A robust transmission method and device for RIS-assisted Internet of Vehicles communication system

Abstract

The present invention discloses a robust transmission method and device for a RIS-assisted vehicle networking communication system, the method comprising the following steps: constructing a corresponding transmission waveform based on the channel characteristics and transmission requirements of the RIS-assisted vehicle networking communication system, mapping the bit data transmitted by the transmitter into a Doppler-robust orthogonal LFM waveform after space-time coding; based on the orthogonal LFM waveform and the Rice channel characteristics of the RIS-assisted vehicle networking communication system, converting the RIS-assisted vehicle networking communication system into a Doppler-robust real-domain linear model; estimating the real-domain equivalent channel of the real-domain linear model based on a linear channel estimation algorithm; and performing data demodulation on the transmission information in the RIS-assisted vehicle networking communication system based on a multi-antenna joint minimum Euclidean distance algorithm to realize information transmission. The present invention can effectively reduce the dependence on channel state information in fast fading scenarios, reduce pilot design overhead, and improve transmission reliability under fast fading conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of digital wireless communication, and in particular to a robust transmission method and device for a RIS-assisted vehicle networking communication system. Background Art

[0002] With the continuous development of 6G wireless communication technology, the standards for communication service quality are becoming increasingly stringent, requiring not only the delay to be controlled within 0.1ms, but also high-reliability transmission capabilities in high-speed mobile scenarios of 500 to 1000km / h. However, the existing 5G communication network is difficult to meet the needs of future intelligent transportation, and it is impossible to achieve an intelligent and reconfigurable wireless propagation environment. Therefore, in order to meet the strict requirements of the Internet of Vehicles for communication quality, researchers have begun to build an intelligent and reconfigurable wireless environment, rather than relying solely on traditional transceiver technology to adapt to wireless random channels.

[0003] At present, as a cost-effective solution, smart metasurface (RIS) has become an emerging technology that can provide a variety of valuable functions for the next generation of wireless communications and significantly improve the performance of RIS-assisted vehicle-to-vehicle communication systems; however, due to the lack of signal processing capabilities and the large number of passive reflection units in RIS, it causes high channel estimation overhead in delay-sensitive high-mobility scenarios, thereby increasing the delay of data transmission. Therefore, in order to reduce the channel estimation overhead, some new solutions have emerged, such as RIS grouping, estimation methods based on channel sparsity, and reference user methods. However, these technologies are usually suitable for low-mobility scenarios with long channel coherence time and cannot meet the robustness requirements of high-mobility vehicle-to-vehicle transmission. Summary of the invention

[0004] In order to overcome the defects and shortcomings of the prior art, the present invention provides a robust transmission method and device for a RIS-assisted vehicle networking communication system. The present invention makes full use of the ability of RIS to provide a virtual line-of-sight (LoS) path and create a Ricean fading environment in the vehicle networking communication system, redesigns the linear frequency modulation (LFM) signal (i.e., Chirp signal) in the traditional radar detection field into a transmission waveform that meets the needs of vehicle networking communication, and designs a corresponding receiving end detection algorithm according to the characteristics of the transmission waveform, converts the RIS-assisted high-mobility vehicle networking system into a Doppler-robust real-domain linear model, and constructs a channel estimation algorithm and a data demodulation algorithm based on the model that significantly reduce the channel estimation overhead, effectively reducing the dependence on channel state information in fast fading scenarios, reducing the pilot design overhead, and improving the transmission reliability under fast fading conditions, thereby effectively solving the transmission reliability problem of the prior art in high-mobility communication scenarios and the high channel estimation overhead problem generated after the introduction of RIS.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a robust transmission method for a RIS-assisted vehicle networking communication system, comprising the following steps:

[0007] Based on the channel characteristics and transmission requirements of the RIS-assisted IoV communication system, the corresponding transmission waveform is constructed, and the bit data transmitted by the transmitter is mapped into a Doppler-robust orthogonal LFM waveform after space-time coding;

[0008] Based on the orthogonal LFM waveform and the Ricean channel characteristics of the RIS-assisted IOV communication system, the RIS-assisted IOV communication system is transformed into a Doppler-robust real-domain linear model.

[0009] The real domain equivalent channel of the real domain linear model is estimated based on the linear channel estimation algorithm;

[0010] Based on the multi-antenna joint minimum Euclidean distance algorithm, data demodulation is performed on the transmission information in the RIS-assisted Internet of Vehicles communication system to achieve information transmission.

[0011] As a preferred technical solution, the RIS-assisted Internet of Vehicles communication system includes: a base station with multiple transmitting antennas, a RIS with multiple reflecting units, and a vehicle communication user with multiple single antennas;

[0012] The channel characteristics of the RIS-assisted IoV communication system are modeled as a Rice channel model based on the LoS path.

[0013] As a preferred technical solution, the bit data transmitted by the transmitting end is mapped into a Doppler robust orthogonal LFM waveform after space-time coding, which is specifically expressed as:

[0014] ;

[0015] in, Indicates n The bit data transmitted by the transmitting antenna, , and bit data The complementary signal is formed and the amplitude of the two signals is M -1, T Indicates the duration of the signal transmission symbol. represents the center carrier frequency, Indicates the frequency modulation slope of the LFM signal. It indicates a positive slope when When , it indicates a negative slope. The positive and negative slopes are orthogonal to each other. is the Up-Chirp signal, It is a Down-Chirp signal. The Up-Chirp signal and the Down-Chirp signal are orthogonal to each other.

[0016] As a preferred technical solution, the RIS-assisted Internet of Vehicles communication system is converted into a Doppler-robust real-domain linear model, specifically including:

[0017] The received signal at the receiving end is processed by matched filtering, and the orthogonal LFM waveform is passed through the Up-Chirp matched filter and the Down-Chirp matched filter to obtain the corresponding matched filtering result;

[0018] The corresponding matched filtering results are differentially detected, and the RIS-assisted Internet of Vehicles communication system is converted into a Doppler robust real domain linear model, which is specifically expressed as:

[0019] ;

[0020] Among them, h m represents the cascade channel vector from the base station to the mth mobile vehicle user after RIS reflection, represents the output vector of the orthogonal LFM waveform after the Up-Chirp matched filter, represents the output vector of the orthogonal LFM waveform after the Down-Chirp matched filter, Doppler shift The phase rotation caused by h mj , represent the amplitude and phase of the cascaded channel respectively, is the real domain equivalent channel vector from the base station to the mth mobile vehicle user after RIS reflection in the real domain linear model, N t represents the total number of transmitting antennas of the base station, is the real-domain equivalent transmitted signal vector of the real-domain linear model, , represents the noise after passing through the Up-Chirp matched filter and the Down-Chirp matched filter respectively. is the equivalent noise of the real domain linear model, B represents the signal bandwidth, Indicates the mutual correlation coefficient between the Up-Chirp signal and the Down-Chirp signal.

[0021] As a preferred technical solution, the orthogonal LFM waveform is passed through an Up-Chirp matched filter and a Down-Chirp matched filter to obtain a corresponding matched filtering result, which is specifically expressed as:

[0022] ;

[0023] .

[0024] As a preferred technical solution, the mutual correlation coefficient of the Up-Chirp signal and the Down-Chirp signal is specifically expressed as:

[0025] ;

[0026] in, , represent the Fresnel cosine function and the Fresnel sine function respectively.

[0027] As a preferred technical solution, the cascade channel vector from the base station to the mth mobile vehicle user after RIS reflection is specifically expressed as:

[0028] ;

[0029] ;

[0030] ;

[0031] in, , They represent the LoS part of the subchannel from the base station to the RIS and from the RIS to the mth mobile vehicle user, respectively. , represents the NLoS part of the subchannel from the base station to the RIS and from the RIS to the mth mobile vehicle user, C , V represents the Rice factor, represents the reflection matrix of the RIS array, Represents the phase shift of the nth reflection unit in the RIS array, and N represents the number of units in the RIS array.

[0032] As a preferred technical solution, the real domain equivalent channel of the real domain linear model is estimated based on a linear channel estimation algorithm, which is specifically expressed as:

[0033] ;

[0034] in, represents the estimated real-domain channel vector, represents the transmitted pilot symbol used for channel estimation, represents the received pilot symbol, T Indicates the duration of the signal transmission symbol.

[0035] As a preferred technical solution, data demodulation is performed on the transmission information in the RIS-assisted Internet of Vehicles communication system based on a multi-antenna combined minimum Euclidean distance algorithm, which is specifically expressed as follows:

[0036] ;

[0037] in, Represents the transmission data restored after data demodulation. It represents the differential detection result of the received signal at the mth receiving antenna. K represents the total number of high-mobility vehicle users with a single antenna, represents the estimated real-domain channel vector, represents the real-domain equivalent transmitted signal vector of the real-domain linear model.

[0038] The present invention also provides a robust transmission device of a RIS-assisted vehicle networking communication system, which is used to implement the above-mentioned robust transmission method of the RIS-assisted vehicle networking communication system. The device includes: a transmission waveform construction unit, a real number domain linear model construction unit, a channel estimation unit, and a data demodulation unit;

[0039] The transmission waveform construction unit is used to construct a corresponding transmission waveform based on the channel characteristics and transmission requirements of the RIS-assisted vehicle networking communication system, and map the bit data transmitted by the transmitter into a Doppler robust orthogonal LFM waveform after space-time coding;

[0040] The real number domain linear model construction unit is used to convert the RIS-assisted vehicle network communication system into a Doppler robust real number domain linear model based on the orthogonal LFM waveform and the Rice channel characteristics of the RIS-assisted vehicle network communication system;

[0041] The channel estimation unit is used to estimate the real domain equivalent channel of the real domain linear model based on a linear channel estimation algorithm;

[0042] The data demodulation unit is used to perform data demodulation on the transmission information in the RIS-assisted Internet of Vehicles communication system based on a multi-antenna joint minimum Euclidean distance algorithm to achieve information transmission.

[0043] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0044] (1) According to the requirements of the IoV communication system, the present invention redesigns the LFM signal with good matching correlation properties, effectively solving the problem of unstable signal transmission of the RIS-assisted IoV communication system under high-speed driving, and realizing a waveform design with higher transmission quality and Doppler tolerance under high-speed moving state.

[0045] (2) The present invention constructs a low-complexity receiving-end detection algorithm based on the characteristics of the transmitted waveform. The algorithm transforms the RIS-assisted IoV communication system into a Doppler-robust real-domain linear model, and uses the characteristics of the real-domain linear model to construct a low-complexity channel estimation method and data demodulation algorithm, which effectively solves the real-time tracking problem of channel phase information in high-speed mobile scenarios, reduces the channel estimation overhead of large-scale RIS arrays, and improves the reliability of system transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flowchart of a robust transmission method of a RIS-assisted vehicle networking communication system of the present invention;

[0047] Figure 2 A schematic diagram of data transmission of the RIS-assisted Internet of Vehicles communication system of the present invention;

[0048] Figure 3 A schematic diagram of a model of the RIS-assisted Internet of Vehicles communication system of the present invention;

[0049] Figure 4 Schematic diagram of the normalized time domain waveform of the LFM signal of the present invention;

[0050] Figure 5 It is a time domain schematic diagram of the matched output of the LFM signal after the matched filter of the present invention;

[0051] Figure 6 It is a time domain schematic diagram of the mismatch output of the LFM signal after passing through the matched filter of the present invention;

[0052] Figure 7 It is a performance simulation comparison diagram of the robust transmission method of the RIS-assisted vehicle networking communication system of the present invention; DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0054] Example 1

[0055] like Figure 1 As shown, this embodiment provides a robust transmission method for a RIS-assisted vehicle networking communication system, which solves the transmission reliability problem and high channel estimation overhead problem of the RIS-assisted vehicle networking communication system in the prior art. The robust transmission method improves the high reliability and low latency communication capability of the vehicle networking communication system in a fast fading environment. This embodiment is applied to a vehicle networking communication system in a high-speed mobile scenario with RIS assistance, and the vehicle networking communication system includes at least one Nt A base station (BS) with a transmitting antenna, at least one N RIS of the reflection unit and K A high-mobility vehicle communication user with a single antenna, the method comprises the following steps:

[0056] S1: Based on the channel characteristics and transmission requirements of the RIS-assisted IoV communication system, a transmission waveform suitable for robust transmission of the IoV communication system is constructed;

[0057] In this embodiment, RIS can provide a virtual LoS path and create a Ricean fading environment in the IoV communication system, so the channel characteristics of the RIS-assisted IoV communication system can be modeled as a Ricean channel model based on the LoS path;

[0058] The sub-channels from the base station to the RIS and from the RIS to the mth mobile vehicle user both show the Rice channel characteristics dominated by the LoS path, which are expressed as:

[0059] ;

[0060] ;

[0061] in, C , V represents the Rice factor, , They represent the LoS part of the subchannel from the base station to the RIS and from the RIS to the mth mobile vehicle user, respectively. , Represents the NLoS portion of the subchannels from the base station to the RIS and from the RIS to the mth mobile vehicle user;

[0062] The cascade channel from the base station to the mth mobile vehicle user after RIS reflection is:

[0063] ;

[0064] in, represents the reflection matrix of the RIS array, represents the phase shift of the nth reflection unit in the RIS array, and N represents the number of units in the RIS array;

[0065] In this embodiment, based on the Rice channel characteristics and transmission robustness requirements of the RIS-assisted vehicle networking communication system, the transmission waveform is selected as an LFM signal (i.e., Chirp signal) with good matching correlation properties. According to the transmission requirements of the RIS-assisted vehicle networking communication system, the transmission waveform is redesigned. Specifically, the relevant characteristics of the LFM signal are as follows:

[0066] The time domain expression of Chirp signal is:

[0067] ;

[0068] in, f 0 indicates the center carrier frequency, 0≤ t ≤ T , T Indicates the duration of the signal transmission symbol, Indicates the frequency modulation slope of the LFM signal. It indicates a positive slope when When , it indicates a negative slope, and the positive and negative slopes are orthogonal to each other.

[0069] In the LFM signal, the impulse response of the matched filter is:

[0070] ;

[0071] in, represents the conjugation operation.

[0072] The Chirp signal is processed by matched filtering and non-matched filtering, respectively, as follows:

[0073] ;

[0074] ;

[0075] in, B represents the signal bandwidth, , Represent the Fresnel cosine function and the Fresnel sine function respectively, specifically:

[0076] ;

[0077] ;

[0078] After matched filtering, the narrow pulse signal is approximately a Sinc function and the output amplitude is enlarged. The output after non-matched filtering is a small-amplitude signal with a relatively gentle amplitude. The matched filtering properties of the Chirp signal are beneficial to the design of a signal detection algorithm suitable for the Internet of Vehicles communication system.

[0079] Then, according to the robust transmission requirements of the RIS-assisted IoV communication system and the relevant characteristics of the LFM signal, the corresponding transmission waveform is constructed;

[0080] like Figure 2 As shown, the bit data transmitted by the transmitter is mapped into a multi-base amplitude complementary orthogonal LFM waveform after space-time coding, as follows:

[0081] ;

[0082] in, Indicates n The bit data transmitted by the transmitting antenna, and The complementary signal is formed and the amplitude of the two signals is M -1, in order to simplify the analysis, it is assumed in this example M =2. In addition, since the positive and negative frequency modulation slopes are orthogonal to each other, Have orthogonality.

[0083] In the orthogonal waveform middle, is the Up-Chirp signal, is a Down-Chirp signal. The two signals are orthogonal to each other, and the mutual correlation coefficient of the two signals is:

[0084] ;

[0085] The impulse response of the Up-Chirp matched filter is the Down-Chirp signal, and the impulse response of the Down-Chirp matched filter is the Up-Chirp signal.

[0086] S2: Based on the orthogonal transmission waveform and the Rice channel characteristics of the RIS-assisted vehicle network communication system, a linear system model with Doppler interference suppression capability is constructed, specifically:

[0087] Combination Figure 2 As shown, first, the received signal is processed by matched filtering at the receiving end, and the orthogonal waveform The output results of Up-Chirp and Down-Chirp matched filters are:

[0088] ;

[0089] ;

[0090] Then, the matched filtering results are differentially detected at the receiving end, and the RIS-assisted IoV communication system is converted into a Doppler-robust real-domain linear model:

[0091] ;

[0092] Among them, h m represents the cascade channel vector from the base station to the mth mobile vehicle user after RIS reflection, represents the output vector of the orthogonal waveform after the Up-Chirp matched filter, Represents the output vector of the orthogonal waveform after passing through the Down-Chirp matched filter; Doppler shift The phase rotation caused by Doppler is approximately constant within one symbol period. After being equivalent to a linear model, the phase rotation caused by Doppler is is eliminated, ensuring the robustness of the RIS-assisted IoV communication system in high-mobility scenarios; h mj , represent the amplitude and phase of the cascaded channel respectively, is the real domain equivalent channel vector from the base station to the mth mobile vehicle user after RIS reflection in the linear model, is the real domain equivalent of the linear model sending signal vector, , represents the noise after the matched filter, is the equivalent noise of the linear model.

[0093] S3: Based on the Doppler robust real domain linear model, a low-complexity channel estimation algorithm and data demodulation algorithm are constructed, including:

[0094] Combination Figure 2 As shown in the figure, according to the characteristics of the linear model, a low-complexity linear channel estimation algorithm (least square method) can be used to estimate the real domain equivalent channel of the linear model, effectively avoiding the real-time tracking of the instantaneous channel information in the complex domain, thereby reducing the high channel estimation overhead problem caused by the introduction of the RIS array. Specifically:

[0095] ;

[0096] in, represents the estimated real-domain channel vector, represents the transmitted pilot symbol used for channel estimation, represents a received pilot symbol;

[0097] Based on the Doppler-robust real-domain linear model and low-complexity channel estimation method, a multi-antenna joint minimum Euclidean distance algorithm is used to demodulate the transmission information in the RIS-assisted vehicle network communication system:

[0098] ;

[0099] in, Represents the transmission data restored after data demodulation. It represents the differential detection result of the received signal at the mth receiving antenna. K represents the total number of high-mobility vehicle users with a single antenna, represents the estimated real-domain channel vector, represents the real-domain equivalent transmitted signal vector of the real-domain linear model.

[0100] In this embodiment, the specific parameters are set as follows:

[0101] like Figure 3 As shown, the initial configuration of the RIS-assisted vehicle networking communication system is:

[0102] Assume that all location information is based on x , y , z The initial coordinate positions of the base station and RIS are (20, -15, 25) m Sum (-5, 45, 10) m .also, L Represents the coverage area of ​​RIS. The vehicle travels in this area at a speed of 50m / s and communicates with the base station. N t =128, N =64, K =8. The center carrier frequency of the LFM signal f 0=3.5 GHz , the signal bandwidth is B=2.5 MHz , the Ricean factor in Ricean fading is set to 10.

[0103] The MATLAB platform is used to compare the performance of the robust transmission method of the RIS-assisted vehicle networking communication system proposed in this embodiment with other transmission methods in related technologies in a high-mobility scenario to illustrate the effect of this embodiment:

[0104] like Figure 4 As shown in the figure, it is the time domain waveform of the transmitted symbol of the LFM signal, and the transmitted code element is 0011. When the transmitted code element is 1, the signal is modulated into an Up-Chirp waveform, and the modulation frequency increases linearly with time; when the transmitted code element is 0, the signal is modulated into a Down-Chirp waveform, and the modulation frequency decreases linearly with time. In the LFM signal, the signal frequency changes linearly within a certain period of time. Since the frequency modulation slopes of different polarities have good orthogonality, different frequency modulation slopes can be used to represent different data, thereby realizing information transmission.

[0105] like Figure 5 , Figure 6 As shown, it is the time domain diagram of the LFM signal after passing through the matched filter. Figure 5 The matching output result of the LFM signal is shown. After matched filtering, the signal is approximately a narrow pulse of the Sinc function with relatively concentrated energy. Figure 6is the mismatched output result of the LFM signal, and the amplitude is relatively flat. The matched filtering characteristics of the LFM signal can be used to perform differential detection on the output result after filtering, and a real domain linear model with Doppler robustness can be derived. From the above results, it can be seen that the LFM signal has good matching correlation, concentrated energy after pulse compression, and is insensitive to frequency deviation and Doppler effect. When applied to the Internet of Vehicles communication system, it can enhance the system's ability to resist frequency deviation and multipath fading.

[0106] like Figure 7 As shown, in the RIS-assisted high-mobility Internet of Vehicles communication scenario, the robust transmission method designed by the present invention is compared with the prior art in terms of transmission reliability. As the user's moving speed increases, the communication performance of the prior art gradually decreases; while the transmission method proposed by the present invention can maintain relatively stable communication capabilities within a larger speed variation range, which verifies that the robust transmission method of the present invention has the advantage of maintaining relatively reliable communication capabilities in a high-mobility Internet of Vehicles communication system.

[0107] Example 2

[0108] This embodiment provides a robust transmission device of a RIS-assisted vehicle networking communication system, which is used to implement the robust transmission method of the RIS-assisted vehicle networking communication system of the above-mentioned embodiment 1. The device includes: a transmission waveform construction unit, a real number domain linear model construction unit, a channel estimation unit, and a data demodulation unit;

[0109] In this embodiment, the transmission waveform construction unit is used to construct a corresponding transmission waveform based on the channel characteristics and transmission requirements of the RIS-assisted vehicle networking communication system, and map the bit data transmitted by the transmitter into a Doppler-robust orthogonal LFM waveform after space-time coding;

[0110] In this embodiment, the real domain linear model construction unit is used to convert the RIS-assisted Internet of Vehicles communication system into a Doppler robust real domain linear model based on the orthogonal LFM waveform and the Ricean channel characteristics of the RIS-assisted Internet of Vehicles communication system;

[0111] In this embodiment, the channel estimation unit is used to estimate the real domain equivalent channel of the real domain linear model based on a linear channel estimation algorithm;

[0112] In this embodiment, the data demodulation unit is used to perform data demodulation on the transmission information in the RIS-assisted Internet of Vehicles communication system based on a multi-antenna joint minimum Euclidean distance algorithm to achieve information transmission.

[0113] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A robust transmission method for a RIS-assisted vehicle networking communication system, characterized in that: The steps include: Based on the channel characteristics and transmission requirements of the RIS-assisted IoV communication system, the corresponding transmission waveform is constructed, and the bit data transmitted by the transmitter is mapped into a Doppler-robust orthogonal LFM waveform after space-time coding; Based on the orthogonal LFM waveform and the Ricean channel characteristics of the RIS-assisted IOV communication system, the RIS-assisted IOV communication system is transformed into a Doppler-robust real-domain linear model. The converting of the RIS-assisted Internet of Vehicles communication system into a Doppler robust real-domain linear model specifically includes: The received signal at the receiving end is processed by matched filtering, and the orthogonal LFM waveform is passed through the Up-Chirp matched filter and the Down-Chirp matched filter to obtain the corresponding matched filtering result; The corresponding matched filtering results are differentially detected, and the RIS-assisted Internet of Vehicles communication system is converted into a Doppler robust real domain linear model, which is specifically expressed as: ； Among them, h m represents the cascade channel vector from the base station to the mth mobile vehicle user after RIS reflection, represents the output vector of the orthogonal LFM waveform after the Up-Chirp matched filter, represents the output vector of the orthogonal LFM waveform after the Down-Chirp matched filter, Doppler shift The phase rotation caused by h mj , represent the amplitude and phase of the cascaded channel respectively, is the real domain equivalent channel vector from the base station to the mth mobile vehicle user after RIS reflection in the real domain linear model, N t represents the total number of transmitting antennas of the base station, is the real-domain equivalent transmitted signal vector of the real-domain linear model, , represents the noise after passing through the Up-Chirp matched filter and the Down-Chirp matched filter respectively. is the equivalent noise of the real domain linear model, B represents the signal bandwidth, Represents the mutual correlation coefficient between the Up-Chirp signal and the Down-Chirp signal, T Indicates the duration of the signal transmission symbol. Indicates n The bit data transmitted by the root transmitting antenna; The real domain equivalent channel of the real domain linear model is estimated based on the linear channel estimation algorithm; Based on the multi-antenna joint minimum Euclidean distance algorithm, data demodulation is performed on the transmission information in the RIS-assisted Internet of Vehicles communication system to achieve information transmission.

2. The robust transmission method of the RIS-assisted vehicle networking communication system according to claim 1 is characterized in that: The RIS-assisted Internet of Vehicles communication system includes: a base station with multiple transmitting antennas, a RIS with multiple reflecting units, and a vehicle communication user with multiple single antennas; The channel characteristics of the RIS-assisted IoV communication system are modeled as a Rice channel model based on the LoS path.

3. The robust transmission method of the RIS-assisted vehicle networking communication system according to claim 1, characterized in that: The bit data transmitted by the transmitting end is mapped into a Doppler robust orthogonal LFM waveform after space-time coding, which is specifically expressed as: ； in, Indicates n The bit data transmitted by the transmitting antenna, , and bit data The complementary signal is formed and the amplitude of the two signals is M -1, T Indicates the duration of the signal transmission symbol. represents the center carrier frequency, Indicates the frequency modulation slope of the LFM signal. It indicates a positive slope when When , it indicates a negative slope. The positive and negative slopes are orthogonal to each other. is the Up-Chirp signal, It is a Down-Chirp signal. The Up-Chirp signal and the Down-Chirp signal are orthogonal to each other.

4. The robust transmission method of the RIS-assisted vehicle networking communication system according to claim 1, characterized in that: The orthogonal LFM waveform passes through the Up-Chirp matched filter and the Down-Chirp matched filter to obtain the corresponding matched filtering results, which are specifically expressed as: ； in, T Indicates the duration of the signal transmission symbol. B Indicates the signal bandwidth.

5. The robust transmission method of the RIS-assisted vehicle networking communication system according to claim 1, characterized in that: The mutual correlation coefficient of the Up-Chirp signal and the Down-Chirp signal is specifically expressed as: ； in, , represent the Fresnel cosine function and the Fresnel sine function respectively, T Indicates the duration of the signal transmission symbol. B Indicates the signal bandwidth.

6. The robust transmission method of the RIS-assisted vehicle networking communication system according to claim 1, characterized in that: The cascade channel vector from the base station to the mth mobile vehicle user after RIS reflection is specifically expressed as: ； ； ； in, , They represent the LoS part of the subchannel from the base station to the RIS and from the RIS to the mth mobile vehicle user, respectively. , represents the NLoS part of the subchannel from the base station to the RIS and from the RIS to the mth mobile vehicle user, C , V represents the Rice factor, represents the reflection matrix of the RIS array, Represents the phase shift of the nth reflection unit in the RIS array, and N represents the number of units in the RIS array.

7. The robust transmission method of the RIS-assisted vehicle networking communication system according to claim 1, characterized in that: The data demodulation of the transmission information in the RIS-assisted Internet of Vehicles communication system is performed based on the multi-antenna joint minimum Euclidean distance algorithm, which is specifically expressed as follows: ； in, Represents the transmission data restored after data demodulation. It represents the differential detection result of the received signal at the mth receiving antenna. K represents the total number of high-mobility vehicle users with a single antenna, represents the estimated real-domain channel vector, represents the real-domain equivalent transmitted signal vector of the real-domain linear model.

8. A robust transmission device for a RIS-assisted vehicle networking communication system, characterized in that: A robust transmission method for a RIS-assisted vehicle networking communication system according to any one of claims 1 to 7, the device comprising: a transmission waveform construction unit, a real domain linear model construction unit, a channel estimation unit, and a data demodulation unit; The transmission waveform construction unit is used to construct a corresponding transmission waveform based on the channel characteristics and transmission requirements of the RIS-assisted vehicle networking communication system, and map the bit data transmitted by the transmitter into a Doppler robust orthogonal LFM waveform after space-time coding; The real number domain linear model construction unit is used to convert the RIS-assisted vehicle network communication system into a Doppler robust real number domain linear model based on the orthogonal LFM waveform and the Rice channel characteristics of the RIS-assisted vehicle network communication system; The channel estimation unit is used to estimate the real domain equivalent channel of the real domain linear model based on a linear channel estimation algorithm; The data demodulation unit is used to perform data demodulation on the transmission information in the RIS-assisted Internet of Vehicles communication system based on a multi-antenna joint minimum Euclidean distance algorithm to achieve information transmission.

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