A Study of Dispersion Compensation of Polarization Multiplexing-Based OFDM-OCDMA for Radio-over-Fiber Transmissions

Abstract

Chromatic dispersion from optical fiber is the most important problem that produces temporal skews and destroys the rectangular structure of code patterns in the spectra-amplitude-coding-based optical code-division multiple-access (SAC-OCDMA) system. Thus, the balance detection scheme does not work perfectly to cancel multiple access interference (MAI) and the system performance will be degraded. Orthogonal frequency-division multiplexing (OFDM) is the fastest developing technology in the academic and industrial fields of wireless transmission. In this study, the radio-over-fiber system is realized by integrating OFDM and OCDMA via polarization multiplexing scheme. The electronic dispersion compensation (EDC) equalizer element of OFDM integrated with the dispersion compensation fiber (DCF) is used in the proposed radio-over-fiber (RoF) system, which can efficiently suppress the chromatic dispersion influence in long-haul transmitted distance. A set of length differences for 10 km-long single-mode fiber (SMF) and 4 km-long DCF is to verify the compensation scheme by relative equalizer algorithms and constellation diagrams. In the simulation result, the proposed dispersion mechanism successfully compensates the dispersion from SMF and the system performance with dispersion equalizer is highly improved.

Quadrature amplitude modulation frequency up- and down-conversions using a positive-intrinsic-negative photodiode sampling mixer

“…Thus, frequency mixing can be obtained as a result of the PD nonlinearity when injecting a local oscillator (LO) signal at its electrical port and simultaneously illuminating it with an optical signal. 4 Electro-optical up converters at BSs can be used to solve the trouble of the chromatic dispersion 5 of the optical fiber, which extremely limits the transmission distance. In this case, the data transmission of intermediate frequency (IF) is <1 GHz and an LO signal is much higher than the IF frequency (Fig.…”

“…Electro-optical up converters at BSs can be used to solve the trouble of the chromatic dispersion 5 of the optical fiber, which extremely limits the transmission distance. In this case, the data transmission of intermediate frequency (IF) is <1 GHz and an LO signal is much higher than the IF frequency (Fig.…”