CN116016073A - PSK communication system online performance evaluation method based on moment method estimation and constellation diagram characteristics - Google Patents

PSK communication system online performance evaluation method based on moment method estimation and constellation diagram characteristics Download PDF

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CN116016073A
CN116016073A CN202211557693.5A CN202211557693A CN116016073A CN 116016073 A CN116016073 A CN 116016073A CN 202211557693 A CN202211557693 A CN 202211557693A CN 116016073 A CN116016073 A CN 116016073A
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constellation
communication system
signal
error rate
points
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王洪
吴龙泉
郭志成
张昊坤
金焱
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Yangtze River Delta Research Institute of UESTC Huzhou
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Abstract

The invention provides an online performance evaluation method of a PSK communication system. And matching and filtering output data of a baseband signal of the PSK communication system, estimating the signal-to-noise ratio of the signal on line based on a moment method, and further calculating the theoretical bit error rate of the PSK communication system. Generating a constellation diagram of the PSK communication system, and extracting constellation diagram features; and determining constellation quality information according to the extracted constellation characteristics. And finally, evaluating the performance of the PSK communication system according to the theoretical error rate and the constellation diagram quality information. Compared with the prior art, the method has the advantages that the theoretical error rate of the PSK communication system is calculated according to the signal-to-noise ratio, the accuracy of transmission can be measured by extracting the relevant characteristics of the constellation diagram and comparing the relevant characteristics with the ideal values, so that the error rate and the quality of the constellation diagram are combined, the performance of the system is comprehensively evaluated, and the current performance state of the communication system is automatically perceived at a low cost.

Description

PSK communication system online performance evaluation method based on moment method estimation and constellation diagram characteristics
Technical Field
The invention relates to the technical field of performance evaluation of communication systems, in particular to an online performance evaluation method of a PSK communication system.
Background
Phase shift keying (PSK, phase Shift Keying) is a digital modulation scheme that transmits data by changing or modulating the phase of a reference signal (carrier).
The design and the realization of the communication system are both aimed at the task executed and the performance achieved by the communication system, a measuring system is additionally arranged outside the communication system for evaluating the communication performance, or a special method is developed for measuring, so that the evaluation result is accurate and reliable, but the special measuring system is required to measure, analyze and calculate by using a proper method, and the communication system has the problems of high cost, long time consumption, incapability of obtaining the current performance of the communication system at any time and the like. Meanwhile, the problems that the available data for the internal measurement performance of the communication system is limited, the substitution functions of the software and the hardware of the communication system for realizing the measurement are limited and the like exist.
Disclosure of Invention
In view of this, an object of the embodiments of the present invention is to provide a technical solution for comprehensively evaluating performance of a communication system by combining a theoretical bit error rate calculated by a signal-to-noise ratio and indirect communication quality calculated by constellation features, so as to realize automatic sensing of a current performance state of the communication system at a low cost.
A first aspect of the present invention provides a method for evaluating online performance of a PSK communication system, the method comprising:
step 1, outputting data according to baseband signal matched filtering of a PSK communication system, and estimating the signal-to-noise ratio of the baseband signal on line based on a moment method;
step 2, calculating the theoretical error rate of the PSK communication system according to the signal-to-noise ratio of the baseband signal;
step 3, generating a constellation diagram of the PSK communication system and extracting the characteristics of the constellation diagram;
step 4, determining constellation quality information according to the extracted constellation characteristics;
and step 5, evaluating the performance of the PSK communication system according to the theoretical error rate and the constellation diagram quality information. Preferably, the step 1 includes:
for the multi-system digital phase MPSK modulation under the attenuation channel with flat frequency, the model of the output signal is:
y n ＝Ae jΦ a n +w n
wherein y is n The output value of the matched filtering is a sample value with symbols as intervals; n=1, 2,3 … L, L being the number of symbols required to estimate the signal-to-noise ratio;
Ae jΦ : the channel coefficient is assumed to be a complex constant channel coefficient during observation, a represents amplitude,
Figure BDA0003983940820000021
representing phase;
a n : is a transmitted MPSK signal; for example, m=2 is BPSK, m=4 is QPSK, and m=8 is 8PSK;
w n : for variance n=2σ 2 Is a complex gaussian random variable;
signal y n Expressed as the second moment of (2):
M 2 ＝E{|y n | 2 }＝S+N
signal y n Is expressed as:
M 4 ＝E{|y n | 4 }＝k a S 2 +4SN+k w N 2
where E represents the mean square value, S is the signal power, N is the noise power,
Figure BDA0003983940820000022
k for MPSK signals in complex AWGN channels a ＝1，k w =2; substituting the second and fourth moments of the signal to obtain the estimated value of the signal to noise ratio>
Figure BDA0003983940820000023
Figure BDA0003983940820000024
Preferably, the step 2 calculates a theoretical bit error rate of the PSK communication system according to a signal-to-noise ratio of the baseband signal, including:
determining a mathematical model of the corresponding error rate and signal-to-noise ratio according to a signal modulation mode;
and (3) calculating to obtain the theoretical bit error rate according to the signal-to-noise ratio of the baseband signal in the step (1) and the mathematical model of the bit error rate and the signal-to-noise ratio.
Preferably, in step 3, the constellation characteristic includes an average value of distances between positions of discrete points in the current constellation and ideal constellation points, a standard deviation between the discrete constellation points and the ideal constellation points, and an average value of angles of the constellation points deviating from a center origin;
wherein the average value of the distances between the positions of the discrete points in the current constellation and the ideal constellation points
Figure BDA0003983940820000031
Comprises the following steps:
the system fault or the system interference causes the points in the constellation diagram to be changed from punctiform distribution to bulk distribution and the distribution is irregular, and the coordinates C of a series of discrete points are extracted i (x i ,y i ) C is calculated i And point C in the ideal constellation 0 (x 0 ,y 0 ) Distance Δd of (2) i Then obtaining the characteristic value by a method of summing and averaging N point data
Figure BDA0003983940820000032
Figure BDA0003983940820000033
The calculation process of the standard deviation sigma of the discrete constellation point and the ideal constellation point comprises the following steps:
taking the average value of the distances between N discrete points and the constellation points under ideal condition
Figure BDA0003983940820000034
The square of the difference is then taken by summingThe average method yields the standard deviation sigma:
Figure BDA0003983940820000035
the average value of the angles of the constellation points from the center origin
Figure BDA0003983940820000036
Comprises the following steps:
when the system is subjected to phase noise, the points in the constellation diagram rotate around the central origin (0, 0) and deviate from the central origin by an angle theta i Characterizing the deviation of points in the constellation, θ 0 Representing angles of corresponding points on an ideal constellation;
by the coordinates (x i ，y i ) Calculating the deviation angle theta i Then summing and averaging to obtain an average value representing the deviation of the system constellation point
Figure BDA0003983940820000046
/>
Figure BDA0003983940820000041
Figure BDA0003983940820000042
Preferably, the step 4 of determining constellation quality information according to extracting the constellation feature includes: setting the expected threshold corresponding to three features of the average value of the distances between the positions of the discrete points in the current constellation and the ideal constellation point, the standard deviation between the discrete constellation point and the ideal constellation point and the average value of the angles of the constellation point deviating from the central origin as G respectively 1 ，G 2 ，G 3 ；
With constellation quality Q C Measuring the quality of the communication system; wherein:
Figure BDA0003983940820000043
preferably, the step 5, according to the theoretical bit error rate and the constellation quality information, evaluates the performance of the PSK communication system, and includes:
setting the expected error rate as P b According to the theoretical error rate of PSK communication system in step 2
Figure BDA0003983940820000044
Theoretical bit error rate, constellation quality Q C Evaluating the performance R of the PSK communication system by adopting a weight method Per ：
Figure BDA0003983940820000045
Wherein the w 1 、w 2 、w 3 Is weight, w 1 +w 2 +w 3 +w 4 ＝1。
In a second aspect, the present invention also proposes an electronic device comprising: one or more processors, memory for storing one or more computer programs; the computer program is configured to be executed by the one or more processors, the program comprising method steps for performing the online performance assessment of the PSK communication system as described in the first aspect.
In a third aspect, the present invention also proposes a storage medium storing a computer program; the program is loaded and executed by a processor to implement the steps of the method for evaluating the online performance of a PSK communication system as described in the first aspect.
In the scheme of the invention, data is output through matching and filtering according to a baseband signal of a PSK communication system, and the signal-to-noise ratio of the baseband signal is estimated on line based on a moment method; calculating a theoretical error rate of the PSK communication system according to the signal-to-noise ratio of the baseband signal; generating a constellation diagram of a PSK communication system and extracting characteristics of the constellation diagram; determining constellation quality information according to the extracted constellation characteristics; and evaluating the performance of the PSK communication system according to the theoretical error rate and the constellation diagram quality information. Compared with the prior art, the method has the advantages that the theoretical error rate of the PSK communication system is calculated according to the signal-to-noise ratio, the accuracy of transmission can be measured by extracting the relevant characteristics of the constellation diagram and comparing the relevant characteristics with the ideal values, so that the error rate and the quality of the constellation diagram are combined, the performance of the system is comprehensively evaluated, and the current performance state of the communication system is automatically perceived at a low cost.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of the overall principle of the PSK communication system online evaluation according to an embodiment of the present invention;
fig. 2 is a flowchart of an online performance evaluation method of a PSK communication system according to an embodiment of the present invention;
fig. 3 is an ideal constellation and an interfered constellation of a QPSK signal according to an embodiment of the present invention;
fig. 4 is a diagram of QPSK signal constellation under the influence of simulated different phase noise according to an embodiment of the present invention;
FIG. 5 is a graph of mean variance versus signal-to-noise ratio for an off-center position of a constellation diagram in accordance with an embodiment of the present invention;
fig. 6 is a graph showing phase noise versus angular offset according to an embodiment of the present invention.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments may be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the present application. One skilled in the relevant art will recognize, however, that the aspects of the application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, etc. In other instances, well-known methods, devices, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the application.
The block diagrams depicted in the figures are merely functional entities and do not necessarily correspond to physically separate entities. That is, the functional entities may be implemented in software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor devices and/or microcontroller devices.
The flow diagrams depicted in the figures are exemplary only, and do not necessarily include all of the elements and operations/steps, nor must they be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the order of actual execution may be changed according to actual situations.
It should be noted that: references herein to "a plurality" means two or more.
The implementation details of the technical solutions of the embodiments of the present application are described in detail below:
in this embodiment, aiming at the characteristics of the PSK communication system, the constellation points formed by the I path and the Q path after the demodulation are used as the original data to estimate the signal-to-noise ratio and the constellation characteristics, and on this basis, a method for comprehensively evaluating the performance of the PSK communication system on line is provided.
Phase shift keying (PSK, phase Shift Keying) is a digital modulation scheme that transmits data by changing or modulating the phase of a reference signal (carrier). In the case of PSK, a limited number of phases are used. Each of these phases is assigned a unique binary bit pattern. Typically, each phase encodes the same number of bits. Each bit pattern forms a symbol represented by a particular phase. A demodulator specifically designed for the set of symbols used by the modulator determines the phase of the received signal and maps it back to the symbol it represents, thereby recovering the original data.
Fig. 1 is a schematic diagram showing the overall principle of online evaluation of the digital communication system of the present example. The method comprises the steps of obtaining a baseband signal, carrying out matching filtering, on one hand, estimating a signal to noise ratio by a moment method, and calculating a theoretical bit error rate based on the signal to noise ratio; meanwhile, decoding is carried out according to the data after matching and filtering, a constellation diagram is obtained, feature extraction of the constellation diagram is carried out, and indirect communication quality evaluation is carried out; and carrying out online comprehensive performance evaluation of the digital communication system according to the theoretical error rate and the indirect communication quality evaluation information.
Fig. 2 is a flowchart of a method for evaluating the online performance of a PSK communication system according to an embodiment of the present invention. The method comprises the following steps:
and S1, outputting data according to baseband signal matched filtering of the PSK communication system, and estimating the signal-to-noise ratio of the baseband signal on line based on a moment method.
Specifically, in this example, obtaining parameters and conditions required for signal-to-noise ratio estimation includes: the signal modulation mode and the channel model of the system, the required number of transmitted symbols, the data of the matched filtering output samples, and the like. Preferably, step S1 comprises: for the multi-system digital phase MPSK modulation under the attenuation channel with flat frequency, the model of the output signal is:
y n ＝Ae jΦ a n +w n
wherein y is n The output value of the matched filtering is a sample value with symbols as intervals; n=1, 2,3 … M, M being the number of symbols required to estimate the signal to noise ratio;
Ae jΦ : the channel coefficient is assumed to be a complex constant channel coefficient during observation, a represents amplitude,
Figure BDA0003983940820000081
representing phase;
a n : is a transmitted MPSK signal; w (w) n : for variance n=2σ 2 Is a complex gaussian random variable;
signal y n Expressed as the second moment of (2):
M 2 ＝E{|y n | 2 }＝S+N
signal y n Is expressed as:
M 4 ＝E{|y n | 4 }＝k a S 2 +4SN+k w N 2
where E represents the mean square value, S is the signal power, N is the noise power,
Figure BDA0003983940820000085
k for MPSK signals in complex AWGN channels a ＝1，k w =2; substituting the second and fourth moments of the signal to obtain the estimated value of the signal to noise ratio>
Figure BDA0003983940820000083
Figure BDA0003983940820000084
And S2, calculating the theoretical error rate of the PSK communication system according to the signal-to-noise ratio of the baseband signal.
Preferably, step S2, calculating a theoretical bit error rate of the PSK communication system according to a signal-to-noise ratio of the baseband signal, includes:
determining a mathematical model of the corresponding error rate and signal-to-noise ratio according to a signal modulation mode;
and (3) calculating to obtain the theoretical bit error rate according to the signal-to-noise ratio of the baseband signal in the step (S1) and the mathematical model of the bit error rate and the signal-to-noise ratio.
Specifically, in this embodiment, by estimating the theoretical bit error rate of the signal-to-noise ratio calculation system, the PSK communication system uses a known channel modelHas a mature mathematical model of the relation between the error rate and the signal to noise ratio, and is brought into the theoretical error rate of a signal to noise ratio computable system
Figure BDA0003983940820000091
Before being brought in, the signal to noise ratio is to be added>
Figure BDA0003983940820000092
Conversion to bit signal-to-noise ratio->
Figure BDA0003983940820000093
And (3) correlating the error rate with the system performance, and setting a proper performance judgment standard for the error rate to judge whether the current performance of the system reaches an expected value.
Specifically, in step S2, a signal modulation mode and a channel model of the communication device are acquired according to the relationship between the signal-to-noise ratio and the bit error ratio, and a mathematical calculation model of the relationship between the bit error ratio and the signal-to-noise ratio is established.
In this embodiment, the signal modulation mode adopted is BPSK, and the bit error rate corresponding to the BPSK signal
Figure BDA0003983940820000094
The relation calculation formula with the signal to noise ratio is as follows: />
Figure BDA0003983940820000095
And calculating the signal-to-noise ratio value output by the receiver of the communication equipment by adopting a signal-to-noise ratio blind estimation algorithm based on a moment method. The information rate, signal bandwidth and signal to noise ratio are calculated as:
Figure BDA0003983940820000096
Figure BDA0003983940820000097
is bit signal to noise ratio, where E b Representing energy per bit in energyJ。N 0 The power spectral density, expressed as noise, is in watts per hertz watt/Hz. N (N) 0 =n/W, W is the signal bandwidth. The unit is Hz, R b The bit rate is in bits per second bit/s. For digital communication systems, the signal bandwidth is equal to the symbol rate R s Is the reciprocal of (2):
Figure BDA0003983940820000098
the modulation order M can be determined according to the signal modulation mode, and the relation between the modulation order and each symbol bit number is:
k＝log 2 M
further determining the number of bits k in each symbol of the transmission signal, based on k and the relation between the bit rate and the symbol rate
Figure BDA0003983940820000101
The calculation formula of the bit signal to noise ratio can be replaced by:
Figure BDA0003983940820000102
the method is characterized in that a second-order fourth-order moment estimation method M2M4 method based on a moment method is adopted, and signals are sampled from a receiving end of communication equipment to obtain sampling output
Figure BDA0003983940820000103
The square and fourth power of the absolute value of each element in the sampled output are then calculated to obtain +.>
Figure BDA0003983940820000104
Second moment of vector>
Figure BDA0003983940820000105
And fourth moment>
Figure BDA0003983940820000106
And finally substituting the calculated formula to obtain the estimated value of the signal to noise ratio. Which is a kind ofThe specific calculation process is as follows:
1) Transmitting N symbol waveforms, sampling at the output end of the matched filter, and sampling N values altogether, wherein the output of the sampling value is
Figure BDA0003983940820000107
Each value corresponds to a transmitted waveform.
2) Respectively to
Figure BDA0003983940820000108
The absolute value is calculated and then the square of the absolute value and the square of the absolute value are calculated respectively.
3) Substituting the square and fourth power of the absolute value of each element found in 2) into the following formula:
Figure BDA0003983940820000109
Figure BDA00039839408200001010
4) By the following substitution
Figure BDA00039839408200001011
Thereby obtaining an estimate of SNR>
Figure BDA00039839408200001012
/>
Figure BDA00039839408200001013
Simulation determines the relation between the estimated signal-to-noise ratio and the performance of the M2M4 method: the simulation condition is that the modulation type of the communication signal is QPSK, the test signal-to-noise ratio range is 1-20 dB, the number of transmission symbols is 1000, the cyclic experiment is carried out for 100 times, the symbol rate is 256000, a 21-order raised cosine roll-off filter is adopted for pulse shaping filtering, the number of over-sampling points is 8, and the noise type is additive Gaussian white noise. The signal-to-noise ratios are 5dB,10dB,15dB and 20dB, and the estimated values are 5.12dB,9.85dB,14.53dB and 21.05dB respectively, and the error is about 1dB from the preset value.
And S3, generating a constellation diagram of the PSK communication system and extracting constellation diagram characteristics.
The constellation diagram reflects the variation trend and the robustness of the error rate of the communication system. I/Q data obtained after PSK communication system decoding takes I path data as an abscissa and Q path data as an ordinate, each decoded data corresponds to a point, and a constellation diagram can be generated. The large amount of decoded data forms countless discrete points on the constellation that deviate from the ideal position, which can reflect the correctness of the current transmission, and the characteristics of the constellation are extracted to indirectly evaluate the performance of the communication system.
The following three features are extracted: the average value of the distances between the positions of the discrete points in the current constellation and the ideal constellation points, the standard deviation between the discrete constellation points and the ideal constellation points and the average value of the angles of the constellation points deviating from the center origin. The method comprises the following steps:
when the system fails, the constellation diagram of the system changes correspondingly by continuously extracting constellation points
Figure BDA0003983940820000111
The quality of the current signal can be reflected in real time, and the fault condition of the system can be represented by the value.
Average value of distances between positions of discrete points in current constellation and ideal constellation points
Figure BDA0003983940820000112
The system fault or system disturbance causes the points in the constellation diagram to be changed from punctiform distribution to bulk distribution and the distribution is irregular, so that the coordinates C of a series of discrete points obtained can be extracted i (x i ,y i ) C is calculated i And point C in the ideal constellation 0 (x 0 ,y 0 ) Distance Δd of (2) i Then the characteristic value +.>
Figure BDA0003983940820000121
Figure BDA0003983940820000122
Standard deviation σ of discrete constellation points from ideal constellation points: taking the average value of the distance between each discrete point and the ideal constellation point
Figure BDA0003983940820000123
The square of the difference is then summed to average the eigenvalue sigma.
Figure BDA0003983940820000124
Figure BDA0003983940820000125
Simulation of σ: the ideal constellation and interfered constellation of the QPSK signal are shown in fig. 3, respectively; let the number of symbols be 20000, the sampling rate be 40M, the signal to noise ratio of additive white gaussian noise: and 0 dB-15 dB, and each value is independently simulated three times under the corresponding signal-to-noise ratio condition and averaged. As shown in FIG. 5, the mean variance of the constellation diagram from the center position and the SNR are plotted, and the simulation shows that the system deviation is improved with the improvement of the SNR, therefore, by extracting +.>
Figure BDA0003983940820000126
Sigma does reflect the behavior of the system.
Average value of angles of constellation points deviating from center origin
Figure BDA0003983940820000127
When the system is subjected to phase noise, the points in the constellation diagram rotate around the central origin (0, 0) and deviate from the central origin by an angle theta i Characterizing the deviation of points in the constellation, θ 0 Representing the angle of the corresponding point on the ideal constellation.By calculating the angle of departure θ for each constellation point i Then summing up and averaging to obtain the deviation of the system constellation point>
Figure BDA00039839408200001210
Figure BDA0003983940820000128
Figure BDA0003983940820000129
Specifically, the shape of the constellation diagram also characterizes the working condition of the system and the noise condition of the signal at the moment, when the signal is interfered, the shape of the constellation diagram can be distorted, and the distortion of the constellation diagram reflects the signal quality and the fault condition of the system. Taking phase noise as an example, the effect of noise on the constellation is discussed.
With respect to
Figure BDA0003983940820000131
Is a simulation of: the difference in phase noise levels makes the rotation angles of the constellation points of the signals different, and fig. 4 shows a QPSK signal constellation under the influence of the simulated different phase noises. It can be seen from the figure that it is practical to express the performance of the system in terms of an angle from the central origin. Setting the modulation mode as QPSK, the code element number as 20000, the sampling rate as 40M, the phase noise range as 100kHz, -122dBc/Hz to-84 dBc/Hz, independently simulating three times under the corresponding phase noise to obtain average value, and the simulation result is shown in figure 6; the phase noise versus angular offset curve shown in fig. 6 illustrates that as the phase noise increases, the absolute value of the offset angle increases, which can characterize the operation of the current system.
And step 4, determining constellation quality information according to the extracted constellation characteristics.
Preferably, the step 4 of determining constellation quality information according to extracting the constellation feature includes: setting upThe expected threshold corresponding to the three features of the average value of the distances between the positions of the discrete points in the current constellation and the ideal constellation point, the standard deviation between the discrete constellation point and the ideal constellation point and the average value of the angles of the constellation point deviating from the central origin are G respectively 1 ，G 2 ，G 3 ；
With constellation quality Q C Measuring the quality of the communication system; wherein:
Figure BDA0003983940820000132
in particular, in the present embodiment,
Figure BDA0003983940820000133
and standard deviation sigma can reflect the quality of the current signal in real time,/or->
Figure BDA0003983940820000134
The phase noise condition of the signal at this time is characterized. For PSK signals, the expected thresholds of three characteristics can be set to be G respectively 1 ，G 2 ，G 3 The threshold is obtained by simulation in advance, namely, for a certain modulation signal, according to the signal-to-noise ratio corresponding to the error rate requirement, a simulation constellation diagram under the signal-to-noise ratio is generated, the values of three characteristics are calculated, and the threshold G is obtained by the average value of multiple simulations 1 ，G 2 ，G 3 。
In some embodiments, in step 4, the threshold value needs to be reasonably selected according to the condition, so as to be able to be resolved. Therefore, the threshold for decision can be referred to for the value, taking QPSK signal as an example, and the ideal constellation is (0, 1), (1, 0), (0, -1), (-1, 0) four points, preferably
Figure BDA0003983940820000141
Threshold value G 1 1/2, sigma threshold G 2 1/4>
Figure BDA0003983940820000142
Threshold value G 3 Is pi-8. Thus, most of the points fall within a range where erroneous judgment does not occur.
And step 5, evaluating the performance of the PSK communication system according to the theoretical error rate and the constellation diagram quality information.
Preferably, the step 5, according to the theoretical bit error rate and the constellation quality information, evaluates the performance of the PSK communication system, and includes:
setting the expected error rate as P b According to the theoretical error rate of PSK communication system in step 2
Figure BDA0003983940820000143
Theoretical bit error rate, constellation quality Q C Evaluating the performance R of the PSK communication system by adopting a weight method Per ：/>
Figure BDA0003983940820000144
Wherein the w 1 、w 2 、w 3 Is weight, w 1 +w 2 +w 3 +w 4 ＝1。
In this embodiment, a weight method is adopted to perform comprehensive evaluation, so that the weight corresponding to each characteristic value is w 1 ，w 2 ，w 3 The directly calculated error rate difference is weighted as w 4 。R Per In order to comprehensively evaluate the numerical value showing the system performance, the specific value of the weight is increased or reduced by a certain weight according to the application situation and different requirements on various conditions, so that the rationality of comprehensive evaluation is ensured.
In some embodiments, in step 5, the weights corresponding to the feature values and the weights corresponding to the bit error rates are selected, usually based on the weights corresponding to the bit error rates, e.g. w is taken respectively 1 ，w 2 ，w 3 ，w 4 Is that
Figure BDA0003983940820000145
Figure BDA0003983940820000146
Because the error rate is directly reflected on the performance, specific setting needs to be specifically considered according to the application scene or the additional requirement of evaluation, for example, the evaluation of the emphasis phase noise increases the weight w corresponding to the angle deviating from the center origin 3 。
In this embodiment, by collecting intermediate signals of the communication system in real time, estimating the theoretical error rate and indirect communication quality of the system, and simultaneously, online estimating the key performance of the communication system. Firstly, output data of baseband signal matched filtering is collected, a moment method is used for estimating a signal to noise ratio, and a theoretical error rate is calculated according to the relation between the error rate and the signal to noise ratio of a PSK communication system. And then collecting a large amount of decoded I/Q data, generating constellation diagram data, comparing the constellation diagram data with an ideal constellation diagram of a communication system, reflecting the current communication quality by using the distribution of discrete point positions and ideal constellation diagram positions on the constellation diagram, extracting three characteristics of a mean value of a distance average value, a standard deviation and an average value deviating from a central origin angle, and indirectly evaluating the transmission correctness of the system by comparing the three characteristics with a set characteristic threshold. And finally, combining the theoretical error rate with the indirect evaluation result of the constellation diagram, providing a quantized performance evaluation calculation formula, and comprehensively evaluating the performance of the communication system. And communication intermediate data are collected in real time in the running process of the system, and online performance evaluation is realized under the condition of no external equipment.
In a second aspect, the present invention also proposes an electronic device comprising: one or more processors, memory for storing one or more computer programs; the computer program is configured to be executed by the one or more processors, the program comprising method steps for performing the online performance assessment of the PSK communication system as described in the first aspect.
In a third aspect, the present invention also proposes a storage medium storing a computer program; the program is loaded and executed by a processor to implement the steps of the method for evaluating the online performance of a PSK communication system as described in the first aspect.
Those of ordinary skill in the art will appreciate that the elements and algorithm steps described in connection with the embodiments disclosed herein may be embodied in electronic hardware, in computer software, or in a combination of the two, and that the elements and steps of the examples have been generally described in terms of function in the foregoing description to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices, or elements, or may be an electrical, mechanical, or other form of connection.
The elements described as separate components may or may not be physically separate, and as such, those skilled in the art will appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, where the elements and steps of the examples are generally described functionally in the foregoing description of the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention is essentially or a part contributing to the prior art, or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a grid device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (8)

1. A method for evaluating the online performance of a PSK communication system, said method comprising:
step 1, outputting data according to baseband signal matched filtering of a PSK communication system, and estimating the signal-to-noise ratio of the baseband signal on line based on a moment method;
step 2, calculating the theoretical error rate of the PSK communication system according to the signal-to-noise ratio of the baseband signal;
step 3, generating a constellation diagram of the PSK communication system and extracting the characteristics of the constellation diagram;
step 4, determining constellation quality information according to the extracted constellation characteristics;
and step 5, evaluating the performance of the PSK communication system according to the theoretical error rate and the constellation diagram quality information.
2. The method for evaluating the online performance of the PSK communication system according to claim 1, wherein said step 1 comprises:
for the multi-system digital phase MPSK modulation under the attenuation channel with flat frequency, the model of the output signal is:
y n ＝Ae jΦ a n +w n
wherein y is n The output value of the matched filtering is a sample value with symbols as intervals; n=1, 2,3 … L, L being the number of symbols required to estimate the signal-to-noise ratio;
Ae jΦ : the channel coefficient is assumed to be a complex constant channel coefficient during observation, a represents amplitude,
Figure FDA0003983940810000011
representing phase;
a n : is a transmitted MPSK signal; for example, m=2 is BPSK, m=4 is QPSK, and m=8 is 8PSK;
w n : for variance n=2σ 2 Is a complex gaussian random variable;
signal y n Expressed as the second moment of (2):
M 2 ＝E{|y n | 2 }＝S+N
signal y n Is expressed as:
M 4 ＝E{|y n | 4 }＝k a S 2 +4SN+k w N 2
where E represents the mean square value, S is the signal power, N is the noise power,
Figure FDA0003983940810000021
Figure FDA0003983940810000022
k for MPSK signals in complex AWGN channels a ＝1，k w =2; substituting the second moment and the fourth moment of the signal to obtain the estimated value of the signal to noise ratio
Figure FDA0003983940810000024
Figure FDA0003983940810000023
3. The method for evaluating the on-line performance of a PSK communication system according to claim 2, wherein said step 2 of calculating a theoretical bit error rate of the PSK communication system based on a signal-to-noise ratio of said baseband signal comprises:
determining a mathematical model of the corresponding error rate and signal-to-noise ratio according to a signal modulation mode;
and (3) calculating to obtain the theoretical bit error rate according to the signal-to-noise ratio of the baseband signal in the step (1) and the mathematical model of the bit error rate and the signal-to-noise ratio.
4. The method for evaluating the online performance of a PSK communication system according to claim 3, wherein in step 3, the constellation features include an average value of distances between positions of discrete points in a current constellation and ideal constellation points, a standard deviation between the discrete constellation points and the ideal constellation points, and an average value of angles of the constellation points from a central origin;
wherein the average value of the distances between the positions of the discrete points in the current constellation and the ideal constellation points
Figure FDA0003983940810000025
Comprises the following steps:
system failure or system disturbance to make point in constellation diagram be punctiformThe distribution becomes a bulk distribution and is irregular, and the coordinates C of the discrete points are extracted for the obtained series of discrete points i (x i ,y i ) C is calculated i And point C in the ideal constellation 0 (x 0 ,y 0 ) Distance Δd of (2) i Then obtaining the characteristic value by a method of summing and averaging N point data
Figure FDA0003983940810000035
Figure FDA0003983940810000031
The calculation process of the standard deviation sigma of the discrete constellation point and the ideal constellation point comprises the following steps:
taking the average value of the distances between N discrete points and the constellation points under ideal condition
Figure FDA0003983940810000036
The square of the difference, and then the standard deviation sigma is obtained by a summing and averaging method:
Figure FDA0003983940810000032
the average value of the angles of the constellation points from the center origin
Figure FDA0003983940810000037
Comprises the following steps:
when the system is subjected to phase noise, the points in the constellation diagram rotate around the central origin (0, 0) and deviate from the central origin by an angle theta i Characterizing the deviation of points in the constellation, θ 0 Representing angles of corresponding points on an ideal constellation;
by the coordinates (x i ，y i ) Calculating the deviation angle theta i Then summing and averaging to obtain the point of the system constellation diagramMean value of deviation
Figure FDA0003983940810000038
Figure FDA0003983940810000033
Figure FDA0003983940810000034
5. The method for evaluating the online performance of the PSK communication system according to claim 4, wherein said step 4 of determining constellation quality information based on extracting said constellation features comprises:
setting the expected threshold corresponding to three features of the average value of the distances between the positions of the discrete points in the current constellation and the ideal constellation point, the standard deviation between the discrete constellation point and the ideal constellation point and the average value of the angles of the constellation point deviating from the central origin as G respectively 1 ，G 2 ，G 3 ；
With constellation quality Q C Measuring the quality of the communication system; wherein:
Figure FDA0003983940810000041
6. the method for evaluating the performance of a PSK communication system according to claim 5, wherein said step 5 of evaluating the performance of the PSK communication system based on said theoretical bit error rate and constellation quality information comprises:
setting the expected error rate as P b According to the theoretical error rate of PSK communication system in step 2
Figure FDA0003983940810000043
Theoretical bit error rate, constellation quality Q C Evaluating the performance R of the PSK communication system by adopting a weight method Per ：
Figure FDA0003983940810000042
Wherein the w 1 、w 2 、w 3 Is weight, w 1 +w 2 +w 3 +w 4 ＝1。
7. An electronic device, the electronic device comprising: one or more processors, memory for storing one or more computer programs; characterized in that the computer program is configured to be executed by the one or more processors, the program comprising method steps for performing the online performance evaluation of the PSK communication system according to any one of claims 1-6.
8. A storage medium storing a computer program; the program being loaded and executed by a processor to implement the steps of the method for online performance assessment of a PSK communication system according to any one of claims 1 to 6.
CN202211557693.5A 2022-12-06 2022-12-06 PSK communication system online performance evaluation method based on moment method estimation and constellation diagram characteristics Pending CN116016073A (en)

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