Parallel-type coherent multistage interference canceller with multiple-antenna reception in DS-CDMA reverse link

This paper proposes a new parallel-type coherent multistage interference canceller (COMSIC) coupled with multiple-antenna reception (MA-COMSIC) and evaluates the capacity increase in a multipath fading channel in the DS-CDMA reverse link, in order to improve further the channel estimation accuracy and increase the space diversity effect. Simulation results show that the MA-COMSIC with a two block-wise antenna configuration, in which each block has 3 antennas (we denote as (B, D) = (2, 3)), achieved a lower required transmit E_b/N₀ than that with (B, D) = (1, 6) except for extreme cases such as when the number of simultaneous users K exceeds 120 corresponding to K/Pg = 250% (where Pg is the processing gain of 48 = 16×3). Consequently, even when K = 120, the increase in the required transmit E_b/N₀ of MA-COMSIC with (B, D) = (2, 3) from that in a single-user case is only 1.0 dB owing to the significant improvement in the channel estimation accompanied by the diversity effect. We also elucidate that even when the angle spread among constituent waves in the same path is σ_ΛS = 5 degrees, the loss of the required transmit E_b/N₀ with (B, D) = (2, 3) for the ideal fading correlation case is suppressed to within 0.5 dB