Generalized Subspace-based Algorithms For Blind Channel Estimation In Cyclic Prefix Systems

Abstract

In this paper a novel generalization of subspace- based blind channel identification methods in cyclic prefix (CP) systems is proposed. For the generalization, a new system parameter called repetition index is introduced whose value is unity for previously reported special cases. By choosing a repetition index larger than unity, the number of received blocks needed for blind identification is significantly reduced compared to all previously reported methods. This feature makes it more realistic especially in wireless environments where the channel state is usually fast-varying. Given the number of received blocks available, the minimum value of repetition index is derived. Theoretical limit allows the proposed method to perform blind identification using only three received blocks. Simulation results not only demonstrate the capability of the algorithm to perform blind identification using fewer received blocks, but also show that in some cases system performance can be improved by choosing a repetition index larger than needed. If the number of received blocks and the repetition index are optimally chosen, the proposed method outperforms previously reported special cases, especially in time-varying channel environments.