Space frequency block codes and code division multiplexing in OFDM systems

The paper investigates different diversity concepts for OFDM systems. These are space frequency block codes (SFBCs) and code division multiplexing (CDM). The performances of both, and of combinations of both, are compared for coded OFDM systems in a Rayleigh fading channel. The applied SFBCs and CDM have in common that they have no rate loss and thus do not decrease the bandwidth efficiency of the system. While the SFBCs exploit space and frequency diversity, CDM exploits frequency and time diversity in OFDM systems. Additionally, the effects due to diversity gains by channel coding are taken into account in the investigations.