Performance Optimization In Radio Over Fiber System Based On OFDM Signal

With the rapid development of the intelligent mobile terminal, such as the smart-phone, tablets, wearable devices, and automotive wireless, the terminal business grows fast. The requirement of the bandwidth of the mobile communication system is higher than before. Technology of 4G has used in business. The research of the next generation technology of broadband wireless develops rapidly. The system of OFDM-ROF has some advantage, such as large capacity, high spectrum efficiency, bandwidth dispersion, low cost, Which has been one of the next generation technologies of broadband wireless.The system of ROF has advantages such as large bandwidth capacity, low transmission loss. OFDM has high bandwidth utilization, dispersion resistance, which has been used in digital video broadcasting, digital audio broadcasting and 802.11 wireless LAN. The study of OFDM in ROF technology has practical significance.This paper introduces the research of ROF technology and OFDM technology, as well as the combination of OFDM technology and ROF technology research, n this paper, the main research contents and research results as follows:(1) The theoretical basis and the key technology of ROF and OFDM technology are introduced. A ROF system is designed by phase modulator used to produce high power millimeter. In central station of this system, four parallel phase modulator to produce high frequency millimeter wave. When the phase bias of phase modulator is Acp= 1092°, the system can produce 12 times millimeter wave frequency. When the input frequency is 5GHz, the system can produce 60GHz millimeter wave. Through the simulation analysis of the system, the ROF system has the feasibility.This paper studies the PAPR of OFDM signal on the OFDM-ROF system. Through the analysis and compare of several methods used to reduce PAPR value, this paper chooses the selective mapping to reduce the PAPR value. Aiming at the problems of the SLM method, this paper put forward some improvement methods. The main idea of this method is to change the value of the specific sequences. The sideband information can be inserted into the signal by changing the mould, then to avoid the direct sideband information transmission. The simulation shows the method can reduce the value of PAPR.Based on the study of improvement on ROF and OFDM technology, this paper uses the Optisystem software to simulate the system. Through the analysis of experimental results, the improved selective mapping reduces the value of PAPR, the system BER become better, the constellation graph display is also improved. So the OFDM-ROF system performance is improved.