A method for amplitude blind synchronization of an APSK continuous modulation signal
By performing blind amplitude synchronization based on the constellation characteristics of APSK modulated signals, and utilizing Q-β transform and gain control factor estimation, the problem of slow convergence speed of amplitude synchronizers in pilotless mode is solved, achieving fast and accurate amplitude synchronization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUANENG LANCANG RIVER HYDROPOWER CO LTD
- Filing Date
- 2023-08-16
- Publication Date
- 2026-07-21
AI Technical Summary
In the pilotless mode of the DVB-S2 standard, the amplitude synchronizer of the APSK continuous modulation signal converges slowly, making it impossible to effectively utilize the known information in the signal for training.
Amplitude blind synchronization is performed using constellation characteristics based on APSK modulated signals. Through Q-β transformation and gain control factor estimation, training is performed using all APSK symbols to eliminate dependence on known symbols.
It achieves rapid convergence amplitude synchronization in pilot-free mode, applicable to both pilot-with and pilot-free modes, improving synchronization accuracy and speed.
Smart Images
Figure CN117014267B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of communication technology, and particularly relates to synchronization technology, specifically to a blind amplitude synchronization method for APSK continuously modulated signals. Background Technology
[0002] The DVB-S2 standard is currently the most widely used satellite communication technology standard. This standard employs advanced forward error correction coding—LDPC codes—to ensure the reliability of information transmission. When decoding LDPC codes, soft-decision decoding techniques are typically used to obtain higher decoding gain. Soft-decision decoding requires that the decoder's input information be accurate soft information about the distance between the received symbol and the standard symbol. If the soft information input to the decoder is inaccurate, the decoding performance will degrade. This is especially true for APSK high-order modulation signals. To obtain accurate soft information, the demodulator must first achieve accurate parameter synchronization of the received signal, including timing synchronization, carrier synchronization, and amplitude synchronization. Therefore, amplitude synchronization is a crucial sub-function of an all-digital demodulator.
[0003] The DVB-S2 standard defines two physical frame formats: pilot mode (e.g.) Figure 1 (as shown) and pilotless mode (such as) Figure 2 (As shown). For APSK continuous modulation signals with pilot mode, the periodically inserted (known) pilot symbols can be used to train the amplitude synchronizer, enabling it to converge quickly and maintain synchronization accuracy. However, for APSK continuous modulation signals without pilot mode, apart from a small number of (known) preamble symbols carried in the physical frame header, there is no other known information in the signal that can be used to train the amplitude synchronizer. Therefore, in the pilotless mode, if a similar amplitude synchronization method as in the pilot-mode is used, the convergence speed of the amplitude synchronizer will be very slow due to the long training interval. Summary of the Invention
[0004] To address the shortcomings and defects of the aforementioned existing technologies, this invention provides a blind amplitude synchronization method for APSK continuous modulation signals. For 16APSK and 32APSK continuous modulation signals defined by the DVB-S2 standard, the amplitude error is estimated based on the constellation characteristics of the APSK modulation signal, thereby completely eliminating the dependence on known symbols in the entire amplitude synchronization method, resulting in faster convergence and a wider range of applications.
[0005] To achieve the above objectives, the present invention employs the following techniques:
[0006] A blind amplitude synchronization method for APSK continuously modulated signals first assumes Let y[k] be a sequence of APSK continuous modulation symbols of length L, where y[k] is an APSK modulation symbol synchronized by timing and carrier synchronization, E[k] represents the energy of y[k], p[k] represents the power of the amplitude synchronizer input signal (p[k] is estimated based on the APSK modulation symbols at time k and before that without amplitude synchronization), g[k] represents the gain control factor, and y′[k] represents the result of y[k] after amplitude adjustment. The Q-β transform of y′[k] is defined as follows: Where Q is a positive integer, and β is the argument. and They represent The real and imaginary parts are given by A, which represents the absolute value of the real part of the symbol with the highest energy after Q-β transformation of all symbols in the standard APSK symbol set. The specific steps of the method described in this invention are as follows:
[0007] S100. Initialize the relevant parameters of the amplitude blind synchronization algorithm: Create a counter k and set its initial value to k=1; set p[0]=0, g[0]=1;
[0008] S200, When k = 1, 2, ..., L, the APSK modulation symbol sequence that has completed timing synchronization and carrier synchronization is obtained. The amplitude synchronizer is sequentially input and blind amplitude synchronization is performed, including:
[0009] S210. Input the k-th APSK modulation symbol y[k] into the amplitude synchronizer and perform the following calculation:
[0010] Adjusting the amplitude of y[k], we get: y′[k]=g[k-1]y[k];
[0011] Calculating the energy of y[k], we get: E[k]=|y[k]| 2 Where |·| represents the modulus of the complex number;
[0012] S220. Filter the amplitude-adjusted symbol y′[k] according to the energy of y[k]. If E[k]≥ηp[k-1], output y′[k] for the next step of amplitude error estimation; otherwise, discard y′[k]. Here, η is the energy filtering factor, which is related to the modulation and coding waveform of the APSK signal and requires specific design for specific waveforms.
[0013] S230. Use the symbols output in step S220 to estimate the amplitude error:
[0014] Perform a Q-β transform on the output symbol y′[k] of step S220 to obtain In the Q-β transform, the values of parameters Q and β are closely related to the constellation definition of the APSK modulated signal. For the 16APSK modulated signal defined by the DVB-S2 standard, Q = 3 and β = 0; for the 32APSK modulated signal defined by the DVB-S2 standard, Q = 4 and β = 0.
[0015] Estimate the amplitude error, and we get:
[0016] S240, Update the gain control factor: g[k] = g[k-1] + μe[k]; where the parameter μ is determined together with the relevant parameters of the amplitude blind synchronization algorithm in S100;
[0017] S250, Update the power estimate of the input signal, p[k]=αp[k-1]+(1-α)E[k]; where the parameter α is determined together with the relevant parameters of the amplitude blind synchronization algorithm in S100;
[0018] S260. Determine whether the input signal has completed amplitude adjustment. If it has, end amplitude synchronization. If not, update the counter: k←k+1, and repeat steps S210 to S260 until the input signal has completed amplitude adjustment.
[0019] The beneficial effects of this invention are as follows:
[0020] A general amplitude blind synchronization method is provided for 16APSK and 32APSK continuous modulation signals defined in the DVB-S2 standard. The amplitude error is estimated based on the constellation characteristics of the APSK modulation signal, thus completely eliminating the dependence on known symbols in the entire amplitude synchronization method. Moreover, this method uses all APSK symbols in the physical frame to train the amplitude synchronizer. Compared with amplitude synchronization algorithms that only use pilot training, it converges faster and is applicable to both pilot-mode and pilot-less mode points. Attached Figure Description
[0021] The accompanying drawings described herein are merely illustrative of selected embodiments, not all possible implementations, and are not intended to limit the scope of the invention.
[0022] Figure 1 This is a schematic diagram of the physical frame format with pilot mode as defined by the DVB-S2 standard.
[0023] Figure 2 This is a schematic diagram of the physical frame format for pilotless mode as defined by the DVB-S2 standard.
[0024] Figure 3 It is a constellation diagram of the 16APSK modulation symbols defined by the DVB-S2 standard.
[0025] Figure 4 It is a constellation diagram of the 32APSK modulation symbols defined by the DVB-S2 standard.
[0026] Figure 5 Yes Figure 3 The constellation diagram after Q-β transformation of the 16APSK standard constellation; where "." represents the 16APSK standard constellation point and "*" represents the constellation point after Q-β transformation; for the 16APSK modulation scheme defined by the DVB-S2 standard, Q=3 and β=0 are taken.
[0027] Figure 6 Yes Figure 4 The diagram shows the constellation of the 32APSK standard constellation after Q-β transformation; where "." represents a point in the 32APSK standard constellation, and "*" represents a point in the constellation after Q-β transformation; for the 32APSK modulation scheme defined by the DVB-S2 standard, Q = 4.
[0028] Figure 7 This is the structure of the amplitude synchronizer used in the embodiments of this application.
[0029] Figure 8 This is the constellation diagram before amplitude synchronization in the embodiments of this application; where "." represents the constellation point of the desired signal before amplitude synchronization, and "*" represents the standard constellation point.
[0030] Figure 9 This is a constellation diagram after amplitude synchronization according to an embodiment of this application; where “.” represents the constellation point of the desired signal after amplitude synchronization, and “*” represents the standard constellation point. Detailed Implementation
[0031] To make the purpose, technical solution, and specific implementation method of this application clearer, this application will be further described in detail below.
[0032] This application provides an amplitude blind synchronization method for APSK continuously modulated signals.
[0033] First, the relevant parameters in the algorithm will be explained. Let y[k] represent a continuous APSK modulation symbol sequence of length L, where y[k] is an APSK modulation symbol synchronized by timing and carrier synchronization. Let E[k] represent the energy of y[k]. Let p[k] represent the power of the amplitude synchronizer input signal (p[k] is estimated based on the APSK modulation symbols at time k and before it without amplitude synchronization). Let g[k] represent the gain control factor. Let y′[k] represent the result of y[k] after amplitude adjustment. The Q-β transform of y′[k] is defined as... Where Q is a positive integer, and β is the argument. and They represent The real and imaginary parts. Let A denote the absolute value of the real part of the symbol with the highest energy after performing a Q-β transform on all symbols in the standard APSK symbol set. For example... Figure 5 and Figure 6 As shown, Figure 5 The asterisk (*) in the middle is a pair of dots. Figure 3 Constellation points after Q-β transformation of the 16APSK standard constellation. Figure 6 The asterisk (*) is a pair of dots. Figure 4 Constellation points after Q-β transformation of the 32APSK standard constellation. Figure 5 and Figure 6 In the middle, the outermost "*" shaped constellation point has the greatest energy, and the absolute values of its real and imaginary parts are equal. The absolute value of their real parts is the value of A under the corresponding conditions.
[0034] The waveform selected in this example is MODCOD=24 in the DVB-S2 standard. D The waveform is a no-pilot short frame. The modulation scheme is 32APSK, such as... Figure 4 As shown, the coding rate is 3 / 4, where the amplitude of the modulation symbol is obtained according to the following method provided by the DVB-S2 standard:
[0035]
[0036] Where R1, R2, and R3 represent the radii of the three constellation rings, and γ1 and γ2 represent the radius ratio. The energy filtering factor designed for this waveform is η = 0.7. Other parameter values for this example are as follows: L = 6660 (total number of symbols in two pilot-less short frames), μ = 0.001 in the gain update equation, α = 0.99 in the power estimation equation, and Q = 4. A = 1.7497319. Figure 7 This is the structure of the amplitude synchronizer used in this example.
[0037] The specific steps of the amplitude blind synchronization method described in this example are as follows:
[0038] 1. Initialize the relevant parameters of the amplitude blind synchronization algorithm:
[0039] 1.1 Create a counter k and set its initial value to k = 1.
[0040] 1.2 Set p[0] = 0 and g[0] = 1.
[0041] 1.3 Determine the value of parameter μ in the gain update equation, and take μ = 0.001.
[0042] 1.4 Determine the value of parameter α in the power estimation equation, and take α = 0.99.
[0043] 2. When k = 1, 2, ..., L, the APSK modulation symbol sequence that has completed timing synchronization and carrier synchronization will be obtained. The amplitude synchronizer is sequentially input and blind amplitude synchronization is performed. The specific steps are as follows:
[0044] 2.1 Input the k-th APSK modulation symbol y[k] into the amplitude synchronizer and perform the following two calculations:
[0045] 2.1.1 Adjust the amplitude of y[k] to get: y′[k]=g[k-1]y[k].
[0046] 2.1.2 Calculate the energy of y[k], and we get: E[k]=|y[k]| 2 , where |·| represents the modulus of the complex number.
[0047] 2.2. Filter the amplitude-adjusted symbol y′[k] according to the energy of y[k]. The specific method is as follows: if E[k]≥ηp[k-1], then output y′[k] for amplitude error estimation in step 2.3; otherwise, discard y′[k].
[0048] 2.3. Use the output symbol from step 2.2 to estimate the amplitude error. The specific steps are as follows:
[0049] 2.3.1 Perform a Q-β transform on the output symbol y′[k] from step 2.2 to obtain...
[0050] 2.3.2. Estimate the amplitude error, and we get:
[0051] 2.4 Update the gain control factor: g[k] = g[k-1] + μe[k].
[0052] 2.5. Update the power estimate of the input signal, p[k]=αp[k-1]+(1-α)E[k].
[0053] 2.6 Determine if the input signal has completed amplitude adjustment. If it has, end amplitude synchronization; otherwise, update the counter: k←k+1, and repeat steps 2.1 and 2.6 until the input signal has completed amplitude adjustment.
[0054] Figure 8 and Figure 9 The constellation diagrams of the selected waveform in this example are shown before and after amplitude synchronization. Figure 8 In the diagram, "." represents the constellation point of the desired signal before amplitude synchronization, and "*" represents the standard constellation point. From... Figure 9 As can be seen, when the amplitude blind synchronization algorithm in this example converges, the "." set and the "*" set almost completely overlap, indicating that the constellation point of the desired signal is accurately amplified to the position of the standard constellation point, thus achieving amplitude synchronization.
[0055] The technical solution of this embodiment is applicable to both pilot-mode and pilotless-mode; this is because the method estimates the amplitude error based on the constellation characteristics of the APSK modulated signal, thereby completely eliminating the dependence on known symbols in the entire amplitude synchronization method.
[0056] Meanwhile, the technical solution in this embodiment converges quickly. This is because the method uses all APSK symbols in the physical frame to train the amplitude synchronizer, thus converging faster than amplitude synchronization algorithms that only use pilot training.
Claims
1. A method for blind amplitude synchronization of APSK continuously modulated signals, characterized in that, Assumption Let be a sequence of APSK continuous modulation symbols of length L, where y[k] is an APSK modulation symbol after timing and carrier synchronization, E[k] represents the energy of y[k], p[k] represents the power of the amplitude synchronizer input signal, g[k] represents the gain control factor, and y′[k] represents the result of y[k] after amplitude adjustment. The Q-β transform of y′[k] is defined as... Where Q is a positive integer, and β is the argument. and They represent The real and imaginary parts, denoted by A, represent the absolute value of the real part of the symbol with the highest energy after Q-β transformation of all symbols in the standard APSK symbol set. The method includes the following steps: S100. Initialize the relevant parameters of the amplitude blind synchronization algorithm: Create a counter k and set its initial value to k=1; set p[0]=0, g[0]=1; S200, When k = 1, 2, ..., L, the APSK modulation symbol sequence that has completed timing synchronization and carrier synchronization is obtained. The amplitude synchronizer is sequentially input and blind amplitude synchronization is performed, including: S210. Input the k-th APSK modulation symbol y[k] into the amplitude synchronizer and perform the following calculation: Adjusting the amplitude of y[k], we get: y′[k]=g[k-1]y[k]; Calculating the energy of y[k], we get: E[k]=|y[k]| 2 Where |·| represents the modulus of the complex number; S220. Filter the amplitude-adjusted symbol y′[k] according to the energy of y[k]. If E[k]≥ηp[k-1], output y′[k] for the next step of amplitude error estimation; otherwise, discard y′[k]. Where η is the energy filtering factor. S230. Using the output symbol from step S220, perform amplitude error estimation. Then, perform a Q-β transform on the output symbol y′[k] from step S220 to obtain... Estimate the amplitude error, and we get: S240, Update the gain control factor: g[k] = g[k-1] + μe[k]; where the parameter μ is determined together with the relevant parameters of the amplitude blind synchronization algorithm in S100; S250, Update the power estimate of the input signal, p[k]=αp[k-1]+(1-α)E[k]; where the parameter α is determined together with the relevant parameters of the amplitude blind synchronization algorithm in S100; S260. Determine whether the input signal has completed amplitude adjustment. If it has, end amplitude synchronization. If not, update the counter: k←k+1, and repeat steps S210 to S260 until the input signal has completed amplitude adjustment.