CN112804007B

CN112804007B - Dual-signal modulation and demodulation method and device for radio-over-fiber communication system

Info

Publication number: CN112804007B
Application number: CN202110392030.1A
Authority: CN
Inventors: 朱敏; 蔡沅成; 王鹏远; 岳凌昊; 黄永明; 尤肖虎
Original assignee: Network Communication and Security Zijinshan Laboratory
Current assignee: Network Communication and Security Zijinshan Laboratory
Priority date: 2021-04-13
Filing date: 2021-04-13
Publication date: 2021-08-31
Anticipated expiration: 2041-04-13
Also published as: WO2022217842A1; CN112804007A

Abstract

The invention provides a dual-signal modulation and demodulation method and a device for a radio over fiber communication system, wherein the modulation method comprises the following steps: performing signal recombination based on the first real-valued signal and the second real-valued signal to obtain a recombined signal; the recombination signal is a double-generation double-sideband signal or a double-generation single-sideband signal; performing electrical dispersion pre-compensation on the recombined signal; performing polar coordinate signal conversion on the recombined signal subjected to electric dispersion precompensation to enable the twinning double sideband signal or the twinning single sideband signal to be represented in a polar coordinate mode; constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of a modulator during electro-optical modulation; electro-optical modulation is performed based on two radio frequency input signals. The modulation method provided by the embodiment of the invention can fully utilize the bandwidth of the receiving and transmitting element, thereby reducing the cost of system devices on the one hand and improving the communication capacity of the system on the other hand.

Description

Dual-signal modulation and demodulation method and device for radio-over-fiber communication system

Technical Field

The invention relates to the technical field of radio over fiber communication, in particular to a method and a device for modulating and demodulating double signals for a radio over fiber communication system.

Background

The 5G era has come to provide communication rates of over 1Gbps, however, the bandwidth and capacity requirements of future 6G wireless communication technologies far exceed those of current 5G technologies, and one of the clear characteristics is the requirement of "full-spectrum" communication capability. The radio-over-fiber communication system, especially the millimeter wave/terahertz communication system, combines the advantages of high capacity, high bandwidth, low time delay and flexible access of radio communication, and can provide strong support for realizing 6G full-spectrum communication. In an optical carrier wireless communication system, in order to avoid a power fading phenomenon induced by optical fiber dispersion of a double-sideband modulation signal, a feasible scheme is to use a dual-drive mach-zehnder modulator (MZM) to modulate a single-sideband signal for transmission in an optical fiber. However, three problems are typically encountered when implementing single sideband signal modulation with dual drive MZMs: firstly, linear conversion of a signal from an electrical domain to an optical domain cannot be realized, and a dual-drive MZM can only work at an orthogonal transmission point to approximate linear modulation, so that an error exists in the signal during electrical dispersion compensation, and the system performance is degraded; secondly, the single-sideband signal cannot fully utilize the bandwidth of a transmitting end device, so that the electrical spectrum efficiency is reduced by half, and the cost waste is caused; finally, the single sideband signal can generate signal-to-signal beat frequency crosstalk (SSBI) after square law detection, and in order to overcome performance degradation caused by the SSBI, either a guard interval with the size equal to the signal bandwidth is reserved at the transmitting end, or an SSBI compensation technology is adopted at the receiving end, the former can halve the spectrum efficiency, and the latter increases the DSP cost and the computational complexity of the system.

At present, linear modulation methods based on dual-drive MZMs have been proposed to achieve better electrical dispersion compensation effects. However, on the one hand, this solution requires that the dc bias voltage of the dual-drive MZM must be perfectly matched with the drive signal, and if there is no matching, the performance of the system will be significantly degraded (the dc drift phenomenon in the actual system can easily cause the two to be mismatched); on the other hand, the scheme only realizes modulation and transmission of a single sideband signal, and still wastes half of the bandwidth of the device. In order to improve the spectrum efficiency of the system and fully utilize the device bandwidth of the system, a common method is to adopt a double-generation single sideband scheme, so that two sideband signals both carry effective information, thereby fully utilizing the device bandwidth of system hardware equipment and doubling the capacity of the system. However, in the demodulation of the twinned single sideband signal, the conventional wireless communication system over optical carrier usually needs two sets of electrical filter, analog-to-digital converter and receiving DSP module, and the duplicated hardware can significantly increase the hardware cost of the system and greatly reduce the possibility of the system merging with the deployed mature commercial system.

Disclosure of Invention

Aiming at the problems in the prior art, the embodiment of the invention provides a dual-signal modulation and demodulation method and system for an optical carrier wireless communication system.

In a first aspect, an embodiment of the present invention provides a dual signal modulation method for an optical carrier wireless communication system, including:

performing signal recombination based on the first real-valued signal and the second real-valued signal to obtain a recombined signal; the recombination signal is a double-generation double-sideband signal or a double-generation single-sideband signal;

performing electrical dispersion pre-compensation on the recombined signal;

performing polar coordinate signal conversion on the recombined signal subjected to electric dispersion precompensation to enable the twinning double sideband signal or the twinning single sideband signal to be represented in a polar coordinate mode;

constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of a modulator during electro-optical modulation;

electro-optical modulation is performed based on two radio frequency input signals.

Further, the signal recombination based on the first real-valued signal and the second real-valued signal to obtain a recombined signal includes:

according to the first relation model, signal recombination is carried out on the basis of the first real-valued signal and the second real-valued signal to obtain a recombined signal; wherein the first relationship model comprises:

s(t)=A+s ₁(t)-js ₂(t)

wherein A is a real number representing a direct current term,s ₁(t) Ands ₂(t) Respectively representing two recombined signals obtained after signal recombination,jthe number of the units of the imaginary number is expressed,tthe time is represented by the time of day,s(t) Representing the double-generated double-sideband signal or the double-generated single-sideband signal obtained after recombination.

Further, two driving signals are constructed based on the polar coordinate mode representation result to carry out digital-to-analog conversion, and the driving signals are used as two radio frequency input signals of a modulator during electro-optical modulation, and the method comprises the following steps:

according to a second relation model, constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of the dual-drive Mach-Zehnder modulator during electro-optical modulation; wherein the second relationship model comprises:

wherein the content of the first and second substances,

represents the half-wave voltage parameter of the dual-drive Mach-Zehnder modulator, pi represents the circumference ratio,

the inverse cosine function is represented as a function of,

representing the maximum amplitude of the signal, t representing time,

which is representative of the first drive signal and,

which is representative of the second drive signal, is,

representing the amplitude of the double raw double sideband or the double raw single sideband signal in a polar coordinate system,

representing the phase of the double raw double sideband or double raw single sideband signal in a polar coordinate system.

In a second aspect, an embodiment of the present invention provides a dual signal demodulation method for a radio over fiber communication system, including:

carrying out carrier extraction based on the sampling digital signal; the sampling digital signal comprises a carrier wave and a double-generation double-sideband signal or a double-generation single-sideband signal;

performing signal recovery based on the extracted carrier; the signal is restored to be the multiplication of the extracted carrier wave and the component of the sampling digital signal, and then a high-frequency item is filtered to obtain a first path of restored signal and a second path of restored signal;

performing signal recombination on the recovered first path of signal and the second path of signal to obtain corresponding recombined signals;

performing electric dispersion post-compensation on the recombined signal;

performing signal decomposition on the recombined signal compensated after the electric dispersion to obtain a first real-valued signal and a second real-valued signal;

signal demodulation is performed based on the first and second real-valued signals.

Further, still include:

reserving a preset guard interval between a carrier and a signal;

accordingly, the carrier is extracted according to a preset guard interval when the carrier extraction is performed based on the sampled digital signal.

In a third aspect, an embodiment of the present invention provides a dual-signal modulation apparatus for a radio over fiber communication system, including:

the first signal recombination module is used for carrying out signal recombination on the basis of the first real-valued signal and the second real-valued signal to obtain a recombined signal; the recombination signal is a double-generation double-sideband signal or a double-generation single-sideband signal;

the electric dispersion pre-compensation module is used for carrying out electric dispersion pre-compensation on the recombined signal;

the polar coordinate signal conversion module is used for performing polar coordinate signal conversion on the recombined signal subjected to electric dispersion precompensation to enable the twinborn double-sideband signal or the twinborn single-sideband signal to be represented in a polar coordinate mode;

the signal construction module is used for constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result and using the two driving signals as two radio frequency input signals of the modulator during electro-optical modulation;

and the modulation module is used for carrying out electro-optical modulation based on the two radio frequency input signals.

In a fourth aspect, an embodiment of the present invention provides a dual signal demodulation apparatus for a radio over fiber communication system, including:

the carrier extraction module is used for carrying out carrier extraction based on the sampling digital signal; the sampling digital signal comprises a carrier wave and a double-generation double-sideband signal or a double-generation single-sideband signal;

the signal recovery module is used for recovering signals based on the extracted carrier waves; the signal is restored to be the multiplication of the extracted carrier wave and the component of the sampling digital signal, and then a high-frequency item is filtered to obtain a first path of restored signal and a second path of restored signal;

the second signal recombination module is used for carrying out signal recombination on the basis of the recovered first path of signal and the recovered second path of signal to obtain a corresponding recombined signal;

the electric dispersion post-compensation module is used for carrying out electric dispersion post-compensation on the recombined signal;

the signal decomposition module is used for performing signal decomposition on the recombined signal compensated after the electric dispersion to obtain a first real-valued signal and a second real-valued signal;

and the signal demodulation module is used for carrying out signal demodulation based on the first real-value signal and the second real-value signal.

In a fifth aspect, an embodiment of the present invention provides an over-the-optical wireless communication system supporting dual-signal modulation and demodulation, including: optical transceivers and wireless transceivers;

a step of implementing the dual-signal modulation method for an optical radio communication system according to the first aspect in the optical transceiver; and the combination of (a) and (b),

correspondingly, the following steps of the dual-signal demodulation method for the radio over fiber communication system are implemented in the wireless transceiver:

performing signal decomposition on the recombined signal to obtain a first real-valued signal and a second real-valued signal;

In a sixth aspect, an embodiment of the present invention provides an over-the-optical wireless communication system supporting dual-signal modulation and demodulation, including: optical transceivers and wireless transceivers;

a step of implementing the method for demodulating dual signals for a radio over fiber communication system according to the second aspect in the wireless transceiver; and the combination of (a) and (b),

correspondingly, the following steps of the dual-signal modulation method for the radio over fiber communication system are realized in the optical transceiver:

performing polar coordinate signal conversion on the recombined signal to enable the twinborn double sideband signal or the twinborn single sideband signal to be represented in a polar coordinate mode;

In a seventh aspect, an embodiment of the present invention further provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the dual-signal modulation method for a radio over fiber communication system according to the first aspect when executing the program; or, the computer program when executed by a processor implements the steps of the method for dual signal demodulation for a wireless communication over optical system according to the second aspect.

In an eighth aspect, an embodiment of the present invention further provides an electronic device, including a memory, a first processor, a second processor, a first computer program stored on the memory and operable on the first processor, and a second computer program stored on the memory and operable on the second processor, where the first processor implements the steps of the dual signal modulation method for an optical radio-over-fiber communication system according to the first aspect when executing the first computer program; the second processor, when executing the second computer program, implements the steps of the method for dual signal demodulation for a wireless communication over optical carrier system according to the second aspect.

In a ninth aspect, the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the dual signal modulation method for a radio over fiber communication system according to the first aspect; or, the computer program when executed by a processor implements the steps of the method for dual signal demodulation for a wireless communication over optical system according to the second aspect.

In a tenth aspect, the present invention further provides a non-transitory computer readable storage medium, on which a first computer program and a second computer program are stored, the first computer program, when executed by a first processor, implementing the steps of the dual signal modulation method for a radio over fiber communication system as described in the first aspect above; the second computer program, when executed by the second processor, implements the steps of the method for dual signal demodulation for a wireless communication over optical carrier system as described in the second aspect above.

As can be seen from the foregoing technical solutions, a dual-signal modulation and demodulation method and apparatus for a radio over fiber communication system according to an embodiment of the present invention include: performing signal recombination based on the first real-valued signal and the second real-valued signal to obtain a recombined signal; the recombination signal is a double-generation double-sideband signal or a double-generation single-sideband signal; performing electrical dispersion pre-compensation on the recombined signal; performing polar coordinate signal conversion on the recombined signal subjected to electric dispersion precompensation to enable the twinning double sideband signal or the twinning single sideband signal to be represented in a polar coordinate mode; constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of a modulator during electro-optical modulation; electro-optical modulation is performed based on two radio frequency input signals. The modulation method provided by the embodiment of the invention can fully utilize the bandwidth of the receiving and transmitting element, thereby reducing the cost of system devices on the one hand and improving the communication capacity of the system on the other hand.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic flowchart of a dual signal modulation method for a wireless over fiber communication system according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a photon-assisted millimeter wave/terahertz signal transmitter supporting dual-signal modulation according to an embodiment of the present invention;

fig. 3 is a schematic flow chart of a transmitting DSP module supporting dual signal modulation according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of the electrical spectrum of a double sideband signal before and after linear modulation according to one embodiment of the present invention;

FIG. 5 is a schematic diagram of the electrical spectrum of a double raw single sideband signal before and after linear modulation according to one embodiment of the present invention;

fig. 6 is a flowchart illustrating a dual signal demodulation method for a wireless over fiber communication system according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a millimeter wave/terahertz signal receiver supporting dual-signal demodulation according to an embodiment of the present invention;

fig. 8 is a schematic diagram of a conventional twinborn single sideband transceiver in a wireless over fiber communication system;

fig. 9 is a schematic diagram of another conventional twinborn single sideband signal receiver architecture in a wireless over fiber communication system;

FIG. 10 is a flow chart of a receiving DSP module supporting dual signal demodulation according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a dual-signal modulation apparatus for a wireless over fiber communication system according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of a dual signal demodulation apparatus for a wireless over fiber communication system according to an embodiment of the present invention;

fig. 13 is a diagram of a wireless over fiber communication system supporting dual signal modulation and demodulation according to another embodiment of the present invention;

fig. 14 is a schematic diagram illustrating a relationship between the error vector magnitude of the dual signals recovered by the receiving end and the received optical power according to an embodiment of the present invention;

fig. 15 is a schematic diagram of a relationship curve between the error vector magnitude of two double-sideband signals recovered by a receiving end and the received optical power by respectively adopting an electrical dispersion pre-compensation and an electrical dispersion post-compensation method under a double-sideband signal modulation scheme provided in an embodiment of the present invention;

fig. 16 is a schematic physical structure diagram of an electronic device according to an embodiment of the present invention;

the reference numerals in the above figures have the meanings given respectively:

in fig. 2, the respective symbols represent: 11 denotes a transmitting DSP block; 121 denotes a first digital-to-analog converter; 122 denotes a second digital-to-analog converter; 13 denotes a transmission laser; 14, electro-optical modulation; 15, a local oscillator laser; 16 denotes a standard single mode optical fibre; 17 denotes optical heterodyne detection; 18 denotes a band pass filter; 19 denotes a transmitting antenna;

in fig. 3, the respective symbols represent: 11 denotes a transmitting DSP block; 111 denotes a first signal generation module; 112 denotes a second signal generation module; 113 signal recombination; 114 denotes electrical dispersion pre-compensation; 115 denotes polar coordinate signal conversion; 116 represents a first drive signal; 117 denotes a second drive signal;

in fig. 7, the symbols respectively represent: 21 denotes a receiving antenna; 22 denotes frequency down conversion; 23 denotes an analog-to-digital converter; 24 denotes a receiving DSP block;

in fig. 8, the respective symbols represent: 25 denotes LSB processing; RSB processing is indicated at 26; 251 denotes an LSB optical filter; 252, LSB photodetector; 253 denotes an LSB transmission antenna; 254 denotes an LSB receiving antenna 254; 255 denotes LSB frequency down conversion; 256 denotes an LSB analog-to-digital converter; 257 denotes the LSB receiving DSP module; 261 denotes an RSB optical filter; 262 denotes an RSB photodetector; 263 denotes an RSB transmitting antenna; 264 denotes an RSB receiving antenna; 265 denotes RSB frequency down conversion; 266 denotes an RSB analog-to-digital converter; 267 denotes an RSB receiving DSP block;

in fig. 9, the respective symbols represent: 21 denotes a receiving antenna; 22 denotes frequency down conversion; 27 denotes LSB reception; RSB reception at 28; 271 denotes a low-pass filter; 272 denotes an LSB analog-to-digital converter; 273 denotes an LSB receiving DSP module; 281 denotes a high pass filter; 282 denotes an RSB analog-to-digital converter; 283 denotes an RSB receiving DSP block;

in fig. 10, the respective symbols represent: 24 denotes a receiving DSP block; 241 denotes a band pass filter; 242 denotes a hilbert transform; 243 denotes a first multiplier; 244 denotes a second multiplier; 245 denotes a first low-pass filter; 246 denotes a second low-pass filter; 247 denotes post-electrical dispersion compensation; 248 denotes signal decomposition; 249 denotes a first signal demodulation unit; 2410 denotes a second signal demodulation unit.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments, but not all embodiments, of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The dual signal modulation and demodulation method for the radio over fiber communication system according to the present invention will be explained and explained in detail by specific embodiments.

Fig. 1 is a schematic flowchart of a dual signal modulation method for a wireless over fiber communication system according to an embodiment of the present invention; as shown in fig. 1, the method includes:

step 101: performing signal recombination based on the first real-valued signal and the second real-valued signal to obtain a recombined signal; the recombined signal is a double-generation double-sideband signal or a double-generation single-sideband signal.

Step 102: and performing electric dispersion pre-compensation on the recombined signal.

Step 103: and performing polar coordinate signal conversion on the recombined signal subjected to electric dispersion pre-compensation to enable the twinning double sideband signal or the twinning single sideband signal to be represented in a polar coordinate mode.

Step 104: and constructing two driving signals for digital-to-analog conversion based on the polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of the modulator during electro-optical modulation.

Step 105: electro-optical modulation is performed based on two radio frequency input signals.

In this embodiment, it should be noted that the dual-signal modulation method for the radio over fiber communication system according to the embodiment of the present invention is applied to a photon-assisted millimeter wave/terahertz signal transmitter supporting dual-signal modulation, where a schematic structural diagram of the photon-assisted millimeter wave/terahertz signal transmitter supporting dual-signal modulation is shown in fig. 2, and the photon-assisted millimeter wave/terahertz signal transmitter supporting dual-signal modulation includes: the system comprises a sending DSP module 11, a first digital-to-analog converter 121, a second digital-to-analog converter 122, a sending laser 13, an electro-optical modulator 14, a local oscillator laser 15, a standard single-mode fiber 16, an optical heterodyne detection 17, a band-pass filter 18 and a transmitting antenna 19; the detailed structure of the transmitting DSP module 11 is shown in fig. 3, and includes a first signal generating module 111, a second signal generating module 112, a signal recombination 113, an electric dispersion pre-compensation 114, a polar coordinate signal conversion 115, a first driving signal 116, and a second driving signal 117.

In order to better understand the present invention, the following examples are further provided to illustrate the content of the present invention, but the present invention is not limited to the following examples.

Specifically, the sending DSP module 11 completes digital signal processing required for dual signal modulation, and mainly includes the following steps.

And (5) signal recombination. Suppose thata(t) Andb(t) The real-valued signals generated by the first signal generation module 111 and the second signal generation module 112, i.e. the first real-valued signal and the second real-valued signal, (without limitation to format, such as PAM, DMT, CAP, etc.), which can be any real-valued signals, have no influence on the modulation method according to the embodiment of the present invention, regardless of whether the real-valued signals are overlapped, and in this embodiment, the two real-valued signals are completely overlapped (i.e. the two signals have the same intermediate frequency and the same bandwidth), which is referred to as "the two signals have the same intermediate frequency" and "the same bandwidth", hereinaftera(t) In order to be able to signal 1, the signal,b(t) Signal 2. After signal recombination 113, the output signal is:

s(t)=A+s ₁(t)-js ₂(t) (1)

wherein the content of the first and second substances,Ais a real number, representing a direct current term,s ₁(t) Ands ₂(t) Respectively representing two recombined signals obtained after signal recombination. When taking:

(2)

at this time, the process of the present invention,s(t) Represents a pair ofA double sideband signal (a double sideband signal) in which signal 1 (i.e. the first real valued signal) and signal 2 (i.e. the second real valued signal) overlap each other spectrally but are 90 ° in phase quadrature, as shown in fig. 4, a signal having such a spectrum in an embodiment of the present invention is referred to as a double sideband signal. On the other hand, when changings ₁(t) Ands ₂(t) Expression (c):

(3)

wherein the content of the first and second substances,

representing a real-valued signalxTaking the hilbert transform. At this time, the process of the present invention,s(t) Representing a pair of single sideband signals (twinned single sideband signals) comprising the Left Sideband (LSB) of signal 1, as expressed in

And the Right Sideband (RSB) of Signal 2, expressed as

There is no overlap of the two spectra, as shown in fig. 5. A signal having such a frequency spectrum is referred to as a twinned single sideband signal in the present invention.

And (3) an electric dispersion pre-compensation step. For the recombined signals(t)=A+s ₁(t)-js ₂(t) The electrical dispersion pre-compensation is carried out to overcome the intersymbol interference caused by the dispersion of signals during the optical fiber transmission. It should be noted that this step is not necessary, and for example, post-dispersion compensation may be used instead at the receiving end.

And a polar coordinate signal conversion step. The target signal of the double-sideband or double-sideband (i.e. the recombined signal after electric dispersion pre-compensation) is expressed in polar coordinate mode, i.e.

(4)

Wherein the content of the first and second substances,r(t)=abs[s(t)]andθ(t)=angle[s(t)]respectively representing the amplitude and the phase of the double-generation double-sideband or the double-generation single-sideband signal under a polar coordinate system, and abs and angle respectively representing a calculated modulus value and a phase angle function.

Two drive signals are constructed. By usingr _max=max[r(t)]Represents the maximum amplitude of the signal, order

(5)

Wherein the content of the first and second substances,V _πrepresents the half-wave voltage parameter of the dual drive MZM,πit is shown that the circumferential ratio,

representing an inverse cosine function.

And

after digital-to-analog conversion (DAC) operation is finished, the signals are respectively used as radio frequency driving signals of an upper arm and a lower arm of the dual-drive MZM so as to finish electro-optic modulation.

When the dual-drive MZM bias is at the maximum transmission point, namely the phases caused by the direct current bias of the upper arm and the lower arm are equal, the double-drive MZM bias is used

It is shown that, under the drive of equation (5), the signal light output by the dual-drive MZM is expressed as:

(6)

wherein the content of the first and second substances,E _in(t) Representing the light wave output by the transmit laser 13. FromEquation (6) it can be seen that when the dual drive MZM is driven with two signals configured, the double-sideband or double-sideband target signal is linearly modulated into the optical field, and the schematic diagrams of the two signals are shown in fig. 4 and 5, respectively. Different from the linear modulation similar to the traditional orthogonal bias dual-drive MZM, the implementation can realize ideal linear mapping of a target signal from an electric domain to an optical field, so that the electric dispersion compensation (transmitting end pre-compensation or receiving end post-compensation) can achieve a better effect.

In this embodiment, it should be noted that, unlike the existing linear modulation method based on dual-drive MZM, the existing method only performs linear modulation on a single sideband signal, and cannot fully utilize the bandwidth of a system device; on the other hand, when the existing method realizes the linear modulation characteristic, the dual-drive MZM is still biased at the orthogonal transmission point, namely the phase difference caused by the direct current bias of the two arms is

Therefore, in order to cancel the phase difference caused by the quadrature point DC offset, it is necessary to set the two driving signals to be respectively

，

It is apparent that the incoming rf signal is now constrained by the dc bias of the modulator. However, in an actual system, the dc offset of the modulator is easy to drift along with the rise of the operating temperature, and once the dc offset deviates from the quadrature operating point, the dc offset and the driving signal are mismatched, so that the linear modulation effect of the signal is destroyed, and the modulation quality of the signal at the transmitting end is reduced.

In embodiments of the present invention, this problem is solved by releasing the modulator dc bias from limiting the input rf signal. The double-drive MZM direct current bias is arranged at the maximum transmission point, namely the direct current bias voltage difference of two arms is zero, which is well realized in an actual system, the same direct current bias voltage is divided into two paths to be respectively supplied to the upper arm and the lower arm of the double-drive MZM, so that the bias characteristic of the maximum transmission point can not be damaged no matter how the direct current bias voltage drifts along with the working environment, and therefore, the direct current drift can not influence the effect of linear modulation. In addition, the embodiment of the invention supports the linear modulation of the double signals including the double-sideband and the double-sideband signal, thereby not only increasing the communication capacity of the transmitting end, but also fully utilizing the bandwidth of the device at the transmitting end.

The above process realizes linear modulation of the double-generation double-sideband and the double-generation single-sideband signals, then, the signal light is transmitted to a far-end base station through a standard single mode fiber 16, after being coupled with a local oscillator laser 15, optical heterodyne detection 17 is adopted for photoelectric conversion, beat frequency of the signal light and the local oscillator light can generate required millimeter wave/terahertz (Mm & THz) signals, and the signals can be extracted through a band-pass filter 18 and then transmitted through a transmitting antenna 19.

In this embodiment, it should be noted that the embodiment of the present invention may be applied to a transmitting end, and based on a dual-drive MZM, a polar coordinate signal conversion method is adopted to implement linear modulation of dual signals, so that constraints between a driving signal and a dc bias of a modulator may be released, and meanwhile, the linear modulation supports efficient electric dispersion compensation of a dual-sideband or a dual-sideband signal. In addition, compared with the traditional single-sideband signal modulation mode, the embodiment of the invention adopts double-signal modulation, which not only can fully utilize the bandwidth of a system device, but also can improve the communication rate and capacity of the system.

In this embodiment, it is preferable that the dual-drive mach-zehnder modulator is set to operate at a maximum transmission point, and the electro-optical modulation is performed based on two radio frequency input signals.

As can be seen from the foregoing technical solutions, in the dual-signal modulation method for an optical wireless communication system according to the embodiments of the present invention, a recombined signal is obtained by performing signal recombination based on a first real-valued signal and a second real-valued signal; the recombination signal is a double-generation double-sideband signal or a double-generation single-sideband signal; performing electrical dispersion pre-compensation on the recombined signal; performing polar coordinate signal conversion on the recombined signal subjected to electric dispersion precompensation to enable the twinning double sideband signal or the twinning single sideband signal to be represented in a polar coordinate mode; constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of a modulator during electro-optical modulation; electro-optical modulation is performed based on two radio frequency input signals. The modulation method provided by the embodiment of the invention can fully utilize the bandwidth of the receiving and transmitting element, thereby reducing the cost of system devices on the one hand and improving the communication capacity of the system on the other hand.

On the basis of the foregoing embodiment, in this embodiment, the performing signal recombination based on the first real-valued signal and the second real-valued signal to obtain a recombined signal includes:

s(t)=A+s ₁(t)-js ₂(t)

wherein the content of the first and second substances,Afor a real number to represent the direct current term,s ₁(t) Ands ₂(t) Respectively representing two recombined signals obtained after signal recombination,jthe number of the units of the imaginary number is expressed,tthe time is represented by the time of day,s(t) Representing the double-generated double-sideband signal or the double-generated single-sideband signal obtained after recombination.

In this embodiment, it should be noted that, according to the first relationship model, signal recombination is performed based on the first real-valued signal and the second real-valued signal to obtain a recombined signal, where the recombined signal is a double-living double-sideband signal or a double-living single-sideband signal, which is beneficial to fully utilizing a bandwidth of a transmitting end device and improving electrical spectrum efficiency, thereby achieving cost saving.

On the basis of the above embodiments, in this embodiment, constructing two driving signals for digital-to-analog conversion based on the polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of a modulator during electro-optical modulation includes:

wherein the content of the first and second substances,

the inverse cosine function is represented as a function of,

representing the maximum amplitude of the signal, t representing time,

which is representative of the first drive signal and,

which is representative of the second drive signal, is,

In this embodiment, it should be noted that, in the scheme for implementing signal linear modulation according to this embodiment, by biasing the dual-drive mach-zehnder modulator at the maximum transmission point, the constraint of the direct current bias of the dual-drive mach-zehnder modulator on the radio frequency input signal is released, and the influence of the direct current drift on the signal linear modulation effect can be avoided.

Fig. 6 is a flowchart illustrating a dual signal demodulation method for a wireless over fiber communication system according to an embodiment of the present invention; as shown in fig. 6, the method includes:

step 601: carrying out carrier extraction based on the sampling digital signal; the sampled digital signal includes a carrier and either a double-sideband signal or a double-sideband signal.

Step 602: performing signal recovery based on the extracted carrier; and the signal is recovered by multiplying the extracted carrier wave by the component of the sampling digital signal, and then filtering high-frequency terms to obtain a first path of recovered signal and a second path of recovered signal.

Step 603: and performing signal recombination on the basis of the recovered first path of signal and the second path of signal to obtain a corresponding recombined signal.

Step 604: and performing electric dispersion post-compensation on the recombined signal.

Step 605: and performing signal decomposition on the recombined signal compensated after the electric dispersion to obtain a first real-valued signal and a second real-valued signal.

Step 606: signal demodulation is performed based on the first and second real-valued signals.

In this embodiment, it should be noted that the dual-signal demodulation method for the radio over fiber communication system according to the embodiment of the present invention is applied to a millimeter wave/terahertz signal receiver supporting dual-signal demodulation, and a schematic structural diagram of the millimeter wave/terahertz signal receiver supporting dual-signal demodulation is shown in fig. 7, where the photon-assisted millimeter wave/terahertz signal transmitter supporting dual-signal modulation includes: a receiving antenna 21, a frequency down-conversion 22, an analog-to-digital converter 23 and a receiving DSP module 24; the receiving DSP module 24 is composed of a band pass filter 241, a hilbert transform 242, a first multiplier 243, a second multiplier 244, a first low pass filter 245, a second low pass filter 246, an electric dispersion post-compensation 247, a signal decomposition 248, a first signal demodulation 249, and a second signal demodulation 2410, as shown in fig. 10.

Specifically, in order to further embody the advance of the receiver of the present invention, fig. 8 shows a schematic diagram of a conventional double-sideband generation single-sideband signal transceiver in an optical wireless communication system, where fig. 8 includes a Left Sideband (LSB) process 25 and a Right Sideband (RSB) process 26, where the LSB process 25 is composed of an LSB optical filter 251, an LSB photodetector 252, an LSB transmitting antenna 253, an LSB receiving antenna 254, an LSB frequency down-conversion 255, an LSB analog-to-digital converter 256, and an LSB receiving DSP module 257, and the RSB process 26 is composed of an RSB optical filter 261, an RSB photodetector 262, an RSB transmitting antenna 263, an RSB receiving antenna 264, an RSB frequency down-conversion 265, an RSB analog-to-digital converter 266, and an RSB receiving DSP module 267; the system separates LSB and RSB by optical filter on optical path, then processes LSB and RSB signal by two sets of photoelectric detector, receiving and transmitting antenna, frequency down-conversion, A/D converter and DSP receiving module. Fig. 9 is a schematic diagram of another conventional twinborn single sideband receiver structure in an optical wireless communication system, where fig. 9 includes a receiving antenna 21, a frequency down-conversion 22, an LSB reception 27, and an RSB reception 28. Where LSB receive 27 is comprised of low pass filter 271, LSB analog to digital converter 272 and LSB receive DSP block 273, and RSB receive 28 is comprised of low pass filter 281, RSB analog to digital converter 282 and RSB receive DSP block 283. Compared with the receiver shown in fig. 8, the receiver shown in fig. 9 saves a large amount of hardware cost, the optical path does not need to repeat hardware, the circuit only needs one set of antenna and frequency down-conversion module, however, when the circuit realizes the demodulation of the twins single sideband signal, two sets of electric filters, analog-to-digital converters and a DSP receiving module are still needed. In summary, compared with the conventional dual-signal receiver, the millimeter wave/terahertz signal receiver provided by the invention can significantly reduce the hardware cost of the receiver, not only can support the demodulation of a double-sideband or a double-sideband signal, but also can be compatible with an optical carrier wireless communication system based on single-signal modulation and demodulation.

The receiving end adopts a heterodyne mixing mode to complete down-conversion of the millimeter wave/terahertz signal, and the signal output by the frequency down-conversion 22 can be represented as:

(7)

wherein the content of the first and second substances,Mis a constant, which is proportional to the average optical power output by the transmit laser 13 and the local oscillator laser 15,

and

respectively representing the central angular frequency and the carried phase noise of the millimeter wave/terahertz signal after down-conversion. In the formula (7), the first term is an intermediate frequency carrier, and the second term and the third term respectively represent two different signals.

Further, the intermediate frequency signal is subjected to analog-to-digital conversion, and then the demodulation of double signals is completed by using a single receiving DSP module. The detailed structure of the receiving DSP module 24 is shown in fig. 10, and includes a band-pass filter 241, a hilbert transform 242, a first multiplier 243, a second multiplier 244, a first low-pass filter 245, a second low-pass filter 246, an electric dispersion compensation 247, a signal decomposition 248, a first signal demodulation 249, and a second signal demodulation 2410. The receiving DSP module 24 implements demodulation of the dual signal including the following steps:

and (5) carrier extraction. The carrier is extracted by a band pass filter 241, whose expression is:

(8)

further, in order to better extract the carrier, a small guard interval (e.g. 500 MHz) may be reserved between the carrier and the signal (sideband signal, i.e. sampling signal is actually composed of the carrier and the sideband signal), and since the bandwidth of the signal in the millimeter wave/terahertz communication system can be as high as 10GHz or more, such an interval does not bring about a significant reduction in the spectrum efficiency.

And (6) recovering the signal. First, in the first step, the extracted carrier is multiplied by the component of the original signal (i.e. the sampled signal, including the carrier and the sideband signal) by using the first multiplier 243, and then the first low-pass filter 245 is used to filter out the high-frequency term, so as to recover the first signal, as shown in the following formula:

(9)

wherein the content of the first and second substances,

representing a low pass filtering operation. Secondly, the extracted carrier wave is subjected to Hilbert transform to obtain

Then, the second path signal can be recovered by using the second multiplier 244 and the second low-pass filter 246 by using the same signal recovery method as the first step, as shown in the following equation:

(10)

and (5) compensating after electric dispersion. Recombining the two recovered signals, i.e.s _r(t)=s ₁(t)-js ₂(t) And then post-dispersion compensation 247 is performed to overcome intersymbol interference caused by dispersion of the signal during transmission through the optical fiber. It should be noted that this step is not necessary, and can be skipped if the transmitting end already employs electric dispersion pre-compensation.

And a signal decomposition step. Receiver-side signal decomposition is the reverse process of the sender-side signal reassembly, with the purpose of obtaining a sums ₁(t) Ands ₂(t) Separating target signala(t) Andb(t). For a double sideband signal, according to equation (2),a(t) Andb(t) Recovery can be achieved by:

(11)

whereas for a twinned single sideband signal, according to equation (3),a(t) Andb(t) Recovery can be achieved by:

(12)

and (5) signal demodulation. After signal decomposition 248, we separatea(t) Andb(t) And then, using first signal demodulation 249 and second signal demodulation 2410, respectivelya(t) Andb(t) The demodulation and demodulation operation of (2) is consistent with the conventional signal demodulation steps, and is not separately described here.

In this embodiment, it should be noted that, no matter the double sideband or the double sideband signal, there is no influence of SSBI because there is no beat operation of the signal and the signal in the signal recovery process, which is another feature of the present invention.

In this embodiment, it should be noted that the embodiment of the present invention may be applied to a receiving end, two sets of repeated hardware devices are not required, and dual signals may be recovered respectively only by completing reception through a single set of hardware and then matching with a specific DSP process, so that the requirement of dual signal demodulation on hardware devices is significantly reduced, and actually, the modulation and demodulation of dual signals is completely compatible with the hardware requirement of the conventional single-sideband/dual-sideband modulation system.

As can be seen from the above technical solutions, the dual-signal demodulation method for the radio over fiber communication system according to the embodiments of the present invention performs carrier extraction based on the sampled digital signal; the sampling digital signal comprises a carrier wave and a double-generation double-sideband signal or a double-generation single-sideband signal; performing signal recovery based on the extracted carrier; the signal is restored to be the multiplication of the extracted carrier wave and the component of the sampling digital signal, and then a high-frequency item is filtered to obtain a first path of restored signal and a second path of restored signal; performing signal recombination on the recovered first path of signal and the second path of signal to obtain corresponding recombined signals; performing electric dispersion post-compensation on the recombined signal; performing signal decomposition on the recombined signal compensated after the electric dispersion to obtain a first real-valued signal and a second real-valued signal; performing signal demodulation based on the first and second real-valued signals; the embodiment of the invention is applied to a wireless receiving end of a double-generation double-sideband or double-generation single-sideband signal, can obviously reduce the requirement of double-signal demodulation on hardware equipment, and can complete the receiving and demodulating work of double signals only by adopting a traditional wireless receiving link (a frequency down-conversion module and an analog-to-digital converter) to be matched with corresponding Digital Signal Processing (DSP).

On the basis of the above embodiment, in this embodiment, the method further includes:

reserving a preset guard interval between a carrier and a signal;

In this embodiment, it should be noted that, in order to better extract the carrier, a smaller guard interval (e.g. 500 MHz) may be reserved between the carrier and the signal, and since the bandwidth of the signal in the millimeter wave/terahertz communication system may be as high as 10GHz or more, such an interval does not bring a significant drop to the spectrum efficiency.

In this embodiment, it should be noted that the preset guard interval may be 0.3GHz to 1.0 GHz.

As can be seen from the above technical solutions, in the dual-signal demodulation method for the radio over fiber communication system according to the embodiments of the present invention, since the signal recovery employs a carrier and signal mixing manner, the system is completely not affected by the SSBI, and only a small preset guard interval needs to be reserved for extracting the carrier.

Fig. 11 is a schematic structural diagram of a dual-signal modulation apparatus for a wireless over fiber communication system according to an embodiment of the present invention, as shown in fig. 11, the system includes: a first signal recombination module 1101, an electrical dispersion pre-compensation module 1102, a polar coordinate signal conversion module 1103, a signal construction module 1104, and a modulation module 1105, wherein:

the first signal recombining module 1101 is configured to perform signal recombining based on the first real-valued signal and the second real-valued signal to obtain a recombined signal; the recombination signal is a double-generation double-sideband signal or a double-generation single-sideband signal;

an electrical dispersion pre-compensation module 1102, configured to perform electrical dispersion pre-compensation on the recombined signal;

a polar coordinate signal conversion module 1103, configured to perform polar coordinate signal conversion on the recombined signal after the electrical dispersion pre-compensation so that the double-birth double-sideband signal or the double-birth single-sideband signal is represented in a polar coordinate manner;

the signal construction module 1104 is used for constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result, and the two driving signals are used as two radio frequency input signals of the modulator during electro-optical modulation;

a modulation module 1105 for performing electro-optical modulation based on two radio frequency input signals.

The dual-signal modulation apparatus for the radio over fiber communication system according to the embodiment of the present invention may be specifically configured to execute the dual-signal modulation method for the radio over fiber communication system according to the above embodiment, and the technical principle and the beneficial effects thereof are similar to each other.

Fig. 12 is a schematic structural diagram of a dual-signal demodulation apparatus for a wireless over fiber communication system according to an embodiment of the present invention, as shown in fig. 12, the system includes: a carrier extraction module 1201, a signal recovery module 1202, a second signal recombination module 1203, an electrical dispersion post-compensation module 1204, a signal decomposition module 1205 and a signal demodulation module 1206, wherein:

the carrier extraction module 1201 is configured to perform carrier extraction based on the sampled digital signal; the sampling digital signal comprises a carrier wave and a double-generation double-sideband signal or a double-generation single-sideband signal;

a signal recovery module 1202, configured to perform signal recovery based on the extracted carrier; the signal is restored to be the multiplication of the extracted carrier wave and the component of the sampling digital signal, and then a high-frequency item is filtered to obtain a first path of restored signal and a second path of restored signal;

a second signal recombining module 1203, configured to perform signal recombining based on the recovered first path of signal and the second path of signal to obtain a corresponding recombined signal;

an electrical dispersion post-compensation module 1204, configured to perform electrical dispersion post-compensation on the recombined signal;

a signal decomposition module 1205, configured to perform signal decomposition on the recombined signal compensated after the electrical dispersion to obtain a first real-valued signal and a second real-valued signal;

a signal demodulation module 1206, configured to perform signal demodulation based on the first real-valued signal and the second real-valued signal.

The dual-signal demodulation apparatus for a radio over fiber communication system according to the embodiment of the present invention may be specifically configured to execute the dual-signal demodulation method for a radio over fiber communication system according to the above embodiment, and the technical principle and the beneficial effect thereof are similar.

Fig. 13 is a schematic structural diagram of an over-the-optical wireless communication system supporting dual-signal modulation and demodulation according to an embodiment of the present invention, and as shown in fig. 13, the system includes: an optical transceiver and a wireless transceiver, wherein:

On the basis of the above embodiments, an embodiment of the present invention provides an optical wireless communication system supporting dual signal modulation and demodulation, including: an optical transceiver and a wireless transceiver, wherein:

the steps of the method for dual signal demodulation for a wireless communication over optical carrier system according to the second aspect are implemented in the wireless transceiver.

In this embodiment, it can be understood that one of the electrical dispersion pre-compensation at the transmitting end and the electrical dispersion post-compensation at the receiving end is selected for use.

In this embodiment, it should be noted that fig. 13 is a schematic structural diagram of an optical wireless communication system supporting dual-signal modulation and demodulation according to an embodiment of the present invention. The whole system consists of an optical transceiver and a wireless transceiver, wherein in the optical transceiver, the modulation of a double-generation double-sideband signal or a double-generation single-sideband signal is realized by utilizing a polar coordinate signal conversion method based on a single double-drive MZM, then the signal is transmitted to a far end through an optical fiber, one path of local oscillator light is coupled to generate a millimeter wave/terahertz signal by utilizing optical heterodyne beat frequency, and the frequency of the millimeter wave/terahertz signal is adjustable. In the wireless transceiver, a target millimeter wave/terahertz signal is firstly subjected to down-conversion by a frequency mixer, then is sent to a receiving DSP module after analog-to-digital conversion, and two paths of signals are sequentially recovered in the DSP by a carrier and signal multiplication method.

Based on the system structure shown in fig. 13, after transmission through a 25 km optical fiber and adoption of a dispersion pre-compensation scheme, fig. 14 shows a relationship curve between the error vector magnitude and the received optical power after demodulation of a dual signal with a carrier frequency of 60GHz and a total rate of 50 Gbps. Wherein, both signals adopt CAP-32QAM modulation format, and the baud rate is 5 Gbaud/s. It can be seen that the error vector magnitude of both signals decreases with increasing optical power, and approaches 6% at-16 dBm, regardless of the double-sideband or double-sideband modulation scheme. For the double-sideband signal modulation format, fig. 15 further shows a relationship curve between the magnitude of the error vector of the signal recovered by the receiving end and the received optical power in two modes of electrical dispersion pre-compensation and electrical dispersion post-compensation, and it can be found that the same effect of the electrical dispersion pre-compensation scheme can be achieved by performing electrical dispersion post-compensation on the two double-sideband signals in the system, which indicates that no obvious power fading phenomenon occurs when the double-sideband signals are transmitted through the optical fiber. That is to say, the invention can overcome the problem of power fading induced by optical fiber dispersion of double-sideband signals in the traditional radio over fiber communication system.

Therefore, in the radio over fiber communication system supporting dual-signal modulation and demodulation provided by the embodiment of the present invention, because the optical transceiver can implement the steps of the above-mentioned dual-signal modulation method for the radio over fiber communication system, the constraint between the radio frequency driving signal of the dual-drive MZM and the dc bias of the modulator is released while two different dual-signal linear electro-optical modulations of the dual-sideband or the dual-sideband are implemented, the high-efficiency electrical dispersion compensation of the dual-signal is supported, and the power fading problem of the conventional dual-sideband signal is overcome; in addition, the bandwidth of a transceiver can be fully utilized through double-sideband or double-sideband modulation, so that the cost of system devices is reduced, and the communication capacity of the system is improved; in addition, no matter the modulation mode of the double-generation double-sideband or the double-generation single-sideband, the demodulation of the double signals is not influenced by SSBI at all, and only a very small protection interval is needed to be set at the cost; therefore, the radio over fiber communication system supporting dual-signal modulation and demodulation provided by the invention can improve the communication rate and the spectrum efficiency of the existing radio over fiber communication system under the condition of lower system complexity and deployment cost, and is beneficial to realizing a 6G-oriented high-capacity and high-performance photonic millimeter wave/terahertz communication system.

Based on the same inventive concept, an embodiment of the present invention provides an electronic device, and referring to fig. 16, the electronic device specifically includes the following contents: a processor 1601, a communication interface 1603, a memory 1602, and a communication bus 1604;

the processor 1601, the communication interface 1603 and the memory 1602 complete communication with each other through the communication bus 1604; the communication interface 1603 is used for realizing information transmission among related equipment such as various modeling software, an intelligent manufacturing equipment module library and the like; the processor 1601 is used for calling the computer program in the memory 1602, and when the processor executes the computer program, the method provided by the above method embodiments is implemented, for example, when the processor executes the computer program, the following steps are implemented: performing signal recombination based on the first real-valued signal and the second real-valued signal to obtain a recombined signal; the recombination signal is a double-generation double-sideband signal or a double-generation single-sideband signal; performing electrical dispersion pre-compensation on the recombined signal; performing polar coordinate signal conversion on the recombined signal subjected to electric dispersion precompensation to enable the twinning double sideband signal or the twinning single sideband signal to be represented in a polar coordinate mode; constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of a modulator during electro-optical modulation; electro-optical modulation is carried out based on two radio frequency input signals; and/or; carrying out carrier extraction based on the sampling digital signal; the sampling digital signal comprises a carrier wave and a double-generation double-sideband signal or a double-generation single-sideband signal; performing signal recovery based on the extracted carrier; the signal is restored to be the multiplication of the extracted carrier wave and the component of the sampling digital signal, and then a high-frequency item is filtered to obtain a first path of restored signal and a second path of restored signal; performing signal recombination on the recovered first path of signal and the second path of signal to obtain corresponding recombined signals; performing electric dispersion post-compensation on the recombined signal; performing signal decomposition on the recombined signal compensated after the electric dispersion to obtain a first real-valued signal and a second real-valued signal; signal demodulation is performed based on the first and second real-valued signals.

Based on the same inventive concept, a non-transitory computer-readable storage medium is further provided, on which a computer program is stored, which, when being executed by a processor, is implemented to perform the methods provided by the above method embodiments, for example, performing signal recombination based on a first real-valued signal and a second real-valued signal to obtain a recombined signal; the recombination signal is a double-generation double-sideband signal or a double-generation single-sideband signal; performing electrical dispersion pre-compensation on the recombined signal; performing polar coordinate signal conversion on the recombined signal subjected to electric dispersion precompensation to enable the twinning double sideband signal or the twinning single sideband signal to be represented in a polar coordinate mode; constructing two driving signals for digital-to-analog conversion based on a polar coordinate mode representation result, and using the two driving signals as two radio frequency input signals of a modulator during electro-optical modulation; electro-optical modulation is carried out based on two radio frequency input signals; and/or; carrying out carrier extraction based on the sampling digital signal; the sampling digital signal comprises a carrier wave and a double-generation double-sideband signal or a double-generation single-sideband signal; performing signal recovery based on the extracted carrier; the signal is restored to be the multiplication of the extracted carrier wave and the component of the sampling digital signal, and then a high-frequency item is filtered to obtain a first path of restored signal and a second path of restored signal; performing signal recombination on the recovered first path of signal and the second path of signal to obtain corresponding recombined signals; performing electric dispersion post-compensation on the recombined signal; performing signal decomposition on the recombined signal compensated after the electric dispersion to obtain a first real-valued signal and a second real-valued signal; signal demodulation is performed based on the first and second real-valued signals.

The above-described system embodiments are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods of the various embodiments or some parts of the embodiments.

In addition, in the present invention, terms such as "first" and "second" 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 at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Moreover, in the present invention, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Furthermore, in the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A dual signal modulation method for a radio over fiber communication system, comprising:

performing electrical dispersion pre-compensation on the recombined signal;

2. The method of claim 1, wherein the signal recombination based on the first real-valued signal and the second real-valued signal to obtain a recombined signal comprises:

s(t)=A+s ₁(t)-js ₂(t)

3. The method of claim 1, wherein two driving signals are constructed based on the polar coordinate representation for digital-to-analog conversion and used as two rf input signals of a modulator during the electro-optical modulation, comprising:

wherein the content of the first and second substances,

the inverse cosine function is represented as a function of,

representing the maximum amplitude of the signal, t representing time,

which is representative of the first drive signal and,

which is representative of the second drive signal, is,

4. A dual signal demodulation method for a radio over fiber communication system, comprising:

performing electric dispersion post-compensation on the recombined signal;

5. The method of claim 4, further comprising:

reserving a preset guard interval between a carrier and a signal;

6. A dual signal modulation apparatus for a wireless over fiber communication system, comprising:

7. A dual signal demodulation apparatus for a wireless over fiber communication system, comprising:

8. A wireless communication over optical system supporting dual signal modulation and demodulation, comprising: optical transceivers and wireless transceivers;

a step of implementing the dual signal modulation method for an over-the-optical wireless communication system according to any one of claims 1 to 3 in the optical transceiver; and the combination of (a) and (b),

9. A wireless communication over optical system supporting dual signal modulation and demodulation, comprising: optical transceivers and wireless transceivers;

a step of implementing in said radio transceiver the method of dual signal demodulation towards a wireless over optical carrier communication system according to claim 4 or 5; and the combination of (a) and (b),

10. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the program implements the steps of the method for dual signal modulation for a wireless communication over optical system according to any of claims 1 to 3; or, the computer program realizes the steps of the method for dual signal demodulation for a wireless communication over optical system according to claim 4 or 5 when executed by a processor.

11. An electronic device comprising a memory, a first processor, a second processor, a first computer program stored on the memory and executable on the first processor, and a second computer program stored on the memory and executable on the second processor, the first processor implementing the steps of the dual signal modulation method for a wireless communication over optical system according to any one of claims 1 to 3 when executing the first computer program; the second processor, when executing the second computer program, implements the steps of the method for dual signal demodulation for a wireless communication over optical carrier system according to claim 4 or 5.

12. A non-transitory computer readable storage medium, having stored thereon a computer program, wherein the computer program, when executed by a processor, implements the steps of the dual signal modulation method for a wireless over optical system according to any of claims 1 to 3; or, the computer program realizes the steps of the method for dual signal demodulation for a wireless communication over optical system according to claim 4 or 5 when executed by a processor.

13. A non-transitory computer readable storage medium, having stored thereon a first computer program and a second computer program, the first computer program, when executed by a first processor, implementing the steps of the dual signal modulation method for a wireless over optical communication system according to any one of claims 1 to 3; the second computer program, when being executed by the second processor, realizes the steps of the method for dual signal demodulation for a wireless communication over optical carrier system according to claim 4 or 5.