Visible light communication space modulation method based on reflecting surface

Abstract

The embodiment of the invention provides a visible light communication spatial modulation method based on a reflecting surface. The technical problem that the visible light communication spatial modulation capability is poor can be solved. The method comprises the following steps: determining an activation reflection group of a reflection surface according to a channel gain of a first optical signal emitted by an emitter; the emitter sends the first optical signal to the activation reflection group; the activation reflection group receives the first optical signal and sends the first optical signal carrying the first data to the receiver; the light reflected by each reflective array element can reach at most one receiving unit. And according to the channel gain of the first optical signal transmitted by the transmitter, determining an activation reflection group in the reflection groups with different activation probabilities so as to adapt to changing channel conditions. By arranging the direct-view link shielding object, the problem that the transmission signal (the first optical signal) is blocked by an obstacle is solved, and the bit error rate is reduced. Therefore, the total rate performance and the total energy efficiency of the system are improved at the same time, and the visible light communication space modulation capability is improved.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a visible light communication spatial modulation method based on a reflecting surface. Background Art

[0002] Visible Light Communication (VLC) is a technology that uses visible light bands for data transmission. Compared with traditional radio frequency communications, VLC has significant advantages such as high bandwidth, strong security, environmental friendliness, and non-interference.

[0003] Currently, visible light wireless communication systems include a transmitter and a receiver. The transmitter converts electrical signals into invisible high-frequency flickering light signals. The receiver receives the light signals emitted by the transmitter and converts them back into electrical signals.

[0004] However, a visible light wireless communication system consisting of only a transmitter and a receiver cannot meet the rate requirements of certain communication scenarios. As the communication environment has increasingly variable requirements for data transmission stability and transmission efficiency, it cannot meet the needs. Therefore, how to improve the modulation flexibility of the visible light wireless communication system has become an urgent problem to be solved. Summary of the invention

[0005] The embodiment of the present application provides a visible light communication spatial modulation method based on a reflecting surface, which can solve the technical problem of poor spatial modulation capability of visible light communication.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a visible light communication spatial modulation method based on a reflecting surface, and the visible light communication spatial modulation method based on a reflecting surface includes: determining an activated reflection group of the reflecting surface according to a channel gain of a first light signal emitted by a transmitter; the reflecting surface includes multiple reflection groups; each reflection group includes multiple reflection array elements; the multiple reflection array elements are distributed in an N*N array, where N is a positive integer; the activated reflection group is one of the multiple reflection groups; at least two reflection groups have different activation probabilities; the transmitter sends a first light signal to the activated reflection group; the activated reflection group receives the first light signal and sends the first light signal carrying first data to a receiver; the receiver includes multiple receiving units arranged in an array; the first data includes an index of the activated reflection group; the light reflected by each reflection array element can reach at most one receiving unit; wherein a direct-line link obstruction is arranged between the transmitter and the receiver, so that the first light signal emitted by the transmitter cannot be directly received by the receiver; the transmitter, the direct-line link obstruction and the receiver are located on a first axis; the reflecting surface is arranged outside the first axis, and the reflecting surface is located between the transmitter and the receiver.

[0008] Based on the above description of the visible light communication spatial modulation method based on the reflection surface provided in the embodiment of the present application, it can be known that the visible light communication spatial modulation method based on the reflection surface includes determining the activated reflection group in the reflection groups with different activation probabilities according to the channel gain of the first light signal emitted by the transmitter to adapt to the changing channel conditions. By setting a direct-line link obstruction, the problem of the transmission signal (first light signal) being blocked by obstacles due to line of sight obstacles and device direction is overcome, and the bit error rate is reduced. By controlling the spatial modulation mode of the activated reflection group, the data rate of the activated reflection group is changed, and the data rate of the transmitter and the activated reflection group is transmitted in parallel. In this way, the overall rate performance and the overall energy efficiency of the system are improved at the same time, thereby improving the spatial modulation capability of visible light communication.

[0009] In a feasible implementation of the first aspect, when executing the step of determining the activated reflection group of the reflection surface according to the channel gain of the first optical signal emitted by the transmitter, the visible light communication spatial modulation method based on the reflection surface also includes: generating Huffman codes according to the number of reflection groups as information transmitted by the reflection surface nodes; based on the Huffman codes, confirming the activation probability of each reflection group; the longer the codeword in the Huffman code, the smaller the activation probability.

[0010] In this way, by introducing Huffman code encoding, the rates of the transmitter and receiver are different. When the total rate is consistent, a channel with a higher channel gain is selected to enable the transmitter to transmit higher-order information.

[0011] As well as improved bit error rate performance and increased channel capacity, with a gain of approximately 5.5dB and a BER of 1e -5 , capable of providing higher data rates.

[0012] In a feasible implementation of the first aspect, when executing the step of determining the activated reflection group of the reflection surface according to the channel gain of the first optical signal emitted by the transmitter, the visible light communication spatial modulation method based on the reflection surface also includes: confirming the activation probability of the reflection group according to the channel gain; the higher the value of the channel gain, the higher the activation probability.

[0013] In a feasible implementation manner of the first aspect, the evaluation parameter of the channel gain includes a signal-to-noise ratio; a higher value of the signal-to-noise ratio indicates a higher activation probability.

[0014] In a feasible implementation manner of the first aspect, the number of reflection array elements in the activated reflection group is an integer multiple of the number of receiving units, so that each receiving unit receives a signal.

[0015] In a feasible implementation of the first aspect, multiple reflection groups include a first reflection group, a second reflection group, a third reflection group and a fourth reflection group; the index of the first reflection group is 0, and the activation probability is 0.5; the index of the second reflection group is 10, and the activation probability is 0.25; the index of the third reflection group is 110, and the activation probability is 0.125; the index of the fourth reflection group is 111, and the activation probability is 0.125.

[0016] In a feasible implementation of the first aspect, before the transmitter sends the first optical signal to the activated reflection group, the visible light communication spatial modulation method based on the reflection surface further includes: preprocessing the first optical signal through pulse amplitude modulation.

[0017] In a possible implementation manner of the first aspect, the emitter is a light emitting diode.

[0018] In a feasible implementation manner of the first aspect, the receiving unit is a photodetector.

[0019] In a second aspect, an embodiment of the present application provides a visible light communication spatial modulation system based on a reflecting surface, and the visible light communication spatial modulation system based on a reflecting surface includes: a transmitter, a reflecting surface, a direct-line link obstruction and a receiver; a transmitter, sending a first light signal to an activated reflection group; the reflecting surface includes multiple reflection groups; each reflection group includes multiple reflection array elements; multiple reflection array elements are distributed in an N*N array, N is a positive integer; the activated reflection group is one of the multiple reflection groups; the activated reflection group is determined by the reflecting surface according to the channel gain of the first light signal; at least two reflection groups have different activation probabilities; the activated reflection group is used to receive the first light signal and send the first light signal carrying first data to the receiver; the receiver includes multiple receiving units arranged in an array; the first data includes the index of the activated reflection group; the light reflected by each reflection array element can reach at most one receiving unit; a direct-line link obstruction is arranged between the transmitter and the receiver, so that the first light signal emitted by the transmitter cannot be directly received by the receiver; the transmitter, the direct-line link obstruction and the receiver are located on a first axis; the reflecting surface is arranged outside the first axis, and the reflecting surface is located between the transmitter and the receiver.

[0020] The visible light communication spatial modulation system based on the reflecting surface performs the method provided in the first aspect, and determines the activated reflection group in the reflection groups with different activation probabilities according to the channel gain of the first light signal emitted by the transmitter to adapt to the changing channel conditions. By setting a direct-view link obstruction, the problem of the transmission signal (first light signal) being blocked by obstacles due to line of sight obstacles and device direction is overcome, and the bit error rate is reduced. In this way, the overall rate performance and overall energy efficiency of the system are improved at the same time, thereby improving the spatial modulation capability of visible light communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1A schematic diagram of the structure of a visible light communication spatial modulation system based on a reflective surface provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of a flow chart of a visible light communication spatial modulation method based on a reflective surface provided in an embodiment of the present application;

[0023] Figure 3 A schematic diagram of the structure of a reflective surface in a visible light communication spatial modulation method based on a reflective surface provided in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of a feasible implementation method of Huffman code in a visible light communication spatial modulation method based on a reflecting surface provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described below in conjunction with the accompanying drawings in the embodiments of the present invention. In the description of the embodiments of the present invention, unless otherwise specified, "multiple" refers to two or more than two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0026] In addition, in order to facilitate the clear description of the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, the words "first", "second" and the like are used to distinguish the same items or similar items with substantially the same functions and effects. Those skilled in the art will understand that the words "first", "second" and the like do not limit the quantity and execution order, and the words "first", "second" and the like do not necessarily limit the difference. At the same time, in the embodiments of the present invention, the words "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or design. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0027] The principles and features of the present application are described below. The examples given are only used to explain the present application and are not used to limit the scope of the present application.

[0028] The embodiment of the present application provides a visible light communication spatial modulation method based on a reflective surface, which is applicable to various visible light communication scenarios. According to the channel gain of the first light signal emitted by the transmitter, the activated reflection group is determined in the reflection groups with different activation probabilities to adapt to the changing channel conditions. By setting a direct-line link obstruction, the problem of the transmission signal (first light signal) being blocked by obstacles due to line of sight obstacles and device direction is overcome, and the bit error rate is reduced. In this way, the overall rate performance and overall energy efficiency of the system are improved at the same time, thereby improving the spatial modulation capability of visible light communication.

[0029] The embodiment of the present application provides a visible light communication spatial modulation system based on a reflecting surface, which can execute the visible light communication spatial modulation method based on a reflecting surface provided in the embodiment of the present application. Figure 1 The present invention provides a schematic diagram of a visible light communication spatial modulation system based on a reflective surface. Figure 1 As shown, in some embodiments, the reflective surface-based visible light communication spatial modulation system includes: a transmitter, a reflective surface, a direct-view link obstruction, and a receiver.

[0030] The transmitter is used to determine an activated reflection group of a reflection surface according to a channel gain. And, send a first optical signal to the activated reflection group. The reflection surface includes a plurality of reflection groups. Each reflection group includes a plurality of reflection array elements. The plurality of reflection array elements are distributed in an N*N array, where N is a positive integer. The activated reflection group is one of the plurality of reflection groups. At least two reflection groups have different activation probabilities.

[0031] The activated reflection group is used to receive the first optical signal and send the first optical signal carrying the first data to the receiver. The receiver includes a plurality of receiving units arranged in an array. The first data includes an index of the activated reflection group. The light reflected by each reflection array element can reach at most one receiving unit.

[0032] A direct-view link shield is provided between the transmitter and the receiver so that the first optical signal emitted by the transmitter cannot be directly received by the receiver.

[0033] The transmitter, the direct-view link shield and the receiver are located on a first axis. The reflective surface is arranged outside the first axis, and the reflective surface is located between the transmitter and the receiver.

[0034] Figure 2 A schematic diagram of a process flow of a visible light communication spatial modulation method based on a reflective surface provided in an embodiment of the present application. Figure 2 As shown, in some embodiments, the visible light communication spatial modulation method based on the reflecting surface includes the following steps:

[0035] S1, determining an activated reflection group of a reflection surface according to a channel gain of a first optical signal transmitted by a transmitter.

[0036] The transmitter converts the electrical signal into an invisible high-frequency flickering light signal. In some embodiments, the transmitter is a light-emitting diode (LED). The first light signal is a high-frequency flickering light signal.

[0037] Reflective surface, also known as reconfigurable intelligent surface (RIS), is a passive device, that is, it only adjusts the reflection direction of the incident light without changing its amplitude. By introducing programmable reflective surfaces in wireless communication environments, the signal propagation characteristics can be improved. Reflective surfaces can enhance signals and have environmental adaptability. By adjusting the reflection characteristics in real time, the reflective surface can adapt to different environmental conditions, optimize the signal transmission quality, and be flexible and energy-saving in deployment. The introduction of reflective surface technology in visible light communication can significantly improve the quality and stability of the signal, enhance communication performance by introducing non-line-of-sight paths and actively reshaping the optical wireless propagation environment, and accurately change the transmission characteristics of the reflected light signal by adjusting parameter indexes such as refractive index and reflection angle.

[0038] In some embodiments, Figure 1 As shown, the RIS includes a plurality of reflection groups. Each reflection group includes a plurality of reflection array elements. The plurality of reflection array elements are distributed in an N*N array, where N is a positive integer.

[0039] In some embodiments, the number of reflection array elements is represented by N e , which are divided equally into N g groups, each with N e / N g Array elements, which are arranged into The secondary array of e / N g and are integers. RIS and W RIS Indicates the length and width of the RIS node. Figure 1 and Figure 3 In one implementation, the reflection surface includes four reflection groups. Each reflection group includes 16 reflection array elements. The 16 reflection array elements are distributed in a 4*4 array.

[0040] The activated reflection group is one of the multiple reflection groups, wherein at least two reflection groups have different activation probabilities. The determination of the activation probability is described in detail below.

[0041] In some embodiments, when executing step S1, the visible light communication spatial modulation method based on the reflecting surface further includes:

[0042] S111, generating a Huffman code according to the number of reflection groups.

[0043] In one implementation, the multiple reflection groups include a first reflection group, a second reflection group, a third reflection group and a fourth reflection group, totaling four reflection groups. Then the Huffman codes are 0, 10, 110 and 111.

[0044] S112, confirming the activation probability of each reflection group based on the Huffman code.

[0045] Among them, the longer the codeword in the Huffman code, the smaller the activation probability.

[0046] like Figure 4 As shown, in one implementation, the plurality of reflection groups include a first reflection group, a second reflection group, a third reflection group, and a fourth reflection group. The Huffman code of the first reflection group is 0, and the activation probability is 0.5. The Huffman code of the second reflection group is 10, and the activation probability is 0.25. The Huffman code of the third reflection group is 110, and the activation probability is 0.125. The Huffman code of the fourth reflection group is 111, and the activation probability is 0.125.

[0047] In another implementation, the plurality of reflection groups include a first reflection group, a second reflection group, a third reflection group, a fourth reflection group, a fifth reflection group, and a sixth reflection group. The Huffman code of the first reflection group is 0, and the activation probability is 0.5. The Huffman code of the second reflection group is 10, and the activation probability is 0.25. The Huffman code of the third reflection group is 110, and the activation probability is 0.125. The Huffman code of the fourth reflection group is 1110, and the activation probability is 0.125. The Huffman code of the fifth reflection group is 11110, and the activation probability is 0.0625. The Huffman code of the sixth reflection group is 11111, and the activation probability is 0.03125.

[0048] It is understandable that the above implementations are only exemplary of four reflection groups and six reflection groups, and do not constitute a limitation on the number of reflection groups. A larger number of reflection groups corresponds to an encoding method with a larger number of bits.

[0049] In this way, by introducing Huffman code encoding, the rates of the transmitter and receiver are different. When the total rate is consistent, a channel with a higher channel gain is selected to enable the transmitter to transmit higher-order information.

[0050] As well as improved bit error rate performance and increased channel capacity, with a gain of approximately 5.5dB and a BER of 1e -5 , capable of providing higher data rates.

[0051] The following describes how to determine the activated reflection group.

[0052] In some embodiments, when executing step S1, the visible light communication spatial modulation method based on the reflecting surface further includes:

[0053] S121: confirm the reflection group activation probability according to the channel gain.

[0054] In some embodiments, the higher the value of the channel gain, the higher the activation probability.

[0055] In one implementation, the evaluation parameter of the channel gain includes a signal-to-noise ratio. The higher the value of the signal-to-noise ratio, the higher the activation probability.

[0056] It can be understood that the present application does not activate the second reflection group when the first reflection group is activated, but all reflection groups (for example, the first reflection group, the second reflection group, the third reflection group and the fourth reflection group) are activated, but with different activation probabilities. That is, when the first optical signal reaches the reflection surface, data is transmitted along a link of a certain reflection group to the receiver with a certain probability.

[0057] For example, the channel signal-to-noise ratio after the first reflection group is 30dB, the channel signal-to-noise ratio after the second reflection group is 15dB, the channel signal-to-noise ratio after the third reflection group is 0dB, and the channel signal-to-noise ratio after the fourth reflection group is 0dB. Then, according to the channel signal-to-noise ratio arranged from large to small, the first reflection group is assigned an activation probability of 0.5, the second reflection group is assigned an activation probability of 0.25, the third reflection group is assigned an activation probability of 0.125, and the fourth reflection group is assigned an activation probability of 0.125. At this time, the first data carried by the reflection surface, that is, the spatial modulation signal carried by the first reflection group is 0, the spatial modulation signal carried by the second reflection group is 10, the spatial modulation signal carried by the third reflection group is 110, and the spatial modulation signal carried by the fourth reflection group is 111, thereby completing the spatial modulation technology with a reflection surface.

[0058] S2, the transmitter sends a first optical signal to the activated reflection group.

[0059] A direct-line link shield is provided between the transmitter and the receiver so that the first optical signal transmitted by the transmitter cannot be directly received by the receiver. The transmitter, the direct-line link shield and the receiver are located on a first axis. The reflective surface is provided outside the first axis, and the reflective surface is located between the transmitter and the receiver. In this way, the transmitter sends the first optical signal to the activated reflective group.

[0060] In some embodiments, before executing step S2, the visible light communication spatial modulation method based on the reflecting surface further includes:

[0061] S21, preprocessing the first optical signal through pulse amplitude modulation.

[0062] Exemplarily, the LED uses pulse amplitude modulation (M-PAM) to transmit log2(m) bits per transmission.

[0063] S3, activating the reflection group to receive the first optical signal, and sending the first optical signal carrying the first data to the receiver.

[0064] All array elements in the activated reflection group can reflect light to the receiver. Except for the activated reflection group, the array elements in other reflection groups are turned off and cannot reflect light. In some embodiments, the reflection direction of the first optical signal can be adjusted.

[0065] The first data indicates data to be transmitted by the activated reflection group. In one implementation, the first data includes an index of the activated reflection group.

[0066] In some embodiments, spatial modulation is used on the reflective surface. In this way, the activated reflective group modulates its own data (ie, first data) onto the first optical signal using spatial modulation technology, which means that the activated reflective group can use the light of the transmitter to send its own data to the receiver.

[0067] Among them, spatial modulation (SM) technology, as a multi-input multi-output fusion digital modulation method, has attracted attention in improving the spectrum efficiency of visible light wireless communication. In a visible light wireless communication system with multiple transmitters, spatial modulation activates only one transmitter at a time and uses its index as the carrier information. This innovation introduces the spatial domain as an additional modulation dimension, thereby improving the spectrum efficiency of the system. Studies have shown that spatial modulation is superior to other MIMO strategies and also provides lower computational complexity for visible light wireless communication systems.

[0068] In one implementation, the index of the activated reflection group can be a Huffman code. Figure 4 As shown, in one implementation, the plurality of reflection groups include a first reflection group, a second reflection group, a third reflection group, and a fourth reflection group. The Huffman code of the first reflection group is 0. The Huffman code of the second reflection group is 10. The Huffman code of the third reflection group is 110. The Huffman code of the fourth reflection group is 111. Among them, the second reflection group is an activated reflection group, and the index is "10".

[0069] The light reflected by each reflective array element can reach at most one receiving unit.

[0070] By arranging a plurality of different array elements in the activated reflection group, light is reflected to different receiving units.

[0071] S4, the receiver receives a first optical signal carrying first data.

[0072] The receiver receives the light signal emitted by the light source transmitter (such as LED) and converts it back into an electrical signal. The receiver includes a plurality of receiving units arranged in an array.

[0073] In some embodiments, the receiving unit is a photodetector, which is also called a photodiode (PD).

[0074] The first optical signal carrying the first data is called a reflected signal.

[0075] In some embodiments, the number of reflection array elements in the activated reflection group is an integer multiple of the number of receiving units, so that each receiving unit receives a signal.

[0076] Combined Figure 1 and Figure 3 In one implementation, there are "16" array elements in each reflection group. "4" PDs receive the optical signal. During each transmission, every "4" array elements in the activated reflection group reflect the incident light (first optical signal and first data) from the LED to one of the "4" PDs. In this way, "16" elements can send light to "4" PDs at the same time, that is, each PD receives the incident light.

[0077] Thus, the receiver receives the reflected signal.

[0078] The reflected signal contains data from the LED and from the reflective surface. At the same time, on the receiver side, the PD array receives the combined data of the LED and the reflective surface, which can be expressed as follows:

[0079]

[0080] Where n is the mean of 0 and the variance of σ 2 The real value of additive Gaussian white noise; r is the photoelectric conversion coefficient; s includes the LED signal s LED and RIS signals RIS The union of is the equivalent channel gain, which can be expressed as:

[0081]

[0082] in, represents the Hadamard product, H is the gain of the non-direct-view channel from the LED to the PD, expressed as:

[0083]

[0084] where h ij (i=1,2,...,N r, j = 1, 2, ..., N e ) includes the product of the gain from the pth LED to the jth reflector and the gain from the jth reflector to the i-th PD, expressed as

[0085] and They are the gain from the transmitter to the array element of the jth reflector and the gain from the array element of the jth reflector to the i-th detector, respectively. The calculation formula for one case is given as:

[0086]

[0087] Where ξ and ∈ are correction coefficients, c is the extinction coefficient based on the atmospheric environment, and D R and D P are the hole diameters of the reflective surface and the detector, respectively, and They represent the distance from the LED to the jth reflector array element and the distance from the jth reflector array element to the i-th detector, respectively. and are the corresponding longitudinal distances respectively. The reflection matrix F and the grouping matrix G are expressed as:

[0088]

[0089] Among them, f ij ∈{0,1}, when f ij =1, it means that the jth reflector array element can reflect light to the ith PD. ij =0, the opposite is true; g jk ∈{0,1}, when g jk = 1, it means that the jth reflector array element is divided into the kth group. Because each array element can only reflect the signal to one PD and belongs to only one group, there are the following constraints on the reflection matrix F and the grouping matrix G, and they remain unchanged after the system is determined.

[0090]

[0091] The visible light communication spatial modulation method based on the reflecting surface provided in the embodiment of the present application includes determining the activated reflection group in the reflection groups with different activation probabilities according to the channel gain of the first light signal emitted by the transmitter to adapt to the changing channel conditions. By setting a direct-line link obstruction, the problem of the transmission signal (first light signal) being blocked by obstacles due to line of sight obstacles and device direction is overcome, and the bit error rate is reduced. By controlling the spatial modulation mode of the activated reflection group, the data rate of the activated reflection group is changed, so as to achieve parallel transmission of the data rates of the transmitter and the activated reflection group. In this way, the overall rate performance and the overall energy efficiency of the system are improved at the same time, thereby improving the spatial modulation capability of visible light communication.

[0092] The reflective surface-based visible light communication spatial modulation method provided in the embodiment of the present application can increase the modulation speed of the light source and reduce the impact of ambient light interference on the signal.

[0093] The visible light communication spatial modulation method based on the reflecting surface provided in the embodiment of the present application can combine the spatial modulation technology with the reconfigurable smart surface in visible light communication to achieve more efficient data transmission.

[0094] The visible light communication spatial modulation method based on the reflective surface provided in the embodiment of the present application optimizes the performance of spatial modulation by setting the reflective surface and dynamically adjusting the characteristics of the reflected signal. It not only reduces the dependence of signal generation on the power amplifier, but also improves the flexibility of the system, making it particularly advantageous in situations where power is limited or a large number of devices are required to transmit data.

[0095] The visible light communication spatial modulation method based on the reflective surface provided in the embodiment of the present application combines visible light wireless communication, reconfigurable smart surface and spatial modulation technology, providing a new idea and solution for future wireless communication systems. This innovative combination can not only improve the data transmission rate, but also effectively deal with environmental interference and improve the security and reliability of communication. With the deepening of research and the continuous development of technology, this field is expected to be widely used in application scenarios such as smart cities and smart homes, promoting the further development of wireless communication technology.

[0096] The visible light communication spatial modulation method based on the reflective surface provided in the embodiment of the present application considers the transmitting end LED and the reflective surface separately, has an independent reflective surface spatial modulation scheme, and is independent of the modulation order and modulation mode of the LED. There is no need to add a RIS controller, and there will be no deployment problems in practical applications. The reflective surface does not depend on the LED and does not limit the data rate. It does not depend on the setting of the power amplifier and is suitable for situations where power is limited or a large number of devices transmit data.

[0097] The embodiment of the present application provides a visible light communication spatial modulation method based on a reflective surface, which introduces Huffman coding into the selection of the reflective surface. The probability of the reflective surface being selected is different, and it can adapt to dynamic communication scenarios where the channel state changes. This technology can improve the flexibility and data rate of the system, adapt to dynamically changing channel conditions, overcome line of sight obstacles and device direction problems, and optimize the rate at which the reflective surface transmits information, thereby realizing a more efficient and reliable visible light communication system.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

[0099] In addition, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices stated in a device claim can also be implemented by one unit or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

Claims

1. A visible light communication spatial modulation method based on a reflecting surface, characterized in that: include: Determining an activated reflection group of the reflection surface according to a channel gain of a first optical signal transmitted by the transmitter; The reflection surface includes a plurality of reflection groups; each of the reflection groups includes a plurality of reflection array elements; the plurality of reflection array elements are distributed in an N*N array, where N is a positive integer; the activated reflection group is one of the plurality of reflection groups; at least two of the reflection groups have different activation probabilities; The transmitter sends the first optical signal to the activated reflection group; The activated reflection group receives the first optical signal and sends the first optical signal carrying the first data to a receiver; the receiver includes a plurality of receiving units arranged in an array; the first data includes an index of the activated reflection group; the light reflected by each reflection array element can reach at most one receiving unit; Wherein, a direct-line link obstruction is arranged between the transmitter and the receiver so that the first optical signal emitted by the transmitter cannot be directly received by the receiver; the transmitter, the direct-line link obstruction and the receiver are located on a first axis; the reflecting surface is arranged outside the first axis, and the reflecting surface is located between the transmitter and the receiver.

2. The visible light communication spatial modulation method based on a reflecting surface according to claim 1, characterized in that: When performing the step of determining the activated reflection group of the reflection surface according to the channel gain of the first light signal transmitted by the transmitter, the visible light communication spatial modulation method based on the reflection surface further includes: Generate a Huffman code according to the number of the reflection groups as information transmitted by the reflection surface node; Based on the Huffman code, the activation probability of each of the reflection groups is confirmed; the longer the codeword in the Huffman code, the smaller the activation probability.

3. The visible light communication spatial modulation method based on a reflecting surface according to claim 2, characterized in that: When performing the step of determining the activated reflection group of the reflection surface according to the channel gain of the first light signal transmitted by the transmitter, the visible light communication spatial modulation method based on the reflection surface further includes: According to the channel gain, the activation probability of the reflection group is confirmed; the higher the value of the channel gain is, the higher the activation probability is.

4. The visible light communication spatial modulation method based on a reflecting surface according to claim 3, characterized in that: The evaluation parameter of the channel gain includes a signal-to-noise ratio; the higher the value of the signal-to-noise ratio is, the higher the activation probability is.

5. The visible light communication spatial modulation method based on a reflecting surface according to any one of claims 1 to 4, characterized in that: The number of the reflection array elements in the activated reflection group is an integer multiple of the number of the receiving units, so that each of the receiving units can receive a signal.

6. The visible light communication spatial modulation method based on a reflecting surface according to any one of claims 1 to 4, characterized in that: The plurality of reflection groups include a first reflection group, a second reflection group, a third reflection group and a fourth reflection group; The index of the first reflection group is 0, and the activation probability is 0.5; the index of the second reflection group is 10, and the activation probability is 0.25; the index of the third reflection group is 110, and the activation probability is 0.125; the index of the fourth reflection group is 111, and the activation probability is 0.

125.

7. The visible light communication spatial modulation method based on a reflective surface according to any one of claims 1 to 4, characterized in that: Before the transmitter sends the first optical signal to the activated reflection group, the visible light communication spatial modulation method based on the reflection surface further includes: The first optical signal is preprocessed by pulse amplitude modulation.

8. The visible light communication spatial modulation method based on a reflective surface according to any one of claims 1 to 4, characterized in that: The emitter is a light emitting diode.

9. The visible light communication spatial modulation method based on a reflective surface according to any one of claims 1 to 4, characterized in that: The receiving unit is a photoelectric detector.

10. A visible light communication spatial modulation system based on a reflective surface, characterized in that: include: Transmitters, reflective surfaces, line-of-sight link obstructions, and receivers; The transmitter sends a first optical signal to the activated reflection group; The reflection surface includes a plurality of reflection groups; each of the reflection groups includes a plurality of reflection array elements; the plurality of reflection array elements are distributed in an N*N array, where N is a positive integer; the activated reflection group is one of the plurality of reflection groups; the activated reflection group is determined by the reflection surface according to the channel gain of the first optical signal; at least two of the reflection groups have different activation probabilities; The activated reflection group is used to receive the first optical signal and send the first optical signal carrying the first data to a receiver; the receiver includes a plurality of receiving units arranged in an array; the first data includes an index of the activated reflection group; the light reflected by each reflection array element can reach at most one receiving unit; A direct-line link shield is provided between the transmitter and the receiver, so that the first optical signal transmitted by the transmitter cannot be directly received by the receiver; The transmitter, the direct-line link obstruction, and the receiver are located on a first axis; The reflecting surface is arranged outside the first axis, and the reflecting surface is located between the transmitter and the receiver.

Images