Hybrid modulation scheme for indoor image sensor communication system using smartphone and LEDs

Abstract

This paper shows a layout for a newly proposed hybrid modulation scheme for image sensor communication, especially for indoor image sensor communication using smartphone and LEDs. The proposed system infers compatibility support for frame rate variation too whereas the compatibility is performed by inserting asynchronous data bit with the original data bit. We propose the modulation scheme considering both frequency domain and phase domain of the communication signal. The scheme contains M-FSK and N-PSK schemes where M and N stand for the number of frequencies and the number of phases, respectively. The M-FSK scheme, a scheme for sharing frequency bandwidth to multiple transmitters, can be useful for rolling shutter cameras while most of the smartphones use rolling shutter functionality for the camera. The N-PSK (only 2-PSK is discussed in the work) method is applied along with M-PSK scheme to achieve higher data rate as well far distant transmission. The higher data rate is very supportive of bringing compatibility in case frame rate variation because the use of asynchronous bit causes a decline in data rate.