CN109412701B - Method for selecting odd-order quadrature amplitude modulation signal precoding constellation points - Google Patents

Method for selecting odd-order quadrature amplitude modulation signal precoding constellation points Download PDF

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CN109412701B
CN109412701B CN201811434994.2A CN201811434994A CN109412701B CN 109412701 B CN109412701 B CN 109412701B CN 201811434994 A CN201811434994 A CN 201811434994A CN 109412701 B CN109412701 B CN 109412701B
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error rate
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CN109412701A (en
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迟楠
邹鹏
王福民
胡昉辰
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Fudan University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/54—Intensity modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • H04B10/0795—Performance monitoring; Measurement of transmission parameters
    • H04B10/07953—Monitoring or measuring OSNR, BER or Q
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • H04B10/0795—Performance monitoring; Measurement of transmission parameters
    • H04B10/07955—Monitoring or measuring power
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/116—Visible light communication

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Abstract

The invention discloses a method for selecting odd-order quadrature amplitude modulation signal precoding constellation points, which comprises the following steps: setting bias current and signal intensity peak-to-peak value; selecting a precoding constellation point as a conventional constellation point, modulating, receiving and recording a first transmission signal; demodulating the first transmission signal according to the recorded first transmission signal and acquiring a first error rate; selecting a precoding constellation point as a full gray constellation point, modulating, receiving and recording a second transmitting signal; demodulating the second transmitting signal according to the recorded second transmitting signal and acquiring a second error rate; calculating to obtain an error correction matrix according to the obtained first error rate and the second error rate; calculating to obtain a standard error code difference matrix according to the set bias current, the signal intensity peak-to-peak value and a standard error code difference formula; and establishing a model according to the error correction matrix and the standard error correction matrix, and obtaining a proper pre-coding constellation point according to the model, the set bias current and the peak-to-peak value of the signal intensity.

Description

Method for selecting odd-order quadrature amplitude modulation signal precoding constellation points
Technical Field
The invention relates to the field of communication, in particular to a method for selecting odd-order quadrature amplitude modulation signal precoding constellation points.
Background
The Visible Light Communication (VLC) technology is a Communication method in which Light in a Visible Light band is used as a carrier, and an optical signal is directly transmitted through air without a fiber lamp or a wired medium. Visible light communication can be realized based on commercial LEDs, and can be used for illumination and high-speed communication. As a new wireless communication means, visible light communication has the advantages of no electromagnetic interference, rich spectrum resources, no need of registration, low cost, high confidentiality and the like. With the large-scale popularization of commercial LEDs, visible light communication plays an important role in the fields of military industry, smart home, urban security and the like in the future.
Visible light communication needs to realize long-distance and high-speed transmission in many occasions, and at the moment, the direct current bias and the signal amplitude of an LED need to be increased so as to increase the emission light intensity. However, the LED will work in a non-linear region, i.e. the peak-to-peak value of the light intensity and the signal voltage is no longer linear, which will greatly affect the communication quality. Meanwhile, high-rate data transmission may cause intersymbol interference, which may degrade system performance. For normal odd-order quadrature amplitude modulation, full gray coding cannot be realized in a precoding stage, and the effect of full gray precoding constellation points is better than that of normal precoding constellation points in a nonlinear region or under the condition of large intersymbol interference. Therefore, if a method is provided, a constellation point with a larger Euclidean distance can be selected in a linear region, and a constellation point of the full Gray code can be selected in a non-linear region, so that the system performance can be effectively improved. However, the existing visible light communication means does not have a scheme for effectively selecting the bias current and the signal amplitude. Therefore, a scheme capable of effectively selecting different precoding constellation points according to different bias currents and signal amplitudes is urgently needed to improve the performance of the system under different bias currents and signal peak-to-peak voltages.
Disclosure of Invention
The embodiment of the invention discloses a method for selecting odd-order quadrature amplitude modulation signal precoding constellation points, which is developed for the purposes of selecting conventional constellation points with larger Euclidean distance in a linear region and selecting full Gray coded constellation points in a non-linear region and effectively improving the system performance, and can effectively select different precoding constellation points according to different bias currents and signal amplitudes so as to improve the performance of the system under different bias currents and signal peak-to-peak voltages.
The embodiment of the invention provides a method for selecting odd-order quadrature amplitude modulation signal precoding constellation points, which comprises the following steps:
setting bias current and signal intensity peak-to-peak value;
selecting a precoding constellation point as a conventional constellation point, modulating, receiving and recording a first transmission signal;
demodulating the first transmission signal according to the recorded first transmission signal and acquiring a first error rate;
selecting a precoding constellation point as a full gray constellation point, modulating, receiving and recording a second transmitting signal;
demodulating the second transmitting signal according to the recorded second transmitting signal and acquiring a second error rate;
calculating to obtain an error correction matrix according to the obtained first error rate and the second error rate;
calculating to obtain a standard error code difference matrix according to the set bias current, the signal intensity peak-to-peak value and a standard error code difference formula;
and establishing a model according to the error correction matrix and the standard error correction matrix, and obtaining a proper pre-coding constellation point according to the model, the set bias current and the peak-to-peak value of the signal intensity.
Further, demodulating the first transmission signal according to the recorded first transmission signal and obtaining a first bit error rate, specifically including:
and according to the set bias current and the signal intensity peak-to-peak value, obtaining a first error rate through a receiving end detection device and a decoding recovery device.
Further, demodulating the second transmission signal according to the recorded second transmission signal and obtaining a second bit error rate, specifically including:
and according to the set bias current and the signal intensity peak value, obtaining a second error rate through a receiving end detection device and a decoding recovery device.
Further, calculating to obtain an error correction matrix according to the obtained first error rate and the second error rate, specifically including:
obtaining an actual error code difference matrix according to the obtained first error code rate and the second error code rate;
and optimizing the actual error code difference matrix to obtain an error code difference correction matrix.
The embodiment of the invention provides a device for selecting odd-order quadrature amplitude modulation signal precoding constellation points, which comprises the following steps:
setting means for setting a bias current and a signal intensity peak-to-peak value;
the first recording device is used for selecting the precoding constellation point as a conventional constellation point, modulating, receiving and recording a first transmission signal;
the first demodulation device is used for demodulating the first transmission signal according to the recorded first transmission signal and acquiring a first error rate;
the second recording device is used for selecting the precoding constellation point as a full-gray constellation point, modulating, receiving and recording a second transmitting signal;
the second demodulation device is used for demodulating the second transmitting signal according to the recorded second transmitting signal and acquiring a second error rate;
the first calculating device is used for calculating to obtain an error correction matrix according to the obtained first error rate and the second error rate;
the second calculating device is used for calculating to obtain a standard error code difference matrix according to the set bias current, the set signal intensity peak-to-peak value and a standard error code difference formula;
and the selection device is used for establishing a model according to the error code correction matrix and the standard error code correction matrix and obtaining a proper pre-coding constellation point according to the model, the set bias current and the peak-to-peak value of the signal intensity.
Further, the first demodulation apparatus specifically includes:
and the first obtaining module is used for obtaining a first error rate through the receiving end detection device and the decoding recovery device according to the set bias current and the signal intensity peak-to-peak value.
Further, the second modulation device specifically includes:
and the second obtaining module is used for obtaining a second error rate through the receiving end detection device and the decoding recovery device according to the set bias current and the signal intensity peak-to-peak value.
Further, the first computing device specifically includes:
the first calculation module is used for obtaining an actual error code difference matrix according to the obtained first error code rate and the second error code rate;
and the optimization module is used for optimizing the actual error code difference matrix to obtain an error code difference correction matrix.
An embodiment of the present invention provides an electronic device, which includes a memory and a processor, where the memory is configured to store one or more computer instructions, where the one or more computer instructions are executed by the processor to implement a method for selecting odd-order qam signal precoding constellation points as described above.
An embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a computer, implements the method for selecting an odd-order qam signal precoding constellation point as described above.
The method for selecting the precoding constellation points of the odd-order quadrature amplitude modulation signals effectively solves the problem of the precoding method of the quadrature amplitude modulation signals of the visible light system under the condition that the modulation format is the odd order. The precoding method can effectively improve the performance of odd-order visible light systems and increase the communication capacity of the systems. The method is relatively easy to realize, and after the model is corrected, the pre-coding mode under the current and voltage value can be judged by only substituting the set current value and the signal intensity peak value into the corrected standard error code error formula.
Drawings
Fig. 1 is a schematic flowchart of a method for selecting odd-order qam signal precoding constellation points according to an embodiment of the present invention;
fig. 2 is a schematic flowchart of a method for selecting odd-order qam signal precoding constellation points according to a second embodiment of the present invention;
fig. 3 is a schematic diagram of an apparatus for selecting odd-order qam signal precoding constellation points according to a third embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular internal procedures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
Example one
Fig. 1 is a flowchart illustrating a method for selecting odd-order qam signal precoding constellation points according to an embodiment of the present invention. As shown in fig. 1, a method for selecting precoding constellation points of an odd-order qam signal according to this embodiment may include the following steps:
step 101, setting a bias current and a signal intensity peak-to-peak value;
step 102, selecting a precoding constellation point as a conventional constellation point, modulating, receiving and recording a first transmission signal;
103, demodulating the first transmission signal according to the recorded first transmission signal and acquiring a first error rate;
104, selecting a precoding constellation point as a full gray constellation point, and modulating, receiving and recording a second transmitting signal;
step 105, demodulating the second transmitting signal according to the recorded second transmitting signal and acquiring a second error rate;
step 106, calculating to obtain an error correction matrix according to the obtained first error rate and the second error rate;
step 107, calculating to obtain a standard error code difference matrix according to the set bias current, the signal intensity peak-to-peak value and a standard error code difference formula;
and step 108, establishing a model according to the error code difference correction matrix and the standard error code difference matrix, and obtaining a proper precoding constellation point according to the model, the set bias current and the peak-to-peak value of the signal intensity.
The specific flow of this embodiment will be explained below:
the transmitting end LED is switched into the signal transmitting system and then is lightened, a transmitting signal of the transmitting system is recorded, then a pre-coding constellation point is selected as a conventional constellation point, and the transmitting signal is modulated. After receiving and recording the signals, demodulating a first transmission signal of a conventional constellation point to obtain a first error rate; then, selecting a full-Gray precoding constellation point to modulate a second transmitting signal, receiving and recording the signal, demodulating the second transmitting signal of the full-Gray precoding constellation point, and obtaining a second error rate again; calculating to obtain an actual error code difference matrix according to the obtained second error code rate, and optimizing the actual error code difference matrix to obtain an error code difference correction matrix; meanwhile, the set peak values of the bias current and the signal intensity are brought into a standard error code difference formula, and a standard error code difference matrix is obtained through calculation; and optimizing and processing the model according to the error correction matrix and the standard error correction matrix to finally obtain the model which can be used for selecting proper precoding constellation points. According to the optimized model, the preset current and signal intensity peak value are only known, and the preset current and signal intensity peak value are brought into the model to obtain the proper precoding constellation point.
The method for selecting the odd-order quadrature amplitude modulation signal precoding constellation points effectively solves the problem of precoding mode selection of the quadrature amplitude modulation signals of the visible light system when the modulation format is the odd-order quadrature amplitude modulation signals. The pre-coding method can effectively improve the performance of odd-order visible light systems and increase the communication capacity of the systems, and the model is relatively easy to use and has small calculation amount. When the model is available, only the bias current and the signal intensity peak-to-peak value are brought in to obtain the proper precoding constellation point.
Example two
The second embodiment of the present invention provides a method for selecting odd-order qam signal precoding constellation points, and fig. 2 is a flowchart of the method for selecting odd-order qam signal precoding constellation points according to the second embodiment of the present invention. As shown in fig. 2, a method for selecting precoding constellation points of an odd-order qam signal according to this embodiment may include the following steps:
step 201, recording the bias current, the peak value of the signal intensity peak and the order of the quadrature amplitude modulation signal to be modulated;
step 202, recording the optical power of a transmitting end and the optical power of a receiving end;
step 203, selecting a precoding constellation point as a conventional constellation point;
step 204, obtaining a first error rate of the system through the signal receiving system and the demodulation recovery system according to the recorded first transmitting signal, the set bias current value and the peak value of the signal intensity peak;
step 205, selecting a precoding constellation point as a full gray coding constellation point;
step 206, obtaining the error code rate value of the system through the signal receiving system and the demodulation and recovery system according to the recorded second transmitting signal, the set bias current value and the peak value of the signal intensity peak;
and step 207, calculating an actual error code difference matrix according to the error code rate values obtained in the steps, and obtaining an error code difference correction matrix through optimization.
Step 208, substituting the set bias current value and the signal intensity peak value into a standard error code difference formula to obtain a standard error code difference value; obtaining a standard error code difference matrix according to the standard error code difference value;
and 209, optimizing the standard error code formula according to the obtained error code correction matrix and the standard error code matrix until the model meets the relevant requirements.
This embodiment explains each step in the first embodiment in detail on the basis of the first embodiment.
The following will illustrate a specific implementation of the present embodiment by using a specific example:
step 201, recording the bias current, the peak value of the signal intensity peak and the order of the quadrature amplitude modulation signal to be modulated; in particular to a method for preparing a high-performance nano-silver alloy,
and connecting the emitting end LED into an emitting system, then lighting the emitting end LED, and recording the bias current I1 of the emitting system and the order M of the quadrature amplitude modulation signal to be modulated.
Step 202, recording the optical power of a transmitting end and the optical power of a receiving end; in particular to a method for preparing a high-performance nano-silver alloy,
measuring the optical power P of the transmitting ends1；
Measuring the optical power P of the receiving endR1；
Repeating the above steps m times, recording the bias current I in m1,I2,…ImOptical power P of lower transmitting terminalS1,PS2,…PSmAnd optical power P of the receiving endR1,PR2,…PRm(ii) a Wherein I1Is the minimum value of the current, ImIs the maximum value of current and satisfies
Figure BDA0001883576370000091
Step 203, selecting the precoding constellation point as a conventional constellation point.
And step 204, obtaining a first error rate of the system through the signal receiving system and the demodulation recovery system according to the recorded first transmitting signal, the set bias current value and the peak value of the signal intensity peak. In particular to a method for preparing a high-performance nano-silver alloy,
setting bias current value to I1Peak to peak voltage of signal intensity of Vpp1And obtaining the error rate value BER of the system through a receiving end detection device and a decoding recovery device11。
Setting bias current values to I1～ImPeak-to-peak voltage of signal intensity is Vpp1～VppnIn which V ispp1For the peak-to-peak voltage minimum of the signal, VppnIs the maximum value of the peak-to-peak voltage of the signal and satisfies
Figure BDA0001883576370000092
Obtaining the error code rate value BER of the system by the receiving end detection system and the demodulation recovery system under each current value and signal peak-to-peak value voltage11，BER12，…BERij,…BERmn. Wherein BERijDenotes a bias current of IiPeak to peak signal voltage VppjThe measured error rate.
Step 205, selecting the precoding constellation point as a full gray coding constellation point.
Step 206, obtaining a second error rate of the system through the signal receiving system and the demodulation recovery system according to the recorded second transmitting signal, the set bias current value and the peak value of the signal intensity peak, that is: setting bias current values to I1～ImPeak-to-peak voltage of signal intensity is Vpp1～VppnIn which V ispp1For the peak-to-peak voltage minimum of the signal, VppnIs the maximum value of the peak-to-peak voltage of the signal and satisfies
Figure BDA0001883576370000093
Obtaining m x n bit error rate values BER 'through a receiving end detection system and a demodulation recovery system at each current value and signal peak-to-peak value voltage'11，BER′12，…BER′ij,…BER′mn. Wherein BER'ijIndicating biasThe flow is IiPeak to peak signal voltage VppjThe measured error rate.
Step 207, calculating an actual error code difference matrix according to the error code values obtained in the above steps, and obtaining an error code difference correction matrix through optimization, that is, taking 10 logarithms of the error code values obtained under two constellation points, and subtracting the values under the same current and voltage to obtain an error code difference matrix:
Figure BDA0001883576370000094
for points where the absolute value of Δ BER is greater than 0.4, 0.3 is subtracted if its value is positive, and 0.3 is added otherwise.
All values in Δ BER are divided by 1.5 to obtain the final error correction matrix Δ NBER.
Step 208, setting the bias current value and the peak value of the signal intensity peak to be substituted into a standard error code difference formula to obtain a standard error code difference value, and taking the standard error code difference value as a standard error code difference matrix; the method specifically comprises the following steps:
respectively setting bias current values to I1～ImPeak to peak voltage of signal intensity of Vpp1～VppnSubstituting into a standard error code difference formula:
Figure BDA0001883576370000101
obtaining m x n standard error code difference values and recording the values as a standard error code difference matrix
Figure BDA0001883576370000102
Wherein a is error code difference constant coefficient, pi is mathematical circumference ratio, IS1,IS2First and second current center response values, respectively. VppsIs the voltage center response value. b is a voltage current sine response coefficient, m is a sine amplitude coefficient, c is a voltage correction coefficient, w is a voltage amplitude correction coefficient, d is a current correction coefficient, f is a current square correction coefficient, h is a current second correction coefficient, and k is a second currentCurrent square correction factor, g is the voltage tangent response factor, λijThe factor is adjusted for the optical power attenuation.
Step 209, optimizing the standard error code equation according to the obtained error code correction matrix and standard error code matrix, so that the model meets the relevant requirements; the method specifically comprises the following steps:
the number of values with unequal signs in Δ NBER and N (0 not calculated) is calculated and is denoted as flag. If it is
Figure BDA0001883576370000105
Then the model is indicated as available; if the condition is not met, calculating the deviation square of error code difference values with unequal symbols according to a formula
Figure BDA0001883576370000103
p and q are subscripts of current and voltage values of the r-th error code difference value respectively, r is a value between 1 and flag, and all deviation squares are summed to obtain a deviation square sum
Figure BDA0001883576370000104
If less than 0.04, it means that the model is still usable, but the value of a in (10) needs to be adjusted so that
Figure BDA0001883576370000111
If it is larger than 0.04 or the value of a is adjusted, it is still impossible to make
Figure BDA0001883576370000112
Then the model is not available and I needs to be adjustedS1，IS2And VppsUntil a value of
Figure BDA0001883576370000113
For the well-established model, the current value is set to I1～ImAny value of I betweensSignal voltage value of Vpp1～VppnAny value V in betweenpps. Will IsAnd VppsSubstituting into the standard error code error formula in (10), if the obtained Nons>And 0, selecting the full Gray coding constellation point for precoding, otherwise, selecting the conventional constellation point for precoding.
According to the method of the embodiment, a 5 th order quadrature amplitude modulation signal is verified in a visible light communication system. The current regulation range selected in the verification experiment of the invention is 50mA to 230mA, the peak voltage of the signal is 0.6V to 1.8V, 7 points are respectively taken, the current change interval is 30mA, and the voltage change interval is 0.2V.
In a verification experiment, the values of the parameters are as follows:
parameter(s) Value taking
a -7.991
b 0.8161
c 0.4914
d 0.7946
f 2.296
g -1.3
h -0.7033
k 0.485
l 6.539
m 1.117
w 5.893
According to experimental measurement, the BER values of normal constellation points are obtained as follows:
Figure BDA0001883576370000121
according to experimental measurement, the BER values of the full-Gray precoding constellation points are obtained as follows:
Figure BDA0001883576370000122
after processing, the obtained error correction matrix is as follows:
Figure BDA0001883576370000123
Figure BDA0001883576370000131
after processing, the obtained standard error matrix is as follows:
Figure BDA0001883576370000132
and calculating to obtain an error number flag which is 3 and meets the requirement of the model. Proving that the model can be used.
And randomly selecting three bias currents and signal voltage peak-to-peak value verification, and respectively measuring the corrected error code difference and the standard error code difference as follows:
serial number Bias current (A) Signal voltage (V) Correcting error code difference Standard error code difference
1 0.07 0.8 -0.1263 -0.0955
2 0.13 1.2 -0.0029 -2.85*10^(-4)
3 0.19 1.6 0.1357 0.1726
It can be seen that, in the model in this embodiment, the sign of the corrected error code difference obtained after actual measurement at different working points is the same as the sign of the standard error code difference obtained through model calculation, which indicates that the model can accurately screen out a proper precoding mode.
Among them, what needs to be particularly described in this embodiment is: the transmitting system in the embodiment comprises a direct current power supply, a BIAS-TEE, an LED, a passive equalization circuit board and a random signal generator. Wherein:
the direct current power supply is as follows: weft fixing GPD-4303S direct current power supply
BIAS-TEE is: ZBBT-4R 2GW-FT +
The LED is as follows: HT-XM50-XM2 blue lamp bead
A random signal generator: thake AWG710
The passive equalization circuit board is a self-made T-shaped bridge type passive equalization circuit board.
The signal receiving system in this embodiment includes a PIN, a receiving circuit, and an amplifier. Wherein:
PIN is: s10784.
The receiving circuit is a home-made receiving circuit based on max 3665.
The amplifier is as follows: ZHL-6A-S +
The demodulation recovery system in this embodiment includes an oscilloscope, a notebook computer, and demodulation software. Wherein:
the oscilloscope is as follows: agilent 54855A DSO
The notebook computer is as follows: DELL notebook computer.
The demodulation software is as follows: and (5) demodulation software written by matlab.
The method for selecting the odd-order quadrature amplitude modulation signal precoding constellation points effectively solves the problem of a precoding method of the quadrature amplitude modulation signals of the visible light system under the condition that the modulation format is the odd-order, and by using the precoding method, the performance of the odd-order visible light system can be effectively improved, and the communication capacity of the system is increased. The method is relatively easy to realize, and after the model is corrected, the pre-coding mode under the current voltage value can be judged by only substituting the set current value and the signal Vpp value into the corrected standard error code difference formula.
EXAMPLE III
A third embodiment of the present invention provides a device for selecting odd-order qam signal precoding constellation points, as shown in fig. 3, the device for selecting odd-order qam signal precoding constellation points of the present embodiment includes:
setting means 310 for setting the bias current and the signal strength peak-to-peak value;
a first recording device 320, configured to select a precoding constellation point as a conventional constellation point, and modulate, receive, and record a first transmission signal;
a first demodulating device 330, configured to demodulate the first transmission signal according to the recorded first transmission signal and obtain a first error rate;
a second recording device 340, configured to select a precoding constellation point as a full gray constellation point, and modulate, receive, and record a second transmission signal;
a second demodulating device 350, configured to demodulate the second transmitted signal according to the recorded second transmitted signal and obtain a second error rate;
the first calculating device 360 is configured to calculate an error correction matrix according to the obtained first error rate and the obtained second error rate;
the second calculating device 370 is used for calculating to obtain a standard error code difference matrix according to the set bias current, the set signal intensity peak-to-peak value and the standard error code difference formula;
and the selecting device 380 is configured to establish a model according to the error correction matrix and the standard error correction matrix, and obtain a suitable precoding constellation point according to the model, the set bias current, and the peak-to-peak value of the signal strength.
Further, the first demodulating apparatus 330 specifically includes:
the first obtaining module 331 is configured to obtain a first error rate through the receiving end detecting device and the decoding recovery device according to the set bias current and the signal intensity peak-to-peak value.
Further, the second modulation device 350 specifically includes:
the second obtaining module 351 is configured to obtain a second bit error rate through the receiving end detection apparatus and the decoding recovery apparatus according to the set bias current and the signal intensity peak-to-peak value.
Further, the first computing device 360 specifically includes:
the first calculating module 361 is used for obtaining an actual error code difference matrix according to the obtained first error code rate and the second error code rate;
and the optimizing module 362 is configured to optimize the actual error correction matrix to obtain an error correction matrix.
The apparatus of this embodiment is used to implement the method for selecting the odd-order qam signal precoding constellation points in the foregoing embodiments, and the implementation method has been described and explained in detail in the foregoing embodiments, and will not be described again here.
Example four
An embodiment of the present invention provides an electronic device, including a memory and a processor memory, where the memory is used to store one or more computer instructions, where the one or more computer instructions are executed by the processor to implement the method for selecting an odd-order qam signal precoding constellation point described in any of the foregoing embodiments.
An embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored, and when the computer program is executed, the method for selecting an odd-order qam signal precoding constellation point according to any of the above embodiments may be implemented. It is clear to those skilled in the art that, for convenience and brevity of description, the specific working process of the apparatus described above may refer to the corresponding process in the foregoing method embodiment, and is not described herein again.
Illustratively, a computer program may be partitioned into one or more modules/units, which are stored in a memory and executed by a processor to implement the present invention. One or more modules/units may be a series of computer program instruction segments capable of performing certain functions, the instruction segments being used to describe the execution of a computer program in a computer device.
The computer device may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The computer device may include, but is not limited to, a processor, a memory. Those skilled in the art will appreciate that the present embodiments are merely exemplary of a computing device and are not intended to be limiting of computing devices, and may include more or fewer components than those shown, or some of the components may be combined, or different components, e.g., the computing device may also include input output devices, network access devices, buses, etc.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage may be an internal storage unit of the computer device, such as a hard disk or a memory of the computer device. The memory may also be an external storage device of the computer device, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), etc. provided on the computer device. Further, the memory may also include both internal and external storage units of the computer device. The memory is used for storing computer programs and other programs and data required by the computer device. The memory may also be used to temporarily store data that has been output or is to be output.
An embodiment of the present invention further provides a computer-readable storage medium storing a computer program, where the computer program is used to enable a computer to implement any one of the above methods for selecting an odd-order qam signal precoding constellation point.
The method for selecting the precoding constellation points of the odd-order quadrature amplitude modulation signals effectively solves the problem of selecting the precoding mode of the quadrature amplitude modulation signals of the visible light system when the modulation format is the odd-order quadrature amplitude modulation signals. The precoding method can effectively improve the performance of odd-order visible light systems and increase the communication capacity of the systems. The method is relatively easy to realize, and after the model is corrected, the pre-coding mode under the current and voltage value can be judged by only substituting the set current value and the signal intensity peak value into the corrected standard error code error formula.
Specific embodiments of the present invention have been described above in detail. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims (10)

1. A method for selecting odd-order quadrature amplitude modulation signal precoding constellation points is characterized by comprising the following steps:
setting bias current and signal intensity peak-to-peak value;
selecting a precoding constellation point as a conventional constellation point, modulating, receiving and recording a first transmission signal;
demodulating the first transmission signal according to the recorded first transmission signal and acquiring a first error rate;
selecting a precoding constellation point as a full gray coding constellation point, modulating, receiving and recording a second transmitting signal;
demodulating the second transmitting signal according to the recorded second transmitting signal and acquiring a second error rate;
calculating to obtain an error correction matrix according to the obtained first error rate and the second error rate;
calculating to obtain a standard error code difference matrix according to the set bias current, the signal intensity peak-to-peak value and a standard error code difference formula;
and establishing a model according to the error correction matrix and the standard error correction matrix, and obtaining a proper pre-coding constellation point according to the model, the set bias current and the peak-to-peak value of the signal intensity.
2. The method of claim 1, wherein demodulating the first transmit signal and obtaining the first bit error rate according to the recorded first transmit signal comprises:
and according to the set bias current and the signal intensity peak-to-peak value, obtaining a first error rate through a receiving end detection device and a decoding recovery device.
3. The method of claim 1, wherein demodulating the second transmission signal and obtaining a second bit error rate according to the recorded second transmission signal comprises:
and according to the set bias current and the signal intensity peak value, obtaining a second error rate through a receiving end detection device and a decoding recovery device.
4. The method of claim 1, wherein the calculating the error correction matrix according to the obtained first error rate and the second error rate comprises:
obtaining an actual error code difference matrix according to the obtained first error code rate and the second error code rate;
and optimizing the actual error code difference matrix to obtain an error code difference correction matrix.
5. An apparatus for selecting odd-order qam signal precoding constellation points, comprising:
setting means for setting a bias current and a signal intensity peak-to-peak value;
the first recording device is used for selecting the precoding constellation point as a conventional constellation point, modulating, receiving and recording a first transmission signal;
the first demodulation device is used for demodulating the first transmission signal according to the recorded first transmission signal and acquiring a first error rate;
the second recording device is used for selecting the precoding constellation point as a full-gray constellation point, modulating, receiving and recording a second transmitting signal;
the second demodulation device is used for demodulating the second transmitting signal according to the recorded second transmitting signal and acquiring a second error rate;
the first calculating device is used for calculating to obtain an error correction matrix according to the obtained first error rate and the second error rate;
the second calculating device is used for calculating to obtain a standard error code difference matrix according to the set bias current, the set signal intensity peak-to-peak value and a standard error code difference formula;
and the selection device is used for establishing a model according to the error code correction matrix and the standard error code correction matrix and obtaining a proper pre-coding constellation point according to the model, the set bias current and the peak-to-peak value of the signal intensity.
6. The apparatus for selecting precoding constellation points for an odd-order qam signal as recited in claim 5, wherein the first demodulation apparatus further comprises:
and the first obtaining module is used for obtaining a first error rate through the receiving end detection device and the decoding recovery device according to the set bias current and the signal intensity peak-to-peak value.
7. The apparatus for selecting precoding constellation points for an odd-order qam signal according to claim 5, wherein the second demodulation apparatus specifically comprises:
and the second obtaining module is used for obtaining a second error rate through the receiving end detection device and the decoding recovery device according to the set bias current and the signal intensity peak-to-peak value.
8. The apparatus for selecting precoding constellation points for an odd-order qam signal according to claim 5, wherein the first computing means specifically comprises:
the first calculation module is used for obtaining an actual error code difference matrix according to the obtained first error code rate and the second error code rate;
and the optimization module is used for optimizing the actual error code difference matrix to obtain an error code difference correction matrix.
9. An electronic device comprising a memory and a processor, the memory configured to store one or more computer instructions, wherein the one or more computer instructions are executable by the processor to implement a method of selecting odd-order quadrature amplitude modulation signal precoding constellation points as recited in any one of claims 1-4.
10. A computer readable storage medium having stored thereon a computer program for causing a computer to perform, when executed, a method of selecting odd order qam signal precoding constellation points as claimed in any one of claims 1 to 4.
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