A receiving end physical phase tilt CPM signal processing method, device and equipment

Abstract

The application discloses a CPM modulation signal processing method, device and equipment of physical tilt phase at a receiving end, relates to communication technology, and comprises the following steps: acquiring a receiving signal; performing filtering sampling, frequency offset compensation and phase compensation processing on the receiving signal to obtain a compensation signal sequence; calculating a phase tilt value; performing physical tilt phase processing on the compensation signal sequence by using the calculated phase tilt value; and performing demodulation on the signal sequence after the physical tilt phase processing to extract an original signal sequence. The method of the application solves the problem of the mismatch between the signal at the sending end and the filter center frequency at the receiving end by performing physical tilt phase processing on the signal at the receiving end without increasing the symbol overhead, thereby reducing the signal loss and improving the demodulation performance of the signal.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a method, apparatus and device for processing CPM signals with physical phase tilt at the receiving end. Background Technology

[0002] Continuous phase modulation (CPM), as a highly efficient modulation technique, features constant envelope and continuous phase. The instantaneous carrier frequency or phase of a CPM signal contains all the information of the data signal. Due to the phase memory characteristic of CPM, the carrier phase is continuous in time, thus avoiding spectral jumps and resulting in a concentrated power spectral density and low out-of-band power. Furthermore, the constant envelope characteristic of CPM signals enables them to perform well in fading channels and allows for processing by nonlinear amplifiers.

[0003] In his 1988 paper, "Adecomposition approach to CPM," B. Rimoldi conducted a fundamental analysis of continuous phase modulation (CPM) using a decomposition method, breaking down complex CPM signals into simpler components. This decomposition technique is crucial for understanding and simplifying the complexity of CPM signals.

[0004] Based on Rimoldi decomposition technology, in order to ensure that the system maintains the time-invariant network structure during demodulation and reduce demodulation complexity, traditional methods usually perform physical phase tilting processing on the CPM signal during modulation at the transmitting end.

[0005] Patent application CN201710952229 proposes a physical layer network coding method based on continuous phase modulation (CPM). This method applies a physical phase tilt to the CPM signal during modulation at the transmitting end. However, this method has a significant drawback. The center frequency of the receiver's filter is typically set to the center frequency of the transmitted signal. When a phase tilt is applied to the signal at the transmitting end, the center frequency of the transmitted signal shifts, causing a mismatch with the center frequency of the receiver's filter. Due to this frequency mismatch, some spectral energy of the received signal is lost, leading to a deterioration in the received signal quality and ultimately affecting demodulation performance. Summary of the Invention

[0006] This application provides a method, apparatus, and device for processing CPM modulated signals with physical phase tilt at the receiving end, aiming to optimize the demodulation and processing of CPM signals at the receiving end and improve the performance and robustness of the communication system.

[0007] This application provides a method for processing CPM (Current Phase Tilt) signals at a receiver, including:

[0008] The received signal is obtained by transmitting the signal generated at the transmitting end by standard CPM modulation of the encoded signal sequence and adding a synchronization header through the channel to the receiving end.

[0009] The received signal is subjected to filtering, sampling, frequency offset compensation, and phase compensation processing to obtain a compensated signal sequence;

[0010] Calculate the phase tilt value, and use the calculated phase tilt value to perform physical phase tilt processing on the compensation signal sequence;

[0011] The signal sequence after physical phase tilting is demodulated to extract the original signal sequence.

[0012] This application embodiment also provides a CPM modulation signal processing apparatus for physically tilting the phase at the receiving end, including a processor and a memory. The memory stores a computer program, and when the computer program is executed by the processor, it implements the steps of the aforementioned CPM modulation signal processing method for physically tilting the phase at the receiving end.

[0013] This application embodiment also provides a receiving device, including a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, it implements the steps of the CPM modulation signal processing method with physical tilt phase at the receiving end as described above.

[0014] This application proposes a CPM modulation signal processing method that physically tilts the phase at the receiving end. By physically tilting the phase of the signal at the receiving end, this method solves the problem of mismatch between the center frequency of the transmitting signal and the receiving filter without increasing symbol overhead, thereby reducing signal loss and improving demodulation performance.

[0015] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0017] Figure 1 This is a schematic diagram of the basic flow of the CPM modulation signal processing method in the embodiments of this application;

[0018] Figure 2 This is a schematic diagram of the communication system used in the CPM modulation signal processing method of this application embodiment;

[0019] Figure 3 This is a flowchart illustrating an implementation example of the CPM modulation signal processing method in this application.

[0020] Figure 4 This is an ML mesh diagram of an even / odd time segment after physical tilt phase processing at the receiving end, as described in the embodiments of this application.

[0021] Figure 5 The figures show a comparison of the bit error rate performance simulations using the method described in this application and under ideal conditions (no frequency offset or phase offset). Detailed Implementation

[0022] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0023] This application provides a method for processing physically tilted phase (CPM) signals at the receiver. The method is used to physically tilt the phase at the receiver. Figure 1 As shown, it includes the following steps:

[0024] In step S101, a received signal is acquired. This received signal is a transmitted signal generated at the transmitting end by performing standard CPM modulation on the encoded signal sequence and adding a synchronization header, then transmitted through the channel to the receiving end. The communication system used in this application embodiment, such as... Figure 2 As shown, in some embodiments, the received signal is specifically transmitted at the transmitting end in the following manner:

[0025] Generate a random input sequence α = [α0, α1, ..., α N-1 ], α i ∈{±1,±3,...,±(M-1)}(i=0,1,...,N-1); where N is the length of the signal sequence and M is the base number.

[0026] The input sequence α is subjected to standard CPM modulation, and the CPM modulation signal is s. c (t,α)=Ae jφ(t,α) , where A is the signal amplitude, t is time, and φ(t,α) is the phase function.

[0027] For the nth symbol interval, t∈[nT,(n+1)T], the phase function is defined as:

[0028]

[0029] Where T is the symbol interval, h is called the modulation index, L is the phase constraint length of the CPM signal, and θ n The cumulative phase is q(t). The function q(t) is called the phase pulse.

[0030] Let all symbols before time 0 carry no information and not participate in the calculation of the accumulated phase. Symbols before time -1 are all 0, which are invalid symbols and carry no information. Symbols at time -1 are not zero and are only used to affect the initial phase of the system. Therefore, θ... n The accumulated phase is:

[0031]

[0032] modulated signal s c (t,α) becomes the transmitted signal s(t) after adding a synchronization header. The transmitted signal s(t) is sent to the receiving end through the channel. The synchronization header is a signal obtained by MSK modulation of the pseudo-random sequence.

[0033] Noise exists when transmitting signals through a channel:

[0034] When the transmitted signal s(t) passes through the channel, the signal will be contaminated by noise, resulting in frequency offset and phase offset, and thus the received signal s'(t) is obtained.

[0035] In step S102, the received signal is subjected to filtering sampling, frequency offset estimation compensation, and phase estimation compensation processing to obtain a compensated signal sequence.

[0036] In step S103, the phase tilt value is calculated, and the calculated phase tilt value is used to perform physical phase tilt processing on the compensation signal sequence.

[0037] In step S104, the signal sequence after physical tilt phase processing is demodulated to extract the original signal sequence.

[0038] In some embodiments, the frequency offset compensation and phase compensation processing of the received signal further includes: using RPA and MSSO search methods to perform frequency offset estimation and phase offset precise estimation.

[0039] In some embodiments, calculating a phase tilt value and performing physical phase tilt processing on the signal sequence using the calculated phase tilt value includes:

[0040] Calculate the phase tilt value:

[0041] Δφ=πh(M-1)t / T

[0042] Where h represents the modulation index, M represents the number system, t represents time, and T represents the symbol interval;

[0043] The signal sequence is physically tilted in phase, and the processed signal sequence r p (t) satisfies:

[0044]

[0045] Where, r f (t) represents the compensated signal sequence, and j represents the imaginary unit. The term is used to compensate for the initial phase of the system, making the initial phase zero.

[0046] The method described in this application reduces signal loss by performing physical phase tilt processing at the receiving end, effectively solving the problem of mismatch between the center frequency of the transmitting signal and the receiving filter, thereby reducing signal loss. This improvement enables the signal to recover the original information more accurately during reception, enhancing the system's transmission efficiency.

[0047] On the other hand, the method of this application can improve demodulation performance: by performing physical phase tilt processing at the receiving end, the present invention can significantly improve the demodulation performance of the signal without increasing symbol overhead. The phase-corrected signal can better match the expected input of the demodulator, reduce demodulation error, and improve the overall performance of the system.

[0048] In some embodiments, demodulating the signal sequence after physical tilt phase processing includes: demodulating the processed signal sequence r p (t) is input to the Viterbi demodulator for signal demodulation.

[0049] The method of this application enhances the flexibility of the system: by implementing phase tilt processing at the receiver, the present invention improves the system's flexibility, enabling it to adapt to different communication conditions and requirements. The phase correction mechanism at the receiver allows the system to maintain efficient and stable operation even in complex environments such as frequency drift and mismatch.

[0050] This application also proposes an implementation example of a CPM modulation signal processing method with physical phase tilt at the receiving end, such as... Figure 3 As shown, it includes the following steps:

[0051] Step 1: At the transmitting end, a standard CPM modulated signal is generated, and a synchronization header is added to generate the transmit signal s(t).

[0052] (1.1) Generate random input sequence α i∈{±1,±3,...,±(M-1)} (i=0,1,...,N-1). This embodiment uses a 4-ary number system with a sequence length of 8192, i.e., M=4, N=8192, where the code element α at time -1 is specified. -1 =-3.

[0053] (1.2) The input sequence α is subjected to standard CPM modulation, and the modulation signal is s. c (t,α)=Ae jφ(t,α) In this embodiment, the signal amplitude A = 1, the symbol interval T = 0.2 μs, the modulation index h = 1 / 4, the constraint length L = 2, and the phase pulse function q(t) adopts a 2RC raised cosine pulse.

[0054] (1.3) Modulate the signal s c The signal (t, α) becomes the transmitted signal s(t) after adding a synchronization header, and is sent to the receiver. Here, the synchronization header is a signal obtained by MSK modulation of the pseudo-random sequence.

[0055] Step 2: The signal passes through the channel. When the transmitted signal s(t) passes through the channel, the signal will experience frequency and phase offset, resulting in the received signal s'(t). The channel selected here is an additive white Gaussian noise channel.

[0056] Step 3: Perform filtering, sampling, frequency offset compensation, and phase compensation on the received signal s'(t):

[0057] (3.1) The received signal s'(t) is filtered and sampled to obtain the sampled signal r(t).

[0058] (3.2) After frequency offset and phase estimation and compensation of the sampled signal r(t), the compensated signal sequence r is obtained. f (t). Here, the frequency offset estimation and phase offset precise estimation methods use the RPA and MSSO search algorithms, respectively.

[0059] Step 4: Calculate the phase tilt value and adjust the compensated signal r. f (t) Perform physical phase tilting processing:

[0060] (4.1) Inclined phase Δφ=πh(M-1)t / T.

[0061] (4.2) For the compensated signal r f (t) Perform physical phase tilting processing. The resulting processed signal sequence r is obtained. p (t), In this embodiment, α -1 =-3, additional phase is added here.

[0062] Step 5: Demodulate the signal, and convert the processed signal sequence r...p (t) is input to the Viterbi demodulator for signal demodulation, and the original signal sequence is extracted.

[0063] This application also provides simulation examples of a CPM modulation signal processing method with physically tilted phase in its embodiments.

[0064] The simulation software is MATLAB R2022b.

[0065] The simulation data structure consists of 400 frames, including the synchronization header and data, with each frame containing 32 symbol elements. The data uses an M=4 modulation index. The memory length L = 2, and the phase pulse adopts a 4CPM modulation method with a raised cosine pulse 2RC.

[0066] The channel uses additive white Gaussian noise with an additional carrier frequency offset Δf = 8kHz and random phase offset. The symbol rate is 5 Msps.

[0067] At the receiving end, the signal undergoes physical phase tilting processing. The resulting ML grid diagram for an even / odd time interval after physical phase tilting processing is shown below. Figure 4 As shown. Figure 4 It can be seen that after physical phase tilting processing, the ML mesh at odd and even times... Figure 1 This avoids the complexity of judging different signal state sets at odd and even times during demodulation. At the same time, physical phase tilt processing is performed at the receiving end, which effectively solves the problem of mismatch between the center frequency of the transmitting signal and the receiving filter, thereby reducing signal loss.

[0068] Simulation Example: Under the above conditions, the communication system corresponding to this application is simulated for transmission and reception using the method of this application and the method without frequency offset and phase offset, respectively. The bit error rate performance of the system is compared, such as... Figure 5 As shown.

[0069] Simulation results show that, under ideal conditions, there is no frequency offset or phase offset interference during signal transmission, resulting in excellent BER performance. When the signal-to-noise ratio increases from 0 dB to 12 dB, the BER decreases from approximately 10 dB to 10 dB. -1 dropped to 10 -5 However, in actual transmission, the signal is affected by frequency offset and phase offset. The method of this invention simulates the actual transmission environment and significantly improves the demodulation performance of the signal by performing physical phase tilt processing at the receiving end. Although the BER is slightly higher than the ideal state, it still achieves good performance in practical applications, especially at high signal-to-noise ratios (above 10dB), where the BER approaches 10. -4 .

[0070] This application proposes a CPM modulation signal processing method that physically tilts the phase at the receiving end. By physically tilting the phase of the signal at the receiving end, this method solves the problem of mismatch between the center frequency of the transmitting signal and the receiving filter without increasing symbol overhead, thereby reducing signal loss and improving demodulation performance.

[0071] The method in this application performs physical phase tilt processing at the receiving end, effectively solving the impact of frequency offset and phase offset on signal demodulation performance. It reduces the bit error rate and improves signal demodulation performance without increasing computational complexity excessively. This method is highly practical, taking into account interference factors in actual signal transmission, and achieves near-ideal performance, demonstrating significant practical application value.

[0072] This application also provides a CPM modulation signal processing apparatus for physically tilting phase at the receiving end, including a processor and a memory. The memory stores a computer program, and when the computer program is executed by the processor, it implements the steps of the aforementioned CPM modulation signal processing method for physically tilting phase.

[0073] This application embodiment also provides a receiving device, including a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, it implements the steps of the CPM modulation signal processing method with physical tilt phase at the receiving end as described above.

[0074] It should be noted that, in the embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0075] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0076] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0077] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.

Claims

1. A method for processing CPM signals with physical phase tilt at the receiving end, characterized in that, include: The received signal is obtained by transmitting the signal generated at the transmitting end by standard CPM modulation of the encoded signal sequence and adding a synchronization header through the channel to the receiving end. The received signal is subjected to filtering, sampling, frequency offset compensation, and phase compensation processing to obtain a compensated signal sequence; Calculate the phase tilt value, and use the calculated phase tilt value to perform physical phase tilt processing on the compensation signal sequence; The signal sequence after physical phase tilting is demodulated to extract the original signal sequence.

2. The receiver physical phase tilt (CPM) signal processing method as described in claim 1, characterized in that, The received signal is obtained at the transmitting end in the following manner: Generate a random input sequence α = [α0, α1, ..., α N-1 ], α i ∈{±1,±3,...,±(M-1)}(i=0,1,...,N-1); The input sequence α is subjected to standard CPM modulation to obtain the modulated signal s. c (t,α); modulated signal s c (t,α) becomes the transmitted signal s(t) after adding a synchronization header. The transmitted signal s(t) is sent to the receiving end through the channel. The synchronization header is a signal obtained by MSK modulation of the pseudo-random sequence.

3. The receiver physical phase tilt (CPM) signal processing method as described in claim 1, characterized in that, The frequency offset compensation and phase compensation processing of the received signal further includes: using RPA and MSSO search methods to estimate the frequency offset, accurately estimate the phase offset, and compensate to obtain the compensated signal sequence r. f (t).

4. The receiver physical phase tilt (CPM) signal processing method as described in claim 1, characterized in that, Calculating the phase tilt value and then using the calculated phase tilt value to physically tilt the signal sequence includes: Calculate the phase tilt value Δφ: Δφ=πh(M-1)t / T Where h represents the modulation index, M represents the number system, t represents time, and T represents the symbol interval; The signal sequence is physically tilted in phase, and the processed signal sequence r p (t) satisfies: Where, r f (t) represents the compensated signal sequence, and j represents the imaginary unit. The term is used to compensate for the initial phase of the system, making the initial phase zero.

5. The receiver physical phase tilt (CPM) signal processing method as described in claim 4, characterized in that, Demodulation of the signal sequence after physical phase tilt processing includes: The processed signal sequence r p (t) is input to the Viterbi demodulator for signal demodulation.

6. A receiver-side physical phase tilt (CPM) signal processing device, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, which, when executed by the processor, implements the steps of the receiver physical phase tilt CPM signal processing method as described in any one of claims 1 to 5.

7. A receiving device, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, which, when executed by the processor, implements the steps of the receiver physical phase tilt CPM signal processing method as described in any one of claims 1 to 5.

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