EXTERNAL MODULATION SCHEMES IN OFDM-ROF LINKS

Intensity modulation plays a significant role in the transmission of millimeter (mm) waves through Radio-over-fiber (RoF) links. Robustness against multipath fading and feasibility of multi-level format can be introduced into RoF links by the use of Orthogonal Frequency Division Multiplexing (OFDM). In this paper the basic principles and performance analysis of the different external intensity moulation schemes in OFDM-Rof links, using Electro-optic modulator (EOM) and Electro-absorption modulator (EAM) are described. Both the external modulation schemes are simulated for a vector modulation format, i.e., the quadrature amplitude modulation (QAM), where an OFDM scheme is used to generate signal subcarriers. The simulations for both schemes are executed with the same values of common global parameters.