Investigation on Transport Schemes for Efficient High-Frequency Broadband OFDM Transmission in Fibre-Wireless Links

This paper investigates the different transport schemes for delivery of high-frequency broadband OFDM signals via fibre-wireless links. We have investigated analog RoF, digitized RoF, and sampled RoF transport schemes and experimentally demonstrated the transmission of broadband RF-OFDM signal using these schemes. Analog RoF results in the simplest BS/RRH configuration but it demands for large optical bandwidth. The performance of this transport scheme is limited by inter-modulation distortion (IMD) and RF power fading. For the digitized RoF transport scheme based on bandpass sampling, although digital optical link is used for signal delivery, the performance is limited by signal clipping and ADC resolution. The sampled RoF transport scheme requires only a narrow optical bandwidth, but the performance is limited by IMD and noise processes introduced by bandpass sampling. Based on our analysis and experimental results, a design guide of fibre-wireless integration system for broadband RF-OFDM transmission is provided. It is found that: analog RoF is best suitable for short-range transmission; digitized RoF has the best performance; and sampled RoF offers a low-cost solution.