Reduction of Optical Background Noise Impact in Light-Emitting Diode (LED)-Based Optical Wireless Communication Systems by Hadamard Codes

Light-emitting diode (LED)-based Optical wireless communications is capable to provide ultracheap wireless communication for many applications, especially for the indoor applications, it can be used to provide flexible wireless communication system for data communication (to connect personal computers/laptops with printers, and digital imaging devices) or creating access points in the floors the LED-based optical wireless communication has many advantages over RF communications like lower system complexity, cheaper components, simple interfacing, and security. Besides these advantages, the LED optical wireless communications face many challenges for its implementation in indoor applications because of high interference from other light sources like florescent lamps, CFL's, which not only emits the light at same spectrum but may also use the switching frequencies (including harmonics) similar modulation frequencies. However, many solutions have been already presented to overcome these challenges. This paper provides the simple and efficient spectrum spreading approach which not only reduces the effect of interference but also enables multiuser communication without using modulating carrier. The simulation results shows that the proposed technique provides much better results than the Manchester coded systems.