OTFS signal processing system and method based on frequency hopping anti-interference

Abstract

The invention discloses an OTFS signal processing system and method based on frequency hopping interference resistance. The system comprises an encoder, an interleaver, a constellation mapping module, a time delay-Doppler mapping module, an OTFS modulation module, a channel, an OTFS demodulation module, a time delay-Doppler de-mapping module, a constellation de-mapping module, a de-interleaver and a decoder which are connected in sequence, and the time delay-Doppler demapping module is also connected with a second frequency hopping pattern module. According to the embodiment of the invention, frequency hopping is combined with OTFS, the number of nodes influenced by single-tone interference is reduced, and the number of nodes influenced by single-tone interference can be further reduced or even avoided through the mode of frequency hopping on the time delay-Doppler domain.

Description

Technical Field

[0001] This application belongs to the field of communication technology, and in particular relates to an OTFS (Orthogonal Time Frequency Space) signal processing system and method based on frequency hopping anti-interference. Background Technology

[0002] As the electromagnetic environment becomes increasingly complex, the interference problems faced by communication systems are becoming more and more severe, which has spurred the rapid development of anti-interference technologies such as spread spectrum and frequency hopping. However, most current frequency hopping schemes are combined with OFDM (Orthogonal Frequency Division Multiplexing), which uses random frequency allocation in the frequency domain to combat interference from the frequency domain. However, the anti-interference performance will deteriorate when the interfering frequency is not orthogonal to the subcarrier. Summary of the Invention

[0003] This application provides an OTFS signal processing system and method based on frequency hopping anti-interference, which at least solves the problem that most frequency hopping schemes in related technologies are combined with OFDM, and have low anti-interference performance when the interference frequency point is not orthogonal to the subcarrier.

[0004] In a first aspect, embodiments of this application provide an OTFS signal processing system based on frequency hopping anti-interference, comprising an encoder, an interleaver, a constellation mapping module, a time delay-Doppler mapping module, an OTFS modulation module, a channel, an OTFS demodulation module, a time delay-Doppler demapping module, a constellation demapping module, a deinterleaver, and a decoder connected in sequence. The time delay-Doppler mapping module is further connected to a first frequency hopping pattern module, and the time delay-Doppler demapping module is further connected to a second frequency hopping pattern module.

[0005] The time-delay-Doppler mapping module is used to randomly select multiple time-delay nodes along the time-delay dimension and multiple Doppler nodes along the Doppler dimension in a two-dimensional grid in the time-delay-Doppler domain, generate a frequency hopping pattern corresponding to the target grid point where the multiple time-delay nodes and multiple Doppler nodes intersect, and map the modulation symbol onto the target grid point through the frequency hopping pattern to obtain the first time-delay-Doppler domain symbol and transmit it to the OTFS modulation module;

[0006] The modulation symbols are obtained by encoding and interleaving the source sequence with the encoder and the interleaver to obtain a codeword sequence, and then performing constellation mapping on the codeword sequence through the constellation mapping module.

[0007] The OTFS modulation module is used to perform OTFS modulation on the first time-delay-Doppler domain symbol to obtain a time-domain signal, so that after the time-domain signal passes through the channel, the receiver generates a target information sequence through the OTFS demodulation module, the time-delay-Doppler demapping module, the constellation demapping module, the deinterleaver, and the decoder.

[0008] Secondly, embodiments of this application provide an OTFS signal processing method based on frequency hopping interference immunity, the method being applied to an OTFS signal processing system based on frequency hopping interference immunity as described in any embodiment of the first aspect, the method comprising:

[0009] The source sequence is encoded and interleaved by an encoder and an interleaver to obtain a codeword sequence.

[0010] The codeword sequence is mapped using a constellation mapping module to obtain modulation symbols.

[0011] The modulation symbols are mapped to first time-delay-Doppler domain symbols using a time-delay-Doppler mapping module;

[0012] The time-domain signal is obtained by performing OTFS modulation on the first time-delay-Doppler domain symbol using the OTFS modulation module;

[0013] After the time-domain signal passes through the channel, the receiving end generates the target information sequence through the OTFS demodulation module, the time-delay-Doppler demapping module, the constellation demapping module, the deinterleaver, and the decoder.

[0014] The OTFS signal processing system and method based on frequency hopping anti-interference in this application combines frequency hopping with OTFS. Even if the frequency of single-tone interference is not orthogonal to the subcarrier, the single-tone interference will only affect Doppler nodes with a Doppler value of Nα (Nα is an integer) in the time delay-Doppler domain, unlike OFDM which affects multiple subcarriers or even the entire frequency band. That is, by using OTFS, the number of nodes affected by single-tone interference is reduced. Furthermore, by using frequency hopping in the time delay-Doppler domain, the number of nodes affected by single-tone interference can be further reduced or even avoided. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the subcarrier frequency hopping FH-OFDM principle;

[0017] Figure 2This is a schematic diagram of the structure of an OTFS signal processing system based on frequency hopping anti-interference provided in an embodiment of this application;

[0018] Figure 3 This is a schematic diagram illustrating the principle of OTFS modulation provided in the embodiments of this application;

[0019] Figure 4 This is a schematic diagram of orthogonal frequency interference provided in an embodiment of this application;

[0020] Figure 5 This is an exemplary time-delay-Doppler domain frequency hopping diagram provided in the embodiments of this application;

[0021] Figure 6 This is a schematic flowchart of an OTFS signal processing method based on frequency hopping anti-interference provided in an embodiment of this application;

[0022] Figure 7 This is a schematic diagram illustrating the system BER performance results under different disturbances provided in the embodiments of this application;

[0023] Figure 8 This is a schematic diagram of the system BLER performance results under different disturbances provided in the embodiments of this application. Detailed Implementation

[0024] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0025] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0026] Table 1 below shows the meaning of each abbreviation in the following text.

[0027] Table 1

[0028]

[0029]

[0030] As the electromagnetic environment becomes increasingly complex, the interference problems faced by communication systems are becoming more and more severe, which has spurred the rapid development of anti-interference technologies such as spread spectrum and frequency hopping. However, most current frequency hopping schemes are combined with OFDM, which uses random frequency allocation in the frequency domain to combat interference from the frequency domain. But when the interfering frequency is not orthogonal to the subcarrier, the anti-interference performance will deteriorate.

[0031] Specifically, Figure 1 A schematic diagram of the subcarrier frequency hopping FH-OFDM (Frequency Hopping Orthogonal Frequency Division Multiplexing) principle is shown.

[0032] like Figure 1 As shown, the actual number of subcarriers transmitted in subcarrier frequency-hopping FH-OFDM is generally less than the maximum number of available subcarriers in the system. The transmitter performs modulation processing such as encoding and interleaving on the binary data, then maps the subcarriers using a frequency-hopping pattern. Following this, it performs traditional OFDM operations such as IFFT (Inverse Finite Fourier Transform). The receiver performs OFDM operations such as FFT (Finite Fourier Transform) on the received data, then demaps the FFT data according to the frequency-hopping pattern to extract the specified subcarrier data. Finally, it performs demodulation, deinterleaving, and decoding to complete the reception of the binary data.

[0033] Frequency-hopping subcarrier FH-OFDM can be further divided into single-subcarrier FH-OFDM and multi-subcarrier FH-OFDM, depending on the number of subcarriers used for data transmission each time. Single-subcarrier FH-OFDM uses only one subcarrier to transmit valid information at a time during subcarrier mapping. Multi-subcarrier FH-OFDM maps data onto multiple different subcarriers for each transmission. Obviously, multi-subcarrier FH-OFDM, using multiple subcarriers for transmission, generally has a faster transmission rate than single-subcarrier FH-OFDM under the same conditions.

[0034] Although subcarrier frequency hopping FH-OFDM can combat narrowband interference in the frequency domain, when the subcarrier frequency is not orthogonal to the single-tone interference frequency, the interference will leak onto multiple subcarriers or even spread to the entire frequency band. In this case, the ability of the subcarrier frequency hopping FH-OFDM system to combat interference by subcarrier frequency hopping is reduced, and the performance will deteriorate sharply.

[0035] To address the problems in the related technologies, this application provides an OTFS signal processing system and method based on frequency hopping anti-interference.

[0036] It should be noted that, for the future needs of 6G mobile communication and integrated air-space-ground-sea communication, OTFS modulation, as a multi-carrier modulation technology suitable for high-mobility communication, has shown significant performance advantages compared to OFDM. Therefore, it is necessary to study frequency hopping schemes under OTFS systems.

[0037] The OTFS signal processing system based on frequency hopping anti-interference provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0038] refer to Figure 2 This is a schematic diagram of the structure of an OTFS signal processing system based on frequency hopping anti-interference according to an embodiment of this application. Figure 2 As shown, the OTFS signal processing system based on frequency hopping interference immunity includes an encoder, an interleaver, a constellation mapping module, a time-delay-Doppler mapping module, an OTFS modulation module, a channel, an OTFS demodulation module, a time-delay-Doppler demapping module, a constellation demapping module, a deinterleaver, and a decoder connected in sequence. The time-delay-Doppler mapping module is also connected to a first frequency hopping pattern module, and the time-delay-Doppler demapping module is also connected to a second frequency hopping pattern module.

[0039] First, the OTFS modulation principle in the embodiments of this application will be explained.

[0040] refer to Figure 3 This is a schematic diagram illustrating the principle of OTFS modulation. It should be understood that... Figure 3 The inner frame can be replaced with commonly used time-frequency domain multicarrier modulation.

[0041] Assume that the total duration of a data burst is NT and the total bandwidth is MΔf, where N is the number of OTFS symbols, M is the number of OTFS subcarriers, T is the symbol time interval, and Δf is the subcarrier frequency interval.

[0042] like Figure 3As shown, OTFS modulation consists of a cascade of two two-dimensional transforms at the transmitter and receiver. The transmitter maps the information symbol x[k,l] in the two-dimensional time-delay-Doppler domain to the information symbol X[n,m] in the time-frequency domain through a combination of inverse symplectic finite Fourier transform and windowing. This cascaded operation is called the OTFS transform. Assuming the window function under consideration is a rectangular window, x[k,l] can be transformed into X[n,m] simply by ISFFT, that is:

[0043]

[0044] Next, the time-frequency signal is transformed into a time-domain signal using the Heisenberg transform, as shown in equation (2), and the transmitted pulse g is used. tx (t) maps X[n,m] on the time-frequency grid to a continuous time-domain waveform s(t), that is:

[0045]

[0046] It is worth noting that the Heisenberg transform represents universal time-frequency modulation, with OFDM modulation being a special case. If g tx (t) is a rectangular pulse with a pulse width of T, and formula (2) degenerates into the traditional IFFT. Therefore, an OTFS block can be regarded as the result of ISFFT precoding of N consecutive independent OFDM symbols (where the number of subcarriers is M).

[0047] At the receiver, the matched filter calculates the ambiguity function for the time-domain received signal r(t) using formula (3a) and samples the received symbol Y[n,m] in the time-frequency domain, then:

[0048]

[0049] Y[n,m]=Y(t,f)| t＝nT,f＝mΔf ,n=0,...,N-1,m=0,...,M-1 (3b)

[0050] Among them, g rx (t) is the receiving filter pulse; Equations (3a) and (3b) are collectively called the Wigner transform, which is the inverse transform of the Heisenberg transform.

[0051] Finally, perform an SFFT on Y[n,m] to obtain the time-delay-Doppler domain received symbol y[k,l]:

[0052]

[0053] Furthermore, given the OTFS system parameters: subcarrier spacing Δf, carrier period T, number of subcarriers M, number of symbols N, and one OTFS frame containing NM sampled symbols, assuming the interference source is a fixed-frequency single-tone interference, and defining q = m + nM, the time-domain discrete expression of the interference signal is:

[0054]

[0055] in, Let and α be the normalized integer and fractional parts of the single-tone frequency relative to the subcarrier spacing, respectively. Transforming them to the time-delay-Doppler domain yields:

[0056]

[0057] When the interference frequency is orthogonal to the subcarrier, i.e., α = 0, we have:

[0058]

[0059] refer to Figure 4 This is a schematic diagram of orthogonal frequency interference. For example... Figure 4 As shown, when a single-tone interference orthogonal to the subcarrier is transformed to the time-delay-Doppler domain, it is not zero only at the zero point of the Doppler axis. At this time, the single / multi-tone interference only affects the sign with a Doppler value of 0.

[0060] In other words, when α ≠ 0, but Nα is an integer, then the following condition is met:

[0061]

[0062] It can be seen that when Nα is an integer, single-tone interference only affects Doppler nodes with a Doppler value of Nα. When a fractional part exists, a spectral leakage effect occurs, with the nearest point being most severely affected, and the interference spreading throughout the entire Doppler band.

[0063] In traditional frequency-hopping OFDM schemes, when the frequencies of the subcarriers and the single-tone interference are not orthogonal, the single-tone interference will leak to multiple subcarriers or even the entire frequency band, resulting in many or even all symbols in the time and frequency domain being affected by the single-tone interference.

[0064] Therefore, in this embodiment, by combining frequency hopping with OTFS, even if the frequency of the single-tone interference is not orthogonal to the subcarrier, when Nα is an integer, the single-tone interference will only affect the Doppler nodes with a Doppler value of Nα in the time-delay-Doppler domain, unlike OFDM which affects multiple subcarriers or even the entire frequency band. That is, by using OTFS, the number of nodes affected by single-tone interference is reduced; and by using frequency hopping in the time-delay-Doppler domain, the number of nodes affected by single-tone interference can be further reduced or even avoided.

[0065] In some embodiments, for the time-delay-Doppler mapping module in the OTFS signal processing system based on frequency hopping anti-interference, the module is used to randomly select multiple time-delay nodes along the time-delay dimension and multiple Doppler nodes along the Doppler dimension in a two-dimensional grid in the time-delay-Doppler domain, generate a frequency hopping pattern corresponding to the target grid point where the multiple time-delay nodes and multiple Doppler nodes intersect, map the modulation symbol onto the target grid point through the frequency hopping pattern to obtain a first time-delay-Doppler domain symbol and transmit it to the OTFS modulation module.

[0066] The modulation symbols are obtained by encoding and interleaving the source sequence with the encoder and interleaver to obtain the codeword sequence, and then performing constellation mapping on the codeword sequence through the constellation mapping module.

[0067] Optionally, in the two-dimensional grid of the time-delay-Doppler domain, the target grid point includes the corresponding data, while the remaining grid points are empty.

[0068] In other words, in a two-dimensional grid in the time-delay-Doppler domain, a subset of Doppler nodes are randomly selected along the Doppler dimension, and a subset of time-delay nodes are randomly selected along the time-delay dimension to generate a frequency-hopping pattern. The modulation symbols are then mapped onto the selected grid points through the frequency-hopping pattern for information transmission. Furthermore, data is placed only at the intersections of the selected nodes; that is, some rows and some columns are selected, and the intersections of these rows and columns constitute the frequency-hopping pattern. Data is placed only at the selected intersections, meaning that the two-dimensional grid only contains data at the nodes within the frequency-hopping pattern, while all other positions are zero.

[0069] In some embodiments, the OTFS modulation module is used to perform OTFS modulation on the first delay-Doppler domain symbol to obtain a time-domain signal, so that after the time-domain signal passes through the channel, the receiver generates a target information sequence through the OTFS demodulation module, the delay-Doppler demapping module, the constellation demapping module, the deinterleaver, and the decoder.

[0070] Figure 5 An exemplary time-delay-Doppler domain frequency hopping diagram is shown. As the analysis above shows, since single-tone interference only affects nodes with a Doppler node of Nα, in order to further reduce the impact of single-tone interference, only a portion of the time-delay nodes and a portion of the Doppler nodes are selected to transmit data in the time-delay-Doppler domain.

[0071] like Figure 5As shown, in the two-dimensional delay-Doppler domain, the number of nodes in the delay dimension (i.e., the number of subcarriers) M = 8, and the number of nodes in the Doppler dimension N = 6. Selecting nodes 0, 2, and 6 in the delay dimension (i.e., three rows in the two-dimensional grid of the delay-Doppler domain) and nodes 0 and 3 in the Doppler dimension (i.e., two columns in the two-dimensional grid of the delay-Doppler domain), the intersection of the selected delay nodes and Doppler nodes forms the generated frequency hopping pattern. Symbols are placed in the delay-Doppler domain (i.e.,... Figure 5 (Left figure), after inverse symplectic finite Fourier transform, it is transformed to the time-frequency domain (i.e., Figure 5 (See right figure), and then perform Heisenberg transformation to the time domain before sending.

[0072] Thus, based on the nature of single / multi-tone interference, when Nα is an integer, single / multi-tone interference only affects the resource grid with a Doppler value of Nα in the time delay-Doppler domain. By performing frequency hopping in the Doppler dimension, the Doppler value affected by single / multi-tone interference will be probabilistically not selected during frequency hopping. At this time, the interference will not affect the transmitted data, thereby achieving anti-interference.

[0073] Furthermore, in some embodiments, the channel is an AWGN channel with single-tone interference. Therefore, the received signal obtained by the receiver includes: a time-domain signal, white Gaussian noise, and a single-tone interference signal.

[0074] That is, the received signal is: r(t) = s(t) + n(t) + j(t);

[0075] Where s(t) represents the time-domain signal, n(t) represents Gaussian white noise, and j(t) represents the single-tone interference signal.

[0076] In some embodiments, the OTFS demodulation module is used to perform OTFS demodulation on the received signal at the channel receiver to transform the received signal into a time-delay-Doppler domain to obtain a second time-delay-Doppler domain symbol, wherein the received signal is obtained by receiving the time-domain signal after passing through the channel.

[0077] In some embodiments, the second frequency hopping pattern module is used to extract valid information symbols from the second delay-Doppler domain symbols.

[0078] In some embodiments, the constellation demapping module is used to perform constellation demapping on the valid information symbols, or to delete the valid information symbols if they are interfered with.

[0079] As an optional embodiment, the constellation demapping module is specifically used to demap the effective information symbols to the corresponding bit log-likelihood ratio, or to set the corresponding bit log-likelihood ratio to 0 when the effective information symbols are interfered with.

[0080] In this way, the receiving end removes the interfered portion of the received data before decoding based on the interfered Doppler value, thereby further avoiding the impact of interference. It should be noted that, in this embodiment, the interfered Doppler value is a known value that can be determined at the receiving end.

[0081] It should be noted that, for ease of description, the above devices are described in terms of function, divided into various modules. Of course, in implementing this application, the functions of each module can be implemented in one or more software and / or hardware.

[0082] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0083] Furthermore, this application also provides an OTFS signal processing method based on frequency hopping interference immunity. It should be noted that the OTFS signal processing method based on frequency hopping interference immunity can be applied to the OTFS signal processing system based on frequency hopping interference immunity as described in any of the above embodiments.

[0084] Figure 6 A schematic flowchart of the OTFS signal processing method based on frequency hopping anti-interference according to an embodiment of this application is shown. Figure 6 As shown, the OTFS signal processing method based on frequency hopping interference immunity may specifically include the following steps:

[0085] S601. The source sequence is encoded and interleaved by an encoder and an interleaver to obtain a codeword sequence.

[0086] S602. The codeword sequence is mapped to a constellation using a constellation mapping module to obtain modulation symbols;

[0087] S603. The modulation symbol is mapped to a first time-delay-Doppler domain symbol through the time-delay-Doppler mapping module;

[0088] S604. The first time-delay-Doppler domain symbol is modulated by the OTFS modulation module to obtain a time-domain signal;

[0089] S605. After the time-domain signal passes through the channel, the receiving end generates the target information sequence through the OTFS demodulation module, the time-delay-Doppler demapping module, the constellation demapping module, the deinterleaver, and the decoder.

[0090] The specific implementation methods for each of the above steps are described below.

[0091] In some embodiments, in S603, in a two-dimensional grid in the time-delay-Doppler domain, multiple time-delay nodes are randomly selected along the time-delay dimension and multiple Doppler nodes are randomly selected along the Doppler dimension; a frequency-hopping pattern corresponding to the target grid point where the multiple time-delay nodes and multiple Doppler nodes intersect is generated; the modulation symbol is mapped onto the target grid point through the frequency-hopping pattern to obtain a first time-delay-Doppler domain symbol.

[0092] In some embodiments, in S605, after the time-domain signal passes through the channel, the receiving end receives the received signal; the received signal is demodulated by the OTFS demodulation module to transform the received signal into the time-delay-Doppler domain to obtain a second time-delay-Doppler domain symbol; the effective information symbol is extracted from the second time-delay-Doppler domain symbol by the second frequency hopping pattern module; the effective information symbol is demapped by the constellation demapping module, or, if the effective information symbol is interfered with, it is deleted.

[0093] In practice, the bitstream u first passes through a channel encoder with a code rate of R and then is interleaved to generate a codeword sequence c of length QMN (Q is the modulation order, which is related to the size of the constellation point set by |A| = 2). Q Then, through the pseudo-random sequence generated by the constellation mapping and frequency hopping pattern mapping modules, the modulation symbols are mapped onto a selected grid in the time-delay-Doppler domain. The modulation symbols mapped in the time-delay-Doppler domain are then converted into a time-domain signal s by OTFS modulation. Further, after passing through the channel, the receiver first performs OTFS demodulation on the received signal r, transforming the received signal r into the time-delay-Doppler domain, and then extracts the effective information symbols through the frequency hopping pattern module. Then, corresponding constellation demapping and deinterleaving are performed. Specifically, during demapping, the interfered parts of the received data are deleted. Finally, the data is sent to the channel decoder for decoding, and the target information sequence is finally obtained.

[0094] Therefore, by combining frequency hopping with OTFS, even if the frequency of single-tone interference is not orthogonal to the subcarrier, single-tone interference will only affect Doppler nodes with a Doppler value of Nα (Nα is an integer) in the time-delay-Doppler domain, unlike OFDM which affects multiple subcarriers or even the entire frequency band. In other words, by using OTFS, the number of nodes affected by single-tone interference is reduced. Furthermore, by using frequency hopping in the time-delay-Doppler domain, the number of nodes affected by single-tone interference can be further reduced or even avoided.

[0095] Next, the anti-interference performance of the embodiments of this application will be further illustrated through simulation.

[0096] Specifically, the OTFS signal processing system based on frequency hopping anti-interference in this application embodiment was simulated under no interference, 0.78% single-tone interference, and 2.34% multi-tone interference, respectively. The system parameters are shown in Table 2 below.

[0097] Table 2

[0098] parameter Value Number of subcarriers 32 Symbolic Number 128 Mapping pattern carrier number 16 Number of mapping pattern symbols 16 Subcarrier spacing 15kHz Modulation method 4-QAM Single-tone interference frequency 7.5kHz Multi-tone interference frequency 7.5kHz, 16.875kHz, 18.75kHz Encoding method LDPC Bit length (bitrate) 512(1 / 4) Decoding algorithm (maximum number of iterations) SPA(50) Channel Model AWGN

[0099] Figure 7 The system BER performance results under different disturbances are shown. Figure 7 As shown, when BER is 10 -5 At that time, compared with the system without interference, the system under single-tone interference has only about 0.08dB of performance loss, and the system under multi-tone interference has only about 0.3dB of performance loss.

[0100] Figure 8 The system BLER performance results under different disturbances are shown. Figure 8 As shown, when BLER is 10 -3 At that time, compared with the system without interference, the system under single-tone interference has a performance loss of about 0.08dB, and the system under multi-tone interference has a performance loss of about 0.3dB.

[0101] Therefore, from Figure 7 , Figure 8 The results show that the frequency hopping scheme under the OTFS system in this application embodiment can resist 0.78% of single-tone interference and 2.34% of multi-tone interference.

[0102] As can be seen, in this embodiment, frequency hopping is combined with the OTFS system. Frequency hopping occurs in the delay-Doppler domain. A frequency hopping pattern is generated by randomly selecting some nodes in the delay and Doppler dimensions. During transmission, the transmitted symbols are mapped using the frequency hopping pattern, and the remaining grid points are padded with zeros. The receiver extracts the received symbols from the frequency hopping pattern and then performs subsequent operations on them. Compared with the traditional scheme combining frequency hopping and OFDM, this approach can combat the impact of interference on data when single / multi-tone interference frequencies are not orthogonal to subcarriers.

[0103] Furthermore, for more complex channel conditions, such as time-frequency dual-selection channels in high-speed mobile scenarios, the channel becomes a time-frequency dual-selection channel in high-speed mobile scenarios. Under such channels, traditional OFDM technology will generate inter-carrier interference due to severe Doppler spread, resulting in a serious deterioration in system performance. However, the OTFS technology used in the embodiments of this application can effectively combat Doppler spread, and therefore has better performance than OFDM technology in high-speed mobile scenarios.

[0104] It should be noted that the above description describes some embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0105] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0106] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected," "linked," and "attached" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0107] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0108] In this application, "multiple" means two or more (including two).

[0109] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0110] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0111] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. An OTFS signal processing system based on frequency hopping interference suppression, characterized in that, The system includes an encoder, an interleaver, a constellation mapping module, a time-delay-Doppler mapping module, an OTFS modulation module, a channel, an OTFS demodulation module, a time-delay-Doppler demapping module, a constellation demapping module, a deinterleaver, and a decoder, all connected in sequence. The time-delay-Doppler mapping module is also connected to a first frequency hopping pattern module, and the time-delay-Doppler demapping module is also connected to a second frequency hopping pattern module. The time-delay-Doppler mapping module is used to randomly select multiple time-delay nodes along the time-delay dimension and multiple Doppler nodes along the Doppler dimension in a two-dimensional grid in the time-delay-Doppler domain, generate a frequency hopping pattern corresponding to the target grid point where the multiple time-delay nodes and multiple Doppler nodes intersect, and map the modulation symbol onto the target grid point through the frequency hopping pattern to obtain the first time-delay-Doppler domain symbol and transmit it to the OTFS modulation module; The modulation symbols are obtained by encoding and interleaving the source sequence with the encoder and the interleaver to obtain a codeword sequence, and then performing constellation mapping on the codeword sequence through the constellation mapping module. The OTFS modulation module is used to perform OTFS modulation on the first time-delay-Doppler domain symbol to obtain a time-domain signal, so that after the time-domain signal passes through the channel, the receiver generates a target information sequence through the OTFS demodulation module, the time-delay-Doppler demapping module, the constellation demapping module, the deinterleaver, and the decoder.

2. The system according to claim 1, characterized in that, The OTFS demodulation module is used to perform OTFS demodulation on the received signal at the channel receiver to transform the received signal into a time-delay-Doppler domain to obtain a second time-delay-Doppler domain symbol. The received signal is obtained by receiving the time-domain signal after it passes through the channel.

3. The system according to claim 2, characterized in that, The second frequency hopping pattern module is used to extract valid information symbols from the second delay-Doppler domain symbols.

4. The system according to claim 3, characterized in that, The constellation demapping module is used to perform constellation demapping on the valid information symbols, or to delete the valid information symbols if they are interfered with.

5. The system according to claim 4, characterized in that, The constellation demapping module is specifically used to demap the effective information symbols to the corresponding bit log-likelihood ratios, or to set the corresponding bit log-likelihood ratios to 0 when the effective information symbols are interfered with.

6. The system according to claim 1, characterized in that, In a two-dimensional grid in the time-delay-Doppler domain, the target grid point contains the corresponding data, while the remaining grid points are empty.

7. The system according to claim 2, characterized in that, The channel is an AWGN channel with single-tone interference, and the received signal includes a time-domain signal, white Gaussian noise, and single-tone interference signal.

8. An OTFS signal processing method based on frequency hopping anti-interference, characterized in that, The method is applied to the OTFS signal processing system based on frequency hopping interference suppression as described in any one of claims 1-7, and the method includes: The source sequence is encoded and interleaved by an encoder and an interleaver to obtain a codeword sequence. The codeword sequence is mapped using a constellation mapping module to obtain modulation symbols. The modulation symbols are mapped to first time-delay-Doppler domain symbols using a time-delay-Doppler mapping module; The time-domain signal is obtained by performing OTFS modulation on the first time-delay-Doppler domain symbol using the OTFS modulation module; After the time-domain signal passes through the channel, the receiving end generates the target information sequence through the OTFS demodulation module, the time-delay-Doppler demapping module, the constellation demapping module, the deinterleaver, and the decoder.

9. The method according to claim 8, characterized in that, The step of mapping the modulation symbol to a first time-delay-Doppler domain symbol via the time-delay-Doppler mapping module includes: In a two-dimensional grid in the time-delay-Doppler domain, multiple time-delay nodes are randomly selected along the time-delay dimension and multiple Doppler nodes are randomly selected along the Doppler dimension. Generate frequency hopping patterns corresponding to target grid points where multiple time delay nodes intersect with multiple Doppler nodes; The modulation symbol is mapped onto the target grid point through the frequency hopping pattern to obtain the first time-delay-Doppler domain symbol.

10. The method according to claim 8, characterized in that, After the time-domain signal passes through the channel, the receiving end generates a target information sequence through an OTFS demodulation module, a time-delay-Doppler demapping module, a constellation demapping module, a deinterleaver, and a decoder, including: After the time-domain signal passes through the channel, the receiving end receives the received signal; The received signal is demodulated using an OTFS demodulation module to transform it into a time-delay-Doppler domain symbol, thus obtaining a second time-delay-Doppler domain symbol. The effective information symbols are extracted from the second delay-Doppler domain symbols by the second frequency hopping pattern module; The valid information symbols can be demapped using a constellation demapping module, or they can be deleted if they are interfered with.

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