Orthogonal frequency division multiplexing with signal space diversity

People need more bandwidth to transmit voice, image and data. Orthogonal frequency division multiplexing (OFDM) is an alternative method of increasing data rate by providing parallel data transmission, no guard band and overlapping channels that provide spectral efficiency and has a good performance to combat frequency selective fading channels. Alamouti space time block coding (STBC) is the best alternative to provide diversity order of two for the two transmit antennas scenario without no channel state information at transmitter. Alamouti STBC does not have penalty in data rate, at two time instants two symbols sent by applying Alamouti encoding scheme. Signal space diversity (SSD) is an efficient technique that does not need extra bandwidth and energy and it can show performance improvement in the system. Using this technique for the physical layer security is being worked on nowadays. By using this technique at physical layer privacy of the communication system can be provided. In this study we incorporate three concepts which are OFDM, Alamouti STBC and SSD. Assumed that channel is frequency selective, by applying OFDM frequency selective fading channel is converted into flat fading channel. Theoretical and simulation results are provided for this incorporation.