Antenna transmit diversity for wireless OFDM systems

We investigate several transmit-diversity techniques for wireless OFDM systems employing multiple antennas. We concentrate our investigation on methods that can be applied with few modifications to existing standards. Existing methods such as delay diversity, clustering and antenna interleaving are investigated and compared. A new approach that yields better results, consisting in applying different phase shifts on each subcarrier and on each antenna is also presented. Some practical implementation issues are also addressed.