rakesh krishna

—In this paper, a simple hybrid radio-over fiber network that can transmit a different quadrature amplitude modulated (QAM) signals simultaneously over a 50-km fiber link is investigated. Simulation results indicate that a maximum of 162 Mbps-64QAM and 108 Mbps-16QAM signals can be sent simultaneously using Optical Single Side Band (OSSB) generation technique without any dispersion compensation. The proposed dual carrier multiplexing (DCM) architecture may be used for the multi-service transmission in heterogeneous networks. In presence of centralized control and processing, subcarrier multiplexing (SCM) techniques over fiber may provide economical and protocol-transparent solutions for the next-generation hybrid networks.

—The paper proposes a 720 Mbps visible light communication (VLC) system using 64-QAM-OFDM signals. Transmission of signals is achieved by modulating red, green and blue (RGB) light emitting diodes (LEDs) and transmitting all three wavelengths over free space optical (FSO) channel after subcarrier multiplexing (SCM) of 64-QAM-OFDM signals on two RF carriers. The performance of the proposed scheme is evaluated for a free space distance under the effect of weak as well as strong scintillations. Data transmission with bit error rates under pre-FEC limit (3.8x10-3) is achieved up to 1.2 meters through the proposed VLC system.