Robust channel estimation and detection for multicarrier CDMA

Multiuser detection (MUD) for code-division multiple-access (CDMA) systems usually relies on some prior estimates of the channel, obtained either blindly or by using training. However, channel estimates are always subject to estimation errors. In this paper, we present robust channel estimation and MUD techniques for multicarrier (MC) CDMA by explicitly taking into account prior channel estimation errors. Specifically, robust channel estimates and MUD receivers are obtained by optimizing the worst-case performance over a bounded uncertainty set. We show that although the prior channel estimation error is generally not bounded, it is beneficial to optimize the worst performance over a properly chosen bounded uncertainty set of the channel centered on the prior channel estimate. Numerical results show that our robust schemes yield improved performance over those that ignore the prior channel estimation error.