Effect of angle spread on system capacity in DS/CDMA cellular system using adaptive array antenna

This paper evaluates the effect of angle spread on the system capacity for a DS/CDMA system using a delay profile measurement based adaptive array antenna combined with beam pattern selection diversity and carrier-to-interference plus noise (CINR) based transmit power control (TPC) techniques. In the proposed system, beam directivity is controlled by the delay profiles for each terminal measured in each antenna element. Moreover, to reduce the number of computation for the beam directivity control, the proposed system calculates the optimum beam directivity for only a limited number of terminals that locates far from the base station, and signals from the rest of the terminals are demodulated by selecting one of the most reliable adaptive array combined signals. This technique is called beam pattern diversity. For the evaluation of impact of the angle spread of the multipath components on the capacity of DS/CDMA systems with an adaptive array antenna, computer simulation is conducted. The results show that the proposed scheme gives better performance than the sector antenna systems under practical angle spread conditions; i.e. less than 10 degree, with relatively a small number of computation