Connections between OSTBC and MIMO BF in General Fading Channels

The paper establishes connections between orthogonal space-time block codes (OSTBC) and multiple-input multiple-output beamforming (MIMO BF). Different from previous work, where the two schemes were studied independently and under specific fading conditions, we consider a framework which unifies the analysis of both schemes in arbitrary fading. In particular, we demonstrate that the diversity gains of OSTBC and MIMO BF are equivalent, regardless of the underlying channel fading distribution. We also derive bounds on the difference in transmit power required for the two schemes to achieve the same outage probability. This result, which again applies for arbitrary fading, quantifies the gain of MIMO BF over OSTBC due to the presence of transmitter channel knowledge.