A high-low speed multi-user access method and system based on cross-domain in an OTFS system

Abstract

The application discloses a high-low speed multi-user access method and system based on cross-domain in an OTFS system, and relates to the technical field of wireless communication, which comprises the following steps: an OFDM sending end carries out first preprocessing on information symbols, and maps the information symbols to a time-delay-Doppler domain and allocates the information symbols to different users; a time-frequency domain conversion scheme is constructed based on the first preprocessing, and multi-user signals are converted from the time-delay-Doppler domain to the time-frequency domain to obtain a time-frequency domain composite signal; an OFDM receiving end receives the time-frequency domain composite signal, recovers the multi-user signals through time-frequency domain demodulation, carries out one-time detection on time-delay-Doppler domain signals of a low-speed sending end to obtain a low-speed signal detection result, carries out two-time detection on the low-speed signal detection result to obtain high-low speed sending end signals, and recovers the high-low speed sending end signals to the time-delay-Doppler domain. The application can effectively avoid multi-user interference, thereby improving the spectral efficiency, and can improve the decoding accuracy of the system according to the processing conditions of a base station on a received complex signal in reality.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a high-low speed multi-user access method and system based on cross-domain in an OTFS system. BACKGROUND

[0002] The orthogonal time frequency space (OTFS) modulation technology has excellent performance in high-speed scenarios and has received extensive attention. Under the research background of OTFS combined with multiple access, some scholars have proposed an OTFS multiple access system without guard interval, and analysis shows that under the premise of ideal pulses, this scheme avoids multi-user interference (MUI), thereby proving that the system has higher spectral efficiency compared with the traditional guard band multiple access scheme. However, the system has high computational complexity in actual application, and the consideration of the channel model is relatively single in the multi-user access scenario, which cannot meet the processing conditions of the base station for the received complex signals in reality.

[0003] Therefore, it is necessary to design a high-low speed multi-user access scheme based on cross-domain in an OTFS system to solve the above problems. SUMMARY

[0004] In view of the above problems, the present application is proposed.

[0005] Therefore, in order to solve the above technical problems, the present application provides the following technical scheme: a high-low speed multi-user access method based on cross-domain in an OTFS system, comprising: a first preprocessing of information symbols by an OFDM sending end, and mapping the information symbols to a time delay-Doppler domain and assigning them to different users;

[0006] Based on the first preprocessing, a time-frequency domain conversion scheme is constructed, and the multi-user signal is converted from the time delay-Doppler domain to the time-frequency domain to obtain a time-frequency domain composite signal;

[0007] The OFDM receiving end receives the time-frequency domain composite signal and recovers the multi-user signal through time-frequency domain demodulation, and performs a first detection on the time delay-Doppler domain signal of the low-speed transmitting end to obtain a low-speed signal detection result;

[0008] The low-speed signal detection result is subjected to a second detection to obtain high-low speed transmitting end signals and recover them to the time delay-Doppler domain, thereby completing multi-user access.

[0009] As a preferred scheme of the high-low speed multi-user access method based on cross-domain in an OTFS system, the first preprocessing comprises,

[0010] The information bit stream is modulated to generate modulated symbols.

[0011] The modulated symbols are mapped onto a time-delay-Doppler grid, and the delay domain and Doppler domain are further divided into M equal parts and N equal parts, respectively. The calculation formula for the allocation method is as follows:

[0012]

[0013] in, Let be the set of allocation schemes, q be the user's index value, (k,l) be the coordinates of the time delay Doppler resource block occupied by the user in the subdivided time delay Doppler domain, and g1 and g2 be the number of grids occupied by dividing the time delay axis and Doppler axis into several equal parts respectively. To round down q / g1, u and v are the index values ​​after dividing the time delay axis and Doppler axis equally, (q) g1 It is the smallest non-negative integer that has the same remainder as q when divided by g1.

[0014] As a preferred embodiment of the cross-domain high- and low-speed multi-user access method based on the OTFS system described in this invention, the step of converting the multi-user signal from the time-delay Doppler domain to the time-frequency domain includes:

[0015] The allocated time-delay-Doppler domain signal is received, which includes a specific symbol block for each user;

[0016] The inverse symplectic finite Fourier transform is used to convert the time-delay-Doppler domain multi-user signal into a time-frequency domain signal;

[0017] The time-frequency domain signals of each user after ISFFT conversion are merged to form a composite time-frequency domain signal containing data from multiple users.

[0018] The time-frequency domain composite signal is packaged into a transmittable signal format and uploaded.

[0019] As a preferred embodiment of the cross-domain high- and low-speed multi-user access method based on the OTFS system described in this invention, the conversion to time-frequency domain signal includes:

[0020] The time-delayed Doppler domain signal x[k,l] after a fixed allocation method is converted into a time-frequency domain transmission signal using ISFFT. The calculation formula after conversion is as follows:

[0021]

[0022] n=0,1,...,((N / g2)-1),m=0,1...,((M / g1)-1)

[0023]

[0024] Where M and N correspond to the number of grids further allocated in the delay domain and Doppler domain, q is the user's index value, (k,l) is the coordinate of the delay Doppler resource block occupied by the user in the subdivided delay Doppler domain, g1 and g2 are the number of grids occupied by dividing the delay axis and Doppler axis into several parts respectively, and X[m,n] is the time-frequency domain signal after ISFFT processing, where m corresponds to the frequency axis and n corresponds to the time axis.

[0025] As a preferred embodiment of the cross-domain high- and low-speed multi-user access method based on the OTFS system described in this invention, wherein: the packetization into a transmittable signal format includes,

[0026] The time-frequency domain data from the high-speed and low-speed transmitters are processed separately. The time-frequency domain signals are converted to the time domain using Heisenberg transform and digital-to-analog conversion. The time-domain transmitted signal is then amplified by the transmitting antenna. The transmitted signal is represented as follows:

[0027]

[0028] Where X[m,n] is the time-frequency domain signal, s(t) is the time-domain transmitted signal, and g tx (t) represents the pulse shaping waveform at the transmitting end, M and N correspond to the number of grids further allocated in the delay domain and Doppler domain, T is the subcarrier spacing, and Δf is the duration of one symbol.

[0029] In the OTFS system, the channel is represented as follows:

[0030]

[0031] Where h(τ,υ) is the channel response to the time-delayed Doppler domain, and τ i It is time delay, υ i It's Doppler, h i It is the channel coefficient;

[0032] When receiving a signal, the received signal in the time-frequency domain is represented as follows:

[0033] r(t)=∫∫h(τ,υ)s(t-τ)e j2πυ(t-τ) dτdυ+w(t)

[0034] Where w(t) is the channel Gaussian white noise, and h(τ,υ) is the channel response to the time-delay Doppler domain.

[0035] As a preferred embodiment of the cross-domain high- and low-speed multi-user access method based on the OTFS system described in this invention, the first detection includes:

[0036] The time-frequency domain data of the low-speed transmitter is obtained by filtering the data from the low-speed transmitter using the MMSE algorithm.

[0037] The channel-related part is matrixed, and the matrix calculation formula for the received signal is as follows:

[0038] r = Hs + w

[0039]

[0040]

[0041] Where r is the time-frequency domain received vector, H is the MN×MN equivalent channel matrix, w is the noise vector, and h i Here, Π represents the channel coefficients, and Π represents the permutation matrix. It is a diagonal matrix;

[0042] Based on the OTFS input-output relationship, the formula for calculating the equivalent channel in the TF domain is as follows:

[0043]

[0044] The equivalent calculation formula for the DD field is as follows:

[0045]

[0046] Among them, H eq To determine the different equivalent channel representations in the time-delay Doppler domain and the time-frequency domain, I n and I m When using rectangular pulses, the pulse shaping matrix becomes the identity matrix F. m and F n Here are the DFT matrices normalized for points M and N. The operation is the Kronecker product. The operation is transpose and conjugate;

[0047] Substituting the TF-domain equivalent channel expression into the standard MMSE algorithm formula yields the time-frequency domain MMSE algorithm for the time-delay Doppler channel.

[0048] The time-frequency domain MMSE algorithm measures detection performance by minimizing the mean square error. The standard MMSE algorithm calculation formula is as follows:

[0049]

[0050] Where y represents the corresponding received signal, and H eq For the equivalent channel, σ 2 For noise power, () H This is the transpose conjugate operation.

[0051] As a preferred embodiment of the cross-domain high- and low-speed multi-user access method based on the OTFS system described in this invention, the step of restoring to the time-delay Doppler domain includes,

[0052] After a single detection at the low-speed transmitter is completed, the low-speed transmitter data after passing through the time-frequency low-speed channel is obtained.

[0053] The high-speed transmitter data at the receiver is obtained by subtracting the time-frequency domain composite signal data from the low-speed transmitter data, performing a second MMSE detection, and fully recovering the data to the entire time-frequency domain.

[0054] A symplectic finite Fourier transform operation is performed on the time-frequency domain signal of the high-speed transmitter to obtain high-speed user data in the time-delay-Doppler domain.

[0055] Another objective of this invention is to provide a high-speed and low-speed multi-user access system based on cross-domain OTFS. To solve the above-mentioned technical problems, this invention provides the following technical solution: a high-speed and low-speed multi-user access system based on cross-domain OTFS, comprising: a first preprocessing module, a time-frequency domain conversion module, a low-speed demodulation detection module, and a high-speed detection module;

[0056] The first preprocessing module is used by the OFDM transmitter to perform first preprocessing on the information symbols and map the information symbols to the delay-Doppler domain and allocate them to different users;

[0057] The time-frequency domain conversion module is used to construct a time-frequency domain conversion scheme based on the first preprocessing, and convert the multi-user signal from the time-delay Doppler domain to the time-frequency domain to obtain a time-frequency domain composite signal;

[0058] The low-speed demodulation detection module is used by the OFDM receiver to receive the time-frequency domain composite signal, recover the multi-user signal through time-frequency domain demodulation, and perform a detection on the time-delay Doppler domain signal of the low-speed transmitter to obtain the low-speed signal detection result.

[0059] The high-speed detection module is used to perform secondary detection on the low-speed signal detection result to obtain the high and low speed transmitting end signals, and restore them to the time delay Doppler domain to complete multi-user access.

[0060] A computer device includes a memory and a processor, the memory storing a computer program, characterized in that the processor executes the computer program to implement the steps of the cross-domain high- and low-speed multi-user access method based on the OTFS system as described above.

[0061] A computer-readable storage medium storing a computer program thereon, characterized in that, when the computer program is executed by a processor, it implements the steps of the cross-domain high- and low-speed multi-user access method based on the OTFS system as described above.

[0062] The beneficial effects of this invention are as follows: The cross-domain high- and low-speed multi-user access scheme designed in this invention in the OTFS system can effectively avoid multi-user interference, thereby improving spectrum efficiency, and improve the decoding accuracy of the system in light of the complex signal processing conditions of base stations in reality. Attached Figure Description

[0063] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 This is a schematic diagram of the terminal structure in the first embodiment of the present invention;

[0065] Figure 2 This is a flowchart of the transmitter in the first embodiment of the present invention;

[0066] Figure 3 This is a schematic diagram of the structure of the computer device in the third embodiment of the present invention;

[0067] Figure 4 This is an ISFFT processing diagram of the high-speed transmitter in the first embodiment of the present invention;

[0068] Figure 5 This is a data model diagram of the high-speed transmitter TF domain reserved in the first embodiment of the present invention;

[0069] Figure 6 This is a diagram of the TF domain data model of the low-speed transmitter in the first embodiment of the present invention;

[0070] Figure 7 This is a flowchart of the receiving end in the first embodiment of the present invention;

[0071] Figure 8 This is a graph showing the bit error rate detection results of the high- and low-speed transmitters in the first embodiment of the present invention. Detailed Implementation

[0072] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0073] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0074] Example 1

[0075] Reference Figure 1 This invention provides a method for cross-domain high- and low-speed multi-user access based on the OTFS system, as one embodiment of the present invention.

[0076] Before detailing the embodiments of this application, some related concepts will be explained for clarity.

[0077] OTFS (Orthogonal Time Frequency Space): OTFS is a novel modulation technique based on the time and frequency domain, enabling signal transmission in the Delay-Doppler (DD) domain. Compared to traditional OFDM technology, OTFS has stronger resistance to multipath and Doppler shift, making it suitable for multi-user communication in high-speed mobile scenarios.

[0078] Inverse Symplectic Finite Fourier Transform (ISFFT) and Symplectic Finite Fourier Transform (SFFT): ISFFT is a transformation method that converts a signal from the time-delay-Doppler domain to the time-frequency domain, typically used at the transmitting end. Conversely, SFFT is a transformation used at the receiving end to restore a signal from the time-frequency domain back to the time-delay-Doppler domain. These two transformations are the core of cross-domain processing in the OTFS system, used to realize the conversion and processing of signals between different domains.

[0079] Delay-Doppler Domain (DD): The Delay-Doppler domain is a method that describes the propagation characteristics of a signal in different transmission environments by introducing delay and Doppler shift. Delay represents the time delay of the signal, and Doppler shift represents the frequency shift caused by the relative motion of the transmitting and receiving devices. OTFS technology, by mapping and processing signals in the DD domain, can better handle signal transmission problems in high-speed mobile environments.

[0080] Time-Frequency Domain (TF): The time-frequency domain is a domain used to describe the changes of a signal in both time and frequency dimensions. In wireless communication, the frequency and time variations of a signal are key factors in analyzing channel characteristics. Analysis in the time-frequency domain allows for a more intuitive representation of the dynamic changes in the signal's spectral distribution over time. OTFS (Orthogonal Time-Frequency Space) modulation technology converts the signal from the time-delay-Doppler domain to the time-frequency domain for transmission in wireless channels. Processing in the TF domain enables effective anti-interference measures against frequency-selective fading and time-selective fading, ensuring signal stability and robustness in complex propagation environments.

[0081] Interleaved Allocation Scheme: The interleaved allocation scheme is a mechanism for allocating delay and Doppler resource blocks to different users. By dividing both the delay and Doppler axes into equal parts and distributing them to different users, it ensures that each user can effectively utilize resources in the delay-Doppler domain. This scheme's allocation strategy considers interference between users and the rational utilization of spectrum resources.

[0082] MMSE (Minimum Mean Square Error) Algorithm: The MMSE algorithm is a signal detection algorithm based on minimizing the mean square error, primarily used for signal processing at the receiver. This algorithm processes received multi-user signals in the time-frequency domain, filtering interference and recovering the signal to the time-delay-Doppler domain. MMSE optimizes the decoding process, reduces the bit error rate, and improves the accuracy of signal detection, making it particularly suitable for multi-user scenarios involving both high and low speeds.

[0083] Equivalent Channel Matrix: In an OTFS system, the equivalent channel matrix is ​​a mathematical model describing the relationship between the input and output signals. In a multi-user environment, signal transmission is affected by multipath effects and Doppler shift. The equivalent channel matrix expresses these effects in a matrix form, helping the system to demodulate and recover signals more accurately.

[0084] First, the cross-domain high- and low-speed multi-user access method based on the OTFS system provided in this application can be applied to, for example... Figure 1 In the terminal shown. For example... Figure 1 As shown, the terminal may include one or two ( Figure 1 Only one processor and a memory for storing data are shown in the diagram. The processor may be, but is not limited to, a processing system such as a microprocessor (MCU) or a programmable logic device (FPGA). The terminal may also include transmission devices for communication functions and input / output devices. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the terminal described above. For example, the terminal may also include components that are larger than... Figure 1The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0085] The memory can be used to store computer programs, such as the computer program corresponding to the cross-domain high- and low-speed multi-user access method based on the OTFS system in this embodiment. The processor executes various functional applications and data processing by running the computer program stored in the memory, thereby implementing the above-described method. The memory may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage systems, flash memory, or other non-volatile solid-state memory. In some instances, the memory may further include memory remotely located relative to the processor, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0086] Transmission devices are used to receive or send data over a network. This network includes wireless networks provided by the terminal's communication provider. In one example, the transmission device includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device may be a Radio Frequency (RF) module, used for wireless communication with the Internet.

[0087] like Figures 2-7 As shown, this embodiment of the invention provides a method for cross-domain high- and low-speed multi-user access in an OTFS system, which is applied to... Figure 1 Taking the terminal in the example, the explanation includes the following steps:

[0088] S1: The OFDM transmitter performs a first preprocessing step, which maps information symbols to the delay-Doppler domain and assigns them to different users.

[0089] Furthermore, the first preprocessing includes,

[0090] The information bit stream is modulated to generate modulated symbols; it should be noted that the modulation method used in this invention includes, but is not limited to, QAM modulation;

[0091] The modulated symbols are mapped onto a time-delay-Doppler grid, and the delay domain and Doppler domain are further subdivided into M and N equal parts, respectively. The user-occupied time-delay-Doppler resource block is a combination of the delay domain and the Doppler equal parts. The calculation formula for the allocation method is as follows:

[0092]

[0093] Where q represents the user's index value, i.e., the q-th user, (k,l) represents the coordinates of the time-delay Doppler resource block occupied by this user in the subdivided time-delay Doppler domain, and g1 and g2 represent the number of grids occupied by dividing the time-delay axis and Doppler axis into several equal parts respectively. This indicates rounding down q / g1. Assuming the total number of users is Q, then Q = g1g2. u and v represent the index values ​​after equally dividing the time delay axis and Doppler axis, where the index value u satisfies... Index value v satisfies (q) g1 Let g1 be the smallest non-negative integer that leaves the same remainder when q is divided by g1.

[0094] Specifically, the latency-Doppler resource blocks occupied by users are allocated after being subdivided along the latency axis and the Doppler axis, ensuring that the resource blocks of each user do not overlap, thus forming an effective multi-user resource allocation strategy.

[0095] S2: Construct a time-frequency domain conversion scheme based on the first preprocessing to convert the multi-user signal from the time-delay Doppler domain to the time-frequency domain;

[0096] Furthermore, converting multi-user signals from the time-delay Doppler domain to the time-frequency domain includes,

[0097] The allocated time-delay-Doppler domain signal is received, which includes a specific symbol block for each user;

[0098] The inverse symplectic finite Fourier transform is used to convert the time-delay-Doppler domain multi-user signal into a time-frequency domain signal; the allocated signal x[k,l] is then converted into a time-frequency domain transmitted signal X[m,n] using ISFFT. The calculation formula after the conversion is as follows:

[0099]

[0100] n=0,1,...,((N / g2)-1),m=0,1...,((M / g1)-1)

[0101]

[0102] Where M and N correspond to the number of grids further allocated in the delay domain and Doppler domain, q is the user's index value, (k,l) are the coordinates of the delay Doppler resource block occupied by the user in the subdivided delay Doppler domain, and g 1 and g 2 To divide the time delay axis and Doppler axis into several equal parts, X[m,n] represents the time-frequency domain signal after ISFFT processing, where m corresponds to the frequency axis and n corresponds to the time axis.

[0103] The time-frequency domain signals of each user after ISFFT transformation are combined to form a composite signal containing multi-user data.

[0104] The merged time-frequency domain signals are packaged into a transmittable signal format and prepared for transmission at the physical layer.

[0105] The time-frequency domain data from both the high-speed and low-speed transmitters are processed separately. Through Heisenberg transform and digital-to-analog conversion, the time-frequency domain signal X[m,n] is converted to the time domain, and then amplified by the transmitting antenna to obtain the time-domain transmitted signal s(t). The high-speed transmitter is represented as follows:

[0106]

[0107] Where X[m,n] is the time-frequency domain signal, s(t) is the time-domain transmitted signal, and g tx (t) represents the pulse shaping waveform at the transmitting end, M and N correspond to the number of grids further allocated in the delay domain and Doppler domain, T is the subcarrier spacing, and Δf is the duration of one symbol.

[0108] In the OTFS system, the channel is represented as follows:

[0109]

[0110] Where h(τ,υ) is the channel response to the time-delayed Doppler domain, and τ i It is time delay, υ i It's Doppler, h i It is the channel coefficient;

[0111] When receiving a signal, its representation in the time-frequency domain is as follows:

[0112] r(t)=∫∫h(τ,υ)s(t-τ)e j2πυ(t-τ) dτdυ+w(t)

[0113] Where w(t) is the channel Gaussian white noise, and h(τ,υ) is the channel response to the time-delay Doppler domain.

[0114] Furthermore, in a multi-user communication system, after the uplink transmission process is processed using the inverse symplectic finite Fourier transform, the signal of each user is mapped to a specific resource block in the time-delay-Doppler domain. When these resource blocks are transformed to the time-frequency domain, they will form a distribution characteristic with the same magnitude across the entire time-frequency plane. Based on this characteristic, for each individual user, only those resource blocks that can completely reconstruct the original time-frequency domain signal need to be selected during its transmission process.

[0115] Furthermore, given the inherent mathematical properties of ISFFT, under the same channel conditions, after multiple users have completed their ISFFT operations, different and non-overlapping time-frequency domain resource blocks can be carefully selected and allocated to each user, thereby ensuring that the data of all users can be evenly distributed within the complete time-frequency domain. This selection and allocation mechanism enables the transmitter to effectively manage the data mapping relationship between the delay-Doppler domain and the time-frequency domain, thereby achieving an efficient and reliable multi-user transmission scheme.

[0116] S3: The OFDM receiver receives the time-frequency domain composite signal and recovers the multi-user data through time-frequency domain demodulation. It performs a detection on the time-delay Doppler domain signal of the low-speed transmitter to obtain the time-delay Doppler domain signal of the low-speed transmitter.

[0117] Furthermore, a single test includes,

[0118] The MMSE algorithm is used to prioritize the selection of data from the low-speed transmitter, thereby obtaining the time-frequency domain data of the low-speed transmitter.

[0119] For ease of subsequent use, the channel-related part is matrixed. The matrix calculation formula for the received signal is as follows:

[0120] r = Hs + w

[0121]

[0122] Where r is the time-frequency domain received vector, H is the MN×MN equivalent channel matrix, w is the noise vector, and h i Here, Π represents the channel coefficients, and Π represents the permutation matrix. It is a diagonal matrix.

[0123] Based on the OTFS input-output relationship, the formula for calculating the equivalent channel in the TF domain is as follows:

[0124]

[0125] The equivalent calculation formula for the DD field is as follows:

[0126]

[0127] Among them, H eq To determine the different equivalent channel representations in the time-delay Doppler domain and the time-frequency domain, I n and I m When using rectangular pulses, the pulse shaping matrix becomes the identity matrix F. m and F n Here are the DFT matrices normalized for points M and N. The operation is the Kronecker product. The operation is transpose conjugate.

[0128] Substituting the TF-domain equivalent channel expression into the standard MMSE algorithm formula yields the time-frequency domain MMSE algorithm for the time-delay Doppler channel.

[0129] The time-frequency domain MMSE algorithm measures detection performance by minimizing the mean square error. The standard MMSE algorithm calculation formula is as follows:

[0130]

[0131] Where y represents the corresponding received signal, and H eq For the equivalent channel, σ 2 For noise power, () H This is the transpose conjugate operation.

[0132] Specifically, at the receiving end, a composite time-frequency signal from both high-speed and low-speed transmitters, occupying the entire time-frequency domain, can be obtained. To distinguish between the high-speed and low-speed transmitters and recover the high-speed transmitter data to the DD domain, this invention adopts the MMSE algorithm. This detection algorithm has two core aspects: first, it prioritizes the selection of low-speed transmitter signal data from the mixed signals; second, in the case of interleaved distribution, it utilizes the characteristics of the symplectic finite Fourier transform to recover the high-speed transmitter data to the DD domain. It is necessary to completely recover the time-frequency domain data to the entire time-frequency domain, but related interference will greatly affect the recovery accuracy, thereby affecting the bit error rate. Therefore, the MMSE detection algorithm, which is convenient for processing in the time-frequency domain, was chosen to improve the system bit error rate.

[0133] S4: Perform secondary detection on the low-speed signal detection result to obtain high-speed and low-speed transmitting end signals, and restore them to the time-delay Doppler domain.

[0134] Further steps to restore to the time-delayed Doppler domain include:

[0135] After the low-speed transmitter is correctly detected, the low-speed transmitter data after passing through the time-frequency low-speed channel is obtained.

[0136] The difference between the time-frequency domain composite signal and this data is obtained to get the high-speed transmitter data at the receiver. Secondary MMSE detection is performed to fully recover the entire time-frequency domain.

[0137] Perform a symplectic finite Fourier transform on the time-frequency domain signal of the high-speed transmitter to obtain high-speed user data in the DD domain.

[0138] Furthermore, the properties of the symplectic finite Fourier transform, in the demodulation process, also roughly consist of two steps, including...

[0139] The signal received from the base station contains data from multiple users. During the demodulation process in the time and frequency domain, each part of the time and frequency domain resource block contains complete data information of different users. The part containing user data is completely restored to the entire time and frequency domain.

[0140] The recovered signal is processed by performing a symplectic finite Fourier transform to recover the user's time-delayed Doppler signal.

[0141] Example 2

[0142] As an embodiment of the present invention, a cross-domain high- and low-speed multi-user access system based on the OTFS system is provided, comprising: a first preprocessing module, a time-frequency domain conversion module, a low-speed demodulation detection module, and a high-speed detection module;

[0143] The first preprocessing module is used by the OFDM transmitter to perform first preprocessing, and to map information symbols to the delay-Doppler domain and distribute them to different users through the first preprocessing.

[0144] The time-frequency domain conversion module is used to construct a time-frequency domain conversion scheme based on the first preprocessing to convert multi-user signals from the time-delay Doppler domain to the time-frequency domain;

[0145] The low-speed demodulation and detection module is used by the OFDM receiver to receive the time-frequency domain composite signal and recover the multi-user data through time-frequency domain demodulation, and to perform a detection on the time-delay Doppler domain signal of the low-speed transmitter to obtain the low-speed signal detection result.

[0146] The high-speed detection module is used to perform secondary detection on the low-speed signal detection result to obtain the high and low speed transmitting end signals and restore them to the time delay Doppler domain.

[0147] Specific limitations regarding cross-domain high- and low-speed multi-user access systems based on OTFS can be found in the above section on limitations of cross-domain high- and low-speed multi-user access methods based on OTFS, and will not be repeated here. Each module in the aforementioned cross-domain high- and low-speed multi-user access system based on OTFS can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in the computer device, or stored in the memory of the computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0148] Example 3

[0149] Reference Figure 3 This is the third embodiment of the present invention. Based on the first two embodiments, this embodiment provides a computer device, which can be a server, and its internal structure diagram can be as follows. Figure 3As shown, the computer device includes a processor, memory, and a network interface connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and databases. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media.

[0150] The computer device's database is used to store motion detection data. The computer device's network interface is used to communicate with external terminals via a network connection. When the computer program is executed by the processor, it implements the steps in any of the above embodiments of the sparse tensor computation acceleration method.

[0151] Those skilled in the art will understand that Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0152] In one embodiment, the present invention provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps in any of the above embodiments of the sparse tensor operation acceleration method.

[0153] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0154] Example 4

[0155] Reference Figure 8As an embodiment of the present invention, a method for cross-domain high- and low-speed multi-user access based on the OTFS system is provided. In order to verify the beneficial effects of the present invention, a simulation experiment is conducted for scientific demonstration.

[0156] Figure 8 The description shows the bit error rate statistics curves of the present invention at high and low speed transmitters with a data symbol signal-to-noise ratio of 0-25dB.

[0157] Basic parameter settings: OTFS delay Doppler domain grid size is M=32, N=32, carrier frequency f c The frequency is 4 GHz, the subcarrier spacing Δf is 15 kHz, and the maximum channel delay is l. max The maximum Doppler value is 3, k. max The value is 3, and the 4QAM symbol is used.

[0158] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for cross-domain high- and low-speed multi-user access in an OTFS system, characterized in that, include: The OFDM transmitter performs a first preprocessing on the information symbols and maps the information symbols to the delay-Doppler domain and assigns them to different users. Based on the first preprocessing, a time-frequency domain conversion scheme is constructed, and the multi-user signal is converted from the time-delay Doppler domain to the time-frequency domain to obtain a time-frequency domain composite signal; The OFDM receiver receives the time-frequency domain composite signal and recovers the multi-user signal through time-frequency domain demodulation. It then performs a detection on the time-delay Doppler domain signal of the low-speed transmitter to obtain the low-speed signal detection result. The low-speed signal detection result is subjected to secondary detection to obtain high-speed and low-speed transmitting end signals, and then restored to the time-delay Doppler domain to complete multi-user access; The single detection includes: The time-frequency domain data of the low-speed transmitter is obtained by filtering the data from the low-speed transmitter using the MMSE algorithm. The channel-related part is matrixed, and the matrix calculation formula for the received signal is as follows: r = Hs + w Where r is the time-frequency domain received vector, H is the MN×MN equivalent channel matrix, w is the noise vector, and h i Here, Π represents the channel coefficients, and Π represents the permutation matrix. It is a diagonal matrix; Based on the OTFS input-output relationship, the formula for calculating the equivalent channel in the TF domain is as follows: The equivalent calculation formula for the DD field is as follows: Among them, H eq To determine the different equivalent channel representations in the time-delay Doppler domain and the time-frequency domain, I n and I m When using rectangular pulses, the pulse shaping matrix becomes the identity matrix F. m and F n Here are the DFT matrices normalized for points M and N. The operation is the Kronecker product. The operation is transpose and conjugate; Substituting the TF-domain equivalent channel expression into the standard MMSE algorithm formula yields the time-frequency domain MMSE algorithm for the time-delay Doppler channel. The time-frequency domain MMSE algorithm measures detection performance by minimizing the mean square error. The standard MMSE algorithm calculation formula is as follows: Where y represents the corresponding received signal, and H eq For the equivalent channel, σ 2 For noise power, () H This is the transpose conjugate operation; The step of restoring to the time-delayed Doppler domain includes: After a single detection at the low-speed transmitter is completed, the low-speed transmitter data after passing through the time-frequency low-speed channel is obtained. The high-speed transmitter data at the receiver is obtained by subtracting the time-frequency domain composite signal data from the low-speed transmitter data, performing a second MMSE detection, and fully recovering the data to the entire time-frequency domain. A symplectic finite Fourier transform operation is performed on the time-frequency domain signal of the high-speed transmitter to obtain high-speed user data in the time-delay-Doppler domain.

2. The method for cross-domain high- and low-speed multi-user access in an OTFS system as described in claim 1, characterized in that: The first preprocessing includes, The information bit stream is modulated to generate modulated symbols; The modulated symbols are mapped onto a time-delay-Doppler grid, and the delay domain and Doppler domain are further divided into M equal parts and N equal parts, respectively. The calculation formula for the allocation method is as follows: in, Let be the set of allocation schemes, q be the user's index value, (k,l) be the coordinates of the time delay Doppler resource block occupied by the user in the subdivided time delay Doppler domain, and g1 and g2 be the number of grids occupied by dividing the time delay axis and Doppler axis into several equal parts respectively. To round down q / g1, u and v are the index values ​​after dividing the time delay axis and Doppler axis equally, (q) g1 It is the smallest non-negative integer that has the same remainder as q when divided by g1.

3. The method for cross-domain high- and low-speed multi-user access in an OTFS system as described in claim 2, characterized in that: The steps for obtaining the time-frequency domain composite signal include: The allocated time-delay-Doppler domain signal is received, which includes a specific symbol block for each user; The inverse symplectic finite Fourier transform is used to convert the time-delay-Doppler domain multi-user signal into a time-frequency domain signal; The time-frequency domain signals of each user after ISFFT conversion are merged to form a composite time-frequency domain signal containing data from multiple users. The time-frequency domain composite signal is packaged into a transmittable signal format and uploaded.

4. The method for cross-domain high- and low-speed multi-user access in an OTFS system as described in claim 3, characterized in that: The conversion to a time-frequency domain signal includes, The time-delayed Doppler domain signal x[k,l] after a fixed allocation method is converted into a time-frequency domain transmission signal using ISFFT. The calculation formula after conversion is as follows: n=0,1,...,((N / g2)-1),m=0,1...,((M / g1)-1) Where M and N correspond to the number of grids further allocated in the delay domain and Doppler domain, q is the user's index value, (k,l) is the coordinate of the delay Doppler resource block occupied by the user in the subdivided delay Doppler domain, g1 and g2 are the number of grids occupied by dividing the delay axis and Doppler axis into several parts respectively, and X[m,n] is the time-frequency domain signal after ISFFT processing, where m corresponds to the frequency axis and n corresponds to the time axis.

5. The method for cross-domain high- and low-speed multi-user access in an OTFS system as described in claim 4, characterized in that: The packaged signal format for transmission includes, The time-frequency domain data from the high-speed and low-speed transmitters are processed separately. The time-frequency domain signals are converted to the time domain using Heisenberg transform and digital-to-analog conversion. The time-domain transmitted signal is then amplified by the transmitting antenna. The transmitted signal is represented as follows: Where X[m,n] is the time-frequency domain signal, s(t) is the time-domain transmitted signal, and g tx (t) represents the pulse shaping waveform at the transmitting end, M and N correspond to the number of grids further allocated in the delay domain and Doppler domain, T is the subcarrier spacing, and Δf is the duration of one symbol. In the OTFS system, the channel is represented as follows: Where h(τ,υ) is the channel response to the time-delayed Doppler domain, and τ i It is time delay, υ i It's Doppler, h i It is the channel coefficient; When receiving a signal, the received signal in the time-frequency domain is represented as follows: r(t)=∫∫h(τ,υ)s(t-τ)e j2πυ(t-τ) dτdυ+w(t) Where w(t) is the channel Gaussian white noise, and h(τ,υ) is the channel response to the time-delay Doppler domain.

6. A system employing the cross-domain high- and low-speed multi-user access method based on OTFS system as described in any one of claims 1 to 5, characterized in that, include: The module consists of a first preprocessing module, a time-frequency domain conversion module, a low-speed demodulation and detection module, and a high-speed detection module. The first preprocessing module is used by the OFDM transmitter to perform first preprocessing on the information symbols and map the information symbols to the delay-Doppler domain and allocate them to different users; The time-frequency domain conversion module is used to construct a time-frequency domain conversion scheme based on the first preprocessing, and convert the multi-user signal from the time-delay Doppler domain to the time-frequency domain to obtain a time-frequency domain composite signal; The low-speed demodulation detection module is used by the OFDM receiver to receive the time-frequency domain composite signal, recover the multi-user signal through time-frequency domain demodulation, and perform a detection on the time-delay Doppler domain signal of the low-speed transmitter to obtain the low-speed signal detection result. The high-speed detection module is used to perform secondary detection on the low-speed signal detection result to obtain the high and low speed transmitting end signals, and restore them to the time delay Doppler domain to complete multi-user access.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the cross-domain high- and low-speed multi-user access method in the OTFS system according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the cross-domain high- and low-speed multi-user access method in the OTFS system according to any one of claims 1 to 5.

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