Improved CDMA multiuser receivers robust to timing errors

We investigate an improved multiuser detector for asynchronous CDMA uplink channels when there exist timing delay estimation errors. We first formulate a robust decorrelating detector with a capacity limit of 50%. To increase the system capacity, we further propose a robust successive interference cancellation (SIC) implementation. The proposed robust SIC detector adds only a residual error estimation procedure onto the standard SIC detector. Computer simulation results show that its performance and capacity are very close to those of the ideal decorrelating detector which assumes perfect knowledge of time delay.