Regularized weighted gradient VFFRLS algorithm-based CSI Estimator for OFDM-IDMA Systems

Channel state information (CSI) estimation with the aid of regularized algorithm developed and proposed for the Orthogonal Frequency Division Multiplexing - Interleave Division Multiple Access (OFDM -IDMA) system is the focus of this paper. The developed estimator is referred to as regularized weighted gradient variable forgetting factor recursive least square (RWGVFFRLS)-based channel estimator. The development of the estimator is based on a weighted RLS algorithm that minimizes a weighted cost function. The criterion for the VFF is achieved by obtaining the gradient of the weighted cost function of the conventional RLS algorithm. The overall expression for the RWGVFFRLS-based estimator is obtained by applying weighted convex l(1) norm to the corresponding cost function of the WGVFFRLS algorithm. Based on the simulations performed, the developed RWGVFFRLS-based estimator shows superior performances in comparison with the other channel estimators considered in this paper, however with a slightly higher computational complexity in comparison with the other estimators that show close performances.