Look-up table based adaptive predistortion for dynamic range enhancement in a radio over fiber link

The biggest limitation of radio over fiber (ROF) links in a microcellular environment is the limited dynamic range (DR) due to laser nonlinearity. In this paper for the first time, a look-up table based adaptive predistortion scheme is proposed to enhance the ROF link linearity. An adaptive filter trains itself to generate table entries and no prior knowledge of link physical parameters is needed. When data is transmitted, each symbol is pre-distorted at the symbol rate to compensate channel distortion. Experimental and simulation results show excellent performance improvement. The power handling capability of the laser diode is the upper limit. This scheme can be further simplified if limited AM-AM distortion is allowed which does not significantly contribute to system degradation