International Journal of Electrical and Computing Engineering Vol. 1, Issue. 1, July – 2014 ISSN (Online): 2349-8218 Mitigating Effect of Flickering & Dimming in Visible Light Communication Using MIMO A. Suban [1] , P. Prabu [2] , R. Manikandan [3] , M. Pradeep [4] Assistant professor, Dept of ECE, Velammal College of Engineering and Technology, Madurai [2] PG student, Dept of CSE, Indian Institute of Information Technology, Trichy [3] Project Engineer, WIPRO Lmited, Chennai, [4] Lecturer, Nagasiva Polytechnique College Abstract— Visible Light Communication (VLC) refers to short-range optical wireless communication using visible light spectrum from 380 to 780nm and it has many advantages such as it can provide a maximum speed of 10GB/S. The other advancement is that the bandwidth available for visible light communication is 300THz whereas it is below 6GHz on RF communication. The transmission of data in VLC is done with the intensity modulating optical source, such as light emitting diodes (LEDs) because of its energy efficiency and recent advancement in LED technology with fast nanoseconds switching time. This paper applies OPPM (Overlapping Pulse Position Modulation) to provide higher data rate during its transmission of digital data when we compared to other modulation techniques. The result shows that the best performance can be obtained using OPPM, making it an ideal modulation technique for future visible light communication. MATLAB and Lab View are the two methodologies we used for simulation purpose. Moreover Multiple Input Multiple Output (MIMO) techniques is potentially adopted for achieving high data rates. MATLAB Simulations are carried out and depicted. Index Terms— Visible light, White LED, On Off Keying, Variable Pulse Modulation, Overlapping Pulse Position Modulation. I. INTRODUCTION In the development of wireless communication system when the third generation mobile communication system is employed, manufacturers and the scientific group are increasingly turning their research interest towards future wireless communication system because traditional radio frequency (RF) communication below 6 GHz is rapidly running out of spectrum bandwidth for high data-rate communication. Visible Light Communication has recently been developed by scientists seeking to create an ultra-high speed, high security, biologically friendly communication networks Suban. A, Electronics & Communication Engineering, Velammal College of Engineering and Technology, Madurai Prabu.P, Computer Sceince & Engineering, Indian Institute of Information Technology Manikandan.R, Project Enineer, WIPRO Limited, Chennai. Pradeep.M, Electrical & Electronics Engineering, Nagasiva Polytechnique College, Madurai that allow the creation and expansion of continuous computing applications using very large bandwidth high- frequency pulsed light instead of radio waves and microwaves. Visible Light Communication (VLC) is the short-range optical wireless communication using the visible light spectrum from 380 to 780nm. With ~300 THz of bandwidth available for VLC, multi-gigabit-per second data rates could be provided over short distances. This wide spread of bandwidth removes one of the major difficulties faced by new communication schemes. Some of the noted advantages of visible light communication over RF (Radio Frequency) and IR (Infra- Red) based systems are:  Higher security than RF communication system.  No restriction on transmission power unlike in IR communication system.  No regulations in the use of the visible electromagnetic spectrum.  The key advantage of VLC is the duality in the use of the visible light. The same light that is used for the communication can also be used for illumination applications such as domestic light bulbs, LED TVs, and traffic lights. In an optical communication system, there is a possibility of modulating the transmitted optical signal in a variety of ways. The phase, frequency and the intensity of the optical signal can be modulated. VLC transmits data by the intensity modulating optical sources, such as light emitting diodes (LEDs) and laser diodes, because it is easy to implement and the optical output power is simply changed in accordance with the modulating signal. There has been renewed interest in visible light optical communication due to widespread deployment of LEDs for energy efficiency and recent advancements in LED technology with fast nanosecond switching times. Figure 1. An Alternate Technology-VLC 8