| Summary: | 碩士 === 國立成功大學 === 電腦與通信工程研究所 === 103 === In recent years, the rapid growth of wireless access technology places a heavy burden on the already congested wireless spectrum. With the throughput of base station (BS) increases gradually, the construction based on optical fiber is required to provide broadband interconnections between the RBSs and central office (CO). This leads to the integration of the optical and wireless broadband infrastructures. The technique of modulating radio frequency (RF) signals onto an optical carrier is known as radio on fiber (RoF). And optical code-division multiple-access (OCDMA) is one of the multiplexing methods for RoF because it provide multiple users to access the network asynchronously without scheduling.
In this study, we propose a novel RoF system consisting of the wavelength reuse technique [7] with a broadband light source (BLS) to convey binary phase shift keying (BPSK) signals. To reduce system complexity, a part of wavelengths for downstream signals from CO is reused by BSs for upstream ones, so that the requirement for a high-quality optical source at BS is avoided. Besides, a simple power control scheme is adopted to support differentiated service in the proposed RoF system. To investigate the feasibility of the proposed system, we analyze the effects of thermal noise and phase-induced intensity noise (PIIN) through theory and simulation. BER performance of downlink and uplink are both demonstrated. The results prove that the differentiated BER achieved by the proposed power control scheme provides distinguish differentiated service provision for individual users.
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