Practical Issues in the Combining of MIMO Techniques and RoF in OFDM/A Systems

In this paper, several multiple-input multiple-output (MIMO) techniques are studied for OFDM/A systems which have antennas connected to the base station with radio over fiber (RoF). The delay effects caused by the optical fibers on the fixed-beam transmit beamforming are studied via Monte Carlo simulations. Also the effect of combining RoF with other MIMO techniques in OFDM/A systems, like spatial multiplexing, space-time coding, and receiver beamforming, is discussed. The results indicate that for phase shift differences lower than those corresponding to a 1 m unevenness in the fiber’s length, RoF does not significantly decrease the performance of an OFDM/A system with fixed transmit beamforming, and with other MIMO techniques, the effect of employing RoF is negligible. Key-Words: Radio over Fiber, OFDMA, beamforming, MIMO, WiMAX