Transmission of 2 bits/symbol over RoF and RoFSO links with different architectures for ubiquitous coverage

[EN] This paper investigates integrated radio-over-fiber and radio-over-free-space optic links in a passive optical network architecture for ubiquitous wireless coverage. Two optical millimeter-wave generation techniques, namely optical heterodyning and optical modulator-based up-conversion are used. In the first configuration, simulation results are achieved for transmission of 20-40 Gb/s 4-PAM over the 60 GHz heterodyned hybrid link. In the second configuration, transmission of 20 MHz 4-QAM over the up-converted 25 GHz hybrid system is examined. System performance evaluation and practical feasibility is carried out in terms of the received optical powers, bit error rates, eye diagrams, error vector magnitude and constellation diagrams.