Combined Equalization and Channel Estimation for MC-IDMA Uplink Transmissions

Combined equalization based on combination of pre and post equalizations in a multicarrier interleave division multiple access (MC-IDMA) system, is described. The channel pre-equalization is constrained to keep transmitted power unchanged. Combined-equalization requires explicit channel state information (CSI) both at the mobile station and the base station. A low complexity uplink channel estimation strategy is developed at the base station for post-equalization. CSI at the mobile is made available for pre-equalization, by exploiting channel reciprocity between down and uplinks in time division duplex (TDD) mode. It is shown that system with combined equalization improves the bit error rate (BER) significantly as compared to the corresponding systems with pre and post equalizations alone.