Unitary space-time modulation method and device, unitary space-time demodulation method and device, electronic equipment and storage medium

Abstract

The invention discloses a unitary space-time modulation and demodulation method and device, electronic equipment and a storage medium, and the method comprises the steps: carrying out the unitary space-time modulation of target data based on a unitary space-time modulation signal constellation set, and obtaining a unitary space-time modulation signal; a first signal in the modulation signal constellation set is generated based on a Hadamard matrix; and converting the unitary space-time modulation signal into an offset quadrature phase shift keying signal, and converting the offset quadrature phase shift keying signal into a continuous phase modulation signal. According to the unitary space-time modulation and demodulation method and device, the electronic equipment and the storage medium, the USTM constellation set head signal is constructed based on the orthogonal characteristic of the Hadamard matrix, the complete constellation set is generated through diagonal matrix design, finally, signal phase continuity is achieved through constant envelope processing, and the peak-to-average ratio can be remarkably reduced.

Description

Spacetime modulation and demodulation methods, devices, electronic equipment and storage media Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a spacetime modulation and demodulation method, apparatus, electronic device, and storage medium. Background Technology

[0002] Multiple-input multiple-output (MIMO) systems, with their high data transmission efficiency and reliability, have become a key technology in the field of wireless communication. Unitary space-time modulation (USTM) is a non-coherent space-time code that eliminates the need for channel estimation at both the transmitting and receiving ends, making it particularly suitable for Rayleigh flat-fading channels with rapidly changing fading coefficients, exhibiting unique advantages in dynamic communication scenarios. However, current mainstream USTM signal design schemes, primarily based on Discrete Fourier Transform (DFT) matrices, Generalized Phase Shift Keying (PSK), or Space-Time Block Code (STBC) matrices, generally suffer from excessively high peak-to-average power ratio (PAPR). Even with a fixed symbol magnitude, these symbol-level unitary matrices still exhibit a high PAPR after low-pass filtering, severely limiting the efficiency of power amplifiers and signal transmission quality.

[0003] 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

[0004] The purpose of this invention is to provide a unitary spacetime modulation and demodulation method, apparatus, electronic device and storage medium that can significantly reduce peak-to-average power ratio and effectively solve the nonlinear distortion problem of high power amplifiers.

[0005] To achieve the above objectives, the present invention provides a unitary spacetime modulation method, comprising:

[0006] Based on a set of unitary spacetime modulation signal constellations, the target data is subjected to unitary spacetime modulation to obtain a unitary spacetime modulation signal; the first signal in the set of modulation signal constellations is generated based on the Hadamard matrix.

[0007] The unitary spacetime modulation signal is converted into an offset quadrature phase shift keying signal, and the offset quadrature phase shift keying signal is converted into a continuous phase modulation signal.

[0008] In one embodiment of the present invention, the step of performing unitary space-time modulation on the transmitted signal based on a unitary space-time modulation signal constellation set to obtain a unitary space-time modulated signal includes:

[0009] Determine the unitary matrix corresponding to the transmitted signal in the unitary spacetime modulation signal constellation set;

[0010] The unitary space-time modulated signal is obtained based on the unitary matrix and the channel coherence time.

[0011] In one embodiment of the present invention, converting the unitary spacetime modulation signal into an offset quadrature phase shift keying signal includes:

[0012] The target data is converted into a symbol vector, and for each symbol in the symbol vector, the unitary space-time modulation signal matrix corresponding to the symbol is determined based on the unitary space-time modulation signal.

[0013] The first signal matrix is ​​obtained by concatenating the first and last lines of each unitary spacetime modulation signal matrix and repeating them line by line.

[0014] The first signal matrix is ​​phase-shifted, and the real part of each column element is sequentially shifted upward by one unit to obtain the offset quadrature phase shift keying signal.

[0015] In one embodiment of the present invention, converting the offset quadrature phase shift keying signal into a continuous phase modulation signal includes:

[0016] The offset quadrature phase shift keying signal is subjected to pulse shaping processing to obtain the continuous phase modulation signal.

[0017] In one embodiment of the present invention, the present invention also provides a unitary spacetime demodulation method, comprising:

[0018] The continuous phase modulation signal is converted into an offset quadrature phase shift keying signal, and the offset quadrature phase shift keying signal is converted into a unitary spacetime modulation signal;

[0019] Based on the unitary spacetime modulation signal constellation set, the unitary spacetime modulation signal is demodulated in a unitary spacetime manner to obtain the target data; the first signal in the modulation signal constellation set is generated based on the Hadamard matrix.

[0020] In one embodiment of the present invention, a unitary spacetime modulation device is also provided, comprising:

[0021] The modulation module is used to perform unitary space-time modulation on the transmitted signal based on a unitary space-time modulation signal constellation set to obtain a unitary space-time modulated signal; the first signal in the modulation signal constellation set is generated based on the Hadamard matrix.

[0022] The first conversion module is used to convert the unitary spacetime modulation signal into an offset quadrature phase shift keying signal, and the offset quadrature phase shift keying signal into a continuous phase modulation signal.

[0023] In one embodiment of the present invention, a spacetime demodulation device is also provided, comprising:

[0024] The second conversion module is used to convert the continuous phase modulation signal into an offset quadrature phase shift keying signal, and the offset quadrature phase shift keying signal into a unitary spacetime modulation signal;

[0025] The demodulation module is used to demodulate the unitary space-time modulated signal based on the unitary space-time modulated signal constellation set to obtain the target data; the first signal in the modulated signal constellation set is generated based on the Hadamard matrix.

[0026] 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 spacetime modulation or demodulation methods.

[0027] 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 spacetime modulation or demodulation methods.

[0028] 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 spacetime modulation or demodulation methods.

[0029] Compared with existing technologies, the beneficial effects of the unitary space-time modulation and demodulation method, apparatus, electronic device, and storage medium according to the present invention are as follows: By constructing the first signal of the USTM constellation set based on the orthogonality of the Hadamard matrix, generating the complete constellation set through diagonal matrix design, and finally achieving signal phase continuity through constant envelope processing, the peak-to-average power ratio (PAPR) can be significantly reduced. Compared with the traditional STBC scheme, its PAPR can be reduced to 0dB, effectively solving the problem of nonlinear distortion in high-power amplifiers. Furthermore, this scheme has a slight improvement in bit error rate performance compared with traditional schemes, and its signal characteristics are highly similar to MSK signals, possessing strong anti-identification capabilities, providing a new approach for the design of wireless communication systems with higher reliability and confidentiality requirements. Attached Figure Description

[0030] Figure 1 is a schematic flowchart of a unitary spacetime modulation method according to an embodiment of the present invention;

[0031] Figure 2 is a schematic flowchart of a spacetime demodulation method according to an embodiment of the present invention;

[0032] Figure 3 is a schematic diagram of the real and imaginary part waveforms of the first column of transmitted signals obtained by the unitary space-time modulation method according to an embodiment of the present invention.

[0033] Figure 4 is a schematic diagram of the real and imaginary waveforms of the second column of transmitted signals obtained by the unitary space-time modulation method according to an embodiment of the present invention.

[0034] Figure 5 is a schematic diagram of the real and imaginary waveforms of the first transmitted signal recovered by the unitary space-time demodulation method according to an embodiment of the present invention.

[0035] Figure 6 is a schematic diagram of the real and imaginary waveforms of the second transmitted signal recovered by the unitary space-time demodulation method according to an embodiment of the present invention;

[0036] Figure 7 is a schematic diagram of the signal transmission flow of the unitary space-time modulation and demodulation method according to an embodiment of the present invention;

[0037] Figure 8 is a schematic diagram of the bit error rate performance of the unitary space-time modulation and demodulation method according to an embodiment of the present invention.

[0038] Figure 9 is a schematic diagram of the structure of a spacetime modulation device according to an embodiment of the present invention;

[0039] Figure 10 is a schematic diagram of the structure of a spacetime modulation device according to an embodiment of the present invention.

[0040] Figure 11 is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] As shown in Figures 1 to 11, the spacetime modulation and demodulation method, apparatus, electronic device and storage medium according to the preferred embodiments of the present invention can be implemented in the following ways.

[0044] Figure 1 is a schematic flowchart of a unitary spacetime modulation method according to an embodiment of the present invention. As shown in Figure 1, the method may include the following steps:

[0045] Step 101: Based on the unitary space-time modulation signal constellation set, perform unitary space-time modulation on the target data to obtain the unitary space-time modulation signal; the first signal in the modulation signal constellation set is generated based on the Hadamard matrix.

[0046] Step 102: Convert the unitary time-time modulation signal into an offset quadrature phase shift keying signal, and then convert the offset quadrature phase shift keying signal into a continuous phase modulation signal.

[0047] In a MIMO wireless transmission system, let the channel coherence time be... That is, in The channel fading coefficient remains constant within one symbol period, and in the next group... Within each symbol period, the channel fading coefficient independently changes to another value, and the average signal-to-noise ratio at the receiver is... Data rate Bits / symbols, number of transmit and receive antennas are respectively and ,but Transmit signal , Received signal The relationship between them is

[0048] (1).

[0049] in, for Fading coefficient, for Additive noise.

[0050] USTM originated from incoherent space-time codes, requiring no channel estimation at either the transmitting or receiving end of the channel, making it suitable for Rayleigh flat-fading channels with rapidly changing fading coefficients. However, research has shown that USTM is also applicable when channel estimation is already available at the receiver, offering a much wider range of signal types and higher diversity gain compared to STBC. The definition of USTM is...

[0051] (2).

[0052] in, for unitary matrix, that is, The number of signals in the constellation set is .

[0053] Let the UST matrix corresponding to symbol 0 be ,but and The correspondence is

[0054] (3).

[0055] in, At the receiver, when there is no channel estimation at either the transmitting or receiving end, the maximum likelihood detection criterion is:

[0056] (4).

[0057] When the receiver has a channel estimate, the maximum likelihood detection criterion is:

[0058] (5).

[0059] Design criteria for incoherent USTM signals generally include: diversity sum criterion and diversity product criterion. For a channel coherence time of... Data rate The unitary spacetime modulation, the number of signals concentrated in the constellation is These matrices need to ensure a low error rate in the transmission system. There are two main design criteria for unitary spacetime signals: diversity sum criterion and diversity product criterion.

[0060] Diversity sum is defined as the maximum correlation between a pair of unitary spacetime signals, i.e.

[0061] (6).

[0062] in, , , for The first singular value decomposition A singular value, The diversity sum is related to the sum of singular values ​​of the correlation matrix. The diversity sum criterion requires that the design of unitary spacetime constellations make... The value should be as small as possible. Diversity and criterion are among the most widely used design principles due to their simplicity and intuitiveness.

[0063] The product of subsets is defined as

[0064] (7).

[0065] The diversity product is related to the product of the singular values ​​of the correlation matrix. The diversity product criterion requires that the design of the unitary spacetime constellation... The value should be as large as possible. Since maximizing the product of subsets ensures full subset division, it is more efficient to use the sum of subsets.

[0066] For a USTM signal designed based on a DFT matrix, the relationship between the transmitted signal matrix and the unitary matrix using unitary space-time modulation can be expressed as follows:

[0067] (8)

[0068] in, . It can be derived from the first unitary spacetime signal Generated in the following way

[0069] (9)

[0070] diagonal array It can be represented as

[0071] (10)

[0072] Among them, the function This represents converting a vector into the diagonal elements of a diagonal matrix. , . for The front of the DFT matrix Column divided by .

[0073] For any , ,have

[0074] (11).

[0075] Considering The above formula is equivalent to applying any beg Therefore, the unitary spacetime signal search based on the DFT matrix is ​​optimized as follows:

[0076] (12).

[0077] in, .

[0078] The design of unitary space-time signals based on DFT matrices has good error performance and wide applications, but it is difficult to simplify the detection complexity, and it loses its practical value when the number of signals in the constellation is too large.

[0079] The advantage of using the generalized PSK concept is that it is applicable to any number of transmit antennas and the mapping and detection are relatively simple. However, the disadvantages are that there are fewer types of constellation sets and the reliability is relatively worse the more transmit antennas there are. In addition, the peak-to-average power ratio is caused by the fact that there are only two non-zero symbols in the coherence time.

[0080] For a USTM signal designed based on a generalized PSK matrix, the unitary spacetime signal is:

[0081] (13).

[0082] in, .

[0083] The advantage of using an STBC matrix is ​​that it eliminates the need to search for an optimal constellation and simplifies detection. The disadvantage is its lack of flexibility in adapting to the number of transmit antennas and channel coherence time. In this design, the transmitted signal is...

[0084] (14).

[0085] in, This is an STBC encoding matrix, applicable to both real and complex signals. Because... Only on the diagonal A non-zero element, in order to make The total power is ,have

[0086] (15).

[0087] Currently, all USTM signals, including the aforementioned mainstream schemes, are symbol-level unitary matrices, with the F-norm of each column being 1. In some schemes, the magnitudes of the symbols within the matrix are not even fixed. Even with fixed symbol magnitudes, they still exhibit a high peak-to-average power ratio (PAPR) after low-pass filtering.

[0088] In some feasible implementations, the transmitted signal is subjected to unitary space-time modulation based on a unitary space-time modulation signal constellation set to obtain a unitary space-time modulated signal, including:

[0089] Determine the unitary matrix corresponding to the transmitted signal in the unitary spacetime modulation signal constellation set;

[0090] The unitary space-time modulated signal is obtained based on the unitary matrix and the channel coherence time.

[0091] The target data is the bit group obtained by grouping the source bits. We can first determine the unitary matrix corresponding to each bit group in the unitary spacetime modulation signal constellation set by searching.

[0092] A Hadamard matrix is ​​a square matrix consisting of 1s and -1s, where any two rows or columns are orthogonal, meaning their inner product is 0. If... Hadamard matrix of order If it exists, then its determinant value is or Currently known The possible values ​​of are all multiples of 1, 2 or 4, but the proof is not yet complete.

[0093] When the order of the Hadamard matrix is ​​an integer power of 2, it can be constructed recursively, using a 2-order matrix as a base and generating higher-order matrices through a block-based method.

[0094] (16).

[0095] The following are several types of Hadamard matrices involved in this invention:

[0096] when Sometimes,

[0097] (17).

[0098] when Sometimes,

[0099] (18).

[0100] when Sometimes,

[0101] (19).

[0102] The overall design concept of USTM signals based on Hadamard matrices is similar to that based on DFT matrices, with the core improvement being the use of Hadamard matrices instead of DFT matrices to generate signals. The row number of the Hadamard matrix corresponds to the channel coherence time. Choose from them Columns and multiply As the first USTM constellation point .

[0103] The USTM signal constellation is clustered, and the relationship between any signal and the first signal is as follows:

[0104] (20).

[0105] diagonal array for

[0106] (twenty one).

[0107] Due to unitary matrix With the transmitted signal matrix The difference between the matrices representing the unitary time-modulated signal and the matrix lies only in the coefficients. Therefore, the optimal values ​​of the two are equivalent. Using exhaustive search to complete one search of equation (12), the internal optimization requires finding... Secondary matrix multiplication, while external optimization requires The internal optimization. It can be seen that the computational complexity of the exhaustive search method increases with... It increases exponentially. When When the value is small, it can be achieved by adjusting the vector. Exhaustive search yields the optimal set of constellations, but when When the value is large, exhaustive search becomes insufficient. In this case, random search is a feasible method. Although random search cannot guarantee that it will be the optimal constellation, it can help by observing smaller values. The search for values ​​reveals that the equivalent... There are multiple optimal combinations, and random search can still find combinations very close to the optimal one with a high probability. combination.

[0108] When the receiver has access to the channel estimate, the search algorithm for the coherent UST signal is shown in the table below.

[0109] Table 1 Search algorithm for coherent UST signals

[0110]

[0111] When searching for the optimal UST signal, the parameters are first initialized according to the requirements. , , Find ,make The matrix corresponding to the symbol 0, i.e. DFT matrix column multiplied by Let the initial distance be... And set the distance of the first round of search to be .

[0112] Let vector Its components are all random integers, and in They follow a uniform distribution. (Based on vectors) Generate a diagonal matrix . use Generate all metrics

[0113] (32).

[0114] in, for The diagonal elements of the diagonal matrix obtained by SVD decomposition. Let the distance value be...

[0115] (33)

[0116] if If so, continue the loop search; if Then Value update The value is used as the new initial metric. The above process is repeated until it is difficult to find a new metric, at which point the loop ends.

[0117] The USTM signal designed using the Hadamard matrix is ​​suitable for any data rate. However, it is not a constant envelope signal.

[0118] Table 2. u-values ​​of the UST signal when R=1 / 2 and T=4

[0119]

[0120] Table 3. u-values ​​of the UST signal when R=1 / 4 and T=8

[0121]

[0122] Table 4. u-values ​​of the UST signal when R=1 / 8 and T=16

[0123]

[0124] The three tables above provide several... of Value vector. When hour, Only when Constant envelope transformation is possible only when the product is 1 or 2. When the product is less than 1, a constellation set cannot be generated; when When the product is greater than 2, a USTM constellation set can be generated, but it is difficult to achieve constant envelope.

[0125] Converting the unitary time-time modulation signal into an offset quadrature phase shift keying signal, and then converting the offset quadrature phase shift keying signal into a continuous phase modulation signal, allows for constant envelope conversion of the USTM signal.

[0126] First, the USTM signal is converted into an OQPSK signal to avoid the signal crossing zero; then the OQPSK signal is converted into a CPM signal to fix the signal envelope.

[0127] Continuous phase modulation (CPM) is a type of constant envelope modulation that has advantages such as low peak-to-average power ratio, concentrated spectrum, and good sidelobe suppression.

[0128] For a given channel coherence time Its value is an integer power of 2. Set the row number corresponding to the number of rows in the Hadamard matrix. ,satisfy It is an integer power of 2. Extracted from this Hadamard matrix. At the same time, it can produce This leads to the generation of the entire USTM signal matrix constellation set.

[0129] The general expression for a CPM modulated signal is [5].

[0130] (26).

[0131] in, The modulation index; The periodicity of the symbol is usually normalized to the dimensionless 1; For data symbols; The phase response function can be derived from the frequency response function. It comes from points, that is

[0132] (27).

[0133] in, The domain is ,in This refers to the length of the memory.

[0134] Based on Laurent's decomposition principle, the CPM signal can be represented as

[0135] (28).

[0136] in, Complex coefficients are

[0137] (29).

[0138] The real basis impulse function is

[0139] (30)

[0140] in, .function The definition of

[0141] (31).

[0142] parameter It takes the value 0 or 1. Specifically, The value is always 0. For any , for The radix-2 vector representation of the first bits, that is

[0143] (32).

[0144] in, .

[0145] Analysis reveals that, through Laurent decomposition, the energy of the second-order CPM signal is mainly concentrated in the first pulse.

[0146] (33)

[0147] Especially for the full response signal, which has only one pulse, there is

[0148] (34).

[0149] There are several precoding schemes for second-order CPM, but the simplest method for receiver processing is...

[0150] (35)

[0151] This precoding allows the receiver to demodulate the signal in the BPSK manner.

[0152] In practical applications of fully-response CPM signals, the above process can be further simplified. First, the source bits are converted into bipolar symbols. Multiply this bipolar symbol sequence by... , The result of multiplication is alternately placed in the imaginary and real parts of the signal to obtain a constant envelope modulated signal.

[0153] In some feasible implementations, the unitary spacetime modulation signal is converted into an offset quadrature phase shift keying signal, including:

[0154] The target data is converted into a symbol vector, and for each symbol in the symbol vector, the corresponding unitary space-time modulation signal matrix is ​​determined based on the unitary space-time modulation signal.

[0155] The first signal matrix is ​​obtained by concatenating the first and last links of each unitary spacetime modulation signal matrix and repeating them row by row.

[0156] The first signal matrix is ​​phase-shifted, and the real part of each column element is cyclically shifted upward by one unit to obtain the offset quadrature phase shift keying signal.

[0157] In some feasible implementations, converting the offset quadrature phase shift keying signal into a continuous phase modulation signal includes:

[0158] Pulse shaping processing is performed on the offset quadrature phase shift keying signal to obtain a continuous phase modulation signal.

[0159] When using it, first make the length of The source bit group is converted into a length The higher-order symbol vector is obtained by selecting a corresponding USTM signal matrix (unitary spacetime modulation signal matrix) for each symbol and concatenating the USTM signal matrices end-to-end according to the symbol order. The signal matrix (i.e., the first signal matrix). Repeating this signal matrix row by row yields a new one. The signal matrix (i.e., the unitary spacetime modulation signal matrix). Multiply this new matrix by... Then, the real parts of each column element are sequentially shifted upwards by one unit to obtain the new... Signal matrix. The signals in this matrix exhibit OQPSK characteristics, meaning the phase difference between adjacent symbols is... .

[0160] The signals after the above real-part cyclic shifting process are then subjected to pulse shaping. The real part of each signal is multiplied by... Imaginary part multiplied by function , Defined by equation (31), where the memory length is The resulting signal exhibits phase continuity and displays characteristics of an MSK signal in both the time and frequency domains.

[0161] Figure 2 is a flowchart illustrating a unitary spacetime demodulation method according to an embodiment of the present invention. As shown in the figure, the method may include the following steps:

[0162] Step 201: Convert the continuous phase modulation signal into an offset quadrature phase shift keying signal, and convert the offset quadrature phase shift keying signal into a unitary spacetime modulation signal;

[0163] Step 202: Based on the unitary space-time modulation signal constellation set, perform unitary space-time demodulation on the unitary space-time modulation signal to obtain the target data; the first signal in the modulation signal constellation set is generated based on the Hadamard matrix.

[0164] Assuming the receiver can obtain accurate channel estimation, the OQPSK signal can be recovered from the continuous phase signal generated by the unitary space-time modulation method of any of the aforementioned embodiments after channel compensation. The real parts of the two signal columns are cyclically shifted one unit in the reverse direction, then merged in steps of two rows, and the new matrix is ​​multiplied by... Perform maximum likelihood detection on the signal matrix at this point, and convert the decimal number to binary bits to obtain the decision bit sequence.

[0165] Due to data rate The value is usually less than 1, so this signal mapping can be regarded as a spread spectrum method.

[0166] The modulation and demodulation principle of the invention embodiment is illustrated below with a simple example. Let... , , The number of signal matrices in the constellation set is , respectively

[0167] , , and .

[0168] If the source data is 0011, then the original transmitted signal matrix is:

[0169] .

[0170] Repeat it line by line, with phase rotation Then, the real parts of each column are cyclically shifted upwards by one unit, resulting in...

[0171] , and .

[0172] The signal is then shaped to obtain the constant envelope signal (i.e., the CPM signal).

[0173] Figure 3 shows the real and imaginary waveforms of the first column of transmitted signals, and Figure 4 shows the real and imaginary waveforms of the second column of transmitted signals. It is easy to see that the signal envelope is constant at 1, the phase is continuous, and both exhibit MSK characteristics. From a signal recognition perspective, this signal is easily misidentified as a normal MSK signal.

[0174] Figure 5 shows the real and imaginary waveforms of the recovered signals in the first column, and Figure 6 shows the real and imaginary waveforms of the recovered signals in the second column. It is easy to see that the signals exhibit OQPSK characteristics.

[0175] Figure 7 illustrates the general transmission flow of the constant enveloped USTM signal in a MIMO wireless channel. This flow is the same as the traditional USTM signal transmission flow, with the main difference being the signal mapping method.

[0176] Figure 8 shows the bit error rate performance of the embodiment of the present invention and the traditional STBC. It is assumed that the receiver can obtain an accurate channel estimate, and the channel coherence time is... That is, the channel remains constant for at least 8 symbol periods, and the number of transmit and receive antennas is... , , Total data rate Bit / symbol period. In contrast, STBC employs the classic Alamouti orthogonal coding scheme, BPSK modulation, and 4x repetition. It can be seen that, under the same transmission efficiency, the proposed scheme has a slightly better bit error rate performance than the traditional STBC scheme.

[0177] Additionally, assuming the matched filter parameters are commonly used... If the extended symbol is 6, the peak-to-average power ratio (PAPR) of the BPSK signal exceeds 4 dB, while the PAPR of the proposed scheme is 0 dB. This means that the effective transmission distance of the embodiment of the present invention significantly exceeds that of the traditional STBC scheme.

[0178] The beneficial effects of this invention are that by constructing the first signal of the USTM constellation set based on the orthogonality of the Hadamard matrix, generating the complete constellation set through diagonal matrix design, and finally achieving signal phase continuity through constant envelope processing, the peak-to-average power ratio (PAPR) can be significantly reduced. Compared with the traditional STBC scheme, its PAPR can be reduced to 0dB, effectively solving the problem of nonlinear distortion in high-power amplifiers. Furthermore, this scheme slightly improves bit error rate performance compared to traditional schemes, and its signal characteristics are highly similar to MSK signals, possessing strong anti-identification capabilities. This provides a new approach for the design of wireless communication systems with higher reliability and security requirements.

[0179] This invention achieves fundamental innovation in signal design, breaking through the design framework of traditional DFT matrices, generalized PSK, or STBC matrices. It innovatively applies the orthogonality of the Hadamard matrix to the construction of the head signal of the USTM constellation set. Utilizing the orthogonality of any two rows or columns of the Hadamard matrix, a superior orthogonal foundation is laid for USTM signal design, enhancing performance potential from the very source of signal design.

[0180] This invention achieves innovative peak-to-average power ratio (PAPR) optimization. A unique diagonal matrix design generates a complete constellation set, and constant envelope processing is performed on this set to ensure signal phase continuity. This innovation significantly reduces the PAPR to 0 dB, completely resolving the PAPR issue inherent in traditional schemes caused by low-pass filtering of the symbol-level unitary matrix. This substantially improves the efficiency of the power amplifier and the signal transmission quality.

[0181] Current space-time signals, whether STBC or USTM, are essentially discrete signals with discontinuous phases. After low-pass filtering at the transmitting end, the envelope is no longer constant and exhibits a high peak-to-average power ratio. The embodiments of this invention can make the space-time signal envelope constant, achieving constant envelope for the space-time modulated signal, and under the same rated transmit power, can support at least 1.5 times the communication distance.

[0182] Current CPM signals, after forced space-time coding, struggle to guarantee the orthogonality of space-time codewords. This invention employs orthogonal space-time coding of CPM signals, ensuring the orthogonality of space-time codewords while maintaining a constant envelope, thereby preserving diversity gain.

[0183] Current CPM signals are too obvious and lack any concealment; even current USTM signals have seen a significant decrease in concealment after worldwide research. This invention reduces the signal-to-noise ratio through its own spread spectrum mechanism and employs a novel design to make the signal exhibit CPM characteristics, thus concealing the signal features. This design makes it extremely easy for the detection party to misinterpret the signal of this invention as a conventional CPM signal, resulting in demodulation failure.

[0184] This invention achieves innovative signal characteristics, with the modulated signal exhibiting characteristics highly similar to Minimum Shift Keying (MSK) in the time-frequency domain. This similarity endows the signal with strong anti-identification capabilities, making it difficult to be easily identified and analyzed during communication, thus providing new technical ideas and advantages for the design of high-reliability, low-power wireless communication systems.

[0185] This invention innovates the constant envelope processing flow by proposing a systematic constant envelope processing procedure. First, the USTM signal is converted into an OQPSK signal to avoid zero crossings, and then further converted into a CPM signal to fix the signal envelope. This process, through a series of processing steps such as phase rotation, real part cyclic shifting, and pulse shaping, ensures the constancy of the signal envelope and the continuity of the phase, which is a key innovative step in achieving a low peak-to-average power ratio.

[0186] The following describes the unitary spacetime modulation device provided by the present invention. The unitary spacetime modulation device described below can be referred to in correspondence with the unitary spacetime modulation method described above.

[0187] Figure 9 is a schematic diagram of the structure of the unitary spacetime modulation device provided by the present invention. Based on any of the above embodiments, as shown in Figure 9, the device includes a modulation module 901 and a first conversion module 902, wherein:

[0188] Modulation module 901 is used to perform unitary space-time modulation on the transmitted signal based on the unitary space-time modulation signal constellation set to obtain the unitary space-time modulation signal;

[0189] The first conversion module 902 is used to convert the unitary spacetime modulation signal into an offset quadrature phase shift keying signal and convert the offset quadrature phase shift keying signal into a continuous phase modulation signal.

[0190] The unitary spacetime modulation apparatus provided in this embodiment of the invention is used to execute the unitary spacetime modulation method described above. Its implementation method is consistent with that of the unitary spacetime modulation method provided by this invention, and it can achieve the same beneficial effects. It will not be described again here.

[0191] The unitary spacetime modulation device is used in the unitary spacetime modulation methods of the foregoing embodiments. Therefore, the descriptions and definitions in the unitary spacetime modulation methods of the foregoing embodiments can be used to understand the execution modules in the embodiments of the present invention.

[0192] The following describes the spacetime demodulation device provided by the present invention. The spacetime demodulation device described below and the spacetime demodulation method described above can be referred to in correspondence.

[0193] Figure 10 is a schematic diagram of the structure of the spacetime demodulation device provided by the present invention. Based on any of the above embodiments, as shown in Figure 10, the device includes a second conversion module 1001 and a demodulation module 1002, wherein:

[0194] The second conversion module 1001 is used to convert the continuous phase modulation signal into an offset quadrature phase shift keying signal, and to convert the offset quadrature phase shift keying signal into a unitary spacetime modulation signal.

[0195] The demodulation module 1002 is used to demodulate the unitary space-time modulated signal based on the unitary space-time modulated signal constellation set to obtain the target data; the first signal in the modulated signal constellation set is generated based on the Hadamard matrix.

[0196] The unitary spacetime demodulation device provided in this embodiment of the invention is used to execute the unitary spacetime demodulation method described above. Its implementation method is consistent with the implementation method of the unitary spacetime demodulation method provided by this invention, and it can achieve the same beneficial effects. It will not be described again here.

[0197] The unitary spacetime demodulation device is used in the unitary spacetime demodulation methods of the foregoing embodiments. Therefore, the descriptions and definitions in the unitary spacetime demodulation methods of the foregoing embodiments can be used to understand the execution modules in the embodiments of the present invention.

[0198] Figure 11 illustrates a schematic diagram of the physical structure of an electronic device. As shown in Figure 11, the electronic device may include: a processor 1110, a communications interface 1120, a memory 1130, and a communication bus 1140, wherein the processor 1110, the communications interface 1120, and the memory 1130 communicate with each other through the communication bus 1140. Processor 1110 can call logic instructions in memory 1130 to execute a unitary space-time modulation method, which includes: performing unitary space-time modulation on target data based on a set of unitary space-time modulation signal constellations to obtain a unitary space-time modulation signal; the first signal in the modulation signal constellation set is generated based on a Hadamard matrix; converting the unitary space-time modulation signal into an offset quadrature phase shift keying (OPSK) signal, and converting the OPSK signal into a continuous phase modulation signal; or including: converting the continuous phase modulation signal into an OPSK signal, and converting the OPSK signal into a unitary space-time modulation signal; performing unitary space-time demodulation on the unitary space-time modulation signal based on the set of unitary space-time modulation signal constellations to obtain target data; the first signal in the modulation signal constellation set is generated based on a Hadamard matrix.

[0199] Furthermore, the logical instructions in the aforementioned memory 1130 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, in essence, 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.

[0200] The processor 1110 in the electronic device provided in this embodiment of the invention can call the logic instructions in the memory 1130. Its implementation method is consistent with the implementation method of the unitary space-time modulation method provided in this invention, and can achieve the same beneficial effects. It will not be described again here.

[0201] 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 unitary space-time modulation method provided by the above methods, the method comprising: performing unitary space-time modulation on target data based on a set of unitary space-time modulation signal constellations to obtain a unitary space-time modulation signal; the first signal in the modulation signal constellation set is generated based on a Hadamard matrix; converting the unitary space-time modulation signal into an offset quadrature phase shift keying signal, and converting the offset quadrature phase shift keying signal into a continuous phase modulation signal; or comprising: converting the continuous phase modulation signal into an offset quadrature phase shift keying signal, and converting the offset quadrature phase shift keying signal into a unitary space-time modulation signal; performing unitary space-time demodulation on the unitary space-time modulation signal based on a set of unitary space-time modulation signal constellations to obtain target data; the first signal in the modulation signal constellation set is generated based on a Hadamard matrix.

[0202] When the computer program product provided in this embodiment of the invention is executed, it implements the above-described unitary spacetime modulation method. 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.

[0203] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the aforementioned unitary space-time modulation methods. The method includes: performing unitary space-time modulation on target data based on a set of unitary space-time modulation signal constellations to obtain a unitary space-time modulated signal; the first signal in the modulation signal constellation set is generated based on a Hadamard matrix; converting the unitary space-time modulated signal into an offset quadrature phase-shift keying (OPSK) signal, and converting the OPSK signal into a continuous phase modulation signal; or including: converting the continuous phase modulation signal into an OPSK signal, and converting the OPSK signal into a unitary space-time modulated signal; performing unitary space-time demodulation on the unitary space-time modulated signal based on the set of unitary space-time modulation signal constellations to obtain target data; the first signal in the modulation signal constellation set is generated based on a Hadamard matrix.

[0204] 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-described unitary spacetime modulation method. 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.

[0205] 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.

[0206] 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, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0207] 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 that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0208] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0209] 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.

[0210] 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 unitary spacetime modulation method, characterized in that, include: Based on the constellation set of unitary space-time modulation signals, the target data is modulated using unitary space-time modulation to obtain the unitary space-time modulation signal; The first signal in the modulation signal constellation set is generated based on the Hadamard matrix; the unitary spacetime modulation signal is converted into an offset quadrature phase shift keying signal, and the offset quadrature phase shift keying signal is converted into a continuous phase modulation signal.

2. The unitary spacetime modulation method according to claim 1, characterized in that, The method of performing unitary space-time modulation on the transmitted signal based on the unitary space-time modulation signal constellation set to obtain the unitary space-time modulation signal includes: determining the unitary matrix corresponding to the transmitted signal in the unitary space-time modulation signal constellation set; and obtaining the unitary space-time modulation signal based on the unitary matrix and the channel coherence time.

3. The unitary spacetime modulation method according to claim 1 or 2, characterized in that, The step of converting the unitary space-time modulation signal into an offset quadrature phase-shift keying signal includes: converting the target data into a symbol vector, and for each symbol in the symbol vector, determining the unitary space-time modulation signal matrix corresponding to the symbol based on the unitary space-time modulation signal; concatenating the first and last of each unitary space-time modulation signal matrix and repeating it row by row to obtain a first signal matrix; performing phase shift processing on the first signal matrix and sequentially shifting the real part of each column element upward by one unit to obtain the offset quadrature phase-shift keying signal.

4. The unitary spacetime modulation method according to claim 3, characterized in that, The step of converting the offset quadrature phase shift keying signal into a continuous phase modulation signal includes: performing pulse shaping processing on the offset quadrature phase shift keying signal to obtain the continuous phase modulation signal.

5. A method for demodulating unitary time-space, characterized in that, include: The continuous phase modulation signal is converted into an offset quadrature phase shift keying signal, and the offset quadrature phase shift keying signal is converted into a unitary spacetime modulation signal; Based on the constellation set of unitary space-time modulated signals, unitary space-time demodulation is performed on the unitary space-time modulated signals to obtain the target data; The first signal in the modulation signal constellation set is generated based on the Hadamard matrix.

6. A spacetime modulation device, characterized in that, include: The modulation module is used to perform unitary space-time modulation on the transmitted signal based on the unitary space-time modulation signal constellation set to obtain the unitary space-time modulated signal. The first signal in the modulation signal constellation set is generated based on the Hadamard matrix; The first conversion module is used to convert the unitary spacetime modulation signal into an offset quadrature phase shift keying signal, and the offset quadrature phase shift keying signal into a continuous phase modulation signal.

7. A spacetime demodulation device, characterized in that, include: The second conversion module is used to convert the continuous phase modulation signal into an offset quadrature phase shift keying signal, and the offset quadrature phase shift keying signal into a unitary spacetime modulation signal; The demodulation module is used to demodulate the unitary space-time modulated signal based on the unitary space-time modulated signal constellation set to obtain the target data; The first signal in the modulation signal constellation set is generated based on the Hadamard matrix.

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 unitary space-time modulation method as described in any one of claims 1 to 4, or the steps of the unitary space-time modulation method as described in claim 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 unitary space-time modulation method as described in any one of claims 1 to 4, or the steps of the unitary space-time modulation method as described in claim 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 unitary space-time modulation method as described in any one of claims 1 to 4, or the steps of the unitary space-time modulation method as described in claim 5.

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