OFDM (Orthogonal Frequency Division Multiplexing) signal modulation method, modulation device, computing equipment and chip system

Abstract

The invention provides an OFDM (Orthogonal Frequency Division Multiplexing) signal modulation method, a modulation device, computing equipment, a computer readable storage medium, a computer program product and a chip system for the computing equipment. The OFDM signal modulation method comprises the steps that first OFDM signal navigation is acquired, a first OFDM signal comprises frequency domain signals of M * N ranging code signals, M represents the number of symbols of the first OFDM signal, N represents the number of subcarriers of the first OFDM signal, and M and N are positive integers; performing phase hopping modulation on the first OFDM signal by taking a subcarrier as a unit to obtain a second OFDM signal; and performing frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal. According to the embodiment of the invention, the modulation method of the OFDM signal can reduce the peak-to-average power ratio of the OFDM signal, can effectively improve the peak-to-average power ratio performance of the OFDM signal, and improves the safety of the OFDM signal.

Description

Technical Field

[0001] The present disclosure relates to the field of satellite communications, and in particular to an OFDM signal modulation method, a modulation device, a computing device, a computer storage medium, a computer program product, and a chip system for a computing device. Background Art

[0002] Low Earth Orbit (LEO) satellites have the characteristics of strong signal landing power and fast geometric changes. They have significant advantages in application fields such as anti-interference and fast high-precision positioning. They are the current development hotspot in the navigation field and an important part of the future integrated PNT (Positioning, Navigation and Timing). Traditional medium and high orbit satellite navigation signals usually broadcast direct sequence spread spectrum signals. However, low-orbit satellite constellations are usually communication constellations, and navigation functions are realized by communication and navigation fusion. Orthogonal frequency division multiplexing (OFDM) is the mainstream signal modulation technology used in ground mobile communication systems represented by 5G. It has the characteristics of high spectrum efficiency. The navigation signal based on OFDM technology is quite competitive in the future communication and navigation fusion satellite system.

[0003] However, the existing OFDM signals still have the problem of too high Peak-to-Average Ratio (PAPR) and low security when used for navigation. Summary of the invention

[0004] It would be advantageous to provide a mechanism that mitigates, alleviates or eliminates at least one of the problems discussed above.

[0005] In a first aspect, a modulation method for an OFDM signal is provided. The method comprises: acquiring a first OFDM signal, the first OFDM signal comprising M×N ranging codes, wherein M represents the number of symbols of the first OFDM signal, and N represents the number of subcarriers of the first OFDM signal, wherein M and N are both positive integers; performing phase hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal; and performing frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal.

[0006] In a second aspect, a modulation device for an OFDM signal is provided. The modulation device includes: a signal acquisition module, used to acquire a first OFDM signal, the first OFDM signal includes M*N ranging codes, wherein M represents the number of symbols of the first OFDM signal, and N represents the number of subcarriers of the first OFDM signal, wherein M and N are both positive integers; a phase-hopping modulation module, used to perform phase-hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal; and a frequency-hopping modulation module, used to perform frequency-hopping modulation on the second OFDM signal to obtain a third OFDM signal.

[0007] In a third aspect, a computing device is provided, comprising: at least one processor; and at least one memory storing instructions, wherein when the instructions are executed by the at least one processor individually or collectively, the computing device executes the above method.

[0008] In a fourth aspect, a computer storage medium is provided, on which instructions are stored, which, when executed individually or collectively by at least one processor of a computing device, cause the computing device to perform the above method.

[0009] In a fifth aspect, a computer program product is provided, comprising instructions, which, when executed individually or collectively by at least one processor of a computing device, cause the computing device to perform the above method.

[0010] In a sixth aspect, a chip system for a computing device is provided, the chip system comprising at least one processor, the at least one processor being configured to individually or collectively execute instructions stored in at least one memory of the computing device so that the computing device performs the above-mentioned method.

[0011] It should be understood that the invention summary is not intended to identify the key or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of some embodiments of the present disclosure in the accompanying drawings, in which: Figure 1 An exemplary flow chart of a modulation method of an OFDM signal in which an embodiment of the present disclosure can be implemented is shown; Figure 2 A schematic diagram of the signal structure of an OFDM navigation signal according to an embodiment of the present disclosure is shown; Figure 3A schematic diagram showing a modulation method according to an embodiment of the present disclosure using a frequency hopping sequence to perform frequency hopping modulation; Figure 4 A schematic diagram showing a subcarrier change after frequency hopping according to a modulation method of an embodiment of the present disclosure; Figure 5 A schematic diagram showing a peak-to-average power ratio judgment in a modulation method according to an embodiment of the present disclosure is shown; Figure 6 A schematic diagram showing a peak-to-average power ratio performance comparison result of an exemplary embodiment of a modulation method disclosed herein is shown; Figure 7 A schematic diagram showing a comparison of peak-to-average power ratio performance under different subcarrier numbers of an exemplary embodiment of a modulation method disclosed herein is shown; Figure 8 A schematic diagram showing a demodulation gain against non-cooperative parties according to an exemplary embodiment of a modulation method disclosed herein; Fig. 9 An exemplary block diagram of a modulation device according to an embodiment of the present disclosure is shown; Figure 10~Figure 12 Schematic diagrams of the process of signal modulation performed by a modulation device according to an embodiment of the present disclosure are respectively shown; Fig.13 A computing device suitable for implementing exemplary embodiments of the modulation methods of the present disclosure is shown. DETAILED DESCRIPTION

[0013] The principle of the present disclosure will now be described with reference to some embodiments. It should be understood that the description of these embodiments is only for illustrative purposes, and helps those skilled in the art to understand and implement the present disclosure, without any limitation to the scope of the present disclosure. The disclosure described herein can be implemented in a manner different from that described below.

[0014] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0015] References in this disclosure to "one embodiment," "an embodiment," "an exemplary embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in conjunction with an exemplary embodiment, whether or not explicitly described, those skilled in the art will recognize that such feature, structure, or characteristic affects incorporation into other embodiments.

[0016] It should be understood that although the terms "first" and "second" etc. may be used to describe various elements herein, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the exemplary embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term "and / or" as used herein includes any and all combinations of one or more of the listed terms.

[0017] The terms used herein are only for describing specific embodiments, rather than for limiting exemplary embodiments. The singular forms "one", "an", and "the" used herein also include plural forms, unless the context clearly indicates otherwise. "A group of elements" or "element set" used herein is intended to include one or more elements. It should also be understood that the terms "include", "comprise", "have", "have", "include" and / or "include", when used herein, specify the presence of the features, elements and / or parts, etc., but do not exclude the presence or addition of one or more other features, elements, parts and / or combinations thereof.

[0018] The existing OFDM signal has a problem of too high peak-to-average power ratio when used for navigation. When the peak-to-average power ratio is too high, the OFDM signal is susceptible to nonlinear distortion, which reduces the measurement performance of the signal. In addition, the existing OFDM signal has a problem of low security when used for navigation. Since civil navigation signals cannot be implemented using complex encryption codes, directly using existing OFDM signals for navigation also faces security risks.

[0019] In response to the problem of excessively high peak-to-average power ratio and low security of OFDM signals when used for navigation, the present disclosure proposes an OFDM modulation method with low peak-to-average power ratio that can be used for communication and navigation fusion satellites. This modulation method adds frequency hopping modulation to change the index order of subcarriers on the basis of phase hopping modulation, which can reduce the signal peak-to-average power ratio to a certain extent while reducing the amount of sideband information transmission, and is beneficial to improving the signal security performance. According to the modulation method of the present disclosure, the peak-to-average power ratio of the OFDM signal is significantly reduced compared to the original OFDM signal, and the more subcarriers there are, the greater the improvement in the peak-to-average power ratio. In addition, the modulation method based on the present disclosure makes the demodulation gain of the OFDM signal against non-cooperative parties larger, indicating that this method can greatly improve the security of the signal.

[0020] The principles and implementations of the present disclosure will be described in detail below with reference to embodiments.

[0021] Figure 1 FIG. 1 is an exemplary flow chart of a modulation method 100 for an OFDM signal according to an embodiment of the present disclosure. Figure 1 As shown, the modulation method 100 of the OFDM signal of this embodiment includes: Step S110: Acquire a first OFDM signal navigation, where the first OFDM signal includes M×N ranging codes, where M represents the number of symbols of the first OFDM signal, and N represents the number of subcarriers of the first OFDM signal, where both M and N are positive integers; Step S120: performing phase hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal; and Step S130: performing frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal.

[0022] By adopting the modulation method 100 of the OFDM signal disclosed in the present invention, the peak-to-average power ratio of the OFDM signal can be reduced and the signal security can be improved by sequentially performing phase hopping modulation and frequency hopping modulation on the OFDM signal.

[0023] The following describes steps S110 to S130 in the modulation method 100 in detail with reference to the accompanying drawings.

[0024] In step S110, the first OFDM signal includes M×N ranging codes. It should be noted that M and N are both positive integers, and the specific values ​​of M and N are related to the structure of the OFDM signal. The present disclosure does not limit the specific values ​​of M and N. In some embodiments, N is first determined according to the number of subcarriers of the first OFDM signal, and then the length M×N of the ranging code is determined, and then the size of M can be determined.

[0025] Figure 2 FIG. 4 shows the time-frequency structure of the first OFDM signal obtained in the modulation method of an embodiment of the present disclosure. Figure 2 As shown in FIG. 1 , the horizontal axis is the OFDM symbol and the vertical axis is the OFDM subcarrier. Figure 2 As shown, the ranging code is divided into M segments on the horizontal axis, and each segment is placed on an OFDM symbol in the subcarrier index order of [1, N]. The M×N ranging codes are numbered 0, 1, 2, ..., M×N-1. Figure 2 Each rectangular block represents a ranging code, or "chip". It can be expressed as: ranging code [i], i = 0 ~ M × N-1.

[0026] After the first OFDM signal is acquired in step S110, step S120 is executed: performing phase hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal.

[0027] In some embodiments, step S120 includes: Step S1211: obtaining a ranging code sequence corresponding to a current symbol in the first OFDM signal, wherein the ranging code sequence includes N ranging codes; and Step S1212: changing the subcarrier phase of each ranging code in the ranging code sequence according to the random phase matrix to obtain a second OFDM signal, wherein the random phase matrix includes N random phases.

[0028] In some embodiments, obtaining the ranging code sequence corresponding to the current symbol in the first OFDM signal in step S121 is to select N ranging codes from M×N ranging codes as the ranging code sequence corresponding to the current symbol.

[0029] In some embodiments, formula (1) is used to represent the ranging code sequence corresponding to the current symbol obtained in step S121: (1) Wherein, C represents the discrete signal vector corresponding to N ranging codes, C[i] represents the frequency domain discrete signal corresponding to the i-th ranging code, i = 0 ~ N-1. C[i] can also be called the ranging code value corresponding to the i-th ranging code.

[0030] In some embodiments, the first OFDM signal obtained by directly modulating the N ranging codes based on the current symbol onto the subcarrier can be expressed by formula (2): (2) Wherein, s[k] is the first OFDM signal obtained by directly performing OFDM modulation on N ranging code values ​​C[0], C[1], ..., C[N-1]. In some embodiments, the OFDM signal s[k] is directly implemented by using an inverse Fourier transform (IFFT) on C[0], C[1], ..., C[N-1]. It can be understood that C[i] is the time domain signal on the i+1th OFDM subcarrier. s[k] is the time domain signal of all N subcarrier signals superimposed after c[i] is OFDM modulated.

[0031] In some embodiments, the ranging code sequence corresponding to each symbol in the first OFDM signal is obtained in sequence, and phase-hopping modulation is performed. That is, N ranging codes are selected from the ranging codes in sequence according to the above method, and these N ranging codes correspond to the ranging code sequence of one OFDM symbol. The N ranging codes will be used as the original frequency domain discrete signal vector of the first OFDM signal in sequence for the phase-hopping modulation in step S120. For example: the 0th to N-1th ranging code modulation is selected for the first time, the Nth to 2N-1th ranging code modulation is selected for the second time, and so on, until the (M-1)×Nth to M×N-1th ranging code modulation is selected for the M-1th time. In this way, N ranging codes are selected each time for phase-hopping modulation, and a total of M times are selected.

[0032] After obtaining the ranging code sequence corresponding to the current symbol in the first OFDM signal in step S1211, step S1212 is performed: changing the subcarrier phase of each ranging code in the ranging code sequence according to the random phase matrix to obtain a second OFDM signal, wherein the random phase matrix includes N random phases.

[0033] The phase hopping modulation in step S120 actually means that the phase is jumped on each subcarrier. In some embodiments, the phase hopping modulation includes: randomly generating N phase values ​​and modulating them to N ranging codes, that is, adding a phase to each ranging code, thereby achieving phase hopping for each ranging code. For example, suppose the discrete phase vector used for phase hopping on an OFDM symbol is Then the second OFDM signal obtained in step S120 can be expressed by formula (3): (3) in, represents a phase-hopping signal, that is, the second OFDM signal.

[0034] Need to explain, First, random phases are added to the ranging code C[i] , that is, after the phase jump, OFDM modulation is performed to obtain a second OFDM signal after phase hopping.

[0035] In some embodiments, the random phase matrix in step S1212 includes K×N random phases, where K represents the number of phase hopping paths, N represents the number of subcarriers of the OFDM navigation signal, and K and N are both positive integers. The number of paths K that need phase hopping can be determined as needed. In some embodiments, K≤M.

[0036] In some embodiments, the random phase matrix B is represented by the following formula (4) and formula (5): (4) (5) in, represents each row in the random phase matrix B, M represents the number of symbols of the first OFDM signal, Indicates random phase, n=0~N-1, . Elements in Random Phase . Each row of the random phase matrix B are a set of random phase sequences, forming a set of random phases .

[0037] In some embodiments, step S120 further includes: Step S1221: obtaining a ranging code sequence corresponding to a current symbol in the first OFDM signal, wherein the ranging code sequence includes N ranging codes; Step S1222: copy the ranging code sequence into K copies to obtain a ranging code sequence matrix, where K is a positive integer greater than or equal to 2; and Step S1223: Obtain K second OFDM signals according to the random phase matrix and the ranging code sequence matrix, wherein the random phase matrix includes K×N random phases.

[0038] In these embodiments, the purpose of copying the ranging code sequence into K copies in step S1222 is to facilitate the subsequent matrix dot multiplication operation. By multiplying the K copies of the ranging code sequence with the corresponding elements in the random phase matrix, the first OFDM signal can be phase-hopped to obtain K second OFDM signals.

[0039] In some embodiments, the ranging code sequence After K copies are made, the copied ranging code sequence is expressed by the following formula (6): (6) in, Represents the kth ranging code sequence, which includes K parts in total.

[0040] In some embodiments, changing the subcarrier phase of each ranging code in the ranging code sequence according to the random phase matrix to obtain the second OFDM signal in step S1212 includes: performing a point multiplication of the ranging code sequence with the random phase matrix to obtain the second OFDM signal.

[0041] In some embodiments, the following formula (7) is used to express the ranging code sequence after replication according to the random phase matrix B: Perform phase-hopping modulation to obtain phase-hopping signal : (7) in, Represents the kth phase-jump signal.

[0042] Formula (7) shows that the random phase in the random phase matrix B can be transformed into Append to each ranging code in the ranging code sequence to obtain a phase-hopping signal Among them, each ranging code after phase hopping can be expressed as: .

[0043] The modulation method disclosed in the present invention performs frequency hopping modulation on the second OFDM signal in step S130 to obtain a third OFDM signal. Figure 3It represents the process of generating the frequency hopping sequence H[i] for controlling the frequency hopping of OFDM signal. Figure 3 As shown, the ranging code [i] becomes the ranging code [H[i] after frequency hopping under the control of the frequency hopping sequence H. The second OFDM signal is subjected to frequency hopping modulation, and the obtained third OFDM signal can be expressed by formula (8): (8) in, .

[0044] In some embodiments, the frequency hopping sequence H is a set of numbers obtained by randomly reordering the N integers 0, 1, 2 ... N-1. That is, the frequency hopping sequence H includes the N integers 0, 1, 2 ... N-1 that are randomly distributed. The frequency hopping sequence H can be used to adjust the order of the N ranging codes in the phase hopping signal to achieve the effect of frequency hopping, that is, to achieve phase hopping frequency hopping.

[0045] This disclosure is Figure 3 The process shown will be N ranging codes after phase hopping , i=0~N-1 becomes the frequency hopping sequence under the control of frequency hopping sequence H , i=0~N-1.

[0046] The following example illustrates a frequency hopping process: Assume that N=5, that is, the first OFDM signal has 5 subcarriers. The 5 ranging code values ​​obtained after the phase hopping in step S120 are: , , , , If OFDM modulation is performed directly, we can get ,in, Modulated onto the first subcarrier of OFDM, Modulated onto the second subcarrier of OFDM, Modulated onto the third subcarrier of OFDM, Modulated onto the 4th subcarrier of OFDM, Modulated onto the 5th subcarrier of OFDM.

[0047] Assuming frequency hopping sequence . Using this frequency hopping sequence After frequency hopping, the five ranging code values ​​become ,Right now , , , , . After OFDM modulation, it becomes Modulated onto the first subcarrier of OFDM, Modulated onto the second subcarrier of OFDM, Modulated onto the third subcarrier of OFDM, Modulated onto the 4th subcarrier of OFDM, It is modulated onto the fifth subcarrier of OFDM, thus achieving frequency hopping.

[0048] Figure 4 The schematic diagram of the change of subcarriers of the 1st to 5th original ranging code sequences before and after the frequency hopping in the above example is shown. Figure 4 In the figure, the horizontal axis is frequency and the vertical axis is power spectrum density. The upper figure shows the power spectrum density distribution before frequency hopping, and the lower figure shows the power spectrum density distribution after frequency hopping. Figure 4 As shown, the frequencies of the subcarriers at the corresponding positions of the original ranging code sequence change before and after the frequency hopping. For example, the frequency of the fifth subcarrier changes to the frequency position of the original first subcarrier, while the power spectrum density does not change.

[0049] In some embodiments, performing frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal in step S130 includes: changing the subcarrier sequence number of each ranging code in the second OFDM signal according to a frequency selection matrix to obtain the third OFDM signal, wherein the frequency selection matrix includes N non-repeating random integers.

[0050] In some embodiments, the frequency selection matrix includes F×N random numbers, where F represents the number of frequency hopping paths, N represents the number of subcarriers of the OFDM navigation signal, and both F and N are positive integers.

[0051] In some embodiments, the frequency selection matrix R is represented by the following formula (9): (9) Among them, each row of the matrix can be expressed as: (10) in, for The random number in the same row No repetition.

[0052] In some embodiments, the frequency selection matrix R is consistent with the frequency hopping sequence described above. Correspondingly. Each row of the frequency selection matrix R includes N numbers, which are a set of frequency hopping sequences, that is, a set of numbers obtained by randomly adjusting the order of 0, 1, 2, ..., N-1. Its function is to adjust the order of the N ranging code symbols of the phase hopping signal after the phase hopping to achieve the effect of frequency hopping. Therefore, the N numbers in each row are not repeated.

[0053] In some embodiments, the frequency hopping in step S130 is to make the second OFDM signal obtained in step S120 follow The order is disrupted according to the rule, thereby obtaining a third OFDM signal.

[0054] In some embodiments, in order to obtain a phase-hopping signal with good randomness and reduce the peak-to-average power ratio of the signal, after obtaining K second OFDM signals, it also includes: calculating the balance of the K second OFDM signals to obtain the second OFDM signal with the best balance as the first target signal; copying the first target signal P times to obtain a first target signal matrix, where P is a positive integer.

[0055] According to this embodiment of the present disclosure, the second OFDM signal with the best balance is used as the first target signal, and the first target signal is made to enter the subsequent frequency hopping modulation step, which can better reduce the peak-to-average power ratio of the modulated OFDM signal.

[0056] In some embodiments, the balance of the second OFDM signal is calculated using the following formula (11): (11) in, is the ranging code of the aforementioned second OFDM signal, , K represents the number of phase jump paths, Indicates the balance parameter. The smaller the balance parameter, the greater the phase jump signal. The better the balance.

[0057] In some embodiments, the best balanced phase-hopping sequence is found among the K phase-hopping sequences, that is, The minimum phase-hopping sequence is taken as the target phase-hopping signal, which is recorded as: , and record the sequence index .

[0058] In some embodiments, step S130: performing frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal includes:

[0059] The subcarrier sequence number of each ranging code in the first target signal matrix is ​​changed according to the frequency selection matrix to obtain P third OFDM signals, wherein the frequency selection matrix includes P×N random integers, and the random integers in each row are not repeated.

[0060] In some embodiments, the following formula (12) and formula (13) are used to express that the first target signal is frequency-hop modulated according to the frequency selection matrix R to obtain the ranging code of the third OFDM signal: : (12) (13) in, represents the ranging code of the first target signal, is the ranging code of the index of the first target signal, Represents the ranging code of the p-th copy of the first target signal.

[0061] After the above frequency hopping steps, p ranging codes of the third OFDM signal can be obtained: , p=1~P.

[0062] Continuing the example of N=5 above, the first OFDM signal has 5 subcarriers. Before frequency hopping, ~ Modulate to OFDM subcarrier 1 to subcarrier 5. Assume that each line in the frequency selection matrix R is: , according to the frequency selection matrix R, frequency hopping and then OFDM is performed, which is , , , , Modulated onto OFDM subcarrier 1 to subcarrier 5 respectively.

[0063] In some embodiments, after obtaining the third OFDM signal, the method further includes: Calculate the peak-to-average power ratios of P third OFDM signals, and use the third OFDM signal with the lowest peak-to-average power ratio as the second target signal; In this embodiment of the present disclosure, calculating the peak-to-average power ratios of P third OFDM signals and selecting the third OFDM signal with the lowest peak-to-average power ratio as the second target signal for modulation can further reduce the peak-to-average power ratio of the signal and improve the security of the signal.

[0064] Figure 5 A schematic diagram of a peak-to-average power ratio determination process according to an embodiment of the present disclosure is shown. Figure 5 A PAPR determination unit 510 is shown in FIG. 5 , which is used to calculate P third OFDM signal ranging codes respectively. The peak-to-average power ratio. Figure 5 As shown, the above P third OFDM signal ranging codes Input to the PAPR determination unit 510, each channel number third OFDM signal ranging code All of them correspond to input into an IFFT unit for OFDM modulation. After modulation, the signal with the smallest PAPR is selected from all the modulated signals as the final desired second target signal ranging code. ,in represents the index of the third OFDM signal with the minimum PAPR.

[0065] According to the modulation method of the above embodiment, on the one hand, after phase hopping, the phase hopping signal with the best balance, i.e., the first target signal, is selected, which increases randomness and is conducive to reducing the peak-to-average power ratio; on the other hand, after frequency hopping, the third OFDM signal with the lowest peak-to-average power ratio is selected as the second target signal, which further reduces the peak-to-average power ratio. In addition, compared with the existing security improvement methods, the modulation method disclosed in the present invention can cleverly combine the structure and generation characteristics of OFDM signals, can be applied to OFDM signals and effectively improve the security of OFDM navigation signals.

[0066] It should be understood that the modulation method disclosed in the present invention can also perform frequency hopping modulation first and then phase hopping modulation in principle. However, in this case, the frequency hopping sequence and phase hopping sequence with the smallest peak-to-average power ratio need to be selected each time. According to the method of first phase hopping and then frequency hopping in the embodiment of the present invention, the phase hopping sequence is optimized for balance, and the frequency hopping sequence is optimized for peak-to-average power ratio, thus avoiding the cumbersomeness of the process.

[0067] Figure 6 , Figure 7 , Figure 8 The schematic diagrams respectively show the effect of applying the modulation method of an embodiment of the present disclosure. Figure 6 The peak-to-average power ratio performance comparison results based on the modulation method disclosed in the present invention are shown. Figure 6 As shown, the horizontal axis represents the peak-to-average power ratio PAPR0, in db; the vertical axis represents the complementary cumulative distribution function CCDF of the peak-to-average power ratio, that is, the probability that PAPR is greater than PAPR0. The different curves represent the OFDM signal, FH-OFDM signal and PH-FH-OFDM signal, namely: the original OFDM signal (the first OFDM signal), the OFDM signal with frequency hopping only, and the OFDM signal after phase-hopping and frequency-hopping modulation (the third OFDM signal). The number of subcarriers N=64. From Figure 6 It can be clearly seen that the PAPR CCDF performance of the PH-FH-OFDM signal (the third OFDM signal) is optimal, and the probability of the peak-to-average ratio being greater than 8.8 dB is close to 0, which is significantly improved compared to the FH-OFDM signal and the original OFDM signal.

[0068] Figure 7 The peak-to-average power ratio performance under different subcarrier numbers of the modulation method based on the present disclosure is shown, wherein the number of phase-hopping PH branches and the number of frequency-hopping FH branches are both 4. Figure 7 The horizontal and vertical axes are Figure 6 Same. Reference Figure 7As shown in the figure, when the peak-to-average power ratio of the horizontal axis is 6dB, the vertical axis of the subcarrier number N=1024 is smaller than that of N=256. In other words, the probability of the peak-to-average power ratio being greater than 6dB when N=1024 is smaller than that of N=256, which means that the peak-to-average power ratio of N=1024 is smaller than that of N=256. Figure 7 The further to the left the curve is, the better the peak-to-average power ratio performance is. Figure 7 It is shown that, based on the modulation method disclosed in the present invention, the more subcarriers there are, the greater the improvement in peak-to-average power ratio performance.

[0069] Figure 8 FIG. 2 is a schematic diagram showing the demodulation gain against non-cooperative parties based on the modulation method disclosed in the present invention. The horizontal axis represents the multi-phase jump phase N', and the vertical axis represents the demodulation gain against non-cooperative parties. Figure 8 As shown, the larger the N' is, the larger the demodulation gain against non-cooperative parties is, indicating that the signal is more difficult to be correctly demodulated and the better the signal security is. For cooperative parties, knowing the phase-hopping frequency modulation sequence can effectively demodulate the signal, while for non-cooperative parties, the phase-hopping frequency modulation sequence cannot be obtained and it is difficult to correctly demodulate the signal. Therefore, the phase-hopping frequency hopping method disclosed in the present invention can greatly improve the security of the signal.

[0070] The present disclosure also provides a modulation device for an OFDM signal. Fig. 9 FIG. 7 shows a modulation device 700 of an embodiment of the present disclosure. The modulation device 700 can be used to perform the modulation method described above, but the present disclosure is not limited thereto. All the descriptions of the modulation method described above can be used to describe the modulation device 700 of the present disclosure. Fig. 9 As shown, the modulation device 700 of this embodiment includes a signal acquisition module 710, a phase-hopping modulation module 720 and a frequency-hopping modulation module 730. The signal acquisition module 710 is used to acquire a first OFDM signal, and the first OFDM signal includes M×N ranging codes, where M represents the number of symbols of the first OFDM signal, and N represents the number of subcarriers of the first OFDM signal, where M and N are both positive integers. The phase-hopping modulation module 720 is used to perform phase-hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal. The frequency-hopping modulation module 730 is used to perform frequency-hopping modulation on the second OFDM signal to obtain a third OFDM signal.

[0071] In some embodiments, the signal acquisition module 710, the phase-hopping modulation module 720 and the frequency-hopping modulation module 730 are respectively used to execute steps S110, S120 and S130 in the modulation method 100 described above.

[0072] In some embodiments, the modulation device 700 further includes a balance judgment unit 740, a peak-to-average power ratio judgment module 750, and a modulation unit 760. Among them, the balance judgment unit 740 is used to judge the balance of the phase-hopping signal, and obtain the first OFDM signal with the best balance as the first target signal. The frequency-hopping modulation module 730 is also used to perform frequency-hopping modulation on the first target signal according to the frequency selection matrix to obtain a third OFDM signal. The peak-to-average power ratio judgment module 750 is used to calculate the peak-to-average power ratio of the third OFDM signal, and obtain the third OFDM signal with the lowest peak-to-average power ratio as the second target signal. The modulation unit 760 is used to perform OFDM modulation on the second target signal.

[0073] Figure 10-12 Schematic diagrams of the flow of signal modulation performed by a modulation device according to an embodiment of the present disclosure are respectively shown. Fig.10 As shown, the original signal, that is, the ranging code sequence of the first OFDM signal, passes through the phase-hopping modulation module 720 and the frequency-hopping modulation module 730 in sequence to obtain an OFDM signal that has undergone phase-hopping and frequency-hopping, that is, the third OFDM signal in step S130.

[0074] In some embodiments, Fig.11 As shown, after the first OFDM signal passes through the phase-hopping modulation module 720, a second OFDM signal is obtained; and then the second OFDM signal passes through the balance judgment unit 740 to obtain the first target signal with the best balance. Fig.12 As shown, the first target signal is modulated by the frequency hopping modulation module 730 to obtain a third OFDM signal. Then, the peak-to-average power ratio determination module 750 is used to obtain a third OFDM signal with the lowest peak-to-average power ratio as the second target signal.

[0075] In some embodiments, the second target signal is input to Fig. 9 The modulation unit 760 shown in the figure obtains a modulated signal after OFDM modulation.

[0076] According to the modulation device of the above embodiment of the present disclosure, an OFDM modulation signal with low peak-to-average power ratio and high security can be obtained.

[0077] Fig.13 900 is a simplified block diagram of a device 900 suitable for implementing an embodiment of the present disclosure. For example, a modulation device can be implemented by the device 900. As shown in the figure, the device 900 includes one or more processors 910, one or more memories 920 coupled to the processor 910, and one or more communication modules 940 coupled to the processor 910.

[0078] The communication module 940 is used for two-way communication. The communication module 940 has at least one antenna to facilitate communication. The communication interface may represent any interface necessary for communicating with other network elements.

[0079] Processor 910 may be of any type suitable for the local technology network, and may include, as non-limiting examples, one or more of: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Device 900 may have multiple processors, such as application specific integrated circuit chips, which are driven in time to a clock that synchronizes a master processor.

[0080] The memory 920 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 924, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), and other magnetic and / or optical memories. Examples of volatile memories include, but are not limited to, random access memory (RAM) 922 and other volatile memories that do not persist during a power outage.

[0081] The computer program 930 includes computer executable instructions executed by the associated processor 910. The program 930 may be stored in the ROM 924. The processor 910 may perform any appropriate actions and processes by loading the program 930 into the RAM 922.

[0082] The embodiments of the present disclosure may be implemented by the program 930, so that the device 900 may perform any of the processes disclosed above. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0083] In some embodiments, the program 930 may be tangibly contained in a computer-readable medium, which may be contained in the device 900 (e.g., memory 920) or other storage devices accessible to the device 900. The device 900 may load the program 930 from the computer-readable medium to the RAM 922 for execution. The computer-readable medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. The program 930 is stored on the computer-readable medium.

[0084] Generally, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are shown and described as block diagrams, flow charts, or using some other graphical representations, it should be understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware or controllers or other computing devices, or some combination thereof.

[0085] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer executable instructions, such as instructions included in program modules, which are executed in a device on a target real or virtual processor to perform the above-mentioned reference Figure 1 The method 100 is described. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of program modules can be combined or separated between program modules as needed. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0086] The program code for executing the disclosed method can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing equipment so that when the program code is executed by the processor or controller, the function / operation specified in the flow chart and / or block diagram is realized. The program code can be executed completely on the machine as an independent software package, partially on the machine, partially on the machine, partially on a remote machine, partially on a remote machine, or all on a remote machine or server.

[0087] In the context of the present disclosure, computer program codes or related data may be carried by any appropriate carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of carriers include signals, computer readable media, etc.

[0088] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or apparatuses, or any suitable combination of the foregoing. Further examples of computer readable storage media include an electrical connection with one or more wires, a portable computer floppy disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0089] In addition, although the operations are described in a specific order, this should not be understood as requiring the specific order or sequence shown to be performed, or performing all the operations shown, to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these details should not be interpreted as limitations on the scope of the present disclosure, but can be interpreted as descriptions of features specific to a particular embodiment. Certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0090] Although the disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

[0091] It should be fully understood that the use of personally identifiable information should be subject to privacy policies and practices generally recognized as meeting or exceeding industry or government requirements for maintaining user privacy. In particular, personally identifiable information data should be managed and processed to minimize the risk of inadvertent or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

Claims

1. A modulation method for an OFDM signal, comprising: Acquire a first OFDM signal, where the first OFDM signal includes M×N ranging codes, where M represents the number of symbols of the first OFDM signal, and N represents the number of subcarriers of the first OFDM signal, where both M and N are positive integers; performing phase hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal; and Perform frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal.

2. The modulation method according to claim 1, characterized in that: The method of performing phase hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal includes: Obtaining a ranging code sequence corresponding to a current symbol in the first OFDM signal, wherein the ranging code sequence includes N ranging codes; and The subcarrier phase of each ranging code in the ranging code sequence is changed according to a random phase matrix to obtain the second OFDM signal, wherein the random phase matrix includes N random phases.

3. The modulation method according to claim 2, characterized in that: The method of changing the subcarrier phase of each ranging code in the ranging code sequence according to a random phase matrix to obtain the second OFDM signal includes: The random phase matrix is ​​point-multiplied by the ranging code sequence to obtain the second OFDM signal.

4. The modulation method according to claim 2 or 3, characterized in that: Also includes: The ranging code sequence corresponding to each symbol in the first OFDM signal is obtained in sequence, and the phase hopping modulation is performed.

5. The modulation method according to claim 1, characterized in that: Performing frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal includes: The subcarrier sequence number of each ranging code in the second OFDM signal is changed according to a frequency selection matrix to obtain the third OFDM signal, wherein the frequency selection matrix includes N non-repeating random integers.

6. The modulation method according to claim 1, characterized in that: The method of performing phase hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal includes: Obtaining a ranging code sequence corresponding to a current symbol in the first OFDM signal, wherein the ranging code sequence includes N ranging codes; Copy the ranging code sequence into K copies to obtain a ranging code sequence matrix, where K is a positive integer greater than or equal to 2; and K second OFDM signals are obtained according to a random phase matrix and the ranging code sequence matrix, wherein the random phase matrix includes K*N random phases.

7. The modulation method according to claim 6, characterized in that: After obtaining K second OFDM signals, the method further includes: Calculate the balance of K second OFDM signals, and obtain the second OFDM signal with the best balance as the first target signal; The first target signal is copied P times to obtain a first target signal matrix, where P is a positive integer.

8. The modulation method according to claim 7, characterized in that: Performing frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal includes: The subcarrier sequence number of each ranging code in the first target signal matrix is ​​changed according to a frequency selection matrix to obtain P third OFDM signals, wherein the frequency selection matrix includes P×N random integers, and the random integers in each row are not repeated.

9. The modulation method according to claim 8, characterized in that: Also includes: Calculating the peak-to-average power ratios of the P third OFDM signals, and taking the third OFDM signal with the lowest peak-to-average power ratio as the second target signal; The second target signal is subjected to OFDM modulation.

10. A modulation device for an OFDM signal, comprising: A signal acquisition module, used to acquire a first OFDM signal, where the first OFDM signal includes M×N ranging codes, where M represents the number of symbols of the first OFDM signal, and N represents the number of subcarriers of the first OFDM signal, where both M and N are positive integers; a phase-hopping modulation module, configured to perform phase-hopping modulation on the first OFDM signal in units of subcarriers to obtain a second OFDM signal; and The frequency hopping modulation module is used to perform frequency hopping modulation on the second OFDM signal to obtain a third OFDM signal.

11. A computing device comprising: at least one processor; as well as At least one memory storing instructions thereon, which, when executed individually or collectively by the at least one processor, cause the computing device to perform the method according to any one of claims 1 to 9.

12. A computer storage medium having stored thereon instructions which, when executed individually or collectively by at least one processor of a computing device, cause the computing device to perform the method according to any one of claims 1 to 9.

13. A computer program product comprising instructions which, when executed individually or collectively by at least one processor of a computing device, cause the computing device to perform the method according to any one of claims 1 to 9.

14. A chip system for a computing device, the chip system comprising at least one processor, the at least one processor being configured to individually or collectively execute instructions stored in at least one memory of the computing device so that the computing device performs a method according to any one of claims 1 to 9.

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