Alamouti Code to achieve diversity without channel knowledg at the transmitter It is assumed that system contains 2 transmit antennas and one receive antenna. At the transmitter the data of a two consecutive slots will be considered. At the odd time slots, the first antenna transmit symbol 1 (s1) and the second ones will transmit symbol 2 (s2) simoltaneously. At the even time slots the -s2* and s1* will be transmited from the first and second antenna respectively. Study "WIRELESS COMMUNICATIONS" by Goldsmith for further information.