Indoor ultra wide band channel sounding using multiple antennas

Inter-symbol interference (ISI) and correlation are the major problem in high data rates mobile communication using spatial diversity. Measurements were done to determine the spatial correlation and the time delays in an indoor environment. The frequency band was 2 to 4 GHz. The frequency-domain measurements were converted to the time-domain through the inverse Fourier transform (IFT) giving impulse responses. The time delays were extracted from the impulse responses. The largest peak of the impulse response was argued to determine the ISI. The time delay is found to be between 10 to 13 % of a bit period. A virtual array was used at the receive side with spatial resolution of 5 cm. The spatial autocorrelation is determined by calculating the correlation between positions on the array. Two receive antennas were also measured simultaneously on the receive side to determine the cross correlation to validate the autocorrelation results. It is found that the autocorrelation and cross correlation gave comparable results.