Multirate CDMA Receivers with Adaptive Antennas in Multipath Fading Channels

Smart antennas, with spatial processing, used in multirate code division multiple access (CDMA) systems can enhance range, reliability and capacity. In this paper, we propose three multirate methodologies, including variable processing gain, variable chip rate and multicode systems in adaptive antenna receiver structures for direct-sequence (DS) CDMA multiuser communications in multipath fading channels. Least mean square (LMS) algorithm is employed in narrowband and wideband receiver structures to adjust the spreading code coefficients. Simulation examples are given to compare the performances of the three proposed multirate receiver structures