Joint delay tracking and interference cancellation in DS-CDMA systems using successive ICA for oversaturated data

Abstract

Recent studies have found successive interference cancellation (SIC) schemes employing blind source separation (BSS) methods to be promising competitors for conventional interference cancellation schemes in DS-CDMA systems. One reason for this is the inherent ability of BSS to mitigate many kinds of interference sources e.g. multi-access, multi-path and out-of-cell interferences. In addition, "more sources than observations"-problem can be somewhat circumvented by combining the SlC-ideology to BSS. Hence, BSS-SIC -type receivers can be used also in highly loaded systems where both conventional ICA and conventional interference cancellation usually fails. Recently proposed BSS-SIC receivers have needed accurate estimates for the user delays. This is mandatory for any interference canceller, since subtraction of a inaccurately estimated source from the original data actually enhances interference. In this paper we propose a scheme in which the ICA solution is used to tracking of users' delays, too, which helps to avoid the performance losses due to the inaccuracies in conventional delay tracking circuitry. © Springer-Verlag.