Evaluation of spatially selective receiving/transmission techniques for a smart antenna system operating at 1.8 GHz in non-stationary scenarios

It has been demonstrated that when the mobile terminal (MT) is stationary or moving at a very low speed, the uplink spatial signature of the MT is stable enough and can be used as a downlink weight vector in time-division-duplex (TDD) smart antenna systems. However, when the terminal is moving at a relatively high speed, the Doppler effect can cause the spatial signature to change quickly. In order to understand the effects of fast moving MT on spatial signatures, experiments are conducted using a 1.8 GHz real-time smart antenna testbed with a uniform circular array. When the MT moves within 50 milliseconds, those parameters such as spatial signatures and direction-of-arrivals (DOAs) are presented, and variation of uplink spatial signatures relative to downlink spatial signatures are analyzed