Interference self-cancellation orthogonal time frequency space method in high mobility extended coverage network

Abstract

The application discloses a kind of interference self-elimination orthogonal time-frequency-space methods in high mobile extended coverage network, comprising the following steps: 1) transmitting end sequentially carries out constellation mapping, repeat precoding, inverse sine Fourier transform, time-frequency domain precoding and Heisenberg transformation to the data to be sent, after adding cyclic prefix, send out again;2) receiving end sequentially carries out to remove cyclic prefix, Wigner transformation, opposite gain combination, time-frequency domain point division equalization, frequency domain direction interval inserts 0 and sine Fourier transform to received signal r (t), obtains time delay Doppler symbol X DD , complete interference self-elimination orthogonal time-frequency-space in high mobile extended coverage network, this method can improve bit error rate performance, reduce detection complexity.

Description

Technical Field

[0001] This invention belongs to the field of communication technology and relates to an orthogonal time-frequency space method for interference self-cancellation in high mobility extended coverage networks. Background Technology

[0002] Next-generation communication technologies need to support highly mobile communication scenarios (such as drone communication and satellite communication), but this introduces high Doppler effects. Orthogonal Frequency Division Multiplexing (OFDM) modulation technology is widely used in fourth-generation and fifth-generation communication technologies, and it has significant advantages in improving spectral efficiency, resisting multipath delay spread, and frequency-selective channels. However, inter-carrier interference caused by Doppler spread in time-varying channels severely impairs the orthogonality of subcarriers in OFDM technology, leading to a significant performance degradation. Orthogonal Time Frequency Space (OTFS) modulation technology uses the delayed Doppler domain to modulate information symbols, achieving complete diversity in both the time and frequency domains, making it superior to OFDM schemes in time-varying channels. To achieve a low-complexity detection scheme for orthogonal time-frequency control, researchers have developed various signal detection methods that utilize the characteristics of time-delay Doppler channels. These methods focus on using low-complexity methods to approximate the interference term, aiming to achieve a balance between detection performance and computational complexity. However, relatively speaking, the bit error rate performance is poor and the detection complexity is high. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an interference self-cancellation orthogonal time-frequency space method in high mobility extended coverage networks. This method can improve bit error rate performance and reduce detection complexity.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides an orthogonal time-frequency-space method for interference self-cancellation in high-mobility extended coverage networks, comprising the following steps:

[0006] 1) The transmitting end performs constellation mapping, repetitive precoding, inverse symmetric Fourier transform, time-frequency domain precoding, and Heisenberg transform on the data to be transmitted in sequence, and then adds a cyclic prefix before sending it out;

[0007] 2) The receiver sequentially performs the following operations on the received signal r(t): removal of the cyclic prefix, Wigner transform, inverse equal gain combining, time-frequency domain point division equalization, frequency domain directional zero-interpolation, and symmetric Fourier transform, to obtain the time-delay Doppler symbol X. DD To achieve interference self-cancellation orthogonal time-frequency space in high mobility extended coverage networks.

[0008] The specific operation of step 1) is as follows:

[0009] 11) At the transmitting end, perform constellation mapping on the data to be transmitted to obtain MN / 2 QAM symbols, and construct an (M / 2)×N symbol matrix B based on the MN / 2 QAM symbols. DD Where M is the number of subcarriers and N is the number of time slots;

[0010] 12) For the symbol matrix B DD Perform repeated precoding to obtain the time-delayed Doppler domain symbol X. DD ;

[0011] 13) For the time-delay Doppler domain symbol X DD Performing an inverse symplectic Fourier transform yields the time-frequency domain symbols separated by zero symbols in the frequency domain direction.

[0012] 14) Regarding the time-frequency domain symbols Time-frequency domain precoding with adjacent carrier inverse padding is performed to obtain the precoding result X. TF ;

[0013] 15) For the precoding result X TF Perform a Heisenberg transform and add a cyclic prefix to obtain the time-domain transmit symbol s(t).

[0014] The precoding result X in step 14) TF for:

[0015]

[0016] Step 2) is as follows:

[0017] 21) The receiver removes the cyclic prefix from the received signal r(t) and then performs a Wigner transform to obtain the time-frequency domain symbol.

[0018] 22) For adjacent time-frequency domain symbols within the same time slot in the time-frequency domain Perform inverse equal-gain combining to obtain the combined result Y. TF ;

[0019] 23) Using equivalent time-frequency domain channel coefficients for Y TF Perform time-frequency domain point division equalization to obtain the equalized time-frequency domain symbol Y. TF ;

[0020] 24) Equalize the time-frequency domain symbol R along the frequency domain direction. TF Insert 0s at intervals to obtain Again Perform a symmetric Fourier transform to obtain the time-delayed Doppler domain symbol.

[0021] The merged result Y in step 22) TF ;

[0022]

[0023] Step 23) Equalized time-frequency domain symbol R TF ;

[0024]

[0025] in, is the equivalent coefficient in the time-frequency domain, and l represents the index of the frequency direction.

[0026] The time-frequency domain equivalent coefficients For (H) TF [l,k]+H TF [l+1, k]).

[0027] The time-delayed Doppler symbol X DD for:

[0028]

[0029] The present invention has the following beneficial effects:

[0030] The interference self-cancellation orthogonal time-frequency space method in high-mobility extended coverage networks described in this invention, in specific operation, effectively eliminates inter-carrier interference and inter-symbol interference by repeatedly precoding the time-delay-Doppler domain symbols, filling the time-frequency domain symbols with negative symbols along the frequency domain direction, and adding cyclic prefixes. Finally, the transceiver design is completed through frequency domain point division equalization with linear complexity, effectively improving bit error rate performance and reducing system design complexity. Attached Figure Description

[0031] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a flowchart of the transmitter of the present invention;

[0033] Figure 2 This is a flowchart of the receiver of the present invention;

[0034] Figure 3 This is a performance comparison chart of the present invention and an uncoded orthogonal time-frequency air conditioning system under different detection methods. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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 scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] The present invention will now be described in further detail with reference to the accompanying drawings:

[0038] refer to Figure 1 and Figure 2 The interference self-cancellation orthogonal time-frequency-space method in a high-mobility extended coverage network described in this invention includes the following steps:

[0039] 1) At the transmitting end

[0040] 11) Perform constellation mapping on the data to be transmitted to obtain MN / 2 QAM symbols, and construct an (M / 2)×N symbol matrix B based on the MN / 2 QAM symbols. DD Where M is the number of subcarriers and N is the number of time slots;

[0041] 12) For the symbol matrix B DD Perform repeated precoding to obtain the time-delayed Doppler domain symbol X. DD The time-delay Doppler domain symbol X DD It is an M×N matrix.

[0042] 13) For the time-delay Doppler domain symbol X DD Performing an inverse symplectic Fourier transform yields the time-frequency domain symbols separated by zero symbols in the frequency domain direction.

[0043] 14) Regarding the time-frequency domain symbols Time-frequency domain precoding with adjacent carrier inverse padding is performed to obtain the precoding result X. TF ;

[0044]

[0045] 15) For the precoding result X TF Perform the Heisenberg transform and add a cyclic prefix to obtain the time-domain transmit symbol s(t);

[0046] 2) At the receiving end

[0047] 21) Remove the cyclic prefix from the received signal r(t) and perform a Wigner transform to obtain the time-frequency domain symbol.

[0048] 22) For adjacent time-frequency domain symbols within the same time slot in the time-frequency domain Perform inverse equal-gain combining to obtain the combined result Y. TF ;

[0049]

[0050] 23) Using equivalent time-frequency domain channel coefficients for Y TF Perform time-frequency domain point division equalization to obtain the equalized time-frequency domain symbol R. TF ;

[0051]

[0052] Among them, the time-frequency domain equivalent coefficients For (H) TF [l,k]+H TF [l+1, k]), where l represents the index of the frequency direction.

[0053] 24) Equalize the time-frequency domain symbol R along the frequency domain direction. TF Insert 0s at intervals to obtain Again Perform a symmetric Fourier transform to obtain the time-delayed Doppler domain symbol.

[0054] In step 2), the time-delay Doppler symbol is repeatedly pre-coded along the time delay direction to obtain the time-delay Doppler symbol X. DD for:

[0055]

[0056] Simulation Experiment

[0057] To better verify and evaluate the performance of this invention, its performance was compared with that of an uncoded orthogonal time-frequency control under different detection methods. Both were coded using MATLAB, and the simulation iterations were 10. 5 Second-rate.

[0058] Figure 3 The graph shows a comparison of the bit error rate performance of the present invention and the uncoded orthogonal time-frequency control under the same channel conditions and different detection methods. It can be seen that the present invention always obtains the best detection performance when the signal-to-noise ratio is less than 30dB, and the maximum gain can reach 15dB under the same detection method.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An orthogonal time-frequency-space method for interference self-cancellation in high-mobility extended coverage networks, characterized in that, Includes the following steps: 1) The transmitting end performs constellation mapping, repetitive precoding, inverse symmetric Fourier transform, time-frequency domain precoding, and Heisenberg transform on the data to be transmitted in sequence, and then adds a cyclic prefix before sending it out; 2) The receiving end receives the signal. The time-delay Doppler symbol is obtained by sequentially performing the following steps: removal of the cyclic prefix, Wigner transform, inverse equal gain combining, time-frequency domain point division equalization, frequency domain directional zero-interpolation, and symplectic Fourier transform. To achieve interference self-cancellation orthogonal time-frequency space in high mobility extended coverage networks; The specific operation of step 1) is as follows: 11) At the transmitting end, perform constellation mapping on the data to be transmitted to obtain... A QAM symbol, based on the QAM symbol construction symbol matrix Where M is the number of subcarriers and N is the number of time slots; 12) For the symbol matrix Perform repeated precoding to obtain the time-delayed Doppler domain symbol. ; 13) For the time-delay Doppler domain symbol Performing an inverse symplectic Fourier transform yields the time-frequency domain symbols separated by zero symbols in the frequency domain direction. ; 14) Regarding the time-frequency domain symbols Time-frequency domain precoding with adjacent carrier backfilling is performed to obtain the precoding result. ; 15) The precoding result Perform a Heisenberg transform and add a cyclic prefix to obtain the time-domain transmit symbol. ; The precoding result in step 14) for: Step 2) is as follows: 21) The receiving end receives the signal. Remove the cyclic prefix and then perform a Wigner transform to obtain the time-frequency domain symbol. ; 22) For adjacent time-frequency domain symbols within the same time slot in the time-frequency domain Perform inverse equal-gain merging to obtain the merged result. ; 23) Using equivalent time-frequency domain channel coefficients to... Perform time-frequency domain point division equalization to obtain the equalized time-frequency domain symbol. ; 24) Equalize the time-frequency domain symbols along the frequency domain direction. Insert 0s at intervals to obtain And then Perform a symmetric Fourier transform to obtain the time-delayed Doppler domain symbol. .

2. The interference self-cancellation orthogonal time-frequency-space method in a high-mobility extended coverage network according to claim 1, characterized in that, The merged result in step 22) ; 。 3. The interference self-cancellation orthogonal time-frequency-space method in a high-mobility extended coverage network according to claim 1, characterized in that, Step 23) Equalized time-frequency domain symbols ; in, These are the time-frequency domain equivalent coefficients. An index indicating the direction of frequency.

4. The interference self-cancellation orthogonal time-frequency-space method in a high-mobility extended coverage network according to claim 3, characterized in that, The time-frequency domain equivalent coefficients for .

5. The interference self-cancellation orthogonal time-frequency-space method in a high-mobility extended coverage network according to claim 1, characterized in that, The time-delayed Doppler symbol for: ； in, Represents two dimensions The matrix obtained by merging the columns of the unit vector matrix.

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