Effects of Virtual Carriers of Channel Estimation for OFDM Systems with Transmit Diversity

In this paper, the performance of discrete Fourier transform (DFT) based channel estimation (CE) for orthogonal frequency division multiplexing (OFDM) systems with transmit antenna diversity is analyzed. Conventional DFT-based CE suffers from the dispersive distortion of an estimated channel impulse response (CIR) due to the existence of virtual carriers (VCs). We analyze the mean squared error (MSE) performance and provide a concise expression which reveals the leakage effect due to VCs. Further, analytical expression for bit error rate (BER) with the effect of VCs is also derived. Simulation results illustrate the accuracy of the theoretical analysis.