Downlink channel modeling for mobile communications with smart antennas at the base station

In this paper, an approach is presented to enable down-link channel modeling for mobile communication systems with smart antennas at the base station (BS). Based on the assumption that the angle of departure (AOD) at the BS is uniformly distributed, closed-form expressions are provided for the probability density function (PDF) of the azimuth angle of arrival (AOA), power spectral density (PSD) and temporal auto-correlation function (ACF), as seen from the mobile station (MS). Simulation results are hereby provided in order to verify the correctness of the derivations. For the proposed model, the level-crossing rate (LCR) and the average duration of fades (ADF) are investigated. All obtained results are also compared with those in case that the BS is equipped with an omnidirectional antenna. The numerical results show that the usage of a smart antenna at the BS will significantly reduce the LCR of the fading envelope, while the ADF increases significantly. Furthermore, an efficient deterministic simulation model is proposed to enable the emulation of the proposed channel model.