RoI-based optical wireless communication method and device
View Patent ↗An optical wireless transmission device according to an embodiment of the present invention comprises: a modulation unit for receiving input of a first input signal and outputting a first output signal; and a light source control unit for controlling a first light source in accordance with the first output signal. The first output signal repeats “0” and “1” in a first phase during clock time if a binary value of the first input signal is 0, and repeats “0” and “1” in a phase opposite from the first phase during the clock time if a binary value of the first input signal is 1.
1. An optical wireless reception apparatus, the optical wireless reception apparatus comprising:
an image reception unit receiving images obtained by photographing a light source at a first sampling rate from a first image sensor; and
a demodulation unit outputting restored data of a first data rate based on the images,
wherein the first data rate is half of the first sampling rate, and the demodulation unit compares flashing states of the light source with respect to two consecutive images, and outputs a binary value identical to or opposite to a previous value of the restored data as a next value of the restored data.
2. The optical wireless reception apparatus according to claim 1 , wherein when the flashing states of the light source with respect to the two consecutive images are equal, the demodulation unit outputs the binary value opposite to the previous value of the restored data as the next value of the restored data, and when the flashing states of the light source with respect to the two consecutive images are different, the demodulation unit outputs the binary value equal to the previous value of the restored data as the next value of the restored data.
3. The optical wireless reception apparatus according to claim 1 , wherein the demodulation unit determines that a preamble is detected when the flashing states of the light source are equal for four consecutive images.
4. The optical wireless reception apparatus according to claim 1 , wherein the demodulation unit determines that a preamble is detected when the flashing states of the light source are equal for three consecutive images.
5. The optical wireless reception apparatus according to claim 1 , wherein the demodulation unit outputs first restored data after detecting a preamble as a binary value 1.
6. The optical wireless reception apparatus according to claim 1 , wherein the demodulation unit outputs restored data for two images after detecting a preamble as a binary value .
7. The optical wireless reception apparatus according to claim 1 , wherein the demodulation unit detects a position of the light source based on the images obtained by photographing the light source at the first sampling rate.
8. The optical wireless reception apparatus according to claim 7 , wherein the demodulation unit obtains identification information of the light source from the restored data of the first data rate.
9. The optical wireless reception apparatus according to claim 7 , wherein the image reception unit receives images obtained by photographing the light source at a second sampling rate higher than the first sampling rate from a second image sensor, and the demodulation unit outputs restored data having a second data rate higher than the first data rate based on the images obtained by photographing the light source at the second sampling rate.
10. The optical wireless reception apparatus according to claim 9 , wherein the second image sensor photographs the light source at the second sampling rate based on a position of the light source, which is detected based on the images obtained by photographing the light source at the first sampling rate.
11. The optical wireless reception apparatus according to claim 9 , wherein the demodulation unit restores the restored data of the second data rate from the images obtained by photographing the light source at the second sampling rate based on the position of the light source, which is detected based on the images obtained by photographing the light source at the first sampling rate.
12. The optical wireless reception apparatus according to claim 1 , wherein the images are photographed by a rolling shutter scheme, and the demodulation unit obtains restored data with respect to different rows in which the light source is photographed in the two consecutive images, and determines final restored data through a majority voting based on the restored data.
13. An optical wireless reception method, the optical wireless reception method comprising:
receiving, by an image reception unit, images obtained by photographing a light source at a first sampling rate from a first image sensor; and
outputting, by a demodulation unit, restored data of a first data rate based on the images,
wherein the first data rate is half of the first sampling rate, and the outputting of the restored data of the first data rate comprises comparing flashing states of the light source with respect to two consecutive images, and outputting a binary value identical to or opposite to a previous value of the restored data as a next value of the restored data.