Blind joint equalization and multiuser detection for DS-CDMA inunknown correlated noise

摘要

The problem of blind demodulation of multiuser information symbolsnin an asynchronous multipath CDMA network in the presence ofnmultiple-access interference (MAI), intersymbol interference (ISI), andnambient channel noise is considered. First, a discrete-time signal modelnfor a multipath code-division multiple-access channel is developed,nbased upon which several linear receiver structures are defined. Blindnchannel-estimation methods exploiting the orthogonality between thensignal and noise subspaces are then discussed. In particular, channelnestimation in the presence of unknown correlated noise is considered. Itnis assumed that the receiver employs two well-separated antennas, suchnthat the noise is spatially uncorrelated. Two subspace methods fornestimating the channel response are examined, based on, respectively,nthe singular value decomposition (SVD) and the canonical correlationndecomposition (CCD) of the cross-correlation matrix of the signalsnreceived by the two antennas. Simulation results show that the CCD-basednmethod substantially outperforms the SVD-based method