CN109039468A - A kind of information modulation method, information demodulation method, device and communication system - Google Patents
A kind of information modulation method, information demodulation method, device and communication system Download PDFInfo
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Abstract
The embodiment of the invention provides a kind of information modulation method, information demodulation method, device and electronic equipments, and wherein information modulation method, is applied to transmitting terminal, and method includes: to be encoded by pre-arranged code mode to initial information；Initial information after coding is mapped in spatial light modulator；By spatial light modulator to the initial information after coding, orbital angular momentum OAM modulation is carried out, obtains carrying the target information that the light beam of OAM Information determines, sends target information to receiving end.Wherein information demodulation method, is applied to receiving end, and method includes: to obtain the target information of transmitting terminal；Orbital angular momentum OAM model is demodulated by convolutional neural networks CNN trained in advance, determines the corresponding OAM demodulated sequence of target information；OAM demodulated sequence is decoded, the initial information that target information corresponds to transmitting terminal is obtained.The present invention, which realizes, improves noise robustness and demodulation efficiency.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to an information modulation method, an information demodulation device, and a communication system.
Background
The free space optical communication combines the advantages of optical fiber communication and microwave communication, has the advantages of large communication capacity and high-speed transmission, and does not need laying optical fibers, thereby improving the utilization efficiency of frequency spectrum and meeting the increasing information demand of people.
In free space optical communication, a transmitting end maps communication data into a spatial light modulator through a mapping relation, OAM (Orbital Angular momentum) modulation is carried out on the communication data through the spatial light modulator to obtain target information, and the target information is transmitted through an atmospheric turbulence channel of spatial light. And the receiving end carries out OAM demodulation on the target information through the optical device to obtain the communication data of the transmitting end.
The inventor finds that the existing transmission process of target information through an optical device is greatly interfered by channel noise, and the demodulation process is low in efficiency. Therefore, how to improve the anti-noise performance and the efficiency of information demodulation is still an urgent problem to be solved.
Disclosure of Invention
The embodiment of the invention aims to provide an information modulation method, an information demodulation device and a communication system, so as to improve the anti-noise performance and the demodulation efficiency. The specific technical scheme is as follows:
in a first aspect, an embodiment of the present invention discloses an information modulation method, which is applied to a transmitting end, and the method includes:
encoding the initial information by a preset encoding mode;
mapping the encoded initial information into a spatial light modulator;
and performing Orbital Angular Momentum (OAM) modulation on the encoded initial information through the spatial light modulator to obtain target information determined by the light beam carrying the OAM information, and sending the light beam information carrying the OAM information to a receiving end.
Optionally, the encoding the initial information in a preset encoding manner includes:
encoding the initial information by a turbo coding mode;
the performing, by the spatial light modulator, orbital angular momentum, OAM, modulation on the encoded initial information to obtain light beam information carrying OAM information includes:
mapping the encoded initial information through the determined gray code mapping relation, so that an encoding sequence corresponding to the encoded initial information is divided into a plurality of data groups, and each data group is mapped to each corresponding OAM mode sequence;
modulating, in the spatial light modulator, a continuous Laguerre-Gaussian LG beam to LG beam information carrying the OAM mode sequences.
In a second aspect, an embodiment of the present invention further discloses an information demodulation method, which is applied to a receiving end, and the method includes:
acquiring target information of a transmitting terminal;
determining an OAM demodulation sequence corresponding to the target information through a pre-trained convolutional neural network CNN demodulation orbital angular momentum OAM model; the CNN demodulation OAM model is determined according to a plurality of OAM modulation information training;
and decoding the OAM demodulation sequence to obtain the initial information of the target information corresponding to the transmitting terminal.
Optionally, the target information is a light intensity map of a laguerre-gaussian LG light beam carrying OAM;
the acquiring target information of the transmitting terminal includes:
and receiving a light intensity diagram of the LG light beam sent by the transmitting terminal through a Charge Coupled Device (CCD) camera.
Optionally, the determining, by using a pre-trained convolutional neural network CNN to demodulate an orbital angular momentum OAM model, an OAM demodulation sequence corresponding to the target information includes:
and inputting the light intensity graph into a pre-trained CNN demodulation OAM model to obtain an OAM demodulation sequence corresponding to the target information.
Optionally, the step of constructing the CNN demodulation OAM model includes:
and training a plurality of pieces of OAM modulation information correspondingly formed through a plurality of OAM modulation modes under a tenserflow frame to obtain a CNN demodulation OAM model.
Optionally, the decoding the OAM demodulation sequence to obtain the initial information that the target information corresponds to the transmitting end includes:
the OAM demodulation sequence is subjected to inverse mapping through a Gray code mapping mode to obtain a demodulation mapping sequence;
and decoding the demodulation mapping sequence by a turbo decoding mode to obtain the initial information of the target information corresponding to the transmitting terminal.
In a third aspect, an embodiment of the present invention discloses an information modulation apparatus, applied to a transmitting end, where the apparatus includes:
the initial information coding module is used for coding the initial information in a preset coding mode;
the initial information mapping module is used for mapping the encoded initial information into the spatial light modulator;
and the initial information modulation module is used for carrying out Orbital Angular Momentum (OAM) modulation on the encoded initial information through the spatial light modulator to obtain target information determined by the light beam carrying the OAM information, and sending the target information to a receiving end.
Optionally, the initial information encoding module is specifically configured to encode the initial information in a turbo coding manner;
the initial information modulation module comprises:
an initial information mapping submodule, configured to map the encoded initial information according to the determined gray code mapping relationship, so that a coding sequence corresponding to the encoded initial information is divided into multiple data groups, and each data group is mapped to a corresponding OAM mode sequence;
and the initial information modulation submodule is used for modulating the continuous Laguerre-Gaussian LG light beam into LG light beam information carrying each OAM mode sequence in the spatial light modulator.
In a third aspect, an embodiment of the present invention further discloses an information demodulation apparatus, which is applied to a receiving end, and the apparatus includes:
the target information acquisition module is used for acquiring target information of the transmitting terminal;
the demodulation sequence determining module is used for demodulating an Orbital Angular Momentum (OAM) model through a pre-trained Convolutional Neural Network (CNN) and determining an OAM demodulation sequence corresponding to the target information; the CNN demodulation OAM model is determined according to a plurality of OAM modulation information training;
and the initial information acquisition module is used for decoding the OAM demodulation sequence to acquire the initial information of the target information corresponding to the transmitting terminal.
Optionally, the target information is a light intensity map of a laguerre-gaussian LG light beam carrying OAM;
the target information acquisition module includes:
and receiving a light intensity diagram of the LG light beam sent by the transmitting terminal through a Charge Coupled Device (CCD) camera.
Optionally, the demodulation sequence determining module is specifically configured to input the light intensity map into a pre-trained CNN demodulation OAM model, so as to obtain an OAM demodulation sequence corresponding to the target information.
Optionally, the apparatus further comprises:
and the demodulation model determining module is used for training a plurality of pieces of OAM modulation information correspondingly formed through a plurality of OAM modulation modes under a tensoflow frame to obtain the CNN demodulation OAM model.
Optionally, the initial information obtaining module includes:
the demodulation mapping sequence acquisition submodule is used for carrying out inverse mapping on the OAM demodulation sequence in a Gray code mapping mode to obtain a demodulation mapping sequence;
and the initial information acquisition sub-module is used for decoding the demodulation mapping sequence in a turbo decoding mode to acquire the initial information of the target information corresponding to the transmitting end.
In a fifth aspect, an embodiment of the present invention further discloses a communication system, including a sending end and a receiving end;
the sending end is used for realizing any one of the information modulation methods;
the sending end is used for realizing any one of the information demodulation methods.
An embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the method step of any one of the above information demodulation methods is implemented.
The embodiment of the invention also provides a computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the method steps of any one of the information modulation methods are realized.
In the information modulation method, the information demodulation device and the communication system provided by the embodiment of the invention, initial information is converted into a binary coding sequence, and the coding sequence maps coding information to a corresponding OAM modulation mode through a determined Gray code mapping relation. After the atmospheric channel is transmitted, an OAM demodulation sequence corresponding to target information is determined through a pre-trained CNN demodulation OAM model, the OAM demodulation sequence is subjected to Gray code demapping, and decoding is carried out to obtain demodulated initial information. The embodiment of the invention improves the error correction performance of the communication system by encoding and mapping the initial information, and simultaneously, compared with the prior art that expensive optical devices are used for demodulating the information, the CNN demodulation OAM model reduces the cost of information demodulation and improves the efficiency of information demodulation.
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 described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of an information modulation method according to an embodiment of the present invention;
FIG. 2 is a flow chart of an information demodulation method according to an embodiment of the present invention;
fig. 3 is a structural diagram of a training process for constructing a CNN demodulation OAM model in an information demodulation method according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of an information modulation apparatus according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of an information modulation apparatus according to an embodiment of the present invention;
FIG. 6 is a communication system framework diagram according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a turbo coding structure in an information modulation method according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a turbo decoding structure in an information demodulation method according to an embodiment of the present invention;
fig. 9 is a diagram illustrating an example of a transmission image in a communication system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.
In a first aspect, an embodiment of the present invention discloses an information modulation method, which is applied to a transmitting end, as shown in fig. 1. Fig. 1 is a flowchart of an information modulation method according to an embodiment of the present invention, where the method includes:
and S101, encoding the initial information in a preset encoding mode.
Because the free space optical communication is strongly interfered by the atmospheric turbulence and the actual transmission channel of the free space optical communication has noise influence, errors exist between the information received after the channel transmission and the initial information of the transmitting end. To overcome the effects of atmospheric turbulence on optical communication performance, error correction coding is introduced into free-space optical communication to improve the transmission quality of the communication system. Meanwhile, to improve the data transmission efficiency, the information stream in the channel is usually required to be encoded to reduce the bit error rate, thereby enhancing the channel reliability.
And S102, mapping the coded initial information into a spatial light modulator.
In this step, the encoded initial information is mapped to a Spatial Light Modulator (SLM).
S103, performing Orbital Angular Momentum (OAM) modulation on the encoded initial information through the spatial light modulator to obtain target information determined by the light beam carrying the OAM information, and sending the target information to a receiving end.
In this step, a spatial light modulator modulates a Gaussian beam into an LG (Laguerre-Gaussian) beam carrying different OAM (Orbital angular momentum), and further, the encoded initial information forms target information modulated by OAM, and the target information is transmitted to a receiving end through a free space turbulent flow channel.
Optionally, the encoding the initial information in S101 by a preset encoding method may include:
the initial information is encoded by turbo coding.
The Turbo coding not only has excellent performance in a high-noise environment with low channel signal-to-noise ratio, but also has strong anti-fading and anti-interference capabilities. The embodiment of the invention selects Turbo coding to code the initial information at the transmitting end.
In S103, performing orbital angular momentum, OAM, modulation on the encoded initial information by using a spatial light modulator to obtain target information determined by a light beam carrying OAM information, which may include:
mapping the encoded initial information through a determined gray code mapping relationship, so that an encoding sequence corresponding to the encoded initial information is divided into a plurality of data groups for transmission, and each data group is mapped to each corresponding OAM mode sequence.
In the encoding of a group of numbers, if any two adjacent codes have only one binary digit different, the encoding is called gray code, and in addition, the maximum number and the minimum number also have only one bit different, namely, are connected end to end, so the encoding is also called cyclic code or reflective code. In digital systems, it is often required that the codes change in a certain order. For example, counting is incremented by a natural number, and if an 8421 code is used, then the four bits all change when the number 0111 changes to 1000, while in practice, a 4-bit change is unlikely to occur absolutely simultaneously, and other codes (1100, 1111, etc.) may be present briefly in the count. In certain situations, a pattern error or input error may result. Gray code mapping is to improve random mapping relationship and specially encode OAM mode combinations which are easy to be classified into errors.
In this step, in order to avoid misclassification of the OAM modulation scheme corresponding to the initial information encoded by the receiving end, after the initial information is encoded by using a preset code (for example, the initial information is encoded by using a Turbo code), a coding sequence corresponding to the encoded initial information is divided into a plurality of data groups by gray code mapping, and each data group is mapped to a corresponding OAM mode sequence.
For example, the OAM pattern {1, 3, -5} corresponding to the binary sequence "1011" is easily mistaken for the OAM pattern { -2} corresponding to the binary sequence "0100". Then, "1011" and "0100" are mapped to "1011" and "0011" by gray codes. Thus, when the receiving end divides {1, 3, -5} errors into { -2} errors through a CNN demodulation OAM model, the original code element "1011" is identified as "0011" at the output end, that is, the error of one-time classification only causes the code element sequence to generate 1-bit errors, thereby improving the transmission performance of the system.
And step two, modulating the continuous Laguerre-Gaussian LG light beam into LG light beam information carrying each OAM mode sequence in the spatial light modulator.
In the step, the continuous Laguerre-Gaussian LG light beam is modulated into LG light beam information carrying each OAM mode sequence in the SLM, and the LG light beam information is transmitted to a receiving end through a free space turbulent flow channel.
The most remarkable characteristic of the LG beam is that the LG beam carries a helical phase and has orbital angular momentum l(Representing the planck constant). Its mathematical description is:
wherein,representing the field distribution of the LG beam; w (z) represents a beam size parameter, subscripts l and p represent angular and radial mode numbers, respectively, Φ (z) represents the Gouy phase, R (z) represents the radius of curvature of the beam,representing the associated laguerre polynomial, i representing the imaginary unit, r representing the radiation distance of the beam to the transmission axis, and k representing the propagation constant.
In an information modulation method according to an embodiment of the present invention, initial information is encoded in a preset encoding manner; and performing orbital angular momentum OAM modulation on the encoded initial information through an SLM to obtain target information, and encoding and modulating the initial information to reduce the error rate in the information transmission process and improve the error correction performance of the whole communication system.
In a second aspect, an embodiment of the present invention discloses an information demodulation method, which is applied to a receiving end, as shown in fig. 2. Fig. 2 is a flowchart of an information demodulation method implemented by the present invention, the method including:
s201, acquiring target information of a transmitting terminal;
in this step, the receiving end obtains the target information of the transmitting end through an optical instrument, for example, a CCD (charged coupled device) camera is used to obtain the target information of the transmitting end.
Optionally, the target information is a light intensity map of a laguerre-gaussian LG light beam carrying OAM;
the acquiring of the target information of the transmitting end in S101 may include:
and receiving a light intensity diagram of the LG light beam sent by the transmitting terminal through a Charge Coupled Device (CCD) camera.
In this step, the target information is a light intensity map of the langeal-gaussian LG light beam carrying OAM, that is, the transmitting end maps the encoded initial information code to the SLM through a mapping relationship, and the SLM converts the gaussian light beam into the langeal-gaussian LG light beam to realize OAM modulation, that is, the encoded initial information is modulated into the light intensity map of the LG light beam carrying OAM and sent to the receiving end. The receiving end can receive the light intensity image of the LG light beam through a Charge Coupled Device (CCD) camera.
S202, determining an OAM demodulation sequence corresponding to target information through a pre-trained convolutional neural network CNN demodulation orbital angular momentum OAM model; the CNN demodulation OAM model is determined according to a plurality of OAM modulation information training.
After receiving the target information, the target information is input into a pre-trained CNN (convolutional neural Network) demodulation OAM (Orbital Angular momentum) model Orbital Angular momentum, and the CNN demodulation OAM model demodulates the target information to determine an OAM demodulation sequence corresponding to the target information.
In the embodiment of the invention, the CNN demodulation OAM model is determined according to a plurality of OAM modulation information training.
Optionally, the step of constructing the CNN demodulation OAM model in S202 may include:
and training a plurality of pieces of OAM modulation information correspondingly formed through a plurality of OAM modulation modes under a tenserflow frame to obtain a CNN demodulation OAM model.
In the embodiment of the invention, an open-source tensierflow frame can be adopted for training, and different OAM mode combination training sets are constructed for recognition training under an atmosphere transmission channel.
As shown in fig. 3, fig. 3 is a schematic structural diagram of a training process for constructing a CNN demodulation OAM model in an information demodulation method according to an embodiment of the present invention. In fig. 3, a plurality of pieces of OAM modulation image information formed by a plurality of OAM modulation schemes are subjected to feature extraction on each piece of OAM modulation information by the convolutional layer 1, the pooling layer 1, the convolutional layer 2, and the pooling layer 2 of the tenserflow frame, and each piece of OAM feature information of the preset OAM modulation scheme corresponding to each piece of OAM modulation information is obtained.
And then, further training each OAM characteristic information in a full connection layer to finally obtain a classification model corresponding to a preset OAM modulation mode of each OAM modulation information, and determining the classification model as a CNN demodulation OAM model.
Specifically, the OAM modulation information is an OAM modulation image, an OAM modulation image sample is collected, the size of the image is fixed, label classification is performed, an OAM modulation mode is manually classified, and OAM characteristic information corresponding to the OAM modulation mode is marked. Training is performed by using the structure shown in fig. 3, the OAM modulation image is cut, and dimension data and a hyper-parameter of each layer are set, and convolution training is performed. Extracting the local features and OAM feature information of the OAM modulation image, and then combining the individual local features of the OAM modulation image into an integral image feature. And multiplying the integral image characteristic information of each type of OAM modulation image by the weight and then adding an offset to obtain an output result mark. The pooling layer further improves the statistical efficiency of the network, the output of the convolutional layer is subjected to maximum pooling through the pooling layer, the data dimension is reduced, then OAM characteristic information of each type of OAM modulation image is distinguished through the full connection layer, a classification model corresponding to the OAM modulation mode of each OAM modulation image is obtained through training, and the classification model is determined to be a CNN demodulation OAM model.
S203, the OAM demodulation sequence is decoded, and initial information of a target information corresponding to a transmitting terminal is obtained.
And after the OAM demodulation sequence of the target information is obtained, decoding the demodulation sequence to further obtain initial information transmitted by a transmitting terminal.
Optionally, decoding the OAM demodulation sequence in S203 to obtain initial information that the target information corresponds to the transmitting end may include:
and step A, performing inverse mapping on the OAM demodulation sequence in a Gray code mapping mode to obtain a demodulation mapping sequence.
In order to reduce errors in the demodulation process of the CNN demodulation OAM model, a Gray code mapping mode can be adopted to inversely map the OAM demodulation sequence.
For the light intensity diagram of the LG light beam carrying a certain OAM modulation mode, if the CNN demodulation OAM model identifies an OAM modulation mode error, an OAM demodulation sequence obtained through the OAM modulation mode will have an error of at least 1 bit. In the worst case, the resulting OAM demodulation sequence may be all wrong.
For example, if the CNN demodulation OAM model erroneously recognizes that the OAM demodulation sequence in the light intensity map is a binary sequence "1011", the corresponding OAM mode of the OAM modulation scheme {1, 3, -5} as an OAM mode of the OAM modulation scheme { -2}, the output OAM demodulation sequence is a binary sequence "0100". That is, in this case, a single recognition error may cause 4-bit consecutive errors in the binary sequence corresponding to the OAM demodulation sequence. This may greatly increase the error rate of the communication process, which affects the communication performance of the system.
In this step, after the CNN demodulates the OAM model, an OAM demodulation mapping sequence is obtained, and the gray code demapps the OAM demodulation sequence into an undecoded transmission sequence. For example, OAM demodulation sequences corresponding to OAM modes {1, 3, -5}, { -2} demodulated by the CNN demodulation OAM model are "1011" and "0011", respectively, and are converted into "1011" and "0100" by gray code reflection.
And B, decoding the demodulation mapping sequence in a turbo decoding mode to obtain initial information of the target information corresponding to the transmitting end.
In this step, a decoding mode of Turbo coding corresponding to the transmitting terminal is adopted to decode the demodulation mapping sequence, and initial information of the target information corresponding to the transmitting terminal is obtained.
In the information demodulation method provided by the embodiment of the invention, the target information of the transmitting end is demodulated through a pre-trained orbital angular momentum CNN demodulation OAM model, and then an OAM demodulation sequence is decoded to obtain the initial information of the target information corresponding to the transmitting end. The embodiment of the invention adopts the trained CNN demodulation OAM model to directly demodulate the input information, and improves the information demodulation efficiency compared with the prior art that an optical device is adopted to demodulate the target information. In addition, compared with the existing method for demodulating information by using expensive optical devices, the embodiment of the invention adopts the volume CNN demodulation OAM model to demodulate the information, thereby reducing the cost of information demodulation.
In a third aspect, an embodiment of the present invention discloses an information modulation apparatus, which is applied to a transmitting end, as shown in fig. 4. Fig. 4 is a schematic structural diagram of an information modulation apparatus according to an embodiment of the present invention, the apparatus including:
an initial information encoding module 401, configured to encode initial information in a preset encoding manner;
an initial information mapping module 402, configured to map the encoded initial information into the spatial light modulator;
the initial information modulation module 403 is configured to perform track angular momentum OAM modulation on the encoded initial information through the spatial light modulator, obtain target information determined by a light beam carrying the OAM information, and send the target information to a receiving end.
Optionally, in an embodiment of the information modulating apparatus of the present invention, the initial information encoding module 401 is specifically configured to encode the initial information in a turbo coding manner;
the initial information modulation module 403 includes:
the initial information mapping submodule is used for mapping the encoded initial information through the determined gray code mapping relation, so that the encoding sequence corresponding to the encoded initial information is divided into a plurality of data groups, and each data group is mapped to each corresponding OAM mode sequence;
and the initial information modulation submodule is used for modulating the continuous Laguerre-Gaussian LG light beam into LG light beam information carrying each OAM mode sequence in the spatial light modulator.
In a fourth aspect, an embodiment of the present invention further discloses an information demodulating apparatus, as shown in fig. 5. Fig. 5 is a schematic structural diagram of an information modulation apparatus according to an embodiment of the present invention, which is applied to a receiving end, and the apparatus includes:
a target information obtaining module 501, configured to obtain target information of a transmitting end;
a demodulation sequence determination module 502, configured to demodulate an orbital angular momentum OAM model through a pre-trained convolutional neural network CNN, and determine an OAM demodulation sequence corresponding to target information; the CNN demodulation OAM model is determined according to a plurality of OAM modulation information training;
an initial information obtaining module 503, configured to decode the OAM demodulation sequence, and obtain initial information that the target information corresponds to the transmitting end.
Optionally, the target information is a light intensity map of a laguerre-gaussian LG light beam carrying OAM;
the target information obtaining module 501 includes:
and receiving a light intensity diagram of the LG light beam sent by the transmitting terminal through a Charge Coupled Device (CCD) camera.
Optionally, the demodulation sequence determining module 502 is specifically configured to input the light intensity map into a pre-trained CNN demodulation OAM model, so as to obtain an OAM demodulation sequence corresponding to the target information.
Optionally, the apparatus further comprises:
and the demodulation model determining module is used for training a plurality of pieces of OAM modulation information correspondingly formed through a plurality of OAM modulation modes under a tensoflow frame to obtain the CNN demodulation OAM model.
Optionally, the initial information obtaining module 503 includes:
the demodulation mapping sequence acquisition submodule is used for carrying out inverse mapping on the OAM demodulation sequence in a Gray code mapping mode to obtain a demodulation mapping sequence;
and the initial information acquisition sub-module is used for decoding the demodulation mapping sequence in a turbo decoding mode to acquire the initial information of the target information corresponding to the transmitting end.
In a fifth aspect, an embodiment of the present invention further discloses a communication system, including a sending end and a receiving end;
the transmitting end is used for realizing any one of the information modulation methods;
the sending end is used for realizing any one of the information demodulation methods.
Fig. 6 shows a communication system according to an embodiment of the present invention. The communication system comprises a transmitting end applying the information modulation method, an atmosphere turbulence channel and a receiving end applying the information demodulation method. The communication system is used as follows:
at a transmitting end, an information sequence corresponding to the initial information is firstly converted into a turbo coding sequence through turbo coding, and then OAM modulation is carried out on the turbo coding sequence. Namely, the turbo coding sequence is mapped through the determined gray code mapping relation, then the SLM modulates the Gaussian beam into the corresponding LG beam carrying different OAMs, and modulates the target information into the LG beam carrying OAM information.
For example, OAM modulated by a spatial light modulator is: s ═ 0001 "," 0010 "," 0100 "," 1000 "can correspond to {1}, { -2}, {3}, { -5}, respectively, where s denotes a symbol sequence, the symbol sequence can be superimposed on the spatial light modulator, and single modes of 4 {1}, { -2}, {3}, { -5} can form 16 combinations, that is, binary sequences corresponding to 16 OAM modulation sequences of 0000 to 1111, and one OAM modulation scheme corresponds to one binary sequence. And modulating the OAM modulation mode onto the LG light beam through an OAM modulator.
And then, transmitting the LG light beam to a receiving end through an atmospheric turbulence channel, capturing a light intensity diagram of the distorted LG light beam by a CCD camera at the receiving end, further transmitting the light intensity diagram to a trained CNN demodulation OAM model, analyzing an OAM demodulation sequence corresponding to the light intensity diagram in an off-line manner, performing inverse mapping on the OAM demodulation sequence in a Gray code mapping manner to obtain a demodulation mapping sequence, and performing turbo decoding on the demodulation mapping sequence to obtain a decoding sequence of target information corresponding to a transmitting end.
Wherein, the turbo coding mode of the transmitting end can be as shown in fig. 7. In fig. 7, the initial information is converted into an uncoded information sequence. The uncoded information sequence is transmitted to the encoder 1 resulting in the generated sequence 1. And simultaneously transmitting the interleaved information sequence to the same encoder 2 to obtain a generated sequence 2. The generated sequence 1 and the generated sequence 2 periodically delete some check bit information through a puncturing unit to generate a check sequence. And multiplexing the uncoded information sequence and the check sequence through a multiplexer to obtain a standard turbo coded sequence. In order to better resist burst errors in the identification process of the CNN demodulation OAM model, the standard turbo-coded sequence is divided into N groups for respective interleaving according to the using number N of the OAM modes. And multiplexing the interleaved sequence to obtain the novel turbo coding sequence.
Wherein, the turbo decoding manner at the receiving end can be as shown in fig. 8. In fig. 8, the OAM demodulation sequence demodulated by the CNN demodulation OAM model is input to a demultiplexer, deinterleaved in N sets of sequences, and each sequence is input to the corresponding deinterleaver 1, deinterleaver 2 … deinterleaver N, and deinterleaved. And the deinterleaved sequence passes through a multiplexer to obtain a standard turbo coding sequence, and the standard turbo coding sequence passes through the demultiplexer to obtain an information sequence, a check sequence 1 and a check sequence 2. The initialization extrinsic information is 0, and the extrinsic information sequence, the check sequence 1, and the information sequence are input to the soft output decoder 1. The extrinsic information generated after decoding by the decoder 1 is used as the prior information of the soft output decoder 2 after passing through the interleaver, the information of the interleaved information sequence and the check sequence 2 are input into the decoder 2, and the extrinsic information generated by the decoder 2 is sent into the deinterleaver for cyclic utilization. And repeating the decoding process, performing de-interleaving on the output of the decoder 2 after multiple iterations, and inputting the output to a decision device for hard decision to obtain initial information of the decoded target information corresponding to the transmitting terminal.
In the communication system applying the information modulation method and the information demodulation method, the turbo code is introduced into the OAM communication system, so that the system error correction performance is improved, the transmission reliability of the communication system is enhanced, the rapid demodulation is realized in the OAM space optical communication system through the convolutional neural network, and the performance of the convolutional neural network is further improved by adding the Gray code mapping relation.
The communication system of the embodiment of the present invention may have an application example as shown in fig. 9. Fig. 9 is a diagram illustrating an example of a transmission image in a communication system according to an embodiment of the present invention.
In this embodiment, the initial information of the transmitting end is a lens image with a pixel value of 128 × 128, and the lens image is firstly grayed and binarized to convert the pixel value into binary information containing 131072 bits, and then turbo-encoded.
After encoding is completed, gray code mapping is carried out, encoding mapping information is loaded on a continuous LG light beam through an SLM, code element information corresponding to the image is converted into a group of OAM mode combination information, and OAM modulation is carried out on the encoded image. And transmitting the modulated LG light beam carrying OAM information to a receiving end through an atmospheric turbulence channel.
In the transmission process, the OAM modulation scheme is very important to the performance of the transmission system because the interval of OAM states has a direct influence on the crosstalk between adjacent OAM modes. The CNN demodulation OAM model is adopted for demodulation, and theoretically, any one group of OAM modes can be selected for mapping, for example, in the embodiment, the OAM modes are selected as {1, -2, 3, -5} for combination, a plurality of OAM modulation modes are generated for transmission, and a light intensity diagram of a Laguerre-Gauss LG light beam with target information carrying OAM is generated.
At a receiving end, a light intensity map of the LG light beam carrying the OAM can be captured and processed by a CCD camera, and then the light intensity map is input into a pre-trained orbital angular momentum CNN demodulation OAM model for demodulation, namely, an OAM modulation mode corresponding to the light intensity map is determined, and then an OAM demodulation sequence is obtained by inverse mapping. And then, the OAM demodulation sequence is subjected to inverse mapping through Gray codes to obtain a demodulation mapping sequence, the demodulation mapping sequence is decoded through a turbo decoding mode to obtain a binary sequence corresponding to a transmitting end, and finally initial information of target information corresponding to the transmitting end is obtained.
For example, in this embodiment, the OAM modulation mode of the optical intensity map is {1, -2, 3, -5}, and demodulation is performed by using the CNN demodulation OAM model of the embodiment of the present invention, that is, the OAM modulation mode corresponding to the optical intensity map is {1, -2, 3, -5}, so as to obtain a binary sequence whose OAM demodulation sequence is "0111", and then the gray code mapping relationship reflects "0111" as "1111". The binary sequence is decoded by turbo decoding, i.e. the obtained binary data is rearranged to obtain a segment of code elements of the lens image at the transmitting end.
In the embodiment of the present invention, a lens image of 128 × 128 pixels is successfully restored. At the receiving end, if a suitable channel transmission distance and medium intensity turbulence are selected for transmission, the recovered image has high fidelity to the binary image.
Therefore, the feasibility of the communication system applying the information modulation method and the information demodulation method is verified through the embodiment of the invention.
The embodiment of the invention also provides a computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the method steps of any one of the information modulation methods are realized.
In a computer-readable storage medium according to an embodiment of the present invention, initial information is encoded in a preset encoding manner; and carrying out orbital angular momentum OAM modulation on the encoded initial information through a spatial light modulator to obtain target information, and encoding and modulating the initial information to reduce the error rate in the information transmission process and improve the error correction performance of a receiving end.
An embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the method step of any one of the above information demodulation methods is implemented.
In a computer-readable storage medium provided in an embodiment of the present invention, target information of a transmitting end is demodulated through a pre-trained orbital angular momentum CNN demodulation OAM model, and then an OAM demodulation sequence is decoded to obtain initial information of the target information corresponding to the transmitting end. The embodiment of the invention adopts the trained CNN demodulation OAM model to directly demodulate the input information, and improves the information demodulation efficiency compared with the prior art that an optical device is adopted to demodulate the target information. In addition, compared with the existing method for demodulating information by using expensive optical devices, the embodiment of the invention adopts the volume CNN demodulation OAM model to demodulate the information, thereby reducing the cost of information demodulation.
In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. The procedures or functions according to the embodiments of the invention are brought about in whole or in part when the computer program instructions are loaded and executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wirelessly (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.
It is noted that, herein, 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.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the device and storage medium embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiments.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. An information modulation method, applied to a transmitting end, the method comprising:
encoding the initial information by a preset encoding mode;
mapping the encoded initial information into a spatial light modulator;
and performing Orbital Angular Momentum (OAM) modulation on the encoded initial information through the spatial light modulator to obtain target information determined by the light beam carrying the OAM information, and sending the target information to a receiving end.
2. The information modulation method according to claim 1, wherein the encoding the initial information by a predetermined encoding method comprises:
encoding the initial information by a turbo coding mode;
the performing, by the spatial light modulator, orbital angular momentum, OAM, modulation on the encoded initial information to obtain target information determined by a light beam carrying OAM information includes:
mapping the encoded initial information through the determined gray code mapping relation, so that an encoding sequence corresponding to the encoded initial information is divided into a plurality of data groups, and each data group is mapped to each corresponding OAM mode sequence;
modulating, in the spatial light modulator, a continuous Laguerre-Gaussian LG beam into an LG beam carrying the OAM mode sequences.
3. An information demodulation method, applied to a receiving end, the method comprising:
acquiring target information of a transmitting terminal;
determining an OAM demodulation sequence corresponding to the target information through a pre-trained convolutional neural network CNN demodulation orbital angular momentum OAM model; the CNN demodulation OAM model is determined according to a plurality of OAM modulation information training;
and decoding the OAM demodulation sequence to obtain the initial information of the target information corresponding to the transmitting terminal.
4. The information demodulation method according to claim 3, wherein the target information is a light intensity map of a Laguerre-Gaussian LG beam carrying OAM;
the acquiring target information of the transmitting terminal includes:
and receiving a light intensity diagram of the LG light beam sent by the transmitting terminal through a Charge Coupled Device (CCD) camera.
5. The information demodulation method according to claim 4, wherein the determining an OAM demodulation sequence corresponding to the target information by demodulating an orbital angular momentum OAM model through a pre-trained Convolutional Neural Network (CNN) comprises:
and inputting the light intensity graph into a pre-trained CNN demodulation OAM model to obtain an OAM demodulation sequence corresponding to the target information.
6. The information demodulation method according to claim 3, wherein the step of constructing the CNN demodulation OAM model includes:
and training a plurality of pieces of OAM modulation information correspondingly formed through a plurality of OAM modulation modes under a tenserflow frame to obtain a CNN demodulation OAM model.
7. The information demodulation method according to claim 3, wherein the decoding the OAM demodulation sequence to obtain the target information corresponding to the initial information of the transmitting end comprises:
the OAM demodulation sequence is subjected to inverse mapping through a Gray code mapping mode to obtain a demodulation mapping sequence;
and decoding the demodulation mapping sequence by a turbo decoding mode to obtain the initial information of the target information corresponding to the transmitting terminal.
8. An information modulation apparatus, applied to a transmitting end, the apparatus comprising:
the initial information coding module is used for coding the initial information in a preset coding mode;
the initial information mapping module is used for mapping the encoded initial information into the spatial light modulator;
and the initial information modulation module is used for carrying out Orbital Angular Momentum (OAM) modulation on the encoded initial information through the spatial light modulator to obtain target information determined by the light beam carrying the OAM information, and sending the target information to a receiving end.
9. An information demodulation apparatus, applied to a receiving end, the apparatus comprising:
the target information acquisition module is used for acquiring target information of the transmitting terminal; the target information is the information of the initial information of the transmitting terminal after encoding and orbital angular momentum OAM modulation;
the demodulation sequence determining module is used for demodulating an Orbital Angular Momentum (OAM) model through a pre-trained Convolutional Neural Network (CNN) and determining an OAM demodulation sequence corresponding to the target information; the CNN demodulation OAM model is determined according to a plurality of OAM modulation information training;
and the demodulation sequence decoding module is used for decoding the OAM demodulation sequence to obtain the initial information of the target information corresponding to the transmitting terminal.
10. A communication system is characterized by comprising a sending end and a receiving end;
the sending end is used for implementing the information modulation method of any one of the above claims 1-2;
the transmitting end is configured to implement the information demodulation method according to any one of claims 3 to 7.
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