We present an all-optical adaptive-antenna radio over fiber transport system that uses proven, commercially-available components to effectively deliver standard-compliant optical signaling to adaptive multiantenna arrays for current and emerging radio technology implementations. The system is based on a directly-modulated reflective emiconductor amplifier (R-SOA) and exploits the interplay between transmission-line dispersion and tunable optical filtering to achieve flexible true time delay, with $2pi$ beam steering at the different antennas. The system was characterized, then successfully tested with two types of signals defined in IEEE 802.16 (WiMAX) standard for wireless networks: a 90 Mbps single-carrier signal (64-QAM at 2.4 GHz) and a 78 Mbps multitone orthogonal frequency-division multiple access (OFDMA) signal. The power budget of this configuration supports a 4-element antenna array.
Prince, K., Presi, M., Chiuchiarelli, A., Cerutti, I., Contestabile, G., Tafur Monroy, I., & Ciaramella, E. C. (2009). Variable delay with directly-modulated R-SOA and optical filters for adaptive antenna radio-fiber access. Journal of Lightwave Technology, 27(22), 5056-5064. https://doi.org/10.1109/JLT.2009.2026491