Multiple-input multiple-output (MIMO) radio channel measurements

In this paper we present results from the first field test to characterize the mobile multiple-input multiple-output (MIMO) radio channel. We measured the capacity, normalized to a single antenna system and fading correlation between antennas of a system with 4 antennas on a laptop computer and 4 antennas at a rooftop base station. The field test results show that close to the theoretical 4 times the capacity of a single antenna system can be supported in a 30 kHz channel with dual-polarized, spatially-separated base station and terminal antennas. For this 4x4 MIMO system the degradation in capacity due to fading correlation is small even with correlation coefficients as high as 0.5. Close to the theoretical 4 times capacity was achieved under a variety of test runs, including suburban drives, highway drives, and pedestrian routes, bath close to the base station and inside a house a few miles from the base station. Therefore, these results show that it may be possible to provide in excess of 1 Mbps in a 200 kHz mobile radio channel (for the SG wireless TDMA system EDGE) with the appropriate base station antennas.