Experimental Results on Mobility Improvement Effects of Adaptive Antenna Arrays Applied to Mobile Stations in SDMA System

Space division multiple access (SDMA) technology attained increasing interest due to its ability to increase system capacity, and thereby to improve frequency usage efficiency. Especially in the Time Division Duplex (TDD) system, the SDMA system is simple due to the reciprocity of TDD channel. However in a fast fading environment, performance of the downlink transmission degrades significantly, since the adaptive control can not track fast changing channels due to the time difference between receive and transmit time slot. iBurst is a TDD broad band wireless communication system, which uses SDMA technology with its 12-element antenna array on the base station side to increase frequency usage efficiency. In this paper, a 2- element Adaptive Antenna Array was introduced into an iBurst mobile station and the field experiments were carried out. The field experiment results show that the performance degradation in fast fading channels is recovered and the mobility is enhanced.