Achieving directionality and transmit diversity via smart antenna pattern oscillation with a geometric-based stochastic channel model for coherence time evaluation

We develop a smart antenna with a controlled beam pattern oscillation, capable of providing both directionality and transmit diversity. Specifically, the antenna pattern directed toward the mobile user oscillates slightly, resulting in a time varying channel with a specific (small) coherence time: this small coherence time results in an exploitable time diversity. To evaluate the channel coherence time created via the proposed beam pattern oscillation, the time varying channel impulse response is simulated using a geometric-based stochastic channel model (GSCM). Assuming a mid-sized city center, coherence times are shown to correspond to 1/7/sup th/ the symbol duration, suggesting a 7-fold time diversity is available with the proposed antenna array-in addition to its directionality benefits.