Hadamard Coded Modulation for Optical Wireless Communication and Performance Analysis

A new method is proposed for optimizing the performance of Hadamard coded modulation (HCM)based systems in visible light communication. Prior to HCM, PSK was used in Wireless Optical Communication (WOC) for data modulation whereas HCM was used as precoder in PSK systems. But the constraint of optical sources used lead to signal distortion at the output. Hence HCM is used as an alternative technique for systems that require high average power. Here data is modulated using Fast Walsh Hadamard Transform. On-off keying (OOK) along with thresholding method is applied to the HCM system for improving its performance. Both the existing and modified system performance is evaluated in terms of various performance parameters. There are numerous modulation methods appropriate for optical wi-fi verbal exchange. OOK, PPM are adopted widely in optical wireless conversation foe its high average-strength-performance. DPPM, DPIM are new modulation techniques for optical wireless verbal exchange, which may be the substitutes of PPM due to their better performance in strength performance and bandwidth performance. On this system in mixture of the feature of the atmospheric optical VLC channel, the bandwidth efficiency, transmission capability, power efficiency and slot errors fee of the everyday modulation schemes as OOK, PPM, DPPM and DPIM for atmospheric optical wi-fi communications are analyzed. Theoretical evaluation and simulation outcomes by using MATLAB display that DPPM, DPIM and DH-PIM are extra relevant for the destiny optical wireless verbal exchange.