Semi Blind Estimation for Multiuser MIMO Channel Using Orthogonal Space Time Block Coding

The problem of estimating the Channel State Information (CSI) of several transmitters that communicate with a single receiver is considered. These transmitters communicate with the receiver using Orthogonal Space Time Block Codes (OSTBCs) method. Based on Rank Revealing LU (RRLU) factorization a novel algorithm to estimate multiuser MIMO channels is proposed. The algorithm estimates the null space of the subspace spanned by the user channels using only a few training blocks to extract the users CSI from this subspace.