Performance Bounds Analysis for Semi-Blind Channel Estimation with Pilot Contamination in Massive MIMO-OFDM Systems

Pilot contamination, in a massive Multiple-Input Multiple-Output (MIMO) system, is an undeniable challenging issue severely affecting the performance of the system by including channel estimation errors. The aim of this paper is to investigate the effectiveness of semi-blind channel estimation approaches in massive MIMO-OFDM (Orthogonal-Frequency Division-Multiplexing) systems. For an estimator-independent study, the performance analysis is carried out using the Cramer Rao Bound (CRB) derivation for pilot-based and semi-blind channel estimation strategies. This analysis demonstrates in particular that: (i) when considering the finite alphabet nature of communication signals, it is possible to efficiently solve the pilot contamination problem with semi-blind channel estimation approach; and (ii) the Second Order Statistics (SOS) only are not sufficient to address the full channel identifiability even if the semi-blind approach is considered.