CN116711338A - RF-based sensing using RSSI and CSI - Google Patents

Abstract

The present invention relates to performing radio frequency based sensing based on Channel State Information (CSI), received Signal Strength Indicator (RSSI), or a combination thereof, based on a current context. A current context for performing radio frequency based sensing is determined, and at least one of the two nodes (26, 28, 30) of the radio frequency system (100) is configured to perform radio frequency based sensing based on the current context, based on CSI, RSSI, or a combination thereof. The current context may be determined in real-time. This may allow for improved detection performance and/or reduced power consumption in real time.

Description

RF-based sensing using RSSI and CSI

Technical Field

The present invention relates to a Radio Frequency (RF) system for performing RF-based sensing, a method for performing RF-based sensing and a computer program product.

Background

WO 2019/096784 A1 shows a method of detecting an intruder into a wireless network formed at least in part by a plurality of luminaires connected in wireless communication. The method comprises the following steps: monitoring, by a network interface of each of a plurality of luminaires in a connected lighting system, wireless network activity of a plurality of client devices; receiving, by a network interface of each luminaire, one or more physical layer characteristics from each client device that is accessing a wireless network and that is located within a geographic area defined by a communication range of each luminaire within a specified time interval; retrieving, by a processor of the connected lighting system, an array of reference profiles, the array comprising a subset of the reference profile of each luminaire, each subset comprising a plurality of reference profiles corresponding to a plurality of time intervals, respectively, each reference profile representing an expected profile of one or more physical layer characteristics of a respective one of the luminaires during a respective one of the plurality of time intervals; generating, by a processor of the connected lighting system, an observation profile for each luminaire, each observation profile representing an actual profile of one or more physical layer property values received by a given one of the luminaires over a specified time interval; comparing, by a processor of the connected lighting system, each observation profile with one of the reference profiles corresponding to the specified time interval, in order to detect anomalies; and if an anomaly is detected, initiating an alarm state by a processor of the connected lighting system. According to one embodiment, the physical layer characteristics include a Received Signal Strength Indicator (RSSI), channel State Information (CSI), or a combination comprising at least one of the foregoing.

WO 2020/043592A1 discloses a system for selecting one or more devices in a wireless network to transmit, receive and/or process radio frequency signals for presence and/or location detection, the system comprising at least one processor configured to determine suitability of each of a plurality of devices for transmitting, receiving and/or processing radio frequency signals for presence and/or location detection, select a subset of devices from the plurality of devices based on the determined suitability for each of the plurality of devices, and instruct at least one of the subset of devices to act as a device for transmitting, receiving and/or processing radio frequency signals for presence and/or location detection.

Disclosure of Invention

It may be seen as an object of the present invention to provide an RF system, a method for performing RF-based sensing, a computer program product and a computer readable medium allowing improved detection performance and/or reduced use for performing RF-based sensing.

In a first aspect of the invention, an RF system is presented comprising at least two nodes for performing RF-based sensing in a sensing area. The RF system is configured to determine a current context (context) for performing RF-based sensing, and based on the current context, configure at least one node for performing RF-based sensing based on CSI, RSSI, or a combination thereof.

Since the RF system is configured to configure at least one node for performing RF-based sensing based on CSI, RSSI, or a combination thereof based on the current context, detection performance for performing RF-based sensing may be improved and/or power consumption may be reduced. The RF system may be configured to determine the current context in real-time. This allows for real-time adjustment of RF-based sensing performed by the RF system depending on the current context.

In general, performing RF-based sensing (i.e., CSI-based sensing) based on CSI provides more detail than performing RF-based sensing (i.e., RSSI-based sensing) based on RSSI. In certain situations, i.e., based on the current context, RSSI-based sensing may be beneficial compared to CSI-based sensing. For example, RSSI-based sensing may be beneficial compared to CSI-based sensing, either due to limitations of sensing applications (e.g., standby power requirements), or due to environmental conditions (e.g., reduced signal-to-noise ratio (SNR) caused by lengthy transmissions or interference). The RF system may allow real-time determination of whether it is beneficial to perform RF-based sensing based on CSI or RSSI or a combination thereof, e.g., in the entire sensing area (such as a room or space of a building) based on the current context.

The RF system may be configured to perform RF-based sensing based on RSSI, CSI, or a combination thereof. The RF system may perform RF-based sensing based on RSSI, CSI, or a combination thereof, based on how to configure at least one node based on the current context.

RF-based sensing allows detection of various sensed events occurring in a sensing region, i.e. a specific space or a specific volume, e.g. a room in a building, a building or any other space. The sensing algorithm or the sensing analysis algorithm may detect and analyze how the RF signal is affected by the tangible entities within the sensing region. The RF signal is used to transmit RF messages. RF-based sensing may be used as a means to detect and classify sensed events, such as user activity in a home, office, etc. For example, based on WiFi RF-based sensing messages transmitted and received by nodes in the form of smart lights, RF-based sensing may determine movement in a room and automatically turn the lights on or off, nodes in the form of WiFi routers may estimate the person's respiratory rate, etc.

The basic principle of RF-based sensing is that the distortion of an RF signal in space is a function of both the physical entity in space (e.g. a moving object) and the frequency of the RF signal. Radio waves propagate through electromagnetic radiation and interact with the environment by reflection, refraction, diffraction, absorption, polarization, and scattering. The wireless attenuation of different materials is different in the typical frequency range used for RF-based sensing applications. Thus, characteristics of the sensing region (e.g., the building form of the room, the spatial arrangement, and the integrated surface area of each material type present in the sensing region) may affect the RF multipath signal characteristics of the sensing region.

To perform RF-based sensing, one node may act as a transmitting node, transmitting an RF signal comprising an RF message to another node acting as a receiving node. The received RF signal may then be analyzed. If the RF signal interacts with one or more tangible entities (e.g., objects or persons) on the transmission path between its nodes, the RF signal is disturbed, e.g., scattered, absorbed, reflected, or any combination thereof. These disturbances may be analyzed and used to perform RF-based sensing. The disturbed and/or reflected RF signal may comprise an RF-based sensed fingerprint based on signal parameters, such as real and imaginary parts of permittivity and susceptibility.

Both RSSI and CSI are metrics extracted from RF messages transmitted on the RF channel and are therefore functions of the RF messages. RSSI is a measure of the total attenuation of a wireless communication link between two nodes. In other words, RSSI is a rough measure of the estimated amount of power when a node starts to receive an RF message, i.e., RSSI corresponds to the average amount of power of the RF message. CSI (e.g., wiFi CSI) represents how RF signals propagate along multiple spatial paths at certain carrier frequencies in an RF channel between a transmitting node and a receiving node, and represents the impact that a tangible entity has along different frequencies. In other words, CSI is a metric extracted from subcarriers used to modulate and demodulate RF messages (e.g., wiFi messages). These sub-carriers represent different parts of the spectrum of the RF channel itself, resulting in more data points per RF message than RSSI. The CSI captures the RF characteristics of the environment in the vicinity because the amplitude and phase of the CSI are affected by multipath effects, which include amplitude attenuation and phase shift of the RF signal. For RF systems with multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM), CSI measurements provide a three-dimensional (3D) matrix of complex values representing amplitude attenuation and phase shift.

The time series of multiple CSI measurements captures how the RF signal propagates through surrounding tangible entities, such as physical objects and people, in the time, frequency, and spatial domains. A wide variety of different wireless sensing applications may be implemented by transmitting RF signals over RF multipath channels and analyzing the time series of multiple CSI measurements using an analysis algorithm (e.g., an artificial intelligence analysis algorithm). For example, CSI amplitude variations in the time domain may have different patterns for different people, activities, gestures, etc., which may be used for presence detection, motion detection, activity recognition, gesture recognition, and identification of people.

The observed CSI phase shifts in the spatial and frequency domains (i.e., transmit/receive antennas and carrier frequencies) are related to signal propagation delays and direction of arrival, which can be used for personnel location with RF-based sensing, as well as tracking in sensing areas (e.g., building space), in addition to occupancy and activity detection.

The CSI phase shifts in the time domain may have different dominant frequency components, which may be used to estimate respiration rate, for example, when RF-based sensing (i.e., CSI-based sensing) is performed based on CSI.

Since both CSI-based sensing (i.e., CSI-based performing RF-based sensing) and RSSI-based sensing (i.e., RSSI-based performing RF-based sensing) may rely on the same physical radio, e.g., if both are extracted from the same protocol such as WiFi, and since the same RF messages may be analyzed for both to detect the sensing region, the physical course of signal propagation of both RF-based sensing methods may be the same, i.e., the RF multipath channels within the sensing region may not change merely because of the CSI data or RSSI data extracted from the radio

Furthermore, both RSSI-based sensing and CSI-based sensing analyze the time sequence of the RF channel between two nodes. In contrast to RSSI-based sensing algorithms, CSI-based sensing algorithms may extract metrics from each different WiFi subcarrier that may be related to multipath characteristics of the sensing region (e.g., physical building space).

The CSI amplitude and phase are affected by RF signals from multiple paths within the sensing region, rather than by a single RF path. For example, RSSI is a simple measurement that is performed locally by any RF radio for "housekeeping" purposes. In contrast, to perform CSI-based sensing using WiFi, multipath information must first be derived from the measured raw CSI data provided by the WiFi microcontroller. For example, a 20MHz WiFi channel may have 64 CSI subcarrier frequencies. Since each of these sub-frequencies is not interacting with a tangible entity (e.g., a physical object such as a brick wall of a room or a decoration of a sofa), analysis of how the 64 sub-components behave as a whole (e.g., their relative differences) may be indicative of multipath behavior of the sensing region.

The current context may include one or more of the following:

The sensing application is performed in a manner that,

the delay requirement is set up in such a way that,

the radio power consumption requirements are that,

the radio transmission power requirements are set,

the radio beam shape requirements,

the radio reception beamforming requirements,

-the current location of the radio frequency system,

-a current location of at least one node,

the current date of the day,

a current mode of operation of at least one node,

the effect of the environment is to be taken care of,

the bandwidth currently available in the RF system,

current capabilities of at least one node,

sensing a current property of the area,

-error event detection rate requirement, and

-a stage of growth of the plant in the sensing area.

The sensing applications may include, for example, which type of sensing event is detected by performing RF-based sensing, such as fast, low-delay motion detection, occupancy detection, idle detection, fall detection, heartbeat detection, or any other sensing event. For example, if the sensing application is a motion or presence detection sensing application for detecting motion or presence of a tangible entity such as a user, the RF system may be configured to perform RSSI-based sensing. RSSI is directly related to the attenuation of RF signals used to perform RF-based sensing. This may allow an increased SNR to be obtained, since all transmission paths between the transmitting node and the receiving node of the RF signal are comprised in the transmission channel. This may allow the transmitting node to transmit at a lower transmission power. Further, RSSI-based sensing may be performed with lower node power consumption than performing CSI-based sensing.

For example, if the sensing application is a life safety critical sensing application, the RF system may also be configured to perform RSSI-based sensing. For example, if the sensing application is idle detection and the lights should be turned off automatically when idle, the RF system may be configured to perform CSI-based sensing. This may allow detection details when the sensing area becomes occupied, e.g. allowing for improved personnel counting and classification. The RF system may be configured to perform RSSI-based sensing after obtaining the context information to reduce power consumption.

The sensing application may also provide context by including requirements of the sensing application, such as standby power requirements of the sensing application, such as a currently required standby power level.

If low latency is required, for example for life safety critical sensing applications requiring fast reaction, the RF system may be configured to perform RSSI-based sensing. RSSI-based sensing may allow sensing events to be detected faster than CSI-based sensing. The delay requirement (e.g. lighting control delay requirement) may depend on e.g. the state of the sensing area. For example, the sensing region may be occupied or unoccupied. In the case where the sensing region is empty, for example, in response to a person entering the sensing region, a node in the form of a luminaire may need to be turned on in less than 200 ms. To achieve a delay of less than 200ms, RSSI-based sensing may be used. On the other hand, if higher accuracy is required, e.g. if the room is occupied and certain details need to be determined, CSI-based sensing may be performed. This may allow for reduced false negative detection.

The radio power consumption requirements may include, for example, standby power management requirements. Standby mode may include, for example, not performing the primary function of a node. The node may be configured to perform RF-based sensing, for example, in a standby mode, i.e. when it does not perform its main function. For example, the node may be a luminaire that does not provide light in standby mode, but performs RF-based sensing. In this case, the standby power consumed by the node corresponds to the power consumed by the node when processing the RF sense messages (e.g., including receiving the RF sense messages and processing them, e.g., using an analysis algorithm). Performing RSSI-based sensing requires less processing effort than performing CSI-based sensing, which may allow for reduced power consumption and meet radio power consumption requirements.

The radio transmit power requirements may include, for example, limits of transmit power, such as radio interference due to high transmit power. For example, in a hospital room, a medical machine may be interfered with by wireless interference such that the allowable RF transmit power for performing RF-based sensing may be limited based on the radio transmit power requirements.

The radio beam shape requirements and the radio receive beam shaping requirements relate to how the beam requirements for performing RF based sensing are shaped. The beam may be, for example, a narrow beam or a divergent beam. The beam shape may affect the sensing area that may be covered by performing RF-based sensing. A narrow beam may, for example, allow coverage of a longer sensing area, while a divergent beam may, for example, allow coverage of a wider sensing area. The use of a narrow beam may allow RF-based sensing to be performed between two nodes that are farther away from each other than if a divergent beam was used. Furthermore, the use of narrow beams allows for focusing the RF signal to a specific direction, such that beamforming in this way may allow for providing a higher signal quality to the receiving node.

The requirements such as standby power management requirements or radio transmit power requirements may depend on, for example, the current location of the RF system and/or the at least one node, and/or the current date (such as a certain time of day or a certain day of the week). The current location of the at least one node may also comprise, for example, a relative location between the nodes that may affect the transmission length between the nodes.

The current mode of operation of the respective node may include, for example, performing a primary function, such as providing illumination, performing RF-based sensing, and/or operating in a standby mode.

Environmental effects may include, for example, radio interference, low SNR, and/or background noise levels. For example, the environmental impact may be caused based on humidity in the air, smoke, cigarette smoke, the current state of the sensing area (e.g., occupied or unoccupied), and the like. The RF system may be configured to perform CSI-based sensing if the current SNR is above a threshold SNR and RSSI-based sensing if the current SNR is below the threshold SNR. For example, the threshold SNR may be selected such that it corresponds to the SNR when CSI-based sensing fails on many subcarriers.

Considering the bandwidth currently available in an RF system may allow compensating for a certain lack of sampling rate, e.g. due to missing RF messages. Because CSI is less susceptible to noise than RSSI, performing CSI-based sensing may allow for compensation for lack of sampling rate at low available bandwidth or high background noise levels, which may occur due to low available bandwidth or high background noise levels. Background noise may be caused, for example, by noise sources such as microwave ovens or streaming televisions. Background noise may degrade the SNR of RF-based sensing and increase the number of lost RF messages between nodes, i.e. decrease the sampling rate or the effective messaging rate, respectively.

The properties of the sensing region may include, for example, shape, regularity, material, prototypes of the room in which the nodes are arranged, or any other property of the sensing region. This allows the properties of the room to be considered to determine whether it is beneficial to perform CSI-based sensing, RSSI-based sensing, or a combination thereof.

The error event detection rate requirements may include a false positive rate (false positive rate) versus a false negative rate (false negative rate).

The RF system may be configured to perform RSSI-based sensing, for example, during a growth phase of poor plant growth when RF signals with high transmit power are transmitted in the sensing region. Because RSSI-based sensing may allow RF-based sensing to be performed at lower transmit power than CSI-based sensing, RSSI-based sensing may be preferred in such a growth phase of plants.

The RF system may be configured to first perform RSSI-based sensing and cascade to CSI-based sensing. The RF system may be configured to use RSSI-based sensing as a trigger to perform CSI-based sensing, i.e., CSI-based sensing may be performed by the RF system upon detection of a sensing event of the RSSI-based sensing. This allows RSSI-based sensing to cascade to CSI-based sensing, which may allow for reduced power consumption while maintaining a high level of accuracy.

The RF system may be configured to perform RF-based sensing based on CSI and RSSI simultaneously. Performing RF-based sensing simultaneously based on CSI and RSSI may allow for improved detection performance. The RF system may perform RF-based sensing simultaneously by, for example, performing CSI-based sensing by one node and RSSI-based sensing by another node (e.g., using Zigbee or BLE). Alternatively, a single node may perform RF-based sensing based on CSI and RSSI, e.g., using WiFi. Performing RF-based sensing by a single node based on CSI and RSSI may include interleaving time intervals during which CSI-based sensing is performed and time intervals during which RSSI-based sensing is performed.

The at least two nodes may include a transmitting node, a CSI receiving node, and an RSSI receiving node. The CSI receiving node may be configured to perform RF-based sensing, i.e. CSI-based sensing, based on CSI. The RSSI receiving node may be configured to perform RF based sensing based on RSSI, i.e. RSSI based sensing. Performing RF-based sensing by the CSI receiving node based on CSI and the RSSI receiving node based on RSSI may allow for improved detection performance. The transmitting node, CSI receiving node and RSSI receiving node may be arranged in and/or define a sensing area. The transmitting node may be configured to transmit RF messages to the CSI receiving node and the RSSI receiving node to perform RF-based sensing.

The transmitting node may be configured to transmit the same RF message to the CSI receiving node and the RSSI receiving node to perform RF-based sensing. This may allow RF-based sensing to be performed by both the CSI receiving node and the RSSI receiving node simultaneously and improve detection performance and/or reduce power consumption of the RF system. The transmitting node may be configured to transmit the RF message such that both the CSI receiving node and the RSSI receiving node may receive and process the RF message. The RF message may be, for example, a WiFi RF message.

The sensing region may be predefined or formed by the node, e.g. defined based on the location of the node.

The transmitting node may be configured to transmit and receive the same RF messages transmitted to the CSI receiving node and the RSSI receiving node to perform RF-based sensing by the transmitting node. This may allow RF-based doppler sensing to be performed by the transmitting node. The transmitting node may comprise a transceiver unit and an antenna configured for transmitting the same RF message to the CSI receiving node and the RSSI receiving node, and for receiving the same RF message for performing RF based sensing by the transmitting node. The RF-based sensing performed by the transmitting node may be, for example, RF-based doppler sensing, which listens for echoes in the sensing region, i.e., reflected RF messages are received and analyzed by the transmitting node. The transmitting node may perform RF-based doppler sensing by analyzing a combination of doppler and micro-doppler shifts of reflected RF messages generated by a complex object, such as a human body including different elements such as torso, legs, and arms, and micro-doppler shifts generated by different elements of the complex object. The doppler effect can be visualized in a heat map, while the x-axis shows the speed of movement, and the y-axis can indicate the distance between the echo-causing object and the transmitting node.

The CSI receiving node may be configured to perform CSI-based sensing in a CSI sensing region. The RSSI receiving node may be configured to perform RSSI-based sensing in the RSSI sensing region. The CSI sensing region and the RSSI sensing region may be included in the sensing region. In the overlapping sensing region, at least a portion of the CSI sensing region may overlap with the RSSI sensing region. Performing RF-based sensing by CSI and RSSI receiving nodes in the overlapping sensing region may allow for more details and improved RF-based sensing.

The RSSI receiving node may be selected from at least two nodes for performing RF based sensing in the sensing region such that the overlapping sensing region is maximized and/or the region of interest is within the overlapping region. Alternatively or additionally, CSI receiving nodes may be selected from at least two nodes for performing RF-based sensing in the sensing region such that the overlapping sensing region is maximized and/or the region of interest is within the overlapping region. Alternatively or additionally, the RSSI receiving node and CSI receiving node may be selected from at least two nodes for performing RF-based sensing in the sensing region such that the overlapping sensing region is maximized and/or the region of interest is within the overlapping region, i.e. such that the overlapping sensing region is maximized, such that the region of interest is within the overlapping region, or such that the overlapping sensing region is maximized and the region of interest is within the overlapping region. The RSSI receiving node and/or CSI receiving node is selected from at least two nodes for performing RF-based sensing in the sensing region such that the overlapping sensing region is maximized, which may allow optimizing the use of nodes with different capabilities. The RSSI receiving node and/or CSI receiving node is selected from at least two nodes for performing RF-based sensing in the sensing region such that the region of interest is within the overlap region, which may allow for improved detection performance and accuracy in the region of interest by using both RSSI and CSI.

The RF system may include a CSI set of nodes performing RF-based sensing based on CSI. The CSI receiving node may be included in a CSI group. Alternatively or additionally, the RF system may include an RSSI group of nodes that perform RF-based sensing based on RSSI. The RSSI receiving nodes may be included in an RSSI group.

The CSI groups and/or RSSI groups may be formed based on the current context (e.g., based on the capabilities and/or location of the node). The current context may additionally or alternatively include current environmental impact, e.g., there may be too low SNR for some nodes to perform CSI-based sensing, so that the nodes may perform RSSI-based sensing.

The RF system may be configured to perform RSSI-based sensing for motion or occupancy detection. This may allow for transmission of RF messages at reduced transmission power compared to performing CSI-based sensing. The RF system may be configured to transmit the RF message at a reduced transmission power when performing RSSI-based sensing, as compared to performing CSI-based sensing.

The RF system may be configured to determine one or more properties of the sensing region based on performing RSSI-based sensing and/or CSI-based sensing. The RF system may be configured to analyze a degree of difference between results obtained from performing the RSSI-based sensing and the CSI-based sensing to determine one or more properties of the sensing region. This may allow for improved determination of, for example, whether the sensing area is larger or smaller, whether the object is within the sensing area, etc. The RF system may be configured to utilize a predetermined classification of the sensing region, e.g., based on a fingerprint of the sensing region. The sensing region classifications may include, for example, larger sensing regions, smaller sensing regions, open spaces, closed spaces, kitchens, living rooms, and the like.

The RF system may be configured to perform RF-based sensing to monitor plant growth. Monitoring the growth of plants may include, for example, monitoring the biomass of the leaves for changes, and/or monitoring the root structure, for example, in a growth medium such as rock wool. Alternatively or additionally, monitoring the growth of the plant may include monitoring the humidity of the leaves, e.g., due to unwanted condensation, and/or environmental conditions in the vicinity of the plant, e.g., millimeter wave RF based sensing may be used to infer humidity. The RF system may be configured to perform CSI-based sensing, RSSI-based sensing, or a combination thereof such that negative effects on plant growth are minimized. The plant may be, for example, a soybean plant. RF systems may be used, for example, in vertical agriculture. The RF system may be configured to selectively perform CSI-based sensing or RSSI-based sensing depending on a growth stage of the plant. For example, RSSI-based sensing may use lower transmit power, which may yield plant health benefits. The RF system may be configured to perform RF-based sensing, for example, depending on the relative position of the node to the plant selecting CSI-based sensing or RSSI-based sensing.

At least two of the nodes may have different capabilities. The different capabilities may include different transmit capabilities, different receive capabilities, different processing capabilities, or a combination thereof. For example, one of the nodes may be of a different type, older than the other node, corrupted, etc. The RSSI receiving node may be configured to perform RF-based sensing, e.g., based on RSSI alone, e.g., it may be able to receive RF messages of 2.4GHz alone without OFDM.

In a further aspect of the invention, a method for performing RF-based sensing in a sensing region by at least two nodes is presented. The method comprises the following steps:

-determining a current context for performing radio frequency based sensing, and

-configuring at least one node for performing radio frequency based sensing based on CSI, RSSI or a combination thereof based on the current context.

The method may include one or more of the following steps:

simultaneously performing radio frequency based sensing based on CSI and RSSI,

transmitting, by the transmitting node, the same radio frequency message to a CSI receiving node for performing radio frequency based sensing based on CSI and to an RSSI receiving node for performing radio frequency based sensing based on RSSI,

Transmitting and receiving by the transmitting node the same radio frequency message transmitted to the CSI receiving node and the RSSI receiving node for performing radio frequency based sensing by the transmitting node,

performing radio frequency based sensing in a CSI sensing region, wherein the CSI sensing region is comprised in a sensing region,

performing radio frequency based sensing in an RSSI sensing area, wherein the RSSI sensing area is comprised in the sensing area,

providing that at least a portion of the CSI sensing region overlaps the RSSI sensing region in the overlapping sensing region,

defining an overlap sensing region maximization,

specifying that the region of interest is within the overlap region,

-determining one or more properties of the sensing area based on performing radio frequency based sensing based on RSSI and/or CSI, and

-performing radio frequency based sensing for monitoring the growth of plants.

In a further aspect of the invention, a computer program product for performing RF-based sensing in a sensing region by at least two nodes is presented. The computer program product comprising program code means for causing a processor to perform the method according to claim 12, claim 13 or any embodiment of the method when the computer program product is run on a processor.

In a further aspect, a computer readable medium having stored the computer program product of claim 14 is presented. Alternatively or additionally, the computer-readable medium may cause a computer program product according to any embodiment of the computer program product to be stored.

It shall be understood that the RF system of claim 1, the method of claim 12, the computer program product of claim 14, and the computer readable medium of claim 15 have similar and/or identical preferred embodiments, in particular as defined in the dependent claims.

It is to be understood that the preferred embodiments of the invention may also be any combination of the dependent claims or the above embodiments with the corresponding independent claims.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.

Drawings

In the following figures:

figure 1 schematically and exemplarily shows a node for an RF system,

fig. 2 schematically and exemplarily shows a first embodiment of an RF system with three nodes, which perform RF-based sensing simultaneously based on CSI and RSSI,

FIG. 3 schematically and exemplarily shows a second embodiment of an RF system with two nodes performing RF-based sensing based on CSI or RSSI based on a plant growth phase, and

Fig. 4 illustrates an embodiment of a method for performing RF-based sensing.

Detailed Description

Fig. 1 schematically and exemplarily shows a node of an RF system, such as a Connected Lighting (CL) system 100 or 100' presented in fig. 2 and 3, respectively. In the following, before providing details regarding the functionality of CL systems 100 and 100', we describe details of an exemplary node 10 that may be used in CL system 100 or 100'.

Node 10 includes a control unit 12, a transceiver unit 14, and an antenna array 16. Instead of an antenna array, a single antenna may also be included in the node.

The control unit 12 includes a computer readable medium in the form of a processor 18 and a memory 20.

In this embodiment, transceiver unit 14 includes a WiFi transceiver 22 for transmitting and receiving RF signals including WiFi-based RF messages (i.e., wiFi RF messages). In other embodiments, the transceiver units may also exchange data based on one or more other communication protocols (e.g., thread, cellular radio, bluetooth, or Bluetooth Low Energy (BLE), or any other communication protocol). The transceiver unit may further comprise two or more transceivers configured to exchange data based on different communication protocols.

Transceiver unit 14 transmits and receives RF signals to and from nodes of CL system 100 or 100', respectively, using antenna array 16 to wirelessly exchange data including RF messages between the nodes and perform RF-based sensing. RF signals transmitted from one node to another may be subject to interference by, for example, tangible entities (e.g., users) within the transmission path between the nodes. The RF signals disturbed by the user may be analyzed in the control unit 12 for performing RF based sensing.

The memory 20 of the control unit 12 stores a computer program product for operating the CL system 100 or 100', respectively. The computer program product comprises program code means for causing the processor 18 to perform a method for operating the CL system 100 or the CL system 100', respectively, when the computer program product is run on the processor 18, e.g. a method for performing RF-based sensing in a sensing area by two nodes as presented in fig. 4. The memory 20 further comprises a computer program product for operating the node 10 and optionally the entire CL system 100 or 100', respectively, e.g. for controlling the functions of the node and the functions of the node controlling the CL system 100 or 100', e.g. for providing illumination and for performing RF-based sensing.

Fig. 2 shows an embodiment of an RF system in the form of a CL system 100 comprising three nodes 26, 28 and 30 for performing RF-based sensing. In other embodiments, the RF system may have a different number of nodes, such as two, four, or more.

Node 26 is a WiFi router and nodes 28 and 30 are luminaires for providing light and for performing RF-based sensing. In other embodiments, the node may also be of another type and perform another function, such as a switch, a light, a bridge, etc. The node 26 is connected to an external server 200. The external server 200 may be used to control the nodes 26, 28, 30 of the CL system 100, for example by transmitting control signals to one or more of them. The external server may be, for example, a server of a Building Management System (BMS). In this embodiment, the external server 200 only exchanges data directly with the node 26. Node 26 may then exchange data with other nodes 28 and 30 to control their functions.

In this embodiment, the locations of nodes 26, 28, and 30 define a sensing region 40 in which RF-based sensing is performed by CL system 100. Further, the locations of nodes 26 and 28 define a CSI sensing region 50 in which CSI-based sensing is performed, and the locations of nodes 26 and 30 define an RSSI sensing region 60 in which RSSI-based sensing is performed. The overlap sensing region 70 is formed by the overlap of the CSI sensing region 50 and the RSSI sensing region 60. In other embodiments, the sensing region may be predefined.

CL system 100 is used to perform RF-based sensing in sensing region 40 based on current context based on CSI, RSSI, or a combination thereof. The function of CL system 100 is explained below.

The node 26 of the CL system 100 determines the current context for performing RF-based sensing and configures the nodes 26, 28, and 30 for performing RF-based sensing based on the current context. In this embodiment, the current context includes the sensing application, the current locations of nodes 26, 28, and 30, and the current capabilities of nodes 26, 28, and 30. In other embodiments, the current context may also include, for example, a latency requirement, a radio power consumption requirement, a radio transmit power requirement, a radio beam shape requirement, a radio receive beam forming requirement, a current location of the RF system, a current date, an environmental impact, a current mode of operation of the at least one node, a current available bandwidth in the RF system, a current attribute of the sensing region, and an error event detection rate requirement.

The sensing application is determined based on a sensing event to be detected or a sensing event to be detected by performing RF-based sensing. The current locations of nodes 26, 28, and 30 may be determined based on time of flight (TOF) measurements between nodes 26, 28, and 30. The current capabilities of the nodes depend on their type, age, and other attributes of the node. In this embodiment, nodes 26, 28, and 30 have different capabilities. The node 30 is limited in its processing power because it can only perform RSSI-based sensing and cannot perform CSI-based sensing. Nodes 26 and 28 may perform CSI-based sensing and/or RSSI-based sensing.

CL system 100 configures node 28 as a CSI receiving node for performing CSI-based sensing and configures node 30 as an RSSI receiving node for performing RSSI-based sensing. In other embodiments, other configurations are also possible, e.g., both nodes are configured as CSI receiving nodes or RSSI receiving nodes.

CL system 100 then performs RF-based sensing based on both CSI and RSSI simultaneously, i.e., by performing CSI-based sensing by node 28 and by performing RSSI-based sensing by node 30.

Thus, node 26 acts as a transmitting node that transmits the same RF message 34 (i.e., wiFi RF message) to CSI receiving node 28 and RSSI receiving node 30 to perform RF-based sensing. In other embodiments, the transmitting node may be configured to transmit and receive the same RF message transmitted to the CSI receiving node and the RSSI receiving node to perform RF-based sensing by the transmitting node.

In this embodiment, CSI receiving node 28 performs CSI-based sensing in CSI sensing region 50, and RSSI receiving node 30 performs RSSI-based sensing in RSSI sensing region 60. The CSI sensing region 50 and the RSSI sensing region 60 partially overlap in the overlap sensing region 70. The overlapping sensing region 70 allows CSI data and RSSI data to be obtained by performing RF-based sensing, and may further improve detection performance. Thus, it may be beneficial to provide the nodes such that the region of interest is within the overlap region and/or such that the overlap region is maximized, for example, by changing the relative positions of the nodes to each other.

In other embodiments, the RSSI receiving node and/or CSI receiving node may be selected from a plurality of nodes of the RF system for performing RF-based sensing in the sensing region such that the overlapping sensing region is maximized and/or the region of interest is within the overlapping region.

In still other embodiments, the RF system may be configured to determine one or more properties of the sensing region based on performing RF-based sensing based on RSSI and/or CSI.

Fig. 3 shows a second embodiment of an RF system in the form of a CL system 100'. CL system 100' has similar functionality as CL system 100 in that it determines a current context and performs RF-based sensing based on CSI, RSSI, or a combination thereof based on the current context.

In contrast to the first embodiment of CL system 100, CL system 100' performs RF-based sensing for monitoring the growth of plants 80 in sensing region 40. In this embodiment, the current context includes a growth phase of the plant 80 in the sensing region 40, i.e., the decision whether to perform CSI-based sensing, RSSI-based sensing, or a combination thereof takes into account the current growth phase of the plant 80.

CL system 100' includes a plurality of nodes, two of which nodes 26 and 28 are shown. Node 26 is a WiFi router and node 28 is a luminaire for providing illumination. Depending on the growth phase, nodes 26 and 28 perform RF-based sensing based on CSI, RSSI, or a combination thereof, in order to avoid negative health problems of the plant during growth.

Hereinafter, further embodiments are presented, but without the figures.

In further embodiments, RSSI-based sensing or CSI-based sensing is performed depending on the currently required standby power level of the node (e.g., a lamp within the sensing area).

Data processing for RSSI-based sensing requires considerably less processing effort than for CSI-based sensing. The RSSI consists of single byte data points, whereas the CSI may contain multiple data points, e.g., 64 complex values including real and imaginary parts. RSSI directly describes the attenuation of an RF signal. Thus, RSSI is a metric that may directly indicate the movement or presence of a person. In contrast, CSI describes the properties of an RF channel extracted from multiple subcarriers of an RF signal (e.g., a WiFi signal). In other words, CSI is not a direct measurement of RF signal attenuation and thus requires a complex additional processing step of the measured data before motion can be inferred based on CSI. Thus, RSSI-based sensing may consume less energy than CSI-based sensing when the luminaire is in a standby mode, in which its primary function (i.e., providing illumination) is not performed. A luminaire for performing CSI-based sensing may require, for example, an iMXRT1060 secondary microcontroller in the luminaire to run the sensing analysis algorithm, while RSSI-based sensing may be performed using an ESP32 microcontroller. The iMXRT1060 microcontroller consumes more energy than the ESP32 microcontroller.

The currently required standby power level may be provided, for example, on a regular basis (e.g., based on the location of the RF system). For example, in california, stringent standby power requirements are provided to the luminaire, particularly whenever the luminaire is in standby mode, i.e. when the light output is off. If the light output is turned on, the standby power requirement does not apply. To meet standby power requirements, such as the state energy regulations (building energy standards-title 24), RSSI-based sensing may be performed when the light output of the luminaire is off, and CSI-based sensing may be performed when the light output is on (e.g., when the sensing area is occupied).

Compared to CSI-based sensing, RSSI-based sensing has a better SNR because it integrates all the multipaths in the channel between the nodes (i.e., the transmitting node and the receiving node). This may allow for further reduction of the transmitting radio power of the luminaire, while still maintaining sufficient RSSI-based sensing performance. The lower transmit radio power may be beneficial for human health, for example, in sensing applications where the transmitting node is located very close to a human, for example, a node in the form of a floor lamp.

In another further embodiment, CSI-based sensing is performed instead of RSSI-based sensing when the wireless network is congested or noisy and thus does not allow for an efficient sampling rate between luminaires.

In yet another embodiment, the available wireless bandwidth as well as the background noise level may be considered when deciding in real time whether to perform CSI-based or RSSI-based sensing in the sensing region.

RSSI-based sensing relies solely on an overall or aggregate RF signal consisting of all wireless multipaths between nodes. To perform RSSI-based sensing, in this embodiment, the node uses only a single carrier containing a time sequence of RSSI data. Such RSSI data is processed in an RSSI-based sensing analysis algorithm. On the other hand, a typical CSI data stream may consist of 64 subcarriers.

The CSI-based sensing analysis algorithm may compensate to some extent for the lack of sampling rate caused by WiFi networks. For example, when an RF message including an expected RSSI sample or CSI sample fails to arrive on time, both the RSSI-based sensing analysis algorithm and the CSI-based sensing analysis algorithm perform a fall-back (fall-back) that involves various types of interpolation of data. The richer data in CSI provides better references that CSI-based sensing analysis algorithms can utilize in their interpolation, while the simpler nature of the RSSI data makes any interpolation more sensitive to noise present in the RF channel. Although the different multipath components extracted from the CSI data stream have lower SNR than the RSSI-based sensing, this can be compensated by CSI metrics that provide the sensing algorithm with 64 times more values of the same single received RF message than the RSSI metrics provide.

The presence of continuous wireless background noise may accompany or cause congestion. For example, noise sources such as microwave ovens or video streaming TVs may deteriorate the SNR between nodes performing RF-based sensing and reduce the effective messaging rate between them, for example, due to an increased number of messages missed by the receiving node.

If SNR degradation due to background noise (e.g., radio interference) is modest, CSI-based sensing may be preferred over RSSI-based sensing because CSI-based sensing may allow compensation for degradation in the effective messaging rate due to loss of RF messages at the receiving node or due to unsuccessful transmission of scheduled RF messages by the transmitting node. If the background noise reaches such a high level that the SNR of a single CSI subcarrier is compromised to such an extent that the CSI-based sensing analysis algorithm fails on a threshold number of subcarriers, CSI-based sensing becomes too error-prone and RSSI-based sensing is preferably performed.

According to another further embodiment, RSSI-based sensing is performed instead of CSI-based sensing whenever the sensing application is fast, low-delay motion detection. RSSI is a much simpler metric than CSI. The RSSI is a value extracted at the receiving node when receiving an RF message, regardless of the payload type of the RF message. The RSSI is extracted in the same way from any short or long RF message or even any RSSI-based sense specific message, e.g. whereby the transmitting node reports its own previously received RSSI data to its sense group. The RSSI may be represented by only a single byte of data. The signed 8bit representation covers the desired RSSI resolution of +20dBm to-100 dBm.

While RSSI may use one single byte of data for each message, CSI, on the other hand, may provide a complex value of approximately 52 times to the CSI-based sensing analysis algorithm for each RF message. Thus, CSI-based sensing requires higher throughput. This increases the delay of motion detection by CSI-based sensing compared to RSSI-based sensing.

In contrast, the simplicity of RSSI-based metrics generally makes RSSI-based sensing analysis algorithms more prone to error, especially if the target is a short detection time window, such as 200ms for occupancy-based lighting control. Within a 200ms detection time window, there may be too little RSSI data associated with event detection that is available for correlating or confirming detection of a sensed event for an RSSI-based sensing analysis algorithm. For example, only a few RSSI samples may actually be generated between nodes within a 200ms time window. The fewer samples that are available, the more affected the RSSI-based sensing analysis algorithm (in the case where one of the samples is affected by noise over a 200ms period). For example, fewer samples makes it more difficult for an RSSI-based sensing analysis algorithm to determine whether a first sensing link is being affected by noise alone, rather than human motion, while a second sensing link in the same sensing region is being affected by human motion.

Thus, RSSI-based sensing may be preferable whenever fast sensing delay is critical, even at the cost of higher false positive rates. For example, whenever a node in the form of a luminaire is currently turned off (i.e., no light is provided), a fast response of the RF system is desired to ensure that the luminaire is turned on in less than 200ms after a person has entered the sensing area.

This low-delay excitation is not required whenever the sensing area is currently occupied by, for example, an office worker. In this case, CSI-based sensing is preferably performed to produce maximum context awareness and minimize false negatives. For example, unlike RSSI-based sensing, CSI-based sensing allows tracking of respiratory motion patterns, and thus real presence detection of a person sitting very quietly on a sofa looking at TV, for example, can be reliably performed.

For life safety critical sensing applications requiring low latency, RSSI-based sensing may also be preferred. For example, RF-based sensing may act as a trigger for activation of a secondary alarm system, for example to alert workers in a warehouse that a forklift is approaching. For these life safety related applications, the risk of missing a sensed event or reacting too late is higher than the dissatisfaction associated with accidental false triggers.

The RF system may be configured to perform null sensing instead of occupancy sensing. For example, california energy regulations (building energy standards-title 24) prescribe the sensing of the absence of certain rooms, such as private offices and conference rooms, i.e. the lighting must always be manually turned on by the user via a switch, and the lighting must be automatically turned off when the room is empty. For rooms with empty sensing, CSI-based sensing is preferably performed whenever the room is empty. This allows the RF system to collect detailed insight about the entering person. For example, in a conference room, when they enter the room, i.e. when they are in an upright body position before sitting down, it may have been analyzed which person or persons entered the room. CSI-based sensing may determine the number of people entering and differentiate between adults and children, or may identify the body shape of an individual, for example via 60GHz WiFi. For example, this information may be used to activate a preferred lighting scene. Once this information has been obtained, the RF system may perform RSSI-based sensing, for example, to reduce power consumption.

In yet another embodiment, an RF system includes a transmitting node, a CSI receiving node in the form of a luminaire, and an RSSI receiving node in the form of a luminaire. Both the CSI receiving node and the RSSI receiving node are co-located in the same sensing region and receive the same RF message transmitted by the transmitting node.

The nodes of the RF system may be, for example, different generations of luminaires. The CSI receiving node may be, for example, a second generation luminaire capable of performing CSI-based sensing, while the RSSI receiving node is a first generation luminaire capable of performing RSSI-based sensing only, since its processing power is only sufficient to run RSSI-based sensing analysis algorithms, not CSI-based sensing analysis algorithms. In this embodiment, it is described how RF-based sensing can be performed when a mix of at least one legacy node and at least one updated more capable node are present in the same sensing region.

The transmitting node transmits an RF message, such as a WiFi sense message. The CSI receiving node receives the RF message and uses it to perform CSI-based sensing while the RSSI receiving node located in the same sensing area receives the same WiFi sensing message but uses it to perform RSSI-based sensing. In this embodiment, the WiFi sense message transmitted by the transmitting node is intentionally selected so that it can be successfully received and processed not only by the CSI receiving node, but also by the RSSI receiving node (i.e., legacy node). For example, an RSSI receiving node may be able to receive only 2.4GHz without OFDM, while a transmitting node and CSI receiving node may also be able to use 5GHz and OFDM.

It may be advantageous to assign a set or subset of nodes in the sensing area to perform RSSI-based sensing, either for pure needs, e.g. because one of the receiving nodes lacks processing power for performing CSI-based sensing, or because other conditions, e.g. having too low SNR at one of the receiving nodes, do not allow for reliable performance of CSI-based sensing.

Where RSSI-based sensing is performed purely by necessity, the RSSI receiving node may, for example, comprise an 802.11b WiFi radio that uses old and inexpensive WiFi variants that do not utilize OFDM. Because the RSSI receiving node is unable to use the subcarriers, it is essentially unable to determine CSI. In this case, to allow the RSSI receiving node to perform RF-based sensing, the transmitting node also needs to use 802.11b in order to transmit RF messages that can be processed by the RSSI receiving node.

For example, in the case where RSSI-based sensing is performed due to a condition, SNR may be compromised due to a long physical distance between a transmitting node and an RSSI receiving node, or due to a wireless noise source (e.g., a microwave oven) located near the RSSI receiving node. Since RSSI combines all multipaths, performing RSSI-based sensing allows in principle an advantage over performing CSI-based sensing in that each individual multipath extracted by CSI receives only a small fraction of the wireless energy transmitted by the transmitting node, but the human to be detected that partially interrupts the wireless path still absorbs the same relative 3dB amount, thus indicating the useful signal contraction that a human is present.

In summary, three scenarios of how a mix of nodes with different capabilities perform RF-based sensing based on CSI, RSSI, or a combination thereof can be distinguished.

The first and most likely scenario is that the RSSI receiving node does not have sufficient processing power, e.g., including dual microprocessors required to run CSI-based sensing analysis algorithms. For example, the RSSI receiving node may comprise an ESP32 microcontroller. In this case, the RSSI receiving node is in principle able to extract CSI, but is unable to perform CSI-based sensing due to lack of processing power for RF-based sensing event detection. Accordingly, the RSSI receiving node preferably performs RSSI-based sensing.

In the second scenario, the RSSI receiving node does not have sufficient processing power at all to extract CSI. The RSSI receiving node may comprise, for example, an ESP8266 microcontroller. The RSSI receiving node may still understand the RF message transmitted by the transmitting node. Further, in this case, the RSSI receiving node performs RSSI-based sensing and extracts RSSI, and the CSI receiving node performs CSI-based sensing and extracts CSI from the same RF message.

In a third scenario, the transmitting node transmits more complex RF messages than the receiving node can understand or interpret, respectively. The receiving node cannot extract neither CSI nor RSSI. In this case, it is not possible for the CSI receiving node and the receiving node to process the same RF message at all, because the receiving node cannot process the RF message.

When the same RF message is transmitted by the transmitting node and RSSI-based sensing is performed by the RSSI receiving node and CSI-based sensing is performed by the CSI receiving node, an overlapping sensing region is formed in the vicinity of the transmitting node, in which the RSSI sensing region and the CSI sensing region overlap. In a further distance to the transmitting node, RSSI-based sensing is performed only in the RSSI sensing area or CSI-based sensing is performed in the CSI sensing area. In the case that the sensing region includes an additional node (e.g., a fourth node) capable of performing only RSSI-based sensing, the RF system may select whether the fourth node is used to perform RSSI-based sensing or whether the RSSI receiving node is used to perform RSSI-based sensing. The RF system may be configured to select one of the nodes such that a maximum overlap is obtained between the RSSI sensing region and the CSI sensing region, i.e., such that the overlapping sensing region is maximized. Furthermore, the overlapping sensing region may be selected such that it coincides with the region of interest (e.g., sofa) in which the event is expected to be sensed. This may allow the RF system to, for example, analyze the degree of difference between RSSI-based sensing and CSI-based sensing to determine whether the properties of the sensing region (such as an object, e.g., furniture) in the overlapping sensing region have changed. This embodiment is also applicable in addition to taking care of legacy nodes, and may be applicable to all nodes with different capabilities, such as high-end nodes and base nodes with which CSI-based sensing can be performed (e.g. lower cost lamps only capable of performing RSSI-based sensing). The RF system may include a high-end node and a base node.

In another further embodiment, the RSSI-based sensing and the CSI-based sensing are performed in a room-form sensing area. RSSI data obtained from performing the RSSI-based sensing is compared with CSI data obtained from performing the CSI-based sensing to determine one or more attributes (e.g., prototypes) of the room.

In this embodiment, RF-based sensing is performed using both RSSI-based sensing that analyzes only the aggregated multipath RF signals and CSI-based sensing that analyzes at various multipath levels to estimate properties of the room, such as shape, prototype, regularity, material type of the room, or other properties of the room. The degree of difference between the RSSI data and the CSI data including the RSSI sensing results and the CSI sensing results is analyzed to determine the properties of the room, for example, by inference. For example, if the time series of RSSI and CSI are very similar in terms of the variations suffered by the RF signal in the presence and absence of humans, this means that the multipath behavior within the sensing region is very limited, indicating that the room may be very large and empty. If a large amount of difference is observed between the RSSI sensing result and the CSI sensing result, this means that the first set or subset of multipaths is better than the second subset of the remaining multipaths.

Prototypes of rooms may include predetermined classifications, such as open spaces (e.g., open offices), compact spaces (e.g., private offices surrounded by walls), semi-open spaces (e.g., open kitchen-living rooms), and rooms containing numerous load-bearing walls (e.g., indicating that the room is located at a corner of a building).

In further embodiments, RSSI-based sensing is performed during certain growth phases of the horticultural plant. RSSI-based sensing may be performed to monitor growth, and/or RF-based sensing may be performed in consideration of the current growth stage of the horticultural plant.

RSSI-based sensing allows RF signals to be transmitted at lower transmit radio power while still maintaining adequate RSSI-based sensing performance because it integrates all multipaths in the channel between nodes, and thus may have better SNR. Lower emitted radio power may produce plant health benefits, such as in applications where the emitting node (e.g., emitting luminaire) is positioned very close to the plant, such as for vertical agro-horticultural luminaires.

RF-based sensing can be used to monitor plant growth. In certain growth phases of plants, it may be advantageous to minimize their RF exposure caused by the nodes performing RF-based sensing. For example, for soybean plants, RSSI-based sensing during the seedling stage is preferred to minimize RF exposure, while CSI-based sensing may be performed during the post-growth stage, which is less affected by wireless radiation, to provide more detailed sensing data than RSSI. It may also be preferable to select the location of the receiving node to be in the vicinity of the plant, rather than as the transmitting node. Further, RSSI-based sensing may be performed by nodes in the vicinity of the plant.

Fig. 4 illustrates an embodiment of a method 400 of performing RF-based sensing by two nodes in a sensing region. These nodes may be nodes of, for example, RF systems, such as CL system 100 or CL system 100' presented in fig. 2 and 3, respectively.

In step 402, a current context for performing RF-based sensing is determined. The current context may include, for example, sensing applications, latency requirements, radio power consumption requirements, radio transmit power requirements, radio beam shape requirements, radio receive beam forming requirements, current location of the RF system, current location of one or more nodes (e.g., their relative positions to each other), current date (e.g., day of the week and/or time of day), current mode of operation of at least one node (e.g., standby mode), environmental impact (e.g., radio interference), bandwidth currently available in the RF system, current capabilities of one or more nodes, current attributes of the sensing area, and error event detection rate requirements. In other embodiments, the current context may also include other factors, such as the growth stage of the plant in the sensing area. These factors may be determined in different ways, for example, a sensing application may be determined based on the selection, which will be executed by the node. Other factors, such as current data, may be determined based on the calendar. For example, the current location may be determined based on a Global Positioning System (GPS) and/or other methods for determining the current location, such as determining a distance between nodes based on time of flight (TOF) measurements to determine the relative location of the nodes.

In step 404, one of the nodes is configured to perform RF-based sensing based on CSI, RSSI, or a combination thereof based on the current context, i.e., to select whether the node performs RF-based sensing based on CSI, RSSI, or a combination thereof, e.g., interleaving CSI and RSSI in different time intervals. The factors of the current context are weighted according to the CSI-RSSI selection algorithm. The CSI-RSSI selection algorithm may be a rule-based algorithm, a machine learning algorithm, or any other type of algorithm that allows CSI, RSSI, or a combination thereof to be selected to perform RF-based sensing based on the current context. Since the current context is determined in real-time, the nodes can be configured in real-time to accommodate the current situation and optimize RF-based sensing for the current situation.

In step 406, RF-based sensing is performed. Depending on how the node is configured in step 404, RF-based sensing is performed based on CSI, RSSI, or a combination thereof, i.e., RF-based sensing is performed based on CSI and RSSI simultaneously. This allows for improved detection performance and/or reduced power consumption.

In step 408, an action is performed in response to detecting the sensing event by performing RF-based sensing. For example, if the sensing area is a room and the sensing event to be detected by RF-based sensing is the occupancy of the room, the action may be to turn on the illumination if the occupancy of the room is detected. In other embodiments, other actions may be performed in response to detecting a sensed event, such as providing a warning or alarm signal.

In step 410, one or more properties of the sensing region are determined based on performing CSI-based sensing and RSSI-based sensing. In this embodiment, the attribute of the sensing region is determined based on the difference of CSI data and RSSI data obtained by simultaneously performing CSI-based sensing and RSSI-based sensing. Step 410 is optional.

In other embodiments, more than two nodes (e.g., three nodes) may be used to perform RF-based sensing. In this case, for example, the transmitting node may transmit the same RF message to the CSI receiving node for performing CSI-based sensing and the RSSI receiving node for performing RSSI-based sensing. The transmitting node may also receive the same RF messages it transmits for performing RF-based sensing. This may allow RF-based doppler sensing to be performed.

CSI-based sensing may be performed in a CSI sensing region. The CSI sensing region may be included in the sensing region. RSSI-based sensing may be performed in the RSSI sensing region. The RSSI sensing region may be included in the sensing region. It may be provided that, in the overlapping sensing region, at least a portion of the CSI sensing region overlaps with the RSSI sensing region. Further, it may be provided that overlapping sensing areas are maximized, for example, based on the node or node location selected for performing RF-based sensing. The region of interest may also be defined to be within the overlapping region.

In still other embodiments, RF-based sensing may be performed to monitor plant growth.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. For example, it is possible to operate the invention in embodiments where the RF system is a heating, ventilation and air conditioning (HVAC) system, a smart home system, or any other type of RF system.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

In the claims, the words "comprise" and "comprising" do not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

A single unit, processor or device may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Operations performed by one or several units or devices (e.g., determining a current context for performing RF-based sensing, configuring at least one node for performing RF-based sensing based on CSI, RSSI, or a combination thereof based on the current context, performing RF-based sensing based on both CSI and RSSI, etc.) may be performed by any other number of units or devices. The operations and/or methods may be implemented as program code means of a computer program and/or as dedicated hardware.

A computer program product may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium, provided together with or as part of other hardware; but may also be distributed in other forms, such as via the internet, ethernet, or other wired or wireless telecommunication systems.

Any reference signs in the claims shall not be construed as limiting the scope.

The invention relates to performing RF-based sensing based on CSI, RSSI, or a combination thereof based on a current context. A current context for performing RF-based sensing is determined, and at least one of the two nodes of the RF system is configured to perform RF-based sensing based on CSI, RSSI, or a combination thereof based on the current context. The current context may be determined in real-time. This may allow for improved detection performance and/or reduced power consumption in real time.

Claims (15)

1. A radio frequency system (100; 100 ') comprising at least two nodes (26, 28, 30) for performing radio frequency based sensing in a sensing region (40, 50, 60, 70), wherein the radio frequency system (100; 100') is configured for determining a current context for performing radio frequency based sensing and, based on the current context, configuring at least one of the nodes (26, 28, 30) for performing radio frequency based sensing based on channel state information, a received signal strength indicator, or a combination thereof.

2. The radio frequency system (100; 100') according to claim 1, wherein the current context comprises one or more of:

the sensing application is performed in a manner that,

the delay requirement is set up in such a way that,

the radio power consumption requirements are that,

the radio transmission power requirements are set,

the radio beam shape requirements,

the radio reception beamforming requirements,

-a current location of the radio frequency system (100; 100'),

-a current location of at least one of said nodes (26, 28, 30),

the current date of the day,

a current mode of operation of at least one of the nodes (26, 28, 30),

the effect of the environment is to be taken care of,

-bandwidth currently available in said radio frequency system (100; 100'),

current capabilities of at least one of the nodes (26, 28, 30),

-a current property of the sensing area (40),

-error event detection rate requirement, and

-a growth phase of the plants (80) in the sensing area (40).

3. The radio frequency system (100; 100 ') according to claim 1 or 2, wherein the radio frequency system (100; 100') is configured to perform radio frequency based sensing simultaneously based on channel state information and a received signal strength indicator.

4. The radio frequency system (100) according to at least one of claims 1 to 3, wherein the at least two nodes (26, 28, 30) comprise:

-a transmitting node (26),

-a channel state information receiving node (28) for performing radio frequency based sensing based on channel state information, and

-a received signal strength indicator receiving node (30) for performing radio frequency based sensing based on the received signal strength indicator.

5. The radio frequency system (100) according to claim 4, wherein the transmitting node (26) is configured for transmitting the same radio frequency message (34) to the channel state information receiving node (28) and the received signal strength indicator receiving node (30) for performing radio frequency based sensing.

6. The radio frequency system (100) according to claim 5, wherein the transmitting node (26) is configured for transmitting and receiving the same radio frequency message (34) transmitted to the channel state information receiving node (28) and the received signal strength indicator receiving node (30) for radio frequency based sensing by the transmitting node (26).

7. The radio frequency system (100) according to at least one of claims 4 to 6, wherein the channel state information receiving node (28) is configured for performing radio frequency based sensing based on channel state information in a channel state information sensing region (50), wherein the received signal strength indicator receiving node (30) is configured for performing radio frequency based sensing based on received signal strength indicators in a received signal strength indicator sensing region (60), wherein the channel state information sensing region (50) and the received signal strength indicator sensing region (60) are comprised in the sensing region (40), and wherein at least a portion of the channel state information sensing region (50) overlaps with the received signal strength indicator sensing region (60) in an overlapping sensing region (70).

8. The radio frequency system (100) according to claim 7, wherein the received signal strength indicator receiving node (30) is selected from the at least two nodes (26, 28, 30) for performing radio frequency based sensing in the sensing region (40); -selecting from said at least two nodes (26, 28, 30) said channel state information receiving node (28) for performing radio frequency based sensing in said sensing region (40); or selecting the received signal strength indicator receiving node (28) and the channel state information receiving node (26) from the at least two nodes (26, 28, 30) for performing radio frequency based sensing in the sensing region (40) such that the overlapping sensing region (70) is maximized and/or the region of interest is within the overlapping region (70).

9. The radio frequency system (100; 100 ') according to at least one of claims 1 to 8, wherein the radio frequency system (100; 100') is configured to perform radio frequency based sensing based on a received signal strength indicator and/or channel state information to determine one or more properties of the sensing region (40).

10. The radio frequency system (100 ') according to at least one of claims 1 to 9, wherein the radio frequency system (100') is configured to perform radio frequency based sensing to monitor the growth of plants (80).

11. The radio frequency system (100; 100') according to at least one of claims 1 to 10, wherein at least two of the nodes (26, 28, 30) have different capabilities.

12. A method for performing radio frequency based sensing in a sensing region by at least two nodes, comprising the steps of:

-determining a current context for performing radio frequency based sensing, and

-based on the current context, configuring at least one of the nodes for performing radio frequency based sensing based on channel state information, a received signal strength indicator, or a combination thereof.

13. The method of claim 12, wherein the method comprises one or more of the following steps:

simultaneously performing radio frequency based sensing based on channel state information and a received signal strength indicator,

transmitting, by the transmitting node, the same radio frequency message to a channel state information receiving node for performing radio frequency based sensing based on channel state information and to a received signal strength indicator receiving node for performing radio frequency based sensing based on a received signal strength indicator,

transmitting and receiving by the transmitting node the same radio frequency message transmitted to the channel state information receiving node and the received signal strength indicator receiving node for performing radio frequency based sensing by the transmitting node,

Performing radio frequency based sensing in a channel state information sensing region, wherein the channel state information sensing region is comprised in the sensing region,

performing radio frequency based sensing in a received signal strength indicator sensing region, wherein the received signal strength indicator Fu Gan region is comprised in the sensing region,

defining that at least a portion of the channel state information sensing region overlaps with the received signal strength indication Fu Gan region in an overlapping sensing region,

defining that the overlapping sensing area is maximized,

specifying that the region of interest is within the overlap region,

-determining one or more properties of the sensing region based on performing radio frequency based sensing based on the received signal strength indicator and/or channel state information, and

-performing radio frequency based sensing for monitoring the growth of plants.

14. A computer program product for performing radio frequency based sensing in a sensing area (40) by at least two nodes (26, 28, 30), wherein the computer program product comprises program code means for causing a processor (18) to carry out the method as claimed in claim 12 or 13 when the computer program product is run on the processor (18).

15. A computer readable medium (20) having stored the computer program product according to claim 14.