| Unlicensed millimeter-wave (mm-wave) band has been considered a potential wireless radio frequency (RF) carrier band for the future wireless communications. However, due to high attenuation of mm-wave signals in the air, the picocell base station (BS) has small coverage and many BSs have to be deployed to cover a large area. In this situation, it is necessary to minimize the cost of the BS and to shift the system complexity and expensive devices to the central station (CS). This can be achieved by implementing the radio over fiber (RoF) distribution scheme where the radio signals are generated at a CS and then distributed via a fiber link to a number of remote antenna BSs.;The objective of this thesis is to investigate and compare three modulation techniques for the generation of mm-wave using OFM with a dual-electrode Mach-Zehnder modulator (MZM), i.e., Technique-A, Technique-B and Technique-C. Specifically, we investigate frequency quadrupling using three optical modulation techniques. The quality of the generated mm-wave for this frequency quadrupler is evaluated in an RoF system considering the impact of modulation index, optical filter bandwidth, and modulation frequency of the RF signal that drives the MZM. The detailed theoretical analysis, experiment, and simulation verification of these techniques are also carried out. Moreover, Q-factor expressions are derived for the mm-wave RoF system using the three OFM techniques for mm-wave generation.;Then, a novel technique for the generation of mm-wave signal using frequency sixuplexing technique is also proposed and comprehensively compared with conventional technique, i.e., optical carrier suppression modulation. The proposed frequency sixupler technique leads to an improvement in receiver sensitivity compared to the conventional technique. Also, the concept proof of the proposed technique was verified by experiments.;Finally, the experimental setup to generate a 30 GHz of multiband orthogonal frequency division multiplexing (MB-OFDM) mm-wave signal transmitted over fiber was performed to validate the proposed techniques and verify the simulation results. The results show that the OFM technique, i.e., Technique-C, is a very promising solution for emerging and future OFDM mm-wave ultra-wideband communications.;Recently, optical mm-wave generation using optical frequency multiplication (OFM) has been adopted in RoF system to simplify the architecture of BSs and reduce the cost of the system. Unfortunately, the problem of how to effectively generate mm-wave signal using OFM with a simple configuration has not yet been well investigated. |
