Accurate FFT Processing Window Timing Detection Based on Maximum SIR Criterion in OFCDM Wireless Access

This paper proposes an accurate Fast Fourier Transform (FFT) window timing detection method based on the maximum signal-to-interference power ratio (SIR) criterion taking into account the received signal and inter-symbol interference power according to different detected FFT window timings in Orthogonal Frequency and Code Division Multiplexing (OFCDM) wireless access. In the proposed method, the SIR of the received signal is estimated using the desired signal power and inter-symbol interference power calculated based on the power delay profile, which is measured by the cross-correlation between the pilot symbol replica and the received signal. Furthermore, since the SIR is calculated only for the received path timing of the first path and those paths exceeding the guard interval duration, the computational complexity of the proposed method is low. Computer simulation results show that the proposed scheme reduces the required average received signal energy per symbol-to-noise power spectrum density ratio (E s /N 0 ) for achieving the average packet error rate of 10 -2 by approximately 1.0dB compared to the conventional method, which detects the forward path timing of the power delay profile (16QAM data modulation, six-path Rayleigh fading channel, and the maximum delay time of 3μsec (root mean squared (r.m.s.) delay spread of 0.86 μsec)).