CN117044070A

CN117044070A - Determining a location of a communication device

Info

Publication number: CN117044070A
Application number: CN202080107187.9A
Authority: CN
Inventors: 布鲁诺·罗伯托·弗朗西斯卡托
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-12-03
Filing date: 2020-12-03
Publication date: 2023-11-10
Also published as: EP4244951A1; WO2022117191A1

Abstract

Embodiments of the present invention relate to determining a location of a communication device (e.g., a UE). By broadcasting a Power-collected (HP) parameter in the control signal, a Line-of-Sight (LoS) signal can be identified and distinguished from multipath signals. Based on the LoS signal, a distance and an angle to the communication device can be determined. The distance and the angle give the position of the communication device. Thus, a single device for determining the location of the communication device may be used to determine the location of the communication device. Thereby reducing cost and complexity, and also improving location accuracy, improving the application of wireless power transfer (Wireless Power Transfer, WPT).

Description

Determining a location of a communication device

Technical Field

Embodiments of the present invention relate to a device for determining the location of a communication device and a wireless power transfer beacon comprising such a device. Furthermore, the embodiment of the invention also relates to a communication device, a corresponding method and a computer program.

Background

In recent years, advances in the development and deployment of internet of things (Internet of Thing, ioT) devices in different markets of industry, consumer electronics, aviation, defense, etc. have been noted. Each market has its own limitations and requirements. However, one common key parameter between these vertical domains is that the deployed devices should have a long battery life, and may even be completely battery-free. Battery replacement costs and environmental impact are the primary reasons for this requirement. One possible solution to the battery problem is to charge the battery or to replace the battery entirely by energy harvesting or energy transfer techniques. In this regard, there are a variety of possible energy sources, such as solar energy, mechanical energy, thermal energy, radio Frequency (RF), and the like.

For wireless energy transfer schemes, one possible application scenario is an indoor environment (e.g., a room) where a user will carry a smartphone into the room, and the smartphone can automatically start charging without any action by the user, such as inserting a data line into the smartphone or placing the smartphone in a particular charging location. Currently, the power required to charge a smart phone can be on the order of 1W. To meet these requirements, wireless power transfer (Wireless Power Transfer, WPT) techniques have been proposed. However, wireless transmission of high power is not easy because high system efficiency is required for high directional antenna beamforming. In addition, when WPT is used, accurate estimation of the position of the object is also required. Thus, the direction in which the object may be positioned and the distance from the object are required.

Disclosure of Invention

It is an aim of embodiments of the present invention to provide a solution that reduces or solves the disadvantages and problems with conventional solutions.

It is another object of embodiments of the present invention to provide a solution with higher positioning accuracy and lower implementation costs than conventional solutions.

The gist of the independent claims is to achieve the above and other objects. Further advantageous embodiments of the invention can be found in the dependent claims.

According to a first aspect of the present invention, the above and other objects are achieved by an apparatus for determining a position of a communication device, the apparatus being adapted to:

broadcasting a wireless power transfer signal;

receiving a set of control signals from the communication device, wherein each control signal comprises a control message indicating an identity of the communication device and a collected power associated with the wireless power transfer signal;

identifying, based on the set of control signals, a line-of-sight signal in the set of control signals;

a location of the communication device is determined based on the identified line-of-sight signal.

The communication device may be a fixed communication device or a mobile communication device.

The wireless power transfer signal may be periodically broadcast so that the location of the communication device can be updated. This is particularly relevant when the communication device is a mobile communication device.

An advantage of the device according to the first aspect is that only a single device is required to determine the position, compared to conventional solutions requiring multiple devices. Thereby reducing complexity and cost. Further, by using the collected power of the communication device as a parameter, the positioning accuracy can be improved as compared with the conventional scheme.

In an implementation form of the device according to the first aspect, each control message further indicates a clock signal associated with the collected power.

This implementation has the advantage that positioning accuracy is further improved, since the identification of the line-of-sight signal is also improved by indicating a clock signal in the control message.

In an implementation form of the device according to the first aspect, each control message is received in a link layer protocol.

The implementation mode has the advantage that the scheme can be easily implemented in the existing protocols such as WiFi, bluetooth, low power consumption and the like.

In an implementation form of the device according to the first aspect, each control message is embedded in a packet data unit payload.

In an implementation form of the apparatus according to the first aspect, the apparatus is further configured to:

determining a set of received signal strength indications (received signal strength indicator, RSSI) based on the set of control signals, wherein each RSSI is associated with a control signal;

the line-of-sight signal is identified based on the set of control signals and the set of RSSI.

This implementation has the advantage that the line-of-sight signal can be identified more accurately.

In an implementation form of the device according to the first aspect, identifying the line-of-sight signal further comprises:

for each RSSI, the associated RSSI equivalent distance is compared to a collected power equivalent distance to identify the line-of-sight signal.

It will be appreciated that each RSSI value corresponds to a particular equivalent distance and each collection power value corresponds to a particular equivalent distance. Thus, the corresponding equivalent distances may be compared to identify the line-of-sight signal.

This implementation has the advantage that the line-of-sight signal can be identified more easily.

identifying a control signal of the set of control signals having a minimum distance between the correlated RSSI equivalent distance and the collected power equivalent distance as the line-of-sight signal.

This implementation has the advantage that the line-of-sight signal is identified with a higher probability.

determining an angle of arrival of the identified line-of-sight signal;

A location of the communication device is determined based on the identified line-of-sight signal and its angle of arrival.

According to a second aspect of the present invention, the above and other objects are achieved by a wireless power transfer beacon for a communication system, the wireless power transfer beacon comprising the apparatus of any of the preceding claims and being adapted to:

and sending out a wireless power transmission signal to the communication device according to the determined position of the communication device.

The wireless power transfer beacon according to the second aspect has an advantage in that implementation complexity and cost are reduced since only a single wireless power transfer beacon is required. Furthermore, since the positioning accuracy is improved, the power transmission is improved as the direction of the power transmission beam is more correctly oriented during the power transmission.

According to a third aspect of the present invention, the above and other objects are achieved by a communication device for a communication system, the communication device being adapted to:

receiving a wireless power transfer signal;

determining a collected power based on the conversion of the received wireless power transfer signal to dc power;

a set of control signals is broadcast, wherein each control signal includes a control message indicating an identification of the communication device and the determined collected power.

In an implementation form of the communication device according to the first aspect, the communication device is further configured to:

a clock signal associated with the determined collected power is inserted into each control message.

In an implementation form of the communication device according to the first aspect, each control message is transmitted in a link layer protocol.

In an implementation form of the communication device according to the first aspect, each control message is embedded in a packet data unit payload.

According to a fourth aspect of the present invention, the above and other objects are achieved by a method for determining a location of a communication device by a device, the method comprising:

broadcasting a wireless power transfer signal;

The method according to the fourth aspect may be extended to an implementation corresponding to an implementation of the device according to the first aspect. Thus, an implementation form of the method comprises the features of a corresponding implementation form of the device.

The advantages of the method according to the fourth aspect are the same as those of the corresponding implementation form of the device according to the first aspect.

According to a fifth aspect of the present invention, the above and other objects are achieved by a method for a communication device, the method comprising:

receiving a wireless power transfer signal;

a set of control signals is broadcast, wherein each control signal includes a control message indicating an identification of the communication device and a control message of the determined collected power.

The method according to the fifth aspect may be extended to an implementation corresponding to an implementation of the communication device according to the third aspect. Thus, an implementation form of the method comprises the features of a corresponding implementation form of the communication device.

The advantages of the method according to the fifth aspect are the same as those of the corresponding implementation form of the communication device according to the third aspect.

The invention also relates to a computer program characterized by program code which, when run by at least one processor, causes the at least one processor to perform any of the methods according to the embodiments of the invention. Furthermore, the invention relates to a computer program product comprising a computer readable medium and said computer program, wherein said computer program is contained in said computer readable medium and comprises one or more from the following groups: read-Only Memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), flash Memory, electrically EPROM (EEPROM), and hard disk drive.

Further applications and advantages of the present invention will be described in detail in the following detailed description.

Drawings

The accompanying drawings are intended to illustrate and explain various embodiments of the present invention, wherein:

figure 1 shows the general principle of an embodiment of the invention;

figure 2 shows a system provided by an embodiment of the invention;

Fig. 3 shows a flow chart of a method of a device for determining the location of a communication device provided by an embodiment of the present invention;

fig. 4 shows a flow chart of a method for a communication device provided by an embodiment of the invention;

FIG. 5 shows a block diagram of a device for determining the location of a communication device provided by an embodiment of the present invention;

fig. 6 shows a block diagram of a communication device provided by an embodiment of the invention;

figure 7 shows a sequence diagram provided by an embodiment of the invention;

figure 8 illustrates two alternative RF to DC conversion techniques that may be implemented in connection with embodiments of the present invention;

FIG. 9 shows a protocol format provided by an embodiment of the present invention;

FIG. 10 shows a detailed algorithm flow chart for determining the location of a communication device provided by an embodiment of the present invention;

figure 11 shows a reference database of HP parameters as a function of distance;

figure 12 shows a reference database of RSSI parameters as a function of distance;

fig. 13 shows a polar representation of two control signals;

fig. 14 shows a polar representation of the final position of the collector.

Detailed Description

In a typical indoor scenario, a single transmission from a communication device may generate multiple received signals by a receiver due to multipath effects. The receiver is essentially unable to distinguish which signal is a Line-of-Sight (LoS) signal and which signal is a multipath signal. Thus, the estimation of the position of the communication device is not easy, as each received signal may produce different results. In order to locate the communication device with only one beacon station, at least two parameters are typically required, namely the distance between the receiver and the communication device and the direction angle to the communication device. Conventional schemes for indoor positioning are well known, but each has its advantages and disadvantages in terms of trade-off between positioning accuracy and the number of transmitters (sometimes also denoted as beacon stations). Examples of conventional indoor positioning schemes are proximity positioning based on received signal strength indication (Received Signal Strength Indication, RSSI), time difference of Arrival (Time Difference of Arrival, TDOA) and Angle of Arrival (AoA). In general, to achieve higher accuracy, the number of beacon stations required to use the conventional scheme is large.

The proximity positioning is based on an RSSI parameter, which is basically the ratio of the received power divided by the transmitted power. This method is highly dependent on the propagation environment and cannot use RSSI to distinguish the LoS signal from the multipath signal.

The TDOA scheme is based on a measurement of a time difference of arrival of the same transmission signal received by at least two beacons. This scheme can provide 2D or 3D positioning. However, 2D positioning requires at least 3 beacon stations, and 3D positioning requires at least 4 beacon stations. According to RF protocols for positioning, such as Ultra Wide Band (UWB), good accuracy can be achieved, but the installation costs are high, because at least 3 beacon stations are required to position the object, and very precise synchronization (in the order of nanoseconds) must be performed between the beacon stations. Furthermore, the distance range may be very limited when using TDOA.

The AoA scheme is based on the measurement of the phase difference between two consecutive elements of an antenna array. The propagation time differences of the signals arriving at the receiver create a phase difference on each antenna of the antenna array and its neighbors. Indoor positioning using AoA is still a good choice if only direction information is needed, as it provides direction information but not distance information. Furthermore, the AoA scheme is highly dependent on multipath behavior, as the receiver can find coherent reflections of the original incident signal from different angles.

From the above, it can be seen that locating the communication device or determining the position of the communication device accordingly is not easy, mainly due to multipath propagation phenomena. Thus, to obtain accurate indoor positioning, one key factor is the ability to distinguish direct RF signals (i.e., loS) from the multipath signals. Conventional indoor positioning techniques cannot distinguish between the LoS signal and the multipath signal, and their positioning algorithms are likely to produce inaccurate outputs, resulting in lower accuracy. However, the present solution provides a new technique for distinguishing the LoS signal from the multipath signal. The received signal is more suitable for position estimation by using a collected Power (HP) parameter, an Identity (ID) of the collector and optionally a transmission clock generation. The HP parameter represents a measure of the RF power converted from a radio frequency signal to DC power at the collector. The collector can broadcast a signal indicative of the HP parameter and the collector ID. The broadcast signal will propagate and multipath signals will occur. Thus, the beacon station receives not only the LoS signal but also an undirected signal due to multipath. In addition, a single beacon station may be used to determine the location of an object, thereby reducing installation costs and complexity. Furthermore, the scheme is independent of the radio frequency protocol, as it can be used for different protocols in the physical layer, e.g. WiFi, bluetooth low energy (Bluetooth Low Energy, BLE), etc.

Fig. 1 emphasizes the importance of distinguishing the LoS signal from the multipath signal, and in fig. 1 the collector broadcasts a signal that will arrive as a LoS signal at the beacon station and at least one multipath signal that is reflected onto an obstacle. If the beacon station uses only the information in the multipath signal, the estimation of the distance to the collector and the angle of arrival will be erroneous. On the other hand, the beacon station according to the embodiment of the present invention can separate the LoS signal from the multipath signal due to the HP parameter and ID contained or indicated in the broadcast signal using the collector. Thus, all broadcast signals originating from the same collector transmission will have the same HP measurement value and the same ID. All signals from the same broadcast transmission will have the same HP value, as it is encoded in the framing protocol as the ID of the collector.

Embodiments of the present invention may be used in any indoor or outdoor application where the position of a collector must be determined or estimated. In particular, WPT applications are suitable where the collector location needs to be known in order to emit energy. However, this solution can be extended to other applications where a low cost and practical positioning solution is required. Non-limiting examples of other potential applications include:

Intelligent home: typically, most smart homes are equipped with RF hubs (e.g., wiFi routers, 3G/4G/5G relays, smart speakers, etc.), and suggested beacons may be integrated into these existing RF hubs, while portable or mobile devices (e.g., smartphones, tags, access cards/keys) may be upgraded with RF collectors.

Secure RF access: with the increasing security issues associated with the different RF protocols currently available, embodiments of the present invention may be used as an additional login security service to ensure access to an RF network (e.g., wiFi, GSM, wireless private network, etc.). For example, in an office conference room equipped with a wireless audio/video system of the prior art, only physically present people can access different wireless networks for privacy reasons. The beacon proposed in the present invention can be placed in a room as a stand-alone device embedded in another RF hub, and everyone has a small smart key/card with a collector. Since the proposed device is able to locate the collector, in this case it is confirmed that the item belonging to someone is in the room and wireless access can be allowed.

Industry 4.0/industry tracking: the necessity of locating objects in a real-time, low cost manner is one of the key requirements of industry 4.0. Embodiments of the present invention provide a reliable and low cost indoor positioning method that can be deployed at an industrial site.

Data center: some data centers require a reliable system to confirm how many server racks are in a particular room, but sometimes also the exact location of a particular server rack. Embodiments of the present invention may potentially be used to provide a low cost and practical solution to this problem.

Accordingly, a system as shown in fig. 2 provided by an embodiment of the present invention is disclosed herein. The system comprises the device 100 for determining the location of the communication device 300 and the communication device 300 itself.

The device 100 for determining the location of the communication device 300 is also referred to as a beacon station 100. Accordingly, these expressions will be used interchangeably in the present invention.

The beacon 100 may be a stand-alone device that may be placed on a wall, a desk, or may be hidden in a suspended ceiling. The beacon station 100 may be a part of other devices such as a base station or an Access Point (AP). In general, the device 100 or the beacon station 100 is configured to generate a waveform signal that will wirelessly power the communication device 300 or the collector 300. The device 100 or the beacon station 100 is further arranged to receive a control signal from the communication device 300 or the collector 300, the control signal having at least information elements or parameters HP and ID.

The communication device 300 is also referred to as a power collector 300 or simply as a collector 300. Accordingly, these expressions will be used interchangeably in the present invention. The collector herein may be any general purpose communication device, such as a smart phone, a smart watch, an IoT device, a smart card/key, and any portable stationary electronic device. The beacon station may be any one of a WPT transmitter, RF hub, wiFi router, smart speaker, and any wall plug device capable of generating RF signals. The collector is capable of measuring the conversion of a received RF signal to DC or AC power.

The collector 300 may be a stand-alone device or embedded in any other suitable device, such as a smart phone, smart home device, ioT device, client device, etc. Client devices in the present invention include, but are not limited to: UEs such as smartphones, cellular phones, cordless phones, session initiation protocol (session initiation protocol, SIP) phones, wireless local loop (wireless local loop, WLL) stations, personal digital assistants (personal digital assistant, PDA), handheld devices with wireless communication capabilities, computing or other processing devices connected to a wireless modem, in-vehicle devices, wearable devices; an integrated access and backhaul (integrated access and backhaul, IAB) node, such as a mobile car or a device installed in a car, a drone, a device-to-device (D2D) device, a wireless camera, a mobile station, an access terminal, a subscriber unit, a wireless communication device, a wireless local area network (wireless local access network, WLAN) station, a wireless enabled tablet, a notebook embedded device, a universal serial bus (universal serial bus, USB) dongle, a wireless client device (CPE-premises equipment), and/or a chipset. In an internet of things (Internet of Thing, IOT) scenario, the client device may represent a machine or another device or chipset in communication with another wireless device and/or network device. The UE may also be referred to as a mobile phone, a cellular phone, a tablet or a notebook with wireless capabilities. The UE described herein may be a portable, pocket, hand-held, computer-built-in or vehicle-mounted mobile device, etc., capable of voice and/or data communication with other entities (e.g., another receiver or server) over a radio access network. The UE may be a Station (STA), which is any device that contains an IEEE 802.11 compliant media access control (media access control, MAC) and physical layer (PHY) interface that interfaces with a Wireless Medium (WM). The UE may also be configured for communication in 3GPP related LTE and LTE-Advanced, wiMAX and its evolution, as well as fifth generation wireless technologies (e.g., NR).

The collector 300 may be a fixed communication device or a mobile communication device. For practical reasons, the Downlink (DL) may be defined as all communication protocols in the sequential direction from the beacon station 100 to the collector 300, and thus the Uplink (UL) may be defined as all communication from the collector 300 to the beacon station 100.

In accordance with an embodiment of the present invention, and in conjunction with the system 500 shown in fig. 2, disclosed herein is a device 100, also referred to as a beacon station 100, for determining the location of a communication device. The device 100 is for broadcasting a wireless power transfer signal 510. The device 100 is further configured to receive a set of control signals (520 a, 520b, … …, 520 n) from the communication device 300 in response to the transmission of the wireless power transfer signal 510. Each control signal 520n includes a control message 520n ', the control message 520n' indicating the ID of the communication device 300 (also referred to as collector 300) and the HP associated with the wireless power transfer signal 510. The apparatus 100 is further for identifying LoS signals in the set of control signals (520 a, 520b, … …, 520 n) based on the set of control signals (520 a, 520b, … …, 520 n). The device 100 is further configured to determine a location of the communication device 300 based on the identified LoS signal. It should be noted that only one beacon station 100 is needed in the system 500 to determine the location of the collector 300.

Fig. 3 shows a flow chart of a corresponding method 200 of a beacon station, which may be performed, for example, by the beacon station 100 shown in fig. 2. The method 200 includes broadcasting (202) a wireless power transfer signal 510. The method 200 further includes receiving (204) a set of control signals (520 a, 520b, … …, 520 n) from the communication device 300. Each control signal 520n includes a control message 520n ', the control message 520n' indicating the ID of the communication device 300 and the HP associated with the wireless power transfer signal 510. The method 200 further includes identifying (206) a LoS signal in the set of control signals (520 a, 520b, … …, 520 n) based on the set of control signals (520 a, 520b, … …, 520 n). The method 200 further includes determining (208) a location of the communication device 300 based on the identified LoS signal.

Also disclosed herein, in accordance with an embodiment of the present invention, in conjunction with the system 500 shown in fig. 2, is a communication device 300 (also denoted as collector 300) for use in the communication system 500. The communication device 300 is arranged to receive a wireless power transfer signal 510. The communication device 300 is further configured to determine HP based on the conversion of the received wireless power transfer signal 510 to dc power. The communication device 300 is further configured to broadcast a set of control signals (520 a, 520b, … …, 520 n), wherein each control signal 520n comprises a control message 520n ', the control message 520n' indicating the ID of the communication device 300 and the determined HP.

Fig. 4 illustrates a flow chart of a method 400 of a communication device, such as may be performed by the communication device 300 shown in fig. 2. The method 400 includes receiving (402) a wireless power transfer signal 510. The method 400 further includes determining (404) an HP based on the conversion of the received wireless power transfer signal 510 into DC power. The method 400 further comprises broadcasting (406) a set of control signals (520 a, 520b, … …, 520 n), wherein each control signal 520n comprises a control message 520n ', the control message 520n' indicating the ID of the communication device 300 and the determined HP.

In an embodiment of the present invention, the beacon station 100 may be included in a WPT beacon station 600 for the communication system 500. The WPT beacon 600 is operable to transmit a wireless power transfer signal 530 to the collector 300 based on the determined location of the collector 300.

Fig. 5 shows a block diagram of an exemplary WPT beacon 600 provided by an embodiment of the present invention. The WPT beacon 600 may include: WPT Transmitter (TX) block 102, antenna array 110, microcontroller unit (Micro Controller Unit, MCU) 106, location determination (Position Determination, PD) block 104, and database 108, including a real-time database and a corresponding reference database (see below). The WPT TX block 102 and the PD block 104 may share the same antenna array or have separate antenna arrays depending on the operating frequency and/or application. The database 108 may be stored locally, for example embedded in the beacon 100 or cloud or a combination thereof (i.e., partially embedded in the beacon 100 and cloud). The different blocks of the beacon 100 are coupled to each other using communication means known in the art.

The WPT TX block 102 of the WPT beacon 600 may include a frequency synthesizer or VCO block, a bi-directional channel with amplitude and phase variations coupled to the antenna array 110. Thus, the block is responsible for creating the waveform signal that will power the collector 300 wirelessly. The PD block 104 with its own MCU is responsible for demodulating the ID and HP of each control message. The database 108 may be divided into two parts, a reference database and a real-time database. The reference database is initially built based on empirical data, and the real-time database stores current measurements of the PD parameters. The reference database stores the HP values.

Fig. 6 shows a block diagram of an exemplary collector 300 provided by another embodiment of the invention. The collector 300 includes: a WPT Receiver (RX) block 302, an MCU 306, an antenna array 310, an RF TX block 304, and a load 308. In addition to powering the load 308, the WPT RX block 302 is also responsible for providing a measurement or estimate of the amount of HP to the MCU 306. The MCU 306 also stores the ID of the collector 300 and in an embodiment generates a clock signal to be sent in each control message for each broadcast transmission. The RF TX block 304 may operate at the same frequency as the WPT RX block 302 or may operate at its own operating frequency, which in the latter case means that it has its own antenna array (not shown). Finally, the RF TX block 304 can broadcast control signals including control messages indicating the parameters, ID, HP, and (in an embodiment) clock signals. Due to multipath effects, the broadcast signal will generate a set of control signals (520 a, 520b, … …, 520 n) at the beacon station 100.

Fig. 7 shows a flowchart for determining the position of the collector 300 provided by other embodiments of the present invention.

In step I of fig. 7, the WPT beacon 600 broadcasts the wireless power transfer signal 510 in a WPT scan mode in different directions (e.g., in an ordered sequence or in a random sequence). Accordingly, the process begins with the WPT beacon 600 broadcasting energy by broadcasting the wireless power transfer signal 510 in a scan mode to search for a collector that is capable of converting RF power to DC power. For example, the speed and angular step size of the WPT scan mode may be adjusted as a function of the RF transmitter operating frequency.

In step II of fig. 7, the collector 300 receives the wireless power transfer signal 510 from the WPT beacon 600 and converts RF power of the received wireless power transfer signal 510 to DC power. The collector 300 also measures or estimates the amount of HP derived from the wireless power transfer signal 510 to obtain the HP parameters used herein.

In step III of fig. 7, in response to receipt of the wireless power transfer signal 510, the collector 300 broadcasts a control signal 520 including a control message 520n' indicating its unique ID and HP parameters. Furthermore, for each broadcast transmission, the collector 300 increments the internal transmission clock. Thus, as previously mentioned in embodiments of the present invention, each control message 520n' also indicates the clock signal associated with the HP. The WPT beacon 600 uses clock parameters to separate the different broadcast transmissions of the collector 300 from each other.

Due to the actual propagation phenomenon, the WPT beacon 600 receives not only the LoS signal but also one or more multipath signals, and thus a set of control signals (520 a, 520b, … …, 520 n) will arrive at the WPT beacon 600.

In step IV of fig. 7, the WPT beacon 600 is able to demodulate each received control signal based on the set of control signals (520 a, 520b, … …, 520 n) received from the collector 300 and their corresponding control messages and store information about the received control signals in a real-time database. For each control signal received from the collector 300, the WPT beacon 600 is used to demodulate the ID and the HP parameters. Furthermore, the WPT beacon 600 calculates an RSSI value and an AoA value of each received control signal and stores the values in the real-time database. For the same clock signal, the control signals of the set of control signals are likely to have the same ID and HP, but different AoA and RSSI values.

The WPT beacon 600 must separate the LoS signal from the multipath signals in the set of control signals (520 a, 520b, … …, 520 n) because the LoS signal is more reliable for position calculation. Because, based on the received set of control signals (520 a, 520b, … …, 520 n), in an embodiment of the invention, the WPT beacon 600 is configured to determine a set of RSSI based on the set of control signals (520 a, 520b, … …, 520 n). Each RSSI in the set of RSSI is associated with a particular received control signal 520 n. Based on the set of control signals (520 a, 520b, … …, 520 n) and the set of RSSI, the LoS signal may be identified in the set of control signals (520 a, 520b, … …, 520 n). In an embodiment of the present invention, identifying the LoS signal further includes: for each RSSI, the associated RSSI equivalent distance is compared to the HP equivalent distance to identify the LoS signal. It has been recognized that each RSSI value corresponds to a particular equivalent distance and each HP value corresponds to a particular equivalent distance. The equivalent distances of the RSSI values and the HP values may be obtained from an HP reference database and an RSSI reference database, respectively.

A non-limiting way of identifying the LoS signal is to identify a control signal 520n of the set of control signals (520 a, 520b, … …, 520 n) having a minimum distance between the associated RSSI equivalent distance and the collected power equivalent distance as the LoS signal. That is, the distance d from the collector 300 may be determined using the set of calculated RSSI's. For example, to determine the LoS signal, for each sampled control signal, its RSSI equivalent distance is compared to the HP equivalent distance. For example, by applying the euclidean minimum absolute method, the WPT beacon 600 may identify the RSSI candidate having an estimated distance closest to the estimated HP distance. Based on this calculation, the WPT beacon 600 can confirm which of the set of control signals (520 a, 520b, … …, 520 n) is the LoS signal. It is noted that methods other than the euclidean minimum absolute method may be used to identify the LoS signal.

Furthermore, based on the received set of control signals (520 a, 520b, … …, 520 n), in an embodiment of the invention, the WPT beacon 600 is also used to calculate the AoA of the received set of control signals (520 a, 520b, … …, 520 n). Thus, by previously identifying the LoS signal, the WPT beacon 600 can determine the corresponding AoA of the identified LoS signal. Thus, the distance d between the collector 300 and the WPT beacon 600 has been determined together with the AoA, i.e. the position of the collector 300 can be determined.

The reference databases, which may be stored locally in the WPT beacon 600 and/or stored in a remote computer through the cloud, may include three reference databases, namely, an RSSI reference database, an HP reference database, and an AoA reference database. Fig. 8 (a), 8 (b) and 8 (c) show examples of the real-time database, the HP reference database and the RSSI reference database.

Fig. 8 (a) shows a real-time database with exemplary entries. For conceptual presentation purposes, in this case, only two control signals 1 and 2 are shown in the figure, but not limited thereto. For each control signal, the following entries are stored in the real-time database: collector ID, HP value (e.g., in dBm), aoA value (e.g., in degrees), RSSI value (e.g., in dBm), and transmit clock.

It can be seen that in addition to the WPT beacon 600 being able to decode the parameters, ID, HP, aoA, RSSI and clock, it is not sufficient to directly determine which signal is a LoS or multipath signal, especially when multiple signals are received.

The RSSI reference database in fig. 8 (b) initially stores a look-up of the distance corresponding to the empirical RSSI values at the location where the collector 300 may be locatedAnd (5) looking up a table. Taking into account the transmission power P of the control signal _t As is known, the WPT beacon 600 is capable of measuring the ratio P of the power of the received control signal to the power of the transmitted control signal _r /P _t . Thus, the RSSI can be calculated because the parameter is P _r /P _t Is a ratio of (2). Due to P _r And P _t Is known and for example based on fries equation, for each RSSI value an equivalent distance between the WPT beacon 600 and the collector 300 may be calculated.

The HP reference database in fig. 8 (c) initially stores a look-up table of empirical HP values versus distance at locations where the collector 300 may be located. In this case, the difference is that P _t And P _r Is opposite, i.e. P _t From the WPT beacon 600, p _r At the collector 300.

The AoA reference database stores a look-up table of AoA values and angles in which the collector 300 may be pointed. In the WPT beacon 600, for example, an embedded software algorithm may compare real-time measurements of the three parameters RSSI, HP and AoA with values in a reference database. Thus, as an output, the position of the collector 300 is determined as described previously.

The referenced database may have initial values derived from empirical calculations. However, in embodiments of the invention, the values in the database may be based on actual measured values. In addition, a calibration process of the database may be implemented to create a baseline between the empirical database and the actual measurements to improve accuracy.

In step V of fig. 7, the WPT beacon 600 indicates a WPT beam at the collector 300. Since the high-precision WPT beacon 600 has determined the position of the collector 300, wireless power supply of the collector 300 can be efficiently performed.

In step VI of fig. 7, the collector 300 receives the directional beam and converts the power in the beam to DC power for powering one or more loads. For example, the converted power may be used to charge rechargeable devices and/or directly power the power consumers of the collector 300.

The above process in fig. 7 may be repeated in a periodic or non-periodic manner to ensure that the collector 300 is in the same position or has been moved (if the collector 300 is a moving collector 300).

In the following description of the present invention, each of the parameters HP, RSSI and AoA will be more thoroughly described and explained in the context of the present scheme.

The collector 300 may include circuitry capable of converting RF power to DC power. Once the antenna array 310 receives the RF signal from the WPT beacon 600, the RF signal may be injected at the input of rectifier 312 where it will be converted to DC power. Depending on the topology of the rectifier 312, e.g., half-wave or full-wave, the rectifier 312 is capable of converting one or both sides of a sinusoidal signal, as shown in fig. 9 (a) and 9 (b). Schottky diodes and transistors are the most commonly used converters in the art. A typical rectifier topology based on schottky diodes is shown in fig. 9 (a), which shows a half-wave single diode topology; fig. 9 (b) shows a full wave voltage multiplier topology. Once the RF to DC conversion is performed, a power management module (Power Management Module, PMM) (not shown) may be required in order to boost the voltage level to an acceptable level in order to charge and/or manage the energy storage element, e.g., capacitor, super capacitor, rechargeable battery, etc.

The amount of power available to the load 308 of the collector 300 depends on different parameters, such as the parameters described in the following equations:

wherein P is _T For WPT transmission power, η _ant And D _ant The efficiency and directivity of the receiver/collector antenna, respectively. The wavelength is λ and the distance between the transmitter (i.e., the WPT beacon 600) and the receiver (i.e., the collector 300) is d. Finally, the step of obtaining the product,for the RF-DC conversion efficiency of the rectifier 312, and (2)>Is the DC-DC conversion efficiency.

There are a variety of RSSI definitions in the art. For convenience, RSSI may be defined herein as the ratio between the received power of the WPT beacon 600 and the power level of the transmitted signal of the collector 300. However, other definitions of RSSI may be used in connection with embodiments of the present invention. It is also noted that the RF channel characteristics (e.g., power, frequency, etc.) of the UL (collector 600 of WPT beacons) are typically different from those in DL to avoid interference.

The system knows the transmission power Pt of the collector _Harv The received power Pr of the beacon station _bea Depending on the path loss. Based on the RSSI measurements, an estimate of the distance d between the collector 300 and the beacon 100 may be calculated. However, such estimation is unreliable due to uncertainty associated with multipath. In other words, if the beacon station 100 relies only on RSSI measurements, it cannot distinguish the direct signal (i.e., loS) from multipath signals.

The PD block 104 of the WPT beacon 600 is capable of sampling received signals from the antenna array. These measurements are sampled by taking multiple phase and amplitude measurements at precise intervals. This process is called in-phase and quadrature sampling-IQ sampling. For each element of the antenna array, IQ samples are acquired. The angle of arrival Θ can be calculated as follows:

where Φ is the phase difference between two elements of the antenna array, λ is the wavelength, and da is the distance between the elements of the antenna array.

In addition, fig. 10 shows a suggested grouping framework of the collector 300 provided by an embodiment of the present invention. The grouping framework presented herein is based on a standard grouping of BLE version 5.1, which includes direction finding information in a fixed frequency extension signal (Constant Tone Extension, CTE). Note that the present packet framework may be based on other packet formats and is therefore not limited to BLE version 5.1.

As shown in fig. 10, each control message 520n' may be transmitted and received in a link layer protocol in a protocol format. The link layer protocol may include a Packet Data Unit (PDU) header, a PDU payload, a message integrity check (Message Integrity Check, MIC), and a cyclic redundancy check (Cyclical Redundancy Check, CRC). In an embodiment of the present invention, each control message 520n' may be embedded in the PDU payload of the link layer protocol shown in FIG. 10. Thus, according to these embodiments, any of the parameters ID, HP, and clock signals may be embedded into the PDU payload.

To verify the performance of the present scheme, the following systems have been implemented in the downlink, from WPT beacon 600 to collector 300: operating frequency=5.8 GHz, transmitter power=24.5 dBm, transmitter antenna gain=15.6 dBi, receiver antenna gain=5 dBi, collector conversion efficiency (i.e., RF/dc+dc/DC) =39%. In the uplink, i.e. from collector 300 to WPT beacon 600: operating frequency = 2.4GHz, transmitter power = 20dBm, transmitter antenna gain = 0dBi, receiver antenna gain = 0dBi.

Fig. 11 shows a reference database of HP parameters as a function of distance, i.e. the x-axis shows the distance (in meters) between the beacon 100 and the collector 300, and the y-axis shows the amount of collected power (in dBm). As shown in fig. 11, the transmission power P of the WPT beacon signal is taken into consideration _t As is known, the collector 300 is capable of measuring the received signal P _r To obtain the parameter HP. Due to P _r And P _r Is known and derived, for example, based on fries equation, for each HP, the equivalent distance between the WPT beacon 600 and the collector 300 can be calculated.

FIG. 12 showsA reference database of RSSI parameters as a function of distance is shown, i.e. the x-axis shows the distance (in meters) between the beacon station 100 and the collector 300 and the y-axis shows the RSSI measurements (in dBm). As shown in fig. 12, the transmission power P of the control signal is taken into consideration _t As is known, the WPT beacon 600 is able to measure the ratio P _r /P _t . Since these powers are known and derived, for example, based on fries equation as described above, for each RSSI, the equivalent distance between the WPT beacon 600 and the collector 300 can be calculated.

Fig. 13 shows polar representation of the first control signal (signal 1) and the second control signal (signal 2) (in terms of angle (in deg.) and x-distance (in m)) and the corresponding distance calculations based on the HP and RSSI parameters. As observed in fig. 13, based on the two received control signals (signals 1 and 2), the WPT beacon 600 cannot directly distinguish which signal is a LoS signal and which signal is a multipath signal, nor can the precise location or direction of the collector 300 be defined. In addition, a significant difference between the estimated distances of each parameter RSSI and HP can also be observed. The algorithm will continue the process flow to identify the LoS signal and then calculate the location of the collector 300. In other words, the algorithm will apply the different steps described to present the first result, wherein each control signal is plotted from the measurements. Any distance calculation to determine the position of the collector 300 in an intermediate step may be erroneous. However, once the PD algorithm converges to the final calculation, the correct position of the collector 300 can be found.

Fig. 14 shows a polar representation of the final position of the collector 300 generated by the WPT beacon 600. It can be observed that the algorithm has identified a signal denoted "signal 1" (see fig. 13) as the LoS signal. From fig. 14, it follows that a single device 100 is able to calculate the distance between itself and the collector 300 and the angle of arrival of the incident LoS signal. Since the LoS signal has been correctly identified, accurate positioning of the collector 300 is possible.

Table 1 below shows some of the differences of this scheme from the conventional scheme. As shown in table 1, locating an indoor object (e.g., communication device 300) using RSSI techniques is not a suitable option, so the values of the RSSI may be quite different for each received signal (i.e., loS or multipath signal) and therefore different range estimates will be obtained. The AoA technique provides only information about the direction angle of the received signal, and does not provide information about the distance. The TDOA technique is one of the most accurate solutions for indoor positioning, but it requires at least 3 beacon stations, which greatly increases implementation costs. However, with this scheme, only one beacon station is required.

Table 1: performance comparison

Furthermore, any method according to an embodiment of the invention may be implemented in a computer program having code means, which when run by processing means causes said processing means to perform the steps of said method. The computer program is embodied in a computer readable medium of a computer program product. The computer readable medium may include essentially any Memory, such as Read-Only Memory (ROM), programmable ROM (Programmable Read-Only Memory), erasable PROM (EPROM), flash Memory, electrically Erasable PROM (Electrically Erasable PROM, EEPROM), or hard disk drive.

Furthermore, the skilled person will appreciate that the embodiments of the device 100 for determining the position of a communication device and the described communication device 300 comprise the necessary communication capabilities in the form of functions, means, units, elements etc. for performing the present solution. Examples of other such devices, units, elements, functions include: processors, memories, buffers, logic controls, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selection units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSP, MSD, TCM encoders, TCM decoders, power supply units, power supply feeders, communication interfaces, communication protocols, etc., are reasonably arranged together for performing the present scheme.

In particular, the device 100 for determining the location of a communication device and the processor of the communication device 300 may comprise, for example, one or more instances of a central processing unit (Central Processing Unit, CPU), processing unit, processing circuit, processor, application specific integrated circuit (Application Specific Integrated Circuit, ASIC), microprocessor, or other processing logic that may interpret and execute instructions. Thus, the term "processor" may refer to a processing circuit including a plurality of processing circuits, such as any, some, or all of the processing circuits listed above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing data, including data buffering and device control functions, such as call processing control, user interface control, and the like.

Finally, it is to be understood that the invention is not limited to the embodiments described above, but that it relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1. A device (100) for determining a position of a communication device (300), characterized in that the device (100) is adapted to:

broadcasting a wireless power transfer signal (510);

Receiving a set of control signals (520 a, 520b, … …, 520 n) from the communication device (300), wherein each control signal (520 n) comprises a control message (520 n '), the control message (520 n') indicating an identity (identity, ID) of the communication device (300) and a collected power associated with the wireless power transfer signal (510);

identifying a line-of-sight (LoS) signal in the set of control signals (520 a, 520b, … …, 520 n) based on the set of control signals (520 a, 520b, … …, 520 n);

-determining a location of the communication device (300) based on the identified line-of-sight (LoS) signal.

2. The device (100) of claim 1, wherein each control message (520 n') further indicates a clock signal associated with the collected power.

3. The device (100) according to claim 1 or 2, wherein each control message (520 n') is received in a link layer protocol.

4. A device (100) according to claim 3, characterized in that each control message (520 n') is embedded in a packet data unit payload.

5. The apparatus (100) according to any one of the preceding claims, further being adapted to:

Determining a set of received signal strength indications (received signal strength indicator, RSSI) based on the set of control signals (520 a, 520b, … …, 520 n), wherein each RSSI is associated with a control signal (520 n);

the line-of-sight (LoS) signal is identified based on the set of control signals (520 a, 520b, … …, 520 n) and the set of RSSI.

6. The device (100) of claim 5, wherein identifying the line-of-sight (LoS) signal further comprises:

for each RSSI, the associated RSSI equivalent distance is compared to a collected power equivalent distance to identify the line-of-sight (LoS) signal.

7. The device (100) of claim 6, wherein identifying the line-of-sight (LoS) signal further comprises:

-identifying a control signal (520 n) of the set of control signals (520 a, 520b, … …, 520 n) having a minimum distance between the correlated RSSI equivalent distance and the collected power equivalent distance as the line-of-sight (LoS) signal.

8. The apparatus (100) according to any one of the preceding claims, further being adapted to:

determining an angle-of-arrival (AoA) of the identified line-of-sight (LoS) signal;

-determining the location of the communication device (300) based on the identified line-of-sight (LoS) signal and its angle of arrival (AoA).

9. A wireless power transfer beacon (600) for a communication system (500), characterized in that the wireless power transfer beacon (600) comprises the device (100) of any of the preceding claims and is adapted to:

-issuing a wireless power transfer signal (530) to said communication device (300) in dependence of said determined position of said communication device (300).

10. A communication device (300) for a communication system (500), characterized in that the communication device (300) is adapted to:

receiving a wireless power transfer signal (510);

determining a collected power based on a conversion of the received wireless power transfer signal (510) to direct current power;

a set of control signals (520 a, 520b, … …, 520 n) is broadcast, wherein each control signal (520 n) comprises a control message (520 n '), the control message (520 n') indicating an Identity (ID) of the communication device (300) and the determined collected power.

11. The communication device (300) of claim 10, further configured to:

A clock signal associated with the determined collected power is inserted into each control message (520 n').

12. The communication device (300) according to claim 10 or 11, wherein each control message (520 n') is transmitted in a link layer protocol.

13. The communication device (300) of claim 12, wherein each control message (520 n') is embedded in a packet data unit payload.

14. A method (200) of a device (100) for determining a location of a communication device, the method (200) comprising:

broadcasting (202) a wireless power transfer signal (510);

-receiving (204) a set of control signals (520 a, 520b, … …, 520 n) from a communication device (300), wherein each control signal (520 n) comprises a control message (520 n '), the control message (520 n') indicating an Identity (ID) of the communication device (300) and a collected power associated with the wireless power transfer signal (510);

identifying (206) a line-of-sight (LoS) signal in the set of control signals (520 a, 520b, … …, 520 n) based on the set of control signals (520 a, 520b, … …, 520 n);

-determining (208) a location of the communication device (300) based on the identified line-of-sight (LoS) signal.

15. A method (400) for a communication device (300), the method (400) comprising:

-receiving (402) a wireless power transfer signal (510);

determining (404) a collected power based on a conversion of the received wireless power transfer signal (510) to direct current power;

a set of control signals (520 a, 520b, … …, 520 n) is broadcast (406), wherein each control signal (520 n) comprises a control message (520 n '), the control message (520 n') indicating an Identity (ID) of the communication device (300) and the determined collected power.

16. Computer program with a program code for performing the method according to claim 14 or 15, when the computer program runs on a computer.