Pilot aided STBC MC-CDMA using overloaded minimum TSC spreading codes

In this paper we investigate the performance of pilot aided space time block codes (STBC) multi-carrier code-division multiple-access (MC-CDMA) using overloaded minimum total squared correlation (TSC) spreading codes in indoor channel environment. Since we employed overloaded spreading codes, a number of MC-CDMA sub-channels in the scheme were not being used for data transmission. These empty sub-channels were utilized as comb-type pilot. For interpolating the channel characteristics of the other sub-channels we applied linear interpolator to maintain low complexity. The validity of the system is confirmed by comparing it with multiple-access STBC systems using the original MC-CDMA method with Walsh-Hadamard spreading codes, employing block-type pilot. All systems use equal gain combining (EGC) or maximum ratio combining (MRC) at the receiver. The simulation result shows that although the spreading codes of interest are not fully orthogonal codes, for a low number of users the system under investigation performed better than Walsh-Hadamard based STBC MC-CDMA using block-type pilot. This will be valuable for personal area network (PAN) where the number of users is typically low.