Uplink pre-equalization for CC-CDMA systems under frequency selective fading

Owing to ideal correlation properties of complementary codes (CCs), a complementary coded code division multiple access (CC-CDMA) system outperforms traditional CDMA systems in terms of its interference resistance in both synchronous and asynchronous transmissions. This paper shows that a normal CC-CDMA system loses its interference-free feature over uplink frequency selective fading channels due to the fact that it is incapable to reconstruct ideal complementary cross-correlation at a receiver. This work proposes a uplink pre-equalized CC-CDMA system to resist multi-user interference and near-far effect over asynchronous frequency selective fading channels with perfect channel state information (CSI). Simulation results show the superiority of the proposed scheme in terms of its interference and near-far effect resistance. In addition, the impact of imperfect CSI is also studied in this work.