Wireless sensing system

Abstract

The utility model discloses a wireless sensing system, which is used for expanding a wireless sensing range and improving the detection reliability of a sensing target. The wireless sensing system provided by the utility model comprises a transmitting end, a receiving end and a signal scattering device, wherein the transmitting end is used for transmitting a signal; the receiving end is used for receiving a signal; the signal scattering device is located between the transmitting end and the receiving end and used for scattering electromagnetic waves of signals transmitted between the transmitting end and the receiving end in the transmission process.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a wireless sensing system. Background Technology

[0002] Wireless sensing technology utilizes wireless signals (such as WiFi and Bluetooth) to detect and understand the surrounding environment. This technology is mainly based on the characteristics of wireless signals, such as scattering, reflection, diffraction, and attenuation. When a transmitter sends a wireless signal into space, if there are people or activities along the electromagnetic wave propagation path before it reaches the receiver, the human body will affect the transmission of the electromagnetic waves, causing changes in the signal state, i.e., changes in the wireless channel state. Utility Model Content

[0003] This application provides a wireless sensing system to expand the wireless sensing range of the wireless sensing system and improve the detection reliability of the sensed target.

[0004] This application provides a wireless sensing system comprising: a transmitter, a receiver, and a signal scattering device; wherein...

[0005] The transmitting end is used to transmit signals;

[0006] The receiving end is used to receive signals;

[0007] The signal scattering device is located between the transmitting end and the receiving end, and is used to scatter the electromagnetic waves of the signal transmitted between the transmitting end and the receiving end during transmission.

[0008] In the wireless sensing system provided in this application embodiment, a signal scattering device is installed between the signal transmitter and the signal receiver to scatter the electromagnetic waves of the signal transmitted between the transmitter and receiver during transmission. This reduces the signal energy on the LOS path, i.e., lowers the intensity of the electromagnetic waves on the LOS path, thereby balancing the energy distribution on the LOS and NLOS paths. This increases the proportion of the signal on the NLOS path in the overall signal received by the receiving device, thus improving the CSI change ratio caused by the activity of people or other sensed targets on the NLOS path. On the other hand, the signal scattering device also increases the intensity of the electromagnetic waves on the NLOS path by scattering the electromagnetic waves from the LOS path to the NLOS path, further increasing the intensity of the reflected waves caused by the activity of people or other sensed targets on the NLOS path. This further increases the CSI change ratio caused by the activity of people or other sensed targets on the NLOS path, ultimately expanding the wireless sensing range of the wireless sensing system and improving the detection reliability of sensed targets.

[0009] In some embodiments, the transmitter, the receiver, and the signal scattering device are located on the same straight line.

[0010] In some embodiments, the material of the signal scattering device includes glass and / or metal.

[0011] In some embodiments, the signal scattering device is a cylinder with an elliptical or circular cross-section.

[0012] In some embodiments, the height of the column is 0.5 to 3 times the height of the antenna of the transmitting end or the receiving end.

[0013] In some embodiments, the signal scattering device has a dimension of 5mm to 5cm in the direction of the line connecting the transmitting end and the receiving end.

[0014] In some embodiments, the signal scattering device has a dimension of 3 mm to 6.5 cm in the direction perpendicular to the connecting line.

[0015] In some embodiments, the dimension of the signal scattering device in the direction perpendicular to the connecting line is 1.5 to 4 times a preset distance, where the preset distance is the distance between the center point of the signal scattering device and the center point of the transmitting end or the receiving end.

[0016] In some embodiments, the surface of the signal scattering device is a reconfigurable smart surface (RIS).

[0017] In some embodiments, the dielectric constant of the signal scattering device is 3 to 10. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a wireless sensing system provided in an embodiment of this application;

[0020] Figure 2 This is a schematic diagram of signal radiation from the transmitting end of the signal provided in an embodiment of this application;

[0021] Figure 3 A schematic diagram of signal radiation at the receiving end of the signal provided in the embodiments of this application;

[0022] Figure 4 A schematic diagram of the wireless personnel sensing system provided in this application embodiment when there are no personnel present;

[0023] Figure 5 This is a schematic diagram of the transmitted signal waveform of the transmitter provided in an embodiment of this application;

[0024] Figure 6 A schematic diagram of the waveforms of the received signal of the LOS path and the received signal of the NLOS path 1 at the receiving end in the wireless sensing system with a signal-free scattering device provided in the embodiments of this application.

[0025] Figure 7 A schematic diagram of the signal response of the received signal of the LOS path and the received signal of the NLOS path 1 when there are no personnel in the wireless sensing system with no signal scattering device provided in the embodiments of this application.

[0026] Figure 8 A schematic diagram of the wireless personnel sensing system provided in this application embodiment when there are personnel present;

[0027] Figure 9 A schematic diagram of the waveforms of the received signals of the LOS path, NLOS path 1, and NLOS path 2 at the receiver end when there are people in the wireless sensing system with a signal-free scattering device provided in the embodiments of this application.

[0028] Figure 10 A schematic diagram of the signal response of the received signals of the LOS path, NLOS path 1, and NLOS path 2 when there are people in the wireless sensing system provided for the embodiment of this application without a signal scattering device.

[0029] Figure 11 This is a schematic diagram showing the location of the signal scattering device provided in the embodiments of this application;

[0030] Figure 12 A waveform diagram of the received signal of the LOS path and the received signal of the NLOS path 1 of the receiver when there are no personnel in the wireless sensing system provided with a signal scattering device in the embodiment of this application.

[0031] Figure 13 A waveform diagram of the received signals of the LOS path, NLOS path 1, and NLOS path 2 of the receiver when there are people in the wireless sensing system provided in the embodiments of this application with a signal scattering device.

[0032] Figure 14 A schematic diagram of the signal response of the LOS path and the NLOS path 1 received signal of the receiver when there are no personnel in the wireless sensing system equipped with a signal scattering device provided in the embodiments of this application.

[0033] Figure 15 This is a schematic diagram of the signal response of the receiver at the location of personnel in a wireless sensing system equipped with a signal scattering device, where personnel are present.

[0034] Figure 16 This is a schematic diagram illustrating the expansion of the sensing area of ​​the wireless sensing system provided in an embodiment of this application. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0036] This application provides a wireless sensing system to expand the wireless sensing range of the wireless sensing system and improve the detection reliability of the sensed target.

[0037] The terms "first," "second," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0038] The following examples and embodiments are to be understood as illustrative only. While this specification may refer to "a," "an," or "some" examples or embodiments in several places, this does not mean that every such reference relates to the same example or embodiment, nor does it mean that the feature applies only to a single example or embodiment. Individual features of different embodiments may also be combined to provide other embodiments. Furthermore, terms such as "comprising" and "including" should be understood not to limit the described embodiments to consisting only of those features mentioned; such examples and embodiments may also include features, structures, units, modules, etc., not specifically mentioned.

[0039] The various embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be noted that the order in which the embodiments are presented in this application represents only a chronological order and does not represent the superiority or inferiority of the technical solutions provided by the embodiments.

[0040] First, let's introduce the technical terms used in the embodiments of this application:

[0041] Channel State Information (CSI): As the name suggests, CSI reflects changes in the state of the wireless channel, describing the communication channel conditions. This channel typically refers to a wireless channel and is frequently used in Wi-Fi and cellular network technologies.

[0042] LOS, short for Line of Sight path, refers to a signal transmission path where the signal travels directly from the transmitter to the receiver without any obstacles in between. In wireless communication, the LOS path is the ideal transmission path because it provides the maximum signal strength and the minimum signal attenuation.

[0043] NLOS: short for Non Line of Sight path, refers to a signal transmission process in which the signal cannot be directly transmitted from the transmitter to the receiver. Instead, it is blocked by obstacles and ultimately reaches the receiver through reflection, refraction, or diffraction.

[0044] Reconfigurable Intelligent Surface (RIS) is an emerging wireless communication technology that can effectively control and optimize the propagation of wireless signals by dynamically adjusting the electromagnetic properties of its surface.

[0045] The application scenarios involved in this application include, for example, scenarios where people are detected using wireless sensing, particularly in scenarios requiring sensing of large areas such as lobbies or outdoors. Considering the influence of the human body on electromagnetic wave transmission, which causes changes in signal state, i.e., changes in the wireless channel state, the current channel state information (CSI) data characteristics can be obtained from the received wireless signals to indicate whether someone is present in the detected area or is engaged in corresponding activities.

[0046] In wireless signal transmission, the signal energy received by the receiver mainly propagates through the Fresnel zone, especially the energy along the line-of-sight (LOS) path, where the propagation distance is shortest, attenuation is minimal, and energy is most concentrated. When people move along the non-line-of-sight (NLOS) path, the propagation path is relatively longer and attenuates more. At the same time, electromagnetic waves are affected by reflectivity during reflection, further reducing the energy received by the receiver along the NLOS path. This results in a weaker proportion of the signal that people bring to the receiver in distant areas. From a macroscopic perspective, the effective sensing area is limited to the vicinity of the LOS path, and the sensing range of the NLOS zone is very small.

[0047] Therefore, during actual operation, the energy on the LOS path is stronger than that on the NLOS path, resulting in a relatively small CSI fluctuation ratio when people move on the NLOS path. This makes it impossible to reliably detect the presence of people, thus resulting in a relatively small effective sensing range.

[0048] The method provided in this application reduces the electromagnetic wave intensity on the LOS path, balances the energy distribution on the LOS and NLOS paths, increases the CSI change ratio caused by the activity of people and other sensed targets on the NLOS path, thereby improving the detection reliability of people and other sensed targets and expanding the effective sensing range.

[0049] See Figure 1 The wireless sensing system provided in this application includes: a transmitter 101, a receiver 102, and a signal scattering device 103; wherein,

[0050] The transmitter 101 is used to transmit signals;

[0051] The receiving end 102 is used to receive signals;

[0052] The signal scattering device 103 is located between the transmitting end 101 and the receiving end 102, and is used to scatter the electromagnetic waves of the signal transmitted between the transmitting end 101 and the receiving end 102 during transmission.

[0053] In some embodiments, the transmitter, the receiver, and the signal scattering device are located on the same straight line.

[0054] In some embodiments, the signal scattering device is made of glass and / or metal, or may also include other dielectric materials. The specific materials and structural dimensions of the signal scattering device can be designed and adjusted according to the actual Wi-Fi operating frequency of the sensing system and the expected performance.

[0055] In some embodiments, the signal scattering device is a cylinder with an elliptical or circular cross-section.

[0056] In some embodiments, the height of the column is 0.5 to 3 times the height of the antenna of the transmitting end or the receiving end.

[0057] In some embodiments, the signal scattering device has a dimension of 5mm to 5cm in the direction of the line connecting the transmitting end and the receiving end.

[0058] In some embodiments, the signal scattering device has a dimension of 3 mm to 6.5 cm in the direction perpendicular to the connecting line.

[0059] In some embodiments, the dimension of the signal scattering device in the direction perpendicular to the connecting line is 1.5 to 4 times a preset distance, where the preset distance is the distance between the center point of the signal scattering device and the center point of the transmitting end or the receiving end.

[0060] For example, when the signal scattering device is closer to the transmitting end, assuming the distance between the center point of the signal scattering device and the center point of the transmitting end is d, the size of the signal scattering device in the direction perpendicular to the line connecting the center point of the transmitting end and the center point of the receiving end is 1.5 to 4 times d.

[0061] In some embodiments, the surface of the signal scattering device is a reconfigurable intelligent surface (RIS), thereby enabling dynamic adjustment according to changes in the field conditions.

[0062] In some embodiments, the dielectric constant of the signal scattering device is 3 to 10.

[0063] The following examples, using specific scenarios, illustrate how the embodiments of this application achieve the goal of expanding the sensing range and improving sensing accuracy.

[0064] In wireless sensing systems, such as Figure 2 , Figure 3 As shown, the transmitting and receiving devices transmit and receive signals through an omnidirectional antenna, and the signal is radiated uniformly in all directions.

[0065] In personnel wireless sensing systems, the system operates when no personnel are present, for example... Figure 4 As shown, there are two signal transmission paths: one is the LOS path, and the other is the NLOS path 1, which passes through surrounding objects such as walls; the signal waveform at the transmitting end is as follows. Figure 5 As shown, after the signal propagates through space, the signal waveforms of the LOS path and NLOS path 1 arriving at the receiving end are as follows: Figure 6As shown, the corresponding channel signal response is as follows: Figure 7 As shown, the system uses the channel signal response and a Fast Fourier Transform (FFT) to obtain the current channel frequency response characteristics, i.e., the CSI information in an unmanned state, which can be represented as CSI. 无 Then we have:

[0066]

[0067] Where H(f,t) is represented by the channel frequency response matrix of the wireless channel in CSI, identified by the letter H; (f,t) indicates that the frequency response is a function of frequency f and time t;

[0068] It is a representation of CSI by summing up the results from each propagation path;

[0069] in:

[0070] a n (f,n) represents the amplitude attenuation factor, which is a function of the frequency f and the propagation path n;

[0071] This represents the phase shift, which is a function of the frequency f and the propagation path n;

[0072] This indicates adding the data from the two paths numbered n=1 and n=2; because Figure 4 and Figure 7 The signal propagation path when no one is present has two paths: the LOS path and NLOS path 1. Therefore, the path number n can be between 1 and 2.

[0073] When there are people (i.e., the target being perceived), the system, for example... Figure 8 As shown, the transmission path passing through personnel is NLOS path 2. The signal waveform at the transmitting end is also shown below. Figure 5 As shown, after the signal propagates through space, the waveform of the signal reaching the receiving end is as follows: Figure 9 As shown, the channel signal response is as follows Figure 10 As shown, the system obtains the current channel frequency response characteristics, i.e., the channel state information (CSI) when someone is present, by performing a Fourier transform (FFT) on the channel signal response. This can be represented as CSI. 有 Then we have:

[0074]

[0075] When the target, such as a person, is far from the LOS path, the signal attenuation due to the long propagation path and the limited reflectivity of the human body results in relatively weak energy in the signal introduced by the human body—the NLOS path 2 signal. When this does not cause a significant change in the receiver's CSI, it leads to an inability to effectively perceive and identify the target.

[0076] Therefore, in this embodiment of the application, a signal scattering device is set up near the signal transmitting end or the signal receiving end (the specific location can be determined according to actual needs) to weaken the signal strength on the LOS path and enhance the signal strength on the NLOS path.

[0077] See Figure 11 For example, placing a circular glass object with a radius of 1 cm at a distance of 5 cm from the transmitting antenna at the transmitting end as a signal scattering device can increase the signal strength on the NLOS path relative to the LOS path signal by 3 times; the specific principle is explained below:

[0078] After adding this signal scattering device, the signal strength on the LOS path weakened, while the signal strength on the NLOS path was enhanced. The signal waveform is as follows: Figure 12 , Figure 13 As shown, where, Figure 12 The image shows the received signal waveforms of the LOS path and NLOS path 1 when no one is present. Figure 13 The diagram shows the received signal waveforms for the LOS path, NLOS path 1, and NLOS path 2 when people are present. The corresponding channel signal responses are shown below. Figure 14 , Figure 15 As shown, where, Figure 14 The diagram shows the channel signal responses of the LOS path and NLOS path 1 when no one is present. Figure 15 The diagram shows the channel signal responses of the LOS path, NLOS path 1, and NLOS path 2 when people are present.

[0079] The CSI status under unmanned conditions is denoted as CSI. new No, the CSI status when there are people is recorded as CSI. new If it exists, then it exists:

[0080]

[0081] Among them, CSI new This indicates the new wireless channel state achieved after using a signal scattering device;

[0082] When no one is around, the receiving antenna receives signals through two paths: the LOS path and NLOS path 1. Therefore, n takes the values ​​1 and 2.

[0083] When there are people present, the receiving antenna receives an additional NLOS path 2 of the signal reflected from the human body, so n takes the values ​​1, 2, and 3.

[0084] Compared to the system without a signal scattering device, the new system using a signal scattering device shows a weakened LOS component and an enhanced NLOS component, demonstrating the effect of the signal scattering device. Specifically, the a1 component, representing the LOS path, is reduced compared to the system without the signal scattering device; while the a1 and a2 components, representing the NLOS path, are enhanced compared to the system without the signal scattering device, thus demonstrating the effect of the signal scattering device: weakening the signal strength along the LOS path and enhancing the signal strength along the NLOS path.

[0085] Assume there are 3 signal propagation paths in the scenario: LOS path a1, NLOS path a2, and path a3 reflected from the human body;

[0086] Before the signal scattering device is introduced, the signal amplitude of LOS path a1 is labeled with 1. Assume that the signal amplitudes of each path are as shown in Table 1 below:

[0087] signal amplitude of LOS path a1 Signal amplitude of NLOS path a2 Signal amplitude of human body reflection path a3 1 0.35 0.3

[0088] Table 1

[0089] CSI is the frequency response, which has a square relationship with the amplitude value. The CSI value of the received signal is calculated as shown in Table 2 below:

[0090]

[0091] Table 2

[0092] As can be seen, from the unmanned situation to the manned situation, the CSI changed from 1.1225 to 1.2125, and the rate of change is 1.2125 ÷ 1.1225 - 100% = 8%;

[0093] However, after introducing the signal scattering device in this embodiment, the signal amplitude of LOS path a1 is reduced to 0.5, and the CSI value of the received signal is calculated as shown in Table 3 below:

[0094]

[0095] Table 3

[0096] As can be seen, from an unmanned situation to a manned situation, the CSI value changes from 0.3725 to 0.4625, with a change rate of 0.4625 ÷ 0.3725 - 100% = 24%. Compared with the system without a signal scattering device, the change rate of the CSI value of the received signal from an unmanned situation to a manned situation is greatly improved.

[0097] Furthermore, in systems using signal scattering devices, after enhancing the NLOS path signal by 10%, the CSI value of the received signal is calculated as shown in Table 4 below:

[0098]

[0099] Table 4

[0100] As can be seen, from an unmanned to a manned situation, the CSI value changes from 0.3725 to 0.4814, a change rate of 0.4814 ÷ 0.3725 - 100% = 29%. Therefore, after enhancing the NLOS path signal by 10%, the change rate increases from the aforementioned 24% to 29%, an increase of 29% ÷ 24% - 100% = 20%. Compared to the system with a signal scattering device but without enhancing the NLOS path signal, the change rate of the received signal's CSI value from an unmanned to a manned situation is further significantly improved.

[0101] In other words, by setting up a signal scattering device, this application reduces the signal energy on the LOS path, i.e., lowers the electromagnetic wave intensity on the LOS path, thereby balancing the energy distribution on the LOS and NLOS paths. This increases the proportion of the signal on the NLOS path in the overall signal received by the receiving device, thus improving the CSI change ratio caused by the activity of people or other sensed targets on the NLOS path. On the other hand, by scattering electromagnetic waves from the LOS path to the NLOS path, the signal scattering device can also increase the electromagnetic wave intensity on the NLOS path, thereby further increasing the intensity of reflected waves caused by the activity of people or other sensed targets on the NLOS path, i.e., further improving the CSI change ratio caused by the activity of people or other sensed targets on the NLOS path.

[0102] Furthermore, by enhancing the signal energy on the NLOS path (e.g., by the aforementioned 10% enhancement), the signal on the NLOS path can be further enhanced, thereby increasing the signal fluctuations caused by the activities of personnel and other perceived targets.

[0103] Ultimately, from the perspective of overall system performance, the system's effective sensing range for the NLOS region has increased, such as... Figure 16 As shown, the accuracy of perception is higher.

[0104] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A wireless sensing system, characterized in that, The system includes: a transmitter, a receiver, and a signal scattering device; wherein... The transmitting end is used to transmit signals; The receiving end is used to receive signals; The signal scattering device is located between the transmitting end and the receiving end, and is used to scatter the electromagnetic waves of the signal transmitted between the transmitting end and the receiving end during transmission.

2. The system according to claim 1, characterized in that, The transmitter, the receiver, and the signal scattering device are located on the same straight line.

3. The system according to claim 1, characterized in that, The materials of the signal scattering device include glass and / or metal.

4. The system according to claim 1, characterized in that, The signal scattering device is a cylinder with an elliptical or circular cross-section.

5. The system according to claim 4, characterized in that, The height of the column is 0.5 to 3 times the height of the antenna of the transmitting end or the receiving end.

6. The system according to claim 1, characterized in that, The signal scattering device has a dimension of 5mm to 5cm in the direction of the line connecting the transmitting end and the receiving end.

7. The system according to claim 6, characterized in that, The signal scattering device has a dimension of 3mm to 6.5cm in the direction perpendicular to the connecting line.

8. The system according to claim 6, characterized in that, The dimension of the signal scattering device in the direction perpendicular to the connecting line is 1.5 to 4 times the preset distance, where the preset distance is the distance between the center point of the signal scattering device and the center point of the transmitting end or the receiving end.

9. The system according to claim 1, characterized in that, The surface of the signal scattering device is a reconfigurable smart surface (RIS).

10. The system according to claim 1, characterized in that, The dielectric constant of the signal scattering device is 3 to 10.

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