A distributed bidirectional wideband MIMO channel souder

In this paper, we present a wideband distributed bidirectional multiple-input - multiple-output (MIMO) channel sounder. It is developed for characterizing up to 4×4 MIMO channel in four frequency bands from 2GHz to 15GHz with 100MHz bandwidth. To fully understand the dynamic characteristics of multilink MIMO, such as distributed and cooperative MIMO, the radio over fiber (RoF) techniques is adopted. Furthermore, the channel sounder does not suffer from the deficiencies of “virtual antenna” measurement systems because of its parallel multi-channels. The hardware and signal frame structure are designed to support bidirectional measurement, which could achieve the real-time channel reciprocity. Finally, system calibration and performance analyses are presented.