Spatial and Temporal Variations of MIMO Channels and Impacts on Capacity

This paper presents analysis for spatial and temporal variations of multiple-input-multiple-output (MIMO) channels at the mobile. The channel study is based on the narrowband measurements at 2.11 GHz in Manhattan, New York with 16 transmitting antennas and 16 receiving antennas. Doppler spread and angle of arrival (AOA) are derived from the temporal correlation of field components. Results show that the AOA at the mobile is not uniformly distributed. The restricted AOA distribution results in approximately twice of correlation distance and correlation time than the predicted values from the Jakes model. The measured median coherence time is at least a few seconds for stationary channels, and 90 ms at mobile pedestrian speed of 3 km/hr. These observations hold for both vertically and horizontally polarized antennas. The measured median rms angular spread at the mobile is 22.5degrees for horizontally polarized antennas and 25.5degrees for vertically polarized antennas.