Equalized parallel interference cancellation for MC-CDMA multicode downlink transmissions

The system performance can be improved by interference cancellation. Due to the flat fading at each narrowband subcarrier and the inter-symbol interference resistance in MC-CDMA, the interference cancellation can be much simpler than that in WCDMA. In MC-CDMA multicode downlink transmissions, the user equipment has the knowledge of all the assigned spreading codes and it makes interference cancellation more feasible. In this paper an advanced equalized parallel interference cancellation (EPIC) receiver that equalizes the data estimates of previous two stages is proposed for MC-CDMA systems. By predefining the weights on power of two, the scaling and soft combination required by the proposed EPIC can be implemented by two summations and one bit-shift operation at each stage instead of one summation and two multiplications. The additional required complexity can be reduced into negligible and the proposed EPIC has approximately same complexity as the conventional scheme. The numerical results proved that the proposed receiver could significantly improve the system performance.