The performance of ML estimation of OFDM symbol time with and without correlation coefficient

In this paper, we show the results of the maximum likelihood (ML) estimation of orthogonal frequency-division multiplexing (OFDM) symbol time as to whether there is a correlation coefficient (CC) or not. The CC is related to signal to noise ratio (SNR), and SNR/(SNR+1), and approximately 1 at high SNR. However, because it is difficult to calculate a SNR in a receiver it is desirable to delete the CC. Thus, we investigate the performance of ML estimation with and without a CC at low SNR under various channel conditions such as additive white Gaussian noise (AWGN), frequency offset and multipath delays. In addition, we simulate the frame error rate (FER) with the same conditions. The results of simulation show that ML estimation with CC is superior to that without it with respect to mean square error (MSE) of OFDM symbol time and FER under all channel environments. However, the former is inferior to the latter in terms of the complexity of an OFDM receiver. Thus, there is trade-off between the performance and simplicity of it.