Methods, apparatuses, and systems for implementing OTFS modulation and demodulation

Abstract

This invention provides a method, device, and system for implementing OTFS modulation and demodulation. At the transmitter, a block interleaver is used to concatenate Polar codes and LDPC codes. After high-order modulation of the concatenated Polar-LDPC codes, ISFFT is used for preprocessing to implement OTFS modulation based on OFDM. At the receiver, SFFT post-processing is used to implement OTFS demodulation based on OFDM. This technical solution improves traditional OFDM modulation systems using single LDPC or Polar codes, easily upgrading OFDM systems to OTFS systems. This improves the communication system's robustness against continuous errors, enhances its performance, and makes it more suitable for high-frequency, high-mobility scenarios in future communications, such as those in 6G.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a method, device and storage medium for sending and receiving information on a communication channel, and a method, device and system for implementing OTFS modulation and demodulation. Background Art

[0002] With increasing user demand for low-latency, high-reliability communications, channel coding has become an indispensable practical solution. Although Polar codes have been shown to theoretically reach the Shannon limit for symmetric capacity in binary discrete memoryless channels and offer lower computational complexity in encoding and decoding than other coding schemes, their decoding performance for short and medium codewords falls short of that of LDPC codes. While LDPC codes offer a relatively low bit error rate (BER) in channels with low signal-to-noise ratios (SNRs), they can experience error flooring in channels with high SNRs.

[0003] In addition, as a widely used multi-carrier modulation technology, OFDM modulation technology cannot meet the needs of reliable communication under dual-selective fading channels in the high-mobility scenarios of 6G and high-frequency communication scenarios such as millimeter waves and terahertz. Summary of the Invention

[0004] Embodiments of the present invention provide a method, device, and storage medium for sending and receiving information on a communication channel, and a method, device, and system for implementing OTFS modulation and demodulation, so as to improve the OFDM modulation system under traditional single LDPC or Polar coding, enhance the performance of the communication system, and make the communication system more suitable for high-frequency and high-mobility scenarios in future communications such as 6G communications.

[0005] To achieve the above object, a method for sending information on a communication channel is provided, comprising:

[0006] The information sequence generated by the signal source is input into the Polar code encoder for outer code encoding, the information after outer code encoding is input into the block interleaver for interleaving, and then the interleaved information is input into the LDPC encoder for inner code encoding and output;

[0007] The information output by the LDPC encoder is subjected to high-order modulation, and the modulation symbols output after the high-order modulation are subjected to OTFS preprocessing. The OTFS preprocessing includes: placing the modulation symbols in the delay-Doppler domain, and transforming the information symbols obtained in the delay-Doppler domain into the time-frequency domain through the inverse symplectic Fourier transform (ISFFT).

[0008] The time-frequency domain information obtained by OTFS preprocessing is converted into a time-domain signal through Heisenberg transform and filter function;

[0009] The time domain signal is sent through a tapped delay line channel model.

[0010] Preferably, the method, wherein the steps of inputting the information sequence into a Polar code encoder for outer code encoding, inputting the outer code-encoded information into a block interleaver for interleaving, and then inputting the interleaved information into an LDPC encoder for inner code encoding, include:

[0011] After the information sequence of length k is input into the Polar encoder for encoding, a Polar code word of length N is obtained;

[0012] Block interleaving is performed on Polar code codewords of length N, where the unit of the block interleaving length is less than N and is divisible by N; wherein the first t bits of each Polar code codeword constitute the first codeword block of the LDPC code, and the next t bits of each Polar code codeword constitute the second codeword block of the LDPC code, where the number t is predetermined;

[0013] The block-interleaved code of length N is used as the signal source for LDPC encoding, where N is equal to k.

[0014] Preferably, in the method, the step of generating a time domain signal from the transformed time-frequency domain information through Heisenberg transform and filtering function comprises:

[0015] A pilot is inserted into the time-frequency domain information obtained by the transformation, and the information obtained after the pilot insertion is input into the OFDM modulation module.

[0016] In another aspect, a method of receiving information on a communication channel is provided, comprising:

[0017] Perform OFDM demodulation on the received information;

[0018] Perform channel estimation and channel equalization on the information after OFDM demodulation;

[0019] Performing OTFS post-processing on the information after channel equalization, OTFS post-processing includes symplectic transform;

[0020] The information processed by OTFS is demodulated by high-order modulation to obtain bit information;

[0021] The bit information is decoded, and the decoding process includes decoding and deinterleaving the inner code LDPC code and decoding the outer code Polar code.

[0022] Preferably, in the method, the channel estimation is pilot channel estimation, and the channel equalization is MMSE channel equalization using fast Fourier transform FFT; the OTFS post-processing also includes: removing the pilot before the symplectic transform and window function processing after the symplectic transform.

[0023] Preferably, in the method, the inner code LDPC is decoded using a BP decoding algorithm, and the outer code Polar code is decoded using an SC decoding algorithm.

[0024] In another aspect, a communication system is provided, comprising:

[0025] A transmitting end device, comprising: a first memory and a first processor, the first memory storing at least one program, the at least one program being executed by the first processor to implement any of the above methods for sending information on a communication channel;

[0026] The receiving end device includes: a second memory and a second processor, the second memory stores at least one program, and the at least one program is executed by the second processor to implement any of the above methods for receiving information on a communication channel.

[0027] On the other hand, a computer-readable storage medium is provided, wherein the storage medium stores at least one program, and the at least one program is executed by a processor to implement any of the methods described above.

[0028] In another aspect, a method for implementing OTFS modulation and demodulation is provided, comprising:

[0029] The modulation process includes:

[0030] OTFS transformation steps: symbol modulate the received bits, perform inverse sigmoid Fourier transform on the modulated information, and perform send windowing. The received bits are information obtained by encoding the source with a Polar-LDPC concatenated code. The Polar-LDPC concatenated code is a concatenated code that uses a Polar code as the outer code and an LDPC code as the inner code, with a block interleaver between the Polar code and the LDPC code.

[0031] Heisenberg transform steps: insert a pilot into the information after OTFS transform, and perform OFDM modulation on the information after the pilot insertion. The OFDM modulated signal is sent through the channel;

[0032] The demodulation process includes:

[0033] Weige transformation step: performing OFDM demodulation processing and pilot removal processing on the signal received through the channel;

[0034] Pilot channel estimation and MMSE channel equalization steps using Fast Fourier Transform;

[0035] OTFS inverse transformation step: the information after channel equalization is subjected to symplectic transformation and receiving window processing, and then symbol demodulation is performed.

[0036] On the other hand, a device for implementing OTFS modulation and demodulation is provided, including: a memory and a processor, the memory storing at least one program, and the at least one program being executed by the processor to implement the method for implementing OTFS modulation and demodulation as described above.

[0037] The technical solution of the embodiment of the present invention provides a more ideal method for solving continuous errors by interleaving the codeword blocks encoded by Polar codes as the source data of LDPC coding, thereby improving the performance and versatility of concatenated codes at a lower complexity cost. In addition, the technical solution of the embodiment of the present invention can realize OTFS modulation based on OFDM by using OTFS preprocessing before OFDM modulation. The structure is clear and simple, and it makes it easier to upgrade the OFDM module to OTFS in the traditional LTE system. It only needs to connect the corresponding OTFS preprocessing modules in series, which improves compatibility and reduces system reconstruction costs.

[0038] In a further embodiment of the present invention, the system reliability can be made stronger by the simultaneous existence of channel estimation and equalization modules; moreover, since the complexity of the system increases after the coding cascade, the complexity of matrix processing is reduced by using fast Fourier transform in the cascade code decoding process and the channel equalization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a block diagram of the overall design of a communication system that implements OTFS modulation in one embodiment of the present invention;

[0040] Figure 2 Schematic diagram of the block interleaving process used to construct Polar-LDPC concatenated codes in one embodiment of the present invention;

[0041] Figure 3 This is a flowchart of implementing OTFS modulation and demodulation processing in one embodiment of the present invention;

[0042] Figure 4 It is a visualization diagram of the symbols in the delay-Doppler grid mapped to the time-frequency domain grid through ISFFT;

[0043] Figure 5 This is the system simulation result diagram when the code length and code rate are selected. DETAILED DESCRIPTION

[0044] To further illustrate various embodiments, the present invention is provided with accompanying drawings. These drawings form part of the present disclosure and are primarily used to illustrate the embodiments and, in conjunction with the relevant description in the specification, to explain the operating principles of the embodiments. By referring to these drawings, one of ordinary skill in the art will understand other possible embodiments and the advantages of the present invention. The components in the figures are not drawn to scale, and similar reference numerals are generally used to represent similar components.

[0045] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0046] A method for sending information on a communication channel according to an embodiment of the present invention includes:

[0047] S1, inputting an information sequence generated by a signal source into a Polar code encoder for outer code encoding, inputting the outer code-encoded information into a block interleaver for interleaving, and then inputting the interleaved information into an LDPC encoder for inner code encoding and outputting. Preferably, the information sequence generated by the signal source is a random sequence. Preferably, in LDPC encoding, the original check matrix is converted into a lower triangular matrix using Gaussian elimination, and then directly encoded.

[0048] S2, performing high-order modulation on the information output by the LDPC encoder, and performing OTFS preprocessing on the modulation symbols output after the high-order modulation. The OTFS preprocessing includes: placing the modulation symbols in the delay-Doppler domain, and transforming the obtained information symbols in the delay-Doppler domain into the time-frequency domain through an inverse sigmoid Fourier transform (ISFFT). In a specific implementation, placing the modulation symbols in the delay-Doppler domain means placing the modulation symbols in a delay-Doppler domain grid.

[0049] S3, the time-frequency domain information obtained by OTFS preprocessing is transformed by Heisenberg and the filter function g t (t) generating a time domain signal; preferably, in this step, the time-frequency domain information obtained by the transformation can be inserted into a pilot signal, and the information obtained after the pilot signal insertion can be input into an OFDM modulation module;

[0050] S4, sending the time domain signal through a tapped delay line, i.e., a TDL channel model.

[0051] Corresponding to the above-mentioned method for sending information, a method for receiving information on a communication channel according to an embodiment of the present invention includes:

[0052] S5, performing OFDM demodulation on the received information;

[0053] S6, performing channel estimation and channel equalization on the OFDM demodulated information; preferably, at the receiving end, considering the instability of high-frequency and high-mobility channels, pilot channel estimation and Fourier transform-assisted MMSE channel equalization processing are performed;

[0054] S7, performing OTFS post-processing on the information after channel equalization, where the OTFS post-processing includes symplectic transform (SFFT); preferably, the OTFS post-processing also includes receiving window function processing;

[0055] S8, demodulating the information after OTFS post-processing through high-order modulation to obtain bit information;

[0056] S9, decoding the bit information, where the decoding process includes decoding and deinterleaving the inner code LDPC code and decoding the outer code Polar code.

[0057] The embodiment of the present invention performs a serial concatenation design of Polar codes and LDPC codes, and adds an interleaver to the concatenated coding to improve the resistance to burst errors. In addition, the embodiment of the present invention implements orthogonal time-frequency-space (OTFS) modulation on the basis of OFDM based on the concatenated coding of Polar codes and LDPC codes. OTFS modulation can utilize the diversity of time and frequency to convert the time-varying fading channel experienced by modulated signals such as OFDM into a time-independent channel, splicing its full diversity potential, low peak-to-average ratio, good robustness, and channel sparsity, becoming a waveform technology with development potential in future mobile communications.

[0058] The method for sending and receiving information in the embodiment of the present invention uses OTFS modulation with concatenated coding; in one embodiment, the OTFS modulation module is constructed based on the OFDM modulation module. Figure 1 FIG1 is a block diagram of the overall design principle of a communication system that uses the OTFS modulation method with concatenated coding for communication in an embodiment of the present invention. Figure 1 , the communication system includes a transmitting end and a receiving end; wherein the transmitting end includes an OTFS transmitting end, and the receiving end includes an OTFS receiving end. wherein the source information is as follows Figure 1The u in the signal is input to the OTFS transmitter for OTFS modulation. Preferably, u is a random sequence generated by the signal source and follows a Bernoulli distribution. The modulated information x(t) is converted to y(t) through the TDL channel. The modulated signal passes through a TDL channel model to simulate the multipath propagation of 0.5 GHz to 100 GHz electromagnetic waves in free space. The OTFS receiver receives the information y(t) from the TDL channel and then performs corresponding demodulation and decoding, including: demodulating the channel output symbol probabilities into bit LLRs, iteratively decoding the LDPC decoding part, deinterleaving the LLR iterative decoding results, and then decoding the Polar code using a Polar code decoding algorithm to obtain the decoded signal u'.

[0059] Figure 1 In the OTFS transmission end, there are two parts, one is the channel coding and decoding part that realizes the Polar-LDPC concatenated code, and the other is the high-order modulation part. q The QAM modulation and demodulation unit, OTFS pre-processing unit, OFDM modulation module transmission unit, and channel unit. In this example, the channel unit is the TDL channel. Specifically, the information u is encoded by the Polar code outer code and sent to the block interleaver, and then encoded by the LDPC inner code; through high-order modulation 2 q The QAM unit converts bits into symbols, each containing q bits. These symbols serve as the initial conditions for the ISFFT transform. The OTFS preprocessing unit includes the ISFFT transform and some window functions to trim the data. The time-frequency domain signal after the ISFFT transform passes through the traditional OFDM modulation module to obtain the time domain signal, which is then transmitted through the TDL channel model. The TDL channel model focuses on delay-Doppler parameters to simulate the multipath propagation of electromagnetic waves in space.

[0060] At the receiving end, the signal y(t) passing through the channel is inversely processed, starting with demodulation at the OFDM receiving end. To compensate for channel losses, channel estimation and channel equalization modules are added. Channel estimation is achieved by inserting pilots in the OTFS preprocessing unit, i.e., pilot-assisted channel estimation is adopted, while channel equalization adopts minimum mean square error (MMSE) channel equalization assisted by fast Fourier transform (FFT). The processing of the OTFS post-processing unit includes: pilot removal, symplectic transform (SFFT), and window function processing. After processing by the OTFS post-processing unit, the information is demodulated by high-order QAM modulation to obtain bit information. Finally, it is sent to the decoding unit for processing. The decoding steps include: decoding of the inner code LDPC using the BP decoding algorithm, deinterleaving, and decoding of the outer code Polar code using the SC decoding algorithm. In the decoding process, the part that processes complex matrices also uses fast Fourier transform (FFT) to simplify the operation steps computationally.

[0061] In a specific implementation, constructing a concatenated code with a Polar code as the outer code, an LDPC code as the inner code, and a block interleaver in between includes the following steps:

[0062] After a signal source of length k is input at the signal source input end, it is encoded by the Polar encoder to obtain a Polar codeword of length N;

[0063] Block interleaving is performed on the resulting codeword of length N. The unit length of the block interleaving must be less than the length N, and N must be divisible by an integer. The first t bits of each Polar code become the first codeword block of the LDPC code, and the next t bits of the Polar code become the second codeword block of the LDPC code. t is a preset number. The composition of other codeword blocks of the LDPC code is deduced in this way.

[0064] The code with a length of N after block interleaving is used as the information source for LDPC encoding. At this time, N is equal to k, and the encoded information code length is m.

[0065] Figure 2 This is a diagram of the block interleaving process. The purpose of interleaving is to regularly disrupt the inner and outer code information of the cascade code, converting continuous errors into random errors, which is beneficial to error correction of code words. Figure 2 The individual matrix blocks of each part are recombined to strike a good balance between interleaving complexity and performance, thereby effectively improving the performance of the system without significantly increasing the complexity.

[0066] Figure 3 This is a flowchart of the OTFS modulation and demodulation process based on OFDM. Figure 3 The OTFS modulation and demodulation processing includes OTFS transform and Heisenberg transform at the OTFS transmitter and Winger transform, channel estimation and channel equalization, and OTFS inverse transform at the OTFS receiver.

[0067] Specifically, the OTFS modulation and demodulation process includes the following steps:

[0068] Symbol modulation is discrete symbols: high-order data modulation symbols are placed in the delay-Doppler domain;

[0069] Time-frequency domain conversion: At the transmitter, the information symbol x[k,l] in the delay-Doppler domain is transformed into X[n,m] in the time-frequency domain through ISFFT and shaping filter;

[0070] Heisenberg transform: by converting the time-frequency domain X[n,m] into a common time-domain signal, namely the time-varying signal s(t);

[0071] Shaping filter: through the transmission pulse shaping filter gtx (t) to achieve;

[0072] Transmitted through a channel: The signal x(t) is transmitted through a linear time-varying channel h(τ,v) with time delay and Doppler variations.

[0073] Vig transform: traditional time-frequency demodulation, pay attention to the acquisition and processing of mutual ambiguity functions;

[0074] Post-processing: including receiving window function W rx [n,m] and SFFT.

[0075] Among them, in the channel estimation and channel equalization part, in the process of using OFDM for data transmission, non-zero pilot symbols and zero protection symbols together constitute the OFDM symbol. At the receiving end, the symbol pilot information will be collected and used as a basis for channel estimation. The OTFS system based on OFDM modulation adopts the time-frequency domain pilot-assisted channel estimation method, and uses the correlation and sparsity of the time-varying channel to jointly estimate its corresponding extended model, thereby improving the spectrum efficiency and ensuring the accuracy of the time-varying channel estimation. In the time-frequency domain channel estimation, for the subcarriers of the OTFS frame, a pilot insertion scheme is adopted. In the equalization part, based on the traditional MMSE equalization, the characteristics of the OTFS dual-cycle channel are utilized, and the fast Fourier transform, namely FFT, is used to optimize the complex calculations such as matrix inversion, which can reduce the complexity, such as the complexity from O(M 3 N 3 )→O(NMlog2(NM)).

[0076] Figure 4 This is a visualization of the symbols in the delay-Doppler grid mapped to the time-frequency domain grid through ISFFT. Figure 5 The following is a diagram showing the system simulation results when the Polar code length and code rate are selected. In one example, the Polar code length is 1024 and the code rate is 0.5. The simulation results compare the performance of Polar codes before and after concatenation, and of OTFS and OFDM systems. Figure 5 The performance gain comparisons shown for concatenated codes and single coding, and for the OTFS system and traditional OFDM systems, show that the combination of concatenated codes and OTFS increases communication reliability, making it suitable for future communication system design. Furthermore, by optimizing complexity using FFT in the decoding and equalization stages, the complexity of such system designs can be reduced.

[0077] An embodiment of the present invention also provides a communication system, comprising: a sending end device, comprising: a first memory and a first processor, the first memory storing at least one program, the at least one program being executed by the first processor to implement any of the methods for sending information on a communication channel as described above; a receiving end device, comprising: a second memory and a second processor, the second memory storing at least one program, the at least one program being executed by the second processor to implement any of the methods for receiving information on a communication channel as described above.

[0078] Furthermore, as an executable solution, the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the computer unit and connects various parts of the entire computer unit using various interfaces and lines.

[0079] The memory can be used to store the computer programs and / or modules, and the processor implements the various functions of the computer unit by running or executing the computer programs and / or modules stored in the memory, and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system and at least one application required for a function; the data storage area can store data created based on the use of the mobile phone, etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0080] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method in the embodiment of the present invention are implemented.

[0081] If the module / unit integrated in the computer unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of the above-mentioned various method embodiments. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM) and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0082] Although the present invention has been particularly shown and described in conjunction with preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims, and all such changes are within the scope of protection of the present invention.

Claims

1. A method for sending information on a communication channel, characterized in that include: The information sequence generated by the signal source is input into the Polar code encoder for outer code encoding, the information after outer code encoding is input into the block interleaver for interleaving, and then the interleaved information is input into the LDPC encoder for inner code encoding and output; The information output by the LDPC encoder is subjected to high-order modulation, and the modulation symbols output after the high-order modulation are subjected to OTFS preprocessing, wherein the OTFS preprocessing includes: placing the modulation symbols in the delay-Doppler domain, and converting the obtained information symbols in the delay-Doppler domain to the time-frequency domain through inverse sigmoid Fourier transform; The time-frequency domain information obtained by OTFS preprocessing is converted into a time-domain signal through Heisenberg transform and filter function; Sending the time domain signal through a tapped delay line channel model; The steps of inputting the information sequence into a Polar code encoder for outer code encoding, inputting the information after outer code encoding into a block interleaver for interleaving, and then inputting the interleaved information into an LDPC encoder for inner code encoding include: After the information sequence of length k is input into the Polar encoder for encoding, a Polar code word of length N is obtained; performing block interleaving on the Polar code codewords of length N, wherein a length unit of the block interleaving is less than N and is divisible by N; wherein the first t bits of each Polar code codeword constitute a first codeword block of the LDPC code, and the next t bits of each Polar code codeword constitute a second codeword block of the LDPC code, wherein the number t is predetermined; The block-interleaved code of length N is used as the signal source for LDPC encoding, where N is equal to k.

2. The method according to claim 1, characterized in that The steps of generating a time domain signal from the transformed time-frequency domain information through Heisenberg transform and filter function include: A pilot is inserted into the time-frequency domain information obtained by the transformation, and the information obtained after the pilot insertion is input into the OFDM modulation module.

3. A method for receiving information on a communication channel, characterized in that The received information is information sent using the method for sending information on a communication channel according to claim 1 or 2, the method comprising: Perform OFDM demodulation on the received information; Perform channel estimation and channel equalization on the information after OFDM demodulation; Performing OTFS post-processing on the information after channel equalization, wherein the OTFS post-processing includes symplectic transformation; Demodulating the information after the OTFS post-processing by high-order modulation to obtain bit information; The bit information is decoded, and the decoding process includes decoding and deinterleaving the inner code LDPC code and decoding the outer code Polar code.

4. The method according to claim 3, characterized in that The channel estimation is pilot channel estimation, and the channel equalization is MMSE channel equalization using fast Fourier transform; The OTFS post-processing further includes: removing pilots before the symplectic transform and window function processing after the symplectic transform.

5. The method according to claim 3, characterized in that The BP decoding algorithm is used to decode the inner code LDPC, and the SC decoding algorithm is used to decode the outer code Polar code.

6. A communication system, characterized in that: include: A transmitting end device, comprising: a first memory and a first processor, wherein the first memory stores at least one program, and the at least one program is executed by the first processor to implement the method according to any one of claims 1 to 2; A receiving end device includes: a second memory and a second processor, wherein the second memory stores at least one program, and the at least one program is executed by the second processor to implement the method according to any one of claims 3 to 5.

7. A computer-readable storage medium, characterized in that The storage medium stores at least one program, and the at least one program is executed by a processor to implement the method according to any one of claims 1 to 5.

8. A method for implementing OTFS modulation and demodulation, characterized in that: include: The modulation process includes: OTFS transformation step: performing symbol modulation on the received bits, and performing inverse sigmoid Fourier transform and send window processing on the modulated information. The received bits are information obtained by encoding the source with a Polar-LDPC concatenated code. The Polar-LDPC concatenated code is a concatenated code composed of a Polar code as an outer code, an LDPC code as an inner code, and a block interleaver between the Polar code and the LDPC code. The Polar-LDPC concatenated code is obtained by the following steps: After the information sequence of length k is input into the Polar encoder for encoding, a Polar code word of length N is obtained; performing block interleaving on the Polar code codewords of length N, wherein a length unit of the block interleaving is less than N and is divisible by N; wherein the first t bits of each Polar code codeword constitute a first codeword block of the LDPC code, and the next t bits of each Polar code codeword constitute a second codeword block of the LDPC code, wherein the number t is predetermined; The block-interleaved code of length N is used as the source for LDPC encoding, where N is equal to k; Heisenberg transform steps: insert a pilot into the information after OTFS transform, and perform OFDM modulation on the information after the pilot insertion. The OFDM modulated signal is sent through the channel; The demodulation process includes: Vige transformation step: performing OFDM demodulation processing and pilot removal processing on the signal modulated by the modulation process received through the channel; Pilot channel estimation and MMSE channel equalization steps using Fast Fourier Transform; OTFS inverse transformation step: the information after channel equalization is subjected to symplectic transformation and receiving window processing, and then symbol demodulation is performed.

9. A device for implementing OTFS modulation and demodulation, characterized in that: include: A memory and a processor, wherein the memory stores at least one program, and the at least one program is executed by the processor to implement the method according to claim 8.

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