Performance of multiuser detection with decision-directed channel estimation

In this paper, we study the performance of a general linear coherent multiuser receiver with decision-directed channel estimation (DDCE) for doubly-selective Rician-fading CDMA channels. Employing the multivariate Gaussian approximation (MGA) and a decision variable-based moment generating function (DV-MGF) approach, both exact and low-complexity approximate bit error probability (BEP) formulas for a linear detector with genie-aided DDCE are provided. Furthermore, using a Markov chain steady-state analysis, a tight BEP approximation for non-ideal DDCE is provided taking into account the error propagation in the decision feedback. Some new findings are illustrated by simulation results.