光载无线系统中多路高纯度本振的远程传送

Generating and Delivering Multi-Channel Local Oscillation Signals with High Purity in Radio-over-Fiber System Remotely

针对光载无线技术在宽带无线网络中应用时.由于宽带无线网络的多标准共存所导致的基站本振频率多样性问题,提出在中心站利用光相位调制器和周期带通滤波器同时产生和远程传送多路不同频率的本振,从而使多类基站共享一个中心站本振源的方案。理论分析了该方案产生本振的频率大小和谱线宽度,用一个6.4 GHz的低频信号仿真实现了19.2 GHz,25.6 GHz和38.4 GHz等多路本振的同时产生。理论与仿真结果均表明本振的纯度很高,并且不受光源线宽的影响。提出了一种双向传输系统,可很好地解决标准的兼容性,减小色散的影响,提高传输容量,并大大降低系统的成本。

Radio-over-fiber system has a broad prospect in broadband wireless communication networks. Due to the coexistence of multiple standards of broadband wireless communication networks, the frequency of local oscillation signal used in base station is different from each other. A novel scheme is presented to generate and deliver multi- channel local oscillation signals simultaneously and remotely by making use of an optical phase modulator and an optical periodic band-pass filter in central station. The single local oscillation system in central station can be shared by a number of base stations which belong to several standards. The frequency and the line width of local oscillation signal is analyzed theoretically. The simulation to generate and deliver multi-channel local oscillation signals such as 19.2 GHz, 25.6 GHz and 38.4 GHz simultaneously with an single electrical drive signal operating at frequency of 6. 4 GHz is performed. The theoretical analysis and simulation results both show that local oscillation signals have very high purity, and the purity is not affected by the line width of the source. Then a bi-directional scheme is proposed. In such scheme, the compatibility of multiple standards can be solved very well. The chromatic dispersion and the cost can be reduced extremely. In addition, the capacity of system could be enlarged.