Antenna Multiplexing & Time Alignment for Mimo Channel Sounding

This paper addresses real-time multiple-input-multiple-output (MIMO) radio channel sounding. To avoid expensive transmitter-receiver chains antenna multiplexing is well suited for that application. However, the sequential measurement principle entails different time lags between the antenna channels. We show how the observed impulse responses can be aligned using classical interpolation methods as long as the Nyquist criterion with respect to the time variance of the measured mobile radio channel is met. This is important since the time lags, if neglected, may lead to wrong results e.g. in ESPRIT based parameter estimates.