Method for reducing PAPR of multi-carrier faster-than-nyquist system

Abstract

Disclosed in the present invention is a method for reducing the PAPR of a multi-carrier faster-than-Nyquist system, comprising: sequentially performing coding, interleaving, constellation mapping, and serial-to-parallel conversion on a source sequence to obtain K subsequences; sequentially performing upsampling and pulse shaping on the K subsequences; modulating K shaped signal sequences onto K different subcarriers, and using different first phase rotation components to rotate a symbol sequence on each subcarrier by an initial phase to obtain K subcarrier signals; dividing the K subcarrier signals into U groups, multiplying a u-th (u=1, 2, ..., U) group of subcarrier signals by a corresponding second phase rotation component, respectively, and then superimposing all the subcarrier signals to obtain a signal having a reduced PAPR; and performing peak clipping processing on the signal having the reduced PAPR to obtain a signal having a further reduced PAPR. The present invention can effectively reduce the PAPR of a multi-carrier faster-than-Nyquist system and reduce system performance loss.

Description

A method for reducing PAPR in a multi-carrier super Nyquist system Technical Field

[0001] This invention belongs to the field of communications, specifically relating to a method for reducing PAPR in a multi-carrier super Nyquist system. Background Technology

[0002] In recent years, with the rapid development and large-scale commercial deployment of 5G, wireless data access traffic has surged, and people's demand for high transmission rates in communication systems has continued to grow. The data transmission rates of traditional communication systems can no longer meet the needs of modern users, leading the industry to focus on the evolution of 5G and the research of new 6G technologies. The convergence of space, ground, and terrestrial networks is one of the key features of 6G mobile communication systems. It combines high-orbit satellite networks, low-orbit satellite networks, and terrestrial cellular networks to form a seamlessly covered mobile communication network, meeting users' precise access and diverse service needs anytime, anywhere. However, due to limited spectrum resources, communication networks should possess high spectral efficiency. Furthermore, addressing the power limitations of satellite communication, how to more effectively reduce the peak-to-average power ratio (PAPR) to achieve high-speed and stable transmission has become an important research topic for communication systems.

[0003] New-generation communication systems have incorporated numerous waveform techniques with high spectral and energy efficiency. Super Nyquist Transmission (FTN) and Multi-Carrier FTN (MFTN) communication systems have received significant attention in this regard due to their potential to improve spectral efficiency. Compared to Orthogonal Frequency Division Multiplexing (OFDM) systems, MFTN systems are non-orthogonal transmission methods that intentionally introduce overlap between information symbols in both the time and frequency domains, thereby greatly enhancing spectral efficiency. It has been demonstrated that MFTN systems, which simultaneously perform time and frequency compression, can save up to 50% of bandwidth without significant loss in BLER (Block Error Rate).

[0004] In practical communication systems, high-power amplifiers are needed to overcome signal attenuation over long distances. However, if the PAPR of the transmitted signal is high, the power amplifier will operate in the saturation region, introducing nonlinear distortion into the transmitted signal. To avoid this nonlinear distortion, traditional satellite communication typically employs power backoff. However, this is not suitable for future space / air / terrestrial networks as it may significantly reduce energy efficiency. F. Schachch and T. Wild, in their paper "A reduced complexity receiver for multi-carrier faster-than-Nyquist signaling" (2013 IEEE Globecom Workshops, 2013, pp. 235-240), point out that the PAPR of multi-carrier FTN systems is higher than that of OFDM systems, posing a challenge to the application of multi-carrier FTN technology.

[0005] In related technologies, PAPR reduction methods for multi-carrier communication systems can be divided into frequency domain methods and time domain methods. Frequency domain methods, such as Partial Transmission Sequence (PTS), generate multiple candidate signals to represent the original signal using certain mathematical methods and select the candidate signal with the lowest PAPR for transmission; however, their implementation complexity is high. Time domain methods reduce PAPR by adding an additional signal before the power amplifier to reduce peak values ​​or increase the average power of the signal. Commonly used methods mainly include clipping, compensated modulation, and predistortion. However, due to significant inter-symbol interference (ISI) and inter-carrier interference (ICI), these time domain methods cannot be directly extended to multi-carrier FTN systems. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a method for reducing PAPR in a multi-carrier super Nyquist system.

[0007] The technical problem to be solved by this invention is achieved through the following technical solution:

[0008] A method for reducing PAPR in a multi-carrier super Nyquist system includes:

[0009] The source sequence is sequentially encoded, interleaved, mapped by constellation, and converted from serial to parallel to obtain K subsequences;

[0010] The K subsequences are upsampled and pulse-shaped sequentially to obtain K shaped signal sequences;

[0011] The K shaped signal sequences are modulated onto K different subcarriers, and the symbol sequence on each subcarrier is rotated by an initial phase using different first phase rotation components to obtain K subcarrier signals;

[0012] The K subcarrier signals are divided into U groups. The subcarrier signals of the uth group (u = [1,2,...,U]) are multiplied by the corresponding second phase rotation component. Then, all the subcarrier signals multiplied by the second phase rotation component are superimposed to obtain the signal with reduced PAPR.

[0013] The PAPR-reduced signal is then subjected to peak clipping to obtain a signal with further reduced PAPR.

[0014] Optionally, the method further includes sending a signal that the PAPR is further reduced.

[0015] Optionally, the method further includes: receiving a signal with the PAPR further reduced to obtain a received signal, and recovering the source sequence from the received signal.

[0016] Optionally, the receiving end recovers the source sequence from the received signal, including:

[0017] The received signal is multiplied by U second negative phase rotation components to obtain U sub-signals; wherein each of the U second negative phase rotation components corresponds to one of the U second phase rotation components and is in opposite phase.

[0018] For each sub-signal, it is multiplied by a corresponding set of first negative phase rotation components, so that U sub-signals multiplied by the first negative phase rotation components yield K recovered subcarrier signals; wherein, all the first negative phase rotation components correspond one-to-one with all the first phase rotation components, and their phases are opposite.

[0019] The K recovered subcarrier signals are sequentially subjected to matched filtering, downsampling, signal detection, and decoding to obtain the recovered source sequence.

[0020] Optionally, the step of modulating the K shaped signal sequences onto K different subcarriers and rotating the symbol sequence on each subcarrier by an initial phase using different first phase rotation components includes:

[0021] For each shaped signal sequence, a set of first phase rotation components corresponding one-to-one with the symbols in the shaped signal sequence are obtained, and each symbol in the shaped signal sequence is multiplied by the corresponding first phase rotation component.

[0022] Among them, the first phase rotation components corresponding to different shaping signal sequences are different.

[0023] Optionally, the first phase rotation component is represented as:

[0024] Where e is the natural base, j is the imaginary part, π is pi, k = [0, 1, ..., K-1], φ ∈ (0, 1] is the frequency domain compression factor, F = 1 / T is the frequency domain spacing of the subcarriers satisfying the orthogonality condition, and T is the symbol spacing of Nyquist transmission.

[0025] Optionally, dividing the K subcarrier signals into U groups includes:

[0026] The number of subcarrier signals in each group is determined using the following formula:

[0027] Among them, P u This represents the number of subcarrier signals in the u-th group;

[0028] Based on the determined number of subcarrier signals in each group, the K subcarrier signals are divided into U groups.

[0029] Optionally, the second phase rotation component corresponding to the u-th subcarrier signal is:

[0030] Where e is the natural base and j is the imaginary part. For each set of angles pre-selected for the u-th subcarrier signal.

[0031] Optionally, the PAPR-reduced signal is subjected to peak clipping processing, including:

[0032] The PAPR-reduced signal is multiplied by a rectangular filter to flatten the waveform above the clipping threshold in the signal.

[0033] Optionally, the peak reduction threshold is calculated using the following formula:

[0034] Among them, A th The peak clipping threshold is represented by PAPR, which represents the peak-to-average power ratio of the signal that is expected to be achieved after the signal with PAPR reduced by the peak clipping process.

[0035] The method for reducing PAPR in a multi-carrier super Nyquist system provided by this invention first modulates K shaped signal sequences onto K different subcarriers. Then, different first-phase rotation components are used to rotate the symbol sequence on each subcarrier by an initial phase, which to some extent avoids the probability of large peaks caused by all subcarriers having completely identical initial phases. Next, the subcarrier signals are grouped, and each group is multiplied by a corresponding second-phase rotation component. All subcarrier signals multiplied by the second-phase rotation component are then superimposed to further reduce the probability of large peaks in the superimposed signal. Finally, peak clipping is performed on the PAPR-reduced signal. Compared to existing technologies that directly reduce PAPR through peak clipping, this invention can reduce system performance loss. Therefore, through the above processing steps, the PAPR of a multi-carrier FTN system can be significantly reduced with minimal performance loss.

[0036] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0037] Figure 1 is a flowchart illustrating a method for reducing PAPR in a multi-carrier super Nyquist system according to an embodiment of the present invention;

[0038] Figure 2 illustrates a modular implementation of an embodiment of the present invention;

[0039] Figure 3 is a comparison of PAPR between a multi-carrier FTN system (referred to as "MFTN IPR-GPR system") and an existing OFDM system when PAPR statistics are performed using CCDF (complementary cumulative distribution function) with the same spectral efficiency.

[0040] Figure 4 is a comparison of PAPR between a multi-carrier FTN system (referred to as "MFTN IPR-GPR-peak clipping system") and an existing OFDM system when PAPR statistics are performed using CCDF and steps S10 to S50 of the present invention are adopted to reduce PAPR.

[0041] Figure 5 shows the frame error rate (BLER) of the "MFTN IPR-GPR-peak clipping" system of this invention and the existing OFDM system as a function of bit signal-to-noise ratio (BNR) under different parameter conditions. b A comparison chart of the changes in / N0). Detailed Implementation

[0042] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0043] Due to the artificial introduction of severe inter-symbol interference and inter-carrier interference, existing research on multi-carrier FTN systems has mostly focused on low-complexity signal detection and achieving high transmission rates. There is relatively little work on reducing PAPR of multi-carrier FTN signals. Moreover, existing PAPR reduction methods for multi-carrier systems are too complex and inconvenient to extend to multi-carrier FTN systems. Therefore, this invention provides a method for reducing PAPR in multi-carrier super Nyquist systems, which has the advantages of low implementation complexity and effective reduction of PAPR in multi-carrier super Nyquist systems. More importantly, when the multi-carrier FTN system compresses only the frequency domain without compressing the time domain, the BLER performance of the multi-carrier FTN system using this invention is almost unaffected.

[0044] As shown in Figure 1, the method for reducing PAPR in a multi-carrier super Nyquist system provided in this embodiment of the invention includes the following steps:

[0045] S10. The source sequence is sequentially encoded, interleaved, mapped by constellation, and converted from serial to parallel to obtain K subsequences.

[0046] Specifically, the source sequence u is encoded to obtain the number sequence c, then interleaved to obtain the interleaved codeword sequence v, and then constellation mapping is performed on the codeword sequence v to obtain the symbol sequence m. Then, the symbol sequence m is converted from string to parallel to obtain K subsequences {m0, m1, ..., m}. k ,…,m K-1}

[0047] S20. The K subsequences are upsampled and pulse-shaped sequentially to obtain K shaped signal sequences.

[0048] Specifically, for subsequence m k The sampled signal is upsampled to obtain a sampled sequence, and then pulse-shaped to obtain a shaped signal sequence.

[0049] Where, x k,n Represents a pair of subsequences m k The nth symbol in the sampled sequence obtained by upsampling, where N is the symbol length of the sampled sequence, τ∈(0,1] is the time-domain compression factor, h(·) is the pulse shaping waveform function, t represents time, and T is the Nyquist symbol interval.

[0050] S30. Modulate K shaped signal sequences onto K different subcarriers, and rotate the symbol sequence on each subcarrier by an initial phase using different first phase rotation components to obtain K subcarrier signals.

[0051] In step S30, K shaped signal sequences are modulated onto K different subcarriers. There are multiple ways to rotate the symbol sequence on each subcarrier by an initial phase using different first phase rotation components. Examples are given below.

[0052] For example, in one implementation, the first phase rotation components include K distinct components, and each of the K shaped signal sequences corresponds one-to-one with one of the K first phase rotation components. Accordingly, step S30 modulates the K shaped signal sequences onto K different subcarriers, and rotates the symbol sequence on each subcarrier by an initial phase using the different first phase rotation components, including:

[0053] Each shaped signal sequence is multiplied by its corresponding first phase rotation component, thereby modulating the shaped signal sequence onto a subcarrier; thus, K shaped signal sequences are modulated onto K different subcarriers respectively, resulting in K subcarrier signals.

[0054] In another implementation, the first phase rotation component includes K groups, each group including N first phase rotation components. The K×N first phase rotation components are all different. K shaped signal sequences correspond one-to-one with the K groups of first phase rotation components. Each group of first phase rotation components corresponding to a shaped signal sequence corresponds one-to-one with the N symbols in that shaped signal sequence. Accordingly, step S30 modulates the K shaped signal sequences onto K different subcarriers, and rotates the symbol sequence on each subcarrier by an initial phase using different first phase rotation components, including:

[0055] For each shaped signal sequence, a set of first phase rotation components corresponding one-to-one with the symbols in the shaped signal sequence are obtained. Each symbol in the shaped signal sequence is multiplied by the corresponding first phase rotation component, thereby modulating the shaped signal sequence onto a subcarrier. Thus, K shaped signal sequences are modulated onto K different subcarriers to obtain K subcarrier signals. The set of first phase rotation components corresponding to different shaped signal sequences are different.

[0056] In this embodiment of the invention, the first phase rotation component is represented as: The subcarrier signal obtained after the shaped signal sequence is modulated onto the subcarrier is represented as follows:

[0057] Where e is the natural base, j is the imaginary part, π is pi, k = [0, 1, ..., K-1], φ ∈ (0, 1] is the frequency domain compression factor, F = 1 / T is the frequency domain spacing of the subcarriers under the condition of orthogonality, T is the symbol spacing of Nyquist transmission, and t represents time. For example, if K = 64 and T = 1, then γk =64k (k=0,1,…,K-1).

[0058] Therefore, the signal sequence composed of the K subcarrier signals obtained in step S30 can be represented as:

[0059] S40. Divide the K subcarrier signals into U groups, multiply the subcarrier signals of the uth group (u = [1,2,...,U]) by the corresponding second phase rotation component, and then superimpose all the subcarrier signals after multiplying by the second phase rotation component to obtain the signal with reduced PAPR.

[0060] There are several specific ways to divide the K subcarrier signals into U groups. For example, the K subcarrier signals can be divided into U groups equally. Alternatively, in a preferred implementation, dividing the K subcarrier signals into U groups can include:

[0061] (1) Determine the number of subcarrier signals in each group according to the following formula:

[0062] Among them, P u This represents the number of subcarrier signals in the u-th subcarrier group. Therefore, the number of subcarrier signals in the u=1-th group is: The subcarrier signals it contains are numbered as follows: The number of subcarriers in the u=1 group is The subcarrier signals it contains are numbered as follows:

[0063] (2) Divide the K subcarrier signals into U groups according to the number of subcarrier signals in each group.

[0064] In the above grouping methods, there are no restrictions on the specific value of U, as long as it is an integer greater than 1.

[0065] In this embodiment of the invention, the second phase rotation component includes U components, and these U second phase rotation components correspond one-to-one with the U groups into which the K subcarriers are divided; wherein, the second phase rotation component corresponding to the u-th group of subcarrier signals is represented as... here, This refers to a set of angles pre-selected for the u-th subcarrier signal. For example, for BPSK modulation, when U = 4, angles can be selected for the u-th subcarrier signal. Of course, this is not the only option. In practice, the same or different subcarrier signals can be selected for each group based on the measured results.

[0066] In step S40, the signal sequence obtained by multiplying the k-th subcarrier signal by the corresponding second phase rotation component can be represented as:

[0067] Then, the subcarrier signals within the same group are superimposed, and the U signal sequences formed by superimposing each group are then superimposed. The resulting signal with reduced PAPR can be expressed as:

[0068] S50: Perform peak clipping on the PAPR-reduced signal to obtain a signal with further reduced PAPR.

[0069] Peak clipping technology reduces the signal's peak power (PAPR) to lower the signal's peak power. This is achieved by limiting the signal before it passes through a nonlinear component, causing the peak signal level to fall below the desired maximum value. Specifically, in this embodiment of the invention, the PAPR-reduced signal obtained in step S40 can be multiplied by a rectangular filter to flatten waveforms above the peak clipping threshold.

[0070] Preferably, the peak reduction threshold can be calculated using the following formula:

[0071] Among them, A th The peak-to-average power ratio (PAPR) represents the peak-to-average power ratio (PAPR) of the signal that is expected to be achieved after peak clipping. Its value can be set according to the requirements of the actual application scenario.

[0072] In step S50, the PAPR-reduced signal s ig The peak-shaving process for (t) can be represented as:

[0073] Where ∠(·) represents the angle of the input complex number, s MFTN (t) indicates a signal that PAPR is further reduced.

[0074] Based on the process shown in steps S10 to S50, Figure 2 illustrates a modular implementation of an embodiment of the present invention, wherein the operation in step S30 and the operation in step S40 of dividing the K subcarrier signals into U groups and multiplying them by the second phase rotation component are encapsulated into an IPR-GPR module.

[0075] In the method for reducing PAPR in a multi-carrier super Nyquist system provided in this invention embodiment, K shaped signal sequences are first modulated onto K different subcarriers. Different first phase rotation components are used to rotate the symbol sequence on each subcarrier by an initial phase, which to some extent avoids the probability of large peaks caused by all subcarriers having completely identical initial phases. Then, the subcarrier signals are grouped, and each group of subcarrier signals is multiplied by a corresponding second phase rotation component. Finally, all subcarrier signals multiplied by the second phase rotation component are superimposed to further reduce the probability of large peaks in the superimposed signal. Specifically, the inventors discovered that when the number of subcarriers is large, executing step S30 results in an insufficient phase rotation for each subcarrier, leading to insufficient phase rotation angles for the symbols on the subcarriers. This results in a high probability of peak-to-peak superposition causing large peak power points. To solve this problem, this invention uses the operation in step S40 to control each group of subcarriers to be given a large phase rotation factor, thus avoiding peak-to-peak superposition. Simultaneously, fewer groups result in greater distances between the given multiple phase rotation factors, leading to a larger symbol phase rotation angle and allowing for more flexible control over the reduction of the PAPR signal. Finally, based on the superimposed signal obtained in step S40, this embodiment of the invention performs further peak clipping on the PAPR-reduced signal. Compared to the prior art's direct peak clipping operation to reduce PAPR, this effectively reduces system performance loss. Therefore, through the above processing flow, this embodiment of the invention can significantly reduce the PAPR of a multi-carrier FTN system with minimal performance loss.

[0076] In one embodiment, the method shown in FIG1 can be applied to a transmitting end (e.g., a communication transmitter). Therefore, the method provided by this embodiment of the invention may further include: transmitting a signal with a further reduced PAPR obtained in step S50. It is understood that, specifically, the transmitting end transmits this signal with a further reduced PAPR as a transmitting end signal into the channel so that the receiving end (e.g., a communication receiver) can receive it.

[0077] In one embodiment, the method provided by the present invention may further include: receiving a signal with a further reduced PAPR at the receiving end to obtain a received signal r. ig (t), and recover the source sequence from the received signal.

[0078] Specifically, the receiving end recovers the source sequence from the received signal, including the following steps:

[0079] (1) Multiply the received signal by U second negative phase rotation components to obtain U sub-signals; wherein the U second negative phase rotation components correspond one-to-one with the U second phase rotation components and are opposite in phase.

[0080] The received signal is represented as: r(t) = s MFTN (t)+ω(t);

[0081] In this formula, ω(t) is Gaussian white noise with a one-sided power spectral density of N0.

[0082] It is understandable that the U second phase rotation components By inverting the phase, we can obtain U second negative phase rotation components.

[0083] (2) For each sub-signal, multiply it by a corresponding set of first negative phase rotation components, so that U sub-signals multiplied by the first negative phase rotation components yield K recovered subcarrier signals; wherein, all first negative phase rotation components correspond one-to-one with all first phase rotation components and are in opposite phase.

[0084] Understandably, for each sub-signal, it is obtained by multiplying the received signal r(t) by a second negative phase rotation component. This second negative phase rotation component uniquely corresponds to a set of subcarriers, each of which corresponds to a first phase rotation component. By inverting the phases of these first phase rotation components, a set of first negative phase rotation components corresponding to the sub-signal can be obtained. The first negative phase rotation component is represented as...

[0085] (3) Matched filtering, downsampling, signal detection and decoding are performed on the K recovered subcarrier signals in sequence to obtain the recovered source sequence.

[0086] Specifically, after sequentially performing matched filtering and downsampling on the K recovered subcarrier signals, K symbol sequences are obtained. These K symbol sequences are then concatenated together (parallel-to-serial conversion) to obtain a long symbol sequence. This symbol sequence is then input into the signal detection and decoding module to output the recovered source sequence. The recovered source sequence is represented as follows:

[0087] The method for reducing PAPR in a carrier super Nyquist system provided in this embodiment of the invention reduces the PAPR of the transmitted signal at the transmitting end using the manner shown in steps S10 to S50, and then recovers the source sequence at the receiving end using the corresponding method. This method can effectively recover the source sequence at the receiving end without reducing system performance loss, and does not require the power amplifier at the transmitting end to have a large power back-off, thereby reducing the nonlinear distortion of the transmitting signal.

[0088] To further illustrate the beneficial effects of the present invention, a comparative analysis is conducted below using simulation experiments.

[0089] The simulation parameters of this invention embodiment are shown in Table 1:

[0090] Table 1

[0091] In addition, to compare and verify the beneficial effects of the embodiments of the present invention, a simulation was performed on an existing OFDM system, and the simulation parameters are shown in Table 2:

[0092] Table 2

[0093] Figure 3 compares the PAPR of a multi-carrier FTN system (referred to as the "MFTN IPR-GPR" system) and an existing OFDM system when PAPR statistics are performed using CCDF, under the condition of consistent spectral efficiency. The simulation results in Figure 3 show that when PAPR statistics are performed using CCDF, the PAPR is reduced using steps S10-S40 of this invention. -3 The PAPR of the multi-carrier FTN system using the method of this invention is reduced by 1 dB compared with that of the OFDM system.

[0094] Figure 4 compares the PAPR of a multi-carrier FTN system (referred to as the "MFTN IPR-GPR-peak clipping" system) and an existing OFDM system when PAPR statistics are performed using CCDF and steps S10-S50 of this invention. As shown in Figure 4, the simulation results indicate that the PAPR of the "MFTN IPR-GPR-peak clipping" system in this invention is reduced by 4 dB compared to the OFDM system.

[0095] Figure 5 shows the frame error rate (BLER) of the "MFTN IPR-GPR-peak clipping" system (labeled "MFTN" in Figure 5) and the existing OFDM system as a function of bit signal-to-noise ratio (BNR) under different (τ, φ, β) conditions. bThe comparison chart shows the changes in PAPR (parameters / N0). As can be seen from the simulation results in Figure 5, under the condition of consistent spectral efficiency, the PAPR of the "MFTN IPR-GPR-peak clipping" system in this invention is reduced by approximately 4 dB. When the parameters are selected as τ = 1, φ = 0.95, and β = 0.05, the BLER performance loss is only 0.4 dB compared to the OFDM system, which is relatively small. Furthermore, the simulation results in Figure 5 show that when the system is not compressed in the time domain, the BLER performance loss of the "MFTN IPR-GPR-peak clipping" system in this invention is small. When the system is compressed in the time domain, although the spectral efficiency and other parameters are approximately the same and PAPR can still be reduced, the BLER performance of the system suffers a relatively large loss. Therefore, under the condition of consistent spectral efficiency, it is best to use parameters that are not compressed in the time domain to reduce the system's PAPR, thus ensuring the system's BLER performance.

[0096] It should be noted that the terms "first," "second," etc., 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. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention.

[0097] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0098] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings and the disclosure in carrying out the claimed invention. In the description of the invention, the word "comprising" does not exclude other components or steps, "a" or "an" does not exclude a plurality, and "a plurality" means two or more, unless otherwise explicitly specified. Furthermore, while different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0099] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

A method for reducing PAPR in a multi-carrier super Nyquist system, characterized in that, include: The source sequence is sequentially encoded, interleaved, mapped by constellation, and converted from serial to parallel to obtain K subsequences; The K subsequences are upsampled and pulse-shaped sequentially to obtain K shaped signal sequences; The K shaped signal sequences are modulated onto K different subcarriers, and the symbol sequence on each subcarrier is rotated by an initial phase using different first phase rotation components to obtain K subcarrier signals; The K subcarrier signals are divided into U groups. The subcarrier signals of the uth group (u = [1,2,...,U]) are multiplied by the corresponding second phase rotation component. Then, all the subcarrier signals multiplied by the second phase rotation component are superimposed to obtain the signal with reduced PAPR. The PAPR-reduced signal is then subjected to peak clipping to obtain a signal with further reduced PAPR. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 1 is characterized in that, The method further includes sending a signal that the PAPR is further reduced. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 2 is characterized in that, The method further includes: receiving a signal with a further reduced PAPR at the receiving end to obtain a received signal, and recovering the source sequence from the received signal. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 3 is characterized in that, The receiving end recovers the source sequence from the received signal, including: The received signal is multiplied by U second negative phase rotation components to obtain U sub-signals; wherein each of the U second negative phase rotation components corresponds to one of the U second phase rotation components and is in opposite phase. For each sub-signal, it is multiplied by a corresponding set of first negative phase rotation components, so that U sub-signals multiplied by the first negative phase rotation components yield K recovered subcarrier signals; wherein, all the first negative phase rotation components correspond one-to-one with all the first phase rotation components, and their phases are opposite. The K recovered subcarrier signals are sequentially subjected to matched filtering, downsampling, signal detection, and decoding to obtain the recovered source sequence. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 1 is characterized in that, The step of modulating the K shaped signal sequences onto K different subcarriers and rotating the symbol sequence on each subcarrier by an initial phase using different first phase rotation components includes: For each shaped signal sequence, a set of first phase rotation components corresponding one-to-one with the symbols in the shaped signal sequence are obtained, and each symbol in the shaped signal sequence is multiplied by the corresponding first phase rotation component. Among them, the first phase rotation components corresponding to different shaping signal sequences are different. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 1 is characterized in that, The first phase rotation component is represented as: Where e is the natural base, j is the imaginary part, π is pi, k = [0, 1, ..., K-1], φ ∈ (0, 1] is the frequency domain compression factor, F = 1 / T is the frequency domain spacing of the subcarriers satisfying the orthogonality condition, and T is the symbol spacing of Nyquist transmission. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 1 is characterized in that, The step of dividing the K subcarrier signals into U groups includes: The number of subcarrier signals in each group is determined using the following formula: Among them, P u This represents the number of subcarrier signals in the u-th group; Based on the determined number of subcarrier signals in each group, the K subcarrier signals are divided into U groups. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 7 is characterized in that, The second phase rotation component corresponding to the uth subcarrier signal is: Where e is the natural base and j is the imaginary part. For each set of angles pre-selected for the u-th subcarrier signal. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 1 is characterized in that, Peak clipping processing is performed on the PAPR-reduced signal, including: The PAPR-reduced signal is multiplied by a rectangular filter to flatten the waveform above the clipping threshold in the signal. The method for reducing PAPR in a multi-carrier super Nyquist system according to claim 9 is characterized in that, The peak reduction threshold is calculated using the following formula: Among them, A th The peak clipping threshold is represented by PAPR, which represents the peak-to-average power ratio of the signal that is expected to be achieved after the signal with PAPR reduced by the peak clipping process.

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