Influence of Non-Reciprocal Transceivers at 2.4 GHz in Adaptive MIMO-OFDM Systems

In this paper, the impact of nonreciprocal transceivers is demonstrated by measurement results for different adaptive transmission strategies in a time division duplex MIMO-OFDM system. These strategies rely on the channel state information (CSI) at the transmitter, thus requiring either appropriate feedback or reciprocity of both communication links. The measurements were performed for point-to-point communication applying a bit and power loading algorithm. Furthermore, a point-tomultipoint scenario with zero forcing pre-equalization is considered. For both scenarios, equalization at the receiver is mandatory for imperfect CSI at the transmitter. To quantify the influence of the nonreciprocal transceivers on data transmission, the bit error rate determined by using the CSI obtained via the reverse link is compared with the bit error rate achieved by using perfectly fed back CSI of the forward link.