Research On The Technology Of WDM-PON Compatible With Radio-Over-Fiber System

With the development of information technology, the next generation access network is committed to providing multiple broadband services for lots of users in an efficient way. WDM-PON (Wavelength Division Multiplexing Passive Optical Network) is an optical access network which has large capacity and high security. The ROF (Radio-Over-Fiber) technology is considered to be an ideal broadband wireless access which can reduce operating costs. The OFDM (Orthogonal Frequency Division Multiplexing) technology can be utilized in the optical communication for dispersion compensation and long distance transmission. WDM-PON compatible with ROF system is the trend in the future all-optical network. WDM-PON compatible with ROF system carrying OFDM signals for overcoming the fiber dispersion, providing wired and wireless services for many users and realizing wavelength reuse in the base station simultaneously that is investigated in the thesis. The results obtained are as follows:Firstly, a scheme of WDM-PON compatible with ROF system employing subcarrier modulation to generate 60GHz optical millimeter-wave that is proposed and demonstrated by simulation. After 60km SMF (Single Mode Fiber) transmission, dowmstream OFDM wireless link data can be basically retrieved, and the constellation figures of downstream OFDM wired link data and eye diagrams of upstream OOK (On-Off Keying) signals are all pretty well.Secondly, in order to further reduce the cost of system, a scheme of WDM-PON compatible with 60GHz ROF system employing a intensity modulator and an optical IL (Interleaver) to realize quadruple frequency modulation that is proposed.2.5Gb/s downstream OFDM wireless link data, wired link data and upstream OOK signals can be successfully transmitted 60km SMF that is demonstrated by system simulation.Thirdly, a WDM-ROF (Wavelength Division Multiplexing Radio-Over-Fiber) system to generate 58GHz optical millimeter-wave with OFDM signal by using a Mach-Zehnder intensity modulator and an IL that is experimentally investigated. In the central office, four channels continuous wave lightwaves are generated by a laser array, and they are modulated by a intensity modulator which is driven by a 29GHz radio frequency signal to realize DSB (Double Sideband) modulation.2.5Gb/s OFDM signals are modulated on the DSB signals by another intensity modulator before they are transmitted to the base station over 20km SMF. In the base station, an optical IL is used to separated optical carriers and first order sidebands. The first order sidebands of desired channel are selected by a tunable optical filter and detected by a high speed optoelectronic detector to generate 58GHz electrical millimeter-wave which is demodulated by coherent demodulation to retrieve downstream OFDM baseband signals. The experimental results show that the power penalty of the downstream OFDM signals transmitted over 20km SMF is less than 0.5dB at the bit error rate of 10-3 and without dispersion compensation, and the constellation figures are still clear.