ABSTRACT
Orthogonal frequency division multiplexing (OFDM) has drawn much attention as a promising modulation scheme for the broadband wireless communications, and it is a strong candidate for the next-generation communication system. The application of the OFDM technique in a wideband and, as a result, frequency-selective wireless channel leads to the division of the initial signal bandwidth into several narrowbands and, as a result, flat fading subchannels. This chapter aims to discuss the presentation of several antenna transmit diversity techniques, which appear in the references. Special interest is given to schemes that concern selective fading channels because they dominate the broadband wireless technology. Space-time trellis codes (STTCs) are a type of space-time code used in multiple-antenna wireless communications. Real orthogonal designs of a full-rate and square code matrix can only be implemented for two, four, and eight transmit antennas. The chapter presents examples of STTCs for multiple transmitting and receiving antennas-OFDM systems found in the references.
