Coherent OFDM for Optical Communication Systems

Abstract

Orthogonal frequency division multiplexing (OFDM) has quickly gained its attraction in optical communications that are evolving towards software-enhanced optical transmissions. Coherent optical OFDM (CO-OFDM) takes advantage of software capabilities of electronic digital signal processing (DSP) to perform sophisticated operations and has demonstrated its easiness of realizing high spectral efficiency and combating various distortions at the same time. Coherent optical OFDM (CO-OFDM) has attracted lots of interest due to its high spectral efficiency (SE) and robustness to fiber dispersion and is considered as a promising candidate for long haul optical fiber transmission systems. In the beginning of this study, we will focus in (OFDM) theoretically with basic initial concepts, then a theoretical study of (CO-OFDM) and Direct detection (DD-OFDM) systems in deep with comparing between them, and identifying the advantages and disadvantages for both systems. Next, a practical study for the previous systems, by using (Optisystem), a special simulation program to simulate and analyze the system. This simulation we will simulate (CO-OFDM) for long-haul transmissions with its analysis such as optical signal to noise ratio (OSNR), RF spectrum, and constellation diagrams .In addition, we will simulate (DD-OFDM) with the same previous parameters and compare between the two systems .Then, we will compare (CO-OFDM) with dispersion compensating fiber (DCF) as a treatment to increase the transmission distance. Finally, we will integrate the wavelength division multiplexing system (WDM) with (CO-OFDM) system, to increase the system performance and achieve high data rates.