An Experimental 8x8 System Used to Characterize the Spatial Channel at 3.5 GHz

Motorola Labs has developed a 20 MHz experimental wide-area mobile multi-antenna system with which to characterize the spatial channel. This system transmits OFDM waveforms from an eight-element array in each of three sectors at the base to an eight-element mobile receive array. In addition, two carrier frequencies are simultaneously transmitted and received, thus providing both FDD and TDD data. The received waveforms are post-processed to extract various channel characteristics such as time of arrivals (TOAs), Doppler frequencies (DFs), and directions of departure (DODs) at the base. This paper describes key components and parameters of this system and describes the spatial characteristics uncovered from the collected field data.