Capacity enhancement and BER in a combined SDMA/TDMA system

This paper considers the performance of a TDMA system employing smart antennas at the base station. Two adaptation schemes are analyzed-the switched beam approach and an adaptive array based on an adaptation algorithm to maximize the Signal-to-Interference and Noise ratio. For an SDMA system the switched beam approach performs worse than the adaptive array. Adaptive arrays based on gradient-vector estimation (e.g. LMS) are not suitable for mobile radio. The class of Least Squares (LS, RLS, SQRLS) algorithms shows satisfactory performance. For a linear array with 8 elements a minimum angular separation of 10° between two users is sufficient for the adaptive array to achieve as good performance as a system serving one user per traffic channel