Potential of Code Division Multiplexing (CDM) and Spatial Diversity in Future Broadband OFDM Systems

Code division multiplexing (CDM) is an efficient coding scheme without rate loss. The combination of robust and spectrally efficient orthogonal frequency division multiplexing (OFDM) with CDM results in an orthogonal frequency code division multiplexing (OFCDM) scheme. This paper investigates the potential of OFCDM for future broadband mobile radio schemes such as IMT-Advanced. The focus is on the performance analysis and comparison of OFDM and OFCDM. The investigations take into account channel coding and different spatial diversity and pre-coding schemes like cyclic delay diversity (CDD), spatial phase coding (SPC) and maximum ratio transmission (MRT). The results show that OFCDM outperforms OFDM with respect to bit error rate performance.