A frequency error resistant blind interference-mitigating CDMA detector

Abstract

This paper presents an enhanced version of the previously-proposed blind adaptive interference detector (BAID) for direct-sequence code division multiple access (DS-CDMA) transmission. Such a new detector, named extended complex BAID (EC-BAID), reveals resistance to a possible large frequency shift (e.g., Doppler shift) on interfering carriers, and features invariance to the phase error on the useful channel's carrier. The EC-BAID is also shown to bear a sensitivity to residual carrier frequency errors on the desired channel which is lower by three orders of magnitude with respect to the data-aided minimum mean square error (DA-MMSE) receiver. The performance of the EC-BAID was numerically assessed by computer simulations and successfully compared to analytical findings under a variety of system configurations. It turned out that the EC-BAID, despite its blind operating mode, bears an uncoded symbol error rate (SER) performance that closely approaches the DA-MMSEs. Finally, a few implementation aspects of the new interference-mitigating detector are also discussed.