Hybrid Linearization of Broadband Radio-Over-Fiber Transmission

This letter presents analog and digital pre-distortion hybrid linearization of a broadband radio-over-fiber transmission system. Analog pre-distortion (APD) is used to mainly compensate for out-of-band nonlinear distortion, and digital predistortion (DPD) is used to mainly compensate for in-band nonlinear distortion and memory effect. Thus, by combining APD and DPD, all the quiescent distortions and memory effect can be suppressed effectively. The hybrid APD and DPD linearization is evaluated in three different scenarios: two 20-MHz long-term evolution (LTE) signals located at 800 and 900 MHz, and located at 800 and 840 MHz, and three 20-MHz LTE signals located at 800, 850, and 900 MHz. All three experiments show that the hybrid linearization results in better improvement in error vector magnitude, adjacent-channel power ratio, and third-order intermodulation distortion than the APD-only and DPD-only.