CN112910818B - Iterative diversity combining and demodulating method and device and terminal equipment - Google Patents
Iterative diversity combining and demodulating method and device and terminal equipment Download PDFInfo
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Abstract
The invention is suitable for the field of optical communication, and provides an iterative diversity combining demodulation method, a device and a terminal device, wherein the method comprises the following steps: acquiring optical signals and calculating odd and even subcarrier signals; further calculating a first diversity combining signal and performing fast Fourier transform to obtain an initial frequency domain signal; carrying out maximum likelihood detection to obtain a first frequency domain signal; converting the first frequency domain signal into a first time domain signal, and acquiring the polarity of the first time domain signal; and calculating a target diversity combined signal according to the polarities of the odd and even subcarrier signals and the first time domain signal, updating the first diversity combined signal by adopting the target diversity combined signal, repeatedly calculating the target diversity combined signal and demodulating the finally obtained target diversity combined signal. The method provided by the invention can reduce signal noise and improve the gain of optical signal transmission by utilizing the maximum likelihood detection and the iterative process, thereby improving the receiving performance of a receiver in the optical communication process.
Description
Technical Field
The invention belongs to the technical field of optical communication, and particularly relates to an iterative diversity combining demodulation method, an iterative diversity combining demodulation device and terminal equipment.
Background
The visible light communication has the characteristics of low cost, high signal-to-noise ratio and spectrum authorization-free, has a wide development prospect, and is a research hotspot in recent years. Because the form of the transmitted signal in the visible light communication process is positive and real, the signal can be received and demodulated by adopting an asymmetric cut-off optical orthogonal frequency division multiplexing (ACO-OFDM) technology.
However, the current ACO-OFDM receiver has large noise interference and small signal gain, which is usually only 1.5dB to 2dB, and has poor performance.
Disclosure of Invention
In view of this, embodiments of the present invention provide an iterative diversity combining and demodulating method, an iterative diversity combining and demodulating device, and a terminal device, so as to solve the problem in the prior art that an asymmetric ablation optical orthogonal frequency division multiplexing receiver has large noise and small gain.
A first aspect of an embodiment of the present invention provides an iterative diversity combining and demodulating method, which is applied to an asymmetric ablation optical orthogonal frequency division multiplexing receiver, and the method includes:
the method comprises the following steps: acquiring an optical signal, converting the optical signal into a digital signal, and calculating an odd subcarrier signal and an even subcarrier signal according to the digital signal;
step two: calculating a first diversity combined signal according to the odd subcarrier signal and the even subcarrier signal, and performing fast Fourier transform on the first diversity combined signal to obtain an initial frequency domain signal;
step three: carrying out maximum likelihood detection on the initial frequency domain signal to obtain a first frequency domain signal;
step four: performing inverse fast Fourier transform on the first frequency domain signal to obtain a first time domain signal, and acquiring the polarity of the first time domain signal;
step five: calculating a target diversity combined signal according to the odd subcarrier signal, the even subcarrier signal and the polarity of the first time domain signal, updating the first diversity combined signal by adopting the target diversity combined signal, and repeatedly executing the steps two to five of preset times; and demodulating the finally obtained target diversity combined signal.
A second aspect of the embodiments of the present invention provides an iterative diversity combining demodulation apparatus, including:
the system comprises a signal acquisition module, a signal processing module and a signal processing module, wherein the signal acquisition module is used for acquiring an optical signal, converting the optical signal into a digital signal and calculating an odd subcarrier signal and an even subcarrier signal according to the digital signal;
and an initial frequency domain signal calculation module. The system comprises a first sub-set and a second sub-set, wherein the first sub-set and the second sub-set are used for calculating a first sub-set combined signal according to the odd sub-carrier signals and the even sub-carrier signals and carrying out fast Fourier transform on the first sub-set combined signal to obtain an initial frequency domain signal;
the maximum likelihood detection module is used for carrying out maximum likelihood detection on the initial frequency domain signal to obtain a first frequency domain signal;
the first time domain signal calculation module is used for performing inverse fast Fourier transform on the first frequency domain signal to obtain a first time domain signal and acquiring the polarity of the first time domain signal;
a target diversity-combining signal calculation module, configured to calculate a target diversity-combining signal according to the polarities of the odd subcarrier signal, the even subcarrier signal, and the first time domain signal, update the first diversity-combining signal with the target diversity-combining signal, and repeatedly perform steps two to five of preset times; and demodulating the finally obtained target diversity combined signal.
A third aspect of the embodiments of the present invention provides a terminal 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 method when executing the computer program.
A fourth aspect of embodiments of the present invention provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the method as described above.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: the embodiment of the invention provides an iterative diversity combining and demodulating method, which comprises the following steps: the method comprises the following steps: acquiring an optical signal, converting the optical signal into a digital signal, and calculating an odd subcarrier signal and an even subcarrier signal according to the digital signal; step two: calculating a first diversity combined signal according to the odd subcarrier signal and the even subcarrier signal, and performing fast Fourier transform on the first diversity combined signal to obtain an initial frequency domain signal; step three: carrying out maximum likelihood detection on the initial frequency domain signal to obtain a first frequency domain signal; step four: performing inverse fast Fourier transform on the first frequency domain signal to obtain a first time domain signal, and acquiring the polarity of the first time domain signal; step five: calculating a target diversity combined signal according to the odd subcarrier signal, the even subcarrier signal and the polarity of the first time domain signal, updating the first diversity combined signal by adopting the target diversity combined signal, and repeatedly executing the steps two to five of preset times; and demodulating the finally obtained target diversity combined signal. The iterative diversity combining and demodulating method provided by the embodiment of the invention can reduce signal noise and improve the gain of optical signal transmission by utilizing maximum likelihood detection and an iterative process, thereby improving the receiving performance of a receiver in the optical communication process.
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In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic flow chart of an implementation of an iterative diversity combining and demodulating method according to an embodiment of the present invention;
fig. 2 is a schematic diagram illustrating an effect of an iterative diversity combining and demodulating method according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an iterative diversity combining and demodulating apparatus according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a terminal device according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular system structures, 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.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
The iterative diversity combining and demodulating method provided by the embodiment of the invention can be applied to an ACO-OFDE visible light communication system and an ACO-OFDM optical fiber communication system.
Fig. 1 shows a schematic flow chart of an implementation of an iterative diversity combining and demodulating method provided by an embodiment of the present invention, and referring to fig. 1, an embodiment of the present invention provides an iterative diversity combining and demodulating method applied to an asymmetric-cut optical orthogonal frequency division multiplexing receiver, where the method includes:
s101: acquiring an optical signal, converting the optical signal into a digital signal, and calculating an odd subcarrier signal and an even subcarrier signal according to the digital signal;
in one embodiment of the present invention, the calculating the odd subcarrier signal and the even subcarrier signal from the digital signal in S101 includes:
carrying out serial-to-parallel conversion on the digital signal, and carrying out cyclic prefix removal processing on the digital signal after the serial-to-parallel conversion to obtain an initial signal;
carrying out symmetrical recovery operation on the initial signal according to an odd subcarrier signal calculation formula and an even subcarrier signal calculation formula to obtain an odd subcarrier signal and an even subcarrier signal;
the odd subcarrier signal calculation formula is as follows:
the even number subcarrier signal calculation formula is as follows:
wherein, y odd,n For the nth odd subcarrier signal, y even,n For the nth even subcarrier signal, y ,n Is the nth initial signal, and N is the sampling number of the initial signal.
Specifically, the optical signal is obtained through the photodiode, and the analog signal is converted into the digital signal through the digital-to-analog converter after the optical signal is converted into the electrical signal.
Optionally, after converting the optical signal into the electrical signal, the method further includes amplifying the electrical signal by a power amplifier.
In this embodiment, the digital signal is subjected to serial-to-parallel conversion and cyclic prefix removal processing by the digital signal processing chip.
S102: calculating a first diversity combined signal according to the odd subcarrier signal and the even subcarrier signal, and performing fast Fourier transform on the first diversity combined signal to obtain an initial frequency domain signal;
in one embodiment of the present invention, the calculating the first diversity combined signal according to the odd subcarrier signal and the even subcarrier signal in S102 includes:
acquiring the polarity of the odd subcarrier signal;
calculating a first combined set signal according to the odd subcarrier signal, the even subcarrier signal, the polarity of the odd subcarrier signal and a first combined set signal calculation formula;
the first subset union signal calculation formula is as follows:
wherein the content of the first and second substances,
is the nth first diversity combined signal, alpha is the combined coefficient, y odd,n For the nth odd subcarrier signal, y even,n For the nth even subcarrier signal, syn (y) odd,n ) The polarity of the nth odd subcarrier signal.
In this embodiment, in S102, performing fast fourier transform on the first combined set signal to obtain an initial frequency domain signal, including:
and substituting the first diversity combining signals into a fast Fourier transform formula to calculate initial frequency domain signals.
The fast fourier transform formula is:
wherein the content of the first and second substances,
is the k initialFrequency domain signal, N is the number of samples of the initial signal,
is the nth first subset sum signal.
In this embodiment, since orthogonality is maintained between subcarriers in the ofdm system, that is, noise on odd subcarrier signals and noise on even subcarrier signals are independent of each other, there is an error in the process of shaping even subcarriers by the polarity of odd subcarrier signals.
In order to reduce errors in the signal shaping process, the embodiment of the invention adopts an iterative mode to calculate the target diversity combined signal, thereby reducing the noise interference of the final target diversity combined signal and improving the signal gain.
S103: carrying out maximum likelihood detection on the initial frequency domain signal to obtain a first frequency domain signal;
in one embodiment of the present invention, S103 includes:
calculating the first frequency domain signal according to the initial frequency domain signal and a maximum likelihood detection formula;
the maximum likelihood detection formula is:
wherein the content of the first and second substances,
for the k-th first frequency-domain signal,
for the kth initial frequency-domain signal, S ACO Is a modulation channel constellation point set, and X is an element in the modulation signal constellation point set.
S104: performing inverse fast Fourier transform on the first frequency domain signal to obtain a first time domain signal, and acquiring the polarity of the first time domain signal;
specifically, substituting the first frequency domain signal into an inverse fast fourier transform formula to calculate a first time domain signal; the inverse fast fourier transform formula is:
wherein
Is the nth first time domain signal, N is the sampling number of the initial signal,
is the kth first frequency domain signal.
In this embodiment, the step of maximum likelihood detection may make the first frequency domain signal closer to the original transmission signal, and the noise of the first time domain signal obtained through maximum likelihood detection and fast fourier transform is greatly reduced, so that the noise interference of the final target diversity combining signal can be reduced.
S105: calculating a target diversity combined signal according to the odd subcarrier signal, the even subcarrier signal and the polarity of the first time domain signal, updating the first diversity combined signal by using the target diversity combined signal, and repeatedly executing S102 to S105 for a preset number of times; and demodulating the finally obtained target diversity combined signal.
The iterative diversity combining demodulation method provided by the embodiment of the invention can reduce signal noise and improve the gain of optical signal transmission by utilizing maximum likelihood detection and an iterative process, thereby improving the receiving performance of a receiver in the optical communication process.
In one embodiment of the present invention, the step S105 of calculating a target diversity-combined signal according to the polarities of the odd subcarrier signal, the even subcarrier signal and the first time domain signal includes:
bringing the polarities of the odd subcarrier signal, the even subcarrier signal and the first time domain signal into a target diversity combined signal calculation formula to obtain a target diversity combined signal;
the target diversity combining signal calculation formula is as follows:
wherein the content of the first and second substances,
diversity-combining signals for the target, alpha being the combining coefficient, y odd For odd subcarrier signals, y even For the even number of sub-carrier signals,
the polarity of the first time domain signal.
In one embodiment of the invention, the asymmetric cut-off optical orthogonal frequency division multiplexing receiver comprises a 4QAM asymmetric cut-off optical orthogonal frequency division multiplexing receiver; the preset times are 1.
In this embodiment, when the preset number of times is 1, two target diversity combining signals are actually calculated, that is, the number of iterations is 2.
In one embodiment of the present invention, the asymmetric cut-off optical orthogonal frequency division multiplexing receiver includes a 16QAM asymmetric cut-off optical orthogonal frequency division multiplexing receiver, a 64QAM asymmetric cut-off optical orthogonal frequency division multiplexing receiver, and a 256QAM asymmetric cut-off orthogonal optical frequency division multiplexing receiver; the preset times are 0 times.
In this embodiment, when the preset number of times is 0 times, 1 time of target diversity combining signals is actually calculated, that is, when the asymmetric ablation optical orthogonal frequency division multiplexing receiver is a 16QAM asymmetric ablation optical orthogonal frequency division multiplexing receiver, a 64QAM asymmetric ablation optical orthogonal frequency division multiplexing receiver, or a 128QAM asymmetric ablation optical orthogonal frequency division multiplexing receiver, iteration is performed for 1 time.
Fig. 2 shows the effect of the iterative diversity combining and demodulating method provided by the embodiment of the present invention, in fig. 2, 209 is a performance curve of a received signal when no iteration is performed in the prior art, 201 and 208 are performance curves of the received signal corresponding to the iterative diversity combining and demodulating method provided by the embodiment of the present invention, referring to fig. 2, the iterative diversity combining and demodulating method provided by the embodiment of the present invention can ensure a 3dB gain of the received signal when the signal-to-noise ratio is small, and can improve the quality of the received signal. Specifically, 201 is 4QAM in the embodiment of the present invention, a performance curve of a received signal corresponding to 2 iterations, 202 is 4QAM, and a performance curve of a received signal corresponding to 1 iteration, and as can be seen from 201 and 202, the iterative diversity combining demodulation method provided in the embodiment of the present invention can enable a signal modulated by 4QAM to achieve a gain of 3dB when the signal-to-noise ratio is less than 10. On the other hand, as can be seen from fig. 2, in 4QAM modulation, the signal obtained by 2 iterations is better than the signal obtained by 1 iteration. 203 and 204 are performance curves of the received signal corresponding to 16QAM, 2 iterations, and 1 iteration in the embodiment of the present invention, and it can be known from 203 and 204 that the iterative diversity combining demodulation method provided in the embodiment of the present invention can make the signal modulated by 16QAM achieve a gain of 3dB when the signal-to-noise ratio is less than 15. 205 and 206 are performance curves of the received signal corresponding to 2 iterations and 1 iteration respectively when performing 64QAM modulation according to this embodiment of the present invention, and 207 and 208 are performance curves of the received signal corresponding to 2 iterations and 1 iteration respectively when performing 256QAM modulation according to this embodiment of the present invention. As can be seen from the curve 203-.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
Referring to fig. 3, an iterative diversity combining and demodulating apparatus 10 according to an embodiment of the present invention includes:
a signal obtaining module 110, configured to obtain an optical signal, convert the optical signal into a digital signal, and calculate an odd subcarrier signal and an even subcarrier signal according to the digital signal;
an initial frequency domain signal calculation module 120, configured to calculate a first subset union signal according to the odd subcarrier signal and the even subcarrier signal, and perform fast fourier transform on the first subset union signal to obtain an initial frequency domain signal;
a maximum likelihood detection module 130, configured to perform maximum likelihood detection on the initial frequency domain signal to obtain a first frequency domain signal;
a first time domain signal calculating module 140, configured to perform inverse fast fourier transform on the first frequency domain signal to obtain a first time domain signal, and obtain a polarity of the first time domain signal;
a target diversity-combined signal calculating module 150, configured to calculate a target diversity-combined signal according to the polarities of the odd subcarrier signal, the even subcarrier signal, and the first time domain signal, update the first diversity-combined signal with the target diversity-combined signal, and repeatedly perform steps two to five of preset times; and demodulating the finally obtained target diversity combined signal.
The iteration diversity combining and demodulating device provided by the embodiment of the invention can reduce signal noise and improve the gain of optical signal transmission by utilizing maximum likelihood detection and an iteration process, thereby improving the receiving performance of a receiver in the optical communication process.
In an embodiment of the present invention, the signal obtaining module 110 is specifically configured to:
carrying out serial-to-parallel conversion on the digital signal, and carrying out cyclic prefix removal processing on the digital signal after the serial-to-parallel conversion to obtain an initial signal;
carrying out symmetrical recovery operation on the initial signal according to an odd subcarrier signal calculation formula and an even subcarrier signal calculation formula to obtain an odd subcarrier signal and an even subcarrier signal;
the odd subcarrier signal calculation formula is as follows:
the even number subcarrier signal calculation formula is as follows:
wherein, y odd,n For the nth odd subcarrier signal, y even,n For the nth even subcarrier signal, y ,n Is the nth initial signal, and N is the sampling number of the initial signal.
In an embodiment of the present invention, the initial frequency domain signal calculating module 120 is specifically configured to:
acquiring the polarity of the odd subcarrier signal;
calculating a first combined set signal according to the odd subcarrier signal, the even subcarrier signal, the polarity of the odd subcarrier signal and a first combined set signal calculation formula;
the first subset union signal calculation formula is as follows:
wherein the content of the first and second substances,
is the nth first diversity combined signal, alpha is the combined coefficient, y odd,n For the nth odd subcarrier signal, y even,n For the nth even subcarrier signal, syn (y) odd,n ) The polarity of the nth odd subcarrier signal.
In an embodiment of the present invention, the maximum likelihood detection module 130 is specifically configured to:
calculating the first frequency domain signal according to the initial frequency domain signal and a maximum likelihood detection formula;
the maximum likelihood detection formula is:
wherein the content of the first and second substances,
for the k-th first frequency-domain signal,
for the kth initial frequency-domain signal, S ACO Is a modulation channel constellation point set, and X is an element in the modulation signal constellation point set.
In an embodiment of the present invention, the target diversity-combined signal calculating module 150 is specifically configured to:
bringing the polarities of the odd subcarrier signal, the even subcarrier signal and the first time domain signal into a target diversity combined signal calculation formula to obtain a target diversity combined signal;
the target diversity combining signal calculation formula is as follows:
wherein the content of the first and second substances,
diversity-combining signals for the targets, alpha being the combining coefficient, y odd For odd subcarrier signals, y even Is a signal of an even number of sub-carriers,
the polarity of the first time domain signal.
In one embodiment of the invention, the asymmetric cut-out optical orthogonal frequency division multiplexing receiver comprises a 4QAM asymmetric cut-out optical orthogonal frequency division multiplexing receiver; the preset times are 1.
In one embodiment of the present invention, the asymmetric cut-off optical orthogonal frequency division multiplexing receiver includes a 16QAM asymmetric cut-off optical orthogonal frequency division multiplexing receiver and a 64QAM asymmetric cut-off optical orthogonal frequency division multiplexing receiver; the preset times are 0 times.
Fig. 4 is a schematic diagram of a terminal device according to an embodiment of the present invention. As shown in fig. 4, the terminal device 4 of this embodiment includes: a processor 40, a memory 41 and a computer program 42, such as an iterative diversity combining demodulation method program, stored in said memory 41 and executable on said processor 40. The processor 40, when executing the computer program 42, implements the steps in each of the embodiments of the iterative diversity combining and demodulating method described above, such as S101 to S105 shown in fig. 1. Alternatively, the processor 40, when executing the computer program 42, implements the functions of the modules/units in the above-mentioned device embodiments, such as the functions of the modules 110 to 150 shown in fig. 3.
Illustratively, the computer program 42 may be partitioned into one or more modules/units that are stored in the memory 41 and executed by the processor 40 to implement the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing certain functions, which are used to describe the execution of the computer program 42 in the terminal device 4. For example, the computer program 42 may be divided into a signal acquisition module, an initial frequency domain signal calculation module, a maximum likelihood detection module, a first time domain signal calculation module, and a target diversity combined signal calculation module (module in a virtual device).
The terminal device 4 may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal device may include, but is not limited to, a processor 40, a memory 41. Those skilled in the art will appreciate that fig. 4 is merely an example of a terminal device 4 and does not constitute a limitation of terminal device 4 and may include more or fewer components than shown, or some components may be combined, or different components, e.g., the terminal device may also include input-output devices, network access devices, buses, etc.
The Processor 40 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 memory 41 may be an internal storage unit of the terminal device 4, such as a hard disk or a memory of the terminal device 4. The memory 41 may also be an external storage device of the terminal device 4, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like, which are provided on the terminal device 4. Further, the memory 41 may also include both an internal storage unit and an external storage device of the terminal device 4. The memory 41 is used for storing the computer program and other programs and data required by the terminal device. The memory 41 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and 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 units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments described above may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should 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; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (9)
1. An iterative diversity combining demodulation method applied to an asymmetric ablation optical orthogonal frequency division multiplexing receiver, the method comprising:
the method comprises the following steps: acquiring an optical signal, converting the optical signal into a digital signal, and calculating an odd subcarrier signal and an even subcarrier signal according to the digital signal;
step two: calculating a first diversity combined signal according to the odd subcarrier signal and the even subcarrier signal, and performing fast Fourier transform on the first diversity combined signal to obtain an initial frequency domain signal;
step three: carrying out maximum likelihood detection on the initial frequency domain signal to obtain a first frequency domain signal;
step four: performing inverse fast Fourier transform on the first frequency domain signal to obtain a first time domain signal, and acquiring the polarity of the first time domain signal;
step five: calculating a target diversity combined signal according to the odd subcarrier signal, the even subcarrier signal and the polarity of the first time domain signal, updating the first diversity combined signal by adopting the target diversity combined signal, and repeatedly executing the steps two to five of preset times; demodulating the finally obtained target diversity combined signal;
the calculating odd subcarrier signals and even subcarrier signals according to the digital signals comprises:
carrying out serial-to-parallel conversion on the digital signal, and carrying out cyclic prefix removal processing on the digital signal after the serial-to-parallel conversion to obtain an initial signal;
carrying out symmetrical recovery operation on the initial signal according to an odd subcarrier signal calculation formula and an even subcarrier signal calculation formula to obtain an odd subcarrier signal and an even subcarrier signal;
the odd subcarrier signal calculation formula is as follows:
the even number subcarrier signal calculation formula is as follows:
wherein, y odd,n For the nth odd subcarrier signal, y even,n For the nth even subcarrier signal, y ,n Is the nth initial signal, and N is the sampling number of the initial signal.
2. The iterative diversity combining demodulation method of claim 1 wherein said computing a first diversity combined signal from said odd subcarrier signal and said even subcarrier signal comprises:
acquiring the polarity of the odd subcarrier signal;
calculating a first combined set signal according to the odd subcarrier signal, the even subcarrier signal, the polarity of the odd subcarrier signal and a first combined set signal calculation formula;
the first subset union signal calculation formula is as follows:
wherein the content of the first and second substances,
is the n-th first diversity combined signal, alpha is the combining coefficient, y odd,n For the nth odd subcarrier signal, y even,n For the nth even subcarrier signal, syn (y) odd,n ) The polarity of the nth odd subcarrier signal.
3. The iterative diversity combining demodulation method of claim 1, wherein said performing maximum likelihood detection on said initial frequency-domain signal to obtain a first frequency-domain signal comprises:
calculating the first frequency domain signal according to the initial frequency domain signal and a maximum likelihood detection formula;
the maximum likelihood detection formula is:
wherein the content of the first and second substances,
for the k-th first frequency-domain signal,
for the kth initial frequency domain signal, S ACO Is a modulation channel constellation point set, and X is an element in the modulation signal constellation point set.
4. The iterative diversity combining demodulation method of claim 1 wherein said calculating a target diversity combined signal based on the polarities of said odd subcarrier signal, said even subcarrier signal and said first time domain signal comprises:
bringing the polarities of the odd subcarrier signal, the even subcarrier signal and the first time domain signal into a target diversity combined signal calculation formula to obtain a target diversity combined signal;
the target diversity combining signal calculation formula is as follows:
wherein the content of the first and second substances,
diversity-combining signals for the target, alpha being the combining coefficient, y odd For odd subcarrier signals, y even For the even number of sub-carrier signals,
the polarity of the first time domain signal.
5. The iterative diversity combining demodulation method of any of claims 1-4 wherein said asymmetrically cut optical OFDM receiver comprises a 4QAM asymmetrically cut optical OFDM receiver; the preset times are 1.
6. The iterative diversity combining demodulation method of any of claims 1-4, wherein the asymmetric cut-out optical orthogonal frequency division multiplexing receiver comprises a 16QAM asymmetric cut-out optical orthogonal frequency division multiplexing receiver, a 64QAM asymmetric cut-out optical orthogonal frequency division multiplexing receiver, and a 256QAM asymmetric cut-out optical orthogonal frequency division multiplexing receiver; the preset times are 0 times.
7. An iterative diversity combining demodulation apparatus, comprising:
the system comprises a signal acquisition module, a signal processing module and a signal processing module, wherein the signal acquisition module is used for acquiring an optical signal, converting the optical signal into a digital signal and calculating an odd subcarrier signal and an even subcarrier signal according to the digital signal;
an initial frequency domain signal calculation module, configured to calculate a first subset union signal according to the odd subcarrier signal and the even subcarrier signal, and perform fast fourier transform on the first subset union signal to obtain an initial frequency domain signal;
the maximum likelihood detection module is used for carrying out maximum likelihood detection on the initial frequency domain signal to obtain a first frequency domain signal;
the first time domain signal calculation module is used for performing inverse fast Fourier transform on the first frequency domain signal to obtain a first time domain signal and acquiring the polarity of the first time domain signal;
a target diversity-combining signal calculation module, configured to calculate a target diversity-combining signal according to the polarities of the odd subcarrier signal, the even subcarrier signal, and the first time domain signal, update the first diversity-combining signal with the target diversity-combining signal, and repeatedly perform steps two to five of preset times; demodulating the finally obtained target diversity combined signal;
the signal obtaining module is configured to calculate odd subcarrier signals and even subcarrier signals according to the digital signal, and includes:
carrying out serial-to-parallel conversion on the digital signal, and carrying out cyclic prefix removal processing on the digital signal after the serial-to-parallel conversion to obtain an initial signal;
carrying out symmetrical recovery operation on the initial signal according to an odd subcarrier signal calculation formula and an even subcarrier signal calculation formula to obtain an odd subcarrier signal and an even subcarrier signal;
the odd subcarrier signal calculation formula is as follows:
the even number subcarrier signal calculation formula is as follows:
wherein, y odd,n For the nth odd subcarrier signal, y even,n For the nth even subcarrier signal, y ,n Is the nth initial signal, and N is the sampling number of the initial signal.
8. A terminal device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of claims 1 to 6 when executing the computer program.
9. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of a method according to any one of claims 1 to 6.
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