Briefly, according to embodiments of the invention, there is provided a wireless communication system and a method to receive by a base station from a first mobile station a first chain of data symbols transmitted by at least two antennas and having a first transmit diversity, to receive from a second mobile station a second chain of data symbols transmitted by at least two antennas and having a second transmit diversity. Both first and second chains of data symbols are transmitted from the first and second mobile stations at the same time, modulated according to an Orthogonal Frequency Division Multiplexing (OFDM) scheme and encoded by a space time block codes scheme.