Semi-blind channel estimation based on receiver diversity

This paper introduces a semi-blind channel estimation algorithm based on receiver diversity for Multiple Input Multiple Output (MIMO) systems using Orthogonal Frequency Division Multiplexing (OFDM) modulation. To enable the receiver to separate deterministically the preamble streams from each transmit antenna, a given set of subcarriers is attributed to each transmit antenna in the data block which is used as preamble. The receiver can extract the desired transmitted signal by using selectors. The problem is then reduced to a Single Input Multiple Output (SIMO) scheme. Our method consists firstly in separating the contributions of the different transmit antennas and secondly in a semi-blind SIMO channel estimation algorithm which uses SVD decomposition of a particular matrix. The scalar ambiguity of the estimated channel is removed by using a reduced number of pilots symbols.