Simulative Performance Analysis Of Radio Over Fiber Systems In Broadband Access Networks

The 21st century is a new era of information technology. With the rapid development of information, communication is playing a more and more important role in our society. Now as the requirements for high-speed multimedia mobile services are increasing, the broadband transmission capacity is stressing the wireless communication systems. How to resolve the issues of wireless high-speed data transmission and radio access coverage span becomes an exigent and key problem. On the other hand, the fiber communication systems have advantages of anti-electromagnetic interference, low-less and high-bandwidth.Radio-over-Fiber (RoF), which responds to meet the requirements of high-speed and large-capacity in radio communication systems, is a newly emerged radio access technology. It helps to construct wired and wireless integrated access networks, and thus listed as one of the most promising schemes to solve problems aforementioned. In RoF systems, radio signal is transmitted over optical carriers in the fiber between base stations and center stations, and the influences of non-linearity and fiber dispersion on its transmission performance are the major problems to be resolved.Consequently, the performances of RoF system for access networks with direct modulation and external modulation are theoretically analyzed. The performance of RoF system with several directly modulations is studied. Furthermore, advices on system design and optimization are provided. The work and the contributions are outlined as follows.(1) RoF technologies, including operation principles, technical classification, current status, technical features and main applications are extensively and systematically investigated. (2) The RoF system structures with direct modulation and external modulation are presented in detail, and the performances of both systems are analyzed theoretically. Besides, key factors which may affect the system performance are identified.(3) A simulation platform is constructed. The system performance with directly modulation is evaluated, in case of typical modulations, such as xPSK, xQAM and OFDM. The BER, the spectra and the signal constellation are given. Several comments on system design and optimization are provided.