of adaptively setting the transmission time for the changed channel 6 according to the interference amount. At this time, when there are a plurality of channels which are in an idle state, the channel sensing unit 420 may perform a change to a channel having the smallest interference amount among a plurality of channels.

In step 520, if the state of the channel for which the transmission time is set is confirmed as an idle state, the data transmission / reception unit 410 can transmit LoRa data through the corresponding channel for the set transmission time. That is, if the interference amount is larger than the reference interference, the LoRa service is provided over the corresponding channel for a short time. If the interference amount is smaller than the reference interference, the channel is occupied for a maximum of 0.4 seconds allowed by the regulation, .

As described above, by providing the LoRa service by adaptively adjusting the transmission time of the LoRa data according to the amount of interference, the license-exempt band can be efficiently used. Table 1 below shows the RFID read success rate when LoRa service is provided by adaptively adjusting the transmission time of LoRa data.

Scenario 1 shows the success rate of RFID service when there is only one RFID system. Scenario 2 shows that LBT (Listen Before Talk) is applied when the RFID system and LBT system coexist. The above-mentioned success rate can be shown. In Scenario 3, if the LBT (Listen Before Talk) is applied in the situation where the RFID system and the LBT system coexist, that is, whether the RFID channel is used or not through the channel sensing, And can be set adaptively to indicate the success rate in the case of using the license-exempt band. Scenario 4 may indicate the RFID read success rate (i.e., the RFID service success rate) when a plurality of RFID systems are present.

Table 1 shows that the longer the transmission time set for the channel, the lower the RFID read success rate. That is, when the transmission time Ton is set to 0.4 second, the read success rate is lowered regardless of the distance from 0.2 second. As the distance between the RFID system (ie RFID reader and tag) and the LBT system increases, the read success rate increases. That is, the smaller the number of RFID systems located in the vicinity of the LBT system, the higher the read success rate. On the contrary, as the distance between the RFID reader and the tag becomes longer, the LBT system can exist between the RFID reader and the tag, so that the read success rate is lowered.

In Table 1, a low read success rate implies requiring a longer read time, and may not ultimately indicate a read failure. Accordingly, as the read success rate decreases, the read time increases and the read rate decreases.

Figure 6 is a flow diagram illustrating an operation for determining whether a channel state is idle or busy in one embodiment of the present invention.

In operation 610, the channel sensing unit 420 may measure the energy of the corresponding channel detected for use in the LoRa service through channel sensing. For example, the strength of a signal received through the channel can be measured.

In operation 620, the channel sensing unit 420 may compare the measured energy with the predetermined reference energy. For example, the reference energy may be preset to -65 dBm. Then, the channel sensing unit 320 can compare whether the measured energy of the corresponding channel is less than -65 dBm.

In step 630, if the measured energy is lower than the reference energy, the channel sensing unit 420 may determine that the channel state is an idle state.

If the measured energy is greater than the reference energy in step 640, the channel sensing unit 420 may determine that the channel is in an idle state.

That is, in the case of a channel having a signal strength of -65 dBm or less, it is confirmed that it is an idle state which is not used for the RFID / USN service. In the case of a channel having a received signal intensity of greater than -65 dBm, It can be confirmed that it is a busy state being used.

As described above, the LBT system that provides the LoRa service using the existing RFID / USN license-exempted band can transmit the LoRa data transmission time (that is, the channel occupancy time) according to the interference amount to the channel detected through the channel sensing Since the LoRa service is provided adaptively, if the interference amount is high, the probability that the RFID system hopes to the corresponding channel is high. Therefore, the LoRa service is occupied for a short time and the RFID system provides the LoRa service if the interference amount is small. Since the probability of hopping is low, it is possible to efficiently provide LoRa service using the license-exempt band used in the existing RFID / USN service by controlling the LoRa service to occupy the channel for a maximum of 0.4 seconds allowed by the regulation .

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (5)

An adaptive LBT method for operating a LoRa network using an RFID / USN license-exempt band,
Performing channel sensing for a plurality of channels corresponding to the RFID / USN license-exempt band;
Adaptively setting a transmission time of LoRa data to be transmitted through the LoRa network based on an interference amount of a channel detected through the channel sensing; And
Transmitting LoRa data over the detected channel based on the adaptively set transmission time
And an adaptive LBT method for LoRa operation. The method according to claim 1,
The step of adaptively setting the transmission time comprises:
If the interference amount is greater than the predetermined reference interference, adjusting the level of the transmission time downward by one step
And an adaptive LBT method for LoRa operation. 3. The method of claim 2,
The step of adaptively setting the transmission time comprises:
If the adjusted transmission time is less than the predetermined minimum time, performing the channel sensing again after a predetermined backoff time
And an adaptive LBT method for LoRa operation. The method according to claim 1,
The step of adaptively setting the transmission time comprises:
If the interference amount is smaller than the predetermined reference interference, setting the level of the transmission time to a maximum level
And an adaptive LBT method for LoRa operation. 1. An adaptive LBT system for operating a LoRa network using an RFID / USN license-exempt band,
A channel sensing unit for performing channel sensing for a plurality of channels corresponding to the RFID / USN license-exempt band;
A transmission time setting unit for adaptively setting a transmission time of LoRa data to be transmitted through the LoRa network based on an interference amount of a channel detected through the channel sensing; And
And a data transmission / reception unit for transmitting LoRa data through the detected channel based on the adaptively set transmission time,
An adaptive LBT system for LoRa operation.

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