Investigation of Channel Estimation Method for Adaptive Antenna Array Transmit Diversity in W-CDMA Forward Link

摘要

This paper investigates an accurate channel estimation method using the common pilot channel (CPICH) in addition to a dedicated pilot channel (PICK) when the fading correlation between the dedicated PICH and CPICH is high, and clarifies the area in which the proposed channel estimation method is effective for adaptive antenna array transmit diversity (AAA-TD) in the forward link. Computer simulation results elucidate that although a more precise channel estimation is possible by using the primary-CPICH (P-CPICH) transmitted from an omni-directional antenna in addition to the dedicated PICH for the area where the distance, d, between a base station and a mobile terminal is longer than approximately 200 m, no improvement is obtained for the area where the value of d is shorter than approximately 200m. Meanwhile, by employing the secondary-CPICH (S-CPICH) transmitted with several directional beams in addition to the dedicated PICH, the required average received E_b/N_0 at the average BER of 10~(-3) is decreased by approximately 0.4 (0.2-0.4) dB compared to the channel estimation method using only the dedicated PICH regardless of the value of d when the number of antennas is 4 (8).