Performance of a frequency-domain OFDM-frame detector

A frequency-domain algorithm for orthogonal frequency-division multiplexing (OFDM)-frame detection is considered useful when the OFDM system is to operate in a known narrowband interference (NBI) channel, e.g., in a cognitive radio OFDM-based overlay system. While frame detection algorithm based on state-of-the-art time-domain correlation perform poorly in such a channel, we propose a frame detection algorithm based on energy detection in frequency domain. By exploiting the NBI band information obtained during sensing period, the proposed algorithm exhibits strong performance and outperforms other existing frequency-domain OFDM frame detection alternatives even at the signal-to-interference ratio (SIR) below 0 dB. Moreover, simulation results are confirmed by the analytical performance presented as a linear combination of the incomplete gamma function. The weight of each component is a function of the eigenvalues of the matrix associated with the detection metric and the number of summation is proportional to the number of non-zero eigenvalues of the matrix associated with the detection metric.