WO2018034439A1 - Backscatter-dependent communication method for wireless power transmission and backscatter-dependent communication system therefor - Google Patents

Abstract

The present invention relates to: a backscatter-dependent communication method for a wireless power transmission, capable of transmitting/receiving, to/from a sensor node, information through carrier modulation for a wireless signal in an industrial scientific medical (ISM) band used in a conventional communication infrastructure such as Wi-Fi without adding a separate infrastructure, and monitoring the state of the sensor node on the basis of the information and performing wireless power supply; and a backscatter-dependent communication system therefor. A terminal device capable of communicating with a wireless AP of a communication infrastructure, having already been constructed, transmits data and power for communication to the sensor node, and the sensor node can respond by using backscattering through carrier modulation for a wireless signal used between the terminal device and the wireless AP, thereby controlling the sensor node by recognizing the sensor node through the terminal device, and performing control such that wireless power is supplied through the wireless AP to the sensor node recognized through the terminal device.

Description

Backscatter Dependent Communication Method for Wireless Power Transmission and Backscatter Dependent Communication System

The present invention utilizes an existing communication infrastructure without additional infrastructure or charging infrastructure, and communicates with sensor nodes such as sensors, tags, and wearable devices in backscattering, and enables wireless power transmission to the sensor nodes. The present invention relates to a backscatter dependent communication method for wireless power transmission and a backscatter dependent communication system for the same.

As the Internet, which connects computer devices around the world and exchanges information, has been developed and its use is becoming more common, IoT (Internet of Internet), which transmits data through the Internet in real time by attaching sensors to things, Things technology has been proposed.

This Internet of Things (IoT) technology is said to be the next revolution following the Internet revolution, and the IoT device market is growing rapidly recently, reaching about 50 billion units by 2022, an average of 14.9 by 2021. % Growth is expected.

Such IoT devices may be broadly classified into sensor modules for detecting peripheral information, communication modules for transmitting and receiving data, signal processing modules for processing the detected signals and data for transmitting and receiving, and the like. Thus, the configuration may vary.

In addition, wireless communication technologies applied to such IoT devices include radio frequency identification (RFID), Near Field Communicatio (NFC), Zigbee, Bluetooth Low Energy (BLE), Long-Term Evolution (LTE), and Wi-Fi. As technologies are being applied, and these standards have advantages and disadvantages, they may be selectively used depending on IoT services, or two or more communication technologies may be used together.

However, in order to apply such communication technology, a separate infrastructure device (gateway, etc.) is required and additional costs are incurred.

And IoT devices are installed in various places and locations according to the application to monitor and control the surrounding environment, depending on the installed location may be limited by the power supply.

Therefore, the power supply problem of IoT devices is commonly solved by using a battery.

However, since the life of the battery is limited, there is an inconvenience in that the battery needs to be replaced or recharged periodically, and a method for solving such a problem is required.

The present invention is proposed to wirelessly supply power to a sensor node, such as an IoT device, which is difficult to supply by using a built-in communication infrastructure such as a Wi-Fi access point (AP). Without additional infrastructure, information is transmitted and received through carrier modulation on radio signals in ISM (Industrial Scientific Medical) bands used in existing communication infrastructures such as sensor nodes and Wi-Fi, and the state of the sensor nodes is monitored based on the information. The present invention provides a backscatter dependent communication method for wireless power transmission capable of performing wireless power supply and a backscatter dependent communication system for the same.

In addition, the present invention is a terminal device capable of communicating with the wireless AP of the established communication infrastructure transmits power and data for communication to the sensor node, the sensor node is a carrier of the radio signal used between the terminal device and the wireless AP By responsive to backscattering through modulation, the sensor node is controlled through the terminal device to control the sensor node, and the wireless node can supply wireless power to the sensor node recognized through the terminal device through the wireless AP. The present invention provides a backscatter dependent communication method for power transmission and a backscatter dependent communication system for the same.

As a means of solving the above-described problems, the present invention can form a channel with the terminal device to transmit and receive data, check the power and voltage state of the sensor node in accordance with the command from the terminal device, Therefore, a wireless access point (CW) transmitting wireless power in the form of CW (Continous Wave) to a sensor node, a data packet including a predetermined command, and a response waiting field (RWF) packet for a response of the sensor node are transmitted. And a terminal device which decodes a response packet transmitted from the sensor node to collect information from the sensor node or controls the sensor node, and instructs the wireless AP to transmit wireless power to the sensor node, and the wireless AP. It operates by receiving the CW power of the wireless power from the terminal device, receiving and processing the data packet from the terminal device, backscattering It provides a backscatter dependent communication system comprising a sensor node for transmitting the response packet by changing the received signal sensitivity of the RWF packet transmitted from the terminal device through.

In addition, the present invention comprises the steps of the terminal device transmits a response packet (RWF: Packet Waiting Field) to the sensor node for the response of the sensor node and the data packet including a predetermined command; Receiving, by the terminal device, a response packet to the command transmitted by varying the signal sensitivity of the RWF packet through backscattering from the sensor node through the wireless AP; Decoding, by the terminal device, the received response packet; And controlling the terminal device to perform wireless power transfer to the sensor node by instructing the wireless AP to transmit wireless power to the sensor node.

In this case, the sensor node includes a plurality of memory banks in which unique information of the sensor node, a measured value sensed by the sensor unit, and information related to a battery providing power for operating the sensor unit are stored.

In addition, the response packet is a change in the channel state information (CSI) level or the received signal strength indication (RSSI) level of the RWF according to data transmitted by the sensor node, and includes a frame detection field, a starting point detection field, and a data preamble. And a payload including a preamble including a data field and a frame check field.

The data packet transmitted by the terminal device may include a wake-up field for wake-up of the sensor node, a preamble including a sync detection field for finding a data start position, and a data field and a frame check field. The frame detection field includes a payload, and the frame detection field includes information for identifying characteristics of a reference channel, information for packet detection using a change in reception sensitivity of a sensor node, and determination reference information for data determination through RSSI or CSI. The data preamble field may include reference information for data restoration.

In addition, the terminal device and the sensor node, the select state for recognizing one or more sensor nodes, the inventory state for selecting one of the recognized sensor nodes, the information of the selected sensor node An access state controlling wireless power transmission is sequentially performed, and a command according to a current state is transmitted and received through the data packet and the response packet.

Accordingly, the command included in the data packet may include a select command for recognizing one or more sensor nodes existing in a communicable area, a query command for transmitting parameters for preventing collision between multiple sensor nodes, QueryRep. Command, which indicates the reduction of parameters generated by the Query command, QueryAdj. Command to adjust the parameters generated by the Query command, the query command, the query Valid query (Valid_Query) command to select one of the sensor nodes received one of reduction command, query adjustment command, ACK command to confirm that the terminal device and sensor node are connected, and ACK command Validation (Valid_ACK) command that instructs a sensor node that received a response, Read command to read data recorded in the sensor node's memory And it includes one of the WPT (Wireless Power Transmission) command for indicating a write (Write) command, the wireless power transmission control of the sensor node to write data to the memory of the sensor node, or more.

In addition, the present invention provides a communication system comprising a terminal device, a wireless AP and a sensor node, the wireless AP receiving a wireless power transfer command for a specific sensor node from the terminal device; Transmitting, by the wireless AP, a command to start wireless power transfer control to the specific sensor node according to the wireless power transfer command; Receiving, by the wireless AP, static characteristic information about rectifier power and voltage from a sensor node receiving the command; The wireless AP receiving dynamic characteristic information about rectifier power and voltage from the sensor node; And transmitting, by the wireless AP, a control command instructing the start or stop of wireless power transmission to a sensor node according to the static characteristic information and the dynamic characteristic information. do.

The present invention is applied to the field of application services such as IoT, micro sensor industry and environmental monitoring related industry, and is a technology for wirelessly supplying power to control IoT devices, micro sensors, wearable devices that are not easily powered.

In particular, the present invention is a terminal device capable of communicating with the wireless AP of the established communication infrastructure transmits power and data for communication to the sensor node, the sensor node is a carrier wave of the radio signal used between the terminal device and the wireless AP By responsive to backscattering through modulation, the sensor node is controlled through the terminal device to control the sensor node, and by supplying wireless power to the sensor node recognized through the terminal device through the wireless AP. It is possible to communicate with sensor nodes such as IoT devices, micro sensors, wearable devices, and the like, and wirelessly provide power to the sensor nodes by utilizing a communication infrastructure using an existing ISM band without constructing an additional infrastructure.

In addition, the present invention enables the operation of a sensor that can operate at low power (several tens of uW or less), energy collection, and communication without a separate infrastructure for a sensor node such as the IoT device, a micro sensor, and a wearable device. .

1 is a block diagram showing the overall configuration and schematic operation of a backscatter dependent communication system for wireless power transmission according to an embodiment of the present invention.

2 is a diagram illustrating a data transmission method of a downlink in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

3 is a diagram illustrating a data transmission method of an uplink in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

4 is a flowchart illustrating a communication procedure for wireless power transmission in the backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

5 is a diagram illustrating a downlink frame structure of a physical layer in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

6 is a diagram illustrating a detailed structure of a preamble field in a downlink frame in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

7 is a diagram illustrating a detailed structure of a payload of a downlink frame in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

8 is a diagram illustrating an uplink frame structure of a physical layer in a back scanner dependent communication method for wireless power transmission according to an embodiment of the present invention.

9 is a diagram illustrating a detailed structure of a preamble field in an uplink frame in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating a detailed structure of a frame detection field of an uplink frame in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

FIG. 11 is a diagram illustrating a detailed structure of a payload of an uplink frame in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

12 is a diagram illustrating a memory structure of a sensor node for backscatter dependent communication for wireless power transmission according to an embodiment of the present invention.

13 is a diagram illustrating a parasitic communication state for wireless power transmission and an operation state for each parasitic communication state in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

14 is a diagram illustrating a process for obtaining and controlling information of RF wireless power transmission between a wireless AP and a sensor node in a backscatter dependent communication method for wireless power transmission according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS To make the features and advantages of the present invention more clear, the present invention will be described in more detail with reference to specific embodiments shown in the accompanying drawings.

However, in the following description and the accompanying drawings, detailed descriptions of well-known functions or configurations that may obscure the subject matter of the present invention will be omitted. In addition, it should be noted that like elements are denoted by like reference numerals as much as possible throughout the drawings.

The terms or words used in the following description and drawings should not be construed as being limited to the ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms for explaining their own invention in the best way. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention. Therefore, the embodiments described in the present specification and the configuration shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all of the technical ideas of the present invention, and various alternatives may be substituted at the time of the present application. It should be understood that there may be equivalents and variations.

In addition to the terms described above, specific terms used in the following description are provided to help the understanding of the present invention, and the use of the specific terms may be changed into other forms without departing from the technical spirit of the present invention.

Now, a backscatter dependent communication system and method for wireless power transmission according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram showing an overall system configuration for backscatter dependent communication for wireless power transmission according to the present invention.

Referring to FIG. 1, a backscatter dependent communication system for wireless power transmission according to the present invention includes a wireless access point (AP) 100, a terminal device 200, and a sensor node 300.

The wireless AP 100 is a device for relaying wireless connection and data transmission and reception of the terminal device 200 in the established communication infrastructure. The wireless AP 100 may form a channel with the terminal device 200 existing in communication coverage according to a known communication protocol, for example, a Wi-Fi standard, and may transmit / receive data through the formed channel. . In this case, data transmitted and received through the channel conforms to the Wi-Fi standard. The present invention intends to communicate with the sensor node 300 and supply wireless power using the wireless AP 100.

To this end, the wireless AP 100 according to the present invention detects a signal sensitivity change (CSI level or RSSI level) of the response signal transmitted by changing the sensitivity by the back scattering from the sensor node 300 to the terminal device 200. To pass. have. In addition, the wireless AP 100 according to the present invention provides the sensor node 300 with wireless power in the form of CW (Continuous Wave) for wireless power transmission according to a command from the terminal device 200.

The terminal device 200 is a device capable of communicating by occupying a channel of the wireless AP 100 according to an existing communication protocol (for example, Wi-Fi standard), for example, a smartphone, a tablet PC, or the like. It may be the same user terminal device. The present invention can recognize the surrounding sensor node 300 through the terminal device 200, and control the sensor node 300.

To this end, the terminal device 200 according to the present invention is a data packet including a predetermined command to the sensor node 300 in a pulse interval encoding (PIE) scheme and a response wait (RWF) to be used for a response to the data packet. Response Waiting Field) Packet transmission. In addition, the terminal device 200 checks the CSI or RSSI level of the response packet transmitted from the sensor node 300 to backscattering through the wireless AP 100 to decode and process the response packet.

In addition, the terminal device 200 recognizes the adjacent sensor node 300 through the backscatter dependent communication with the sensor node 300, and transmits wireless power to the recognized sensor node 300. Instructs the AP 100.

In the backscatter dependent communication system according to the present invention, the sensor node 300 is a device to which wireless power is transmitted. The sensor node 300 may be a micro device or a portable device which is difficult to supply power, such as a micro sensor device or an IoT device or a wearable device. .

In the present invention, the sensor node 300 decodes and processes the data packet transmitted from the terminal device 200, and waits for a response packet in which the terminal device 200 subsequently transmits the response packet. The sensor node 300 according to the present invention is provided with a Backscatter Communication Unit (BCU) that supports communication in a backscatter fashion without a power supply as a communication module. A smart sensor unit (SSU) including various sensors for sensing environmental information and a BU (Battery Unit) for receiving and charging wireless power transmitted from the wireless AP 100 to provide power for the operation of the SSU. It can be configured to include.

More specifically, the BSC (Backscatter Communication Unit) is a configuration for responding to the data packet transmitted from the terminal device 200 by the carrier through the load modulation, the power source is open to the radio signal from the terminal device 200 Represents a communication module to communicate.

In addition, the smart sensor unit (SSU) refers to various sensors (for example, a temperature sensor and a humidity sensor) attachable to the sensor node 300, and at this time, the amount of power required for each sensor may be different. For this purpose, a separate power supply means is required.

Battery unit (BU) is a configuration for supporting the sensor-specific operating power of the sensor node 300, in particular, refers to a battery and a circuit that is charged by receiving wireless power.

Next, a backscatter dependent communication method for wireless power transmission between the wireless AP 100, the terminal device 200, and the sensor node 300 will be described.

In general, wireless power transmission includes energy harvesting, magnetic induction, or magnetic resonance wireless power transmission in a broad sense, and means wirelessly transmitting power to facilities in a living infrastructure using RF radio waves. The present invention provides a communication procedure for performing wireless power transfer to the sensor node (300).

The overall operation process will be briefly described with reference to FIG. 1. In an initial operation, the terminal device 200 transmits a radio signal and a data packet to the sensor node 300 to wake up and drive the sensor node 300, particularly the BCU. (S100). Thereafter, the sensor node 300 changes its channel to change a channel signal formed between the terminal device 200 and the wireless AP 100 and transmits a response packet to be sent to the terminal device 200. (S200). At this time, the wireless AP 100 receives the response packet transmitted from the sensor node 300 to backscattering, detects a change in the CSI level or the RSSI level, and transmits the change to the terminal device 200. Accordingly, the terminal device 200 may receive information from the sensor node 300 by decoding the response of the sensor node 300. In this case, the information sent by the sensor node 300 may be configured in various ways such as ID information given to the sensor node 300, battery information provided in the sensor node 300, and sensor data detected by the sensor node 300. In addition, the terminal device 200 commands wireless power for the sensor node 300 to the wireless AP 100 while processing the information transmitted from the sensor node 300 (S300).

The wireless AP 100 receives the battery, the voltage of the sensor node 300 itself, information on the remaining battery level, etc. from the sensor node 300 according to the command of the terminal device 200, and based on this, wireless power transmission is performed in real time. Perform and control (S400).

In the backscatter dependent communication method according to the present invention, a downlink for transmitting data from the terminal device 200 to the sensor node 300 and a sensor node 300 for transmitting data to the terminal device 200 are provided. Depending on the uplink, the data transmission scheme is different. Specifically, in the downlink, a pulse interval encoding (PIE) method is used in which a bit value is changed according to a packet length as a modulation method for data transmission, and in the uplink, a received signal according to a bit value is a modulation method for data transmission. A two-level approach is used to vary the sensitivity of. In addition, in the uplink process, when the same data (0 or 1) occurs in succession, a case where the data cannot be distinguished due to the DC offset may occur. Therefore, in the uplink, FMO coding or Miller coding can be used.

This downlink and uplink communication scheme will be described in detail with reference to FIGS. 2 and 3.

2 is a diagram illustrating a downlink communication method for transmitting data from the terminal device 200 to the sensor node 300 in the backscatter dependent communication method for wireless power transmission according to the present invention.

1 and 2, for backscatter dependent communication according to the present invention, the terminal device 200 and the wireless AP 100 should form a communication channel. The communication channel may be established according to an existing communication protocol (eg, Wi-Fi standard).

In addition, the terminal device 200 transmits a data packet, which may be simultaneously received by the wireless AP 100 and the sensor node 300 located near the terminal device 200. As shown in (a) of FIG. 2, the data packet transmitted by the terminal device 200 is coded differently and transmitted according to bit values (0, 1). That is, the packet including the preamble P, the header H, and the payload D represents bit '1', and the packet consisting of the preamble P and the header H represents bit '0'. . Thus, predetermined information 1011 may be transmitted by continuously transmitting packets having different lengths. In FIG. 2, the bit value is changed according to the presence or absence of the payload D. Alternatively, the length of the payload D may be different. That is, all packets transmitted on the downlink are composed of a preamble (P), a header (H), and a payload (D), wherein the length of the payload (D) depends on the bit value (1 or 0). Different.

In this case, the data packet transmitted from the terminal device 200 is a signal of the same band as the carrier of the channel formed in the terminal device 200 and the wireless AP 100, but the structure of the data frame is different. The structure of the data frame will be described later.

In the downlink data packet shown in FIG. 2A, FIG. 2B transmits the same carrier signal.

The sensor node 300 operates by obtaining energy from the data packet of the terminal device 200 transmitted as described above, and then decodes the length of the received data packet to transmit the information (or command) sent by the terminal device 200. Interpret Meanwhile, the wireless AP 100 may receive the data packet transmitted by the terminal device 200, but since the frame format is different, the wireless AP 100 ignores the data packet.

3 is a diagram illustrating a data transmission method of an uplink in which a sensor node 300 transmits data to a terminal device 200 in a backscatter communication method for wireless power transmission according to the present invention.

1 and 3, when the sensor node 300 wants to transmit data (response packet) to the terminal device 200, the relay of the wireless AP 100 is read to read the information of the sensor node 300. Required.

That is, for downlink communication, the terminal device 200 transmits a meaningless response waiting (RWF) packet to the sensor node 300 for a response.

The sensitivity change of the received signal of the wireless AP 100 is confirmed by the backscattering of the sensor node 300 through the generated channel with the wireless AP 100. The sensitivity change of the received signal is measured through a change in a received signal strength indicator (RSSI) or a channel state information (CSI).

This is because the sensor node 300 receives a channel between the terminal device 200 and the wireless AP 100 through backscattering when transmitting a continuous packet (RWF) transmitted by the terminal device 200 without directly active communication. This is because information is transmitted by changing the sensitivity of the signal.

That is, when the terminal device 200 transmits a meaningless data packet (referred to as a response waiting field (RWF) packet) as shown in FIG. 3A, the sensor node 300 backscatters at this time. Through the change of the received signal sensitivity of the RWF packet to a kind of Amplitude Shift Keying (ASK) method, which is represented by a change in the CSI level or RSSI level for the RWF packet received from the wireless AP (100).

3B illustrates an RWF packet whose received signal sensitivity is changed by the sensor node 300 in a backscattering manner.

Therefore, the wireless AP 100 measures the received signal sensitivity of the RWF packet transmitted from the terminal device 200 at the CIS level or the RSSI level and transmits the received signal sensitivity to the terminal device 200.

Accordingly, the terminal device 200 decodes information to be sent by the sensor node 300 according to the received signal sensitivity confirmed by the wireless AP 100. For example, when the reception sensitivity is better than the reference sensitivity, it may be decoded as '1' and in case of bad reception, '0'. In addition, as shown in (b) of FIG. 3, each packet may be decoded into '101', '010', ..., etc. according to reception sensitivity.

4 is a diagram illustrating data flow according to downlink and uplink between a wireless AP 100, a terminal device 200, and a sensor node 300 in a backscattering dependent communication method for wireless power transmission according to the present invention. to be.

Referring to FIG. 4, in backscattering dependent communication for wireless power transmission according to the present invention, during a downlink period, the terminal device 200 wakes up and recognizes a neighboring sensor node 300 (CMD). Send a data packet containing the command. In this case, the terminal device 200 sends a packet consisting of a preamble + header + data payload (P + H + D) when sending '1' and a preamble + header (P + H) when sending '0'. Send a packet. In another example, the terminal device 200 sends a packet consisting of a preamble + header + long data payload (P + H + D1) when sending '1' and a preamble + header + short when sending '0'. Send a packet of length data payload (P + H + D2). That is, the terminal device 200 encodes and transmits data through a type of pulse interval encoding (PIE).

At this time, the sensor node 300 detects the energy level by receiving the data packet, and is activated accordingly to decode the command sent from the terminal device 200 by measuring the length of the received packet (CMD decoding). Meanwhile, since the wireless AP 100 is similar to the existing Wi-Fi packet of the data packet, the wireless AP 100 may receive the same, but accepts bit information in the packet without meaning.

Following the downlink period described above, the sensor node 300 operates in an uplink period for sending a response packet.

In the uplink period, the terminal device 200 transmits a meaningless response waiting (RWF) packet for the response of the sensor node 300. The RWF packet consists only of a preamble and a header (P + H). In this case, the sensor node 300 decodes the RWF packet as 000..000, and recognizes an uplink period.

At the same time, the sensor node 300 performs backscattering according to the information (101010 ... 101010) that it wants to send to the terminal device 200, thereby changing the received signal sensitivity of the RWF packet.

During the uplink period, the wireless AP 100 may receive an RWF packet transmitted from the terminal device 200, wherein the RWF packet is changed by a backscatter of the sensor node 300 to change the signal level. Is received.

Accordingly, during the uplink period, the wireless AP 100 detects a change in the received signal sensitivity due to backscattering of the sensor node 300 with respect to the RWF packet.

Next, it operates in a second uplink period of transmitting data from the wireless AP 100 to the terminal device 200.

In the second uplink period, the wireless AP 100 transmits the detected change in the received signal sensitivity to the terminal device 200 as a response by the sensor node 300, and the terminal device 200 receives the received signal. The response of the sensor node 300 is decoded according to the sensitivity change, and the information sent from the sensor node 300 is confirmed.

Following the second uplink period, a second downlink period in which the terminal device 200 commands wireless power transmission to the wireless AP 100 is performed.

In the second downlink period, the terminal device 200 transmits a command (WPT command) for instructing wireless power transmission to the wireless AP 100 through a previously generated channel, and the wireless AP 100 receiving the same The state of the sensor node 300 is checked and wireless power transmission is performed accordingly.

Next, the frame structure of the data packet transmitted in the downlink and uplink described above will be described with reference to FIGS. 5 to 11.

5 is a diagram illustrating a downlink frame structure of a physical layer in wireless power transmission according to the present invention.

Referring to FIG. 5, the downlink frame includes, for example, an 8-bit preamble and a payload of 0 to 260 bits. Here, the payload is composed of a data field of 0 to 255 bits and a frame check sequence field of 5 bits. The downlink frame is transmitted and received from the most significant bit (MSB). For reference, in backscatter dependent communication, the Quasi-static Guarantee ratio (= payload / data rate), which is used as a measure for maintaining a stable channel, is 0.0128. Accordingly, at a 30 kbps data rate, about 320 payloads Since possible, it is desirable to configure the payload to 256 or less.

In the downlink frame, the preamble consists of 8 bits as shown in FIG. 6, and consists of four bits '1111 ₂ ' and four bits '0000 ₂ '. The first four bits of the preamble are used as a wake-up signal for waking and operating the sensor node 300, and the next four bits are used as a synchronization signal (Sync_finder) to find a data start position.

The payload of the downlink frame is composed of a data field to be transmitted and a frame check sequence (FCS) field for checking an error thereof, as shown in FIG. 7, but the frame check sequence is not included when the length of the data field is zero. . Therefore, the payload length is from 0 bits up to 260 bits.

The frame check sequence field may be generated using, for example, a 5-bit Cyclic Redundancy Code (CRC), and is generated by calculating a data field.

In performing the downlink communication based on the above-described frame structure, the sensor node 300 should be activated by the preamble of the downlink packet, and the power requirement required by each sensor node 300 may be different. To this end, the present invention allows the sensor node 300 to continuously transmit the preamble variably until the sensor node 300 is activated to transmit a response signal. In this case, the number of repetitive dispatches of the preamble for wakeup of the sensor node 300 varies depending on the sensor node 300.

8 is a diagram illustrating a frame structure for uplink communication in the backscattering communication method for wireless power transmission according to the present invention.

Referring to FIG. 8, the uplink frame is composed of preambles and payloads as in the downlink frame.

Unlike the downlink frame, however, the preamble of the uplink frame includes a frame detection field, a starting point finder field, and a data preamble field, and the payload is the same as the data. Field and frame check sequence field. Similarly, the uplink frame is transmitted and received from the most significant bit (MSB).

The preamble and payload of the uplink frame of the above-described structure are transmitted using impedance modulation after two-level signal conversion.

In the uplink frame, the preamble includes a 12-bit frame detection field, an 8-bit starting point finder field, and an 8-bit data preamble field as shown in FIG. Is done. Since the preamble is transmitted from the MSB, the MSB of the frame detection field is transmitted first and the least significant bit (LSB) of the data preamble is transmitted last.

As illustrated in FIG. 10, the frame detection field includes two bits 00 ₂ , eight bits AA _h , and two bits 10 ₂ . The first two bits of the frame detection field are used for the purpose of identifying reference channel characteristics. The eight bits 10101010 following the first two bits are used for the purpose of detecting a packet by using the channel reception sensitivity change of the sensor node 300 (a level difference between 0 bits and 1 bit in a 2 level change). The next two bits are used as criterion for data determination according to the RSSI or CSI level.

Next, among the preambles of the uplink frame, the starting point finder field is composed of 8 bits B0 _h (1011_0000), as shown in FIG. 9, to determine the criterion of the last two bits defined in the frame detection field. Data (0 or 1) is determined using criterion. The determined starting point detection section is used for the purpose of detecting the starting position of the frame using the correlator.

Finally, the data preamble field of the preamble of the uplink frame is represented by eight bits (AA _{h in} the case of 2-level) according to the modulation method of the sensor node 300, and is referred to when restoring data. Used as a reference data. When reconstructing, data for each level is stored using a reference signal, and then the received data is reconstructed by comparing the payload data with each stored level.

11 is a diagram illustrating a detailed structure of a payload in an uplink frame in a backscattering dependent communication method for wireless power transmission according to the present invention.

Referring to FIG. 11, a payload of an uplink frame includes a data field to be transmitted and a frame check sequence (FCS) field for checking an error thereof. If the length of the data is zero, the frame check sequence is not included. Therefore, the payload length is from 0 bits up to 260 bits.

The data field is a section in which data to be transmitted is transmitted, from 0 bit up to 255 bits.

The frame check sequence field is generated using a 5-bit Cyclic Redundancy Code (CRC). The frame check sequence is calculated for the data field and is not generated if the length of the data field is zero. The frame check sequence is calculated according to the definition in Table 1 below, for example, and then sent back after the data by converting it back to 1's complement.

CRC type Length Polynomial Initial value Surplus value - 5 bits (packets) x ⁵ + x ³ +1 01001 ₂ 00000 ₂

Next, FIG. 12 is a diagram illustrating a memory structure of a sensor node 300 for backscattering dependent communication according to the present invention.

Referring to FIG. 12, the sensor node 300 according to the present invention has a memory bank including battery information for wireless power transmission.

Specifically, the sensor node 300 is composed of four memory banks (bank 11 bank 10, bank 01, bank 00). Each memory bank consists of up to 96 bits. This is to store information that can be carried in the data field except for 128 bits because 16 bits are used as preambles and 16 bits are used as CRC when the response packet transmitted on the uplink is composed of 128 bits.

In the sensor node 300, the main information related to the battery and power supply circuit of the BU is stored in the memory bank Bank 11 as the WPT information related to the wireless power transmission.

The unique identification information (ID information) of the sensor node 300 is stored in the memory bank Bank 10.

When a sensor is provided at the sensor node 300, the measured value of SSU is stored in the memory bank Bank 01. That is, when measurement sensors capable of measuring temperature, humidity, or illuminance are added, the memory bank area of the sensor node 300 is used to access and control them.

The remaining memory bank Bank 00 is a reserved future used (RFU), and may be used for recording other required information in addition to the above-described information.

The sensor node 300 may write data in a specific memory bank or read and transmit data of a specific memory bank according to a command included in a data packet transmitted from the terminal device 200.

In the backscatter dependent communication method for wireless power transmission according to the present invention, the terminal device 200 performs three basic operations to recognize and manage a plurality of sensor nodes 300, and is used for each step. Instructions are constructed.

13 is a diagram illustrating a procedure for recognizing and managing a plurality of sensor nodes 300 in the backscatter communication method for wireless power transmission according to the present invention.

In the backscatter dependent communication method for wireless power transmission according to the present invention, a basic operation step of the terminal device 200 for managing the sensor node 300 includes a select step, an inventory step, and an access. ).

The select step is a step for the terminal device 200 to recognize a plurality of sensor nodes 300 present in the periphery, and the inventory step is one sensor node 300 of the plurality of sensor nodes 300 recognized through the select step. ), And the access step is to grasp the information of the selected sensor node 300 and actively control the wireless power transmission.

(A) of FIG. 13 shows an operation process in a Select step, (b) shows an operation process of an Inventory step, and (c) shows an operation process of an Access step.

In the three operation stages, the downlink / uplink communication described above is performed, and in the access stage, the battery and state information of the selected sensor node 300 is continuously monitored, and accordingly, the wireless AP 100 is CW-type. RF wireless power transmission is performed.

In detail, in the selecting step, when there are a plurality of sensor nodes 300, the terminal device 200 selects a plurality of sensor nodes 300 under the control right of the user to select a single sensor node 300. Check it. At this time, as shown in FIG. 13A, the terminal device 200 transmits a select command to the surrounding sensor nodes 300 to recognize at least one sensor node 300 that can communicate therewith. .

The Select command is defined as shown in Table 2, and transmits a value corresponding to the target register of the sensor node 300 divided into S0 to S3 and SL so that the corresponding sensor node 300 responds. to be.

Select CMD Command Target Action CRC # of bits 4 3 2 16 Description 0000 000: Inventoried (S0) 001: Inventoried (S1) 010: Inventoried (S2) 011: Inventoried (s3) 100: SL101: RFU110: RFU111: RFU 00: assert SL01: deassert SL10: do nothing11: negate SL CRC-16

In Table 2, Target refers to grouping information of the sensor node 300 for giving a command to the sensor node 300 divided into S0 to S3 and SL.

Action is a field that defines an action regarding whether to give a command to the sensor node 300 specified in the target in a state recognized by the terminal device 200 or to select a new sensor node 200.

CRC16 is a field for recording a test sequence, and the polynomial X ¹⁶ + X ¹² + X ⁵ + 1 for calculating CRC 16 is applied mutatis mutandis by the international standard ITU. The terminal device 200 applies the 16-bit polynomial to the data block to be transmitted, and adds the resulting code to the block. The sensor node 300 applies the same polynomial to the data and compares the result with the result sent from the terminal device 200. If the two match, the data has been successfully received.

In the inventory step, the terminal device 200 selects only one sensor node 300 by performing an inventory round on the plurality of sensor nodes 300 recognized in the select step. In this case, the terminal device 200 uses an anti-collision algorithm to select only one sensor node 300 from among the plurality of selected sensor nodes 300.

That is, as shown in (b) of FIG. 13, the query series command (Query / QueryRep. / QueryAdj.) Is transmitted, and the sensor node 300 receiving the command transmits a valid response, and for authentication therefor, The terminal device 200 selects one sensor node 300 by transmitting an acknowledgment command to the sensor node 300 that has transmitted a valid response.

The above-described command (Query / QueryRep. / QueryAdj.) Of the Query series will be described in detail.

First, the query command (Query CMD) is a command that can prevent a collision when a plurality of sensor nodes 300 exist. The anti-collision algorithm uses a specific parameter (Q value) generated by a random number. However, since the present invention assumes a command to a single sensor node 300, the parameter (Q value) is fixed to 0. The query command (Query CMD) may be defined as shown in Table 3 below. That is, the terminal device 200 transmits a parameter (Q value) between 0 and 15 to the sensor node 300 through a query command, and the parameter (Q value) of the sensor node 300 that receives the command is changed. The sensor node 300 which becomes 0 transmits a valid response (Valid_Query).

Query CMD Command Sel Session Q CRC # of bits 4 2 2 4 5 description 0001 00: All01: All10: ~ SL11: SL 00: S001: S110: S211: S3 0-15 CRC-5

In Table 3, Sel is a field for selecting a sensor node 300 to transmit the query command, and the sensor node 300 or all the sensor nodes 300 selected in the terminal device 200 can be selected. have.

Session is a command field for selecting five register groups S0 to S3 and SL among the sensor nodes 300.

Q is a parameter generated by the random number in the terminal device 200 and is transmitted to the plurality of sensor nodes 300. The plurality of sensor nodes 300 may generate a unique random number for each sensor node 300 of 2 ^Q by using the received parameter (Q value), and may use the collision prevention algorithm.

The query reduction command QueryRep. Is a command used to identify a specific sensor node 300 among sensor nodes 300 that have received a query command for a collision avoidance algorithm. The plurality of sensor nodes 300 that have received the Q value from the query command generate a random number and have a unique value corresponding to the 2 ^Q value, among which the sensor node 300 whose unique value is 0. Responds to the query reduction command QueryRep. At this time, the sensor node 300, which has received the query reduction command (QueryRep.) Command, continuously decreases the Q value that it has, and accordingly, when the Q value that it has becomes 0, the terminal receives Valid_Query in response. The device 200 transmits the status to the next step. The query reduction command may be defined as shown in Table 4.

QueryRep. CMD Command Session # of bits 4 2 description 0010 00: S001: S110: S211: S3

In Table 4, Session is a command field for selecting the sensor node 300 currently selected in the terminal device 200 or all the sensor nodes 300 recognized in the periphery, and is unique to the sensor node 300. Specify the register group whose Q value you want to decrease.

Next, the QueryAdj. Command is another command used for the collision avoidance algorithm. A plurality of sensor nodes 300 received Q values from a query command generate random numbers to form unique values corresponding to 2 ^Q values. The query adjustment command is selected by a query command. This command is used to adjust the Q value, which is the random number generation value of a group. As the Q value increases, the collision rate between the plurality of sensor nodes 300 decreases, and in theory, communication with the plurality of 63,488 sensor nodes 300 is possible. Query tuning commands can be defined as shown in Table 5. The sensor node 300 transmits Valid_Query when the Q value becomes 0 after receiving the corresponding query adjustment command.

QueryAdj. CMD Command Session UpDn # of bits 4 2 3 description 0011 00: S001: S110: S211: S3 110: Q = Q + 1000: No Change to Q011: Q = Q-1

Session in Table 5 is a command field for specifying five register groups S0 to S3 and SL of the sensor node 300.

UpDn is a command field for indicating how to adjust the unique Q value of the sensor node 300. UpDn is a command field for increasing the Q value by 1, not changing the Q value, or decreasing the Q value by 1. Can be.

Valid_Query, which is a response signal, is a response signal transmitted by the sensor node 300 whose Q value inherent to the sensor node 300 is zero among the sensor nodes 300 that receive Query-related commands Query / QueryRep. / QueryAdj. The RWF packet transmitted by the terminal device 200 is modulated by using load modulation to inform the terminal device 200 that the user is selected. Valid_Query may be defined, as shown in Table 6. The Valid_Query response is set to a specific response signal 01010011 of an unusual type that cannot be detected in a normal channel, and is left as a packet that does not respond to the remaining 120 bits.

Valid_Query Reply_Query Null # of bits 8 120 Description 01010011: Query Reply 120'h0

Next, the confirmation command (ACK), which is defined as shown in Table 7, is a command for finally confirming that the terminal device 200 and the sensor node 300 are connected, and the sensor node 300 that does not receive the ACK command during communication. ) Does not proceed to the next step (Access), it returns to the initial step and waits for another command. In response to the ACK command, the sensor node 300 transmits Valid_Ack to the terminal device 200.

Ack CMD Command Ack number # of bits 4 16 Description 0100 16'h0ACC

In Table 7, the Ack Number included in the ACK command is an acknowledgment number, and the terminal device 200 and one sensor node 300 finally receive each other by transmitting a signal having various forms and transmitting the same ACK number in the response. Command field to check.

The only sensor node 300 receiving the ACK command responds to the terminal device 200 with a Valid-Ack including a value equal to 16'0ACC, which is an Ack Number received through the ACK command, to the terminal device 200 and the next step (Access). Wait for step). At this time, the Valid_Ack response, which is a response signal, is defined as shown in Table 8 and transmits the Ack Number 16'h0ACC received as an ACK command to the terminal device 200 through the Reply_Ack field. At this time, the remaining 112 bits of the response packet were left as unresponsive packets.

Valid_Ack Reply_Ack Null # of bits 16 112 Description 16'h0ACC 112'h0

One sensor node 300 and the terminal device 200 finally confirmed by the above proceeds to the Access step.

The access step is to perform various operations for controlling or collecting information on the sensor node 300 selected in the inventory step. Commands transmitted in the access phase are largely divided into a read command (Read) for reading the memory value of the sensor node 300, a write command (Write) for recording specific information in the memory value, and a WPT command for instructing wireless power transfer. do.

The read command is a command for reading a value (WPT information, sensor node ID information, measurement data information of a sensor connected to the sensor node, etc.) existing in the memory inside the sensor node 300 from the terminal device 200. The full command field is defined as shown in Table 9. The read reply to the read command is transmitted to the STA by using the RWF, and responds using all 128 bits. A response to a read command may be defined as shown in Table 10.

Read CMD Command Membank Ack number CRC # of bits 4 2 16 16 description 0101 00: Reserved01: SSN ID10: SSU ID11: WPT ID 16'h0ACC CRC-16

Read Reply Ack number Memory ID CRC # of bits 16 96 16 description 16’h0ACC Data CRC-16

In Table 9, MemBank is a command field that specifically selects a memory bank (WPT information, sensor node ID information, measurement data information of a sensor connected to a sensor node, etc.) to read 96 bits, and in Table 9 and Table 10, Ack Number is an acknowledgment number that is a command field for confirming that it is a response of the sensor node 300 that has received a corresponding read command by transmitting a signal having many types and receiving the same response. Therefore, when transmitting the response to the read command, the sensor node 300 includes the Ack Number included in the read command.

The write command is a command for writing predetermined data (WPT information, sensor node ID information, measurement data information of a sensor connected to the sensor node, etc.) in the memory inside the sensor node 300 in the terminal device 200. . The entire command field of the write command is defined as shown in Table 11. The corresponding write command transmits a 48-bit Write Reply to the terminal device 200 in response to the success or failure. Command fields for Write Reply are defined in Table 12.

Write CMD Command Membank WordPtr Data Ack number CRC # of bits 4 2 16 16 16 16 description 0110 00: Reserved01: SSN ID10: SSU ID11: WPT ID AddressPointer Ack Numberⓧword written 16’h0ACC CRC-16

Write Reply Ack number Write Success CRC # of bits 16 16 16 description 16’h0ACC Writing Data CRC-16

In Table 11, MemBank is a command field that specifically selects a memory bank (WPT information, sensor node information, measurement data information of a sensor connected to a sensor node, etc.) to input data (16 bits), and WordPtr is a selected memory bank. This field is used to select a position to input data into a memory bank in order to write data in Word (16 bits). 00 _h indicates the first 16-bit word, 01 _h indicates the second 16-bit word, and consists of the entire 0F _h .

Data is an instruction field for recording data to be recorded, and records 16-bit data obtained by Ack Number and Exclusive OR processing for encryption.

The Ack Number is an acknowledgment number, which is a command field for confirming that the terminal device 200 is connected to one sensor node 300 by transmitting a signal having many variations and receiving the same response.

In Table 12, Write Success is a command field for verifying validity of data received by transmitting a value obtained by encrypting a 16-bit response to the Write command to the terminal device 200 by decrypting the received data.

The terminal device 200 that recognizes the sensor node 300 through the above command may instruct the wireless AP 100 to transmit wireless power to the recognized sensor node 300. The AP 100 monitors the state of the sensor node 300 to perform wireless power transmission.

In the wireless power transmission according to the present invention, the wireless charging network between the wireless AP 100 and the plurality of sensor nodes 300 has a star topology structure. The wireless AP 100 exchanges data with the sensor node 300 in real time to determine an operation point and allocates resources. Each sensor node 300 transmits its own information (battery and power related information) to the wireless AP 100 and receives a control message from the wireless AP 100.

The wireless AP 100 generates and maintains a wireless charging network. In the wireless charging state, the wireless AP 100 sets the timing and the order of wireless power transmission with the plurality of sensor nodes 300.

Wireless power transfer control at the wireless AP 100 protects the sensor node 300 from over-voltage, the rectified voltage output of the sensor node 300 is less than the maximum rectified voltage, is greater than the minimum desired rectified voltage In this case, the power efficiency used or the overall system efficiency may be maximized.

14 is a diagram illustrating an information acquisition and control process performed for wireless power transmission between the wireless AP 100 and the sensor node 300 in the backscattering dependent communication method for wireless power transmission according to the present invention.

As described above, the wireless power transmission according to the present invention starts by recognizing the sensor node 300 by performing the Select step and the Inventory step for the plurality of sensor nodes 300. Through this process, the ID values of the sensor nodes 300 are recognized to ensure an independent communication channel during communication for each sensor node 300.

Thereafter, the wireless AP 100 checks whether each device node 300 is a device capable of transmitting wireless power through a WPT command (S401). The transmission power is determined based on the information of the sensor node 300 obtained through the connection process, and the determined transmission power is transmitted. The BCU status of the sensor node 300 is monitored through the Read command continuously during the transmission process.

First, the sensor node 300 receiving the WPT command continuously collects state information about its BCU, that is, static and dynamic characteristic information of the battery and load, and transmits it to the wireless AP 100, and accordingly, the wireless AP 100. Controls the RF wireless power transmission in real time.

The WPT command, after recognizing a plurality of sensor nodes 300 in the terminal device 200 commands a wireless power transmission to the wireless AP 100, the wireless AP 100 is wireless power transmission to the sensor node 300. Command to indicate the start of.

Subsequently, transmission and reception of information (dynamic characteristic information and static characteristic information) necessary for wireless power transmission between the wireless AP 100 and the sensor node 300 and the response of the characteristic information sent from the sensor node 300 by the wireless AP 100. Is transmitted (S402 to S406), and the wireless AP 100 transmits a wireless power transfer control command (SSN control command) based on the collected information (S407).

Upon receiving the SSN control command, the sensor node 300 transmits a response to the wireless AP 100 (S408).

Thereafter, steps S409 to S412 are performed by repeating the processes of S402 to S408 again, through which wireless power transmission and control for the sensor node 300 is continuously performed.

The entire command field of the command for wireless power transmission is defined as shown in Table 13, and the WPT subcommand described in the WPT CMD classification field is shown in Table 14.

WPT CMD WPT Command WPT CMD Classification Ack number # of bits 4 4 16 description 0111 0001 16’h0ACC

WPT Sub CMD Code Length (Bits) WPT 0001 24 SSN control 0010 28 Reply of SSN control 0011 24 SSN static parameter 0100 56 SSN dynamic parameter 0101 80

The SSN control command is a command for instructing power transmission start, stop, and the like for wireless power transmission from the wireless AP 100 to the sensor node 300. After receiving the static and dynamic information of the sensor node 300 continuously, the wireless AP 100 controls the wireless power transmission in real time through the SSN control command based on this. The fields of the SSN Control command are defined as shown in Table 15, and the detailed WPT allowance fields are defined as shown in Table 16. In addition, the response to the SSN control command is shown in Table 17.

SSN control CMD WPT Command WPT CMD Classification WPT allowed Ack number # of bits 4 4 4 16 description 0111 0010 See Table 16 16’h0ACC

3 2 One 0 Allow SSN output Allow SSN Charging Output adjustment command 1 = allowed 0 = not allowed 1 = allowed 0 = not allowed 00 = maximum power (23 dBm) 01 = 66% * maximum power 10 = 33% * maximum power 11 = RFU

In Table 15, the WPT allowance field refers to a field for notifying the sensor node 300 to receive information for wireless power transmission from the wireless AP 100 to the sensor node 300.

As shown in Table 16, SSN out allow, SSN charge allow, and output adjustment commands may be indicated.

In Table 16, SSN output permission refers to a field for allowing output information to receive the current battery and output status of the sensor node 300 in the wireless AP 100.

The SSN charging allowance refers to a field for the actual wireless AP 100 to command the sensor node 300 to continue, resume, and the like.

The output adjustment command refers to a field for controlling the output of the wireless power transmission of the current wireless AP 100 based on the static and dynamic information received from the sensor node 300.

Reply of SSN control Ack number Command WPT CMD Classification # of bits 16 4 4 description 16’h0ACC 0011 0011

The response defined in Table 17 is transmitted from the sensor node 300 receiving the SSN control command to the wireless AP 100 in step S408, and includes the Ack Number and WPT CMD classification fields included in the received SSN control command. do.

In step S402, the static characteristic information of the sensor node 300 is transmitted to the wireless AP 100, and information about the rectifier power and voltage of the sensor node 300 is transmitted. In this case, the static characteristic information may be transmitted through a command field structure as shown in Table 18.

SSN static parameter CMD WPT Command WPT CMD Classification Rectifier maximum power Rectifier Minimum Constant Voltage Rectifier maximum constant voltage Rectifier Desired Constant Voltage Ack number # of bits 4 4 8 8 8 8 16 description 0111 0100 0-255 0-255 0-255 0-255 16’h0ACC

Here, the rectifier maximum power represents the maximum rectified power allowable in the rectifier of the sensor node 300, the rectifier minimum constant voltage represents the minimum rectifier voltage that SSN can allow in the rectifier, and the rectifier maximum constant voltage indicates that the SSN is the self rectifier. Represents the maximum rectified constant voltage allowable at, and the rectifier desired constant voltage represents a desired rectified constant voltage desired by the sensor node, and these may represent bit values of 0 to 255, and may be defined as 1 mW differences per 1 bit.

The step S405 is a step in which the sensor node 300 delivers dynamic characteristic information to the wireless AP 100 and may be transmitted through a command field as shown in Table 19.

SSN dynamic parameter CMD WPT Command WPT CMD Classification Rectifier dynamic voltage Rectifier dynamic current Battery dynamic voltage # of bits 4 4 8 8 8 description 0111 0101 0-255 0-255 0-255 SSN dynamic parameter CMD Battery dynamic current Battery temperature SSN Critical State Rectifier desired minimum voltage Ack number # of bits 8 8 8 8 16 description 0-255 0-255 0-255 0-255 16’h0ACC

At this time, among the dynamic characteristic information transmitted, the rectifier dynamic voltage refers to the dynamic voltage of the sensor node rectifier, expressed as a value of 0 ~ 255mV in mV unit, the rectifier dynamic current means the rectifier dynamic current of the sensor node 300, , and the battery dynamic voltage refers to the dynamic voltage output from the battery terminal of the sensor node 300 in mA units, and is expressed as 0 to 255 mV in mV units, and the battery dynamic current represents the sensor node ( It refers to the dynamic current output from the battery terminal of the 300), expressed as a value of 0 ~ 255mA in mA unit, the battery temperature, refers to the current temperature of the battery of the sensor node 300 to prevent excess current inflow, -40 Expressed as a temperature value in the range of + + 215, SSN dangerous state is a field indicating the dangerous state of the sensor node 300, based on the dynamic and static parameters according to the wireless power transmission, 8 bits The overvoltage, overcurrent, temperature overload, self-charging cutoff, charge completion, wired charge detection, RFU, etc. are displayed, and the desired rectifier minimum voltage refers to the minimum voltage required at the rectifier terminal of the sensor node 300. 0 ~ 255mV in mV unit.

As described above, the specification includes the details of a number of specific implementations, but these should not be understood as being limited to the scope of any invention or claimable, but rather may be specific to a particular embodiment of a particular invention. It should be understood as a description of the features. Certain features that are described in this specification in the context of separate embodiments may be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable subcombination. Furthermore, while the features may operate in a particular combination and may be initially depicted as so claimed, one or more features from the claimed combination may in some cases be excluded from the combination, the claimed combination being a subcombination Or a combination of subcombinations.

Specific embodiments of the subject matter described in this specification have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order but still achieve desirable results. As an example, the process depicted in the accompanying drawings does not necessarily require that particular illustrated or sequential order to obtain desirable results. In certain implementations, multitasking and parallel processing may be advantageous.

The foregoing description presents the best mode of the invention, and provides examples to illustrate the invention and to enable one skilled in the art to make and use the invention. The specification thus produced is not intended to limit the invention to the specific terms presented. Thus, although the present invention has been described in detail with reference to the above examples, those skilled in the art can make modifications, changes and variations to the examples without departing from the scope of the invention.

Therefore, the scope of the present invention should not be defined by the described embodiments, but should be defined by the claims.

The present invention is applied to the field of application services, such as the IoT, micro-sensor industry and environmental monitoring-related industries, to control the power supply of IoT devices, micro-sensors, wearable devices that are not easy to supply power and to supply power wirelessly.

In particular, the present invention is a terminal device capable of communicating with the wireless AP of the established communication infrastructure transmits power and data for communication to the sensor node, the sensor node is a carrier wave of the radio signal used between the terminal device and the wireless AP By responsive to backscattering through modulation, the sensor node is controlled through the terminal device to control the sensor node, and by supplying wireless power to the sensor node recognized through the terminal device through the wireless AP. It is possible to communicate with sensor nodes such as IoT devices, micro sensors, wearable devices, and the like, and wirelessly provide power to the sensor nodes by utilizing a communication infrastructure using an existing ISM band without constructing an additional infrastructure.

In addition, the present invention enables the operation of a sensor that can operate at low power (several tens of uW or less), energy collection, and communication without a separate infrastructure for a sensor node such as the IoT device, a micro sensor, and a wearable device. .

Claims (11)

Form a channel with the terminal device to transmit and receive data, and check the power and voltage state of the sensor node according to the command from the terminal device, and according to the power and voltage state to the sensor node in the form of CW (Continous Wave) A wireless access point (AP) for transmitting wireless power; Sends a response waiting field (RWF) packet for a response of a sensor node and a data packet including a predetermined command, decodes a response packet transmitted from the sensor node to collect information from the sensor node, or A terminal device controlling a node and instructing the wireless AP to transmit wireless power to the sensor node; And Operating by receiving the CW power of the wireless power from the wireless AP, receiving and processing the data packet from the terminal device, and changes the received signal sensitivity of the RWF packet transmitted from the terminal device through backscattering the response packet Backscatter dependent communication system comprising a sensor node for transmitting. In the backscattering dependent communication method for wireless power transmission in a communication system consisting of a terminal device, a wireless AP and a sensor node, Transmitting, by the terminal device, a data packet including a predetermined command and a response waiting field (RWF) packet to the sensor node for a response of the sensor node; Receiving, by the terminal device, a response packet to the command transmitted by varying the signal sensitivity of the RWF packet through backscattering from the sensor node through the wireless AP; Decoding, by the terminal device, the received response packet; Controlling the terminal device to perform wireless power transfer to the sensor node by instructing wireless AP to transmit wireless power to the sensor node; Backscatter dependent communication method for wireless power transmission comprising a. The method of claim 2, wherein the sensor node is A plurality of memory banks for storing unique information of a sensor node, measured values sensed by the sensor unit, and information related to a battery providing a power source for operating the sensor unit. Communication method. The method of claim 2, wherein the response packet, And a channel state information (CSI) level or a received signal strength indication (RSSI) level of the RWF according to data to be transmitted by the sensor node. The method of claim 2, wherein the response packet, A backscatter dependent communication method for wireless power transmission, comprising: a preamble including a frame detection field, a starting point detection field, a data preamble, and a payload including a data field and a frame check field. The method of claim 2, wherein the data packet transmitted by the terminal device A preamble including a wakeup field for wakeup of the sensor node and a sync detection field for finding a data start position; A backscatter dependent communication method for wireless power transmission, comprising: a payload comprising a data field and a frame check field. The method of claim 5, wherein the frame detection field is Information to characterize the reference channel, Information for packet detection using a change in reception sensitivity of a sensor node, and Backscatter dependent communication method for wireless power transmission, characterized in that it comprises decision criteria information for data determination by RSSI or CSI. The method of claim 5, wherein the data preamble field is Backscatter dependent communication method for wireless power transmission, characterized in that it comprises reference information for data recovery. The method of claim 2, The terminal device and the sensor node, Select states for recognizing one or more sensor nodes, Inventory status to select one of the recognized sensor nodes, Wireless power transmission is characterized in that the information of the selected sensor node to sequentially perform the access (Access) to control the wireless power transmission, and transmits and receives a command according to the current state through the data packet and the response packet. Backscatter dependent communication method. The method of claim 2, wherein the data packet, Select instructions for recognizing one or more sensor nodes present in a communicable area, Query command that passes parameters to prevent collision between multiple sensor nodes, QueryRep. Command, which directs the reduction of parameters generated by the Query command, QueryAdj. Command to adjust the parameters generated by the Query command, Valid query (Valid_Query) command for selecting one of the sensor node received one of the query command, query reduction command, query adjustment command, Acknowledgment (ACK) command to confirm that the terminal device and the sensor node is connected, Valid_ACK command that instructs a sensor node that has received an acknowledgment (ACK) command to respond, Read command to read the data recorded in the sensor node's memory, Write command to write data to the sensor node's memory, And at least one of a wireless power transmission (WPT) command for instructing wireless power transfer control of the sensor node. In the backscattering dependent communication method for wireless power transmission in a communication system consisting of a terminal device, a wireless AP and a sensor node, The wireless AP receiving a wireless power transfer command for a specific sensor node from a terminal device; Transmitting, by the wireless AP, a command to start wireless power transfer control to the specific sensor node according to the wireless power transfer command; Receiving, by the wireless AP, static characteristic information about rectifier power and voltage from a sensor node receiving the command; The wireless AP receiving dynamic characteristic information about rectifier power and voltage from the sensor node; And And transmitting, by the wireless AP, a control command indicating a start or stop of wireless power transmission to a sensor node according to the static characteristic information and the dynamic characteristic information. Way.  Dependent communication method.

Images