A low complexity turbo receiver for data nulling superimposed pilots in OFDM

The main drawback of classical superimposed pilot (CSP) schemes is the deteriorated channel estimation performance due to interference from data. A recent proposal of a data nulling superimposed pilot (DNSP) scheme in orthogonal frequency division multiplexing (OFDM) was able to circumvent this drawback with interference-free pilot sub-carriers. However, the proposed suboptimal receiver for DNSP does not exploit the full potential of this scheme. In this paper, we propose a low complexity soft approximated minimum mean square error (MMSE) interference canceler (IC) to replace the suboptimal receiver of the literature. By exploiting the particularity of the interference structure of DNSP, a single diagonal matrix inversion is needed at the receiver. The results show that the bit error rate (BER) performance of the proposed receiver for DNSP outperforms that of the literature with a comparable complexity.