Performance Analysis and Link Design of Long Haul Coherent Optical OFDM Systems

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is a suitable solution due to its many advantages known in wireless communications. On the other hand, optical communications is also used as a backbone to transmit and receive large data rates with economical and good performance. Recently, fiber optical communication and OFDM method are combined to obtain both advantages in a communication link. Coherent optical OFDM (CO-OFDM) has recently been proposed against the chromatic dispersion effect in electrical domain. According to the ITU-T standards there are 111 channels (C and L bands) can be used (191.4 to 185.9 THz) at 50 GHz spacing. Thanks to Wavelength Division Multiplexing, even we use only one RF carrier, we can reach 1.7 Tb/s (111'16 Gb/s) using only one optical cable and utilizing C and L bands. In this research, CO-OFDM technique is modeled and simulated by designing a Monte Carlo simulation. In this simulation, dispersion, data rate, SNR-BER and BER-Distance variations are calculated and results are given in graphical forms. These graphics show the performance of the CO-OFDM system in 5, 8 and 16 Gb/s at different distances for one RF carrier and one optical carrier. It is also shown that how to get 64 Gb/s data rate using the same structure with one optical carrier.