Jammer cancellation in DS-CDMA arrays: pre and post switching of ICA and RAKE

In this paper independent component analysis (ICA) is considered for blind interference cancellation in a direct sequence spread spectrum communication system utilizing antenna arrays. An ICA-assisted interference canceler was proposed by Ristaniemi, Raju and Karhunen (see Proc. IEEE Int. Conf. on Communications, New York, USA, April 2002). This receiver structure is an extension to the framework proposed by Belouchrani and Amin (see Signal Processing, vol.80, p.723-29, 2000), in which blind source separation (BSS) techniques were utilized to the jammer mitigation problem. A common feature for both is that they apply an advanced pre-processing tool to offer an unjammed signal for conventional detection. However, it is not always desirable to apply the pre-processing tool, since it might even cause additional interference if the jammer is weak or absent. What would make the receivers more practical is to switch the additional canceler active only whenever it is expected to improve conventional detection. We compare two possible switching strategies at both ends of the receiver chain, pre- and post-switching schemes, and evaluate their impacts to the overall performance improvement of the array receiver.