Effects of Channel Estimation Error in the Presence of CFO on OFDM BER in Frequency-Selective Rayleigh Fading Channels

Abstract

<p class="MsoNormal" style="text-align: left; margin: 0cm 0cm 0pt; layout-grid-mode: char;" align="left"><span class="text"><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;">In this paper, we study the effects of channel estimation error on the bit-error-rate (BER) of orthogonal frequency division multiplexing (OFDM) systems in frequency-selective slowly Rayleigh fading channels. Due to the additive white Gaussian noise (AWGN) and the intercarrier interference (ICI) caused by the residual carrier frequency offset (CFO), the channel estimation based on the training symbols is not perfect. We characterize the performance degradation resulting from imperfect channel state information (CSI) by deriving the BER formulas for BPSK, QPSK, 16-QAM, and 64-QAM modulation schemes. The derived BER formulas contain no numerical integrals and can be evaluated easily and accurately. Simulation results validate the correctness of our theoretical analysis.</span></span><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;"></span></p&gt

Effect of polynomial interpolations on the estimation performance of a frequency‐selective Rayleigh channel in orthogonal frequency division multiplexing systems

“…In the same way for a 4-QAM, and as mentioned in [14], the decision domains are exactly symmetric with regard to the Q and I axes for the most significant bit and for the least significant bit, respectively. Thus, let us set C =+d +jd in the following developments.…”

“…Let us then set C = +1 in the following developments. The probability of detection error, noted is then given by In the same way for a 4‐QAM, and as mentioned in [14], the decision domains are exactly symmetric with regard to the Q and I axes for the most significant bit and for the least significant bit, respectively. Thus, let us set C = + d + j d in the following developments.…”

“…However, it does not provide any analytical expression of this BER lower bound. In [13,14], an analytical expression of the SER and BER for a transmission in presence of channel frequency offset and channel estimation errors is derived for different modulation schemes. However, the developments are made by using the probability density functions (PDFs) given in [15], in which the channel coefficients and the error of estimation are supposed to be uncorrelated, which is not the case in practice.…”

“…Consequently, the analysis of their performance limits is of great interest. To this end, we characterise the system performance not only with a BER value as usually in the literature [10,11,13,14], but also with the MSE of the channel estimation performed by means of the least-square (LS) method with interpolations, as it is done in [4,17] for the LMMSE. As in [10,11], we use a Rayleigh channel model with correlated interpolation errors, but we consider the transmission of an OFDM signal over a frequency-selective channel.…”

Theoretical bit error floor analysis of 16‐QAM OFDM signal with channel estimation using polynomial interpolation

“…Performance analyses of channel estimation errors have been undertaken for both single carrier systems [8,9] and OFDM modulation. In the latter case, the literature mainly deals with estimation errors that are due to the presence of channel frequency offset [10,11]. More recently, an analysis of the performance limits of pilot-aided OFDM systems using polynomial interpolations has been proposed in [12].…”