caption: System level issues -- optimum use of multiple antennas Multiple antenna usage is not new in mobile systems: Spatial diversity systems Different goals: Beamforming is optimum using a large number of closely spaced antennas: --Directional beamforming imposes stringent limits on spacing, typically a half wavelength --Best performance in line-of-sight (LOS) MIMO algorithms focusses on diversity or data rate maximization: --Antennas will use as much space as possible to realize decorrelation between antennas --Turning rich multipath into an advantage and lose the gain in LOS cases
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