A communication method, device, medium and equipment based on MQAM-OFDM modulation

Abstract

The application belongs to the technical field of wireless communication, and particularly relates to a communication method, device, medium and equipment based on MQAM-OFDM modulation, which comprises the following steps: generating a random data source and performing MQAM modulation, generating a serial modulation signal, performing serial-parallel conversion and subcarrier mapping, and obtaining frequency domain subcarrier data; performing inverse fast Fourier transform on the frequency domain subcarrier data to generate time domain OFDM symbols, and adding a cyclic prefix to obtain a sending signal; transmitting the sending signal based on a multipath channel model; receiving the sending signal and removing the cyclic prefix part in the sending signal to obtain an effective OFDM signal; performing fast Fourier transform on the effective OFDM signal to recover frequency domain data and obtain a frequency domain receiving symbol sequence; performing channel estimation and equalization on the frequency domain receiving symbol sequence to obtain a frequency domain symbol estimation value; performing MQAM demodulation on the frequency domain symbol estimation value, and recovering parallel data streams into a serial bit stream, thereby completing data recovery.

Description

Technical Field

[0001] This application belongs to the field of wireless communication technology, specifically relating to a communication method, apparatus, medium, and device based on MQAM-OFDM modulation. Background Technology

[0002] Orthogonal Frequency Division Multiplexing (OFDM) technology has become a core physical layer technology for modern communication systems such as 4G / 5G and Wi-Fi due to its high spectral efficiency and strong resistance to multipath fading. However, OFDM systems still face challenges in practical applications, including peak-to-average power ratio (PAPR), sensitivity to synchronization errors, and high computational complexity.

[0003] While existing single-carrier systems are simple, they have significant shortcomings in spectral efficiency and multipath resistance. Therefore, in-depth modeling, simulation, and optimization of OFDM systems, and combining them with higher-order modulation (such as MQAM, M-ary Quadrature Amplitude Modulation) to improve performance, has important theoretical and engineering significance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this application is to provide a communication method, apparatus, medium, and device based on MQAM-OFDM modulation. This application aims to improve the spectral efficiency and transmission reliability of MQAM-OFDM systems in highly dynamic multipath channels through adaptive cyclic prefix and intelligent channel equalization mechanisms.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] A communication method based on MQAM-OFDM modulation includes: generating a random data source and performing MQAM modulation to generate a serial modulation signal; performing serial-to-parallel conversion and subcarrier mapping on the serial modulation signal to obtain frequency domain subcarrier data; performing inverse fast Fourier transform on the frequency domain subcarrier data to generate time domain OFDM symbols and adding a cyclic prefix to obtain a transmitted signal; transmitting the transmitted signal based on a multipath channel model; receiving the transmitted signal and removing the cyclic prefix portion to obtain a valid OFDM signal; performing fast Fourier transform on the valid OFDM signal to recover the frequency domain data and obtain a frequency domain received symbol sequence; performing channel estimation and equalization on the frequency domain received symbol sequence to obtain a frequency domain symbol estimate; performing MQAM demodulation on the frequency domain symbol estimate and restoring the parallel data stream to a serial bit stream to complete data recovery.

[0007] Optionally, generating a random data source and performing MQAM modulation to generate a serial modulation signal includes: generating a random integer sequence; adjusting the mapping of each integer symbol in the random integer sequence to generate a serial modulation signal.

[0008] Optionally, the step of performing serial-to-parallel conversion and subcarrier mapping on the serial modulation signal to obtain frequency domain subcarrier data includes: converting the serial modulation signal into a parallel data matrix; and mapping each row of the parallel data matrix to a subcarrier to form frequency domain subcarrier data.

[0009] Optionally, the step of performing an inverse fast Fourier transform on the frequency domain subcarrier data to generate time-domain OFDM symbols and adding a cyclic prefix to obtain the transmitted signal includes: performing an inverse fast Fourier transform on each row of the frequency domain subcarrier data to generate a time-domain signal matrix; estimating the maximum multipath delay domain Doppler frequency shift of the current channel, dynamically calculating and selecting the optimal cyclic prefix; and adding the optimal cyclic prefix to each OFDM symbol in the time-domain signal matrix.

[0010] Optionally, the multipath channel model includes a time-domain part and a frequency-domain part, wherein,

[0011] The time domain part is represented as follows:

[0012]

[0013] in, Indicates the time variable and delay variables Channel response under these conditions; Indicates the total number of distinguishable paths in the channel; Indicates the first The signal amplitude attenuates along the path and varies with time. change; Indicates the first Phase rotation term for the path; Indicates the first The phase of the path; Indicates the first The delay of the path; Represents the Dirac impulse function; Represents the imaginary unit;

[0014] The frequency domain portion is represented as follows:

[0015]

[0016] in, Indicates frequency and time variables The complex transmission function of the lower channel includes amplitude attenuation and phase rotation; Indicates the total number of distinguishable paths in the channel; Indicates the first Signal attenuation along the path, and its variation with time. change; Indicates the first Phase rotation term for the path; Indicates the first The phase of the path; Indicates the first The delay of the path; This represents a complex rotation caused by the path phase; Represents pi; It represents the imaginary unit.

[0017] Optionally, receiving the transmitted signal and removing the cyclic prefix portion therein to obtain a valid OFDM signal includes: performing frame synchronization on the transmitted signal; performing offset estimation and compensation on the frame-synchronized transmitted signal; removing the cyclic prefix portion in the offset-estimated and compensated transmitted signal, and retaining valid time-domain samples.

[0018] Optionally, the step of performing channel estimation and equalization on the frequency domain received symbol sequence to obtain frequency domain symbol estimates includes: estimating the channel frequency domain response based on pilot symbols or training sequences; and compensating the channel frequency domain response based on an intelligent equalization strategy to obtain frequency domain symbol estimates.

[0019] This application also provides a communication device based on MQAM-OFDM modulation. The device includes: a data generation and modulation unit for generating a random data source and performing MQAM modulation to generate a serial modulation signal; a serial-to-parallel conversion and subcarrier mapping unit for performing serial-to-parallel conversion and subcarrier mapping on the serial modulation signal to obtain frequency domain subcarrier data; a time-domain symbol generation unit for performing inverse fast Fourier transform on the frequency domain subcarrier data to generate time-domain OFDM symbols and adding a cyclic prefix to obtain a transmitted signal; a signal transmission unit for transmitting the transmitted signal based on a multipath channel model; a cyclic prefix removal unit for receiving the transmitted signal and removing the cyclic prefix portion therein to obtain a valid OFDM signal; a frequency domain recovery unit for performing fast Fourier transform on the valid OFDM signal to recover the frequency domain data and obtain a frequency domain received symbol sequence; a channel estimation and equalization unit for performing channel estimation and equalization on the frequency domain received symbol sequence to obtain a frequency domain symbol estimate; and a data demodulation and recovery unit for performing MQAM demodulation on the frequency domain symbol estimate and restoring the parallel data stream to a serial bit stream to complete data recovery.

[0020] This application also provides a storage medium including instructions that, when executed on a computer, cause the computer to perform the method as described in the preceding claim.

[0021] This application also provides an electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method as described in any of the preceding claims.

[0022] Compared with the prior art, the beneficial effects of this application are as follows:

[0023] This application integrates mechanisms such as high-order modulation, adaptive cyclic prefix, time-varying multipath channel modeling, and intelligent channel estimation and equalization. While maintaining high spectral efficiency, it can enhance the system's resistance to multipath fading and frequency offset in complex channel environments, effectively optimize the peak-to-average power ratio, and improve the robustness of signal recovery and the reliability of data transmission. It is suitable for high-dynamic and high-reliability communication scenarios such as 5G enhanced mobile broadband, vehicle-to-everything (V2X) and industrial IoT. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating a communication method based on MQAM-OFDM modulation, provided in an exemplary embodiment of this application.

[0025] Figure 2 This is a schematic diagram of the structure of a communication device based on MQAM-OFDM modulation, provided in another exemplary embodiment of this application;

[0026] Figure 3 This is a schematic diagram of the structure of a storage medium provided in another embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the structure of an electronic device provided in another embodiment of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] Figure 1 This application provides an exemplary embodiment of a communication method based on MQAM-OFDM modulation, such as... Figure 1 As shown, the method includes the following steps:

[0030] S100: Generates a random data source and performs MQAM modulation to generate a serial modulation signal. ;

[0031] In this step, a pseudo-random number generator is first used to generate a uniformly distributed sequence of random integers within the range [0, M-1] to simulate a binary information bitstream, where M is the modulation order (e.g., 4, 16, 64). For example, this can be achieved using MATLAB. randi The function () generates a random number sequence. The implementation process is as follows:

[0032]

[0033] in, This represents the total number of random integers generated.

[0034] Secondly, based on QAM modulation functions (such as those in MATLAB) qammod The function () performs constellation mapping on each integer sign in the random integer sequence to transform the random number sequence Converted to constellation point symbols on the complex plane (such as 16QAM, 64QAM), and a serial modulation signal is generated. In this context, each complex number represents an MQAM symbol, and the serial modulation signal... It is expressed as follows:

[0035]

[0036] in, Represents a sequence of random numbers. This indicates the order in the QAM modulation process.

[0037] S200: For serial modulation signals Perform serial-to-parallel conversion and subcarrier mapping to obtain frequency domain subcarrier data;

[0038] In this step, this embodiment uses a reshaping function (such as in MATLAB). reshape () function), for the serial modulation signal generated in step S100 Perform a serial-to-parallel conversion operation to reshape it into... N × K ( N Indicates the total number of subcarriers. Parallel frequency domain data matrix (representing the number of symbols carried on each subcarrier) This matrix can be represented as follows:

[0039]

[0040] Then, the matrix Each row in the matrix is ​​mapped to an independent subcarrier, forming a frequency domain subcarrier data matrix, which serves as the input for the subsequent inverse fast Fourier transform.

[0041] S300: Perform inverse fast Fourier transform on frequency domain subcarrier data to generate time domain OFDM symbols, and add a cyclic prefix to obtain the transmitted signal;

[0042] In this step, this embodiment applies the parallel frequency domain data matrix obtained in step S200. Each line in the code (i.e., the sequence of symbols on each subcarrier) is executed. N The inverse fast Fourier transform (IFFT) is used to convert complex symbols in the frequency domain into a sequence of OFDM symbol samples in the time domain, and to generate a time-domain signal matrix. The specific steps are as follows:

[0043]

[0044] Subsequently, based on real-time channel state information, the time-domain signal matrix is ​​dynamically generated. An optimal cyclic prefix is ​​added to each OFDM symbol. Specifically, the receiver estimates the maximum multipath delay spread of the current channel using pilot symbols or training sequences. The Doppler frequency shift is fed back to the transmitter, which dynamically calculates and selects the optimal cyclic prefix based on a preset channel efficiency and guard interval trade-off model. The length of this optimal cyclic prefix is... And it must meet the following conditions:

[0045]

[0046] in, The system sampling rate; A protection margin is reserved for Doppler variations.

[0047] Specifically, in scenarios with slow channel changes, the length of the optimal cyclic prefix can be appropriately shortened to improve spectral efficiency. Conversely, in highly dynamic or multipath-prone scenarios, the length of the optimal cyclic prefix can be automatically extended to ensure orthogonality between symbols. When adding the optimal cyclic prefix, the length of the last element of each OFDM symbol is... The sampling points are copied to the symbol start position to form a transmitted signal with an adaptive guard interval. This adaptive cyclic prefix mechanism enables seamless switching between consecutive OFDM frames via control signaling, achieving real-time optimization of spectral efficiency and anti-interference performance.

[0048] S400: Transmits signals based on a multipath channel model;

[0049] In this step, firstly, the transmitting end needs to convert the parallel OFDM symbol stream with the optimal cyclic prefix added back into a serial signal stream so that it can be transmitted through a single antenna.

[0050] Secondly, to achieve channel modeling that more closely resembles the real-world environment, this application constructs a time-varying multipath channel model. This model can not only simulate static multipath effects but also support fading simulation under dynamic channel conditions. In the time domain, this channel model is represented as the superposition of impulse responses from multiple paths with different delays, attenuation coefficients, and phase offsets, allowing these parameters to vary over time, thus realistically reflecting the Doppler effect and time-varying channel characteristics in mobile communication environments.

[0051] Specifically, this embodiment adopts a multi-antenna system transmission model, which includes a time domain part and a frequency domain part. The time domain part is represented as follows:

[0052]

[0053] in, Indicates the time variable and delay variables Channel response under these conditions; Indicates the total number of distinguishable paths in the channel; Indicates the first The signal amplitude attenuates along the path and varies with time. change; Indicates the first Phase rotation term for the path; Indicates the first The phase of the path; Indicates the first The delay of the path; Represents the Dirac impulse function; Represents the imaginary unit;

[0054] The frequency domain portion is represented as follows:

[0055]

[0056] in, Indicates frequency and time variables The complex transmission function of the lower channel includes amplitude attenuation and phase rotation; Indicates the total number of distinguishable paths in the channel; Indicates the first Signal attenuation along the path, and its variation with time. change; Indicates the first Phase rotation term for the path; Indicates the first The phase of the path; Indicates the first The delay of the path; This represents a complex rotation caused by the path phase; Represents pi; It represents the imaginary unit.

[0057] To enhance simulation realism, this embodiment supports the integration of standard channel models (such as ITU-R M.1225, 3GPP TR38.901, etc.), which can simulate composite fading effects including path loss, shadowing fading, and fast fading. Under MIMO configuration, this model can also support different transmission modes such as spatial diversity, beamforming, or multi-stream transmission, providing a more complete simulation foundation for system capacity and reliability assessment.

[0058] S500: Receives the transmitted signal and removes the cyclic prefix portion to obtain a valid OFDM signal;

[0059] In this step, the receiver first performs high-precision frame synchronization on the received serial time-domain signal to accurately identify the start position of each OFDM symbol. This embodiment can employ synchronization methods based on training sequences or cyclic prefixes, such as using repeating preambles (e.g., Barker codes, ZC sequences) for autocorrelation detection, or using cross-correlation to match known pilots, thereby achieving robust symbol synchronization in low signal-to-noise ratio and multipath environments.

[0060] After frame synchronization is completed, carrier frequency offset estimation and compensation are further performed. Since transceiver crystal oscillator deviation and Doppler frequency shift exist in actual systems, carrier synchronization is crucial. This embodiment can employ a frequency offset estimation algorithm based on the periodicity of the cyclic prefix, or use pilot symbols for phase tracking, and correct the frequency offset of the received signal using a digital phase-locked loop or frequency domain interpolation method to restore the orthogonality between subcarriers.

[0061] Subsequently, based on the synchronized symbol timing information, the system accurately removes the cyclic prefix portion (of length ) from the front end of each OFDM symbol. Only the original length is retained. Valid time-domain samples.

[0062] By performing this step, this embodiment can eliminate the redundancy introduced by the cyclic prefix and provide an effective time-domain signal segment that is not affected by inter-symbol interference for subsequent frequency-domain transformation.

[0063] S600: Performs a fast Fourier transform on the valid OFDM signal to recover the frequency domain data and obtain the frequency domain received symbol sequence;

[0064] In this step, this embodiment performs an N-point Fast Fourier Transform (FFT) on each OFDM symbol in the effective OFDM signal after removing the cyclic prefix, and converts the time-domain sampling sequence back to the frequency domain to obtain a frequency-domain received symbol sequence Y[k] containing the effects of channel distortion and noise. This sequence contains the effects of channel distortion, noise, and possible residual synchronization errors.

[0065] Before the FFT transform, this embodiment can further introduce time-domain windowing processing. By applying smooth window functions such as raised cosine window and Hanning window, the OFDM symbol boundary is smoothly transitioned to reduce spectral leakage and adjacent channel interference. This is especially suitable for discontinuous spectrum allocation or asynchronous multi-user systems.

[0066] For scenarios with significant residual carrier frequency offset or phase noise, this embodiment supports joint processing of iterative FFT and phase compensation. Specifically, after the initial FFT, the system estimates and compensates for the common phase error and linear phase drift on each subcarrier based on pilot symbols or equalized data symbols. Subsequently, time-domain phase correction can be performed again and FFT can be executed a second time, thereby progressively improving the accuracy of frequency domain data and subcarrier orthogonality.

[0067] This embodiment can also combine frequency domain interpolation and noise suppression techniques to interpolate and smooth the discrete frequency domain response after the FFT output, and use the correlation between subcarriers to initially suppress noise, providing a cleaner frequency domain input for subsequent channel estimation and equalization.

[0068] Through the above-mentioned time-frequency joint enhancement processing, this step not only completes the basic mapping from the time domain to the frequency domain, but also provides the system with stronger robustness and higher signal recovery accuracy under non-ideal reception conditions, which is especially suitable for high-frequency communication, high-speed mobile or high phase noise scenarios.

[0069] S700: Perform channel estimation and equalization on the frequency domain received symbol sequence to obtain the frequency domain symbol estimate;

[0070] In this step, this embodiment first estimates the channel's frequency domain response H[k] based on the pilot symbols or training sequences inserted into the frequency domain received symbol sequence Y[k]. Specifically, at the transmitting end, the system periodically inserts known pilot symbols at specific subcarrier positions; the receiving end extracts the received values ​​at these positions. and compared with the original pilot values ​​stored locally. The system compares the results and uses a least-squares estimation algorithm to initially obtain the channel frequency response at the pilot position. Further, the system employs an interpolation method based on discrete Fourier transform or a low-pass filter interpolation technique to interpolate and extrapolate the channel response at the data subcarrier position using the channel estimate at the pilot position, thereby reconstructing a complete channel frequency response curve and providing accurate channel state information for subsequent equalization processing.

[0071] Furthermore, this embodiment supports multiple estimation strategies to adapt to different scenarios as shown below:

[0072] Pilot-assisted estimation: At fixed or adaptively distributed pilot locations, the initial channel response is obtained by least squares or linear minimum mean square error estimation, and the full-band channel response is obtained by DFT-based interpolation, spline interpolation or low-pass filtering methods.

[0073] Blind and semi-blind estimation: In scenarios with high spectral efficiency requirements, blind estimation can be performed using the statistical characteristics of the received signal or the decision feedback structure, or semi-blind joint estimation can be achieved by combining a small number of pilots to reduce pilot overhead.

[0074] Deep learning-based estimation: Construct convolutional neural network or recurrent neural network models, and use offline or online training to directly learn the channel response mapping function from the disturbed frequency domain signal, thereby improving the estimation accuracy and robustness under complex time-varying channels.

[0075] After obtaining the channel's frequency domain response H[k], this embodiment employs the intelligent equalization strategy described below to compensate the frequency domain received symbol sequence Y[k], in order to eliminate the amplitude attenuation, phase rotation, and possible inter-carrier interference introduced by the channel:

[0076] Classic equalization algorithms include zero-forcing equalization and minimum mean square error equalization, among which MMSE equalization can effectively balance noise amplification and interference suppression.

[0077] Enhanced equalization: For deeply fading subcarriers, a hybrid equalization structure combining frequency domain equalization and time domain filtering can be used; for MIMO systems, a space-frequency joint equalization algorithm is applied.

[0078] Iterative equalization and decoding: When the system uses channel coding, the equalizer and decoder can be iterated in a turbo manner, and the equalization and decoding performance can be gradually improved through external information exchange.

[0079] Finally, output the frequency domain symbol estimate. :

[0080]

[0081] By employing the aforementioned adaptive channel estimation and intelligent equalization mechanism, this embodiment achieves an optimized trade-off between spectral efficiency, computational complexity, and system robustness, thereby improving the system's recovery performance under frequency-selective fading and time-varying channels.

[0082] S800: Performs MQAM demodulation on the frequency domain symbol estimate and restores the parallel data stream to a serial bit stream, thus completing data recovery.

[0083] In this step, the frequency domain symbol estimate in this embodiment is... MQAM demodulation is performed. For higher-order modulation (such as 256QAM and 1024QAM), low-complexity approximation algorithms such as layered demodulation or spherical decoding are used to reduce the computational burden while ensuring performance.

[0084] After demodulation, each complex symbol is mapped back to its corresponding integer information, and then further converted into a binary bit sequence, which is then merged into a serial bit stream through parallel-to-serial conversion.

[0085] Based on this, this embodiment further integrates a complete post-receive processing chain, specifically including: first, deinterleaving the bit stream to disperse burst errors; then, using a modern channel decoder that supports soft input and soft output to decode encoded data such as LDPC, polar codes, or Turbo codes; subsequently, ensuring data integrity through cyclic redundancy check and retransmitting or discarding erroneous frames; and finally, performing decryption and decapsulation operations when necessary to restore the original user data.

[0086] In summary, this embodiment, by employing a closed-loop processing mechanism from demodulation to decoding and verification, enables reliable and efficient recovery of the received signal to the original information bits in high-reliability, high-data-rate scenarios such as 5G enhanced mobile broadband, vehicle-to-everything (V2X) and industrial IoT.

[0087] In another exemplary embodiment, this application also provides a communication device based on MQAM-OFDM modulation, such as... Figure 2 As shown, the device includes: a data generation and modulation unit 100, used to generate a random data source and perform MQAM modulation to generate a serial modulation signal; and a serial-to-parallel conversion and subcarrier mapping unit 200, used to convert the serial modulation signal... The system performs serial-to-parallel conversion and subcarrier mapping to obtain frequency-domain subcarrier data; a time-domain symbol generation unit 300 performs inverse fast Fourier transform on the frequency-domain subcarrier data to generate time-domain OFDM symbols and adds a cyclic prefix to obtain the transmitted signal; a signal transmission unit 400 transmits the transmitted signal based on a multipath channel model; a cyclic prefix removal unit 500 receives the transmitted signal and removes the cyclic prefix portion to obtain a valid OFDM signal; a frequency domain recovery unit 600 performs fast Fourier transform on the valid OFDM signal to recover the frequency-domain data and obtain a frequency-domain received symbol sequence; a channel estimation and equalization unit 700 performs channel estimation and equalization on the frequency-domain received symbol sequence to obtain a frequency-domain symbol estimate; and a data demodulation and recovery unit 800 performs MQAM demodulation on the frequency-domain symbol estimate and restores the parallel data stream to a serial bit stream to complete data recovery.

[0088] Based on the above embodiments, refer to Figure 3 The computer-readable storage medium of exemplary embodiments of this application will be described below. Please refer to [link / reference]. Figure 3 The computer-readable storage medium shown is an optical disc 40, on which a computer program (i.e., a program product) is stored. When the computer program is run by a processor, it implements the steps described in the above method implementation, such as generating a random data source and performing MQAM modulation to generate a serial modulation signal; performing serial-to-parallel conversion and subcarrier mapping on the serial modulation signal to obtain frequency domain subcarrier data; performing inverse fast Fourier transform on the frequency domain subcarrier data to generate time domain OFDM symbols and adding a cyclic prefix to obtain a transmitted signal; transmitting the transmitted signal based on a multipath channel model; receiving the transmitted signal and removing the cyclic prefix portion to obtain a valid OFDM signal; performing fast Fourier transform on the valid OFDM signal to recover the frequency domain data and obtain a frequency domain received symbol sequence; performing channel estimation and equalization on the frequency domain received symbol sequence to obtain a frequency domain symbol estimate; performing MQAM demodulation on the frequency domain symbol estimate and restoring the parallel data stream to a serial bit stream to complete data recovery.

[0089] It should be noted that the computer-readable storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other optical and magnetic storage media, which will not be described in detail here.

[0090] Based on the above embodiments, this application also provides an electronic device, which is described below with reference to... Figure 4 An electronic device for file downloading according to an exemplary embodiment of this application will be described.

[0091] Figure 4 A block diagram is shown of an exemplary electronic device 50 suitable for implementing embodiments of the present application. The electronic device 50 may be a computer system or a cloud server. Figure 4 The electronic device 50 shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0092] like Figure 4 As shown, the electronic device 50 includes, but is not limited to: one or more processors or processing units 501, system memory 502, and bus 503 connecting different system components (including system memory 502 and processing unit 501).

[0093] Electronic device 50 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by electronic device 50, including volatile and non-volatile media, removable and non-removable media.

[0094] System memory 502 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 5021 and / or cache memory 5022. Electronic device 50 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, ROM 5023 may be used to read and write non-removable, non-volatile magnetic media (…). Figure 4 (Not shown in the image, usually referred to as "hard drive"). Although not shown in... Figure 4 The diagram illustrates that a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) can be provided. In these cases, each drive can be connected to bus 503 via one or more data media interfaces. System memory 502 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of this application.

[0095] A program / utility 5025 having a set (at least one) of program modules 5024 may be stored, for example, in system memory 502, and such program modules 5024 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment. Program modules 5024 typically perform the functions and / or methods described in the embodiments of this application.

[0096] Electronic device 50 can also communicate with one or more external devices 504 (such as a keyboard, pointing device, display, etc.). This communication can be performed through input / output (I / O) interface 505. Furthermore, electronic device 50 can also communicate with one or more networks (such as local area networks (LANs), wide area networks (WANs), and / or public networks, such as the Internet) via network adapter 506. Figure 4 As shown, network adapter 506 communicates with other modules of electronic device 50 (such as processing unit 501) via bus 503. It should be understood that, although... Figure 4 As not shown, it can be used in conjunction with electronic device 50 with other hardware and / or software modules.

[0097] Processing unit 501 executes various functional applications and data processing by running programs stored in system memory 502. For example, it generates a random data source and performs MQAM modulation to generate a serial modulated signal; it performs serial-to-parallel conversion and subcarrier mapping on the serial modulated signal to obtain frequency-domain subcarrier data; it performs inverse fast Fourier transform on the frequency-domain subcarrier data to generate time-domain OFDM symbols and adds a cyclic prefix to obtain a transmitted signal; it transmits the transmitted signal based on a multipath channel model; it receives the transmitted signal and removes the cyclic prefix to obtain a valid OFDM signal; it performs fast Fourier transform on the valid OFDM signal to recover the frequency-domain data, obtaining a frequency-domain received symbol sequence; it performs channel estimation and equalization on the frequency-domain received symbol sequence to obtain a frequency-domain symbol estimate; it performs MQAM demodulation on the frequency-domain symbol estimate and restores the parallel data stream to a serial bit stream, completing data recovery. The specific implementation methods of each step will not be repeated here.

[0098] It should be noted that although several units / modules or sub-units / sub-modules of the file concurrent download device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided and embodied by multiple units / modules.

[0099] In the description of this application, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0100] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0101] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0102] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0103] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0104] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions that enable a computer device (which may be a personal computer, a cloud server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0105] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A communication method based on MQAM-OFDM modulation, characterized in that, The method includes: Generate a random data source and perform MQAM modulation to generate a serial modulated signal; The serial modulation signal is converted from serial to parallel and then mapped to subcarriers to obtain frequency domain subcarrier data. Performing an inverse fast Fourier transform on the frequency domain subcarrier data to generate time-domain OFDM symbols, and adding a cyclic prefix to obtain the transmitted signal, the process includes: Perform an inverse fast Fourier transform on each row of the frequency domain subcarrier data to generate a time-domain signal matrix; Estimate the maximum multipath delay-domain Doppler frequency shift of the current channel. Based on a preset channel efficiency and guard interval trade-off model, dynamically calculate and select the optimal cyclic prefix, which satisfies the following conditions: in, The system sampling rate; A protection margin is reserved for Doppler variations; The maximum multipath delay spread of the current channel; Add an optimal cyclic prefix to each OFDM symbol in the time-domain signal matrix. When adding the optimal cyclic prefix, set the length of the end of each OFDM symbol to be... The sampling points are copied to the symbol start position to form a transmitted signal with an adaptive guard interval; The transmitted signal is transmitted based on a multipath channel model; Receive the transmitted signal and remove the cyclic prefix portion to obtain a valid OFDM signal; Perform a Fast Fourier Transform on the valid OFDM signal to recover the frequency domain data and obtain the frequency domain received symbol sequence; Channel estimation and equalization are performed on the frequency domain received symbol sequence to obtain the frequency domain symbol estimate; The frequency domain symbol estimates are demodulated using MQAM, and the parallel data stream is restored to a serial bit stream, thus completing the data recovery.

2. The method according to claim 1, characterized in that, The process of generating a random data source and performing MQAM modulation to generate a serial modulation signal includes: Generate a random integer sequence; Each integer symbol in the random integer sequence is adjusted and mapped to generate a serial modulated signal.

3. The method according to claim 1, characterized in that, The step of performing serial-to-parallel conversion and subcarrier mapping on the serial modulated signal to obtain frequency domain subcarrier data includes: Convert the serial modulated signal into a parallel data matrix; Each row in the parallel data matrix is ​​mapped to a subcarrier to obtain frequency domain subcarrier data.

4. The method according to claim 1, characterized in that, The multipath channel model includes a time domain part and a frequency domain part, wherein, The time domain part is represented as follows: in, Indicates the time variable and delay variables Channel response under these conditions; Indicates the total number of distinguishable paths in the channel; Indicates the first The signal amplitude attenuates along the path and varies with time. change; Indicates the first Phase rotation term for the path; Indicates the first The phase of the path; Indicates the first The delay of the path; Represents the Dirac impulse function; Represents the imaginary unit; The frequency domain portion is represented as follows: in, Indicates frequency and time variables The complex transmission function of the lower channel includes amplitude attenuation and phase rotation; Indicates the total number of distinguishable paths in the channel; Indicates the first Signal attenuation along the path, and its variation with time. change; Indicates the first Phase rotation term for the path; Indicates the first The phase of the path; Indicates the first The delay of the path; This represents a complex rotation caused by the path phase; Represents pi; It represents the imaginary unit.

5. The method according to claim 1, characterized in that, The process of receiving and transmitting the signal and removing the cyclic prefix portion to obtain a valid OFDM signal includes: Perform frame synchronization on the transmitted signals; Offset estimation and compensation are performed on the transmitted signal after frame synchronization; Remove the cyclic prefix portion from the transmitted signal after offset estimation and compensation, and retain the valid time-domain samples.

6. The method according to claim 1, characterized in that, The process of performing channel estimation and equalization on the frequency domain received symbol sequence to obtain frequency domain symbol estimates includes: Estimate the channel frequency domain response based on pilot symbols or training sequences; The channel frequency domain response is compensated based on an intelligent equalization strategy to obtain frequency domain symbol estimates.

7. A communication apparatus for implementing the communication method based on MQAM-OFDM modulation as described in claim 1, characterized in that, The device includes: The data generation and modulation unit is used to generate a random data source and perform MQAM modulation to generate a serial modulation signal. The serial-to-parallel conversion and subcarrier mapping unit is used to convert the serial modulated signal into a serial-to-parallel signal and perform subcarrier mapping to obtain frequency domain subcarrier data. A time-domain symbol generation unit is used to perform inverse fast Fourier transform on frequency-domain subcarrier data to generate time-domain OFDM symbols and add a cyclic prefix to obtain a transmission signal. The process of performing inverse fast Fourier transform on frequency-domain subcarrier data to generate time-domain OFDM symbols and adding a cyclic prefix to obtain a transmission signal includes: Perform an inverse fast Fourier transform on each row of the frequency domain subcarrier data to generate a time-domain signal matrix; Estimate the maximum multipath delay-domain Doppler frequency shift of the current channel. Based on a preset channel efficiency and guard interval trade-off model, dynamically calculate and select the optimal cyclic prefix, which satisfies the following conditions: in, The system sampling rate; A protection margin is reserved for Doppler variations; The maximum multipath delay spread of the current channel; Add an optimal cyclic prefix to each OFDM symbol in the time-domain signal matrix. When adding the optimal cyclic prefix, set the length of the end of each OFDM symbol to be... The sampling points are copied to the symbol start position to form a transmitted signal with an adaptive guard interval; The signal transmission unit is used to transmit the signal based on the multipath channel model; The cyclic prefix removal unit is used to receive the transmitted signal and remove the cyclic prefix portion therein to obtain a valid OFDM signal; The frequency domain recovery unit is used to perform a fast Fourier transform on the valid OFDM signal to recover the frequency domain data and obtain the frequency domain received symbol sequence; The channel estimation and equalization unit is used to perform channel estimation and equalization on the frequency domain received symbol sequence to obtain the frequency domain symbol estimate value. The data demodulation and recovery unit is used to perform MQAM demodulation on the frequency domain symbol estimate and restore the parallel data stream to a serial bit stream, thus completing the data recovery.

8. A storage medium, characterized in that, It includes instructions that, when executed on a computer, cause the computer to perform the method of any one of claims 1 to 6.

9. An electronic device, characterized in that, The electronic device includes: Memory, processor, and computer programs stored in memory and executable on the processor, wherein, When the processor executes the program, it implements the method as described in any one of claims 1 to 6.

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