Channel estimation algorithms for DS/BPSK-CDMA communications systems

Different channel estimation algorithms for direct-sequence code-division multiple-access (DS/CDMA) communications systems using binary phase-shift-keying (BPSK) modulation and a RAKE receiver are evaluated under fading multipath conditions. Two strategies are considered: the transmission of a pilot signal in the downlink and the block organization of the data in the uplink. The performance degradation of the system is due mainly to inaccurate estimation of the complex amplitudes rather than the delays; it remains low when using pilot signals with averaging filters or combining preamble information with symbol estimation.