High-order CPM modulation and demodulation method and device based on Gray mapping and precoding

Abstract

The invention discloses a high-order CPM modulation and demodulation method and device based on Gray mapping and precoding, and the method comprises the steps: carrying out the Gray mapping processing of a to-be-modulated signal, and obtaining a unipolar first symbol; performing polarity conversion on the first symbol to convert the first symbol into a bipolar second symbol; and after the second symbol is pre-coded, continuous phase modulation of which the order is greater than or equal to 2 is carried out, and a high-order CPM modulation signal is obtained. According to the high-order CPM modulation and demodulation method and the high-order CPM modulation and demodulation device based on the Gray mapping and the precoding disclosed by the invention, each-order CPM modulation is realized by combining the Gray mapping and precoding technologies, the demodulation complexity of the high-order CPM can be obviously reduced, and the performance of the high-order CPM can be improved.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a high-order CPM modulation and demodulation method and apparatus based on Gray mapping and precoding. Background Technology

[0002] Continuous phase modulation (CPM) is a type of constant envelope modulation with advantages such as low peak-to-average power ratio (PAPR), concentrated spectrum, and good sidelobe suppression. Second-order CPM has been widely used in wireless communication standards such as second-generation mobile communication, Bluetooth, Link-16, and TTN, as well as in satellite communication, telemetry, and remote sensing. With the increasing scarcity of spectrum resources and the continuous improvement of data transmission rates, traditional low-order CPM can no longer meet the needs of modern communication systems, and high-order CPM is gradually attracting research attention.

[0003] Traditional high-order CPM, whether directly demodulated or equivalent to convolutional coding and memoryless modulation using Rimoldi decomposition, requires the use of trellis diagrams. This high complexity and the performance degradation compared to linear modulation of the same order offsets the improvement in peak-to-average power ratio (PAPR). These issues limit the application of high-order CPM. To address this, existing technologies generally utilize the Mengali decomposition principle of high-order CPM signals for modulation. For example, the Mengali decomposition principle of high-order CPM signals can be used to extract the bit-level log-likelihood ratio (LLR) based on a pre-coded 4th-order CPM modulation and demodulation scheme, employing symbol-by-symbol integration across the entire sequence. This alleviates the demodulation complexity problem. However, the bit mapping and LLR extraction involved in precoding cannot be extended to arbitrary modulation orders, and the LLR extraction method using full-sequence integration is overly complex. For example, the Mengali decomposition principle can be used to realize a full-response high-order CPM with raised cosine frequency shaping, but the modulation process needs to distinguish between odd and even moments, and the error performance is significantly lower than that of multiple phase shift keying (MPSK) modulation.

[0004] In summary, existing technologies have shortcomings such as difficulty in balancing demodulation complexity and error performance.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a high-order CPM modulation and demodulation method and apparatus based on Gray mapping and precoding, which can significantly reduce the demodulation complexity of high-order CPM and improve its performance. Its demodulation complexity and error performance are comparable to MPSK.

[0007] To achieve the above objectives, this invention provides a high-order CPM modulation method based on Gray mapping and precoding, comprising:

[0008] The signal to be modulated is processed by Gray mapping to obtain the first symbol of unipolarity;

[0009] The first symbol is transformed by polarity conversion to a bipolar second symbol;

[0010] After precoding the second symbol, continuous phase modulation with an order greater than or equal to 2 is performed to obtain a high-order CPM modulated signal.

[0011] In one embodiment of the present invention, a high-order CPM demodulation method based on Gray mapping and precoding includes:

[0012] The signal to be demodulated is downsampled and derotated to obtain a first signal; the signal to be demodulated is a high-order CPM modulation signal generated based on the high-order CPM modulation method based on Gray mapping and precoding as described in claim 1.

[0013] The first signal is demodulated.

[0014] In one embodiment of the present invention, demodulating the first signal includes:

[0015] The first signal is demodulated based on the maximum a posteriori probability detection method.

[0016] In one embodiment of the present invention, demodulating the first signal includes:

[0017] When the signal to be demodulated is a full-response high-order CPM signal, the first signal is demodulated based on a multi-level phase shift keying method.

[0018] In one embodiment of the present invention, after demodulating the first signal using the maximum a posteriori probability detection method, the method further includes:

[0019] After performing Gray inverse mapping on the demodulated log-likelihood matrix, a number system conversion is performed.

[0020] In one embodiment of the present invention, a high-order CPM modulation device based on Gray mapping and precoding includes:

[0021] The Gray mapping module is used to process the signal to be modulated through Gray mapping to obtain the first symbol of unipolarity.

[0022] A polarity conversion module is used to convert the first symbol into a bipolar second symbol.

[0023] The precoding module is used to precode the second symbol and then perform continuous phase modulation of order greater than or equal to 2 to obtain a high-order CPM modulated signal.

[0024] In one embodiment of the present invention, a high-order CPM demodulation device based on Gray mapping and precoding includes:

[0025] The sampling module is used to downsample and derotate the signal to be demodulated to obtain a first signal; the signal to be demodulated is a high-order CPM modulation signal generated based on the high-order CPM modulation method based on Gray mapping and precoding as described in claim 1.

[0026] The demodulation module is used to demodulate the first signal.

[0027] In one embodiment of the present invention, an electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of any of the above-described high-order CPM modulation or demodulation methods based on Gray mapping and precoding.

[0028] In one embodiment of the present invention, a non-transitory computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of any of the above-described high-order CPM modulation or demodulation methods based on Gray mapping and precoding.

[0029] In one embodiment of the present invention, a computer program product includes a computer program that, when executed by a processor, implements the steps of any of the above-described high-order CPM modulation or demodulation methods based on Gray mapping and precoding.

[0030] Compared with existing technologies, the present invention, based on a high-order CPM modulation and demodulation method and apparatus using Gray mapping and precoding, offers the following advantages: it proposes a general scheme for high-order CPM modulation and demodulation based on Gray mapping and precoding. This scheme utilizes the Mengali decomposition principle, combining Gray mapping and precoding techniques to implement CPM modulation at various orders. It uses the Max-Log-MAP algorithm to calculate the symbol-level log-likelihood value, and then outputs the bit-level log-likelihood ratio through inverse Gray mapping. This significantly reduces the demodulation complexity of high-order CPM and improves its performance. In particular, for full-response high-order CPM, it simplifies it to ordinary MPSK modulation, and its demodulation complexity and error performance are comparable to MPSK. Attached Figure Description

[0031] Figure 1 This is one of the flowcharts of a high-order CPM modulation method based on Gray mapping and precoding according to an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the Gray mapping of a second-order signal in a high-order CPM modulation and demodulation method based on Gray mapping and precoding according to an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of the Gray mapping of a 4th-order signal in a high-order CPM modulation and demodulation method based on Gray mapping and precoding according to an embodiment of the present invention.

[0034] Figure 4 This is a schematic diagram of the Gray mapping of an 8th-order signal in a high-order CPM modulation and demodulation method based on Gray mapping and precoding according to an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram of the Gray mapping of a 16th-order signal in a high-order CPM modulation and demodulation method based on Gray mapping and precoding according to an embodiment of the present invention.

[0036] Figure 6 This is a second flowchart illustrating a high-order CPM modulation method based on Gray mapping and precoding according to an embodiment of the present invention.

[0037] Figure 7 This is one of the flowcharts of a high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention;

[0038] Figure 8 This is a second flowchart illustrating a high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention.

[0039] Figure 9The 4th-order CPM mesh map with precoding is used in the high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention.

[0040] Figure 10 This is the third flowchart of a high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention;

[0041] Figure 11 This is one of the schematic diagrams illustrating the effect of a high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention;

[0042] Figure 12 This is a second schematic diagram illustrating the effect of a high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention;

[0043] Figure 13 This is a schematic diagram of a high-order CPM modulation device based on Gray mapping and precoding according to an embodiment of the present invention;

[0044] Figure 14 This is a schematic diagram of the structure of a high-order CPM demodulation device based on Gray mapping and precoding according to an embodiment of the present invention;

[0045] Figure 15 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0046] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0047] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0048] like Figures 1 to 15 As shown, the high-order CPM modulation and demodulation method and apparatus based on Gray mapping and precoding according to a preferred embodiment of the present invention can be implemented in the following ways.

[0049] Figure 1 This is one of the flowcharts illustrating a high-order CPM modulation method based on Gray mapping and precoding according to an embodiment of the present invention. Figure 1 As shown, the method may include the following steps:

[0050] Step 101: The signal to be modulated is processed by Gray mapping to obtain the first symbol of unipolarity;

[0051] Step 102: Perform a polarity transformation on the first symbol to convert it into a bipolar second symbol;

[0052] Step 103: After precoding the second symbol, perform continuous phase modulation with an order greater than or equal to 2 to obtain a high-order CPM modulated signal.

[0053] Specifically, the general expression for a continuous phase modulated signal is:

[0054] (1).

[0055] In the formula, The amplitude is constant. The phase expression can be expanded as follows:

[0056] (2).

[0057] in, For symbol period, and Modulation index Usually The rational number between the two, and its most commonly used value is the reciprocal of the modulation order. For memory length, when When this modulation occurs, it is called full-response CPM; when... When this modulation occurs, it is called partial response CPM. Let the modulation efficiency be... Bit / symbol, then the modulation order is Therefore, the unipolar symbol , Its mapping relationship with bipolar symbols is as follows: Data is carried in a bipolar vector. And there are

[0058] (3).

[0059] Phase response function It has continuous and monotonic properties and satisfies

[0060] (4).

[0061] in, It can usually be determined by the frequency response function. It comes from points.

[0062] Frequency response functions can include rectangular, raised cosine, Gaussian, and spectral raised cosine functions, among others. Different types of frequency response functions have different spectral efficiencies and error performance. In practice, different frequency response functions can be selected according to different requirements. When the modulation order is the same, as the memory length increases, the spectrum of the modulated signal becomes more compact, and there is less interference to adjacent frequency bands. For full-response CPM, the spectral shapes of rectangular pulses and Gaussian pulses are quite similar, and the main lobe of rectangular pulses is relatively narrower; therefore, rectangular pulses are often used in full-response CPM. For partial-response CPM, the spectral shape of Gaussian pulses is the smoothest, and the sidelobe suppression is also the best; therefore, Gaussian pulses are often used in partial-response CPM.

[0063] The Mengali decomposition of higher-order CPM signals (order greater than or equal to 2) is a high-dimensional extension of the Laurent decomposition of second-order CPM signals. Based on the Mengali decomposition principle, higher-order CPM signals can be represented as...

[0064] (6).

[0065] in, , Higher-order pseudo-symbols are

[0066] (7).

[0067] Higher-order basis pulses are

[0068] (8).

[0069] In expressions with higher-order pseudo-symbols,

[0070] (9).

[0071] In the expression of higher-order basis pulses, using

[0072] (10).

[0073] Then there is

[0074] (11).

[0075] Analysis reveals that through Mengali decomposition... The energy of the first-order CPM signal is mainly concentrated in the front. On a pulse.

[0076] For a full-response CPM, the shape of the rectangular pulse is similar to that of the CPM pulse corresponding to the Gaussian frequency response function; while for a partial-response CPM, the shape of the raised cosine pulse is similar to that of the CPM pulse corresponding to the Gaussian frequency response function. This phenomenon is consistent with the pattern of similar spectral frequencies.

[0077] In traditional direct CPM modulation, pseudo-symbols do not directly reflect the original information. The main function of precoding is to enable pseudo-symbols to intuitively represent the original information. Furthermore, precoding, along with Gray mapping, can reduce the error rate.

[0078] Gray mapping rules guarantee that there is only one bit difference between adjacent symbols, thereby reducing the bit error rate under the same symbol error rate. In Gray mapping from bit sequences to higher-order CPM signals, in addition to satisfying the general rules of Gray mapping, it is also necessary to make it easy for the receiver to extract the likelihood ratio.

[0079] It is generally believed that discrete modulation schemes such as ASK, PSK, and QAM can be briefly described using constellation diagrams, while CPM is difficult to represent using constellation diagrams due to its continuous phase transformation. However, after precoding, CPM signals can also be visually represented using constellation diagrams to reflect the original data.

[0080] Figures 2 to 5 The diagram shows the Gray mapping in a high-order CPM signal constellation diagram. The constellation points are uniformly distributed on the unit circle, and the constellation point corresponding to all-zero bits is... A bit sequence starting with 0... Starting with a positive distribution, the bit sequence begins with 1 and continues in a positive direction. The starting point is the reverse distribution. In the mapping, the first bit corresponds to the imaginary part, and the second bit corresponds to the real part. This mapping facilitates the extraction of soft information at the receiving end. In the Gray mapping of each order of CPM, corresponding to the constellation diagram, the bit groups... Natural unipolar symbol And the bipolar symbol after Gray mapping The relationships are shown in Tables 1 to 4 below.

[0081] Table 1. Gray mapping from second-order CPM bit groups to bipolar symbols.

[0082]

[0083] Table 2. Gray mapping from 4th-order CPM bit groups to bipolar symbols.

[0084]

[0085] Table 3. Gray mapping from 8th-order CPM bit groups to bipolar symbols.

[0086]

[0087] Table 4. Gray mapping from 16th-order CPM bit groups to bipolar symbols

[0088]

[0089]

[0090] In the CPM constellation diagram of this invention embodiment, the constellation point corresponding to all 0 bits is: The relationship between bit groups and constellation points is the Gray mapping, where the first bit is 0 in the upper half of the complex plane and 1 in the lower half, meaning the 0 and 1 of the first bit correspond to the positive and negative imaginary parts of the sign. This design is suitable for the characteristics of CPM modulation and also incorporates the high reliability of the Gray mapping.

[0091] For the 4th-order CPM precoding scheme, it can be extended to any The order (P is a positive integer) case, i.e.

[0092] (12).

[0093] in, ; Corrected model The operation is based on the usual modulo operation, and involves addition or subtraction. ,make . Desirable Any odd number between 0 and 1. For ease of processing, we can let 0 = 0. That is, Understandably, The result of precoding is given by d, where d is a signal or symbol of length n to be precoded, and bits 0 to n-1 of d are denoted as d0 to d1 respectively. n-1 .

[0094] Based on the above formula, the results of the 2nd, 4th, and 8th order operations can be obtained, as shown in Tables 5-7. The 16th order operation is similar, and due to space limitations, it will not be listed here.

[0095] Table 5 Results of 2nd-order precoding operations

[0096]

[0097] Table 6 Results of 4th-order precoding operations

[0098]

[0099] Table 7 Results of 8th-order precoding operations

[0100]

[0101]

[0102]

[0103]

[0104] It should be noted that extending 4th-order precoding to the general case of arbitrary modulation order and incorporating precoding of various modulation orders into a unified framework provides a consistent approach for the implementation of higher-order CPMs of different orders.

[0105] Based on the Gray mapping CPM constellation diagram and high-order precoding, the entire modulation process from bit group (i.e. the signal to be modulated) to high-order CPM signal can be completely described.

[0106] Figure 6 This is a second flowchart illustrating a high-order CPM modulation method based on Gray mapping and precoding according to an embodiment of the present invention. Figure 6 The diagram illustrates the CPM modulation process based on Gray mapping and precoding. (Reference) Figure 6 Source bit sequence (The signal to be modulated) is transformed into a unipolar higher-order symbol through Gray mapping. (i.e., the first symbol); utilizing Perform a polarity transformation to convert the unipolar higher-order sign. It is transformed into a bipolar symbol d (i.e., the second symbol); the bipolar symbol d is then transformed via higher-order precoding. Finally, based on the definition of advanced CPM, it is possible to... Higher-order CPM signals are obtained based on this. .

[0107] Figure 7 This is one of the flowcharts illustrating a high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention. Figure 7 As shown, the method may include the following steps:

[0108] Step 701: Perform downsampling and derotation processing on the signal to be demodulated to obtain the first signal; the signal to be demodulated is a high-order CPM modulation signal generated based on any of the aforementioned high-order CPM modulation methods based on Gray mapping and precoding.

[0109] Step 702: Demodulate the first signal.

[0110] Specifically, a general method applicable to any memory length can be used, namely, using a mesh graph and a MAP (maximum a posteriori) detection method (described below as an example) for demodulation.

[0111] In some feasible implementations, the first signal is demodulated, including: demodulating the first signal based on a maximum a posteriori probability detection method.

[0112] In some feasible implementations, after demodulating the first signal based on the maximum a posteriori probability detection method, the method further includes: performing Gray inverse mapping on the demodulated log-likelihood matrix and then performing a base conversion.

[0113] It should be noted that the general method applicable to the demodulation of Gray mapping and precoded high-order CPM signals involves derotating the received signal, describing the relationship between source signals at adjacent time points using a trellis diagram, implementing symbol-level demodulation using the Max-Log-MAP algorithm, and then extracting the bit-level log-likelihood ratio based on the Gray mapping relationship.

[0114] Figure 8 This is a second flowchart illustrating a high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention.

[0115] refer to Figure 8 Let the length of the higher-order data be Receive signal (i.e., the signal to be demodulated) first passes through A parallel filter is obtained. Output signal Among them, the first Lu Wei

[0116] (13)

[0117] In the formula, ,symbol" "" indicates convolution. Each signal is downsampled separately to obtain... road signal For simplicity, let... .right Solve the rotations separately to obtain phases that do not rotate with time. Path output (i.e., the first signal), the rotation solution is as follows:

[0118] (14)

[0119] In Max-Log-MAP (MAP with maximum value in the logarithmic field) demodulation, the branch metric is calculated as follows: When performing iterative operations with the decoder, the branch metric should also include prior information. In the calculation of the branch metric, Only data at the current time related, Compared with the data of the previous moment and current data All are relevant. For level 4 CPM, there are

[0120] (15).

[0121] Dividing both sides of each equation by the rotation factor stabilizes the metric values, thus yielding:

[0122] (16).

[0123] Similarly, for level 8 CPM, there is

[0124] (17).

[0125] refer to Figure 9 , Figure 9 The image shown is a 4th-order CPM mesh plot using pre-coding. For ease of representation, Figure 9 The local vector for the middle branch metric label is The exponent term, whose base is . .

[0126] The Max-Log-MAP demodulation output corresponds to the Gray map. Log-likelihood matrix When calculating the forward recursive state metric, the state... The metric value is 0, and the metric values ​​for the other states are... When calculating backward recursive state metrics, each state metric value is... After reconstructing the order column-wise, the log-likelihood matrix of the natural mapping is obtained. This allows for the extraction of the second-order log-likelihood ratio sequence. The correspondences between the 4th, 8th, and 16th order natural mappings and the Gray mappings are shown in Tables 2-4.

[0127] The above analysis shows that even with precoding, the general demodulation method of high-order CPM is still related to the signal from the previous moment.

[0128] In some feasible implementations, demodulating the first signal includes: when the signal to be demodulated is a full-response high-order CPM signal, demodulating the first signal based on a multi-level phase shift keying method.

[0129] Specifically, a simplified method applicable to full-response high-order CPM can be used to convert the high-order CPM signal into a corresponding MPSK signal, thereby greatly reducing demodulation complexity while maintaining reliability.

[0130] For demodulation of fully-response high-order CPM signals, there are simpler methods. Let's review the duration of the Mengali decomposition basis functions in fully-response high-order CPM: energy-dominant basis functions. Duration is And at the moment The maximum value is 1; the remaining basis functions The duration is This means that during the symbol period Sampling at integer multiples can obtain While maximizing the value, it avoids interference from other basis functions, thus greatly reducing demodulation complexity.

[0131] The core of full-response advanced CPM demodulation lies in

[0132] (18)

[0133] This formula makes time... Pseudo-symbols involved in metric calculation Only the raw data at the current moment Related.

[0134] Figure 10 This is the third flowchart of a high-order CPM demodulation method based on Gray mapping and precoding according to an embodiment of the present invention. Figure 10 The diagram shows the full-response high-order CPM demodulation process based on Gray mapping and precoding. Received signal (i.e., the signal to be demodulated) is multiplied by an integer multiple. Downsampling, to obtain After rotation, we obtain .

[0135] At this time This is the MPSK received signal (i.e., the first signal). The final log-likelihood ratio can be obtained by using the conventional MPSK detection method. For BPSK, one symbol corresponds to one LLR, and its extraction method is as follows:

[0136] (19).

[0137] For QPSK, one symbol corresponds to two LLRs. The extraction method is the same as BPSK. for

[0138] (20).

[0139] For 8PSK, one symbol corresponds to three LLRs. and The extraction method is the same as QPSK. for

[0140] (twenty one).

[0141] For 16PSK, one symbol corresponds to four LLRs. , and The extraction method is the same as 8PSK. for

[0142] (twenty two).

[0143] It should be noted that the full-response high-order CPM signal demodulation method applicable to Gray mapping and precoding greatly reduces the demodulation complexity by directly extracting the bit-level log-likelihood ratio in the MPSK manner after derotating the received signal, and its reliability is comparable to MPSK.

[0144] Traditional CPM signals without precoding can be demodulated using two types of trellises. One is by directly expanding the phase expression, which involves dividing the phase into phase states. and related status The number of states in its grid diagram is Another approach is Rimoldi decomposition, which introduces the concept of "tilted phase" to decompose the CPM modulation process into two modules: continuous phase coding and memoryless modulation. Its trellis diagram has the following number of states: .

[0145] Table 8 Comparison of the number of demodulation mesh diagram states for different high-order CPM implementation methods

[0146]

[0147] Table 8 presents a comparison of the number of states in the high-order CPM demodulation trellis with and without precoding. It can be seen that, without precoding, regardless of whether Rimoldi decomposition is used, the number of trellis states and modulation efficiency are significantly lower. and memory length The relationships are all exponential. Specifically, demodulation complexity without decomposition is twice that with Rimoldi decomposition. For high-order CPM signals with partial responses, the excessive number of mesh graph states makes demodulation unacceptable.

[0148] When employing a precoding scheme, it is necessary to combine it with Mengali decomposition. The number of states in the higher-order CPM trellis diagram with different memory lengths is only related to the modulation efficiency and is the same as the number of states in the full-response higher-order CPM trellis diagram of Rimoldi decomposition. In particular, through Mengali decomposition, the full-response higher-order CPM signal can be losslessly converted into an MPSK signal, greatly reducing the demodulation complexity.

[0149] Simulations demonstrate the error performance of the full and partial responses of 4th-order CPM and 8th-order CPM based on Gray mapping and precoding. In practical applications, rectangular pulses are commonly used as the frequency shaping function for the full response, while Gaussian pulses are commonly used as the frequency shaping function for the partial response. For comparison, the error performance of the same-order PSK based on Gray mapping is also presented.

[0150] Figure 11 The figure shows the modulation error performance of 4th-order CPM and QPSK based on Gray mapping and precoding, where the modulation index of 4th-order CPM is... .when At that time, the bit error rate curves of 4th-order CPM and QPSK almost overlapped. At that time, the error performance of 4th-order CPM deteriorates significantly. In practical applications, 4th-order modulation constant concatenation of medium-rate channel coding such as 1 / 2 and 2 / 3 code rates needs to be examined. Around 4dB. At this point, the QPSK and memory length are... The performance difference between the 4th-order CPM is approximately 2 dB. Considering that the peak-to-average power ratio (PAPR) of QPSK is approximately 4 dB, while that of the 4th-order CPM is 0 dB, therefore, under the same hardware conditions and communication quality requirements, The 4th-order CPM supports longer communication distances.

[0151] Figure 12 The figure shows the modulation error performance of 8th-order CPM and 8PSK based on Gray mapping and precoding, where the modulation index of 8th-order CPM is... .when At that time, the bit error rate curves of 8th order CPM and 8PSK almost overlapped. At that time, the error performance of 8th-order CPM deteriorates significantly. In practical applications, high-rate channel coding with 8th-order modulation constant concatenation greater than 2 / 3 requires further investigation. Around 6dB. At this point, 8PSK and the memory length are... The performance difference between the 8th-order CPM is approximately 4 dB. Considering that the peak-to-average power ratio (PAPR) of 8PSK is approximately 4 dB, while that of 8th-order CPM is 0 dB, therefore, under the same hardware conditions and communication quality requirements, The 8th-order CPM no longer has a significant advantage.

[0152] The beneficial effect of this invention is that it proposes a general scheme for high-order CPM modulation and demodulation based on Gray mapping and precoding. This scheme utilizes the Mengali decomposition principle, combined with Gray mapping and precoding techniques to implement CPM modulation at various orders, and uses algorithms such as Max-Log-MAP to calculate symbol-level log-likelihood values. Then, it outputs bit-level log-likelihood ratios through inverse Gray mapping, which significantly reduces the demodulation complexity of high-order CPM and improves its performance. In particular, for full-response high-order CPM, it can simplify it to ordinary MPSK modulation, and its demodulation complexity and error performance are comparable to MPSK. Through in-depth research and analysis, this invention can provide new ideas and methods for the application of high-order CPM in wireless communication.

[0153] This application proposes a general method for Gray mapping and precoding suitable for various CPMs, and proposes a Max-Log-MAP demodulation method suitable for partial response CPMs and a simplified demodulation method suitable for full response.

[0154] The high-order CPM modulation and demodulation scheme proposed in this invention, based on Gray mapping and precoding, simplifies the demodulation complexity of high-order CPM and improves reliability. Utilizing the Mengali decomposition principle, demodulation can be achieved using only a few pulses through a trellis diagram. Particularly for full-response high-order CPM, it can be converted into an MPSK signal, thus significantly reducing the computational load of demodulation. Simulation results show that due to the constant envelope advantage of CPM signals, they are suitable for nonlinear amplifiers and make more efficient use of transmitter power. Therefore, compared with MPSK modulation of the same order, the proposed scheme can support longer communication distances.

[0155] The high-order CPM modulation and demodulation device based on Gray mapping and precoding provided by the present invention is described below. The high-order CPM modulation and demodulation device based on Gray mapping and precoding described below can be referred to in correspondence with the high-order CPM modulation and demodulation method based on Gray mapping and precoding described above.

[0156] Figure 13 This is a schematic diagram of the structure of the high-order CPM modulation device based on Gray mapping and precoding provided by the present invention. Based on the content of any of the above embodiments, as... Figure 13 As shown, the device includes a Gray mapping module 1301, a polarity conversion module 1302, and a precoding module 1303, wherein:

[0157] The Gray mapping module 1301 is used to process the signal to be modulated through Gray mapping to obtain the first symbol of unipolarity.

[0158] The polarity conversion module 1302 is used to convert the first symbol into a bipolar second symbol.

[0159] The precoding module 1303 is used to precode the second symbol and then perform continuous phase modulation of order greater than or equal to 2 to obtain a high-order CPM modulated signal.

[0160] The high-order CPM modulation apparatus based on Gray mapping and precoding provided in this embodiment of the invention is used to execute the high-order CPM modulation method based on Gray mapping and precoding described above. Its implementation method is consistent with the implementation method of the high-order CPM modulation method based on Gray mapping and precoding provided in this invention, and can achieve the same beneficial effects, so it will not be described again here.

[0161] This high-order CPM modulation apparatus based on Gray mapping and precoding is used in the high-order CPM modulation methods based on Gray mapping and precoding in the foregoing embodiments. Therefore, the descriptions and definitions in the high-order CPM modulation methods based on Gray mapping and precoding in the foregoing embodiments can be used for understanding the execution modules in the embodiments of the present invention.

[0162] Figure 14 This is a schematic diagram of the structure of the high-order CPM demodulation device based on Gray mapping and precoding provided by the present invention. Based on the content of any of the above embodiments, as... Figure 14 As shown, the device includes a sampling module 1401 and a demodulation module 1402, wherein:

[0163] Sampling module 1401 is used to downsample and derotate the signal to be demodulated to obtain a first signal; the signal to be demodulated is a high-order CPM modulation signal generated based on the high-order CPM modulation method based on Gray mapping and precoding as described in claim 1.

[0164] The demodulation module 1402 is used to demodulate the first signal.

[0165] The high-order CPM demodulation device based on Gray mapping and precoding provided in this embodiment of the invention is used to execute the high-order CPM demodulation method based on Gray mapping and precoding described above. Its implementation method is consistent with the implementation method of the high-order CPM demodulation method based on Gray mapping and precoding provided in this invention, and can achieve the same beneficial effects, so it will not be described again here.

[0166] This high-order CPM demodulation apparatus based on Gray mapping and precoding is used in the high-order CPM demodulation methods based on Gray mapping and precoding in the foregoing embodiments. Therefore, the descriptions and definitions in the high-order CPM demodulation methods based on Gray mapping and precoding in the foregoing embodiments can be used to understand the execution modules in the embodiments of the present invention.

[0167] In some feasible implementations, the demodulation module 1402 can be specifically used to demodulate the first signal based on the maximum a posteriori probability detection method.

[0168] In some feasible implementations, the demodulation module 1402 can be specifically used to demodulate the first signal based on a multi-level phase shift keying method when the signal to be demodulated is a full-response high-order CPM signal.

[0169] In some feasible implementations, the demodulation module 1402 can also be used to perform Gray inverse mapping on the demodulated log-likelihood matrix and then perform base conversion.

[0170] Figure 15 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 15 As shown, the electronic device may include: a processor 1510, a communications interface 1520, a memory 1530, and a communication bus 1540, wherein the processor 1510, the communications interface 1520, and the memory 1530 communicate with each other through the communication bus 1540. The processor 1510 can call logic instructions in the memory 1530 to execute a high-order CPM modulation and demodulation method based on Gray mapping and precoding. The method includes: processing the signal to be modulated through Gray mapping to obtain a unipolar first symbol; performing a polarity transformation on the first symbol to convert it into a bipolar second symbol; precoding the second symbol and then performing continuous phase modulation of order greater than or equal to 2 to obtain a high-order CPM modulated signal; or, performing downsampling and derotation processing on the signal to be demodulated to obtain a first signal; the signal to be demodulated is a high-order CPM modulated signal generated based on any of the aforementioned high-order CPM modulation methods based on Gray mapping and precoding; and demodulating the first signal.

[0171] Furthermore, the logical instructions in the aforementioned memory 1530 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0172] The processor 1510 in the electronic device provided in this embodiment of the invention can call the logic instructions in the memory 1530. Its implementation method is consistent with the implementation method of the high-order CPM modulation and demodulation method based on Gray mapping and precoding provided in this invention, and can achieve the same beneficial effects. It will not be described again here.

[0173] On the other hand, the present invention also provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, wherein when the program instructions are executed by a computer, the computer is able to execute the high-order CPM modulation and demodulation method based on Gray mapping and precoding provided by the above methods, the method comprising: processing the signal to be modulated through Gray mapping to obtain a unipolar first symbol; performing a polarity transformation on the first symbol to convert it into a bipolar second symbol; performing precoding on the second symbol and then performing continuous phase modulation of order greater than or equal to 2 to obtain a high-order CPM modulated signal; or, performing downsampling and derotation processing on the signal to be demodulated to obtain a first signal; the signal to be demodulated is a high-order CPM modulated signal generated based on any of the aforementioned high-order CPM modulation methods based on Gray mapping and precoding; and demodulating the first signal.

[0174] When the computer program product provided in this embodiment of the invention is executed, it implements the above-mentioned high-order CPM modulation and demodulation method based on Gray mapping and precoding. Its specific implementation method is consistent with the implementation method described in the aforementioned method embodiment, and can achieve the same beneficial effect, which will not be repeated here.

[0175] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements the aforementioned high-order CPM modulation and demodulation methods based on Gray mapping and precoding. The method includes: processing the signal to be modulated through Gray mapping to obtain a unipolar first symbol; performing a polarity transformation on the first symbol to convert it into a bipolar second symbol; precoding the second symbol and then performing continuous phase modulation of order greater than or equal to 2 to obtain a high-order CPM modulated signal; or, performing downsampling and derotation processing on the signal to be demodulated to obtain a first signal; the signal to be demodulated is a high-order CPM modulated signal generated based on any of the aforementioned high-order CPM modulation methods based on Gray mapping and precoding; and demodulating the first signal.

[0176] When the computer program stored on the non-transitory computer-readable storage medium provided in this embodiment of the invention is executed, it implements the above-mentioned high-order CPM modulation and demodulation method based on Gray mapping and precoding. Its specific implementation method is consistent with the implementation method described in the aforementioned method embodiments, and can achieve the same beneficial effects, which will not be repeated here.

[0177] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0178] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0179] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0180] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0181] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

[0182] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A high-order CPM modulation method based on Gray mapping and precoding, characterized in that, include: The signal to be modulated is processed by Gray mapping to obtain the first symbol of unipolarity; The first symbol is transformed by polarity conversion to a bipolar second symbol; After precoding the second symbol, continuous phase modulation with an order greater than or equal to 2 is performed to obtain a high-order CPM modulated signal.

2. A high-order CPM demodulation method based on Gray mapping and precoding, characterized in that, include: The signal to be demodulated is downsampled and derotated to obtain the first signal; The signal to be demodulated is a high-order CPM modulated signal generated based on the high-order CPM modulation method based on Gray mapping and precoding as described in claim 1. The first signal is demodulated.

3. The high-order CPM demodulation method based on Gray mapping and precoding according to claim 2, characterized in that, The demodulation of the first signal includes: The first signal is demodulated based on the maximum a posteriori probability detection method.

4. The high-order CPM demodulation method based on Gray mapping and precoding according to claim 2, characterized in that, The demodulation of the first signal includes: When the signal to be demodulated is a full-response high-order CPM signal, the first signal is demodulated based on a multi-level phase shift keying method.

5. The high-order CPM demodulation method based on Gray mapping and precoding according to claim 3, characterized in that, After demodulating the first signal using the maximum a posteriori probability detection method, the method further includes: After performing Gray inverse mapping on the demodulated log-likelihood matrix, a number system conversion is performed.

6. A high-order CPM modulation device based on Gray mapping and precoding, characterized in that, include: The Gray mapping module is used to process the signal to be modulated through Gray mapping to obtain the first symbol of unipolarity. A polarity conversion module is used to convert the first symbol into a bipolar second symbol. The precoding module is used to precode the second symbol and then perform continuous phase modulation of order greater than or equal to 2 to obtain a high-order CPM modulated signal.

7. A high-order CPM demodulation device based on Gray mapping and precoding, characterized in that, include: The sampling module is used to downsample and derotate the signal to be demodulated to obtain the first signal; The signal to be demodulated is a high-order CPM modulated signal generated based on the high-order CPM modulation method based on Gray mapping and precoding as described in claim 1. The demodulation module is used to demodulate the first signal.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the high-order CPM modulation method based on Gray mapping and precoding as described in claim 1, or the steps of the high-order CPM demodulation method based on Gray mapping and precoding as described in any one of claims 2 to 5.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the high-order CPM modulation method based on Gray mapping and precoding as described in claim 1, or the steps of the high-order CPM demodulation method based on Gray mapping and precoding as described in any one of claims 2 to 5.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the high-order CPM modulation method based on Gray mapping and precoding as described in claim 1, or the steps of the high-order CPM demodulation method based on Gray mapping and precoding as described in any one of claims 2 to 5.

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