Channel Identifiability for Blind Subspace-Based Channel Estimator in Uplink MC-CDMA Systems
Lokesh Bheema Thiagarajan, Samir Attallah, Ying‐Chang Liang, Karim Abed‐Meraim · 2008
Subspace-based channel impulse response (CIR) estimators have been proposed for multi carrier code division multiple access (MC-CDMA) systems. Channel identifiability conditions have been formulated for blind (non-data-aided) CIR estimators. These identifiability conditions require the channel filtering matrix to satisfy certain rank conditions. In this paper, the generalized uplink MC-CDMA system model is analyzed in detail. It will be shown that each user's signal subspace dimensionality is independent of the user's spreading code and CIR. Furthermore, for any realization of the users' CIR, the channel identifiability is established by only imposing a simple rank condition on the users' spreading codes.