Performance of MIMO-OFDM E-SDM systems using circular arrays

In the paper, performance of multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) eigenbeam-space division multiplexing (E-SDM) systems using uniform circular antenna arrays is evaluated. We conducted a MIMO channel measurement campaign at a 5.2 GHz frequency band in an indoor fading environment. Simulation results based on the measured data have shown that differently from the linear array, the BER performance of the circular array is almost the same for the array orientation. It is also shown that the performance can be degraded due to a channel change during the time delay between the transmit weight matrix determination and the actual data transmission. To compensate for the channel change, we have proposed two methods of channel extrapolation. Applying the proposed methods, robust performance can be obtained.