Single carrier frequency domain equalization with noise prediction for broadband wireless systems

Recent research has shown that single carrier frequency domain equalization (SC-FDE) is an attractive technology for broadband wireless communications because it does not have the problems of OFDM systems such as large peak-to-average ratio and the sensitivity to carrier frequency offsets. The FD-DFE structure, which combines a frequency domain feedforward equalizer and a time domain feedback filter, has been proposed to bring better performance than the linear ME scheme for severely distorted channels. However, this structure cannot be applied directly to coded systems because of the decision delays associated with these systems. In this paper, we propose a novel structure, which consists of a linear frequency domain equalizer and a time domain noise predictor. By using a simple block interleaver/deinterleaver pair to rearrange the order of the received signals prior to decoding, delayed reliable decisions can be used for feedback. By doing so, significant performance improvement over the conventional FD-LE and the FD-DFE schemes can be achieved in the proposed FDE-NP scheme. It is also demonstrated that the performance complexity tradeoff of the proposed scheme can be obtained by only changing the order of the noise predictor. This is in contrast to the conventional FD-DFE scheme where both the ME and the time domain feedback filter must be modified simultaneously.