Forwarding Channel State Information in Passive Wireless Sensing Networks

Abstract

The present invention relates to performing sensing in a wireless network based on detecting changes in received radio frequency signals, and in particular performing such sensing based on analyzing channel state information. The wireless network includes at least one node of a first type that performs analysis of channel state information associated with wireless signals transmitted in the wireless network and a plurality of nodes of a second type. One or more wireless signals are transmitted between the plurality of nodes of the second type, and at least one of the nodes determines channel state information associated with the one or more wireless signals and transmits at least a portion of the determined channel state information to one of the at least one node of the first type. The node of the first type receives at least a portion of the determined channel state information and analyzes it to determine a sensing value.

Description

[Technical Field]

[0001] The present invention relates to methods, devices and systems for performing passive wireless sensing in wireless networks based on detecting changes in received radio frequency signals, and in particular to performing such sensing based on analyzing channel state information. [Background technology]

[0002] A wireless network, such as a Wi-Fi network, consists of multiple nodes that communicate with each other using radio frequency (RF) signals. RF signals exchanged between nodes can be affected due to absorption, reflection, and scattering of such RF signals by objects, such as walls, doors, and, if present, human or animal bodies. Recently, Wi-Fi devices have begun to use Channel State Information (CSI), which describes how wireless signals propagate in a wireless channel between a transmitter and a receiver at a certain carrier frequency along multiple spatial paths. Because the amplitude and phase of CSI are affected by multipath effects, including amplitude attenuation and phase shift of wireless signals, CSI therefore captures the wireless characteristics of the nearby environment.

[0003] A time series of multiple CSI measurements captures how wireless signals move through space in the time, frequency, and spatial domains. Therefore, these signals may be analyzed to enable a variety of different wireless sensing applications. For example, CSI amplitude fluctuations in the time domain have different patterns for different people, activities, gestures, etc., and can be used for presence detection, motion detection, activity recognition, etc.

[0004] Analyzing RF signals can require powerful hardware, e.g., in terms of computational power and / or memory. This is especially true if the analysis is based on CSI, which can be voluminous, e.g., if the link has many subcarrier frequencies. Indeed, in modern Wi-Fi networks using MIMO-OFDM (Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing), CSI measurements result in a three-dimensional matrix of complex values ​​representing amplitude attenuation and phase shift over time. Summary of the Invention [Problem to be solved by the invention]

[0005] Increasing the number of nodes in such wireless networks to improve coverage of the area to be monitored and to enable improved sensing can make such systems very expensive, as multiple nodes are required. [Means for solving the problem]

[0006] In a first aspect, a method for performing sensing in a wireless network is provided. The wireless network includes at least one node of a first type and a plurality of nodes of a second type. The at least one node of the first type performs analysis of channel state information (CSI) associated with wireless signals transmitted in the wireless network. Therefore, this node requires certain hardware, e.g., a certain amount of memory and / or a certain amount of computing power, to be able to perform this analysis. The nodes of the second type are different from the nodes of the first type. The nodes of the second type do not need to be able to perform analysis of the CSI, but this does not exclude such nodes having powerful hardware requirements, e.g., for performing other functions.

[0007] The method includes transmitting one or more wireless signals between a plurality of nodes of a second type. These signals may be transmitted solely for the purpose of performing the analysis, but these signals may also include data transmission between the nodes for other purposes. At least one of the plurality of nodes of the second type determines CSI associated with the one or more wireless signals. Thereafter, the at least one of the plurality of nodes of the second type transmits at least a portion of the determined CSI to a node of the at least one node of the first type. Thereafter, the node of the at least one node of the first type receives at least a portion of the determined CSI and analyzes the received at least a portion of the CSI. Based on the analysis, a sensing value is determined.

[0008] In this manner, the second type node can determine (i.e., extract) the CSI and transmit (i.e., forward) at least a portion of the CSI, and at least one node of the first type can process this received at least a portion of the CSI. This allows CSI associated with signals transmitted between multiple nodes of the second type to be used in performing sensing without requiring these nodes of the second type to perform the analysis themselves. As a result, the second type nodes can be used to improve the coverage and / or quality of sensing performed in a wireless network while reducing hardware requirements compared to utilizing only first type nodes, which can be more costly. In other words, a system may include a first type node A located in area A and two second type nodes B1 and B2 located in area B, where areas A and B do not overlap. Prior art indicates that node A may determine the CSI of a first signal transmitted from node B1 to node A and, optionally, the CSI of a second signal transmitted from node B2 to node A. The CSI associated with the first signal and optionally the second signal may be analyzed by node A to determine a sensing value, such as presence. Thus, the sensing value is determined based on the CSI associated with signals transmitted from node(s) in area B to nodes in area A. Thus, sensing is performed for a combination of at least a portion of area A and at least a portion of area B. In this example, when presence sensing is performed, if a person moves in area B, this can be detected (assuming the first or second signal is affected by the person moving in area B), but if a person moves in area A, this will also trigger such detection (again assuming the first or second signal is affected by the person moving in area A). Furthermore, coverage in area B may not be optimal.

[0009] Continuing with this example, the present invention provides that, alternatively or in addition to the first and optional second signals being transmitted as described above, one or more third signals are transmitted between nodes in area B, e.g., from B1 to B2, and that the CSI of these one or more third signals is determined by B2, in this example, based on signals it receives from B1. The determined CSI (or a portion thereof) related to these one or more third signals is then transmitted from the node that determined it, in this example, node B2, to node A. Node A can then process (a portion of) the received CSI, where this CSI relates to signals transmitted within area B only between nodes within area B. In this example, the CSI analyzed by node A relates to signals transmitted from node B1 to node B2. In this way, presence can be detected in area B rather than in a combination of areas A and B, and sensing coverage in area B can be improved.

[0010] The second type node may compress data, e.g., CSI, to take up a smaller payload during transmission, filter or remove noise across multiple previously determined CSIs, and / or extract certain minor features across multiple previously determined CSIs. For example, the minor features may indicate maximum / minimum amplitude / deviation / phase shifts. If these maximum / minimum values ​​are not significantly different from those previously received by the second type node, the node may simply avoid processing the CSI and use its computational resources for other purposes. The level and / or type of preprocessing performed by the second type node may be determined based on the node's computational capabilities, its battery power level, power consumption, memory usage, additional functions the node is performing, etc., and based on the computational capabilities of at least one node of the first type. Furthermore, the type of sensing performed (e.g., requiring maximum detection latency), wireless network conditions, etc., may determine the extent to which preprocessing is performed.

[0011] In one embodiment, the method further includes transmitting one or more additional wireless signals between the at least one node of the first type and one or more nodes of the plurality of nodes of the second type, the at least one node of the first type determining additional CSI associated with the one or more additional wireless signals and analyzing the CSI, and determining a sensing value based further on the analysis of the additional CSI.

[0012] This allows sensing to be performed based on both the CSI extracted for the wireless signals transmitted between the plurality of nodes of the second type and the wireless signals transmitted between at least one node of the first type and one or more nodes of the second type, thereby further improving the coverage and / or quality of the sensing performed. The sensing value may relate to one characteristic, such as detecting the presence of a person, or may relate to multiple characteristics, such as detecting the presence of a person and detecting the presence of an animal. Each such characteristic may be determined based on the CSI associated with the signals transmitted between the plurality of nodes of the second type, the wireless signals transmitted between at least one node of the first type and one or more nodes of the second type, or both. For example, the status of a house may be determined as occupied or unoccupied based on the CSI associated with the wireless signals transmitted between at least one node of the first type and one or more nodes of the second type, and the CSI associated with the signals transmitted between the plurality of nodes of the second type may be used to determine the status of a single room (or multiple rooms, together or individually) as occupied or unoccupied.

[0013] In this embodiment, optionally, the one or more further wireless signals include a transmission of at least a portion of the determined CSI. Thus, at least one node of the first type receives at least a portion of the CSI and further determines the further CSI based on this transmission of at least a portion of the CSI. This allows the same message carrying at least a portion of the determined CSI to be used to determine the further CSI, thereby more efficiently utilizing wireless network and / or other resources.

[0014] In a further embodiment, the sensing value indicates movement of an object in a sensing zone, the sensing zone being defined by the locations of at least a plurality of nodes of a second type. The plurality of nodes of the second type may be located in a room of a building, such as a house. In this case, the sensing zone may be determined as the room (or a portion thereof). This is useful for motion detection, including presence detection, and thus the movement or presence of a person, an animal (such as a pet), or other object may be detected.

[0015] In another embodiment, determining, by at least one of the plurality of nodes of the second type, CSI associated with the one or more wireless signals includes extracting a plurality of time series values ​​from a communication stack of the at least one of the plurality of nodes of the second type. Determining, by the at least one of the plurality of nodes of the second type, CSI associated with the one or more wireless signals may further include selecting a frequency or periodicity at which the CSI is extracted, or what CSI is extracted (e.g., which sub-frequencies / carriers).

[0016] Optionally, determining, by at least one node of the plurality of nodes of the second type, CSI associated with one or more wireless signals further includes selecting at least a portion of the CSI to be transmitted from the determined CSI. In such a case, selecting at least a portion of the CSI to be transmitted from the determined CSI may be done based on at least one of a state of the wireless network, a sensing value to be determined, a capability of the node transmitting the CSI and / or a capability of the node receiving the CSI, and a size of the extracted CSI in terms of processing, memory, or network requirements. This may be advantageously used to avoid using too many resources, for example, to avoid flooding the wireless network with messages carrying CSI data.

[0017] In another embodiment, the analysis of at least some of the received CSI performed by the at least one node of the first type differs from the analysis of the further CSI performed by the at least one node of the first type. This may be useful, for example, when the area covered by the signals transmitted between the plurality of nodes of the second type (e.g., a particular room or floor of a building) differs from the area covered by the further wireless signals (e.g., the general perimeter of a building, such as a residence). Alternatively or additionally, the sensed values ​​may be different (e.g., detecting the presence of a person versus performing breathing detection).

[0018] In yet another embodiment, a node of at least one node of a first type controls which at least one node of a plurality of nodes of a second type determines CSI associated with the wireless signal. Advantageously, this allows the node of the first type to orchestrate CSI determination, e.g., by changing over time which nodes of the second type perform CSI determination for sensing in a particular area (e.g., periodically). This is particularly beneficial when there is a need to limit the amount of traffic in the wireless network and sensing may be restricted to a particular area.

[0019] In yet another embodiment, the at least one node of the first type controls a characteristic for transmitting at least a portion of the CSI determined by the at least one node of the plurality of nodes of the second type to the at least one node of the first type. The characteristic may include one or more of: how often the at least a portion of the CSI is transmitted, which portion of the CSI is transmitted, when the CSI is transmitted, and how the CSI is transmitted (e.g., in what format, together with other data, etc.).

[0020] In a particularly advantageous embodiment, the wireless network includes a plurality of nodes of a first type, and the method further includes selecting one or more nodes of the plurality of nodes of the first type to which at least a portion of the determined CSI is transmitted, such that the selected one or more nodes of the plurality of nodes of the first type receive at least a portion of the determined CSI and analyze the received at least a portion of the CSI. This allows for balancing which nodes of the first type perform the analysis, and may be used, inter alia, when each of the nodes of the first type performs a different type of analysis (e.g., to determine different characteristics of the sensed value).

[0021] According to a second aspect, there is provided a computer program comprising instructions which, when said program is executed by a processor, cause the processor to carry out a method according to the first aspect and any of its embodiments.

[0022] According to a third aspect, there is provided a system including a wireless network, the wireless network including at least one node of a first type and a plurality of nodes of a second type, the at least one node of the first type performing analysis of CSI associated with wireless signals transmitted in the wireless network, and the plurality of nodes of the second type being different from the first type.

[0023] Each of the plurality of nodes of the second type transmits one or more wireless signals between the plurality of nodes of the second type, determines CSI associated with the one or more wireless signals, and transmits at least a portion of the determined CSI to a node of the at least one node of the first type.

[0024] Further, each of the at least one node of the first type receives at least a portion of the determined CSI, and analyzes the received at least a portion of the CSI, and determines a sensing value based on the analysis.

[0025] According to a fourth aspect, there is provided a device for use as a first type node in the system according to the third aspect, the device including: an input to receive at least a portion of the determined CSI from the second type node; and a processor to analyze the received at least a portion of the CSI and to determine a sensing value based on the analysis. [Brief explanation of the drawings]

[0026] These and other aspects of the invention will be apparent from and further elucidated, by way of example, with reference to the following drawings, in which corresponding elements are indicated by the same reference numerals, and in which: [Figure 1] 1 shows a first system according to the prior art, with limited sensing coverage; [Figure 2] 2 shows a second system according to the prior art that requires the use of many expensive nodes. [Figure 3] 1 illustrates a system for sensing in a wireless network according to a first aspect. [Figure 4] The characteristics of the system shown in FIG. [Figure 5] 1 illustrates an embodiment of a system according to a first aspect, including a plurality of nodes of a first type. [Figure 6] We present the characteristics of a system containing many nodes of the second type. [Figure 7] 7 illustrates an embodiment of a system according to a first aspect that addresses the characteristics illustrated in FIG. 6. [Figure 8] 1 is a block diagram of a method for sensing in a wireless network. DETAILED DESCRIPTION OF THE INVENTION

[0027] FIG. 1 illustrates a building, in this example a residence 100, including a first area 115, such as the first floor, and a second area 120, such as the floor above the first floor. A first wireless network sensing system 105 according to the prior art is installed in the residence 100. The system 105 includes a first type node 110 and two second type nodes 120 and 130. The first type node 110 processes channel state information (CSI) associated with wireless links within the wireless network sensing system 110 and, based on this analysis, can determine whether a person is present. The second type nodes 120 and 130 do not analyze CSI, as they may not be able to do so due to, for example, memory or processing power limitations or other limitations. The second type nodes may be relatively less expensive than the first type nodes due to reduced requirements given that they do not need to be able to perform CSI analysis.

[0028] An advantage of this first system 105 according to the prior art is that it is relatively inexpensive, since only a single node 110 of a first type is required. However, the signals transmitted within the system 105 that can be used to perform sensing based on analyzing the CSI are limited to a first signal 112 and a second signal 114 associated with the links between the node 110 of the first type and a first node 120 of a second type and a second node 130 of the second type, respectively. As a result, based on analyzing the CSI, a first person A and a third person C can be detected within the residence 100, but a second person B may not be detected because the second person does not sufficiently influence the links 112, 114.

[0029] FIG. 2 illustrates a second prior art wireless network sensing system 205. In this system 205, there are three nodes 110, 220, and 230 of a first type. Each of these nodes can analyze the CSI associated with the link between each node. Here, there is a third signal 225 associated with the link between a second node 220 of the first type and a third node 230 of the first type. Therefore, a second person B can also be detected separately from the system 105 of FIG. 1 because of the affected link 225.

[0030] An advantage of this second system according to the prior art 205 is that it provides a larger coverage for sensing in the home 100. However, it is relatively expensive when compared to the first wireless network sensing system according to the prior art 105 of Figure 1, since it requires more nodes of the first type.

[0031] FIG. 3 illustrates a system 305 according to one embodiment of the first aspect. The system 305 includes a first node 310 of a first type and two nodes 320, 330 of a second type. Similar to the system illustrated in FIG. 1, the first node of the first type analyzes CSI associated with each of the links 312, 314 it has with the first and second nodes 320, 330 of a second type. The second type node cannot analyze CSI associated with the link 325 between them, but there is a signal transmitted between the first and second nodes 320, 330 of the second type. Determination of the CSI of this signal 325 may be performed by one of the second type nodes 220, 230.

[0032] 4, CSI associated with one or more wireless signals transmitted between the second-type nodes 320, 330 is extracted, and at least a portion of the CSI is transmitted by one of the second-type nodes 330 to the first-type node 310 via link 410. Whether one or both second-type nodes transmit CSI data can be determined in various manners, for example, each second-type node may autonomously decide whether to transmit extracted CSI to the first-type node 310, or the second-type nodes 320, 330 may decide this together, e.g., in a master / slave configuration, or the first-type node 110 may poll or instruct the second-type nodes 220, 230 to transmit at least a portion of the extracted CSI.

[0033] The first type node 310 then analyzes at least a portion of the received CSI associated with wireless signals transmitted between the second type nodes 320, 330. In this manner, the system 305 can, for example, detect all three persons A, B, and C shown in Figure 3 while requiring only one node of the first type. This provides the low cost advantages of the system 105 shown in Figure 1 and the large coverage advantages of the system 205 shown in Figure 2.

[0034] While in the system 305 shown in Figure 4, only a single node of the first type is required, there may be multiple nodes 310, 540 of the first type, as shown in the system 505 of Figure 5. One of the nodes 330 of the second type transmits at least a portion of its CSI to one or both of the nodes 310, 540 of the first type. The node of the first type to which at least a portion of the extracted CSI is transmitted may be determined autonomously by the node of the second type, or may be predetermined, configured by a user, set by the node of the first type, etc. Transmitting at least a portion of the determined CSI to only one node of the first type reduces the bandwidth required in the wireless network to transmit this data. By transmitting at least a portion of the determined CSI to multiple nodes of a first type, each such node of the first type may track changes in the determined CSI over time, or each such node may use a different algorithm to perform sensing, for example, a first node of the first type may determine a value indicative of a person moving around an area based on analysis of the extracted CSI, while a second node of the first type may determine a value indicative of a person breathing, and further these determined values ​​may be used together to determine a value indicative of the presence of a person.

[0035] The examples provided in FIGS. 3-5 show only two nodes of the second type. Following the example provided in FIG. 5, there may be more than one node of the first type. In fact, there may be any number of nodes of the first type, as long as there is at least one node. There may also be any number of nodes of the second type, i.e., at least two nodes. A system 605 including four nodes 620, 630, 650, and 660 of the second type is shown in FIG. 6. In this system 605, each node of the second type creates a link with each of the other nodes of the second type, and further, the node 310 of the first type creates a link with each of the nodes 620, 630, 650, and 660 of the second type. While this may create a large number of links 60, for example, it may enable extending the coverage area in which sensing is performed, but it may also have adverse effects on the improved sensing, such as increased lag or dropped messages, if the wireless network becomes congested.

[0036] 7, the system 605 of FIG. 6 is shown again, but now with a limited number of links between devices used for sensing. In this example, three distinct wireless signals 710, 720, 730 are transmitted between two nodes 620, 630, 650, 660 of a second type, respectively. Optionally, the first node 620 may transmit a message to the second node 650, which may determine CSI associated with its link with the first node and transmit at least a portion of this CSI to the third node 630 as a message 720. The third node 630 may then determine CSI associated with its link with the second node 650 and transmit at least a portion of this CSI, along with CSI data received from the second node 650 associated with the link 710 with the first node 620, to the fourth node 660. Finally, the fourth node 660 may determine CSI associated with the link 730 with the third node and transmit 740 at least a portion of this determined CSI to the first type node. Furthermore, the fourth node 660 will transmit CSI data received from the third node, including the CSI data the third node received from the second node, to the first type node. The first type node 310 may then analyze the CSI data associated with each of the three links 710, 720, and 730 described above. Furthermore, the first type node 310 may extract and analyze CSI data associated with the link 740 with the fourth node 660 of the second type.

[0037] 8, a block diagram illustrating an example of a method 800 for performing sensing in a wireless network is shown. The wireless network includes at least one node of a first type that performs an analysis of CSI associated with wireless signals transmitted in the wireless network, and a plurality of nodes of a second type different from the first type. The method includes: transmitting 810 one or more wireless signals between a plurality of nodes of a second type; determining 820, by at least one node of the plurality of nodes of a second type, CSI associated with the one or more wireless signals; transmitting 830 at least a portion of the determined CSI by at least one node of the plurality of nodes of the second type to a node of the at least one node of the first type; receiving 840 at least a portion of the determined CSI by a node of the at least one node of a first type; Analyzing 850, by a node of at least one node of a first type, at least a portion of the received CSI, and determining 860 a sensing value based on the analysis.

[0038] Various embodiments of the present invention may be implemented as a program product for use with a computer system, the program of the program product defining the functions of the embodiments (including the methods described herein). In one embodiment, the program may be contained on various non-transitory computer-readable storage media; as used herein, the phrase "non-transitory computer-readable storage medium" includes all computer-readable media, with the sole exception of transitory propagating signals. In another embodiment, the program may be contained on various transitory computer-readable storage media. Exemplary computer-readable storage media include, but are not limited to, (i) non-writable storage media in which information is permanently stored (e.g., a read-only memory device internal to a computer, such as a CD-ROM disk readable by a CD-ROM drive, a ROM chip, or any type of non-volatile solid-state semiconductor memory), and (ii) writable storage media in which changeable information is stored (e.g., a flash memory, a floppy disk inside a diskette drive or hard disk drive, or any type of random-access solid-state semiconductor memory). The computer program may be executed on a processor.

[0039] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will be further understood that as used herein, the terms "comprise" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0040] Corresponding structure, materials, acts, and equivalents of all means-plus-function or step-plus-function elements in the following claims are intended to include any structure, material, or acts for performing the function in combination with other claim elements as specifically claimed. The description of the embodiments of the present invention has been presented for illustrative purposes, but is not intended to be exhaustive or limited to the disclosed form of implementation. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The embodiments were chosen and described to best explain the principles and some practical applications of the invention, and to enable others skilled in the art to understand the invention in terms of various embodiments with various modifications as suited to the particular uses contemplated.

Claims

1. 1. A method for performing sensing in a wireless network, the wireless network including at least one node of a first type that performs analysis of channel state information associated with wireless signals transmitted in the wireless network, the wireless network further including a plurality of nodes of a second type different from the first type, the method comprising: transmitting one or more wireless signals between the plurality of nodes of the second type; determining, by at least one node of the plurality of nodes of the second type, channel state information associated with the one or more wireless signals; transmitting, by the at least one node of the plurality of nodes of the second type to a node of the at least one node of the first type, one or more further wireless signals including at least a portion of the determined channel state information; receiving, by the node of the at least one node of the first type, the one or more further wireless signals; determining, by the node of the at least one node of the first type, further channel state information associated with the one or more further wireless signals; - analyzing, by the node of the at least one node of the first type, both the received at least part of the channel state information and the further channel state information, and determining a sensing value based on the analysis; A method comprising:

2. The method of claim 1 , wherein the sensing value indicates movement of an object in a sensing zone, the sensing zone being defined by positions of at least a plurality of nodes of the plurality of nodes of the second type.

3. 3. The method of claim 1, wherein determining, by the at least one node of the plurality of nodes of the second type, channel state information associated with the one or more wireless signals comprises extracting a plurality of time series values ​​from a communication stack of the at least one node of the plurality of nodes of the second type.

4. 4. The method of claim 3, wherein determining, by the at least one node of the plurality of nodes of the second type, channel state information associated with the one or more wireless signals includes selecting a frequency or periodicity at which the channel state information is extracted.

5. 5. The method of claim 3, wherein determining, by the at least one node of the plurality of nodes of the second type, channel state information associated with the one or more wireless signals comprises selecting from the determined channel state information the at least some of the channel state information to be transmitted.

6. 6. The method of claim 5, wherein selecting the at least a portion of the channel state information to be transmitted from the determined channel state information is performed based on at least one of a state of a wireless network, a sensing value to be determined, and an amount of channel state information to be extracted.

7. 7. The method of claim 1, wherein an analysis of the received at least part of the channel state information performed by the node of the at least one node of the first type differs from an analysis of the further channel state information performed by the node of the at least one node of the first type.

8. 8. The method of claim 1, wherein the node of the at least one node of the first type controls which at least one node of the plurality of nodes of the second type determines channel state information associated with the wireless signal.

9. 9. The method of claim 1, wherein the node of the at least one node of the first type controls a property of transmitting at least a portion of the determined channel state information by the at least one node of the plurality of nodes of the second type to the node of the at least one node of the first type.

10. The wireless network includes a plurality of nodes of the first type, and the method comprises: selecting one or more nodes of the plurality of nodes of the first type to which the at least some of the determined channel state information is to be transmitted, such that the selected one or more nodes of the plurality of nodes of the first type receive the at least some of the determined channel state information and analyze the received at least some of the channel state information; The method of claim 1 , comprising:

11. A computer program comprising instructions which, when executed by a processor, cause the processor to carry out the method of any one of claims 1 to 10.

12. 1. A system including a wireless network, the wireless network comprising: at least one node of a first type configured to analyze channel state information associated with wireless signals transmitted in the wireless network; a plurality of nodes of a second type different from the first type; Including, Each of the plurality of nodes of the second type comprises: transmitting one or more wireless signals between the plurality of nodes of the second type; determining, by at least one node of the plurality of nodes of the second type, channel state information associated with the one or more wireless signals; and transmitting, by the at least one node of the plurality of nodes of the second type to a node of the at least one node of the first type, one or more further wireless signals including at least a portion of the determined channel state information; and Each of the at least one node of a first type comprises: receiving the one or more further wireless signals; determining further channel state information associated with the one or more further wireless signals; and analyzing both the received at least part of the channel state information and the further channel state information, and determining a sensing value based on the analysis. system.

13. 13. A device for use as the first type node in the system of claim 12, the device comprising: an input for receiving said at least a portion of said determined channel state information from said second type node; a processor for analyzing both the received at least part of the channel state information and the further channel state information, and for determining a sensing value based on the analysis; Including, the device.

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