Adaptive base station antenna configuration for street microcells considering propagation environment

An adaptive beamforming technique is an effective way to combat multipath waves which degrade the transmission quality of high speed wireless communication systems. An antenna using the beamforming technique adaptively directs the nulls of its radiation pattern to the multipath waves. However, it sometimes requires a number of elements to direct the main beam to the desired wave and to nullify the multipath waves. This increases the hardware complexity. This paper proposes a suitable configuration for an adaptive base station antenna employing a fewer number of elements than an conventional antenna array for a street microcell, a typical cell of a microcell mobile communication system. This configuration takes into consideration the propagation characteristics of multipath waves in this typical cell, a street cell. The appropriateness of the proposed configuration is evaluated by a bit error rate (BER) simulation using the measured propagation characteristics. This paper first describes the propagation characteristics of multipath waves measured in a Japanese suburban area. Then the antenna configuration is investigated in terms of the arrangement and element spacing employing omnidirectional elements. Finally, the effectiveness of bidirectional elements is described.