Blind Channel Estimation based on Second Order Statistics for IFDMA

In this paper, the Interleaved Frequency Division Multiple Access (IFDMA) scheme is considered as a special case of Discrete Fourier Transform (DFT)-precoded Orthogonal Frequency Division Multiple Access (OFDMA) with interleaved subcarrier allocation. The redundancy that is characteristic for an IFDMA-signal is exploited in order to estimate the channel without pilot symbols and, thus, overcome the drawback of increased pilot symbol overhead that arises for IFDMA-systems. Two well-known blind channel estimation algorithms based on Second Order Statistics (SOS) are adapted to the application in an IFDMA-system and compared in terms of performance and convergence. Further on, the influence of multi-user transmission is illustrated for the two proposed blind channel estimation algorithms and the differences between multi-user uplink and downlink transmission in terms of channel estimation performance are investigated and emphasized by numerical results.