WO2017122924A1 - S2-psk 광학 무선 통신 방법 및 장치 - Google Patents
S2-psk 광학 무선 통신 방법 및 장치 Download PDFInfo
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- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
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Definitions
- the present invention relates to a method and apparatus for S2-PSK optical wireless communication.
- VLC Visible Light Communication
- PD photo diode
- OWC Optical Wirelesss Communications
- the present inventor is leading the OWC international standardization by submitting many articles on the OWC technology as the chairman of the IEEE 802.15.7r1 OWC TG international standardization organization, and the present invention is one of the most essential technologies of the OWC international standardization technology, S2-PSK. (Spatial 2-Phase Shift Keying) Modulation method.
- the present invention provides an optical wireless communication method and apparatus using an LED and an image sensor.
- An optical wireless communication apparatus includes a modulator and a transmitter, wherein the modulator generates a reference signal that periodically repeats binary values 0 and 1, and receives a first binary data signal. And outputting a second binary data signal, wherein the second binary data signal has the same frequency as the reference signal, and when the first binary data signal has a binary value of 0, is in phase with the reference signal and the first binary data.
- the phase is opposite to the reference signal, or when the first binary data signal is binary value 1, the phase is the same as the reference signal, and when the first binary data signal is binary value 0
- the transmitter the first light source blinks in accordance with the reference signal, characterized in that the second light source blinks in accordance with the second data signal, characterized in that The.
- the second binary data signal may be in phase with the reference signal when the first binary data signal has a binary value of 0 and the phase with the reference signal when the first binary data signal has a binary value of 1. It is characterized by the opposite.
- the line encoder may further include a line encoder for receiving a third binary data signal, encoding the third binary data at a code rate of 1/2, and outputting the first binary data signal. Outputs binary value (0,0) or (1, 1) if the signal is binary 0; outputs binary value (0,1) or (1, 0) if the binary value of the input signal is 1, or Output a binary value (0,1) or (1, 0) if the input signal is binary 0, and output a binary value (0,0) or (1, 1) if the input signal is binary 1 It features.
- the line encoder outputs a binary value (0,0) when the input signal is a binary value 0, and outputs a binary value (0,1) when the binary value of the input signal is 1. It is done.
- the modulator may be configured to receive a third binary data signal and output a fourth binary data signal, wherein the fourth binary data signal has the same frequency as the reference signal and the third binary data signal is equal to the third binary data signal.
- the phase is the same as the reference signal
- the third binary data signal is the binary value 1
- the phase is opposite to the reference signal or when the third binary data signal is the binary value 1
- the transmitter blinks a third light source according to the fourth binary data signal.
- An optical wireless communication apparatus includes a receiver and a demodulator, wherein the receiver receives images photographed continuously from an image sensor, and the demodulator is based on the images. If the blinking phase of the first light source on the images is the same as the blinking phase of the second light source on the images, the binary value is 0. If the blinking phase of the first light source and the blinking phase of the second light source are opposite, the binary value is 1; A first binary value of 1 when the blinking phase of the first light source and the blinking phase of the second light source are the same, and a binary value of 0 when the blinking phase of the first light source and the blinking phase of the second light source are opposite to each other; And outputting a data signal.
- the demodulator is a binary value of 0 when the blinking phase of the first light source on the images and the blinking phase of the second light source on the images are the same, and the blinking phase of the first light source and the second light source of the second light source.
- the first binary data signal having a binary value of 1 is output.
- a light source detector for detecting the position of the first light source and the second light source in each of the images, the demodulator, based on the position of the detected first light source and the second light source And outputs a binary data signal.
- the light source detector comprises an artificial neural network for detecting positions of the first light source and the second light source, the artificial neural network comprising a first neuron layer and a second neuron layer, and the first neuron
- the layer and the second neuron layer each comprise a convolutional layer and a RoI pooling layer, read previous positions of the first and second light sources, and generate a training data set for the artificial neural network based on the previous positions.
- the output of the artificial neural network is obtained by inputting the training data set. If the error of the output does not satisfy a target error, the weights of the artificial neural network are updated by back propagation, and then the training data set is input. Obtaining the output of the artificial neural network, and if the error of the output satisfies the target error, and outputs the positions of the first light source and the second light source do.
- the demodulator includes an artificial neural network that calculates an XOR value or an NXOR value of flickering states of the first and second light sources in consideration of noise, wherein the artificial neural network includes five neurons.
- a second hidden layer comprising one hidden layer and three neurons, wherein all neurons of the neural network are fully connected, the activation function of the first and second hidden layers is a tan-sigmoid function, the first light source and Read flashing states of a second light source, generate a training data set for the artificial neural network based on the flashing states, obtain the output of the artificial neural network with the training data set as input, and the error of the output is the target If the error is not satisfied, the weights of the artificial neural network are updated by back propagation, and then the training data set is input.
- the XOR value or the NXOR value of the flickering states of the first light source and the second light source is output.
- the line decoder may further include a line decoder configured to receive a first binary data signal, decode the first binary data at a code rate of 1/2, and output a second binary data signal.
- the line decoder may further include an input signal. Outputs binary value 0 when is binary value (0,0) or (1, 1), outputs binary value 1 when input signal is binary value (0,1) or (1, 0), or input signal If the binary value (0,0) or (1, 1) is a binary value 1, and if the input signal is a binary value (0,1) or (1, 0), it outputs a binary value 0 do.
- the line decoder outputs a binary value 0 when the input signal is a binary value (0,0) or (1, 1), and the input signal is a binary value (0,1) or (1, 0). ), The binary value 1 is output.
- the receiver characterized in that for receiving the images taken by the rolling shutter method from the image sensor.
- the light source detector detects a position of a third light source in each of the images, and the demodulator blinks the first light source based on the detected positions of the first light source and the third light source.
- the binary value is 0, and when the blinking phase of the first light source and the blinking phase of the third light source are opposite, the binary value is 1, or the blinking phase of the first light source and the third
- a second binary data signal having a binary value of 1 when the blinking phase of the three light sources is the same and a binary value of 0 when the blinking phase of the first light source and the blinking phase of the third light source are opposite to each other.
- An optical wireless communication apparatus includes a receiver and a demodulator, wherein the receiver receives images photographed continuously from an image sensor, and the demodulator receives data from the images by the following equation. It is characterized by demodulation.
- S 1 (k) and S 2 (k) represent the blinking state of the first light source and the blinking state of the second light source in the k-th image, respectively.
- An optical wireless communication apparatus includes a receiver and a demodulator, wherein the receiver receives images photographed continuously from an image sensor, and the demodulator receives data from the images by the following equation. It is characterized by demodulation.
- S 1 (k) and S 2 (k) represent the blinking state of the first light source and the blinking state of the second light source in the k-th image, respectively.
- the modulator generates a reference signal for periodically repeating binary values 0 and 1, the modulator receives a first binary data signal, the modulator, When the frequency is the same as the reference signal, the first binary data signal is a binary value 0 and the phase is the same as the reference signal, when the first binary data signal is a binary value 1 is in phase with the reference signal or the Outputting a second binary data signal that is in phase with the reference signal when the first binary data signal is a binary value 1 and that is in phase with the reference signal when the first binary data signal is a binary value 0; And flashing, by the transmitter, a first light source according to the reference signal, and flashing a second light source according to the second binary data signal.
- the line encoder may further include receiving a third binary data signal, encoding the third binary data at a code rate of 1/2, and outputting the first binary data signal. Outputs a binary value (0,0) or (1, 1) if the input signal is binary 0, and returns a binary value (0,1) or (1, 0) if the binary value of the input signal is 1 Outputs a binary value (0,1) or (1, 0) if the input signal is binary 0, and returns a binary value (0,0) or (1, 1) if the input signal is binary 1 It is characterized by outputting.
- An optical wireless communication method comprises the steps of: a receiver receiving images continuously photographed from an image sensor, and a demodulator, based on the images, a blinking phase of a first light source on the images Is a binary value of 0 when the blinking phase of the second light source on the images is the same, and a blinking phase of the first light source and a blinking phase of the second light source are binary values of 1, or Outputting a first binary data signal having a binary value of 1 when the blinking phase of the second light source is the same and a binary value of 0 when the blinking phase of the first light source and the blinking phase of the second light source are opposite to each other; It is characterized by.
- the method further comprises detecting a position of a first light source and a second light source in each of the images, and outputting a first binary data signal comprises: detecting the first light source and the first light source; 2 is performed based on the position of the light source.
- the light source detector comprises an artificial neural network for detecting positions of the first light source and the second light source, the artificial neural network comprising a first neuron layer and a second neuron layer, and the first neuron
- the layer and the second neuron layer each comprise a convolutional layer and a RoI pulling layer
- the detecting of the positions of the first and second light sources by the light source detector comprises: transferring the first and second light sources.
- Reading positions generating a training data set for the artificial neural network based on the previous positions, obtaining an output of the artificial neural network with the training data set as input, wherein the error of the output is a target error If not satisfied, updating the weights of the artificial neural network by back propagation, and obtaining the output of the artificial neural network by inputting the training data set; and And if the error of output satisfies a target error, outputting positions of the first light source and the second light source.
- the demodulator includes an artificial neural network that calculates an XOR value or an NXOR value of flickering states of the first and second light sources in consideration of noise, wherein the artificial neural network includes five neurons.
- a second hidden layer comprising one hidden layer and three neurons, wherein all neurons of the neural network are fully connected, the activation function of the first and second hidden layers is a tan-sigmoid function, and the demodulator is a first Generating a binary data signal may include reading flashing states of the first and second light sources, generating a training data set for the artificial neural network based on the flashing states, and inputting the training data set.
- the line decoder may further include receiving a first binary data signal, decoding the first binary data at a code rate of 1/2, and outputting a second binary data signal.
- Output binary value 0 if the input signal is binary (0,0) or (1, 1), output binary value 1 if the input signal is binary (0,1) or (1, 0) If the input signal is binary value (0,0) or (1, 1), output binary value 1; if the input signal is binary value (0,1) or (1, 0), output binary value 0 It is characterized by.
- the present invention includes a program stored in a medium for executing a method according to an embodiment of the present invention on a computer.
- the present invention includes a computer readable recording medium having recorded thereon a program for executing the method according to an embodiment of the present invention on a computer.
- wireless communication may be performed using an LED and an image sensor, and in particular, the vehicle-to-vehicle communication using a tail light of a vehicle and a smartphone may be efficiently performed.
- FIG. 1 is a diagram schematically illustrating a configuration of an optical wireless communication system according to an embodiment of the present invention.
- FIG. 2 is a view comparing an optical wireless communication method using one light source and an optical wireless communication method using two light sources.
- FIG. 3 is a diagram illustrating a modulation scheme of an optical wireless communication system according to an embodiment of the present invention.
- FIG. 4 is a diagram illustrating a demodulation scheme of an optical wireless communication system according to an embodiment of the present invention.
- FIG. 5 is a flowchart schematically showing the flow of a demodulation method using an artificial neural network according to an embodiment of the present invention.
- FIG. 6 is a diagram illustrating an XOR demodulator using an artificial neural network according to an embodiment of the present invention.
- FIG. 7 is a diagram illustrating a phenomenon that occurs when a plurality of light sources are photographed by a rolling shutter method.
- FIG. 8 is a diagram illustrating bad-sampling due to a long exposure time.
- FIG 9 illustrates an internal FEC according to an embodiment of the present invention.
- FIGS. 10 and 11 illustrate a use case to which an optical wireless communication system according to an embodiment of the present invention can be applied.
- an optical wireless communication system includes an optical wireless transmitting apparatus 100 and an optical wireless receiving apparatus 200, and the optical wireless transmitting apparatus 100 includes a modulator 110.
- the optical wireless receiver 200 may include a receiver 210 and a demodulator 230, and may further include a light source detector 220.
- the modulator 110 receives a binary data signal D [i], which is a bit sequence to be transmitted, and generates binary data signals S 1 (t) and S 2 (t) having a modulated pulse waveform.
- D [i] which is a bit sequence to be transmitted
- S 1 (t) and S 2 (t) having a modulated pulse waveform.
- S 1 and S 2 may be continuous signals or discrete signals, which will be described below with reference to continuous signals.
- the transmitter 120 transmits data by blinking the first light source 121 and the second light source 122 in accordance with the binary data signals S 1 (t) and S 2 (t), respectively.
- the blinking here does not necessarily indicate only how the light source is completely turned on and off, but includes all the ways of representing two states of binary values 0 and 1 using a change in brightness of the light source. If the flashing frequency of the light source is above a certain value (eg, 200 Hz), a person does not feel the light source blinking.
- the receiver 210 receives an image sequence in which an image sensor continuously photographs (samples) light sources.
- the light source detector 220 detects positions of the light sources in the received image.
- the demodulator 230 demodulates the data signal from the blinking state of the light sources.
- the transmitter 120 transmits data using two or more light sources.
- the transmitter 120 will be mainly described in the case where two light sources are used.
- the use of the plurality of light sources is to effectively perform optical wireless communication by spatially separating the data signal and the reference signal.
- the main considerations in implementing optical wireless communication are as follows. First, we need to consider whether we can support both global shutter and rolling shutter. That is, a communication method that can be used for both a global shutter camera (image sensor) and a rolling shutter camera is preferable. Second, consider the change in frame rate. In a device operating based on a general OS, the frame rate of the image sensor is not constant and changes according to the resource usage state of the OS. For example, for smartphone cameras, the frame rate fluctuates between approximately 20 fps and 30 fps. Therefore, it is desirable for the optical wireless communication scheme to support such a flexible frame rate.
- optical wireless communication has many use cases in which a transmitting device or a receiving device moves, and in particular, in a case of inter-vehicle communication, since the transmitting and receiving device moves at a high speed of 10 m / s or more, the continuous communication between the images captured by the image sensor is performed.
- the noise environment is likely to vary greatly. Therefore, it is preferable that the optical wireless communication system can cope with such sudden noise change.
- FIG. 2 is a view comparing an optical wireless communication method using one light source and an optical wireless communication method using two light sources.
- S (i) and the like are transmission signals and N (k) is noise at sampling. Due to the nature of asynchronous communication, the bit index i and the sampling index k of a transmission signal may be different.
- the reference signal S (i) and the data signal S ′ (i) are separated and transmitted temporally. Therefore, the sampling time points of the reference signal and the data signal are changed to k and k + 1, and the noise is also changed to N (k) and N (k + 1).
- the reference signal S 1 (i) and the data signal S 2 (i) may be spatially separated and transmitted simultaneously. Since the sampling of both signals occurs at the same time, the noise of both signals becomes equal to N (k). Therefore, the space separation method using a plurality of light sources can more effectively communicate in a situation where the environment changes rapidly, such as communication between vehicles. As will be described later, the present invention by the spatial separation method can demodulate data without being affected by the rolling shutter effect and the frame rate change.
- the first light source 121 of the two light sources flashing according to the signals S 1 (t) and S 2 (t) generated by the modulator 110 is a reference light source and a second light source 122.
- the data light source is a light source blinking by a data signal carrying data to be actually transmitted
- the reference light source is a light source blinking according to a reference signal that periodically repeats binary values 0 and 1.
- the reference signal S 1 (t) for blinking the reference light source is a pulse string signal that periodically repeats the binary values 0 and 1, and the waveform may be represented by Equation (1).
- T is the pulse period of the reference signal
- N pulses are included in one bit section
- k is a natural number of 1, ..., N.
- the data signal S 2 (t) which flashes the data light source is a pulse string signal having the same frequency as the reference signal S 1 (t), and is a reference when the data to be transmitted, that is, the input data signal D [i] is 0. If has the same phase as the signal S 1 (t), input data signals D [i] is one having a standard signal S 1 (t) and the opposite phase.
- the demodulator 230 compares the flickering state, that is, phase, of the first light source and the second light source in the sampled image.
- the demodulator 230 may use positions of the first light source and the second light source detected by the light source detector 220.
- the demodulator 230 outputs a binary value 0 when the two light sources have the same phase, and outputs a binary value 1 when the phases of the two light sources are opposite. That is, the demodulator 230 demodulates by XOR operation on the blinking state of the two light sources as shown in Equation (2).
- S 1 (k) and S 2 (k) are the blinking states of each light source in the k-th image.
- the demodulator 230 outputs a binary value 0 when both light sources are turned on or off in the sampled image, and outputs a binary value 1 when only one light source is turned on. Accordingly, the optical radio receiver 200 does not need to know which of the two light sources is the reference light source and which is the data light source for demodulation. It also compares two light sources captured in a single image, so if the frame rate of the image sensor changes, it is not affected. However, the frame rate must be greater than or equal to the frequency of the data clock.
- the modulator 110 is the data signal S 2 (t) is the input data, if the signal is a first reference signal when the S 1 has the same phase as (t), the input data signal is zero, the reference signal S 1 (t)
- demodulator 230 performs demodulation by NXOR operation instead of XOR in Equation 2.
- the former will be referred to as the first modulation scheme and the latter as the second modulation scheme, and the description will be made based on the first modulation scheme as a reference unless otherwise specified.
- the first modulation scheme and the second modulation scheme are merely a matter of phase selection for data values, and correspond substantially to the same technical idea.
- the optical wireless receiver 200 may use two-phase neural network training to reduce an error due to a noise environment.
- the two-stage neural network consists of one step of detecting the positions of the light sources and two steps of calculating the XOR.
- the periodic bit intervals can be learned from the past (ie, previous images), and the neural network determines the features of interest of the light source (e.g. region of interest (RoI), the size of the light source, and the brightness of the ON state). You can refer to what you have learned in doing so.
- region of interest RoI
- the neural network of the light source detector 220 obtains existing positions of the light sources from the captured images and estimates the current position. Once the neural network finishes learning, it can go through the verification process by processing all the images. In addition, it is necessary to consider that the flickering state of the light source is affected by the noise when the demodulator 230 performs the XOR operation. Since a pair of noisy inputs require an efficient noisy XOR operator, we also use an artificial neural network.
- the light source detector 220 includes an artificial neural network that detects positions of a first light source and a second light source, and the artificial neural network includes a first neuron layer and a second neuron layer.
- the first neuron layer acts as a filter to output a relative region of interest in which the light sources are located, and the second neuron layer determines the exact location of the light sources and groups the light sources into pairs belonging to each vehicle.
- the first neuron layer and the second neuron layer each comprise a convolutional layer and a RoI pooling layer. Convolution is a translational invariant.
- the convolutional layer learns which features include the light sources.
- the strength of the output signal is independent of where the features are located and simply depends on whether the features are present. Since the bit interval is known, the brightness relationship between two light sources of a vehicle can be predicted. Therefore, even if the light source pair moves to another position, the artificial neural network can still recognize this.
- the region of interest is downsampled by the RoI pooling layer to reduce the size. RoI pooling also reduces the sensitivity to noise. The last RoI pooling ends when the center of the light sources is detected as an acceptable error.
- the light source detector 220 reads previous positions of the first light source and the second light source, generates a training data set for the artificial neural network based on the previous positions, and uses the training data set as an input to output the output of the artificial neural network. Obtain If the error of the output does not satisfy the target error, the weights of the neural network are updated by backpropagation, and then the process of obtaining the output of the neural network by inputting the training data set is repeated.
- the artificial neural network uses the information it learns (including the flashing section of the light source and the relative position between the light source pairs) to detect the position of the light sources within the RoI. Without the neural network, it is impossible to detect the position of the light sources that are completely off.
- the positions of the first light source and the second light source are output.
- the brightness of the light sources is detected and input to the next step.
- the data set can be enlarged by augmentation of available data to train the artificial neural network.
- the position shift, size change, rotation, and flip of the light source may be used.
- the demodulator 230 includes an artificial neural network that calculates XOR values of flickering states of the first light source and the second light source in consideration of noise.
- the neural network comprises a first hidden layer comprising five neurons and a second hidden layer comprising three neurons, all the neurons of the neural network are completely connected, and the activation function of the first and second hidden layers is tan-sigmoid It can be a function.
- the demodulator 230 reads the blinking states of the first light source and the second light source, generates a training data set for the artificial neural network based on the blinking states, and obtains the output of the artificial neural network by using the training data set as an input.
- the weights of the artificial neural network are updated by back propagation, and then the process of obtaining the output of the artificial neural network by inputting a training data set is repeated. If the error of the output satisfies the target error, the XOR value or NXOR value of the flashing states of the first light source and the second light source is output.
- the error may be a mean square error.
- 6 is a diagram illustrating an XOR demodulator using an artificial neural network according to an embodiment of the present invention. W denotes a weight, B denotes a bias, and the bias may be regarded as one weight.
- the sampling time of the two light sources may be different depending on the rotation state or the distance between the light source and the image sensor, which leads to variations in the flickering phase difference between the two light sources, resulting in an error in demodulation.
- the demodulated data may be 1 because one light source is turned on and one is turned off in the sampled image.
- the sampled image may be zero in both demodulated data because the light sources are both turned on or both turned off.
- One embodiment of the present invention uses additional line coding to reduce such errors.
- the optical wireless transmission apparatus 100 may include a line encoder in front of the modulator 110.
- the line encoder encodes and outputs the binary data signal D [i] at a code rate of 1/2 according to Table 1, and the modulator 110 receives the line code output by the line encoder and receives the binary data signal S in the same manner as described above. Produces 1 (t) and S 2 (t).
- the optical wireless receiver 200 includes a line decoder at the rear end of the demodulator 230, and the line decoder receives the demodulated binary data signal from the demodulator 230 and decodes it according to Equation (4).
- XOR (k) is an output signal of the demodulator 230 and means a binary value demodulated in the k-th image.
- the data to be decoded is determined according to the relative relationship between the light source flickering state of one image and the light source flickering state of the next image, thereby obtaining the same result regardless of the absolute light source flickering state.
- the first light source and the second light source of the sampled image have a flashing phase reversed from the original due to the sampling time difference due to the rolling shutter effect, that is, the transmission data is 0, the two light sources flash in the opposite direction, or the transmission data is 1 Even when the two light sources are blinking the same, demodulation is normally performed. Therefore, in the case of using the line coding in this way, the optical radio receiver 200 does not need to know whether the modulation method of the optical radio transmitting apparatus 100 is the first modulation method or the second modulation method.
- the demodulation is normally performed only when two consecutive images used by the line decoder have the same rolling shutter error, and an error still occurs when only one of the two images has the rolling shutter error. That is, according to the present invention, an error due to the rolling shutter effect does not occur when the rotation state of the light source and the image sensor does not change, and an error may occur when the rotation state changes.
- Tables 2 and 3 show the effects of line coding.
- Table 2 shows the effects of the rolling shutter effect on the case of no line coding and Table 3 on the case of line coding. This is the case that the demodulation error occurs because the shaded part of the table is out of phase due to the rolling shutter effect.
- the line decoder has no problem in decoding even if two consecutive pairs of images constituting the line code are grouped incorrectly.
- the line decoder must decode the kth image and the k + 1th image with one code, and k + 2th image and the k + 3th image with one code. Even if the image and k-th image are combined into one code and the k + 1 and k + 2th images are combined into one code, the decoding is normally performed.
- the line decoder according to the present invention decodes the flashing state of two consecutive images by XOR. In other words, when the flashing state of two consecutive images is not changing, 0 is outputted, and 1 is outputted each time a change occurs. Therefore, even if the images are pushed or pulled one by one, the result is not changed.
- the same effect can be obtained when the line encoder uses any one of four encoding schemes as shown in Table 6, and the line decoder performs decoding by NXORing the blinking states of two consecutive images as shown in Equation (5).
- the modulation and demodulation schemes according to Tables 5 and 6 and Equations 4 and 5 are all substantially the same technical idea.
- FIG. 8 is a diagram illustrating bad-sampling due to a long exposure time.
- additional errors may occur due to the rotation of the light source or the image sensor. This occurs when one light source is sampled at the Nth bit interval and the other light source is sampled at the N + 1th bit interval.
- an inner FEC of code rate 1/4 is used according to the IEE 802.15.7 VLC standard. That is, as shown in FIG. 9, a 1/3 mother code is punctured to obtain a 1/2 code, and a 1/4 code is obtained using a simple repetition code.
- optical wireless communication system is compatible with both the global shutter and the rolling shutter, and is compatible with a widely varying frame rate, and can be applied to the rapid movement of a light source or an image sensor. Since it operates normally even when rotated at an angle, it is particularly useful for communication between vehicles.
- FIG. 10 and 11 illustrate a use case to which an optical wireless communication system according to an embodiment of the present invention can be applied.
- data may be transmitted using an LED tail light of a vehicle, and short identification information or a short message may be transmitted between vehicles.
- the signboard may be divided into left and right or up and down to use the two light sources to apply the optical wireless communication of the present invention. When the light source blinks fast enough, people do not feel the rear lights or signs flashing.
- the optical wireless communication system of the present invention may use three or more light sources, and may use one of the plurality of light sources as a reference signal and the other as a data signal.
- the data signals may transmit the same signal to each other for diversity or may transmit different signals to improve transmission speed.
- Computer-readable recording media include all storage media, including magnetic storage media, optical reading media and carrier waves (eg, transmission over the Internet).
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Abstract
Description
Claims (25)
- 변조기; 및 송신기를 포함하며,상기 변조기는,이진값 0과 1을 주기적으로 반복하는 기준 신호를 생성하고,제1 이진 데이터 신호를 입력받고,제2 이진 데이터 신호를 출력하며,상기 제2 이진 데이터 신호는,상기 기준 신호와 주파수가 같고,상기 제1 이진 데이터 신호가 이진값 0인 경우 상기 기준 신호와 위상이 같고, 상기 제1 이진 데이터 신호가 이진값 1인 경우 상기 기준 신호와 위상이 반대이거나,상기 제1 이진 데이터 신호가 이진값 1인 경우 상기 기준 신호와 위상이 같고, 상기 제1 이진 데이터 신호가 이진값 0인 경우 상기 기준 신호와 위상이 반대이며,상기 송신기는,상기 기준 신호에 따라 제1 광원을 점멸시키고, 상기 제2 이진 데이터 신호에 따라 제2 광원을 점멸시키는 것을 특징으로 하는 광학 무선 통신 장치.
- 제1항에 있어서,상기 제2 이진 데이터 신호는,상기 제1 이진 데이터 신호가 이진값 0인 경우 상기 기준 신호와 위상이 같고, 상기 제1 이진 데이터 신호가 이진값 1인 경우 상기 기준 신호와 위상이 반대인 것을 특징으로 하는 광학 무선 통신 장치.
- 제1항에 있어서,제3 이진 데이터 신호를 입력받고, 상기 제3 이진 데이터를 부호율 1/2로 부호화하여 상기 제1 이진 데이터 신호를 출력하는 선로 부호기를 더 포함하며,상기 선로 부호기는,입력 신호가 이진값 0인 경우 이진값 (0,0) 또는 (1, 1)을 출력하고, 입력 신호의 이진값이 1인 경우 이진값 (0,1) 또는 (1, 0)을 출력하거나,입력 신호가 이진값 0인 경우 이진값 (0,1) 또는 (1, 0)을 출력하고, 입력 신호가 이진값 1인 경우 이진값 (0,0) 또는 (1, 1)을 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제3항에 있어서,상기 선로 부호기는,입력 신호가 이진값 0인 경우 이진값 (0,0)을 출력하고, 입력 신호의 이진값이 1인 경우 이진값 (0,1)을 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제1항에 있어서,상기 변조기는,제3 이진 데이터 신호를 입력받고,제4 이진 데이터 신호를 출력하며,상기 제4 이진 데이터 신호는,상기 기준 신호와 주파수가 같고,상기 제3 이진 데이터 신호가 이진값 0인 경우 상기 기준 신호와 위상이 같고, 상기 제3 이진 데이터 신호가 이진값 1인 경우 상기 기준 신호와 위상이 반대이거나,상기 제3 이진 데이터 신호가 이진값 1인 경우 상기 기준 신호와 위상이 같고, 상기 제3 이진 데이터 신호가 이진값 0인 경우 상기 기준 신호와 위상이 반대이며,상기 송신기는,상기 제4 이진 데이터 신호에 따라 제3 광원을 점멸시키는 것을 특징으로 하는 광학 무선 통신 장치.
- 수신기; 및 복조기를 포함하며,상기 수신기는,이미지 센서로부터 연속적으로 촬영한 이미지들을 수신하고,상기 복조기는,상기 이미지들에 기초하여,상기 이미지들상의 제1 광원의 점멸 위상과 상기 이미지들상의 제2 광원의 점멸 위상이 같은 경우 이진값 0이고 상기 제1 광원의 점멸 위상과 상기 제2 광원의 점멸 위상이 반대인 경우 이진값 1이거나,상기 제1 광원의 점멸 위상과 상기 제2 광원의 점멸 위상이 같은 경우 이진값 1이고 상기 제1 광원의 점멸 위상과 상기 제2 광원의 점멸 위상이 반대인 경우 이진값 0인,제1 이진 데이터 신호를 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제6항에 있어서,상기 복조기는,상기 이미지들상의 제1 광원의 점멸 위상과 상기 이미지들상의 제2 광원의 점멸 위상이 같은 경우 이진값 0이고 상기 제1 광원의 점멸 위상과 상기 제2 광원의 점멸 위상이 반대인 경우 이진값 1인 제1 이진 데이터 신호를 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제6항에 있어서,상기 이미지들 각각에서 제1 광원 및 제2 광원의 위치를 검출하는 광원 검출기를 더 포함하며,상기 복조기는, 상기 검출된 제1 광원 및 제2 광원의 위치에 기초하여 제1 이진 데이터 신호를 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제8항에 있어서,상기 광원 검출기는,상기 제1 광원 및 제2 광원의 위치들을 검출하는 인공신경망을 포함하고,상기 인공신경망은 제1 뉴런층 및 제2 뉴런층을 포함하고,상기 제1 뉴런층 및 제2 뉴런층은 각각 컨볼루션층 및 RoI 풀링층을 포함하며,상기 제1 광원 및 제2 광원의 이전 위치들을 읽고,상기 이전 위치들에 기초하여 상기 인공신경망을 위한 학습 데이터 세트를 생성하고,상기 학습 데이터 세트를 입력으로 하여 상기 인공신경망의 출력을 구하고,상기 출력의 오류가 목표 오류를 만족시키지 않으면, 역전파에 의해 상기 인공신경망의 가중치들을 갱신한 후, 상기 학습 데이터 세트를 입력으로 하여 상기 인공신경망의 출력을 구하고,상기 출력의 오류가 목표 오류를 만족시키면, 상기 제1 광원 및 제2 광원의 위치들을 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제6항에 있어서,상기 복조기는,노이즈를 고려하여 상기 제1 광원 및 제2 광원의 점멸 상태들의 XOR 값 또는 NXOR 값을 계산하는 인공신경망을 포함하고,상기 인공신경망은 5개의 뉴런을 포함하는 제1 은닉층 및 3개의 뉴런을 포함하는 제2 은닉층을 포함하고,상기 인공신경망의 모든 뉴런들은 완전히 연결돼 있고,상기 제1 및 제2 은닉층의 활성화 함수는 tan-sigmoid 함수이며,상기 제1 광원 및 제2 광원의 점멸 상태들을 읽고,상기 점멸 상태들에 기초하여 상기 인공신경망을 위한 학습 데이터 세트를 생성하고,상기 학습 데이터 세트를 입력으로 하여 상기 인공신경망의 출력을 구하고,상기 출력의 오류가 목표 오류를 만족시키지 않으면, 역전파에 의해 상기 인공신경망의 가중치들을 갱신한 후, 상기 학습 데이터 세트를 입력으로 하여 상기 인공신경망의 출력을 구하고,상기 출력의 오류가 목표 오류를 만족시키면, 상기 제1 광원 및 제2 광원의 점멸 상태들의 XOR 값 또는 NXOR 값을 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제6항에 있어서,제1 이진 데이터 신호를 입력받고, 상기 제1 이진 데이터를 부호율 1/2로 복호화하여 제2 이진 데이터 신호를 출력하는 선로 복호기를 더 포함하며,상기 선로 복호기는,입력 신호가 이진값 (0,0) 또는 (1, 1)인 경우 이진값 0을 출력하고, 입력 신호가 이진값 (0,1) 또는 (1, 0)인 경우 이진값 1을 출력하거나,입력 신호가 이진값 (0,0) 또는 (1, 1)인 경우 이진값 1을 출력하고, 입력 신호가 이진값 (0,1) 또는 (1, 0)인 경우 이진값 0을 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제11항에 있어서,상기 선로 복호기는,입력 신호가 이진값 (0,0) 또는 (1, 1)인 경우 이진값 0을 출력하고, 입력 신호가 이진값 (0,1) 또는 (1, 0)인 경우 이진값 1을 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제11항에 있어서,상기 수신기는,상기 이미지 센서로부터 롤링 셔터 방식으로 촬영한 이미지들을 수신하는 것을 특징으로 하는 광학 무선 통신 장치.
- 제8항에 있어서,상기 광원 검출기는,상기 이미지들 각각에서 제3 광원의 위치를 검출하고,상기 복조기는,상기 검출된 제1 광원 및 제3 광원의 위치에 기초하여,상기 제1 광원의 점멸 위상과 상기 제3 광원의 점멸 위상이 같은 경우 이진값 0이고 상기 제1 광원의 점멸 위상과 상기 제3 광원의 점멸 위상이 반대인 경우 이진값 1이거나,상기 제1 광원의 점멸 위상과 상기 제3 광원의 점멸 위상이 같은 경우 이진값 1이고 상기 제1 광원의 점멸 위상과 상기 제3 광원의 점멸 위상이 반대인 경우 이진값 0인,제2 이진 데이터 신호를 출력하는 것을 특징으로 하는 광학 무선 통신 장치.
- 수신기; 및 복조기를 포함하며,상기 수신기는 이미지 센서로부터 연속적으로 촬영한 이미지들을 수신하고,상기 복조기는 다음 식에 의해 상기 이미지들로부터 데이터를 복조하는 것을 특징으로 하는 광학 무선 통신 장치.bit = XOR[XOR{s1(k); s2(k)}; XOR{s1(k+1); s2(k+1)}]상기 식에서 S1(k) 및 S2(k)는 k번째 이미지에서의 제1 광원의 점멸 상태 및 제2 광원의 점멸 상태를 각각 나타냄.
- 변조기가 이진값 0과 1을 주기적으로 반복하는 기준 신호를 생성하는 단계;상기 변조기가 제1 이진 데이터 신호를 입력받는 단계;상기 변조기가,상기 기준 신호와 주파수가 같고,상기 제1 이진 데이터 신호가 이진값 0인 경우 상기 기준 신호와 위상이 같고, 상기 제1 이진 데이터 신호가 이진값 1인 경우 상기 기준 신호와 위상이 반대이거나,상기 제1 이진 데이터 신호가 이진값 1인 경우 상기 기준 신호와 위상이 같고, 상기 제1 이진 데이터 신호가 이진값 0인 경우 상기 기준 신호와 위상이 반대인,제2 이진 데이터 신호를 출력하는 단계; 및송신기가,상기 기준 신호에 따라 제1 광원을 점멸시키고, 상기 제2 이진 데이터 신호에 따라 제2 광원을 점멸시키는 단계를 포함하는 것을 특징으로 하는 광학 무선 통신 방법.
- 제17항에 있어서,선로 부호기가, 제3 이진 데이터 신호를 입력받고, 상기 제3 이진 데이터를 부호율 1/2로 부호화하여 상기 제1 이진 데이터 신호를 출력하는 단계를 더 포함하며,상기 선로 부호기는,입력 신호가 이진값 0인 경우 이진값 (0,0) 또는 (1, 1)을 출력하고, 입력 신호의 이진값이 1인 경우 이진값 (0,1) 또는 (1, 0)을 출력하거나,입력 신호가 이진값 0인 경우 이진값 (0,1) 또는 (1, 0)을 출력하고, 입력 신호가 이진값 1인 경우 이진값 (0,0) 또는 (1, 1)을 출력하는 것을 특징으로 하는 광학 무선 통신 방법.
- 수신기가 이미지 센서로부터 연속적으로 촬영한 이미지들을 수신하는 단계; 및복조기가,상기 이미지들에 기초하여,상기 이미지들상의 제1 광원의 점멸 위상과 상기 이미지들상의 제2 광원의 점멸 위상이 같은 경우 이진값 0이고 상기 제1 광원의 점멸 위상과 상기 제2 광원의 점멸 위상이 반대인 경우 이진값 1이거나,상기 제1 광원의 점멸 위상과 상기 제2 광원의 점멸 위상이 같은 경우 이진값 1이고 상기 제1 광원의 점멸 위상과 상기 제2 광원의 점멸 위상이 반대인 경우 이진값 0인,제1 이진 데이터 신호를 출력하는 단계를 포함하는 것을 특징으로 하는 광학 무선 통신 방법.
- 제19항에 있어서,광원 검출기가 상기 이미지들 각각에서 제1 광원 및 제2 광원의 위치를 검출하는 단계를 더 포함하고,제1 이진 데이터 신호를 출력하는 단계는, 상기 검출된 제1 광원 및 제2 광원의 위치에 기초하여 수행되는 것을 특징으로 하는 광학 무선 통신 방법.
- 제20항에 있어서,상기 광원 검출기는,상기 제1 광원 및 제2 광원의 위치들을 검출하는 인공신경망을 포함하고,상기 인공신경망은 제1 뉴런층 및 제2 뉴런층을 포함하고,상기 제1 뉴런층 및 제2 뉴런층은 각각 컨볼루션층 및 RoI 풀링층을 포함하며,상기 광원 검출기가 상기 제1 광원 및 상기 제2 광원의 위치를 검출하는 단계는,상기 제1 광원 및 제2 광원의 이전 위치들을 읽는 단계;상기 이전 위치들에 기초하여 상기 인공신경망을 위한 학습 데이터 세트를 생성하는 단계;상기 학습 데이터 세트를 입력으로 하여 상기 인공신경망의 출력을 구하는 단계;상기 출력의 오류가 목표 오류를 만족시키지 않으면, 역전파에 의해 상기 인공신경망의 가중치들을 갱신한 후, 상기 학습 데이터 세트를 입력으로 하여 상기 인공신경망의 출력을 구하는 단계; 및상기 출력의 오류가 목표 오류를 만족시키면, 상기 제1 광원 및 제2 광원의 위치들을 출력하는 단계를 포함하는 것을 특징으로 하는 광학 무선 통신 방법.
- 제19항에 있어서,상기 복조기는,노이즈를 고려하여 상기 제1 광원 및 제2 광원의 점멸 상태들의 XOR 값 또는 NXOR 값을 계산하는 인공신경망을 포함하고,상기 인공신경망은 5개의 뉴런을 포함하는 제1 은닉층 및 3개의 뉴런을 포함하는 제2 은닉층을 포함하고,상기 인공신경망의 모든 뉴런들은 완전히 연결돼 있고,상기 제1 및 제2 은닉층의 활성화 함수는 tan-sigmoid 함수이며,상기 복조기가 제1 이진 데이터 신호를 생성하는 단계는,상기 제1 광원 및 제2 광원의 점멸 상태들을 읽는 단계;상기 점멸 상태들에 기초하여 상기 인공신경망을 위한 학습 데이터 세트를 생성하는 단계;상기 학습 데이터 세트를 입력으로 하여 상기 인공신경망의 출력을 구하는 단계;상기 출력의 오류가 목표 오류를 만족시키지 않으면, 역전파에 의해 상기 인공신경망의 가중치들을 갱신한 후, 상기 학습 데이터 세트를 입력으로 하여 상기 인공신경망의 출력을 구하는 단계; 및상기 출력의 오류가 목표 오류를 만족시키면, 상기 제1 광원 및 제2 광원의 점멸 상태들의 XOR 값 또는 NXOR 값을 출력하는 단계를 포함하는 것을 특징으로 하는 광학 무선 통신 방법.
- 제19항에 있어서,선로 복호기가, 제1 이진 데이터 신호를 입력받고, 상기 제1 이진 데이터를 부호율 1/2로 복호화하여 제2 이진 데이터 신호를 출력하는 단계를 더 포함하며,상기 선로 복호기는,입력 신호가 이진값 (0,0) 또는 (1, 1)인 경우 이진값 0을 출력하고, 입력 신호가 이진값 (0,1) 또는 (1, 0)인 경우 이진값 1을 출력하거나,입력 신호가 이진값 (0,0) 또는 (1, 1)인 경우 이진값 1을 출력하고, 입력 신호가 이진값 (0,1) 또는 (1, 0)인 경우 이진값 0을 출력하는 것을 특징으로 하는 광학 무선 통신 방법.
- 제17항 내지 제22항 중 어느 한 항의 방법을 컴퓨터에서 실행시키기 위하여 매체에 저장된 컴퓨터프로그램.
- 제17항 내지 제22항 중 어느 한 항의 방법을 수행하는 프로그램이 기록된 컴퓨터로 읽을 수 있는 기록매체.
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