MC-CDMA system using unitary space-time modulation on down-link broadband mobile radio communication

摘要

In order to mitigate the effect of fading, the MC-CDMA system using Space-Time Block Code (STBC) has been studied. When MC-CDMA system has small number of users, the HER performance of the STBC/MC-CDMA system can be improved compared with MC-CDMA system with one transmit antenna. However, when the MC-CDMA system has large number of users, the HER performance of the STBC/MC-CDMA system is degraded compared with MC-CDMA system with one transmit antenna. This is because the STBC/MC-CDMA system enhances the effect of Multi-User Interference (MUI), and diversity gain obtained by employing STBC is reduced by the effect of MUI. To solve this problem, we propose the Unitary Space-Time Modulation (USTM)/MC-CDMA system. In the proposed system, the effect of MUI can be reduced in comparison with STBC/MC-CDMA by employing USTM. Consequently, we show that the proposed system can improve the HER performance compared with the STBC/MC-CDMA system when the MC-CDMA system has large number of users.