Wireless portable communications using pre-RAKE CDMA/TDD/QPSK systems with different combining techniques and imperfect channel estimation

摘要

This paper studies the use of pre-RAKE combining technique in code-division multiple-access (CDMA) systems with QPSK carrier modulation and time division duplex (TDD) in wide-band wireless portable communication systems. The system performance is analyzed in a generalized Rayleigh fading multipath channel. Our analysis is focused on two main issues. The first issue is comparing the various diversity techniques and studying the effect of the diversity order. Two diversity combining techniques, namely, maximal ratio combing (MRC) and equal gain combing (EGC) supplemented by a selection diversity for the strongest paths in gain are examined. The second considered issue is studying the effect of imperfect channel estimation on the system performance and comparing it with the ideal QPSK pre-RAKE system.