KR102471155B1 - Cell overlapping prevention algorithm based slotframe scheduling method of relay apparatus - Google Patents

Abstract

A slot frame scheduling method of a relay device included in an IoT system in a SWIPT environment is disclosed. The slot frame scheduling method includes the steps of receiving a cell allocation request including information on the length of a slot frame set according to a transmission period of the electronic device from an electronic device, at least one empty cell in a slot frame having a set length Identifying, obtaining a first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission and reception, information on the first list and the second list Transmitting a cell allocation response including information about a first cell selected in a first list and a second cell selected in a second list from the electronic device do.

Description

Slot frame scheduling method based on cell overlap prevention algorithm of relay device { CELL OVERLAPPING PREVENTION ALGORITHM BASED SLOTFRAME SCHEDULING METHOD OF RELAY APPARATUS }

The present disclosure relates to a slot frame scheduling method of a relay device, and more particularly, to a multi-slot frame scheduling method based on a COP (Cell Overlapping Prevention) algorithm.

Recently, SWIPT (Simultaneous Wireless Information and Power Transfer) has been devised in which a sensor device acquires energy from a radio frequency (RF) signal received from a nearby HAP (Hybrid Access Point) and exchanges data packets using the acquired energy. .

As a result, a hybrid access point (HAP) can wirelessly transmit and receive data while wirelessly supplying power to sensor devices in the IoT device.

However, in the case of heterogeneous sensor devices with different transmission cycles, as a result of HAP using only a single length slot frame, it is difficult to supply energy and transmit data in a timely manner due to back-off delay and collision between sensor devices.

Registered Patent Publication No. 10-21402540000 (2020.06.17)

The present disclosure provides a slot frame scheduling method of a relay device capable of increasing a cell utilization rate of electronic devices by using a frame having a flexible length according to a transmission period of the electronic device in a SWIPT environment.

Specifically, the present disclosure provides a slot frame scheduling method capable of ensuring timeliness of energy supply and data transmission in an IoT network based on a TS-SWIPT environment including electronic devices (sensor devices) having different transmission cycles. to provide.

The objects of the present disclosure are not limited to the above-mentioned objects, and other objects and advantages of the present disclosure not mentioned above can be understood by the following description and will be more clearly understood by the embodiments of the present disclosure. Further, it will be readily apparent that the objects and advantages of the present disclosure may be realized by means of the instrumentalities and combinations indicated in the claims.

A slotframe scheduling method of a relay device included in an Internet of Things (IoT) system in a Simultaneous Wireless Information and Power Transfer (SWIPT) environment according to an embodiment of the present disclosure includes a transmission period of an electronic device Receiving, from the electronic device, a cell assignment request including information on a length of a slot frame set according to the step, wherein at least one via not allocated to another electronic device among a plurality of cells included in a slot frame having the set length Identifying an empty cell, based on the identified at least one empty cell, a first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission/reception Acquiring 2 lists, transmitting a cell assignment response including information on the first list and the second list to the electronic device, at least one selected by the electronic device from the first list and receiving, from the electronic device, a cell assignment confirmation including information on a first cell and at least one second cell selected by the electronic device from the second list.

The slot frame scheduling method includes supplying power to the electronic device within a timeslot of the first cell among the plurality of cells, and supplying power to the electronic device and data within the timeslot of the second cell among the plurality of cells. It may further include the step of transmitting and receiving.

Meanwhile, in the present slot frame scheduling method, when the slot frame having the set length is not included in the slot frame list, the slot frame having the set length may be added to the slot frame list.

In this case, the identifying of the at least one empty cell may include generating a virtual slot frame having a length corresponding to the least common multiple of the lengths of the slot frames included in the slot frame list; Dividing the slot frame into a plurality of partitions according to the set length, and identifying an empty cell in each of the plurality of partitions.

Meanwhile, in the receiving of the cell allocation request from the electronic device, the cell allocation request including information on the number of cells required for power supply and the number of cells required for data transmission/reception may be received from the electronic device. . Here, the obtaining of the first list and the second list may include the number of the identified empty cells additionally to generate the number of cells required for power supply, the number of cells required for data transmission and reception, and candidate lists. If more than or equal to the sum of the number of required cells, the first list and the second list may be obtained using the identified empty cells.

However, the slot frame scheduling method of the relay apparatus may further include identifying that slot frame scheduling has failed when the number of the identified empty cells is less than the sum.

Meanwhile, the obtaining of the first list and the second list may include selecting a first candidate cell for power supply from among the identified at least one empty cell, and including the selected first candidate cell. Obtaining 1 list, selecting a cell having a larger timeslot offset than the first candidate cell among the identified at least one empty cell as a second candidate cell for data transmission and reception, and including the selected second candidate cell The second list may be obtained.

According to an embodiment of the present disclosure, a relay device included in an Internet of Things (IoT) system in a Simultaneous Wireless Information and Power Transfer (SWIPT) environment communicates with an electronic device and wirelessly supplies power to the electronic device. It includes a communication unit for doing so, and a processor connected to the communication unit. The processor receives a cell allocation request including information on a length of a slot frame set according to a transmission period of the electronic device from the electronic device through the communication unit, and within a slot frame having the set length. A first method comprising identifying at least one empty cell not allocated to another electronic device among a plurality of included cells, and including one or more candidate cells for power supply based on the identified at least one cell. Obtaining a second list including a list and one or more candidate cells for data transmission and reception, and transmitting a cell allocation response including information on the first list and the second list to the electronic device through the communication unit, The communication unit sends a cell allocation response including information on at least one first cell selected by the electronic device in the first list and at least one second cell selected by the electronic device in the second list. It is received from the electronic device through

An Internet of Things (IoT) system in a Simultaneous Wireless Information and Power Transfer (SWIPT) environment according to an embodiment of the present disclosure includes an electronic device, and performing communication with the electronic device and wirelessly supplying power to the electronic device. Including a relay device. The electronic device sets the length of the slot frame according to the transmission period of the electronic device, identifies the number of cells required for power supply and the number of cells required for data transmission and reception, and determines the length of the set slot frame. A cell allocation request including information about is transmitted to the relay device. The relay device identifies at least one empty cell not allocated to another electronic device among a plurality of cells included in the slot frame having the set length, and based on the identified at least one cell, A first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission/reception are obtained, and cell assignment including information about the first list and the second list is obtained. A response is sent to the electronic device. In addition, the electronic device selects at least one first cell from the first list as many as the number of cells required for power supply, and selects at least one second cell from the second list required for transmitting and receiving the data. Cells are selected as many as the number, and cell allocation confirmation including information on the selected first and second cells is transmitted to the relay device.

The multi-slot frame scheduling method of the relay device according to the present disclosure has an effect of having improved delay performance, throughput, and cell utilization rate compared to the conventional TSCH in a SWIPT environment.

1 schematically illustrates a system architecture of a TS-SWIPT supported IoT network in TMSS according to an embodiment of the present disclosure;
2 is a flowchart illustrating a slot frame scheduling method of a relay device according to an embodiment of the present disclosure;
3 is a diagram showing an example of a slot frame structure of TSCH MAC;
4 is a sequence diagram illustrating an embodiment of the operation of a 3-step 6P transaction;
5 is a sequence diagram for explaining an example in which an electronic device and a relay device perform operation of a 3-step 6P transaction supporting both power supply and data transmission according to an embodiment of the present disclosure;
6 is a timing diagram for transmitting data from the electronic device 100 to the relay device 200;
7 is a block diagram for explaining configurations of an electronic device 100 and a relay device 200 according to an embodiment of the present disclosure;
8a and 8b are graphs for comparing delay performance of TMSS with conventional TSCH according to an embodiment of the present disclosure;
9a and 9b are graphs for comparing total throughput performance of TMSS with conventional TSCH according to an embodiment of the present disclosure, and
10A and 10B are graphs for comparing cell utilization performance of TMSS with existing TSCH according to an embodiment of the present disclosure.

Prior to a detailed description of the present disclosure, the method of describing the present specification and drawings will be described.

First, terms used in the present specification and claims are general terms in consideration of functions in various embodiments of the present disclosure. However, these terms may vary depending on the intention of a technician working in the art, legal or technical interpretation, and the emergence of new technologies. In addition, some terms are arbitrarily selected by the applicant. These terms may be interpreted as the meanings defined in this specification, and if there is no specific term definition, they may be interpreted based on the overall content of this specification and common technical knowledge in the art.

In addition, the same reference numerals or numerals in each drawing attached to this specification indicate parts or components that perform substantially the same function. For convenience of description and understanding, the same reference numerals or symbols are used in different embodiments. That is, even if all components having the same reference numerals are shown in a plurality of drawings, the plurality of drawings do not mean one embodiment.

Also, in the present specification and claims, terms including ordinal numbers such as “first” and “second” may be used to distinguish between elements. These ordinal numbers are used to distinguish the same or similar components from each other, and the meaning of the term should not be construed as being limited due to the use of these ordinal numbers. For example, the order of use or arrangement of elements associated with such ordinal numbers should not be limited by the number. If necessary, each ordinal number may be used interchangeably.

In this specification, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprise" or "consist of" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other It should be understood that the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof is not precluded.

In the embodiments of the present disclosure, terms such as “module,” “unit,” and “part” are terms used to refer to components that perform at least one function or operation, and these components are hardware or software. It may be implemented or implemented as a combination of hardware and software. In addition, a plurality of "modules", "units", "parts", etc. are integrated into at least one module or chip, except for cases where each of them needs to be implemented with separate specific hardware, so that at least one processor can be implemented as

In addition, in an embodiment of the present disclosure, when a part is said to be connected to another part, this includes not only a direct connection but also an indirect connection through another medium. In addition, the meaning that a certain part includes a certain component means that it may further include other components without excluding other components unless otherwise stated.

The present disclosure provides time-slotted channel hopping (TSCH) multi-slotframe scheduling to ensure energy harvesting and timeliness of data transmission for electronic devices (or sensor devices) having different transmission periods in a TS-SWIPT supported IoT network. (TMSS: TSCH multiple slot-frame scheduling) protocol is provided.

TMSS according to an embodiment of the present disclosure may use TSCH MAC standardized in IEEE 802.15.4-2015 as a basic MAC method, which is a TDMA-based MAC protocol, and may use several slot frames with different lengths to support various types of traffic. can be used

A TSCH slot frame is composed of a plurality of cells having a fixed size, and each cell may be indicated by a time offset and a channel offset.

In TMSS, the electronic device may set the same slot frame length as the transmission period. In this case, the electronic device may estimate the number of power and data cells to be allocated to the configured slot frame and then request cell allocation from the HAP by using the length of the slot frame and the number of power and data cells.

Initially, the HAP maintains one slot frame, and when receiving a cell allocation request from an electronic device, it executes a cell overlapping prevention (COP) algorithm to solve the cell overlapping problem of the already allocated existing cells.

After the cell overlap problem is resolved through the COP algorithm, the HAP may respond to the electronic device with a candidate cell list including empty cells in the slot frame of the corresponding electronic device.

When a response is received from the HAP, the electronic device may determine a power cell (cell for supplying power) and a data cell (cell for transmitting/receiving data) by referring to the candidate cell list.

In this regard, an experimental simulation was performed to confirm the superiority of TMSS according to the present disclosure, and the performance of TMSS was compared with that of TSCH MAC using a single (length) slot frame. As a result, the TMSS according to the present disclosure achieves an average of 40.41% lower delay, 0.68% higher total throughput, and 6.44% higher cell utilization compared to the conventional TSCH MAC using a single-slot frame.

In order to support various transmission periods of different types of electronic devices in a TS-SWIPT supported IoT network, TMSS according to an embodiment of the present disclosure uses a multi-simultaneous slot frame of the TSCH MAC standard, where 6top of the IETF 6TiSCH standard Power cells and data cells can be allocated using protocol (6P).

The operation of the TMSS according to the present disclosure and the configuration/system of related devices will be described through the following drawings.

1 schematically illustrates a system architecture of a TS-SWIPT supported IoT network in TMSS according to an embodiment of the present disclosure.

Referring to FIG. 1 , a TS-SWIPT supporting IoT network 10 may include a relay device 200 and a plurality of different electronic devices 100-1, 2, ....

Here, each electronic device may correspond to various types of sensor devices for obtaining information about the surrounding environment or various types of terminal devices that perform at least one function/operation by receiving a user command. It can be implemented in various types of devices to configure the IoT system.

The relay device 200 may be implemented as a hybrid access point (HAP) capable of wirelessly supplying power to each electronic device while being wirelessly connected to at least one electronic device.

The relay device 200 may transmit data received from the electronic device to at least one external server, or may transmit data received from the external server to at least one electronic device.

Each electronic device may have a different transmission period and may be placed within the transmission range of the relay device 200 .

Here, each electronic device and the repeater 200 may be equipped with a single omni-directional antenna and communicate with each other in a half-duplex manner. Meanwhile, power transmission is performed only by the electronic device in the relay device 200, whereas data transmission may be performed in both directions.

The electronic device 100 may monitor the surrounding environment (eg, using at least one sensor) and periodically transmit data packets to the relay device 200 .

However, the electronic device may first collect necessary energy through a specific RF signal transmitted from the relay device 200 before performing sensing and data transmission.

Accordingly, when starting network operation, each electronic device may first check a transmission period and set it as a slot frame length.

Meanwhile, the electronic device 100 may identify the number of cells required for power supply and the number of cells required for data transmission/reception.

Specifically, when an Enhanced Beacon (EB) signal is received by the relay device 200, the electronic device may measure a received signal strength indicator (RSSI) of the received signal and then check information included in the EB signal.

Here, the information included in the EB signal may include a time slot length, the number of slot frames, a slot frame identifier, the length of each slot frame, power and data cells allocated to each slot frame, transmit (Tx) power, etc. .

In addition, the electronic device may estimate the number of power cells required for each slot frame (the number of cells required for power supply) by calculating expected energy consumption per slot frame and expected energy yield per timeslot.

Here, the expected energy yield per timeslot may vary depending on the distance between the relay device 200 and the electronic device.

Therefore, the measured RSSI can be used to find the distance in this estimation process.

Meanwhile, the number of data cells required for data transmission and reception may be estimated through the number of data packets, data packet size, and data rate.

As such, if the number of power cells and data cells required for each slot frame is estimated, the electronic device may transmit a cell allocation request including information on the length (ie, transmission period) of the configured slot frame to the relay device 200 .

In this case, the cell allocation request may also include information on the number of power cells and data cells required for each slot frame identified above.

On the other hand, the relay device 200 plays a role in coordinating the entire network and provides power for supplying power to electronic devices. To this end, the relay device 200 broadcasts EB to provide network information such as a slot frame list, reserved power, and data cells. can be advertised periodically.

The slot frame list maintained by the relay device 200 includes slot frames of the relay device 200 and slot frames of reserved electronic devices, and each slot frame may have a different length and be indexed with a unique identifier.

2 is a flowchart illustrating a slot frame scheduling method of a repeater according to an embodiment of the present disclosure.

Referring to FIG. 2 , the relay device 200 may receive a cell allocation request transmitted by the electronic device 100 (S210).

At this time, the cell allocation request may include information about the length of the slot frame set according to the transmission period of the electronic device 100 . In addition, the cell allocation request may include information about the number of cells required for power supply and the number of cells required for data transmission and reception.

Specifically, the relay device 200 may maintain one slot frame to broadcast EB and exchange control packets (eg, cell assignment request, cell assignment response, etc.).

Here, whenever a cell allocation request including information on a new slot frame length (set according to a transmission period of an electronic device) is received from at least one electronic device (from at least one electronic device), the relay device 200 ) may add a new slot frame to the slot frame list.

Also, the relay device 200 may identify at least one empty cell not allocated to another electronic device among a plurality of cells included in a slot frame having a set length (S220).

At this time, the relay device 200 generates a virtual slot frame having a length corresponding to the least common multiple of the lengths of the slot frames included in the slot frame list, and converts the generated virtual slot frame according to the previously set length of the slot frame. It can be divided into multiple partitions.

Also, the relay device 200 may identify an empty cell in each of a plurality of partitions.

Next, the relay device 200 uses the identified at least one empty cell, a first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission/reception. A list can be acquired (S230).

Specifically, the relay device 200 determines the candidate power cell by referring to the slot frame list, the information included in the received cell allocation request (ie, the slot frame length, the number of power cells and the number of data cells), and the already allocated existing cells. A first list for data cells and a second list for candidate data cells may be generated.

At this time, the relay device 200 may identify the required number of power cells through information included in the cell allocation request, and generate a (first) list including candidate power cells greater than or equal to the required number of power cells.

Also, the relay device 200 may identify the required number of data cells through information included in the cell allocation request, and generate a (second) list including candidate data cells equal to or greater than the required number of data cells.

Here, the relay device 200 may generate a (second) list including candidate data cells having timeslot offsets greater than timeslot offsets of candidate power cells. As a result, power supply may be performed prior to data transmission and reception.

However, if as many candidate power/data cells as the required number of power/data cells are not found (eg, if no extra cells are found in the slot frame due to communication and power supply to other electronic devices of the relay device 200), case), scheduling of the electronic device 100 and the relay device 200 may be identified as failure.

Meanwhile, the relay device 200 may transmit a cell allocation response including a list of candidate power cells identified in step S230 and a list of candidate data cells to the electronic device 200 (S240).

When a cell allocation response is received from the relay device 200, the electronic device 100 selects a cell for power supply and a cell for data transmission/reception, and confirms the cell allocation including information on the selected cells to the relay device 200. ) can be transmitted.

Specifically, the electronic device 100 may select at least one cell for supplying power from among the candidate power cells included in the list of candidate power cells. At this time, the electronic device 100 may select as many cells as the number of cells necessary for power supply.

Also, the electronic device 100 may select at least one cell for data transmission/reception among candidate data cells included in the list of candidate data cells. At this time, the electronic device 100 may select as many cells as the number of cells required for data transmission/reception.

As a result, the relay device 200 may receive cell allocation confirmation (S250).

3 illustrates an example of a slot frame structure of TSCH MAC.

Referring to Figure 3, a slotframe may consist of a fixed number of time slots, generally defined in length to accommodate the maximum size of a data packet.

Accordingly, the slot frame length may be determined according to the number of time slots.

In a slot frame, a pair [timeslot offset, channel offset] can represent each cell, and timeslot offset and channel offset represent timeslot and channel indexes, respectively.

A cell may be used for data transmission or power supply between a pair of devices (electronic device and relay device).

Specifically, a cell may be assigned to a specific pair of devices to exclusively perform data (or power) transmission (ie, a dedicated cell).

However, a cell may be allocated to be shared by a plurality of device pairs (ie, a shared cell). In this case, competition between electronic devices for transmitting data packets is inevitable.

Slot frames are repeated. Thus, the role of the assigned cell can continue to be maintained in subsequent slot frames.

Meanwhile, as described above, the TSCH MAC standard may use multiple simultaneous slot frames each having a different length.

Here, all slot frames may be overlapped in order to set a communication schedule comprehensively considering cells allocated to multiple slot frames.

To this end, slot frames are aligned based on timeslot boundaries, and an absolute slot number (ASN) of a first timeslot within a first slot frame may be set to 0.

ASN represents the total number of time slots that have elapsed since network startup.

When a cell having a specific ASN is simultaneously used by two or more electronic devices using slot frames of different lengths, cell overlap may occur. To solve this problem, the TSCH MAC standard can assign a transmission priority to each slot frame using the slot frame handle (i.e. macSlotframeHandle), which is an identifier for the slot frame.

That is, a low macSlotframeHandle may have a higher transmission priority than a high macSlotframeHandle. However, in this approach, delay performance may be degraded because transmission delay is unavoidable when an electronic device using a lower macSlotframeHandle cell overlaps.

Therefore, in order to prevent cell overlap, the TMSS according to the present disclosure may use a cell-overlapping prevention (COP) algorithm, which is a new algorithm that generates a candidate power and data cell list consisting only of empty cells over all slot frames.

Meanwhile, the existing TSCH MAC standard does not specify a method of setting and managing a TSCH schedule for device-to-device communication. The IETF 6TiSCH working group has designated a 6TiSCH operating sublayer (6top) on top of the TSCH MAC. The minimum 6TiSCH configuration sets the initial TSCH schedule and the 6top protocol (6P) manages the TSCH schedule according to the cell allocation procedure.

In this case, for cell allocation within the slot frame, 6P may support two types of cell allocation procedures, 2-step and 3-step 6P transactions. In the former case, a device requesting cell allocation (ie, an electronic device) may generate a candidate cell list, and in the latter case, a device receiving the request (ie, a relay device) may generate a candidate cell list.

TMSS according to the present disclosure may use 3-step 6P transactions. Accordingly, the relay device 200 may generate a candidate cell list.

Relatedly, FIG. 4 illustrates one embodiment of the operation of a three-phase 6P transaction.

In FIG. 4, Type, SeqNum, NumCells, and CellList represent message types, transaction sequence numbers, the number of cells to be added, and cell sets, respectively.

Referring to FIG. 4 , the electronic device 100 may transmit a cell allocation request message to allocate two cells (for data transmission/reception) to the relay device 200.

When the cell allocation request message is received, the relay device 200 randomly selects an empty cell within the slot frame to generate a candidate cell list, and generates a cell allocation response including information about the generated candidate cell list. ) message to the electronic device 100.

Here, the relay device 200 may set the number of candidate cells in the candidate cell list to be greater than the NumCells value (ie, the number of cells to be added), and set the CellList of the cell assignment response message to be the same as the candidate cell list.

Finally, the electronic device 100 selects two cells corresponding to the number of cells to be added from the candidate cell list, and sends a cell allocation confirmation message including information about the selected cells to the relay device 200. ) can be transmitted.

On the other hand, since the above-described three-step 6P transaction is designed to allocate only a single type of cell (ie, a data cell for data transmission and reception), the above-described three-step 6P transaction is a TS-using both a power cell and a data cell. If applied to the SWIPT-based IoT network as it is, the number of exchanged control messages can increase rapidly, resulting in high overhead.

Accordingly, the TMSS according to an embodiment of the present disclosure may simultaneously allocate power cells and data cells using the modified 3-step 6P transaction.

In relation to this, FIG. 5 is a sequence diagram for explaining an overall operation of TMSS for a pair of devices (HAP and electronic device) according to an embodiment of the present disclosure.

In order to allocate both power cells and data cells within a slot frame of a TS-SWIPT supported IoT network, TMSS according to an embodiment of the present disclosure may use a modified 3-step 6P transaction as shown in FIG. 4 .

Here, NumPwrCells, NumDataCells, PwrCellList, and DataCellList are the number of power cells to be added (the number of cells required for each slot frame for power supply), the number of data cells to be added (the number of cells required for each slot frame for data transmission and reception), and power cells set and data cell set, respectively.

Referring to FIG. 5, TMSS according to an embodiment of the present disclosure uses a SlotframeLength field indicating the length of a slot frame requested for cell allocation in a cell allocation request message to support the use of TSCH multi-simultaneous slot frames. can

Here, the electronic device 100 may first check the transmission period of the electronic device 100 and set it as the slot frame length (SlotframeLength).

Next, the electronic device 100 may wait for the EB broadcast by the relay device 200 .

When the EB is received from the relay device 200, the electronic device 100 obtains RSSI information of the EB, and calculates the distance between the relay device 200 and the electronic device 100 using Equation 1 below. have.

Here, RSSI _d is an RSSI value obtained through the electronic device 100, RSSI ₁ is an RSSI value obtained when the distance is 1 m, and α corresponds to a path loss parameter.

Also, the electronic device 100 may estimate the number of power cells and data cells to be allocated within a slot frame.

In relation to this, FIG. 6 shows a timing diagram for transmitting data from the electronic device 100 to the relay device 200 .

Here, TsTxOffset and TsRxAckDelay are time intervals preparing for data packet transmission and acknowledgment reception, respectively. In this interval, the electronic device 100 is in an idle state.

In order to estimate the number of power cells (N _pwrCells ) to be added to the configured slot frame, the electronic device 100 may first calculate an expected energy consumption per slot frame (Q _slotframe ).

For example, when the electronic device 100 is a sensor device, the expected energy consumption per slot frame (Q _slotframe ) may be determined as the sum of energy consumed for sensing and data transmission for each slot frame (eg, Q _{slotframe =} Q _sensing + Q _transmission ). Here, it may be assumed that Q _sensing is predefined as a predetermined value according to the configuration, performance, standard, etc. of a sensor included in the electronic device.

Meanwhile, in the above example (Q _{slotframe =} Q _sensing + Q _transmission ), when the electronic device 100 is implemented as a simple sensor device, the electronic device 100 transmits data to the relay device 200. Only the amount of energy consumed was considered, but if the electronic device 100 also receives data from the relay device 200, the amount of power consumed by the electronic device 200 to receive data in the form of Q _reception is additionally considered. Of course, it may be considered.

Meanwhile, Q _transmission can be obtained through Equation 2 below.

Here, N _pkt is the number of data packets to be transmitted during the slot frame, and Size _pkt and Size _ack are data sizes of the data packet and Ack, respectively. Further, Q _tx , Q _rx , and Q _idle denote energy (power) consumption per second in the Tx, Rx, and idle states, respectively.

In addition, the electronic device 100 may calculate the amount of power (E _timeslot ) supplied from the relay device 200 to the electronic device 100 for each timeslot. In power transmission, the relay device 200 may wait for TsTxOffset from the beginning of a timeslot and then transmit an RF signal until the timeslot ends. Therefore, E _timeslot can be calculated as in Equation 3 below.

In this case, L _timeslot is the length of the timeslot, E _s is the amount of power supplied per second, h is the energy supply efficiency coefficient, and P _Tx corresponds to the Tx power of the repeater 100.

Also, N _pwrCells may be calculated through Equation 4 below.

는 입력 변수 이상인 최소 정수를 구하기 위한 ceiling function에 해당한다.here

corresponds to the ceiling function to find the minimum integer that is greater than or equal to the input variable.

After N _pwrCells is calculated, the number of data cells (N _dataCells ) to be added in the slot frame may also be calculated.

Here, the electronic device 100 may calculate the maximum number of data packets that can be transmitted within one timeslot according to Equation 5 below.

는 입력 변수 이하인 최대 정수를 구하기 위한 floor function에 해당한다.here

corresponds to the floor function for finding the largest integer less than or equal to the input variable.

Also, the electronic device 100 may calculate the number of data cells (N _dataCells ) to be added to the slot frame according to Equation 6 below.

According to the above process, the electronic device 100 transmits a cell assignment request message including L _req (length of slot frame: transmission period of the electronic device 100), N _{pwrCells, and} N _dataCells to the relay device 200. can

When a cell assignment request message is received from the electronic device 100, the relay device 200 may update the slot frame list.

For example, if a slot frame having a length not included in the existing slot frame list is included in the received cell allocation request message, the relay device 200 may add the corresponding slot frame to the slot frame list as a new slot frame. . On the other hand, if the cell allocation request message does not include a slot frame having a length not included in the existing slot frame list, the existing slot frame list is maintained.

For example, the relay device 200 may initially maintain only one slot frame having an identifier of 0 in order to broadcast EB and exchange control packets. Also, a new identifier that increases by 1 each time a new slot frame is added to the slot frame list may be allocated. The slot frame list may include information on an identifier, length, allocated power, and data cell sets (ID, L, SetCells) of each slot frame, and each may be expressed as follows.

ID = [ ID ₍₀₎ , ID ₍₁₎ , ID ₍₂₎ , ... , ID _(i) ]

L = [ L ₍₀₎ , L ₍₁₎ , L ₍₂₎ , ... , L _(i) ]

SetCells = [ Cells ₍₀₎ , Cells ₍₁₎ , Cells ₍₂₎ , ... , Cells _(i) ]

Here, ID _(i) , L _(i) , and Cells _(i) respectively correspond to an identifier for the i+1 th slot frame, a slot frame length, and a set of power and data cells.

Cells _(i) = [ Cell _(i,0) , Cell _(i,1) , Cell _(i,2) , ... , Cell _(i,j) ]

In the above equation, Cell _{(i, j)} represents the j+1 th cell in the i+1 th slot frame that can be expressed as [TO _{(i, j)} , CO _{(i, j)} ]. Here, TO _{(i, j)} and CO _{(i, j)} correspond to the timeslot offset and channel offset of the j+1th cell in the i+1th slot frame, respectively.

Meanwhile, as described above, if a specific cell having a specific ASN is assigned to multiple electronic devices, a cell overlapping problem occurs between the electronic devices.

Accordingly, the relay device 200 may generate a candidate power cell list and a candidate data cell list composed of empty cells by executing the COP algorithm.

The procedure of the COP algorithm according to an embodiment of the present disclosure will be described in detail through Algorithm 1 below.

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1: INITIALIZE L _LCM to 0, numRep to 0, N _partition to 0, index _empty to 0, CellListFlag to FALSE // Initialize variables

2: /*=======Step 1. LCM slotframe creation=======*/

3: L _LCM ← lcm ( L ) // Caculate the length of the LCM slotframe

//n_slotframe is the number of slotframes withing the slotframe list4: FOR each slotframe,

//n _slotframe is the number of slotframes with the slotframe list

5: numRep ← L _LCM /L _(i)

6: FOR each repetition,

//n_cell,i is the number of cells withing the ith slotframe7: FOR each cell,

//n _cell,i is the number of cells with the i th slotframe

8: LCM [TO _(i,j) + numRep * L _(i) ] ← 1

9: ENDFOR

10: ENDFOR

11:ENDFOR

12:/* =======Step 2. Empty timeslot discovery========*/

13: N _partition ← L _LCM / L _req //Caculate the number of partitions in LCM slotframe

14: FOR each partition,

15: LCM _(l) ← extract ( LCM , l*(L _req /L _timeslot ) : (l+1)( L _req / L _timeslot )-1)

16: LCM _overlap ← LCM _{overlap ∪} LCM _(l)

17: ENDFOR

//Search timeslot of empty cells in LCM _overlap 18: FOR each timeslot,

//Search timeslot of empty cells in LCM _overlap

19: IF LCM _overlap [m] = 0

20: TS _empty [index _empty ] ← m

21: ENDIF

22: index _empty ← index _empty + 1

23: ENDFOR

24: /*=======Step 3. Candidate cell list creation=======*/

25: IF size( TS _empty ) ≥ (N _pwrCells + N _dataCells + 2N _extraCells )

26: FOR each empty cell,

27: Cells _pwr [p] ← [ TS _empty [p], rand( Channel )]

28: ENDFOR

29: FOR each empty cell,

30: Cells _data [q] ← [ TS _empty [q], rand( Channel )]

31: ENDFOR

32: CellListFlag ← TRUE

33: ELSE

34: Cells _pwr ← [ ]

35: Cells _data ← [ ]

36: CellListFlag ← FALSE

37: ENDIF

38: RETURN Cells _pwr , Cells _data , CellListFlag

===========================================

In Algorithm 1, the relay device 200 generates a virtual slot frame (ie, LCM slot frame) having the same length as the least common multiple (LCM) of the lengths of all slot frames included in the slot frame list. Also, the relay device 200 searches for an empty cell among all slot frames in the slot frame list by using this.

The procedure of the COP algorithm consists of three steps: (1) LCM slot frame generation, (2) empty timeslot discovery, and (3) candidate cell list generation.

In the first step, the LCM slotframe is created, and in the second step, the LCM slotframe is divided into several partitions and timeslot offsets of empty cells are found in all partitions. Finally, in the third step, a list of candidate power and data cells is generated by referring to timeslot offsets of empty cells.

Referring to the COP algorithm, first, variables (L _LCM , numRep , N _partition , index _empty , CellListFlag, etc.) necessary for generating a candidate power cell/data cell list are initialized.

Here, L _LCM is the length of the LCM slot frame, and numRep is the number of repetitions of each slot frame included in the slot frame list of the repeater 200 within the LCM slot frame.

N _partition is the number of partitions of the LCM slot frame, and means the number of repetitions of the slot frame requested by the electronic device within the LCM slot frame.

index _empty represents indexes of elements included in a timeslot offset set for an empty cell (TS _empty ). And, the Cell List Flag indicates whether the candidate cell list has been successfully generated.

As a first step, the relay device 200 may calculate L _LCM through lcm(), which is a function that outputs the least common multiple (LCM) of input variables. Also, the relay device 200 may generate an LCM slot frame (LCM) composed of (L _LCM /L _timeslot ) cells as shown in the following equation.

LCM =

Here, lcm(l) represents whether the l+1th cell in the LCM slot frame has already been allocated by another electronic device. Here, if the corresponding value is 1, the corresponding cell has already been assigned to another electronic device, and if 0, the corresponding cell has not yet been assigned.

As a second step, the LCM slot frame may be divided into several partitions according to the length of the slot frame requested by the electronic device.

Here, LCM _(l) means the l+1 th partition in the LCM slot frame. And, extract(INPUT, x:y) is a function for extracting elements from the xth column to the yth column according to INPUT.

All partitions overlap to find timeslot offsets of cells with a value of 0 (i.e., LCM _overlap is created). And, TS _empty is created by listing the found timeslot offsets in order.

As a last step, the relay device 200 may compare the number of elements included in TS _empty with the sum of N _pwrCells , N _dataCells , and 2N _extraCells .

The number of elements included in TS _empty can be obtained through size(), a function that counts the number of elements of an input variable. And, N _extraCells- is the number of cells additionally required to generate the candidate cell list.

When the number of elements included in TS _empty is greater than or equal to the above-described sum, the relay device 200 generates a list of candidate power cells and a list of candidate data cells (ie, Cells _pwr , Cells _data ), and Cell List Flag can be set to True.

To perform power transfer before data transfer, within TS _empty , timeslot offsets for candidate power cells may be smaller than timeslot offsets for candidate data cells.

Meanwhile, on the contrary, when the number of elements included in TS _empty is smaller than the above-described sum, the relay device 200 may empty both lists and then set CellListFlag to FALSE.

Within a given channel list (Channel), channel offsets for cells are randomly selected. Then, this algorithm returns to Cells _pwr , Cells _data , and CellListFlag.

After executing the COP algorithm, the relay device 200 checks the CellListFlag.

If TRUE, the relay device 200 transmits a cell allocation response message including the selected candidate power cell and candidate data cell to the electronic device.

Upon receiving the cell assignment response message, the electronic device randomly selects necessary power cells and data cells from among candidate power cells and candidate data cells, and transmits a cell assignment confirmation message including the selected cells to the relay device 200 .

In this case, the electronic device 200 may select as many power cells and data cells as necessary (N _pwrCells , N _dataCells ) previously estimated.

Meanwhile, in case of FALSE, the relay device 200 may transmit a cell assignment response message including an empty candidate cell list to the electronic device. In this case, the electronic device may determine that cell allocation has failed.

7 is a block diagram for explaining configurations of an electronic device 100 and a relay device 200 according to an embodiment of the present disclosure.

Referring to FIG. 7 , the electronic device 100 may include a communication unit 110 and a processor 120.

The communication unit 110 is a component for the electronic device 100 to communicate with at least one external device. Also, the communication unit 110 is a component for the electronic device 100 to receive power from at least one external device.

Specifically, the processor 120 may communicate with the relay device 200 through the communication unit 110, and receive an RF signal for wirelessly receiving power from the relay device 200 through the communication unit 200. can do.

To this end, the communication unit 110 may include a TS-SWIPT type receiver, and may periodically switch an antenna between an energy supply circuit and an information decoding circuit to obtain information in a time division manner while receiving energy. have.

The processor 120 controls overall operations of the electronic device 100 .

To this end, the processor 120 may include a central processing unit (CPU), a graphic processing unit (GPU), a neural processing unit (NPU), and the like in terms of hardware, and may include other components included in the electronic device 100. Control-related calculations and data processing can be executed.

The processor 120 may be implemented as a micro processing unit (MPU), or may correspond to a computer having random access memory (RAM) and read only memory (ROM) connected to a CPU and the like through a system bus.

The processor 120 may control not only hardware components included in the electronic device 100, but also one or more software modules included in the electronic device 100, and a result of the processor 120 controlling the software modules is It may also be derived from the operation of hardware components.

The processor 120 may perform the slot frame scheduling method by executing at least one instruction stored in memory.

Specifically, the processor 120 may set the length of the slot frame according to the transmission period of the electronic device 100, and identify the number of cells required for power supply and the number of cells required for data transmission and reception. .

Also, the processor 120 may transmit a cell allocation request including information on the length of the set slot frame to the relay device through the communication unit.

Thereafter, a cell allocation response including information on a first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission/reception is transmitted through the communication unit 110 to the relay device ( 200 to the electronic device 100.

At this time, the processor 120 selects at least one first cell from the first list as many as the number of cells required for power supply, and selects at least one second cell from the second list as many as the number of cells required for data transmission and reception. You can choose.

Also, the processor 120 may transmit cell allocation confirmation including information on the selected first cell and second cell to the relay device 200 through the communication unit 110 .

Meanwhile, although not shown in FIG. 7 , the electronic device 100 may additionally include components such as at least one sensor and a memory for obtaining information on the surrounding environment.

Referring to FIG. 7 , the relay device 200 may include a communication unit 210 and a processor 220.

The relay device 200 may communicate with one or more electronic devices through the communication unit 210 and may output an RF signal for supplying power to one or more electronic devices.

The processor 220 may control various hardware/software components included in the relay device 200, including the communication unit 210.

The processor 220 may perform the slot frame scheduling method by executing at least one instruction stored in the memory of the repeater 200 .

Specifically, the processor 220 receives a cell allocation request including information about the length of a slot frame set according to the transmission period of the electronic device 100 from the electronic device 100 through the communication unit 210. can do.

Also, the processor 220 may identify at least one empty cell not allocated to another electronic device among a plurality of cells included in a slot frame having a set length.

Here, based on the identified at least one cell, the processor 220 may obtain a first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission/reception. have.

Also, the processor 220 may transmit a cell assignment response including information on the first list and the second list to the electronic device 100 through the communication unit 210 .

Subsequently, cell assignment including information about at least one first cell selected by the electronic device 100 in the first list and at least one second cell selected by the electronic device 100 in the second list A response may be received from the electronic device 100 to the relay device 200 through the communication unit 210 .

Meanwhile, in order to evaluate the performance of the TMSS according to the present disclosure, an experimental simulation was performed in an IEEE 802.15.4 physical (PHY) / MAC layer environment.

The effect of TMSS was confirmed by comparing the simulation results of the performance of TMSS with the results of TSCH using a single-slot frame (ie, conventional TSCH). The simulation settings and results are described in detail below.

In this simulation, two simulation scenarios in which the transmission period (TP) of the electronic device is set to be shorter or longer than (or equal to) the length of a slot frame (ie, EB slot frame) used for EB broadcasting and control packet transmission were considered.

In both scenarios, the length of the EB slot frame was set to 2 seconds. Since the timeslot length was set to 10 ms, the number of time slots in the EB slot frame was 200.

In each scenario, three groups of electronic devices are deployed, and the electronic devices in each group have the same transmission period. However, TPs of different lengths were used for each group.

Specifically, in the first scenario (i.e., short-term TP scenario: the TP is shorter than the slot frame length of EB), the TPs of each group are set to 0.5, 1, and 1.5 seconds, and in the second scenario, the TPs of each group are set to 2 and 2.5 seconds. , set to 3 seconds (i.e. long-term TP scenario: scenario where TP is longer than or equal to EB's slot frame length). Each group consists of several electronic devices and one HAP, and the number of electronic devices per group varies in the range [2, 20].

In the simulation, it is assumed that all electronic devices are within communication range of the HAP. The distance (d) between the electronic device and the HAP was arbitrarily set to 1 to 4 m.

The number of data packets to be transmitted from TP to HAP (eg N _pkt ), packet size, and data rate were set to 5, 125 bytes, and 250 kbps, respectively. Accordingly, the number of data cells allocated to each electronic device is five.

Meanwhile, the number of power cells allocated to each electronic device varies according to the TP. The amount of energy consumed in Tx, Rx and idle state (e.g. Q _tx , Q _rx , Q _idle ), Tx power of HAP (P _TX ), path loss parameter (α), efficiency factor (η) are 24.11 mW, respectively; were set at 19.26 mW, 4.67 mW, 100 mW, 2.7 and 0.65.

The performance of TMSS in terms of latency, total throughput and cell utilization was compared with that of conventional TSCH. The cell utilization rate represents the ratio of the number of cells used for energy supply and data transmission to the total number of cells allocated to the sensor device. In the case of the existing TSCH, the slot frame length of electronic devices of all groups is set equal to the EB slot frame length (ie, 2 seconds) regardless of TP.

The number of data packets transmitted to the HAP within the slot frame length is set to [N _pkt /(TP/2)]. The simulation was repeated 200 times and the detailed simulation parameters are listed in Table 1 below.

8a and 8b show the delay performance of TMSS for short-term and long-term TP scenarios, respectively. Delay represents the time it takes to deliver N _pkt of data packets to the HAP.

In both scenarios, since the electronic device is allowed to set the slot frame length equal to the TP, the delay of TMSS is shorter than the TP length of each group regardless of the number of electronic devices per group. Therefore, the TMSS according to the present disclosure has an effect of ensuring timeliness of energy harvesting and data transmission.

On the other hand, in the short-term TP scenario, the legacy TSCH does not guarantee timeliness when the TP is 0.5 second or 1 second.

When the number of electronic devices per group is 8 or more, the waiting time of the existing TSCH is generally longer than that of the TP. This is because some electronic devices wait for the next slot frame to transmit data packets.

In the existing TSCH, most electronic devices use several slot frames when the slot frame length and TP are not the same, whereas all electronic devices executing TMSS according to the present disclosure use one slot frame to transmit data packets use only

Therefore, the TMSS according to the present disclosure shows a shorter delay than the conventional TSCH except when the TP is equal to the EB slot frame length. Quantitatively, TMSS achieved 54.32% and 26.49% shorter delays compared to legacy TSCH in short-term and long-term TP scenarios, respectively.

9A and 9B show the performance change of the total throughput when the number of electronic devices per group is different.

9a and 9b, the total throughput increases because the total number of data packets received by the HAP increases when the TP decreases.

For each TP, the total throughput tends to increase as the number of electronic devices per group increases. However, when the number of electronic devices per group reaches a certain number, the total throughput does not increase any further. This is because the number of electronic devices that have successfully allocated cells (i.e., successful devices) is limited by the number of timeslots in a slot frame.

Table 2 lists the average number of successful devices. where n _dev is the number of sensor devices per group.

In Table 2, when the TP is 0.5 seconds, the number of successful devices is close to 4 even if the number of electronic devices is changed from 4 to 20.

However, the average number of successful devices of TMSS is slightly higher than that of conventional TSCH. When TP is 1.5, 2.5, 3 seconds. On average, the total throughput of TMSS is 0.68% higher than that of conventional TSCH.

10A and 10B show cell utilization of TMSS for short and long TP scenarios.

The cell utilization rate of TMSS is 100% in all scenarios because cells are allocated to slot frames in consideration of the TP of the electronic device.

That is, all cells assigned to the electronic device are used for energy supply or data transmission without exception.

However, the cell utilization of the existing TSCH decreases when the TP is longer than the slot frame length (ie, the EB slot frame length). In particular, in a long-term TP scenario, an electronic device using an existing TSCH needs to add at least two cells to a slot frame for energy supply and data transmission.

In this case, since the allocated data cells are repeated in a shorter slot frame length than the TP, several data cells may not be used for data transmission. Also, even if the electronic device does not transmit data packets in a slot frame, energy supply/collection is periodically performed, and thus unnecessary energy supply/collection may occur. In the long-term TP scenario, the cell utilization of TMSS is 6.44% higher than that of conventional TSCH.

Meanwhile, various embodiments described above may be implemented in a recording medium readable by a computer or a similar device using software, hardware, or a combination thereof.

According to the hardware implementation, the embodiments described in this disclosure are application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), and field programmable gate arrays (FPGAs). ), processors, controllers, micro-controllers, microprocessors, and electrical units for performing other functions.

In some cases, the embodiments described herein may be implemented by a processor itself. According to software implementation, embodiments such as procedures and functions described in this specification may be implemented as separate software modules. Each of the software modules described above may perform one or more functions and operations described herein.

On the other hand, computer instructions or computer programs for performing processing operations in the electronic device 100 according to various embodiments of the present disclosure described above are provided on a non-transitory computer-readable medium can be stored in Computer instructions or computer programs stored in such a non-transitory computer readable medium, when executed by a processor of a specific device, cause the above-described specific device to perform processing operations in the electronic device 100 according to various embodiments.

A non-transitory computer readable medium is a medium that stores data semi-permanently and is readable by a device, not a medium that stores data for a short moment, such as a register, cache, or memory. Specific examples of the non-transitory computer readable media may include CD, DVD, hard disk, Blu-ray disk, USB, memory card, ROM, and the like.

Although the preferred embodiments of the present disclosure have been shown and described above, the present disclosure is not limited to the specific embodiments described above, and is common in the technical field belonging to the present disclosure without departing from the gist of the present disclosure claimed in the claims. Of course, various modifications and implementations are possible by those with knowledge of, and these modifications should not be individually understood from the technical spirit or perspective of the present disclosure.

100, 100-1, 100-2: electronic device
200: relay device

Claims (9)

In the slot frame scheduling method of a relay device included in an Internet of Things (IoT) system in a Simultaneous Wireless Information and Power Transfer (SWIPT) environment,
Receiving a cell allocation request including information about a length of a slot frame set according to a transmission period of the electronic device from the electronic device;
identifying at least one empty cell not allocated to another electronic device among a plurality of cells included in the slot frame having the set length;
obtaining a first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission/reception, based on the identified at least one empty cell;
transmitting a cell assignment response including information on the first list and the second list to the electronic device; and
Cell assignment confirmation including information about at least one first cell selected by the electronic device in the first list and at least one second cell selected by the electronic device in the second list Receiving from the electronic device; including, slot frame scheduling method of the relay device. According to claim 1,
The slot frame scheduling method of the relay device,
supplying power to the electronic device within a timeslot of the first cell among the plurality of cells; and
Transmitting and receiving data with the electronic device within the timeslot of the second cell of the plurality of cells; further comprising, the slot frame scheduling method of the relay device. According to claim 1,
When the slot frame having the set length is not included in the slot frame list, adding the slot frame having the set length to the slot frame list. According to claim 3,
The step of identifying the at least one empty cell,
generating a virtual slot frame having a length corresponding to a least common multiple of lengths of slot frames included in the slot frame list;
Dividing the generated virtual slot frame into a plurality of partitions according to the set length; and
Identifying an empty cell in each of the plurality of partitions; including, slot frame scheduling method of the relay device. According to claim 1,
Receiving the cell assignment request from the electronic device,
Receiving the cell allocation request including information on the number of cells for power supply and the number of cells for data transmission and reception from the electronic device;
Obtaining the first list and the second list,
When the number of identified empty cells is greater than or equal to the sum of the number of cells for power supply, the number of cells for data transmission and reception, and the number of cells for generating candidate lists, the identified empty cells are selected. A method for scheduling slot frames in a relay device, wherein the first list and the second list are obtained by using According to claim 5,
The slot frame scheduling method of the relay device,
If the number of the identified empty cells is less than the sum, identifying that slot frame scheduling has failed. According to claim 1,
Obtaining the first list and the second list,
Selecting a first candidate cell for power supply from among the identified at least one empty cell;
Obtaining the first list including the selected first candidate cell;
Selecting a cell having a larger timeslot offset than the first candidate cell among the identified at least one empty cell as a second candidate cell for data transmission and reception;
The slot frame scheduling method of the relay apparatus obtaining the second list including the selected second candidate cell. In a relay device included in an Internet of Things (IoT) system in a Simultaneous Wireless Information and Power Transfer (SWIPT) environment,
a communication unit configured to communicate with an electronic device and wirelessly supply power to the electronic device; and
Including; a processor connected to the communication unit;
the processor,
Receiving a cell allocation request including information on a length of a slot frame set according to a transmission period of the electronic device from the electronic device through the communication unit;
Identifying at least one empty cell not allocated to another electronic device among a plurality of cells included in the slot frame having the set length;
Based on the identified at least one cell, obtaining a first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission and reception,
Transmitting a cell allocation response including information on the first list and the second list to the electronic device through the communication unit;
The communication unit sends a cell allocation response including information on at least one first cell selected by the electronic device in the first list and at least one second cell selected by the electronic device in the second list. Receiving from the electronic device through, the relay device. In the Internet of Things (IoT) system in a Simultaneous Wireless Information and Power Transfer (SWIPT) environment,
electronic devices; and
A relay device that communicates with the electronic device and wirelessly supplies power to the electronic device;
The electronic device,
The length of the slot frame is set according to the transmission period of the electronic device,
identify the number of cells for power supply and the number of cells for data transmission and reception;
Transmitting a cell allocation request including information on the length of the set slot frame to the relay device;
The relay device,
Identifying at least one empty cell not allocated to another electronic device among a plurality of cells included in the slot frame having the set length;
Based on the identified at least one cell, obtaining a first list including one or more candidate cells for power supply and a second list including one or more candidate cells for data transmission and reception,
Transmitting a cell assignment response including information on the first list and the second list to the electronic device;
The electronic device,
Selecting at least one first cell as many as the number of cells for power supply in the first list, and selecting at least one second cell as many as the number of cells for data transmission and reception in the second list,
A SWIPT environment IoT system that transmits cell allocation confirmation including information on the selected first cell and second cell to the relay device.

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