CHANNEL STATE INFORMATION FORWARDING IN PASSIVE WIRELESS SENSING NETWORK

Abstract

The invention relates to performing sensing in a wireless network based on detecting changes in received radio frequency signals and in particular to performing such sensing based on analyzing channel state information. The wireless network comprises at least one node of a first type arranged for performing analysis of channel state information related to 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 these nodes determines channel state information, related to the one or more wireless signals, and transmits at least part of the determined channel state information to a node of the at least one node of the first type. This node of the first type receives the at least part of the determined channel state information and analyzes it to determine a sensing value.

Claims

1. A method for performing sensing in a wireless network, the wireless network comprising at least one node of a first type arranged for performing analysis of channel state information related to wireless signals transmitted in the wireless network, the wireless network further comprising a plurality of nodes of a second type, different from the first type, and 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, related to the one or more wireless signals transmitted between the plurality of nodes of the second type; transmitting one or more further wireless signals, 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, comprising at least part of the determined channel state information related to the one or more wireless signals transmitted between the plurality of nodes of the second type; receiving the one or more further wireless signals, by the node of the at least one node of the first type, comprising the at least part of the determined channel state information related to the one or more wireless signals transmitted between the plurality of nodes of the second type; determining, by the node of the at least one node of the first type, further channel state information, related to the one or more further wireless signals transmitted between 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; 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 related to the one or more wireless signals transmitted between the plurality of nodes of the second type and, the further channel state information; and determining a sensing value based on said analysis.

2. (canceled)

3. (canceled)

4. The method according to claim 1, wherein the sensing value is indicative of movement of an object in a sensing zone, said sensing zone defined by at least the position of multiple of the plurality of nodes of the second type.

5. The method according to claim 1, wherein the determining channel state information, related to the one or more wireless signals, by the at least one node of the plurality of nodes of the second type comprises extracting multiple time-series values from a communication stack of the at least one node of the plurality of nodes of the second type.

6. The method according to claim 5, wherein the determining channel state information, related to the one or more wireless signals, by the at least one node of the plurality of nodes of the second type further comprises selecting a frequency or periodicity at which the channel state information is extracted.

7. The method according to claim 5, wherein the determining channel state information, related to said one or more wireless signals, by the at least one node of the plurality of nodes of the second type further comprises selecting the at least part of the channel state information to be transmitted from the determined channel state information.

8. The method according to claim 7, wherein the selecting the at least part 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 the wireless network, the sensing value to be determined, and amount of the channel state information that is extracted.

9. The method according to claim 1, wherein the 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 is different from the analysis of the further channel state information performed by the node of the at least one node of the first type.

10. The method according to 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 related to said wireless signal.

11. The method according to claim 1, wherein the node of the at least one node of the first type controls a characteristic of the transmitting at least part 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.

12. The method according to claim 1, wherein the wireless network comprises multiple nodes of the first type, and wherein the method further comprises: selecting one or more of the multiple nodes of the first type to which the at least part of the determined channel state information is transmitted, such that the selected one or more of the multiple nodes of the first type receive the at least part of the determined channel state information and analyze the received at least part of the channel state information.

13. A computer program product comprising instructions which, when the program is executed by a processor, cause the processor to carry out the method according to claim 1.

14. A system comprising a wireless network, the wireless network comprising: at least one node of a first type arranged for performing analysis of channel state information related to wireless signals transmitted in the wireless network, and a plurality of nodes of a second type, different from the first type, wherein each of the plurality of nodes of the second type are arranged for: 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, related to the one or more wireless signals transmitted between the plurality of nodes of the second type; and transmitting one or more further wireless signals, 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, comprising at least part of the determined channel state information related to the one or more wireless signals transmitted between the plurality of nodes of the second type; wherein each of the at least one node of a first type are further arranged for: receiving the one or more further wireless signals comprising the at least part of the determined channel state information related to the one or more wireless signals transmitted between the plurality of nodes of the second type; determining further channel state information related to the one or more further wireless signals transmitted between the at least one node of the plurality of nodes of the second wireless signals transmitted between the 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 and analyzing both the received at least part of the channel state information related to the one or more wireless signals transmitted between the plurality of nodes of the second type and, the further channel state information, and determining based on said analysis, a sensing value.

15. A device for use as a node of the first type in the system according to claim 14, the device comprising: an input for receiving the at least part of the determined channel state information from a node of the second type; and a processor arranged for analyzing both the received at least part of the channel state information and the further channel state infomation and further for, based on said analysis, determining a sensing value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] These and other aspects of the invention are apparent from and will be further elucidated, by way of example, with reference to the drawings, in which:

[0027] FIG. 1 shows a first system according to the prior art, with limited sensing coverage;

[0028] FIG. 2 shows a second system according to the prior art, which requires the use of many expensive nodes;

[0029] FIG. 3 shows a system for performing sensing in a wireless network according to the first aspect;

[0030] FIG. 4 illustrates a characteristic of the system illustrated in the FIG. 3;

[0031] FIG. 5 illustrates an embodiment of a system according to the first aspect, comprising multiple nodes of the first type;

[0032] FIG. 6 illustrates a characteristic of a system comprising many nodes of the second type;

[0033] FIG. 7 illustrates an embodiment of the system according to the first aspect, addressing the characteristic illustrated in FIG. 6; and

[0034] FIG. 8 is a block diagram of method for performing sensing in a wireless network.

[0035] Corresponding elements in the drawings are denoted by the same reference numeral.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] FIG. 1 shows a building, in this example a house 100, comprising a first area 115, such as a ground floor, and a second area 120, such as a floor above the ground floor. In this house 100, a first wireless network sensing system according to the prior art 105 is installed. The system 105 comprises a node of a first type 110 and two nodes of a second type 120, 130. The node of the first type 110 is able to process channel state information, CSI, related to wireless links within the wireless network sensing system 110 and based on this analysis determine whether a person is present. The nodes 120, 130 of the second type do not analyze CSI, as they may not be able to due to, for example, limitations in memory or processing power or other limitations. Nodes of the second type may be relatively cheaper than nodes of the first type, due to the reduced requirements in view of these not needing to be able to perform analysis of CSI.

[0037] The benefit of this first system according to the prior art 105 is that it is relatively cheap, as only a single node of the first type 110 is required. However, the signals being sent within the system 105 which may be used for performing sensing based on analyzing CSI are limited to a first signal 112 and a second signal 114 related to a link between the node of the first type 110 and, respectively, a first node of the second type 120 and a second node of the second type 130. As a result, a first person A and a third person C may be detected in the home 100, based on analyzing the CSI, however a second person B may not be detected as this second person does not impact the links 112, 114 sufficiently.

[0038] FIG. 2 shows a second wireless network sensing system according to the prior art 205. In this system 205, there are three nodes of the first type 110, 220, 230. Each of these nodes can analyze CSI related to links between each of the nodes. As there is now a third signal 225 related to a link between a second node of the first type 220 and a third node of the first type 230, also the second person B can be detected as, other than in the system 105 of FIG. 1, there now is a link 225 which is impacted.

[0039] The benefit of this second system according to the prior art 205 is that it provides greater coverage for performing sensing in the house 100. However, it is relatively expensive as it requires that there are more nodes of the first type when compared to the first wireless network sensing system according to the prior art 105 of FIG. 1.

[0040] In FIG. 3 a system 305 according to an embodiment of the first aspect is shown. This system 305 comprises a first node of the first type 310 and two nodes of the second type 320, 330. Similar to the system shown in FIG. 1, the first node of the first type analyzes CSI related to each of the links 312, 314 this node has with the first and second node of the second type 320, 330. Although the nodes of the second type are not capable of analyzing CSI related to a link 325 between them, there is a signal transmitted between the first and second nodes of the second type 320, 330. A determination of the CSI of this signal 325 may be made by one of the nodes of the second type 220, 230.

[0041] As shown in FIG. 4, the CSI related to the one or more wireless signals transmitted between the nodes of the second type 320, 330 is extracted and at least part of the CSI is transmitted by one of the nodes of the second type 330 over a link 410 to the node of the first type 310. Whether one or both nodes of the second type transmit CSI data can be determined in a variety of manners, for example each node of the second type may autonomously determine whether to transmit extracted CSI to the node of the first type 310, or the nodes of the second type 320, 330 determine this together e.g. in a master/slave configuration, or the node of the first type 110 may poll or instruct a node of the second type 220, 230 to transmit at least part of the extracted CSI.

[0042] The node of the first type 310 then analyses the received at least part of the CSI, which relates to the wireless signals transmitted between the nodes of the second type 320, 330. Thus, the system 305 is able to, for example, detect all three persons A, B, C shown in FIG. 3, while only requiring at least one node of the first type. This provides the lower cost benefits of the system 105 shown in FIG. 1, and the greater coverage benefits of the system 205 shown in FIG. 2.

[0043] Although only a single node of the first type is needed in the system 305 shown in FIG. 4, there may be, as is illustrated in the system 505 of FIG. 5, multiple nodes of the first type 310, 540. One of the nodes of the second type 330 transmits at least part of the CSI to either one or both nodes of the first type 310, 540. To which node(s) of the first type at least part of the extracted CSI is transmitted, may be determined autonomously by the nodes of the second type, or it may be predetermined, user configured, set by the nodes of the first type. etc. Transmitting at least part of the determined CSI to only one node of the first type, lessens the bandwidth needed in the wireless network for transmitting this data. By transmitting at least part of the determined CSI to multiple nodes of the 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 for performing sensing e.g. a first node of the first type may determine a value indicative of a person moving around an area, based on the analysis of the extracted CSI, whereas a second node of the first type may determine a value indicative of a person breathing; further these determined values may together be used to determine a value indicative of presence of a person.

[0044] The examples provided in FIGS. 3-5 show only two nodes of the second type. As follows from 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. There may also be any number of nodes of the second type, as long as there are multiple i.e. at least two nodes of the second type. Shown in FIG. 6 is a system 605 comprising four nodes of the second type 620, 630, 650, 660. In this system 605 each node of the second type creates a link with each of the other nodes of the second type, and when further the node of the first type 310 creates a link with each of the nodes of the second type 620, 630, 650, 660. This creates a large number of links 60, which may allow e.g. for extending the coverage area in which sensing is performed, however which may also be detrimental to improved sensing, such as when the wireless network becomes congested, when lag increases or messages are dropped.

[0045] In FIG. 7 the system 605 of FIG. 6 is shown again, however here the number of links between devices used for sensing is limited. In this example, three distinct wireless signals 710, 720, 730 are each transmitted between two nodes of the second type 620, 630, 650, 660. This allows, although optional, to send a message from a first node 620 to a second node 650, for the second node to determine the CSI related to its link with the first node and send at least part of this CSI as a message 720 to the third node 630. The third node 630 may then determine the CSI related to its link with the second node 650 and transmit at least part of this CSI as well as the CSI data received from the second node 650 related to its link 710 with the first node 620 to the fourth node 660. Finally, the fourth node 660 may again determine the CSI related to its link 730 with the third node and transmit at least part of this CSI it has determined to the node of the first type 740. The fourth node 660 will further send the CSI data it has received from the third node, which includes the CSI data which the third node has received from the second node, to the node of the first type. The node of the first type 310 may then analyze the CSI data related to each of the three links 710, 720, 730 discussed above. Further, the node of the first type 310 may extract CSI data related to the link 740 it has with the fourth node of the second type 660 and analyze this.

[0046] In FIG. 8 a block diagram is shown which shows an example of a method 800 for performing sensing in a wireless network. The wireless network comprises at least one node of the first type arranged for performing analysis on CSI related to wireless signals transmitted in the wireless network and a plurality of nodes of the second type, different from the first type. The method comprises: [0047] transmitting 810 one or more wireless signals between the plurality of nodes of the second type, [0048] determining 820 CSI, related to the one or more wireless signals, by at least one node of the plurality of nodes of the second type, [0049] transmitting 830 at least part of the determined CSI, 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; [0050] receiving 840 the at least part of the determined CSI by the node of the at least one node of the first type; and [0051] analyzing 850, by the node of the at least one node of the first type, the received at least part of the CSI and, based on said analysis, determining 860 a sensing value.

[0052] Various embodiments of the invention may be implemented as a program product for use with a computer system, where the program(s) of the program product define functions of the embodiments (including the methods described herein). In one embodiment, the program(s) can be contained on a variety of non-transitory computer-readable storage media, where, as used herein, the expression “non-transitory computer readable storage media” comprises all computer-readable media, with the sole exception being a transitory, propagating signal. In another embodiment, the program(s) can be contained on a variety of transitory computer-readable storage media. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., flash memory, floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. The computer program may be run on a processor.

[0053] 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 indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0054] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of embodiments of the present invention has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present invention. The embodiments were chosen and described in order to best explain the principles and some practical applications of the present invention, and to enable others of ordinary skill in the art to understand the present invention for various embodiments with various modifications as are suited to the particular use contemplated.