A weighted linear prediction approach for the blind CDMA forward link channel estimation

Blind channel estimation for periodic sequence DS-CDMA systems can be cast into the framework of “structured” blind estimation of multi-input/multi-output (MIMO) FIR systems, where the structure is imposed by the user´s signatures. The well known subspace method can in particular be adapted to this context, but it suffers from a lack of robustness to an over-determination of the order of the channel. In a previous work, we showed that the use a structured linear prediction approach can overcome this drawback. However, the statistical performance of the corresponding estimate are disappointing. In this paper, we concentrate on the forward link channel estimation, and propose to use a weighted linear prediction approach. The optimal weighting matrix is in practice quite difficult to use. We therefore propose a sub-optimum matrix, leading to a quite simple estimation algorithm, and which is shown to have optimum performance when the signal to noise ratio converges to +∞. Some simulation results confirm the potential of the new approach