基于四倍频矢量信号和波长重用的双向光载无线系统

Bidirectional Radio over Fiber System Based on Frequency-Quadrupled Vector Signal and Wavelength Reuse

为提高光载无线(RoF)系统传输容量,提出了一种基于四倍频矢量信号生成及波长重用技术的双向RoF传输系统。该系统中,下行链路由基于受激布里渊散射效应的窄带光带阻滤波器和Sagnac环在光域实现四倍频矢量信号调制;在基站端,未调制的边带由检偏器滤出作为上行链路光载波实现波长重用。传输实验验证了24 GHz的四倍频正交相移键控(QPSK)信号的拍频产生,并测试了码率为400 Mbit/s的8 GHz下行频带QPSK和400 Mbit/s的上行基带开关键控(OOK)信号的6.15 km光纤传输。实验结果验证了该系统的可行性。

In order to improve the transmission capacity of the radio over fiber （RoF） system, a bidirectional RoF transmission system is proposed based on the generation of frequency quadrupled vector signal and wavelength reuse technique. For the downlink transmission, a stimulated Brillouin scattering-assisted narrow-band optical notch filter and a Sagnac loop are employed to generate a frequency-quadrupled vector signal directly in optical domain. At the base station, the unmodulated sideband of the downlink signal is filtered out by a polarizer and reused as the uplink optical carrier to achieve wavelength reuse. In the experiment, a quadrature phase shift keying （QPSK） signal centered at 24 GHz is generated by frequency beating. A 400 Mbit/s downlink QPSK signal at 8 GHz and a 400 Mbit/s baseband on-off keying （OOK） signal as uplink are used to evaluate the system performance over a 6.15 km fiber link. The feasibility of the proposed system is confirmed by the experimental result.