A vehicle networking user communication method and device based on polarization modulation, spatial modulation and omnidirectional intelligent metasurface assistance

Abstract

The application discloses a kind of based on polarization modulation, spatial modulation and omnidirectional intelligent metasurface auxiliary car networking user communication method and device, belong to car networking wireless communication technical field, the method includes: S1.The synthesis of signal;S2.Signal multiple access transmission;S3.Signal detection and demodulation;The device includes: base station transmitting end, omnidirectional intelligent metasurface and user receiving end.The application suppresses the interference between car networking users without relying on successive interference cancellation operation, effectively reduces the computational complexity;Through the optimized reflection / transmission phase configuration, the coverage of signal is improved, further eliminates the signal coverage blind area in car networking scene, and enhances the flexibility of deployment;Through multidimensional physical layer modulation, the spectral efficiency is improved, and the hardware complexity is reduced by minimizing the number of radio frequency chains while maintaining spatial diversity gain;Further reduce the energy consumption of base station transmitting end, more environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle networking wireless communication, and in particular to a vehicle networking user communication method and device based on polarization modulation, spatial modulation and omnidirectional intelligent metasurface assistance. BACKGROUND

[0002] The application of vehicle networking has greatly promoted the development of intelligent transportation, driving safety and vehicle information entertainment. With the introduction of multiple-input multiple-output (MIMO) technology, the data transmission rate and spectrum efficiency in vehicle networking communication have been guaranteed and improved, and the signal coverage range and anti-interference capability have also been enhanced. In order to further reduce the cost and hardware complexity of vehicle networking MIMO system, MIMO enhancement technology can be used to improve system performance and reduce transmission energy consumption by utilizing spatial and temporal diversity gain.

[0003] Spatial modulation is a main method to realize MIMO enhancement of vehicle networking. Based on spatial modulation, only one transmitting antenna is activated and sends the actual modulated signal in each time slot, which is cost-effective and can avoid inter-antenna synchronization and inter-carrier interference. Index modulation is a generalized form of spatial modulation. For example, the document with DOI number 10.1109 / TVT.2020.3002067 provides a parallel concatenated index modulation scheme integrated with M-ary phase shift keying, which improves energy efficiency while ensuring reliable vehicle communication and achieving low peak-to-average power ratio; the document with DOI number 10.1109 / TVT.2022.3219888 provides a hybrid exponential modulation scheme that integrates index modulation with a dual-function radar communication system, which can improve energy and spectrum efficiency in vehicle communication systems.

[0004] In addition to spatial modulation, polarization modulation also provides a new research idea for improving the transmission efficiency of vehicle networking communication. As a parameter of data modulation, polarization is essentially orthogonal, and through the polarization characteristics of dual-polarized antenna elements, the bit error rate performance of the MIMO system can be improved and the diversity gain can be enhanced. For example, the document with DOI number 10.1109 / GLOBECOM46510.2021.9686020 provides a communication system architecture based on offset circular polarization modulation, which can increase channel capacity and improve data security to prevent eavesdropping.

[0005] In addition, with the wide application of omnidirectional intelligent metasurfaces, various operating modes supported by the omnidirectional intelligent metasurfaces, such as mode switching, energy splitting, and time switching, can be used to realize full-space wireless signal coverage. On this basis, non-orthogonal multiple access technology allows multiple user equipment to share resources, and the integration of non-orthogonal multiple access technology and omnidirectional intelligent metasurfaces further improves the spectrum efficiency. For example, the document with DOI number 10.1109 / LCOMM.2022.3223968 provides a scheme that combines the concept of indexing into an omnidirectional intelligent metasurface-assisted non-orthogonal multiple access system. Although this scheme can improve the spectrum and energy efficiency, it needs to use successive interference cancellation to mitigate inter-user interference, which has high computational complexity and limits the system with limited processing capacity. The patent with publication number CN118413259B provides an omnidirectional intelligent metasurface-assisted non-orthogonal multiple access communication method and system, which uses a user-oriented weighted sum rate optimization resource allocation model. This scheme also needs to use traditional successive interference cancellation decoding, and in the case of communication link obstruction, the signal coverage range and corresponding device deployment flexibility achieved by this scheme will be greatly limited.

[0006] In summary of the above research progress, in the existing vehicle-to-everything MIMO enhancement technology, certain achievements have been made in spatial modulation technology, polarization modulation technology, and omnidirectional intelligent metasurface-assisted non-orthogonal multiple access technology, but the related schemes involving non-orthogonal multiple access rely heavily on successive interference cancellation technology with high computational complexity, and no scheme can effectively combine spatial modulation, polarization modulation, and omnidirectional metasurface-assisted non-orthogonal multiple access in a vehicle-to-everything communication system, so there is still room for improvement in spectrum efficiency and signal coverage range.

[0007] Therefore, in a vehicle-to-everything communication system, for non-orthogonal multiple access signal transmission of transmission users and reflection users in an omnidirectional intelligent reflecting surface system, it is of great significance to design a vehicle-to-everything communication user non-orthogonal multiple access scheme that combines spatial modulation and polarization modulation, and omnidirectional intelligent metasurface assistance, to reduce hardware complexity, computational complexity, expand signal coverage range, and improve spectrum efficiency. SUMMARY

[0008] The technical problem to be solved by the present application is to overcome the deficiencies in the prior art and provide a vehicle-to-everything user communication method and device based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance, which has low hardware complexity, low computational complexity, large signal coverage range, and high spectrum efficiency.

[0009] The technical scheme adopted by the present application to solve its technical problem is:

[0010] In a first aspect, a vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance includes the following steps:

[0011] S1. Signal Synthesis: The bit data transmitted by the base station transmitter is divided into index bits and symbol bits. The dual-polarized antenna is activated and the polarization mode is selected based on the index bits. A phase-shift keying modulation signal is generated based on the symbol bits. The signal is then synthesized at the activated dual-polarized antenna. And send it to the omnidirectional intelligent metasurface;

[0012] S2. Multiple access transmission of signals: Establishing a cascaded channel for omnidirectional intelligent metasurface transmission surfaces. Cascaded channels with reflectors Based on the synthesized signal from the base station transmitter Calculate the signal transmitted to the remote user receiver. and the signal reflected to the near-end user receiver And send it to the corresponding user receiving end;

[0013] S3. Signal Detection and Demodulation: Signals are detected using a maximum likelihood estimation algorithm. and signal The index information is obtained at the remote user receiver and the index bits are demodulated, while the modulation information is obtained at the near user receiver and the symbol bits are demodulated.

[0014] Furthermore, step S1 further includes the following steps:

[0015] S11. Based on the total number of dual-polarized antennas at the base station transmitter. and total number of polarization modes Calculate the index bit length Randomly generated length is index bits Based on the radix of the phase shift keying modulation signal Calculate the length of the symbol bits Randomly generated length is symbol bits ;

[0016] S12. Based on the index information of the dual-polarized antennas at the base station transmitter carried by the index bits, activate the dual-polarized antennas with the corresponding sequence numbers, and calculate the antenna activation matrix of the dual-polarized antennas. Based on the index information of the polarization mode carried by the index bits, select the polarization mode with the corresponding sequence number, and calculate the polarization matrix of the selected polarization mode. Based on the modulation information carried by the symbol bits, the constellation symbol of the phase shift keying signal is obtained. First, based on the polarization matrix and constellation symbols Calculate the signal vector transmitted by the dual-polarized antenna at the base station transmitter under the selected polarization mode and the modulation signal used. Then, based on the antenna activation matrix The synthesized signal is calculated at the activated dual-polarized antenna. .

[0017] Furthermore, in step S11, the index bit length The calculation formula is:

[0018]

[0019] in, This represents the total number of dual-polarized antennas at the base station transmitter. This represents the total number of polarization modes;

[0020] The symbol bit length The calculation formula is:

[0021]

[0022] in, It is the radix of the phase shift keying modulation signal.

[0023] Furthermore, in step S12, the antenna activation matrix The calculation formula is:

[0024]

[0025] in, This refers to the sequence number of the dual-polarized antenna activated at the base station transmitter.

[0026] The polarization matrix The expression is:

[0027]

[0028] in, , These are the polarization information for the vertical and horizontal components, respectively. This is the sequence number of the polarization mode;

[0029] The constellation symbol The expression is:

[0030]

[0031] in, , for Sub-symbols transmitted at the vertical component and the horizontal component respectively;

[0032] The signal vector The calculation formula is:

[0033]

[0034] in, , These are sub-signals representing the vertical and horizontal components, respectively.

[0035] The synthesized signal The calculation formula is:

[0036]

[0037] in, The first activated at the base station transmitter The signal subvector transmitted at each dual-polarized antenna. For the vector of an inactive dual-polarized antenna, This is the serial number of the inactive dual-polarized antenna. This is for the transpose operation.

[0038] Furthermore, in step S2, the signal transmitted to the remote user receiver... According to the cascaded channel of the transmission surface Synthetic signal from base station transmitter and noise in the transmission region The signal generated and reflected to the near-end user receiver. According to the cascaded channels of the reflector , synthetic signal and noise in the reflection area Generation, signal and The calculation formulas are as follows:

[0039]

[0040]

[0041] in, ~ , ~ All are additive white Gaussian noise. This indicates that the mean is 0 and the variance is 0. The complex Gaussian distribution, This is for the transpose operation.

[0042] Furthermore, the cascaded channel of the transmission surface Through the base station transmitter The first dual-polarized antenna and the omnidirectional intelligent metasurface channel coefficients between the array elements and the omni-directional intelligent metasurface channel coefficients between the array elements and the far-end user receiving end established, the cascaded channel of the reflecting surface by the channel coefficients and the omni-directional intelligent metasurface channel coefficients between the array elements and the near-end user receiving end established, the channel and the calculation formulas are respectively:

[0043]

[0044]

[0045] wherein, , , , represents a complex Gaussian distribution with a mean of 0 and a variance of 1, is the serial number of the base station transmitting end dual-polarized antenna, is the total number of the base station transmitting end dual-polarized antenna, is the phase of the array element, is the serial number of the array element of the transmitting surface, is the set of the array element of the transmitting surface, is the serial number of the array element of the reflecting surface, is the set of the array element of the reflecting surface.

[0046] Further, the calculation formulas of the channel coefficients , and are respectively:

[0047]

[0048]

[0049]

[0050] wherein, is the path loss index, is the distance from the base station transmitting end dual-polarized antenna to the array element of the omni-directional intelligent metasurface, is the distance from the array element of the omni-directional intelligent metasurface to the far-end user receiving end,​​​ for the omni-directional intelligent metasurface is the distance from the m-th array element to the near-end user receiver, is the average path loss intensity per unit distance, is the phase shift of the m-th array element.

[0051] Further, in the step S3, the maximum likelihood estimation detection algorithm is respectively as follows:

[0052]

[0053]

[0054] wherein, corresponds to the index bit, is the antenna activation matrix obtained by maximum likelihood estimation detection, is the polarization matrix obtained by maximum likelihood estimation detection; corresponds to the symbol bit, is the constellation symbol corresponding to the modulation signal obtained by maximum likelihood estimation detection.

[0055] In a second aspect, a vehicle-to-everything user communication device based on polarization modulation, spatial modulation and omni-directional intelligent metasurface assistance includes a base station transmitting end, an omni-directional intelligent metasurface and a user receiving end.

[0056] Further, the omni-directional intelligent metasurface is a programmable electromagnetic metasurface, which divides the space into a transmission region and a reflection region, and the transmission region and the reflection region are respectively located on both sides of the omni-directional intelligent metasurface. The signals between the two regions are independently transmitted and do not interfere with each other, and the signals have no intensity loss after being transmitted or reflected by the omni-directional intelligent metasurface.

[0057] Further, the user receiving end includes a far-end user receiving end and a near-end user receiving end, the far-end user receiving end is located in the transmission region by default, the near-end user receiving end is located in the reflection region by default, and the positions of the far-end user receiving end and the near-end user receiving end can be interchanged.

[0058] Further, the base station transmitting end and the user receiving end each include a plurality of dual-polarized antennas, and each dual-polarized antenna supports vertical polarization and horizontal polarization.

[0059] In a third aspect, a memory is used to store the vehicle-to-everything user communication method based on polarization modulation, spatial modulation and omni-directional intelligent metasurface assistance.

[0060] The beneficial effects of the present application are:

[0061] ​(1) The application detects the index of the vehicle networking user receiving end antenna and polarization mode, and detects the amplitude phase modulation through another vehicle networking user receiving end, compared with the traditional omnidirectional intelligent super surface assisted power domain non-orthogonal multiple access technology, can suppress the interference between vehicle networking users without relying on continuous interference cancellation operation, effectively reduces the calculation complexity;

[0062] (2) The application uses omnidirectional intelligent super surface which integrates reflection and transmission characteristics, compensates for complex channel fading and enhances omnidirectional link reliability by using full spatial electromagnetic manipulation ability, improves the coverage range of the signal by optimizing the reflection / transmission phase configuration, further eliminates the signal coverage blind area in the vehicle networking scene, and enhances the deployment flexibility;

[0063] (3) The application multiplexes the space and polarization dimensions of each vehicle networking user through the horizontal and vertical component modulation of the dual-polarized antenna element, so that it can transmit signals from horizontal and vertical components at the same time, thereby improving the spectrum efficiency through multi-dimensional physical layer modulation, and reducing the hardware complexity by minimizing the number of radio frequency chains while maintaining spatial diversity gain;

[0064] (4) The application further reduces the energy consumption of the base station transmitting end by carrying part of the bit information on the index of the antenna and the index of the polarization mode, and is more environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0065] The application will be further described below in combination with the drawings and examples.

[0066] Figure 1 is the application scenario schematic diagram of the application;

[0067] Figure 2 is the signal transmission and reception process schematic diagram of the application;

[0068] Figure 3 is the bit error rate curve comparison schematic diagram of the application and the traditional scheme under different distances from the omnidirectional intelligent super surface to the user;

[0069] Figure 4 is the bit error rate curve comparison schematic diagram of the application under the condition of fixed modulation order and different number of transmitting antennas;

[0070] Figure 5 is the bit error rate curve comparison schematic diagram of the application under the condition of fixed number of transmitting antennas and different modulation orders;

[0071] Figure 6 is the bit error rate curve comparison schematic diagram of the application and the traditional scheme under the condition of total transmission rate of 8bit / s / Hz and different transmitting antenna configurations. DETAILED DESCRIPTION

[0072] The present invention will now be further described in conjunction with the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0073] like Figure 1 As shown, a vehicle-to-everything (V2X) user communication device based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance includes a base station transmitter, an omnidirectional intelligent metasurface, and a user receiver. The user receiver includes a remote user receiver. and near-end user receiver , and Corresponding to Figure 1 One of the connected car users.

[0074] Specifically, the base station transmitter is equipped with One antenna, this Each antenna consists of Composed of several dual-polarized antennas, used to transmit the synthesized signal to the omnidirectional smart metasurface. Each dual-polarized antenna supports both vertical and horizontal polarization and is subject to power constraints. polarization matrix under ,in, , polarization matrices Polarization information for horizontal and vertical components.

[0075] Specifically, the omnidirectional intelligent metasurface is equipped with Each array element, this The array elements are divided into two groups, with each group containing 10 array elements. These are used for signal transmission and signal reflection, respectively. Each array element can transmit an input signal and either transmit or reflect the signal to... or This omnidirectional intelligent metasurface is a programmable electromagnetic metasurface that divides space into a reflection region and a transmission region, located on opposite sides of the surface. Signal transmission between the two regions is independent and free from interference, and the signal experiences no intensity loss after transmission or reflection through the omnidirectional intelligent metasurface. Each element can have its electromagnetic properties altered by external control, thereby enabling simultaneous control of the transmission and reflection of incident electromagnetic waves.

[0076] Specifically, and All use One antenna is used to receive signals transmitted or reflected by the omnidirectional smart metasurface. Each antenna is made of each dual-polarized antenna also supports vertical polarization and horizontal polarization, wherein, by default located in the transmission region, by default located in the reflection region, and and the positions can be interchanged.

[0077] It should be noted that the channel coefficient between the base station transmitting end and the first dual-polarized antenna and the first array element of the omnidirectional intelligent metasurface is the channel coefficient between the first array element of the omnidirectional intelligent metasurface and the second and is and the non-line-of-sight (NLOS) channel all obeys an independent Rayleigh fading channel model, that is, ~, , ~, , ~, wherein represents a complex Gaussian distribution with a mean of 0 and a variance of 1. Each antenna should be able to receive a signal of a specific polarization completely isolated from the cross-polarization component. However, in practice, this ideal situation may not be suitable for dual-polarized antennas, because the cross-polarization discrimination (XPD) includes two effects, namely cross-polarization interference and cross-polarization ratio. Therefore, all channels also consider the spatial separation of cross-polarization discrimination and depolarization effects, and the cross-polarization discrimination is represented as:

[0078]

[0079] wherein, is used to measure the degree of polarization decorrelation, defined as the average ratio of co-polarization power to cross-polarization power, is the mathematical expectation. is the channel coefficient from the vertical polarization transmitting antenna to the vertical polarization receiving antenna, is the channel coefficient from the horizontal polarization transmitting antenna to the horizontal polarization receiving antenna, is the channel coefficient from the vertical polarization transmitting antenna to the horizontal polarization receiving antenna, is the channel coefficient from the horizontal polarization transmitting antenna to the vertical polarization receiving antenna. is the polarization discrimination factor, also known as the channel XPD parameter. The larger the value, the smaller the inter-polarization leakage, indicating that the channel maintains the polarization better, , These are the power scaling factors for the common-polarization channel and the cross-polarization channel, respectively. The actual general channel model is the Ricean channel model, whose expression is:

[0080]

[0081] in, The direct-path coefficients are represented by an all-one matrix, which represents the direct path. The non-direct channel coefficients are represented by a random matrix, which represents non-direct path effects such as scattering and multipath. The Rice factor represents the ratio of the direct component power to the scattered component power, reflecting the importance of the direct path. , All are weighting factors, ensuring The total power is normalized. Furthermore, the noise figures in the transmission and reflection regions are respectively... and Both types of noise are additive white Gaussian noise, i.e. ~ , ~ ,in This indicates that the mean is 0 and the variance is 0. The complex Gaussian distribution.

[0082] like Figure 2 As shown, a vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance includes the following steps:

[0083] S1. Signal Synthesis: The bit data stream transmitted by the base station transmitter is divided into index bits and symbol bits. The dual-polarized antenna is activated and the polarization mode is selected based on the index bits. A phase-shift keying modulation signal is generated based on the symbol bits. The signal is then synthesized at the activated dual-polarized antenna. And send it to the omnidirectional intelligent metasurface;

[0084] S2. Multiple access transmission of signals: Establishing a cascaded channel for omnidirectional intelligent metasurface transmission surfaces. Cascaded channels with reflectors Based on the synthesized signal from the base station transmitter Calculate the transmission to signal and reflection to signal And send it to the corresponding user receiving end;

[0085] S3. Signal Detection and Demodulation: Signals are detected using a maximum likelihood estimation algorithm. and signal ,exist obtaining the index information and demodulating the index bits, in obtaining the modulation information and demodulating the symbol bits.

[0086] Specifically, the step S1 further comprises the following steps:

[0087] S11. According to the total number of dual-polarized antennas of the base station transmitting end and the total number of polarization modes , the length of the index bits is calculated , and the index bits with the length of are randomly generated ; according to the number of the base of the phase shift keying modulation signal , the length of the symbol bits is calculated , and the symbol bits with the length of are randomly generated . Preferably, the base station transmitting end is equipped with dual-polarized antennas and polarization modes, and the symbol modulation adopts binary phase shift keying modulation , then the length of the index bits is:

[0088]

[0089] the length of the symbol bits is:

[0090]

[0091] the index bits with the length of 2 and the symbol bits with the length of 2 are randomly generated, then the bit data of the base station transmitting end can be represented as:

[0092]

[0093] S12. According to the index information of the dual-polarized antennas of the base station transmitting end carried by the index bits, the dual-polarized antenna with the corresponding serial number is activated, and the antenna activation matrix of the dual-polarized antenna is calculated ; according to the index information of the polarization mode carried by the index bits, the polarization mode with the corresponding serial number is selected, and the polarization matrix of the selected polarization mode is calculated ; according to the modulation information carried by the symbol bits, the constellation symbol of the phase shift keying signal is obtained ; first, according to the polarization matrix and the constellation symbol , the signal vector of the base station transmitting end dual-polarized antenna under the selected polarization mode and the used modulation signal is calculated , and then according to the antenna activation matrix The composite signal is calculated at the activated dual-polarized antenna The antenna activation matrix is preferably set as

[0094]

[0095] The polarization pattern matrix is preferably set as

[0096]

[0097] According to the index bits , the first bit is used for antenna index, and the second bit is used for polarization mode index, then the selection is and According to , the constellation symbol of the binary phase shift keying signal .

[0098] The signal vector of the dual-polarized antenna under the action of the polarization matrix and the constellation symbol is :

[0099]

[0100] The composite signal is:

[0101]

[0102] Specifically, in step S2, the signal transmitted to the is generated according to the cascaded channel of the transmission surface , the composite signal of the base station transmitting end and the noise located in the transmission area , and the signal reflected to the is generated according to the cascaded channel of the reflection surface , the composite signal and the noise located in the transmission area , wherein the cascaded channel of the transmission surface is established through the channel coefficient between the first dual-polarized antenna of the base station transmitting end and the first array element of the omnidirectional intelligent metasurface, and the channel coefficient between the first array element of the omnidirectional intelligent metasurface and , and the cascaded channel of the reflection surface is established through the channel coefficient and the first array element of the omnidirectional intelligent metasurface and Channel coefficients between Establishment. Preferably, the omnidirectional intelligent metasurface is constructed from... Composed of multiple array elements, it supports mode switching protocols, enabling simultaneous signal transmission and reflection, with both the transmission and reflection surfaces having an array element count of [number missing]. The set of transmission array elements is The set of reflector elements is . Use a single dual-polarized antenna located in the transmission region. A single dual-polarized antenna is also used, located in the reflection region. Path loss index. The base station transmitter Distance from a dual-polarized antenna to the first element of the omnidirectional smart metasurface The first array element of the omnidirectional intelligent metasurface distance The first array element of the omnidirectional intelligent metasurface distance Average path loss intensity per unit distance Then the base station transmitter's first The channel coefficient between the dual-polarized antenna and the first element of the omnidirectional smart metasurface for:

[0103]

[0104] The first element of the omnidirectional intelligent metasurface and Channel coefficients between Represented as:

[0105]

[0106] The first element of the omnidirectional intelligent metasurface and Channel coefficients between Represented as:

[0107]

[0108] in, The transmission coefficient of the first array element. Let be the reflection coefficient of the first element, satisfying and .

[0109] Preferably, the channel matrix from the first dual-polarized antenna at the base station transmitter to the first element of the omnidirectional smart metasurface is:

[0110]

[0111] Such matrices are 128 in total, each corresponding to 1 array element; the channel matrix from the 2nd dual-polarized antenna of the base station transmitting end to the 1st array element of the omnidirectional intelligent metasurface is:

[0112]

[0113] Such matrices are 128 in total, each corresponding to 1 array element; the channel coefficient between the 1st array element of the omnidirectional intelligent metasurface and is:

[0114]

[0115] Such matrices are 64 in total, each corresponding to 1 transmissive surface array element; the channel coefficient between the 1st array element of the omnidirectional intelligent metasurface and is:

[0116]

[0117] Such matrices are 64 in total, each corresponding to 1 reflective surface array element. Then the transmissive surface cascaded channel is:

[0118]

[0119] The reflective surface cascaded channel is:

[0120]

[0121] It should be noted that the signal transmitted to is generated according to the transmissive surface cascaded channel , the synthesized signal of the base station transmitting end and the noise located in the transmission area, and the signal reflected to is generated according to the reflective surface cascaded channel , the synthesized signal and the noise located in the transmission area. Preferably, the received signal is:

[0122]

[0123] The received signal of is:

[0124] ​

[0125] Specifically, in step S3, the bit data corresponding to the transmission symbol is By maximum likelihood estimation, the detection traverses all the symbols, antenna activation matrices and polarization matrices to obtain and wherein, The corresponding antenna activation matrix , The corresponding polarization matrix Finally, according to the mapping table, the corresponding index bits are demodulated, and the algorithm is as follows:

[0126]

[0127] The bit data corresponding to the transmission symbol is Similarly, by maximum likelihood estimation, the detection traverses all the symbols, antenna indices and polarization matrices to obtain , and The corresponding constellation symbol Finally, according to the mapping table, the corresponding index bits are demodulated, and the algorithm is as follows:

[0128]

[0129] Preferably, the mapping rules between the bit data , the antenna activation matrix , the polarization matrix , the constellation symbol and the transmission symbol are shown in Table 1.

[0130] Table 1

[0131]

[0132] In order to verify the superiority of the omnidirectional intelligent metasurface assisted vehicle networking user communication method based on polarization modulation and spatial modulation proposed in the application, the application adopts the following four strategies to compare the performance of the proposed scheme horizontally or vertically, and the application is verified in the Matlab R2023a environment:

[0133] (1) Observe the bit error rate curves of the application and the traditional scheme at different distances from the omnidirectional intelligent metasurface to the vehicle networking user equipment;

[0134] (2) Observe the bit error rate curves of the application under the same modulation order and different numbers of transmission antennas;

[0135] (3) Observe the bit error rate curves of the application under the same number of transmission antennas and different modulation orders.

[0136] (4) Observe the bit error rate curves of the application and the traditional scheme under the same and different transmission rates.

[0137] The bit error rate (BER) performance of the PSM-STAR-RIS and TITO-STAR-RIS systems as a function of the distance of the vehicular user to the omnidirectional intelligent surface (STAR-RIS) is shown in Figure 3 Since the TITO-STAR-RIS system does not have polarization modulation, the transmission rate is 3 bits / s / Hz. As the distance between the vehicular user and the STAR-RIS increases, the BER of both systems rises, which indicates a decrease in channel quality due to an increase in path loss. It is worth noting that the PSM-STAR-RIS system exhibits better BER performance than the TITO-STAR-RIS system at all distances, especially at shorter distances, highlighting its superior ability to maintain channel reliability. However, when the distance exceeds a certain threshold (e.g., 50 m), the performance gap between the two systems narrows, indicating that both systems experience similar limitations under severe propagation conditions. This analysis shows that the distance of the vehicular user to the STAR-RIS plays a key role in determining system performance and emphasizes the importance of optimizing spatial deployment for STAR-RIS-assisted communication systems.

[0138] Preferably, in the PSM-STAR-RIS system using QPSK modulation, the BER performance for different numbers of antennas is shown in Figure 4 while in the same system using 16 antennas, the BER performance for different modulation orders is shown in Figure 5 The simulation results show that as the transmission rate of the UE increases, the BER performance deteriorates, and at a BER level of , an approximately 3 dB difference is observed for every 2 bits / s / Hz increase in the transmission rate. This result indicates that the impact of increasing the number of antennas on the BER performance of one vehicular user is comparable to the impact of increasing the modulation order on the BER performance of another vehicular user. This finding highlights the relationship between the spatial diversity achieved by increasing the number of antennas and the spectral efficiency achieved by adopting higher modulation orders. While both factors have a significant impact on the error performance of the system, a balance must be struck between them in order to optimize the overall performance of the system.

[0139] Preferably, the BER performance of the PSM-STAR-RIS system with a total transmission rate of 8 bits / s / Hz is shown in Figure 6 , which employs three different configurations. When and The PSM-STAR-RIS system has a significantly better performance than the conventional TITO-STAR-RIS system at high SNR when transmitting the same number of bits. Specifically, the BER performance of the PSM-STAR-RIS system exceeds that of the conventional system when , and , which is consistent with the conclusion drawn from Figure 3 . In addition, the PSM-STAR-RIS system achieves the best BER performance when uses BPSK under different resource allocation scenarios. Meanwhile, the BER performance of the PSM-STAR-RIS system remains relatively unaffected when uses QPSK. Therefore, the PSM-STAR-RIS system can benefit from a higher transmission rate without significantly affecting its BER performance in cases where has lower communication requirements.

[0140] In summary, the present application provides a vehicle-to-everything user communication method and device based on polarization modulation, spatial modulation, and omnidirectional intelligent surface assistance, aiming to address the challenges of poor signal coverage and low transmission efficiency faced by multiple vehicle-to-everything users accessing the communication surface in non-line-of-sight complex environments. The technical key points and protection points of the present application are as follows:

[0141] (1) A polarization spatial modulation transmitter is developed, which implicitly embeds additional bits by jointly utilizing the degrees of freedom in the polarization domain and the spatial domain, and achieves enhanced spectral efficiency through multi-dimensional physical layer modulation. This design minimizes the number of radio frequency chains while maintaining spatial diversity gain, thereby significantly reducing hardware complexity.

[0142] (2) The omnidirectional intelligent surface's full-space electromagnetic manipulation capability is used to compensate for complex channel fading and enhance omnidirectional link reliability. Through optimized reflection / transmission phase configuration, the proposed deployment strategy eliminates coverage blind spots in vehicle-to-everything scenarios.

[0143] (3) An orthogonal multi-user access framework is established to suppress interference between vehicle-to-everything users without relying on successive interference cancellation operations. By modulating the horizontal / vertical components based on dual-polarized antenna elements, the spatial and polarization dimensions of each vehicle-to-everything user are multiplexed, achieving simultaneous complexity reduction and spectral efficiency improvement compared to traditional architectures.

[0144] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and essence of the present application should be covered within the protection scope of the present application.​

Claims

1. A vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance, characterized in that, Includes the following steps: S1. Signal synthesis: Divide the bit data transmitted by the base station transmitter into index bits and symbol bits; The dual-polarized antenna is activated based on the index information of the base station transmitter dual-polarized antenna carried by the index bits, and the polarization mode is selected based on the index information of the polarization mode carried by the index bits. The constellation symbol of the phase shift keying modulation signal is obtained based on the modulation information carried by the symbol bits, and the phase shift keying modulation signal is generated. Based on the selected polarization mode and the obtained constellation symbol, the signal is synthesized at the activated dual-polarized antenna. And send it to the omnidirectional intelligent metasurface; S2. Multiple access transmission of signals: Establishing a cascaded channel for omnidirectional intelligent metasurface transmission surfaces. Cascaded channels with reflectors Based on the synthesized signal from the base station transmitter Calculate the signal transmitted to the remote user receiver. and the signal reflected to the near-end user receiver And send it to the corresponding user receiving end; S3. Signal Detection and Demodulation: Signals are detected using a maximum likelihood estimation algorithm. and signal The index information is obtained at the remote user receiver and the index bits are demodulated, while the modulation information is obtained at the near user receiver and the symbol bits are demodulated.

2. The vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance according to claim 1, characterized in that, Step S1 further includes the following steps: S11. Based on the total number of dual-polarized antennas at the base station transmitter. and total number of polarization modes Calculate the index bit length Randomly generated length is index bits Based on the radix of the phase shift keying modulation signal Calculate the length of the symbol bits Randomly generated length is symbol bits ; S12. Based on the index information of the dual-polarized antennas at the base station transmitter carried by the index bits, activate the dual-polarized antennas with the corresponding sequence numbers, and calculate the antenna activation matrix of the dual-polarized antennas. Based on the index information of the polarization mode carried by the index bits, select the polarization mode with the corresponding sequence number, and calculate the polarization matrix of the selected polarization mode. Based on the modulation information carried by the symbol bits, the constellation symbols of the phase shift keying modulation signal are obtained. First, based on the polarization matrix and constellation symbols Calculate the signal vector transmitted by the dual-polarized antenna at the base station transmitter under the selected polarization mode and the modulation signal used. Then, based on the antenna activation matrix The synthesized signal is calculated at the activated dual-polarized antenna. .

3. The vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance as described in claim 2, characterized in that... In step S11, the index bit length The calculation formula is: in, This refers to the total number of dual-polarized antennas at the base station transmitter. This represents the total number of polarization modes; The symbol bit length The calculation formula is: in, It is the radix of the phase shift keying modulation signal.

4. The vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance according to claim 2, characterized in that, In step S12, the antenna activation matrix The calculation formula is: in, This refers to the sequence number of the dual-polarized antenna activated at the base station transmitter. The polarization matrix The expression is: in, , These are the polarization information for the vertical and horizontal components, respectively. This is the sequence number of the polarization mode; The constellation symbol The expression is: in, , for Sub-symbols transmitted at the vertical component and the horizontal component respectively; The signal vector The calculation formula is: in, , These are sub-signals representing the vertical and horizontal components, respectively. The synthesized signal The calculation formula is: in, The first activated at the base station transmitter The signal subvector transmitted at each dual-polarized antenna. For the vector of an inactive dual-polarized antenna, This is the serial number of the inactive dual-polarized antenna. This is for the transpose operation.

5. The vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance according to claim 1, characterized in that, In step S2, the signal transmitted to the remote user receiver... According to the cascaded channel of the transmission surface Synthetic signal from base station transmitter and noise in the transmission region The signal generated and reflected to the near-end user receiver. According to the cascaded channels of the reflector , synthetic signal and noise in the reflection area Generation, signal and The calculation formulas are as follows: in, ~ , ~ All are additive white Gaussian noise. This indicates that the mean is 0 and the variance is 0. The complex Gaussian distribution, This is for the transpose operation.

6. The vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance according to claim 5, characterized in that, The cascaded channel of the transmission surface Through the base station transmitter The first dual-polarized antenna and the omnidirectional intelligent metasurface Channel coefficients between array elements And the first omnidirectional intelligent metasurface Channel coefficient between each array element and the remote user receiver Establish the cascaded channel of the reflective surface. Through channel coefficients And the first omnidirectional intelligent metasurface Channel coefficients between individual array elements and the near-end user receiver Establish, channel and The calculation formulas are as follows: in, ~ , ~ , ~ , This represents a complex Gaussian distribution with a mean of 0 and a variance of 1. This refers to the serial number of the dual-polarized antenna at the base station transmitter. This represents the total number of dual-polarized antennas at the base station transmitter. The phase of the array element. This refers to the serial number of the transmission array element. It is a collection of transmission surface elements. The index of the reflector element is denoted by . It is a set of reflective array elements.

7. The vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance according to claim 6, characterized in that, The channel coefficient , and The calculation formulas are as follows: in, This is the path loss index. For the base station transmitter From a dual-polarized antenna to an omnidirectional intelligent metasurface The distance between each array element, For the first omnidirectional intelligent metasurface The distance from each array element to the remote user receiver. For the first omnidirectional intelligent metasurface The distance from each array element to the near-end user receiver. The average path loss intensity per unit distance. For the first Phase shift of each array element.

8. The vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance according to claim 1, characterized in that, In step S3, the formulas for the maximum likelihood estimation detection algorithm at the far-end user receiver and the near-end user receiver are as follows: in, Corresponding index bits, This is the antenna activation matrix obtained through maximum likelihood estimation. The polarization matrix is ​​obtained through maximum likelihood estimation. Corresponding symbol bits, Let be the constellation symbol corresponding to the modulated signal detected by maximum likelihood estimation.

9. A communication device based on a vehicle-to-everything (V2X) user communication method assisted by polarization modulation, spatial modulation, and omnidirectional intelligent metasurface as described in any one of claims 1 to 8, characterized in that, It includes the base station transmitter, the omnidirectional intelligent metasurface, and the user receiver.

10. A communication device according to claim 9, characterized in that, The omnidirectional intelligent metasurface is a programmable electromagnetic metasurface that divides space into a transmission region and a reflection region. The transmission region and the reflection region are located on opposite sides of the omnidirectional intelligent metasurface. Signals between the two regions are transmitted independently without interference, and there is no intensity loss after the signal is transmitted or reflected by the omnidirectional intelligent metasurface.

11. A communication device according to claim 10, characterized in that, The user receiver includes a remote user receiver and a near user receiver. The remote user receiver is located in the transmission region by default, and the near user receiver is located in the reflection region by default. The positions of the remote user receiver and the near user receiver can be interchanged.

12. A communication device according to claim 9, characterized in that, Both the base station transmitter and the user receiver include several dual-polarized antennas, and each dual-polarized antenna supports both vertical and horizontal polarization.

13. A memory, characterized in that, Used for storing a vehicle-to-everything (V2X) user communication method based on polarization modulation, spatial modulation, and omnidirectional intelligent metasurface assistance as described in any one of claims 1 to 8.

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