Method, device and equipment for processing physical phase tilt (CPM) signal of receiving end

Abstract

The invention discloses a CPM modulation signal processing method, device and equipment for carrying out physical tilt phase at a receiving end, and relates to the communication technology, and the method comprises the steps: obtaining a received signal; performing filtering sampling, frequency offset compensation and phase compensation processing on the received signal to obtain a compensation signal sequence; calculating a phase tilt value, and performing physical tilt phase processing on the compensation signal sequence by using the calculated phase tilt value; and demodulating the signal sequence after the physical tilt phase processing to extract an original signal sequence. According to the method, physical tilt phase processing is carried out on the signal at the receiving end, and the problem that the signal at the sending end is not matched with the center frequency of the filter at the receiving end is solved under the condition that symbol overhead is not increased, so that signal loss is reduced, and the demodulation performance of the signal is improved.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a method, device and equipment for processing a physical phase tilt CPM signal at a receiving end. Background Art

[0002] Continuous phase modulation (CPM) is a highly efficient modulation technique characterized by 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 CPM's phase memory property, the carrier phase is continuous in time, thus avoiding spectral jumps. This results in a concentrated power spectral density and low out-of-band power in the CPM signal. Furthermore, the constant envelope characteristic of the CPM signal enables good performance in fading channels and can be processed by nonlinear amplifiers.

[0003] In his 1988 paper, "A decomposition 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's decomposition technology, in order to ensure that the system maintains a time-invariant network structure during demodulation and reduce demodulation complexity, traditional methods usually perform physical phase tilt processing on the CPM signal during modulation at the transmitter.

[0005] Patent document CN201710952229 proposes a physical layer network coding method based on continuous phase modulation. This method physically tilts the phase of the CPM signal during modulation at the transmitter. However, this method has significant drawbacks. The center frequency of the filter at the receiver is typically set to the center frequency of the signal transmitted by the transmitter. When a tilted phase is applied to the signal at the transmitter, the center frequency of the transmitted signal shifts, mismatching the center frequency of the filter at the receiver. Due to this frequency mismatch, some of the spectral energy of the received signal is lost, resulting in a decrease in the quality of the received signal and ultimately affecting demodulation performance. Summary of the Invention

[0006] The embodiments of the present application provide a method, apparatus, and device for processing CPM modulated signals with physical phase tilt at a 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] The present application provides a receiving end physical phase tilt CPM signal processing method, including:

[0008] Acquire a received signal, where the received signal is a signal generated by performing standard CPM modulation on the encoded signal sequence at the transmitting end and adding a synchronization header, and then transmitting the generated signal through a channel to the receiving end;

[0009] Performing filtering sampling, frequency offset compensation, and phase compensation processing on the received signal to obtain a compensated signal sequence;

[0010] Calculating a phase tilt value, and performing physical tilt phase processing on the compensation signal sequence using the calculated phase tilt value;

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

[0012] An embodiment of the present application also provides a CPM modulation signal processing device that performs physical phase tilting at the receiving end, including a processor and a memory, wherein a computer program is stored on the memory, and when the computer program is executed by the processor, the steps of the CPM modulation signal processing method that performs physical phase tilting at the receiving end as described above are implemented.

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

[0014] The present invention proposes a method for processing CPM modulated signals with physical phase tilt at the receiving end. By physically tilting the phase of the signal at the receiving end, the method solves the problem of mismatch between the transmitting signal and the center frequency of the receiving filter without increasing symbol overhead, thereby reducing signal loss and improving signal demodulation performance.

[0015] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0017] Figure 1 This is a basic flow diagram of the CPM modulation signal processing method according to an embodiment of the present application;

[0018] Figure 2 Schematic diagram of a communication system used in the CPM modulation signal processing method according to an embodiment of the present application;

[0019] Figure 3 This is a flowchart of an implementation case of the CPM modulation signal processing method according to an embodiment of the present application;

[0020] Figure 4 This is an ML grid diagram of an odd-even time segment after the physical tilt phase processing is performed at the receiving end according to the method of the embodiment of the present application;

[0021] Figure 5 The figures are comparison diagrams of bit error performance simulation using the method of the present application and under ideal conditions (no frequency offset or phase offset). DETAILED DESCRIPTION

[0022] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0023] The embodiment of the present application provides a receiving end physical phase tilt CPM signal processing method, the method of the present application is used to perform physical phase tilt at the receiving end, such as Figure 1 As shown, the following steps are included:

[0024] In step S101, a received signal is obtained, wherein the received signal is a signal generated by performing standard CPM modulation on the encoded signal sequence at the transmitting end and adding a synchronization header to the transmitted signal, which is transmitted through a channel to the receiving end. The communication system used in the embodiment of the present application is as follows: Figure 2 As shown, in some embodiments, the received signal is specifically sent by 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 a 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, θ n is the accumulated phase. The function q(t) is called the phase pulse.

[0030] Assume that the code elements before time 0 do not carry any information and do not participate in the calculation of the cumulative phase. The code elements before time -1 are all 0, which are invalid code elements and do not carry any information. The code elements at time -1 are not zero and are only used to affect the initial phase of the system. Then θ n The accumulated phase is:

[0031]

[0032] The modulated signal s c (t,α) plus a synchronization header becomes a transmission signal s(t), and the transmission signal s(t) is sent to the receiving end through the channel, where the synchronization header is a signal obtained by performing MSK modulation on a pseudo-random sequence.

[0033] The transmitted signal passes through the channel, and there is noise:

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

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

[0036] In step S103, a 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 the physical tilt phase processing is demodulated to extract the original signal sequence.

[0038] In some embodiments, performing frequency offset compensation and phase compensation processing on 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 tilt phase processing on a 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 base number, t represents the time, and T represents the symbol interval;

[0043] Perform physical tilt phase processing on the signal sequence, and the processed signal sequence r p (t) Satisfy:

[0044]

[0045] Among them, r f (t) represents the compensated signal sequence, j represents the imaginary unit, The term is used to compensate the initial phase of the system so that the initial phase is zero.

[0046] The method proposed in this application can reduce signal loss by physically tilting the phase at the receiving end, effectively resolving the mismatch between the transmitting signal and the center frequency of the receiving filter, thereby reducing signal loss. This improvement enables more accurate restoration of the original information during signal reception, improving the system's transmission efficiency.

[0047] Furthermore, the method of this application can improve demodulation performance: by physically tilting the phase at the receiving end, the present invention can significantly improve signal demodulation performance without increasing symbol overhead. The phase-corrected signal can better match the expected input of the demodulator, reducing demodulation errors and improving overall system performance.

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

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

[0050] The embodiment of the present application also proposes an implementation case of a CPM modulation signal processing method for performing physical phase tilting at the receiving end, such as Figure 3 As shown, the following steps are included:

[0051] Step 1: Perform standard CPM modulation on the transmitting end and add a synchronization header to generate the transmitted signal s(t).

[0052] (1.1) Generate a random input sequence α i∈{±1,±3,...,±(M-1)}(i=0,1,...,N-1). This embodiment uses quaternary numbers, and the sequence length is 8192, that is, 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) uses a 2RC raised cosine pulse.

[0054] (1.3) The modulated signal s c The synchronization header is added to (t,α) to become the transmitted signal s(t), which is then sent to the receiver. Here, the synchronization header is a signal obtained by performing MSK modulation on a 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 deviations, resulting in the received signal s'(t). The channel selected here is an additive white Gaussian noise channel.

[0056] Step 3: Filter and sample the received signal s'(t), perform frequency offset compensation, and phase compensation:

[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 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 compare it with the compensated signal r f (t) Perform physical tilt phase processing:

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

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

[0062] Step 5: Perform signal demodulation and convert the processed signal sequence rp (t) is input into the Viterbi demodulator for signal demodulation to extract the original signal sequence.

[0063] The embodiment of the present application also proposes a simulation case of a CPM modulation signal processing method with a physical tilt phase.

[0064] The simulation software is MATLAB R2022b.

[0065] The data structure in the simulation is: 400 frames of synchronization header and data, each frame has 32 code symbols. The data uses M=4 and modulation index The memory length L=2, and the phase pulse adopts the 4CPM modulation mode of the raised cosine pulse 2RC.

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

[0067] At the receiving end, the signal is processed by physical tilt phase. The ML grid diagram of a period of odd and even moments after the physical tilt phase processing is as follows: Figure 4 shown. Figure 4 It can be seen that after the physical tilt phase processing, the ML grids at odd and even times Figure 1 The demodulation avoids the complexity of judging different signal state sets at odd and even moments. At the same time, physical tilt phase processing is performed at the receiving end, which effectively solves the problem of mismatch between the transmitting signal and the center frequency of the receiving filter, thereby reducing signal loss.

[0068] Simulation example: Under the above conditions, the transmission and reception simulations of the communication system corresponding to the present application are performed using the method of the present application and the method without frequency offset and phase offset, and the bit error performance comparison of the system is obtained, as shown in FIG. Figure 5 shown.

[0069] From the simulation results, it can be seen that under ideal conditions, there is no frequency deviation and phase deviation interference during signal transmission, and the BER performance is better. When the signal-to-noise ratio increases from 0dB to 12dB, the BER increases from about 10 -1 Down to 10 -5 However, in the actual transmission process, the signal will be affected by frequency deviation and phase deviation. The method of the present invention simulates the actual transmission environment and significantly improves the demodulation performance of the signal by performing physical tilt phase processing at the receiving end. Although the BER is slightly higher than the ideal state, it can still achieve good performance in the actual application environment, especially under high signal-to-noise ratio (above 10dB), the BER is close to 10 -4 .

[0070] The present invention proposes a method for processing CPM modulated signals with physical phase tilt at the receiving end. By physically tilting the phase of the signal at the receiving end, the method solves the problem of mismatch between the transmitting signal and the center frequency of the receiving filter without increasing symbol overhead, thereby reducing signal loss and improving signal demodulation performance.

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

[0072] An embodiment of the present application also provides a CPM modulation signal processing device with physical tilt phase at the receiving end, including a processor and a memory, wherein a computer program is stored on the memory, and when the computer program is executed by the processor, the steps of the CPM modulation signal processing method with physical tilt phase as described above are implemented.

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

[0074] It should be noted that, in the various embodiments of the present application, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0075] The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0076] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course 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 the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for enabling a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0077] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are protected by this application.

Claims

1. A receiving end physical phase tilt CPM signal processing method, characterized in that: include: Acquire a received signal, where the received signal is a signal generated by performing standard CPM modulation on the encoded signal sequence at the transmitting end and adding a synchronization header, and then transmitting the generated signal through a channel to the receiving end; Performing filtering sampling, frequency offset compensation, and phase compensation processing on the received signal to obtain a compensated signal sequence; Calculating a phase tilt value, and performing physical tilt phase processing on the compensation signal sequence using the calculated phase tilt value; The signal sequence after physical tilt phase processing is demodulated to extract the original signal sequence.

2. The receiving end physical phase tilt CPM signal processing method according to claim 1, characterized in that: The received signal is specifically 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); Perform standard CPM modulation on the input sequence α to obtain the modulated signal s c (t,α); The modulated signal s c (t,α) plus a synchronization header becomes a transmission signal s(t), and the transmission signal s(t) is sent to the receiving end through the channel, where the synchronization header is a signal obtained by performing MSK modulation on a pseudo-random sequence.

3. The receiving end physical phase tilt CPM signal processing method according to claim 1, characterized in that: The frequency offset compensation and phase compensation processing of the received signal also 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 receiving end physical phase tilt CPM signal processing method according to claim 1, characterized in that: Calculating a phase tilt value, and performing physical tilt phase processing on a signal sequence using the calculated phase tilt value includes: Calculate the phase tilt value Δφ: Δφ=πh(M-1)t / T Where h represents the modulation index, M represents the base number, t represents the time, and T represents the symbol interval; Perform physical tilt phase processing on the signal sequence, and the processed signal sequence r p (t) Satisfy: Among them, r f (t) represents the compensated signal sequence, j represents the imaginary unit, The term is used to compensate the initial phase of the system so that the initial phase is zero.

5. The receiving end physical phase tilt CPM signal processing method according to claim 4, characterized in that: Demodulating the signal sequence after physical tilt phase processing includes: The processed signal sequence r p (t) is input to the Viterbi demodulator for signal demodulation.

6. A receiving end physical phase tilt CPM signal processing device, characterized in that: The method comprises a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the receiving end physical phase tilt CPM signal processing method as described in any one of claims 1 to 5 are implemented.

7. A receiving device, characterized in that: The method comprises a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the receiving end physical phase tilt CPM signal processing method as described in any one of claims 1 to 5 are implemented.

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