A subspace approach for blind estimation of time-varying channels under STBC transmissions

In this paper we consider the problem of blind estimation of time-varying multiple-input multiple-output (MIMO) channels under space-time block coded (STBC) transmissions. Firstly, the time-varying channel is deterministically represented by means of a basis expansion model (BEM), which reduces the number of parameters to be estimated. Secondly, the STBC structure is exploited to blindly recover the channel parameters by means of a subspace technique, which reduces to the solution of a generalized eigenvalue problem (GEV). Unlike previous approaches, the proposed method provides very accurate results even for non-orthogonal STBCs and high Doppler frequencies, which is illustrated by means of some numerical examples.