Weighted gradient VFF-RLS based-time domain iterative channel estimation for MC-IDMA systems

Abstract

This paper presents a new adaptive algorithm for implementation of channel estimation in a multiuser based Multicarrier-Interleave Division Multiple Access (MC-IDMA wireless communication systems. The proposed estimator is based on the modified version of adaptive recursive least square algorithm. A new variable forgetting factor procedure is developed for the RLS algorithm by differentiating a cost function upon which a noise variance weighting factor has been applied. The developed channel estimator is named weighted gradient variable forgetting factor RLS (WGVFF-RLS)-based channel estimator. Comparative performances of the proposed WGVFF-RLS-based channel estimator and some earlier proposed channel estimators: the least mean square (LMS)-based channel estimator, the VFFRLS-based estimator and the combined channel transfer function (CTF)-estimator and CIR predictor are obtained through computer simulations. The achievable performances of these estimators are documented in the context of the channel that is experiencing both slow and fast fading phenomenon for MC-IDMA system. The results show that the proposed WGVFF-RLS-based channel estimator exhibits improved performance than the other estimators, though with high penalty in terms of computational complexity.